--- /dev/null
+Technical Notes about PCRE
+--------------------------
+
+Many years ago I implemented some regular expression functions to an algorithm
+suggested by Martin Richards. These were not Unix-like in form, and were quite
+restricted in what they could do by comparison with Perl. The interesting part
+about the algorithm was that the amount of space required to hold the compiled
+form of an expression was known in advance. The code to apply an expression did
+not operate by backtracking, as the Henry Spencer and Perl code does, but
+instead checked all possibilities simultaneously by keeping a list of current
+states and checking all of them as it advanced through the subject string. (In
+the terminology of Jeffrey Friedl's book, it was a "DFA algorithm".) When the
+pattern was all used up, all remaining states were possible matches, and the
+one matching the longest subset of the subject string was chosen. This did not
+necessarily maximize the individual wild portions of the pattern, as is
+expected in Unix and Perl-style regular expressions.
+
+By contrast, the code originally written by Henry Spencer and subsequently
+heavily modified for Perl actually compiles the expression twice: once in a
+dummy mode in order to find out how much store will be needed, and then for
+real. The execution function operates by backtracking and maximizing (or,
+optionally, minimizing in Perl) the amount of the subject that matches
+individual wild portions of the pattern. This is an "NFA algorithm" in Friedl's
+terminology.
+
+For the set of functions that forms PCRE (which are unrelated to those
+mentioned above), I tried at first to invent an algorithm that used an amount
+of store bounded by a multiple of the number of characters in the pattern, to
+save on compiling time. However, because of the greater complexity in Perl
+regular expressions, I couldn't do this. In any case, a first pass through the
+pattern is needed, in order to find internal flag settings like (?i) at top
+level. So PCRE works by running a very degenerate first pass to calculate a
+maximum store size, and then a second pass to do the real compile - which may
+use a bit less than the predicted amount of store. The idea is that this is
+going to turn out faster because the first pass is degenerate and the second
+pass can just store stuff straight into the vector. It does make the compiling
+functions bigger, of course, but they have got quite big anyway to handle all
+the Perl stuff.
+
+The compiled form of a pattern is a vector of bytes, containing items of
+variable length. The first byte in an item is an opcode, and the length of the
+item is either implicit in the opcode or contained in the data bytes which
+follow it. A list of all the opcodes follows:
+
+Opcodes with no following data
+------------------------------
+
+These items are all just one byte long
+
+ OP_END end of pattern
+ OP_ANY match any character
+ OP_SOD match start of data: \A
+ OP_CIRC ^ (start of data, or after \n in multiline)
+ OP_NOT_WORD_BOUNDARY \W
+ OP_WORD_BOUNDARY \w
+ OP_NOT_DIGIT \D
+ OP_DIGIT \d
+ OP_NOT_WHITESPACE \S
+ OP_WHITESPACE \s
+ OP_NOT_WORDCHAR \W
+ OP_WORDCHAR \w
+ OP_EODN match end of data or \n at end: \Z
+ OP_EOD match end of data: \z
+ OP_DOLL $ (end of data, or before \n in multiline)
+ OP_RECURSE match the pattern recursively
+
+
+Repeating single characters
+---------------------------
+
+The common repeats (*, +, ?) when applied to a single character appear as
+two-byte items using the following opcodes:
+
+ OP_STAR
+ OP_MINSTAR
+ OP_PLUS
+ OP_MINPLUS
+ OP_QUERY
+ OP_MINQUERY
+
+Those with "MIN" in their name are the minimizing versions. Each is followed by
+the character that is to be repeated. Other repeats make use of
+
+ OP_UPTO
+ OP_MINUPTO
+ OP_EXACT
+
+which are followed by a two-byte count (most significant first) and the
+repeated character. OP_UPTO matches from 0 to the given number. A repeat with a
+non-zero minimum and a fixed maximum is coded as an OP_EXACT followed by an
+OP_UPTO (or OP_MINUPTO).
+
+
+Repeating character types
+-------------------------
+
+Repeats of things like \d are done exactly as for single characters, except
+that instead of a character, the opcode for the type is stored in the data
+byte. The opcodes are:
+
+ OP_TYPESTAR
+ OP_TYPEMINSTAR
+ OP_TYPEPLUS
+ OP_TYPEMINPLUS
+ OP_TYPEQUERY
+ OP_TYPEMINQUERY
+ OP_TYPEUPTO
+ OP_TYPEMINUPTO
+ OP_TYPEEXACT
+
+
+Matching a character string
+---------------------------
+
+The OP_CHARS opcode is followed by a one-byte count and then that number of
+characters. If there are more than 255 characters in sequence, successive
+instances of OP_CHARS are used.
+
+
+Character classes
+-----------------
+
+OP_CLASS is used for a character class, provided there are at least two
+characters in the class. If there is only one character, OP_CHARS is used for a
+positive class, and OP_NOT for a negative one (that is, for something like
+[^a]). Another set of repeating opcodes (OP_NOTSTAR etc.) are used for a
+repeated, negated, single-character class. The normal ones (OP_STAR etc.) are
+used for a repeated positive single-character class.
+
+OP_CLASS is followed by a 32-byte bit map containing a 1 bit for every
+character that is acceptable. The bits are counted from the least significant
+end of each byte.
+
+
+Back references
+---------------
+
+OP_REF is followed by a single byte containing the reference number.
+
+
+Repeating character classes and back references
+-----------------------------------------------
+
+Single-character classes are handled specially (see above). This applies to
+OP_CLASS and OP_REF. In both cases, the repeat information follows the base
+item. The matching code looks at the following opcode to see if it is one of
+
+ OP_CRSTAR
+ OP_CRMINSTAR
+ OP_CRPLUS
+ OP_CRMINPLUS
+ OP_CRQUERY
+ OP_CRMINQUERY
+ OP_CRRANGE
+ OP_CRMINRANGE
+
+All but the last two are just single-byte items. The others are followed by
+four bytes of data, comprising the minimum and maximum repeat counts.
+
+
+Brackets and alternation
+------------------------
+
+A pair of non-capturing (round) brackets is wrapped round each expression at
+compile time, so alternation always happens in the context of brackets.
+Non-capturing brackets use the opcode OP_BRA, while capturing brackets use
+OP_BRA+1, OP_BRA+2, etc. [Note for North Americans: "bracket" to some English
+speakers, including myself, can be round, square, curly, or pointy. Hence this
+usage.]
+
+A bracket opcode is followed by two bytes which give the offset to the next
+alternative OP_ALT or, if there aren't any branches, to the matching KET
+opcode. Each OP_ALT is followed by two bytes giving the offset to the next one,
+or to the KET opcode.
+
+OP_KET is used for subpatterns that do not repeat indefinitely, while
+OP_KETRMIN and OP_KETRMAX are used for indefinite repetitions, minimally or
+maximally respectively. All three are followed by two bytes giving (as a
+positive number) the offset back to the matching BRA opcode.
+
+If a subpattern is quantified such that it is permitted to match zero times, it
+is preceded by one of OP_BRAZERO or OP_BRAMINZERO. These are single-byte
+opcodes which tell the matcher that skipping this subpattern entirely is a
+valid branch.
+
+A subpattern with an indefinite maximum repetition is replicated in the
+compiled data its minimum number of times (or once with a BRAZERO if the
+minimum is zero), with the final copy terminating with a KETRMIN or KETRMAX as
+appropriate.
+
+A subpattern with a bounded maximum repetition is replicated in a nested
+fashion up to the maximum number of times, with BRAZERO or BRAMINZERO before
+each replication after the minimum, so that, for example, (abc){2,5} is
+compiled as (abc)(abc)((abc)((abc)(abc)?)?)?. The 200-bracket limit does not
+apply to these internally generated brackets.
+
+
+Assertions
+----------
+
+Forward assertions are just like other subpatterns, but starting with one of
+the opcodes OP_ASSERT or OP_ASSERT_NOT. Backward assertions use the opcodes
+OP_ASSERTBACK and OP_ASSERTBACK_NOT, and the first opcode inside the assertion
+is OP_REVERSE, followed by a two byte count of the number of characters to move
+back the pointer in the subject string. A separate count is present in each
+alternative of a lookbehind assertion, allowing them to have different fixed
+lengths.
+
+
+Once-only subpatterns
+---------------------
+
+These are also just like other subpatterns, but they start with the opcode
+OP_ONCE.
+
+
+Conditional subpatterns
+-----------------------
+
+These are like other subpatterns, but they start with the opcode OP_COND. If
+the condition is a back reference, this is stored at the start of the
+subpattern using the opcode OP_CREF followed by one byte containing the
+reference number. Otherwise, a conditional subpattern will always start with
+one of the assertions.
+
+
+Changing options
+----------------
+
+If any of the /i, /m, or /s options are changed within a parenthesized group,
+an OP_OPT opcode is compiled, followed by one byte containing the new settings
+of these flags. If there are several alternatives in a group, there is an
+occurrence of OP_OPT at the start of all those following the first options
+change, to set appropriate options for the start of the alternative.
+Immediately after the end of the group there is another such item to reset the
+flags to their previous values. Other changes of flag within the pattern can be
+handled entirely at compile time, and so do not cause anything to be put into
+the compiled data.
+
+
+Philip Hazel
+February 2000
--- /dev/null
+.TH PCRE 3
+.SH NAME
+pcre - Perl-compatible regular expressions.
+.SH SYNOPSIS
+.B #include <pcre.h>
+.PP
+.SM
+.br
+.B pcre *pcre_compile(const char *\fIpattern\fR, int \fIoptions\fR,
+.ti +5n
+.B const char **\fIerrptr\fR, int *\fIerroffset\fR,
+.ti +5n
+.B const unsigned char *\fItableptr\fR);
+.PP
+.br
+.B pcre_extra *pcre_study(const pcre *\fIcode\fR, int \fIoptions\fR,
+.ti +5n
+.B const char **\fIerrptr\fR);
+.PP
+.br
+.B int pcre_exec(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"
+.ti +5n
+.B "const char *\fIsubject\fR," int \fIlength\fR, int \fIstartoffset\fR,
+.ti +5n
+.B int \fIoptions\fR, int *\fIovector\fR, int \fIovecsize\fR);
+.PP
+.br
+.B int pcre_copy_substring(const char *\fIsubject\fR, int *\fIovector\fR,
+.ti +5n
+.B int \fIstringcount\fR, int \fIstringnumber\fR, char *\fIbuffer\fR,
+.ti +5n
+.B int \fIbuffersize\fR);
+.PP
+.br
+.B int pcre_get_substring(const char *\fIsubject\fR, int *\fIovector\fR,
+.ti +5n
+.B int \fIstringcount\fR, int \fIstringnumber\fR,
+.ti +5n
+.B const char **\fIstringptr\fR);
+.PP
+.br
+.B int pcre_get_substring_list(const char *\fIsubject\fR,
+.ti +5n
+.B int *\fIovector\fR, int \fIstringcount\fR, "const char ***\fIlistptr\fR);"
+.PP
+.br
+.B const unsigned char *pcre_maketables(void);
+.PP
+.br
+.B int pcre_fullinfo(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"
+.ti +5n
+.B int \fIwhat\fR, void *\fIwhere\fR);
+.PP
+.br
+.B int pcre_info(const pcre *\fIcode\fR, int *\fIoptptr\fR, int
+.B *\fIfirstcharptr\fR);
+.PP
+.br
+.B char *pcre_version(void);
+.PP
+.br
+.B void *(*pcre_malloc)(size_t);
+.PP
+.br
+.B void (*pcre_free)(void *);
+
+
+
+.SH DESCRIPTION
+The PCRE library is a set of functions that implement regular expression
+pattern matching using the same syntax and semantics as Perl 5, with just a few
+differences (see below). The current implementation corresponds to Perl 5.005,
+with some additional features from the Perl development release.
+
+PCRE has its own native API, which is described in this document. There is also
+a set of wrapper functions that correspond to the POSIX regular expression API.
+These are described in the \fBpcreposix\fR documentation.
+
+The native API function prototypes are defined in the header file \fBpcre.h\fR,
+and on Unix systems the library itself is called \fBlibpcre.a\fR, so can be
+accessed by adding \fB-lpcre\fR to the command for linking an application which
+calls it. The header file defines the macros PCRE_MAJOR and PCRE_MINOR to
+contain the major and minor release numbers for the library. Applications can
+use these to include support for different releases.
+
+The functions \fBpcre_compile()\fR, \fBpcre_study()\fR, and \fBpcre_exec()\fR
+are used for compiling and matching regular expressions, while
+\fBpcre_copy_substring()\fR, \fBpcre_get_substring()\fR, and
+\fBpcre_get_substring_list()\fR are convenience functions for extracting
+captured substrings from a matched subject string. The function
+\fBpcre_maketables()\fR is used (optionally) to build a set of character tables
+in the current locale for passing to \fBpcre_compile()\fR.
+
+The function \fBpcre_fullinfo()\fR is used to find out information about a
+compiled pattern; \fBpcre_info()\fR is an obsolete version which returns only
+some of the available information, but is retained for backwards compatibility.
+The function \fBpcre_version()\fR returns a pointer to a string containing the
+version of PCRE and its date of release.
+
+The global variables \fBpcre_malloc\fR and \fBpcre_free\fR initially contain
+the entry points of the standard \fBmalloc()\fR and \fBfree()\fR functions
+respectively. PCRE calls the memory management functions via these variables,
+so a calling program can replace them if it wishes to intercept the calls. This
+should be done before calling any PCRE functions.
+
+
+.SH MULTI-THREADING
+The PCRE functions can be used in multi-threading applications, with the
+proviso that the memory management functions pointed to by \fBpcre_malloc\fR
+and \fBpcre_free\fR are shared by all threads.
+
+The compiled form of a regular expression is not altered during matching, so
+the same compiled pattern can safely be used by several threads at once.
+
+
+.SH COMPILING A PATTERN
+The function \fBpcre_compile()\fR is called to compile a pattern into an
+internal form. The pattern is a C string terminated by a binary zero, and
+is passed in the argument \fIpattern\fR. A pointer to a single block of memory
+that is obtained via \fBpcre_malloc\fR is returned. This contains the
+compiled code and related data. The \fBpcre\fR type is defined for this for
+convenience, but in fact \fBpcre\fR is just a typedef for \fBvoid\fR, since the
+contents of the block are not externally defined. It is up to the caller to
+free the memory when it is no longer required.
+.PP
+The size of a compiled pattern is roughly proportional to the length of the
+pattern string, except that each character class (other than those containing
+just a single character, negated or not) requires 33 bytes, and repeat
+quantifiers with a minimum greater than one or a bounded maximum cause the
+relevant portions of the compiled pattern to be replicated.
+.PP
+The \fIoptions\fR argument contains independent bits that affect the
+compilation. It should be zero if no options are required. Some of the options,
+in particular, those that are compatible with Perl, can also be set and unset
+from within the pattern (see the detailed description of regular expressions
+below). For these options, the contents of the \fIoptions\fR argument specifies
+their initial settings at the start of compilation and execution. The
+PCRE_ANCHORED option can be set at the time of matching as well as at compile
+time.
+.PP
+If \fIerrptr\fR is NULL, \fBpcre_compile()\fR returns NULL immediately.
+Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fR returns
+NULL, and sets the variable pointed to by \fIerrptr\fR to point to a textual
+error message. The offset from the start of the pattern to the character where
+the error was discovered is placed in the variable pointed to by
+\fIerroffset\fR, which must not be NULL. If it is, an immediate error is given.
+.PP
+If the final argument, \fItableptr\fR, is NULL, PCRE uses a default set of
+character tables which are built when it is compiled, using the default C
+locale. Otherwise, \fItableptr\fR must be the result of a call to
+\fBpcre_maketables()\fR. See the section on locale support below.
+.PP
+The following option bits are defined in the header file:
+
+ PCRE_ANCHORED
+
+If this bit is set, the pattern is forced to be "anchored", that is, it is
+constrained to match only at the start of the string which is being searched
+(the "subject string"). This effect can also be achieved by appropriate
+constructs in the pattern itself, which is the only way to do it in Perl.
+
+ PCRE_CASELESS
+
+If this bit is set, letters in the pattern match both upper and lower case
+letters. It is equivalent to Perl's /i option.
+
+ PCRE_DOLLAR_ENDONLY
+
+If this bit is set, a dollar metacharacter in the pattern matches only at the
+end of the subject string. Without this option, a dollar also matches
+immediately before the final character if it is a newline (but not before any
+other newlines). The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is
+set. There is no equivalent to this option in Perl.
+
+ PCRE_DOTALL
+
+If this bit is set, a dot metacharater in the pattern matches all characters,
+including newlines. Without it, newlines are excluded. This option is
+equivalent to Perl's /s option. A negative class such as [^a] always matches a
+newline character, independent of the setting of this option.
+
+ PCRE_EXTENDED
+
+If this bit is set, whitespace data characters in the pattern are totally
+ignored except when escaped or inside a character class, and characters between
+an unescaped # outside a character class and the next newline character,
+inclusive, are also ignored. This is equivalent to Perl's /x option, and makes
+it possible to include comments inside complicated patterns. Note, however,
+that this applies only to data characters. Whitespace characters may never
+appear within special character sequences in a pattern, for example within the
+sequence (?( which introduces a conditional subpattern.
+
+ PCRE_EXTRA
+
+This option was invented in order to turn on additional functionality of PCRE
+that is incompatible with Perl, but it is currently of very little use. When
+set, any backslash in a pattern that is followed by a letter that has no
+special meaning causes an error, thus reserving these combinations for future
+expansion. By default, as in Perl, a backslash followed by a letter with no
+special meaning is treated as a literal. There are at present no other features
+controlled by this option. It can also be set by a (?X) option setting within a
+pattern.
+
+ PCRE_MULTILINE
+
+By default, PCRE treats the subject string as consisting of a single "line" of
+characters (even if it actually contains several newlines). The "start of line"
+metacharacter (^) matches only at the start of the string, while the "end of
+line" metacharacter ($) matches only at the end of the string, or before a
+terminating newline (unless PCRE_DOLLAR_ENDONLY is set). This is the same as
+Perl.
+
+When PCRE_MULTILINE it is set, the "start of line" and "end of line" constructs
+match immediately following or immediately before any newline in the subject
+string, respectively, as well as at the very start and end. This is equivalent
+to Perl's /m option. If there are no "\\n" characters in a subject string, or
+no occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no
+effect.
+
+ PCRE_UNGREEDY
+
+This option inverts the "greediness" of the quantifiers so that they are not
+greedy by default, but become greedy if followed by "?". It is not compatible
+with Perl. It can also be set by a (?U) option setting within the pattern.
+
+
+.SH STUDYING A PATTERN
+When a pattern is going to be used several times, it is worth spending more
+time analyzing it in order to speed up the time taken for matching. The
+function \fBpcre_study()\fR takes a pointer to a compiled pattern as its first
+argument, and returns a pointer to a \fBpcre_extra\fR block (another \fBvoid\fR
+typedef) containing additional information about the pattern; this can be
+passed to \fBpcre_exec()\fR. If no additional information is available, NULL
+is returned.
+
+The second argument contains option bits. At present, no options are defined
+for \fBpcre_study()\fR, and this argument should always be zero.
+
+The third argument for \fBpcre_study()\fR is a pointer to an error message. If
+studying succeeds (even if no data is returned), the variable it points to is
+set to NULL. Otherwise it points to a textual error message.
+
+At present, studying a pattern is useful only for non-anchored patterns that do
+not have a single fixed starting character. A bitmap of possible starting
+characters is created.
+
+
+.SH LOCALE SUPPORT
+PCRE handles caseless matching, and determines whether characters are letters,
+digits, or whatever, by reference to a set of tables. The library contains a
+default set of tables which is created in the default C locale when PCRE is
+compiled. This is used when the final argument of \fBpcre_compile()\fR is NULL,
+and is sufficient for many applications.
+
+An alternative set of tables can, however, be supplied. Such tables are built
+by calling the \fBpcre_maketables()\fR function, which has no arguments, in the
+relevant locale. The result can then be passed to \fBpcre_compile()\fR as often
+as necessary. For example, to build and use tables that are appropriate for the
+French locale (where accented characters with codes greater than 128 are
+treated as letters), the following code could be used:
+
+ setlocale(LC_CTYPE, "fr");
+ tables = pcre_maketables();
+ re = pcre_compile(..., tables);
+
+The tables are built in memory that is obtained via \fBpcre_malloc\fR. The
+pointer that is passed to \fBpcre_compile\fR is saved with the compiled
+pattern, and the same tables are used via this pointer by \fBpcre_study()\fR
+and \fBpcre_exec()\fR. Thus for any single pattern, compilation, studying and
+matching all happen in the same locale, but different patterns can be compiled
+in different locales. It is the caller's responsibility to ensure that the
+memory containing the tables remains available for as long as it is needed.
+
+
+.SH INFORMATION ABOUT A PATTERN
+The \fBpcre_fullinfo()\fR function returns information about a compiled
+pattern. It replaces the obsolete \fBpcre_info()\fR function, which is
+nevertheless retained for backwards compability (and is documented below).
+
+The first argument for \fBpcre_fullinfo()\fR is a pointer to the compiled
+pattern. The second argument is the result of \fBpcre_study()\fR, or NULL if
+the pattern was not studied. The third argument specifies which piece of
+information is required, while the fourth argument is a pointer to a variable
+to receive the data. The yield of the function is zero for success, or one of
+the following negative numbers:
+
+ PCRE_ERROR_NULL the argument \fIcode\fR was NULL
+ the argument \fIwhere\fR was NULL
+ PCRE_ERROR_BADMAGIC the "magic number" was not found
+ PCRE_ERROR_BADOPTION the value of \fIwhat\fR was invalid
+
+The possible values for the third argument are defined in \fBpcre.h\fR, and are
+as follows:
+
+ PCRE_INFO_OPTIONS
+
+Return a copy of the options with which the pattern was compiled. The fourth
+argument should point to au \fBunsigned long int\fR variable. These option bits
+are those specified in the call to \fBpcre_compile()\fR, modified by any
+top-level option settings within the pattern itself, and with the PCRE_ANCHORED
+bit forcibly set if the form of the pattern implies that it can match only at
+the start of a subject string.
+
+ PCRE_INFO_SIZE
+
+Return the size of the compiled pattern, that is, the value that was passed as
+the argument to \fBpcre_malloc()\fR when PCRE was getting memory in which to
+place the compiled data. The fourth argument should point to a \fBsize_t\fR
+variable.
+
+ PCRE_INFO_CAPTURECOUNT
+
+Return the number of capturing subpatterns in the pattern. The fourth argument
+should point to an \fbint\fR variable.
+
+ PCRE_INFO_BACKREFMAX
+
+Return the number of the highest back reference in the pattern. The fourth
+argument should point to an \fBint\fR variable. Zero is returned if there are
+no back references.
+
+ PCRE_INFO_FIRSTCHAR
+
+Return information about the first character of any matched string, for a
+non-anchored pattern. If there is a fixed first character, e.g. from a pattern
+such as (cat|cow|coyote), then it is returned in the integer pointed to by
+\fIwhere\fR. Otherwise, if either
+
+(a) the pattern was compiled with the PCRE_MULTILINE option, and every branch
+starts with "^", or
+
+(b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set
+(if it were set, the pattern would be anchored),
+
+then -1 is returned, indicating that the pattern matches only at the
+start of a subject string or after any "\\n" within the string. Otherwise -2 is
+returned. For anchored patterns, -2 is returned.
+
+ PCRE_INFO_FIRSTTABLE
+
+If the pattern was studied, and this resulted in the construction of a 256-bit
+table indicating a fixed set of characters for the first character in any
+matching string, a pointer to the table is returned. Otherwise NULL is
+returned. The fourth argument should point to an \fBunsigned char *\fR
+variable.
+
+ PCRE_INFO_LASTLITERAL
+
+For a non-anchored pattern, return the value of the rightmost literal character
+which must exist in any matched string, other than at its start. The fourth
+argument should point to an \fBint\fR variable. If there is no such character,
+or if the pattern is anchored, -1 is returned. For example, for the pattern
+/a\\d+z\\d+/ the returned value is 'z'.
+
+The \fBpcre_info()\fR function is now obsolete because its interface is too
+restrictive to return all the available data about a compiled pattern. New
+programs should use \fBpcre_fullinfo()\fR instead. The yield of
+\fBpcre_info()\fR is the number of capturing subpatterns, or one of the
+following negative numbers:
+
+ PCRE_ERROR_NULL the argument \fIcode\fR was NULL
+ PCRE_ERROR_BADMAGIC the "magic number" was not found
+
+If the \fIoptptr\fR argument is not NULL, a copy of the options with which the
+pattern was compiled is placed in the integer it points to (see
+PCRE_INFO_OPTIONS above).
+
+If the pattern is not anchored and the \fIfirstcharptr\fR argument is not NULL,
+it is used to pass back information about the first character of any matched
+string (see PCRE_INFO_FIRSTCHAR above).
+
+
+.SH MATCHING A PATTERN
+The function \fBpcre_exec()\fR is called to match a subject string against a
+pre-compiled pattern, which is passed in the \fIcode\fR argument. If the
+pattern has been studied, the result of the study should be passed in the
+\fIextra\fR argument. Otherwise this must be NULL.
+
+The PCRE_ANCHORED option can be passed in the \fIoptions\fR argument, whose
+unused bits must be zero. However, if a pattern was compiled with
+PCRE_ANCHORED, or turned out to be anchored by virtue of its contents, it
+cannot be made unachored at matching time.
+
+There are also three further options that can be set only at matching time:
+
+ PCRE_NOTBOL
+
+The first character of the string is not the beginning of a line, so the
+circumflex metacharacter should not match before it. Setting this without
+PCRE_MULTILINE (at compile time) causes circumflex never to match.
+
+ PCRE_NOTEOL
+
+The end of the string is not the end of a line, so the dollar metacharacter
+should not match it nor (except in multiline mode) a newline immediately before
+it. Setting this without PCRE_MULTILINE (at compile time) causes dollar never
+to match.
+
+ PCRE_NOTEMPTY
+
+An empty string is not considered to be a valid match if this option is set. If
+there are alternatives in the pattern, they are tried. If all the alternatives
+match the empty string, the entire match fails. For example, if the pattern
+
+ a?b?
+
+is applied to a string not beginning with "a" or "b", it matches the empty
+string at the start of the subject. With PCRE_NOTEMPTY set, this match is not
+valid, so PCRE searches further into the string for occurrences of "a" or "b".
+
+Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case
+of a pattern match of the empty string within its \fBsplit()\fR function, and
+when using the /g modifier. It is possible to emulate Perl's behaviour after
+matching a null string by first trying the match again at the same offset with
+PCRE_NOTEMPTY set, and then if that fails by advancing the starting offset (see
+below) and trying an ordinary match again.
+
+The subject string is passed as a pointer in \fIsubject\fR, a length in
+\fIlength\fR, and a starting offset in \fIstartoffset\fR. Unlike the pattern
+string, it may contain binary zero characters. When the starting offset is
+zero, the search for a match starts at the beginning of the subject, and this
+is by far the most common case.
+
+A non-zero starting offset is useful when searching for another match in the
+same subject by calling \fBpcre_exec()\fR again after a previous success.
+Setting \fIstartoffset\fR differs from just passing over a shortened string and
+setting PCRE_NOTBOL in the case of a pattern that begins with any kind of
+lookbehind. For example, consider the pattern
+
+ \\Biss\\B
+
+which finds occurrences of "iss" in the middle of words. (\\B matches only if
+the current position in the subject is not a word boundary.) When applied to
+the string "Mississipi" the first call to \fBpcre_exec()\fR finds the first
+occurrence. If \fBpcre_exec()\fR is called again with just the remainder of the
+subject, namely "issipi", it does not match, because \\B is always false at the
+start of the subject, which is deemed to be a word boundary. However, if
+\fBpcre_exec()\fR is passed the entire string again, but with \fIstartoffset\fR
+set to 4, it finds the second occurrence of "iss" because it is able to look
+behind the starting point to discover that it is preceded by a letter.
+
+If a non-zero starting offset is passed when the pattern is anchored, one
+attempt to match at the given offset is tried. This can only succeed if the
+pattern does not require the match to be at the start of the subject.
+
+In general, a pattern matches a certain portion of the subject, and in
+addition, further substrings from the subject may be picked out by parts of the
+pattern. Following the usage in Jeffrey Friedl's book, this is called
+"capturing" in what follows, and the phrase "capturing subpattern" is used for
+a fragment of a pattern that picks out a substring. PCRE supports several other
+kinds of parenthesized subpattern that do not cause substrings to be captured.
+
+Captured substrings are returned to the caller via a vector of integer offsets
+whose address is passed in \fIovector\fR. The number of elements in the vector
+is passed in \fIovecsize\fR. The first two-thirds of the vector is used to pass
+back captured substrings, each substring using a pair of integers. The
+remaining third of the vector is used as workspace by \fBpcre_exec()\fR while
+matching capturing subpatterns, and is not available for passing back
+information. The length passed in \fIovecsize\fR should always be a multiple of
+three. If it is not, it is rounded down.
+
+When a match has been successful, information about captured substrings is
+returned in pairs of integers, starting at the beginning of \fIovector\fR, and
+continuing up to two-thirds of its length at the most. The first element of a
+pair is set to the offset of the first character in a substring, and the second
+is set to the offset of the first character after the end of a substring. The
+first pair, \fIovector[0]\fR and \fIovector[1]\fR, identify the portion of the
+subject string matched by the entire pattern. The next pair is used for the
+first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fR
+is the number of pairs that have been set. If there are no capturing
+subpatterns, the return value from a successful match is 1, indicating that
+just the first pair of offsets has been set.
+
+Some convenience functions are provided for extracting the captured substrings
+as separate strings. These are described in the following section.
+
+It is possible for an capturing subpattern number \fIn+1\fR to match some
+part of the subject when subpattern \fIn\fR has not been used at all. For
+example, if the string "abc" is matched against the pattern (a|(z))(bc)
+subpatterns 1 and 3 are matched, but 2 is not. When this happens, both offset
+values corresponding to the unused subpattern are set to -1.
+
+If a capturing subpattern is matched repeatedly, it is the last portion of the
+string that it matched that gets returned.
+
+If the vector is too small to hold all the captured substrings, it is used as
+far as possible (up to two-thirds of its length), and the function returns a
+value of zero. In particular, if the substring offsets are not of interest,
+\fBpcre_exec()\fR may be called with \fIovector\fR passed as NULL and
+\fIovecsize\fR as zero. However, if the pattern contains back references and
+the \fIovector\fR isn't big enough to remember the related substrings, PCRE has
+to get additional memory for use during matching. Thus it is usually advisable
+to supply an \fIovector\fR.
+
+Note that \fBpcre_info()\fR can be used to find out how many capturing
+subpatterns there are in a compiled pattern. The smallest size for
+\fIovector\fR that will allow for \fIn\fR captured substrings in addition to
+the offsets of the substring matched by the whole pattern is (\fIn\fR+1)*3.
+
+If \fBpcre_exec()\fR fails, it returns a negative number. The following are
+defined in the header file:
+
+ PCRE_ERROR_NOMATCH (-1)
+
+The subject string did not match the pattern.
+
+ PCRE_ERROR_NULL (-2)
+
+Either \fIcode\fR or \fIsubject\fR was passed as NULL, or \fIovector\fR was
+NULL and \fIovecsize\fR was not zero.
+
+ PCRE_ERROR_BADOPTION (-3)
+
+An unrecognized bit was set in the \fIoptions\fR argument.
+
+ PCRE_ERROR_BADMAGIC (-4)
+
+PCRE stores a 4-byte "magic number" at the start of the compiled code, to catch
+the case when it is passed a junk pointer. This is the error it gives when the
+magic number isn't present.
+
+ PCRE_ERROR_UNKNOWN_NODE (-5)
+
+While running the pattern match, an unknown item was encountered in the
+compiled pattern. This error could be caused by a bug in PCRE or by overwriting
+of the compiled pattern.
+
+ PCRE_ERROR_NOMEMORY (-6)
+
+If a pattern contains back references, but the \fIovector\fR that is passed to
+\fBpcre_exec()\fR is not big enough to remember the referenced substrings, PCRE
+gets a block of memory at the start of matching to use for this purpose. If the
+call via \fBpcre_malloc()\fR fails, this error is given. The memory is freed at
+the end of matching.
+
+
+.SH EXTRACTING CAPTURED SUBSTRINGS
+Captured substrings can be accessed directly by using the offsets returned by
+\fBpcre_exec()\fR in \fIovector\fR. For convenience, the functions
+\fBpcre_copy_substring()\fR, \fBpcre_get_substring()\fR, and
+\fBpcre_get_substring_list()\fR are provided for extracting captured substrings
+as new, separate, zero-terminated strings. A substring that contains a binary
+zero is correctly extracted and has a further zero added on the end, but the
+result does not, of course, function as a C string.
+
+The first three arguments are the same for all three functions: \fIsubject\fR
+is the subject string which has just been successfully matched, \fIovector\fR
+is a pointer to the vector of integer offsets that was passed to
+\fBpcre_exec()\fR, and \fIstringcount\fR is the number of substrings that
+were captured by the match, including the substring that matched the entire
+regular expression. This is the value returned by \fBpcre_exec\fR if it
+is greater than zero. If \fBpcre_exec()\fR returned zero, indicating that it
+ran out of space in \fIovector\fR, then the value passed as
+\fIstringcount\fR should be the size of the vector divided by three.
+
+The functions \fBpcre_copy_substring()\fR and \fBpcre_get_substring()\fR
+extract a single substring, whose number is given as \fIstringnumber\fR. A
+value of zero extracts the substring that matched the entire pattern, while
+higher values extract the captured substrings. For \fBpcre_copy_substring()\fR,
+the string is placed in \fIbuffer\fR, whose length is given by
+\fIbuffersize\fR, while for \fBpcre_get_substring()\fR a new block of store is
+obtained via \fBpcre_malloc\fR, and its address is returned via
+\fIstringptr\fR. The yield of the function is the length of the string, not
+including the terminating zero, or one of
+
+ PCRE_ERROR_NOMEMORY (-6)
+
+The buffer was too small for \fBpcre_copy_substring()\fR, or the attempt to get
+memory failed for \fBpcre_get_substring()\fR.
+
+ PCRE_ERROR_NOSUBSTRING (-7)
+
+There is no substring whose number is \fIstringnumber\fR.
+
+The \fBpcre_get_substring_list()\fR function extracts all available substrings
+and builds a list of pointers to them. All this is done in a single block of
+memory which is obtained via \fBpcre_malloc\fR. The address of the memory block
+is returned via \fIlistptr\fR, which is also the start of the list of string
+pointers. The end of the list is marked by a NULL pointer. The yield of the
+function is zero if all went well, or
+
+ PCRE_ERROR_NOMEMORY (-6)
+
+if the attempt to get the memory block failed.
+
+When any of these functions encounter a substring that is unset, which can
+happen when capturing subpattern number \fIn+1\fR matches some part of the
+subject, but subpattern \fIn\fR has not been used at all, they return an empty
+string. This can be distinguished from a genuine zero-length substring by
+inspecting the appropriate offset in \fIovector\fR, which is negative for unset
+substrings.
+
+
+
+.SH LIMITATIONS
+There are some size limitations in PCRE but it is hoped that they will never in
+practice be relevant.
+The maximum length of a compiled pattern is 65539 (sic) bytes.
+All values in repeating quantifiers must be less than 65536.
+The maximum number of capturing subpatterns is 99.
+The maximum number of all parenthesized subpatterns, including capturing
+subpatterns, assertions, and other types of subpattern, is 200.
+
+The maximum length of a subject string is the largest positive number that an
+integer variable can hold. However, PCRE uses recursion to handle subpatterns
+and indefinite repetition. This means that the available stack space may limit
+the size of a subject string that can be processed by certain patterns.
+
+
+.SH DIFFERENCES FROM PERL
+The differences described here are with respect to Perl 5.005.
+
+1. By default, a whitespace character is any character that the C library
+function \fBisspace()\fR recognizes, though it is possible to compile PCRE with
+alternative character type tables. Normally \fBisspace()\fR matches space,
+formfeed, newline, carriage return, horizontal tab, and vertical tab. Perl 5
+no longer includes vertical tab in its set of whitespace characters. The \\v
+escape that was in the Perl documentation for a long time was never in fact
+recognized. However, the character itself was treated as whitespace at least
+up to 5.002. In 5.004 and 5.005 it does not match \\s.
+
+2. PCRE does not allow repeat quantifiers on lookahead assertions. Perl permits
+them, but they do not mean what you might think. For example, (?!a){3} does
+not assert that the next three characters are not "a". It just asserts that the
+next character is not "a" three times.
+
+3. Capturing subpatterns that occur inside negative lookahead assertions are
+counted, but their entries in the offsets vector are never set. Perl sets its
+numerical variables from any such patterns that are matched before the
+assertion fails to match something (thereby succeeding), but only if the
+negative lookahead assertion contains just one branch.
+
+4. Though binary zero characters are supported in the subject string, they are
+not allowed in a pattern string because it is passed as a normal C string,
+terminated by zero. The escape sequence "\\0" can be used in the pattern to
+represent a binary zero.
+
+5. The following Perl escape sequences are not supported: \\l, \\u, \\L, \\U,
+\\E, \\Q. In fact these are implemented by Perl's general string-handling and
+are not part of its pattern matching engine.
+
+6. The Perl \\G assertion is not supported as it is not relevant to single
+pattern matches.
+
+7. Fairly obviously, PCRE does not support the (?{code}) and (?p{code})
+constructions. However, there is some experimental support for recursive
+patterns using the non-Perl item (?R).
+
+8. There are at the time of writing some oddities in Perl 5.005_02 concerned
+with the settings of captured strings when part of a pattern is repeated. For
+example, matching "aba" against the pattern /^(a(b)?)+$/ sets $2 to the value
+"b", but matching "aabbaa" against /^(aa(bb)?)+$/ leaves $2 unset. However, if
+the pattern is changed to /^(aa(b(b))?)+$/ then $2 (and $3) get set.
+
+In Perl 5.004 $2 is set in both cases, and that is also true of PCRE. If in the
+future Perl changes to a consistent state that is different, PCRE may change to
+follow.
+
+9. Another as yet unresolved discrepancy is that in Perl 5.005_02 the pattern
+/^(a)?(?(1)a|b)+$/ matches the string "a", whereas in PCRE it does not.
+However, in both Perl and PCRE /^(a)?a/ matched against "a" leaves $1 unset.
+
+10. PCRE provides some extensions to the Perl regular expression facilities:
+
+(a) Although lookbehind assertions must match fixed length strings, each
+alternative branch of a lookbehind assertion can match a different length of
+string. Perl 5.005 requires them all to have the same length.
+
+(b) If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not set, the $ meta-
+character matches only at the very end of the string.
+
+(c) If PCRE_EXTRA is set, a backslash followed by a letter with no special
+meaning is faulted.
+
+(d) If PCRE_UNGREEDY is set, the greediness of the repetition quantifiers is
+inverted, that is, by default they are not greedy, but if followed by a
+question mark they are.
+
+(e) PCRE_ANCHORED can be used to force a pattern to be tried only at the start
+of the subject.
+
+(f) The PCRE_NOTBOL, PCRE_NOTEOL, and PCRE_NOTEMPTY options for
+\fBpcre_exec()\fR have no Perl equivalents.
+
+(g) The (?R) construct allows for recursive pattern matching (Perl 5.6 can do
+this using the (?p{code}) construct, which PCRE cannot of course support.)
+
+
+.SH REGULAR EXPRESSION DETAILS
+The syntax and semantics of the regular expressions supported by PCRE are
+described below. Regular expressions are also described in the Perl
+documentation and in a number of other books, some of which have copious
+examples. Jeffrey Friedl's "Mastering Regular Expressions", published by
+O'Reilly (ISBN 1-56592-257), covers them in great detail. The description
+here is intended as reference documentation.
+
+A regular expression is a pattern that is matched against a subject string from
+left to right. Most characters stand for themselves in a pattern, and match the
+corresponding characters in the subject. As a trivial example, the pattern
+
+ The quick brown fox
+
+matches a portion of a subject string that is identical to itself. The power of
+regular expressions comes from the ability to include alternatives and
+repetitions in the pattern. These are encoded in the pattern by the use of
+\fImeta-characters\fR, which do not stand for themselves but instead are
+interpreted in some special way.
+
+There are two different sets of meta-characters: those that are recognized
+anywhere in the pattern except within square brackets, and those that are
+recognized in square brackets. Outside square brackets, the meta-characters are
+as follows:
+
+ \\ general escape character with several uses
+ ^ assert start of subject (or line, in multiline mode)
+ $ assert end of subject (or line, in multiline mode)
+ . match any character except newline (by default)
+ [ start character class definition
+ | start of alternative branch
+ ( start subpattern
+ ) end subpattern
+ ? extends the meaning of (
+ also 0 or 1 quantifier
+ also quantifier minimizer
+ * 0 or more quantifier
+ + 1 or more quantifier
+ { start min/max quantifier
+
+Part of a pattern that is in square brackets is called a "character class". In
+a character class the only meta-characters are:
+
+ \\ general escape character
+ ^ negate the class, but only if the first character
+ - indicates character range
+ ] terminates the character class
+
+The following sections describe the use of each of the meta-characters.
+
+
+.SH BACKSLASH
+The backslash character has several uses. Firstly, if it is followed by a
+non-alphameric character, it takes away any special meaning that character may
+have. This use of backslash as an escape character applies both inside and
+outside character classes.
+
+For example, if you want to match a "*" character, you write "\\*" in the
+pattern. This applies whether or not the following character would otherwise be
+interpreted as a meta-character, so it is always safe to precede a
+non-alphameric with "\\" to specify that it stands for itself. In particular,
+if you want to match a backslash, you write "\\\\".
+
+If a pattern is compiled with the PCRE_EXTENDED option, whitespace in the
+pattern (other than in a character class) and characters between a "#" outside
+a character class and the next newline character are ignored. An escaping
+backslash can be used to include a whitespace or "#" character as part of the
+pattern.
+
+A second use of backslash provides a way of encoding non-printing characters
+in patterns in a visible manner. There is no restriction on the appearance of
+non-printing characters, apart from the binary zero that terminates a pattern,
+but when a pattern is being prepared by text editing, it is usually easier to
+use one of the following escape sequences than the binary character it
+represents:
+
+ \\a alarm, that is, the BEL character (hex 07)
+ \\cx "control-x", where x is any character
+ \\e escape (hex 1B)
+ \\f formfeed (hex 0C)
+ \\n newline (hex 0A)
+ \\r carriage return (hex 0D)
+ \\t tab (hex 09)
+ \\xhh character with hex code hh
+ \\ddd character with octal code ddd, or backreference
+
+The precise effect of "\\cx" is as follows: if "x" is a lower case letter, it
+is converted to upper case. Then bit 6 of the character (hex 40) is inverted.
+Thus "\\cz" becomes hex 1A, but "\\c{" becomes hex 3B, while "\\c;" becomes hex
+7B.
+
+After "\\x", up to two hexadecimal digits are read (letters can be in upper or
+lower case).
+
+After "\\0" up to two further octal digits are read. In both cases, if there
+are fewer than two digits, just those that are present are used. Thus the
+sequence "\\0\\x\\07" specifies two binary zeros followed by a BEL character.
+Make sure you supply two digits after the initial zero if the character that
+follows is itself an octal digit.
+
+The handling of a backslash followed by a digit other than 0 is complicated.
+Outside a character class, PCRE reads it and any following digits as a decimal
+number. If the number is less than 10, or if there have been at least that many
+previous capturing left parentheses in the expression, the entire sequence is
+taken as a \fIback reference\fR. A description of how this works is given
+later, following the discussion of parenthesized subpatterns.
+
+Inside a character class, or if the decimal number is greater than 9 and there
+have not been that many capturing subpatterns, PCRE re-reads up to three octal
+digits following the backslash, and generates a single byte from the least
+significant 8 bits of the value. Any subsequent digits stand for themselves.
+For example:
+
+ \\040 is another way of writing a space
+ \\40 is the same, provided there are fewer than 40
+ previous capturing subpatterns
+ \\7 is always a back reference
+ \\11 might be a back reference, or another way of
+ writing a tab
+ \\011 is always a tab
+ \\0113 is a tab followed by the character "3"
+ \\113 is the character with octal code 113 (since there
+ can be no more than 99 back references)
+ \\377 is a byte consisting entirely of 1 bits
+ \\81 is either a back reference, or a binary zero
+ followed by the two characters "8" and "1"
+
+Note that octal values of 100 or greater must not be introduced by a leading
+zero, because no more than three octal digits are ever read.
+
+All the sequences that define a single byte value can be used both inside and
+outside character classes. In addition, inside a character class, the sequence
+"\\b" is interpreted as the backspace character (hex 08). Outside a character
+class it has a different meaning (see below).
+
+The third use of backslash is for specifying generic character types:
+
+ \\d any decimal digit
+ \\D any character that is not a decimal digit
+ \\s any whitespace character
+ \\S any character that is not a whitespace character
+ \\w any "word" character
+ \\W any "non-word" character
+
+Each pair of escape sequences partitions the complete set of characters into
+two disjoint sets. Any given character matches one, and only one, of each pair.
+
+A "word" character is any letter or digit or the underscore character, that is,
+any character which can be part of a Perl "word". The definition of letters and
+digits is controlled by PCRE's character tables, and may vary if locale-
+specific matching is taking place (see "Locale support" above). For example, in
+the "fr" (French) locale, some character codes greater than 128 are used for
+accented letters, and these are matched by \\w.
+
+These character type sequences can appear both inside and outside character
+classes. They each match one character of the appropriate type. If the current
+matching point is at the end of the subject string, all of them fail, since
+there is no character to match.
+
+The fourth use of backslash is for certain simple assertions. An assertion
+specifies a condition that has to be met at a particular point in a match,
+without consuming any characters from the subject string. The use of
+subpatterns for more complicated assertions is described below. The backslashed
+assertions are
+
+ \\b word boundary
+ \\B not a word boundary
+ \\A start of subject (independent of multiline mode)
+ \\Z end of subject or newline at end (independent of multiline mode)
+ \\z end of subject (independent of multiline mode)
+
+These assertions may not appear in character classes (but note that "\\b" has a
+different meaning, namely the backspace character, inside a character class).
+
+A word boundary is a position in the subject string where the current character
+and the previous character do not both match \\w or \\W (i.e. one matches
+\\w and the other matches \\W), or the start or end of the string if the
+first or last character matches \\w, respectively.
+
+The \\A, \\Z, and \\z assertions differ from the traditional circumflex and
+dollar (described below) in that they only ever match at the very start and end
+of the subject string, whatever options are set. They are not affected by the
+PCRE_NOTBOL or PCRE_NOTEOL options. If the \fIstartoffset\fR argument of
+\fBpcre_exec()\fR is non-zero, \\A can never match. The difference between \\Z
+and \\z is that \\Z matches before a newline that is the last character of the
+string as well as at the end of the string, whereas \\z matches only at the
+end.
+
+
+.SH CIRCUMFLEX AND DOLLAR
+Outside a character class, in the default matching mode, the circumflex
+character is an assertion which is true only if the current matching point is
+at the start of the subject string. If the \fIstartoffset\fR argument of
+\fBpcre_exec()\fR is non-zero, circumflex can never match. Inside a character
+class, circumflex has an entirely different meaning (see below).
+
+Circumflex need not be the first character of the pattern if a number of
+alternatives are involved, but it should be the first thing in each alternative
+in which it appears if the pattern is ever to match that branch. If all
+possible alternatives start with a circumflex, that is, if the pattern is
+constrained to match only at the start of the subject, it is said to be an
+"anchored" pattern. (There are also other constructs that can cause a pattern
+to be anchored.)
+
+A dollar character is an assertion which is true only if the current matching
+point is at the end of the subject string, or immediately before a newline
+character that is the last character in the string (by default). Dollar need
+not be the last character of the pattern if a number of alternatives are
+involved, but it should be the last item in any branch in which it appears.
+Dollar has no special meaning in a character class.
+
+The meaning of dollar can be changed so that it matches only at the very end of
+the string, by setting the PCRE_DOLLAR_ENDONLY option at compile or matching
+time. This does not affect the \\Z assertion.
+
+The meanings of the circumflex and dollar characters are changed if the
+PCRE_MULTILINE option is set. When this is the case, they match immediately
+after and immediately before an internal "\\n" character, respectively, in
+addition to matching at the start and end of the subject string. For example,
+the pattern /^abc$/ matches the subject string "def\\nabc" in multiline mode,
+but not otherwise. Consequently, patterns that are anchored in single line mode
+because all branches start with "^" are not anchored in multiline mode, and a
+match for circumflex is possible when the \fIstartoffset\fR argument of
+\fBpcre_exec()\fR is non-zero. The PCRE_DOLLAR_ENDONLY option is ignored if
+PCRE_MULTILINE is set.
+
+Note that the sequences \\A, \\Z, and \\z can be used to match the start and
+end of the subject in both modes, and if all branches of a pattern start with
+\\A is it always anchored, whether PCRE_MULTILINE is set or not.
+
+
+.SH FULL STOP (PERIOD, DOT)
+Outside a character class, a dot in the pattern matches any one character in
+the subject, including a non-printing character, but not (by default) newline.
+If the PCRE_DOTALL option is set, then dots match newlines as well. The
+handling of dot is entirely independent of the handling of circumflex and
+dollar, the only relationship being that they both involve newline characters.
+Dot has no special meaning in a character class.
+
+
+.SH SQUARE BRACKETS
+An opening square bracket introduces a character class, terminated by a closing
+square bracket. A closing square bracket on its own is not special. If a
+closing square bracket is required as a member of the class, it should be the
+first data character in the class (after an initial circumflex, if present) or
+escaped with a backslash.
+
+A character class matches a single character in the subject; the character must
+be in the set of characters defined by the class, unless the first character in
+the class is a circumflex, in which case the subject character must not be in
+the set defined by the class. If a circumflex is actually required as a member
+of the class, ensure it is not the first character, or escape it with a
+backslash.
+
+For example, the character class [aeiou] matches any lower case vowel, while
+[^aeiou] matches any character that is not a lower case vowel. Note that a
+circumflex is just a convenient notation for specifying the characters which
+are in the class by enumerating those that are not. It is not an assertion: it
+still consumes a character from the subject string, and fails if the current
+pointer is at the end of the string.
+
+When caseless matching is set, any letters in a class represent both their
+upper case and lower case versions, so for example, a caseless [aeiou] matches
+"A" as well as "a", and a caseless [^aeiou] does not match "A", whereas a
+caseful version would.
+
+The newline character is never treated in any special way in character classes,
+whatever the setting of the PCRE_DOTALL or PCRE_MULTILINE options is. A class
+such as [^a] will always match a newline.
+
+The minus (hyphen) character can be used to specify a range of characters in a
+character class. For example, [d-m] matches any letter between d and m,
+inclusive. If a minus character is required in a class, it must be escaped with
+a backslash or appear in a position where it cannot be interpreted as
+indicating a range, typically as the first or last character in the class.
+
+It is not possible to have the literal character "]" as the end character of a
+range. A pattern such as [W-]46] is interpreted as a class of two characters
+("W" and "-") followed by a literal string "46]", so it would match "W46]" or
+"-46]". However, if the "]" is escaped with a backslash it is interpreted as
+the end of range, so [W-\\]46] is interpreted as a single class containing a
+range followed by two separate characters. The octal or hexadecimal
+representation of "]" can also be used to end a range.
+
+Ranges operate in ASCII collating sequence. They can also be used for
+characters specified numerically, for example [\\000-\\037]. If a range that
+includes letters is used when caseless matching is set, it matches the letters
+in either case. For example, [W-c] is equivalent to [][\\^_`wxyzabc], matched
+caselessly, and if character tables for the "fr" locale are in use,
+[\\xc8-\\xcb] matches accented E characters in both cases.
+
+The character types \\d, \\D, \\s, \\S, \\w, and \\W may also appear in a
+character class, and add the characters that they match to the class. For
+example, [\\dABCDEF] matches any hexadecimal digit. A circumflex can
+conveniently be used with the upper case character types to specify a more
+restricted set of characters than the matching lower case type. For example,
+the class [^\\W_] matches any letter or digit, but not underscore.
+
+All non-alphameric characters other than \\, -, ^ (at the start) and the
+terminating ] are non-special in character classes, but it does no harm if they
+are escaped.
+
+
+.SH POSIX CHARACTER CLASSES
+Perl 5.6 (not yet released at the time of writing) is going to support the
+POSIX notation for character classes, which uses names enclosed by [: and :]
+within the enclosing square brackets. PCRE supports this notation. For example,
+
+ [01[:alpha:]%]
+
+matches "0", "1", any alphabetic character, or "%". The supported class names
+are
+
+ alnum letters and digits
+ alpha letters
+ ascii character codes 0 - 127
+ cntrl control characters
+ digit decimal digits (same as \\d)
+ graph printing characters, excluding space
+ lower lower case letters
+ print printing characters, including space
+ punct printing characters, excluding letters and digits
+ space white space (same as \\s)
+ upper upper case letters
+ word "word" characters (same as \\w)
+ xdigit hexadecimal digits
+
+The names "ascii" and "word" are Perl extensions. Another Perl extension is
+negation, which is indicated by a ^ character after the colon. For example,
+
+ [12[:^digit:]]
+
+matches "1", "2", or any non-digit. PCRE (and Perl) also recogize the POSIX
+syntax [.ch.] and [=ch=] where "ch" is a "collating element", but these are not
+supported, and an error is given if they are encountered.
+
+
+.SH VERTICAL BAR
+Vertical bar characters are used to separate alternative patterns. For example,
+the pattern
+
+ gilbert|sullivan
+
+matches either "gilbert" or "sullivan". Any number of alternatives may appear,
+and an empty alternative is permitted (matching the empty string).
+The matching process tries each alternative in turn, from left to right,
+and the first one that succeeds is used. If the alternatives are within a
+subpattern (defined below), "succeeds" means matching the rest of the main
+pattern as well as the alternative in the subpattern.
+
+
+.SH INTERNAL OPTION SETTING
+The settings of PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, and PCRE_EXTENDED
+can be changed from within the pattern by a sequence of Perl option letters
+enclosed between "(?" and ")". The option letters are
+
+ i for PCRE_CASELESS
+ m for PCRE_MULTILINE
+ s for PCRE_DOTALL
+ x for PCRE_EXTENDED
+
+For example, (?im) sets caseless, multiline matching. It is also possible to
+unset these options by preceding the letter with a hyphen, and a combined
+setting and unsetting such as (?im-sx), which sets PCRE_CASELESS and
+PCRE_MULTILINE while unsetting PCRE_DOTALL and PCRE_EXTENDED, is also
+permitted. If a letter appears both before and after the hyphen, the option is
+unset.
+
+The scope of these option changes depends on where in the pattern the setting
+occurs. For settings that are outside any subpattern (defined below), the
+effect is the same as if the options were set or unset at the start of
+matching. The following patterns all behave in exactly the same way:
+
+ (?i)abc
+ a(?i)bc
+ ab(?i)c
+ abc(?i)
+
+which in turn is the same as compiling the pattern abc with PCRE_CASELESS set.
+In other words, such "top level" settings apply to the whole pattern (unless
+there are other changes inside subpatterns). If there is more than one setting
+of the same option at top level, the rightmost setting is used.
+
+If an option change occurs inside a subpattern, the effect is different. This
+is a change of behaviour in Perl 5.005. An option change inside a subpattern
+affects only that part of the subpattern that follows it, so
+
+ (a(?i)b)c
+
+matches abc and aBc and no other strings (assuming PCRE_CASELESS is not used).
+By this means, options can be made to have different settings in different
+parts of the pattern. Any changes made in one alternative do carry on
+into subsequent branches within the same subpattern. For example,
+
+ (a(?i)b|c)
+
+matches "ab", "aB", "c", and "C", even though when matching "C" the first
+branch is abandoned before the option setting. This is because the effects of
+option settings happen at compile time. There would be some very weird
+behaviour otherwise.
+
+The PCRE-specific options PCRE_UNGREEDY and PCRE_EXTRA can be changed in the
+same way as the Perl-compatible options by using the characters U and X
+respectively. The (?X) flag setting is special in that it must always occur
+earlier in the pattern than any of the additional features it turns on, even
+when it is at top level. It is best put at the start.
+
+
+.SH SUBPATTERNS
+Subpatterns are delimited by parentheses (round brackets), which can be nested.
+Marking part of a pattern as a subpattern does two things:
+
+1. It localizes a set of alternatives. For example, the pattern
+
+ cat(aract|erpillar|)
+
+matches one of the words "cat", "cataract", or "caterpillar". Without the
+parentheses, it would match "cataract", "erpillar" or the empty string.
+
+2. It sets up the subpattern as a capturing subpattern (as defined above).
+When the whole pattern matches, that portion of the subject string that matched
+the subpattern is passed back to the caller via the \fIovector\fR argument of
+\fBpcre_exec()\fR. Opening parentheses are counted from left to right (starting
+from 1) to obtain the numbers of the capturing subpatterns.
+
+For example, if the string "the red king" is matched against the pattern
+
+ the ((red|white) (king|queen))
+
+the captured substrings are "red king", "red", and "king", and are numbered 1,
+2, and 3.
+
+The fact that plain parentheses fulfil two functions is not always helpful.
+There are often times when a grouping subpattern is required without a
+capturing requirement. If an opening parenthesis is followed by "?:", the
+subpattern does not do any capturing, and is not counted when computing the
+number of any subsequent capturing subpatterns. For example, if the string "the
+white queen" is matched against the pattern
+
+ the ((?:red|white) (king|queen))
+
+the captured substrings are "white queen" and "queen", and are numbered 1 and
+2. The maximum number of captured substrings is 99, and the maximum number of
+all subpatterns, both capturing and non-capturing, is 200.
+
+As a convenient shorthand, if any option settings are required at the start of
+a non-capturing subpattern, the option letters may appear between the "?" and
+the ":". Thus the two patterns
+
+ (?i:saturday|sunday)
+ (?:(?i)saturday|sunday)
+
+match exactly the same set of strings. Because alternative branches are tried
+from left to right, and options are not reset until the end of the subpattern
+is reached, an option setting in one branch does affect subsequent branches, so
+the above patterns match "SUNDAY" as well as "Saturday".
+
+
+.SH REPETITION
+Repetition is specified by quantifiers, which can follow any of the following
+items:
+
+ a single character, possibly escaped
+ the . metacharacter
+ a character class
+ a back reference (see next section)
+ a parenthesized subpattern (unless it is an assertion - see below)
+
+The general repetition quantifier specifies a minimum and maximum number of
+permitted matches, by giving the two numbers in curly brackets (braces),
+separated by a comma. The numbers must be less than 65536, and the first must
+be less than or equal to the second. For example:
+
+ z{2,4}
+
+matches "zz", "zzz", or "zzzz". A closing brace on its own is not a special
+character. If the second number is omitted, but the comma is present, there is
+no upper limit; if the second number and the comma are both omitted, the
+quantifier specifies an exact number of required matches. Thus
+
+ [aeiou]{3,}
+
+matches at least 3 successive vowels, but may match many more, while
+
+ \\d{8}
+
+matches exactly 8 digits. An opening curly bracket that appears in a position
+where a quantifier is not allowed, or one that does not match the syntax of a
+quantifier, is taken as a literal character. For example, {,6} is not a
+quantifier, but a literal string of four characters.
+
+The quantifier {0} is permitted, causing the expression to behave as if the
+previous item and the quantifier were not present.
+
+For convenience (and historical compatibility) the three most common
+quantifiers have single-character abbreviations:
+
+ * is equivalent to {0,}
+ + is equivalent to {1,}
+ ? is equivalent to {0,1}
+
+It is possible to construct infinite loops by following a subpattern that can
+match no characters with a quantifier that has no upper limit, for example:
+
+ (a?)*
+
+Earlier versions of Perl and PCRE used to give an error at compile time for
+such patterns. However, because there are cases where this can be useful, such
+patterns are now accepted, but if any repetition of the subpattern does in fact
+match no characters, the loop is forcibly broken.
+
+By default, the quantifiers are "greedy", that is, they match as much as
+possible (up to the maximum number of permitted times), without causing the
+rest of the pattern to fail. The classic example of where this gives problems
+is in trying to match comments in C programs. These appear between the
+sequences /* and */ and within the sequence, individual * and / characters may
+appear. An attempt to match C comments by applying the pattern
+
+ /\\*.*\\*/
+
+to the string
+
+ /* first command */ not comment /* second comment */
+
+fails, because it matches the entire string due to the greediness of the .*
+item.
+
+However, if a quantifier is followed by a question mark, then it ceases to be
+greedy, and instead matches the minimum number of times possible, so the
+pattern
+
+ /\\*.*?\\*/
+
+does the right thing with the C comments. The meaning of the various
+quantifiers is not otherwise changed, just the preferred number of matches.
+Do not confuse this use of question mark with its use as a quantifier in its
+own right. Because it has two uses, it can sometimes appear doubled, as in
+
+ \\d??\\d
+
+which matches one digit by preference, but can match two if that is the only
+way the rest of the pattern matches.
+
+If the PCRE_UNGREEDY option is set (an option which is not available in Perl)
+then the quantifiers are not greedy by default, but individual ones can be made
+greedy by following them with a question mark. In other words, it inverts the
+default behaviour.
+
+When a parenthesized subpattern is quantified with a minimum repeat count that
+is greater than 1 or with a limited maximum, more store is required for the
+compiled pattern, in proportion to the size of the minimum or maximum.
+
+If a pattern starts with .* or .{0,} and the PCRE_DOTALL option (equivalent
+to Perl's /s) is set, thus allowing the . to match newlines, then the pattern
+is implicitly anchored, because whatever follows will be tried against every
+character position in the subject string, so there is no point in retrying the
+overall match at any position after the first. PCRE treats such a pattern as
+though it were preceded by \\A. In cases where it is known that the subject
+string contains no newlines, it is worth setting PCRE_DOTALL when the pattern
+begins with .* in order to obtain this optimization, or alternatively using ^
+to indicate anchoring explicitly.
+
+When a capturing subpattern is repeated, the value captured is the substring
+that matched the final iteration. For example, after
+
+ (tweedle[dume]{3}\\s*)+
+
+has matched "tweedledum tweedledee" the value of the captured substring is
+"tweedledee". However, if there are nested capturing subpatterns, the
+corresponding captured values may have been set in previous iterations. For
+example, after
+
+ /(a|(b))+/
+
+matches "aba" the value of the second captured substring is "b".
+
+
+.SH BACK REFERENCES
+Outside a character class, a backslash followed by a digit greater than 0 (and
+possibly further digits) is a back reference to a capturing subpattern earlier
+(i.e. to its left) in the pattern, provided there have been that many previous
+capturing left parentheses.
+
+However, if the decimal number following the backslash is less than 10, it is
+always taken as a back reference, and causes an error only if there are not
+that many capturing left parentheses in the entire pattern. In other words, the
+parentheses that are referenced need not be to the left of the reference for
+numbers less than 10. See the section entitled "Backslash" above for further
+details of the handling of digits following a backslash.
+
+A back reference matches whatever actually matched the capturing subpattern in
+the current subject string, rather than anything matching the subpattern
+itself. So the pattern
+
+ (sens|respons)e and \\1ibility
+
+matches "sense and sensibility" and "response and responsibility", but not
+"sense and responsibility". If caseful matching is in force at the time of the
+back reference, then the case of letters is relevant. For example,
+
+ ((?i)rah)\\s+\\1
+
+matches "rah rah" and "RAH RAH", but not "RAH rah", even though the original
+capturing subpattern is matched caselessly.
+
+There may be more than one back reference to the same subpattern. If a
+subpattern has not actually been used in a particular match, then any back
+references to it always fail. For example, the pattern
+
+ (a|(bc))\\2
+
+always fails if it starts to match "a" rather than "bc". Because there may be
+up to 99 back references, all digits following the backslash are taken
+as part of a potential back reference number. If the pattern continues with a
+digit character, then some delimiter must be used to terminate the back
+reference. If the PCRE_EXTENDED option is set, this can be whitespace.
+Otherwise an empty comment can be used.
+
+A back reference that occurs inside the parentheses to which it refers fails
+when the subpattern is first used, so, for example, (a\\1) never matches.
+However, such references can be useful inside repeated subpatterns. For
+example, the pattern
+
+ (a|b\\1)+
+
+matches any number of "a"s and also "aba", "ababaa" etc. At each iteration of
+the subpattern, the back reference matches the character string corresponding
+to the previous iteration. In order for this to work, the pattern must be such
+that the first iteration does not need to match the back reference. This can be
+done using alternation, as in the example above, or by a quantifier with a
+minimum of zero.
+
+
+.SH ASSERTIONS
+An assertion is a test on the characters following or preceding the current
+matching point that does not actually consume any characters. The simple
+assertions coded as \\b, \\B, \\A, \\Z, \\z, ^ and $ are described above. More
+complicated assertions are coded as subpatterns. There are two kinds: those
+that look ahead of the current position in the subject string, and those that
+look behind it.
+
+An assertion subpattern is matched in the normal way, except that it does not
+cause the current matching position to be changed. Lookahead assertions start
+with (?= for positive assertions and (?! for negative assertions. For example,
+
+ \\w+(?=;)
+
+matches a word followed by a semicolon, but does not include the semicolon in
+the match, and
+
+ foo(?!bar)
+
+matches any occurrence of "foo" that is not followed by "bar". Note that the
+apparently similar pattern
+
+ (?!foo)bar
+
+does not find an occurrence of "bar" that is preceded by something other than
+"foo"; it finds any occurrence of "bar" whatsoever, because the assertion
+(?!foo) is always true when the next three characters are "bar". A
+lookbehind assertion is needed to achieve this effect.
+
+Lookbehind assertions start with (?<= for positive assertions and (?<! for
+negative assertions. For example,
+
+ (?<!foo)bar
+
+does find an occurrence of "bar" that is not preceded by "foo". The contents of
+a lookbehind assertion are restricted such that all the strings it matches must
+have a fixed length. However, if there are several alternatives, they do not
+all have to have the same fixed length. Thus
+
+ (?<=bullock|donkey)
+
+is permitted, but
+
+ (?<!dogs?|cats?)
+
+causes an error at compile time. Branches that match different length strings
+are permitted only at the top level of a lookbehind assertion. This is an
+extension compared with Perl 5.005, which requires all branches to match the
+same length of string. An assertion such as
+
+ (?<=ab(c|de))
+
+is not permitted, because its single top-level branch can match two different
+lengths, but it is acceptable if rewritten to use two top-level branches:
+
+ (?<=abc|abde)
+
+The implementation of lookbehind assertions is, for each alternative, to
+temporarily move the current position back by the fixed width and then try to
+match. If there are insufficient characters before the current position, the
+match is deemed to fail. Lookbehinds in conjunction with once-only subpatterns
+can be particularly useful for matching at the ends of strings; an example is
+given at the end of the section on once-only subpatterns.
+
+Several assertions (of any sort) may occur in succession. For example,
+
+ (?<=\\d{3})(?<!999)foo
+
+matches "foo" preceded by three digits that are not "999". Notice that each of
+the assertions is applied independently at the same point in the subject
+string. First there is a check that the previous three characters are all
+digits, then there is a check that the same three characters are not "999".
+This pattern does \fInot\fR match "foo" preceded by six characters, the first
+of which are digits and the last three of which are not "999". For example, it
+doesn't match "123abcfoo". A pattern to do that is
+
+ (?<=\\d{3}...)(?<!999)foo
+
+This time the first assertion looks at the preceding six characters, checking
+that the first three are digits, and then the second assertion checks that the
+preceding three characters are not "999".
+
+Assertions can be nested in any combination. For example,
+
+ (?<=(?<!foo)bar)baz
+
+matches an occurrence of "baz" that is preceded by "bar" which in turn is not
+preceded by "foo", while
+
+ (?<=\\d{3}(?!999)...)foo
+
+is another pattern which matches "foo" preceded by three digits and any three
+characters that are not "999".
+
+Assertion subpatterns are not capturing subpatterns, and may not be repeated,
+because it makes no sense to assert the same thing several times. If any kind
+of assertion contains capturing subpatterns within it, these are counted for
+the purposes of numbering the capturing subpatterns in the whole pattern.
+However, substring capturing is carried out only for positive assertions,
+because it does not make sense for negative assertions.
+
+Assertions count towards the maximum of 200 parenthesized subpatterns.
+
+
+.SH ONCE-ONLY SUBPATTERNS
+With both maximizing and minimizing repetition, failure of what follows
+normally causes the repeated item to be re-evaluated to see if a different
+number of repeats allows the rest of the pattern to match. Sometimes it is
+useful to prevent this, either to change the nature of the match, or to cause
+it fail earlier than it otherwise might, when the author of the pattern knows
+there is no point in carrying on.
+
+Consider, for example, the pattern \\d+foo when applied to the subject line
+
+ 123456bar
+
+After matching all 6 digits and then failing to match "foo", the normal
+action of the matcher is to try again with only 5 digits matching the \\d+
+item, and then with 4, and so on, before ultimately failing. Once-only
+subpatterns provide the means for specifying that once a portion of the pattern
+has matched, it is not to be re-evaluated in this way, so the matcher would
+give up immediately on failing to match "foo" the first time. The notation is
+another kind of special parenthesis, starting with (?> as in this example:
+
+ (?>\\d+)bar
+
+This kind of parenthesis "locks up" the part of the pattern it contains once
+it has matched, and a failure further into the pattern is prevented from
+backtracking into it. Backtracking past it to previous items, however, works as
+normal.
+
+An alternative description is that a subpattern of this type matches the string
+of characters that an identical standalone pattern would match, if anchored at
+the current point in the subject string.
+
+Once-only subpatterns are not capturing subpatterns. Simple cases such as the
+above example can be thought of as a maximizing repeat that must swallow
+everything it can. So, while both \\d+ and \\d+? are prepared to adjust the
+number of digits they match in order to make the rest of the pattern match,
+(?>\\d+) can only match an entire sequence of digits.
+
+This construction can of course contain arbitrarily complicated subpatterns,
+and it can be nested.
+
+Once-only subpatterns can be used in conjunction with lookbehind assertions to
+specify efficient matching at the end of the subject string. Consider a simple
+pattern such as
+
+ abcd$
+
+when applied to a long string which does not match. Because matching proceeds
+from left to right, PCRE will look for each "a" in the subject and then see if
+what follows matches the rest of the pattern. If the pattern is specified as
+
+ ^.*abcd$
+
+then the initial .* matches the entire string at first, but when this fails
+(because there is no following "a"), it backtracks to match all but the last
+character, then all but the last two characters, and so on. Once again the
+search for "a" covers the entire string, from right to left, so we are no
+better off. However, if the pattern is written as
+
+ ^(?>.*)(?<=abcd)
+
+then there can be no backtracking for the .* item; it can match only the entire
+string. The subsequent lookbehind assertion does a single test on the last four
+characters. If it fails, the match fails immediately. For long strings, this
+approach makes a significant difference to the processing time.
+
+When a pattern contains an unlimited repeat inside a subpattern that can itself
+be repeated an unlimited number of times, the use of a once-only subpattern is
+the only way to avoid some failing matches taking a very long time indeed.
+The pattern
+
+ (\\D+|<\\d+>)*[!?]
+
+matches an unlimited number of substrings that either consist of non-digits, or
+digits enclosed in <>, followed by either ! or ?. When it matches, it runs
+quickly. However, if it is applied to
+
+ aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+
+it takes a long time before reporting failure. This is because the string can
+be divided between the two repeats in a large number of ways, and all have to
+be tried. (The example used [!?] rather than a single character at the end,
+because both PCRE and Perl have an optimization that allows for fast failure
+when a single character is used. They remember the last single character that
+is required for a match, and fail early if it is not present in the string.)
+If the pattern is changed to
+
+ ((?>\\D+)|<\\d+>)*[!?]
+
+sequences of non-digits cannot be broken, and failure happens quickly.
+
+
+.SH CONDITIONAL SUBPATTERNS
+It is possible to cause the matching process to obey a subpattern
+conditionally or to choose between two alternative subpatterns, depending on
+the result of an assertion, or whether a previous capturing subpattern matched
+or not. The two possible forms of conditional subpattern are
+
+ (?(condition)yes-pattern)
+ (?(condition)yes-pattern|no-pattern)
+
+If the condition is satisfied, the yes-pattern is used; otherwise the
+no-pattern (if present) is used. If there are more than two alternatives in the
+subpattern, a compile-time error occurs.
+
+There are two kinds of condition. If the text between the parentheses consists
+of a sequence of digits, then the condition is satisfied if the capturing
+subpattern of that number has previously matched. Consider the following
+pattern, which contains non-significant white space to make it more readable
+(assume the PCRE_EXTENDED option) and to divide it into three parts for ease
+of discussion:
+
+ ( \\( )? [^()]+ (?(1) \\) )
+
+The first part matches an optional opening parenthesis, and if that
+character is present, sets it as the first captured substring. The second part
+matches one or more characters that are not parentheses. The third part is a
+conditional subpattern that tests whether the first set of parentheses matched
+or not. If they did, that is, if subject started with an opening parenthesis,
+the condition is true, and so the yes-pattern is executed and a closing
+parenthesis is required. Otherwise, since no-pattern is not present, the
+subpattern matches nothing. In other words, this pattern matches a sequence of
+non-parentheses, optionally enclosed in parentheses.
+
+If the condition is not a sequence of digits, it must be an assertion. This may
+be a positive or negative lookahead or lookbehind assertion. Consider this
+pattern, again containing non-significant white space, and with the two
+alternatives on the second line:
+
+ (?(?=[^a-z]*[a-z])
+ \\d{2}-[a-z]{3}-\\d{2} | \\d{2}-\\d{2}-\\d{2} )
+
+The condition is a positive lookahead assertion that matches an optional
+sequence of non-letters followed by a letter. In other words, it tests for the
+presence of at least one letter in the subject. If a letter is found, the
+subject is matched against the first alternative; otherwise it is matched
+against the second. This pattern matches strings in one of the two forms
+dd-aaa-dd or dd-dd-dd, where aaa are letters and dd are digits.
+
+
+.SH COMMENTS
+The sequence (?# marks the start of a comment which continues up to the next
+closing parenthesis. Nested parentheses are not permitted. The characters
+that make up a comment play no part in the pattern matching at all.
+
+If the PCRE_EXTENDED option is set, an unescaped # character outside a
+character class introduces a comment that continues up to the next newline
+character in the pattern.
+
+
+.SH RECURSIVE PATTERNS
+Consider the problem of matching a string in parentheses, allowing for
+unlimited nested parentheses. Without the use of recursion, the best that can
+be done is to use a pattern that matches up to some fixed depth of nesting. It
+is not possible to handle an arbitrary nesting depth. Perl 5.6 has provided an
+experimental facility that allows regular expressions to recurse (amongst other
+things). It does this by interpolating Perl code in the expression at run time,
+and the code can refer to the expression itself. A Perl pattern to solve the
+parentheses problem can be created like this:
+
+ $re = qr{\\( (?: (?>[^()]+) | (?p{$re}) )* \\)}x;
+
+The (?p{...}) item interpolates Perl code at run time, and in this case refers
+recursively to the pattern in which it appears. Obviously, PCRE cannot support
+the interpolation of Perl code. Instead, the special item (?R) is provided for
+the specific case of recursion. This PCRE pattern solves the parentheses
+problem (assume the PCRE_EXTENDED option is set so that white space is
+ignored):
+
+ \\( ( (?>[^()]+) | (?R) )* \\)
+
+First it matches an opening parenthesis. Then it matches any number of
+substrings which can either be a sequence of non-parentheses, or a recursive
+match of the pattern itself (i.e. a correctly parenthesized substring). Finally
+there is a closing parenthesis.
+
+This particular example pattern contains nested unlimited repeats, and so the
+use of a once-only subpattern for matching strings of non-parentheses is
+important when applying the pattern to strings that do not match. For example,
+when it is applied to
+
+ (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa()
+
+it yields "no match" quickly. However, if a once-only subpattern is not used,
+the match runs for a very long time indeed because there are so many different
+ways the + and * repeats can carve up the subject, and all have to be tested
+before failure can be reported.
+
+The values set for any capturing subpatterns are those from the outermost level
+of the recursion at which the subpattern value is set. If the pattern above is
+matched against
+
+ (ab(cd)ef)
+
+the value for the capturing parentheses is "ef", which is the last value taken
+on at the top level. If additional parentheses are added, giving
+
+ \\( ( ( (?>[^()]+) | (?R) )* ) \\)
+ ^ ^
+ ^ ^
+then the string they capture is "ab(cd)ef", the contents of the top level
+parentheses. If there are more than 15 capturing parentheses in a pattern, PCRE
+has to obtain extra memory to store data during a recursion, which it does by
+using \fBpcre_malloc\fR, freeing it via \fBpcre_free\fR afterwards. If no
+memory can be obtained, it saves data for the first 15 capturing parentheses
+only, as there is no way to give an out-of-memory error from within a
+recursion.
+
+
+.SH PERFORMANCE
+Certain items that may appear in patterns are more efficient than others. It is
+more efficient to use a character class like [aeiou] than a set of alternatives
+such as (a|e|i|o|u). In general, the simplest construction that provides the
+required behaviour is usually the most efficient. Jeffrey Friedl's book
+contains a lot of discussion about optimizing regular expressions for efficient
+performance.
+
+When a pattern begins with .* and the PCRE_DOTALL option is set, the pattern is
+implicitly anchored by PCRE, since it can match only at the start of a subject
+string. However, if PCRE_DOTALL is not set, PCRE cannot make this optimization,
+because the . metacharacter does not then match a newline, and if the subject
+string contains newlines, the pattern may match from the character immediately
+following one of them instead of from the very start. For example, the pattern
+
+ (.*) second
+
+matches the subject "first\\nand second" (where \\n stands for a newline
+character) with the first captured substring being "and". In order to do this,
+PCRE has to retry the match starting after every newline in the subject.
+
+If you are using such a pattern with subject strings that do not contain
+newlines, the best performance is obtained by setting PCRE_DOTALL, or starting
+the pattern with ^.* to indicate explicit anchoring. That saves PCRE from
+having to scan along the subject looking for a newline to restart at.
+
+Beware of patterns that contain nested indefinite repeats. These can take a
+long time to run when applied to a string that does not match. Consider the
+pattern fragment
+
+ (a+)*
+
+This can match "aaaa" in 33 different ways, and this number increases very
+rapidly as the string gets longer. (The * repeat can match 0, 1, 2, 3, or 4
+times, and for each of those cases other than 0, the + repeats can match
+different numbers of times.) When the remainder of the pattern is such that the
+entire match is going to fail, PCRE has in principle to try every possible
+variation, and this can take an extremely long time.
+
+An optimization catches some of the more simple cases such as
+
+ (a+)*b
+
+where a literal character follows. Before embarking on the standard matching
+procedure, PCRE checks that there is a "b" later in the subject string, and if
+there is not, it fails the match immediately. However, when there is no
+following literal this optimization cannot be used. You can see the difference
+by comparing the behaviour of
+
+ (a+)*\\d
+
+with the pattern above. The former gives a failure almost instantly when
+applied to a whole line of "a" characters, whereas the latter takes an
+appreciable time with strings longer than about 20 characters.
+
+.SH AUTHOR
+Philip Hazel <ph10@cam.ac.uk>
+.br
+University Computing Service,
+.br
+New Museums Site,
+.br
+Cambridge CB2 3QG, England.
+.br
+Phone: +44 1223 334714
+
+Last updated: 27 January 2000
+.br
+Copyright (c) 1997-2000 University of Cambridge.
--- /dev/null
+<HTML>
+<HEAD>
+<TITLE>pcre specification</TITLE>
+</HEAD>
+<body bgcolor="#FFFFFF" text="#00005A">
+<H1>pcre specification</H1>
+This HTML document has been generated automatically from the original man page.
+If there is any nonsense in it, please consult the man page in case the
+conversion went wrong.
+<UL>
+<LI><A NAME="TOC1" HREF="#SEC1">NAME</A>
+<LI><A NAME="TOC2" HREF="#SEC2">SYNOPSIS</A>
+<LI><A NAME="TOC3" HREF="#SEC3">DESCRIPTION</A>
+<LI><A NAME="TOC4" HREF="#SEC4">MULTI-THREADING</A>
+<LI><A NAME="TOC5" HREF="#SEC5">COMPILING A PATTERN</A>
+<LI><A NAME="TOC6" HREF="#SEC6">STUDYING A PATTERN</A>
+<LI><A NAME="TOC7" HREF="#SEC7">LOCALE SUPPORT</A>
+<LI><A NAME="TOC8" HREF="#SEC8">INFORMATION ABOUT A PATTERN</A>
+<LI><A NAME="TOC9" HREF="#SEC9">MATCHING A PATTERN</A>
+<LI><A NAME="TOC10" HREF="#SEC10">EXTRACTING CAPTURED SUBSTRINGS</A>
+<LI><A NAME="TOC11" HREF="#SEC11">LIMITATIONS</A>
+<LI><A NAME="TOC12" HREF="#SEC12">DIFFERENCES FROM PERL</A>
+<LI><A NAME="TOC13" HREF="#SEC13">REGULAR EXPRESSION DETAILS</A>
+<LI><A NAME="TOC14" HREF="#SEC14">BACKSLASH</A>
+<LI><A NAME="TOC15" HREF="#SEC15">CIRCUMFLEX AND DOLLAR</A>
+<LI><A NAME="TOC16" HREF="#SEC16">FULL STOP (PERIOD, DOT)</A>
+<LI><A NAME="TOC17" HREF="#SEC17">SQUARE BRACKETS</A>
+<LI><A NAME="TOC18" HREF="#SEC18">POSIX CHARACTER CLASSES</A>
+<LI><A NAME="TOC19" HREF="#SEC19">VERTICAL BAR</A>
+<LI><A NAME="TOC20" HREF="#SEC20">INTERNAL OPTION SETTING</A>
+<LI><A NAME="TOC21" HREF="#SEC21">SUBPATTERNS</A>
+<LI><A NAME="TOC22" HREF="#SEC22">REPETITION</A>
+<LI><A NAME="TOC23" HREF="#SEC23">BACK REFERENCES</A>
+<LI><A NAME="TOC24" HREF="#SEC24">ASSERTIONS</A>
+<LI><A NAME="TOC25" HREF="#SEC25">ONCE-ONLY SUBPATTERNS</A>
+<LI><A NAME="TOC26" HREF="#SEC26">CONDITIONAL SUBPATTERNS</A>
+<LI><A NAME="TOC27" HREF="#SEC27">COMMENTS</A>
+<LI><A NAME="TOC28" HREF="#SEC28">RECURSIVE PATTERNS</A>
+<LI><A NAME="TOC29" HREF="#SEC29">PERFORMANCE</A>
+<LI><A NAME="TOC30" HREF="#SEC30">AUTHOR</A>
+</UL>
+<LI><A NAME="SEC1" HREF="#TOC1">NAME</A>
+<P>
+pcre - Perl-compatible regular expressions.
+</P>
+<LI><A NAME="SEC2" HREF="#TOC1">SYNOPSIS</A>
+<P>
+<B>#include <pcre.h></B>
+</P>
+<P>
+<B>pcre *pcre_compile(const char *<I>pattern</I>, int <I>options</I>,</B>
+<B>const char **<I>errptr</I>, int *<I>erroffset</I>,</B>
+<B>const unsigned char *<I>tableptr</I>);</B>
+</P>
+<P>
+<B>pcre_extra *pcre_study(const pcre *<I>code</I>, int <I>options</I>,</B>
+<B>const char **<I>errptr</I>);</B>
+</P>
+<P>
+<B>int pcre_exec(const pcre *<I>code</I>, const pcre_extra *<I>extra</I>,</B>
+<B>const char *<I>subject</I>, int <I>length</I>, int <I>startoffset</I>,</B>
+<B>int <I>options</I>, int *<I>ovector</I>, int <I>ovecsize</I>);</B>
+</P>
+<P>
+<B>int pcre_copy_substring(const char *<I>subject</I>, int *<I>ovector</I>,</B>
+<B>int <I>stringcount</I>, int <I>stringnumber</I>, char *<I>buffer</I>,</B>
+<B>int <I>buffersize</I>);</B>
+</P>
+<P>
+<B>int pcre_get_substring(const char *<I>subject</I>, int *<I>ovector</I>,</B>
+<B>int <I>stringcount</I>, int <I>stringnumber</I>,</B>
+<B>const char **<I>stringptr</I>);</B>
+</P>
+<P>
+<B>int pcre_get_substring_list(const char *<I>subject</I>,</B>
+<B>int *<I>ovector</I>, int <I>stringcount</I>, const char ***<I>listptr</I>);</B>
+</P>
+<P>
+<B>const unsigned char *pcre_maketables(void);</B>
+</P>
+<P>
+<B>int pcre_fullinfo(const pcre *<I>code</I>, const pcre_extra *<I>extra</I>,</B>
+<B>int <I>what</I>, void *<I>where</I>);</B>
+</P>
+<P>
+<B>int pcre_info(const pcre *<I>code</I>, int *<I>optptr</I>, int</B>
+<B>*<I>firstcharptr</I>);</B>
+</P>
+<P>
+<B>char *pcre_version(void);</B>
+</P>
+<P>
+<B>void *(*pcre_malloc)(size_t);</B>
+</P>
+<P>
+<B>void (*pcre_free)(void *);</B>
+</P>
+<LI><A NAME="SEC3" HREF="#TOC1">DESCRIPTION</A>
+<P>
+The PCRE library is a set of functions that implement regular expression
+pattern matching using the same syntax and semantics as Perl 5, with just a few
+differences (see below). The current implementation corresponds to Perl 5.005,
+with some additional features from the Perl development release.
+</P>
+<P>
+PCRE has its own native API, which is described in this document. There is also
+a set of wrapper functions that correspond to the POSIX regular expression API.
+These are described in the <B>pcreposix</B> documentation.
+</P>
+<P>
+The native API function prototypes are defined in the header file <B>pcre.h</B>,
+and on Unix systems the library itself is called <B>libpcre.a</B>, so can be
+accessed by adding <B>-lpcre</B> to the command for linking an application which
+calls it. The header file defines the macros PCRE_MAJOR and PCRE_MINOR to
+contain the major and minor release numbers for the library. Applications can
+use these to include support for different releases.
+</P>
+<P>
+The functions <B>pcre_compile()</B>, <B>pcre_study()</B>, and <B>pcre_exec()</B>
+are used for compiling and matching regular expressions, while
+<B>pcre_copy_substring()</B>, <B>pcre_get_substring()</B>, and
+<B>pcre_get_substring_list()</B> are convenience functions for extracting
+captured substrings from a matched subject string. The function
+<B>pcre_maketables()</B> is used (optionally) to build a set of character tables
+in the current locale for passing to <B>pcre_compile()</B>.
+</P>
+<P>
+The function <B>pcre_fullinfo()</B> is used to find out information about a
+compiled pattern; <B>pcre_info()</B> is an obsolete version which returns only
+some of the available information, but is retained for backwards compatibility.
+The function <B>pcre_version()</B> returns a pointer to a string containing the
+version of PCRE and its date of release.
+</P>
+<P>
+The global variables <B>pcre_malloc</B> and <B>pcre_free</B> initially contain
+the entry points of the standard <B>malloc()</B> and <B>free()</B> functions
+respectively. PCRE calls the memory management functions via these variables,
+so a calling program can replace them if it wishes to intercept the calls. This
+should be done before calling any PCRE functions.
+</P>
+<LI><A NAME="SEC4" HREF="#TOC1">MULTI-THREADING</A>
+<P>
+The PCRE functions can be used in multi-threading applications, with the
+proviso that the memory management functions pointed to by <B>pcre_malloc</B>
+and <B>pcre_free</B> are shared by all threads.
+</P>
+<P>
+The compiled form of a regular expression is not altered during matching, so
+the same compiled pattern can safely be used by several threads at once.
+</P>
+<LI><A NAME="SEC5" HREF="#TOC1">COMPILING A PATTERN</A>
+<P>
+The function <B>pcre_compile()</B> is called to compile a pattern into an
+internal form. The pattern is a C string terminated by a binary zero, and
+is passed in the argument <I>pattern</I>. A pointer to a single block of memory
+that is obtained via <B>pcre_malloc</B> is returned. This contains the
+compiled code and related data. The <B>pcre</B> type is defined for this for
+convenience, but in fact <B>pcre</B> is just a typedef for <B>void</B>, since the
+contents of the block are not externally defined. It is up to the caller to
+free the memory when it is no longer required.
+</P>
+<P>
+The size of a compiled pattern is roughly proportional to the length of the
+pattern string, except that each character class (other than those containing
+just a single character, negated or not) requires 33 bytes, and repeat
+quantifiers with a minimum greater than one or a bounded maximum cause the
+relevant portions of the compiled pattern to be replicated.
+</P>
+<P>
+The <I>options</I> argument contains independent bits that affect the
+compilation. It should be zero if no options are required. Some of the options,
+in particular, those that are compatible with Perl, can also be set and unset
+from within the pattern (see the detailed description of regular expressions
+below). For these options, the contents of the <I>options</I> argument specifies
+their initial settings at the start of compilation and execution. The
+PCRE_ANCHORED option can be set at the time of matching as well as at compile
+time.
+</P>
+<P>
+If <I>errptr</I> is NULL, <B>pcre_compile()</B> returns NULL immediately.
+Otherwise, if compilation of a pattern fails, <B>pcre_compile()</B> returns
+NULL, and sets the variable pointed to by <I>errptr</I> to point to a textual
+error message. The offset from the start of the pattern to the character where
+the error was discovered is placed in the variable pointed to by
+<I>erroffset</I>, which must not be NULL. If it is, an immediate error is given.
+</P>
+<P>
+If the final argument, <I>tableptr</I>, is NULL, PCRE uses a default set of
+character tables which are built when it is compiled, using the default C
+locale. Otherwise, <I>tableptr</I> must be the result of a call to
+<B>pcre_maketables()</B>. See the section on locale support below.
+</P>
+<P>
+The following option bits are defined in the header file:
+</P>
+<P>
+<PRE>
+ PCRE_ANCHORED
+</PRE>
+</P>
+<P>
+If this bit is set, the pattern is forced to be "anchored", that is, it is
+constrained to match only at the start of the string which is being searched
+(the "subject string"). This effect can also be achieved by appropriate
+constructs in the pattern itself, which is the only way to do it in Perl.
+</P>
+<P>
+<PRE>
+ PCRE_CASELESS
+</PRE>
+</P>
+<P>
+If this bit is set, letters in the pattern match both upper and lower case
+letters. It is equivalent to Perl's /i option.
+</P>
+<P>
+<PRE>
+ PCRE_DOLLAR_ENDONLY
+</PRE>
+</P>
+<P>
+If this bit is set, a dollar metacharacter in the pattern matches only at the
+end of the subject string. Without this option, a dollar also matches
+immediately before the final character if it is a newline (but not before any
+other newlines). The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is
+set. There is no equivalent to this option in Perl.
+</P>
+<P>
+<PRE>
+ PCRE_DOTALL
+</PRE>
+</P>
+<P>
+If this bit is set, a dot metacharater in the pattern matches all characters,
+including newlines. Without it, newlines are excluded. This option is
+equivalent to Perl's /s option. A negative class such as [^a] always matches a
+newline character, independent of the setting of this option.
+</P>
+<P>
+<PRE>
+ PCRE_EXTENDED
+</PRE>
+</P>
+<P>
+If this bit is set, whitespace data characters in the pattern are totally
+ignored except when escaped or inside a character class, and characters between
+an unescaped # outside a character class and the next newline character,
+inclusive, are also ignored. This is equivalent to Perl's /x option, and makes
+it possible to include comments inside complicated patterns. Note, however,
+that this applies only to data characters. Whitespace characters may never
+appear within special character sequences in a pattern, for example within the
+sequence (?( which introduces a conditional subpattern.
+</P>
+<P>
+<PRE>
+ PCRE_EXTRA
+</PRE>
+</P>
+<P>
+This option was invented in order to turn on additional functionality of PCRE
+that is incompatible with Perl, but it is currently of very little use. When
+set, any backslash in a pattern that is followed by a letter that has no
+special meaning causes an error, thus reserving these combinations for future
+expansion. By default, as in Perl, a backslash followed by a letter with no
+special meaning is treated as a literal. There are at present no other features
+controlled by this option. It can also be set by a (?X) option setting within a
+pattern.
+</P>
+<P>
+<PRE>
+ PCRE_MULTILINE
+</PRE>
+</P>
+<P>
+By default, PCRE treats the subject string as consisting of a single "line" of
+characters (even if it actually contains several newlines). The "start of line"
+metacharacter (^) matches only at the start of the string, while the "end of
+line" metacharacter ($) matches only at the end of the string, or before a
+terminating newline (unless PCRE_DOLLAR_ENDONLY is set). This is the same as
+Perl.
+</P>
+<P>
+When PCRE_MULTILINE it is set, the "start of line" and "end of line" constructs
+match immediately following or immediately before any newline in the subject
+string, respectively, as well as at the very start and end. This is equivalent
+to Perl's /m option. If there are no "\n" characters in a subject string, or
+no occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no
+effect.
+</P>
+<P>
+<PRE>
+ PCRE_UNGREEDY
+</PRE>
+</P>
+<P>
+This option inverts the "greediness" of the quantifiers so that they are not
+greedy by default, but become greedy if followed by "?". It is not compatible
+with Perl. It can also be set by a (?U) option setting within the pattern.
+</P>
+<LI><A NAME="SEC6" HREF="#TOC1">STUDYING A PATTERN</A>
+<P>
+When a pattern is going to be used several times, it is worth spending more
+time analyzing it in order to speed up the time taken for matching. The
+function <B>pcre_study()</B> takes a pointer to a compiled pattern as its first
+argument, and returns a pointer to a <B>pcre_extra</B> block (another <B>void</B>
+typedef) containing additional information about the pattern; this can be
+passed to <B>pcre_exec()</B>. If no additional information is available, NULL
+is returned.
+</P>
+<P>
+The second argument contains option bits. At present, no options are defined
+for <B>pcre_study()</B>, and this argument should always be zero.
+</P>
+<P>
+The third argument for <B>pcre_study()</B> is a pointer to an error message. If
+studying succeeds (even if no data is returned), the variable it points to is
+set to NULL. Otherwise it points to a textual error message.
+</P>
+<P>
+At present, studying a pattern is useful only for non-anchored patterns that do
+not have a single fixed starting character. A bitmap of possible starting
+characters is created.
+</P>
+<LI><A NAME="SEC7" HREF="#TOC1">LOCALE SUPPORT</A>
+<P>
+PCRE handles caseless matching, and determines whether characters are letters,
+digits, or whatever, by reference to a set of tables. The library contains a
+default set of tables which is created in the default C locale when PCRE is
+compiled. This is used when the final argument of <B>pcre_compile()</B> is NULL,
+and is sufficient for many applications.
+</P>
+<P>
+An alternative set of tables can, however, be supplied. Such tables are built
+by calling the <B>pcre_maketables()</B> function, which has no arguments, in the
+relevant locale. The result can then be passed to <B>pcre_compile()</B> as often
+as necessary. For example, to build and use tables that are appropriate for the
+French locale (where accented characters with codes greater than 128 are
+treated as letters), the following code could be used:
+</P>
+<P>
+<PRE>
+ setlocale(LC_CTYPE, "fr");
+ tables = pcre_maketables();
+ re = pcre_compile(..., tables);
+</PRE>
+</P>
+<P>
+The tables are built in memory that is obtained via <B>pcre_malloc</B>. The
+pointer that is passed to <B>pcre_compile</B> is saved with the compiled
+pattern, and the same tables are used via this pointer by <B>pcre_study()</B>
+and <B>pcre_exec()</B>. Thus for any single pattern, compilation, studying and
+matching all happen in the same locale, but different patterns can be compiled
+in different locales. It is the caller's responsibility to ensure that the
+memory containing the tables remains available for as long as it is needed.
+</P>
+<LI><A NAME="SEC8" HREF="#TOC1">INFORMATION ABOUT A PATTERN</A>
+<P>
+The <B>pcre_fullinfo()</B> function returns information about a compiled
+pattern. It replaces the obsolete <B>pcre_info()</B> function, which is
+nevertheless retained for backwards compability (and is documented below).
+</P>
+<P>
+The first argument for <B>pcre_fullinfo()</B> is a pointer to the compiled
+pattern. The second argument is the result of <B>pcre_study()</B>, or NULL if
+the pattern was not studied. The third argument specifies which piece of
+information is required, while the fourth argument is a pointer to a variable
+to receive the data. The yield of the function is zero for success, or one of
+the following negative numbers:
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_NULL the argument <I>code</I> was NULL
+ the argument <I>where</I> was NULL
+ PCRE_ERROR_BADMAGIC the "magic number" was not found
+ PCRE_ERROR_BADOPTION the value of <I>what</I> was invalid
+</PRE>
+</P>
+<P>
+The possible values for the third argument are defined in <B>pcre.h</B>, and are
+as follows:
+</P>
+<P>
+<PRE>
+ PCRE_INFO_OPTIONS
+</PRE>
+</P>
+<P>
+Return a copy of the options with which the pattern was compiled. The fourth
+argument should point to au <B>unsigned long int</B> variable. These option bits
+are those specified in the call to <B>pcre_compile()</B>, modified by any
+top-level option settings within the pattern itself, and with the PCRE_ANCHORED
+bit forcibly set if the form of the pattern implies that it can match only at
+the start of a subject string.
+</P>
+<P>
+<PRE>
+ PCRE_INFO_SIZE
+</PRE>
+</P>
+<P>
+Return the size of the compiled pattern, that is, the value that was passed as
+the argument to <B>pcre_malloc()</B> when PCRE was getting memory in which to
+place the compiled data. The fourth argument should point to a <B>size_t</B>
+variable.
+</P>
+<P>
+<PRE>
+ PCRE_INFO_CAPTURECOUNT
+</PRE>
+</P>
+<P>
+Return the number of capturing subpatterns in the pattern. The fourth argument
+should point to an \fbint\fR variable.
+</P>
+<P>
+<PRE>
+ PCRE_INFO_BACKREFMAX
+</PRE>
+</P>
+<P>
+Return the number of the highest back reference in the pattern. The fourth
+argument should point to an <B>int</B> variable. Zero is returned if there are
+no back references.
+</P>
+<P>
+<PRE>
+ PCRE_INFO_FIRSTCHAR
+</PRE>
+</P>
+<P>
+Return information about the first character of any matched string, for a
+non-anchored pattern. If there is a fixed first character, e.g. from a pattern
+such as (cat|cow|coyote), then it is returned in the integer pointed to by
+<I>where</I>. Otherwise, if either
+</P>
+<P>
+(a) the pattern was compiled with the PCRE_MULTILINE option, and every branch
+starts with "^", or
+</P>
+<P>
+(b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set
+(if it were set, the pattern would be anchored),
+</P>
+<P>
+then -1 is returned, indicating that the pattern matches only at the
+start of a subject string or after any "\n" within the string. Otherwise -2 is
+returned. For anchored patterns, -2 is returned.
+</P>
+<P>
+<PRE>
+ PCRE_INFO_FIRSTTABLE
+</PRE>
+</P>
+<P>
+If the pattern was studied, and this resulted in the construction of a 256-bit
+table indicating a fixed set of characters for the first character in any
+matching string, a pointer to the table is returned. Otherwise NULL is
+returned. The fourth argument should point to an <B>unsigned char *</B>
+variable.
+</P>
+<P>
+<PRE>
+ PCRE_INFO_LASTLITERAL
+</PRE>
+</P>
+<P>
+For a non-anchored pattern, return the value of the rightmost literal character
+which must exist in any matched string, other than at its start. The fourth
+argument should point to an <B>int</B> variable. If there is no such character,
+or if the pattern is anchored, -1 is returned. For example, for the pattern
+/a\d+z\d+/ the returned value is 'z'.
+</P>
+<P>
+The <B>pcre_info()</B> function is now obsolete because its interface is too
+restrictive to return all the available data about a compiled pattern. New
+programs should use <B>pcre_fullinfo()</B> instead. The yield of
+<B>pcre_info()</B> is the number of capturing subpatterns, or one of the
+following negative numbers:
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_NULL the argument <I>code</I> was NULL
+ PCRE_ERROR_BADMAGIC the "magic number" was not found
+</PRE>
+</P>
+<P>
+If the <I>optptr</I> argument is not NULL, a copy of the options with which the
+pattern was compiled is placed in the integer it points to (see
+PCRE_INFO_OPTIONS above).
+</P>
+<P>
+If the pattern is not anchored and the <I>firstcharptr</I> argument is not NULL,
+it is used to pass back information about the first character of any matched
+string (see PCRE_INFO_FIRSTCHAR above).
+</P>
+<LI><A NAME="SEC9" HREF="#TOC1">MATCHING A PATTERN</A>
+<P>
+The function <B>pcre_exec()</B> is called to match a subject string against a
+pre-compiled pattern, which is passed in the <I>code</I> argument. If the
+pattern has been studied, the result of the study should be passed in the
+<I>extra</I> argument. Otherwise this must be NULL.
+</P>
+<P>
+The PCRE_ANCHORED option can be passed in the <I>options</I> argument, whose
+unused bits must be zero. However, if a pattern was compiled with
+PCRE_ANCHORED, or turned out to be anchored by virtue of its contents, it
+cannot be made unachored at matching time.
+</P>
+<P>
+There are also three further options that can be set only at matching time:
+</P>
+<P>
+<PRE>
+ PCRE_NOTBOL
+</PRE>
+</P>
+<P>
+The first character of the string is not the beginning of a line, so the
+circumflex metacharacter should not match before it. Setting this without
+PCRE_MULTILINE (at compile time) causes circumflex never to match.
+</P>
+<P>
+<PRE>
+ PCRE_NOTEOL
+</PRE>
+</P>
+<P>
+The end of the string is not the end of a line, so the dollar metacharacter
+should not match it nor (except in multiline mode) a newline immediately before
+it. Setting this without PCRE_MULTILINE (at compile time) causes dollar never
+to match.
+</P>
+<P>
+<PRE>
+ PCRE_NOTEMPTY
+</PRE>
+</P>
+<P>
+An empty string is not considered to be a valid match if this option is set. If
+there are alternatives in the pattern, they are tried. If all the alternatives
+match the empty string, the entire match fails. For example, if the pattern
+</P>
+<P>
+<PRE>
+ a?b?
+</PRE>
+</P>
+<P>
+is applied to a string not beginning with "a" or "b", it matches the empty
+string at the start of the subject. With PCRE_NOTEMPTY set, this match is not
+valid, so PCRE searches further into the string for occurrences of "a" or "b".
+</P>
+<P>
+Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case
+of a pattern match of the empty string within its <B>split()</B> function, and
+when using the /g modifier. It is possible to emulate Perl's behaviour after
+matching a null string by first trying the match again at the same offset with
+PCRE_NOTEMPTY set, and then if that fails by advancing the starting offset (see
+below) and trying an ordinary match again.
+</P>
+<P>
+The subject string is passed as a pointer in <I>subject</I>, a length in
+<I>length</I>, and a starting offset in <I>startoffset</I>. Unlike the pattern
+string, it may contain binary zero characters. When the starting offset is
+zero, the search for a match starts at the beginning of the subject, and this
+is by far the most common case.
+</P>
+<P>
+A non-zero starting offset is useful when searching for another match in the
+same subject by calling <B>pcre_exec()</B> again after a previous success.
+Setting <I>startoffset</I> differs from just passing over a shortened string and
+setting PCRE_NOTBOL in the case of a pattern that begins with any kind of
+lookbehind. For example, consider the pattern
+</P>
+<P>
+<PRE>
+ \Biss\B
+</PRE>
+</P>
+<P>
+which finds occurrences of "iss" in the middle of words. (\B matches only if
+the current position in the subject is not a word boundary.) When applied to
+the string "Mississipi" the first call to <B>pcre_exec()</B> finds the first
+occurrence. If <B>pcre_exec()</B> is called again with just the remainder of the
+subject, namely "issipi", it does not match, because \B is always false at the
+start of the subject, which is deemed to be a word boundary. However, if
+<B>pcre_exec()</B> is passed the entire string again, but with <I>startoffset</I>
+set to 4, it finds the second occurrence of "iss" because it is able to look
+behind the starting point to discover that it is preceded by a letter.
+</P>
+<P>
+If a non-zero starting offset is passed when the pattern is anchored, one
+attempt to match at the given offset is tried. This can only succeed if the
+pattern does not require the match to be at the start of the subject.
+</P>
+<P>
+In general, a pattern matches a certain portion of the subject, and in
+addition, further substrings from the subject may be picked out by parts of the
+pattern. Following the usage in Jeffrey Friedl's book, this is called
+"capturing" in what follows, and the phrase "capturing subpattern" is used for
+a fragment of a pattern that picks out a substring. PCRE supports several other
+kinds of parenthesized subpattern that do not cause substrings to be captured.
+</P>
+<P>
+Captured substrings are returned to the caller via a vector of integer offsets
+whose address is passed in <I>ovector</I>. The number of elements in the vector
+is passed in <I>ovecsize</I>. The first two-thirds of the vector is used to pass
+back captured substrings, each substring using a pair of integers. The
+remaining third of the vector is used as workspace by <B>pcre_exec()</B> while
+matching capturing subpatterns, and is not available for passing back
+information. The length passed in <I>ovecsize</I> should always be a multiple of
+three. If it is not, it is rounded down.
+</P>
+<P>
+When a match has been successful, information about captured substrings is
+returned in pairs of integers, starting at the beginning of <I>ovector</I>, and
+continuing up to two-thirds of its length at the most. The first element of a
+pair is set to the offset of the first character in a substring, and the second
+is set to the offset of the first character after the end of a substring. The
+first pair, <I>ovector[0]</I> and <I>ovector[1]</I>, identify the portion of the
+subject string matched by the entire pattern. The next pair is used for the
+first capturing subpattern, and so on. The value returned by <B>pcre_exec()</B>
+is the number of pairs that have been set. If there are no capturing
+subpatterns, the return value from a successful match is 1, indicating that
+just the first pair of offsets has been set.
+</P>
+<P>
+Some convenience functions are provided for extracting the captured substrings
+as separate strings. These are described in the following section.
+</P>
+<P>
+It is possible for an capturing subpattern number <I>n+1</I> to match some
+part of the subject when subpattern <I>n</I> has not been used at all. For
+example, if the string "abc" is matched against the pattern (a|(z))(bc)
+subpatterns 1 and 3 are matched, but 2 is not. When this happens, both offset
+values corresponding to the unused subpattern are set to -1.
+</P>
+<P>
+If a capturing subpattern is matched repeatedly, it is the last portion of the
+string that it matched that gets returned.
+</P>
+<P>
+If the vector is too small to hold all the captured substrings, it is used as
+far as possible (up to two-thirds of its length), and the function returns a
+value of zero. In particular, if the substring offsets are not of interest,
+<B>pcre_exec()</B> may be called with <I>ovector</I> passed as NULL and
+<I>ovecsize</I> as zero. However, if the pattern contains back references and
+the <I>ovector</I> isn't big enough to remember the related substrings, PCRE has
+to get additional memory for use during matching. Thus it is usually advisable
+to supply an <I>ovector</I>.
+</P>
+<P>
+Note that <B>pcre_info()</B> can be used to find out how many capturing
+subpatterns there are in a compiled pattern. The smallest size for
+<I>ovector</I> that will allow for <I>n</I> captured substrings in addition to
+the offsets of the substring matched by the whole pattern is (<I>n</I>+1)*3.
+</P>
+<P>
+If <B>pcre_exec()</B> fails, it returns a negative number. The following are
+defined in the header file:
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_NOMATCH (-1)
+</PRE>
+</P>
+<P>
+The subject string did not match the pattern.
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_NULL (-2)
+</PRE>
+</P>
+<P>
+Either <I>code</I> or <I>subject</I> was passed as NULL, or <I>ovector</I> was
+NULL and <I>ovecsize</I> was not zero.
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_BADOPTION (-3)
+</PRE>
+</P>
+<P>
+An unrecognized bit was set in the <I>options</I> argument.
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_BADMAGIC (-4)
+</PRE>
+</P>
+<P>
+PCRE stores a 4-byte "magic number" at the start of the compiled code, to catch
+the case when it is passed a junk pointer. This is the error it gives when the
+magic number isn't present.
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_UNKNOWN_NODE (-5)
+</PRE>
+</P>
+<P>
+While running the pattern match, an unknown item was encountered in the
+compiled pattern. This error could be caused by a bug in PCRE or by overwriting
+of the compiled pattern.
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_NOMEMORY (-6)
+</PRE>
+</P>
+<P>
+If a pattern contains back references, but the <I>ovector</I> that is passed to
+<B>pcre_exec()</B> is not big enough to remember the referenced substrings, PCRE
+gets a block of memory at the start of matching to use for this purpose. If the
+call via <B>pcre_malloc()</B> fails, this error is given. The memory is freed at
+the end of matching.
+</P>
+<LI><A NAME="SEC10" HREF="#TOC1">EXTRACTING CAPTURED SUBSTRINGS</A>
+<P>
+Captured substrings can be accessed directly by using the offsets returned by
+<B>pcre_exec()</B> in <I>ovector</I>. For convenience, the functions
+<B>pcre_copy_substring()</B>, <B>pcre_get_substring()</B>, and
+<B>pcre_get_substring_list()</B> are provided for extracting captured substrings
+as new, separate, zero-terminated strings. A substring that contains a binary
+zero is correctly extracted and has a further zero added on the end, but the
+result does not, of course, function as a C string.
+</P>
+<P>
+The first three arguments are the same for all three functions: <I>subject</I>
+is the subject string which has just been successfully matched, <I>ovector</I>
+is a pointer to the vector of integer offsets that was passed to
+<B>pcre_exec()</B>, and <I>stringcount</I> is the number of substrings that
+were captured by the match, including the substring that matched the entire
+regular expression. This is the value returned by <B>pcre_exec</B> if it
+is greater than zero. If <B>pcre_exec()</B> returned zero, indicating that it
+ran out of space in <I>ovector</I>, then the value passed as
+<I>stringcount</I> should be the size of the vector divided by three.
+</P>
+<P>
+The functions <B>pcre_copy_substring()</B> and <B>pcre_get_substring()</B>
+extract a single substring, whose number is given as <I>stringnumber</I>. A
+value of zero extracts the substring that matched the entire pattern, while
+higher values extract the captured substrings. For <B>pcre_copy_substring()</B>,
+the string is placed in <I>buffer</I>, whose length is given by
+<I>buffersize</I>, while for <B>pcre_get_substring()</B> a new block of store is
+obtained via <B>pcre_malloc</B>, and its address is returned via
+<I>stringptr</I>. The yield of the function is the length of the string, not
+including the terminating zero, or one of
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_NOMEMORY (-6)
+</PRE>
+</P>
+<P>
+The buffer was too small for <B>pcre_copy_substring()</B>, or the attempt to get
+memory failed for <B>pcre_get_substring()</B>.
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_NOSUBSTRING (-7)
+</PRE>
+</P>
+<P>
+There is no substring whose number is <I>stringnumber</I>.
+</P>
+<P>
+The <B>pcre_get_substring_list()</B> function extracts all available substrings
+and builds a list of pointers to them. All this is done in a single block of
+memory which is obtained via <B>pcre_malloc</B>. The address of the memory block
+is returned via <I>listptr</I>, which is also the start of the list of string
+pointers. The end of the list is marked by a NULL pointer. The yield of the
+function is zero if all went well, or
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_NOMEMORY (-6)
+</PRE>
+</P>
+<P>
+if the attempt to get the memory block failed.
+</P>
+<P>
+When any of these functions encounter a substring that is unset, which can
+happen when capturing subpattern number <I>n+1</I> matches some part of the
+subject, but subpattern <I>n</I> has not been used at all, they return an empty
+string. This can be distinguished from a genuine zero-length substring by
+inspecting the appropriate offset in <I>ovector</I>, which is negative for unset
+substrings.
+</P>
+<LI><A NAME="SEC11" HREF="#TOC1">LIMITATIONS</A>
+<P>
+There are some size limitations in PCRE but it is hoped that they will never in
+practice be relevant.
+The maximum length of a compiled pattern is 65539 (sic) bytes.
+All values in repeating quantifiers must be less than 65536.
+The maximum number of capturing subpatterns is 99.
+The maximum number of all parenthesized subpatterns, including capturing
+subpatterns, assertions, and other types of subpattern, is 200.
+</P>
+<P>
+The maximum length of a subject string is the largest positive number that an
+integer variable can hold. However, PCRE uses recursion to handle subpatterns
+and indefinite repetition. This means that the available stack space may limit
+the size of a subject string that can be processed by certain patterns.
+</P>
+<LI><A NAME="SEC12" HREF="#TOC1">DIFFERENCES FROM PERL</A>
+<P>
+The differences described here are with respect to Perl 5.005.
+</P>
+<P>
+1. By default, a whitespace character is any character that the C library
+function <B>isspace()</B> recognizes, though it is possible to compile PCRE with
+alternative character type tables. Normally <B>isspace()</B> matches space,
+formfeed, newline, carriage return, horizontal tab, and vertical tab. Perl 5
+no longer includes vertical tab in its set of whitespace characters. The \v
+escape that was in the Perl documentation for a long time was never in fact
+recognized. However, the character itself was treated as whitespace at least
+up to 5.002. In 5.004 and 5.005 it does not match \s.
+</P>
+<P>
+2. PCRE does not allow repeat quantifiers on lookahead assertions. Perl permits
+them, but they do not mean what you might think. For example, (?!a){3} does
+not assert that the next three characters are not "a". It just asserts that the
+next character is not "a" three times.
+</P>
+<P>
+3. Capturing subpatterns that occur inside negative lookahead assertions are
+counted, but their entries in the offsets vector are never set. Perl sets its
+numerical variables from any such patterns that are matched before the
+assertion fails to match something (thereby succeeding), but only if the
+negative lookahead assertion contains just one branch.
+</P>
+<P>
+4. Though binary zero characters are supported in the subject string, they are
+not allowed in a pattern string because it is passed as a normal C string,
+terminated by zero. The escape sequence "\0" can be used in the pattern to
+represent a binary zero.
+</P>
+<P>
+5. The following Perl escape sequences are not supported: \l, \u, \L, \U,
+\E, \Q. In fact these are implemented by Perl's general string-handling and
+are not part of its pattern matching engine.
+</P>
+<P>
+6. The Perl \G assertion is not supported as it is not relevant to single
+pattern matches.
+</P>
+<P>
+7. Fairly obviously, PCRE does not support the (?{code}) and (?p{code})
+constructions. However, there is some experimental support for recursive
+patterns using the non-Perl item (?R).
+</P>
+<P>
+8. There are at the time of writing some oddities in Perl 5.005_02 concerned
+with the settings of captured strings when part of a pattern is repeated. For
+example, matching "aba" against the pattern /^(a(b)?)+$/ sets $2 to the value
+"b", but matching "aabbaa" against /^(aa(bb)?)+$/ leaves $2 unset. However, if
+the pattern is changed to /^(aa(b(b))?)+$/ then $2 (and $3) get set.
+</P>
+<P>
+In Perl 5.004 $2 is set in both cases, and that is also true of PCRE. If in the
+future Perl changes to a consistent state that is different, PCRE may change to
+follow.
+</P>
+<P>
+9. Another as yet unresolved discrepancy is that in Perl 5.005_02 the pattern
+/^(a)?(?(1)a|b)+$/ matches the string "a", whereas in PCRE it does not.
+However, in both Perl and PCRE /^(a)?a/ matched against "a" leaves $1 unset.
+</P>
+<P>
+10. PCRE provides some extensions to the Perl regular expression facilities:
+</P>
+<P>
+(a) Although lookbehind assertions must match fixed length strings, each
+alternative branch of a lookbehind assertion can match a different length of
+string. Perl 5.005 requires them all to have the same length.
+</P>
+<P>
+(b) If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not set, the $ meta-
+character matches only at the very end of the string.
+</P>
+<P>
+(c) If PCRE_EXTRA is set, a backslash followed by a letter with no special
+meaning is faulted.
+</P>
+<P>
+(d) If PCRE_UNGREEDY is set, the greediness of the repetition quantifiers is
+inverted, that is, by default they are not greedy, but if followed by a
+question mark they are.
+</P>
+<P>
+(e) PCRE_ANCHORED can be used to force a pattern to be tried only at the start
+of the subject.
+</P>
+<P>
+(f) The PCRE_NOTBOL, PCRE_NOTEOL, and PCRE_NOTEMPTY options for
+<B>pcre_exec()</B> have no Perl equivalents.
+</P>
+<P>
+(g) The (?R) construct allows for recursive pattern matching (Perl 5.6 can do
+this using the (?p{code}) construct, which PCRE cannot of course support.)
+</P>
+<LI><A NAME="SEC13" HREF="#TOC1">REGULAR EXPRESSION DETAILS</A>
+<P>
+The syntax and semantics of the regular expressions supported by PCRE are
+described below. Regular expressions are also described in the Perl
+documentation and in a number of other books, some of which have copious
+examples. Jeffrey Friedl's "Mastering Regular Expressions", published by
+O'Reilly (ISBN 1-56592-257), covers them in great detail. The description
+here is intended as reference documentation.
+</P>
+<P>
+A regular expression is a pattern that is matched against a subject string from
+left to right. Most characters stand for themselves in a pattern, and match the
+corresponding characters in the subject. As a trivial example, the pattern
+</P>
+<P>
+<PRE>
+ The quick brown fox
+</PRE>
+</P>
+<P>
+matches a portion of a subject string that is identical to itself. The power of
+regular expressions comes from the ability to include alternatives and
+repetitions in the pattern. These are encoded in the pattern by the use of
+<I>meta-characters</I>, which do not stand for themselves but instead are
+interpreted in some special way.
+</P>
+<P>
+There are two different sets of meta-characters: those that are recognized
+anywhere in the pattern except within square brackets, and those that are
+recognized in square brackets. Outside square brackets, the meta-characters are
+as follows:
+</P>
+<P>
+<PRE>
+ \ general escape character with several uses
+ ^ assert start of subject (or line, in multiline mode)
+ $ assert end of subject (or line, in multiline mode)
+ . match any character except newline (by default)
+ [ start character class definition
+ | start of alternative branch
+ ( start subpattern
+ ) end subpattern
+ ? extends the meaning of (
+ also 0 or 1 quantifier
+ also quantifier minimizer
+ * 0 or more quantifier
+ + 1 or more quantifier
+ { start min/max quantifier
+</PRE>
+</P>
+<P>
+Part of a pattern that is in square brackets is called a "character class". In
+a character class the only meta-characters are:
+</P>
+<P>
+<PRE>
+ \ general escape character
+ ^ negate the class, but only if the first character
+ - indicates character range
+ ] terminates the character class
+</PRE>
+</P>
+<P>
+The following sections describe the use of each of the meta-characters.
+</P>
+<LI><A NAME="SEC14" HREF="#TOC1">BACKSLASH</A>
+<P>
+The backslash character has several uses. Firstly, if it is followed by a
+non-alphameric character, it takes away any special meaning that character may
+have. This use of backslash as an escape character applies both inside and
+outside character classes.
+</P>
+<P>
+For example, if you want to match a "*" character, you write "\*" in the
+pattern. This applies whether or not the following character would otherwise be
+interpreted as a meta-character, so it is always safe to precede a
+non-alphameric with "\" to specify that it stands for itself. In particular,
+if you want to match a backslash, you write "\\".
+</P>
+<P>
+If a pattern is compiled with the PCRE_EXTENDED option, whitespace in the
+pattern (other than in a character class) and characters between a "#" outside
+a character class and the next newline character are ignored. An escaping
+backslash can be used to include a whitespace or "#" character as part of the
+pattern.
+</P>
+<P>
+A second use of backslash provides a way of encoding non-printing characters
+in patterns in a visible manner. There is no restriction on the appearance of
+non-printing characters, apart from the binary zero that terminates a pattern,
+but when a pattern is being prepared by text editing, it is usually easier to
+use one of the following escape sequences than the binary character it
+represents:
+</P>
+<P>
+<PRE>
+ \a alarm, that is, the BEL character (hex 07)
+ \cx "control-x", where x is any character
+ \e escape (hex 1B)
+ \f formfeed (hex 0C)
+ \n newline (hex 0A)
+ \r carriage return (hex 0D)
+ \t tab (hex 09)
+ \xhh character with hex code hh
+ \ddd character with octal code ddd, or backreference
+</PRE>
+</P>
+<P>
+The precise effect of "\cx" is as follows: if "x" is a lower case letter, it
+is converted to upper case. Then bit 6 of the character (hex 40) is inverted.
+Thus "\cz" becomes hex 1A, but "\c{" becomes hex 3B, while "\c;" becomes hex
+7B.
+</P>
+<P>
+After "\x", up to two hexadecimal digits are read (letters can be in upper or
+lower case).
+</P>
+<P>
+After "\0" up to two further octal digits are read. In both cases, if there
+are fewer than two digits, just those that are present are used. Thus the
+sequence "\0\x\07" specifies two binary zeros followed by a BEL character.
+Make sure you supply two digits after the initial zero if the character that
+follows is itself an octal digit.
+</P>
+<P>
+The handling of a backslash followed by a digit other than 0 is complicated.
+Outside a character class, PCRE reads it and any following digits as a decimal
+number. If the number is less than 10, or if there have been at least that many
+previous capturing left parentheses in the expression, the entire sequence is
+taken as a <I>back reference</I>. A description of how this works is given
+later, following the discussion of parenthesized subpatterns.
+</P>
+<P>
+Inside a character class, or if the decimal number is greater than 9 and there
+have not been that many capturing subpatterns, PCRE re-reads up to three octal
+digits following the backslash, and generates a single byte from the least
+significant 8 bits of the value. Any subsequent digits stand for themselves.
+For example:
+</P>
+<P>
+<PRE>
+ \040 is another way of writing a space
+ \40 is the same, provided there are fewer than 40
+ previous capturing subpatterns
+ \7 is always a back reference
+ \11 might be a back reference, or another way of
+ writing a tab
+ \011 is always a tab
+ \0113 is a tab followed by the character "3"
+ \113 is the character with octal code 113 (since there
+ can be no more than 99 back references)
+ \377 is a byte consisting entirely of 1 bits
+ \81 is either a back reference, or a binary zero
+ followed by the two characters "8" and "1"
+</PRE>
+</P>
+<P>
+Note that octal values of 100 or greater must not be introduced by a leading
+zero, because no more than three octal digits are ever read.
+</P>
+<P>
+All the sequences that define a single byte value can be used both inside and
+outside character classes. In addition, inside a character class, the sequence
+"\b" is interpreted as the backspace character (hex 08). Outside a character
+class it has a different meaning (see below).
+</P>
+<P>
+The third use of backslash is for specifying generic character types:
+</P>
+<P>
+<PRE>
+ \d any decimal digit
+ \D any character that is not a decimal digit
+ \s any whitespace character
+ \S any character that is not a whitespace character
+ \w any "word" character
+ \W any "non-word" character
+</PRE>
+</P>
+<P>
+Each pair of escape sequences partitions the complete set of characters into
+two disjoint sets. Any given character matches one, and only one, of each pair.
+</P>
+<P>
+A "word" character is any letter or digit or the underscore character, that is,
+any character which can be part of a Perl "word". The definition of letters and
+digits is controlled by PCRE's character tables, and may vary if locale-
+specific matching is taking place (see "Locale support" above). For example, in
+the "fr" (French) locale, some character codes greater than 128 are used for
+accented letters, and these are matched by \w.
+</P>
+<P>
+These character type sequences can appear both inside and outside character
+classes. They each match one character of the appropriate type. If the current
+matching point is at the end of the subject string, all of them fail, since
+there is no character to match.
+</P>
+<P>
+The fourth use of backslash is for certain simple assertions. An assertion
+specifies a condition that has to be met at a particular point in a match,
+without consuming any characters from the subject string. The use of
+subpatterns for more complicated assertions is described below. The backslashed
+assertions are
+</P>
+<P>
+<PRE>
+ \b word boundary
+ \B not a word boundary
+ \A start of subject (independent of multiline mode)
+ \Z end of subject or newline at end (independent of multiline mode)
+ \z end of subject (independent of multiline mode)
+</PRE>
+</P>
+<P>
+These assertions may not appear in character classes (but note that "\b" has a
+different meaning, namely the backspace character, inside a character class).
+</P>
+<P>
+A word boundary is a position in the subject string where the current character
+and the previous character do not both match \w or \W (i.e. one matches
+\w and the other matches \W), or the start or end of the string if the
+first or last character matches \w, respectively.
+</P>
+<P>
+The \A, \Z, and \z assertions differ from the traditional circumflex and
+dollar (described below) in that they only ever match at the very start and end
+of the subject string, whatever options are set. They are not affected by the
+PCRE_NOTBOL or PCRE_NOTEOL options. If the <I>startoffset</I> argument of
+<B>pcre_exec()</B> is non-zero, \A can never match. The difference between \Z
+and \z is that \Z matches before a newline that is the last character of the
+string as well as at the end of the string, whereas \z matches only at the
+end.
+</P>
+<LI><A NAME="SEC15" HREF="#TOC1">CIRCUMFLEX AND DOLLAR</A>
+<P>
+Outside a character class, in the default matching mode, the circumflex
+character is an assertion which is true only if the current matching point is
+at the start of the subject string. If the <I>startoffset</I> argument of
+<B>pcre_exec()</B> is non-zero, circumflex can never match. Inside a character
+class, circumflex has an entirely different meaning (see below).
+</P>
+<P>
+Circumflex need not be the first character of the pattern if a number of
+alternatives are involved, but it should be the first thing in each alternative
+in which it appears if the pattern is ever to match that branch. If all
+possible alternatives start with a circumflex, that is, if the pattern is
+constrained to match only at the start of the subject, it is said to be an
+"anchored" pattern. (There are also other constructs that can cause a pattern
+to be anchored.)
+</P>
+<P>
+A dollar character is an assertion which is true only if the current matching
+point is at the end of the subject string, or immediately before a newline
+character that is the last character in the string (by default). Dollar need
+not be the last character of the pattern if a number of alternatives are
+involved, but it should be the last item in any branch in which it appears.
+Dollar has no special meaning in a character class.
+</P>
+<P>
+The meaning of dollar can be changed so that it matches only at the very end of
+the string, by setting the PCRE_DOLLAR_ENDONLY option at compile or matching
+time. This does not affect the \Z assertion.
+</P>
+<P>
+The meanings of the circumflex and dollar characters are changed if the
+PCRE_MULTILINE option is set. When this is the case, they match immediately
+after and immediately before an internal "\n" character, respectively, in
+addition to matching at the start and end of the subject string. For example,
+the pattern /^abc$/ matches the subject string "def\nabc" in multiline mode,
+but not otherwise. Consequently, patterns that are anchored in single line mode
+because all branches start with "^" are not anchored in multiline mode, and a
+match for circumflex is possible when the <I>startoffset</I> argument of
+<B>pcre_exec()</B> is non-zero. The PCRE_DOLLAR_ENDONLY option is ignored if
+PCRE_MULTILINE is set.
+</P>
+<P>
+Note that the sequences \A, \Z, and \z can be used to match the start and
+end of the subject in both modes, and if all branches of a pattern start with
+\A is it always anchored, whether PCRE_MULTILINE is set or not.
+</P>
+<LI><A NAME="SEC16" HREF="#TOC1">FULL STOP (PERIOD, DOT)</A>
+<P>
+Outside a character class, a dot in the pattern matches any one character in
+the subject, including a non-printing character, but not (by default) newline.
+If the PCRE_DOTALL option is set, then dots match newlines as well. The
+handling of dot is entirely independent of the handling of circumflex and
+dollar, the only relationship being that they both involve newline characters.
+Dot has no special meaning in a character class.
+</P>
+<LI><A NAME="SEC17" HREF="#TOC1">SQUARE BRACKETS</A>
+<P>
+An opening square bracket introduces a character class, terminated by a closing
+square bracket. A closing square bracket on its own is not special. If a
+closing square bracket is required as a member of the class, it should be the
+first data character in the class (after an initial circumflex, if present) or
+escaped with a backslash.
+</P>
+<P>
+A character class matches a single character in the subject; the character must
+be in the set of characters defined by the class, unless the first character in
+the class is a circumflex, in which case the subject character must not be in
+the set defined by the class. If a circumflex is actually required as a member
+of the class, ensure it is not the first character, or escape it with a
+backslash.
+</P>
+<P>
+For example, the character class [aeiou] matches any lower case vowel, while
+[^aeiou] matches any character that is not a lower case vowel. Note that a
+circumflex is just a convenient notation for specifying the characters which
+are in the class by enumerating those that are not. It is not an assertion: it
+still consumes a character from the subject string, and fails if the current
+pointer is at the end of the string.
+</P>
+<P>
+When caseless matching is set, any letters in a class represent both their
+upper case and lower case versions, so for example, a caseless [aeiou] matches
+"A" as well as "a", and a caseless [^aeiou] does not match "A", whereas a
+caseful version would.
+</P>
+<P>
+The newline character is never treated in any special way in character classes,
+whatever the setting of the PCRE_DOTALL or PCRE_MULTILINE options is. A class
+such as [^a] will always match a newline.
+</P>
+<P>
+The minus (hyphen) character can be used to specify a range of characters in a
+character class. For example, [d-m] matches any letter between d and m,
+inclusive. If a minus character is required in a class, it must be escaped with
+a backslash or appear in a position where it cannot be interpreted as
+indicating a range, typically as the first or last character in the class.
+</P>
+<P>
+It is not possible to have the literal character "]" as the end character of a
+range. A pattern such as [W-]46] is interpreted as a class of two characters
+("W" and "-") followed by a literal string "46]", so it would match "W46]" or
+"-46]". However, if the "]" is escaped with a backslash it is interpreted as
+the end of range, so [W-\]46] is interpreted as a single class containing a
+range followed by two separate characters. The octal or hexadecimal
+representation of "]" can also be used to end a range.
+</P>
+<P>
+Ranges operate in ASCII collating sequence. They can also be used for
+characters specified numerically, for example [\000-\037]. If a range that
+includes letters is used when caseless matching is set, it matches the letters
+in either case. For example, [W-c] is equivalent to [][\^_`wxyzabc], matched
+caselessly, and if character tables for the "fr" locale are in use,
+[\xc8-\xcb] matches accented E characters in both cases.
+</P>
+<P>
+The character types \d, \D, \s, \S, \w, and \W may also appear in a
+character class, and add the characters that they match to the class. For
+example, [\dABCDEF] matches any hexadecimal digit. A circumflex can
+conveniently be used with the upper case character types to specify a more
+restricted set of characters than the matching lower case type. For example,
+the class [^\W_] matches any letter or digit, but not underscore.
+</P>
+<P>
+All non-alphameric characters other than \, -, ^ (at the start) and the
+terminating ] are non-special in character classes, but it does no harm if they
+are escaped.
+</P>
+<LI><A NAME="SEC18" HREF="#TOC1">POSIX CHARACTER CLASSES</A>
+<P>
+Perl 5.6 (not yet released at the time of writing) is going to support the
+POSIX notation for character classes, which uses names enclosed by [: and :]
+within the enclosing square brackets. PCRE supports this notation. For example,
+</P>
+<P>
+<PRE>
+ [01[:alpha:]%]
+</PRE>
+</P>
+<P>
+matches "0", "1", any alphabetic character, or "%". The supported class names
+are
+</P>
+<P>
+<PRE>
+ alnum letters and digits
+ alpha letters
+ ascii character codes 0 - 127
+ cntrl control characters
+ digit decimal digits (same as \d)
+ graph printing characters, excluding space
+ lower lower case letters
+ print printing characters, including space
+ punct printing characters, excluding letters and digits
+ space white space (same as \s)
+ upper upper case letters
+ word "word" characters (same as \w)
+ xdigit hexadecimal digits
+</PRE>
+</P>
+<P>
+The names "ascii" and "word" are Perl extensions. Another Perl extension is
+negation, which is indicated by a ^ character after the colon. For example,
+</P>
+<P>
+<PRE>
+ [12[:^digit:]]
+</PRE>
+</P>
+<P>
+matches "1", "2", or any non-digit. PCRE (and Perl) also recogize the POSIX
+syntax [.ch.] and [=ch=] where "ch" is a "collating element", but these are not
+supported, and an error is given if they are encountered.
+</P>
+<LI><A NAME="SEC19" HREF="#TOC1">VERTICAL BAR</A>
+<P>
+Vertical bar characters are used to separate alternative patterns. For example,
+the pattern
+</P>
+<P>
+<PRE>
+ gilbert|sullivan
+</PRE>
+</P>
+<P>
+matches either "gilbert" or "sullivan". Any number of alternatives may appear,
+and an empty alternative is permitted (matching the empty string).
+The matching process tries each alternative in turn, from left to right,
+and the first one that succeeds is used. If the alternatives are within a
+subpattern (defined below), "succeeds" means matching the rest of the main
+pattern as well as the alternative in the subpattern.
+</P>
+<LI><A NAME="SEC20" HREF="#TOC1">INTERNAL OPTION SETTING</A>
+<P>
+The settings of PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, and PCRE_EXTENDED
+can be changed from within the pattern by a sequence of Perl option letters
+enclosed between "(?" and ")". The option letters are
+</P>
+<P>
+<PRE>
+ i for PCRE_CASELESS
+ m for PCRE_MULTILINE
+ s for PCRE_DOTALL
+ x for PCRE_EXTENDED
+</PRE>
+</P>
+<P>
+For example, (?im) sets caseless, multiline matching. It is also possible to
+unset these options by preceding the letter with a hyphen, and a combined
+setting and unsetting such as (?im-sx), which sets PCRE_CASELESS and
+PCRE_MULTILINE while unsetting PCRE_DOTALL and PCRE_EXTENDED, is also
+permitted. If a letter appears both before and after the hyphen, the option is
+unset.
+</P>
+<P>
+The scope of these option changes depends on where in the pattern the setting
+occurs. For settings that are outside any subpattern (defined below), the
+effect is the same as if the options were set or unset at the start of
+matching. The following patterns all behave in exactly the same way:
+</P>
+<P>
+<PRE>
+ (?i)abc
+ a(?i)bc
+ ab(?i)c
+ abc(?i)
+</PRE>
+</P>
+<P>
+which in turn is the same as compiling the pattern abc with PCRE_CASELESS set.
+In other words, such "top level" settings apply to the whole pattern (unless
+there are other changes inside subpatterns). If there is more than one setting
+of the same option at top level, the rightmost setting is used.
+</P>
+<P>
+If an option change occurs inside a subpattern, the effect is different. This
+is a change of behaviour in Perl 5.005. An option change inside a subpattern
+affects only that part of the subpattern that follows it, so
+</P>
+<P>
+<PRE>
+ (a(?i)b)c
+</PRE>
+</P>
+<P>
+matches abc and aBc and no other strings (assuming PCRE_CASELESS is not used).
+By this means, options can be made to have different settings in different
+parts of the pattern. Any changes made in one alternative do carry on
+into subsequent branches within the same subpattern. For example,
+</P>
+<P>
+<PRE>
+ (a(?i)b|c)
+</PRE>
+</P>
+<P>
+matches "ab", "aB", "c", and "C", even though when matching "C" the first
+branch is abandoned before the option setting. This is because the effects of
+option settings happen at compile time. There would be some very weird
+behaviour otherwise.
+</P>
+<P>
+The PCRE-specific options PCRE_UNGREEDY and PCRE_EXTRA can be changed in the
+same way as the Perl-compatible options by using the characters U and X
+respectively. The (?X) flag setting is special in that it must always occur
+earlier in the pattern than any of the additional features it turns on, even
+when it is at top level. It is best put at the start.
+</P>
+<LI><A NAME="SEC21" HREF="#TOC1">SUBPATTERNS</A>
+<P>
+Subpatterns are delimited by parentheses (round brackets), which can be nested.
+Marking part of a pattern as a subpattern does two things:
+</P>
+<P>
+1. It localizes a set of alternatives. For example, the pattern
+</P>
+<P>
+<PRE>
+ cat(aract|erpillar|)
+</PRE>
+</P>
+<P>
+matches one of the words "cat", "cataract", or "caterpillar". Without the
+parentheses, it would match "cataract", "erpillar" or the empty string.
+</P>
+<P>
+2. It sets up the subpattern as a capturing subpattern (as defined above).
+When the whole pattern matches, that portion of the subject string that matched
+the subpattern is passed back to the caller via the <I>ovector</I> argument of
+<B>pcre_exec()</B>. Opening parentheses are counted from left to right (starting
+from 1) to obtain the numbers of the capturing subpatterns.
+</P>
+<P>
+For example, if the string "the red king" is matched against the pattern
+</P>
+<P>
+<PRE>
+ the ((red|white) (king|queen))
+</PRE>
+</P>
+<P>
+the captured substrings are "red king", "red", and "king", and are numbered 1,
+2, and 3.
+</P>
+<P>
+The fact that plain parentheses fulfil two functions is not always helpful.
+There are often times when a grouping subpattern is required without a
+capturing requirement. If an opening parenthesis is followed by "?:", the
+subpattern does not do any capturing, and is not counted when computing the
+number of any subsequent capturing subpatterns. For example, if the string "the
+white queen" is matched against the pattern
+</P>
+<P>
+<PRE>
+ the ((?:red|white) (king|queen))
+</PRE>
+</P>
+<P>
+the captured substrings are "white queen" and "queen", and are numbered 1 and
+2. The maximum number of captured substrings is 99, and the maximum number of
+all subpatterns, both capturing and non-capturing, is 200.
+</P>
+<P>
+As a convenient shorthand, if any option settings are required at the start of
+a non-capturing subpattern, the option letters may appear between the "?" and
+the ":". Thus the two patterns
+</P>
+<P>
+<PRE>
+ (?i:saturday|sunday)
+ (?:(?i)saturday|sunday)
+</PRE>
+</P>
+<P>
+match exactly the same set of strings. Because alternative branches are tried
+from left to right, and options are not reset until the end of the subpattern
+is reached, an option setting in one branch does affect subsequent branches, so
+the above patterns match "SUNDAY" as well as "Saturday".
+</P>
+<LI><A NAME="SEC22" HREF="#TOC1">REPETITION</A>
+<P>
+Repetition is specified by quantifiers, which can follow any of the following
+items:
+</P>
+<P>
+<PRE>
+ a single character, possibly escaped
+ the . metacharacter
+ a character class
+ a back reference (see next section)
+ a parenthesized subpattern (unless it is an assertion - see below)
+</PRE>
+</P>
+<P>
+The general repetition quantifier specifies a minimum and maximum number of
+permitted matches, by giving the two numbers in curly brackets (braces),
+separated by a comma. The numbers must be less than 65536, and the first must
+be less than or equal to the second. For example:
+</P>
+<P>
+<PRE>
+ z{2,4}
+</PRE>
+</P>
+<P>
+matches "zz", "zzz", or "zzzz". A closing brace on its own is not a special
+character. If the second number is omitted, but the comma is present, there is
+no upper limit; if the second number and the comma are both omitted, the
+quantifier specifies an exact number of required matches. Thus
+</P>
+<P>
+<PRE>
+ [aeiou]{3,}
+</PRE>
+</P>
+<P>
+matches at least 3 successive vowels, but may match many more, while
+</P>
+<P>
+<PRE>
+ \d{8}
+</PRE>
+</P>
+<P>
+matches exactly 8 digits. An opening curly bracket that appears in a position
+where a quantifier is not allowed, or one that does not match the syntax of a
+quantifier, is taken as a literal character. For example, {,6} is not a
+quantifier, but a literal string of four characters.
+</P>
+<P>
+The quantifier {0} is permitted, causing the expression to behave as if the
+previous item and the quantifier were not present.
+</P>
+<P>
+For convenience (and historical compatibility) the three most common
+quantifiers have single-character abbreviations:
+</P>
+<P>
+<PRE>
+ * is equivalent to {0,}
+ + is equivalent to {1,}
+ ? is equivalent to {0,1}
+</PRE>
+</P>
+<P>
+It is possible to construct infinite loops by following a subpattern that can
+match no characters with a quantifier that has no upper limit, for example:
+</P>
+<P>
+<PRE>
+ (a?)*
+</PRE>
+</P>
+<P>
+Earlier versions of Perl and PCRE used to give an error at compile time for
+such patterns. However, because there are cases where this can be useful, such
+patterns are now accepted, but if any repetition of the subpattern does in fact
+match no characters, the loop is forcibly broken.
+</P>
+<P>
+By default, the quantifiers are "greedy", that is, they match as much as
+possible (up to the maximum number of permitted times), without causing the
+rest of the pattern to fail. The classic example of where this gives problems
+is in trying to match comments in C programs. These appear between the
+sequences /* and */ and within the sequence, individual * and / characters may
+appear. An attempt to match C comments by applying the pattern
+</P>
+<P>
+<PRE>
+ /\*.*\*/
+</PRE>
+</P>
+<P>
+to the string
+</P>
+<P>
+<PRE>
+ /* first command */ not comment /* second comment */
+</PRE>
+</P>
+<P>
+fails, because it matches the entire string due to the greediness of the .*
+item.
+</P>
+<P>
+However, if a quantifier is followed by a question mark, then it ceases to be
+greedy, and instead matches the minimum number of times possible, so the
+pattern
+</P>
+<P>
+<PRE>
+ /\*.*?\*/
+</PRE>
+</P>
+<P>
+does the right thing with the C comments. The meaning of the various
+quantifiers is not otherwise changed, just the preferred number of matches.
+Do not confuse this use of question mark with its use as a quantifier in its
+own right. Because it has two uses, it can sometimes appear doubled, as in
+</P>
+<P>
+<PRE>
+ \d??\d
+</PRE>
+</P>
+<P>
+which matches one digit by preference, but can match two if that is the only
+way the rest of the pattern matches.
+</P>
+<P>
+If the PCRE_UNGREEDY option is set (an option which is not available in Perl)
+then the quantifiers are not greedy by default, but individual ones can be made
+greedy by following them with a question mark. In other words, it inverts the
+default behaviour.
+</P>
+<P>
+When a parenthesized subpattern is quantified with a minimum repeat count that
+is greater than 1 or with a limited maximum, more store is required for the
+compiled pattern, in proportion to the size of the minimum or maximum.
+</P>
+<P>
+If a pattern starts with .* or .{0,} and the PCRE_DOTALL option (equivalent
+to Perl's /s) is set, thus allowing the . to match newlines, then the pattern
+is implicitly anchored, because whatever follows will be tried against every
+character position in the subject string, so there is no point in retrying the
+overall match at any position after the first. PCRE treats such a pattern as
+though it were preceded by \A. In cases where it is known that the subject
+string contains no newlines, it is worth setting PCRE_DOTALL when the pattern
+begins with .* in order to obtain this optimization, or alternatively using ^
+to indicate anchoring explicitly.
+</P>
+<P>
+When a capturing subpattern is repeated, the value captured is the substring
+that matched the final iteration. For example, after
+</P>
+<P>
+<PRE>
+ (tweedle[dume]{3}\s*)+
+</PRE>
+</P>
+<P>
+has matched "tweedledum tweedledee" the value of the captured substring is
+"tweedledee". However, if there are nested capturing subpatterns, the
+corresponding captured values may have been set in previous iterations. For
+example, after
+</P>
+<P>
+<PRE>
+ /(a|(b))+/
+</PRE>
+</P>
+<P>
+matches "aba" the value of the second captured substring is "b".
+</P>
+<LI><A NAME="SEC23" HREF="#TOC1">BACK REFERENCES</A>
+<P>
+Outside a character class, a backslash followed by a digit greater than 0 (and
+possibly further digits) is a back reference to a capturing subpattern earlier
+(i.e. to its left) in the pattern, provided there have been that many previous
+capturing left parentheses.
+</P>
+<P>
+However, if the decimal number following the backslash is less than 10, it is
+always taken as a back reference, and causes an error only if there are not
+that many capturing left parentheses in the entire pattern. In other words, the
+parentheses that are referenced need not be to the left of the reference for
+numbers less than 10. See the section entitled "Backslash" above for further
+details of the handling of digits following a backslash.
+</P>
+<P>
+A back reference matches whatever actually matched the capturing subpattern in
+the current subject string, rather than anything matching the subpattern
+itself. So the pattern
+</P>
+<P>
+<PRE>
+ (sens|respons)e and \1ibility
+</PRE>
+</P>
+<P>
+matches "sense and sensibility" and "response and responsibility", but not
+"sense and responsibility". If caseful matching is in force at the time of the
+back reference, then the case of letters is relevant. For example,
+</P>
+<P>
+<PRE>
+ ((?i)rah)\s+\1
+</PRE>
+</P>
+<P>
+matches "rah rah" and "RAH RAH", but not "RAH rah", even though the original
+capturing subpattern is matched caselessly.
+</P>
+<P>
+There may be more than one back reference to the same subpattern. If a
+subpattern has not actually been used in a particular match, then any back
+references to it always fail. For example, the pattern
+</P>
+<P>
+<PRE>
+ (a|(bc))\2
+</PRE>
+</P>
+<P>
+always fails if it starts to match "a" rather than "bc". Because there may be
+up to 99 back references, all digits following the backslash are taken
+as part of a potential back reference number. If the pattern continues with a
+digit character, then some delimiter must be used to terminate the back
+reference. If the PCRE_EXTENDED option is set, this can be whitespace.
+Otherwise an empty comment can be used.
+</P>
+<P>
+A back reference that occurs inside the parentheses to which it refers fails
+when the subpattern is first used, so, for example, (a\1) never matches.
+However, such references can be useful inside repeated subpatterns. For
+example, the pattern
+</P>
+<P>
+<PRE>
+ (a|b\1)+
+</PRE>
+</P>
+<P>
+matches any number of "a"s and also "aba", "ababaa" etc. At each iteration of
+the subpattern, the back reference matches the character string corresponding
+to the previous iteration. In order for this to work, the pattern must be such
+that the first iteration does not need to match the back reference. This can be
+done using alternation, as in the example above, or by a quantifier with a
+minimum of zero.
+</P>
+<LI><A NAME="SEC24" HREF="#TOC1">ASSERTIONS</A>
+<P>
+An assertion is a test on the characters following or preceding the current
+matching point that does not actually consume any characters. The simple
+assertions coded as \b, \B, \A, \Z, \z, ^ and $ are described above. More
+complicated assertions are coded as subpatterns. There are two kinds: those
+that look ahead of the current position in the subject string, and those that
+look behind it.
+</P>
+<P>
+An assertion subpattern is matched in the normal way, except that it does not
+cause the current matching position to be changed. Lookahead assertions start
+with (?= for positive assertions and (?! for negative assertions. For example,
+</P>
+<P>
+<PRE>
+ \w+(?=;)
+</PRE>
+</P>
+<P>
+matches a word followed by a semicolon, but does not include the semicolon in
+the match, and
+</P>
+<P>
+<PRE>
+ foo(?!bar)
+</PRE>
+</P>
+<P>
+matches any occurrence of "foo" that is not followed by "bar". Note that the
+apparently similar pattern
+</P>
+<P>
+<PRE>
+ (?!foo)bar
+</PRE>
+</P>
+<P>
+does not find an occurrence of "bar" that is preceded by something other than
+"foo"; it finds any occurrence of "bar" whatsoever, because the assertion
+(?!foo) is always true when the next three characters are "bar". A
+lookbehind assertion is needed to achieve this effect.
+</P>
+<P>
+Lookbehind assertions start with (?<= for positive assertions and (?<! for
+negative assertions. For example,
+</P>
+<P>
+<PRE>
+ (?<!foo)bar
+</PRE>
+</P>
+<P>
+does find an occurrence of "bar" that is not preceded by "foo". The contents of
+a lookbehind assertion are restricted such that all the strings it matches must
+have a fixed length. However, if there are several alternatives, they do not
+all have to have the same fixed length. Thus
+</P>
+<P>
+<PRE>
+ (?<=bullock|donkey)
+</PRE>
+</P>
+<P>
+is permitted, but
+</P>
+<P>
+<PRE>
+ (?<!dogs?|cats?)
+</PRE>
+</P>
+<P>
+causes an error at compile time. Branches that match different length strings
+are permitted only at the top level of a lookbehind assertion. This is an
+extension compared with Perl 5.005, which requires all branches to match the
+same length of string. An assertion such as
+</P>
+<P>
+<PRE>
+ (?<=ab(c|de))
+</PRE>
+</P>
+<P>
+is not permitted, because its single top-level branch can match two different
+lengths, but it is acceptable if rewritten to use two top-level branches:
+</P>
+<P>
+<PRE>
+ (?<=abc|abde)
+</PRE>
+</P>
+<P>
+The implementation of lookbehind assertions is, for each alternative, to
+temporarily move the current position back by the fixed width and then try to
+match. If there are insufficient characters before the current position, the
+match is deemed to fail. Lookbehinds in conjunction with once-only subpatterns
+can be particularly useful for matching at the ends of strings; an example is
+given at the end of the section on once-only subpatterns.
+</P>
+<P>
+Several assertions (of any sort) may occur in succession. For example,
+</P>
+<P>
+<PRE>
+ (?<=\d{3})(?<!999)foo
+</PRE>
+</P>
+<P>
+matches "foo" preceded by three digits that are not "999". Notice that each of
+the assertions is applied independently at the same point in the subject
+string. First there is a check that the previous three characters are all
+digits, then there is a check that the same three characters are not "999".
+This pattern does <I>not</I> match "foo" preceded by six characters, the first
+of which are digits and the last three of which are not "999". For example, it
+doesn't match "123abcfoo". A pattern to do that is
+</P>
+<P>
+<PRE>
+ (?<=\d{3}...)(?<!999)foo
+</PRE>
+</P>
+<P>
+This time the first assertion looks at the preceding six characters, checking
+that the first three are digits, and then the second assertion checks that the
+preceding three characters are not "999".
+</P>
+<P>
+Assertions can be nested in any combination. For example,
+</P>
+<P>
+<PRE>
+ (?<=(?<!foo)bar)baz
+</PRE>
+</P>
+<P>
+matches an occurrence of "baz" that is preceded by "bar" which in turn is not
+preceded by "foo", while
+</P>
+<P>
+<PRE>
+ (?<=\d{3}(?!999)...)foo
+</PRE>
+</P>
+<P>
+is another pattern which matches "foo" preceded by three digits and any three
+characters that are not "999".
+</P>
+<P>
+Assertion subpatterns are not capturing subpatterns, and may not be repeated,
+because it makes no sense to assert the same thing several times. If any kind
+of assertion contains capturing subpatterns within it, these are counted for
+the purposes of numbering the capturing subpatterns in the whole pattern.
+However, substring capturing is carried out only for positive assertions,
+because it does not make sense for negative assertions.
+</P>
+<P>
+Assertions count towards the maximum of 200 parenthesized subpatterns.
+</P>
+<LI><A NAME="SEC25" HREF="#TOC1">ONCE-ONLY SUBPATTERNS</A>
+<P>
+With both maximizing and minimizing repetition, failure of what follows
+normally causes the repeated item to be re-evaluated to see if a different
+number of repeats allows the rest of the pattern to match. Sometimes it is
+useful to prevent this, either to change the nature of the match, or to cause
+it fail earlier than it otherwise might, when the author of the pattern knows
+there is no point in carrying on.
+</P>
+<P>
+Consider, for example, the pattern \d+foo when applied to the subject line
+</P>
+<P>
+<PRE>
+ 123456bar
+</PRE>
+</P>
+<P>
+After matching all 6 digits and then failing to match "foo", the normal
+action of the matcher is to try again with only 5 digits matching the \d+
+item, and then with 4, and so on, before ultimately failing. Once-only
+subpatterns provide the means for specifying that once a portion of the pattern
+has matched, it is not to be re-evaluated in this way, so the matcher would
+give up immediately on failing to match "foo" the first time. The notation is
+another kind of special parenthesis, starting with (?> as in this example:
+</P>
+<P>
+<PRE>
+ (?>\d+)bar
+</PRE>
+</P>
+<P>
+This kind of parenthesis "locks up" the part of the pattern it contains once
+it has matched, and a failure further into the pattern is prevented from
+backtracking into it. Backtracking past it to previous items, however, works as
+normal.
+</P>
+<P>
+An alternative description is that a subpattern of this type matches the string
+of characters that an identical standalone pattern would match, if anchored at
+the current point in the subject string.
+</P>
+<P>
+Once-only subpatterns are not capturing subpatterns. Simple cases such as the
+above example can be thought of as a maximizing repeat that must swallow
+everything it can. So, while both \d+ and \d+? are prepared to adjust the
+number of digits they match in order to make the rest of the pattern match,
+(?>\d+) can only match an entire sequence of digits.
+</P>
+<P>
+This construction can of course contain arbitrarily complicated subpatterns,
+and it can be nested.
+</P>
+<P>
+Once-only subpatterns can be used in conjunction with lookbehind assertions to
+specify efficient matching at the end of the subject string. Consider a simple
+pattern such as
+</P>
+<P>
+<PRE>
+ abcd$
+</PRE>
+</P>
+<P>
+when applied to a long string which does not match. Because matching proceeds
+from left to right, PCRE will look for each "a" in the subject and then see if
+what follows matches the rest of the pattern. If the pattern is specified as
+</P>
+<P>
+<PRE>
+ ^.*abcd$
+</PRE>
+</P>
+<P>
+then the initial .* matches the entire string at first, but when this fails
+(because there is no following "a"), it backtracks to match all but the last
+character, then all but the last two characters, and so on. Once again the
+search for "a" covers the entire string, from right to left, so we are no
+better off. However, if the pattern is written as
+</P>
+<P>
+<PRE>
+ ^(?>.*)(?<=abcd)
+</PRE>
+</P>
+<P>
+then there can be no backtracking for the .* item; it can match only the entire
+string. The subsequent lookbehind assertion does a single test on the last four
+characters. If it fails, the match fails immediately. For long strings, this
+approach makes a significant difference to the processing time.
+</P>
+<P>
+When a pattern contains an unlimited repeat inside a subpattern that can itself
+be repeated an unlimited number of times, the use of a once-only subpattern is
+the only way to avoid some failing matches taking a very long time indeed.
+The pattern
+</P>
+<P>
+<PRE>
+ (\D+|<\d+>)*[!?]
+</PRE>
+</P>
+<P>
+matches an unlimited number of substrings that either consist of non-digits, or
+digits enclosed in <>, followed by either ! or ?. When it matches, it runs
+quickly. However, if it is applied to
+</P>
+<P>
+<PRE>
+ aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+</PRE>
+</P>
+<P>
+it takes a long time before reporting failure. This is because the string can
+be divided between the two repeats in a large number of ways, and all have to
+be tried. (The example used [!?] rather than a single character at the end,
+because both PCRE and Perl have an optimization that allows for fast failure
+when a single character is used. They remember the last single character that
+is required for a match, and fail early if it is not present in the string.)
+If the pattern is changed to
+</P>
+<P>
+<PRE>
+ ((?>\D+)|<\d+>)*[!?]
+</PRE>
+</P>
+<P>
+sequences of non-digits cannot be broken, and failure happens quickly.
+</P>
+<LI><A NAME="SEC26" HREF="#TOC1">CONDITIONAL SUBPATTERNS</A>
+<P>
+It is possible to cause the matching process to obey a subpattern
+conditionally or to choose between two alternative subpatterns, depending on
+the result of an assertion, or whether a previous capturing subpattern matched
+or not. The two possible forms of conditional subpattern are
+</P>
+<P>
+<PRE>
+ (?(condition)yes-pattern)
+ (?(condition)yes-pattern|no-pattern)
+</PRE>
+</P>
+<P>
+If the condition is satisfied, the yes-pattern is used; otherwise the
+no-pattern (if present) is used. If there are more than two alternatives in the
+subpattern, a compile-time error occurs.
+</P>
+<P>
+There are two kinds of condition. If the text between the parentheses consists
+of a sequence of digits, then the condition is satisfied if the capturing
+subpattern of that number has previously matched. Consider the following
+pattern, which contains non-significant white space to make it more readable
+(assume the PCRE_EXTENDED option) and to divide it into three parts for ease
+of discussion:
+</P>
+<P>
+<PRE>
+ ( \( )? [^()]+ (?(1) \) )
+</PRE>
+</P>
+<P>
+The first part matches an optional opening parenthesis, and if that
+character is present, sets it as the first captured substring. The second part
+matches one or more characters that are not parentheses. The third part is a
+conditional subpattern that tests whether the first set of parentheses matched
+or not. If they did, that is, if subject started with an opening parenthesis,
+the condition is true, and so the yes-pattern is executed and a closing
+parenthesis is required. Otherwise, since no-pattern is not present, the
+subpattern matches nothing. In other words, this pattern matches a sequence of
+non-parentheses, optionally enclosed in parentheses.
+</P>
+<P>
+If the condition is not a sequence of digits, it must be an assertion. This may
+be a positive or negative lookahead or lookbehind assertion. Consider this
+pattern, again containing non-significant white space, and with the two
+alternatives on the second line:
+</P>
+<P>
+<PRE>
+ (?(?=[^a-z]*[a-z])
+ \d{2}-[a-z]{3}-\d{2} | \d{2}-\d{2}-\d{2} )
+</PRE>
+</P>
+<P>
+The condition is a positive lookahead assertion that matches an optional
+sequence of non-letters followed by a letter. In other words, it tests for the
+presence of at least one letter in the subject. If a letter is found, the
+subject is matched against the first alternative; otherwise it is matched
+against the second. This pattern matches strings in one of the two forms
+dd-aaa-dd or dd-dd-dd, where aaa are letters and dd are digits.
+</P>
+<LI><A NAME="SEC27" HREF="#TOC1">COMMENTS</A>
+<P>
+The sequence (?# marks the start of a comment which continues up to the next
+closing parenthesis. Nested parentheses are not permitted. The characters
+that make up a comment play no part in the pattern matching at all.
+</P>
+<P>
+If the PCRE_EXTENDED option is set, an unescaped # character outside a
+character class introduces a comment that continues up to the next newline
+character in the pattern.
+</P>
+<LI><A NAME="SEC28" HREF="#TOC1">RECURSIVE PATTERNS</A>
+<P>
+Consider the problem of matching a string in parentheses, allowing for
+unlimited nested parentheses. Without the use of recursion, the best that can
+be done is to use a pattern that matches up to some fixed depth of nesting. It
+is not possible to handle an arbitrary nesting depth. Perl 5.6 has provided an
+experimental facility that allows regular expressions to recurse (amongst other
+things). It does this by interpolating Perl code in the expression at run time,
+and the code can refer to the expression itself. A Perl pattern to solve the
+parentheses problem can be created like this:
+</P>
+<P>
+<PRE>
+ $re = qr{\( (?: (?>[^()]+) | (?p{$re}) )* \)}x;
+</PRE>
+</P>
+<P>
+The (?p{...}) item interpolates Perl code at run time, and in this case refers
+recursively to the pattern in which it appears. Obviously, PCRE cannot support
+the interpolation of Perl code. Instead, the special item (?R) is provided for
+the specific case of recursion. This PCRE pattern solves the parentheses
+problem (assume the PCRE_EXTENDED option is set so that white space is
+ignored):
+</P>
+<P>
+<PRE>
+ \( ( (?>[^()]+) | (?R) )* \)
+</PRE>
+</P>
+<P>
+First it matches an opening parenthesis. Then it matches any number of
+substrings which can either be a sequence of non-parentheses, or a recursive
+match of the pattern itself (i.e. a correctly parenthesized substring). Finally
+there is a closing parenthesis.
+</P>
+<P>
+This particular example pattern contains nested unlimited repeats, and so the
+use of a once-only subpattern for matching strings of non-parentheses is
+important when applying the pattern to strings that do not match. For example,
+when it is applied to
+</P>
+<P>
+<PRE>
+ (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa()
+</PRE>
+</P>
+<P>
+it yields "no match" quickly. However, if a once-only subpattern is not used,
+the match runs for a very long time indeed because there are so many different
+ways the + and * repeats can carve up the subject, and all have to be tested
+before failure can be reported.
+</P>
+<P>
+The values set for any capturing subpatterns are those from the outermost level
+of the recursion at which the subpattern value is set. If the pattern above is
+matched against
+</P>
+<P>
+<PRE>
+ (ab(cd)ef)
+</PRE>
+</P>
+<P>
+the value for the capturing parentheses is "ef", which is the last value taken
+on at the top level. If additional parentheses are added, giving
+</P>
+<P>
+<PRE>
+ \( ( ( (?>[^()]+) | (?R) )* ) \)
+ ^ ^
+ ^ ^
+</PRE>
+then the string they capture is "ab(cd)ef", the contents of the top level
+parentheses. If there are more than 15 capturing parentheses in a pattern, PCRE
+has to obtain extra memory to store data during a recursion, which it does by
+using <B>pcre_malloc</B>, freeing it via <B>pcre_free</B> afterwards. If no
+memory can be obtained, it saves data for the first 15 capturing parentheses
+only, as there is no way to give an out-of-memory error from within a
+recursion.
+</P>
+<LI><A NAME="SEC29" HREF="#TOC1">PERFORMANCE</A>
+<P>
+Certain items that may appear in patterns are more efficient than others. It is
+more efficient to use a character class like [aeiou] than a set of alternatives
+such as (a|e|i|o|u). In general, the simplest construction that provides the
+required behaviour is usually the most efficient. Jeffrey Friedl's book
+contains a lot of discussion about optimizing regular expressions for efficient
+performance.
+</P>
+<P>
+When a pattern begins with .* and the PCRE_DOTALL option is set, the pattern is
+implicitly anchored by PCRE, since it can match only at the start of a subject
+string. However, if PCRE_DOTALL is not set, PCRE cannot make this optimization,
+because the . metacharacter does not then match a newline, and if the subject
+string contains newlines, the pattern may match from the character immediately
+following one of them instead of from the very start. For example, the pattern
+</P>
+<P>
+<PRE>
+ (.*) second
+</PRE>
+</P>
+<P>
+matches the subject "first\nand second" (where \n stands for a newline
+character) with the first captured substring being "and". In order to do this,
+PCRE has to retry the match starting after every newline in the subject.
+</P>
+<P>
+If you are using such a pattern with subject strings that do not contain
+newlines, the best performance is obtained by setting PCRE_DOTALL, or starting
+the pattern with ^.* to indicate explicit anchoring. That saves PCRE from
+having to scan along the subject looking for a newline to restart at.
+</P>
+<P>
+Beware of patterns that contain nested indefinite repeats. These can take a
+long time to run when applied to a string that does not match. Consider the
+pattern fragment
+</P>
+<P>
+<PRE>
+ (a+)*
+</PRE>
+</P>
+<P>
+This can match "aaaa" in 33 different ways, and this number increases very
+rapidly as the string gets longer. (The * repeat can match 0, 1, 2, 3, or 4
+times, and for each of those cases other than 0, the + repeats can match
+different numbers of times.) When the remainder of the pattern is such that the
+entire match is going to fail, PCRE has in principle to try every possible
+variation, and this can take an extremely long time.
+</P>
+<P>
+An optimization catches some of the more simple cases such as
+</P>
+<P>
+<PRE>
+ (a+)*b
+</PRE>
+</P>
+<P>
+where a literal character follows. Before embarking on the standard matching
+procedure, PCRE checks that there is a "b" later in the subject string, and if
+there is not, it fails the match immediately. However, when there is no
+following literal this optimization cannot be used. You can see the difference
+by comparing the behaviour of
+</P>
+<P>
+<PRE>
+ (a+)*\d
+</PRE>
+</P>
+<P>
+with the pattern above. The former gives a failure almost instantly when
+applied to a whole line of "a" characters, whereas the latter takes an
+appreciable time with strings longer than about 20 characters.
+</P>
+<LI><A NAME="SEC30" HREF="#TOC1">AUTHOR</A>
+<P>
+Philip Hazel <ph10@cam.ac.uk>
+<BR>
+University Computing Service,
+<BR>
+New Museums Site,
+<BR>
+Cambridge CB2 3QG, England.
+<BR>
+Phone: +44 1223 334714
+</P>
+<P>
+Last updated: 27 January 2000
+<BR>
+Copyright (c) 1997-2000 University of Cambridge.
--- /dev/null
+NAME
+ pcre - Perl-compatible regular expressions.
+
+
+
+SYNOPSIS
+ #include <pcre.h>
+
+ pcre *pcre_compile(const char *pattern, int options,
+ const char **errptr, int *erroffset,
+ const unsigned char *tableptr);
+
+ pcre_extra *pcre_study(const pcre *code, int options,
+ const char **errptr);
+
+ int pcre_exec(const pcre *code, const pcre_extra *extra,
+ const char *subject, int length, int startoffset,
+ int options, int *ovector, int ovecsize);
+
+ int pcre_copy_substring(const char *subject, int *ovector,
+ int stringcount, int stringnumber, char *buffer,
+ int buffersize);
+
+ int pcre_get_substring(const char *subject, int *ovector,
+ int stringcount, int stringnumber,
+ const char **stringptr);
+
+ int pcre_get_substring_list(const char *subject,
+ int *ovector, int stringcount, const char ***listptr);
+
+ const unsigned char *pcre_maketables(void);
+
+ int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
+ int what, void *where);
+
+ int pcre_info(const pcre *code, int *optptr, *firstcharptr);
+
+ char *pcre_version(void);
+
+ void *(*pcre_malloc)(size_t);
+
+ void (*pcre_free)(void *);
+
+
+
+
+DESCRIPTION
+ The PCRE library is a set of functions that implement regu-
+ lar expression pattern matching using the same syntax and
+ semantics as Perl 5, with just a few differences (see
+ below). The current implementation corresponds to Perl
+ 5.005, with some additional features from the Perl develop-
+ ment release.
+
+ PCRE has its own native API, which is described in this
+ document. There is also a set of wrapper functions that
+ correspond to the POSIX regular expression API. These are
+ described in the pcreposix documentation.
+
+ The native API function prototypes are defined in the header
+ file pcre.h, and on Unix systems the library itself is
+ called libpcre.a, so can be accessed by adding -lpcre to the
+ command for linking an application which calls it. The
+ header file defines the macros PCRE_MAJOR and PCRE_MINOR to
+ contain the major and minor release numbers for the library.
+ Applications can use these to include support for different
+ releases.
+
+ The functions pcre_compile(), pcre_study(), and pcre_exec()
+ are used for compiling and matching regular expressions,
+ while pcre_copy_substring(), pcre_get_substring(), and
+ pcre_get_substring_list() are convenience functions for
+ extracting captured substrings from a matched subject
+ string. The function pcre_maketables() is used (optionally)
+ to build a set of character tables in the current locale for
+ passing to pcre_compile().
+
+ The function pcre_fullinfo() is used to find out information
+ about a compiled pattern; pcre_info() is an obsolete version
+ which returns only some of the available information, but is
+ retained for backwards compatibility. The function
+ pcre_version() returns a pointer to a string containing the
+ version of PCRE and its date of release.
+
+ The global variables pcre_malloc and pcre_free initially
+ contain the entry points of the standard malloc() and free()
+ functions respectively. PCRE calls the memory management
+ functions via these variables, so a calling program can
+ replace them if it wishes to intercept the calls. This
+ should be done before calling any PCRE functions.
+
+
+
+MULTI-THREADING
+ The PCRE functions can be used in multi-threading applica-
+ tions, with the proviso that the memory management functions
+ pointed to by pcre_malloc and pcre_free are shared by all
+ threads.
+
+ The compiled form of a regular expression is not altered
+ during matching, so the same compiled pattern can safely be
+ used by several threads at once.
+
+
+
+
+COMPILING A PATTERN
+ The function pcre_compile() is called to compile a pattern
+ into an internal form. The pattern is a C string terminated
+ by a binary zero, and is passed in the argument pattern. A
+ pointer to a single block of memory that is obtained via
+ pcre_malloc is returned. This contains the compiled code and
+ related data. The pcre type is defined for this for conveni-
+ ence, but in fact pcre is just a typedef for void, since the
+ contents of the block are not externally defined. It is up
+ to the caller to free the memory when it is no longer
+ required.
+
+ The size of a compiled pattern is roughly proportional to
+ the length of the pattern string, except that each character
+ class (other than those containing just a single character,
+ negated or not) requires 33 bytes, and repeat quantifiers
+ with a minimum greater than one or a bounded maximum cause
+ the relevant portions of the compiled pattern to be repli-
+ cated.
+
+ The options argument contains independent bits that affect
+ the compilation. It should be zero if no options are
+ required. Some of the options, in particular, those that are
+ compatible with Perl, can also be set and unset from within
+ the pattern (see the detailed description of regular expres-
+ sions below). For these options, the contents of the options
+ argument specifies their initial settings at the start of
+ compilation and execution. The PCRE_ANCHORED option can be
+ set at the time of matching as well as at compile time.
+
+ If errptr is NULL, pcre_compile() returns NULL immediately.
+ Otherwise, if compilation of a pattern fails, pcre_compile()
+ returns NULL, and sets the variable pointed to by errptr to
+ point to a textual error message. The offset from the start
+ of the pattern to the character where the error was
+ discovered is placed in the variable pointed to by
+ erroffset, which must not be NULL. If it is, an immediate
+ error is given.
+
+ If the final argument, tableptr, is NULL, PCRE uses a
+ default set of character tables which are built when it is
+ compiled, using the default C locale. Otherwise, tableptr
+ must be the result of a call to pcre_maketables(). See the
+ section on locale support below.
+
+ The following option bits are defined in the header file:
+
+ PCRE_ANCHORED
+
+ If this bit is set, the pattern is forced to be "anchored",
+ that is, it is constrained to match only at the start of the
+ string which is being searched (the "subject string"). This
+ effect can also be achieved by appropriate constructs in the
+ pattern itself, which is the only way to do it in Perl.
+
+ PCRE_CASELESS
+
+ If this bit is set, letters in the pattern match both upper
+ and lower case letters. It is equivalent to Perl's /i
+ option.
+
+ PCRE_DOLLAR_ENDONLY
+
+ If this bit is set, a dollar metacharacter in the pattern
+ matches only at the end of the subject string. Without this
+ option, a dollar also matches immediately before the final
+ character if it is a newline (but not before any other new-
+ lines). The PCRE_DOLLAR_ENDONLY option is ignored if
+ PCRE_MULTILINE is set. There is no equivalent to this option
+ in Perl.
+
+ PCRE_DOTALL
+
+ If this bit is set, a dot metacharater in the pattern
+ matches all characters, including newlines. Without it, new-
+ lines are excluded. This option is equivalent to Perl's /s
+ option. A negative class such as [^a] always matches a new-
+ line character, independent of the setting of this option.
+
+ PCRE_EXTENDED
+
+ If this bit is set, whitespace data characters in the pat-
+ tern are totally ignored except when escaped or inside a
+ character class, and characters between an unescaped # out-
+ side a character class and the next newline character,
+ inclusive, are also ignored. This is equivalent to Perl's /x
+ option, and makes it possible to include comments inside
+ complicated patterns. Note, however, that this applies only
+ to data characters. Whitespace characters may never appear
+ within special character sequences in a pattern, for example
+ within the sequence (?( which introduces a conditional sub-
+ pattern.
+
+ PCRE_EXTRA
+
+ This option was invented in order to turn on additional
+ functionality of PCRE that is incompatible with Perl, but it
+ is currently of very little use. When set, any backslash in
+ a pattern that is followed by a letter that has no special
+ meaning causes an error, thus reserving these combinations
+ for future expansion. By default, as in Perl, a backslash
+ followed by a letter with no special meaning is treated as a
+ literal. There are at present no other features controlled
+ by this option. It can also be set by a (?X) option setting
+ within a pattern.
+
+ PCRE_MULTILINE
+
+ By default, PCRE treats the subject string as consisting of
+ a single "line" of characters (even if it actually contains
+ several newlines). The "start of line" metacharacter (^)
+ matches only at the start of the string, while the "end of
+ line" metacharacter ($) matches only at the end of the
+ string, or before a terminating newline (unless
+ PCRE_DOLLAR_ENDONLY is set). This is the same as Perl.
+
+ When PCRE_MULTILINE it is set, the "start of line" and "end
+ of line" constructs match immediately following or immedi-
+ ately before any newline in the subject string, respec-
+ tively, as well as at the very start and end. This is
+ equivalent to Perl's /m option. If there are no "\n" charac-
+ ters in a subject string, or no occurrences of ^ or $ in a
+ pattern, setting PCRE_MULTILINE has no effect.
+
+ PCRE_UNGREEDY
+
+ This option inverts the "greediness" of the quantifiers so
+ that they are not greedy by default, but become greedy if
+ followed by "?". It is not compatible with Perl. It can also
+ be set by a (?U) option setting within the pattern.
+
+
+
+STUDYING A PATTERN
+ When a pattern is going to be used several times, it is
+ worth spending more time analyzing it in order to speed up
+ the time taken for matching. The function pcre_study() takes
+ a pointer to a compiled pattern as its first argument, and
+ returns a pointer to a pcre_extra block (another void
+ typedef) containing additional information about the pat-
+ tern; this can be passed to pcre_exec(). If no additional
+ information is available, NULL is returned.
+
+ The second argument contains option bits. At present, no
+ options are defined for pcre_study(), and this argument
+ should always be zero.
+
+ The third argument for pcre_study() is a pointer to an error
+ message. If studying succeeds (even if no data is returned),
+ the variable it points to is set to NULL. Otherwise it
+ points to a textual error message.
+
+ At present, studying a pattern is useful only for non-
+ anchored patterns that do not have a single fixed starting
+ character. A bitmap of possible starting characters is
+ created.
+
+
+
+LOCALE SUPPORT
+ PCRE handles caseless matching, and determines whether char-
+ acters are letters, digits, or whatever, by reference to a
+ set of tables. The library contains a default set of tables
+ which is created in the default C locale when PCRE is com-
+ piled. This is used when the final argument of
+ pcre_compile() is NULL, and is sufficient for many applica-
+ tions.
+
+ An alternative set of tables can, however, be supplied. Such
+ tables are built by calling the pcre_maketables() function,
+ which has no arguments, in the relevant locale. The result
+ can then be passed to pcre_compile() as often as necessary.
+ For example, to build and use tables that are appropriate
+ for the French locale (where accented characters with codes
+ greater than 128 are treated as letters), the following code
+ could be used:
+
+ setlocale(LC_CTYPE, "fr");
+ tables = pcre_maketables();
+ re = pcre_compile(..., tables);
+
+ The tables are built in memory that is obtained via
+ pcre_malloc. The pointer that is passed to pcre_compile is
+ saved with the compiled pattern, and the same tables are
+ used via this pointer by pcre_study() and pcre_exec(). Thus
+ for any single pattern, compilation, studying and matching
+ all happen in the same locale, but different patterns can be
+ compiled in different locales. It is the caller's responsi-
+ bility to ensure that the memory containing the tables
+ remains available for as long as it is needed.
+
+
+
+INFORMATION ABOUT A PATTERN
+ The pcre_fullinfo() function returns information about a
+ compiled pattern. It replaces the obsolete pcre_info() func-
+ tion, which is nevertheless retained for backwards compabil-
+ ity (and is documented below).
+
+ The first argument for pcre_fullinfo() is a pointer to the
+ compiled pattern. The second argument is the result of
+ pcre_study(), or NULL if the pattern was not studied. The
+ third argument specifies which piece of information is
+ required, while the fourth argument is a pointer to a vari-
+ able to receive the data. The yield of the function is zero
+ for success, or one of the following negative numbers:
+
+ PCRE_ERROR_NULL the argument code was NULL
+ the argument where was NULL
+ PCRE_ERROR_BADMAGIC the "magic number" was not found
+ PCRE_ERROR_BADOPTION the value of what was invalid
+
+ The possible values for the third argument are defined in
+ pcre.h, and are as follows:
+
+ PCRE_INFO_OPTIONS
+
+ Return a copy of the options with which the pattern was com-
+ piled. The fourth argument should point to au unsigned long
+ int variable. These option bits are those specified in the
+ call to pcre_compile(), modified by any top-level option
+ settings within the pattern itself, and with the
+ PCRE_ANCHORED bit forcibly set if the form of the pattern
+ implies that it can match only at the start of a subject
+ string.
+
+ PCRE_INFO_SIZE
+
+ Return the size of the compiled pattern, that is, the value
+ that was passed as the argument to pcre_malloc() when PCRE
+ was getting memory in which to place the compiled data. The
+ fourth argument should point to a size_t variable.
+
+ PCRE_INFO_CAPTURECOUNT
+
+ Return the number of capturing subpatterns in the pattern.
+ The fourth argument should point to an int variable.
+
+ PCRE_INFO_BACKREFMAX
+
+ Return the number of the highest back reference in the pat-
+ tern. The fourth argument should point to an int variable.
+ Zero is returned if there are no back references.
+
+ PCRE_INFO_FIRSTCHAR
+
+ Return information about the first character of any matched
+ string, for a non-anchored pattern. If there is a fixed
+ first character, e.g. from a pattern such as
+ (cat|cow|coyote), then it is returned in the integer pointed
+ to by where. Otherwise, if either
+
+ (a) the pattern was compiled with the PCRE_MULTILINE option,
+ and every branch starts with "^", or
+
+ (b) every branch of the pattern starts with ".*" and
+ PCRE_DOTALL is not set (if it were set, the pattern would be
+ anchored),
+
+ then -1 is returned, indicating that the pattern matches
+ only at the start of a subject string or after any "\n"
+ within the string. Otherwise -2 is returned. For anchored
+ patterns, -2 is returned.
+
+ PCRE_INFO_FIRSTTABLE
+
+ If the pattern was studied, and this resulted in the con-
+ struction of a 256-bit table indicating a fixed set of char-
+ acters for the first character in any matching string, a
+ pointer to the table is returned. Otherwise NULL is
+ returned. The fourth argument should point to an unsigned
+ char * variable.
+
+ PCRE_INFO_LASTLITERAL
+
+ For a non-anchored pattern, return the value of the right-
+ most literal character which must exist in any matched
+ string, other than at its start. The fourth argument should
+ point to an int variable. If there is no such character, or
+ if the pattern is anchored, -1 is returned. For example, for
+ the pattern /a\d+z\d+/ the returned value is 'z'.
+
+ The pcre_info() function is now obsolete because its inter-
+ face is too restrictive to return all the available data
+ about a compiled pattern. New programs should use
+ pcre_fullinfo() instead. The yield of pcre_info() is the
+ number of capturing subpatterns, or one of the following
+ negative numbers:
+
+ PCRE_ERROR_NULL the argument code was NULL
+ PCRE_ERROR_BADMAGIC the "magic number" was not found
+
+ If the optptr argument is not NULL, a copy of the options
+ with which the pattern was compiled is placed in the integer
+ it points to (see PCRE_INFO_OPTIONS above).
+
+ If the pattern is not anchored and the firstcharptr argument
+ is not NULL, it is used to pass back information about the
+ first character of any matched string (see
+ PCRE_INFO_FIRSTCHAR above).
+
+
+
+MATCHING A PATTERN
+ The function pcre_exec() is called to match a subject string
+ against a pre-compiled pattern, which is passed in the code
+ argument. If the pattern has been studied, the result of the
+ study should be passed in the extra argument. Otherwise this
+ must be NULL.
+
+ The PCRE_ANCHORED option can be passed in the options argu-
+ ment, whose unused bits must be zero. However, if a pattern
+ was compiled with PCRE_ANCHORED, or turned out to be
+ anchored by virtue of its contents, it cannot be made
+ unachored at matching time.
+
+ There are also three further options that can be set only at
+ matching time:
+
+ PCRE_NOTBOL
+
+ The first character of the string is not the beginning of a
+ line, so the circumflex metacharacter should not match
+ before it. Setting this without PCRE_MULTILINE (at compile
+ time) causes circumflex never to match.
+
+ PCRE_NOTEOL
+
+ The end of the string is not the end of a line, so the dol-
+ lar metacharacter should not match it nor (except in multi-
+ line mode) a newline immediately before it. Setting this
+ without PCRE_MULTILINE (at compile time) causes dollar never
+ to match.
+
+ PCRE_NOTEMPTY
+
+ An empty string is not considered to be a valid match if
+ this option is set. If there are alternatives in the pat-
+ tern, they are tried. If all the alternatives match the
+ empty string, the entire match fails. For example, if the
+ pattern
+
+ a?b?
+
+ is applied to a string not beginning with "a" or "b", it
+ matches the empty string at the start of the subject. With
+ PCRE_NOTEMPTY set, this match is not valid, so PCRE searches
+ further into the string for occurrences of "a" or "b".
+
+ Perl has no direct equivalent of PCRE_NOTEMPTY, but it does
+ make a special case of a pattern match of the empty string
+ within its split() function, and when using the /g modifier.
+ It is possible to emulate Perl's behaviour after matching a
+ null string by first trying the match again at the same
+ offset with PCRE_NOTEMPTY set, and then if that fails by
+ advancing the starting offset (see below) and trying an
+ ordinary match again.
+
+ The subject string is passed as a pointer in subject, a
+ length in length, and a starting offset in startoffset.
+ Unlike the pattern string, it may contain binary zero char-
+ acters. When the starting offset is zero, the search for a
+ match starts at the beginning of the subject, and this is by
+ far the most common case.
+
+ A non-zero starting offset is useful when searching for
+ another match in the same subject by calling pcre_exec()
+ again after a previous success. Setting startoffset differs
+ from just passing over a shortened string and setting
+ PCRE_NOTBOL in the case of a pattern that begins with any
+ kind of lookbehind. For example, consider the pattern
+
+ \Biss\B
+
+ which finds occurrences of "iss" in the middle of words. (\B
+ matches only if the current position in the subject is not a
+ word boundary.) When applied to the string "Mississipi" the
+ first call to pcre_exec() finds the first occurrence. If
+ pcre_exec() is called again with just the remainder of the
+ subject, namely "issipi", it does not match, because \B is
+ always false at the start of the subject, which is deemed to
+ be a word boundary. However, if pcre_exec() is passed the
+ entire string again, but with startoffset set to 4, it finds
+ the second occurrence of "iss" because it is able to look
+ behind the starting point to discover that it is preceded by
+ a letter.
+
+ If a non-zero starting offset is passed when the pattern is
+ anchored, one attempt to match at the given offset is tried.
+ This can only succeed if the pattern does not require the
+ match to be at the start of the subject.
+
+ In general, a pattern matches a certain portion of the sub-
+ ject, and in addition, further substrings from the subject
+ may be picked out by parts of the pattern. Following the
+ usage in Jeffrey Friedl's book, this is called "capturing"
+ in what follows, and the phrase "capturing subpattern" is
+ used for a fragment of a pattern that picks out a substring.
+ PCRE supports several other kinds of parenthesized subpat-
+ tern that do not cause substrings to be captured.
+
+ Captured substrings are returned to the caller via a vector
+ of integer offsets whose address is passed in ovector. The
+ number of elements in the vector is passed in ovecsize. The
+ first two-thirds of the vector is used to pass back captured
+ substrings, each substring using a pair of integers. The
+ remaining third of the vector is used as workspace by
+ pcre_exec() while matching capturing subpatterns, and is not
+ available for passing back information. The length passed in
+ ovecsize should always be a multiple of three. If it is not,
+ it is rounded down.
+
+ When a match has been successful, information about captured
+ substrings is returned in pairs of integers, starting at the
+ beginning of ovector, and continuing up to two-thirds of its
+ length at the most. The first element of a pair is set to
+ the offset of the first character in a substring, and the
+ second is set to the offset of the first character after the
+ end of a substring. The first pair, ovector[0] and ovec-
+ tor[1], identify the portion of the subject string matched
+ by the entire pattern. The next pair is used for the first
+ capturing subpattern, and so on. The value returned by
+ pcre_exec() is the number of pairs that have been set. If
+ there are no capturing subpatterns, the return value from a
+ successful match is 1, indicating that just the first pair
+ of offsets has been set.
+
+ Some convenience functions are provided for extracting the
+ captured substrings as separate strings. These are described
+ in the following section.
+
+ It is possible for an capturing subpattern number n+1 to
+ match some part of the subject when subpattern n has not
+ been used at all. For example, if the string "abc" is
+ matched against the pattern (a|(z))(bc) subpatterns 1 and 3
+ are matched, but 2 is not. When this happens, both offset
+ values corresponding to the unused subpattern are set to -1.
+
+ If a capturing subpattern is matched repeatedly, it is the
+ last portion of the string that it matched that gets
+ returned.
+
+ If the vector is too small to hold all the captured sub-
+ strings, it is used as far as possible (up to two-thirds of
+ its length), and the function returns a value of zero. In
+ particular, if the substring offsets are not of interest,
+ pcre_exec() may be called with ovector passed as NULL and
+ ovecsize as zero. However, if the pattern contains back
+ references and the ovector isn't big enough to remember the
+ related substrings, PCRE has to get additional memory for
+ use during matching. Thus it is usually advisable to supply
+ an ovector.
+
+ Note that pcre_info() can be used to find out how many cap-
+ turing subpatterns there are in a compiled pattern. The
+ smallest size for ovector that will allow for n captured
+ substrings in addition to the offsets of the substring
+ matched by the whole pattern is (n+1)*3.
+
+ If pcre_exec() fails, it returns a negative number. The fol-
+ lowing are defined in the header file:
+
+ PCRE_ERROR_NOMATCH (-1)
+
+ The subject string did not match the pattern.
+
+ PCRE_ERROR_NULL (-2)
+
+ Either code or subject was passed as NULL, or ovector was
+ NULL and ovecsize was not zero.
+
+ PCRE_ERROR_BADOPTION (-3)
+
+ An unrecognized bit was set in the options argument.
+
+ PCRE_ERROR_BADMAGIC (-4)
+
+ PCRE stores a 4-byte "magic number" at the start of the com-
+ piled code, to catch the case when it is passed a junk
+ pointer. This is the error it gives when the magic number
+ isn't present.
+
+ PCRE_ERROR_UNKNOWN_NODE (-5)
+
+ While running the pattern match, an unknown item was encoun-
+ tered in the compiled pattern. This error could be caused by
+ a bug in PCRE or by overwriting of the compiled pattern.
+
+ PCRE_ERROR_NOMEMORY (-6)
+
+ If a pattern contains back references, but the ovector that
+ is passed to pcre_exec() is not big enough to remember the
+ referenced substrings, PCRE gets a block of memory at the
+ start of matching to use for this purpose. If the call via
+ pcre_malloc() fails, this error is given. The memory is
+ freed at the end of matching.
+
+
+
+EXTRACTING CAPTURED SUBSTRINGS
+ Captured substrings can be accessed directly by using the
+ offsets returned by pcre_exec() in ovector. For convenience,
+ the functions pcre_copy_substring(), pcre_get_substring(),
+ and pcre_get_substring_list() are provided for extracting
+ captured substrings as new, separate, zero-terminated
+ strings. A substring that contains a binary zero is
+ correctly extracted and has a further zero added on the end,
+ but the result does not, of course, function as a C string.
+
+ The first three arguments are the same for all three func-
+ tions: subject is the subject string which has just been
+ successfully matched, ovector is a pointer to the vector of
+ integer offsets that was passed to pcre_exec(), and
+ stringcount is the number of substrings that were captured
+ by the match, including the substring that matched the
+ entire regular expression. This is the value returned by
+ pcre_exec if it is greater than zero. If pcre_exec()
+ returned zero, indicating that it ran out of space in ovec-
+ tor, then the value passed as stringcount should be the size
+ of the vector divided by three.
+
+ The functions pcre_copy_substring() and pcre_get_substring()
+ extract a single substring, whose number is given as string-
+ number. A value of zero extracts the substring that matched
+ the entire pattern, while higher values extract the captured
+ substrings. For pcre_copy_substring(), the string is placed
+ in buffer, whose length is given by buffersize, while for
+ pcre_get_substring() a new block of store is obtained via
+ pcre_malloc, and its address is returned via stringptr. The
+ yield of the function is the length of the string, not
+ including the terminating zero, or one of
+
+ PCRE_ERROR_NOMEMORY (-6)
+
+ The buffer was too small for pcre_copy_substring(), or the
+ attempt to get memory failed for pcre_get_substring().
+
+ PCRE_ERROR_NOSUBSTRING (-7)
+
+ There is no substring whose number is stringnumber.
+
+ The pcre_get_substring_list() function extracts all avail-
+ able substrings and builds a list of pointers to them. All
+ this is done in a single block of memory which is obtained
+ via pcre_malloc. The address of the memory block is returned
+ via listptr, which is also the start of the list of string
+ pointers. The end of the list is marked by a NULL pointer.
+ The yield of the function is zero if all went well, or
+
+ PCRE_ERROR_NOMEMORY (-6)
+
+ if the attempt to get the memory block failed.
+
+ When any of these functions encounter a substring that is
+ unset, which can happen when capturing subpattern number n+1
+ matches some part of the subject, but subpattern n has not
+ been used at all, they return an empty string. This can be
+ distinguished from a genuine zero-length substring by
+ inspecting the appropriate offset in ovector, which is nega-
+ tive for unset substrings.
+
+
+
+
+LIMITATIONS
+ There are some size limitations in PCRE but it is hoped that
+ they will never in practice be relevant. The maximum length
+ of a compiled pattern is 65539 (sic) bytes. All values in
+ repeating quantifiers must be less than 65536. The maximum
+ number of capturing subpatterns is 99. The maximum number
+ of all parenthesized subpatterns, including capturing sub-
+ patterns, assertions, and other types of subpattern, is 200.
+
+ The maximum length of a subject string is the largest posi-
+ tive number that an integer variable can hold. However, PCRE
+ uses recursion to handle subpatterns and indefinite repeti-
+ tion. This means that the available stack space may limit
+ the size of a subject string that can be processed by cer-
+ tain patterns.
+
+
+
+DIFFERENCES FROM PERL
+ The differences described here are with respect to Perl
+ 5.005.
+
+ 1. By default, a whitespace character is any character that
+ the C library function isspace() recognizes, though it is
+ possible to compile PCRE with alternative character type
+ tables. Normally isspace() matches space, formfeed, newline,
+ carriage return, horizontal tab, and vertical tab. Perl 5 no
+ longer includes vertical tab in its set of whitespace char-
+ acters. The \v escape that was in the Perl documentation for
+ a long time was never in fact recognized. However, the char-
+ acter itself was treated as whitespace at least up to 5.002.
+ In 5.004 and 5.005 it does not match \s.
+
+ 2. PCRE does not allow repeat quantifiers on lookahead
+ assertions. Perl permits them, but they do not mean what you
+ might think. For example, (?!a){3} does not assert that the
+ next three characters are not "a". It just asserts that the
+ next character is not "a" three times.
+
+ 3. Capturing subpatterns that occur inside negative looka-
+ head assertions are counted, but their entries in the
+ offsets vector are never set. Perl sets its numerical vari-
+ ables from any such patterns that are matched before the
+ assertion fails to match something (thereby succeeding), but
+ only if the negative lookahead assertion contains just one
+ branch.
+
+ 4. Though binary zero characters are supported in the sub-
+ ject string, they are not allowed in a pattern string
+ because it is passed as a normal C string, terminated by
+ zero. The escape sequence "\0" can be used in the pattern to
+ represent a binary zero.
+
+ 5. The following Perl escape sequences are not supported:
+ \l, \u, \L, \U, \E, \Q. In fact these are implemented by
+ Perl's general string-handling and are not part of its pat-
+ tern matching engine.
+
+ 6. The Perl \G assertion is not supported as it is not
+ relevant to single pattern matches.
+
+ 7. Fairly obviously, PCRE does not support the (?{code}) and
+ (?p{code}) constructions. However, there is some experimen-
+ tal support for recursive patterns using the non-Perl item
+ (?R).
+ 8. There are at the time of writing some oddities in Perl
+ 5.005_02 concerned with the settings of captured strings
+ when part of a pattern is repeated. For example, matching
+ "aba" against the pattern /^(a(b)?)+$/ sets $2 to the value
+ "b", but matching "aabbaa" against /^(aa(bb)?)+$/ leaves $2
+ unset. However, if the pattern is changed to
+ /^(aa(b(b))?)+$/ then $2 (and $3) get set.
+
+ In Perl 5.004 $2 is set in both cases, and that is also true
+ of PCRE. If in the future Perl changes to a consistent state
+ that is different, PCRE may change to follow.
+
+ 9. Another as yet unresolved discrepancy is that in Perl
+ 5.005_02 the pattern /^(a)?(?(1)a|b)+$/ matches the string
+ "a", whereas in PCRE it does not. However, in both Perl and
+ PCRE /^(a)?a/ matched against "a" leaves $1 unset.
+
+ 10. PCRE provides some extensions to the Perl regular
+ expression facilities:
+
+ (a) Although lookbehind assertions must match fixed length
+ strings, each alternative branch of a lookbehind assertion
+ can match a different length of string. Perl 5.005 requires
+ them all to have the same length.
+
+ (b) If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not
+ set, the $ meta- character matches only at the very end of
+ the string.
+
+ (c) If PCRE_EXTRA is set, a backslash followed by a letter
+ with no special meaning is faulted.
+
+ (d) If PCRE_UNGREEDY is set, the greediness of the repeti-
+ tion quantifiers is inverted, that is, by default they are
+ not greedy, but if followed by a question mark they are.
+
+ (e) PCRE_ANCHORED can be used to force a pattern to be tried
+ only at the start of the subject.
+
+ (f) The PCRE_NOTBOL, PCRE_NOTEOL, and PCRE_NOTEMPTY options
+ for pcre_exec() have no Perl equivalents.
+
+ (g) The (?R) construct allows for recursive pattern matching
+ (Perl 5.6 can do this using the (?p{code}) construct, which
+ PCRE cannot of course support.)
+
+
+
+REGULAR EXPRESSION DETAILS
+ The syntax and semantics of the regular expressions sup-
+ ported by PCRE are described below. Regular expressions are
+ also described in the Perl documentation and in a number of
+
+ other books, some of which have copious examples. Jeffrey
+ Friedl's "Mastering Regular Expressions", published by
+ O'Reilly (ISBN 1-56592-257), covers them in great detail.
+ The description here is intended as reference documentation.
+
+ A regular expression is a pattern that is matched against a
+ subject string from left to right. Most characters stand for
+ themselves in a pattern, and match the corresponding charac-
+ ters in the subject. As a trivial example, the pattern
+
+ The quick brown fox
+
+ matches a portion of a subject string that is identical to
+ itself. The power of regular expressions comes from the
+ ability to include alternatives and repetitions in the pat-
+ tern. These are encoded in the pattern by the use of meta-
+ characters, which do not stand for themselves but instead
+ are interpreted in some special way.
+
+ There are two different sets of meta-characters: those that
+ are recognized anywhere in the pattern except within square
+ brackets, and those that are recognized in square brackets.
+ Outside square brackets, the meta-characters are as follows:
+
+ \ general escape character with several uses
+ ^ assert start of subject (or line, in multiline
+ mode)
+ $ assert end of subject (or line, in multiline mode)
+ . match any character except newline (by default)
+ [ start character class definition
+ | start of alternative branch
+ ( start subpattern
+ ) end subpattern
+ ? extends the meaning of (
+ also 0 or 1 quantifier
+ also quantifier minimizer
+ * 0 or more quantifier
+ + 1 or more quantifier
+ { start min/max quantifier
+
+ Part of a pattern that is in square brackets is called a
+ "character class". In a character class the only meta-
+ characters are:
+
+ \ general escape character
+ ^ negate the class, but only if the first character
+ - indicates character range
+ ] terminates the character class
+
+ The following sections describe the use of each of the
+ meta-characters.
+
+
+
+BACKSLASH
+ The backslash character has several uses. Firstly, if it is
+ followed by a non-alphameric character, it takes away any
+ special meaning that character may have. This use of
+ backslash as an escape character applies both inside and
+ outside character classes.
+
+ For example, if you want to match a "*" character, you write
+ "\*" in the pattern. This applies whether or not the follow-
+ ing character would otherwise be interpreted as a meta-
+ character, so it is always safe to precede a non-alphameric
+ with "\" to specify that it stands for itself. In particu-
+ lar, if you want to match a backslash, you write "\\".
+
+ If a pattern is compiled with the PCRE_EXTENDED option, whi-
+ tespace in the pattern (other than in a character class) and
+ characters between a "#" outside a character class and the
+ next newline character are ignored. An escaping backslash
+ can be used to include a whitespace or "#" character as part
+ of the pattern.
+
+ A second use of backslash provides a way of encoding non-
+ printing characters in patterns in a visible manner. There
+ is no restriction on the appearance of non-printing charac-
+ ters, apart from the binary zero that terminates a pattern,
+ but when a pattern is being prepared by text editing, it is
+ usually easier to use one of the following escape sequences
+ than the binary character it represents:
+
+ \a alarm, that is, the BEL character (hex 07)
+ \cx "control-x", where x is any character
+ \e escape (hex 1B)
+ \f formfeed (hex 0C)
+ \n newline (hex 0A)
+ \r carriage return (hex 0D)
+ \t tab (hex 09)
+ \xhh character with hex code hh
+ \ddd character with octal code ddd, or backreference
+
+ The precise effect of "\cx" is as follows: if "x" is a lower
+ case letter, it is converted to upper case. Then bit 6 of
+ the character (hex 40) is inverted. Thus "\cz" becomes hex
+ 1A, but "\c{" becomes hex 3B, while "\c;" becomes hex 7B.
+
+ After "\x", up to two hexadecimal digits are read (letters
+ can be in upper or lower case).
+
+ After "\0" up to two further octal digits are read. In both
+ cases, if there are fewer than two digits, just those that
+ are present are used. Thus the sequence "\0\x\07" specifies
+ two binary zeros followed by a BEL character. Make sure you
+ supply two digits after the initial zero if the character
+ that follows is itself an octal digit.
+
+ The handling of a backslash followed by a digit other than 0
+ is complicated. Outside a character class, PCRE reads it
+ and any following digits as a decimal number. If the number
+ is less than 10, or if there have been at least that many
+ previous capturing left parentheses in the expression, the
+ entire sequence is taken as a back reference. A description
+ of how this works is given later, following the discussion
+ of parenthesized subpatterns.
+
+ Inside a character class, or if the decimal number is
+ greater than 9 and there have not been that many capturing
+ subpatterns, PCRE re-reads up to three octal digits follow-
+ ing the backslash, and generates a single byte from the
+ least significant 8 bits of the value. Any subsequent digits
+ stand for themselves. For example:
+
+ \040 is another way of writing a space
+ \40 is the same, provided there are fewer than 40
+ previous capturing subpatterns
+ \7 is always a back reference
+ \11 might be a back reference, or another way of
+ writing a tab
+ \011 is always a tab
+ \0113 is a tab followed by the character "3"
+ \113 is the character with octal code 113 (since there
+ can be no more than 99 back references)
+ \377 is a byte consisting entirely of 1 bits
+ \81 is either a back reference, or a binary zero
+ followed by the two characters "8" and "1"
+
+ Note that octal values of 100 or greater must not be intro-
+ duced by a leading zero, because no more than three octal
+ digits are ever read.
+
+ All the sequences that define a single byte value can be
+ used both inside and outside character classes. In addition,
+ inside a character class, the sequence "\b" is interpreted
+ as the backspace character (hex 08). Outside a character
+ class it has a different meaning (see below).
+
+ The third use of backslash is for specifying generic charac-
+ ter types:
+
+ \d any decimal digit
+ \D any character that is not a decimal digit
+ \s any whitespace character
+ \S any character that is not a whitespace character
+ \w any "word" character
+ \W any "non-word" character
+
+ Each pair of escape sequences partitions the complete set of
+ characters into two disjoint sets. Any given character
+ matches one, and only one, of each pair.
+
+ A "word" character is any letter or digit or the underscore
+ character, that is, any character which can be part of a
+ Perl "word". The definition of letters and digits is con-
+ trolled by PCRE's character tables, and may vary if locale-
+ specific matching is taking place (see "Locale support"
+ above). For example, in the "fr" (French) locale, some char-
+ acter codes greater than 128 are used for accented letters,
+ and these are matched by \w.
+
+ These character type sequences can appear both inside and
+ outside character classes. They each match one character of
+ the appropriate type. If the current matching point is at
+ the end of the subject string, all of them fail, since there
+ is no character to match.
+
+ The fourth use of backslash is for certain simple asser-
+ tions. An assertion specifies a condition that has to be met
+ at a particular point in a match, without consuming any
+ characters from the subject string. The use of subpatterns
+ for more complicated assertions is described below. The
+ backslashed assertions are
+
+ \b word boundary
+ \B not a word boundary
+ \A start of subject (independent of multiline mode)
+ \Z end of subject or newline at end (independent of
+ multiline mode)
+ \z end of subject (independent of multiline mode)
+
+ These assertions may not appear in character classes (but
+ note that "\b" has a different meaning, namely the backspace
+ character, inside a character class).
+
+ A word boundary is a position in the subject string where
+ the current character and the previous character do not both
+ match \w or \W (i.e. one matches \w and the other matches
+ \W), or the start or end of the string if the first or last
+ character matches \w, respectively.
+
+ The \A, \Z, and \z assertions differ from the traditional
+ circumflex and dollar (described below) in that they only
+ ever match at the very start and end of the subject string,
+ whatever options are set. They are not affected by the
+ PCRE_NOTBOL or PCRE_NOTEOL options. If the startoffset argu-
+ ment of pcre_exec() is non-zero, \A can never match. The
+ difference between \Z and \z is that \Z matches before a
+ newline that is the last character of the string as well as
+ at the end of the string, whereas \z matches only at the
+ end.
+
+
+
+CIRCUMFLEX AND DOLLAR
+ Outside a character class, in the default matching mode, the
+ circumflex character is an assertion which is true only if
+ the current matching point is at the start of the subject
+ string. If the startoffset argument of pcre_exec() is non-
+ zero, circumflex can never match. Inside a character class,
+ circumflex has an entirely different meaning (see below).
+
+ Circumflex need not be the first character of the pattern if
+ a number of alternatives are involved, but it should be the
+ first thing in each alternative in which it appears if the
+ pattern is ever to match that branch. If all possible alter-
+ natives start with a circumflex, that is, if the pattern is
+ constrained to match only at the start of the subject, it is
+ said to be an "anchored" pattern. (There are also other con-
+ structs that can cause a pattern to be anchored.)
+
+ A dollar character is an assertion which is true only if the
+ current matching point is at the end of the subject string,
+ or immediately before a newline character that is the last
+ character in the string (by default). Dollar need not be the
+ last character of the pattern if a number of alternatives
+ are involved, but it should be the last item in any branch
+ in which it appears. Dollar has no special meaning in a
+ character class.
+
+ The meaning of dollar can be changed so that it matches only
+ at the very end of the string, by setting the
+ PCRE_DOLLAR_ENDONLY option at compile or matching time. This
+ does not affect the \Z assertion.
+
+ The meanings of the circumflex and dollar characters are
+ changed if the PCRE_MULTILINE option is set. When this is
+ the case, they match immediately after and immediately
+ before an internal "\n" character, respectively, in addition
+ to matching at the start and end of the subject string. For
+ example, the pattern /^abc$/ matches the subject string
+ "def\nabc" in multiline mode, but not otherwise. Conse-
+ quently, patterns that are anchored in single line mode
+ because all branches start with "^" are not anchored in mul-
+ tiline mode, and a match for circumflex is possible when the
+ startoffset argument of pcre_exec() is non-zero. The
+ PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is
+ set.
+
+ Note that the sequences \A, \Z, and \z can be used to match
+ the start and end of the subject in both modes, and if all
+ branches of a pattern start with \A is it always anchored,
+ whether PCRE_MULTILINE is set or not.
+
+
+
+FULL STOP (PERIOD, DOT)
+ Outside a character class, a dot in the pattern matches any
+ one character in the subject, including a non-printing char-
+ acter, but not (by default) newline. If the PCRE_DOTALL
+ option is set, then dots match newlines as well. The han-
+ dling of dot is entirely independent of the handling of cir-
+ cumflex and dollar, the only relationship being that they
+ both involve newline characters. Dot has no special meaning
+ in a character class.
+
+
+
+SQUARE BRACKETS
+ An opening square bracket introduces a character class, ter-
+ minated by a closing square bracket. A closing square
+ bracket on its own is not special. If a closing square
+ bracket is required as a member of the class, it should be
+ the first data character in the class (after an initial cir-
+ cumflex, if present) or escaped with a backslash.
+
+ A character class matches a single character in the subject;
+ the character must be in the set of characters defined by
+ the class, unless the first character in the class is a cir-
+ cumflex, in which case the subject character must not be in
+ the set defined by the class. If a circumflex is actually
+ required as a member of the class, ensure it is not the
+ first character, or escape it with a backslash.
+
+ For example, the character class [aeiou] matches any lower
+ case vowel, while [^aeiou] matches any character that is not
+ a lower case vowel. Note that a circumflex is just a con-
+ venient notation for specifying the characters which are in
+ the class by enumerating those that are not. It is not an
+ assertion: it still consumes a character from the subject
+ string, and fails if the current pointer is at the end of
+ the string.
+
+ When caseless matching is set, any letters in a class
+ represent both their upper case and lower case versions, so
+ for example, a caseless [aeiou] matches "A" as well as "a",
+ and a caseless [^aeiou] does not match "A", whereas a case-
+ ful version would.
+
+ The newline character is never treated in any special way in
+ character classes, whatever the setting of the PCRE_DOTALL
+ or PCRE_MULTILINE options is. A class such as [^a] will
+ always match a newline.
+
+ The minus (hyphen) character can be used to specify a range
+ of characters in a character class. For example, [d-m]
+ matches any letter between d and m, inclusive. If a minus
+ character is required in a class, it must be escaped with a
+ backslash or appear in a position where it cannot be inter-
+ preted as indicating a range, typically as the first or last
+ character in the class.
+
+ It is not possible to have the literal character "]" as the
+ end character of a range. A pattern such as [W-]46] is
+ interpreted as a class of two characters ("W" and "-") fol-
+ lowed by a literal string "46]", so it would match "W46]" or
+ "-46]". However, if the "]" is escaped with a backslash it
+ is interpreted as the end of range, so [W-\]46] is inter-
+ preted as a single class containing a range followed by two
+ separate characters. The octal or hexadecimal representation
+ of "]" can also be used to end a range.
+
+ Ranges operate in ASCII collating sequence. They can also be
+ used for characters specified numerically, for example
+ [\000-\037]. If a range that includes letters is used when
+ caseless matching is set, it matches the letters in either
+ case. For example, [W-c] is equivalent to [][\^_`wxyzabc],
+ matched caselessly, and if character tables for the "fr"
+ locale are in use, [\xc8-\xcb] matches accented E characters
+ in both cases.
+
+ The character types \d, \D, \s, \S, \w, and \W may also
+ appear in a character class, and add the characters that
+ they match to the class. For example, [\dABCDEF] matches any
+ hexadecimal digit. A circumflex can conveniently be used
+ with the upper case character types to specify a more res-
+ tricted set of characters than the matching lower case type.
+ For example, the class [^\W_] matches any letter or digit,
+ but not underscore.
+
+ All non-alphameric characters other than \, -, ^ (at the
+ start) and the terminating ] are non-special in character
+ classes, but it does no harm if they are escaped.
+
+
+
+POSIX CHARACTER CLASSES
+ Perl 5.6 (not yet released at the time of writing) is going
+ to support the POSIX notation for character classes, which
+ uses names enclosed by [: and :] within the enclosing
+ square brackets. PCRE supports this notation. For example,
+
+ [01[:alpha:]%]
+
+ matches "0", "1", any alphabetic character, or "%". The sup-
+ ported class names are
+
+ alnum letters and digits
+ alpha letters
+ ascii character codes 0 - 127
+ cntrl control characters
+ digit decimal digits (same as \d)
+ graph printing characters, excluding space
+ lower lower case letters
+ print printing characters, including space
+ punct printing characters, excluding letters and digits
+ space white space (same as \s)
+ upper upper case letters
+ word "word" characters (same as \w)
+ xdigit hexadecimal digits
+
+ The names "ascii" and "word" are Perl extensions. Another
+ Perl extension is negation, which is indicated by a ^ char-
+ acter after the colon. For example,
+
+ [12[:^digit:]]
+
+ matches "1", "2", or any non-digit. PCRE (and Perl) also
+ recogize the POSIX syntax [.ch.] and [=ch=] where "ch" is a
+ "collating element", but these are not supported, and an
+ error is given if they are encountered.
+
+
+
+VERTICAL BAR
+ Vertical bar characters are used to separate alternative
+ patterns. For example, the pattern
+
+ gilbert|sullivan
+
+ matches either "gilbert" or "sullivan". Any number of alter-
+ natives may appear, and an empty alternative is permitted
+ (matching the empty string). The matching process tries
+ each alternative in turn, from left to right, and the first
+ one that succeeds is used. If the alternatives are within a
+ subpattern (defined below), "succeeds" means matching the
+ rest of the main pattern as well as the alternative in the
+ subpattern.
+
+
+
+INTERNAL OPTION SETTING
+ The settings of PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL,
+ and PCRE_EXTENDED can be changed from within the pattern by
+ a sequence of Perl option letters enclosed between "(?" and
+ ")". The option letters are
+
+ i for PCRE_CASELESS
+ m for PCRE_MULTILINE
+ s for PCRE_DOTALL
+ x for PCRE_EXTENDED
+
+ For example, (?im) sets caseless, multiline matching. It is
+ also possible to unset these options by preceding the letter
+ with a hyphen, and a combined setting and unsetting such as
+ (?im-sx), which sets PCRE_CASELESS and PCRE_MULTILINE while
+ unsetting PCRE_DOTALL and PCRE_EXTENDED, is also permitted.
+ If a letter appears both before and after the hyphen, the
+ option is unset.
+
+ The scope of these option changes depends on where in the
+ pattern the setting occurs. For settings that are outside
+ any subpattern (defined below), the effect is the same as if
+ the options were set or unset at the start of matching. The
+ following patterns all behave in exactly the same way:
+
+ (?i)abc
+ a(?i)bc
+ ab(?i)c
+ abc(?i)
+
+ which in turn is the same as compiling the pattern abc with
+ PCRE_CASELESS set. In other words, such "top level" set-
+ tings apply to the whole pattern (unless there are other
+ changes inside subpatterns). If there is more than one set-
+ ting of the same option at top level, the rightmost setting
+ is used.
+
+ If an option change occurs inside a subpattern, the effect
+ is different. This is a change of behaviour in Perl 5.005.
+ An option change inside a subpattern affects only that part
+ of the subpattern that follows it, so
+
+ (a(?i)b)c
+
+ matches abc and aBc and no other strings (assuming
+ PCRE_CASELESS is not used). By this means, options can be
+ made to have different settings in different parts of the
+ pattern. Any changes made in one alternative do carry on
+ into subsequent branches within the same subpattern. For
+ example,
+
+ (a(?i)b|c)
+
+ matches "ab", "aB", "c", and "C", even though when matching
+ "C" the first branch is abandoned before the option setting.
+ This is because the effects of option settings happen at
+ compile time. There would be some very weird behaviour oth-
+ erwise.
+
+ The PCRE-specific options PCRE_UNGREEDY and PCRE_EXTRA can
+ be changed in the same way as the Perl-compatible options by
+ using the characters U and X respectively. The (?X) flag
+ setting is special in that it must always occur earlier in
+ the pattern than any of the additional features it turns on,
+ even when it is at top level. It is best put at the start.
+
+
+
+SUBPATTERNS
+ Subpatterns are delimited by parentheses (round brackets),
+ which can be nested. Marking part of a pattern as a subpat-
+ tern does two things:
+
+ 1. It localizes a set of alternatives. For example, the pat-
+ tern
+
+ cat(aract|erpillar|)
+
+ matches one of the words "cat", "cataract", or "caterpil-
+ lar". Without the parentheses, it would match "cataract",
+ "erpillar" or the empty string.
+
+ 2. It sets up the subpattern as a capturing subpattern (as
+ defined above). When the whole pattern matches, that por-
+ tion of the subject string that matched the subpattern is
+ passed back to the caller via the ovector argument of
+ pcre_exec(). Opening parentheses are counted from left to
+ right (starting from 1) to obtain the numbers of the captur-
+ ing subpatterns.
+
+ For example, if the string "the red king" is matched against
+ the pattern
+
+ the ((red|white) (king|queen))
+
+ the captured substrings are "red king", "red", and "king",
+ and are numbered 1, 2, and 3.
+
+ The fact that plain parentheses fulfil two functions is not
+ always helpful. There are often times when a grouping sub-
+ pattern is required without a capturing requirement. If an
+ opening parenthesis is followed by "?:", the subpattern does
+ not do any capturing, and is not counted when computing the
+ number of any subsequent capturing subpatterns. For example,
+ if the string "the white queen" is matched against the pat-
+ tern
+
+ the ((?:red|white) (king|queen))
+
+ the captured substrings are "white queen" and "queen", and
+ are numbered 1 and 2. The maximum number of captured sub-
+ strings is 99, and the maximum number of all subpatterns,
+ both capturing and non-capturing, is 200.
+
+ As a convenient shorthand, if any option settings are
+ required at the start of a non-capturing subpattern, the
+ option letters may appear between the "?" and the ":". Thus
+ the two patterns
+
+ (?i:saturday|sunday)
+ (?:(?i)saturday|sunday)
+
+ match exactly the same set of strings. Because alternative
+ branches are tried from left to right, and options are not
+ reset until the end of the subpattern is reached, an option
+ setting in one branch does affect subsequent branches, so
+ the above patterns match "SUNDAY" as well as "Saturday".
+
+
+
+REPETITION
+ Repetition is specified by quantifiers, which can follow any
+ of the following items:
+
+ a single character, possibly escaped
+ the . metacharacter
+ a character class
+ a back reference (see next section)
+ a parenthesized subpattern (unless it is an assertion -
+ see below)
+
+ The general repetition quantifier specifies a minimum and
+ maximum number of permitted matches, by giving the two
+ numbers in curly brackets (braces), separated by a comma.
+ The numbers must be less than 65536, and the first must be
+ less than or equal to the second. For example:
+
+ z{2,4}
+
+ matches "zz", "zzz", or "zzzz". A closing brace on its own
+ is not a special character. If the second number is omitted,
+ but the comma is present, there is no upper limit; if the
+ second number and the comma are both omitted, the quantifier
+ specifies an exact number of required matches. Thus
+
+ [aeiou]{3,}
+
+ matches at least 3 successive vowels, but may match many
+ more, while
+
+ \d{8}
+
+ matches exactly 8 digits. An opening curly bracket that
+ appears in a position where a quantifier is not allowed, or
+ one that does not match the syntax of a quantifier, is taken
+ as a literal character. For example, {,6} is not a quantif-
+ ier, but a literal string of four characters.
+
+ The quantifier {0} is permitted, causing the expression to
+ behave as if the previous item and the quantifier were not
+ present.
+
+ For convenience (and historical compatibility) the three
+ most common quantifiers have single-character abbreviations:
+
+ * is equivalent to {0,}
+ + is equivalent to {1,}
+ ? is equivalent to {0,1}
+
+ It is possible to construct infinite loops by following a
+ subpattern that can match no characters with a quantifier
+ that has no upper limit, for example:
+
+ (a?)*
+
+ Earlier versions of Perl and PCRE used to give an error at
+ compile time for such patterns. However, because there are
+ cases where this can be useful, such patterns are now
+ accepted, but if any repetition of the subpattern does in
+ fact match no characters, the loop is forcibly broken.
+
+ By default, the quantifiers are "greedy", that is, they
+ match as much as possible (up to the maximum number of per-
+ mitted times), without causing the rest of the pattern to
+ fail. The classic example of where this gives problems is in
+ trying to match comments in C programs. These appear between
+ the sequences /* and */ and within the sequence, individual
+ * and / characters may appear. An attempt to match C com-
+ ments by applying the pattern
+
+ /\*.*\*/
+
+ to the string
+
+ /* first command */ not comment /* second comment */
+
+ fails, because it matches the entire string due to the
+ greediness of the .* item.
+
+ However, if a quantifier is followed by a question mark,
+ then it ceases to be greedy, and instead matches the minimum
+ number of times possible, so the pattern
+
+ /\*.*?\*/
+
+ does the right thing with the C comments. The meaning of the
+ various quantifiers is not otherwise changed, just the pre-
+ ferred number of matches. Do not confuse this use of ques-
+ tion mark with its use as a quantifier in its own right.
+ Because it has two uses, it can sometimes appear doubled, as
+ in
+
+ \d??\d
+
+ which matches one digit by preference, but can match two if
+ that is the only way the rest of the pattern matches.
+
+ If the PCRE_UNGREEDY option is set (an option which is not
+ available in Perl) then the quantifiers are not greedy by
+ default, but individual ones can be made greedy by following
+ them with a question mark. In other words, it inverts the
+ default behaviour.
+
+ When a parenthesized subpattern is quantified with a minimum
+ repeat count that is greater than 1 or with a limited max-
+ imum, more store is required for the compiled pattern, in
+ proportion to the size of the minimum or maximum.
+
+ If a pattern starts with .* or .{0,} and the PCRE_DOTALL
+ option (equivalent to Perl's /s) is set, thus allowing the .
+ to match newlines, then the pattern is implicitly anchored,
+ because whatever follows will be tried against every charac-
+ ter position in the subject string, so there is no point in
+ retrying the overall match at any position after the first.
+ PCRE treats such a pattern as though it were preceded by \A.
+ In cases where it is known that the subject string contains
+ no newlines, it is worth setting PCRE_DOTALL when the pat-
+ tern begins with .* in order to obtain this optimization, or
+ alternatively using ^ to indicate anchoring explicitly.
+
+ When a capturing subpattern is repeated, the value captured
+ is the substring that matched the final iteration. For exam-
+ ple, after
+
+ (tweedle[dume]{3}\s*)+
+
+ has matched "tweedledum tweedledee" the value of the cap-
+ tured substring is "tweedledee". However, if there are
+ nested capturing subpatterns, the corresponding captured
+ values may have been set in previous iterations. For exam-
+ ple, after
+
+ /(a|(b))+/
+
+ matches "aba" the value of the second captured substring is
+ "b".
+
+
+
+BACK REFERENCES
+ Outside a character class, a backslash followed by a digit
+ greater than 0 (and possibly further digits) is a back
+ reference to a capturing subpattern earlier (i.e. to its
+ left) in the pattern, provided there have been that many
+ previous capturing left parentheses.
+
+ However, if the decimal number following the backslash is
+ less than 10, it is always taken as a back reference, and
+ causes an error only if there are not that many capturing
+ left parentheses in the entire pattern. In other words, the
+ parentheses that are referenced need not be to the left of
+ the reference for numbers less than 10. See the section
+ entitled "Backslash" above for further details of the han-
+ dling of digits following a backslash.
+
+ A back reference matches whatever actually matched the cap-
+ turing subpattern in the current subject string, rather than
+ anything matching the subpattern itself. So the pattern
+
+ (sens|respons)e and \1ibility
+
+ matches "sense and sensibility" and "response and responsi-
+ bility", but not "sense and responsibility". If caseful
+ matching is in force at the time of the back reference, then
+ the case of letters is relevant. For example,
+
+ ((?i)rah)\s+\1
+
+ matches "rah rah" and "RAH RAH", but not "RAH rah", even
+ though the original capturing subpattern is matched case-
+ lessly.
+
+ There may be more than one back reference to the same sub-
+ pattern. If a subpattern has not actually been used in a
+ particular match, then any back references to it always
+ fail. For example, the pattern
+
+ (a|(bc))\2
+
+ always fails if it starts to match "a" rather than "bc".
+ Because there may be up to 99 back references, all digits
+ following the backslash are taken as part of a potential
+ back reference number. If the pattern continues with a digit
+ character, then some delimiter must be used to terminate the
+ back reference. If the PCRE_EXTENDED option is set, this can
+ be whitespace. Otherwise an empty comment can be used.
+
+ A back reference that occurs inside the parentheses to which
+ it refers fails when the subpattern is first used, so, for
+ example, (a\1) never matches. However, such references can
+ be useful inside repeated subpatterns. For example, the
+ pattern
+
+ (a|b\1)+
+
+ matches any number of "a"s and also "aba", "ababaa" etc. At
+ each iteration of the subpattern, the back reference matches
+ the character string corresponding to the previous itera-
+ tion. In order for this to work, the pattern must be such
+ that the first iteration does not need to match the back
+ reference. This can be done using alternation, as in the
+ example above, or by a quantifier with a minimum of zero.
+
+
+
+ASSERTIONS
+ An assertion is a test on the characters following or
+ preceding the current matching point that does not actually
+ consume any characters. The simple assertions coded as \b,
+ \B, \A, \Z, \z, ^ and $ are described above. More compli-
+ cated assertions are coded as subpatterns. There are two
+ kinds: those that look ahead of the current position in the
+ subject string, and those that look behind it.
+
+ An assertion subpattern is matched in the normal way, except
+ that it does not cause the current matching position to be
+ changed. Lookahead assertions start with (?= for positive
+ assertions and (?! for negative assertions. For example,
+
+ \w+(?=;)
+
+ matches a word followed by a semicolon, but does not include
+ the semicolon in the match, and
+
+ foo(?!bar)
+
+ matches any occurrence of "foo" that is not followed by
+ "bar". Note that the apparently similar pattern
+
+ (?!foo)bar
+
+ does not find an occurrence of "bar" that is preceded by
+ something other than "foo"; it finds any occurrence of "bar"
+ whatsoever, because the assertion (?!foo) is always true
+ when the next three characters are "bar". A lookbehind
+ assertion is needed to achieve this effect.
+
+ Lookbehind assertions start with (?<= for positive asser-
+ tions and (?<! for negative assertions. For example,
+
+ (?<!foo)bar
+
+ does find an occurrence of "bar" that is not preceded by
+ "foo". The contents of a lookbehind assertion are restricted
+ such that all the strings it matches must have a fixed
+ length. However, if there are several alternatives, they do
+ not all have to have the same fixed length. Thus
+
+ (?<=bullock|donkey)
+
+ is permitted, but
+
+ (?<!dogs?|cats?)
+
+ causes an error at compile time. Branches that match dif-
+ ferent length strings are permitted only at the top level of
+ a lookbehind assertion. This is an extension compared with
+ Perl 5.005, which requires all branches to match the same
+ length of string. An assertion such as
+
+ (?<=ab(c|de))
+
+ is not permitted, because its single top-level branch can
+ match two different lengths, but it is acceptable if rewrit-
+ ten to use two top-level branches:
+
+ (?<=abc|abde)
+
+ The implementation of lookbehind assertions is, for each
+ alternative, to temporarily move the current position back
+ by the fixed width and then try to match. If there are
+ insufficient characters before the current position, the
+ match is deemed to fail. Lookbehinds in conjunction with
+ once-only subpatterns can be particularly useful for match-
+ ing at the ends of strings; an example is given at the end
+ of the section on once-only subpatterns.
+
+ Several assertions (of any sort) may occur in succession.
+ For example,
+
+ (?<=\d{3})(?<!999)foo
+
+ matches "foo" preceded by three digits that are not "999".
+ Notice that each of the assertions is applied independently
+ at the same point in the subject string. First there is a
+ check that the previous three characters are all digits,
+ then there is a check that the same three characters are not
+ "999". This pattern does not match "foo" preceded by six
+ characters, the first of which are digits and the last three
+ of which are not "999". For example, it doesn't match
+ "123abcfoo". A pattern to do that is
+
+ (?<=\d{3}...)(?<!999)foo
+
+ This time the first assertion looks at the preceding six
+ characters, checking that the first three are digits, and
+ then the second assertion checks that the preceding three
+ characters are not "999".
+
+ Assertions can be nested in any combination. For example,
+
+ (?<=(?<!foo)bar)baz
+
+ matches an occurrence of "baz" that is preceded by "bar"
+ which in turn is not preceded by "foo", while
+
+ (?<=\d{3}(?!999)...)foo
+
+ is another pattern which matches "foo" preceded by three
+ digits and any three characters that are not "999".
+
+ Assertion subpatterns are not capturing subpatterns, and may
+ not be repeated, because it makes no sense to assert the
+ same thing several times. If any kind of assertion contains
+ capturing subpatterns within it, these are counted for the
+ purposes of numbering the capturing subpatterns in the whole
+ pattern. However, substring capturing is carried out only
+ for positive assertions, because it does not make sense for
+ negative assertions.
+
+ Assertions count towards the maximum of 200 parenthesized
+ subpatterns.
+
+
+
+ONCE-ONLY SUBPATTERNS
+ With both maximizing and minimizing repetition, failure of
+ what follows normally causes the repeated item to be re-
+ evaluated to see if a different number of repeats allows the
+ rest of the pattern to match. Sometimes it is useful to
+ prevent this, either to change the nature of the match, or
+ to cause it fail earlier than it otherwise might, when the
+ author of the pattern knows there is no point in carrying
+ on.
+
+ Consider, for example, the pattern \d+foo when applied to
+ the subject line
+
+ 123456bar
+
+ After matching all 6 digits and then failing to match "foo",
+ the normal action of the matcher is to try again with only 5
+ digits matching the \d+ item, and then with 4, and so on,
+ before ultimately failing. Once-only subpatterns provide the
+ means for specifying that once a portion of the pattern has
+ matched, it is not to be re-evaluated in this way, so the
+ matcher would give up immediately on failing to match "foo"
+ the first time. The notation is another kind of special
+ parenthesis, starting with (?> as in this example:
+
+ (?>\d+)bar
+
+ This kind of parenthesis "locks up" the part of the pattern
+ it contains once it has matched, and a failure further into
+ the pattern is prevented from backtracking into it. Back-
+ tracking past it to previous items, however, works as nor-
+ mal.
+
+ An alternative description is that a subpattern of this type
+ matches the string of characters that an identical stan-
+ dalone pattern would match, if anchored at the current point
+ in the subject string.
+
+ Once-only subpatterns are not capturing subpatterns. Simple
+ cases such as the above example can be thought of as a max-
+ imizing repeat that must swallow everything it can. So,
+ while both \d+ and \d+? are prepared to adjust the number of
+ digits they match in order to make the rest of the pattern
+ match, (?>\d+) can only match an entire sequence of digits.
+
+ This construction can of course contain arbitrarily compli-
+ cated subpatterns, and it can be nested.
+
+ Once-only subpatterns can be used in conjunction with look-
+ behind assertions to specify efficient matching at the end
+ of the subject string. Consider a simple pattern such as
+
+ abcd$
+
+ when applied to a long string which does not match. Because
+ matching proceeds from left to right, PCRE will look for
+ each "a" in the subject and then see if what follows matches
+ the rest of the pattern. If the pattern is specified as
+
+ ^.*abcd$
+
+ then the initial .* matches the entire string at first, but
+ when this fails (because there is no following "a"), it
+ backtracks to match all but the last character, then all but
+ the last two characters, and so on. Once again the search
+ for "a" covers the entire string, from right to left, so we
+ are no better off. However, if the pattern is written as
+
+ ^(?>.*)(?<=abcd)
+
+ then there can be no backtracking for the .* item; it can
+ match only the entire string. The subsequent lookbehind
+ assertion does a single test on the last four characters. If
+ it fails, the match fails immediately. For long strings,
+ this approach makes a significant difference to the process-
+ ing time.
+
+ When a pattern contains an unlimited repeat inside a subpat-
+ tern that can itself be repeated an unlimited number of
+ times, the use of a once-only subpattern is the only way to
+ avoid some failing matches taking a very long time indeed.
+ The pattern
+
+ (\D+|<\d+>)*[!?]
+
+ matches an unlimited number of substrings that either con-
+ sist of non-digits, or digits enclosed in <>, followed by
+ either ! or ?. When it matches, it runs quickly. However, if
+ it is applied to
+
+ aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+
+ it takes a long time before reporting failure. This is
+ because the string can be divided between the two repeats in
+ a large number of ways, and all have to be tried. (The exam-
+ ple used [!?] rather than a single character at the end,
+ because both PCRE and Perl have an optimization that allows
+ for fast failure when a single character is used. They
+ remember the last single character that is required for a
+ match, and fail early if it is not present in the string.)
+ If the pattern is changed to
+
+ ((?>\D+)|<\d+>)*[!?]
+
+ sequences of non-digits cannot be broken, and failure hap-
+ pens quickly.
+
+
+
+CONDITIONAL SUBPATTERNS
+ It is possible to cause the matching process to obey a sub-
+ pattern conditionally or to choose between two alternative
+ subpatterns, depending on the result of an assertion, or
+ whether a previous capturing subpattern matched or not. The
+ two possible forms of conditional subpattern are
+
+ (?(condition)yes-pattern)
+ (?(condition)yes-pattern|no-pattern)
+
+ If the condition is satisfied, the yes-pattern is used; oth-
+ erwise the no-pattern (if present) is used. If there are
+ more than two alternatives in the subpattern, a compile-time
+ error occurs.
+
+ There are two kinds of condition. If the text between the
+ parentheses consists of a sequence of digits, then the
+ condition is satisfied if the capturing subpattern of that
+ number has previously matched. Consider the following pat-
+ tern, which contains non-significant white space to make it
+ more readable (assume the PCRE_EXTENDED option) and to
+ divide it into three parts for ease of discussion:
+
+ ( \( )? [^()]+ (?(1) \) )
+
+ The first part matches an optional opening parenthesis, and
+ if that character is present, sets it as the first captured
+ substring. The second part matches one or more characters
+ that are not parentheses. The third part is a conditional
+ subpattern that tests whether the first set of parentheses
+ matched or not. If they did, that is, if subject started
+ with an opening parenthesis, the condition is true, and so
+ the yes-pattern is executed and a closing parenthesis is
+ required. Otherwise, since no-pattern is not present, the
+ subpattern matches nothing. In other words, this pattern
+ matches a sequence of non-parentheses, optionally enclosed
+ in parentheses.
+
+ If the condition is not a sequence of digits, it must be an
+ assertion. This may be a positive or negative lookahead or
+ lookbehind assertion. Consider this pattern, again contain-
+ ing non-significant white space, and with the two alterna-
+ tives on the second line:
+
+ (?(?=[^a-z]*[a-z])
+ \d{2}-[a-z]{3}-\d{2} | \d{2}-\d{2}-\d{2} )
+
+ The condition is a positive lookahead assertion that matches
+ an optional sequence of non-letters followed by a letter. In
+ other words, it tests for the presence of at least one
+ letter in the subject. If a letter is found, the subject is
+ matched against the first alternative; otherwise it is
+ matched against the second. This pattern matches strings in
+ one of the two forms dd-aaa-dd or dd-dd-dd, where aaa are
+ letters and dd are digits.
+
+
+
+COMMENTS
+ The sequence (?# marks the start of a comment which contin-
+ ues up to the next closing parenthesis. Nested parentheses
+ are not permitted. The characters that make up a comment
+ play no part in the pattern matching at all.
+
+ If the PCRE_EXTENDED option is set, an unescaped # character
+ outside a character class introduces a comment that contin-
+ ues up to the next newline character in the pattern.
+
+
+
+RECURSIVE PATTERNS
+ Consider the problem of matching a string in parentheses,
+ allowing for unlimited nested parentheses. Without the use
+ of recursion, the best that can be done is to use a pattern
+ that matches up to some fixed depth of nesting. It is not
+ possible to handle an arbitrary nesting depth. Perl 5.6 has
+ provided an experimental facility that allows regular
+ expressions to recurse (amongst other things). It does this
+ by interpolating Perl code in the expression at run time,
+ and the code can refer to the expression itself. A Perl pat-
+ tern to solve the parentheses problem can be created like
+ this:
+
+ $re = qr{\( (?: (?>[^()]+) | (?p{$re}) )* \)}x;
+
+ The (?p{...}) item interpolates Perl code at run time, and
+ in this case refers recursively to the pattern in which it
+ appears. Obviously, PCRE cannot support the interpolation of
+ Perl code. Instead, the special item (?R) is provided for
+ the specific case of recursion. This PCRE pattern solves the
+ parentheses problem (assume the PCRE_EXTENDED option is set
+ so that white space is ignored):
+
+ \( ( (?>[^()]+) | (?R) )* \)
+
+ First it matches an opening parenthesis. Then it matches any
+ number of substrings which can either be a sequence of non-
+ parentheses, or a recursive match of the pattern itself
+ (i.e. a correctly parenthesized substring). Finally there is
+ a closing parenthesis.
+
+ This particular example pattern contains nested unlimited
+ repeats, and so the use of a once-only subpattern for match-
+ ing strings of non-parentheses is important when applying
+ the pattern to strings that do not match. For example, when
+ it is applied to
+
+ (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa()
+
+ it yields "no match" quickly. However, if a once-only sub-
+ pattern is not used, the match runs for a very long time
+ indeed because there are so many different ways the + and *
+ repeats can carve up the subject, and all have to be tested
+ before failure can be reported.
+
+ The values set for any capturing subpatterns are those from
+ the outermost level of the recursion at which the subpattern
+ value is set. If the pattern above is matched against
+
+ (ab(cd)ef)
+
+ the value for the capturing parentheses is "ef", which is
+ the last value taken on at the top level. If additional
+ parentheses are added, giving
+
+ \( ( ( (?>[^()]+) | (?R) )* ) \)
+ ^ ^
+ ^ ^ then the string they capture
+ is "ab(cd)ef", the contents of the top level parentheses. If
+ there are more than 15 capturing parentheses in a pattern,
+ PCRE has to obtain extra memory to store data during a
+ recursion, which it does by using pcre_malloc, freeing it
+ via pcre_free afterwards. If no memory can be obtained, it
+ saves data for the first 15 capturing parentheses only, as
+ there is no way to give an out-of-memory error from within a
+ recursion.
+
+
+
+PERFORMANCE
+ Certain items that may appear in patterns are more efficient
+ than others. It is more efficient to use a character class
+ like [aeiou] than a set of alternatives such as (a|e|i|o|u).
+ In general, the simplest construction that provides the
+ required behaviour is usually the most efficient. Jeffrey
+ Friedl's book contains a lot of discussion about optimizing
+ regular expressions for efficient performance.
+
+ When a pattern begins with .* and the PCRE_DOTALL option is
+ set, the pattern is implicitly anchored by PCRE, since it
+ can match only at the start of a subject string. However, if
+ PCRE_DOTALL is not set, PCRE cannot make this optimization,
+ because the . metacharacter does not then match a newline,
+ and if the subject string contains newlines, the pattern may
+ match from the character immediately following one of them
+ instead of from the very start. For example, the pattern
+
+ (.*) second
+
+ matches the subject "first\nand second" (where \n stands for
+ a newline character) with the first captured substring being
+ "and". In order to do this, PCRE has to retry the match
+ starting after every newline in the subject.
+
+ If you are using such a pattern with subject strings that do
+ not contain newlines, the best performance is obtained by
+ setting PCRE_DOTALL, or starting the pattern with ^.* to
+ indicate explicit anchoring. That saves PCRE from having to
+ scan along the subject looking for a newline to restart at.
+
+ Beware of patterns that contain nested indefinite repeats.
+ These can take a long time to run when applied to a string
+ that does not match. Consider the pattern fragment
+
+ (a+)*
+
+ This can match "aaaa" in 33 different ways, and this number
+ increases very rapidly as the string gets longer. (The *
+ repeat can match 0, 1, 2, 3, or 4 times, and for each of
+ those cases other than 0, the + repeats can match different
+ numbers of times.) When the remainder of the pattern is such
+ that the entire match is going to fail, PCRE has in princi-
+ ple to try every possible variation, and this can take an
+ extremely long time.
+
+ An optimization catches some of the more simple cases such
+ as
+
+ (a+)*b
+
+ where a literal character follows. Before embarking on the
+ standard matching procedure, PCRE checks that there is a "b"
+ later in the subject string, and if there is not, it fails
+ the match immediately. However, when there is no following
+ literal this optimization cannot be used. You can see the
+ difference by comparing the behaviour of
+
+ (a+)*\d
+
+ with the pattern above. The former gives a failure almost
+ instantly when applied to a whole line of "a" characters,
+ whereas the latter takes an appreciable time with strings
+ longer than about 20 characters.
+
+
+
+AUTHOR
+ Philip Hazel <ph10@cam.ac.uk>
+ University Computing Service,
+ New Museums Site,
+ Cambridge CB2 3QG, England.
+ Phone: +44 1223 334714
+
+ Last updated: 27 January 2000
+ Copyright (c) 1997-2000 University of Cambridge.
--- /dev/null
+.TH PCRE 3
+.SH NAME
+pcreposix - POSIX API for Perl-compatible regular expressions.
+.SH SYNOPSIS
+.B #include <pcreposix.h>
+.PP
+.SM
+.br
+.B int regcomp(regex_t *\fIpreg\fR, const char *\fIpattern\fR,
+.ti +5n
+.B int \fIcflags\fR);
+.PP
+.br
+.B int regexec(regex_t *\fIpreg\fR, const char *\fIstring\fR,
+.ti +5n
+.B size_t \fInmatch\fR, regmatch_t \fIpmatch\fR[], int \fIeflags\fR);
+.PP
+.br
+.B size_t regerror(int \fIerrcode\fR, const regex_t *\fIpreg\fR,
+.ti +5n
+.B char *\fIerrbuf\fR, size_t \fIerrbuf_size\fR);
+.PP
+.br
+.B void regfree(regex_t *\fIpreg\fR);
+
+
+.SH DESCRIPTION
+This set of functions provides a POSIX-style API to the PCRE regular expression
+package. See the \fBpcre\fR documentation for a description of the native API,
+which contains additional functionality.
+
+The functions described here are just wrapper functions that ultimately call
+the native API. Their prototypes are defined in the \fBpcreposix.h\fR header
+file, and on Unix systems the library itself is called \fBpcreposix.a\fR, so
+can be accessed by adding \fB-lpcreposix\fR to the command for linking an
+application which uses them. Because the POSIX functions call the native ones,
+it is also necessary to add \fR-lpcre\fR.
+
+I have implemented only those option bits that can be reasonably mapped to PCRE
+native options. In addition, the options REG_EXTENDED and REG_NOSUB are defined
+with the value zero. They have no effect, but since programs that are written
+to the POSIX interface often use them, this makes it easier to slot in PCRE as
+a replacement library. Other POSIX options are not even defined.
+
+When PCRE is called via these functions, it is only the API that is POSIX-like
+in style. The syntax and semantics of the regular expressions themselves are
+still those of Perl, subject to the setting of various PCRE options, as
+described below.
+
+The header for these functions is supplied as \fBpcreposix.h\fR to avoid any
+potential clash with other POSIX libraries. It can, of course, be renamed or
+aliased as \fBregex.h\fR, which is the "correct" name. It provides two
+structure types, \fIregex_t\fR for compiled internal forms, and
+\fIregmatch_t\fR for returning captured substrings. It also defines some
+constants whose names start with "REG_"; these are used for setting options and
+identifying error codes.
+
+
+.SH COMPILING A PATTERN
+
+The function \fBregcomp()\fR is called to compile a pattern into an
+internal form. The pattern is a C string terminated by a binary zero, and
+is passed in the argument \fIpattern\fR. The \fIpreg\fR argument is a pointer
+to a regex_t structure which is used as a base for storing information about
+the compiled expression.
+
+The argument \fIcflags\fR is either zero, or contains one or more of the bits
+defined by the following macros:
+
+ REG_ICASE
+
+The PCRE_CASELESS option is set when the expression is passed for compilation
+to the native function.
+
+ REG_NEWLINE
+
+The PCRE_MULTILINE option is set when the expression is passed for compilation
+to the native function.
+
+The yield of \fBregcomp()\fR is zero on success, and non-zero otherwise. The
+\fIpreg\fR structure is filled in on success, and one member of the structure
+is publicized: \fIre_nsub\fR contains the number of capturing subpatterns in
+the regular expression. Various error codes are defined in the header file.
+
+
+.SH MATCHING A PATTERN
+The function \fBregexec()\fR is called to match a pre-compiled pattern
+\fIpreg\fR against a given \fIstring\fR, which is terminated by a zero byte,
+subject to the options in \fIeflags\fR. These can be:
+
+ REG_NOTBOL
+
+The PCRE_NOTBOL option is set when calling the underlying PCRE matching
+function.
+
+ REG_NOTEOL
+
+The PCRE_NOTEOL option is set when calling the underlying PCRE matching
+function.
+
+The portion of the string that was matched, and also any captured substrings,
+are returned via the \fIpmatch\fR argument, which points to an array of
+\fInmatch\fR structures of type \fIregmatch_t\fR, containing the members
+\fIrm_so\fR and \fIrm_eo\fR. These contain the offset to the first character of
+each substring and the offset to the first character after the end of each
+substring, respectively. The 0th element of the vector relates to the entire
+portion of \fIstring\fR that was matched; subsequent elements relate to the
+capturing subpatterns of the regular expression. Unused entries in the array
+have both structure members set to -1.
+
+A successful match yields a zero return; various error codes are defined in the
+header file, of which REG_NOMATCH is the "expected" failure code.
+
+
+.SH ERROR MESSAGES
+The \fBregerror()\fR function maps a non-zero errorcode from either
+\fBregcomp\fR or \fBregexec\fR to a printable message. If \fIpreg\fR is not
+NULL, the error should have arisen from the use of that structure. A message
+terminated by a binary zero is placed in \fIerrbuf\fR. The length of the
+message, including the zero, is limited to \fIerrbuf_size\fR. The yield of the
+function is the size of buffer needed to hold the whole message.
+
+
+.SH STORAGE
+Compiling a regular expression causes memory to be allocated and associated
+with the \fIpreg\fR structure. The function \fBregfree()\fR frees all such
+memory, after which \fIpreg\fR may no longer be used as a compiled expression.
+
+
+.SH AUTHOR
+Philip Hazel <ph10@cam.ac.uk>
+.br
+University Computing Service,
+.br
+New Museums Site,
+.br
+Cambridge CB2 3QG, England.
+.br
+Phone: +44 1223 334714
+
+Copyright (c) 1997-1999 University of Cambridge.
--- /dev/null
+<HTML>
+<HEAD>
+<TITLE>pcreposix specification</TITLE>
+</HEAD>
+<body bgcolor="#FFFFFF" text="#00005A">
+<H1>pcreposix specification</H1>
+This HTML document has been generated automatically from the original man page.
+If there is any nonsense in it, please consult the man page in case the
+conversion went wrong.
+<UL>
+<LI><A NAME="TOC1" HREF="#SEC1">NAME</A>
+<LI><A NAME="TOC2" HREF="#SEC2">SYNOPSIS</A>
+<LI><A NAME="TOC3" HREF="#SEC3">DESCRIPTION</A>
+<LI><A NAME="TOC4" HREF="#SEC4">COMPILING A PATTERN</A>
+<LI><A NAME="TOC5" HREF="#SEC5">MATCHING A PATTERN</A>
+<LI><A NAME="TOC6" HREF="#SEC6">ERROR MESSAGES</A>
+<LI><A NAME="TOC7" HREF="#SEC7">STORAGE</A>
+<LI><A NAME="TOC8" HREF="#SEC8">AUTHOR</A>
+</UL>
+<LI><A NAME="SEC1" HREF="#TOC1">NAME</A>
+<P>
+pcreposix - POSIX API for Perl-compatible regular expressions.
+</P>
+<LI><A NAME="SEC2" HREF="#TOC1">SYNOPSIS</A>
+<P>
+<B>#include <pcreposix.h></B>
+</P>
+<P>
+<B>int regcomp(regex_t *<I>preg</I>, const char *<I>pattern</I>,</B>
+<B>int <I>cflags</I>);</B>
+</P>
+<P>
+<B>int regexec(regex_t *<I>preg</I>, const char *<I>string</I>,</B>
+<B>size_t <I>nmatch</I>, regmatch_t <I>pmatch</I>[], int <I>eflags</I>);</B>
+</P>
+<P>
+<B>size_t regerror(int <I>errcode</I>, const regex_t *<I>preg</I>,</B>
+<B>char *<I>errbuf</I>, size_t <I>errbuf_size</I>);</B>
+</P>
+<P>
+<B>void regfree(regex_t *<I>preg</I>);</B>
+</P>
+<LI><A NAME="SEC3" HREF="#TOC1">DESCRIPTION</A>
+<P>
+This set of functions provides a POSIX-style API to the PCRE regular expression
+package. See the <B>pcre</B> documentation for a description of the native API,
+which contains additional functionality.
+</P>
+<P>
+The functions described here are just wrapper functions that ultimately call
+the native API. Their prototypes are defined in the <B>pcreposix.h</B> header
+file, and on Unix systems the library itself is called <B>pcreposix.a</B>, so
+can be accessed by adding <B>-lpcreposix</B> to the command for linking an
+application which uses them. Because the POSIX functions call the native ones,
+it is also necessary to add \fR-lpcre\fR.
+</P>
+<P>
+I have implemented only those option bits that can be reasonably mapped to PCRE
+native options. In addition, the options REG_EXTENDED and REG_NOSUB are defined
+with the value zero. They have no effect, but since programs that are written
+to the POSIX interface often use them, this makes it easier to slot in PCRE as
+a replacement library. Other POSIX options are not even defined.
+</P>
+<P>
+When PCRE is called via these functions, it is only the API that is POSIX-like
+in style. The syntax and semantics of the regular expressions themselves are
+still those of Perl, subject to the setting of various PCRE options, as
+described below.
+</P>
+<P>
+The header for these functions is supplied as <B>pcreposix.h</B> to avoid any
+potential clash with other POSIX libraries. It can, of course, be renamed or
+aliased as <B>regex.h</B>, which is the "correct" name. It provides two
+structure types, <I>regex_t</I> for compiled internal forms, and
+<I>regmatch_t</I> for returning captured substrings. It also defines some
+constants whose names start with "REG_"; these are used for setting options and
+identifying error codes.
+</P>
+<LI><A NAME="SEC4" HREF="#TOC1">COMPILING A PATTERN</A>
+<P>
+The function <B>regcomp()</B> is called to compile a pattern into an
+internal form. The pattern is a C string terminated by a binary zero, and
+is passed in the argument <I>pattern</I>. The <I>preg</I> argument is a pointer
+to a regex_t structure which is used as a base for storing information about
+the compiled expression.
+</P>
+<P>
+The argument <I>cflags</I> is either zero, or contains one or more of the bits
+defined by the following macros:
+</P>
+<P>
+<PRE>
+ REG_ICASE
+</PRE>
+</P>
+<P>
+The PCRE_CASELESS option is set when the expression is passed for compilation
+to the native function.
+</P>
+<P>
+<PRE>
+ REG_NEWLINE
+</PRE>
+</P>
+<P>
+The PCRE_MULTILINE option is set when the expression is passed for compilation
+to the native function.
+</P>
+<P>
+The yield of <B>regcomp()</B> is zero on success, and non-zero otherwise. The
+<I>preg</I> structure is filled in on success, and one member of the structure
+is publicized: <I>re_nsub</I> contains the number of capturing subpatterns in
+the regular expression. Various error codes are defined in the header file.
+</P>
+<LI><A NAME="SEC5" HREF="#TOC1">MATCHING A PATTERN</A>
+<P>
+The function <B>regexec()</B> is called to match a pre-compiled pattern
+<I>preg</I> against a given <I>string</I>, which is terminated by a zero byte,
+subject to the options in <I>eflags</I>. These can be:
+</P>
+<P>
+<PRE>
+ REG_NOTBOL
+</PRE>
+</P>
+<P>
+The PCRE_NOTBOL option is set when calling the underlying PCRE matching
+function.
+</P>
+<P>
+<PRE>
+ REG_NOTEOL
+</PRE>
+</P>
+<P>
+The PCRE_NOTEOL option is set when calling the underlying PCRE matching
+function.
+</P>
+<P>
+The portion of the string that was matched, and also any captured substrings,
+are returned via the <I>pmatch</I> argument, which points to an array of
+<I>nmatch</I> structures of type <I>regmatch_t</I>, containing the members
+<I>rm_so</I> and <I>rm_eo</I>. These contain the offset to the first character of
+each substring and the offset to the first character after the end of each
+substring, respectively. The 0th element of the vector relates to the entire
+portion of <I>string</I> that was matched; subsequent elements relate to the
+capturing subpatterns of the regular expression. Unused entries in the array
+have both structure members set to -1.
+</P>
+<P>
+A successful match yields a zero return; various error codes are defined in the
+header file, of which REG_NOMATCH is the "expected" failure code.
+</P>
+<LI><A NAME="SEC6" HREF="#TOC1">ERROR MESSAGES</A>
+<P>
+The <B>regerror()</B> function maps a non-zero errorcode from either
+<B>regcomp</B> or <B>regexec</B> to a printable message. If <I>preg</I> is not
+NULL, the error should have arisen from the use of that structure. A message
+terminated by a binary zero is placed in <I>errbuf</I>. The length of the
+message, including the zero, is limited to <I>errbuf_size</I>. The yield of the
+function is the size of buffer needed to hold the whole message.
+</P>
+<LI><A NAME="SEC7" HREF="#TOC1">STORAGE</A>
+<P>
+Compiling a regular expression causes memory to be allocated and associated
+with the <I>preg</I> structure. The function <B>regfree()</B> frees all such
+memory, after which <I>preg</I> may no longer be used as a compiled expression.
+</P>
+<LI><A NAME="SEC8" HREF="#TOC1">AUTHOR</A>
+<P>
+Philip Hazel <ph10@cam.ac.uk>
+<BR>
+University Computing Service,
+<BR>
+New Museums Site,
+<BR>
+Cambridge CB2 3QG, England.
+<BR>
+Phone: +44 1223 334714
+</P>
+<P>
+Copyright (c) 1997-1999 University of Cambridge.
--- /dev/null
+NAME
+ pcreposix - POSIX API for Perl-compatible regular expres-
+ sions.
+
+
+
+SYNOPSIS
+ #include <pcreposix.h>
+
+ int regcomp(regex_t *preg, const char *pattern,
+ int cflags);
+
+ int regexec(regex_t *preg, const char *string,
+ size_t nmatch, regmatch_t pmatch[], int eflags);
+
+ size_t regerror(int errcode, const regex_t *preg,
+ char *errbuf, size_t errbuf_size);
+
+ void regfree(regex_t *preg);
+
+
+
+DESCRIPTION
+ This set of functions provides a POSIX-style API to the PCRE
+ regular expression package. See the pcre documentation for a
+ description of the native API, which contains additional
+ functionality.
+
+ The functions described here are just wrapper functions that
+ ultimately call the native API. Their prototypes are defined
+ in the pcreposix.h header file, and on Unix systems the
+ library itself is called pcreposix.a, so can be accessed by
+ adding -lpcreposix to the command for linking an application
+ which uses them. Because the POSIX functions call the native
+ ones, it is also necessary to add -lpcre.
+
+ I have implemented only those option bits that can be rea-
+ sonably mapped to PCRE native options. In addition, the
+ options REG_EXTENDED and REG_NOSUB are defined with the
+ value zero. They have no effect, but since programs that are
+ written to the POSIX interface often use them, this makes it
+ easier to slot in PCRE as a replacement library. Other POSIX
+ options are not even defined.
+
+ When PCRE is called via these functions, it is only the API
+ that is POSIX-like in style. The syntax and semantics of the
+ regular expressions themselves are still those of Perl, sub-
+ ject to the setting of various PCRE options, as described
+ below.
+
+ The header for these functions is supplied as pcreposix.h to
+ avoid any potential clash with other POSIX libraries. It
+ can, of course, be renamed or aliased as regex.h, which is
+ the "correct" name. It provides two structure types, regex_t
+ for compiled internal forms, and regmatch_t for returning
+ captured substrings. It also defines some constants whose
+ names start with "REG_"; these are used for setting options
+ and identifying error codes.
+
+
+
+COMPILING A PATTERN
+ The function regcomp() is called to compile a pattern into
+ an internal form. The pattern is a C string terminated by a
+ binary zero, and is passed in the argument pattern. The preg
+ argument is a pointer to a regex_t structure which is used
+ as a base for storing information about the compiled expres-
+ sion.
+
+ The argument cflags is either zero, or contains one or more
+ of the bits defined by the following macros:
+
+ REG_ICASE
+
+ The PCRE_CASELESS option is set when the expression is
+ passed for compilation to the native function.
+
+ REG_NEWLINE
+
+ The PCRE_MULTILINE option is set when the expression is
+ passed for compilation to the native function.
+
+ The yield of regcomp() is zero on success, and non-zero oth-
+ erwise. The preg structure is filled in on success, and one
+ member of the structure is publicized: re_nsub contains the
+ number of capturing subpatterns in the regular expression.
+ Various error codes are defined in the header file.
+
+
+
+MATCHING A PATTERN
+ The function regexec() is called to match a pre-compiled
+ pattern preg against a given string, which is terminated by
+ a zero byte, subject to the options in eflags. These can be:
+
+ REG_NOTBOL
+
+ The PCRE_NOTBOL option is set when calling the underlying
+ PCRE matching function.
+
+ REG_NOTEOL
+
+ The PCRE_NOTEOL option is set when calling the underlying
+ PCRE matching function.
+
+ The portion of the string that was matched, and also any
+ captured substrings, are returned via the pmatch argument,
+ which points to an array of nmatch structures of type
+ regmatch_t, containing the members rm_so and rm_eo. These
+ contain the offset to the first character of each substring
+ and the offset to the first character after the end of each
+ substring, respectively. The 0th element of the vector
+ relates to the entire portion of string that was matched;
+ subsequent elements relate to the capturing subpatterns of
+ the regular expression. Unused entries in the array have
+ both structure members set to -1.
+
+ A successful match yields a zero return; various error codes
+ are defined in the header file, of which REG_NOMATCH is the
+ "expected" failure code.
+
+
+
+ERROR MESSAGES
+ The regerror() function maps a non-zero errorcode from
+ either regcomp or regexec to a printable message. If preg is
+ not NULL, the error should have arisen from the use of that
+ structure. A message terminated by a binary zero is placed
+ in errbuf. The length of the message, including the zero, is
+ limited to errbuf_size. The yield of the function is the
+ size of buffer needed to hold the whole message.
+
+
+
+STORAGE
+ Compiling a regular expression causes memory to be allocated
+ and associated with the preg structure. The function reg-
+ free() frees all such memory, after which preg may no longer
+ be used as a compiled expression.
+
+
+
+AUTHOR
+ Philip Hazel <ph10@cam.ac.uk>
+ University Computing Service,
+ New Museums Site,
+ Cambridge CB2 3QG, England.
+ Phone: +44 1223 334714
+
+ Copyright (c) 1997-1999 University of Cambridge.
--- /dev/null
+The pcretest program
+--------------------
+
+This program is intended for testing PCRE, but it can also be used for
+experimenting with regular expressions.
+
+If it is given two filename arguments, it reads from the first and writes to
+the second. If it is given only one filename argument, it reads from that file
+and writes to stdout. Otherwise, it reads from stdin and writes to stdout, and
+prompts for each line of input, using "re>" to prompt for regular expressions,
+and "data>" to prompt for data lines.
+
+The program handles any number of sets of input on a single input file. Each
+set starts with a regular expression, and continues with any number of data
+lines to be matched against the pattern. An empty line signals the end of the
+data lines, at which point a new regular expression is read. The regular
+expressions are given enclosed in any non-alphameric delimiters other than
+backslash, for example
+
+ /(a|bc)x+yz/
+
+White space before the initial delimiter is ignored. A regular expression may
+be continued over several input lines, in which case the newline characters are
+included within it. See the test input files in the testdata directory for many
+examples. It is possible to include the delimiter within the pattern by
+escaping it, for example
+
+ /abc\/def/
+
+If you do so, the escape and the delimiter form part of the pattern, but since
+delimiters are always non-alphameric, this does not affect its interpretation.
+If the terminating delimiter is immediately followed by a backslash, for
+example,
+
+ /abc/\
+
+then a backslash is added to the end of the pattern. This is done to provide a
+way of testing the error condition that arises if a pattern finishes with a
+backslash, because
+
+ /abc\/
+
+is interpreted as the first line of a pattern that starts with "abc/", causing
+pcretest to read the next line as a continuation of the regular expression.
+
+The pattern may be followed by i, m, s, or x to set the PCRE_CASELESS,
+PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively. For
+example:
+
+ /caseless/i
+
+These modifier letters have the same effect as they do in Perl. There are
+others which set PCRE options that do not correspond to anything in Perl: /A,
+/E, and /X set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and PCRE_EXTRA respectively.
+
+Searching for all possible matches within each subject string can be requested
+by the /g or /G modifier. After finding a match, PCRE is called again to search
+the remainder of the subject string. The difference between /g and /G is that
+the former uses the startoffset argument to pcre_exec() to start searching at
+a new point within the entire string (which is in effect what Perl does),
+whereas the latter passes over a shortened substring. This makes a difference
+to the matching process if the pattern begins with a lookbehind assertion
+(including \b or \B).
+
+If any call to pcre_exec() in a /g or /G sequence matches an empty string, the
+next call is done with the PCRE_NOTEMPTY flag set so that it cannot match an
+empty string again at the same point. If however, this second match fails, the
+start offset is advanced by one, and the match is retried. This imitates the
+way Perl handles such cases when using the /g modifier or the split() function.
+
+There are a number of other modifiers for controlling the way pcretest
+operates.
+
+The /+ modifier requests that as well as outputting the substring that matched
+the entire pattern, pcretest should in addition output the remainder of the
+subject string. This is useful for tests where the subject contains multiple
+copies of the same substring.
+
+The /L modifier must be followed directly by the name of a locale, for example,
+
+ /pattern/Lfr
+
+For this reason, it must be the last modifier letter. The given locale is set,
+pcre_maketables() is called to build a set of character tables for the locale,
+and this is then passed to pcre_compile() when compiling the regular
+expression. Without an /L modifier, NULL is passed as the tables pointer; that
+is, /L applies only to the expression on which it appears.
+
+The /I modifier requests that pcretest output information about the compiled
+expression (whether it is anchored, has a fixed first character, and so on). It
+does this by calling pcre_fullinfo() after compiling an expression, and
+outputting the information it gets back. If the pattern is studied, the results
+of that are also output.
+
+The /D modifier is a PCRE debugging feature, which also assumes /I. It causes
+the internal form of compiled regular expressions to be output after
+compilation.
+
+The /S modifier causes pcre_study() to be called after the expression has been
+compiled, and the results used when the expression is matched.
+
+The /M modifier causes the size of memory block used to hold the compiled
+pattern to be output.
+
+Finally, the /P modifier causes pcretest to call PCRE via the POSIX wrapper API
+rather than its native API. When this is done, all other modifiers except /i,
+/m, and /+ are ignored. REG_ICASE is set if /i is present, and REG_NEWLINE is
+set if /m is present. The wrapper functions force PCRE_DOLLAR_ENDONLY always,
+and PCRE_DOTALL unless REG_NEWLINE is set.
+
+Before each data line is passed to pcre_exec(), leading and trailing whitespace
+is removed, and it is then scanned for \ escapes. The following are recognized:
+
+ \a alarm (= BEL)
+ \b backspace
+ \e escape
+ \f formfeed
+ \n newline
+ \r carriage return
+ \t tab
+ \v vertical tab
+ \nnn octal character (up to 3 octal digits)
+ \xhh hexadecimal character (up to 2 hex digits)
+
+ \A pass the PCRE_ANCHORED option to pcre_exec()
+ \B pass the PCRE_NOTBOL option to pcre_exec()
+ \Cdd call pcre_copy_substring() for substring dd after a successful match
+ (any decimal number less than 32)
+ \Gdd call pcre_get_substring() for substring dd after a successful match
+ (any decimal number less than 32)
+ \L call pcre_get_substringlist() after a successful match
+ \N pass the PCRE_NOTEMPTY option to pcre_exec()
+ \Odd set the size of the output vector passed to pcre_exec() to dd
+ (any number of decimal digits)
+ \Z pass the PCRE_NOTEOL option to pcre_exec()
+
+A backslash followed by anything else just escapes the anything else. If the
+very last character is a backslash, it is ignored. This gives a way of passing
+an empty line as data, since a real empty line terminates the data input.
+
+If /P was present on the regex, causing the POSIX wrapper API to be used, only
+\B, and \Z have any effect, causing REG_NOTBOL and REG_NOTEOL to be passed to
+regexec() respectively.
+
+When a match succeeds, pcretest outputs the list of captured substrings that
+pcre_exec() returns, starting with number 0 for the string that matched the
+whole pattern. Here is an example of an interactive pcretest run.
+
+ $ pcretest
+ PCRE version 2.06 08-Jun-1999
+
+ re> /^abc(\d+)/
+ data> abc123
+ 0: abc123
+ 1: 123
+ data> xyz
+ No match
+
+If the strings contain any non-printing characters, they are output as \0x
+escapes. If the pattern has the /+ modifier, then the output for substring 0 is
+followed by the the rest of the subject string, identified by "0+" like this:
+
+ re> /cat/+
+ data> cataract
+ 0: cat
+ 0+ aract
+
+If the pattern has the /g or /G modifier, the results of successive matching
+attempts are output in sequence, like this:
+
+ re> /\Bi(\w\w)/g
+ data> Mississippi
+ 0: iss
+ 1: ss
+ 0: iss
+ 1: ss
+ 0: ipp
+ 1: pp
+
+"No match" is output only if the first match attempt fails.
+
+If any of \C, \G, or \L are present in a data line that is successfully
+matched, the substrings extracted by the convenience functions are output with
+C, G, or L after the string number instead of a colon. This is in addition to
+the normal full list. The string length (that is, the return from the
+extraction function) is given in parentheses after each string for \C and \G.
+
+Note that while patterns can be continued over several lines (a plain ">"
+prompt is used for continuations), data lines may not. However newlines can be
+included in data by means of the \n escape.
+
+If the -p option is given to pcretest, it is equivalent to adding /P to each
+regular expression: the POSIX wrapper API is used to call PCRE. None of the
+following flags has any effect in this case.
+
+If the option -d is given to pcretest, it is equivalent to adding /D to each
+regular expression: the internal form is output after compilation.
+
+If the option -i is given to pcretest, it is equivalent to adding /I to each
+regular expression: information about the compiled pattern is given after
+compilation.
+
+If the option -m is given to pcretest, it outputs the size of each compiled
+pattern after it has been compiled. It is equivalent to adding /M to each
+regular expression. For compatibility with earlier versions of pcretest, -s is
+a synonym for -m.
+
+If the -t option is given, each compile, study, and match is run 20000 times
+while being timed, and the resulting time per compile or match is output in
+milliseconds. Do not set -t with -s, because you will then get the size output
+20000 times and the timing will be distorted. If you want to change the number
+of repetitions used for timing, edit the definition of LOOPREPEAT at the top of
+pcretest.c
+
+Philip Hazel <ph10@cam.ac.uk>
+January 2000
--- /dev/null
+The perltest program
+--------------------
+
+The perltest program tests Perl's regular expressions; it has the same
+specification as pcretest, and so can be given identical input, except that
+input patterns can be followed only by Perl's lower case modifiers and /+ (as
+used by pcretest), which is recognized and handled by the program.
+
+The data lines are processed as Perl double-quoted strings, so if they contain
+" \ $ or @ characters, these have to be escaped. For this reason, all such
+characters in testinput1 and testinput3 are escaped so that they can be used
+for perltest as well as for pcretest, and the special upper case modifiers such
+as /A that pcretest recognizes are not used in these files. The output should
+be identical, apart from the initial identifying banner.
+
+The testinput2 and testinput4 files are not suitable for feeding to perltest,
+since they do make use of the special upper case modifiers and escapes that
+pcretest uses to test some features of PCRE. The first of these files also
+contains malformed regular expressions, in order to check that PCRE diagnoses
+them correctly.
+
+Philip Hazel <ph10@cam.ac.uk>
+January 2000
--- /dev/null
+.TH PGREP 1
+.SH NAME
+pgrep - a grep with Perl-compatible regular expressions.
+.SH SYNOPSIS
+.B pgrep [-Vchilnsvx] pattern [file] ...
+
+
+.SH DESCRIPTION
+\fBpgrep\fR searches files for character patterns, in the same way as other
+grep commands do, but it uses the PCRE regular expression library to support
+patterns that are compatible with the regular expressions of Perl 5. See
+\fBpcre(3)\fR for a full description of syntax and semantics.
+
+If no files are specified, \fBpgrep\fR reads the standard input. By default,
+each line that matches the pattern is copied to the standard output, and if
+there is more than one file, the file name is printed before each line of
+output. However, there are options that can change how \fBpgrep\fR behaves.
+
+Lines are limited to BUFSIZ characters. BUFSIZ is defined in \fB<stdio.h>\fR.
+The newline character is removed from the end of each line before it is matched
+against the pattern.
+
+
+.SH OPTIONS
+.TP 10
+\fB-V\fR
+Write the version number of the PCRE library being used to the standard error
+stream.
+.TP
+\fB-c\fR
+Do not print individual lines; instead just print a count of the number of
+lines that would otherwise have been printed. If several files are given, a
+count is printed for each of them.
+.TP
+\fB-h\fR
+Suppress printing of filenames when searching multiple files.
+.TP
+\fB-i\fR
+Ignore upper/lower case distinctions during comparisons.
+.TP
+\fB-l\fR
+Instead of printing lines from the files, just print the names of the files
+containing lines that would have been printed. Each file name is printed
+once, on a separate line.
+.TP
+\fB-n\fR
+Precede each line by its line number in the file.
+.TP
+\fB-s\fR
+Work silently, that is, display nothing except error messages.
+The exit status indicates whether any matches were found.
+.TP
+\fB-v\fR
+Invert the sense of the match, so that lines which do \fInot\fR match the
+pattern are now the ones that are found.
+.TP
+\fB-x\fR
+Force the pattern to be anchored (it must start matching at the beginning of
+the line) and in addition, require it to match the entire line. This is
+equivalent to having ^ and $ characters at the start and end of each
+alternative branch in the regular expression.
+
+
+.SH SEE ALSO
+\fBpcre(3)\fR, Perl 5 documentation
+
+
+.SH DIAGNOSTICS
+Exit status is 0 if any matches were found, 1 if no matches were found, and 2
+for syntax errors or inacessible files (even if matches were found).
+
+
+.SH AUTHOR
+Philip Hazel <ph10@cam.ac.uk>
+.br
+Copyright (c) 1997-1999 University of Cambridge.
--- /dev/null
+<HTML>
+<HEAD>
+<TITLE>pgrep specification</TITLE>
+</HEAD>
+<body bgcolor="#FFFFFF" text="#00005A">
+<H1>pgrep specification</H1>
+This HTML document has been generated automatically from the original man page.
+If there is any nonsense in it, please consult the man page in case the
+conversion went wrong.
+<UL>
+<LI><A NAME="TOC1" HREF="#SEC1">NAME</A>
+<LI><A NAME="TOC2" HREF="#SEC2">SYNOPSIS</A>
+<LI><A NAME="TOC3" HREF="#SEC3">DESCRIPTION</A>
+<LI><A NAME="TOC4" HREF="#SEC4">OPTIONS</A>
+<LI><A NAME="TOC5" HREF="#SEC5">SEE ALSO</A>
+<LI><A NAME="TOC6" HREF="#SEC6">DIAGNOSTICS</A>
+<LI><A NAME="TOC7" HREF="#SEC7">AUTHOR</A>
+</UL>
+<LI><A NAME="SEC1" HREF="#TOC1">NAME</A>
+<P>
+pgrep - a grep with Perl-compatible regular expressions.
+</P>
+<LI><A NAME="SEC2" HREF="#TOC1">SYNOPSIS</A>
+<P>
+<B>pgrep [-Vchilnsvx] pattern [file] ...</B>
+</P>
+<LI><A NAME="SEC3" HREF="#TOC1">DESCRIPTION</A>
+<P>
+<B>pgrep</B> searches files for character patterns, in the same way as other
+grep commands do, but it uses the PCRE regular expression library to support
+patterns that are compatible with the regular expressions of Perl 5. See
+<B>pcre(3)</B> for a full description of syntax and semantics.
+</P>
+<P>
+If no files are specified, <B>pgrep</B> reads the standard input. By default,
+each line that matches the pattern is copied to the standard output, and if
+there is more than one file, the file name is printed before each line of
+output. However, there are options that can change how <B>pgrep</B> behaves.
+</P>
+<P>
+Lines are limited to BUFSIZ characters. BUFSIZ is defined in <B><stdio.h></B>.
+The newline character is removed from the end of each line before it is matched
+against the pattern.
+</P>
+<LI><A NAME="SEC4" HREF="#TOC1">OPTIONS</A>
+<P>
+<B>-V</B>
+Write the version number of the PCRE library being used to the standard error
+stream.
+</P>
+<P>
+<B>-c</B>
+Do not print individual lines; instead just print a count of the number of
+lines that would otherwise have been printed. If several files are given, a
+count is printed for each of them.
+</P>
+<P>
+<B>-h</B>
+Suppress printing of filenames when searching multiple files.
+</P>
+<P>
+<B>-i</B>
+Ignore upper/lower case distinctions during comparisons.
+</P>
+<P>
+<B>-l</B>
+Instead of printing lines from the files, just print the names of the files
+containing lines that would have been printed. Each file name is printed
+once, on a separate line.
+</P>
+<P>
+<B>-n</B>
+Precede each line by its line number in the file.
+</P>
+<P>
+<B>-s</B>
+Work silently, that is, display nothing except error messages.
+The exit status indicates whether any matches were found.
+</P>
+<P>
+<B>-v</B>
+Invert the sense of the match, so that lines which do <I>not</I> match the
+pattern are now the ones that are found.
+</P>
+<P>
+<B>-x</B>
+Force the pattern to be anchored (it must start matching at the beginning of
+the line) and in addition, require it to match the entire line. This is
+equivalent to having ^ and $ characters at the start and end of each
+alternative branch in the regular expression.
+</P>
+<LI><A NAME="SEC5" HREF="#TOC1">SEE ALSO</A>
+<P>
+<B>pcre(3)</B>, Perl 5 documentation
+</P>
+<LI><A NAME="SEC6" HREF="#TOC1">DIAGNOSTICS</A>
+<P>
+Exit status is 0 if any matches were found, 1 if no matches were found, and 2
+for syntax errors or inacessible files (even if matches were found).
+</P>
+<LI><A NAME="SEC7" HREF="#TOC1">AUTHOR</A>
+<P>
+Philip Hazel <ph10@cam.ac.uk>
+<BR>
+Copyright (c) 1997-1999 University of Cambridge.
--- /dev/null
+NAME
+ pgrep - a grep with Perl-compatible regular expressions.
+
+
+
+SYNOPSIS
+ pgrep [-Vchilnsvx] pattern [file] ...
+
+
+
+DESCRIPTION
+ pgrep searches files for character patterns, in the same way
+ as other grep commands do, but it uses the PCRE regular
+ expression library to support patterns that are compatible
+ with the regular expressions of Perl 5. See pcre(3) for a
+ full description of syntax and semantics.
+
+ If no files are specified, pgrep reads the standard input.
+ By default, each line that matches the pattern is copied to
+ the standard output, and if there is more than one file, the
+ file name is printed before each line of output. However,
+ there are options that can change how pgrep behaves.
+
+ Lines are limited to BUFSIZ characters. BUFSIZ is defined in
+ <stdio.h>. The newline character is removed from the end of
+ each line before it is matched against the pattern.
+
+
+
+OPTIONS
+ -V Write the version number of the PCRE library being
+ used to the standard error stream.
+
+ -c Do not print individual lines; instead just print
+ a count of the number of lines that would other-
+ wise have been printed. If several files are
+ given, a count is printed for each of them.
+
+ -h Suppress printing of filenames when searching mul-
+ tiple files.
+
+ -i Ignore upper/lower case distinctions during com-
+ parisons.
+
+ -l Instead of printing lines from the files, just
+ print the names of the files containing lines that
+ would have been printed. Each file name is printed
+ once, on a separate line.
+
+ -n Precede each line by its line number in the file.
+
+ -s Work silently, that is, display nothing except
+ error messages. The exit status indicates whether
+ any matches were found.
+
+ -v Invert the sense of the match, so that lines which
+ do not match the pattern are now the ones that are
+ found.
+
+ -x Force the pattern to be anchored (it must start
+ matching at the beginning of the line) and in
+ addition, require it to match the entire line.
+ This is equivalent to having ^ and $ characters at
+ the start and end of each alternative branch in
+ the regular expression.
+
+
+
+SEE ALSO
+ pcre(3), Perl 5 documentation
+
+
+
+
+
+DIAGNOSTICS
+ Exit status is 0 if any matches were found, 1 if no matches
+ were found, and 2 for syntax errors or inacessible files
+ (even if matches were found).
+
+
+
+AUTHOR
+ Philip Hazel <ph10@cam.ac.uk>
+ Copyright (c) 1997-1999 University of Cambridge.
+
--- /dev/null
+/the quick brown fox/
+ the quick brown fox
+ The quick brown FOX
+ What do you know about the quick brown fox?
+ What do you know about THE QUICK BROWN FOX?
+
+/The quick brown fox/i
+ the quick brown fox
+ The quick brown FOX
+ What do you know about the quick brown fox?
+ What do you know about THE QUICK BROWN FOX?
+
+/abcd\t\n\r\f\a\e\071\x3b\$\\\?caxyz/
+ abcd\t\n\r\f\a\e9;\$\\?caxyz
+
+/a*abc?xyz+pqr{3}ab{2,}xy{4,5}pq{0,6}AB{0,}zz/
+ abxyzpqrrrabbxyyyypqAzz
+ abxyzpqrrrabbxyyyypqAzz
+ aabxyzpqrrrabbxyyyypqAzz
+ aaabxyzpqrrrabbxyyyypqAzz
+ aaaabxyzpqrrrabbxyyyypqAzz
+ abcxyzpqrrrabbxyyyypqAzz
+ aabcxyzpqrrrabbxyyyypqAzz
+ aaabcxyzpqrrrabbxyyyypAzz
+ aaabcxyzpqrrrabbxyyyypqAzz
+ aaabcxyzpqrrrabbxyyyypqqAzz
+ aaabcxyzpqrrrabbxyyyypqqqAzz
+ aaabcxyzpqrrrabbxyyyypqqqqAzz
+ aaabcxyzpqrrrabbxyyyypqqqqqAzz
+ aaabcxyzpqrrrabbxyyyypqqqqqqAzz
+ aaaabcxyzpqrrrabbxyyyypqAzz
+ abxyzzpqrrrabbxyyyypqAzz
+ aabxyzzzpqrrrabbxyyyypqAzz
+ aaabxyzzzzpqrrrabbxyyyypqAzz
+ aaaabxyzzzzpqrrrabbxyyyypqAzz
+ abcxyzzpqrrrabbxyyyypqAzz
+ aabcxyzzzpqrrrabbxyyyypqAzz
+ aaabcxyzzzzpqrrrabbxyyyypqAzz
+ aaaabcxyzzzzpqrrrabbxyyyypqAzz
+ aaaabcxyzzzzpqrrrabbbxyyyypqAzz
+ aaaabcxyzzzzpqrrrabbbxyyyyypqAzz
+ aaabcxyzpqrrrabbxyyyypABzz
+ aaabcxyzpqrrrabbxyyyypABBzz
+ >>>aaabxyzpqrrrabbxyyyypqAzz
+ >aaaabxyzpqrrrabbxyyyypqAzz
+ >>>>abcxyzpqrrrabbxyyyypqAzz
+ *** Failers
+ abxyzpqrrabbxyyyypqAzz
+ abxyzpqrrrrabbxyyyypqAzz
+ abxyzpqrrrabxyyyypqAzz
+ aaaabcxyzzzzpqrrrabbbxyyyyyypqAzz
+ aaaabcxyzzzzpqrrrabbbxyyypqAzz
+ aaabcxyzpqrrrabbxyyyypqqqqqqqAzz
+
+/^(abc){1,2}zz/
+ abczz
+ abcabczz
+ *** Failers
+ zz
+ abcabcabczz
+ >>abczz
+
+/^(b+?|a){1,2}?c/
+ bc
+ bbc
+ bbbc
+ bac
+ bbac
+ aac
+ abbbbbbbbbbbc
+ bbbbbbbbbbbac
+ *** Failers
+ aaac
+ abbbbbbbbbbbac
+
+/^(b+|a){1,2}c/
+ bc
+ bbc
+ bbbc
+ bac
+ bbac
+ aac
+ abbbbbbbbbbbc
+ bbbbbbbbbbbac
+ *** Failers
+ aaac
+ abbbbbbbbbbbac
+
+/^(b+|a){1,2}?bc/
+ bbc
+
+/^(b*|ba){1,2}?bc/
+ babc
+ bbabc
+ bababc
+ *** Failers
+ bababbc
+ babababc
+
+/^(ba|b*){1,2}?bc/
+ babc
+ bbabc
+ bababc
+ *** Failers
+ bababbc
+ babababc
+
+/^\ca\cA\c[\c{\c:/
+ \x01\x01\e;z
+
+/^[ab\]cde]/
+ athing
+ bthing
+ ]thing
+ cthing
+ dthing
+ ething
+ *** Failers
+ fthing
+ [thing
+ \\thing
+
+/^[]cde]/
+ ]thing
+ cthing
+ dthing
+ ething
+ *** Failers
+ athing
+ fthing
+
+/^[^ab\]cde]/
+ fthing
+ [thing
+ \\thing
+ *** Failers
+ athing
+ bthing
+ ]thing
+ cthing
+ dthing
+ ething
+
+/^[^]cde]/
+ athing
+ fthing
+ *** Failers
+ ]thing
+ cthing
+ dthing
+ ething
+
+/^\\81/
+ \81
+
+/^ÿ/
+ ÿ
+
+/^[0-9]+$/
+ 0
+ 1
+ 2
+ 3
+ 4
+ 5
+ 6
+ 7
+ 8
+ 9
+ 10
+ 100
+ *** Failers
+ abc
+
+/^.*nter/
+ enter
+ inter
+ uponter
+
+/^xxx[0-9]+$/
+ xxx0
+ xxx1234
+ *** Failers
+ xxx
+
+/^.+[0-9][0-9][0-9]$/
+ x123
+ xx123
+ 123456
+ *** Failers
+ 123
+ x1234
+
+/^.+?[0-9][0-9][0-9]$/
+ x123
+ xx123
+ 123456
+ *** Failers
+ 123
+ x1234
+
+/^([^!]+)!(.+)=apquxz\.ixr\.zzz\.ac\.uk$/
+ abc!pqr=apquxz.ixr.zzz.ac.uk
+ *** Failers
+ !pqr=apquxz.ixr.zzz.ac.uk
+ abc!=apquxz.ixr.zzz.ac.uk
+ abc!pqr=apquxz:ixr.zzz.ac.uk
+ abc!pqr=apquxz.ixr.zzz.ac.ukk
+
+/:/
+ Well, we need a colon: somewhere
+ *** Fail if we don't
+
+/([\da-f:]+)$/i
+ 0abc
+ abc
+ fed
+ E
+ ::
+ 5f03:12C0::932e
+ fed def
+ Any old stuff
+ *** Failers
+ 0zzz
+ gzzz
+ fed\x20
+ Any old rubbish
+
+/^.*\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$/
+ .1.2.3
+ A.12.123.0
+ *** Failers
+ .1.2.3333
+ 1.2.3
+ 1234.2.3
+
+/^(\d+)\s+IN\s+SOA\s+(\S+)\s+(\S+)\s*\(\s*$/
+ 1 IN SOA non-sp1 non-sp2(
+ 1 IN SOA non-sp1 non-sp2 (
+ *** Failers
+ 1IN SOA non-sp1 non-sp2(
+
+/^[a-zA-Z\d][a-zA-Z\d\-]*(\.[a-zA-Z\d][a-zA-z\d\-]*)*\.$/
+ a.
+ Z.
+ 2.
+ ab-c.pq-r.
+ sxk.zzz.ac.uk.
+ x-.y-.
+ *** Failers
+ -abc.peq.
+
+/^\*\.[a-z]([a-z\-\d]*[a-z\d]+)?(\.[a-z]([a-z\-\d]*[a-z\d]+)?)*$/
+ *.a
+ *.b0-a
+ *.c3-b.c
+ *.c-a.b-c
+ *** Failers
+ *.0
+ *.a-
+ *.a-b.c-
+ *.c-a.0-c
+
+/^(?=ab(de))(abd)(e)/
+ abde
+
+/^(?!(ab)de|x)(abd)(f)/
+ abdf
+
+/^(?=(ab(cd)))(ab)/
+ abcd
+
+/^[\da-f](\.[\da-f])*$/i
+ a.b.c.d
+ A.B.C.D
+ a.b.c.1.2.3.C
+
+/^\".*\"\s*(;.*)?$/
+ \"1234\"
+ \"abcd\" ;
+ \"\" ; rhubarb
+ *** Failers
+ \"1234\" : things
+
+/^$/
+ \
+ *** Failers
+
+/ ^ a (?# begins with a) b\sc (?# then b c) $ (?# then end)/x
+ ab c
+ *** Failers
+ abc
+ ab cde
+
+/(?x) ^ a (?# begins with a) b\sc (?# then b c) $ (?# then end)/
+ ab c
+ *** Failers
+ abc
+ ab cde
+
+/^ a\ b[c ]d $/x
+ a bcd
+ a b d
+ *** Failers
+ abcd
+ ab d
+
+/^(a(b(c)))(d(e(f)))(h(i(j)))(k(l(m)))$/
+ abcdefhijklm
+
+/^(?:a(b(c)))(?:d(e(f)))(?:h(i(j)))(?:k(l(m)))$/
+ abcdefhijklm
+
+/^[\w][\W][\s][\S][\d][\D][\b][\n][\c]][\022]/
+ a+ Z0+\x08\n\x1d\x12
+
+/^[.^$|()*+?{,}]+/
+ .^\$(*+)|{?,?}
+
+/^a*\w/
+ z
+ az
+ aaaz
+ a
+ aa
+ aaaa
+ a+
+ aa+
+
+/^a*?\w/
+ z
+ az
+ aaaz
+ a
+ aa
+ aaaa
+ a+
+ aa+
+
+/^a+\w/
+ az
+ aaaz
+ aa
+ aaaa
+ aa+
+
+/^a+?\w/
+ az
+ aaaz
+ aa
+ aaaa
+ aa+
+
+/^\d{8}\w{2,}/
+ 1234567890
+ 12345678ab
+ 12345678__
+ *** Failers
+ 1234567
+
+/^[aeiou\d]{4,5}$/
+ uoie
+ 1234
+ 12345
+ aaaaa
+ *** Failers
+ 123456
+
+/^[aeiou\d]{4,5}?/
+ uoie
+ 1234
+ 12345
+ aaaaa
+ 123456
+
+/\A(abc|def)=(\1){2,3}\Z/
+ abc=abcabc
+ def=defdefdef
+ *** Failers
+ abc=defdef
+
+/^(a)(b)(c)(d)(e)(f)(g)(h)(i)(j)(k)\11*(\3\4)\1(?#)2$/
+ abcdefghijkcda2
+ abcdefghijkkkkcda2
+
+/(cat(a(ract|tonic)|erpillar)) \1()2(3)/
+ cataract cataract23
+ catatonic catatonic23
+ caterpillar caterpillar23
+
+
+/^From +([^ ]+) +[a-zA-Z][a-zA-Z][a-zA-Z] +[a-zA-Z][a-zA-Z][a-zA-Z] +[0-9]?[0-9] +[0-9][0-9]:[0-9][0-9]/
+ From abcd Mon Sep 01 12:33:02 1997
+
+/^From\s+\S+\s+([a-zA-Z]{3}\s+){2}\d{1,2}\s+\d\d:\d\d/
+ From abcd Mon Sep 01 12:33:02 1997
+ From abcd Mon Sep 1 12:33:02 1997
+ *** Failers
+ From abcd Sep 01 12:33:02 1997
+
+/^12.34/s
+ 12\n34
+ 12\r34
+
+/\w+(?=\t)/
+ the quick brown\t fox
+
+/foo(?!bar)(.*)/
+ foobar is foolish see?
+
+/(?:(?!foo)...|^.{0,2})bar(.*)/
+ foobar crowbar etc
+ barrel
+ 2barrel
+ A barrel
+
+/^(\D*)(?=\d)(?!123)/
+ abc456
+ *** Failers
+ abc123
+
+/^1234(?# test newlines
+ inside)/
+ 1234
+
+/^1234 #comment in extended re
+ /x
+ 1234
+
+/#rhubarb
+ abcd/x
+ abcd
+
+/^abcd#rhubarb/x
+ abcd
+
+/^(a)\1{2,3}(.)/
+ aaab
+ aaaab
+ aaaaab
+ aaaaaab
+
+/(?!^)abc/
+ the abc
+ *** Failers
+ abc
+
+/(?=^)abc/
+ abc
+ *** Failers
+ the abc
+
+/^[ab]{1,3}(ab*|b)/
+ aabbbbb
+
+/^[ab]{1,3}?(ab*|b)/
+ aabbbbb
+
+/^[ab]{1,3}?(ab*?|b)/
+ aabbbbb
+
+/^[ab]{1,3}(ab*?|b)/
+ aabbbbb
+
+/ (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* # optional leading comment
+(?: (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+" (?: # opening quote...
+[^\\\x80-\xff\n\015"] # Anything except backslash and quote
+| # or
+\\ [^\x80-\xff] # Escaped something (something != CR)
+)* " # closing quote
+) # initial word
+(?: (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* \. (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+" (?: # opening quote...
+[^\\\x80-\xff\n\015"] # Anything except backslash and quote
+| # or
+\\ [^\x80-\xff] # Escaped something (something != CR)
+)* " # closing quote
+) )* # further okay, if led by a period
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* @ (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+| \[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+) # initial subdomain
+(?: #
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* \. # if led by a period...
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+| \[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+) # ...further okay
+)*
+# address
+| # or
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+" (?: # opening quote...
+[^\\\x80-\xff\n\015"] # Anything except backslash and quote
+| # or
+\\ [^\x80-\xff] # Escaped something (something != CR)
+)* " # closing quote
+) # one word, optionally followed by....
+(?:
+[^()<>@,;:".\\\[\]\x80-\xff\000-\010\012-\037] | # atom and space parts, or...
+\(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) | # comments, or...
+
+" (?: # opening quote...
+[^\\\x80-\xff\n\015"] # Anything except backslash and quote
+| # or
+\\ [^\x80-\xff] # Escaped something (something != CR)
+)* " # closing quote
+# quoted strings
+)*
+< (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* # leading <
+(?: @ (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+| \[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+) # initial subdomain
+(?: #
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* \. # if led by a period...
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+| \[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+) # ...further okay
+)*
+
+(?: (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* , (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* @ (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+| \[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+) # initial subdomain
+(?: #
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* \. # if led by a period...
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+| \[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+) # ...further okay
+)*
+)* # further okay, if led by comma
+: # closing colon
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* )? # optional route
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+" (?: # opening quote...
+[^\\\x80-\xff\n\015"] # Anything except backslash and quote
+| # or
+\\ [^\x80-\xff] # Escaped something (something != CR)
+)* " # closing quote
+) # initial word
+(?: (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* \. (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+" (?: # opening quote...
+[^\\\x80-\xff\n\015"] # Anything except backslash and quote
+| # or
+\\ [^\x80-\xff] # Escaped something (something != CR)
+)* " # closing quote
+) )* # further okay, if led by a period
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* @ (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+| \[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+) # initial subdomain
+(?: #
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* \. # if led by a period...
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+| \[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+) # ...further okay
+)*
+# address spec
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* > # trailing >
+# name and address
+) (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* # optional trailing comment
+/x
+ Alan Other <user\@dom.ain>
+ <user\@dom.ain>
+ user\@dom.ain
+ \"A. Other\" <user.1234\@dom.ain> (a comment)
+ A. Other <user.1234\@dom.ain> (a comment)
+ \"/s=user/ou=host/o=place/prmd=uu.yy/admd= /c=gb/\"\@x400-re.lay
+ A missing angle <user\@some.where
+ *** Failers
+ The quick brown fox
+
+/[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional leading comment
+(?:
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+# Atom
+| # or
+" # "
+[^\\\x80-\xff\n\015"] * # normal
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015"] * )* # ( special normal* )*
+" # "
+# Quoted string
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+\.
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+# Atom
+| # or
+" # "
+[^\\\x80-\xff\n\015"] * # normal
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015"] * )* # ( special normal* )*
+" # "
+# Quoted string
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# additional words
+)*
+@
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+\[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+(?:
+\.
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+\[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+)*
+# address
+| # or
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+# Atom
+| # or
+" # "
+[^\\\x80-\xff\n\015"] * # normal
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015"] * )* # ( special normal* )*
+" # "
+# Quoted string
+)
+# leading word
+[^()<>@,;:".\\\[\]\x80-\xff\000-\010\012-\037] * # "normal" atoms and or spaces
+(?:
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+|
+" # "
+[^\\\x80-\xff\n\015"] * # normal
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015"] * )* # ( special normal* )*
+" # "
+) # "special" comment or quoted string
+[^()<>@,;:".\\\[\]\x80-\xff\000-\010\012-\037] * # more "normal"
+)*
+<
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# <
+(?:
+@
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+\[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+(?:
+\.
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+\[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+)*
+(?: ,
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+@
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+\[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+(?:
+\.
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+\[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+)*
+)* # additional domains
+:
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+)? # optional route
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+# Atom
+| # or
+" # "
+[^\\\x80-\xff\n\015"] * # normal
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015"] * )* # ( special normal* )*
+" # "
+# Quoted string
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+\.
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+# Atom
+| # or
+" # "
+[^\\\x80-\xff\n\015"] * # normal
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015"] * )* # ( special normal* )*
+" # "
+# Quoted string
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# additional words
+)*
+@
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+\[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+(?:
+\.
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+\[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+)*
+# address spec
+> # >
+# name and address
+)
+/x
+ Alan Other <user\@dom.ain>
+ <user\@dom.ain>
+ user\@dom.ain
+ \"A. Other\" <user.1234\@dom.ain> (a comment)
+ A. Other <user.1234\@dom.ain> (a comment)
+ \"/s=user/ou=host/o=place/prmd=uu.yy/admd= /c=gb/\"\@x400-re.lay
+ A missing angle <user\@some.where
+ *** Failers
+ The quick brown fox
+
+/abc\0def\00pqr\000xyz\0000AB/
+ abc\0def\00pqr\000xyz\0000AB
+ abc456 abc\0def\00pqr\000xyz\0000ABCDE
+
+/abc\x0def\x00pqr\x000xyz\x0000AB/
+ abc\x0def\x00pqr\x000xyz\x0000AB
+ abc456 abc\x0def\x00pqr\x000xyz\x0000ABCDE
+
+/^[\000-\037]/
+ \0A
+ \01B
+ \037C
+
+/\0*/
+ \0\0\0\0
+
+/A\x0{2,3}Z/
+ The A\x0\x0Z
+ An A\0\x0\0Z
+ *** Failers
+ A\0Z
+ A\0\x0\0\x0Z
+
+/^(cow|)\1(bell)/
+ cowcowbell
+ bell
+ *** Failers
+ cowbell
+
+/^\s/
+ \040abc
+ \x0cabc
+ \nabc
+ \rabc
+ \tabc
+ *** Failers
+ abc
+
+/^a b
+
+ \f c/x
+ abc
+
+/^(a|)\1*b/
+ ab
+ aaaab
+ b
+ *** Failers
+ acb
+
+/^(a|)\1+b/
+ aab
+ aaaab
+ b
+ *** Failers
+ ab
+
+/^(a|)\1?b/
+ ab
+ aab
+ b
+ *** Failers
+ acb
+
+/^(a|)\1{2}b/
+ aaab
+ b
+ *** Failers
+ ab
+ aab
+ aaaab
+
+/^(a|)\1{2,3}b/
+ aaab
+ aaaab
+ b
+ *** Failers
+ ab
+ aab
+ aaaaab
+
+/ab{1,3}bc/
+ abbbbc
+ abbbc
+ abbc
+ *** Failers
+ abc
+ abbbbbc
+
+/([^.]*)\.([^:]*):[T ]+(.*)/
+ track1.title:TBlah blah blah
+
+/([^.]*)\.([^:]*):[T ]+(.*)/i
+ track1.title:TBlah blah blah
+
+/([^.]*)\.([^:]*):[t ]+(.*)/i
+ track1.title:TBlah blah blah
+
+/^[W-c]+$/
+ WXY_^abc
+ ***Failers
+ wxy
+
+/^[W-c]+$/i
+ WXY_^abc
+ wxy_^ABC
+
+/^[\x3f-\x5F]+$/i
+ WXY_^abc
+ wxy_^ABC
+
+/^abc$/m
+ abc
+ qqq\nabc
+ abc\nzzz
+ qqq\nabc\nzzz
+
+/^abc$/
+ abc
+ *** Failers
+ qqq\nabc
+ abc\nzzz
+ qqq\nabc\nzzz
+
+/\Aabc\Z/m
+ abc
+ abc\n
+ *** Failers
+ qqq\nabc
+ abc\nzzz
+ qqq\nabc\nzzz
+
+/\A(.)*\Z/s
+ abc\ndef
+
+/\A(.)*\Z/m
+ *** Failers
+ abc\ndef
+
+/(?:b)|(?::+)/
+ b::c
+ c::b
+
+/[-az]+/
+ az-
+ *** Failers
+ b
+
+/[az-]+/
+ za-
+ *** Failers
+ b
+
+/[a\-z]+/
+ a-z
+ *** Failers
+ b
+
+/[a-z]+/
+ abcdxyz
+
+/[\d-]+/
+ 12-34
+ *** Failers
+ aaa
+
+/[\d-z]+/
+ 12-34z
+ *** Failers
+ aaa
+
+/\x5c/
+ \\
+
+/\x20Z/
+ the Zoo
+ *** Failers
+ Zulu
+
+/(abc)\1/i
+ abcabc
+ ABCabc
+ abcABC
+
+/(main(O)?)+/
+ mainmain
+ mainOmain
+
+/ab{3cd/
+ ab{3cd
+
+/ab{3,cd/
+ ab{3,cd
+
+/ab{3,4a}cd/
+ ab{3,4a}cd
+
+/{4,5a}bc/
+ {4,5a}bc
+
+/^a.b/
+ a\rb
+ *** Failers
+ a\nb
+
+/abc$/
+ abc
+ abc\n
+ *** Failers
+ abc\ndef
+
+/(abc)\123/
+ abc\x53
+
+/(abc)\223/
+ abc\x93
+
+/(abc)\323/
+ abc\xd3
+
+/(abc)\500/
+ abc\x40
+ abc\100
+
+/(abc)\5000/
+ abc\x400
+ abc\x40\x30
+ abc\1000
+ abc\100\x30
+ abc\100\060
+ abc\100\60
+
+/abc\81/
+ abc\081
+ abc\0\x38\x31
+
+/abc\91/
+ abc\091
+ abc\0\x39\x31
+
+/(a)(b)(c)(d)(e)(f)(g)(h)(i)(j)(k)(l)\12\123/
+ abcdefghijkllS
+
+/(a)(b)(c)(d)(e)(f)(g)(h)(i)(j)(k)\12\123/
+ abcdefghijk\12S
+
+/ab\gdef/
+ abgdef
+
+/a{0}bc/
+ bc
+
+/(a|(bc)){0,0}?xyz/
+ xyz
+
+/abc[\10]de/
+ abc\010de
+
+/abc[\1]de/
+ abc\1de
+
+/(abc)[\1]de/
+ abc\1de
+
+/a.b(?s)/
+ a\nb
+
+/^([^a])([^\b])([^c]*)([^d]{3,4})/
+ baNOTccccd
+ baNOTcccd
+ baNOTccd
+ bacccd
+ *** Failers
+ anything
+ b\bc
+ baccd
+
+/[^a]/
+ Abc
+
+/[^a]/i
+ Abc
+
+/[^a]+/
+ AAAaAbc
+
+/[^a]+/i
+ AAAaAbc
+
+/[^a]+/
+ bbb\nccc
+
+/[^k]$/
+ abc
+ *** Failers
+ abk
+
+/[^k]{2,3}$/
+ abc
+ kbc
+ kabc
+ *** Failers
+ abk
+ akb
+ akk
+
+/^\d{8,}\@.+[^k]$/
+ 12345678\@a.b.c.d
+ 123456789\@x.y.z
+ *** Failers
+ 12345678\@x.y.uk
+ 1234567\@a.b.c.d
+
+/(a)\1{8,}/
+ aaaaaaaaa
+ aaaaaaaaaa
+ *** Failers
+ aaaaaaa
+
+/[^a]/
+ aaaabcd
+ aaAabcd
+
+/[^a]/i
+ aaaabcd
+ aaAabcd
+
+/[^az]/
+ aaaabcd
+ aaAabcd
+
+/[^az]/i
+ aaaabcd
+ aaAabcd
+
+/\000\001\002\003\004\005\006\007\010\011\012\013\014\015\016\017\020\021\022\023\024\025\026\027\030\031\032\033\034\035\036\037\040\041\042\043\044\045\046\047\050\051\052\053\054\055\056\057\060\061\062\063\064\065\066\067\070\071\072\073\074\075\076\077\100\101\102\103\104\105\106\107\110\111\112\113\114\115\116\117\120\121\122\123\124\125\126\127\130\131\132\133\134\135\136\137\140\141\142\143\144\145\146\147\150\151\152\153\154\155\156\157\160\161\162\163\164\165\166\167\170\171\172\173\174\175\176\177\200\201\202\203\204\205\206\207\210\211\212\213\214\215\216\217\220\221\222\223\224\225\226\227\230\231\232\233\234\235\236\237\240\241\242\243\244\245\246\247\250\251\252\253\254\255\256\257\260\261\262\263\264\265\266\267\270\271\272\273\274\275\276\277\300\301\302\303\304\305\306\307\310\311\312\313\314\315\316\317\320\321\322\323\324\325\326\327\330\331\332\333\334\335\336\337\340\341\342\343\344\345\346\347\350\351\352\353\354\355\356\357\360\361\362\363\364\365\366\367\370\371\372\373\374\375\376\377/
+ \000\001\002\003\004\005\006\007\010\011\012\013\014\015\016\017\020\021\022\023\024\025\026\027\030\031\032\033\034\035\036\037\040\041\042\043\044\045\046\047\050\051\052\053\054\055\056\057\060\061\062\063\064\065\066\067\070\071\072\073\074\075\076\077\100\101\102\103\104\105\106\107\110\111\112\113\114\115\116\117\120\121\122\123\124\125\126\127\130\131\132\133\134\135\136\137\140\141\142\143\144\145\146\147\150\151\152\153\154\155\156\157\160\161\162\163\164\165\166\167\170\171\172\173\174\175\176\177\200\201\202\203\204\205\206\207\210\211\212\213\214\215\216\217\220\221\222\223\224\225\226\227\230\231\232\233\234\235\236\237\240\241\242\243\244\245\246\247\250\251\252\253\254\255\256\257\260\261\262\263\264\265\266\267\270\271\272\273\274\275\276\277\300\301\302\303\304\305\306\307\310\311\312\313\314\315\316\317\320\321\322\323\324\325\326\327\330\331\332\333\334\335\336\337\340\341\342\343\344\345\346\347\350\351\352\353\354\355\356\357\360\361\362\363\364\365\366\367\370\371\372\373\374\375\376\377
+
+/P[^*]TAIRE[^*]{1,6}?LL/
+ xxxxxxxxxxxPSTAIREISLLxxxxxxxxx
+
+/P[^*]TAIRE[^*]{1,}?LL/
+ xxxxxxxxxxxPSTAIREISLLxxxxxxxxx
+
+/(\.\d\d[1-9]?)\d+/
+ 1.230003938
+ 1.875000282
+ 1.235
+
+/(\.\d\d((?=0)|\d(?=\d)))/
+ 1.230003938
+ 1.875000282
+ *** Failers
+ 1.235
+
+/a(?)b/
+ ab
+
+/\b(foo)\s+(\w+)/i
+ Food is on the foo table
+
+/foo(.*)bar/
+ The food is under the bar in the barn.
+
+/foo(.*?)bar/
+ The food is under the bar in the barn.
+
+/(.*)(\d*)/
+ I have 2 numbers: 53147
+
+/(.*)(\d+)/
+ I have 2 numbers: 53147
+
+/(.*?)(\d*)/
+ I have 2 numbers: 53147
+
+/(.*?)(\d+)/
+ I have 2 numbers: 53147
+
+/(.*)(\d+)$/
+ I have 2 numbers: 53147
+
+/(.*?)(\d+)$/
+ I have 2 numbers: 53147
+
+/(.*)\b(\d+)$/
+ I have 2 numbers: 53147
+
+/(.*\D)(\d+)$/
+ I have 2 numbers: 53147
+
+/^\D*(?!123)/
+ ABC123
+
+/^(\D*)(?=\d)(?!123)/
+ ABC445
+ *** Failers
+ ABC123
+
+/^[W-]46]/
+ W46]789
+ -46]789
+ *** Failers
+ Wall
+ Zebra
+ 42
+ [abcd]
+ ]abcd[
+
+/^[W-\]46]/
+ W46]789
+ Wall
+ Zebra
+ Xylophone
+ 42
+ [abcd]
+ ]abcd[
+ \\backslash
+ *** Failers
+ -46]789
+ well
+
+/\d\d\/\d\d\/\d\d\d\d/
+ 01/01/2000
+
+/word (?:[a-zA-Z0-9]+ ){0,10}otherword/
+ word cat dog elephant mussel cow horse canary baboon snake shark otherword
+ word cat dog elephant mussel cow horse canary baboon snake shark
+
+/word (?:[a-zA-Z0-9]+ ){0,300}otherword/
+ word cat dog elephant mussel cow horse canary baboon snake shark the quick brown fox and the lazy dog and several other words getting close to thirty by now I hope
+
+/^(a){0,0}/
+ bcd
+ abc
+ aab
+
+/^(a){0,1}/
+ bcd
+ abc
+ aab
+
+/^(a){0,2}/
+ bcd
+ abc
+ aab
+
+/^(a){0,3}/
+ bcd
+ abc
+ aab
+ aaa
+
+/^(a){0,}/
+ bcd
+ abc
+ aab
+ aaa
+ aaaaaaaa
+
+/^(a){1,1}/
+ bcd
+ abc
+ aab
+
+/^(a){1,2}/
+ bcd
+ abc
+ aab
+
+/^(a){1,3}/
+ bcd
+ abc
+ aab
+ aaa
+
+/^(a){1,}/
+ bcd
+ abc
+ aab
+ aaa
+ aaaaaaaa
+
+/.*\.gif/
+ borfle\nbib.gif\nno
+
+/.{0,}\.gif/
+ borfle\nbib.gif\nno
+
+/.*\.gif/m
+ borfle\nbib.gif\nno
+
+/.*\.gif/s
+ borfle\nbib.gif\nno
+
+/.*\.gif/ms
+ borfle\nbib.gif\nno
+
+/.*$/
+ borfle\nbib.gif\nno
+
+/.*$/m
+ borfle\nbib.gif\nno
+
+/.*$/s
+ borfle\nbib.gif\nno
+
+/.*$/ms
+ borfle\nbib.gif\nno
+
+/.*$/
+ borfle\nbib.gif\nno\n
+
+/.*$/m
+ borfle\nbib.gif\nno\n
+
+/.*$/s
+ borfle\nbib.gif\nno\n
+
+/.*$/ms
+ borfle\nbib.gif\nno\n
+
+/(.*X|^B)/
+ abcde\n1234Xyz
+ BarFoo
+ *** Failers
+ abcde\nBar
+
+/(.*X|^B)/m
+ abcde\n1234Xyz
+ BarFoo
+ abcde\nBar
+
+/(.*X|^B)/s
+ abcde\n1234Xyz
+ BarFoo
+ *** Failers
+ abcde\nBar
+
+/(.*X|^B)/ms
+ abcde\n1234Xyz
+ BarFoo
+ abcde\nBar
+
+/(?s)(.*X|^B)/
+ abcde\n1234Xyz
+ BarFoo
+ *** Failers
+ abcde\nBar
+
+/(?s:.*X|^B)/
+ abcde\n1234Xyz
+ BarFoo
+ *** Failers
+ abcde\nBar
+
+/^.*B/
+ **** Failers
+ abc\nB
+
+/(?s)^.*B/
+ abc\nB
+
+/(?m)^.*B/
+ abc\nB
+
+/(?ms)^.*B/
+ abc\nB
+
+/(?ms)^B/
+ abc\nB
+
+/(?s)B$/
+ B\n
+
+/^[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]/
+ 123456654321
+
+/^\d\d\d\d\d\d\d\d\d\d\d\d/
+ 123456654321
+
+/^[\d][\d][\d][\d][\d][\d][\d][\d][\d][\d][\d][\d]/
+ 123456654321
+
+/^[abc]{12}/
+ abcabcabcabc
+
+/^[a-c]{12}/
+ abcabcabcabc
+
+/^(a|b|c){12}/
+ abcabcabcabc
+
+/^[abcdefghijklmnopqrstuvwxy0123456789]/
+ n
+ *** Failers
+ z
+
+/abcde{0,0}/
+ abcd
+ *** Failers
+ abce
+
+/ab[cd]{0,0}e/
+ abe
+ *** Failers
+ abcde
+
+/ab(c){0,0}d/
+ abd
+ *** Failers
+ abcd
+
+/a(b*)/
+ a
+ ab
+ abbbb
+ *** Failers
+ bbbbb
+
+/ab\d{0}e/
+ abe
+ *** Failers
+ ab1e
+
+/"([^\\"]+|\\.)*"/
+ the \"quick\" brown fox
+ \"the \\\"quick\\\" brown fox\"
+
+/.*?/g+
+ abc
+
+/\b/g+
+ abc
+
+/\b/+g
+ abc
+
+//g
+ abc
+
+/ End of test input /
--- /dev/null
+/(a)b|/
+
+/abc/
+ abc
+ defabc
+ \Aabc
+ *** Failers
+ \Adefabc
+ ABC
+
+/^abc/
+ abc
+ \Aabc
+ *** Failers
+ defabc
+ \Adefabc
+
+/a+bc/
+
+/a*bc/
+
+/a{3}bc/
+
+/(abc|a+z)/
+
+/^abc$/
+ abc
+ *** Failers
+ def\nabc
+
+/ab\gdef/X
+
+/(?X)ab\gdef/X
+
+/x{5,4}/
+
+/z{65536}/
+
+/[abcd/
+
+/[\B]/
+
+/[a-\w]/
+
+/[z-a]/
+
+/^*/
+
+/(abc/
+
+/(?# abc/
+
+/(?z)abc/
+
+/.*b/
+
+/.*?b/
+
+/cat|dog|elephant/
+ this sentence eventually mentions a cat
+ this sentences rambles on and on for a while and then reaches elephant
+
+/cat|dog|elephant/S
+ this sentence eventually mentions a cat
+ this sentences rambles on and on for a while and then reaches elephant
+
+/cat|dog|elephant/iS
+ this sentence eventually mentions a CAT cat
+ this sentences rambles on and on for a while to elephant ElePhant
+
+/a|[bcd]/S
+
+/(a|[^\dZ])/S
+
+/(a|b)*[\s]/S
+
+/(ab\2)/
+
+/{4,5}abc/
+
+/(a)(b)(c)\2/
+ abcb
+ \O0abcb
+ \O3abcb
+ \O6abcb
+ \O9abcb
+ \O12abcb
+
+/(a)bc|(a)(b)\2/
+ abc
+ \O0abc
+ \O3abc
+ \O6abc
+ aba
+ \O0aba
+ \O3aba
+ \O6aba
+ \O9aba
+ \O12aba
+
+/abc$/E
+ abc
+ *** Failers
+ abc\n
+ abc\ndef
+
+/(a)(b)(c)(d)(e)\6/
+
+/the quick brown fox/
+ the quick brown fox
+ this is a line with the quick brown fox
+
+/the quick brown fox/A
+ the quick brown fox
+ *** Failers
+ this is a line with the quick brown fox
+
+/ab(?z)cd/
+
+/^abc|def/
+ abcdef
+ abcdef\B
+
+/.*((abc)$|(def))/
+ defabc
+ \Zdefabc
+
+/abc/P
+ abc
+ *** Failers
+
+/^abc|def/P
+ abcdef
+ abcdef\B
+
+/.*((abc)$|(def))/P
+ defabc
+ \Zdefabc
+
+/the quick brown fox/P
+ the quick brown fox
+ *** Failers
+ The Quick Brown Fox
+
+/the quick brown fox/Pi
+ the quick brown fox
+ The Quick Brown Fox
+
+/abc.def/P
+ *** Failers
+ abc\ndef
+
+/abc$/P
+ abc
+ abc\n
+
+/(abc)\2/P
+
+/(abc\1)/P
+ abc
+
+/)/
+
+/a[]b/
+
+/[^aeiou ]{3,}/
+ co-processors, and for
+
+/<.*>/
+ abc<def>ghi<klm>nop
+
+/<.*?>/
+ abc<def>ghi<klm>nop
+
+/<.*>/U
+ abc<def>ghi<klm>nop
+
+/<.*>(?U)/
+ abc<def>ghi<klm>nop
+
+/<.*?>/U
+ abc<def>ghi<klm>nop
+
+/={3,}/U
+ abc========def
+
+/(?U)={3,}?/
+ abc========def
+
+/(?<!bar|cattle)foo/
+ foo
+ catfoo
+ *** Failers
+ the barfoo
+ and cattlefoo
+
+/(?<=a+)b/
+
+/(?<=aaa|b{0,3})b/
+
+/(?<!(foo)a\1)bar/
+
+/(?i)abc/
+
+/(a|(?m)a)/
+
+/(?i)^1234/
+
+/(^b|(?i)^d)/
+
+/(?s).*/
+
+/[abcd]/S
+
+/(?i)[abcd]/S
+
+/(?m)[xy]|(b|c)/S
+
+/(^a|^b)/m
+
+/(?i)(^a|^b)/m
+
+/(a)(?(1)a|b|c)/
+
+/(?(?=a)a|b|c)/
+
+/(?(1a)/
+
+/(?(?i))/
+
+/(?(abc))/
+
+/(?(?<ab))/
+
+/((?s)blah)\s+\1/
+
+/((?i)blah)\s+\1/
+
+/((?i)b)/DS
+
+/(a*b|(?i:c*(?-i)d))/S
+
+/a$/
+ a
+ a\n
+ *** Failers
+ \Za
+ \Za\n
+
+/a$/m
+ a
+ a\n
+ \Za\n
+ *** Failers
+ \Za
+
+/\Aabc/m
+
+/^abc/m
+
+/^((a+)(?U)([ab]+)(?-U)([bc]+)(\w*))/
+ aaaaabbbbbcccccdef
+
+/(?<=foo)[ab]/S
+
+/(?<!foo)(alpha|omega)/S
+
+/(?!alphabet)[ab]/S
+
+/(?<=foo\n)^bar/m
+
+/(?>^abc)/m
+ abc
+ def\nabc
+ *** Failers
+ defabc
+
+/(?<=ab(c+)d)ef/
+
+/(?<=ab(?<=c+)d)ef/
+
+/(?<=ab(c|de)f)g/
+
+/The next three are in testinput2 because they have variable length branches/
+
+/(?<=bullock|donkey)-cart/
+ the bullock-cart
+ a donkey-cart race
+ *** Failers
+ cart
+ horse-and-cart
+
+/(?<=ab(?i)x|y|z)/
+
+/(?>.*)(?<=(abcd)|(xyz))/
+ alphabetabcd
+ endingxyz
+
+/(?<=ab(?i)x(?-i)y|(?i)z|b)ZZ/
+ abxyZZ
+ abXyZZ
+ ZZZ
+ zZZ
+ bZZ
+ BZZ
+ *** Failers
+ ZZ
+ abXYZZ
+ zzz
+ bzz
+
+/(?<!(foo)a)bar/
+ bar
+ foobbar
+ *** Failers
+ fooabar
+
+/This one is here because Perl 5.005_02 doesn't fail it/
+
+/^(a)?(?(1)a|b)+$/
+ *** Failers
+ a
+
+/This one is here because I think Perl 5.005_02 gets the setting of $1 wrong/
+
+/^(a\1?){4}$/
+ aaaaaa
+
+/These are syntax tests from Perl 5.005/
+
+/a[b-a]/
+
+/a[]b/
+
+/a[/
+
+/*a/
+
+/(*)b/
+
+/abc)/
+
+/(abc/
+
+/a**/
+
+/)(/
+
+/\1/
+
+/\2/
+
+/(a)|\2/
+
+/a[b-a]/i
+
+/a[]b/i
+
+/a[/i
+
+/*a/i
+
+/(*)b/i
+
+/abc)/i
+
+/(abc/i
+
+/a**/i
+
+/)(/i
+
+/:(?:/
+
+/(?<%)b/
+
+/a(?{)b/
+
+/a(?{{})b/
+
+/a(?{}})b/
+
+/a(?{"{"})b/
+
+/a(?{"{"}})b/
+
+/(?(1?)a|b)/
+
+/(?(1)a|b|c)/
+
+/[a[:xyz:/
+
+/(?<=x+)y/
+
+/a{37,17}/
+
+/abc/\
+
+/abc/\P
+
+/abc/\i
+
+/(a)bc(d)/
+ abcd
+ abcd\C2
+ abcd\C5
+
+/(.{20})/
+ abcdefghijklmnopqrstuvwxyz
+ abcdefghijklmnopqrstuvwxyz\C1
+ abcdefghijklmnopqrstuvwxyz\G1
+
+/(.{15})/
+ abcdefghijklmnopqrstuvwxyz
+ abcdefghijklmnopqrstuvwxyz\C1\G1
+
+/(.{16})/
+ abcdefghijklmnopqrstuvwxyz
+ abcdefghijklmnopqrstuvwxyz\C1\G1\L
+
+/^(a|(bc))de(f)/
+ adef\G1\G2\G3\G4\L
+ bcdef\G1\G2\G3\G4\L
+ adefghijk\C0
+
+/^abc\00def/
+ abc\00def\L\C0
+
+/word ((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+
+)((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+
+)?)?)?)?)?)?)?)?)?otherword/M
+
+/.*X/D
+
+/.*X/Ds
+
+/(.*X|^B)/D
+
+/(.*X|^B)/Ds
+
+/(?s)(.*X|^B)/D
+
+/(?s:.*X|^B)/D
+
+/\Biss\B/+
+ Mississippi
+
+/\Biss\B/+P
+ Mississippi
+
+/iss/G+
+ Mississippi
+
+/\Biss\B/G+
+ Mississippi
+
+/\Biss\B/g+
+ Mississippi
+ *** Failers
+ Mississippi\A
+
+/(?<=[Ms])iss/g+
+ Mississippi
+
+/(?<=[Ms])iss/G+
+ Mississippi
+
+/^iss/g+
+ ississippi
+
+/.*iss/g+
+ abciss\nxyzisspqr
+
+/.i./+g
+ Mississippi
+ Mississippi\A
+ Missouri river
+ Missouri river\A
+
+/^.is/+g
+ Mississippi
+
+/^ab\n/g+
+ ab\nab\ncd
+
+/^ab\n/mg+
+ ab\nab\ncd
+
+/abc/
+
+/abc|bac/
+
+/(abc|bac)/
+
+/(abc|(c|dc))/
+
+/(abc|(d|de)c)/
+
+/a*/
+
+/a+/
+
+/(baa|a+)/
+
+/a{0,3}/
+
+/baa{3,}/
+
+/"([^\\"]+|\\.)*"/
+
+/(abc|ab[cd])/
+
+/(a|.)/
+
+/a|ba|\w/
+
+/abc(?=pqr)/
+
+/...(?<=abc)/
+
+/abc(?!pqr)/
+
+/ab./
+
+/ab[xyz]/
+
+/abc*/
+
+/ab.c*/
+
+/a.c*/
+
+/.c*/
+
+/ac*/
+
+/(a.c*|b.c*)/
+
+/a.c*|aba/
+
+/.+a/
+
+/(?=abcda)a.*/
+
+/(?=a)a.*/
+
+/a(b)*/
+
+/a\d*/
+
+/ab\d*/
+
+/a(\d)*/
+
+/abcde{0,0}/
+
+/ab\d+/
+
+/a(?(1)b)/
+
+/a(?(1)bag|big)/
+
+/a(?(1)bag|big)*/
+
+/a(?(1)bag|big)+/
+
+/a(?(1)b..|b..)/
+
+/ab\d{0}e/
+
+/a?b?/
+ a
+ b
+ ab
+ \
+ *** Failers
+ \N
+
+/|-/
+ abcd
+ -abc
+ \Nab-c
+ *** Failers
+ \Nabc
+
+/a*(b+)(z)(z)/P
+ aaaabbbbzzzz
+ aaaabbbbzzzz\O0
+ aaaabbbbzzzz\O1
+ aaaabbbbzzzz\O2
+ aaaabbbbzzzz\O3
+ aaaabbbbzzzz\O4
+ aaaabbbbzzzz\O5
+
+/^.?abcd/S
+
+/\( # ( at start
+ (?: # Non-capturing bracket
+ (?>[^()]+) # Either a sequence of non-brackets (no backtracking)
+ | # Or
+ (?R) # Recurse - i.e. nested bracketed string
+ )* # Zero or more contents
+ \) # Closing )
+ /x
+ (abcd)
+ (abcd)xyz
+ xyz(abcd)
+ (ab(xy)cd)pqr
+ (ab(xycd)pqr
+ () abc ()
+ 12(abcde(fsh)xyz(foo(bar))lmno)89
+ *** Failers
+ abcd
+ abcd)
+ (abcd
+
+/\( ( (?>[^()]+) | (?R) )* \) /xg
+ (ab(xy)cd)pqr
+ 1(abcd)(x(y)z)pqr
+
+/\( (?: (?>[^()]+) | (?R) ) \) /x
+ (abcd)
+ (ab(xy)cd)
+ (a(b(c)d)e)
+ ((ab))
+ *** Failers
+ ()
+
+/\( (?: (?>[^()]+) | (?R) )? \) /x
+ ()
+ 12(abcde(fsh)xyz(foo(bar))lmno)89
+
+/\( ( (?>[^()]+) | (?R) )* \) /x
+ (ab(xy)cd)
+
+/\( ( ( (?>[^()]+) | (?R) )* ) \) /x
+ (ab(xy)cd)
+
+/\( (123)? ( ( (?>[^()]+) | (?R) )* ) \) /x
+ (ab(xy)cd)
+ (123ab(xy)cd)
+
+/\( ( (123)? ( (?>[^()]+) | (?R) )* ) \) /x
+ (ab(xy)cd)
+ (123ab(xy)cd)
+
+/\( (((((((((( ( (?>[^()]+) | (?R) )* )))))))))) \) /x
+ (ab(xy)cd)
+
+/\( ( ( (?>[^()<>]+) | ((?>[^()]+)) | (?R) )* ) \) /x
+ (abcd(xyz<p>qrs)123)
+
+/\( ( ( (?>[^()]+) | ((?R)) )* ) \) /x
+ (ab(cd)ef)
+ (ab(cd(ef)gh)ij)
+
+/^[[:alnum:]]/D
+
+/^[[:alpha:]]/D
+
+/^[[:ascii:]]/D
+
+/^[[:cntrl:]]/D
+
+/^[[:digit:]]/D
+
+/^[[:graph:]]/D
+
+/^[[:lower:]]/D
+
+/^[[:print:]]/D
+
+/^[[:punct:]]/D
+
+/^[[:space:]]/D
+
+/^[[:upper:]]/D
+
+/^[[:xdigit:]]/D
+
+/^[[:word:]]/D
+
+/^[[:^cntrl:]]/D
+
+/^[12[:^digit:]]/D
+
+/[01[:alpha:]%]/D
+
+/[[.ch.]]/
+
+/[[=ch=]]/
+
+/[[:rhubarb:]]/
+
+/[[:upper:]]/i
+ A
+ a
+
+/[[:lower:]]/i
+ A
+ a
+
+/((?-i)[[:lower:]])[[:lower:]]/i
+ ab
+ aB
+ *** Failers
+ Ab
+ AB
+
+/ End of test input /
--- /dev/null
+/(?<!bar)foo/
+ foo
+ catfood
+ arfootle
+ rfoosh
+ *** Failers
+ barfoo
+ towbarfoo
+
+/\w{3}(?<!bar)foo/
+ catfood
+ *** Failers
+ foo
+ barfoo
+ towbarfoo
+
+/(?<=(foo)a)bar/
+ fooabar
+ *** Failers
+ bar
+ foobbar
+
+/\Aabc\z/m
+ abc
+ *** Failers
+ abc\n
+ qqq\nabc
+ abc\nzzz
+ qqq\nabc\nzzz
+
+"(?>.*/)foo"
+ /this/is/a/very/long/line/in/deed/with/very/many/slashes/in/it/you/see/
+
+"(?>.*/)foo"
+ /this/is/a/very/long/line/in/deed/with/very/many/slashes/in/and/foo
+
+/(?>(\.\d\d[1-9]?))\d+/
+ 1.230003938
+ 1.875000282
+ *** Failers
+ 1.235
+
+/^((?>\w+)|(?>\s+))*$/
+ now is the time for all good men to come to the aid of the party
+ *** Failers
+ this is not a line with only words and spaces!
+
+/(\d+)(\w)/
+ 12345a
+ 12345+
+
+/((?>\d+))(\w)/
+ 12345a
+ *** Failers
+ 12345+
+
+/(?>a+)b/
+ aaab
+
+/((?>a+)b)/
+ aaab
+
+/(?>(a+))b/
+ aaab
+
+/(?>b)+/
+ aaabbbccc
+
+/(?>a+|b+|c+)*c/
+ aaabbbbccccd
+
+/((?>[^()]+)|\([^()]*\))+/
+ ((abc(ade)ufh()()x
+
+/\(((?>[^()]+)|\([^()]+\))+\)/
+ (abc)
+ (abc(def)xyz)
+ *** Failers
+ ((()aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+
+/a(?-i)b/i
+ ab
+ *** Failers
+ Ab
+ aB
+ AB
+
+/(a (?x)b c)d e/
+ a bcd e
+ *** Failers
+ a b cd e
+ abcd e
+ a bcde
+
+/(a b(?x)c d (?-x)e f)/
+ a bcde f
+ *** Failers
+ abcdef
+
+/(a(?i)b)c/
+ abc
+ aBc
+ *** Failers
+ abC
+ aBC
+ Abc
+ ABc
+ ABC
+ AbC
+
+/a(?i:b)c/
+ abc
+ aBc
+ *** Failers
+ ABC
+ abC
+ aBC
+
+/a(?i:b)*c/
+ aBc
+ aBBc
+ *** Failers
+ aBC
+ aBBC
+
+/a(?=b(?i)c)\w\wd/
+ abcd
+ abCd
+ *** Failers
+ aBCd
+ abcD
+
+/(?s-i:more.*than).*million/i
+ more than million
+ more than MILLION
+ more \n than Million
+ *** Failers
+ MORE THAN MILLION
+ more \n than \n million
+
+/(?:(?s-i)more.*than).*million/i
+ more than million
+ more than MILLION
+ more \n than Million
+ *** Failers
+ MORE THAN MILLION
+ more \n than \n million
+
+/(?>a(?i)b+)+c/
+ abc
+ aBbc
+ aBBc
+ *** Failers
+ Abc
+ abAb
+ abbC
+
+/(?=a(?i)b)\w\wc/
+ abc
+ aBc
+ *** Failers
+ Ab
+ abC
+ aBC
+
+/(?<=a(?i)b)(\w\w)c/
+ abxxc
+ aBxxc
+ *** Failers
+ Abxxc
+ ABxxc
+ abxxC
+
+/(?:(a)|b)(?(1)A|B)/
+ aA
+ bB
+ *** Failers
+ aB
+ bA
+
+/^(a)?(?(1)a|b)+$/
+ aa
+ b
+ bb
+ *** Failers
+ ab
+
+/^(?(?=abc)\w{3}:|\d\d)$/
+ abc:
+ 12
+ *** Failers
+ 123
+ xyz
+
+/^(?(?!abc)\d\d|\w{3}:)$/
+ abc:
+ 12
+ *** Failers
+ 123
+ xyz
+
+/(?(?<=foo)bar|cat)/
+ foobar
+ cat
+ fcat
+ focat
+ *** Failers
+ foocat
+
+/(?(?<!foo)cat|bar)/
+ foobar
+ cat
+ fcat
+ focat
+ *** Failers
+ foocat
+
+/( \( )? [^()]+ (?(1) \) |) /x
+ abcd
+ (abcd)
+ the quick (abcd) fox
+ (abcd
+
+/( \( )? [^()]+ (?(1) \) ) /x
+ abcd
+ (abcd)
+ the quick (abcd) fox
+ (abcd
+
+/^(?(2)a|(1)(2))+$/
+ 12
+ 12a
+ 12aa
+ *** Failers
+ 1234
+
+/((?i)blah)\s+\1/
+ blah blah
+ BLAH BLAH
+ Blah Blah
+ blaH blaH
+ *** Failers
+ blah BLAH
+ Blah blah
+ blaH blah
+
+/((?i)blah)\s+(?i:\1)/
+ blah blah
+ BLAH BLAH
+ Blah Blah
+ blaH blaH
+ blah BLAH
+ Blah blah
+ blaH blah
+
+/(?>a*)*/
+ a
+ aa
+ aaaa
+
+/(abc|)+/
+ abc
+ abcabc
+ abcabcabc
+ xyz
+
+/([a]*)*/
+ a
+ aaaaa
+
+/([ab]*)*/
+ a
+ b
+ ababab
+ aaaabcde
+ bbbb
+
+/([^a]*)*/
+ b
+ bbbb
+ aaa
+
+/([^ab]*)*/
+ cccc
+ abab
+
+/([a]*?)*/
+ a
+ aaaa
+
+/([ab]*?)*/
+ a
+ b
+ abab
+ baba
+
+/([^a]*?)*/
+ b
+ bbbb
+ aaa
+
+/([^ab]*?)*/
+ c
+ cccc
+ baba
+
+/(?>a*)*/
+ a
+ aaabcde
+
+/((?>a*))*/
+ aaaaa
+ aabbaa
+
+/((?>a*?))*/
+ aaaaa
+ aabbaa
+
+/(?(?=[^a-z]+[a-z]) \d{2}-[a-z]{3}-\d{2} | \d{2}-\d{2}-\d{2} ) /x
+ 12-sep-98
+ 12-09-98
+ *** Failers
+ sep-12-98
+
+/(?<=(foo))bar\1/
+ foobarfoo
+ foobarfootling
+ *** Failers
+ foobar
+ barfoo
+
+/(?i:saturday|sunday)/
+ saturday
+ sunday
+ Saturday
+ Sunday
+ SATURDAY
+ SUNDAY
+ SunDay
+
+/(a(?i)bc|BB)x/
+ abcx
+ aBCx
+ bbx
+ BBx
+ *** Failers
+ abcX
+ aBCX
+ bbX
+ BBX
+
+/^([ab](?i)[cd]|[ef])/
+ ac
+ aC
+ bD
+ elephant
+ Europe
+ frog
+ France
+ *** Failers
+ Africa
+
+/^(ab|a(?i)[b-c](?m-i)d|x(?i)y|z)/
+ ab
+ aBd
+ xy
+ xY
+ zebra
+ Zambesi
+ *** Failers
+ aCD
+ XY
+
+/(?<=foo\n)^bar/m
+ foo\nbar
+ *** Failers
+ bar
+ baz\nbar
+
+/(?<=(?<!foo)bar)baz/
+ barbaz
+ barbarbaz
+ koobarbaz
+ *** Failers
+ baz
+ foobarbaz
+
+/The case of aaaaaa is missed out below because I think Perl 5.005_02 gets/
+/it wrong; it sets $1 to aaa rather than aa. Compare the following test,/
+/where it does set $1 to aa when matching aaaaaa./
+
+/^(a\1?){4}$/
+ a
+ aa
+ aaa
+ aaaa
+ aaaaa
+ aaaaaaa
+ aaaaaaaa
+ aaaaaaaaa
+ aaaaaaaaaa
+ aaaaaaaaaaa
+ aaaaaaaaaaaa
+ aaaaaaaaaaaaa
+ aaaaaaaaaaaaaa
+ aaaaaaaaaaaaaaa
+ aaaaaaaaaaaaaaaa
+
+/^(a\1?)(a\1?)(a\2?)(a\3?)$/
+ a
+ aa
+ aaa
+ aaaa
+ aaaaa
+ aaaaaa
+ aaaaaaa
+ aaaaaaaa
+ aaaaaaaaa
+ aaaaaaaaaa
+ aaaaaaaaaaa
+ aaaaaaaaaaaa
+ aaaaaaaaaaaaa
+ aaaaaaaaaaaaaa
+ aaaaaaaaaaaaaaa
+ aaaaaaaaaaaaaaaa
+
+/The following tests are taken from the Perl 5.005 test suite; some of them/
+/are compatible with 5.004, but I'd rather not have to sort them out./
+
+/abc/
+ abc
+ xabcy
+ ababc
+ *** Failers
+ xbc
+ axc
+ abx
+
+/ab*c/
+ abc
+
+/ab*bc/
+ abc
+ abbc
+ abbbbc
+
+/.{1}/
+ abbbbc
+
+/.{3,4}/
+ abbbbc
+
+/ab{0,}bc/
+ abbbbc
+
+/ab+bc/
+ abbc
+ *** Failers
+ abc
+ abq
+
+/ab{1,}bc/
+
+/ab+bc/
+ abbbbc
+
+/ab{1,}bc/
+ abbbbc
+
+/ab{1,3}bc/
+ abbbbc
+
+/ab{3,4}bc/
+ abbbbc
+
+/ab{4,5}bc/
+ *** Failers
+ abq
+ abbbbc
+
+/ab?bc/
+ abbc
+ abc
+
+/ab{0,1}bc/
+ abc
+
+/ab?bc/
+
+/ab?c/
+ abc
+
+/ab{0,1}c/
+ abc
+
+/^abc$/
+ abc
+ *** Failers
+ abbbbc
+ abcc
+
+/^abc/
+ abcc
+
+/^abc$/
+
+/abc$/
+ aabc
+ *** Failers
+ aabc
+ aabcd
+
+/^/
+ abc
+
+/$/
+ abc
+
+/a.c/
+ abc
+ axc
+
+/a.*c/
+ axyzc
+
+/a[bc]d/
+ abd
+ *** Failers
+ axyzd
+ abc
+
+/a[b-d]e/
+ ace
+
+/a[b-d]/
+ aac
+
+/a[-b]/
+ a-
+
+/a[b-]/
+ a-
+
+/a]/
+ a]
+
+/a[]]b/
+ a]b
+
+/a[^bc]d/
+ aed
+ *** Failers
+ abd
+ abd
+
+/a[^-b]c/
+ adc
+
+/a[^]b]c/
+ adc
+ *** Failers
+ a-c
+ a]c
+
+/\ba\b/
+ a-
+ -a
+ -a-
+
+/\by\b/
+ *** Failers
+ xy
+ yz
+ xyz
+
+/\Ba\B/
+ *** Failers
+ a-
+ -a
+ -a-
+
+/\By\b/
+ xy
+
+/\by\B/
+ yz
+
+/\By\B/
+ xyz
+
+/\w/
+ a
+
+/\W/
+ -
+ *** Failers
+ -
+ a
+
+/a\sb/
+ a b
+
+/a\Sb/
+ a-b
+ *** Failers
+ a-b
+ a b
+
+/\d/
+ 1
+
+/\D/
+ -
+ *** Failers
+ -
+ 1
+
+/[\w]/
+ a
+
+/[\W]/
+ -
+ *** Failers
+ -
+ a
+
+/a[\s]b/
+ a b
+
+/a[\S]b/
+ a-b
+ *** Failers
+ a-b
+ a b
+
+/[\d]/
+ 1
+
+/[\D]/
+ -
+ *** Failers
+ -
+ 1
+
+/ab|cd/
+ abc
+ abcd
+
+/()ef/
+ def
+
+/$b/
+
+/a\(b/
+ a(b
+
+/a\(*b/
+ ab
+ a((b
+
+/a\\b/
+ a\b
+
+/((a))/
+ abc
+
+/(a)b(c)/
+ abc
+
+/a+b+c/
+ aabbabc
+
+/a{1,}b{1,}c/
+ aabbabc
+
+/a.+?c/
+ abcabc
+
+/(a+|b)*/
+ ab
+
+/(a+|b){0,}/
+ ab
+
+/(a+|b)+/
+ ab
+
+/(a+|b){1,}/
+ ab
+
+/(a+|b)?/
+ ab
+
+/(a+|b){0,1}/
+ ab
+
+/[^ab]*/
+ cde
+
+/abc/
+ *** Failers
+ b
+
+
+/a*/
+
+
+/([abc])*d/
+ abbbcd
+
+/([abc])*bcd/
+ abcd
+
+/a|b|c|d|e/
+ e
+
+/(a|b|c|d|e)f/
+ ef
+
+/abcd*efg/
+ abcdefg
+
+/ab*/
+ xabyabbbz
+ xayabbbz
+
+/(ab|cd)e/
+ abcde
+
+/[abhgefdc]ij/
+ hij
+
+/^(ab|cd)e/
+
+/(abc|)ef/
+ abcdef
+
+/(a|b)c*d/
+ abcd
+
+/(ab|ab*)bc/
+ abc
+
+/a([bc]*)c*/
+ abc
+
+/a([bc]*)(c*d)/
+ abcd
+
+/a([bc]+)(c*d)/
+ abcd
+
+/a([bc]*)(c+d)/
+ abcd
+
+/a[bcd]*dcdcde/
+ adcdcde
+
+/a[bcd]+dcdcde/
+ *** Failers
+ abcde
+ adcdcde
+
+/(ab|a)b*c/
+ abc
+
+/((a)(b)c)(d)/
+ abcd
+
+/[a-zA-Z_][a-zA-Z0-9_]*/
+ alpha
+
+/^a(bc+|b[eh])g|.h$/
+ abh
+
+/(bc+d$|ef*g.|h?i(j|k))/
+ effgz
+ ij
+ reffgz
+ *** Failers
+ effg
+ bcdd
+
+/((((((((((a))))))))))/
+ a
+
+/((((((((((a))))))))))\10/
+ aa
+
+/(((((((((a)))))))))/
+ a
+
+/multiple words of text/
+ *** Failers
+ aa
+ uh-uh
+
+/multiple words/
+ multiple words, yeah
+
+/(.*)c(.*)/
+ abcde
+
+/\((.*), (.*)\)/
+ (a, b)
+
+/[k]/
+
+/abcd/
+ abcd
+
+/a(bc)d/
+ abcd
+
+/a[-]?c/
+ ac
+
+/(abc)\1/
+ abcabc
+
+/([a-c]*)\1/
+ abcabc
+
+/(a)|\1/
+ a
+ *** Failers
+ ab
+ x
+
+/(([a-c])b*?\2)*/
+ ababbbcbc
+
+/(([a-c])b*?\2){3}/
+ ababbbcbc
+
+/((\3|b)\2(a)x)+/
+ aaaxabaxbaaxbbax
+
+/((\3|b)\2(a)){2,}/
+ bbaababbabaaaaabbaaaabba
+
+/abc/i
+ ABC
+ XABCY
+ ABABC
+ *** Failers
+ aaxabxbaxbbx
+ XBC
+ AXC
+ ABX
+
+/ab*c/i
+ ABC
+
+/ab*bc/i
+ ABC
+ ABBC
+
+/ab*?bc/i
+ ABBBBC
+
+/ab{0,}?bc/i
+ ABBBBC
+
+/ab+?bc/i
+ ABBC
+
+/ab+bc/i
+ *** Failers
+ ABC
+ ABQ
+
+/ab{1,}bc/i
+
+/ab+bc/i
+ ABBBBC
+
+/ab{1,}?bc/i
+ ABBBBC
+
+/ab{1,3}?bc/i
+ ABBBBC
+
+/ab{3,4}?bc/i
+ ABBBBC
+
+/ab{4,5}?bc/i
+ *** Failers
+ ABQ
+ ABBBBC
+
+/ab??bc/i
+ ABBC
+ ABC
+
+/ab{0,1}?bc/i
+ ABC
+
+/ab??bc/i
+
+/ab??c/i
+ ABC
+
+/ab{0,1}?c/i
+ ABC
+
+/^abc$/i
+ ABC
+ *** Failers
+ ABBBBC
+ ABCC
+
+/^abc/i
+ ABCC
+
+/^abc$/i
+
+/abc$/i
+ AABC
+
+/^/i
+ ABC
+
+/$/i
+ ABC
+
+/a.c/i
+ ABC
+ AXC
+
+/a.*?c/i
+ AXYZC
+
+/a.*c/i
+ *** Failers
+ AABC
+ AXYZD
+
+/a[bc]d/i
+ ABD
+
+/a[b-d]e/i
+ ACE
+ *** Failers
+ ABC
+ ABD
+
+/a[b-d]/i
+ AAC
+
+/a[-b]/i
+ A-
+
+/a[b-]/i
+ A-
+
+/a]/i
+ A]
+
+/a[]]b/i
+ A]B
+
+/a[^bc]d/i
+ AED
+
+/a[^-b]c/i
+ ADC
+ *** Failers
+ ABD
+ A-C
+
+/a[^]b]c/i
+ ADC
+
+/ab|cd/i
+ ABC
+ ABCD
+
+/()ef/i
+ DEF
+
+/$b/i
+ *** Failers
+ A]C
+ B
+
+/a\(b/i
+ A(B
+
+/a\(*b/i
+ AB
+ A((B
+
+/a\\b/i
+ A\B
+
+/((a))/i
+ ABC
+
+/(a)b(c)/i
+ ABC
+
+/a+b+c/i
+ AABBABC
+
+/a{1,}b{1,}c/i
+ AABBABC
+
+/a.+?c/i
+ ABCABC
+
+/a.*?c/i
+ ABCABC
+
+/a.{0,5}?c/i
+ ABCABC
+
+/(a+|b)*/i
+ AB
+
+/(a+|b){0,}/i
+ AB
+
+/(a+|b)+/i
+ AB
+
+/(a+|b){1,}/i
+ AB
+
+/(a+|b)?/i
+ AB
+
+/(a+|b){0,1}/i
+ AB
+
+/(a+|b){0,1}?/i
+ AB
+
+/[^ab]*/i
+ CDE
+
+/abc/i
+
+/a*/i
+
+
+/([abc])*d/i
+ ABBBCD
+
+/([abc])*bcd/i
+ ABCD
+
+/a|b|c|d|e/i
+ E
+
+/(a|b|c|d|e)f/i
+ EF
+
+/abcd*efg/i
+ ABCDEFG
+
+/ab*/i
+ XABYABBBZ
+ XAYABBBZ
+
+/(ab|cd)e/i
+ ABCDE
+
+/[abhgefdc]ij/i
+ HIJ
+
+/^(ab|cd)e/i
+ ABCDE
+
+/(abc|)ef/i
+ ABCDEF
+
+/(a|b)c*d/i
+ ABCD
+
+/(ab|ab*)bc/i
+ ABC
+
+/a([bc]*)c*/i
+ ABC
+
+/a([bc]*)(c*d)/i
+ ABCD
+
+/a([bc]+)(c*d)/i
+ ABCD
+
+/a([bc]*)(c+d)/i
+ ABCD
+
+/a[bcd]*dcdcde/i
+ ADCDCDE
+
+/a[bcd]+dcdcde/i
+
+/(ab|a)b*c/i
+ ABC
+
+/((a)(b)c)(d)/i
+ ABCD
+
+/[a-zA-Z_][a-zA-Z0-9_]*/i
+ ALPHA
+
+/^a(bc+|b[eh])g|.h$/i
+ ABH
+
+/(bc+d$|ef*g.|h?i(j|k))/i
+ EFFGZ
+ IJ
+ REFFGZ
+ *** Failers
+ ADCDCDE
+ EFFG
+ BCDD
+
+/((((((((((a))))))))))/i
+ A
+
+/((((((((((a))))))))))\10/i
+ AA
+
+/(((((((((a)))))))))/i
+ A
+
+/(?:(?:(?:(?:(?:(?:(?:(?:(?:(a))))))))))/i
+ A
+
+/(?:(?:(?:(?:(?:(?:(?:(?:(?:(a|b|c))))))))))/i
+ C
+
+/multiple words of text/i
+ *** Failers
+ AA
+ UH-UH
+
+/multiple words/i
+ MULTIPLE WORDS, YEAH
+
+/(.*)c(.*)/i
+ ABCDE
+
+/\((.*), (.*)\)/i
+ (A, B)
+
+/[k]/i
+
+/abcd/i
+ ABCD
+
+/a(bc)d/i
+ ABCD
+
+/a[-]?c/i
+ AC
+
+/(abc)\1/i
+ ABCABC
+
+/([a-c]*)\1/i
+ ABCABC
+
+/a(?!b)./
+ abad
+
+/a(?=d)./
+ abad
+
+/a(?=c|d)./
+ abad
+
+/a(?:b|c|d)(.)/
+ ace
+
+/a(?:b|c|d)*(.)/
+ ace
+
+/a(?:b|c|d)+?(.)/
+ ace
+ acdbcdbe
+
+/a(?:b|c|d)+(.)/
+ acdbcdbe
+
+/a(?:b|c|d){2}(.)/
+ acdbcdbe
+
+/a(?:b|c|d){4,5}(.)/
+ acdbcdbe
+
+/a(?:b|c|d){4,5}?(.)/
+ acdbcdbe
+
+/((foo)|(bar))*/
+ foobar
+
+/a(?:b|c|d){6,7}(.)/
+ acdbcdbe
+
+/a(?:b|c|d){6,7}?(.)/
+ acdbcdbe
+
+/a(?:b|c|d){5,6}(.)/
+ acdbcdbe
+
+/a(?:b|c|d){5,6}?(.)/
+ acdbcdbe
+
+/a(?:b|c|d){5,7}(.)/
+ acdbcdbe
+
+/a(?:b|c|d){5,7}?(.)/
+ acdbcdbe
+
+/a(?:b|(c|e){1,2}?|d)+?(.)/
+ ace
+
+/^(.+)?B/
+ AB
+
+/^([^a-z])|(\^)$/
+ .
+
+/^[<>]&/
+ <&OUT
+
+/^(a\1?){4}$/
+ aaaaaaaaaa
+ *** Failers
+ AB
+ aaaaaaaaa
+ aaaaaaaaaaa
+
+/^(a(?(1)\1)){4}$/
+ aaaaaaaaaa
+ *** Failers
+ aaaaaaaaa
+ aaaaaaaaaaa
+
+/(?:(f)(o)(o)|(b)(a)(r))*/
+ foobar
+
+/(?<=a)b/
+ ab
+ *** Failers
+ cb
+ b
+
+/(?<!c)b/
+ ab
+ b
+ b
+
+/(?:..)*a/
+ aba
+
+/(?:..)*?a/
+ aba
+
+/^(?:b|a(?=(.)))*\1/
+ abc
+
+/^(){3,5}/
+ abc
+
+/^(a+)*ax/
+ aax
+
+/^((a|b)+)*ax/
+ aax
+
+/^((a|bc)+)*ax/
+ aax
+
+/(a|x)*ab/
+ cab
+
+/(a)*ab/
+ cab
+
+/(?:(?i)a)b/
+ ab
+
+/((?i)a)b/
+ ab
+
+/(?:(?i)a)b/
+ Ab
+
+/((?i)a)b/
+ Ab
+
+/(?:(?i)a)b/
+ *** Failers
+ cb
+ aB
+
+/((?i)a)b/
+
+/(?i:a)b/
+ ab
+
+/((?i:a))b/
+ ab
+
+/(?i:a)b/
+ Ab
+
+/((?i:a))b/
+ Ab
+
+/(?i:a)b/
+ *** Failers
+ aB
+ aB
+
+/((?i:a))b/
+
+/(?:(?-i)a)b/i
+ ab
+
+/((?-i)a)b/i
+ ab
+
+/(?:(?-i)a)b/i
+ aB
+
+/((?-i)a)b/i
+ aB
+
+/(?:(?-i)a)b/i
+ *** Failers
+ aB
+ Ab
+
+/((?-i)a)b/i
+
+/(?:(?-i)a)b/i
+ aB
+
+/((?-i)a)b/i
+ aB
+
+/(?:(?-i)a)b/i
+ *** Failers
+ Ab
+ AB
+
+/((?-i)a)b/i
+
+/(?-i:a)b/i
+ ab
+
+/((?-i:a))b/i
+ ab
+
+/(?-i:a)b/i
+ aB
+
+/((?-i:a))b/i
+ aB
+
+/(?-i:a)b/i
+ *** Failers
+ AB
+ Ab
+
+/((?-i:a))b/i
+
+/(?-i:a)b/i
+ aB
+
+/((?-i:a))b/i
+ aB
+
+/(?-i:a)b/i
+ *** Failers
+ Ab
+ AB
+
+/((?-i:a))b/i
+
+/((?-i:a.))b/i
+ *** Failers
+ AB
+ a\nB
+
+/((?s-i:a.))b/i
+ a\nB
+
+/(?:c|d)(?:)(?:a(?:)(?:b)(?:b(?:))(?:b(?:)(?:b)))/
+ cabbbb
+
+/(?:c|d)(?:)(?:aaaaaaaa(?:)(?:bbbbbbbb)(?:bbbbbbbb(?:))(?:bbbbbbbb(?:)(?:bbbbbbbb)))/
+ caaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
+
+/(ab)\d\1/i
+ Ab4ab
+ ab4Ab
+
+/foo\w*\d{4}baz/
+ foobar1234baz
+
+/x(~~)*(?:(?:F)?)?/
+ x~~
+
+/^a(?#xxx){3}c/
+ aaac
+
+/^a (?#xxx) (?#yyy) {3}c/x
+ aaac
+
+/(?<![cd])b/
+ *** Failers
+ B\nB
+ dbcb
+
+/(?<![cd])[ab]/
+ dbaacb
+
+/(?<!(c|d))b/
+
+/(?<!(c|d))[ab]/
+ dbaacb
+
+/(?<!cd)[ab]/
+ cdaccb
+
+/^(?:a?b?)*$/
+ *** Failers
+ dbcb
+ a--
+
+/((?s)^a(.))((?m)^b$)/
+ a\nb\nc\n
+
+/((?m)^b$)/
+ a\nb\nc\n
+
+/(?m)^b/
+ a\nb\n
+
+/(?m)^(b)/
+ a\nb\n
+
+/((?m)^b)/
+ a\nb\n
+
+/\n((?m)^b)/
+ a\nb\n
+
+/((?s).)c(?!.)/
+ a\nb\nc\n
+ a\nb\nc\n
+
+/((?s)b.)c(?!.)/
+ a\nb\nc\n
+ a\nb\nc\n
+
+/^b/
+
+/()^b/
+ *** Failers
+ a\nb\nc\n
+ a\nb\nc\n
+
+/((?m)^b)/
+ a\nb\nc\n
+
+/(?(1)a|b)/
+
+/(?(1)b|a)/
+ a
+
+/(x)?(?(1)a|b)/
+ *** Failers
+ a
+ a
+
+/(x)?(?(1)b|a)/
+ a
+
+/()?(?(1)b|a)/
+ a
+
+/()(?(1)b|a)/
+
+/()?(?(1)a|b)/
+ a
+
+/^(\()?blah(?(1)(\)))$/
+ (blah)
+ blah
+ *** Failers
+ a
+ blah)
+ (blah
+
+/^(\(+)?blah(?(1)(\)))$/
+ (blah)
+ blah
+ *** Failers
+ blah)
+ (blah
+
+/(?(?!a)a|b)/
+
+/(?(?!a)b|a)/
+ a
+
+/(?(?=a)b|a)/
+ *** Failers
+ a
+ a
+
+/(?(?=a)a|b)/
+ a
+
+/(?=(a+?))(\1ab)/
+ aaab
+
+/^(?=(a+?))\1ab/
+
+/(\w+:)+/
+ one:
+
+/$(?<=^(a))/
+ a
+
+/(?=(a+?))(\1ab)/
+ aaab
+
+/^(?=(a+?))\1ab/
+ *** Failers
+ aaab
+ aaab
+
+/([\w:]+::)?(\w+)$/
+ abcd
+ xy:z:::abcd
+
+/^[^bcd]*(c+)/
+ aexycd
+
+/(a*)b+/
+ caab
+
+/([\w:]+::)?(\w+)$/
+ abcd
+ xy:z:::abcd
+ *** Failers
+ abcd:
+ abcd:
+
+/^[^bcd]*(c+)/
+ aexycd
+
+/(>a+)ab/
+
+/(?>a+)b/
+ aaab
+
+/([[:]+)/
+ a:[b]:
+
+/([[=]+)/
+ a=[b]=
+
+/([[.]+)/
+ a.[b].
+
+/((?>a+)b)/
+ aaab
+
+/(?>(a+))b/
+ aaab
+
+/((?>[^()]+)|\([^()]*\))+/
+ ((abc(ade)ufh()()x
+
+/a\Z/
+ *** Failers
+ aaab
+ a\nb\n
+
+/b\Z/
+ a\nb\n
+
+/b\z/
+
+/b\Z/
+ a\nb
+
+/b\z/
+ a\nb
+ *** Failers
+
+/^(?>(?(1)\.|())[^\W_](?>[a-z0-9-]*[^\W_])?)+$/
+ a
+ abc
+ a-b
+ 0-9
+ a.b
+ 5.6.7
+ the.quick.brown.fox
+ a100.b200.300c
+ 12-ab.1245
+ ***Failers
+ \
+ .a
+ -a
+ a-
+ a.
+ a_b
+ a.-
+ a..
+ ab..bc
+ the.quick.brown.fox-
+ the.quick.brown.fox.
+ the.quick.brown.fox_
+ the.quick.brown.fox+
+
+/(?>.*)(?<=(abcd|wxyz))/
+ alphabetabcd
+ endingwxyz
+ *** Failers
+ a rather long string that doesn't end with one of them
+
+/word (?>(?:(?!otherword)[a-zA-Z0-9]+ ){0,30})otherword/
+ word cat dog elephant mussel cow horse canary baboon snake shark otherword
+ word cat dog elephant mussel cow horse canary baboon snake shark
+
+/word (?>[a-zA-Z0-9]+ ){0,30}otherword/
+ word cat dog elephant mussel cow horse canary baboon snake shark the quick brown fox and the lazy dog and several other words getting close to thirty by now I hope
+
+/(?<=\d{3}(?!999))foo/
+ 999foo
+ 123999foo
+ *** Failers
+ 123abcfoo
+
+/(?<=(?!...999)\d{3})foo/
+ 999foo
+ 123999foo
+ *** Failers
+ 123abcfoo
+
+/(?<=\d{3}(?!999)...)foo/
+ 123abcfoo
+ 123456foo
+ *** Failers
+ 123999foo
+
+/(?<=\d{3}...)(?<!999)foo/
+ 123abcfoo
+ 123456foo
+ *** Failers
+ 123999foo
+
+/<a[\s]+href[\s]*=[\s]* # find <a href=
+ ([\"\'])? # find single or double quote
+ (?(1) (.*?)\1 | ([^\s]+)) # if quote found, match up to next matching
+ # quote, otherwise match up to next space
+/isx
+ <a href=abcd xyz
+ <a href=\"abcd xyz pqr\" cats
+ <a href=\'abcd xyz pqr\' cats
+
+/<a\s+href\s*=\s* # find <a href=
+ (["'])? # find single or double quote
+ (?(1) (.*?)\1 | (\S+)) # if quote found, match up to next matching
+ # quote, otherwise match up to next space
+/isx
+ <a href=abcd xyz
+ <a href=\"abcd xyz pqr\" cats
+ <a href = \'abcd xyz pqr\' cats
+
+/<a\s+href(?>\s*)=(?>\s*) # find <a href=
+ (["'])? # find single or double quote
+ (?(1) (.*?)\1 | (\S+)) # if quote found, match up to next matching
+ # quote, otherwise match up to next space
+/isx
+ <a href=abcd xyz
+ <a href=\"abcd xyz pqr\" cats
+ <a href = \'abcd xyz pqr\' cats
+
+/ End of test input /
--- /dev/null
+/^[\w]+/
+ *** Failers
+ École
+
+/^[\w]+/Lfr
+ École
+
+/^[\w]+/
+ *** Failers
+ École
+
+/^[\W]+/
+ École
+
+/^[\W]+/Lfr
+ *** Failers
+ École
+
+/[\b]/
+ \b
+ *** Failers
+ a
+
+/[\b]/Lfr
+ \b
+ *** Failers
+ a
+
+/^\w+/
+ *** Failers
+ École
+
+/^\w+/Lfr
+ École
+
+/(.+)\b(.+)/
+ École
+
+/(.+)\b(.+)/Lfr
+ *** Failers
+ École
+
+/École/i
+ École
+ *** Failers
+ école
+
+/École/iLfr
+ École
+ école
+
+/\w/IS
+
+/\w/ISLfr
+
+/^[\xc8-\xc9]/iLfr
+ École
+ école
+
+/^[\xc8-\xc9]/Lfr
+ École
+ *** Failers
+ école
+
--- /dev/null
+PCRE version 3.1 09-Feb-2000
+
+/the quick brown fox/
+ the quick brown fox
+ 0: the quick brown fox
+ The quick brown FOX
+No match
+ What do you know about the quick brown fox?
+ 0: the quick brown fox
+ What do you know about THE QUICK BROWN FOX?
+No match
+
+/The quick brown fox/i
+ the quick brown fox
+ 0: the quick brown fox
+ The quick brown FOX
+ 0: The quick brown FOX
+ What do you know about the quick brown fox?
+ 0: the quick brown fox
+ What do you know about THE QUICK BROWN FOX?
+ 0: THE QUICK BROWN FOX
+
+/abcd\t\n\r\f\a\e\071\x3b\$\\\?caxyz/
+ abcd\t\n\r\f\a\e9;\$\\?caxyz
+ 0: abcd\x09\x0a\x0d\x0c\x07\x1b9;$\?caxyz
+
+/a*abc?xyz+pqr{3}ab{2,}xy{4,5}pq{0,6}AB{0,}zz/
+ abxyzpqrrrabbxyyyypqAzz
+ 0: abxyzpqrrrabbxyyyypqAzz
+ abxyzpqrrrabbxyyyypqAzz
+ 0: abxyzpqrrrabbxyyyypqAzz
+ aabxyzpqrrrabbxyyyypqAzz
+ 0: aabxyzpqrrrabbxyyyypqAzz
+ aaabxyzpqrrrabbxyyyypqAzz
+ 0: aaabxyzpqrrrabbxyyyypqAzz
+ aaaabxyzpqrrrabbxyyyypqAzz
+ 0: aaaabxyzpqrrrabbxyyyypqAzz
+ abcxyzpqrrrabbxyyyypqAzz
+ 0: abcxyzpqrrrabbxyyyypqAzz
+ aabcxyzpqrrrabbxyyyypqAzz
+ 0: aabcxyzpqrrrabbxyyyypqAzz
+ aaabcxyzpqrrrabbxyyyypAzz
+ 0: aaabcxyzpqrrrabbxyyyypAzz
+ aaabcxyzpqrrrabbxyyyypqAzz
+ 0: aaabcxyzpqrrrabbxyyyypqAzz
+ aaabcxyzpqrrrabbxyyyypqqAzz
+ 0: aaabcxyzpqrrrabbxyyyypqqAzz
+ aaabcxyzpqrrrabbxyyyypqqqAzz
+ 0: aaabcxyzpqrrrabbxyyyypqqqAzz
+ aaabcxyzpqrrrabbxyyyypqqqqAzz
+ 0: aaabcxyzpqrrrabbxyyyypqqqqAzz
+ aaabcxyzpqrrrabbxyyyypqqqqqAzz
+ 0: aaabcxyzpqrrrabbxyyyypqqqqqAzz
+ aaabcxyzpqrrrabbxyyyypqqqqqqAzz
+ 0: aaabcxyzpqrrrabbxyyyypqqqqqqAzz
+ aaaabcxyzpqrrrabbxyyyypqAzz
+ 0: aaaabcxyzpqrrrabbxyyyypqAzz
+ abxyzzpqrrrabbxyyyypqAzz
+ 0: abxyzzpqrrrabbxyyyypqAzz
+ aabxyzzzpqrrrabbxyyyypqAzz
+ 0: aabxyzzzpqrrrabbxyyyypqAzz
+ aaabxyzzzzpqrrrabbxyyyypqAzz
+ 0: aaabxyzzzzpqrrrabbxyyyypqAzz
+ aaaabxyzzzzpqrrrabbxyyyypqAzz
+ 0: aaaabxyzzzzpqrrrabbxyyyypqAzz
+ abcxyzzpqrrrabbxyyyypqAzz
+ 0: abcxyzzpqrrrabbxyyyypqAzz
+ aabcxyzzzpqrrrabbxyyyypqAzz
+ 0: aabcxyzzzpqrrrabbxyyyypqAzz
+ aaabcxyzzzzpqrrrabbxyyyypqAzz
+ 0: aaabcxyzzzzpqrrrabbxyyyypqAzz
+ aaaabcxyzzzzpqrrrabbxyyyypqAzz
+ 0: aaaabcxyzzzzpqrrrabbxyyyypqAzz
+ aaaabcxyzzzzpqrrrabbbxyyyypqAzz
+ 0: aaaabcxyzzzzpqrrrabbbxyyyypqAzz
+ aaaabcxyzzzzpqrrrabbbxyyyyypqAzz
+ 0: aaaabcxyzzzzpqrrrabbbxyyyyypqAzz
+ aaabcxyzpqrrrabbxyyyypABzz
+ 0: aaabcxyzpqrrrabbxyyyypABzz
+ aaabcxyzpqrrrabbxyyyypABBzz
+ 0: aaabcxyzpqrrrabbxyyyypABBzz
+ >>>aaabxyzpqrrrabbxyyyypqAzz
+ 0: aaabxyzpqrrrabbxyyyypqAzz
+ >aaaabxyzpqrrrabbxyyyypqAzz
+ 0: aaaabxyzpqrrrabbxyyyypqAzz
+ >>>>abcxyzpqrrrabbxyyyypqAzz
+ 0: abcxyzpqrrrabbxyyyypqAzz
+ *** Failers
+No match
+ abxyzpqrrabbxyyyypqAzz
+No match
+ abxyzpqrrrrabbxyyyypqAzz
+No match
+ abxyzpqrrrabxyyyypqAzz
+No match
+ aaaabcxyzzzzpqrrrabbbxyyyyyypqAzz
+No match
+ aaaabcxyzzzzpqrrrabbbxyyypqAzz
+No match
+ aaabcxyzpqrrrabbxyyyypqqqqqqqAzz
+No match
+
+/^(abc){1,2}zz/
+ abczz
+ 0: abczz
+ 1: abc
+ abcabczz
+ 0: abcabczz
+ 1: abc
+ *** Failers
+No match
+ zz
+No match
+ abcabcabczz
+No match
+ >>abczz
+No match
+
+/^(b+?|a){1,2}?c/
+ bc
+ 0: bc
+ 1: b
+ bbc
+ 0: bbc
+ 1: b
+ bbbc
+ 0: bbbc
+ 1: bb
+ bac
+ 0: bac
+ 1: a
+ bbac
+ 0: bbac
+ 1: a
+ aac
+ 0: aac
+ 1: a
+ abbbbbbbbbbbc
+ 0: abbbbbbbbbbbc
+ 1: bbbbbbbbbbb
+ bbbbbbbbbbbac
+ 0: bbbbbbbbbbbac
+ 1: a
+ *** Failers
+No match
+ aaac
+No match
+ abbbbbbbbbbbac
+No match
+
+/^(b+|a){1,2}c/
+ bc
+ 0: bc
+ 1: b
+ bbc
+ 0: bbc
+ 1: bb
+ bbbc
+ 0: bbbc
+ 1: bbb
+ bac
+ 0: bac
+ 1: a
+ bbac
+ 0: bbac
+ 1: a
+ aac
+ 0: aac
+ 1: a
+ abbbbbbbbbbbc
+ 0: abbbbbbbbbbbc
+ 1: bbbbbbbbbbb
+ bbbbbbbbbbbac
+ 0: bbbbbbbbbbbac
+ 1: a
+ *** Failers
+No match
+ aaac
+No match
+ abbbbbbbbbbbac
+No match
+
+/^(b+|a){1,2}?bc/
+ bbc
+ 0: bbc
+ 1: b
+
+/^(b*|ba){1,2}?bc/
+ babc
+ 0: babc
+ 1: ba
+ bbabc
+ 0: bbabc
+ 1: ba
+ bababc
+ 0: bababc
+ 1: ba
+ *** Failers
+No match
+ bababbc
+No match
+ babababc
+No match
+
+/^(ba|b*){1,2}?bc/
+ babc
+ 0: babc
+ 1: ba
+ bbabc
+ 0: bbabc
+ 1: ba
+ bababc
+ 0: bababc
+ 1: ba
+ *** Failers
+No match
+ bababbc
+No match
+ babababc
+No match
+
+/^\ca\cA\c[\c{\c:/
+ \x01\x01\e;z
+ 0: \x01\x01\x1b;z
+
+/^[ab\]cde]/
+ athing
+ 0: a
+ bthing
+ 0: b
+ ]thing
+ 0: ]
+ cthing
+ 0: c
+ dthing
+ 0: d
+ ething
+ 0: e
+ *** Failers
+No match
+ fthing
+No match
+ [thing
+No match
+ \\thing
+No match
+
+/^[]cde]/
+ ]thing
+ 0: ]
+ cthing
+ 0: c
+ dthing
+ 0: d
+ ething
+ 0: e
+ *** Failers
+No match
+ athing
+No match
+ fthing
+No match
+
+/^[^ab\]cde]/
+ fthing
+ 0: f
+ [thing
+ 0: [
+ \\thing
+ 0: \
+ *** Failers
+ 0: *
+ athing
+No match
+ bthing
+No match
+ ]thing
+No match
+ cthing
+No match
+ dthing
+No match
+ ething
+No match
+
+/^[^]cde]/
+ athing
+ 0: a
+ fthing
+ 0: f
+ *** Failers
+ 0: *
+ ]thing
+No match
+ cthing
+No match
+ dthing
+No match
+ ething
+No match
+
+/^\\81/
+ \81
+ 0: \x81
+
+/^ÿ/
+ ÿ
+ 0: \xff
+
+/^[0-9]+$/
+ 0
+ 0: 0
+ 1
+ 0: 1
+ 2
+ 0: 2
+ 3
+ 0: 3
+ 4
+ 0: 4
+ 5
+ 0: 5
+ 6
+ 0: 6
+ 7
+ 0: 7
+ 8
+ 0: 8
+ 9
+ 0: 9
+ 10
+ 0: 10
+ 100
+ 0: 100
+ *** Failers
+No match
+ abc
+No match
+
+/^.*nter/
+ enter
+ 0: enter
+ inter
+ 0: inter
+ uponter
+ 0: uponter
+
+/^xxx[0-9]+$/
+ xxx0
+ 0: xxx0
+ xxx1234
+ 0: xxx1234
+ *** Failers
+No match
+ xxx
+No match
+
+/^.+[0-9][0-9][0-9]$/
+ x123
+ 0: x123
+ xx123
+ 0: xx123
+ 123456
+ 0: 123456
+ *** Failers
+No match
+ 123
+No match
+ x1234
+ 0: x1234
+
+/^.+?[0-9][0-9][0-9]$/
+ x123
+ 0: x123
+ xx123
+ 0: xx123
+ 123456
+ 0: 123456
+ *** Failers
+No match
+ 123
+No match
+ x1234
+ 0: x1234
+
+/^([^!]+)!(.+)=apquxz\.ixr\.zzz\.ac\.uk$/
+ abc!pqr=apquxz.ixr.zzz.ac.uk
+ 0: abc!pqr=apquxz.ixr.zzz.ac.uk
+ 1: abc
+ 2: pqr
+ *** Failers
+No match
+ !pqr=apquxz.ixr.zzz.ac.uk
+No match
+ abc!=apquxz.ixr.zzz.ac.uk
+No match
+ abc!pqr=apquxz:ixr.zzz.ac.uk
+No match
+ abc!pqr=apquxz.ixr.zzz.ac.ukk
+No match
+
+/:/
+ Well, we need a colon: somewhere
+ 0: :
+ *** Fail if we don't
+No match
+
+/([\da-f:]+)$/i
+ 0abc
+ 0: 0abc
+ 1: 0abc
+ abc
+ 0: abc
+ 1: abc
+ fed
+ 0: fed
+ 1: fed
+ E
+ 0: E
+ 1: E
+ ::
+ 0: ::
+ 1: ::
+ 5f03:12C0::932e
+ 0: 5f03:12C0::932e
+ 1: 5f03:12C0::932e
+ fed def
+ 0: def
+ 1: def
+ Any old stuff
+ 0: ff
+ 1: ff
+ *** Failers
+No match
+ 0zzz
+No match
+ gzzz
+No match
+ fed\x20
+No match
+ Any old rubbish
+No match
+
+/^.*\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$/
+ .1.2.3
+ 0: .1.2.3
+ 1: 1
+ 2: 2
+ 3: 3
+ A.12.123.0
+ 0: A.12.123.0
+ 1: 12
+ 2: 123
+ 3: 0
+ *** Failers
+No match
+ .1.2.3333
+No match
+ 1.2.3
+No match
+ 1234.2.3
+No match
+
+/^(\d+)\s+IN\s+SOA\s+(\S+)\s+(\S+)\s*\(\s*$/
+ 1 IN SOA non-sp1 non-sp2(
+ 0: 1 IN SOA non-sp1 non-sp2(
+ 1: 1
+ 2: non-sp1
+ 3: non-sp2
+ 1 IN SOA non-sp1 non-sp2 (
+ 0: 1 IN SOA non-sp1 non-sp2 (
+ 1: 1
+ 2: non-sp1
+ 3: non-sp2
+ *** Failers
+No match
+ 1IN SOA non-sp1 non-sp2(
+No match
+
+/^[a-zA-Z\d][a-zA-Z\d\-]*(\.[a-zA-Z\d][a-zA-z\d\-]*)*\.$/
+ a.
+ 0: a.
+ Z.
+ 0: Z.
+ 2.
+ 0: 2.
+ ab-c.pq-r.
+ 0: ab-c.pq-r.
+ 1: .pq-r
+ sxk.zzz.ac.uk.
+ 0: sxk.zzz.ac.uk.
+ 1: .uk
+ x-.y-.
+ 0: x-.y-.
+ 1: .y-
+ *** Failers
+No match
+ -abc.peq.
+No match
+
+/^\*\.[a-z]([a-z\-\d]*[a-z\d]+)?(\.[a-z]([a-z\-\d]*[a-z\d]+)?)*$/
+ *.a
+ 0: *.a
+ *.b0-a
+ 0: *.b0-a
+ 1: 0-a
+ *.c3-b.c
+ 0: *.c3-b.c
+ 1: 3-b
+ 2: .c
+ *.c-a.b-c
+ 0: *.c-a.b-c
+ 1: -a
+ 2: .b-c
+ 3: -c
+ *** Failers
+No match
+ *.0
+No match
+ *.a-
+No match
+ *.a-b.c-
+No match
+ *.c-a.0-c
+No match
+
+/^(?=ab(de))(abd)(e)/
+ abde
+ 0: abde
+ 1: de
+ 2: abd
+ 3: e
+
+/^(?!(ab)de|x)(abd)(f)/
+ abdf
+ 0: abdf
+ 1: <unset>
+ 2: abd
+ 3: f
+
+/^(?=(ab(cd)))(ab)/
+ abcd
+ 0: ab
+ 1: abcd
+ 2: cd
+ 3: ab
+
+/^[\da-f](\.[\da-f])*$/i
+ a.b.c.d
+ 0: a.b.c.d
+ 1: .d
+ A.B.C.D
+ 0: A.B.C.D
+ 1: .D
+ a.b.c.1.2.3.C
+ 0: a.b.c.1.2.3.C
+ 1: .C
+
+/^\".*\"\s*(;.*)?$/
+ \"1234\"
+ 0: "1234"
+ \"abcd\" ;
+ 0: "abcd" ;
+ 1: ;
+ \"\" ; rhubarb
+ 0: "" ; rhubarb
+ 1: ; rhubarb
+ *** Failers
+No match
+ \"1234\" : things
+No match
+
+/^$/
+ \
+ 0:
+ *** Failers
+No match
+
+/ ^ a (?# begins with a) b\sc (?# then b c) $ (?# then end)/x
+ ab c
+ 0: ab c
+ *** Failers
+No match
+ abc
+No match
+ ab cde
+No match
+
+/(?x) ^ a (?# begins with a) b\sc (?# then b c) $ (?# then end)/
+ ab c
+ 0: ab c
+ *** Failers
+No match
+ abc
+No match
+ ab cde
+No match
+
+/^ a\ b[c ]d $/x
+ a bcd
+ 0: a bcd
+ a b d
+ 0: a b d
+ *** Failers
+No match
+ abcd
+No match
+ ab d
+No match
+
+/^(a(b(c)))(d(e(f)))(h(i(j)))(k(l(m)))$/
+ abcdefhijklm
+ 0: abcdefhijklm
+ 1: abc
+ 2: bc
+ 3: c
+ 4: def
+ 5: ef
+ 6: f
+ 7: hij
+ 8: ij
+ 9: j
+10: klm
+11: lm
+12: m
+
+/^(?:a(b(c)))(?:d(e(f)))(?:h(i(j)))(?:k(l(m)))$/
+ abcdefhijklm
+ 0: abcdefhijklm
+ 1: bc
+ 2: c
+ 3: ef
+ 4: f
+ 5: ij
+ 6: j
+ 7: lm
+ 8: m
+
+/^[\w][\W][\s][\S][\d][\D][\b][\n][\c]][\022]/
+ a+ Z0+\x08\n\x1d\x12
+ 0: a+ Z0+\x08\x0a\x1d\x12
+
+/^[.^$|()*+?{,}]+/
+ .^\$(*+)|{?,?}
+ 0: .^$(*+)|{?,?}
+
+/^a*\w/
+ z
+ 0: z
+ az
+ 0: az
+ aaaz
+ 0: aaaz
+ a
+ 0: a
+ aa
+ 0: aa
+ aaaa
+ 0: aaaa
+ a+
+ 0: a
+ aa+
+ 0: aa
+
+/^a*?\w/
+ z
+ 0: z
+ az
+ 0: a
+ aaaz
+ 0: a
+ a
+ 0: a
+ aa
+ 0: a
+ aaaa
+ 0: a
+ a+
+ 0: a
+ aa+
+ 0: a
+
+/^a+\w/
+ az
+ 0: az
+ aaaz
+ 0: aaaz
+ aa
+ 0: aa
+ aaaa
+ 0: aaaa
+ aa+
+ 0: aa
+
+/^a+?\w/
+ az
+ 0: az
+ aaaz
+ 0: aa
+ aa
+ 0: aa
+ aaaa
+ 0: aa
+ aa+
+ 0: aa
+
+/^\d{8}\w{2,}/
+ 1234567890
+ 0: 1234567890
+ 12345678ab
+ 0: 12345678ab
+ 12345678__
+ 0: 12345678__
+ *** Failers
+No match
+ 1234567
+No match
+
+/^[aeiou\d]{4,5}$/
+ uoie
+ 0: uoie
+ 1234
+ 0: 1234
+ 12345
+ 0: 12345
+ aaaaa
+ 0: aaaaa
+ *** Failers
+No match
+ 123456
+No match
+
+/^[aeiou\d]{4,5}?/
+ uoie
+ 0: uoie
+ 1234
+ 0: 1234
+ 12345
+ 0: 1234
+ aaaaa
+ 0: aaaa
+ 123456
+ 0: 1234
+
+/\A(abc|def)=(\1){2,3}\Z/
+ abc=abcabc
+ 0: abc=abcabc
+ 1: abc
+ 2: abc
+ def=defdefdef
+ 0: def=defdefdef
+ 1: def
+ 2: def
+ *** Failers
+No match
+ abc=defdef
+No match
+
+/^(a)(b)(c)(d)(e)(f)(g)(h)(i)(j)(k)\11*(\3\4)\1(?#)2$/
+ abcdefghijkcda2
+ 0: abcdefghijkcda2
+ 1: a
+ 2: b
+ 3: c
+ 4: d
+ 5: e
+ 6: f
+ 7: g
+ 8: h
+ 9: i
+10: j
+11: k
+12: cd
+ abcdefghijkkkkcda2
+ 0: abcdefghijkkkkcda2
+ 1: a
+ 2: b
+ 3: c
+ 4: d
+ 5: e
+ 6: f
+ 7: g
+ 8: h
+ 9: i
+10: j
+11: k
+12: cd
+
+/(cat(a(ract|tonic)|erpillar)) \1()2(3)/
+ cataract cataract23
+ 0: cataract cataract23
+ 1: cataract
+ 2: aract
+ 3: ract
+ 4:
+ 5: 3
+ catatonic catatonic23
+ 0: catatonic catatonic23
+ 1: catatonic
+ 2: atonic
+ 3: tonic
+ 4:
+ 5: 3
+ caterpillar caterpillar23
+ 0: caterpillar caterpillar23
+ 1: caterpillar
+ 2: erpillar
+ 3: <unset>
+ 4:
+ 5: 3
+
+
+/^From +([^ ]+) +[a-zA-Z][a-zA-Z][a-zA-Z] +[a-zA-Z][a-zA-Z][a-zA-Z] +[0-9]?[0-9] +[0-9][0-9]:[0-9][0-9]/
+ From abcd Mon Sep 01 12:33:02 1997
+ 0: From abcd Mon Sep 01 12:33
+ 1: abcd
+
+/^From\s+\S+\s+([a-zA-Z]{3}\s+){2}\d{1,2}\s+\d\d:\d\d/
+ From abcd Mon Sep 01 12:33:02 1997
+ 0: From abcd Mon Sep 01 12:33
+ 1: Sep
+ From abcd Mon Sep 1 12:33:02 1997
+ 0: From abcd Mon Sep 1 12:33
+ 1: Sep
+ *** Failers
+No match
+ From abcd Sep 01 12:33:02 1997
+No match
+
+/^12.34/s
+ 12\n34
+ 0: 12\x0a34
+ 12\r34
+ 0: 12\x0d34
+
+/\w+(?=\t)/
+ the quick brown\t fox
+ 0: brown
+
+/foo(?!bar)(.*)/
+ foobar is foolish see?
+ 0: foolish see?
+ 1: lish see?
+
+/(?:(?!foo)...|^.{0,2})bar(.*)/
+ foobar crowbar etc
+ 0: rowbar etc
+ 1: etc
+ barrel
+ 0: barrel
+ 1: rel
+ 2barrel
+ 0: 2barrel
+ 1: rel
+ A barrel
+ 0: A barrel
+ 1: rel
+
+/^(\D*)(?=\d)(?!123)/
+ abc456
+ 0: abc
+ 1: abc
+ *** Failers
+No match
+ abc123
+No match
+
+/^1234(?# test newlines
+ inside)/
+ 1234
+ 0: 1234
+
+/^1234 #comment in extended re
+ /x
+ 1234
+ 0: 1234
+
+/#rhubarb
+ abcd/x
+ abcd
+ 0: abcd
+
+/^abcd#rhubarb/x
+ abcd
+ 0: abcd
+
+/^(a)\1{2,3}(.)/
+ aaab
+ 0: aaab
+ 1: a
+ 2: b
+ aaaab
+ 0: aaaab
+ 1: a
+ 2: b
+ aaaaab
+ 0: aaaaa
+ 1: a
+ 2: a
+ aaaaaab
+ 0: aaaaa
+ 1: a
+ 2: a
+
+/(?!^)abc/
+ the abc
+ 0: abc
+ *** Failers
+No match
+ abc
+No match
+
+/(?=^)abc/
+ abc
+ 0: abc
+ *** Failers
+No match
+ the abc
+No match
+
+/^[ab]{1,3}(ab*|b)/
+ aabbbbb
+ 0: aabb
+ 1: b
+
+/^[ab]{1,3}?(ab*|b)/
+ aabbbbb
+ 0: aabbbbb
+ 1: abbbbb
+
+/^[ab]{1,3}?(ab*?|b)/
+ aabbbbb
+ 0: aa
+ 1: a
+
+/^[ab]{1,3}(ab*?|b)/
+ aabbbbb
+ 0: aabb
+ 1: b
+
+/ (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* # optional leading comment
+(?: (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+" (?: # opening quote...
+[^\\\x80-\xff\n\015"] # Anything except backslash and quote
+| # or
+\\ [^\x80-\xff] # Escaped something (something != CR)
+)* " # closing quote
+) # initial word
+(?: (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* \. (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+" (?: # opening quote...
+[^\\\x80-\xff\n\015"] # Anything except backslash and quote
+| # or
+\\ [^\x80-\xff] # Escaped something (something != CR)
+)* " # closing quote
+) )* # further okay, if led by a period
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* @ (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+| \[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+) # initial subdomain
+(?: #
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* \. # if led by a period...
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+| \[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+) # ...further okay
+)*
+# address
+| # or
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+" (?: # opening quote...
+[^\\\x80-\xff\n\015"] # Anything except backslash and quote
+| # or
+\\ [^\x80-\xff] # Escaped something (something != CR)
+)* " # closing quote
+) # one word, optionally followed by....
+(?:
+[^()<>@,;:".\\\[\]\x80-\xff\000-\010\012-\037] | # atom and space parts, or...
+\(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) | # comments, or...
+
+" (?: # opening quote...
+[^\\\x80-\xff\n\015"] # Anything except backslash and quote
+| # or
+\\ [^\x80-\xff] # Escaped something (something != CR)
+)* " # closing quote
+# quoted strings
+)*
+< (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* # leading <
+(?: @ (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+| \[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+) # initial subdomain
+(?: #
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* \. # if led by a period...
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+| \[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+) # ...further okay
+)*
+
+(?: (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* , (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* @ (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+| \[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+) # initial subdomain
+(?: #
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* \. # if led by a period...
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+| \[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+) # ...further okay
+)*
+)* # further okay, if led by comma
+: # closing colon
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* )? # optional route
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+" (?: # opening quote...
+[^\\\x80-\xff\n\015"] # Anything except backslash and quote
+| # or
+\\ [^\x80-\xff] # Escaped something (something != CR)
+)* " # closing quote
+) # initial word
+(?: (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* \. (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+" (?: # opening quote...
+[^\\\x80-\xff\n\015"] # Anything except backslash and quote
+| # or
+\\ [^\x80-\xff] # Escaped something (something != CR)
+)* " # closing quote
+) )* # further okay, if led by a period
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* @ (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+| \[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+) # initial subdomain
+(?: #
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* \. # if led by a period...
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* (?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+| \[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+) # ...further okay
+)*
+# address spec
+(?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* > # trailing >
+# name and address
+) (?: [\040\t] | \(
+(?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] | \( (?: [^\\\x80-\xff\n\015()] | \\ [^\x80-\xff] )* \) )*
+\) )* # optional trailing comment
+/x
+ Alan Other <user\@dom.ain>
+ 0: Alan Other <user@dom.ain>
+ <user\@dom.ain>
+ 0: user@dom.ain
+ user\@dom.ain
+ 0: user@dom.ain
+ \"A. Other\" <user.1234\@dom.ain> (a comment)
+ 0: "A. Other" <user.1234@dom.ain> (a comment)
+ A. Other <user.1234\@dom.ain> (a comment)
+ 0: Other <user.1234@dom.ain> (a comment)
+ \"/s=user/ou=host/o=place/prmd=uu.yy/admd= /c=gb/\"\@x400-re.lay
+ 0: "/s=user/ou=host/o=place/prmd=uu.yy/admd= /c=gb/"@x400-re.lay
+ A missing angle <user\@some.where
+ 0: user@some.where
+ *** Failers
+No match
+ The quick brown fox
+No match
+
+/[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional leading comment
+(?:
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+# Atom
+| # or
+" # "
+[^\\\x80-\xff\n\015"] * # normal
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015"] * )* # ( special normal* )*
+" # "
+# Quoted string
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+\.
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+# Atom
+| # or
+" # "
+[^\\\x80-\xff\n\015"] * # normal
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015"] * )* # ( special normal* )*
+" # "
+# Quoted string
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# additional words
+)*
+@
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+\[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+(?:
+\.
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+\[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+)*
+# address
+| # or
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+# Atom
+| # or
+" # "
+[^\\\x80-\xff\n\015"] * # normal
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015"] * )* # ( special normal* )*
+" # "
+# Quoted string
+)
+# leading word
+[^()<>@,;:".\\\[\]\x80-\xff\000-\010\012-\037] * # "normal" atoms and or spaces
+(?:
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+|
+" # "
+[^\\\x80-\xff\n\015"] * # normal
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015"] * )* # ( special normal* )*
+" # "
+) # "special" comment or quoted string
+[^()<>@,;:".\\\[\]\x80-\xff\000-\010\012-\037] * # more "normal"
+)*
+<
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# <
+(?:
+@
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+\[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+(?:
+\.
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+\[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+)*
+(?: ,
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+@
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+\[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+(?:
+\.
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+\[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+)*
+)* # additional domains
+:
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+)? # optional route
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+# Atom
+| # or
+" # "
+[^\\\x80-\xff\n\015"] * # normal
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015"] * )* # ( special normal* )*
+" # "
+# Quoted string
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+\.
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+# Atom
+| # or
+" # "
+[^\\\x80-\xff\n\015"] * # normal
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015"] * )* # ( special normal* )*
+" # "
+# Quoted string
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# additional words
+)*
+@
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+\[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+(?:
+\.
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+(?:
+[^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]+ # some number of atom characters...
+(?![^(\040)<>@,;:".\\\[\]\000-\037\x80-\xff]) # ..not followed by something that could be part of an atom
+|
+\[ # [
+(?: [^\\\x80-\xff\n\015\[\]] | \\ [^\x80-\xff] )* # stuff
+\] # ]
+)
+[\040\t]* # Nab whitespace.
+(?:
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: # (
+(?: \\ [^\x80-\xff] |
+\( # (
+[^\\\x80-\xff\n\015()] * # normal*
+(?: \\ [^\x80-\xff] [^\\\x80-\xff\n\015()] * )* # (special normal*)*
+\) # )
+) # special
+[^\\\x80-\xff\n\015()] * # normal*
+)* # )*
+\) # )
+[\040\t]* )* # If comment found, allow more spaces.
+# optional trailing comments
+)*
+# address spec
+> # >
+# name and address
+)
+/x
+ Alan Other <user\@dom.ain>
+ 0: Alan Other <user@dom.ain>
+ <user\@dom.ain>
+ 0: user@dom.ain
+ user\@dom.ain
+ 0: user@dom.ain
+ \"A. Other\" <user.1234\@dom.ain> (a comment)
+ 0: "A. Other" <user.1234@dom.ain>
+ A. Other <user.1234\@dom.ain> (a comment)
+ 0: Other <user.1234@dom.ain>
+ \"/s=user/ou=host/o=place/prmd=uu.yy/admd= /c=gb/\"\@x400-re.lay
+ 0: "/s=user/ou=host/o=place/prmd=uu.yy/admd= /c=gb/"@x400-re.lay
+ A missing angle <user\@some.where
+ 0: user@some.where
+ *** Failers
+No match
+ The quick brown fox
+No match
+
+/abc\0def\00pqr\000xyz\0000AB/
+ abc\0def\00pqr\000xyz\0000AB
+ 0: abc\x00def\x00pqr\x00xyz\x000AB
+ abc456 abc\0def\00pqr\000xyz\0000ABCDE
+ 0: abc\x00def\x00pqr\x00xyz\x000AB
+
+/abc\x0def\x00pqr\x000xyz\x0000AB/
+ abc\x0def\x00pqr\x000xyz\x0000AB
+ 0: abc\x0def\x00pqr\x000xyz\x0000AB
+ abc456 abc\x0def\x00pqr\x000xyz\x0000ABCDE
+ 0: abc\x0def\x00pqr\x000xyz\x0000AB
+
+/^[\000-\037]/
+ \0A
+ 0: \x00
+ \01B
+ 0: \x01
+ \037C
+ 0: \x1f
+
+/\0*/
+ \0\0\0\0
+ 0: \x00\x00\x00\x00
+
+/A\x0{2,3}Z/
+ The A\x0\x0Z
+ 0: A\x00\x00Z
+ An A\0\x0\0Z
+ 0: A\x00\x00\x00Z
+ *** Failers
+No match
+ A\0Z
+No match
+ A\0\x0\0\x0Z
+No match
+
+/^(cow|)\1(bell)/
+ cowcowbell
+ 0: cowcowbell
+ 1: cow
+ 2: bell
+ bell
+ 0: bell
+ 1:
+ 2: bell
+ *** Failers
+No match
+ cowbell
+No match
+
+/^\s/
+ \040abc
+ 0:
+ \x0cabc
+ 0: \x0c
+ \nabc
+ 0: \x0a
+ \rabc
+ 0: \x0d
+ \tabc
+ 0: \x09
+ *** Failers
+No match
+ abc
+No match
+
+/^a b
+
+ \f c/x
+ abc
+ 0: abc
+
+/^(a|)\1*b/
+ ab
+ 0: ab
+ 1: a
+ aaaab
+ 0: aaaab
+ 1: a
+ b
+ 0: b
+ 1:
+ *** Failers
+No match
+ acb
+No match
+
+/^(a|)\1+b/
+ aab
+ 0: aab
+ 1: a
+ aaaab
+ 0: aaaab
+ 1: a
+ b
+ 0: b
+ 1:
+ *** Failers
+No match
+ ab
+No match
+
+/^(a|)\1?b/
+ ab
+ 0: ab
+ 1: a
+ aab
+ 0: aab
+ 1: a
+ b
+ 0: b
+ 1:
+ *** Failers
+No match
+ acb
+No match
+
+/^(a|)\1{2}b/
+ aaab
+ 0: aaab
+ 1: a
+ b
+ 0: b
+ 1:
+ *** Failers
+No match
+ ab
+No match
+ aab
+No match
+ aaaab
+No match
+
+/^(a|)\1{2,3}b/
+ aaab
+ 0: aaab
+ 1: a
+ aaaab
+ 0: aaaab
+ 1: a
+ b
+ 0: b
+ 1:
+ *** Failers
+No match
+ ab
+No match
+ aab
+No match
+ aaaaab
+No match
+
+/ab{1,3}bc/
+ abbbbc
+ 0: abbbbc
+ abbbc
+ 0: abbbc
+ abbc
+ 0: abbc
+ *** Failers
+No match
+ abc
+No match
+ abbbbbc
+No match
+
+/([^.]*)\.([^:]*):[T ]+(.*)/
+ track1.title:TBlah blah blah
+ 0: track1.title:TBlah blah blah
+ 1: track1
+ 2: title
+ 3: Blah blah blah
+
+/([^.]*)\.([^:]*):[T ]+(.*)/i
+ track1.title:TBlah blah blah
+ 0: track1.title:TBlah blah blah
+ 1: track1
+ 2: title
+ 3: Blah blah blah
+
+/([^.]*)\.([^:]*):[t ]+(.*)/i
+ track1.title:TBlah blah blah
+ 0: track1.title:TBlah blah blah
+ 1: track1
+ 2: title
+ 3: Blah blah blah
+
+/^[W-c]+$/
+ WXY_^abc
+ 0: WXY_^abc
+ ***Failers
+No match
+ wxy
+No match
+
+/^[W-c]+$/i
+ WXY_^abc
+ 0: WXY_^abc
+ wxy_^ABC
+ 0: wxy_^ABC
+
+/^[\x3f-\x5F]+$/i
+ WXY_^abc
+ 0: WXY_^abc
+ wxy_^ABC
+ 0: wxy_^ABC
+
+/^abc$/m
+ abc
+ 0: abc
+ qqq\nabc
+ 0: abc
+ abc\nzzz
+ 0: abc
+ qqq\nabc\nzzz
+ 0: abc
+
+/^abc$/
+ abc
+ 0: abc
+ *** Failers
+No match
+ qqq\nabc
+No match
+ abc\nzzz
+No match
+ qqq\nabc\nzzz
+No match
+
+/\Aabc\Z/m
+ abc
+ 0: abc
+ abc\n
+ 0: abc
+ *** Failers
+No match
+ qqq\nabc
+No match
+ abc\nzzz
+No match
+ qqq\nabc\nzzz
+No match
+
+/\A(.)*\Z/s
+ abc\ndef
+ 0: abc\x0adef
+ 1: f
+
+/\A(.)*\Z/m
+ *** Failers
+ 0: *** Failers
+ 1: s
+ abc\ndef
+No match
+
+/(?:b)|(?::+)/
+ b::c
+ 0: b
+ c::b
+ 0: ::
+
+/[-az]+/
+ az-
+ 0: az-
+ *** Failers
+ 0: a
+ b
+No match
+
+/[az-]+/
+ za-
+ 0: za-
+ *** Failers
+ 0: a
+ b
+No match
+
+/[a\-z]+/
+ a-z
+ 0: a-z
+ *** Failers
+ 0: a
+ b
+No match
+
+/[a-z]+/
+ abcdxyz
+ 0: abcdxyz
+
+/[\d-]+/
+ 12-34
+ 0: 12-34
+ *** Failers
+No match
+ aaa
+No match
+
+/[\d-z]+/
+ 12-34z
+ 0: 12-34z
+ *** Failers
+No match
+ aaa
+No match
+
+/\x5c/
+ \\
+ 0: \
+
+/\x20Z/
+ the Zoo
+ 0: Z
+ *** Failers
+No match
+ Zulu
+No match
+
+/(abc)\1/i
+ abcabc
+ 0: abcabc
+ 1: abc
+ ABCabc
+ 0: ABCabc
+ 1: ABC
+ abcABC
+ 0: abcABC
+ 1: abc
+
+/(main(O)?)+/
+ mainmain
+ 0: mainmain
+ 1: main
+ mainOmain
+ 0: mainOmain
+ 1: main
+ 2: O
+
+/ab{3cd/
+ ab{3cd
+ 0: ab{3cd
+
+/ab{3,cd/
+ ab{3,cd
+ 0: ab{3,cd
+
+/ab{3,4a}cd/
+ ab{3,4a}cd
+ 0: ab{3,4a}cd
+
+/{4,5a}bc/
+ {4,5a}bc
+ 0: {4,5a}bc
+
+/^a.b/
+ a\rb
+ 0: a\x0db
+ *** Failers
+No match
+ a\nb
+No match
+
+/abc$/
+ abc
+ 0: abc
+ abc\n
+ 0: abc
+ *** Failers
+No match
+ abc\ndef
+No match
+
+/(abc)\123/
+ abc\x53
+ 0: abcS
+ 1: abc
+
+/(abc)\223/
+ abc\x93
+ 0: abc\x93
+ 1: abc
+
+/(abc)\323/
+ abc\xd3
+ 0: abc\xd3
+ 1: abc
+
+/(abc)\500/
+ abc\x40
+ 0: abc@
+ 1: abc
+ abc\100
+ 0: abc@
+ 1: abc
+
+/(abc)\5000/
+ abc\x400
+ 0: abc@0
+ 1: abc
+ abc\x40\x30
+ 0: abc@0
+ 1: abc
+ abc\1000
+ 0: abc@0
+ 1: abc
+ abc\100\x30
+ 0: abc@0
+ 1: abc
+ abc\100\060
+ 0: abc@0
+ 1: abc
+ abc\100\60
+ 0: abc@0
+ 1: abc
+
+/abc\81/
+ abc\081
+ 0: abc\x0081
+ abc\0\x38\x31
+ 0: abc\x0081
+
+/abc\91/
+ abc\091
+ 0: abc\x0091
+ abc\0\x39\x31
+ 0: abc\x0091
+
+/(a)(b)(c)(d)(e)(f)(g)(h)(i)(j)(k)(l)\12\123/
+ abcdefghijkllS
+ 0: abcdefghijkllS
+ 1: a
+ 2: b
+ 3: c
+ 4: d
+ 5: e
+ 6: f
+ 7: g
+ 8: h
+ 9: i
+10: j
+11: k
+12: l
+
+/(a)(b)(c)(d)(e)(f)(g)(h)(i)(j)(k)\12\123/
+ abcdefghijk\12S
+ 0: abcdefghijk\x0aS
+ 1: a
+ 2: b
+ 3: c
+ 4: d
+ 5: e
+ 6: f
+ 7: g
+ 8: h
+ 9: i
+10: j
+11: k
+
+/ab\gdef/
+ abgdef
+ 0: abgdef
+
+/a{0}bc/
+ bc
+ 0: bc
+
+/(a|(bc)){0,0}?xyz/
+ xyz
+ 0: xyz
+
+/abc[\10]de/
+ abc\010de
+ 0: abc\x08de
+
+/abc[\1]de/
+ abc\1de
+ 0: abc\x01de
+
+/(abc)[\1]de/
+ abc\1de
+ 0: abc\x01de
+ 1: abc
+
+/a.b(?s)/
+ a\nb
+ 0: a\x0ab
+
+/^([^a])([^\b])([^c]*)([^d]{3,4})/
+ baNOTccccd
+ 0: baNOTcccc
+ 1: b
+ 2: a
+ 3: NOT
+ 4: cccc
+ baNOTcccd
+ 0: baNOTccc
+ 1: b
+ 2: a
+ 3: NOT
+ 4: ccc
+ baNOTccd
+ 0: baNOTcc
+ 1: b
+ 2: a
+ 3: NO
+ 4: Tcc
+ bacccd
+ 0: baccc
+ 1: b
+ 2: a
+ 3:
+ 4: ccc
+ *** Failers
+ 0: *** Failers
+ 1: *
+ 2: *
+ 3: * Fail
+ 4: ers
+ anything
+No match
+ b\bc
+No match
+ baccd
+No match
+
+/[^a]/
+ Abc
+ 0: A
+
+/[^a]/i
+ Abc
+ 0: b
+
+/[^a]+/
+ AAAaAbc
+ 0: AAA
+
+/[^a]+/i
+ AAAaAbc
+ 0: bc
+
+/[^a]+/
+ bbb\nccc
+ 0: bbb\x0accc
+
+/[^k]$/
+ abc
+ 0: c
+ *** Failers
+ 0: s
+ abk
+No match
+
+/[^k]{2,3}$/
+ abc
+ 0: abc
+ kbc
+ 0: bc
+ kabc
+ 0: abc
+ *** Failers
+ 0: ers
+ abk
+No match
+ akb
+No match
+ akk
+No match
+
+/^\d{8,}\@.+[^k]$/
+ 12345678\@a.b.c.d
+ 0: 12345678@a.b.c.d
+ 123456789\@x.y.z
+ 0: 123456789@x.y.z
+ *** Failers
+No match
+ 12345678\@x.y.uk
+No match
+ 1234567\@a.b.c.d
+No match
+
+/(a)\1{8,}/
+ aaaaaaaaa
+ 0: aaaaaaaaa
+ 1: a
+ aaaaaaaaaa
+ 0: aaaaaaaaaa
+ 1: a
+ *** Failers
+No match
+ aaaaaaa
+No match
+
+/[^a]/
+ aaaabcd
+ 0: b
+ aaAabcd
+ 0: A
+
+/[^a]/i
+ aaaabcd
+ 0: b
+ aaAabcd
+ 0: b
+
+/[^az]/
+ aaaabcd
+ 0: b
+ aaAabcd
+ 0: A
+
+/[^az]/i
+ aaaabcd
+ 0: b
+ aaAabcd
+ 0: b
+
+/\000\001\002\003\004\005\006\007\010\011\012\013\014\015\016\017\020\021\022\023\024\025\026\027\030\031\032\033\034\035\036\037\040\041\042\043\044\045\046\047\050\051\052\053\054\055\056\057\060\061\062\063\064\065\066\067\070\071\072\073\074\075\076\077\100\101\102\103\104\105\106\107\110\111\112\113\114\115\116\117\120\121\122\123\124\125\126\127\130\131\132\133\134\135\136\137\140\141\142\143\144\145\146\147\150\151\152\153\154\155\156\157\160\161\162\163\164\165\166\167\170\171\172\173\174\175\176\177\200\201\202\203\204\205\206\207\210\211\212\213\214\215\216\217\220\221\222\223\224\225\226\227\230\231\232\233\234\235\236\237\240\241\242\243\244\245\246\247\250\251\252\253\254\255\256\257\260\261\262\263\264\265\266\267\270\271\272\273\274\275\276\277\300\301\302\303\304\305\306\307\310\311\312\313\314\315\316\317\320\321\322\323\324\325\326\327\330\331\332\333\334\335\336\337\340\341\342\343\344\345\346\347\350\351\352\353\354\355\356\357\360\361\362\363\364\365\366\367\370\371\372\373\374\375\376\377/
+ \000\001\002\003\004\005\006\007\010\011\012\013\014\015\016\017\020\021\022\023\024\025\026\027\030\031\032\033\034\035\036\037\040\041\042\043\044\045\046\047\050\051\052\053\054\055\056\057\060\061\062\063\064\065\066\067\070\071\072\073\074\075\076\077\100\101\102\103\104\105\106\107\110\111\112\113\114\115\116\117\120\121\122\123\124\125\126\127\130\131\132\133\134\135\136\137\140\141\142\143\144\145\146\147\150\151\152\153\154\155\156\157\160\161\162\163\164\165\166\167\170\171\172\173\174\175\176\177\200\201\202\203\204\205\206\207\210\211\212\213\214\215\216\217\220\221\222\223\224\225\226\227\230\231\232\233\234\235\236\237\240\241\242\243\244\245\246\247\250\251\252\253\254\255\256\257\260\261\262\263\264\265\266\267\270\271\272\273\274\275\276\277\300\301\302\303\304\305\306\307\310\311\312\313\314\315\316\317\320\321\322\323\324\325\326\327\330\331\332\333\334\335\336\337\340\341\342\343\344\345\346\347\350\351\352\353\354\355\356\357\360\361\362\363\364\365\366\367\370\371\372\373\374\375\376\377
+ 0: \x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~\x7f\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff
+
+/P[^*]TAIRE[^*]{1,6}?LL/
+ xxxxxxxxxxxPSTAIREISLLxxxxxxxxx
+ 0: PSTAIREISLL
+
+/P[^*]TAIRE[^*]{1,}?LL/
+ xxxxxxxxxxxPSTAIREISLLxxxxxxxxx
+ 0: PSTAIREISLL
+
+/(\.\d\d[1-9]?)\d+/
+ 1.230003938
+ 0: .230003938
+ 1: .23
+ 1.875000282
+ 0: .875000282
+ 1: .875
+ 1.235
+ 0: .235
+ 1: .23
+
+/(\.\d\d((?=0)|\d(?=\d)))/
+ 1.230003938
+ 0: .23
+ 1: .23
+ 2:
+ 1.875000282
+ 0: .875
+ 1: .875
+ 2: 5
+ *** Failers
+No match
+ 1.235
+No match
+
+/a(?)b/
+ ab
+ 0: ab
+
+/\b(foo)\s+(\w+)/i
+ Food is on the foo table
+ 0: foo table
+ 1: foo
+ 2: table
+
+/foo(.*)bar/
+ The food is under the bar in the barn.
+ 0: food is under the bar in the bar
+ 1: d is under the bar in the
+
+/foo(.*?)bar/
+ The food is under the bar in the barn.
+ 0: food is under the bar
+ 1: d is under the
+
+/(.*)(\d*)/
+ I have 2 numbers: 53147
+ 0: I have 2 numbers: 53147
+ 1: I have 2 numbers: 53147
+ 2:
+
+/(.*)(\d+)/
+ I have 2 numbers: 53147
+ 0: I have 2 numbers: 53147
+ 1: I have 2 numbers: 5314
+ 2: 7
+
+/(.*?)(\d*)/
+ I have 2 numbers: 53147
+ 0:
+ 1:
+ 2:
+
+/(.*?)(\d+)/
+ I have 2 numbers: 53147
+ 0: I have 2
+ 1: I have
+ 2: 2
+
+/(.*)(\d+)$/
+ I have 2 numbers: 53147
+ 0: I have 2 numbers: 53147
+ 1: I have 2 numbers: 5314
+ 2: 7
+
+/(.*?)(\d+)$/
+ I have 2 numbers: 53147
+ 0: I have 2 numbers: 53147
+ 1: I have 2 numbers:
+ 2: 53147
+
+/(.*)\b(\d+)$/
+ I have 2 numbers: 53147
+ 0: I have 2 numbers: 53147
+ 1: I have 2 numbers:
+ 2: 53147
+
+/(.*\D)(\d+)$/
+ I have 2 numbers: 53147
+ 0: I have 2 numbers: 53147
+ 1: I have 2 numbers:
+ 2: 53147
+
+/^\D*(?!123)/
+ ABC123
+ 0: AB
+
+/^(\D*)(?=\d)(?!123)/
+ ABC445
+ 0: ABC
+ 1: ABC
+ *** Failers
+No match
+ ABC123
+No match
+
+/^[W-]46]/
+ W46]789
+ 0: W46]
+ -46]789
+ 0: -46]
+ *** Failers
+No match
+ Wall
+No match
+ Zebra
+No match
+ 42
+No match
+ [abcd]
+No match
+ ]abcd[
+No match
+
+/^[W-\]46]/
+ W46]789
+ 0: W
+ Wall
+ 0: W
+ Zebra
+ 0: Z
+ Xylophone
+ 0: X
+ 42
+ 0: 4
+ [abcd]
+ 0: [
+ ]abcd[
+ 0: ]
+ \\backslash
+ 0: \
+ *** Failers
+No match
+ -46]789
+No match
+ well
+No match
+
+/\d\d\/\d\d\/\d\d\d\d/
+ 01/01/2000
+ 0: 01/01/2000
+
+/word (?:[a-zA-Z0-9]+ ){0,10}otherword/
+ word cat dog elephant mussel cow horse canary baboon snake shark otherword
+ 0: word cat dog elephant mussel cow horse canary baboon snake shark otherword
+ word cat dog elephant mussel cow horse canary baboon snake shark
+No match
+
+/word (?:[a-zA-Z0-9]+ ){0,300}otherword/
+ word cat dog elephant mussel cow horse canary baboon snake shark the quick brown fox and the lazy dog and several other words getting close to thirty by now I hope
+No match
+
+/^(a){0,0}/
+ bcd
+ 0:
+ abc
+ 0:
+ aab
+ 0:
+
+/^(a){0,1}/
+ bcd
+ 0:
+ abc
+ 0: a
+ 1: a
+ aab
+ 0: a
+ 1: a
+
+/^(a){0,2}/
+ bcd
+ 0:
+ abc
+ 0: a
+ 1: a
+ aab
+ 0: aa
+ 1: a
+
+/^(a){0,3}/
+ bcd
+ 0:
+ abc
+ 0: a
+ 1: a
+ aab
+ 0: aa
+ 1: a
+ aaa
+ 0: aaa
+ 1: a
+
+/^(a){0,}/
+ bcd
+ 0:
+ abc
+ 0: a
+ 1: a
+ aab
+ 0: aa
+ 1: a
+ aaa
+ 0: aaa
+ 1: a
+ aaaaaaaa
+ 0: aaaaaaaa
+ 1: a
+
+/^(a){1,1}/
+ bcd
+No match
+ abc
+ 0: a
+ 1: a
+ aab
+ 0: a
+ 1: a
+
+/^(a){1,2}/
+ bcd
+No match
+ abc
+ 0: a
+ 1: a
+ aab
+ 0: aa
+ 1: a
+
+/^(a){1,3}/
+ bcd
+No match
+ abc
+ 0: a
+ 1: a
+ aab
+ 0: aa
+ 1: a
+ aaa
+ 0: aaa
+ 1: a
+
+/^(a){1,}/
+ bcd
+No match
+ abc
+ 0: a
+ 1: a
+ aab
+ 0: aa
+ 1: a
+ aaa
+ 0: aaa
+ 1: a
+ aaaaaaaa
+ 0: aaaaaaaa
+ 1: a
+
+/.*\.gif/
+ borfle\nbib.gif\nno
+ 0: bib.gif
+
+/.{0,}\.gif/
+ borfle\nbib.gif\nno
+ 0: bib.gif
+
+/.*\.gif/m
+ borfle\nbib.gif\nno
+ 0: bib.gif
+
+/.*\.gif/s
+ borfle\nbib.gif\nno
+ 0: borfle\x0abib.gif
+
+/.*\.gif/ms
+ borfle\nbib.gif\nno
+ 0: borfle\x0abib.gif
+
+/.*$/
+ borfle\nbib.gif\nno
+ 0: no
+
+/.*$/m
+ borfle\nbib.gif\nno
+ 0: borfle
+
+/.*$/s
+ borfle\nbib.gif\nno
+ 0: borfle\x0abib.gif\x0ano
+
+/.*$/ms
+ borfle\nbib.gif\nno
+ 0: borfle\x0abib.gif\x0ano
+
+/.*$/
+ borfle\nbib.gif\nno\n
+ 0: no
+
+/.*$/m
+ borfle\nbib.gif\nno\n
+ 0: borfle
+
+/.*$/s
+ borfle\nbib.gif\nno\n
+ 0: borfle\x0abib.gif\x0ano\x0a
+
+/.*$/ms
+ borfle\nbib.gif\nno\n
+ 0: borfle\x0abib.gif\x0ano\x0a
+
+/(.*X|^B)/
+ abcde\n1234Xyz
+ 0: 1234X
+ 1: 1234X
+ BarFoo
+ 0: B
+ 1: B
+ *** Failers
+No match
+ abcde\nBar
+No match
+
+/(.*X|^B)/m
+ abcde\n1234Xyz
+ 0: 1234X
+ 1: 1234X
+ BarFoo
+ 0: B
+ 1: B
+ abcde\nBar
+ 0: B
+ 1: B
+
+/(.*X|^B)/s
+ abcde\n1234Xyz
+ 0: abcde\x0a1234X
+ 1: abcde\x0a1234X
+ BarFoo
+ 0: B
+ 1: B
+ *** Failers
+No match
+ abcde\nBar
+No match
+
+/(.*X|^B)/ms
+ abcde\n1234Xyz
+ 0: abcde\x0a1234X
+ 1: abcde\x0a1234X
+ BarFoo
+ 0: B
+ 1: B
+ abcde\nBar
+ 0: B
+ 1: B
+
+/(?s)(.*X|^B)/
+ abcde\n1234Xyz
+ 0: abcde\x0a1234X
+ 1: abcde\x0a1234X
+ BarFoo
+ 0: B
+ 1: B
+ *** Failers
+No match
+ abcde\nBar
+No match
+
+/(?s:.*X|^B)/
+ abcde\n1234Xyz
+ 0: abcde\x0a1234X
+ BarFoo
+ 0: B
+ *** Failers
+No match
+ abcde\nBar
+No match
+
+/^.*B/
+ **** Failers
+No match
+ abc\nB
+No match
+
+/(?s)^.*B/
+ abc\nB
+ 0: abc\x0aB
+
+/(?m)^.*B/
+ abc\nB
+ 0: B
+
+/(?ms)^.*B/
+ abc\nB
+ 0: abc\x0aB
+
+/(?ms)^B/
+ abc\nB
+ 0: B
+
+/(?s)B$/
+ B\n
+ 0: B
+
+/^[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]/
+ 123456654321
+ 0: 123456654321
+
+/^\d\d\d\d\d\d\d\d\d\d\d\d/
+ 123456654321
+ 0: 123456654321
+
+/^[\d][\d][\d][\d][\d][\d][\d][\d][\d][\d][\d][\d]/
+ 123456654321
+ 0: 123456654321
+
+/^[abc]{12}/
+ abcabcabcabc
+ 0: abcabcabcabc
+
+/^[a-c]{12}/
+ abcabcabcabc
+ 0: abcabcabcabc
+
+/^(a|b|c){12}/
+ abcabcabcabc
+ 0: abcabcabcabc
+ 1: c
+
+/^[abcdefghijklmnopqrstuvwxy0123456789]/
+ n
+ 0: n
+ *** Failers
+No match
+ z
+No match
+
+/abcde{0,0}/
+ abcd
+ 0: abcd
+ *** Failers
+No match
+ abce
+No match
+
+/ab[cd]{0,0}e/
+ abe
+ 0: abe
+ *** Failers
+No match
+ abcde
+No match
+
+/ab(c){0,0}d/
+ abd
+ 0: abd
+ *** Failers
+No match
+ abcd
+No match
+
+/a(b*)/
+ a
+ 0: a
+ 1:
+ ab
+ 0: ab
+ 1: b
+ abbbb
+ 0: abbbb
+ 1: bbbb
+ *** Failers
+ 0: a
+ 1:
+ bbbbb
+No match
+
+/ab\d{0}e/
+ abe
+ 0: abe
+ *** Failers
+No match
+ ab1e
+No match
+
+/"([^\\"]+|\\.)*"/
+ the \"quick\" brown fox
+ 0: "quick"
+ 1: quick
+ \"the \\\"quick\\\" brown fox\"
+ 0: "the \"quick\" brown fox"
+ 1: brown fox
+
+/.*?/g+
+ abc
+ 0:
+ 0+ abc
+ 0: a
+ 0+ bc
+ 0:
+ 0+ bc
+ 0: b
+ 0+ c
+ 0:
+ 0+ c
+ 0: c
+ 0+
+ 0:
+ 0+
+
+/\b/g+
+ abc
+ 0:
+ 0+ abc
+ 0:
+ 0+
+
+/\b/+g
+ abc
+ 0:
+ 0+ abc
+ 0:
+ 0+
+
+//g
+ abc
+ 0:
+ 0:
+ 0:
+ 0:
+
+/ End of test input /
+
--- /dev/null
+PCRE version 3.1 09-Feb-2000
+
+/(a)b|/
+Capturing subpattern count = 1
+No options
+No first char
+No need char
+
+/abc/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+Need char = 'c'
+ abc
+ 0: abc
+ defabc
+ 0: abc
+ \Aabc
+ 0: abc
+ *** Failers
+No match
+ \Adefabc
+No match
+ ABC
+No match
+
+/^abc/
+Capturing subpattern count = 0
+Options: anchored
+No first char
+Need char = 'c'
+ abc
+ 0: abc
+ \Aabc
+ 0: abc
+ *** Failers
+No match
+ defabc
+No match
+ \Adefabc
+No match
+
+/a+bc/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+Need char = 'c'
+
+/a*bc/
+Capturing subpattern count = 0
+No options
+No first char
+Need char = 'c'
+
+/a{3}bc/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+Need char = 'c'
+
+/(abc|a+z)/
+Capturing subpattern count = 1
+No options
+First char = 'a'
+No need char
+
+/^abc$/
+Capturing subpattern count = 0
+Options: anchored
+No first char
+Need char = 'c'
+ abc
+ 0: abc
+ *** Failers
+No match
+ def\nabc
+No match
+
+/ab\gdef/X
+Failed: unrecognized character follows \ at offset 3
+
+/(?X)ab\gdef/X
+Failed: unrecognized character follows \ at offset 7
+
+/x{5,4}/
+Failed: numbers out of order in {} quantifier at offset 5
+
+/z{65536}/
+Failed: number too big in {} quantifier at offset 7
+
+/[abcd/
+Failed: missing terminating ] for character class at offset 5
+
+/[\B]/
+Failed: invalid escape sequence in character class at offset 2
+
+/[a-\w]/
+Failed: invalid escape sequence in character class at offset 4
+
+/[z-a]/
+Failed: range out of order in character class at offset 3
+
+/^*/
+Failed: nothing to repeat at offset 1
+
+/(abc/
+Failed: missing ) at offset 4
+
+/(?# abc/
+Failed: missing ) after comment at offset 7
+
+/(?z)abc/
+Failed: unrecognized character after (? at offset 2
+
+/.*b/
+Capturing subpattern count = 0
+No options
+First char at start or follows \n
+Need char = 'b'
+
+/.*?b/
+Capturing subpattern count = 0
+No options
+First char at start or follows \n
+Need char = 'b'
+
+/cat|dog|elephant/
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+ this sentence eventually mentions a cat
+ 0: cat
+ this sentences rambles on and on for a while and then reaches elephant
+ 0: elephant
+
+/cat|dog|elephant/S
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+Starting character set: c d e
+ this sentence eventually mentions a cat
+ 0: cat
+ this sentences rambles on and on for a while and then reaches elephant
+ 0: elephant
+
+/cat|dog|elephant/iS
+Capturing subpattern count = 0
+Options: caseless
+No first char
+No need char
+Starting character set: C D E c d e
+ this sentence eventually mentions a CAT cat
+ 0: CAT
+ this sentences rambles on and on for a while to elephant ElePhant
+ 0: elephant
+
+/a|[bcd]/S
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+Starting character set: a b c d
+
+/(a|[^\dZ])/S
+Capturing subpattern count = 1
+No options
+No first char
+No need char
+Starting character set: \x00 \x01 \x02 \x03 \x04 \x05 \x06 \x07 \x08 \x09 \x0a
+ \x0b \x0c \x0d \x0e \x0f \x10 \x11 \x12 \x13 \x14 \x15 \x16 \x17 \x18 \x19
+ \x1a \x1b \x1c \x1d \x1e \x1f \x20 ! " # $ % & ' ( ) * + , - . / : ; < = >
+ ? @ A B C D E F G H I J K L M N O P Q R S T U V W X Y [ \ ] ^ _ ` a b c d
+ e f g h i j k l m n o p q r s t u v w x y z { | } ~ \x7f \x80 \x81 \x82 \x83
+ \x84 \x85 \x86 \x87 \x88 \x89 \x8a \x8b \x8c \x8d \x8e \x8f \x90 \x91 \x92
+ \x93 \x94 \x95 \x96 \x97 \x98 \x99 \x9a \x9b \x9c \x9d \x9e \x9f \xa0 \xa1
+ \xa2 \xa3 \xa4 \xa5 \xa6 \xa7 \xa8 \xa9 \xaa \xab \xac \xad \xae \xaf \xb0
+ \xb1 \xb2 \xb3 \xb4 \xb5 \xb6 \xb7 \xb8 \xb9 \xba \xbb \xbc \xbd \xbe \xbf
+ \xc0 \xc1 \xc2 \xc3 \xc4 \xc5 \xc6 \xc7 \xc8 \xc9 \xca \xcb \xcc \xcd \xce
+ \xcf \xd0 \xd1 \xd2 \xd3 \xd4 \xd5 \xd6 \xd7 \xd8 \xd9 \xda \xdb \xdc \xdd
+ \xde \xdf \xe0 \xe1 \xe2 \xe3 \xe4 \xe5 \xe6 \xe7 \xe8 \xe9 \xea \xeb \xec
+ \xed \xee \xef \xf0 \xf1 \xf2 \xf3 \xf4 \xf5 \xf6 \xf7 \xf8 \xf9 \xfa \xfb
+ \xfc \xfd \xfe \xff
+
+/(a|b)*[\s]/S
+Capturing subpattern count = 1
+No options
+No first char
+No need char
+Starting character set: \x09 \x0a \x0b \x0c \x0d \x20 a b
+
+/(ab\2)/
+Failed: back reference to non-existent subpattern at offset 6
+
+/{4,5}abc/
+Failed: nothing to repeat at offset 4
+
+/(a)(b)(c)\2/
+Capturing subpattern count = 3
+Max back reference = 2
+No options
+First char = 'a'
+Need char = 'c'
+ abcb
+ 0: abcb
+ 1: a
+ 2: b
+ 3: c
+ \O0abcb
+Matched, but too many substrings
+ \O3abcb
+Matched, but too many substrings
+ 0: abcb
+ \O6abcb
+Matched, but too many substrings
+ 0: abcb
+ 1: a
+ \O9abcb
+Matched, but too many substrings
+ 0: abcb
+ 1: a
+ 2: b
+ \O12abcb
+ 0: abcb
+ 1: a
+ 2: b
+ 3: c
+
+/(a)bc|(a)(b)\2/
+Capturing subpattern count = 3
+Max back reference = 2
+No options
+First char = 'a'
+No need char
+ abc
+ 0: abc
+ 1: a
+ \O0abc
+Matched, but too many substrings
+ \O3abc
+Matched, but too many substrings
+ 0: abc
+ \O6abc
+ 0: abc
+ 1: a
+ aba
+ 0: aba
+ 1: <unset>
+ 2: a
+ 3: b
+ \O0aba
+Matched, but too many substrings
+ \O3aba
+Matched, but too many substrings
+ 0: aba
+ \O6aba
+Matched, but too many substrings
+ 0: aba
+ 1: <unset>
+ \O9aba
+Matched, but too many substrings
+ 0: aba
+ 1: <unset>
+ 2: a
+ \O12aba
+ 0: aba
+ 1: <unset>
+ 2: a
+ 3: b
+
+/abc$/E
+Capturing subpattern count = 0
+Options: dollar_endonly
+First char = 'a'
+Need char = 'c'
+ abc
+ 0: abc
+ *** Failers
+No match
+ abc\n
+No match
+ abc\ndef
+No match
+
+/(a)(b)(c)(d)(e)\6/
+Failed: back reference to non-existent subpattern at offset 17
+
+/the quick brown fox/
+Capturing subpattern count = 0
+No options
+First char = 't'
+Need char = 'x'
+ the quick brown fox
+ 0: the quick brown fox
+ this is a line with the quick brown fox
+ 0: the quick brown fox
+
+/the quick brown fox/A
+Capturing subpattern count = 0
+Options: anchored
+No first char
+Need char = 'x'
+ the quick brown fox
+ 0: the quick brown fox
+ *** Failers
+No match
+ this is a line with the quick brown fox
+No match
+
+/ab(?z)cd/
+Failed: unrecognized character after (? at offset 4
+
+/^abc|def/
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+ abcdef
+ 0: abc
+ abcdef\B
+ 0: def
+
+/.*((abc)$|(def))/
+Capturing subpattern count = 3
+No options
+First char at start or follows \n
+No need char
+ defabc
+ 0: defabc
+ 1: abc
+ 2: abc
+ \Zdefabc
+ 0: def
+ 1: def
+ 2: <unset>
+ 3: def
+
+/abc/P
+ abc
+ 0: abc
+ *** Failers
+No match: POSIX code 17: match failed
+
+/^abc|def/P
+ abcdef
+ 0: abc
+ abcdef\B
+ 0: def
+
+/.*((abc)$|(def))/P
+ defabc
+ 0: defabc
+ 1: abc
+ 2: abc
+ \Zdefabc
+ 0: def
+ 1: def
+ 3: def
+
+/the quick brown fox/P
+ the quick brown fox
+ 0: the quick brown fox
+ *** Failers
+No match: POSIX code 17: match failed
+ The Quick Brown Fox
+No match: POSIX code 17: match failed
+
+/the quick brown fox/Pi
+ the quick brown fox
+ 0: the quick brown fox
+ The Quick Brown Fox
+ 0: The Quick Brown Fox
+
+/abc.def/P
+ *** Failers
+No match: POSIX code 17: match failed
+ abc\ndef
+No match: POSIX code 17: match failed
+
+/abc$/P
+ abc
+ 0: abc
+ abc\n
+ 0: abc
+
+/(abc)\2/P
+Failed: POSIX code 15: bad back reference at offset 7
+
+/(abc\1)/P
+ abc
+No match: POSIX code 17: match failed
+
+/)/
+Failed: unmatched parentheses at offset 0
+
+/a[]b/
+Failed: missing terminating ] for character class at offset 4
+
+/[^aeiou ]{3,}/
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+ co-processors, and for
+ 0: -pr
+
+/<.*>/
+Capturing subpattern count = 0
+No options
+First char = '<'
+Need char = '>'
+ abc<def>ghi<klm>nop
+ 0: <def>ghi<klm>
+
+/<.*?>/
+Capturing subpattern count = 0
+No options
+First char = '<'
+Need char = '>'
+ abc<def>ghi<klm>nop
+ 0: <def>
+
+/<.*>/U
+Capturing subpattern count = 0
+Options: ungreedy
+First char = '<'
+Need char = '>'
+ abc<def>ghi<klm>nop
+ 0: <def>
+
+/<.*>(?U)/
+Capturing subpattern count = 0
+Options: ungreedy
+First char = '<'
+Need char = '>'
+ abc<def>ghi<klm>nop
+ 0: <def>
+
+/<.*?>/U
+Capturing subpattern count = 0
+Options: ungreedy
+First char = '<'
+Need char = '>'
+ abc<def>ghi<klm>nop
+ 0: <def>ghi<klm>
+
+/={3,}/U
+Capturing subpattern count = 0
+Options: ungreedy
+First char = '='
+Need char = '='
+ abc========def
+ 0: ===
+
+/(?U)={3,}?/
+Capturing subpattern count = 0
+Options: ungreedy
+First char = '='
+Need char = '='
+ abc========def
+ 0: ========
+
+/(?<!bar|cattle)foo/
+Capturing subpattern count = 0
+No options
+First char = 'f'
+Need char = 'o'
+ foo
+ 0: foo
+ catfoo
+ 0: foo
+ *** Failers
+No match
+ the barfoo
+No match
+ and cattlefoo
+No match
+
+/(?<=a+)b/
+Failed: lookbehind assertion is not fixed length at offset 6
+
+/(?<=aaa|b{0,3})b/
+Failed: lookbehind assertion is not fixed length at offset 14
+
+/(?<!(foo)a\1)bar/
+Failed: lookbehind assertion is not fixed length at offset 12
+
+/(?i)abc/
+Capturing subpattern count = 0
+Options: caseless
+First char = 'a'
+Need char = 'c'
+
+/(a|(?m)a)/
+Capturing subpattern count = 1
+No options
+First char = 'a'
+No need char
+
+/(?i)^1234/
+Capturing subpattern count = 0
+Options: anchored caseless
+No first char
+Need char = '4'
+
+/(^b|(?i)^d)/
+Capturing subpattern count = 1
+Options: anchored
+Case state changes
+No first char
+No need char
+
+/(?s).*/
+Capturing subpattern count = 0
+Options: anchored dotall
+No first char
+No need char
+
+/[abcd]/S
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+Starting character set: a b c d
+
+/(?i)[abcd]/S
+Capturing subpattern count = 0
+Options: caseless
+No first char
+No need char
+Starting character set: A B C D a b c d
+
+/(?m)[xy]|(b|c)/S
+Capturing subpattern count = 1
+Options: multiline
+No first char
+No need char
+Starting character set: b c x y
+
+/(^a|^b)/m
+Capturing subpattern count = 1
+Options: multiline
+First char at start or follows \n
+No need char
+
+/(?i)(^a|^b)/m
+Capturing subpattern count = 1
+Options: caseless multiline
+First char at start or follows \n
+No need char
+
+/(a)(?(1)a|b|c)/
+Failed: conditional group contains more than two branches at offset 13
+
+/(?(?=a)a|b|c)/
+Failed: conditional group contains more than two branches at offset 12
+
+/(?(1a)/
+Failed: malformed number after (?( at offset 4
+
+/(?(?i))/
+Failed: assertion expected after (?( at offset 3
+
+/(?(abc))/
+Failed: assertion expected after (?( at offset 3
+
+/(?(?<ab))/
+Failed: unrecognized character after (?< at offset 2
+
+/((?s)blah)\s+\1/
+Capturing subpattern count = 1
+Max back reference = 1
+No options
+First char = 'b'
+Need char = 'h'
+
+/((?i)blah)\s+\1/
+Capturing subpattern count = 1
+Max back reference = 1
+No options
+Case state changes
+No first char
+Need char = 'h'
+
+/((?i)b)/DS
+------------------------------------------------------------------
+ 0 16 Bra 0
+ 3 8 Bra 1
+ 6 01 Opt
+ 8 1 b
+ 11 8 Ket
+ 14 00 Opt
+ 16 16 Ket
+ 19 End
+------------------------------------------------------------------
+Capturing subpattern count = 1
+No options
+Case state changes
+No first char
+Need char = 'b'
+Starting character set: B b
+
+/(a*b|(?i:c*(?-i)d))/S
+Capturing subpattern count = 1
+No options
+Case state changes
+No first char
+No need char
+Starting character set: C a b c d
+
+/a$/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+No need char
+ a
+ 0: a
+ a\n
+ 0: a
+ *** Failers
+No match
+ \Za
+No match
+ \Za\n
+No match
+
+/a$/m
+Capturing subpattern count = 0
+Options: multiline
+First char = 'a'
+No need char
+ a
+ 0: a
+ a\n
+ 0: a
+ \Za\n
+ 0: a
+ *** Failers
+No match
+ \Za
+No match
+
+/\Aabc/m
+Capturing subpattern count = 0
+Options: anchored multiline
+No first char
+Need char = 'c'
+
+/^abc/m
+Capturing subpattern count = 0
+Options: multiline
+First char at start or follows \n
+Need char = 'c'
+
+/^((a+)(?U)([ab]+)(?-U)([bc]+)(\w*))/
+Capturing subpattern count = 5
+Options: anchored
+No first char
+Need char = 'a'
+ aaaaabbbbbcccccdef
+ 0: aaaaabbbbbcccccdef
+ 1: aaaaabbbbbcccccdef
+ 2: aaaaa
+ 3: b
+ 4: bbbbccccc
+ 5: def
+
+/(?<=foo)[ab]/S
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+Starting character set: a b
+
+/(?<!foo)(alpha|omega)/S
+Capturing subpattern count = 1
+No options
+No first char
+Need char = 'a'
+Starting character set: a o
+
+/(?!alphabet)[ab]/S
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+Starting character set: a b
+
+/(?<=foo\n)^bar/m
+Capturing subpattern count = 0
+Options: multiline
+First char at start or follows \n
+Need char = 'r'
+
+/(?>^abc)/m
+Capturing subpattern count = 0
+Options: multiline
+First char at start or follows \n
+Need char = 'c'
+ abc
+ 0: abc
+ def\nabc
+ 0: abc
+ *** Failers
+No match
+ defabc
+No match
+
+/(?<=ab(c+)d)ef/
+Failed: lookbehind assertion is not fixed length at offset 11
+
+/(?<=ab(?<=c+)d)ef/
+Failed: lookbehind assertion is not fixed length at offset 12
+
+/(?<=ab(c|de)f)g/
+Failed: lookbehind assertion is not fixed length at offset 13
+
+/The next three are in testinput2 because they have variable length branches/
+Capturing subpattern count = 0
+No options
+First char = 'T'
+Need char = 's'
+
+/(?<=bullock|donkey)-cart/
+Capturing subpattern count = 0
+No options
+First char = '-'
+Need char = 't'
+ the bullock-cart
+ 0: -cart
+ a donkey-cart race
+ 0: -cart
+ *** Failers
+No match
+ cart
+No match
+ horse-and-cart
+No match
+
+/(?<=ab(?i)x|y|z)/
+Capturing subpattern count = 0
+No options
+Case state changes
+No first char
+No need char
+
+/(?>.*)(?<=(abcd)|(xyz))/
+Capturing subpattern count = 2
+No options
+First char at start or follows \n
+No need char
+ alphabetabcd
+ 0: alphabetabcd
+ 1: abcd
+ endingxyz
+ 0: endingxyz
+ 1: <unset>
+ 2: xyz
+
+/(?<=ab(?i)x(?-i)y|(?i)z|b)ZZ/
+Capturing subpattern count = 0
+No options
+Case state changes
+First char = 'Z'
+Need char = 'Z'
+ abxyZZ
+ 0: ZZ
+ abXyZZ
+ 0: ZZ
+ ZZZ
+ 0: ZZ
+ zZZ
+ 0: ZZ
+ bZZ
+ 0: ZZ
+ BZZ
+ 0: ZZ
+ *** Failers
+No match
+ ZZ
+No match
+ abXYZZ
+No match
+ zzz
+No match
+ bzz
+No match
+
+/(?<!(foo)a)bar/
+Capturing subpattern count = 1
+No options
+First char = 'b'
+Need char = 'r'
+ bar
+ 0: bar
+ foobbar
+ 0: bar
+ *** Failers
+No match
+ fooabar
+No match
+
+/This one is here because Perl 5.005_02 doesn't fail it/
+Capturing subpattern count = 0
+No options
+First char = 'T'
+Need char = 't'
+
+/^(a)?(?(1)a|b)+$/
+Capturing subpattern count = 1
+Options: anchored
+No first char
+No need char
+ *** Failers
+No match
+ a
+No match
+
+/This one is here because I think Perl 5.005_02 gets the setting of $1 wrong/
+Capturing subpattern count = 0
+No options
+First char = 'T'
+Need char = 'g'
+
+/^(a\1?){4}$/
+Capturing subpattern count = 1
+Max back reference = 1
+Options: anchored
+No first char
+Need char = 'a'
+ aaaaaa
+ 0: aaaaaa
+ 1: aa
+
+/These are syntax tests from Perl 5.005/
+Capturing subpattern count = 0
+No options
+First char = 'T'
+Need char = '5'
+
+/a[b-a]/
+Failed: range out of order in character class at offset 4
+
+/a[]b/
+Failed: missing terminating ] for character class at offset 4
+
+/a[/
+Failed: missing terminating ] for character class at offset 2
+
+/*a/
+Failed: nothing to repeat at offset 0
+
+/(*)b/
+Failed: nothing to repeat at offset 1
+
+/abc)/
+Failed: unmatched parentheses at offset 3
+
+/(abc/
+Failed: missing ) at offset 4
+
+/a**/
+Failed: nothing to repeat at offset 2
+
+/)(/
+Failed: unmatched parentheses at offset 0
+
+/\1/
+Failed: back reference to non-existent subpattern at offset 2
+
+/\2/
+Failed: back reference to non-existent subpattern at offset 2
+
+/(a)|\2/
+Failed: back reference to non-existent subpattern at offset 6
+
+/a[b-a]/i
+Failed: range out of order in character class at offset 4
+
+/a[]b/i
+Failed: missing terminating ] for character class at offset 4
+
+/a[/i
+Failed: missing terminating ] for character class at offset 2
+
+/*a/i
+Failed: nothing to repeat at offset 0
+
+/(*)b/i
+Failed: nothing to repeat at offset 1
+
+/abc)/i
+Failed: unmatched parentheses at offset 3
+
+/(abc/i
+Failed: missing ) at offset 4
+
+/a**/i
+Failed: nothing to repeat at offset 2
+
+/)(/i
+Failed: unmatched parentheses at offset 0
+
+/:(?:/
+Failed: missing ) at offset 4
+
+/(?<%)b/
+Failed: unrecognized character after (?< at offset 0
+
+/a(?{)b/
+Failed: unrecognized character after (? at offset 3
+
+/a(?{{})b/
+Failed: unrecognized character after (? at offset 3
+
+/a(?{}})b/
+Failed: unrecognized character after (? at offset 3
+
+/a(?{"{"})b/
+Failed: unrecognized character after (? at offset 3
+
+/a(?{"{"}})b/
+Failed: unrecognized character after (? at offset 3
+
+/(?(1?)a|b)/
+Failed: malformed number after (?( at offset 4
+
+/(?(1)a|b|c)/
+Failed: conditional group contains more than two branches at offset 10
+
+/[a[:xyz:/
+Failed: missing terminating ] for character class at offset 8
+
+/(?<=x+)y/
+Failed: lookbehind assertion is not fixed length at offset 6
+
+/a{37,17}/
+Failed: numbers out of order in {} quantifier at offset 7
+
+/abc/\
+Failed: \ at end of pattern at offset 4
+
+/abc/\P
+Failed: POSIX code 9: bad escape sequence at offset 4
+
+/abc/\i
+Failed: \ at end of pattern at offset 4
+
+/(a)bc(d)/
+Capturing subpattern count = 2
+No options
+First char = 'a'
+Need char = 'd'
+ abcd
+ 0: abcd
+ 1: a
+ 2: d
+ abcd\C2
+ 0: abcd
+ 1: a
+ 2: d
+ 2C d (1)
+ abcd\C5
+ 0: abcd
+ 1: a
+ 2: d
+copy substring 5 failed -7
+
+/(.{20})/
+Capturing subpattern count = 1
+No options
+No first char
+No need char
+ abcdefghijklmnopqrstuvwxyz
+ 0: abcdefghijklmnopqrst
+ 1: abcdefghijklmnopqrst
+ abcdefghijklmnopqrstuvwxyz\C1
+ 0: abcdefghijklmnopqrst
+ 1: abcdefghijklmnopqrst
+copy substring 1 failed -6
+ abcdefghijklmnopqrstuvwxyz\G1
+ 0: abcdefghijklmnopqrst
+ 1: abcdefghijklmnopqrst
+ 1G abcdefghijklmnopqrst (20)
+
+/(.{15})/
+Capturing subpattern count = 1
+No options
+No first char
+No need char
+ abcdefghijklmnopqrstuvwxyz
+ 0: abcdefghijklmno
+ 1: abcdefghijklmno
+ abcdefghijklmnopqrstuvwxyz\C1\G1
+ 0: abcdefghijklmno
+ 1: abcdefghijklmno
+ 1C abcdefghijklmno (15)
+ 1G abcdefghijklmno (15)
+
+/(.{16})/
+Capturing subpattern count = 1
+No options
+No first char
+No need char
+ abcdefghijklmnopqrstuvwxyz
+ 0: abcdefghijklmnop
+ 1: abcdefghijklmnop
+ abcdefghijklmnopqrstuvwxyz\C1\G1\L
+ 0: abcdefghijklmnop
+ 1: abcdefghijklmnop
+copy substring 1 failed -6
+ 1G abcdefghijklmnop (16)
+ 0L abcdefghijklmnop
+ 1L abcdefghijklmnop
+
+/^(a|(bc))de(f)/
+Capturing subpattern count = 3
+Options: anchored
+No first char
+Need char = 'f'
+ adef\G1\G2\G3\G4\L
+ 0: adef
+ 1: a
+ 2: <unset>
+ 3: f
+ 1G a (1)
+ 2G (0)
+ 3G f (1)
+get substring 4 failed -7
+ 0L adef
+ 1L a
+ 2L
+ 3L f
+ bcdef\G1\G2\G3\G4\L
+ 0: bcdef
+ 1: bc
+ 2: bc
+ 3: f
+ 1G bc (2)
+ 2G bc (2)
+ 3G f (1)
+get substring 4 failed -7
+ 0L bcdef
+ 1L bc
+ 2L bc
+ 3L f
+ adefghijk\C0
+ 0: adef
+ 1: a
+ 2: <unset>
+ 3: f
+ 0C adef (4)
+
+/^abc\00def/
+Capturing subpattern count = 0
+Options: anchored
+No first char
+Need char = 'f'
+ abc\00def\L\C0
+ 0: abc\x00def
+ 0C abc (7)
+ 0L abc
+
+/word ((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+
+)((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+
+)?)?)?)?)?)?)?)?)?otherword/M
+Memory allocation (code space): 428
+Capturing subpattern count = 8
+No options
+First char = 'w'
+Need char = 'd'
+
+/.*X/D
+------------------------------------------------------------------
+ 0 8 Bra 0
+ 3 Any*
+ 5 1 X
+ 8 8 Ket
+ 11 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+No options
+First char at start or follows \n
+Need char = 'X'
+
+/.*X/Ds
+------------------------------------------------------------------
+ 0 8 Bra 0
+ 3 Any*
+ 5 1 X
+ 8 8 Ket
+ 11 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+Options: anchored dotall
+No first char
+Need char = 'X'
+
+/(.*X|^B)/D
+------------------------------------------------------------------
+ 0 21 Bra 0
+ 3 8 Bra 1
+ 6 Any*
+ 8 1 X
+ 11 7 Alt
+ 14 ^
+ 15 1 B
+ 18 15 Ket
+ 21 21 Ket
+ 24 End
+------------------------------------------------------------------
+Capturing subpattern count = 1
+No options
+First char at start or follows \n
+No need char
+
+/(.*X|^B)/Ds
+------------------------------------------------------------------
+ 0 21 Bra 0
+ 3 8 Bra 1
+ 6 Any*
+ 8 1 X
+ 11 7 Alt
+ 14 ^
+ 15 1 B
+ 18 15 Ket
+ 21 21 Ket
+ 24 End
+------------------------------------------------------------------
+Capturing subpattern count = 1
+Options: anchored dotall
+No first char
+No need char
+
+/(?s)(.*X|^B)/D
+------------------------------------------------------------------
+ 0 21 Bra 0
+ 3 8 Bra 1
+ 6 Any*
+ 8 1 X
+ 11 7 Alt
+ 14 ^
+ 15 1 B
+ 18 15 Ket
+ 21 21 Ket
+ 24 End
+------------------------------------------------------------------
+Capturing subpattern count = 1
+Options: anchored dotall
+No first char
+No need char
+
+/(?s:.*X|^B)/D
+------------------------------------------------------------------
+ 0 27 Bra 0
+ 3 10 Bra 0
+ 6 04 Opt
+ 8 Any*
+ 10 1 X
+ 13 9 Alt
+ 16 04 Opt
+ 18 ^
+ 19 1 B
+ 22 19 Ket
+ 25 00 Opt
+ 27 27 Ket
+ 30 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+No options
+First char at start or follows \n
+No need char
+
+/\Biss\B/+
+Capturing subpattern count = 0
+No options
+First char = 'i'
+Need char = 's'
+ Mississippi
+ 0: iss
+ 0+ issippi
+
+/\Biss\B/+P
+ Mississippi
+ 0: iss
+ 0+ issippi
+
+/iss/G+
+Capturing subpattern count = 0
+No options
+First char = 'i'
+Need char = 's'
+ Mississippi
+ 0: iss
+ 0+ issippi
+ 0: iss
+ 0+ ippi
+
+/\Biss\B/G+
+Capturing subpattern count = 0
+No options
+First char = 'i'
+Need char = 's'
+ Mississippi
+ 0: iss
+ 0+ issippi
+
+/\Biss\B/g+
+Capturing subpattern count = 0
+No options
+First char = 'i'
+Need char = 's'
+ Mississippi
+ 0: iss
+ 0+ issippi
+ 0: iss
+ 0+ ippi
+ *** Failers
+No match
+ Mississippi\A
+No match
+
+/(?<=[Ms])iss/g+
+Capturing subpattern count = 0
+No options
+First char = 'i'
+Need char = 's'
+ Mississippi
+ 0: iss
+ 0+ issippi
+ 0: iss
+ 0+ ippi
+
+/(?<=[Ms])iss/G+
+Capturing subpattern count = 0
+No options
+First char = 'i'
+Need char = 's'
+ Mississippi
+ 0: iss
+ 0+ issippi
+
+/^iss/g+
+Capturing subpattern count = 0
+Options: anchored
+No first char
+Need char = 's'
+ ississippi
+ 0: iss
+ 0+ issippi
+
+/.*iss/g+
+Capturing subpattern count = 0
+No options
+First char at start or follows \n
+Need char = 's'
+ abciss\nxyzisspqr
+ 0: abciss
+ 0+ \x0axyzisspqr
+ 0: xyziss
+ 0+ pqr
+
+/.i./+g
+Capturing subpattern count = 0
+No options
+No first char
+Need char = 'i'
+ Mississippi
+ 0: Mis
+ 0+ sissippi
+ 0: sis
+ 0+ sippi
+ 0: sip
+ 0+ pi
+ Mississippi\A
+ 0: Mis
+ 0+ sissippi
+ 0: sis
+ 0+ sippi
+ 0: sip
+ 0+ pi
+ Missouri river
+ 0: Mis
+ 0+ souri river
+ 0: ri
+ 0+ river
+ 0: riv
+ 0+ er
+ Missouri river\A
+ 0: Mis
+ 0+ souri river
+
+/^.is/+g
+Capturing subpattern count = 0
+Options: anchored
+No first char
+Need char = 's'
+ Mississippi
+ 0: Mis
+ 0+ sissippi
+
+/^ab\n/g+
+Capturing subpattern count = 0
+Options: anchored
+No first char
+Need char = 10
+ ab\nab\ncd
+ 0: ab\x0a
+ 0+ ab\x0acd
+
+/^ab\n/mg+
+Capturing subpattern count = 0
+Options: multiline
+First char at start or follows \n
+Need char = 10
+ ab\nab\ncd
+ 0: ab\x0a
+ 0+ ab\x0acd
+ 0: ab\x0a
+ 0+ cd
+
+/abc/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+Need char = 'c'
+
+/abc|bac/
+Capturing subpattern count = 0
+No options
+No first char
+Need char = 'c'
+
+/(abc|bac)/
+Capturing subpattern count = 1
+No options
+No first char
+Need char = 'c'
+
+/(abc|(c|dc))/
+Capturing subpattern count = 2
+No options
+No first char
+Need char = 'c'
+
+/(abc|(d|de)c)/
+Capturing subpattern count = 2
+No options
+No first char
+Need char = 'c'
+
+/a*/
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+
+/a+/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+No need char
+
+/(baa|a+)/
+Capturing subpattern count = 1
+No options
+No first char
+Need char = 'a'
+
+/a{0,3}/
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+
+/baa{3,}/
+Capturing subpattern count = 0
+No options
+First char = 'b'
+Need char = 'a'
+
+/"([^\\"]+|\\.)*"/
+Capturing subpattern count = 1
+No options
+First char = '"'
+Need char = '"'
+
+/(abc|ab[cd])/
+Capturing subpattern count = 1
+No options
+First char = 'a'
+No need char
+
+/(a|.)/
+Capturing subpattern count = 1
+No options
+No first char
+No need char
+
+/a|ba|\w/
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+
+/abc(?=pqr)/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+Need char = 'r'
+
+/...(?<=abc)/
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+
+/abc(?!pqr)/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+Need char = 'c'
+
+/ab./
+Capturing subpattern count = 0
+No options
+First char = 'a'
+Need char = 'b'
+
+/ab[xyz]/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+Need char = 'b'
+
+/abc*/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+Need char = 'b'
+
+/ab.c*/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+Need char = 'b'
+
+/a.c*/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+No need char
+
+/.c*/
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+
+/ac*/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+No need char
+
+/(a.c*|b.c*)/
+Capturing subpattern count = 1
+No options
+No first char
+No need char
+
+/a.c*|aba/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+No need char
+
+/.+a/
+Capturing subpattern count = 0
+No options
+No first char
+Need char = 'a'
+
+/(?=abcda)a.*/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+No need char
+
+/(?=a)a.*/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+No need char
+
+/a(b)*/
+Capturing subpattern count = 1
+No options
+First char = 'a'
+No need char
+
+/a\d*/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+No need char
+
+/ab\d*/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+Need char = 'b'
+
+/a(\d)*/
+Capturing subpattern count = 1
+No options
+First char = 'a'
+No need char
+
+/abcde{0,0}/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+Need char = 'd'
+
+/ab\d+/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+Need char = 'b'
+
+/a(?(1)b)/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+No need char
+
+/a(?(1)bag|big)/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+Need char = 'g'
+
+/a(?(1)bag|big)*/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+No need char
+
+/a(?(1)bag|big)+/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+Need char = 'g'
+
+/a(?(1)b..|b..)/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+Need char = 'b'
+
+/ab\d{0}e/
+Capturing subpattern count = 0
+No options
+First char = 'a'
+Need char = 'e'
+
+/a?b?/
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+ a
+ 0: a
+ b
+ 0: b
+ ab
+ 0: ab
+ \
+ 0:
+ *** Failers
+ 0:
+ \N
+No match
+
+/|-/
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+ abcd
+ 0:
+ -abc
+ 0:
+ \Nab-c
+ 0: -
+ *** Failers
+ 0:
+ \Nabc
+No match
+
+/a*(b+)(z)(z)/P
+ aaaabbbbzzzz
+ 0: aaaabbbbzz
+ 1: bbbb
+ 2: z
+ 3: z
+ aaaabbbbzzzz\O0
+ aaaabbbbzzzz\O1
+ 0: aaaabbbbzz
+ aaaabbbbzzzz\O2
+ 0: aaaabbbbzz
+ 1: bbbb
+ aaaabbbbzzzz\O3
+ 0: aaaabbbbzz
+ 1: bbbb
+ 2: z
+ aaaabbbbzzzz\O4
+ 0: aaaabbbbzz
+ 1: bbbb
+ 2: z
+ 3: z
+ aaaabbbbzzzz\O5
+ 0: aaaabbbbzz
+ 1: bbbb
+ 2: z
+ 3: z
+
+/^.?abcd/S
+Capturing subpattern count = 0
+Options: anchored
+No first char
+Need char = 'd'
+Study returned NULL
+
+/\( # ( at start
+ (?: # Non-capturing bracket
+ (?>[^()]+) # Either a sequence of non-brackets (no backtracking)
+ | # Or
+ (?R) # Recurse - i.e. nested bracketed string
+ )* # Zero or more contents
+ \) # Closing )
+ /x
+Capturing subpattern count = 0
+Options: extended
+First char = '('
+Need char = ')'
+ (abcd)
+ 0: (abcd)
+ (abcd)xyz
+ 0: (abcd)
+ xyz(abcd)
+ 0: (abcd)
+ (ab(xy)cd)pqr
+ 0: (ab(xy)cd)
+ (ab(xycd)pqr
+ 0: (xycd)
+ () abc ()
+ 0: ()
+ 12(abcde(fsh)xyz(foo(bar))lmno)89
+ 0: (abcde(fsh)xyz(foo(bar))lmno)
+ *** Failers
+No match
+ abcd
+No match
+ abcd)
+No match
+ (abcd
+No match
+
+/\( ( (?>[^()]+) | (?R) )* \) /xg
+Capturing subpattern count = 1
+Options: extended
+First char = '('
+Need char = ')'
+ (ab(xy)cd)pqr
+ 0: (ab(xy)cd)
+ 1: cd
+ 1(abcd)(x(y)z)pqr
+ 0: (abcd)
+ 1: abcd
+ 0: (x(y)z)
+ 1: z
+
+/\( (?: (?>[^()]+) | (?R) ) \) /x
+Capturing subpattern count = 0
+Options: extended
+First char = '('
+Need char = ')'
+ (abcd)
+ 0: (abcd)
+ (ab(xy)cd)
+ 0: (xy)
+ (a(b(c)d)e)
+ 0: (c)
+ ((ab))
+ 0: ((ab))
+ *** Failers
+No match
+ ()
+No match
+
+/\( (?: (?>[^()]+) | (?R) )? \) /x
+Capturing subpattern count = 0
+Options: extended
+First char = '('
+Need char = ')'
+ ()
+ 0: ()
+ 12(abcde(fsh)xyz(foo(bar))lmno)89
+ 0: (fsh)
+
+/\( ( (?>[^()]+) | (?R) )* \) /x
+Capturing subpattern count = 1
+Options: extended
+First char = '('
+Need char = ')'
+ (ab(xy)cd)
+ 0: (ab(xy)cd)
+ 1: cd
+
+/\( ( ( (?>[^()]+) | (?R) )* ) \) /x
+Capturing subpattern count = 2
+Options: extended
+First char = '('
+Need char = ')'
+ (ab(xy)cd)
+ 0: (ab(xy)cd)
+ 1: ab(xy)cd
+ 2: cd
+
+/\( (123)? ( ( (?>[^()]+) | (?R) )* ) \) /x
+Capturing subpattern count = 3
+Options: extended
+First char = '('
+Need char = ')'
+ (ab(xy)cd)
+ 0: (ab(xy)cd)
+ 1: <unset>
+ 2: ab(xy)cd
+ 3: cd
+ (123ab(xy)cd)
+ 0: (123ab(xy)cd)
+ 1: 123
+ 2: ab(xy)cd
+ 3: cd
+
+/\( ( (123)? ( (?>[^()]+) | (?R) )* ) \) /x
+Capturing subpattern count = 3
+Options: extended
+First char = '('
+Need char = ')'
+ (ab(xy)cd)
+ 0: (ab(xy)cd)
+ 1: ab(xy)cd
+ 2: <unset>
+ 3: cd
+ (123ab(xy)cd)
+ 0: (123ab(xy)cd)
+ 1: 123ab(xy)cd
+ 2: 123
+ 3: cd
+
+/\( (((((((((( ( (?>[^()]+) | (?R) )* )))))))))) \) /x
+Capturing subpattern count = 11
+Options: extended
+First char = '('
+Need char = ')'
+ (ab(xy)cd)
+ 0: (ab(xy)cd)
+ 1: ab(xy)cd
+ 2: ab(xy)cd
+ 3: ab(xy)cd
+ 4: ab(xy)cd
+ 5: ab(xy)cd
+ 6: ab(xy)cd
+ 7: ab(xy)cd
+ 8: ab(xy)cd
+ 9: ab(xy)cd
+10: ab(xy)cd
+11: cd
+
+/\( ( ( (?>[^()<>]+) | ((?>[^()]+)) | (?R) )* ) \) /x
+Capturing subpattern count = 3
+Options: extended
+First char = '('
+Need char = ')'
+ (abcd(xyz<p>qrs)123)
+ 0: (abcd(xyz<p>qrs)123)
+ 1: abcd(xyz<p>qrs)123
+ 2: 123
+ 3: <p>qrs
+
+/\( ( ( (?>[^()]+) | ((?R)) )* ) \) /x
+Capturing subpattern count = 3
+Options: extended
+First char = '('
+Need char = ')'
+ (ab(cd)ef)
+ 0: (ab(cd)ef)
+ 1: ab(cd)ef
+ 2: ef
+ 3: (cd)
+ (ab(cd(ef)gh)ij)
+ 0: (ab(cd(ef)gh)ij)
+ 1: ab(cd(ef)gh)ij
+ 2: ij
+ 3: (cd(ef)gh)
+
+/^[[:alnum:]]/D
+------------------------------------------------------------------
+ 0 37 Bra 0
+ 3 ^
+ 4 [0-9A-Za-z]
+ 37 37 Ket
+ 40 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+Options: anchored
+No first char
+No need char
+
+/^[[:alpha:]]/D
+------------------------------------------------------------------
+ 0 37 Bra 0
+ 3 ^
+ 4 [A-Za-z]
+ 37 37 Ket
+ 40 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+Options: anchored
+No first char
+No need char
+
+/^[[:ascii:]]/D
+------------------------------------------------------------------
+ 0 37 Bra 0
+ 3 ^
+ 4 [\x00-\x7f]
+ 37 37 Ket
+ 40 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+Options: anchored
+No first char
+No need char
+
+/^[[:cntrl:]]/D
+------------------------------------------------------------------
+ 0 37 Bra 0
+ 3 ^
+ 4 [\x00-\x1f\x7f]
+ 37 37 Ket
+ 40 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+Options: anchored
+No first char
+No need char
+
+/^[[:digit:]]/D
+------------------------------------------------------------------
+ 0 37 Bra 0
+ 3 ^
+ 4 [0-9]
+ 37 37 Ket
+ 40 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+Options: anchored
+No first char
+No need char
+
+/^[[:graph:]]/D
+------------------------------------------------------------------
+ 0 37 Bra 0
+ 3 ^
+ 4 [!-~]
+ 37 37 Ket
+ 40 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+Options: anchored
+No first char
+No need char
+
+/^[[:lower:]]/D
+------------------------------------------------------------------
+ 0 37 Bra 0
+ 3 ^
+ 4 [a-z]
+ 37 37 Ket
+ 40 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+Options: anchored
+No first char
+No need char
+
+/^[[:print:]]/D
+------------------------------------------------------------------
+ 0 37 Bra 0
+ 3 ^
+ 4 [ -~]
+ 37 37 Ket
+ 40 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+Options: anchored
+No first char
+No need char
+
+/^[[:punct:]]/D
+------------------------------------------------------------------
+ 0 37 Bra 0
+ 3 ^
+ 4 [!-/:-@[-`{-~]
+ 37 37 Ket
+ 40 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+Options: anchored
+No first char
+No need char
+
+/^[[:space:]]/D
+------------------------------------------------------------------
+ 0 37 Bra 0
+ 3 ^
+ 4 [\x09-\x0d ]
+ 37 37 Ket
+ 40 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+Options: anchored
+No first char
+No need char
+
+/^[[:upper:]]/D
+------------------------------------------------------------------
+ 0 37 Bra 0
+ 3 ^
+ 4 [A-Z]
+ 37 37 Ket
+ 40 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+Options: anchored
+No first char
+No need char
+
+/^[[:xdigit:]]/D
+------------------------------------------------------------------
+ 0 37 Bra 0
+ 3 ^
+ 4 [0-9A-Fa-f]
+ 37 37 Ket
+ 40 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+Options: anchored
+No first char
+No need char
+
+/^[[:word:]]/D
+------------------------------------------------------------------
+ 0 37 Bra 0
+ 3 ^
+ 4 [0-9A-Z_a-z]
+ 37 37 Ket
+ 40 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+Options: anchored
+No first char
+No need char
+
+/^[[:^cntrl:]]/D
+------------------------------------------------------------------
+ 0 37 Bra 0
+ 3 ^
+ 4 [ -~\x80-\xff]
+ 37 37 Ket
+ 40 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+Options: anchored
+No first char
+No need char
+
+/^[12[:^digit:]]/D
+------------------------------------------------------------------
+ 0 37 Bra 0
+ 3 ^
+ 4 [\x00-/1-2:-\xff]
+ 37 37 Ket
+ 40 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+Options: anchored
+No first char
+No need char
+
+/[01[:alpha:]%]/D
+------------------------------------------------------------------
+ 0 36 Bra 0
+ 3 [%0-1A-Za-z]
+ 36 36 Ket
+ 39 End
+------------------------------------------------------------------
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+
+/[[.ch.]]/
+Failed: POSIX collating elements are not supported at offset 1
+
+/[[=ch=]]/
+Failed: POSIX collating elements are not supported at offset 1
+
+/[[:rhubarb:]]/
+Failed: unknown POSIX class name at offset 3
+
+/[[:upper:]]/i
+Capturing subpattern count = 0
+Options: caseless
+No first char
+No need char
+ A
+ 0: A
+ a
+ 0: a
+
+/[[:lower:]]/i
+Capturing subpattern count = 0
+Options: caseless
+No first char
+No need char
+ A
+ 0: A
+ a
+ 0: a
+
+/((?-i)[[:lower:]])[[:lower:]]/i
+Capturing subpattern count = 1
+Options: caseless
+Case state changes
+No first char
+No need char
+ ab
+ 0: ab
+ 1: a
+ aB
+ 0: aB
+ 1: a
+ *** Failers
+ 0: ai
+ 1: a
+ Ab
+No match
+ AB
+No match
+
+/ End of test input /
+Capturing subpattern count = 0
+No options
+First char = ' '
+Need char = ' '
+
--- /dev/null
+PCRE version 3.1 09-Feb-2000
+
+/(?<!bar)foo/
+ foo
+ 0: foo
+ catfood
+ 0: foo
+ arfootle
+ 0: foo
+ rfoosh
+ 0: foo
+ *** Failers
+No match
+ barfoo
+No match
+ towbarfoo
+No match
+
+/\w{3}(?<!bar)foo/
+ catfood
+ 0: catfoo
+ *** Failers
+No match
+ foo
+No match
+ barfoo
+No match
+ towbarfoo
+No match
+
+/(?<=(foo)a)bar/
+ fooabar
+ 0: bar
+ 1: foo
+ *** Failers
+No match
+ bar
+No match
+ foobbar
+No match
+
+/\Aabc\z/m
+ abc
+ 0: abc
+ *** Failers
+No match
+ abc\n
+No match
+ qqq\nabc
+No match
+ abc\nzzz
+No match
+ qqq\nabc\nzzz
+No match
+
+"(?>.*/)foo"
+ /this/is/a/very/long/line/in/deed/with/very/many/slashes/in/it/you/see/
+No match
+
+"(?>.*/)foo"
+ /this/is/a/very/long/line/in/deed/with/very/many/slashes/in/and/foo
+ 0: /this/is/a/very/long/line/in/deed/with/very/many/slashes/in/and/foo
+
+/(?>(\.\d\d[1-9]?))\d+/
+ 1.230003938
+ 0: .230003938
+ 1: .23
+ 1.875000282
+ 0: .875000282
+ 1: .875
+ *** Failers
+No match
+ 1.235
+No match
+
+/^((?>\w+)|(?>\s+))*$/
+ now is the time for all good men to come to the aid of the party
+ 0: now is the time for all good men to come to the aid of the party
+ 1: party
+ *** Failers
+No match
+ this is not a line with only words and spaces!
+No match
+
+/(\d+)(\w)/
+ 12345a
+ 0: 12345a
+ 1: 12345
+ 2: a
+ 12345+
+ 0: 12345
+ 1: 1234
+ 2: 5
+
+/((?>\d+))(\w)/
+ 12345a
+ 0: 12345a
+ 1: 12345
+ 2: a
+ *** Failers
+No match
+ 12345+
+No match
+
+/(?>a+)b/
+ aaab
+ 0: aaab
+
+/((?>a+)b)/
+ aaab
+ 0: aaab
+ 1: aaab
+
+/(?>(a+))b/
+ aaab
+ 0: aaab
+ 1: aaa
+
+/(?>b)+/
+ aaabbbccc
+ 0: bbb
+
+/(?>a+|b+|c+)*c/
+ aaabbbbccccd
+ 0: aaabbbbc
+
+/((?>[^()]+)|\([^()]*\))+/
+ ((abc(ade)ufh()()x
+ 0: abc(ade)ufh()()x
+ 1: x
+
+/\(((?>[^()]+)|\([^()]+\))+\)/
+ (abc)
+ 0: (abc)
+ 1: abc
+ (abc(def)xyz)
+ 0: (abc(def)xyz)
+ 1: xyz
+ *** Failers
+No match
+ ((()aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+No match
+
+/a(?-i)b/i
+ ab
+ 0: ab
+ *** Failers
+No match
+ Ab
+No match
+ aB
+No match
+ AB
+No match
+
+/(a (?x)b c)d e/
+ a bcd e
+ 0: a bcd e
+ 1: a bc
+ *** Failers
+No match
+ a b cd e
+No match
+ abcd e
+No match
+ a bcde
+No match
+
+/(a b(?x)c d (?-x)e f)/
+ a bcde f
+ 0: a bcde f
+ 1: a bcde f
+ *** Failers
+No match
+ abcdef
+No match
+
+/(a(?i)b)c/
+ abc
+ 0: abc
+ 1: ab
+ aBc
+ 0: aBc
+ 1: aB
+ *** Failers
+No match
+ abC
+No match
+ aBC
+No match
+ Abc
+No match
+ ABc
+No match
+ ABC
+No match
+ AbC
+No match
+
+/a(?i:b)c/
+ abc
+ 0: abc
+ aBc
+ 0: aBc
+ *** Failers
+No match
+ ABC
+No match
+ abC
+No match
+ aBC
+No match
+
+/a(?i:b)*c/
+ aBc
+ 0: aBc
+ aBBc
+ 0: aBBc
+ *** Failers
+No match
+ aBC
+No match
+ aBBC
+No match
+
+/a(?=b(?i)c)\w\wd/
+ abcd
+ 0: abcd
+ abCd
+ 0: abCd
+ *** Failers
+No match
+ aBCd
+No match
+ abcD
+No match
+
+/(?s-i:more.*than).*million/i
+ more than million
+ 0: more than million
+ more than MILLION
+ 0: more than MILLION
+ more \n than Million
+ 0: more \x0a than Million
+ *** Failers
+No match
+ MORE THAN MILLION
+No match
+ more \n than \n million
+No match
+
+/(?:(?s-i)more.*than).*million/i
+ more than million
+ 0: more than million
+ more than MILLION
+ 0: more than MILLION
+ more \n than Million
+ 0: more \x0a than Million
+ *** Failers
+No match
+ MORE THAN MILLION
+No match
+ more \n than \n million
+No match
+
+/(?>a(?i)b+)+c/
+ abc
+ 0: abc
+ aBbc
+ 0: aBbc
+ aBBc
+ 0: aBBc
+ *** Failers
+No match
+ Abc
+No match
+ abAb
+No match
+ abbC
+No match
+
+/(?=a(?i)b)\w\wc/
+ abc
+ 0: abc
+ aBc
+ 0: aBc
+ *** Failers
+No match
+ Ab
+No match
+ abC
+No match
+ aBC
+No match
+
+/(?<=a(?i)b)(\w\w)c/
+ abxxc
+ 0: xxc
+ 1: xx
+ aBxxc
+ 0: xxc
+ 1: xx
+ *** Failers
+No match
+ Abxxc
+No match
+ ABxxc
+No match
+ abxxC
+No match
+
+/(?:(a)|b)(?(1)A|B)/
+ aA
+ 0: aA
+ 1: a
+ bB
+ 0: bB
+ *** Failers
+No match
+ aB
+No match
+ bA
+No match
+
+/^(a)?(?(1)a|b)+$/
+ aa
+ 0: aa
+ 1: a
+ b
+ 0: b
+ bb
+ 0: bb
+ *** Failers
+No match
+ ab
+No match
+
+/^(?(?=abc)\w{3}:|\d\d)$/
+ abc:
+ 0: abc:
+ 12
+ 0: 12
+ *** Failers
+No match
+ 123
+No match
+ xyz
+No match
+
+/^(?(?!abc)\d\d|\w{3}:)$/
+ abc:
+ 0: abc:
+ 12
+ 0: 12
+ *** Failers
+No match
+ 123
+No match
+ xyz
+No match
+
+/(?(?<=foo)bar|cat)/
+ foobar
+ 0: bar
+ cat
+ 0: cat
+ fcat
+ 0: cat
+ focat
+ 0: cat
+ *** Failers
+No match
+ foocat
+No match
+
+/(?(?<!foo)cat|bar)/
+ foobar
+ 0: bar
+ cat
+ 0: cat
+ fcat
+ 0: cat
+ focat
+ 0: cat
+ *** Failers
+No match
+ foocat
+No match
+
+/( \( )? [^()]+ (?(1) \) |) /x
+ abcd
+ 0: abcd
+ (abcd)
+ 0: (abcd)
+ 1: (
+ the quick (abcd) fox
+ 0: the quick
+ (abcd
+ 0: abcd
+
+/( \( )? [^()]+ (?(1) \) ) /x
+ abcd
+ 0: abcd
+ (abcd)
+ 0: (abcd)
+ 1: (
+ the quick (abcd) fox
+ 0: the quick
+ (abcd
+ 0: abcd
+
+/^(?(2)a|(1)(2))+$/
+ 12
+ 0: 12
+ 1: 1
+ 2: 2
+ 12a
+ 0: 12a
+ 1: 1
+ 2: 2
+ 12aa
+ 0: 12aa
+ 1: 1
+ 2: 2
+ *** Failers
+No match
+ 1234
+No match
+
+/((?i)blah)\s+\1/
+ blah blah
+ 0: blah blah
+ 1: blah
+ BLAH BLAH
+ 0: BLAH BLAH
+ 1: BLAH
+ Blah Blah
+ 0: Blah Blah
+ 1: Blah
+ blaH blaH
+ 0: blaH blaH
+ 1: blaH
+ *** Failers
+No match
+ blah BLAH
+No match
+ Blah blah
+No match
+ blaH blah
+No match
+
+/((?i)blah)\s+(?i:\1)/
+ blah blah
+ 0: blah blah
+ 1: blah
+ BLAH BLAH
+ 0: BLAH BLAH
+ 1: BLAH
+ Blah Blah
+ 0: Blah Blah
+ 1: Blah
+ blaH blaH
+ 0: blaH blaH
+ 1: blaH
+ blah BLAH
+ 0: blah BLAH
+ 1: blah
+ Blah blah
+ 0: Blah blah
+ 1: Blah
+ blaH blah
+ 0: blaH blah
+ 1: blaH
+
+/(?>a*)*/
+ a
+ 0: a
+ aa
+ 0: aa
+ aaaa
+ 0: aaaa
+
+/(abc|)+/
+ abc
+ 0: abc
+ 1:
+ abcabc
+ 0: abcabc
+ 1:
+ abcabcabc
+ 0: abcabcabc
+ 1:
+ xyz
+ 0:
+ 1:
+
+/([a]*)*/
+ a
+ 0: a
+ 1:
+ aaaaa
+ 0: aaaaa
+ 1:
+
+/([ab]*)*/
+ a
+ 0: a
+ 1:
+ b
+ 0: b
+ 1:
+ ababab
+ 0: ababab
+ 1:
+ aaaabcde
+ 0: aaaab
+ 1:
+ bbbb
+ 0: bbbb
+ 1:
+
+/([^a]*)*/
+ b
+ 0: b
+ 1:
+ bbbb
+ 0: bbbb
+ 1:
+ aaa
+ 0:
+ 1:
+
+/([^ab]*)*/
+ cccc
+ 0: cccc
+ 1:
+ abab
+ 0:
+ 1:
+
+/([a]*?)*/
+ a
+ 0:
+ 1:
+ aaaa
+ 0:
+ 1:
+
+/([ab]*?)*/
+ a
+ 0:
+ 1:
+ b
+ 0:
+ 1:
+ abab
+ 0:
+ 1:
+ baba
+ 0:
+ 1:
+
+/([^a]*?)*/
+ b
+ 0:
+ 1:
+ bbbb
+ 0:
+ 1:
+ aaa
+ 0:
+ 1:
+
+/([^ab]*?)*/
+ c
+ 0:
+ 1:
+ cccc
+ 0:
+ 1:
+ baba
+ 0:
+ 1:
+
+/(?>a*)*/
+ a
+ 0: a
+ aaabcde
+ 0: aaa
+
+/((?>a*))*/
+ aaaaa
+ 0: aaaaa
+ 1:
+ aabbaa
+ 0: aa
+ 1:
+
+/((?>a*?))*/
+ aaaaa
+ 0:
+ 1:
+ aabbaa
+ 0:
+ 1:
+
+/(?(?=[^a-z]+[a-z]) \d{2}-[a-z]{3}-\d{2} | \d{2}-\d{2}-\d{2} ) /x
+ 12-sep-98
+ 0: 12-sep-98
+ 12-09-98
+ 0: 12-09-98
+ *** Failers
+No match
+ sep-12-98
+No match
+
+/(?<=(foo))bar\1/
+ foobarfoo
+ 0: barfoo
+ 1: foo
+ foobarfootling
+ 0: barfoo
+ 1: foo
+ *** Failers
+No match
+ foobar
+No match
+ barfoo
+No match
+
+/(?i:saturday|sunday)/
+ saturday
+ 0: saturday
+ sunday
+ 0: sunday
+ Saturday
+ 0: Saturday
+ Sunday
+ 0: Sunday
+ SATURDAY
+ 0: SATURDAY
+ SUNDAY
+ 0: SUNDAY
+ SunDay
+ 0: SunDay
+
+/(a(?i)bc|BB)x/
+ abcx
+ 0: abcx
+ 1: abc
+ aBCx
+ 0: aBCx
+ 1: aBC
+ bbx
+ 0: bbx
+ 1: bb
+ BBx
+ 0: BBx
+ 1: BB
+ *** Failers
+No match
+ abcX
+No match
+ aBCX
+No match
+ bbX
+No match
+ BBX
+No match
+
+/^([ab](?i)[cd]|[ef])/
+ ac
+ 0: ac
+ 1: ac
+ aC
+ 0: aC
+ 1: aC
+ bD
+ 0: bD
+ 1: bD
+ elephant
+ 0: e
+ 1: e
+ Europe
+ 0: E
+ 1: E
+ frog
+ 0: f
+ 1: f
+ France
+ 0: F
+ 1: F
+ *** Failers
+No match
+ Africa
+No match
+
+/^(ab|a(?i)[b-c](?m-i)d|x(?i)y|z)/
+ ab
+ 0: ab
+ 1: ab
+ aBd
+ 0: aBd
+ 1: aBd
+ xy
+ 0: xy
+ 1: xy
+ xY
+ 0: xY
+ 1: xY
+ zebra
+ 0: z
+ 1: z
+ Zambesi
+ 0: Z
+ 1: Z
+ *** Failers
+No match
+ aCD
+No match
+ XY
+No match
+
+/(?<=foo\n)^bar/m
+ foo\nbar
+ 0: bar
+ *** Failers
+No match
+ bar
+No match
+ baz\nbar
+No match
+
+/(?<=(?<!foo)bar)baz/
+ barbaz
+ 0: baz
+ barbarbaz
+ 0: baz
+ koobarbaz
+ 0: baz
+ *** Failers
+No match
+ baz
+No match
+ foobarbaz
+No match
+
+/The case of aaaaaa is missed out below because I think Perl 5.005_02 gets/
+/it wrong; it sets $1 to aaa rather than aa. Compare the following test,/
+No match
+/where it does set $1 to aa when matching aaaaaa./
+No match
+
+/^(a\1?){4}$/
+ a
+No match
+ aa
+No match
+ aaa
+No match
+ aaaa
+ 0: aaaa
+ 1: a
+ aaaaa
+ 0: aaaaa
+ 1: a
+ aaaaaaa
+ 0: aaaaaaa
+ 1: a
+ aaaaaaaa
+No match
+ aaaaaaaaa
+No match
+ aaaaaaaaaa
+ 0: aaaaaaaaaa
+ 1: aaaa
+ aaaaaaaaaaa
+No match
+ aaaaaaaaaaaa
+No match
+ aaaaaaaaaaaaa
+No match
+ aaaaaaaaaaaaaa
+No match
+ aaaaaaaaaaaaaaa
+No match
+ aaaaaaaaaaaaaaaa
+No match
+
+/^(a\1?)(a\1?)(a\2?)(a\3?)$/
+ a
+No match
+ aa
+No match
+ aaa
+No match
+ aaaa
+ 0: aaaa
+ 1: a
+ 2: a
+ 3: a
+ 4: a
+ aaaaa
+ 0: aaaaa
+ 1: a
+ 2: aa
+ 3: a
+ 4: a
+ aaaaaa
+ 0: aaaaaa
+ 1: a
+ 2: aa
+ 3: a
+ 4: aa
+ aaaaaaa
+ 0: aaaaaaa
+ 1: a
+ 2: aa
+ 3: aaa
+ 4: a
+ aaaaaaaa
+No match
+ aaaaaaaaa
+No match
+ aaaaaaaaaa
+ 0: aaaaaaaaaa
+ 1: a
+ 2: aa
+ 3: aaa
+ 4: aaaa
+ aaaaaaaaaaa
+No match
+ aaaaaaaaaaaa
+No match
+ aaaaaaaaaaaaa
+No match
+ aaaaaaaaaaaaaa
+No match
+ aaaaaaaaaaaaaaa
+No match
+ aaaaaaaaaaaaaaaa
+No match
+
+/The following tests are taken from the Perl 5.005 test suite; some of them/
+/are compatible with 5.004, but I'd rather not have to sort them out./
+No match
+
+/abc/
+ abc
+ 0: abc
+ xabcy
+ 0: abc
+ ababc
+ 0: abc
+ *** Failers
+No match
+ xbc
+No match
+ axc
+No match
+ abx
+No match
+
+/ab*c/
+ abc
+ 0: abc
+
+/ab*bc/
+ abc
+ 0: abc
+ abbc
+ 0: abbc
+ abbbbc
+ 0: abbbbc
+
+/.{1}/
+ abbbbc
+ 0: a
+
+/.{3,4}/
+ abbbbc
+ 0: abbb
+
+/ab{0,}bc/
+ abbbbc
+ 0: abbbbc
+
+/ab+bc/
+ abbc
+ 0: abbc
+ *** Failers
+No match
+ abc
+No match
+ abq
+No match
+
+/ab{1,}bc/
+
+/ab+bc/
+ abbbbc
+ 0: abbbbc
+
+/ab{1,}bc/
+ abbbbc
+ 0: abbbbc
+
+/ab{1,3}bc/
+ abbbbc
+ 0: abbbbc
+
+/ab{3,4}bc/
+ abbbbc
+ 0: abbbbc
+
+/ab{4,5}bc/
+ *** Failers
+No match
+ abq
+No match
+ abbbbc
+No match
+
+/ab?bc/
+ abbc
+ 0: abbc
+ abc
+ 0: abc
+
+/ab{0,1}bc/
+ abc
+ 0: abc
+
+/ab?bc/
+
+/ab?c/
+ abc
+ 0: abc
+
+/ab{0,1}c/
+ abc
+ 0: abc
+
+/^abc$/
+ abc
+ 0: abc
+ *** Failers
+No match
+ abbbbc
+No match
+ abcc
+No match
+
+/^abc/
+ abcc
+ 0: abc
+
+/^abc$/
+
+/abc$/
+ aabc
+ 0: abc
+ *** Failers
+No match
+ aabc
+ 0: abc
+ aabcd
+No match
+
+/^/
+ abc
+ 0:
+
+/$/
+ abc
+ 0:
+
+/a.c/
+ abc
+ 0: abc
+ axc
+ 0: axc
+
+/a.*c/
+ axyzc
+ 0: axyzc
+
+/a[bc]d/
+ abd
+ 0: abd
+ *** Failers
+No match
+ axyzd
+No match
+ abc
+No match
+
+/a[b-d]e/
+ ace
+ 0: ace
+
+/a[b-d]/
+ aac
+ 0: ac
+
+/a[-b]/
+ a-
+ 0: a-
+
+/a[b-]/
+ a-
+ 0: a-
+
+/a]/
+ a]
+ 0: a]
+
+/a[]]b/
+ a]b
+ 0: a]b
+
+/a[^bc]d/
+ aed
+ 0: aed
+ *** Failers
+No match
+ abd
+No match
+ abd
+No match
+
+/a[^-b]c/
+ adc
+ 0: adc
+
+/a[^]b]c/
+ adc
+ 0: adc
+ *** Failers
+No match
+ a-c
+ 0: a-c
+ a]c
+No match
+
+/\ba\b/
+ a-
+ 0: a
+ -a
+ 0: a
+ -a-
+ 0: a
+
+/\by\b/
+ *** Failers
+No match
+ xy
+No match
+ yz
+No match
+ xyz
+No match
+
+/\Ba\B/
+ *** Failers
+ 0: a
+ a-
+No match
+ -a
+No match
+ -a-
+No match
+
+/\By\b/
+ xy
+ 0: y
+
+/\by\B/
+ yz
+ 0: y
+
+/\By\B/
+ xyz
+ 0: y
+
+/\w/
+ a
+ 0: a
+
+/\W/
+ -
+ 0: -
+ *** Failers
+ 0: *
+ -
+ 0: -
+ a
+No match
+
+/a\sb/
+ a b
+ 0: a b
+
+/a\Sb/
+ a-b
+ 0: a-b
+ *** Failers
+No match
+ a-b
+ 0: a-b
+ a b
+No match
+
+/\d/
+ 1
+ 0: 1
+
+/\D/
+ -
+ 0: -
+ *** Failers
+ 0: *
+ -
+ 0: -
+ 1
+No match
+
+/[\w]/
+ a
+ 0: a
+
+/[\W]/
+ -
+ 0: -
+ *** Failers
+ 0: *
+ -
+ 0: -
+ a
+No match
+
+/a[\s]b/
+ a b
+ 0: a b
+
+/a[\S]b/
+ a-b
+ 0: a-b
+ *** Failers
+No match
+ a-b
+ 0: a-b
+ a b
+No match
+
+/[\d]/
+ 1
+ 0: 1
+
+/[\D]/
+ -
+ 0: -
+ *** Failers
+ 0: *
+ -
+ 0: -
+ 1
+No match
+
+/ab|cd/
+ abc
+ 0: ab
+ abcd
+ 0: ab
+
+/()ef/
+ def
+ 0: ef
+ 1:
+
+/$b/
+
+/a\(b/
+ a(b
+ 0: a(b
+
+/a\(*b/
+ ab
+ 0: ab
+ a((b
+ 0: a((b
+
+/a\\b/
+ a\b
+No match
+
+/((a))/
+ abc
+ 0: a
+ 1: a
+ 2: a
+
+/(a)b(c)/
+ abc
+ 0: abc
+ 1: a
+ 2: c
+
+/a+b+c/
+ aabbabc
+ 0: abc
+
+/a{1,}b{1,}c/
+ aabbabc
+ 0: abc
+
+/a.+?c/
+ abcabc
+ 0: abc
+
+/(a+|b)*/
+ ab
+ 0: ab
+ 1: b
+
+/(a+|b){0,}/
+ ab
+ 0: ab
+ 1: b
+
+/(a+|b)+/
+ ab
+ 0: ab
+ 1: b
+
+/(a+|b){1,}/
+ ab
+ 0: ab
+ 1: b
+
+/(a+|b)?/
+ ab
+ 0: a
+ 1: a
+
+/(a+|b){0,1}/
+ ab
+ 0: a
+ 1: a
+
+/[^ab]*/
+ cde
+ 0: cde
+
+/abc/
+ *** Failers
+No match
+ b
+No match
+
+
+/a*/
+
+
+/([abc])*d/
+ abbbcd
+ 0: abbbcd
+ 1: c
+
+/([abc])*bcd/
+ abcd
+ 0: abcd
+ 1: a
+
+/a|b|c|d|e/
+ e
+ 0: e
+
+/(a|b|c|d|e)f/
+ ef
+ 0: ef
+ 1: e
+
+/abcd*efg/
+ abcdefg
+ 0: abcdefg
+
+/ab*/
+ xabyabbbz
+ 0: ab
+ xayabbbz
+ 0: a
+
+/(ab|cd)e/
+ abcde
+ 0: cde
+ 1: cd
+
+/[abhgefdc]ij/
+ hij
+ 0: hij
+
+/^(ab|cd)e/
+
+/(abc|)ef/
+ abcdef
+ 0: ef
+ 1:
+
+/(a|b)c*d/
+ abcd
+ 0: bcd
+ 1: b
+
+/(ab|ab*)bc/
+ abc
+ 0: abc
+ 1: a
+
+/a([bc]*)c*/
+ abc
+ 0: abc
+ 1: bc
+
+/a([bc]*)(c*d)/
+ abcd
+ 0: abcd
+ 1: bc
+ 2: d
+
+/a([bc]+)(c*d)/
+ abcd
+ 0: abcd
+ 1: bc
+ 2: d
+
+/a([bc]*)(c+d)/
+ abcd
+ 0: abcd
+ 1: b
+ 2: cd
+
+/a[bcd]*dcdcde/
+ adcdcde
+ 0: adcdcde
+
+/a[bcd]+dcdcde/
+ *** Failers
+No match
+ abcde
+No match
+ adcdcde
+No match
+
+/(ab|a)b*c/
+ abc
+ 0: abc
+ 1: ab
+
+/((a)(b)c)(d)/
+ abcd
+ 0: abcd
+ 1: abc
+ 2: a
+ 3: b
+ 4: d
+
+/[a-zA-Z_][a-zA-Z0-9_]*/
+ alpha
+ 0: alpha
+
+/^a(bc+|b[eh])g|.h$/
+ abh
+ 0: bh
+
+/(bc+d$|ef*g.|h?i(j|k))/
+ effgz
+ 0: effgz
+ 1: effgz
+ ij
+ 0: ij
+ 1: ij
+ 2: j
+ reffgz
+ 0: effgz
+ 1: effgz
+ *** Failers
+No match
+ effg
+No match
+ bcdd
+No match
+
+/((((((((((a))))))))))/
+ a
+ 0: a
+ 1: a
+ 2: a
+ 3: a
+ 4: a
+ 5: a
+ 6: a
+ 7: a
+ 8: a
+ 9: a
+10: a
+
+/((((((((((a))))))))))\10/
+ aa
+ 0: aa
+ 1: a
+ 2: a
+ 3: a
+ 4: a
+ 5: a
+ 6: a
+ 7: a
+ 8: a
+ 9: a
+10: a
+
+/(((((((((a)))))))))/
+ a
+ 0: a
+ 1: a
+ 2: a
+ 3: a
+ 4: a
+ 5: a
+ 6: a
+ 7: a
+ 8: a
+ 9: a
+
+/multiple words of text/
+ *** Failers
+No match
+ aa
+No match
+ uh-uh
+No match
+
+/multiple words/
+ multiple words, yeah
+ 0: multiple words
+
+/(.*)c(.*)/
+ abcde
+ 0: abcde
+ 1: ab
+ 2: de
+
+/\((.*), (.*)\)/
+ (a, b)
+ 0: (a, b)
+ 1: a
+ 2: b
+
+/[k]/
+
+/abcd/
+ abcd
+ 0: abcd
+
+/a(bc)d/
+ abcd
+ 0: abcd
+ 1: bc
+
+/a[-]?c/
+ ac
+ 0: ac
+
+/(abc)\1/
+ abcabc
+ 0: abcabc
+ 1: abc
+
+/([a-c]*)\1/
+ abcabc
+ 0: abcabc
+ 1: abc
+
+/(a)|\1/
+ a
+ 0: a
+ 1: a
+ *** Failers
+ 0: a
+ 1: a
+ ab
+ 0: a
+ 1: a
+ x
+No match
+
+/(([a-c])b*?\2)*/
+ ababbbcbc
+ 0: ababb
+ 1: bb
+ 2: b
+
+/(([a-c])b*?\2){3}/
+ ababbbcbc
+ 0: ababbbcbc
+ 1: cbc
+ 2: c
+
+/((\3|b)\2(a)x)+/
+ aaaxabaxbaaxbbax
+ 0: bbax
+ 1: bbax
+ 2: b
+ 3: a
+
+/((\3|b)\2(a)){2,}/
+ bbaababbabaaaaabbaaaabba
+ 0: bbaaaabba
+ 1: bba
+ 2: b
+ 3: a
+
+/abc/i
+ ABC
+ 0: ABC
+ XABCY
+ 0: ABC
+ ABABC
+ 0: ABC
+ *** Failers
+No match
+ aaxabxbaxbbx
+No match
+ XBC
+No match
+ AXC
+No match
+ ABX
+No match
+
+/ab*c/i
+ ABC
+ 0: ABC
+
+/ab*bc/i
+ ABC
+ 0: ABC
+ ABBC
+ 0: ABBC
+
+/ab*?bc/i
+ ABBBBC
+ 0: ABBBBC
+
+/ab{0,}?bc/i
+ ABBBBC
+ 0: ABBBBC
+
+/ab+?bc/i
+ ABBC
+ 0: ABBC
+
+/ab+bc/i
+ *** Failers
+No match
+ ABC
+No match
+ ABQ
+No match
+
+/ab{1,}bc/i
+
+/ab+bc/i
+ ABBBBC
+ 0: ABBBBC
+
+/ab{1,}?bc/i
+ ABBBBC
+ 0: ABBBBC
+
+/ab{1,3}?bc/i
+ ABBBBC
+ 0: ABBBBC
+
+/ab{3,4}?bc/i
+ ABBBBC
+ 0: ABBBBC
+
+/ab{4,5}?bc/i
+ *** Failers
+No match
+ ABQ
+No match
+ ABBBBC
+No match
+
+/ab??bc/i
+ ABBC
+ 0: ABBC
+ ABC
+ 0: ABC
+
+/ab{0,1}?bc/i
+ ABC
+ 0: ABC
+
+/ab??bc/i
+
+/ab??c/i
+ ABC
+ 0: ABC
+
+/ab{0,1}?c/i
+ ABC
+ 0: ABC
+
+/^abc$/i
+ ABC
+ 0: ABC
+ *** Failers
+No match
+ ABBBBC
+No match
+ ABCC
+No match
+
+/^abc/i
+ ABCC
+ 0: ABC
+
+/^abc$/i
+
+/abc$/i
+ AABC
+ 0: ABC
+
+/^/i
+ ABC
+ 0:
+
+/$/i
+ ABC
+ 0:
+
+/a.c/i
+ ABC
+ 0: ABC
+ AXC
+ 0: AXC
+
+/a.*?c/i
+ AXYZC
+ 0: AXYZC
+
+/a.*c/i
+ *** Failers
+No match
+ AABC
+ 0: AABC
+ AXYZD
+No match
+
+/a[bc]d/i
+ ABD
+ 0: ABD
+
+/a[b-d]e/i
+ ACE
+ 0: ACE
+ *** Failers
+No match
+ ABC
+No match
+ ABD
+No match
+
+/a[b-d]/i
+ AAC
+ 0: AC
+
+/a[-b]/i
+ A-
+ 0: A-
+
+/a[b-]/i
+ A-
+ 0: A-
+
+/a]/i
+ A]
+ 0: A]
+
+/a[]]b/i
+ A]B
+ 0: A]B
+
+/a[^bc]d/i
+ AED
+ 0: AED
+
+/a[^-b]c/i
+ ADC
+ 0: ADC
+ *** Failers
+No match
+ ABD
+No match
+ A-C
+No match
+
+/a[^]b]c/i
+ ADC
+ 0: ADC
+
+/ab|cd/i
+ ABC
+ 0: AB
+ ABCD
+ 0: AB
+
+/()ef/i
+ DEF
+ 0: EF
+ 1:
+
+/$b/i
+ *** Failers
+No match
+ A]C
+No match
+ B
+No match
+
+/a\(b/i
+ A(B
+ 0: A(B
+
+/a\(*b/i
+ AB
+ 0: AB
+ A((B
+ 0: A((B
+
+/a\\b/i
+ A\B
+No match
+
+/((a))/i
+ ABC
+ 0: A
+ 1: A
+ 2: A
+
+/(a)b(c)/i
+ ABC
+ 0: ABC
+ 1: A
+ 2: C
+
+/a+b+c/i
+ AABBABC
+ 0: ABC
+
+/a{1,}b{1,}c/i
+ AABBABC
+ 0: ABC
+
+/a.+?c/i
+ ABCABC
+ 0: ABC
+
+/a.*?c/i
+ ABCABC
+ 0: ABC
+
+/a.{0,5}?c/i
+ ABCABC
+ 0: ABC
+
+/(a+|b)*/i
+ AB
+ 0: AB
+ 1: B
+
+/(a+|b){0,}/i
+ AB
+ 0: AB
+ 1: B
+
+/(a+|b)+/i
+ AB
+ 0: AB
+ 1: B
+
+/(a+|b){1,}/i
+ AB
+ 0: AB
+ 1: B
+
+/(a+|b)?/i
+ AB
+ 0: A
+ 1: A
+
+/(a+|b){0,1}/i
+ AB
+ 0: A
+ 1: A
+
+/(a+|b){0,1}?/i
+ AB
+ 0:
+
+/[^ab]*/i
+ CDE
+ 0: CDE
+
+/abc/i
+
+/a*/i
+
+
+/([abc])*d/i
+ ABBBCD
+ 0: ABBBCD
+ 1: C
+
+/([abc])*bcd/i
+ ABCD
+ 0: ABCD
+ 1: A
+
+/a|b|c|d|e/i
+ E
+ 0: E
+
+/(a|b|c|d|e)f/i
+ EF
+ 0: EF
+ 1: E
+
+/abcd*efg/i
+ ABCDEFG
+ 0: ABCDEFG
+
+/ab*/i
+ XABYABBBZ
+ 0: AB
+ XAYABBBZ
+ 0: A
+
+/(ab|cd)e/i
+ ABCDE
+ 0: CDE
+ 1: CD
+
+/[abhgefdc]ij/i
+ HIJ
+ 0: HIJ
+
+/^(ab|cd)e/i
+ ABCDE
+No match
+
+/(abc|)ef/i
+ ABCDEF
+ 0: EF
+ 1:
+
+/(a|b)c*d/i
+ ABCD
+ 0: BCD
+ 1: B
+
+/(ab|ab*)bc/i
+ ABC
+ 0: ABC
+ 1: A
+
+/a([bc]*)c*/i
+ ABC
+ 0: ABC
+ 1: BC
+
+/a([bc]*)(c*d)/i
+ ABCD
+ 0: ABCD
+ 1: BC
+ 2: D
+
+/a([bc]+)(c*d)/i
+ ABCD
+ 0: ABCD
+ 1: BC
+ 2: D
+
+/a([bc]*)(c+d)/i
+ ABCD
+ 0: ABCD
+ 1: B
+ 2: CD
+
+/a[bcd]*dcdcde/i
+ ADCDCDE
+ 0: ADCDCDE
+
+/a[bcd]+dcdcde/i
+
+/(ab|a)b*c/i
+ ABC
+ 0: ABC
+ 1: AB
+
+/((a)(b)c)(d)/i
+ ABCD
+ 0: ABCD
+ 1: ABC
+ 2: A
+ 3: B
+ 4: D
+
+/[a-zA-Z_][a-zA-Z0-9_]*/i
+ ALPHA
+ 0: ALPHA
+
+/^a(bc+|b[eh])g|.h$/i
+ ABH
+ 0: BH
+
+/(bc+d$|ef*g.|h?i(j|k))/i
+ EFFGZ
+ 0: EFFGZ
+ 1: EFFGZ
+ IJ
+ 0: IJ
+ 1: IJ
+ 2: J
+ REFFGZ
+ 0: EFFGZ
+ 1: EFFGZ
+ *** Failers
+No match
+ ADCDCDE
+No match
+ EFFG
+No match
+ BCDD
+No match
+
+/((((((((((a))))))))))/i
+ A
+ 0: A
+ 1: A
+ 2: A
+ 3: A
+ 4: A
+ 5: A
+ 6: A
+ 7: A
+ 8: A
+ 9: A
+10: A
+
+/((((((((((a))))))))))\10/i
+ AA
+ 0: AA
+ 1: A
+ 2: A
+ 3: A
+ 4: A
+ 5: A
+ 6: A
+ 7: A
+ 8: A
+ 9: A
+10: A
+
+/(((((((((a)))))))))/i
+ A
+ 0: A
+ 1: A
+ 2: A
+ 3: A
+ 4: A
+ 5: A
+ 6: A
+ 7: A
+ 8: A
+ 9: A
+
+/(?:(?:(?:(?:(?:(?:(?:(?:(?:(a))))))))))/i
+ A
+ 0: A
+ 1: A
+
+/(?:(?:(?:(?:(?:(?:(?:(?:(?:(a|b|c))))))))))/i
+ C
+ 0: C
+ 1: C
+
+/multiple words of text/i
+ *** Failers
+No match
+ AA
+No match
+ UH-UH
+No match
+
+/multiple words/i
+ MULTIPLE WORDS, YEAH
+ 0: MULTIPLE WORDS
+
+/(.*)c(.*)/i
+ ABCDE
+ 0: ABCDE
+ 1: AB
+ 2: DE
+
+/\((.*), (.*)\)/i
+ (A, B)
+ 0: (A, B)
+ 1: A
+ 2: B
+
+/[k]/i
+
+/abcd/i
+ ABCD
+ 0: ABCD
+
+/a(bc)d/i
+ ABCD
+ 0: ABCD
+ 1: BC
+
+/a[-]?c/i
+ AC
+ 0: AC
+
+/(abc)\1/i
+ ABCABC
+ 0: ABCABC
+ 1: ABC
+
+/([a-c]*)\1/i
+ ABCABC
+ 0: ABCABC
+ 1: ABC
+
+/a(?!b)./
+ abad
+ 0: ad
+
+/a(?=d)./
+ abad
+ 0: ad
+
+/a(?=c|d)./
+ abad
+ 0: ad
+
+/a(?:b|c|d)(.)/
+ ace
+ 0: ace
+ 1: e
+
+/a(?:b|c|d)*(.)/
+ ace
+ 0: ace
+ 1: e
+
+/a(?:b|c|d)+?(.)/
+ ace
+ 0: ace
+ 1: e
+ acdbcdbe
+ 0: acd
+ 1: d
+
+/a(?:b|c|d)+(.)/
+ acdbcdbe
+ 0: acdbcdbe
+ 1: e
+
+/a(?:b|c|d){2}(.)/
+ acdbcdbe
+ 0: acdb
+ 1: b
+
+/a(?:b|c|d){4,5}(.)/
+ acdbcdbe
+ 0: acdbcdb
+ 1: b
+
+/a(?:b|c|d){4,5}?(.)/
+ acdbcdbe
+ 0: acdbcd
+ 1: d
+
+/((foo)|(bar))*/
+ foobar
+ 0: foobar
+ 1: bar
+ 2: foo
+ 3: bar
+
+/a(?:b|c|d){6,7}(.)/
+ acdbcdbe
+ 0: acdbcdbe
+ 1: e
+
+/a(?:b|c|d){6,7}?(.)/
+ acdbcdbe
+ 0: acdbcdbe
+ 1: e
+
+/a(?:b|c|d){5,6}(.)/
+ acdbcdbe
+ 0: acdbcdbe
+ 1: e
+
+/a(?:b|c|d){5,6}?(.)/
+ acdbcdbe
+ 0: acdbcdb
+ 1: b
+
+/a(?:b|c|d){5,7}(.)/
+ acdbcdbe
+ 0: acdbcdbe
+ 1: e
+
+/a(?:b|c|d){5,7}?(.)/
+ acdbcdbe
+ 0: acdbcdb
+ 1: b
+
+/a(?:b|(c|e){1,2}?|d)+?(.)/
+ ace
+ 0: ace
+ 1: c
+ 2: e
+
+/^(.+)?B/
+ AB
+ 0: AB
+ 1: A
+
+/^([^a-z])|(\^)$/
+ .
+ 0: .
+ 1: .
+
+/^[<>]&/
+ <&OUT
+ 0: <&
+
+/^(a\1?){4}$/
+ aaaaaaaaaa
+ 0: aaaaaaaaaa
+ 1: aaaa
+ *** Failers
+No match
+ AB
+No match
+ aaaaaaaaa
+No match
+ aaaaaaaaaaa
+No match
+
+/^(a(?(1)\1)){4}$/
+ aaaaaaaaaa
+ 0: aaaaaaaaaa
+ 1: aaaa
+ *** Failers
+No match
+ aaaaaaaaa
+No match
+ aaaaaaaaaaa
+No match
+
+/(?:(f)(o)(o)|(b)(a)(r))*/
+ foobar
+ 0: foobar
+ 1: f
+ 2: o
+ 3: o
+ 4: b
+ 5: a
+ 6: r
+
+/(?<=a)b/
+ ab
+ 0: b
+ *** Failers
+No match
+ cb
+No match
+ b
+No match
+
+/(?<!c)b/
+ ab
+ 0: b
+ b
+ 0: b
+ b
+ 0: b
+
+/(?:..)*a/
+ aba
+ 0: aba
+
+/(?:..)*?a/
+ aba
+ 0: a
+
+/^(?:b|a(?=(.)))*\1/
+ abc
+ 0: ab
+ 1: b
+
+/^(){3,5}/
+ abc
+ 0:
+ 1:
+
+/^(a+)*ax/
+ aax
+ 0: aax
+ 1: a
+
+/^((a|b)+)*ax/
+ aax
+ 0: aax
+ 1: a
+ 2: a
+
+/^((a|bc)+)*ax/
+ aax
+ 0: aax
+ 1: a
+ 2: a
+
+/(a|x)*ab/
+ cab
+ 0: ab
+
+/(a)*ab/
+ cab
+ 0: ab
+
+/(?:(?i)a)b/
+ ab
+ 0: ab
+
+/((?i)a)b/
+ ab
+ 0: ab
+ 1: a
+
+/(?:(?i)a)b/
+ Ab
+ 0: Ab
+
+/((?i)a)b/
+ Ab
+ 0: Ab
+ 1: A
+
+/(?:(?i)a)b/
+ *** Failers
+No match
+ cb
+No match
+ aB
+No match
+
+/((?i)a)b/
+
+/(?i:a)b/
+ ab
+ 0: ab
+
+/((?i:a))b/
+ ab
+ 0: ab
+ 1: a
+
+/(?i:a)b/
+ Ab
+ 0: Ab
+
+/((?i:a))b/
+ Ab
+ 0: Ab
+ 1: A
+
+/(?i:a)b/
+ *** Failers
+No match
+ aB
+No match
+ aB
+No match
+
+/((?i:a))b/
+
+/(?:(?-i)a)b/i
+ ab
+ 0: ab
+
+/((?-i)a)b/i
+ ab
+ 0: ab
+ 1: a
+
+/(?:(?-i)a)b/i
+ aB
+ 0: aB
+
+/((?-i)a)b/i
+ aB
+ 0: aB
+ 1: a
+
+/(?:(?-i)a)b/i
+ *** Failers
+No match
+ aB
+ 0: aB
+ Ab
+No match
+
+/((?-i)a)b/i
+
+/(?:(?-i)a)b/i
+ aB
+ 0: aB
+
+/((?-i)a)b/i
+ aB
+ 0: aB
+ 1: a
+
+/(?:(?-i)a)b/i
+ *** Failers
+No match
+ Ab
+No match
+ AB
+No match
+
+/((?-i)a)b/i
+
+/(?-i:a)b/i
+ ab
+ 0: ab
+
+/((?-i:a))b/i
+ ab
+ 0: ab
+ 1: a
+
+/(?-i:a)b/i
+ aB
+ 0: aB
+
+/((?-i:a))b/i
+ aB
+ 0: aB
+ 1: a
+
+/(?-i:a)b/i
+ *** Failers
+No match
+ AB
+No match
+ Ab
+No match
+
+/((?-i:a))b/i
+
+/(?-i:a)b/i
+ aB
+ 0: aB
+
+/((?-i:a))b/i
+ aB
+ 0: aB
+ 1: a
+
+/(?-i:a)b/i
+ *** Failers
+No match
+ Ab
+No match
+ AB
+No match
+
+/((?-i:a))b/i
+
+/((?-i:a.))b/i
+ *** Failers
+No match
+ AB
+No match
+ a\nB
+No match
+
+/((?s-i:a.))b/i
+ a\nB
+ 0: a\x0aB
+ 1: a\x0a
+
+/(?:c|d)(?:)(?:a(?:)(?:b)(?:b(?:))(?:b(?:)(?:b)))/
+ cabbbb
+ 0: cabbbb
+
+/(?:c|d)(?:)(?:aaaaaaaa(?:)(?:bbbbbbbb)(?:bbbbbbbb(?:))(?:bbbbbbbb(?:)(?:bbbbbbbb)))/
+ caaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
+ 0: caaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
+
+/(ab)\d\1/i
+ Ab4ab
+ 0: Ab4ab
+ 1: Ab
+ ab4Ab
+ 0: ab4Ab
+ 1: ab
+
+/foo\w*\d{4}baz/
+ foobar1234baz
+ 0: foobar1234baz
+
+/x(~~)*(?:(?:F)?)?/
+ x~~
+ 0: x~~
+ 1: ~~
+
+/^a(?#xxx){3}c/
+ aaac
+ 0: aaac
+
+/^a (?#xxx) (?#yyy) {3}c/x
+ aaac
+ 0: aaac
+
+/(?<![cd])b/
+ *** Failers
+No match
+ B\nB
+No match
+ dbcb
+No match
+
+/(?<![cd])[ab]/
+ dbaacb
+ 0: a
+
+/(?<!(c|d))b/
+
+/(?<!(c|d))[ab]/
+ dbaacb
+ 0: a
+
+/(?<!cd)[ab]/
+ cdaccb
+ 0: b
+
+/^(?:a?b?)*$/
+ *** Failers
+No match
+ dbcb
+No match
+ a--
+No match
+
+/((?s)^a(.))((?m)^b$)/
+ a\nb\nc\n
+ 0: a\x0ab
+ 1: a\x0a
+ 2: \x0a
+ 3: b
+
+/((?m)^b$)/
+ a\nb\nc\n
+ 0: b
+ 1: b
+
+/(?m)^b/
+ a\nb\n
+ 0: b
+
+/(?m)^(b)/
+ a\nb\n
+ 0: b
+ 1: b
+
+/((?m)^b)/
+ a\nb\n
+ 0: b
+ 1: b
+
+/\n((?m)^b)/
+ a\nb\n
+ 0: \x0ab
+ 1: b
+
+/((?s).)c(?!.)/
+ a\nb\nc\n
+ 0: \x0ac
+ 1: \x0a
+ a\nb\nc\n
+ 0: \x0ac
+ 1: \x0a
+
+/((?s)b.)c(?!.)/
+ a\nb\nc\n
+ 0: b\x0ac
+ 1: b\x0a
+ a\nb\nc\n
+ 0: b\x0ac
+ 1: b\x0a
+
+/^b/
+
+/()^b/
+ *** Failers
+No match
+ a\nb\nc\n
+No match
+ a\nb\nc\n
+No match
+
+/((?m)^b)/
+ a\nb\nc\n
+ 0: b
+ 1: b
+
+/(?(1)a|b)/
+
+/(?(1)b|a)/
+ a
+ 0: a
+
+/(x)?(?(1)a|b)/
+ *** Failers
+No match
+ a
+No match
+ a
+No match
+
+/(x)?(?(1)b|a)/
+ a
+ 0: a
+
+/()?(?(1)b|a)/
+ a
+ 0: a
+
+/()(?(1)b|a)/
+
+/()?(?(1)a|b)/
+ a
+ 0: a
+ 1:
+
+/^(\()?blah(?(1)(\)))$/
+ (blah)
+ 0: (blah)
+ 1: (
+ 2: )
+ blah
+ 0: blah
+ *** Failers
+No match
+ a
+No match
+ blah)
+No match
+ (blah
+No match
+
+/^(\(+)?blah(?(1)(\)))$/
+ (blah)
+ 0: (blah)
+ 1: (
+ 2: )
+ blah
+ 0: blah
+ *** Failers
+No match
+ blah)
+No match
+ (blah
+No match
+
+/(?(?!a)a|b)/
+
+/(?(?!a)b|a)/
+ a
+ 0: a
+
+/(?(?=a)b|a)/
+ *** Failers
+No match
+ a
+No match
+ a
+No match
+
+/(?(?=a)a|b)/
+ a
+ 0: a
+
+/(?=(a+?))(\1ab)/
+ aaab
+ 0: aab
+ 1: a
+ 2: aab
+
+/^(?=(a+?))\1ab/
+
+/(\w+:)+/
+ one:
+ 0: one:
+ 1: one:
+
+/$(?<=^(a))/
+ a
+ 0:
+ 1: a
+
+/(?=(a+?))(\1ab)/
+ aaab
+ 0: aab
+ 1: a
+ 2: aab
+
+/^(?=(a+?))\1ab/
+ *** Failers
+No match
+ aaab
+No match
+ aaab
+No match
+
+/([\w:]+::)?(\w+)$/
+ abcd
+ 0: abcd
+ 1: <unset>
+ 2: abcd
+ xy:z:::abcd
+ 0: xy:z:::abcd
+ 1: xy:z:::
+ 2: abcd
+
+/^[^bcd]*(c+)/
+ aexycd
+ 0: aexyc
+ 1: c
+
+/(a*)b+/
+ caab
+ 0: aab
+ 1: aa
+
+/([\w:]+::)?(\w+)$/
+ abcd
+ 0: abcd
+ 1: <unset>
+ 2: abcd
+ xy:z:::abcd
+ 0: xy:z:::abcd
+ 1: xy:z:::
+ 2: abcd
+ *** Failers
+ 0: Failers
+ 1: <unset>
+ 2: Failers
+ abcd:
+No match
+ abcd:
+No match
+
+/^[^bcd]*(c+)/
+ aexycd
+ 0: aexyc
+ 1: c
+
+/(>a+)ab/
+
+/(?>a+)b/
+ aaab
+ 0: aaab
+
+/([[:]+)/
+ a:[b]:
+ 0: :[
+ 1: :[
+
+/([[=]+)/
+ a=[b]=
+ 0: =[
+ 1: =[
+
+/([[.]+)/
+ a.[b].
+ 0: .[
+ 1: .[
+
+/((?>a+)b)/
+ aaab
+ 0: aaab
+ 1: aaab
+
+/(?>(a+))b/
+ aaab
+ 0: aaab
+ 1: aaa
+
+/((?>[^()]+)|\([^()]*\))+/
+ ((abc(ade)ufh()()x
+ 0: abc(ade)ufh()()x
+ 1: x
+
+/a\Z/
+ *** Failers
+No match
+ aaab
+No match
+ a\nb\n
+No match
+
+/b\Z/
+ a\nb\n
+ 0: b
+
+/b\z/
+
+/b\Z/
+ a\nb
+ 0: b
+
+/b\z/
+ a\nb
+ 0: b
+ *** Failers
+No match
+
+/^(?>(?(1)\.|())[^\W_](?>[a-z0-9-]*[^\W_])?)+$/
+ a
+ 0: a
+ 1:
+ abc
+ 0: abc
+ 1:
+ a-b
+ 0: a-b
+ 1:
+ 0-9
+ 0: 0-9
+ 1:
+ a.b
+ 0: a.b
+ 1:
+ 5.6.7
+ 0: 5.6.7
+ 1:
+ the.quick.brown.fox
+ 0: the.quick.brown.fox
+ 1:
+ a100.b200.300c
+ 0: a100.b200.300c
+ 1:
+ 12-ab.1245
+ 0: 12-ab.1245
+ 1:
+ ***Failers
+No match
+ \
+No match
+ .a
+No match
+ -a
+No match
+ a-
+No match
+ a.
+No match
+ a_b
+No match
+ a.-
+No match
+ a..
+No match
+ ab..bc
+No match
+ the.quick.brown.fox-
+No match
+ the.quick.brown.fox.
+No match
+ the.quick.brown.fox_
+No match
+ the.quick.brown.fox+
+No match
+
+/(?>.*)(?<=(abcd|wxyz))/
+ alphabetabcd
+ 0: alphabetabcd
+ 1: abcd
+ endingwxyz
+ 0: endingwxyz
+ 1: wxyz
+ *** Failers
+No match
+ a rather long string that doesn't end with one of them
+No match
+
+/word (?>(?:(?!otherword)[a-zA-Z0-9]+ ){0,30})otherword/
+ word cat dog elephant mussel cow horse canary baboon snake shark otherword
+ 0: word cat dog elephant mussel cow horse canary baboon snake shark otherword
+ word cat dog elephant mussel cow horse canary baboon snake shark
+No match
+
+/word (?>[a-zA-Z0-9]+ ){0,30}otherword/
+ word cat dog elephant mussel cow horse canary baboon snake shark the quick brown fox and the lazy dog and several other words getting close to thirty by now I hope
+No match
+
+/(?<=\d{3}(?!999))foo/
+ 999foo
+ 0: foo
+ 123999foo
+ 0: foo
+ *** Failers
+No match
+ 123abcfoo
+No match
+
+/(?<=(?!...999)\d{3})foo/
+ 999foo
+ 0: foo
+ 123999foo
+ 0: foo
+ *** Failers
+No match
+ 123abcfoo
+No match
+
+/(?<=\d{3}(?!999)...)foo/
+ 123abcfoo
+ 0: foo
+ 123456foo
+ 0: foo
+ *** Failers
+No match
+ 123999foo
+No match
+
+/(?<=\d{3}...)(?<!999)foo/
+ 123abcfoo
+ 0: foo
+ 123456foo
+ 0: foo
+ *** Failers
+No match
+ 123999foo
+No match
+
+/<a[\s]+href[\s]*=[\s]* # find <a href=
+ ([\"\'])? # find single or double quote
+ (?(1) (.*?)\1 | ([^\s]+)) # if quote found, match up to next matching
+ # quote, otherwise match up to next space
+/isx
+ <a href=abcd xyz
+ 0: <a href=abcd
+ 1: <unset>
+ 2: <unset>
+ 3: abcd
+ <a href=\"abcd xyz pqr\" cats
+ 0: <a href="abcd xyz pqr"
+ 1: "
+ 2: abcd xyz pqr
+ <a href=\'abcd xyz pqr\' cats
+ 0: <a href='abcd xyz pqr'
+ 1: '
+ 2: abcd xyz pqr
+
+/<a\s+href\s*=\s* # find <a href=
+ (["'])? # find single or double quote
+ (?(1) (.*?)\1 | (\S+)) # if quote found, match up to next matching
+ # quote, otherwise match up to next space
+/isx
+ <a href=abcd xyz
+ 0: <a href=abcd
+ 1: <unset>
+ 2: <unset>
+ 3: abcd
+ <a href=\"abcd xyz pqr\" cats
+ 0: <a href="abcd xyz pqr"
+ 1: "
+ 2: abcd xyz pqr
+ <a href = \'abcd xyz pqr\' cats
+ 0: <a href = 'abcd xyz pqr'
+ 1: '
+ 2: abcd xyz pqr
+
+/<a\s+href(?>\s*)=(?>\s*) # find <a href=
+ (["'])? # find single or double quote
+ (?(1) (.*?)\1 | (\S+)) # if quote found, match up to next matching
+ # quote, otherwise match up to next space
+/isx
+ <a href=abcd xyz
+ 0: <a href=abcd
+ 1: <unset>
+ 2: <unset>
+ 3: abcd
+ <a href=\"abcd xyz pqr\" cats
+ 0: <a href="abcd xyz pqr"
+ 1: "
+ 2: abcd xyz pqr
+ <a href = \'abcd xyz pqr\' cats
+ 0: <a href = 'abcd xyz pqr'
+ 1: '
+ 2: abcd xyz pqr
+
+/ End of test input /
+
--- /dev/null
+PCRE version 3.1 09-Feb-2000
+
+/^[\w]+/
+ *** Failers
+No match
+ École
+No match
+
+/^[\w]+/Lfr
+ École
+ 0: École
+
+/^[\w]+/
+ *** Failers
+No match
+ École
+No match
+
+/^[\W]+/
+ École
+ 0: \xc9
+
+/^[\W]+/Lfr
+ *** Failers
+ 0: ***
+ École
+No match
+
+/[\b]/
+ \b
+ 0: \x08
+ *** Failers
+No match
+ a
+No match
+
+/[\b]/Lfr
+ \b
+ 0: \x08
+ *** Failers
+No match
+ a
+No match
+
+/^\w+/
+ *** Failers
+No match
+ École
+No match
+
+/^\w+/Lfr
+ École
+ 0: École
+
+/(.+)\b(.+)/
+ École
+ 0: \xc9cole
+ 1: \xc9
+ 2: cole
+
+/(.+)\b(.+)/Lfr
+ *** Failers
+ 0: *** Failers
+ 1: ***
+ 2: Failers
+ École
+No match
+
+/École/i
+ École
+ 0: \xc9cole
+ *** Failers
+No match
+ école
+No match
+
+/École/iLfr
+ École
+ 0: École
+ école
+ 0: école
+
+/\w/IS
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+Starting character set: 0 1 2 3 4 5 6 7 8 9 A B C D E F G H I J K L M N O P
+ Q R S T U V W X Y Z _ a b c d e f g h i j k l m n o p q r s t u v w x y z
+
+/\w/ISLfr
+Capturing subpattern count = 0
+No options
+No first char
+No need char
+Starting character set: 0 1 2 3 4 5 6 7 8 9 A B C D E F G H I J K L M N O P
+ Q R S T U V W X Y Z _ a b c d e f g h i j k l m n o p q r s t u v w x y z
+ À Á Â Ã Ä Å Æ Ç È É Ê Ë Ì Í Î Ï Ð Ñ Ò Ó Ô Õ Ö Ø Ù Ú Û Ü Ý Þ ß à á â ã ä å
+ æ ç è é ê ë ì í î ï ð ñ ò ó ô õ ö ø ù ú û ü ý þ ÿ
+
+/^[\xc8-\xc9]/iLfr
+ École
+ 0: É
+ école
+ 0: é
+
+/^[\xc8-\xc9]/Lfr
+ École
+ 0: É
+ *** Failers
+No match
+ école
+No match
+
+
projects / php / commitdiff