separate text files for the pcregrep and pcretest commands.
-----------------------------------------------------------------------------
-NAME
- PCRE - Perl-compatible regular expressions
+PCRE(3) PCRE(3)
+
+NAME
+ PCRE - Perl-compatible regular expressions
+
DESCRIPTION
- The PCRE library is a set of functions that implement regu-
- lar expression pattern matching using the same syntax and
- semantics as Perl, with just a few differences. The current
- implementation of PCRE (release 4.x) corresponds approxi-
- mately with Perl 5.8, including support for UTF-8 encoded
- strings. However, this support has to be explicitly
- enabled; it is not the default.
+ The PCRE library is a set of functions that implement regular expres-
+ sion pattern matching using the same syntax and semantics as Perl, with
+ just a few differences. The current implementation of PCRE (release
+ 4.x) corresponds approximately with Perl 5.8, including support for
+ UTF-8 encoded strings. However, this support has to be explicitly
+ enabled; it is not the default.
- PCRE is written in C and released as a C library. However, a
- number of people have written wrappers and interfaces of
- various kinds. A C++ class is included in these contribu-
- tions, which can be found in the Contrib directory at the
- primary FTP site, which is:
+ PCRE is written in C and released as a C library. However, a number of
+ people have written wrappers and interfaces of various kinds. A C++
+ class is included in these contributions, which can be found in the
+ Contrib directory at the primary FTP site, which is:
- ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre
+ ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre
- Details of exactly which Perl regular expression features
- are and are not supported by PCRE are given in separate
- documents. See the pcrepattern and pcrecompat pages.
+ Details of exactly which Perl regular expression features are and are
+ not supported by PCRE are given in separate documents. See the pcrepat-
+ tern and pcrecompat pages.
- Some features of PCRE can be included, excluded, or changed
- when the library is built. The pcre_config() function makes
- it possible for a client to discover which features are
- available. Documentation about building PCRE for various
- operating systems can be found in the README file in the
- source distribution.
+ Some features of PCRE can be included, excluded, or changed when the
+ library is built. The pcre_config() function makes it possible for a
+ client to discover which features are available. Documentation about
+ building PCRE for various operating systems can be found in the README
+ file in the source distribution.
USER DOCUMENTATION
- The user documentation for PCRE has been split up into a
- number of different sections. In the "man" format, each of
- these is a separate "man page". In the HTML format, each is
- a separate page, linked from the index page. In the plain
- text format, all the sections are concatenated, for ease of
- searching. The sections are as follows:
-
- pcre this document
- pcreapi details of PCRE's native API
- pcrebuild options for building PCRE
- pcrecallout details of the callout feature
- pcrecompat discussion of Perl compatibility
- pcregrep description of the pcregrep command
- pcrepattern syntax and semantics of supported
- regular expressions
- pcreperform discussion of performance issues
- pcreposix the POSIX-compatible API
- pcresample discussion of the sample program
- pcretest the pcretest testing command
-
- In addition, in the "man" and HTML formats, there is a short
- page for each library function, listing its arguments and
- results.
+ The user documentation for PCRE has been split up into a number of dif-
+ ferent sections. In the "man" format, each of these is a separate "man
+ page". In the HTML format, each is a separate page, linked from the
+ index page. In the plain text format, all the sections are concate-
+ nated, for ease of searching. The sections are as follows:
+
+ pcre this document
+ pcreapi details of PCRE's native API
+ pcrebuild options for building PCRE
+ pcrecallout details of the callout feature
+ pcrecompat discussion of Perl compatibility
+ pcregrep description of the pcregrep command
+ pcrepattern syntax and semantics of supported
+ regular expressions
+ pcreperform discussion of performance issues
+ pcreposix the POSIX-compatible API
+ pcresample discussion of the sample program
+ pcretest the pcretest testing command
+
+ In addition, in the "man" and HTML formats, there is a short page for
+ each library function, listing its arguments and results.
LIMITATIONS
- There are some size limitations in PCRE but it is hoped that
- they will never in practice be relevant.
+ 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 if PCRE is compiled with the default internal linkage
- size of 2. If you want to process regular expressions that
- are truly enormous, you can compile PCRE with an internal
- linkage size of 3 or 4 (see the README file in the source
- distribution and the pcrebuild documentation for details).
- If these cases the limit is substantially larger. However,
- the speed of execution will be slower.
+ The maximum length of a compiled pattern is 65539 (sic) bytes if PCRE
+ is compiled with the default internal linkage size of 2. If you want to
+ process regular expressions that are truly enormous, you can compile
+ PCRE with an internal linkage size of 3 or 4 (see the README file in
+ the source distribution and the pcrebuild documentation for details).
+ If these cases the limit is substantially larger. However, the speed
+ of execution will be slower.
- All values in repeating quantifiers must be less than 65536.
- The maximum number of capturing subpatterns is 65535.
+ All values in repeating quantifiers must be less than 65536. The maxi-
+ mum number of capturing subpatterns is 65535.
- There is no limit to the number of non-capturing subpat-
- terns, but the maximum depth of nesting of all kinds of
- parenthesized subpattern, including capturing subpatterns,
- assertions, and other types of subpattern, is 200.
+ There is no limit to the number of non-capturing subpatterns, but the
+ maximum depth of nesting of all kinds of parenthesized subpattern,
+ including capturing subpatterns, assertions, and other types of subpat-
+ tern, 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.
+ The maximum length of a subject string is the largest positive number
+ that an integer variable can hold. However, PCRE uses recursion to han-
+ dle subpatterns and indefinite repetition. This means that the avail-
+ able stack space may limit the size of a subject string that can be
+ processed by certain patterns.
UTF-8 SUPPORT
- Starting at release 3.3, PCRE has had some support for char-
- acter strings encoded in the UTF-8 format. For release 4.0
- this has been greatly extended to cover most common require-
- ments.
+ Starting at release 3.3, PCRE has had some support for character
+ strings encoded in the UTF-8 format. For release 4.0 this has been
+ greatly extended to cover most common requirements.
- In order process UTF-8 strings, you must build PCRE to
- include UTF-8 support in the code, and, in addition, you
- must call pcre_compile() with the PCRE_UTF8 option flag.
- When you do this, both the pattern and any subject strings
- that are matched against it are treated as UTF-8 strings
- instead of just strings of bytes.
+ In order process UTF-8 strings, you must build PCRE to include UTF-8
+ support in the code, and, in addition, you must call pcre_compile()
+ with the PCRE_UTF8 option flag. When you do this, both the pattern and
+ any subject strings that are matched against it are treated as UTF-8
+ strings instead of just strings of bytes.
- If you compile PCRE with UTF-8 support, but do not use it at
- run time, the library will be a bit bigger, but the addi-
- tional run time overhead is limited to testing the PCRE_UTF8
- flag in several places, so should not be very large.
+ If you compile PCRE with UTF-8 support, but do not use it at run time,
+ the library will be a bit bigger, but the additional run time overhead
+ is limited to testing the PCRE_UTF8 flag in several places, so should
+ not be very large.
- The following comments apply when PCRE is running in UTF-8
- mode:
+ The following comments apply when PCRE is running in UTF-8 mode:
- 1. PCRE assumes that the strings it is given contain valid
- UTF-8 codes. It does not diagnose invalid UTF-8 strings. If
- you pass invalid UTF-8 strings to PCRE, the results are
- undefined.
+ 1. When you set the PCRE_UTF8 flag, the strings passed as patterns and
+ subjects are checked for validity on entry to the relevant functions.
+ If an invalid UTF-8 string is passed, an error return is given. In some
+ situations, you may already know that your strings are valid, and
+ therefore want to skip these checks in order to improve performance. If
+ you set the PCRE_NO_UTF8_CHECK flag at compile time or at run time,
+ PCRE assumes that the pattern or subject it is given (respectively)
+ contains only valid UTF-8 codes. In this case, it does not diagnose an
+ invalid UTF-8 string. If you pass an invalid UTF-8 string to PCRE when
+ PCRE_NO_UTF8_CHECK is set, the results are undefined. Your program may
+ crash.
- 2. In a pattern, the escape sequence \x{...}, where the con-
- tents of the braces is a string of hexadecimal digits, is
- interpreted as a UTF-8 character whose code number is the
- given hexadecimal number, for example: \x{1234}. If a non-
- hexadecimal digit appears between the braces, the item is
- not recognized. This escape sequence can be used either as
- a literal, or within a character class.
+ 2. In a pattern, the escape sequence \x{...}, where the contents of the
+ braces is a string of hexadecimal digits, is interpreted as a UTF-8
+ character whose code number is the given hexadecimal number, for exam-
+ ple: \x{1234}. If a non-hexadecimal digit appears between the braces,
+ the item is not recognized. This escape sequence can be used either as
+ a literal, or within a character class.
- 3. The original hexadecimal escape sequence, \xhh, matches a
- two-byte UTF-8 character if the value is greater than 127.
+ 3. The original hexadecimal escape sequence, \xhh, matches a two-byte
+ UTF-8 character if the value is greater than 127.
- 4. Repeat quantifiers apply to complete UTF-8 characters,
- not to individual bytes, for example: \x{100}{3}.
+ 4. Repeat quantifiers apply to complete UTF-8 characters, not to indi-
+ vidual bytes, for example: \x{100}{3}.
- 5. The dot metacharacter matches one UTF-8 character instead
- of a single byte.
+ 5. The dot metacharacter matches one UTF-8 character instead of a
+ single byte.
- 6. The escape sequence \C can be used to match a single byte
- in UTF-8 mode, but its use can lead to some strange effects.
+ 6. The escape sequence \C can be used to match a single byte in UTF-8
+ mode, but its use can lead to some strange effects.
- 7. The character escapes \b, \B, \d, \D, \s, \S, \w, and \W
- correctly test characters of any code value, but the charac-
- ters that PCRE recognizes as digits, spaces, or word charac-
- ters remain the same set as before, all with values less
- than 256.
+ 7. The character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly
+ test characters of any code value, but the characters that PCRE recog-
+ nizes as digits, spaces, or word characters remain the same set as
+ before, all with values less than 256.
- 8. Case-insensitive matching applies only to characters
- whose values are less than 256. PCRE does not support the
- notion of "case" for higher-valued characters.
+ 8. Case-insensitive matching applies only to characters whose values
+ are less than 256. PCRE does not support the notion of "case" for
+ higher-valued characters.
- 9. PCRE does not support the use of Unicode tables and pro-
- perties or the Perl escapes \p, \P, and \X.
+ 9. PCRE does not support the use of Unicode tables and properties or
+ the Perl escapes \p, \P, and \X.
AUTHOR
- Philip Hazel <ph10@cam.ac.uk>
- University Computing Service,
- Cambridge CB2 3QG, England.
- Phone: +44 1223 334714
+
Philip Hazel <ph10@cam.ac.uk>
+ University Computing Service,
+ Cambridge CB2 3QG, England.
+ Phone: +44 1223 334714
-Last updated: 04 February 2003
+Last updated: 20 August 2003
Copyright (c) 1997-2003 University of Cambridge.
-----------------------------------------------------------------------------
-NAME
- PCRE - Perl-compatible regular expressions
+PCRE(3) PCRE(3)
+
+NAME
+ PCRE - Perl-compatible regular expressions
+
PCRE BUILD-TIME OPTIONS
- This document describes the optional features of PCRE that
- can be selected when the library is compiled. They are all
- selected, or deselected, by providing options to the config-
- ure script which is run before the make command. The com-
- plete list of options for configure (which includes the
- standard ones such as the selection of the installation
- directory) can be obtained by running
+ This document describes the optional features of PCRE that can be
+ selected when the library is compiled. They are all selected, or dese-
+ lected, by providing options to the configure script which is run
+ before the make command. The complete list of options for configure
+ (which includes the standard ones such as the selection of the instal-
+ lation directory) can be obtained by running
- ./configure --help
+ ./configure --help
- The following sections describe certain options whose names
- begin with --enable or --disable. These settings specify
- changes to the defaults for the configure command. Because
- of the way that configure works, --enable and --disable
- always come in pairs, so the complementary option always
- exists as well, but as it specifies the default, it is not
- described.
+ The following sections describe certain options whose names begin with
+ --enable or --disable. These settings specify changes to the defaults
+ for the configure command. Because of the way that configure works,
+ --enable and --disable always come in pairs, so the complementary
+ option always exists as well, but as it specifies the default, it is
+ not described.
UTF-8 SUPPORT
- To build PCRE with support for UTF-8 character strings, add
+ To build PCRE with support for UTF-8 character strings, add
- --enable-utf8
+ --enable-utf8
- to the configure command. Of itself, this does not make PCRE
- treat strings as UTF-8. As well as compiling PCRE with this
- option, you also have have to set the PCRE_UTF8 option when
- you call the pcre_compile() function.
+ to the configure command. Of itself, this does not make PCRE treat
+ strings as UTF-8. As well as compiling PCRE with this option, you also
+ have have to set the PCRE_UTF8 option when you call the pcre_compile()
+ function.
CODE VALUE OF NEWLINE
- By default, PCRE treats character 10 (linefeed) as the new-
- line character. This is the normal newline character on
- Unix-like systems. You can compile PCRE to use character 13
- (carriage return) instead by adding
+ By default, PCRE treats character 10 (linefeed) as the newline charac-
+ ter. This is the normal newline character on Unix-like systems. You can
+ compile PCRE to use character 13 (carriage return) instead by adding
- --enable-newline-is-cr
+ --enable-newline-is-cr
- to the configure command. For completeness there is also a
- --enable-newline-is-lf option, which explicitly specifies
- linefeed as the newline character.
+ to the configure command. For completeness there is also a --enable-
+ newline-is-lf option, which explicitly specifies linefeed as the new-
+ line character.
BUILDING SHARED AND STATIC LIBRARIES
- The PCRE building process uses libtool to build both shared
- and static Unix libraries by default. You can suppress one
- of these by adding one of
+ The PCRE building process uses libtool to build both shared and static
+ Unix libraries by default. You can suppress one of these by adding one
+ of
- --disable-shared
- --disable-static
+ --disable-shared
+ --disable-static
- to the configure command, as required.
+ to the configure command, as required.
POSIX MALLOC USAGE
- When PCRE is called through the POSIX interface (see the
- pcreposix documentation), additional working storage is
- required for holding the pointers to capturing substrings
- because PCRE requires three integers per substring, whereas
- the POSIX interface provides only two. If the number of
- expected substrings is small, the wrapper function uses
- space on the stack, because this is faster than using mal-
- loc() for each call. The default threshold above which the
- stack is no longer used is 10; it can be changed by adding a
- setting such as
+ When PCRE is called through the POSIX interface (see the pcreposix
+ documentation), additional working storage is required for holding the
+ pointers to capturing substrings because PCRE requires three integers
+ per substring, whereas the POSIX interface provides only two. If the
+ number of expected substrings is small, the wrapper function uses space
+ on the stack, because this is faster than using malloc() for each call.
+ The default threshold above which the stack is no longer used is 10; it
+ can be changed by adding a setting such as
- --with-posix-malloc-threshold=20
+ --with-posix-malloc-threshold=20
- to the configure command.
+ to the configure command.
LIMITING PCRE RESOURCE USAGE
- Internally, PCRE has a function called match() which it
- calls repeatedly (possibly recursively) when performing a
- matching operation. By limiting the number of times this
- function may be called, a limit can be placed on the
- resources used by a single call to pcre_exec(). The limit
- can be changed at run time, as described in the pcreapi
- documentation. The default is 10 million, but this can be
- changed by adding a setting such as
+ Internally, PCRE has a function called match() which it calls repeat-
+ edly (possibly recursively) when performing a matching operation. By
+ limiting the number of times this function may be called, a limit can
+ be placed on the resources used by a single call to pcre_exec(). The
+ limit can be changed at run time, as described in the pcreapi documen-
+ tation. The default is 10 million, but this can be changed by adding a
+ setting such as
- --with-match-limit=500000
+ --with-match-limit=500000
- to the configure command.
+ to the configure command.
HANDLING VERY LARGE PATTERNS
- Within a compiled pattern, offset values are used to point
- from one part to another (for example, from an opening
- parenthesis to an alternation metacharacter). By default
- two-byte values are used for these offsets, leading to a
- maximum size for a compiled pattern of around 64K. This is
- sufficient to handle all but the most gigantic patterns.
- Nevertheless, some people do want to process enormous pat-
- terns, so it is possible to compile PCRE to use three-byte
- or four-byte offsets by adding a setting such as
+ Within a compiled pattern, offset values are used to point from one
+ part to another (for example, from an opening parenthesis to an alter-
+ nation metacharacter). By default two-byte values are used for these
+ offsets, leading to a maximum size for a compiled pattern of around
+ 64K. This is sufficient to handle all but the most gigantic patterns.
+ Nevertheless, some people do want to process enormous patterns, so it
+ is possible to compile PCRE to use three-byte or four-byte offsets by
+ adding a setting such as
- --with-link-size=3
+ --with-link-size=3
- to the configure command. The value given must be 2, 3, or
- 4. Using longer offsets slows down the operation of PCRE
- because it has to load additional bytes when handling them.
+ to the configure command. The value given must be 2, 3, or 4. Using
+ longer offsets slows down the operation of PCRE because it has to load
+ additional bytes when handling them.
- If you build PCRE with an increased link size, test 2 (and
- test 5 if you are using UTF-8) will fail. Part of the output
- of these tests is a representation of the compiled pattern,
- and this changes with the link size.
+ If you build PCRE with an increased link size, test 2 (and test 5 if
+ you are using UTF-8) will fail. Part of the output of these tests is a
+ representation of the compiled pattern, and this changes with the link
+ size.
-Last updated: 21 January 2003
+
+AVOIDING EXCESSIVE STACK USAGE
+
+ PCRE implements backtracking while matching by making recursive calls
+ to an internal function called match(). In environments where the size
+ of the stack is limited, this can severely limit PCRE's operation. (The
+ Unix environment does not usually suffer from this problem.) An alter-
+ native approach that uses memory from the heap to remember data,
+ instead of using recursive function calls, has been implemented to work
+ round this problem. If you want to build a version of PCRE that works
+ this way, add
+
+ --disable-stack-for-recursion
+
+ to the configure command. With this configuration, PCRE will use the
+ pcre_stack_malloc and pcre_stack_free variables to call memory
+ management functions. Separate functions are provided because the usage
+ is very predictable: the block sizes requested are always the same, and
+ the blocks are always freed in reverse order. A calling program might
+ be able to implement optimized functions that perform better than the
+ standard malloc() and free() functions. PCRE runs noticeably more
+ slowly when built in this way.
+
+
+USING EBCDIC CODE
+
+ PCRE assumes by default that it will run in an environment where the
+ character code is ASCII (or UTF-8, which is a superset of ASCII). PCRE
+ can, however, be compiled to run in an EBCDIC environment by adding
+
+ --enable-ebcdic
+
+ to the configure command.
+
+Last updated: 09 December 2003
Copyright (c) 1997-2003 University of Cambridge.
-----------------------------------------------------------------------------
-NAME
- PCRE - Perl-compatible regular expressions
+PCRE(3) PCRE(3)
+
+
+NAME
+ PCRE - Perl-compatible regular expressions
SYNOPSIS OF PCRE API
- #include <pcre.h>
+ #include <pcre.h>
+
+ pcre *pcre_compile(const char *pattern, int options,
+ const char **errptr, int *erroffset,
+ const unsigned char *tableptr);
- 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);
- 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_exec(const pcre *code, const pcre_extra *extra,
- const char *subject, int length, int startoffset,
- int options, int *ovector, int ovecsize);
+ int pcre_copy_named_substring(const pcre *code,
+ const char *subject, int *ovector,
+ int stringcount, const char *stringname,
+ char *buffer, int buffersize);
- int pcre_copy_named_substring(const pcre *code,
- const char *subject, int *ovector,
- int stringcount, const char *stringname,
- char *buffer, int buffersize);
+ int pcre_copy_substring(const char *subject, int *ovector,
+ int stringcount, int stringnumber, char *buffer,
+ int buffersize);
- int pcre_copy_substring(const char *subject, int *ovector,
- int stringcount, int stringnumber, char *buffer,
- int buffersize);
+ int pcre_get_named_substring(const pcre *code,
+ const char *subject, int *ovector,
+ int stringcount, const char *stringname,
+ const char **stringptr);
- int pcre_get_named_substring(const pcre *code,
- const char *subject, int *ovector,
- int stringcount, const char *stringname,
- const char **stringptr);
+ int pcre_get_stringnumber(const pcre *code,
+ const char *name);
- int pcre_get_stringnumber(const pcre *code,
- const char *name);
+ int pcre_get_substring(const char *subject, int *ovector,
+ int stringcount, int stringnumber,
+ const char **stringptr);
- 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);
- int pcre_get_substring_list(const char *subject,
- int *ovector, int stringcount, const char ***listptr);
+ void pcre_free_substring(const char *stringptr);
- void pcre_free_substring(const char *stringptr);
+ void pcre_free_substring_list(const char **stringptr);
- void pcre_free_substring_list(const char **stringptr);
+ const unsigned char *pcre_maketables(void);
- const unsigned char *pcre_maketables(void);
+ int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
+ int what, void *where);
- int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
- int what, void *where);
+ int pcre_info(const pcre *code, int *optptr, int *firstcharptr);
+ int pcre_config(int what, void *where);
- int pcre_info(const pcre *code, int *optptr, *firstcharptr);
+ char *pcre_version(void);
- int pcre_config(int what, void *where);
+ void *(*pcre_malloc)(size_t);
- char *pcre_version(void);
+ void (*pcre_free)(void *);
- void *(*pcre_malloc)(size_t);
+ void *(*pcre_stack_malloc)(size_t);
- void (*pcre_free)(void *);
+ void (*pcre_stack_free)(void *);
- int (*pcre_callout)(pcre_callout_block *);
+ int (*pcre_callout)(pcre_callout_block *);
PCRE API
- 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. A
- sample program that demonstrates the simplest way of using
- them is given in the file pcredemo.c. The pcresample docu-
- mentation describes how to run it.
-
- There are convenience functions for extracting captured sub-
- strings from a matched subject string. They are:
-
- pcre_copy_substring()
- pcre_copy_named_substring()
- pcre_get_substring()
- pcre_get_named_substring()
- pcre_get_substring_list()
-
- pcre_free_substring() and pcre_free_substring_list() are
- also provided, to free the memory used for extracted
- strings.
-
- 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.
-
- The global variable pcre_callout initially contains NULL. It
- can be set by the caller to a "callout" function, which PCRE
- will then call at specified points during a matching opera-
- tion. Details are given in the pcrecallout documentation.
+ 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 applica-
+ tion 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. A sample program that
+ demonstrates the simplest way of using them is given in the file pcre-
+ demo.c. The pcresample documentation describes how to run it.
+
+ There are convenience functions for extracting captured substrings from
+ a matched subject string. They are:
+
+ pcre_copy_substring()
+ pcre_copy_named_substring()
+ pcre_get_substring()
+ pcre_get_named_substring()
+ pcre_get_substring_list()
+
+ pcre_free_substring() and pcre_free_substring_list() are also provided,
+ to free the memory used for extracted strings.
+
+ 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 com-
+ patibility. 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 respec-
+ tively. 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.
+
+ The global variables pcre_stack_malloc and pcre_stack_free are also
+ indirections to memory management functions. These special functions
+ are used only when PCRE is compiled to use the heap for remembering
+ data, instead of recursive function calls. This is a non-standard way
+ of building PCRE, for use in environments that have limited stacks.
+ Because of the greater use of memory management, it runs more slowly.
+ Separate functions are provided so that special-purpose external code
+ can be used for this case. When used, these functions are always called
+ in a stack-like manner (last obtained, first freed), and always for
+ memory blocks of the same size.
+
+ The global variable pcre_callout initially contains NULL. It can be set
+ by the caller to a "callout" function, which PCRE will then call at
+ specified points during a matching operation. Details are given in the
+ pcrecallout documentation.
MULTITHREADING
- 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, and the callout
- function pointed to by pcre_callout, are shared by all
- threads.
+ The PCRE functions can be used in multi-threading applications, with
+ the proviso that the memory management functions pointed to by
+ pcre_malloc, pcre_free, pcre_stack_malloc, and pcre_stack_free, and the
+ callout function pointed to by pcre_callout, 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.
+ The compiled form of a regular expression is not altered during match-
+ ing, so the same compiled pattern can safely be used by several threads
+ at once.
CHECKING BUILD-TIME OPTIONS
- int pcre_config(int what, void *where);
+ int pcre_config(int what, void *where);
+
+ The function pcre_config() makes it possible for a PCRE client to dis-
+ cover which optional features have been compiled into the PCRE library.
+ The pcrebuild documentation has more details about these optional fea-
+ tures.
- The function pcre_config() makes it possible for a PCRE
- client to discover which optional features have been com-
- piled into the PCRE library. The pcrebuild documentation has
- more details about these optional features.
+ The first argument for pcre_config() is an integer, specifying which
+ information is required; the second argument is a pointer to a variable
+ into which the information is placed. The following information is
+ available:
- The first argument for pcre_config() is an integer, specify-
- ing which information is required; the second argument is a
- pointer to a variable into which the information is placed.
- The following information is available:
+ PCRE_CONFIG_UTF8
- PCRE_CONFIG_UTF8
+ The output is an integer that is set to one if UTF-8 support is avail-
+ able; otherwise it is set to zero.
- The output is an integer that is set to one if UTF-8 support
- is available; otherwise it is set to zero.
+ PCRE_CONFIG_NEWLINE
- PCRE_CONFIG_NEWLINE
+ The output is an integer that is set to the value of the code that is
+ used for the newline character. It is either linefeed (10) or carriage
+ return (13), and should normally be the standard character for your
+ operating system.
- The output is an integer that is set to the value of the
- code that is used for the newline character. It is either
- linefeed (10) or carriage return (13), and should normally
- be the standard character for your operating system.
+ PCRE_CONFIG_LINK_SIZE
- PCRE_CONFIG_LINK_SIZE
+ The output is an integer that contains the number of bytes used for
+ internal linkage in compiled regular expressions. The value is 2, 3, or
+ 4. Larger values allow larger regular expressions to be compiled, at
+ the expense of slower matching. The default value of 2 is sufficient
+ for all but the most massive patterns, since it allows the compiled
+ pattern to be up to 64K in size.
- The output is an integer that contains the number of bytes
- used for internal linkage in compiled regular expressions.
- The value is 2, 3, or 4. Larger values allow larger regular
- expressions to be compiled, at the expense of slower match-
- ing. The default value of 2 is sufficient for all but the
- most massive patterns, since it allows the compiled pattern
- to be up to 64K in size.
+ PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
- PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
+ The output is an integer that contains the threshold above which the
+ POSIX interface uses malloc() for output vectors. Further details are
+ given in the pcreposix documentation.
- The output is an integer that contains the threshold above
- which the POSIX interface uses malloc() for output vectors.
- Further details are given in the pcreposix documentation.
+ PCRE_CONFIG_MATCH_LIMIT
- PCRE_CONFIG_MATCH_LIMIT
+ The output is an integer that gives the default limit for the number of
+ internal matching function calls in a pcre_exec() execution. Further
+ details are given with pcre_exec() below.
- The output is an integer that gives the default limit for
- the number of internal matching function calls in a
- pcre_exec() execution. Further details are given with
- pcre_exec() below.
+ PCRE_CONFIG_STACKRECURSE
+
+ The output is an integer that is set to one if internal recursion is
+ implemented by recursive function calls that use the stack to remember
+ their state. This is the usual way that PCRE is compiled. The output is
+ zero if PCRE was compiled to use blocks of data on the heap instead of
+ recursive function calls. In this case, pcre_stack_malloc and
+ pcre_stack_free are called to manage memory blocks on the heap, thus
+ avoiding the use of the stack.
COMPILING A PATTERN
- pcre *pcre_compile(const char *pattern, int options,
- const char **errptr, int *erroffset,
- const unsigned char *tableptr);
-
- 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 the returned
- block; this is a typedef for a structure whose contents are
- not externally defined. It is up to the caller to free the
- memory when it is no longer required.
-
- Although the compiled code of a PCRE regex is relocatable,
- that is, it does not depend on memory location, the complete
- pcre data block is not fully relocatable, because it con-
- tains a copy of the tableptr argument, which is an address
- (see below).
- 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 in the pcrepattern documentation). 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.
-
- This code fragment shows a typical straightforward call to
- pcre_compile():
-
- pcre *re;
- const char *error;
- int erroffset;
- re = pcre_compile(
- "^A.*Z", /* the pattern */
- 0, /* default options */
- &error, /* for error message */
- &erroffset, /* for error offset */
- NULL); /* use default character tables */
-
- The following option bits are defined:
-
- PCRE_ANCHORED
-
- If this bit is set, the pattern is forced to be "anchored",
- that is, it is constrained to match only at the first match-
- ing point in the string which is being searched (the "sub-
- ject string"). This effect can also be achieved by appropri-
- ate 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, and it can be changed within a pattern by a (?i)
- option setting.
-
- 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, and no way to set it within a pattern.
-
- 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, and it can be changed within a pattern by a (?s)
- option setting. 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 pat-
- tern are totally ignored except when escaped or inside a
- character class. Whitespace does not include the VT charac-
- ter (code 11). In addition, 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 it can be changed within a pattern by a (?x)
- option setting.
-
- This option 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, and it can be changed within
- a pattern by a (?m) option setting. 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_NO_AUTO_CAPTURE
-
- If this option is set, it disables the use of numbered cap-
- turing parentheses in the pattern. Any opening parenthesis
- that is not followed by ? behaves as if it were followed by
- ?: but named parentheses can still be used for capturing
- (and they acquire numbers in the usual way). There is no
- equivalent of this option in Perl.
-
- 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.
-
- PCRE_UTF8
-
- This option causes PCRE to regard both the pattern and the
- subject as strings of UTF-8 characters instead of single-
- byte character strings. However, it is available only if
- PCRE has been built to include UTF-8 support. If not, the
- use of this option provokes an error. Details of how this
- option changes the behaviour of PCRE are given in the sec-
- tion on UTF-8 support in the main pcre page.
+ pcre *pcre_compile(const char *pattern, int options,
+ const char **errptr, int *erroffset,
+ const unsigned char *tableptr);
+
+
+ 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 the
+ returned block; this is a typedef for a structure whose contents are
+ not externally defined. It is up to the caller to free the memory when
+ it is no longer required.
+
+ Although the compiled code of a PCRE regex is relocatable, that is, it
+ does not depend on memory location, the complete pcre data block is not
+ fully relocatable, because it contains a copy of the tableptr argument,
+ which is an address (see below).
+
+ The options argument contains independent bits that affect the compila-
+ tion. 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 in the pcrepattern documentation). 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 mes-
+ sage. 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.
+
+ This code fragment shows a typical straightforward call to pcre_com-
+ pile():
+
+ pcre *re;
+ const char *error;
+ int erroffset;
+ re = pcre_compile(
+ "^A.*Z", /* the pattern */
+ 0, /* default options */
+ &error, /* for error message */
+ &erroffset, /* for error offset */
+ NULL); /* use default character tables */
+
+ The following option bits are defined:
+
+ PCRE_ANCHORED
+
+ If this bit is set, the pattern is forced to be "anchored", that is, it
+ is constrained to match only at the first matching point in 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, and it can be
+ changed within a pattern by a (?i) option setting.
+
+ 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, and no way to set it within a pattern.
+
+ PCRE_DOTALL
+
+ If this bit is set, a dot metacharater in the pattern matches all char-
+ acters, including newlines. Without it, newlines are excluded. This
+ option is equivalent to Perl's /s option, and it can be changed within
+ a pattern by a (?s) option setting. 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.
+ Whitespace does not include the VT character (code 11). In addition,
+ 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 it can be changed within a pattern by a (?x)
+ option setting.
+
+ This option 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_DOL-
+ LAR_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 new-
+ line in the subject string, respectively, as well as at the very start
+ and end. This is equivalent to Perl's /m option, and it can be changed
+ within a pattern by a (?m) option setting. 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_NO_AUTO_CAPTURE
+
+ If this option is set, it disables the use of numbered capturing paren-
+ theses in the pattern. Any opening parenthesis that is not followed by
+ ? behaves as if it were followed by ?: but named parentheses can still
+ be used for capturing (and they acquire numbers in the usual way).
+ There is no equivalent of this option in Perl.
+
+ 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.
+
+ PCRE_UTF8
+
+ This option causes PCRE to regard both the pattern and the subject as
+ strings of UTF-8 characters instead of single-byte character strings.
+ However, it is available only if PCRE has been built to include UTF-8
+ support. If not, the use of this option provokes an error. Details of
+ how this option changes the behaviour of PCRE are given in the section
+ on UTF-8 support in the main pcre page.
+
+ PCRE_NO_UTF8_CHECK
+
+ When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
+ automatically checked. If an invalid UTF-8 sequence of bytes is found,
+ pcre_compile() returns an error. If you already know that your pattern
+ is valid, and you want to skip this check for performance reasons, you
+ can set the PCRE_NO_UTF8_CHECK option. When it is set, the effect of
+ passing an invalid UTF-8 string as a pattern is undefined. It may cause
+ your program to crash. Note that there is a similar option for sup-
+ pressing the checking of subject strings passed to pcre_exec().
+
STUDYING A PATTERN
- pcre_extra *pcre_study(const pcre *code, int options,
- const char **errptr);
-
- 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. If
- studing the pattern produces additional information that
- will help speed up matching, pcre_study() returns a pointer
- to a pcre_extra block, in which the study_data field points
- to the results of the study.
-
- The returned value from a pcre_study() can be passed
- directly to pcre_exec(). However, the pcre_extra block also
- contains other fields that can be set by the caller before
- the block is passed; these are described below. If studying
- the pattern does not produce any additional information,
- pcre_study() returns NULL. In that circumstance, if the cal-
- ling program wants to pass some of the other fields to
- pcre_exec(), it must set up its own pcre_extra block.
-
- 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 for an
- error message. If studying succeeds (even if no data is
- returned), the variable it points to is set to NULL. Other-
- wise it points to a textual error message. You should there-
- fore test the error pointer for NULL after calling
- pcre_study(), to be sure that it has run successfully.
-
- This is a typical call to pcre_study():
-
- pcre_extra *pe;
- pe = pcre_study(
- re, /* result of pcre_compile() */
- 0, /* no options exist */
- &error); /* set to NULL or points to a 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.
+ pcre_extra *pcre_study(const pcre *code, int options,
+ const char **errptr);
+
+ 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 match-
+ ing. The function pcre_study() takes a pointer to a compiled pattern as
+ its first argument. If studing the pattern produces additional informa-
+ tion that will help speed up matching, pcre_study() returns a pointer
+ to a pcre_extra block, in which the study_data field points to the
+ results of the study.
+
+ The returned value from a pcre_study() can be passed directly to
+ pcre_exec(). However, the pcre_extra block also contains other fields
+ that can be set by the caller before the block is passed; these are
+ described below. If studying the pattern does not produce any addi-
+ tional information, pcre_study() returns NULL. In that circumstance, if
+ the calling program wants to pass some of the other fields to
+ pcre_exec(), it must set up its own pcre_extra block.
+
+ 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 for 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 mes-
+ sage. You should therefore test the error pointer for NULL after call-
+ ing pcre_study(), to be sure that it has run successfully.
+
+ This is a typical call to pcre_study():
+
+ pcre_extra *pe;
+ pe = pcre_study(
+ re, /* result of pcre_compile() */
+ 0, /* no options exist */
+ &error); /* set to NULL or points to a 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 possi-
+ ble 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. When running in UTF-8 mode, this applies only
- to characters with codes less than 256. The library contains
- a default set of tables that is created in the default C
- locale when PCRE is compiled. This is used when the final
- argument of pcre_compile() is NULL, and is sufficient for
- many applications.
-
- 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.
+ PCRE handles caseless matching, and determines whether characters are
+ letters, digits, or whatever, by reference to a set of tables. When
+ running in UTF-8 mode, this applies only to characters with codes less
+ than 256. The library contains a default set of tables that is created
+ in the default C locale when PCRE is compiled. This is used when the
+ final argument of pcre_compile() is NULL, and is sufficient for many
+ applications.
+
+ An alternative set of tables can, however, be supplied. Such tables are
+ built by calling the pcre_maketables() function, which has no argu-
+ ments, 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 char-
+ acters with codes greater than 128 are treated as letters), the follow-
+ ing 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 pat-
+ tern, 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 responsibility to
+ ensure that the memory containing the tables remains available for as
+ long as it is needed.
INFORMATION ABOUT A PATTERN
- int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
- int what, void *where);
-
- 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, and 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 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
-
- Here is a typical call of pcre_fullinfo(), to obtain the
- length of the compiled pattern:
-
- int rc;
- unsigned long int length;
- rc = pcre_fullinfo(
- re, /* result of pcre_compile() */
- pe, /* result of pcre_study(), or NULL */
- PCRE_INFO_SIZE, /* what is required */
- &length); /* where to put the data */
-
- The possible values for the third argument are defined in
- pcre.h, and are as follows:
-
- 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_CAPTURECOUNT
-
- Return the number of capturing subpatterns in the pattern.
- The fourth argument should point to an int variable.
-
- PCRE_INFO_FIRSTBYTE
-
- Return information about the first byte of any matched
- string, for a non-anchored pattern. (This option used to be
- called PCRE_INFO_FIRSTCHAR; the old name is still recognized
- for backwards compatibility.)
-
- If there is a fixed first byte, e.g. from a pattern such as
- (cat|cow|coyote), 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),
-
- -1 is returned, indicating that the pattern matches only at
- the start of a subject string or after any newline 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 bytes
- for the first byte 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
-
- Return the value of the rightmost literal byte that must
- exist in any matched string, other than at its start, if
- such a byte has been recorded. The fourth argument should
- point to an int variable. If there is no such byte, -1 is
- returned. For anchored patterns, a last literal byte is
- recorded only if it follows something of variable length.
- For example, for the pattern /^a\d+z\d+/ the returned value
- is "z", but for /^a\dz\d/ the returned value is -1.
-
- PCRE_INFO_NAMECOUNT
- PCRE_INFO_NAMEENTRYSIZE
- PCRE_INFO_NAMETABLE
-
- PCRE supports the use of named as well as numbered capturing
- parentheses. The names are just an additional way of identi-
- fying the parentheses, which still acquire a number. A
- caller that wants to extract data from a named subpattern
- must convert the name to a number in order to access the
- correct pointers in the output vector (described with
- pcre_exec() below). In order to do this, it must first use
- these three values to obtain the name-to-number mapping
- table for the pattern.
-
- The map consists of a number of fixed-size entries.
- PCRE_INFO_NAMECOUNT gives the number of entries, and
- PCRE_INFO_NAMEENTRYSIZE gives the size of each entry; both
- of these return an int value. The entry size depends on the
- length of the longest name. PCRE_INFO_NAMETABLE returns a
- pointer to the first entry of the table (a pointer to char).
- The first two bytes of each entry are the number of the cap-
- turing parenthesis, most significant byte first. The rest of
- the entry is the corresponding name, zero terminated. The
- names are in alphabetical order. For example, consider the
- following pattern (assume PCRE_EXTENDED is set, so white
- space - including newlines - is ignored):
-
- (?P<date> (?P<year>(\d\d)?\d\d) -
- (?P<month>\d\d) - (?P<day>\d\d) )
-
- There are four named subpatterns, so the table has four
- entries, and each entry in the table is eight bytes long.
- The table is as follows, with non-printing bytes shows in
- hex, and undefined bytes shown as ??:
-
- 00 01 d a t e 00 ??
- 00 05 d a y 00 ?? ??
- 00 04 m o n t h 00
- 00 02 y e a r 00 ??
-
- When writing code to extract data from named subpatterns,
- remember that the length of each entry may be different for
- each compiled pattern.
-
- PCRE_INFO_OPTIONS
-
- Return a copy of the options with which the pattern was com-
- piled. The fourth argument should point to an 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.
-
- A pattern is automatically anchored by PCRE if all of its
- top-level alternatives begin with one of the following:
-
- ^ unless PCRE_MULTILINE is set
- \A always
- \G always
- .* if PCRE_DOTALL is set and there are no back
- references to the subpattern in which .* appears
-
- For such patterns, the PCRE_ANCHORED bit is set in the
- options returned by pcre_fullinfo().
-
- 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_STUDYSIZE
-
- Returns the size of the data block pointed to by the
- study_data field in a pcre_extra block. That is, it is the
- value that was passed to pcre_malloc() when PCRE was getting
- memory into which to place the data created by pcre_study().
- The fourth argument should point to a size_t variable.
+ int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
+ int what, void *where);
+
+ The pcre_fullinfo() function returns information about a compiled pat-
+ tern. It replaces the obsolete pcre_info() function, which is neverthe-
+ less retained for backwards compability (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, and 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 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
+
+ Here is a typical call of pcre_fullinfo(), to obtain the length of the
+ compiled pattern:
+
+ int rc;
+ unsigned long int length;
+ rc = pcre_fullinfo(
+ re, /* result of pcre_compile() */
+ pe, /* result of pcre_study(), or NULL */
+ PCRE_INFO_SIZE, /* what is required */
+ &length); /* where to put the data */
+
+ The possible values for the third argument are defined in pcre.h, and
+ are as follows:
+
+ PCRE_INFO_BACKREFMAX
+
+ Return the number of the highest back reference in the pattern. The
+ fourth argument should point to an int variable. Zero is returned if
+ there are no back references.
+
+ PCRE_INFO_CAPTURECOUNT
+
+ Return the number of capturing subpatterns in the pattern. The fourth
+ argument should point to an int variable.
+
+ PCRE_INFO_FIRSTBYTE
+
+ Return information about the first byte of any matched string, for a
+ non-anchored pattern. (This option used to be called
+ PCRE_INFO_FIRSTCHAR; the old name is still recognized for backwards
+ compatibility.)
+
+ If there is a fixed first byte, e.g. from a pattern such as
+ (cat|cow|coyote), 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),
+
+ -1 is returned, indicating that the pattern matches only at the start
+ of a subject string or after any newline 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 bytes for the first byte in any
+ matching string, a pointer to the table is returned. Otherwise NULL is
+ returned. The fourth argument should point to an unsigned char * vari-
+ able.
+
+ PCRE_INFO_LASTLITERAL
+
+ Return the value of the rightmost literal byte that must exist in any
+ matched string, other than at its start, if such a byte has been
+ recorded. The fourth argument should point to an int variable. If there
+ is no such byte, -1 is returned. For anchored patterns, a last literal
+ byte is recorded only if it follows something of variable length. For
+ example, for the pattern /^a\d+z\d+/ the returned value is "z", but for
+ /^a\dz\d/ the returned value is -1.
+
+ PCRE_INFO_NAMECOUNT
+ PCRE_INFO_NAMEENTRYSIZE
+ PCRE_INFO_NAMETABLE
+
+ PCRE supports the use of named as well as numbered capturing parenthe-
+ ses. The names are just an additional way of identifying the parenthe-
+ ses, which still acquire a number. A caller that wants to extract data
+ from a named subpattern must convert the name to a number in order to
+ access the correct pointers in the output vector (described with
+ pcre_exec() below). In order to do this, it must first use these three
+ values to obtain the name-to-number mapping table for the pattern.
+
+ The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT
+ gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size
+ of each entry; both of these return an int value. The entry size
+ depends on the length of the longest name. PCRE_INFO_NAMETABLE returns
+ a pointer to the first entry of the table (a pointer to char). The
+ first two bytes of each entry are the number of the capturing parenthe-
+ sis, most significant byte first. The rest of the entry is the corre-
+ sponding name, zero terminated. The names are in alphabetical order.
+ For example, consider the following pattern (assume PCRE_EXTENDED is
+ set, so white space - including newlines - is ignored):
+
+ (?P<date> (?P<year>(\d\d)?\d\d) -
+ (?P<month>\d\d) - (?P<day>\d\d) )
+
+ There are four named subpatterns, so the table has four entries, and
+ each entry in the table is eight bytes long. The table is as follows,
+ with non-printing bytes shows in hex, and undefined bytes shown as ??:
+
+ 00 01 d a t e 00 ??
+ 00 05 d a y 00 ?? ??
+ 00 04 m o n t h 00
+ 00 02 y e a r 00 ??
+
+ When writing code to extract data from named subpatterns, remember that
+ the length of each entry may be different for each compiled pattern.
+
+ PCRE_INFO_OPTIONS
+
+ Return a copy of the options with which the pattern was compiled. The
+ fourth argument should point to an 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.
+
+ A pattern is automatically anchored by PCRE if all of its top-level
+ alternatives begin with one of the following:
+
+ ^ unless PCRE_MULTILINE is set
+ \A always
+ \G always
+ .* if PCRE_DOTALL is set and there are no back
+ references to the subpattern in which .* appears
+
+ For such patterns, the PCRE_ANCHORED bit is set in the options returned
+ by pcre_fullinfo().
+
+ 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_STUDYSIZE
+
+ Returns the size of the data block pointed to by the study_data field
+ in a pcre_extra block. That is, it is the value that was passed to
+ pcre_malloc() when PCRE was getting memory into which to place the data
+ created by pcre_study(). The fourth argument should point to a size_t
+ variable.
OBSOLETE INFO FUNCTION
- int pcre_info(const pcre *code, int *optptr, *firstcharptr);
+ int pcre_info(const pcre *code, int *optptr, int *firstcharptr);
- 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:
+ The pcre_info() function is now obsolete because its interface 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 fol-
+ lowing negative numbers:
- PCRE_ERROR_NULL the argument code was NULL
- PCRE_ERROR_BADMAGIC the "magic number" was not found
+ 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 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_FIRSTBYTE 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_FIRSTBYTE above).
MATCHING A PATTERN
- int pcre_exec(const pcre *code, const pcre_extra *extra,
- const char *subject, int length, int startoffset,
- int options, int *ovector, int ovecsize);
-
- 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.
-
- Here is an example of a simple call to pcre_exec():
-
- int rc;
- int ovector[30];
- rc = pcre_exec(
- re, /* result of pcre_compile() */
- NULL, /* we didn't study the pattern */
- "some string", /* the subject string */
- 11, /* the length of the subject string */
- 0, /* start at offset 0 in the subject */
- 0, /* default options */
- ovector, /* vector for substring information */
- 30); /* number of elements in the vector */
-
- If the extra argument is not NULL, it must point to a
- pcre_extra data block. The pcre_study() function returns
- such a block (when it doesn't return NULL), but you can also
- create one for yourself, and pass additional information in
- it. The fields in the block are as follows:
-
- unsigned long int flags;
- void *study_data;
- unsigned long int match_limit;
- void *callout_data;
-
- The flags field is a bitmap that specifies which of the
- other fields are set. The flag bits are:
-
- PCRE_EXTRA_STUDY_DATA
- PCRE_EXTRA_MATCH_LIMIT
- PCRE_EXTRA_CALLOUT_DATA
-
- Other flag bits should be set to zero. The study_data field
- is set in the pcre_extra block that is returned by
- pcre_study(), together with the appropriate flag bit. You
- should not set this yourself, but you can add to the block
- by setting the other fields.
-
- The match_limit field provides a means of preventing PCRE
- from using up a vast amount of resources when running pat-
- terns that are not going to match, but which have a very
- large number of possibilities in their search trees. The
- classic example is the use of nested unlimited repeats.
- Internally, PCRE uses a function called match() which it
- calls repeatedly (sometimes recursively). The limit is
- imposed on the number of times this function is called dur-
- ing a match, which has the effect of limiting the amount of
- recursion and backtracking that can take place. For patterns
- that are not anchored, the count starts from zero for each
- position in the subject string.
-
- The default limit for the library can be set when PCRE is
- built; the default default is 10 million, which handles all
- but the most extreme cases. You can reduce the default by
- suppling pcre_exec() with a pcre_extra block in which
- match_limit is set to a smaller value, and
- PCRE_EXTRA_MATCH_LIMIT is set in the flags field. If the
- limit is exceeded, pcre_exec() returns
- PCRE_ERROR_MATCHLIMIT.
-
- The pcre_callout field is used in conjunction with the "cal-
- lout" feature, which is described in the pcrecallout docu-
- mentation.
-
- The PCRE_ANCHORED option can be passed in the options argu-
- ment, whose unused bits must be zero. This limits
- pcre_exec() to matching at the first matching position. How-
- ever, if a pattern was compiled with PCRE_ANCHORED, or
- turned out to be anchored by virtue of its contents, it can-
- not 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 to pcre_exec() as a pointer in
- subject, a length in length, and a starting offset in star-
- toffset. Unlike the pattern string, the subject may contain
- binary zero bytes. 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.
-
- If the pattern was compiled with the PCRE_UTF8 option, the
- subject must be a sequence of bytes that is a valid UTF-8
- string. If an invalid UTF-8 string is passed, PCRE's
- behaviour is not defined.
-
- 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.
-
- PCRE_ERROR_NOSUBSTRING (-7)
-
- This error is used by the pcre_copy_substring(),
- pcre_get_substring(), and pcre_get_substring_list() func-
- tions (see below). It is never returned by pcre_exec().
-
- PCRE_ERROR_MATCHLIMIT (-8)
-
- The recursion and backtracking limit, as specified by the
- match_limit field in a pcre_extra structure (or defaulted)
- was reached. See the description above.
+ int pcre_exec(const pcre *code, const pcre_extra *extra,
+ const char *subject, int length, int startoffset,
+ int options, int *ovector, int ovecsize);
+
+ 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 pat-
+ tern has been studied, the result of the study should be passed in the
+ extra argument.
+
+ Here is an example of a simple call to pcre_exec():
+
+ int rc;
+ int ovector[30];
+ rc = pcre_exec(
+ re, /* result of pcre_compile() */
+ NULL, /* we didn't study the pattern */
+ "some string", /* the subject string */
+ 11, /* the length of the subject string */
+ 0, /* start at offset 0 in the subject */
+ 0, /* default options */
+ ovector, /* vector for substring information */
+ 30); /* number of elements in the vector */
+
+ If the extra argument is not NULL, it must point to a pcre_extra data
+ block. The pcre_study() function returns such a block (when it doesn't
+ return NULL), but you can also create one for yourself, and pass addi-
+ tional information in it. The fields in the block are as follows:
+
+ unsigned long int flags;
+ void *study_data;
+ unsigned long int match_limit;
+ void *callout_data;
+
+ The flags field is a bitmap that specifies which of the other fields
+ are set. The flag bits are:
+
+ PCRE_EXTRA_STUDY_DATA
+ PCRE_EXTRA_MATCH_LIMIT
+ PCRE_EXTRA_CALLOUT_DATA
+
+ Other flag bits should be set to zero. The study_data field is set in
+ the pcre_extra block that is returned by pcre_study(), together with
+ the appropriate flag bit. You should not set this yourself, but you can
+ add to the block by setting the other fields.
+
+ The match_limit field provides a means of preventing PCRE from using up
+ a vast amount of resources when running patterns that are not going to
+ match, but which have a very large number of possibilities in their
+ search trees. The classic example is the use of nested unlimited
+ repeats. Internally, PCRE uses a function called match() which it calls
+ repeatedly (sometimes recursively). The limit is imposed on the number
+ of times this function is called during a match, which has the effect
+ of limiting the amount of recursion and backtracking that can take
+ place. For patterns that are not anchored, the count starts from zero
+ for each position in the subject string.
+
+ The default limit for the library can be set when PCRE is built; the
+ default default is 10 million, which handles all but the most extreme
+ cases. You can reduce the default by suppling pcre_exec() with a
+ pcre_extra block in which match_limit is set to a smaller value, and
+ PCRE_EXTRA_MATCH_LIMIT is set in the flags field. If the limit is
+ exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
+
+ The pcre_callout field is used in conjunction with the "callout" fea-
+ ture, which is described in the pcrecallout documentation.
+
+ The PCRE_ANCHORED option can be passed in the options argument, whose
+ unused bits must be zero. This limits pcre_exec() to matching at the
+ first matching position. 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.
+
+ When PCRE_UTF8 was set at compile time, the validity of the subject as
+ a UTF-8 string is automatically checked, and the value of startoffset
+ is also checked to ensure that it points to the start of a UTF-8 char-
+ acter. If an invalid UTF-8 sequence of bytes is found, pcre_exec()
+ returns the error PCRE_ERROR_BADUTF8. If startoffset contains an
+ invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.
+
+ If you already know that your subject is valid, and you want to skip
+ these checks for performance reasons, you can set the
+ PCRE_NO_UTF8_CHECK option when calling pcre_exec(). You might want to
+ do this for the second and subsequent calls to pcre_exec() if you are
+ making repeated calls to find all the matches in a single subject
+ string. However, you should be sure that the value of startoffset
+ points to the start of a UTF-8 character. When PCRE_NO_UTF8_CHECK is
+ set, the effect of passing an invalid UTF-8 string as a subject, or a
+ value of startoffset that does not point to the start of a UTF-8 char-
+ acter, is undefined. Your program may crash.
+
+ 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 metachar-
+ acter 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 occur-
+ rences of "a" or "b".
+
+ Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a spe-
+ cial 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 to pcre_exec() as a pointer in subject, a
+ length in length, and a starting byte offset in startoffset. Unlike the
+ pattern string, the subject may contain binary zero bytes. 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.
+
+ If the pattern was compiled with the PCRE_UTF8 option, the subject must
+ be a sequence of bytes that is a valid UTF-8 string, and the starting
+ offset must point to the beginning of a UTF-8 character. If an invalid
+ UTF-8 string or offset is passed, an error (either PCRE_ERROR_BADUTF8
+ or PCRE_ERROR_BADUTF8_OFFSET) is returned, unless the option
+ PCRE_NO_UTF8_CHECK is set, in which case PCRE's behaviour is not
+ defined.
+
+ A non-zero starting offset is useful when searching for another match
+ in the same subject by calling pcre_exec() again after a previous suc-
+ cess. 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 suc-
+ ceed 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 sub-
+ string. 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 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 sub-
+ string, 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 subpat-
+ tern, 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 substrings, it is
+ used as far as possible (up to two-thirds of its length), and the func-
+ tion 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 refer-
+ ences and the ovector isn't big enough to remember the related sub-
+ strings, 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 capturing sub-
+ patterns 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 following 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 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 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.
+
+ PCRE_ERROR_NOSUBSTRING (-7)
+
+ This error is used by the pcre_copy_substring(), pcre_get_substring(),
+ and pcre_get_substring_list() functions (see below). It is never
+ returned by pcre_exec().
- PCRE_ERROR_CALLOUT (-9)
+ PCRE_ERROR_MATCHLIMIT (-8)
- This error is never generated by pcre_exec() itself. It is
- provided for use by callout functions that want to yield a
- distinctive error code. See the pcrecallout documentation
- for details.
+ The recursion and backtracking limit, as specified by the match_limit
+ field in a pcre_extra structure (or defaulted) was reached. See the
+ description above.
+
+ PCRE_ERROR_CALLOUT (-9)
+
+ This error is never generated by pcre_exec() itself. It is provided for
+ use by callout functions that want to yield a distinctive error code.
+ See the pcrecallout documentation for details.
+
+ PCRE_ERROR_BADUTF8 (-10)
+
+ A string that contains an invalid UTF-8 byte sequence was passed as a
+ subject.
+
+ PCRE_ERROR_BADUTF8_OFFSET (-11)
+
+ The UTF-8 byte sequence that was passed as a subject was valid, but the
+ value of startoffset did not point to the beginning of a UTF-8 charac-
+ ter.
EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
- 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);
-
- 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. These functions identify substrings by number. The
- next section describes functions for extracting named sub-
- strings. A substring that contains a binary zero is
- correctly extracted and has a further zero added on the end,
- but the result is not, of course, a C string.
-
- The first three arguments are the same for all three of
- these functions: 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 cap-
- tured 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, 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 memory 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.
-
- The two convenience functions pcre_free_substring() and
- pcre_free_substring_list() can be used to free the memory
- returned by a previous call of pcre_get_substring() or
- pcre_get_substring_list(), respectively. They do nothing
- more than call the function pointed to by pcre_free, which
- of course could be called directly from a C program. How-
- ever, PCRE is used in some situations where it is linked via
- a special interface to another programming language which
- cannot use pcre_free directly; it is for these cases that
- the functions are provided.
+ 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);
+
+ 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_sub-
+ string_list() are provided for extracting captured substrings as new,
+ separate, zero-terminated strings. These functions identify substrings
+ by number. The next section describes functions for extracting named
+ substrings. A substring that contains a binary zero is correctly
+ extracted and has a further zero added on the end, but the result is
+ not, of course, a C string.
+
+ The first three arguments are the same for all three of these 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 ovector, 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 stringnumber. A value of
+ zero extracts the substring that matched the entire pattern, while
+ higher values extract the captured substrings. For pcre_copy_sub-
+ string(), the string is placed in buffer, whose length is given by
+ buffersize, while for pcre_get_substring() a new block of memory 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 available sub-
+ strings 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 sub-
+ string by inspecting the appropriate offset in ovector, which is nega-
+ tive for unset substrings.
+
+ The two convenience functions pcre_free_substring() and
+ pcre_free_substring_list() can be used to free the memory returned by a
+ previous call of pcre_get_substring() or pcre_get_substring_list(),
+ respectively. They do nothing more than call the function pointed to by
+ pcre_free, which of course could be called directly from a C program.
+ However, PCRE is used in some situations where it is linked via a spe-
+ cial interface to another programming language which cannot use
+ pcre_free directly; it is for these cases that the functions are pro-
+ vided.
EXTRACTING CAPTURED SUBSTRINGS BY NAME
- int pcre_copy_named_substring(const pcre *code,
- const char *subject, int *ovector,
- int stringcount, const char *stringname,
- char *buffer, int buffersize);
+ int pcre_copy_named_substring(const pcre *code,
+ const char *subject, int *ovector,
+ int stringcount, const char *stringname,
+ char *buffer, int buffersize);
- int pcre_get_stringnumber(const pcre *code,
- const char *name);
+ int pcre_get_stringnumber(const pcre *code,
+ const char *name);
- int pcre_get_named_substring(const pcre *code,
- const char *subject, int *ovector,
- int stringcount, const char *stringname,
- const char **stringptr);
+ int pcre_get_named_substring(const pcre *code,
+ const char *subject, int *ovector,
+ int stringcount, const char *stringname,
+ const char **stringptr);
- To extract a substring by name, you first have to find asso-
- ciated number. This can be done by calling
- pcre_get_stringnumber(). The first argument is the compiled
- pattern, and the second is the name. For example, for this
- pattern
+ To extract a substring by name, you first have to find associated num-
+ ber. This can be done by calling pcre_get_stringnumber(). The first
+ argument is the compiled pattern, and the second is the name. For exam-
+ ple, for this pattern
- ab(?<xxx>\d+)...
+ ab(?<xxx>\d+)...
- the number of the subpattern called "xxx" is 1. Given the
- number, you can then extract the substring directly, or use
- one of the functions described in the previous section. For
- convenience, there are also two functions that do the whole
- job.
+ the number of the subpattern called "xxx" is 1. Given the number, you
+ can then extract the substring directly, or use one of the functions
+ described in the previous section. For convenience, there are also two
+ functions that do the whole job.
- Most of the arguments of pcre_copy_named_substring() and
- pcre_get_named_substring() are the same as those for the
- functions that extract by number, and so are not re-
- described here. There are just two differences.
+ Most of the arguments of pcre_copy_named_substring() and
+ pcre_get_named_substring() are the same as those for the functions that
+ extract by number, and so are not re-described here. There are just two
+ differences.
- First, instead of a substring number, a substring name is
- given. Second, there is an extra argument, given at the
- start, which is a pointer to the compiled pattern. This is
- needed in order to gain access to the name-to-number trans-
- lation table.
+ First, instead of a substring number, a substring name is given. Sec-
+ ond, there is an extra argument, given at the start, which is a pointer
+ to the compiled pattern. This is needed in order to gain access to the
+ name-to-number translation table.
- These functions call pcre_get_stringnumber(), and if it
- succeeds, they then call pcre_copy_substring() or
- pcre_get_substring(), as appropriate.
+ These functions call pcre_get_stringnumber(), and if it succeeds, they
+ then call pcre_copy_substring() or pcre_get_substring(), as appropri-
+ ate.
-Last updated: 03 February 2003
+Last updated: 09 December 2003
Copyright (c) 1997-2003 University of Cambridge.
-----------------------------------------------------------------------------
-NAME
- PCRE - Perl-compatible regular expressions
+PCRE(3) PCRE(3)
+
+NAME
+ PCRE - Perl-compatible regular expressions
+
PCRE CALLOUTS
- int (*pcre_callout)(pcre_callout_block *);
-
- PCRE provides a feature called "callout", which is a means
- of temporarily passing control to the caller of PCRE in the
- middle of pattern matching. The caller of PCRE provides an
- external function by putting its entry point in the global
- variable pcre_callout. By default, this variable contains
- NULL, which disables all calling out.
-
- Within a regular expression, (?C) indicates the points at
- which the external function is to be called. Different cal-
- lout points can be identified by putting a number less than
- 256 after the letter C. The default value is zero. For
- example, this pattern has two callout points:
-
- (?C1)\e9abc(?C2)def
-
- During matching, when PCRE reaches a callout point (and
- pcre_callout is set), the external function is called. Its
- only argument is a pointer to a pcre_callout block. This
- contains the following variables:
-
- int version;
- int callout_number;
- int *offset_vector;
- const char *subject;
- int subject_length;
- int start_match;
- int current_position;
- int capture_top;
- int capture_last;
- void *callout_data;
-
- The version field is an integer containing the version
- number of the block format. The current version is zero. The
- version number may change in future if additional fields are
- added, but the intention is never to remove any of the
- existing fields.
-
- The callout_number field contains the number of the callout,
- as compiled into the pattern (that is, the number after ?C).
-
- The offset_vector field is a pointer to the vector of
- offsets that was passed by the caller to pcre_exec(). The
- contents can be inspected in order to extract substrings
- that have been matched so far, in the same way as for
- extracting substrings after a match has completed.
- The subject and subject_length fields contain copies the
- values that were passed to pcre_exec().
-
- The start_match field contains the offset within the subject
- at which the current match attempt started. If the pattern
- is not anchored, the callout function may be called several
- times for different starting points.
-
- The current_position field contains the offset within the
- subject of the current match pointer.
-
- The capture_top field contains the number of the highest
- captured substring so far.
-
- The capture_last field contains the number of the most
- recently captured substring.
-
- The callout_data field contains a value that is passed to
- pcre_exec() by the caller specifically so that it can be
- passed back in callouts. It is passed in the pcre_callout
- field of the pcre_extra data structure. If no such data was
- passed, the value of callout_data in a pcre_callout block is
- NULL. There is a description of the pcre_extra structure in
- the pcreapi documentation.
+ int (*pcre_callout)(pcre_callout_block *);
+
+ PCRE provides a feature called "callout", which is a means of temporar-
+ ily passing control to the caller of PCRE in the middle of pattern
+ matching. The caller of PCRE provides an external function by putting
+ its entry point in the global variable pcre_callout. By default, this
+ variable contains NULL, which disables all calling out.
+
+ Within a regular expression, (?C) indicates the points at which the
+ external function is to be called. Different callout points can be
+ identified by putting a number less than 256 after the letter C. The
+ default value is zero. For example, this pattern has two callout
+ points:
+
+ (?C1)abc(?C2)def
+
+ During matching, when PCRE reaches a callout point (and pcre_callout is
+ set), the external function is called. Its only argument is a pointer
+ to a pcre_callout block. This contains the following variables:
+
+ int version;
+ int callout_number;
+ int *offset_vector;
+ const char *subject;
+ int subject_length;
+ int start_match;
+ int current_position;
+ int capture_top;
+ int capture_last;
+ void *callout_data;
+
+ The version field is an integer containing the version number of the
+ block format. The current version is zero. The version number may
+ change in future if additional fields are added, but the intention is
+ never to remove any of the existing fields.
+
+ The callout_number field contains the number of the callout, as com-
+ piled into the pattern (that is, the number after ?C).
+
+ The offset_vector field is a pointer to the vector of offsets that was
+ passed by the caller to pcre_exec(). The contents can be inspected in
+ order to extract substrings that have been matched so far, in the same
+ way as for extracting substrings after a match has completed.
+
+ The subject and subject_length fields contain copies the values that
+ were passed to pcre_exec().
+
+ The start_match field contains the offset within the subject at which
+ the current match attempt started. If the pattern is not anchored, the
+ callout function may be called several times for different starting
+ points.
+
+ The current_position field contains the offset within the subject of
+ the current match pointer.
+
+ The capture_top field contains one more than the number of the highest
+ numbered captured substring so far. If no substrings have been
+ captured, the value of capture_top is one.
+
+ The capture_last field contains the number of the most recently cap-
+ tured substring.
+
+ The callout_data field contains a value that is passed to pcre_exec()
+ by the caller specifically so that it can be passed back in callouts.
+ It is passed in the pcre_callout field of the pcre_extra data struc-
+ ture. If no such data was passed, the value of callout_data in a
+ pcre_callout block is NULL. There is a description of the pcre_extra
+ structure in the pcreapi documentation.
RETURN VALUES
- The callout function returns an integer. If the value is
- zero, matching proceeds as normal. If the value is greater
- than zero, matching fails at the current point, but back-
- tracking to test other possibilities goes ahead, just as if
- a lookahead assertion had failed. If the value is less than
- zero, the match is abandoned, and pcre_exec() returns the
- value.
+ The callout function returns an integer. If the value is zero, matching
+ proceeds as normal. If the value is greater than zero, matching fails
+ at the current point, but backtracking to test other possibilities goes
+ ahead, just as if a lookahead assertion had failed. If the value is
+ less than zero, the match is abandoned, and pcre_exec() returns the
+ value.
- Negative values should normally be chosen from the set of
- PCRE_ERROR_xxx values. In particular, PCRE_ERROR_NOMATCH
- forces a standard "no match" failure. The error number
- PCRE_ERROR_CALLOUT is reserved for use by callout functions;
- it will never be used by PCRE itself.
+ Negative values should normally be chosen from the set of
+ PCRE_ERROR_xxx values. In particular, PCRE_ERROR_NOMATCH forces a stan-
+ dard "no match" failure. The error number PCRE_ERROR_CALLOUT is
+ reserved for use by callout functions; it will never be used by PCRE
+ itself.
Last updated: 21 January 2003
Copyright (c) 1997-2003 University of Cambridge.
-----------------------------------------------------------------------------
-NAME
- PCRE - Perl-compatible regular expressions
+PCRE(3) PCRE(3)
+
+NAME
+ PCRE - Perl-compatible regular expressions
+
DIFFERENCES FROM PERL
- This document describes the differences in the ways that
- PCRE and Perl handle regular expressions. The differences
- described here are with respect to Perl 5.8.
-
- 1. 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.
-
- 2. 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.
-
- 3. 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.
-
- 4. The following Perl escape sequences are not supported:
- \l, \u, \L, \U, \P, \p, and \X. In fact these are imple-
- mented by Perl's general string-handling and are not part of
- its pattern matching engine. If any of these are encountered
- by PCRE, an error is generated.
-
- 5. PCRE does support the \Q...\E escape for quoting sub-
- strings. Characters in between are treated as literals. This
- is slightly different from Perl in that $ and @ are also
- handled as literals inside the quotes. In Perl, they cause
- variable interpolation (but of course PCRE does not have
- variables). Note the following examples:
-
- Pattern PCRE matches Perl matches
-
- \Qabc$xyz\E abc$xyz abc followed by the
- contents of $xyz
- \Qabc\$xyz\E abc\$xyz abc\$xyz
- \Qabc\E\$\Qxyz\E abc$xyz abc$xyz
-
- In PCRE, the \Q...\E mechanism is not recognized inside a
- character class.
-
- 8. Fairly obviously, PCRE does not support the (?{code}) and
- (?p{code}) constructions. However, there is some experimen-
- tal support for recursive patterns using the non-Perl items
- (?R), (?number) and (?P>name). Also, the PCRE "callout"
- feature allows an external function to be called during pat-
- tern matching.
-
- 9. There are some differences that are concerned with the
- settings of captured strings when part of a pattern is
- repeated. For example, matching "aba" against the pattern
- /^(a(b)?)+$/ in Perl leaves $2 unset, but in PCRE it is set
- to "b".
-
- 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 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 first matching position in the subject string.
-
- (f) The PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and
- PCRE_NO_AUTO_CAPTURE options for pcre_exec() have no Perl
- equivalents.
-
- (g) The (?R), (?number), and (?P>name) constructs allows for
- recursive pattern matching (Perl can do this using the
- (?p{code}) construct, which PCRE cannot support.)
-
- (h) PCRE supports named capturing substrings, using the
- Python syntax.
-
- (i) PCRE supports the possessive quantifier "++" syntax,
- taken from Sun's Java package.
-
- (j) The (R) condition, for testing recursion, is a PCRE
- extension.
-
- (k) The callout facility is PCRE-specific.
+ This document describes the differences in the ways that PCRE and Perl
+ handle regular expressions. The differences described here are with
+ respect to Perl 5.8.
-Last updated: 03 February 2003
+ 1. PCRE does not have full UTF-8 support. Details of what it does have
+ are given in the section on UTF-8 support in the main pcre page.
+
+ 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 asser-
+ tions 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 succeed-
+ ing), 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 nor-
+ mal 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, \P, \p, \N, and \X. In fact these are implemented by Perl's general
+ string-handling and are not part of its pattern matching engine. If any
+ of these are encountered by PCRE, an error is generated.
+
+ 6. PCRE does support the \Q...\E escape for quoting substrings. Charac-
+ ters in between are treated as literals. This is slightly different
+ from Perl in that $ and @ are also handled as literals inside the
+ quotes. In Perl, they cause variable interpolation (but of course PCRE
+ does not have variables). Note the following examples:
+
+ Pattern PCRE matches Perl matches
+
+ \Qabc$xyz\E abc$xyz abc followed by the
+ contents of $xyz
+ \Qabc\$xyz\E abc\$xyz abc\$xyz
+ \Qabc\E\$\Qxyz\E abc$xyz abc$xyz
+
+ The \Q...\E sequence is recognized both inside and outside character
+ classes.
+
+ 7. Fairly obviously, PCRE does not support the (?{code}) and (?p{code})
+ constructions. However, there is some experimental support for recur-
+ sive patterns using the non-Perl items (?R), (?number) and (?P>name).
+ Also, the PCRE "callout" feature allows an external function to be
+ called during pattern matching.
+
+ 8. There are some differences that are concerned with the settings of
+ captured strings when part of a pattern is repeated. For example,
+ matching "aba" against the pattern /^(a(b)?)+$/ in Perl leaves $2
+ unset, but in PCRE it is set to "b".
+
+ 9. 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 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 spe-
+ cial meaning is faulted.
+
+ (d) If PCRE_UNGREEDY is set, the greediness of the repetition quanti-
+ fiers is inverted, that is, by default they are not greedy, but if fol-
+ lowed by a question mark they are.
+
+ (e) PCRE_ANCHORED can be used to force a pattern to be tried only at
+ the first matching position in the subject string.
+
+ (f) The PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and PCRE_NO_AUTO_CAP-
+ TURE options for pcre_exec() have no Perl equivalents.
+
+ (g) The (?R), (?number), and (?P>name) constructs allows for recursive
+ pattern matching (Perl can do this using the (?p{code}) construct,
+ which PCRE cannot support.)
+
+ (h) PCRE supports named capturing substrings, using the Python syntax.
+
+ (i) PCRE supports the possessive quantifier "++" syntax, taken from
+ Sun's Java package.
+
+ (j) The (R) condition, for testing recursion, is a PCRE extension.
+
+ (k) The callout facility is PCRE-specific.
+
+Last updated: 09 December 2003
Copyright (c) 1997-2003 University of Cambridge.
-----------------------------------------------------------------------------
-NAME
- PCRE - Perl-compatible regular expressions
+PCRE(3) PCRE(3)
+
+NAME
+ PCRE - Perl-compatible regular expressions
+
PCRE 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, covers them in great detail. The description here
- is intended as reference documentation.
-
- The basic operation of PCRE is on strings of bytes. However,
- there is also support for UTF-8 character strings. To use
- this support you must build PCRE to include UTF-8 support,
- and then call pcre_compile() with the PCRE_UTF8 option. How
- this affects the pattern matching is mentioned in several
- places below. There is also a summary of UTF-8 features in
- the section on UTF-8 support in the main pcre page.
-
- 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 string (or line, in multiline mode)
- $ assert end of string (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
- also "possessive 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
- [ POSIX character class (only if followed by POSIX
- syntax)
- ] terminates the character class
-
- The following sections describe the use of each of the
- meta-characters.
+ 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 copi-
+ ous examples. Jeffrey Friedl's "Mastering Regular Expressions", pub-
+ lished by O'Reilly, covers them in great detail. The description here
+ is intended as reference documentation.
+
+ The basic operation of PCRE is on strings of bytes. However, there is
+ also support for UTF-8 character strings. To use this support you must
+ build PCRE to include UTF-8 support, and then call pcre_compile() with
+ the PCRE_UTF8 option. How this affects the pattern matching is men-
+ tioned in several places below. There is also a summary of UTF-8 fea-
+ tures in the section on UTF-8 support in the main pcre page.
+
+ 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 alterna-
+ tives and repetitions in the pattern. 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 recog-
+ nized 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 string (or line, in multiline mode)
+ $ assert end of string (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
+ also "possessive 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
+ [ POSIX character class (only if followed by POSIX
+ syntax)
+ ] 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 escaping action 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 backslash 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, 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.
-
- If you want to remove the special meaning from a sequence of
- characters, you can do so by putting them between \Q and \E.
- This is different from Perl in that $ and @ are handled as
- literals in \Q...\E sequences in PCRE, whereas in Perl, $
- and @ cause variable interpolation. Note the following exam-
- ples:
-
- Pattern PCRE matches Perl matches
-
- \Qabc$xyz\E abc$xyz abc followed by the
-
- contents of $xyz
- \Qabc\$xyz\E abc\$xyz abc\$xyz
- \Qabc\E\$\Qxyz\E abc$xyz abc$xyz
-
- The \Q...\E sequence is recognized both inside and outside
- character classes.
-
- 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)
- \ddd character with octal code ddd, or backreference
- \xhh character with hex code hh
- \x{hhh..} character with hex code hhh... (UTF-8 mode only)
-
- 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, from zero to two hexadecimal digits are read
- (letters can be in upper or lower case). In UTF-8 mode, any
- number of hexadecimal digits may appear between \x{ and },
- but the value of the character code must be less than 2**31
- (that is, the maximum hexadecimal value is 7FFFFFFF). If
- characters other than hexadecimal digits appear between \x{
- and }, or if there is no terminating }, this form of escape
- is not recognized. Instead, the initial \x will be inter-
- preted as a basic hexadecimal escape, with no following
- digits, giving a byte whose value is zero.
-
- Characters whose value is less than 256 can be defined by
- either of the two syntaxes for \x when PCRE is in UTF-8
- mode. There is no difference in the way they are handled.
- For example, \xdc is exactly the same as \x{dc}.
-
- 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 (code value 7).
- 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 might be a back reference, otherwise the
- character with octal code 113
- \377 might be a back reference, otherwise
- the 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 or a sin-
- gle UTF-8 character (in UTF-8 mode) can be used both inside
- and outside character classes. In addition, inside a charac-
- ter class, the sequence \b is interpreted as the backspace
- character (hex 08). Outside a character class it has a dif-
- ferent 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.
-
- In UTF-8 mode, characters with values greater than 255 never
- match \d, \s, or \w, and always match \D, \S, and \W.
-
- For compatibility with Perl, \s does not match the VT char-
- acter (code 11). This makes it different from the the POSIX
- "space" class. The \s characters are HT (9), LF (10), FF
- (12), CR (13), and space (32).
-
- 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" in
- the pcreapi page). 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 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 matches at a word boundary
- \B matches when not at a word boundary
- \A matches at start of subject
- \Z matches at end of subject or before newline at end
- \z matches at end of subject
- \G matches at first matching position in subject
-
- 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. Thus, they are independent of mul-
- tiline mode.
-
- They are not affected by the PCRE_NOTBOL or PCRE_NOTEOL
- options. If the startoffset argument of pcre_exec() is non-
- zero, indicating that matching is to start at a point other
- than the beginning of the subject, \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.
-
- The \G assertion is true only when the current matching
- position is at the start point of the match, as specified by
- the startoffset argument of pcre_exec(). It differs from \A
- when the value of startoffset is non-zero. By calling
- pcre_exec() multiple times with appropriate arguments, you
- can mimic Perl's /g option, and it is in this kind of imple-
- mentation where \G can be useful.
-
- Note, however, that PCRE's interpretation of \G, as the
- start of the current match, is subtly different from Perl's,
- which defines it as the end of the previous match. In Perl,
- these can be different when the previously matched string
- was empty. Because PCRE does just one match at a time, it
- cannot reproduce this behaviour.
-
- If all the alternatives of a pattern begin with \G, the
- expression is anchored to the starting match position, and
- the "anchored" flag is set in the compiled regular expres-
- sion.
+ 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 escaping action 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 backslash 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 # charac-
+ ter as part of the pattern.
+
+ If you want to remove the special meaning from a sequence of charac-
+ ters, you can do so by putting them between \Q and \E. This is differ-
+ ent from Perl in that $ and @ are handled as literals in \Q...\E
+ sequences in PCRE, whereas in Perl, $ and @ cause variable interpola-
+ tion. Note the following examples:
+
+ Pattern PCRE matches Perl matches
+
+ \Qabc$xyz\E abc$xyz abc followed by the
+ contents of $xyz
+ \Qabc\$xyz\E abc\$xyz abc\$xyz
+ \Qabc\E\$\Qxyz\E abc$xyz abc$xyz
+
+ The \Q...\E sequence is recognized both inside and outside character
+ classes.
+
+ A second use of backslash provides a way of encoding non-printing char-
+ acters 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)
+ \ddd character with octal code ddd, or backreference
+ \xhh character with hex code hh
+ \x{hhh..} character with hex code hhh... (UTF-8 mode only)
+
+ 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, from zero to two hexadecimal digits are read (letters can be
+ in upper or lower case). In UTF-8 mode, any number of hexadecimal dig-
+ its may appear between \x{ and }, but the value of the character code
+ must be less than 2**31 (that is, the maximum hexadecimal value is
+ 7FFFFFFF). If characters other than hexadecimal digits appear between
+ \x{ and }, or if there is no terminating }, this form of escape is not
+ recognized. Instead, the initial \x will be interpreted as a basic hex-
+ adecimal escape, with no following digits, giving a byte whose value is
+ zero.
+
+ Characters whose value is less than 256 can be defined by either of the
+ two syntaxes for \x when PCRE is in UTF-8 mode. There is no difference
+ in the way they are handled. For example, \xdc is exactly the same as
+ \x{dc}.
+
+ 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 (code value 7). 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 compli-
+ cated. Outside a character class, PCRE reads it and any following dig-
+ its 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 following the backslash, and generates a sin-
+ gle 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 might be a back reference, otherwise the
+ character with octal code 113
+ \377 might be a back reference, otherwise
+ the 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 or a single UTF-8
+ character (in UTF-8 mode) 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.
+
+ In UTF-8 mode, characters with values greater than 255 never match \d,
+ \s, or \w, and always match \D, \S, and \W.
+
+ For compatibility with Perl, \s does not match the VT character (code
+ 11). This makes it different from the the POSIX "space" class. The \s
+ characters are HT (9), LF (10), FF (12), CR (13), and space (32).
+
+ 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 defini-
+ tion of letters and digits is controlled by PCRE's character tables,
+ and may vary if locale- specific matching is taking place (see "Locale
+ support" in the pcreapi page). 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 char-
+ acter 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 asser-
+ tion 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 matches at a word boundary
+ \B matches when not at a word boundary
+ \A matches at start of subject
+ \Z matches at end of subject or before newline at end
+ \z matches at end of subject
+ \G matches at first matching position in subject
+
+ These assertions may not appear in character classes (but note that \b
+ has a different meaning, namely the backspace character, inside a char-
+ acter 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. Thus,
+ they are independent of multiline mode.
+
+ They are not affected by the PCRE_NOTBOL or PCRE_NOTEOL options. If the
+ startoffset argument of pcre_exec() is non-zero, indicating that match-
+ ing is to start at a point other than the beginning of the subject, \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.
+
+ The \G assertion is true only when the current matching position is at
+ the start point of the match, as specified by the startoffset argument
+ of pcre_exec(). It differs from \A when the value of startoffset is
+ non-zero. By calling pcre_exec() multiple times with appropriate argu-
+ ments, you can mimic Perl's /g option, and it is in this kind of imple-
+ mentation where \G can be useful.
+
+ Note, however, that PCRE's interpretation of \G, as the start of the
+ current match, is subtly different from Perl's, which defines it as the
+ end of the previous match. In Perl, these can be different when the
+ previously matched string was empty. Because PCRE does just one match
+ at a time, it cannot reproduce this behaviour.
+
+ If all the alternatives of a pattern begin with \G, the expression is
+ anchored to the starting match position, and the "anchored" flag is set
+ in the compiled regular expression.
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 if the PCRE_MULTILINE
- option is unset. 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 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 newline character, respectively, in addi-
- tion 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 multi-
- line 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 it is always anchored,
- whether PCRE_MULTILINE is set or not.
+ 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 argu-
+ ment of pcre_exec() is non-zero, circumflex can never match if the
+ PCRE_MULTILINE option is unset. 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 sub-
+ ject, 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 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 immedi-
+ ately after and immediately before an internal newline character,
+ respectively, in addition to matching at the start and end of the sub-
+ ject 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 cir-
+ cumflex 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 it is 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. In UTF-8 mode, a dot
- matches any UTF-8 character, which might be more than one
- byte long, except (by default) for newline. If the
- PCRE_DOTALL option is set, 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.
-
+ Outside a character class, a dot in the pattern matches any one charac-
+ ter in the subject, including a non-printing character, but not (by
+ default) newline. In UTF-8 mode, a dot matches any UTF-8 character,
+ which might be more than one byte long, except (by default) for new-
+ line. If the PCRE_DOTALL option is set, dots match newlines as well.
+ The handling of dot is entirely independent of the handling of circum-
+ flex and dollar, the only relationship being that they both involve
+ newline characters. Dot has no special meaning in a character class.
MATCHING A SINGLE BYTE
- Outside a character class, the escape sequence \C matches
- any one byte, both in and out of UTF-8 mode. Unlike a dot,
- it always matches a newline. The feature is provided in Perl
- in order to match individual bytes in UTF-8 mode. Because
- it breaks up UTF-8 characters into individual bytes, what
- remains in the string may be a malformed UTF-8 string. For
- this reason it is best avoided.
+ Outside a character class, the escape sequence \C matches any one byte,
+ both in and out of UTF-8 mode. Unlike a dot, it always matches a new-
+ line. The feature is provided in Perl in order to match individual
+ bytes in UTF-8 mode. Because it breaks up UTF-8 characters into indi-
+ vidual bytes, what remains in the string may be a malformed UTF-8
+ string. For this reason it is best avoided.
- PCRE does not allow \C to appear in lookbehind assertions
- (see below), because in UTF-8 mode it makes it impossible to
- calculate the length of the lookbehind.
+ PCRE does not allow \C to appear in lookbehind assertions (see below),
+ because in UTF-8 mode it makes it impossible to calculate the length of
+ the lookbehind.
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.
- In UTF-8 mode, the character may occupy more than one byte.
- A matched character must be in the set of characters defined
- by the class, unless the first character in the class defin-
- ition 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 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.
-
- In UTF-8 mode, characters with values greater than 255 can
- be included in a class as a literal string of bytes, or by
- using the \x{ escaping mechanism.
-
- 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. PCRE does not support the concept of case
- for characters with values greater than 255.
- 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 the collating sequence of character
- values. They can also be used for characters specified
- numerically, for example [\000-\037]. In UTF-8 mode, ranges
- can include characters whose values are greater than 255,
- for example [\x{100}-\x{2ff}].
-
- 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.
+ An opening square bracket introduces a character class, terminated by a
+ closing square bracket. A closing square bracket on its own is not spe-
+ cial. 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. In UTF-8
+ mode, the character may occupy more than one byte. A matched character
+ must be in the set of characters defined by the class, unless the first
+ character in the class definition 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.
+
+ In UTF-8 mode, characters with values greater than 255 can be included
+ in a class as a literal string of bytes, or by using the \x{ escaping
+ mechanism.
+
+ 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. PCRE does not support the
+ concept of case for characters with values greater than 255.
+
+ 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 charac-
+ ters 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 charac-
+ ter 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 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 the collating sequence of character values. They can
+ also be used for characters specified numerically, for example
+ [\000-\037]. In UTF-8 mode, ranges can include characters whose values
+ are greater than 255, for example [\x{100}-\x{2ff}].
+
+ 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.
POSIX CHARACTER CLASSES
- Perl supports the POSIX notation for character classes,
- which uses names enclosed by [: and :] within the enclosing
- square brackets. PCRE also supports this notation. For exam-
- ple,
-
- [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
- blank space or tab only
- 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 (not quite the same as \s)
- upper upper case letters
- word "word" characters (same as \w)
- xdigit hexadecimal digits
-
- The "space" characters are HT (9), LF (10), VT (11), FF
- (12), CR (13), and space (32). Notice that this list
- includes the VT character (code 11). This makes "space" dif-
- ferent to \s, which does not include VT (for Perl compati-
- bility).
-
- The name "word" is a Perl extension, and "blank" is a GNU
- extension from Perl 5.8. 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
- recognize 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.
-
- In UTF-8 mode, characters with values greater than 255 do
- not match any of the POSIX character classes.
+ Perl supports the POSIX notation for character classes, which uses
+ names enclosed by [: and :] within the enclosing square brackets. PCRE
+ also 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
+ blank space or tab only
+ 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 (not quite the same as \s)
+ upper upper case letters
+ word "word" characters (same as \w)
+ xdigit hexadecimal digits
+
+ The "space" characters are HT (9), LF (10), VT (11), FF (12), CR (13),
+ and space (32). Notice that this list includes the VT character (code
+ 11). This makes "space" different to \s, which does not include VT (for
+ Perl compatibility).
+
+ The name "word" is a Perl extension, and "blank" is a GNU extension
+ from Perl 5.8. 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 recognize 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.
+
+ In UTF-8 mode, characters with values greater than 255 do not match any
+ of the POSIX character classes.
VERTICAL BAR
- Vertical bar characters are used to separate alternative
- patterns. For example, the pattern
+ Vertical bar characters are used to separate alternative patterns. For
+ example, the pattern
- gilbert|sullivan
+ 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.
+ 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 alterna-
+ tives are within a subpattern (defined below), "succeeds" means match-
+ ing the rest of the main pattern as well as the alternative in the sub-
+ pattern.
INTERNAL OPTION SETTING
- The settings of the PCRE_CASELESS, PCRE_MULTILINE,
- PCRE_DOTALL, and PCRE_EXTENDED options 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.
-
- When an option change occurs at top level (that is, not
- inside subpattern parentheses), the change applies to the
- remainder of the pattern that follows. If the change is
- placed right at the start of a pattern, PCRE extracts it
- into the global options (and it will therefore show up in
- data extracted by the pcre_fullinfo() function).
-
- An option change within a subpattern affects only that part
- of the current pattern 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.
+ The settings of the PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, and
+ PCRE_EXTENDED options 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 possi-
+ ble to unset these options by preceding the letter with a hyphen, and a
+ combined setting and unsetting such as (?im-sx), which sets PCRE_CASE-
+ LESS 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.
+
+ When an option change occurs at top level (that is, not inside subpat-
+ tern parentheses), the change applies to the remainder of the pattern
+ that follows. If the change is placed right at the start of a pattern,
+ PCRE extracts it into the global options (and it will therefore show up
+ in data extracted by the pcre_fullinfo() function).
+
+ An option change within a subpattern affects only that part of the cur-
+ rent pattern 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.
SUBPATTERNS
- Subpatterns are delimited by parentheses (round brackets),
- which can be nested. Marking part of a pattern as a subpat-
- tern does two things:
+ 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 pat-
- tern
+ 1. It localizes a set of alternatives. For example, the pattern
- cat(aract|erpillar|)
+ 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.
+ 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 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.
+ 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
+ ovector argument of pcre_exec(). 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
+ For example, if the string "the red king" is matched against the pat-
+ tern
- the ((red|white) (king|queen))
+ the ((red|white) (king|queen))
- the captured substrings are "red king", "red", and "king",
- and are numbered 1, 2, and 3, respectively.
+ the captured substrings are "red king", "red", and "king", and are num-
+ bered 1, 2, and 3, respectively.
- 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 a question mark and a
- colon, the subpattern does not do any capturing, and is not
- counted when computing the number of any subsequent captur-
- ing subpatterns. For example, if the string "the white
- queen" is matched against the pattern
+ 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 a question mark and a colon, the subpattern does not do any captur-
+ ing, 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 ((?:red|white) (king|queen))
- the captured substrings are "white queen" and "queen", and
- are numbered 1 and 2. The maximum number of capturing sub-
- patterns is 65535, and the maximum depth of nesting of all
- subpatterns, both capturing and non-capturing, is 200.
+ the captured substrings are "white queen" and "queen", and are numbered
+ 1 and 2. The maximum number of capturing subpatterns is 65535, and the
+ maximum depth of nesting 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
+ 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)
+ (?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".
+ 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".
NAMED SUBPATTERNS
- Identifying capturing parentheses by number is simple, but
- it can be very hard to keep track of the numbers in compli-
- cated regular expressions. Furthermore, if an expression is
- modified, the numbers may change. To help with the diffi-
- culty, PCRE supports the naming of subpatterns, something
- that Perl does not provide. The Python syntax (?P<name>...)
- is used. Names consist of alphanumeric characters and under-
- scores, and must be unique within a pattern.
+ Identifying capturing parentheses by number is simple, but it can be
+ very hard to keep track of the numbers in complicated regular expres-
+ sions. Furthermore, if an expression is modified, the numbers may
+ change. To help with the difficulty, PCRE supports the naming of sub-
+ patterns, something that Perl does not provide. The Python syntax
+ (?P<name>...) is used. Names consist of alphanumeric characters and
+ underscores, and must be unique within a pattern.
- Named capturing parentheses are still allocated numbers as
- well as names. The PCRE API provides function calls for
- extracting the name-to-number translation table from a com-
- piled pattern. For further details see the pcreapi documen-
- tation.
+ Named capturing parentheses are still allocated numbers as well as
+ names. The PCRE API provides function calls for extracting the name-to-
+ number translation table from a compiled pattern. For further details
+ see the pcreapi documentation.
REPETITION
- Repetition is specified by quantifiers, which can follow any
- of the following items:
+ Repetition is specified by quantifiers, which can follow any of the
+ following items:
+
+ a literal data character
+ the . metacharacter
+ the \C escape sequence
+ escapes such as \d that match single characters
+ a character class
+ a back reference (see next section)
+ a parenthesized subpattern (unless it is an assertion)
+
+ The general repetition quantifier specifies a minimum and maximum num-
+ ber 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 exam-
+ ple, {,6} is not a quantifier, but a literal string of four characters.
+
+ In UTF-8 mode, quantifiers apply to UTF-8 characters rather than to
+ individual bytes. Thus, for example, \x{100}{2} matches two UTF-8 char-
+ acters, each of which is represented by a two-byte sequence.
- a literal data character
- the . metacharacter
- the \C escape sequence
- escapes such as \d that match single characters
- a character class
- a back reference (see next section)
- a parenthesized subpattern (unless it is an assertion)
+ The quantifier {0} is permitted, causing the expression to behave as if
+ the previous item and the quantifier were not present.
- 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.
-
- In UTF-8 mode, quantifiers apply to UTF-8 characters rather
- than to individual bytes. Thus, for example, \x{100}{2}
- matches two UTF-8 characters, each of which is represented
- by a two-byte sequence.
-
- 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:
+ For convenience (and historical compatibility) the three most common
+ quantifiers have single-character abbreviations:
- (a?)*
+ * is equivalent to {0,}
+ + is equivalent to {1,}
+ ? is equivalent to {0,1}
- 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.
+ 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:
- 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
+ (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 bro-
+ ken.
- to the string
+ 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, indi-
+ vidual * and / characters may appear. An attempt to match C comments by
+ applying the pattern
- /* first command */ not comment /* second comment */
+ /\*.*\*/
- fails, because it matches the entire string owing to the
- greediness of the .* item.
+ to the string
- However, if a quantifier is followed by a question mark, it
- ceases to be greedy, and instead matches the minimum number
- of times possible, so the pattern
+ /* first command */ not comment /* second comment */
- /\*.*?\*/
+ fails, because it matches the entire string owing to the greediness of
+ the .* item.
- 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
+ However, if a quantifier is followed by a question mark, it ceases to
+ be greedy, and instead matches the minimum number of times possible, so
+ the pattern
- \d??\d
+ /\*.*?\*/
- which matches one digit by preference, but can match two if
- that is the only way the rest of the pattern matches.
+ 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
- If the PCRE_UNGREEDY option is set (an option which is not
- available in Perl), 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.
+ \d??\d
- 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, 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 normally treats such a pattern as though it were pre-
- ceded by \A.
+ which matches one digit by preference, but can match two if that is the
+ only way the rest of the pattern matches.
- In cases where it is known that the subject string contains
- no newlines, it is worth setting PCRE_DOTALL in order to
- obtain this optimization, or alternatively using ^ to indi-
- cate anchoring explicitly.
+ If the PCRE_UNGREEDY option is set (an option which is not available in
+ Perl), 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.
- However, there is one situation where the optimization can-
- not be used. When .* is inside capturing parentheses that
- are the subject of a backreference elsewhere in the pattern,
- a match at the start may fail, and a later one succeed. Con-
- sider, for example:
+ 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.
- (.*)abc\1
+ If a pattern starts with .* or .{0,} and the PCRE_DOTALL option (equiv-
+ alent to Perl's /s) is set, thus allowing the . to match newlines, 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 normally treats such a pattern as though it were preceded by \A.
- If the subject is "xyz123abc123" the match point is the
- fourth character. For this reason, such a pattern is not
- implicitly anchored.
+ In cases where it is known that the subject string contains no new-
+ lines, it is worth setting PCRE_DOTALL in order to obtain this opti-
+ mization, 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
+ However, there is one situation where the optimization cannot be used.
+ When .* is inside capturing parentheses that are the subject of a
+ backreference elsewhere in the pattern, a match at the start may fail,
+ and a later one succeed. Consider, for example:
- (tweedle[dume]{3}\s*)+
+ (.*)abc\1
- 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
+ If the subject is "xyz123abc123" the match point is the fourth charac-
+ ter. For this reason, such a pattern is not implicitly anchored.
- /(a|(b))+/
+ When a capturing subpattern is repeated, the value captured is the sub-
+ string that matched the final iteration. For example, after
- matches "aba" the value of the second captured substring is
- "b".
+ (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 itera-
+ tions. For example, after
+
+ /(a|(b))+/
+
+ matches "aba" the value of the second captured substring is "b".
ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS
- 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. "Atomic grouping" (a term taken
- from Jeffrey Friedl's book) provides the means for specify-
- ing that once a subpattern has matched, it is not to be re-
- evaluated in this way.
-
- If we use atomic grouping for the previous example, the
- matcher would give up immediately on failing to match "foo"
- the first time. The notation is a 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.
-
- Atomic grouping 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.
-
- Atomic groups in general can of course contain arbitrarily
- complicated subpatterns, and can be nested. However, when
- the subpattern for an atomic group is just a single repeated
- item, as in the example above, a simpler notation, called a
- "possessive quantifier" can be used. This consists of an
- additional + character following a quantifier. Using this
- notation, the previous example can be rewritten as
-
- \d++bar
-
- Possessive quantifiers are always greedy; the setting of the
- PCRE_UNGREEDY option is ignored. They are a convenient nota-
- tion for the simpler forms of atomic group. However, there
- is no difference in the meaning or processing of a posses-
- sive quantifier and the equivalent atomic group.
-
- The possessive quantifier syntax is an extension to the Perl
- syntax. It originates in Sun's Java package.
-
- When a pattern contains an unlimited repeat inside a subpat-
- tern that can itself be repeated an unlimited number of
- times, the use of an atomic group 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.
+ With both maximizing and minimizing repetition, failure of what follows
+ normally causes the repeated item to be re-evaluated to see if a dif-
+ ferent number of repeats allows the rest of the pattern to match. Some-
+ times 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.
+ "Atomic grouping" (a term taken from Jeffrey Friedl's book) provides
+ the means for specifying that once a subpattern has matched, it is not
+ to be re-evaluated in this way.
+
+ If we use atomic grouping for the previous example, the matcher would
+ give up immediately on failing to match "foo" the first time. The nota-
+ tion is a kind of special parenthesis, starting with (?> as in this
+ example:
+
+ (?>\d+)foo
+
+ This kind of parenthesis "locks up" the part of the pattern it con-
+ tains 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.
+
+ Atomic grouping 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 pre-
+ pared 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.
+
+ Atomic groups in general can of course contain arbitrarily complicated
+ subpatterns, and can be nested. However, when the subpattern for an
+ atomic group is just a single repeated item, as in the example above, a
+ simpler notation, called a "possessive quantifier" can be used. This
+ consists of an additional + character following a quantifier. Using
+ this notation, the previous example can be rewritten as
+
+ \d++bar
+
+ Possessive quantifiers are always greedy; the setting of the
+ PCRE_UNGREEDY option is ignored. They are a convenient notation for the
+ simpler forms of atomic group. However, there is no difference in the
+ meaning or processing of a possessive quantifier and the equivalent
+ atomic group.
+
+ The possessive quantifier syntax is an extension to the Perl syntax. It
+ originates in Sun's Java package.
+
+ When a pattern contains an unlimited repeat inside a subpattern that
+ can itself be repeated an unlimited number of times, the use of an
+ atomic group 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 opti-
+ mization 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.
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 (that is, 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 (see "Subpatterns as
- subroutines" below for a way of doing that). 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, 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.
-
- Back references to named subpatterns use the Python syntax
- (?P=name). We could rewrite the above example as follows:
-
- (?<p1>(?i)rah)\s+(?P=p1)
-
- 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, 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 many capturing parentheses in a pat-
- tern, all digits following the backslash are taken as part
- of a potential back reference number. If the pattern contin-
- ues with a digit character, 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 pat-
- tern
-
- (a|b\1)+
-
- matches any number of "a"s and also "aba", "ababbaa" 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.
+ Outside a character class, a backslash followed by a digit greater than
+ 0 (and possibly further digits) is a back reference to a capturing sub-
+ pattern earlier (that is, 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 pat-
+ tern. 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 dig-
+ its following a backslash.
+
+ A back reference matches whatever actually matched the capturing sub-
+ pattern in the current subject string, rather than anything matching
+ the subpattern itself (see "Subpatterns as subroutines" below for a way
+ of doing that). 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, the case of letters is relevant. For exam-
+ ple,
+
+ ((?i)rah)\s+\1
+
+ matches "rah rah" and "RAH RAH", but not "RAH rah", even though the
+ original capturing subpattern is matched caselessly.
+
+ Back references to named subpatterns use the Python syntax (?P=name).
+ We could rewrite the above example as follows:
+
+ (?<p1>(?i)rah)\s+(?P=p1)
+
+ There may be more than one back reference to the same subpattern. If a
+ subpattern has not actually been used in a particular match, 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 many capturing parentheses in a pattern, all digits following
+ the backslash are taken as part of a potential back reference number.
+ If the pattern continues with a digit character, 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 sub-
+ patterns. For example, the pattern
+
+ (a|b\1)+
+
+ matches any number of "a"s and also "aba", "ababbaa" etc. At each iter-
+ ation 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.
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, \G, \Z, \z, ^ and $ are described above. More com-
- plicated 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 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, \G, \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,
+ 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+(?=;)
+ \w+(?=;)
- matches a word followed by a semicolon, but does not include
- the semicolon in the match, and
+ matches a word followed by a semicolon, but does not include the semi-
+ colon in the match, and
- foo(?!bar)
+ foo(?!bar)
- matches any occurrence of "foo" that is not followed by
- "bar". Note that the apparently similar pattern
+ matches any occurrence of "foo" that is not followed by "bar". Note
+ that the apparently similar pattern
- (?!foo)bar
+ (?!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.
+ 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.
- If you want to force a matching failure at some point in a
- pattern, the most convenient way to do it is with (?!)
- because an empty string always matches, so an assertion that
- requires there not to be an empty string must always fail.
+ If you want to force a matching failure at some point in a pattern, the
+ most convenient way to do it is with (?!) because an empty string
+ always matches, so an assertion that requires there not to be an empty
+ string must always fail.
- Lookbehind assertions start with (?<= for positive asser-
- tions and (?<! for negative assertions. For example,
+ Lookbehind assertions start with (?<= for positive assertions and (?<!
+ for negative assertions. For example,
- (?<!foo)bar
+ (?<!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
+ 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 sev-
+ eral alternatives, they do not all have to have the same fixed length.
+ Thus
- (?<=bullock|donkey)
+ (?<=bullock|donkey)
- is permitted, but
+ is permitted, but
- (?<!dogs?|cats?)
+ (?<!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 (at least for 5.8), which requires all branches to
- match the same length of string. An assertion such as
+ 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 (at least for 5.8), which
+ requires all branches to match the same length of string. An assertion
+ such as
- (?<=ab(c|de))
+ (?<=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:
+ 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)
+ (?<=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.
+ 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 cur-
+ rent position, the match is deemed to fail.
- PCRE does not allow the \C escape (which matches a single
- byte in UTF-8 mode) to appear in lookbehind assertions,
- because it makes it impossible to calculate the length of
- the lookbehind.
+ PCRE does not allow the \C escape (which matches a single byte in UTF-8
+ mode) to appear in lookbehind assertions, because it makes it impossi-
+ ble to calculate the length of the lookbehind.
- Atomic groups 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
+ Atomic groups 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$
+ abcd$
- when applied to a long string that 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
+ when applied to a long string that 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$
+ ^.*abcd$
- the initial .* matches the entire string at first, but when
- this fails (because there is no following "a"), it back-
- tracks 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
+ 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)
+ ^(?>.*)(?<=abcd)
- or, equivalently,
+ or, equivalently,
- ^.*+(?<=abcd)
+ ^.*+(?<=abcd)
- 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.
+ 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.
- Several assertions (of any sort) may occur in succession.
- For example,
+ Several assertions (of any sort) may occur in succession. For example,
- (?<=\d{3})(?<!999)foo
+ (?<=\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, and
- 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
+ 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, and then there is a check that the same
+ three characters are not "999". This pattern does not match "foo" pre-
+ ceded by six characters, the first of which are digits and the last
+ three of which are not "999". For example, it doesn't match "123abc-
+ foo". A pattern to do that is
- (?<=\d{3}...)(?<!999)foo
+ (?<=\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".
+ 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,
+ Assertions can be nested in any combination. For example,
- (?<=(?<!foo)bar)baz
+ (?<=(?<!foo)bar)baz
- matches an occurrence of "baz" that is preceded by "bar"
- which in turn is not preceded by "foo", while
+ matches an occurrence of "baz" that is preceded by "bar" which in turn
+ is not preceded by "foo", while
- (?<=\d{3}(?!999)...)foo
+ (?<=\d{3}(?!999)...)foo
- is another pattern which matches "foo" preceded by three
- digits and any three characters that are not "999".
+ 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.
+ 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 sub-
+ patterns in the whole pattern. However, substring capturing is carried
+ out only for positive assertions, because it does not make sense for
+ negative assertions.
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 three kinds of condition. If the text between the
- parentheses consists of a sequence of digits, the condition
- is satisfied if the capturing subpattern of that number has
- previously matched. The number must be greater than zero.
- 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 the string (R), it is satisfied if a
- recursive call to the pattern or subpattern has been made.
- At "top level", the condition is false. This is a PCRE
- extension. Recursive patterns are described in the next
- section.
-
- If the condition is not a sequence of digits or (R), it must
- be an assertion. This may be a positive or negative looka-
- head 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.
+ It is possible to cause the matching process to obey a subpattern con-
+ ditionally 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 sub-
+ pattern 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 alterna-
+ tives in the subpattern, a compile-time error occurs.
+
+ There are three kinds of condition. If the text between the parentheses
+ consists of a sequence of digits, the condition is satisfied if the
+ capturing subpattern of that number has previously matched. The number
+ must be greater than zero. Consider the following pattern, which con-
+ tains 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 sec-
+ ond 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-pat-
+ tern 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 the string (R), it is satisfied if a recursive call
+ to the pattern or subpattern has been made. At "top level", the condi-
+ tion is false. This is a PCRE extension. Recursive patterns are
+ described in the next section.
+
+ If the condition is not a sequence of digits or (R), 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.
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.
+ 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 contin-
- ues up to the next newline character in the pattern.
+ If the PCRE_EXTENDED option is set, an unescaped # character outside a
+ character class introduces a comment that continues up to the next new-
+ line 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 has pro-
- vided an experimental facility that allows regular expres-
- sions 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, it supports some special syntax for
- recursion of the entire pattern, and also for individual
- subpattern recursion.
-
- The special item that consists of (? followed by a number
- greater than zero and a closing parenthesis is a recursive
- call of the subpattern of the given number, provided that it
- occurs inside that subpattern. (If not, it is a "subroutine"
- call, which is described in the next section.) The special
- item (?R) is a recursive call of the entire regular expres-
- sion.
-
- For example, this PCRE pattern solves the nested 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
- (that is a correctly parenthesized substring). Finally
- there is a closing parenthesis.
-
- If this were part of a larger pattern, you would not want to
- recurse the entire pattern, so instead you could use this:
-
- ( \( ( (?>[^()]+) | (?1) )* \) )
-
- We have put the pattern into parentheses, and caused the
- recursion to refer to them instead of the whole pattern. In
- a larger pattern, keeping track of parenthesis numbers can
- be tricky. It may be more convenient to use named
- parentheses instead. For this, PCRE uses (?P>name), which is
- an extension to the Python syntax that PCRE uses for named
- parentheses (Perl does not provide named parentheses). We
- could rewrite the above example as follows:
-
- (?<pn> \( ( (?>[^()]+) | (?P>pn) )* \) )
-
- This particular example pattern contains nested unlimited
- repeats, and so the use of atomic grouping for matching
- strings of non-parentheses is important when applying the
- pattern to strings that do not match. For example, when this
- pattern is applied to
-
- (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa()
-
- it yields "no match" quickly. However, if atomic grouping 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.
- At the end of a match, the values set for any capturing sub-
- patterns are those from the outermost level of the recursion
- at which the subpattern value is set. If you want to obtain
- intermediate values, a callout function can be used (see
- below and the pcrecallout documentation). 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
-
- \( ( ( (?>[^()]+) | (?R) )* ) \)
- ^ ^
- ^ ^
-
- 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, the match fails with the
- PCRE_ERROR_NOMEMORY error.
-
- Do not confuse the (?R) item with the condition (R), which
- tests for recursion. Consider this pattern, which matches
- text in angle brackets, allowing for arbitrary nesting. Only
- digits are allowed in nested brackets (that is, when recurs-
- ing), whereas any characters are permitted at the outer
- level.
-
- < (?: (?(R) \d++ | [^<>]*+) | (?R)) * >
-
- In this pattern, (?(R) is the start of a conditional subpat-
- tern, with two different alternatives for the recursive and
- non-recursive cases. The (?R) item is the actual recursive
- call.
+ 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 has provided an experimental facility that allows regular
+ expressions to recurse (amongst other things). It does this by interpo-
+ lating Perl code in the expression at run time, and the code can refer
+ to the expression itself. A Perl pattern to solve the parentheses prob-
+ lem 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, it supports
+ some special syntax for recursion of the entire pattern, and also for
+ individual subpattern recursion.
+
+ The special item that consists of (? followed by a number greater than
+ zero and a closing parenthesis is a recursive call of the subpattern of
+ the given number, provided that it occurs inside that subpattern. (If
+ not, it is a "subroutine" call, which is described in the next sec-
+ tion.) The special item (?R) is a recursive call of the entire regular
+ expression.
+
+ For example, this PCRE pattern solves the nested 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 (that is a correctly parenthe-
+ sized substring). Finally there is a closing parenthesis.
+
+ If this were part of a larger pattern, you would not want to recurse
+ the entire pattern, so instead you could use this:
+
+ ( \( ( (?>[^()]+) | (?1) )* \) )
+
+ We have put the pattern into parentheses, and caused the recursion to
+ refer to them instead of the whole pattern. In a larger pattern, keep-
+ ing track of parenthesis numbers can be tricky. It may be more conve-
+ nient to use named parentheses instead. For this, PCRE uses (?P>name),
+ which is an extension to the Python syntax that PCRE uses for named
+ parentheses (Perl does not provide named parentheses). We could rewrite
+ the above example as follows:
+
+ (?P<pn> \( ( (?>[^()]+) | (?P>pn) )* \) )
+
+ This particular example pattern contains nested unlimited repeats, and
+ so the use of atomic grouping for matching strings of non-parentheses
+ is important when applying the pattern to strings that do not match.
+ For example, when this pattern is applied to
+
+ (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa()
+
+ it yields "no match" quickly. However, if atomic grouping 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.
+
+ At the end of a match, the values set for any capturing subpatterns are
+ those from the outermost level of the recursion at which the subpattern
+ value is set. If you want to obtain intermediate values, a callout
+ function can be used (see below and the pcrecallout documentation). 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
+
+ \( ( ( (?>[^()]+) | (?R) )* ) \)
+ ^ ^
+ ^ ^
+
+ 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 pat-
+ tern, PCRE has to obtain extra memory to store data during a recursion,
+ which it does by using pcre_malloc, freeing it via pcre_free after-
+ wards. If no memory can be obtained, the match fails with the
+ PCRE_ERROR_NOMEMORY error.
+
+ Do not confuse the (?R) item with the condition (R), which tests for
+ recursion. Consider this pattern, which matches text in angle brack-
+ ets, allowing for arbitrary nesting. Only digits are allowed in nested
+ brackets (that is, when recursing), whereas any characters are permit-
+ ted at the outer level.
+
+ < (?: (?(R) \d++ | [^<>]*+) | (?R)) * >
+
+ In this pattern, (?(R) is the start of a conditional subpattern, with
+ two different alternatives for the recursive and non-recursive cases.
+ The (?R) item is the actual recursive call.
SUBPATTERNS AS SUBROUTINES
- If the syntax for a recursive subpattern reference (either
- by number or by name) is used outside the parentheses to
- which it refers, it operates like a subroutine in a program-
- ming language. An earlier example pointed out that the pat-
- tern
+ If the syntax for a recursive subpattern reference (either by number or
+ by name) is used outside the parentheses to which it refers, it oper-
+ ates like a subroutine in a programming language. An earlier example
+ pointed out that the pattern
- (sens|respons)e and \1ibility
+ (sens|respons)e and \1ibility
- matches "sense and sensibility" and "response and responsi-
- bility", but not "sense and responsibility". If instead the
- pattern
+ matches "sense and sensibility" and "response and responsibility", but
+ not "sense and responsibility". If instead the pattern
- (sens|respons)e and (?1)ibility
+ (sens|respons)e and (?1)ibility
- is used, it does match "sense and responsibility" as well as
- the other two strings. Such references must, however, follow
- the subpattern to which they refer.
+ is used, it does match "sense and responsibility" as well as the other
+ two strings. Such references must, however, follow the subpattern to
+ which they refer.
CALLOUTS
- Perl has a feature whereby using the sequence (?{...})
- causes arbitrary Perl code to be obeyed in the middle of
- matching a regular expression. This makes it possible,
- amongst other things, to extract different substrings that
- match the same pair of parentheses when there is a repeti-
- tion.
-
- PCRE provides a similar feature, but of course it cannot
- obey arbitrary Perl code. The feature is called "callout".
- The caller of PCRE provides an external function by putting
- its entry point in the global variable pcre_callout. By
- default, this variable contains NULL, which disables all
- calling out.
-
- Within a regular expression, (?C) indicates the points at
- which the external function is to be called. If you want to
- identify different callout points, you can put a number less
- than 256 after the letter C. The default value is zero. For
- example, this pattern has two callout points:
-
- (?C1)\e9abc(?C2)def
-
- During matching, when PCRE reaches a callout point (and
- pcre_callout is set), the external function is called. It is
- provided with the number of the callout, and, optionally,
- one item of data originally supplied by the caller of
- pcre_exec(). The callout function may cause matching to
- backtrack, or to fail altogether. A complete description of
- the interface to the callout function is given in the pcre-
- callout documentation.
+ Perl has a feature whereby using the sequence (?{...}) causes arbitrary
+ Perl code to be obeyed in the middle of matching a regular expression.
+ This makes it possible, amongst other things, to extract different sub-
+ strings that match the same pair of parentheses when there is a repeti-
+ tion.
+
+ PCRE provides a similar feature, but of course it cannot obey arbitrary
+ Perl code. The feature is called "callout". The caller of PCRE provides
+ an external function by putting its entry point in the global variable
+ pcre_callout. By default, this variable contains NULL, which disables
+ all calling out.
+
+ Within a regular expression, (?C) indicates the points at which the
+ external function is to be called. If you want to identify different
+ callout points, you can put a number less than 256 after the letter C.
+ The default value is zero. For example, this pattern has two callout
+ points:
+
+ (?C1)abc(?C2)def
+
+ During matching, when PCRE reaches a callout point (and pcre_callout is
+ set), the external function is called. It is provided with the number
+ of the callout, and, optionally, one item of data originally supplied
+ by the caller of pcre_exec(). The callout function may cause matching
+ to backtrack, or to fail altogether. A complete description of the
+ interface to the callout function is given in the pcrecallout documen-
+ tation.
Last updated: 03 February 2003
Copyright (c) 1997-2003 University of Cambridge.
-----------------------------------------------------------------------------
-NAME
- PCRE - Perl-compatible regular expressions
+PCRE(3) PCRE(3)
+
+
+NAME
+ PCRE - Perl-compatible regular expressions
PCRE PERFORMANCE
- Certain items that may appear in regular expression 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 discus-
- sion about optimizing regular expressions for efficient per-
- formance.
-
- When a pattern begins with .* not in parentheses, or in
- parentheses that are not the subject of a backreference, 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 match starting at the seventh
- character. 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.
+ Certain items that may appear in regular expression 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 gen-
+ eral, 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 perfor-
+ mance.
+
+ When a pattern begins with .* not in parentheses, or in parentheses
+ that are not the subject of a backreference, 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 new-
+ lines, 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 match starting at the seventh character. 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 con-
+ tain 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 sub-
+ ject string, and if there is not, it fails the match immediately. How-
+ ever, 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.
Last updated: 03 February 2003
Copyright (c) 1997-2003 University of Cambridge.
-----------------------------------------------------------------------------
-NAME
- PCRE - Perl-compatible regular expressions.
+PCRE(3) PCRE(3)
+
+NAME
+ PCRE - Perl-compatible regular expressions.
+
SYNOPSIS OF POSIX API
- #include <pcreposix.h>
- int regcomp(regex_t *preg, const char *pattern,
- int cflags);
+ 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);
+ 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);
+ size_t regerror(int errcode, const regex_t *preg,
+ char *errbuf, size_t errbuf_size);
- void regfree(regex_t *preg);
+ void regfree(regex_t *preg);
DESCRIPTION
- This set of functions provides a POSIX-style API to the PCRE
- regular expression package. See the pcreapi documentation
- for a description of the native API, which contains addi-
- tional functionality.
-
- The functions described here are just wrapper functions that
- ultimately call the PCRE 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 applica-
- tion 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. "POSIX-like in style" means that the API approximates
- to the POSIX definition; it is not fully POSIX-compatible,
- and in multi-byte encoding domains it is probably even less
- compatible.
-
- 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.
+ This set of functions provides a POSIX-style API to the PCRE regular
+ expression package. See the pcreapi documentation for a description of
+ the native API, which contains additional functionality.
+
+ The functions described here are just wrapper functions that ultimately
+ call the PCRE 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 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 expres-
+ sions themselves are still those of Perl, subject to the setting of
+ various PCRE options, as described below. "POSIX-like in style" means
+ that the API approximates to the POSIX definition; it is not fully
+ POSIX-compatible, and in multi-byte encoding domains it is probably
+ even less compatible.
+
+ 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 reg-
+ match_t for returning captured substrings. It also defines some con-
+ stants 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 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 expression.
- The argument cflags is either zero, or contains one or more
- of the bits defined by the following macros:
+ The argument cflags is either zero, or contains one or more of the bits
+ defined by the following macros:
- REG_ICASE
+ REG_ICASE
- The PCRE_CASELESS option is set when the expression is
- passed for compilation to the native function.
+ The PCRE_CASELESS option is set when the expression is passed for com-
+ pilation to the native function.
- REG_NEWLINE
+ REG_NEWLINE
- The PCRE_MULTILINE option is set when the expression is
- passed for compilation to the native function. Note that
- this does not mimic the defined POSIX behaviour for
- REG_NEWLINE (see the following section).
+ The PCRE_MULTILINE option is set when the expression is passed for com-
+ pilation to the native function. Note that this does not mimic the
+ defined POSIX behaviour for REG_NEWLINE (see the following section).
- In the absence of these flags, no options are passed to the
- native function. This means the the regex is compiled with
- PCRE default semantics. In particular, the way it handles
- newline characters in the subject string is the Perl way,
- not the POSIX way. Note that setting PCRE_MULTILINE has only
- some of the effects specified for REG_NEWLINE. It does not
- affect the way newlines are matched by . (they aren't) or by
- a negative class such as [^a] (they are).
+ In the absence of these flags, no options are passed to the native
+ function. This means the the regex is compiled with PCRE default
+ semantics. In particular, the way it handles newline characters in the
+ subject string is the Perl way, not the POSIX way. Note that setting
+ PCRE_MULTILINE has only some of the effects specified for REG_NEWLINE.
+ It does not affect the way newlines are matched by . (they aren't) or
+ by a negative class such as [^a] (they are).
- 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 public: re_nsub contains the
- number of capturing subpatterns in the regular expression.
- Various error codes are defined in the header file.
+ The yield of regcomp() is zero on success, and non-zero otherwise. The
+ preg structure is filled in on success, and one member of the structure
+ is public: re_nsub contains the number of capturing subpatterns in the
+ regular expression. Various error codes are defined in the header file.
MATCHING NEWLINE CHARACTERS
- This area is not simple, because POSIX and Perl take dif-
- ferent views of things. It is not possible to get PCRE to
- obey POSIX semantics, but then PCRE was never intended to be
- a POSIX engine. The following table lists the different pos-
- sibilities for matching newline characters in PCRE:
+ This area is not simple, because POSIX and Perl take different views of
+ things. It is not possible to get PCRE to obey POSIX semantics, but
+ then PCRE was never intended to be a POSIX engine. The following table
+ lists the different possibilities for matching newline characters in
+ PCRE:
- Default Change with
+ Default Change with
- . matches newline no PCRE_DOTALL
- newline matches [^a] yes not changeable
- $ matches \n at end yes PCRE_DOLLARENDONLY
- $ matches \n in middle no PCRE_MULTILINE
- ^ matches \n in middle no PCRE_MULTILINE
+ . matches newline no PCRE_DOTALL
+ newline matches [^a] yes not changeable
+ $ matches \n at end yes PCRE_DOLLARENDONLY
+ $ matches \n in middle no PCRE_MULTILINE
+ ^ matches \n in middle no PCRE_MULTILINE
- This is the equivalent table for POSIX:
+ This is the equivalent table for POSIX:
- Default Change with
+ Default Change with
- . matches newline yes REG_NEWLINE
- newline matches [^a] yes REG_NEWLINE
- $ matches \n at end no REG_NEWLINE
- $ matches \n in middle no REG_NEWLINE
- ^ matches \n in middle no REG_NEWLINE
+ . matches newline yes REG_NEWLINE
+ newline matches [^a] yes REG_NEWLINE
+ $ matches \n at end no REG_NEWLINE
+ $ matches \n in middle no REG_NEWLINE
+ ^ matches \n in middle no REG_NEWLINE
- PCRE's behaviour is the same as Perl's, except that there is
- no equivalent for PCRE_DOLLARENDONLY in Perl. In both PCRE
- and Perl, there is no way to stop newline from matching
- [^a].
+ PCRE's behaviour is the same as Perl's, except that there is no equiva-
+ lent for PCRE_DOLLARENDONLY in Perl. In both PCRE and Perl, there is no
+ way to stop newline from matching [^a].
- The default POSIX newline handling can be obtained by set-
- ting PCRE_DOTALL and PCRE_DOLLARENDONLY, but there is no way
- to make PCRE behave exactly as for the REG_NEWLINE action.
+ The default POSIX newline handling can be obtained by setting
+ PCRE_DOTALL and PCRE_DOLLARENDONLY, but there is no way to make PCRE
+ behave exactly as for the REG_NEWLINE action.
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:
+ 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
+ REG_NOTBOL
- The PCRE_NOTBOL option is set when calling the underlying
- PCRE matching function.
+ The PCRE_NOTBOL option is set when calling the underlying PCRE matching
+ function.
- REG_NOTEOL
+ REG_NOTEOL
- The PCRE_NOTEOL option is set when calling the underlying
- PCRE matching function.
+ 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.
+ The portion of the string that was matched, and also any captured sub-
+ strings, 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 sub-
+ string and the offset to the first character after the end of each sub-
+ string, 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.
+ 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.
+ 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 func-
+ tion 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.
+ Compiling a regular expression causes memory to be allocated and asso-
+ ciated with the preg structure. The function regfree() frees all such
+ memory, after which preg may no longer be used as a compiled expres-
+ sion.
AUTHOR
- Philip Hazel <ph10@cam.ac.uk>
- University Computing Service,
- Cambridge CB2 3QG, England.
+
Philip Hazel <ph10@cam.ac.uk>
+ University Computing Service,
+ Cambridge CB2 3QG, England.
Last updated: 03 February 2003
Copyright (c) 1997-2003 University of Cambridge.
-----------------------------------------------------------------------------
-NAME
- PCRE - Perl-compatible regular expressions
+PCRE(3) PCRE(3)
+
+NAME
+ PCRE - Perl-compatible regular expressions
+
PCRE SAMPLE PROGRAM
- A simple, complete demonstration program, to get you started
- with using PCRE, is supplied in the file pcredemo.c in the
- PCRE distribution.
+ A simple, complete demonstration program, to get you started with using
+ PCRE, is supplied in the file pcredemo.c in the PCRE distribution.
- The program compiles the regular expression that is its
- first argument, and matches it against the subject string in
- its second argument. No PCRE options are set, and default
- character tables are used. If matching succeeds, the program
- outputs the portion of the subject that matched, together
- with the contents of any captured substrings.
+ The program compiles the regular expression that is its first argument,
+ and matches it against the subject string in its second argument. No
+ PCRE options are set, and default character tables are used. If match-
+ ing succeeds, the program outputs the portion of the subject that
+ matched, together with the contents of any captured substrings.
- If the -g option is given on the command line, the program
- then goes on to check for further matches of the same regu-
- lar expression in the same subject string. The logic is a
- little bit tricky because of the possibility of matching an
- empty string. Comments in the code explain what is going on.
+ If the -g option is given on the command line, the program then goes on
+ to check for further matches of the same regular expression in the same
+ subject string. The logic is a little bit tricky because of the possi-
+ bility of matching an empty string. Comments in the code explain what
+ is going on.
- On a Unix system that has PCRE installed in /usr/local, you
- can compile the demonstration program using a command like
- this:
+ On a Unix system that has PCRE installed in /usr/local, you can compile
+ the demonstration program using a command like this:
- gcc -o pcredemo pcredemo.c -I/usr/local/include \
- -L/usr/local/lib -lpcre
+ gcc -o pcredemo pcredemo.c -I/usr/local/include \
+ -L/usr/local/lib -lpcre
- Then you can run simple tests like this:
+ Then you can run simple tests like this:
- ./pcredemo 'cat|dog' 'the cat sat on the mat'
- ./pcredemo -g 'cat|dog' 'the dog sat on the cat'
+ ./pcredemo 'cat|dog' 'the cat sat on the mat'
+ ./pcredemo -g 'cat|dog' 'the dog sat on the cat'
- Note that there is a much more comprehensive test program,
- called pcretest, which supports many more facilities for
- testing regular expressions and the PCRE library. The
- pcredemo program is provided as a simple coding example.
+ Note that there is a much more comprehensive test program, called
+ pcretest, which supports many more facilities for testing regular
+ expressions and the PCRE library. The pcredemo program is provided as a
+ simple coding example.
- On some operating systems (e.g. Solaris) you may get an
- error like this when you try to run pcredemo:
+ On some operating systems (e.g. Solaris) you may get an error like this
+ when you try to run pcredemo:
- ld.so.1: a.out: fatal: libpcre.so.0: open failed: No such
- file or directory
+ ld.so.1: a.out: fatal: libpcre.so.0: open failed: No such file or
+ directory
- This is caused by the way shared library support works on
- those systems. You need to add
+ This is caused by the way shared library support works on those sys-
+ tems. You need to add
- -R/usr/local/lib
+ -R/usr/local/lib
- to the compile command to get round this problem.
+ to the compile command to get round this problem.
Last updated: 28 January 2003
Copyright (c) 1997-2003 University of Cambridge.
-----------------------------------------------------------------------------
*/
-/* Define DEBUG to get debugging output on stdout. */
+/* Define DEBUG to get debugging output on stdout. */
/* #define DEBUG */
/* Use a macro for debugging printing, 'cause that eliminates the use of #ifdef
#define DPRINTF(p) /*nothing*/
#endif
-/* Include the internals header, which itself includes Standard C headers plus
-the external pcre header. */
+/* Include the internals header, which itself includes "config.h", the Standard
+C headers, and the external pcre header. */
#include "internal.h"
/* Table of sizes for the fixed-length opcodes. It's defined in a macro so that
the definition is next to the definition of the opcodes in internal.h. */
-static uschar OP_lengths[] = { OP_LENGTHS };
+static const uschar OP_lengths[] = { OP_LENGTHS };
/* Min and max values for the common repeats; for the maxima, 0 => infinity */
on. Zero means further processing is needed (for things like \x), or the escape
is invalid. */
+#if !EBCDIC /* This is the "normal" table for ASCII systems */
static const short int escapes[] = {
0, 0, 0, 0, 0, 0, 0, 0, /* 0 - 7 */
0, 0, ':', ';', '<', '=', '>', '?', /* 8 - ? */
0, 0, -ESC_z /* x - z */
};
+#else /* This is the "abnormal" table for EBCDIC systems */
+static const short int escapes[] = {
+/* 48 */ 0, 0, 0, '.', '<', '(', '+', '|',
+/* 50 */ '&', 0, 0, 0, 0, 0, 0, 0,
+/* 58 */ 0, 0, '!', '$', '*', ')', ';', '~',
+/* 60 */ '-', '/', 0, 0, 0, 0, 0, 0,
+/* 68 */ 0, 0, '|', ',', '%', '_', '>', '?',
+/* 70 */ 0, 0, 0, 0, 0, 0, 0, 0,
+/* 78 */ 0, '`', ':', '#', '@', '\'', '=', '"',
+/* 80 */ 0, 7, -ESC_b, 0, -ESC_d, ESC_e, ESC_f, 0,
+/* 88 */ 0, 0, 0, '{', 0, 0, 0, 0,
+/* 90 */ 0, 0, 0, 'l', 0, ESC_n, 0, 0,
+/* 98 */ 0, ESC_r, 0, '}', 0, 0, 0, 0,
+/* A0 */ 0, '~', -ESC_s, ESC_tee, 0, 0, -ESC_w, 0,
+/* A8 */ 0,-ESC_z, 0, 0, 0, '[', 0, 0,
+/* B0 */ 0, 0, 0, 0, 0, 0, 0, 0,
+/* B8 */ 0, 0, 0, 0, 0, ']', '=', '-',
+/* C0 */ '{',-ESC_A, -ESC_B, -ESC_C, -ESC_D,-ESC_E, 0, -ESC_G,
+/* C8 */ 0, 0, 0, 0, 0, 0, 0, 0,
+/* D0 */ '}', 0, 0, 0, 0, 0, 0, 0,
+/* D8 */-ESC_Q, 0, 0, 0, 0, 0, 0, 0,
+/* E0 */ '\\', 0, -ESC_S, 0, 0, 0, -ESC_W, 0,
+/* E8 */ 0,-ESC_Z, 0, 0, 0, 0, 0, 0,
+/* F0 */ 0, 0, 0, 0, 0, 0, 0, 0,
+/* F8 */ 0, 0, 0, 0, 0, 0, 0, 0
+};
+#endif
+
+
/* Tables of names of POSIX character classes and their lengths. The list is
terminated by a zero length entry. The first three must be alpha, upper, lower,
as this is assumed for handling case independence. */
-static const char *posix_names[] = {
+static const char *const posix_names[] = {
"alpha", "lower", "upper",
"alnum", "ascii", "blank", "cntrl", "digit", "graph",
"print", "punct", "space", "word", "xdigit" };
cbit_xdigit,-1, -1 /* xdigit */
};
-/* Table to identify ASCII digits and hex digits. This is used when compiling
+/* Table to identify digits and hex digits. This is used when compiling
patterns. Note that the tables in chartables are dependent on the locale, and
may mark arbitrary characters as digits - but the PCRE compiling code expects
to handle only 0-9, a-z, and A-Z as digits when compiling. That is why we have
Then we can use ctype_digit and ctype_xdigit in the code. */
+#if !EBCDIC /* This is the "normal" case, for ASCII systems */
static const unsigned char digitab[] =
{
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 0- 7 */
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 240-247 */
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00};/* 248-255 */
+#else /* This is the "abnormal" case, for EBCDIC systems */
+static const unsigned char digitab[] =
+ {
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 0- 7 0 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 8- 15 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 16- 23 10 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 24- 31 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 32- 39 20 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 40- 47 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 48- 55 30 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 56- 63 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* - 71 40 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 72- | */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* & - 87 50 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 88- ¬ */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* - -103 60 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 104- ? */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 112-119 70 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 120- " */
+ 0x00,0x08,0x08,0x08,0x08,0x08,0x08,0x00, /* 128- g 80 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* h -143 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 144- p 90 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* q -159 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 160- x A0 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* y -175 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* ^ -183 B0 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 184-191 */
+ 0x00,0x08,0x08,0x08,0x08,0x08,0x08,0x00, /* { - G C0 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* H -207 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* } - P D0 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* Q -223 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* \ - X E0 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* Y -239 */
+ 0x0c,0x0c,0x0c,0x0c,0x0c,0x0c,0x0c,0x0c, /* 0 - 7 F0 */
+ 0x0c,0x0c,0x00,0x00,0x00,0x00,0x00,0x00};/* 8 -255 */
+
+static const unsigned char ebcdic_chartab[] = { /* chartable partial dup */
+ 0x80,0x00,0x00,0x00,0x00,0x01,0x00,0x00, /* 0- 7 */
+ 0x00,0x00,0x00,0x00,0x01,0x01,0x00,0x00, /* 8- 15 */
+ 0x00,0x00,0x00,0x00,0x00,0x01,0x00,0x00, /* 16- 23 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 24- 31 */
+ 0x00,0x00,0x00,0x00,0x00,0x01,0x00,0x00, /* 32- 39 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 40- 47 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 48- 55 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 56- 63 */
+ 0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* - 71 */
+ 0x00,0x00,0x00,0x80,0x00,0x80,0x80,0x80, /* 72- | */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* & - 87 */
+ 0x00,0x00,0x00,0x80,0x80,0x80,0x00,0x00, /* 88- ¬ */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* - -103 */
+ 0x00,0x00,0x00,0x00,0x00,0x10,0x00,0x80, /* 104- ? */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 112-119 */
+ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 120- " */
+ 0x00,0x1a,0x1a,0x1a,0x1a,0x1a,0x1a,0x12, /* 128- g */
+ 0x12,0x12,0x00,0x00,0x00,0x00,0x00,0x00, /* h -143 */
+ 0x00,0x12,0x12,0x12,0x12,0x12,0x12,0x12, /* 144- p */
+ 0x12,0x12,0x00,0x00,0x00,0x00,0x00,0x00, /* q -159 */
+ 0x00,0x00,0x12,0x12,0x12,0x12,0x12,0x12, /* 160- x */
+ 0x12,0x12,0x00,0x00,0x00,0x00,0x00,0x00, /* y -175 */
+ 0x80,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* ^ -183 */
+ 0x00,0x00,0x80,0x00,0x00,0x00,0x00,0x00, /* 184-191 */
+ 0x80,0x1a,0x1a,0x1a,0x1a,0x1a,0x1a,0x12, /* { - G */
+ 0x12,0x12,0x00,0x00,0x00,0x00,0x00,0x00, /* H -207 */
+ 0x00,0x12,0x12,0x12,0x12,0x12,0x12,0x12, /* } - P */
+ 0x12,0x12,0x00,0x00,0x00,0x00,0x00,0x00, /* Q -223 */
+ 0x00,0x00,0x12,0x12,0x12,0x12,0x12,0x12, /* \ - X */
+ 0x12,0x12,0x00,0x00,0x00,0x00,0x00,0x00, /* Y -239 */
+ 0x1c,0x1c,0x1c,0x1c,0x1c,0x1c,0x1c,0x1c, /* 0 - 7 */
+ 0x1c,0x1c,0x00,0x00,0x00,0x00,0x00,0x00};/* 8 -255 */
+#endif
+
+
/* Definition to allow mutual recursion */
static BOOL
/* Structure for building a chain of data that actually lives on the
stack, for holding the values of the subject pointer at the start of each
subpattern, so as to detect when an empty string has been matched by a
-subpattern - to break infinite loops. */
+subpattern - to break infinite loops. When NO_RECURSE is set, these blocks
+are on the heap, not on the stack. */
typedef struct eptrblock {
- struct eptrblock *prev;
- const uschar *saved_eptr;
+ struct eptrblock *epb_prev;
+ const uschar *epb_saved_eptr;
} eptrblock;
/* Flag bits for the match() function */
*************************************************/
/* PCRE is thread-clean and doesn't use any global variables in the normal
-sense. However, it calls memory allocation and free functions via the two
+sense. However, it calls memory allocation and free functions via the four
indirections below, and it can optionally do callouts. These values can be
changed by the caller, but are shared between all threads. However, when
compiling for Virtual Pascal, things are done differently (see pcre.in). */
#ifndef VPCOMPAT
+#ifdef __cplusplus
+extern "C" void *(*pcre_malloc)(size_t) = malloc;
+extern "C" void (*pcre_free)(void *) = free;
+extern "C" void *(*pcre_stack_malloc)(size_t) = malloc;
+extern "C" void (*pcre_stack_free)(void *) = free;
+extern "C" int (*pcre_callout)(pcre_callout_block *) = NULL;
+#else
void *(*pcre_malloc)(size_t) = malloc;
void (*pcre_free)(void *) = free;
+void *(*pcre_stack_malloc)(size_t) = malloc;
+void (*pcre_stack_free)(void *) = free;
int (*pcre_callout)(pcre_callout_block *) = NULL;
#endif
+#endif
/*************************************************
#define STRING(a) # a
#define XSTRING(s) STRING(s)
-const char *
+EXPORT const char *
pcre_version(void)
{
return XSTRING(PCRE_MAJOR) "." XSTRING(PCRE_MINOR) " " XSTRING(PCRE_DATE);
or negative values on error
*/
-int
+EXPORT int
pcre_info(const pcre *external_re, int *optptr, int *first_byte)
{
const real_pcre *re = (const real_pcre *)external_re;
Returns: 0 if data returned, negative on error
*/
-int
+EXPORT int
pcre_fullinfo(const pcre *external_re, const pcre_extra *extra_data, int what,
void *where)
{
if (re->magic_number != MAGIC_NUMBER) return PCRE_ERROR_BADMAGIC;
if (extra_data != NULL && (extra_data->flags & PCRE_EXTRA_STUDY_DATA) != 0)
- study = extra_data->study_data;
+ study = (const pcre_study_data *)extra_data->study_data;
switch (what)
{
Returns: 0 if data returned, negative on error
*/
-int
+EXPORT int
pcre_config(int what, void *where)
{
switch (what)
{
case PCRE_CONFIG_UTF8:
- #ifdef SUPPORT_UTF8
+#ifdef SUPPORT_UTF8
*((int *)where) = 1;
- #else
+#else
*((int *)where) = 0;
- #endif
+#endif
break;
case PCRE_CONFIG_NEWLINE:
*((unsigned int *)where) = MATCH_LIMIT;
break;
+ case PCRE_CONFIG_STACKRECURSE:
+#ifdef NO_RECURSE
+ *((int *)where) = 0;
+#else
+ *((int *)where) = 1;
+#endif
+ break;
+
default: return PCRE_ERROR_BADOPTION;
}
bracount number of previous extracting brackets
options the options bits
isclass TRUE if inside a character class
- cd pointer to char tables block
Returns: zero or positive => a data character
negative => a special escape sequence
static int
check_escape(const uschar **ptrptr, const char **errorptr, int bracount,
- int options, BOOL isclass, compile_data *cd)
+ int options, BOOL isclass)
{
const uschar *ptr = *ptrptr;
int c, i;
c = *(++ptr);
if (c == 0) *errorptr = ERR1;
-/* Digits or letters may have special meaning; all others are literals. */
-
-else if (c < '0' || c > 'z') {}
-
-/* Do an initial lookup in a table. A non-zero result is something that can be
-returned immediately. Otherwise further processing may be required. */
+/* Non-alphamerics are literals. For digits or letters, do an initial lookup in
+a table. A non-zero result is something that can be returned immediately.
+Otherwise further processing may be required. */
+#if !EBCDIC /* ASCII coding */
+else if (c < '0' || c > 'z') {} /* Not alphameric */
else if ((i = escapes[c - '0']) != 0) c = i;
+#else /* EBCDIC coding */
+else if (c < 'a' || (ebcdic_chartab[c] & 0x0E) == 0) {} /* Not alphameric */
+else if ((i = escapes[c - 0x48]) != 0) c = i;
+#endif
+
/* Escapes that need further processing, or are illegal. */
else
while ((digitab[*pt] & ctype_xdigit) != 0)
{
int cc = *pt++;
- if (cc >= 'a') cc -= 32; /* Convert to upper case */
count++;
+#if !EBCDIC /* ASCII coding */
+ if (cc >= 'a') cc -= 32; /* Convert to upper case */
c = c * 16 + cc - ((cc < 'A')? '0' : ('A' - 10));
+#else /* EBCDIC coding */
+ if (cc >= 'a' && cc <= 'z') cc += 64; /* Convert to upper case */
+ c = c * 16 + cc - ((cc >= '0')? '0' : ('A' - 10));
+#endif
}
if (*pt == '}')
{
c = 0;
while (i++ < 2 && (digitab[ptr[1]] & ctype_xdigit) != 0)
{
- int cc = *(++ptr);
+ int cc; /* Some compilers don't like ++ */
+ cc = *(++ptr); /* in initializers */
+#if !EBCDIC /* ASCII coding */
if (cc >= 'a') cc -= 32; /* Convert to upper case */
c = c * 16 + cc - ((cc < 'A')? '0' : ('A' - 10));
+#else /* EBCDIC coding */
+ if (cc <= 'z') cc += 64; /* Convert to upper case */
+ c = c * 16 + cc - ((cc >= '0')? '0' : ('A' - 10));
+#endif
}
break;
}
/* A letter is upper-cased; then the 0x40 bit is flipped. This coding
- is ASCII-specific, but then the whole concept of \cx is ASCII-specific. */
+ is ASCII-specific, but then the whole concept of \cx is ASCII-specific.
+ (However, an EBCDIC equivalent has now been added.) */
+#if !EBCDIC /* ASCII coding */
if (c >= 'a' && c <= 'z') c -= 32;
c ^= 0x40;
+#else /* EBCDIC coding */
+ if (c >= 'a' && c <= 'z') c += 64;
+ c ^= 0xC0;
+#endif
break;
/* PCRE_EXTRA enables extensions to Perl in the matter of escapes. Any
Arguments:
p pointer to the first char after '{'
- cd pointer to char tables block
Returns: TRUE or FALSE
*/
static BOOL
-is_counted_repeat(const uschar *p, compile_data *cd)
+is_counted_repeat(const uschar *p)
{
-if ((digitab[*p++] && ctype_digit) == 0) return FALSE;
+if ((digitab[*p++] & ctype_digit) == 0) return FALSE;
while ((digitab[*p] & ctype_digit) != 0) p++;
if (*p == '}') return TRUE;
if (*p++ != ',') return FALSE;
if (*p == '}') return TRUE;
-if ((digitab[*p++] && ctype_digit) == 0) return FALSE;
+if ((digitab[*p++] & ctype_digit) == 0) return FALSE;
while ((digitab[*p] & ctype_digit) != 0) p++;
return (*p == '}');
maxp pointer to int for max
returned as -1 if no max
errorptr points to pointer to error message
- cd pointer to character tables clock
Returns: pointer to '}' on success;
current ptr on error, with errorptr set
*/
static const uschar *
-read_repeat_counts(const uschar *p, int *minp, int *maxp,
- const char **errorptr, compile_data *cd)
+read_repeat_counts(const uschar *p, int *minp, int *maxp, const char **errorptr)
{
int min = 0;
int max = -1;
{
code += OP_lengths[c];
+#ifdef SUPPORT_UTF8
+
/* In UTF-8 mode, opcodes that are followed by a character may be followed
by a multi-byte character. The length in the table is a minimum, so we have
to scan along to skip the extra characters. All opcodes are less than 128,
so we can use relatively efficient code. */
+ if (utf8) switch(c)
+ {
+ case OP_EXACT:
+ case OP_UPTO:
+ case OP_MINUPTO:
+ case OP_STAR:
+ case OP_MINSTAR:
+ case OP_PLUS:
+ case OP_MINPLUS:
+ case OP_QUERY:
+ case OP_MINQUERY:
+ while ((*code & 0xc0) == 0x80) code++;
+ break;
+
+ /* XCLASS is used for classes that cannot be represented just by a bit
+ map. This includes negated single high-valued characters. The length in
+ the table is zero; the actual length is stored in the compled code. */
+
+ case OP_XCLASS:
+ code += GET(code, 1) + 1;
+ break;
+ }
+#endif
+ }
+ }
+}
+
+
+
+/*************************************************
+* Scan compiled regex for recursion reference *
+*************************************************/
+
+/* This little function scans through a compiled pattern until it finds an
+instance of OP_RECURSE.
+
+Arguments:
+ code points to start of expression
+ utf8 TRUE in UTF-8 mode
+
+Returns: pointer to the opcode for OP_RECURSE, or NULL if not found
+*/
+
+static const uschar *
+find_recurse(const uschar *code, BOOL utf8)
+{
+#ifndef SUPPORT_UTF8
+utf8 = utf8; /* Stop pedantic compilers complaining */
+#endif
+
+for (;;)
+ {
+ register int c = *code;
+ if (c == OP_END) return NULL;
+ else if (c == OP_RECURSE) return code;
+ else if (c == OP_CHARS) code += code[1] + OP_lengths[c];
+ else if (c > OP_BRA)
+ {
+ code += OP_lengths[OP_BRA];
+ }
+ else
+ {
+ code += OP_lengths[c];
+
#ifdef SUPPORT_UTF8
+
+ /* In UTF-8 mode, opcodes that are followed by a character may be followed
+ by a multi-byte character. The length in the table is a minimum, so we have
+ to scan along to skip the extra characters. All opcodes are less than 128,
+ so we can use relatively efficient code. */
+
if (utf8) switch(c)
{
case OP_EXACT:
case OP_MINQUERY:
while ((*code & 0xc0) == 0x80) code++;
break;
+
+ /* XCLASS is used for classes that cannot be represented just by a bit
+ map. This includes negated single high-valued characters. The length in
+ the table is zero; the actual length is stored in the compled code. */
+
+ case OP_XCLASS:
+ code += GET(code, 1) + 1;
+ break;
}
#endif
}
}
+/*************************************************
+* Adjust OP_RECURSE items in repeated group *
+*************************************************/
+
+/* OP_RECURSE items contain an offset from the start of the regex to the group
+that is referenced. This means that groups can be replicated for fixed
+repetition simply by copying (because the recursion is allowed to refer to
+earlier groups that are outside the current group). However, when a group is
+optional (i.e. the minimum quantifier is zero), OP_BRAZERO is inserted before
+it, after it has been compiled. This means that any OP_RECURSE items within it
+that refer to the group itself or any contained groups have to have their
+offsets adjusted. That is the job of this function. Before it is called, the
+partially compiled regex must be temporarily terminated with OP_END.
+
+Arguments:
+ group points to the start of the group
+ adjust the amount by which the group is to be moved
+ utf8 TRUE in UTF-8 mode
+ cd contains pointers to tables etc.
+
+Returns: nothing
+*/
+
+static void
+adjust_recurse(uschar *group, int adjust, BOOL utf8, compile_data *cd)
+{
+uschar *ptr = group;
+while ((ptr = (uschar *)find_recurse(ptr, utf8)) != NULL)
+ {
+ int offset = GET(ptr, 1);
+ if (cd->start_code + offset >= group) PUT(ptr, 1, offset + adjust);
+ ptr += 1 + LINK_SIZE;
+ }
+}
+
/*************************************************
posix_class *= 3;
for (i = 0; i < 3; i++)
{
- BOOL isblank = strncmp((char *)ptr, "blank", 5) == 0;
+ BOOL blankclass = strncmp((char *)ptr, "blank", 5) == 0;
int taboffset = posix_class_maps[posix_class + i];
if (taboffset < 0) break;
if (local_negate)
{
for (c = 0; c < 32; c++) class[c] |= ~cbits[c+taboffset];
- if (isblank) class[1] |= 0x3c;
+ if (blankclass) class[1] |= 0x3c;
}
else
{
for (c = 0; c < 32; c++) class[c] |= cbits[c+taboffset];
- if (isblank) class[1] &= ~0x3c;
+ if (blankclass) class[1] &= ~0x3c;
}
}
if (c == '\\')
{
- c = check_escape(&ptr, errorptr, *brackets, options, TRUE, cd);
+ c = check_escape(&ptr, errorptr, *brackets, options, TRUE);
if (-c == ESC_b) c = '\b'; /* \b is backslash in a class */
if (-c == ESC_Q) /* Handle start of quoted string */
if (d == '\\')
{
const uschar *oldptr = ptr;
- d = check_escape(&ptr, errorptr, *brackets, options, TRUE, cd);
+ d = check_escape(&ptr, errorptr, *brackets, options, TRUE);
/* \b is backslash; any other special means the '-' was literal */
/* Various kinds of repeat */
case '{':
- if (!is_counted_repeat(ptr+1, cd)) goto NORMAL_CHAR;
- ptr = read_repeat_counts(ptr+1, &repeat_min, &repeat_max, errorptr, cd);
+ if (!is_counted_repeat(ptr+1)) goto NORMAL_CHAR;
+ ptr = read_repeat_counts(ptr+1, &repeat_min, &repeat_max, errorptr);
if (*errorptr != NULL) goto FAILED;
goto REPEAT;
}
/* If the maximum is 1 or unlimited, we just have to stick in the
- BRAZERO and do no more at this point. */
+ BRAZERO and do no more at this point. However, we do need to adjust
+ any OP_RECURSE calls inside the group that refer to the group itself or
+ any internal group, because the offset is from the start of the whole
+ regex. Temporarily terminate the pattern while doing this. */
if (repeat_max <= 1)
{
+ *code = OP_END;
+ adjust_recurse(previous, 1, utf8, cd);
memmove(previous+1, previous, len);
code++;
*previous++ = OP_BRAZERO + repeat_type;
in a nested fashion, sticking OP_BRAZERO before each set of brackets.
The first one has to be handled carefully because it's the original
copy, which has to be moved up. The remainder can be handled by code
- that is common with the non-zero minimum case below. We just have to
- adjust the value or repeat_max, since one less copy is required. */
+ that is common with the non-zero minimum case below. We have to
+ adjust the value or repeat_max, since one less copy is required. Once
+ again, we may have to adjust any OP_RECURSE calls inside the group. */
else
{
int offset;
+ *code = OP_END;
+ adjust_recurse(previous, 2 + LINK_SIZE, utf8, cd);
memmove(previous + 2 + LINK_SIZE, previous, len);
code += 2 + LINK_SIZE;
*previous++ = OP_BRAZERO + repeat_type;
case '\\':
tempptr = ptr;
- c = check_escape(&ptr, errorptr, *brackets, options, FALSE, cd);
+ c = check_escape(&ptr, errorptr, *brackets, options, FALSE);
/* Handle metacharacters introduced by \. For ones like \d, the ESC_ values
are arranged to be the negation of the corresponding OP_values. For the
if (c == '\\')
{
tempptr = ptr;
- c = check_escape(&ptr, errorptr, *brackets, options, FALSE, cd);
+ c = check_escape(&ptr, errorptr, *brackets, options, FALSE);
if (c < 0) { ptr = tempptr; break; }
/* If a character is > 127 in UTF-8 mode, we have to turn it into
- two or more characters in the UTF-8 encoding. */
+ two or more bytes in the UTF-8 encoding. */
#ifdef SUPPORT_UTF8
if (utf8 && c > 127)
+#ifdef SUPPORT_UTF8
+/*************************************************
+* Validate a UTF-8 string *
+*************************************************/
+
+/* This function is called (optionally) at the start of compile or match, to
+validate that a supposed UTF-8 string is actually valid. The early check means
+that subsequent code can assume it is dealing with a valid string. The check
+can be turned off for maximum performance, but then consequences of supplying
+an invalid string are then undefined.
+
+Arguments:
+ string points to the string
+ length length of string, or -1 if the string is zero-terminated
+
+Returns: < 0 if the string is a valid UTF-8 string
+ >= 0 otherwise; the value is the offset of the bad byte
+*/
+
+static int
+valid_utf8(const uschar *string, int length)
+{
+register const uschar *p;
+
+if (length < 0)
+ {
+ for (p = string; *p != 0; p++);
+ length = p - string;
+ }
+
+for (p = string; length-- > 0; p++)
+ {
+ register int ab;
+ register int c = *p;
+ if (c < 128) continue;
+ if ((c & 0xc0) != 0xc0) return p - string;
+ ab = utf8_table4[c & 0x3f]; /* Number of additional bytes */
+ if (length < ab) return p - string;
+ length -= ab;
+
+ /* Check top bits in the second byte */
+ if ((*(++p) & 0xc0) != 0x80) return p - string;
+
+ /* Check for overlong sequences for each different length */
+ switch (ab)
+ {
+ /* Check for xx00 000x */
+ case 1:
+ if ((c & 0x3e) == 0) return p - string;
+ continue; /* We know there aren't any more bytes to check */
+
+ /* Check for 1110 0000, xx0x xxxx */
+ case 2:
+ if (c == 0xe0 && (*p & 0x20) == 0) return p - string;
+ break;
+
+ /* Check for 1111 0000, xx00 xxxx */
+ case 3:
+ if (c == 0xf0 && (*p & 0x30) == 0) return p - string;
+ break;
+
+ /* Check for 1111 1000, xx00 0xxx */
+ case 4:
+ if (c == 0xf8 && (*p & 0x38) == 0) return p - string;
+ break;
+
+ /* Check for leading 0xfe or 0xff, and then for 1111 1100, xx00 00xx */
+ case 5:
+ if (c == 0xfe || c == 0xff ||
+ (c == 0xfc && (*p & 0x3c) == 0)) return p - string;
+ break;
+ }
+
+ /* Check for valid bytes after the 2nd, if any; all must start 10 */
+ while (--ab > 0)
+ {
+ if ((*(++p) & 0xc0) != 0x80) return p - string;
+ }
+ }
+
+return -1;
+}
+#endif
+
+
+
/*************************************************
* Compile a Regular Expression *
*************************************************/
with errorptr and erroroffset set
*/
-pcre *
+EXPORT pcre *
pcre_compile(const char *pattern, int options, const char **errorptr,
int *erroroffset, const unsigned char *tables)
{
#ifdef SUPPORT_UTF8
utf8 = (options & PCRE_UTF8) != 0;
+if (utf8 && (options & PCRE_NO_UTF8_CHECK) == 0 &&
+ (*erroroffset = valid_utf8((uschar *)pattern, -1)) >= 0)
+ {
+ *errorptr = ERR44;
+ return NULL;
+ }
#else
if ((options & PCRE_UTF8) != 0)
{
case '\\':
{
const uschar *save_ptr = ptr;
- c = check_escape(&ptr, errorptr, bracount, options, FALSE, &compile_block);
+ c = check_escape(&ptr, errorptr, bracount, options, FALSE);
if (*errorptr != NULL) goto PCRE_ERROR_RETURN;
if (c >= 0)
{
if (refnum > compile_block.top_backref)
compile_block.top_backref = refnum;
length += 2; /* For single back reference */
- if (ptr[1] == '{' && is_counted_repeat(ptr+2, &compile_block))
+ if (ptr[1] == '{' && is_counted_repeat(ptr+2))
{
- ptr = read_repeat_counts(ptr+2, &min, &max, errorptr, &compile_block);
+ ptr = read_repeat_counts(ptr+2, &min, &max, errorptr);
if (*errorptr != NULL) goto PCRE_ERROR_RETURN;
if ((min == 0 && (max == 1 || max == -1)) ||
(min == 1 && max == -1))
class, or back reference. */
case '{':
- if (!is_counted_repeat(ptr+1, &compile_block)) goto NORMAL_CHAR;
- ptr = read_repeat_counts(ptr+1, &min, &max, errorptr, &compile_block);
+ if (!is_counted_repeat(ptr+1)) goto NORMAL_CHAR;
+ ptr = read_repeat_counts(ptr+1, &min, &max, errorptr);
if (*errorptr != NULL) goto PCRE_ERROR_RETURN;
/* These special cases just insert one extra opcode */
#ifdef SUPPORT_UTF8
int prevchar = ptr[-1];
#endif
- int ch = check_escape(&ptr, errorptr, bracount, options, TRUE,
- &compile_block);
+ int ch = check_escape(&ptr, errorptr, bracount, options, TRUE);
if (*errorptr != NULL) goto PCRE_ERROR_RETURN;
/* \b is backspace inside a class */
{
length += 33;
- /* A repeat needs either 1 or 5 bytes. */
+ /* A repeat needs either 1 or 5 bytes. If it is a possessive quantifier,
+ we also need extra for wrapping the whole thing in a sub-pattern. */
- if (*ptr != 0 && ptr[1] == '{' && is_counted_repeat(ptr+2, &compile_block))
+ if (*ptr != 0 && ptr[1] == '{' && is_counted_repeat(ptr+2))
{
- ptr = read_repeat_counts(ptr+2, &min, &max, errorptr, &compile_block);
+ ptr = read_repeat_counts(ptr+2, &min, &max, errorptr);
if (*errorptr != NULL) goto PCRE_ERROR_RETURN;
if ((min == 0 && (max == 1 || max == -1)) ||
(min == 1 && max == -1))
length++;
else length += 5;
- if (ptr[1] == '?') ptr++;
+ if (ptr[1] == '+')
+ {
+ ptr++;
+ length += 2 + 2*LINK_SIZE;
+ }
+ else if (ptr[1] == '?') ptr++;
}
}
continue;
/* Leave ptr at the final char; for read_repeat_counts this happens
automatically; for the others we need an increment. */
- if ((c = ptr[1]) == '{' && is_counted_repeat(ptr+2, &compile_block))
+ if ((c = ptr[1]) == '{' && is_counted_repeat(ptr+2))
{
- ptr = read_repeat_counts(ptr+2, &min, &max, errorptr, &compile_block);
+ ptr = read_repeat_counts(ptr+2, &min, &max, errorptr);
if (*errorptr != NULL) goto PCRE_ERROR_RETURN;
}
else if (c == '*') { min = 0; max = -1; ptr++; }
if (c == '\\')
{
const uschar *saveptr = ptr;
- c = check_escape(&ptr, errorptr, bracount, options, FALSE,
- &compile_block);
+ c = check_escape(&ptr, errorptr, bracount, options, FALSE);
if (*errorptr != NULL) goto PCRE_ERROR_RETURN;
if (c < 0) { ptr = saveptr; break; }
if ((re->options & PCRE_FIRSTSET) != 0)
{
int ch = re->first_byte & 255;
- char *caseless = ((re->first_byte & REQ_CASELESS) == 0)? "" : " (caseless)";
+ const char *caseless = ((re->first_byte & REQ_CASELESS) == 0)? "" : " (caseless)";
if (isprint(ch)) printf("First char = %c%s\n", ch, caseless);
else printf("First char = \\x%02x%s\n", ch, caseless);
}
if ((re->options & PCRE_REQCHSET) != 0)
{
int ch = re->req_byte & 255;
- char *caseless = ((re->req_byte & REQ_CASELESS) == 0)? "" : " (caseless)";
+ const char *caseless = ((re->req_byte & REQ_CASELESS) == 0)? "" : " (caseless)";
if (isprint(ch)) printf("Req char = %c%s\n", ch, caseless);
else printf("Req char = \\x%02x%s\n", ch, caseless);
}
#endif
+/***************************************************************************
+****************************************************************************
+ RECURSION IN THE match() FUNCTION
+
+The match() function is highly recursive. Some regular expressions can cause
+it to recurse thousands of times. I was writing for Unix, so I just let it
+call itself recursively. This uses the stack for saving everything that has
+to be saved for a recursive call. On Unix, the stack can be large, and this
+works fine.
+
+It turns out that on non-Unix systems there are problems with programs that
+use a lot of stack. (This despite the fact that every last chip has oodles
+of memory these days, and techniques for extending the stack have been known
+for decades.) So....
+
+There is a fudge, triggered by defining NO_RECURSE, which avoids recursive
+calls by keeping local variables that need to be preserved in blocks of memory
+obtained from malloc instead instead of on the stack. Macros are used to
+achieve this so that the actual code doesn't look very different to what it
+always used to.
+****************************************************************************
+***************************************************************************/
+
+
+/* These versions of the macros use the stack, as normal */
+
+#ifndef NO_RECURSE
+#define REGISTER register
+#define RMATCH(rx,ra,rb,rc,rd,re,rf,rg) rx = match(ra,rb,rc,rd,re,rf,rg)
+#define RRETURN(ra) return ra
+#else
+
+
+/* These versions of the macros manage a private stack on the heap. Note
+that the rd argument of RMATCH isn't actually used. It's the md argument of
+match(), which never actually changes. */
+
+#define REGISTER
+
+#define RMATCH(rx,ra,rb,rc,rd,re,rf,rg)\
+ {\
+ heapframe *newframe = (pcre_stack_malloc)(sizeof(heapframe));\
+ if (setjmp(frame->Xwhere) == 0)\
+ {\
+ newframe->Xeptr = ra;\
+ newframe->Xecode = rb;\
+ newframe->Xoffset_top = rc;\
+ newframe->Xims = re;\
+ newframe->Xeptrb = rf;\
+ newframe->Xflags = rg;\
+ newframe->Xprevframe = frame;\
+ frame = newframe;\
+ DPRINTF(("restarting from line %d\n", __LINE__));\
+ goto HEAP_RECURSE;\
+ }\
+ else\
+ {\
+ DPRINTF(("longjumped back to line %d\n", __LINE__));\
+ frame = md->thisframe;\
+ rx = frame->Xresult;\
+ }\
+ }
+
+#define RRETURN(ra)\
+ {\
+ heapframe *newframe = frame;\
+ frame = newframe->Xprevframe;\
+ (pcre_stack_free)(newframe);\
+ if (frame != NULL)\
+ {\
+ frame->Xresult = ra;\
+ md->thisframe = frame;\
+ longjmp(frame->Xwhere, 1);\
+ }\
+ return ra;\
+ }
+
+
+/* Structure for remembering the local variables in a private frame */
+
+typedef struct heapframe {
+ struct heapframe *Xprevframe;
+
+ /* Function arguments that may change */
+
+ const uschar *Xeptr;
+ const uschar *Xecode;
+ int Xoffset_top;
+ long int Xims;
+ eptrblock *Xeptrb;
+ int Xflags;
+
+ /* Function local variables */
+
+ const uschar *Xcallpat;
+ const uschar *Xcharptr;
+ const uschar *Xdata;
+ const uschar *Xlastptr;
+ const uschar *Xnext;
+ const uschar *Xpp;
+ const uschar *Xprev;
+ const uschar *Xsaved_eptr;
+
+ recursion_info Xnew_recursive;
+
+ BOOL Xcur_is_word;
+ BOOL Xcondition;
+ BOOL Xminimize;
+ BOOL Xprev_is_word;
+
+ unsigned long int Xoriginal_ims;
+
+ int Xctype;
+ int Xfc;
+ int Xfi;
+ int Xlength;
+ int Xmax;
+ int Xmin;
+ int Xnumber;
+ int Xoffset;
+ int Xop;
+ int Xsave_capture_last;
+ int Xsave_offset1, Xsave_offset2, Xsave_offset3;
+ int Xstacksave[REC_STACK_SAVE_MAX];
+
+ eptrblock Xnewptrb;
+
+ /* Place to pass back result, and where to jump back to */
+
+ int Xresult;
+ jmp_buf Xwhere;
+
+} heapframe;
+
+#endif
+
+
+/***************************************************************************
+***************************************************************************/
+
/*************************************************
*/
static int
-match(register const uschar *eptr, register const uschar *ecode,
+match(REGISTER const uschar *eptr, REGISTER const uschar *ecode,
int offset_top, match_data *md, unsigned long int ims, eptrblock *eptrb,
int flags)
{
-unsigned long int original_ims = ims; /* Save for resetting on ')' */
-register int rrc;
+/* These variables do not need to be preserved over recursion in this function,
+so they can be ordinary variables in all cases. Mark them with "register"
+because they are used a lot in loops. */
+
+register int rrc; /* Returns from recursive calls */
+register int i; /* Used for loops not involving calls to RMATCH() */
+register int c; /* Character values not kept over RMATCH() calls */
+
+/* When recursion is not being used, all "local" variables that have to be
+preserved over calls to RMATCH() are part of a "frame" which is obtained from
+heap storage. Set up the top-level frame here; others are obtained from the
+heap whenever RMATCH() does a "recursion". See the macro definitions above. */
+
+#ifdef NO_RECURSE
+heapframe *frame = (pcre_stack_malloc)(sizeof(heapframe));
+frame->Xprevframe = NULL; /* Marks the top level */
+
+/* Copy in the original argument variables */
+
+frame->Xeptr = eptr;
+frame->Xecode = ecode;
+frame->Xoffset_top = offset_top;
+frame->Xims = ims;
+frame->Xeptrb = eptrb;
+frame->Xflags = flags;
+
+/* This is where control jumps back to to effect "recursion" */
+
+HEAP_RECURSE:
+
+/* Macros make the argument variables come from the current frame */
+
+#define eptr frame->Xeptr
+#define ecode frame->Xecode
+#define offset_top frame->Xoffset_top
+#define ims frame->Xims
+#define eptrb frame->Xeptrb
+#define flags frame->Xflags
+
+/* Ditto for the local variables */
+
+#define callpat frame->Xcallpat
+#define charptr frame->Xcharptr
+#define data frame->Xdata
+#define lastptr frame->Xlastptr
+#define next frame->Xnext
+#define pp frame->Xpp
+#define prev frame->Xprev
+#define saved_eptr frame->Xsaved_eptr
+
+#define new_recursive frame->Xnew_recursive
+
+#define cur_is_word frame->Xcur_is_word
+#define condition frame->Xcondition
+#define minimize frame->Xminimize
+#define prev_is_word frame->Xprev_is_word
+
+#define original_ims frame->Xoriginal_ims
+
+#define ctype frame->Xctype
+#define fc frame->Xfc
+#define fi frame->Xfi
+#define length frame->Xlength
+#define max frame->Xmax
+#define min frame->Xmin
+#define number frame->Xnumber
+#define offset frame->Xoffset
+#define op frame->Xop
+#define save_capture_last frame->Xsave_capture_last
+#define save_offset1 frame->Xsave_offset1
+#define save_offset2 frame->Xsave_offset2
+#define save_offset3 frame->Xsave_offset3
+#define stacksave frame->Xstacksave
+
+#define newptrb frame->Xnewptrb
+
+/* When recursion is being used, local variables are allocated on the stack and
+get preserved during recursion in the normal way. In this environment, fi and
+i, and fc and c, can be the same variables. */
+
+#else
+#define fi i
+#define fc c
+
+const uschar *callpat; /* Many of these variables are used ony */
+const uschar *charptr; /* small blocks of the code. My normal */
+const uschar *data; /* style of coding would have declared */
+const uschar *lastptr; /* them within each of those blocks. */
+const uschar *next; /* However, in order to accommodate the */
+const uschar *pp; /* version of this code that uses an */
+const uschar *prev; /* external "stack" implemented on the */
+const uschar *saved_eptr; /* heap, it is easier to declare them */
+ /* all here, so the declarations can */
+recursion_info new_recursive; /* be cut out in a block. The only */
+ /* declarations within blocks below are */
+BOOL cur_is_word; /* for variables that do not have to */
+BOOL condition; /* be preserved over a recursive call */
+BOOL minimize; /* to RMATCH(). */
+BOOL prev_is_word;
+
+unsigned long int original_ims;
+
+int ctype;
+int length;
+int max;
+int min;
+int number;
+int offset;
+int op;
+int save_capture_last;
+int save_offset1, save_offset2, save_offset3;
+int stacksave[REC_STACK_SAVE_MAX];
+
eptrblock newptrb;
+#endif
+
-if (md->match_call_count++ >= md->match_limit) return PCRE_ERROR_MATCHLIMIT;
+/* OK, now we can get on with the real code of the function. Recursion is
+specified by the macros RMATCH and RRETURN. When NO_RECURSE is *not* defined,
+these just turn into a recursive call to match() and a "return", respectively.
+However, RMATCH isn't like a function call because it's quite a complicated
+macro. It has to be used in one particular way. This shouldn't, however, impact
+performance when true recursion is being used. */
+
+if (md->match_call_count++ >= md->match_limit) RRETURN(PCRE_ERROR_MATCHLIMIT);
+
+original_ims = ims; /* Save for resetting on ')' */
/* At the start of a bracketed group, add the current subject pointer to the
stack of such pointers, to be re-instated at the end of the group when we hit
the closing ket. When match() is called in other circumstances, we don't add to
-the stack. */
+this stack. */
if ((flags & match_isgroup) != 0)
{
- newptrb.prev = eptrb;
- newptrb.saved_eptr = eptr;
+ newptrb.epb_prev = eptrb;
+ newptrb.epb_saved_eptr = eptr;
eptrb = &newptrb;
}
for (;;)
{
- int op = (int)*ecode;
- int min, max, ctype;
- register int i;
- register int c;
- BOOL minimize = FALSE;
+ op = *ecode;
+ minimize = FALSE;
/* Opening capturing bracket. If there is space in the offset vector, save
the current subject position in the working slot at the top of the vector. We
if (op > OP_BRA)
{
- int offset;
- int number = op - OP_BRA;
+ number = op - OP_BRA;
/* For extended extraction brackets (large number), we have to fish out the
number from a dummy opcode at the start. */
if (offset < md->offset_max)
{
- int save_offset1 = md->offset_vector[offset];
- int save_offset2 = md->offset_vector[offset+1];
- int save_offset3 = md->offset_vector[md->offset_end - number];
- int save_capture_last = md->capture_last;
+ save_offset1 = md->offset_vector[offset];
+ save_offset2 = md->offset_vector[offset+1];
+ save_offset3 = md->offset_vector[md->offset_end - number];
+ save_capture_last = md->capture_last;
DPRINTF(("saving %d %d %d\n", save_offset1, save_offset2, save_offset3));
md->offset_vector[md->offset_end - number] = eptr - md->start_subject;
do
{
- if ((rrc = match(eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims,
- eptrb, match_isgroup)) != MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, eptrb,
+ match_isgroup);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
md->capture_last = save_capture_last;
ecode += GET(ecode, 1);
}
md->offset_vector[offset+1] = save_offset2;
md->offset_vector[md->offset_end - number] = save_offset3;
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
}
/* Insufficient room for saving captured contents */
DPRINTF(("start bracket 0\n"));
do
{
- if ((rrc = match(eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, eptrb,
- match_isgroup)) != MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, eptrb,
+ match_isgroup);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
ecode += GET(ecode, 1);
}
while (*ecode == OP_ALT);
DPRINTF(("bracket 0 failed\n"));
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
/* Conditional group: compilation checked that there are no more than
two branches. If the condition is false, skipping the first branch takes us
case OP_COND:
if (ecode[LINK_SIZE+1] == OP_CREF) /* Condition extract or recurse test */
{
- int offset = GET2(ecode, LINK_SIZE+2) << 1; /* Doubled ref number */
- BOOL condition = (offset == CREF_RECURSE * 2)?
+ offset = GET2(ecode, LINK_SIZE+2) << 1; /* Doubled ref number */
+ condition = (offset == CREF_RECURSE * 2)?
(md->recursive != NULL) :
(offset < offset_top && md->offset_vector[offset] >= 0);
- return match(eptr, ecode + (condition?
+ RMATCH(rrc, eptr, ecode + (condition?
(LINK_SIZE + 4) : (LINK_SIZE + 1 + GET(ecode, 1))),
offset_top, md, ims, eptrb, match_isgroup);
+ RRETURN(rrc);
}
/* The condition is an assertion. Call match() to evaluate it - setting
else
{
- if ((rrc = match(eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, NULL,
- match_condassert | match_isgroup)) == MATCH_MATCH)
+ RMATCH(rrc, eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, NULL,
+ match_condassert | match_isgroup);
+ if (rrc == MATCH_MATCH)
{
ecode += 1 + LINK_SIZE + GET(ecode, LINK_SIZE+2);
while (*ecode == OP_ALT) ecode += GET(ecode, 1);
}
- else if (rrc != MATCH_NOMATCH) return rrc;
+ else if (rrc != MATCH_NOMATCH)
+ {
+ RRETURN(rrc); /* Need braces because of following else */
+ }
else ecode += GET(ecode, 1);
- return match(eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, eptrb,
+ RMATCH(rrc, eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, eptrb,
match_isgroup);
+ RRETURN(rrc);
}
/* Control never reaches here */
{
recursion_info *rec = md->recursive;
DPRINTF(("Hit the end in a (?0) recursion\n"));
- md->recursive = rec->prev;
+ md->recursive = rec->prevrec;
memmove(md->offset_vector, rec->offset_save,
rec->saved_max * sizeof(int));
md->start_match = rec->save_start;
/* Otherwise, if PCRE_NOTEMPTY is set, fail if we have matched an empty
string - backtracking will then try other alternatives, if any. */
- if (md->notempty && eptr == md->start_match) return MATCH_NOMATCH;
+ if (md->notempty && eptr == md->start_match) RRETURN(MATCH_NOMATCH);
md->end_match_ptr = eptr; /* Record where we ended */
md->end_offset_top = offset_top; /* and how many extracts were taken */
- return MATCH_MATCH;
+ RRETURN(MATCH_MATCH);
/* Change option settings */
case OP_ASSERTBACK:
do
{
- if ((rrc = match(eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, NULL,
- match_isgroup)) == MATCH_MATCH) break;
- if (rrc != MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, NULL,
+ match_isgroup);
+ if (rrc == MATCH_MATCH) break;
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
ecode += GET(ecode, 1);
}
while (*ecode == OP_ALT);
- if (*ecode == OP_KET) return MATCH_NOMATCH;
+ if (*ecode == OP_KET) RRETURN(MATCH_NOMATCH);
/* If checking an assertion for a condition, return MATCH_MATCH. */
- if ((flags & match_condassert) != 0) return MATCH_MATCH;
+ if ((flags & match_condassert) != 0) RRETURN(MATCH_MATCH);
/* Continue from after the assertion, updating the offsets high water
mark, since extracts may have been taken during the assertion. */
case OP_ASSERTBACK_NOT:
do
{
- if ((rrc = match(eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, NULL,
- match_isgroup)) == MATCH_MATCH) return MATCH_NOMATCH;
- if (rrc != MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, NULL,
+ match_isgroup);
+ if (rrc == MATCH_MATCH) RRETURN(MATCH_NOMATCH);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
ecode += GET(ecode,1);
}
while (*ecode == OP_ALT);
- if ((flags & match_condassert) != 0) return MATCH_MATCH;
+ if ((flags & match_condassert) != 0) RRETURN(MATCH_MATCH);
ecode += 1 + LINK_SIZE;
continue;
for (i = 0; i < c; i++)
{
eptr--;
- if (eptr < md->start_subject) return MATCH_NOMATCH;
+ if (eptr < md->start_subject) RRETURN(MATCH_NOMATCH);
BACKCHAR(eptr)
}
}
{
eptr -= GET(ecode,1);
- if (eptr < md->start_subject) return MATCH_NOMATCH;
+ if (eptr < md->start_subject) RRETURN(MATCH_NOMATCH);
}
/* Skip to next op code */
cb.capture_top = offset_top/2;
cb.capture_last = md->capture_last;
cb.callout_data = md->callout_data;
- if ((rrc = (*pcre_callout)(&cb)) > 0) return MATCH_NOMATCH;
- if (rrc < 0) return rrc;
+ if ((rrc = (*pcre_callout)(&cb)) > 0) RRETURN(MATCH_NOMATCH);
+ if (rrc < 0) RRETURN(rrc);
}
ecode += 2;
break;
/* Recursion either matches the current regex, or some subexpression. The
offset data is the offset to the starting bracket from the start of the
- whole pattern. However, it is possible that a BRAZERO was inserted before
- this bracket after we took the offset - we just skip it if encountered.
+ whole pattern. (This is so that it works from duplicated subpatterns.)
If there are any capturing brackets started but not finished, we have to
save their starting points and reinstate them after the recursion. However,
case OP_RECURSE:
{
- int stacksave[REC_STACK_SAVE_MAX];
- recursion_info new_recursive;
- const uschar *callpat = md->start_code + GET(ecode, 1);
-
- if (*callpat == OP_BRAZERO) callpat++;
-
+ callpat = md->start_code + GET(ecode, 1);
new_recursive.group_num = *callpat - OP_BRA;
/* For extended extraction brackets (large number), we have to fish out
/* Add to "recursing stack" */
- new_recursive.prev = md->recursive;
+ new_recursive.prevrec = md->recursive;
md->recursive = &new_recursive;
/* Find where to continue from afterwards */
{
new_recursive.offset_save =
(int *)(pcre_malloc)(new_recursive.saved_max * sizeof(int));
- if (new_recursive.offset_save == NULL) return PCRE_ERROR_NOMEMORY;
+ if (new_recursive.offset_save == NULL) RRETURN(PCRE_ERROR_NOMEMORY);
}
memcpy(new_recursive.offset_save, md->offset_vector,
DPRINTF(("Recursing into group %d\n", new_recursive.group_num));
do
{
- if ((rrc = match(eptr, callpat + 1 + LINK_SIZE, offset_top, md, ims,
- eptrb, match_isgroup)) == MATCH_MATCH)
+ RMATCH(rrc, eptr, callpat + 1 + LINK_SIZE, offset_top, md, ims,
+ eptrb, match_isgroup);
+ if (rrc == MATCH_MATCH)
{
- md->recursive = new_recursive.prev;
+ md->recursive = new_recursive.prevrec;
if (new_recursive.offset_save != stacksave)
(pcre_free)(new_recursive.offset_save);
- return MATCH_MATCH;
+ RRETURN(MATCH_MATCH);
}
- else if (rrc != MATCH_NOMATCH) return rrc;
+ else if (rrc != MATCH_NOMATCH) RRETURN(rrc);
md->recursive = &new_recursive;
memcpy(md->offset_vector, new_recursive.offset_save,
while (*callpat == OP_ALT);
DPRINTF(("Recursion didn't match\n"));
- md->recursive = new_recursive.prev;
+ md->recursive = new_recursive.prevrec;
if (new_recursive.offset_save != stacksave)
(pcre_free)(new_recursive.offset_save);
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
}
/* Control never reaches here */
case OP_ONCE:
{
- const uschar *prev = ecode;
- const uschar *saved_eptr = eptr;
+ prev = ecode;
+ saved_eptr = eptr;
do
{
- if ((rrc = match(eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims,
- eptrb, match_isgroup)) == MATCH_MATCH) break;
- if (rrc != MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims,
+ eptrb, match_isgroup);
+ if (rrc == MATCH_MATCH) break;
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
ecode += GET(ecode,1);
}
while (*ecode == OP_ALT);
/* If hit the end of the group (which could be repeated), fail */
- if (*ecode != OP_ONCE && *ecode != OP_ALT) return MATCH_NOMATCH;
+ if (*ecode != OP_ONCE && *ecode != OP_ALT) RRETURN(MATCH_NOMATCH);
/* Continue as from after the assertion, updating the offsets high water
mark, since extracts may have been taken. */
if (*ecode == OP_KETRMIN)
{
- if ((rrc = match(eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims,
- eptrb, 0)) != MATCH_NOMATCH) return rrc;
- if ((rrc = match(eptr, prev, offset_top, md, ims, eptrb,
- match_isgroup)) != MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ RMATCH(rrc, eptr, prev, offset_top, md, ims, eptrb, match_isgroup);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
}
else /* OP_KETRMAX */
{
- if ((rrc = match(eptr, prev, offset_top, md, ims, eptrb,
- match_isgroup)) != MATCH_NOMATCH) return rrc;
- if ((rrc = match(eptr, ecode + 1+LINK_SIZE, offset_top, md, ims, eptrb,
- 0)) != MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, prev, offset_top, md, ims, eptrb, match_isgroup);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ RMATCH(rrc, eptr, ecode + 1+LINK_SIZE, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
}
}
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
/* An alternation is the end of a branch; scan along to find the end of the
bracketed group and go to there. */
case OP_BRAZERO:
{
- const uschar *next = ecode+1;
- if ((rrc = match(eptr, next, offset_top, md, ims, eptrb, match_isgroup))
- != MATCH_NOMATCH) return rrc;
+ next = ecode+1;
+ RMATCH(rrc, eptr, next, offset_top, md, ims, eptrb, match_isgroup);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
do next += GET(next,1); while (*next == OP_ALT);
ecode = next + 1+LINK_SIZE;
}
case OP_BRAMINZERO:
{
- const uschar *next = ecode+1;
+ next = ecode+1;
do next += GET(next,1); while (*next == OP_ALT);
- if ((rrc = match(eptr, next + 1+LINK_SIZE, offset_top, md, ims, eptrb,
- match_isgroup)) != MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, next + 1+LINK_SIZE, offset_top, md, ims, eptrb,
+ match_isgroup);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
ecode++;
}
break;
case OP_KETRMIN:
case OP_KETRMAX:
{
- const uschar *prev = ecode - GET(ecode, 1);
- const uschar *saved_eptr = eptrb->saved_eptr;
+ prev = ecode - GET(ecode, 1);
+ saved_eptr = eptrb->epb_saved_eptr;
- eptrb = eptrb->prev; /* Back up the stack of bracket start pointers */
+ /* Back up the stack of bracket start pointers. */
+
+ eptrb = eptrb->epb_prev;
if (*prev == OP_ASSERT || *prev == OP_ASSERT_NOT ||
*prev == OP_ASSERTBACK || *prev == OP_ASSERTBACK_NOT ||
{
md->end_match_ptr = eptr; /* For ONCE */
md->end_offset_top = offset_top;
- return MATCH_MATCH;
+ RRETURN(MATCH_MATCH);
}
/* In all other cases except a conditional group we have to check the
if (*prev != OP_COND)
{
- int offset;
- int number = *prev - OP_BRA;
+ number = *prev - OP_BRA;
/* For extended extraction brackets (large number), we have to fish out
the number from a dummy opcode at the start. */
{
recursion_info *rec = md->recursive;
DPRINTF(("Recursion (%d) succeeded - continuing\n", number));
- md->recursive = rec->prev;
+ md->recursive = rec->prevrec;
md->start_match = rec->save_start;
memcpy(md->offset_vector, rec->offset_save,
rec->saved_max * sizeof(int));
if (*ecode == OP_KETRMIN)
{
- if ((rrc = match(eptr, ecode + 1+LINK_SIZE, offset_top, md, ims, eptrb,
- 0)) != MATCH_NOMATCH) return rrc;
- if ((rrc = match(eptr, prev, offset_top, md, ims, eptrb,
- match_isgroup)) != MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode + 1+LINK_SIZE, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ RMATCH(rrc, eptr, prev, offset_top, md, ims, eptrb, match_isgroup);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
}
else /* OP_KETRMAX */
{
- if ((rrc = match(eptr, prev, offset_top, md, ims, eptrb,
- match_isgroup)) != MATCH_NOMATCH) return rrc;
- if ((rrc = match(eptr, ecode + 1+LINK_SIZE, offset_top, md, ims, eptrb,
- 0)) != MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, prev, offset_top, md, ims, eptrb, match_isgroup);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ RMATCH(rrc, eptr, ecode + 1+LINK_SIZE, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
}
}
- return MATCH_NOMATCH;
+
+ RRETURN(MATCH_NOMATCH);
/* Start of subject unless notbol, or after internal newline if multiline */
case OP_CIRC:
- if (md->notbol && eptr == md->start_subject) return MATCH_NOMATCH;
+ if (md->notbol && eptr == md->start_subject) RRETURN(MATCH_NOMATCH);
if ((ims & PCRE_MULTILINE) != 0)
{
if (eptr != md->start_subject && eptr[-1] != NEWLINE)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
ecode++;
break;
}
/* Start of subject assertion */
case OP_SOD:
- if (eptr != md->start_subject) return MATCH_NOMATCH;
+ if (eptr != md->start_subject) RRETURN(MATCH_NOMATCH);
ecode++;
break;
/* Start of match assertion */
case OP_SOM:
- if (eptr != md->start_subject + md->start_offset) return MATCH_NOMATCH;
+ if (eptr != md->start_subject + md->start_offset) RRETURN(MATCH_NOMATCH);
ecode++;
break;
if ((ims & PCRE_MULTILINE) != 0)
{
if (eptr < md->end_subject)
- { if (*eptr != NEWLINE) return MATCH_NOMATCH; }
+ { if (*eptr != NEWLINE) RRETURN(MATCH_NOMATCH); }
else
- { if (md->noteol) return MATCH_NOMATCH; }
+ { if (md->noteol) RRETURN(MATCH_NOMATCH); }
ecode++;
break;
}
else
{
- if (md->noteol) return MATCH_NOMATCH;
+ if (md->noteol) RRETURN(MATCH_NOMATCH);
if (!md->endonly)
{
if (eptr < md->end_subject - 1 ||
(eptr == md->end_subject - 1 && *eptr != NEWLINE))
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
ecode++;
break;
}
/* End of subject assertion (\z) */
case OP_EOD:
- if (eptr < md->end_subject) return MATCH_NOMATCH;
+ if (eptr < md->end_subject) RRETURN(MATCH_NOMATCH);
ecode++;
break;
case OP_EODN:
if (eptr < md->end_subject - 1 ||
- (eptr == md->end_subject - 1 && *eptr != NEWLINE)) return MATCH_NOMATCH;
+ (eptr == md->end_subject - 1 && *eptr != NEWLINE)) RRETURN(MATCH_NOMATCH);
ecode++;
break;
case OP_NOT_WORD_BOUNDARY:
case OP_WORD_BOUNDARY:
{
- BOOL prev_is_word, cur_is_word;
/* Find out if the previous and current characters are "word" characters.
It takes a bit more work in UTF-8 mode. Characters > 255 are assumed to
{
if (eptr == md->start_subject) prev_is_word = FALSE; else
{
- const uschar *lastptr = eptr - 1;
+ lastptr = eptr - 1;
while((*lastptr & 0xc0) == 0x80) lastptr--;
GETCHAR(c, lastptr);
prev_is_word = c < 256 && (md->ctypes[c] & ctype_word) != 0;
if ((*ecode++ == OP_WORD_BOUNDARY)?
cur_is_word == prev_is_word : cur_is_word != prev_is_word)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
}
break;
case OP_ANY:
if ((ims & PCRE_DOTALL) == 0 && eptr < md->end_subject && *eptr == NEWLINE)
- return MATCH_NOMATCH;
- if (eptr++ >= md->end_subject) return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
+ if (eptr++ >= md->end_subject) RRETURN(MATCH_NOMATCH);
#ifdef SUPPORT_UTF8
if (md->utf8)
while (eptr < md->end_subject && (*eptr & 0xc0) == 0x80) eptr++;
any byte, even newline, independent of the setting of PCRE_DOTALL. */
case OP_ANYBYTE:
- if (eptr++ >= md->end_subject) return MATCH_NOMATCH;
+ if (eptr++ >= md->end_subject) RRETURN(MATCH_NOMATCH);
ecode++;
break;
case OP_NOT_DIGIT:
- if (eptr >= md->end_subject) return MATCH_NOMATCH;
+ if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
GETCHARINCTEST(c, eptr);
if (
#ifdef SUPPORT_UTF8
#endif
(md->ctypes[c] & ctype_digit) != 0
)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
ecode++;
break;
case OP_DIGIT:
- if (eptr >= md->end_subject) return MATCH_NOMATCH;
+ if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
GETCHARINCTEST(c, eptr);
if (
#ifdef SUPPORT_UTF8
#endif
(md->ctypes[c] & ctype_digit) == 0
)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
ecode++;
break;
case OP_NOT_WHITESPACE:
- if (eptr >= md->end_subject) return MATCH_NOMATCH;
+ if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
GETCHARINCTEST(c, eptr);
if (
#ifdef SUPPORT_UTF8
#endif
(md->ctypes[c] & ctype_space) != 0
)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
ecode++;
break;
case OP_WHITESPACE:
- if (eptr >= md->end_subject) return MATCH_NOMATCH;
+ if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
GETCHARINCTEST(c, eptr);
if (
#ifdef SUPPORT_UTF8
#endif
(md->ctypes[c] & ctype_space) == 0
)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
ecode++;
break;
case OP_NOT_WORDCHAR:
- if (eptr >= md->end_subject) return MATCH_NOMATCH;
+ if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
GETCHARINCTEST(c, eptr);
if (
#ifdef SUPPORT_UTF8
#endif
(md->ctypes[c] & ctype_word) != 0
)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
ecode++;
break;
case OP_WORDCHAR:
- if (eptr >= md->end_subject) return MATCH_NOMATCH;
+ if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
GETCHARINCTEST(c, eptr);
if (
#ifdef SUPPORT_UTF8
#endif
(md->ctypes[c] & ctype_word) == 0
)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
ecode++;
break;
case OP_REF:
{
- int length;
- int offset = GET2(ecode, 1) << 1; /* Doubled ref number */
+ offset = GET2(ecode, 1) << 1; /* Doubled ref number */
ecode += 3; /* Advance past item */
/* If the reference is unset, set the length to be longer than the amount
break;
default: /* No repeat follows */
- if (!match_ref(offset, eptr, length, md, ims)) return MATCH_NOMATCH;
+ if (!match_ref(offset, eptr, length, md, ims)) RRETURN(MATCH_NOMATCH);
eptr += length;
continue; /* With the main loop */
}
for (i = 1; i <= min; i++)
{
- if (!match_ref(offset, eptr, length, md, ims)) return MATCH_NOMATCH;
+ if (!match_ref(offset, eptr, length, md, ims)) RRETURN(MATCH_NOMATCH);
eptr += length;
}
if (minimize)
{
- for (i = min;; i++)
+ for (fi = min;; fi++)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
- if (i >= max || !match_ref(offset, eptr, length, md, ims))
- return MATCH_NOMATCH;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ if (fi >= max || !match_ref(offset, eptr, length, md, ims))
+ RRETURN(MATCH_NOMATCH);
eptr += length;
}
/* Control never gets here */
else
{
- const uschar *pp = eptr;
+ pp = eptr;
for (i = min; i < max; i++)
{
if (!match_ref(offset, eptr, length, md, ims)) break;
}
while (eptr >= pp)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
eptr -= length;
}
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
}
}
/* Control never gets here */
case OP_NCLASS:
case OP_CLASS:
{
- const uschar *data = ecode + 1; /* Save for matching */
+ data = ecode + 1; /* Save for matching */
ecode += 33; /* Advance past the item */
switch (*ecode)
{
for (i = 1; i <= min; i++)
{
- if (eptr >= md->end_subject) return MATCH_NOMATCH;
+ if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
GETCHARINC(c, eptr);
if (c > 255)
{
- if (op == OP_CLASS) return MATCH_NOMATCH;
+ if (op == OP_CLASS) RRETURN(MATCH_NOMATCH);
}
else
{
- if ((data[c/8] & (1 << (c&7))) == 0) return MATCH_NOMATCH;
+ if ((data[c/8] & (1 << (c&7))) == 0) RRETURN(MATCH_NOMATCH);
}
}
}
{
for (i = 1; i <= min; i++)
{
- if (eptr >= md->end_subject) return MATCH_NOMATCH;
+ if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
c = *eptr++;
- if ((data[c/8] & (1 << (c&7))) == 0) return MATCH_NOMATCH;
+ if ((data[c/8] & (1 << (c&7))) == 0) RRETURN(MATCH_NOMATCH);
}
}
/* UTF-8 mode */
if (md->utf8)
{
- for (i = min;; i++)
+ for (fi = min;; fi++)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
- if (i >= max || eptr >= md->end_subject) return MATCH_NOMATCH;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ if (fi >= max || eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
GETCHARINC(c, eptr);
if (c > 255)
{
- if (op == OP_CLASS) return MATCH_NOMATCH;
+ if (op == OP_CLASS) RRETURN(MATCH_NOMATCH);
}
else
{
- if ((data[c/8] & (1 << (c&7))) == 0) return MATCH_NOMATCH;
+ if ((data[c/8] & (1 << (c&7))) == 0) RRETURN(MATCH_NOMATCH);
}
}
}
#endif
/* Not UTF-8 mode */
{
- for (i = min;; i++)
+ for (fi = min;; fi++)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
- if (i >= max || eptr >= md->end_subject) return MATCH_NOMATCH;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ if (fi >= max || eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
c = *eptr++;
- if ((data[c/8] & (1 << (c&7))) == 0) return MATCH_NOMATCH;
+ if ((data[c/8] & (1 << (c&7))) == 0) RRETURN(MATCH_NOMATCH);
}
}
/* Control never gets here */
else
{
- const uschar *pp = eptr;
+ pp = eptr;
#ifdef SUPPORT_UTF8
/* UTF-8 mode */
}
for (;;)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
if (eptr-- == pp) break; /* Stop if tried at original pos */
BACKCHAR(eptr);
}
}
while (eptr >= pp)
{
- if ((rrc = match(eptr--, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ eptr--;
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
}
}
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
}
}
/* Control never gets here */
#ifdef SUPPORT_UTF8
case OP_XCLASS:
{
- const uschar *data = ecode + 1 + LINK_SIZE; /* Save for matching */
+ data = ecode + 1 + LINK_SIZE; /* Save for matching */
ecode += GET(ecode, 1); /* Advance past the item */
switch (*ecode)
for (i = 1; i <= min; i++)
{
- if (eptr >= md->end_subject) return MATCH_NOMATCH;
+ if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
GETCHARINC(c, eptr);
- if (!match_xclass(c, data)) return MATCH_NOMATCH;
+ if (!match_xclass(c, data)) RRETURN(MATCH_NOMATCH);
}
/* If max == min we can continue with the main loop without the
if (minimize)
{
- for (i = min;; i++)
+ for (fi = min;; fi++)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
- if (i >= max || eptr >= md->end_subject) return MATCH_NOMATCH;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ if (fi >= max || eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
GETCHARINC(c, eptr);
- if (!match_xclass(c, data)) return MATCH_NOMATCH;
+ if (!match_xclass(c, data)) RRETURN(MATCH_NOMATCH);
}
/* Control never gets here */
}
else
{
- const uschar *pp = eptr;
+ pp = eptr;
for (i = min; i < max; i++)
{
int len = 1;
}
for(;;)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
if (eptr-- == pp) break; /* Stop if tried at original pos */
BACKCHAR(eptr)
}
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
}
/* Control never gets here */
case OP_CHARS:
{
- register int length = ecode[1];
+ register int slen = ecode[1];
ecode += 2;
#ifdef DEBUG /* Sigh. Some compilers never learn. */
else
{
printf("matching subject ");
- pchars(eptr, length, TRUE, md);
+ pchars(eptr, slen, TRUE, md);
printf(" against pattern ");
}
- pchars(ecode, length, FALSE, md);
+ pchars(ecode, slen, FALSE, md);
printf("\n");
#endif
- if (length > md->end_subject - eptr) return MATCH_NOMATCH;
+ if (slen > md->end_subject - eptr) RRETURN(MATCH_NOMATCH);
if ((ims & PCRE_CASELESS) != 0)
{
- while (length-- > 0)
+ while (slen-- > 0)
if (md->lcc[*ecode++] != md->lcc[*eptr++])
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
}
else
{
- while (length-- > 0) if (*ecode++ != *eptr++) return MATCH_NOMATCH;
+ while (slen-- > 0) if (*ecode++ != *eptr++) RRETURN(MATCH_NOMATCH);
}
}
break;
#ifdef SUPPORT_UTF8
if (md->utf8)
{
- int len = 1;
- const uschar *charptr = ecode;
- GETCHARLEN(c, ecode, len);
- if (min * len > md->end_subject - eptr) return MATCH_NOMATCH;
- ecode += len;
+ length = 1;
+ charptr = ecode;
+ GETCHARLEN(fc, ecode, length);
+ if (min * length > md->end_subject - eptr) RRETURN(MATCH_NOMATCH);
+ ecode += length;
/* Handle multibyte character matching specially here. There is no
support for any kind of casing for multibyte characters. */
- if (len > 1)
+ if (length > 1)
{
for (i = 1; i <= min; i++)
{
- if (memcmp(eptr, charptr, len) != 0) return MATCH_NOMATCH;
- eptr += len;
+ if (memcmp(eptr, charptr, length) != 0) RRETURN(MATCH_NOMATCH);
+ eptr += length;
}
if (min == max) continue;
if (minimize)
{
- for (i = min;; i++)
+ for (fi = min;; fi++)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
- if (i >= max ||
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ if (fi >= max ||
eptr >= md->end_subject ||
- memcmp(eptr, charptr, len) != 0)
- return MATCH_NOMATCH;
- eptr += len;
+ memcmp(eptr, charptr, length) != 0)
+ RRETURN(MATCH_NOMATCH);
+ eptr += length;
}
/* Control never gets here */
}
else
{
- const uschar *pp = eptr;
+ pp = eptr;
for (i = min; i < max; i++)
{
- if (eptr > md->end_subject - len ||
- memcmp(eptr, charptr, len) != 0)
+ if (eptr > md->end_subject - length ||
+ memcmp(eptr, charptr, length) != 0)
break;
- eptr += len;
+ eptr += length;
}
while (eptr >= pp)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
- eptr -= len;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ eptr -= length;
}
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
}
/* Control never gets here */
}
/* If the length of a UTF-8 character is 1, we fall through here, and
obey the code as for non-UTF-8 characters below, though in this case the
- value of c will always be < 128. */
+ value of fc will always be < 128. */
}
else
#endif
/* When not in UTF-8 mode, load a single-byte character. */
{
- if (min > md->end_subject - eptr) return MATCH_NOMATCH;
- c = *ecode++;
+ if (min > md->end_subject - eptr) RRETURN(MATCH_NOMATCH);
+ fc = *ecode++;
}
- /* The value of c at this point is always less than 256, though we may or
+ /* The value of fc at this point is always less than 256, though we may or
may not be in UTF-8 mode. The code is duplicated for the caseless and
caseful cases, for speed, since matching characters is likely to be quite
common. First, ensure the minimum number of matches are present. If min =
matching character if failing, up to the maximum. Alternatively, if
maximizing, find the maximum number of characters and work backwards. */
- DPRINTF(("matching %c{%d,%d} against subject %.*s\n", c, min, max,
+ DPRINTF(("matching %c{%d,%d} against subject %.*s\n", fc, min, max,
max, eptr));
if ((ims & PCRE_CASELESS) != 0)
{
- c = md->lcc[c];
+ fc = md->lcc[fc];
for (i = 1; i <= min; i++)
- if (c != md->lcc[*eptr++]) return MATCH_NOMATCH;
+ if (fc != md->lcc[*eptr++]) RRETURN(MATCH_NOMATCH);
if (min == max) continue;
if (minimize)
{
- for (i = min;; i++)
+ for (fi = min;; fi++)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
- if (i >= max || eptr >= md->end_subject ||
- c != md->lcc[*eptr++])
- return MATCH_NOMATCH;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ if (fi >= max || eptr >= md->end_subject ||
+ fc != md->lcc[*eptr++])
+ RRETURN(MATCH_NOMATCH);
}
/* Control never gets here */
}
else
{
- const uschar *pp = eptr;
+ pp = eptr;
for (i = min; i < max; i++)
{
- if (eptr >= md->end_subject || c != md->lcc[*eptr]) break;
+ if (eptr >= md->end_subject || fc != md->lcc[*eptr]) break;
eptr++;
}
while (eptr >= pp)
- if ((rrc = match(eptr--, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
- return MATCH_NOMATCH;
+ {
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ eptr--;
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ }
+ RRETURN(MATCH_NOMATCH);
}
/* Control never gets here */
}
else
{
- for (i = 1; i <= min; i++) if (c != *eptr++) return MATCH_NOMATCH;
+ for (i = 1; i <= min; i++) if (fc != *eptr++) RRETURN(MATCH_NOMATCH);
if (min == max) continue;
if (minimize)
{
- for (i = min;; i++)
+ for (fi = min;; fi++)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
- if (i >= max || eptr >= md->end_subject || c != *eptr++)
- return MATCH_NOMATCH;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ if (fi >= max || eptr >= md->end_subject || fc != *eptr++)
+ RRETURN(MATCH_NOMATCH);
}
/* Control never gets here */
}
else
{
- const uschar *pp = eptr;
+ pp = eptr;
for (i = min; i < max; i++)
{
- if (eptr >= md->end_subject || c != *eptr) break;
+ if (eptr >= md->end_subject || fc != *eptr) break;
eptr++;
}
while (eptr >= pp)
- if ((rrc = match(eptr--, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
- return MATCH_NOMATCH;
+ {
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ eptr--;
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ }
+ RRETURN(MATCH_NOMATCH);
}
}
/* Control never gets here */
checking can be multibyte. */
case OP_NOT:
- if (eptr >= md->end_subject) return MATCH_NOMATCH;
+ if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
ecode++;
GETCHARINCTEST(c, eptr);
if ((ims & PCRE_CASELESS) != 0)
if (c < 256)
#endif
c = md->lcc[c];
- if (md->lcc[*ecode++] == c) return MATCH_NOMATCH;
+ if (md->lcc[*ecode++] == c) RRETURN(MATCH_NOMATCH);
}
else
{
- if (*ecode++ == c) return MATCH_NOMATCH;
+ if (*ecode++ == c) RRETURN(MATCH_NOMATCH);
}
break;
characters left in the subject. */
REPEATNOTCHAR:
- if (min > md->end_subject - eptr) return MATCH_NOMATCH;
- c = *ecode++;
+ if (min > md->end_subject - eptr) RRETURN(MATCH_NOMATCH);
+ fc = *ecode++;
/* The code is duplicated for the caseless and caseful cases, for speed,
since matching characters is likely to be quite common. First, ensure the
maximum. Alternatively, if maximizing, find the maximum number of
characters and work backwards. */
- DPRINTF(("negative matching %c{%d,%d} against subject %.*s\n", c, min, max,
+ DPRINTF(("negative matching %c{%d,%d} against subject %.*s\n", fc, min, max,
max, eptr));
if ((ims & PCRE_CASELESS) != 0)
{
- c = md->lcc[c];
+ fc = md->lcc[fc];
#ifdef SUPPORT_UTF8
/* UTF-8 mode */
{
GETCHARINC(d, eptr);
if (d < 256) d = md->lcc[d];
- if (c == d) return MATCH_NOMATCH;
+ if (fc == d) RRETURN(MATCH_NOMATCH);
}
}
else
/* Not UTF-8 mode */
{
for (i = 1; i <= min; i++)
- if (c == md->lcc[*eptr++]) return MATCH_NOMATCH;
+ if (fc == md->lcc[*eptr++]) RRETURN(MATCH_NOMATCH);
}
if (min == max) continue;
if (md->utf8)
{
register int d;
- for (i = min;; i++)
+ for (fi = min;; fi++)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
GETCHARINC(d, eptr);
if (d < 256) d = md->lcc[d];
- if (i >= max || eptr >= md->end_subject || c == d)
- return MATCH_NOMATCH;
+ if (fi >= max || eptr >= md->end_subject || fc == d)
+ RRETURN(MATCH_NOMATCH);
}
}
else
#endif
/* Not UTF-8 mode */
{
- for (i = min;; i++)
+ for (fi = min;; fi++)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
- if (i >= max || eptr >= md->end_subject || c == md->lcc[*eptr++])
- return MATCH_NOMATCH;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ if (fi >= max || eptr >= md->end_subject || fc == md->lcc[*eptr++])
+ RRETURN(MATCH_NOMATCH);
}
}
/* Control never gets here */
else
{
- const uschar *pp = eptr;
+ pp = eptr;
#ifdef SUPPORT_UTF8
/* UTF-8 mode */
if (eptr >= md->end_subject) break;
GETCHARLEN(d, eptr, len);
if (d < 256) d = md->lcc[d];
- if (c == d) break;
+ if (fc == d) break;
eptr += len;
}
for(;;)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
if (eptr-- == pp) break; /* Stop if tried at original pos */
BACKCHAR(eptr);
}
{
for (i = min; i < max; i++)
{
- if (eptr >= md->end_subject || c == md->lcc[*eptr]) break;
+ if (eptr >= md->end_subject || fc == md->lcc[*eptr]) break;
eptr++;
}
while (eptr >= pp)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
eptr--;
}
}
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
}
/* Control never gets here */
}
for (i = 1; i <= min; i++)
{
GETCHARINC(d, eptr);
- if (c == d) return MATCH_NOMATCH;
+ if (fc == d) RRETURN(MATCH_NOMATCH);
}
}
else
/* Not UTF-8 mode */
{
for (i = 1; i <= min; i++)
- if (c == *eptr++) return MATCH_NOMATCH;
+ if (fc == *eptr++) RRETURN(MATCH_NOMATCH);
}
if (min == max) continue;
if (md->utf8)
{
register int d;
- for (i = min;; i++)
+ for (fi = min;; fi++)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
GETCHARINC(d, eptr);
- if (i >= max || eptr >= md->end_subject || c == d)
- return MATCH_NOMATCH;
+ if (fi >= max || eptr >= md->end_subject || fc == d)
+ RRETURN(MATCH_NOMATCH);
}
}
else
#endif
/* Not UTF-8 mode */
{
- for (i = min;; i++)
+ for (fi = min;; fi++)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
- if (i >= max || eptr >= md->end_subject || c == *eptr++)
- return MATCH_NOMATCH;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ if (fi >= max || eptr >= md->end_subject || fc == *eptr++)
+ RRETURN(MATCH_NOMATCH);
}
}
/* Control never gets here */
else
{
- const uschar *pp = eptr;
+ pp = eptr;
#ifdef SUPPORT_UTF8
/* UTF-8 mode */
int len = 1;
if (eptr >= md->end_subject) break;
GETCHARLEN(d, eptr, len);
- if (c == d) break;
+ if (fc == d) break;
eptr += len;
}
for(;;)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
if (eptr-- == pp) break; /* Stop if tried at original pos */
BACKCHAR(eptr);
}
{
for (i = min; i < max; i++)
{
- if (eptr >= md->end_subject || c == *eptr) break;
+ if (eptr >= md->end_subject || fc == *eptr) break;
eptr++;
}
while (eptr >= pp)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
eptr--;
}
}
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
}
}
/* Control never gets here */
UTF-8 mode, but it does no harm. Separate the UTF-8 code completely as that
is tidier. */
- if (min > md->end_subject - eptr) return MATCH_NOMATCH;
+ if (min > md->end_subject - eptr) RRETURN(MATCH_NOMATCH);
if (min > 0)
{
#ifdef SUPPORT_UTF8
{
if (eptr >= md->end_subject ||
(*eptr++ == NEWLINE && (ims & PCRE_DOTALL) == 0))
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
while (eptr < md->end_subject && (*eptr & 0xc0) == 0x80) eptr++;
}
break;
case OP_NOT_DIGIT:
for (i = 1; i <= min; i++)
{
- if (eptr >= md->end_subject) return MATCH_NOMATCH;
+ if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
GETCHARINC(c, eptr);
if (c < 256 && (md->ctypes[c] & ctype_digit) != 0)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
}
break;
{
if (eptr >= md->end_subject ||
*eptr >= 128 || (md->ctypes[*eptr++] & ctype_digit) == 0)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
/* No need to skip more bytes - we know it's a 1-byte character */
}
break;
{
if (eptr >= md->end_subject ||
(*eptr < 128 && (md->ctypes[*eptr++] & ctype_space) != 0))
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
while (eptr < md->end_subject && (*eptr & 0xc0) == 0x80) eptr++;
}
break;
{
if (eptr >= md->end_subject ||
*eptr >= 128 || (md->ctypes[*eptr++] & ctype_space) == 0)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
/* No need to skip more bytes - we know it's a 1-byte character */
}
break;
{
if (eptr >= md->end_subject ||
(*eptr < 128 && (md->ctypes[*eptr++] & ctype_word) != 0))
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
while (eptr < md->end_subject && (*eptr & 0xc0) == 0x80) eptr++;
}
break;
{
if (eptr >= md->end_subject ||
*eptr >= 128 || (md->ctypes[*eptr++] & ctype_word) == 0)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
/* No need to skip more bytes - we know it's a 1-byte character */
}
break;
if ((ims & PCRE_DOTALL) == 0)
{
for (i = 1; i <= min; i++)
- if (*eptr++ == NEWLINE) return MATCH_NOMATCH;
+ if (*eptr++ == NEWLINE) RRETURN(MATCH_NOMATCH);
}
else eptr += min;
break;
case OP_NOT_DIGIT:
for (i = 1; i <= min; i++)
- if ((md->ctypes[*eptr++] & ctype_digit) != 0) return MATCH_NOMATCH;
+ if ((md->ctypes[*eptr++] & ctype_digit) != 0) RRETURN(MATCH_NOMATCH);
break;
case OP_DIGIT:
for (i = 1; i <= min; i++)
- if ((md->ctypes[*eptr++] & ctype_digit) == 0) return MATCH_NOMATCH;
+ if ((md->ctypes[*eptr++] & ctype_digit) == 0) RRETURN(MATCH_NOMATCH);
break;
case OP_NOT_WHITESPACE:
for (i = 1; i <= min; i++)
- if ((md->ctypes[*eptr++] & ctype_space) != 0) return MATCH_NOMATCH;
+ if ((md->ctypes[*eptr++] & ctype_space) != 0) RRETURN(MATCH_NOMATCH);
break;
case OP_WHITESPACE:
for (i = 1; i <= min; i++)
- if ((md->ctypes[*eptr++] & ctype_space) == 0) return MATCH_NOMATCH;
+ if ((md->ctypes[*eptr++] & ctype_space) == 0) RRETURN(MATCH_NOMATCH);
break;
case OP_NOT_WORDCHAR:
for (i = 1; i <= min; i++)
if ((md->ctypes[*eptr++] & ctype_word) != 0)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
break;
case OP_WORDCHAR:
for (i = 1; i <= min; i++)
if ((md->ctypes[*eptr++] & ctype_word) == 0)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
break;
}
}
/* UTF-8 mode */
if (md->utf8)
{
- for (i = min;; i++)
+ for (fi = min;; fi++)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
- if (i >= max || eptr >= md->end_subject) return MATCH_NOMATCH;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ if (fi >= max || eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
GETCHARINC(c, eptr);
switch(ctype)
{
case OP_ANY:
- if ((ims & PCRE_DOTALL) == 0 && c == NEWLINE) return MATCH_NOMATCH;
+ if ((ims & PCRE_DOTALL) == 0 && c == NEWLINE) RRETURN(MATCH_NOMATCH);
break;
case OP_ANYBYTE:
case OP_NOT_DIGIT:
if (c < 256 && (md->ctypes[c] & ctype_digit) != 0)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
break;
case OP_DIGIT:
if (c >= 256 || (md->ctypes[c] & ctype_digit) == 0)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
break;
case OP_NOT_WHITESPACE:
if (c < 256 && (md->ctypes[c] & ctype_space) != 0)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
break;
case OP_WHITESPACE:
if (c >= 256 || (md->ctypes[c] & ctype_space) == 0)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
break;
case OP_NOT_WORDCHAR:
if (c < 256 && (md->ctypes[c] & ctype_word) != 0)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
break;
case OP_WORDCHAR:
if (c >= 256 && (md->ctypes[c] & ctype_word) == 0)
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
break;
}
}
#endif
/* Not UTF-8 mode */
{
- for (i = min;; i++)
+ for (fi = min;; fi++)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
- if (i >= max || eptr >= md->end_subject) return MATCH_NOMATCH;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
+ if (fi >= max || eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
c = *eptr++;
switch(ctype)
{
case OP_ANY:
- if ((ims & PCRE_DOTALL) == 0 && c == NEWLINE) return MATCH_NOMATCH;
+ if ((ims & PCRE_DOTALL) == 0 && c == NEWLINE) RRETURN(MATCH_NOMATCH);
break;
case OP_ANYBYTE:
break;
case OP_NOT_DIGIT:
- if ((md->ctypes[c] & ctype_digit) != 0) return MATCH_NOMATCH;
+ if ((md->ctypes[c] & ctype_digit) != 0) RRETURN(MATCH_NOMATCH);
break;
case OP_DIGIT:
- if ((md->ctypes[c] & ctype_digit) == 0) return MATCH_NOMATCH;
+ if ((md->ctypes[c] & ctype_digit) == 0) RRETURN(MATCH_NOMATCH);
break;
case OP_NOT_WHITESPACE:
- if ((md->ctypes[c] & ctype_space) != 0) return MATCH_NOMATCH;
+ if ((md->ctypes[c] & ctype_space) != 0) RRETURN(MATCH_NOMATCH);
break;
case OP_WHITESPACE:
- if ((md->ctypes[c] & ctype_space) == 0) return MATCH_NOMATCH;
+ if ((md->ctypes[c] & ctype_space) == 0) RRETURN(MATCH_NOMATCH);
break;
case OP_NOT_WORDCHAR:
- if ((md->ctypes[c] & ctype_word) != 0) return MATCH_NOMATCH;
+ if ((md->ctypes[c] & ctype_word) != 0) RRETURN(MATCH_NOMATCH);
break;
case OP_WORDCHAR:
- if ((md->ctypes[c] & ctype_word) == 0) return MATCH_NOMATCH;
+ if ((md->ctypes[c] & ctype_word) == 0) RRETURN(MATCH_NOMATCH);
break;
}
}
else
{
- const uschar *pp = eptr;
+ pp = eptr;
#ifdef SUPPORT_UTF8
/* UTF-8 mode */
for(;;)
{
- if ((rrc = match(eptr, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
if (eptr-- == pp) break; /* Stop if tried at original pos */
BACKCHAR(eptr);
}
while (eptr >= pp)
{
- if ((rrc = match(eptr--, ecode, offset_top, md, ims, eptrb, 0)) !=
- MATCH_NOMATCH) return rrc;
+ RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
+ eptr--;
+ if (rrc != MATCH_NOMATCH) RRETURN(rrc);
}
}
/* Get here if we can't make it match with any permitted repetitions */
- return MATCH_NOMATCH;
+ RRETURN(MATCH_NOMATCH);
}
/* Control never gets here */
default:
DPRINTF(("Unknown opcode %d\n", *ecode));
- return PCRE_ERROR_UNKNOWN_NODE;
+ RRETURN(PCRE_ERROR_UNKNOWN_NODE);
}
/* Do not stick any code in here without much thought; it is assumed
}
+/***************************************************************************
+****************************************************************************
+ RECURSION IN THE match() FUNCTION
+
+Undefine all the macros that were defined above to handle this. */
+
+#ifdef NO_RECURSE
+#undef eptr
+#undef ecode
+#undef offset_top
+#undef ims
+#undef eptrb
+#undef flags
+
+#undef callpat
+#undef charptr
+#undef data
+#undef lastptr
+#undef next
+#undef pp
+#undef prev
+#undef saved_eptr
+
+#undef new_recursive
+
+#undef cur_is_word
+#undef condition
+#undef minimize
+#undef prev_is_word
+
+#undef original_ims
+
+#undef ctype
+#undef length
+#undef max
+#undef min
+#undef number
+#undef offset
+#undef op
+#undef save_capture_last
+#undef save_offset1
+#undef save_offset2
+#undef save_offset3
+#undef stacksave
+
+#undef newptrb
+
+#endif
+
+/* These two are defined as macros in both cases */
+
+#undef fc
+#undef fi
+
+/***************************************************************************
+***************************************************************************/
+
/*************************************************
< -1 => some kind of unexpected problem
*/
-int
+EXPORT int
pcre_exec(const pcre *external_re, const pcre_extra *extra_data,
const char *subject, int length, int start_offset, int options, int *offsets,
int offsetcount)
{
register unsigned int flags = extra_data->flags;
if ((flags & PCRE_EXTRA_STUDY_DATA) != 0)
- study = extra_data->study_data;
+ study = (const pcre_study_data *)extra_data->study_data;
if ((flags & PCRE_EXTRA_MATCH_LIMIT) != 0)
match_block.match_limit = extra_data->match_limit;
if ((flags & PCRE_EXTRA_CALLOUT_DATA) != 0)
match_block.lcc = re->tables + lcc_offset;
match_block.ctypes = re->tables + ctypes_offset;
+/* Check a UTF-8 string if required. Unfortunately there's no way of passing
+back the character offset. */
+
+#ifdef SUPPORT_UTF8
+if (match_block.utf8 && (options & PCRE_NO_UTF8_CHECK) == 0)
+ {
+ if (valid_utf8((uschar *)subject, length) >= 0)
+ return PCRE_ERROR_BADUTF8;
+ if (start_offset > 0 && start_offset < length)
+ {
+ int tb = ((uschar *)subject)[start_offset];
+ if (tb > 127)
+ {
+ tb &= 0xc0;
+ if (tb != 0 && tb != 0xc0) return PCRE_ERROR_BADUTF8_OFFSET;
+ }
+ }
+ }
+#endif
+
/* The ims options can vary during the matching as a result of the presence
of (?ims) items in the pattern. They are kept in a local variable so that
restoring at the exit of a group is easy. */
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