|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
?? ?? 1999, Version 4.0 Beta 3
+- Reworked preg_* functions according to the new PCRE API, which also made
+ them behave much more like Perl ones (Andrey)
+- Made it possible to specify external location of PCRE library (Andrey)
+- Updated bundled PCRE library to version 2.08 (Andrey)
- count()/is_array/is_object... speedups. (Thies)
- OCI8 supports appending and positioning when saving LOBs (Thies)
- Added metaphone support (Thies)
/* define if you want to use the PCRE extension */
#define HAVE_PCRE 0
+#define HAVE_BUNDLED_PCRE 0
AC_MSG_CHECKING(whether to include PCRE support)
AC_ARG_WITH(pcre-regex,
-[ --without-pcre-regex Don't include Perl Compatible Regular Expressions support],[
- if test "$withval" = "yes"; then
- EXTRA_LIBS="-L$abs_builddir/ext/pcre/pcrelib -lpcre $EXTRA_LIBS"
- PCRE_SUBDIR="pcrelib"
- AC_DEFINE(HAVE_PCRE, 1)
- AC_MSG_RESULT(yes)
- PHP_EXTENSION(pcre)
- else
- AC_MSG_RESULT(no)
- fi
+[ --without-pcre-regex Don't include Perl Compatible Regular Expressions support
+ Use --with-pcre-regex=DIR to specify DIR where PCRE include
+ and library files are located],[
+ case "$withval" in
+ no)
+ AC_MSG_RESULT(no)
+ ;;
+ yes)
+ EXTRA_LIBS="-L$abs_builddir/ext/pcre/pcrelib -lpcre $EXTRA_LIBS"
+ PCRE_SUBDIR="pcrelib"
+ AC_DEFINE(HAVE_BUNDLED_PCRE, 1)
+ AC_MSG_RESULT(yes)
+ PHP_EXTENSION(pcre)
+ ;;
+ *)
+ if test -f $withval/pcre.h ; then
+ changequote({,})
+ pcre_major=`grep PCRE_MAJOR $withval/pcre.h | sed -e 's/[^0-9]//g'`
+ pcre_minor=`grep PCRE_MINOR $withval/pcre.h | sed -e 's/[^0-9]//g'`
+ changequote([,])
+ pcre_version=$pcre_major$pcre_minor
+ if test "$pcre_version" -ge 208; then
+ AC_ADD_INCLUDE($withval)
+ else
+ AC_MSG_ERROR(PCRE extension requires PCRE library version >= 2.08)
+ fi
+ else
+ AC_MSG_ERROR(Could not find pcre.h in $withval)
+ fi
+
+ if test -f $withval/libpcre.a ; then
+ AC_ADD_LIBRARY_WITH_PATH(pcre, $withval)
+ else
+ AC_MSG_ERROR(Could not find libpcre.a in $withval)
+ fi
+
+ AC_DEFINE(HAVE_PCRE, 1)
+ AC_MSG_RESULT(yes)
+ PHP_EXTENSION(pcre)
+ ;;
+ esac
],[
EXTRA_LIBS="-L$abs_builddir/ext/pcre/pcrelib -lpcre $EXTRA_LIBS"
PCRE_SUBDIR="pcrelib"
- AC_DEFINE(HAVE_PCRE, 1)
+ AC_DEFINE(HAVE_BUNDLED_PCRE, 1)
AC_MSG_RESULT(yes)
PHP_EXTENSION(pcre)
])
AC_MSG_CHECKING(whether to include PCRE support)
AC_ARG_WITH(pcre-regex,
-[ --without-pcre-regex Don't include Perl Compatible Regular Expressions support],[
- if test "$withval" = "yes"; then
- EXTRA_LIBS="-L$abs_builddir/ext/pcre/pcrelib -lpcre $EXTRA_LIBS"
- PCRE_SUBDIR="pcrelib"
- AC_DEFINE(HAVE_PCRE, 1)
- AC_MSG_RESULT(yes)
- PHP_EXTENSION(pcre)
- else
- AC_MSG_RESULT(no)
- fi
+[ --without-pcre-regex Don't include Perl Compatible Regular Expressions support
+ Use --with-pcre-regex=DIR to specify DIR where PCRE include
+ and library files are located],[
+ case "$withval" in
+ no)
+ AC_MSG_RESULT(no)
+ ;;
+ yes)
+ EXTRA_LIBS="-L$abs_builddir/ext/pcre/pcrelib -lpcre $EXTRA_LIBS"
+ PCRE_SUBDIR="pcrelib"
+ AC_DEFINE(HAVE_BUNDLED_PCRE, 1)
+ AC_MSG_RESULT(yes)
+ PHP_EXTENSION(pcre)
+ ;;
+ *)
+ if test -f $withval/pcre.h ; then
+ changequote({,})
+ pcre_major=`grep PCRE_MAJOR $withval/pcre.h | sed -e 's/[^0-9]//g'`
+ pcre_minor=`grep PCRE_MINOR $withval/pcre.h | sed -e 's/[^0-9]//g'`
+ changequote([,])
+ pcre_version=$pcre_major$pcre_minor
+ if test "$pcre_version" -ge 208; then
+ AC_ADD_INCLUDE($withval)
+ else
+ AC_MSG_ERROR(PCRE extension requires PCRE library version >= 2.08)
+ fi
+ else
+ AC_MSG_ERROR(Could not find pcre.h in $withval)
+ fi
+
+ if test -f $withval/libpcre.a ; then
+ AC_ADD_LIBRARY_WITH_PATH(pcre, $withval)
+ else
+ AC_MSG_ERROR(Could not find libpcre.a in $withval)
+ fi
+
+ AC_DEFINE(HAVE_PCRE, 1)
+ AC_MSG_RESULT(yes)
+ PHP_EXTENSION(pcre)
+ ;;
+ esac
],[
EXTRA_LIBS="-L$abs_builddir/ext/pcre/pcrelib -lpcre $EXTRA_LIBS"
PCRE_SUBDIR="pcrelib"
- AC_DEFINE(HAVE_PCRE, 1)
+ AC_DEFINE(HAVE_BUNDLED_PCRE, 1)
AC_MSG_RESULT(yes)
PHP_EXTENSION(pcre)
])
------------------
+Version 2.08 31-Aug-99
+----------------------
+
+1. When startoffset was not zero and the pattern began with ".*", PCRE was not
+trying to match at the startoffset position, but instead was moving forward to
+the next newline as if a previous match had failed.
+
+2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
+and could get into a loop if a null string was matched other than at the start
+of the subject.
+
+3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
+be distinguished at compile time, and for completeness also added PCRE_DATE.
+
+5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
+in GnuWin32 environments.
+
+
+Version 2.07 29-Jul-99
+----------------------
+
+1. The documentation is now supplied in plain text form and HTML as well as in
+the form of man page sources.
+
+2. C++ compilers don't like assigning (void *) values to other pointer types.
+In particular this affects malloc(). Although there is no problem in Standard
+C, I've put in casts to keep C++ compilers happy.
+
+3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
+should be (const char *).
+
+4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
+be useful for non-Unix systems who don't want to bother with the POSIX stuff.
+However, I haven't made this a standard facility. The documentation doesn't
+mention it, and the Makefile doesn't support it.
+
+5. The Makefile now contains an "install" target, with editable destinations at
+the top of the file. The pcretest program is not installed.
+
+6. pgrep -V now gives the PCRE version number and date.
+
+7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
+causing the entire string to be ignored, instead of just the last character.
+
+8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
+non-matching string, it can take a very, very long time, even for strings of
+quite modest length, because of the nested recursion. PCRE now does better in
+some of these cases. It does this by remembering the last required literal
+character in the pattern, and pre-searching the subject to ensure it is present
+before running the real match. In other words, it applies a heuristic to detect
+some types of certain failure quickly, and in the above example, if presented
+with a string that has no trailing " it gives "no match" very quickly.
+
+9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
+other alternatives are tried instead.
+
+
+Version 2.06 09-Jun-99
+----------------------
+
+1. Change pcretest's output for amount of store used to show just the code
+space, because the remainder (the data block) varies in size between 32-bit and
+64-bit systems.
+
+2. Added an extra argument to pcre_exec() to supply an offset in the subject to
+start matching at. This allows lookbehinds to work when searching for multiple
+occurrences in a string.
+
+3. Added additional options to pcretest for testing multiple occurrences:
+
+ /+ outputs the rest of the string that follows a match
+ /g loops for multiple occurrences, using the new startoffset argument
+ /G loops for multiple occurrences by passing an incremented pointer
+
+4. PCRE wasn't doing the "first character" optimization for patterns starting
+with \b or \B, though it was doing it for other lookbehind assertions. That is,
+it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
+the letter 'x'. On long subject strings, this gives a significant speed-up.
+
+
Version 2.05 21-Apr-99
----------------------
* possible to pass over a pointer to character tables built in the current *
* locale by pcre_maketables(). To use the default tables, this new arguement *
* should be passed as NULL. *
+* *
+* IMPORTANT FOR THOSE UPGRADING FROM VERSION 2.05 *
+* *
+* Yet another (and again I hope this really is the last) change has been made *
+* to the API for the pcre_exec() function. An additional argument has been *
+* added to make it possible to start the match other than at the start of the *
+* subject string. This is important if there are lookbehinds. The new man *
+* page has the details, but you just want to convert existing programs, all *
+* you need to do is to stick in a new fifth argument to pcre_exec(), with a *
+* value of zero. For example, change *
+* *
+* pcre_exec(pattern, extra, subject, length, options, ovec, ovecsize) *
+* to *
+* pcre_exec(pattern, extra, subject, length, 0, options, ovec, ovecsize) *
*******************************************************************************
+
The distribution should contain the following files:
ChangeLog log of changes to the code
LICENCE conditions for the use of PCRE
- Makefile for building PCRE
+ Makefile for building PCRE in Unix systems
README this file
- RunTest a shell script for running tests
+ RunTest a Unix shell script for running tests
Tech.Notes notes on the encoding
- pcre.3 man page for the functions
- pcreposix.3 man page for the POSIX wrapper API
+ pcre.3 man page source for the functions
+ pcre.3.txt plain text version
+ pcre.3.html HTML version
+ pcreposix.3 man page source for the POSIX wrapper API
+ pcreposix.3.txt plain text version
+ pcreposix.3.HTML HTML version
dftables.c auxiliary program for building chartables.c
get.c )
maketables.c )
pcreposix.h header for the external POSIX wrapper API
internal.h header for internal use
pcretest.c test program
- pgrep.1 man page for pgrep
+ pgrep.1 man page source for pgrep
+ pgrep.1.txt plain text version
+ pgrep.1.HTML HTML version
pgrep.c source of a grep utility that uses PCRE
perltest Perl test program
testinput1 test data, compatible with Perl 5.004 and 5.005
testinput2 test data for error messages and non-Perl things
testinput3 test data, compatible with Perl 5.005
testinput4 test data for locale-specific tests
- testoutput1 test results corresponding to testinput
+ testoutput1 test results corresponding to testinput1
testoutput2 test results corresponding to testinput2
testoutput3 test results corresponding to testinput3
testoutput4 test results corresponding to testinput4
-
-To build PCRE, edit Makefile for your system (it is a fairly simple make file,
-and there are some comments at the top) and then run it. It builds two
-libraries called libpcre.a and libpcreposix.a, a test program called pcretest,
-and the pgrep command.
-
-To test PCRE, run the RunTest script in the pcre directory. This runs pcretest
-on each of the testinput files in turn, and compares the output with the
+ dll.mk for Win32 DLL
+ pcre.def ditto
+
+To build PCRE on a Unix system, first edit Makefile for your system. It is a
+fairly simple make file, and there are some comments near the top, after the
+text "On a Unix system". Then run "make". It builds two libraries called
+libpcre.a and libpcreposix.a, a test program called pcretest, and the pgrep
+command. You can use "make install" to copy these, and the public header file
+pcre.h, to appropriate live directories on your system. These installation
+directories are defined at the top of the Makefile, and you should edit them if
+necessary.
+
+For a non-Unix system, read the comments at the top of Makefile, which give
+some hints on what needs to be done. PCRE has been compiled on Windows systems
+and on Macintoshes, but I don't know the details as I don't use those systems.
+It should be straightforward to build PCRE on any system that has a Standard C
+compiler.
+
+Some help in building a Win32 DLL of PCRE in GnuWin32 environments was
+contributed by Paul.Sokolovsky@technologist.com. These environments are
+Mingw32 (http://www.xraylith.wisc.edu/~khan/software/gnu-win32/) and
+CygWin (http://sourceware.cygnus.com/cygwin/). Paul comments:
+
+ For CygWin, set CFLAGS=-mno-cygwin, and do 'make dll'. You'll get
+ pcre.dll (containing pcreposix also), libpcre.dll.a, and dynamically
+ linked pgrep and pcretest. If you have /bin/sh, run RunTest (three
+ main test go ok, locale not supported).
+
+To test PCRE, run the RunTest script in the pcre directory. This can also be
+run by "make runtest". It runs the pcretest test program (which is documented
+below) on each of the testinput files in turn, and compares the output with the
contents of the corresponding testoutput file. A file called testtry is used to
-hold the output from pcretest (which is documented below).
-
-To run pcretest on just one of the test files, give its number as an argument
-to RunTest, for example:
+hold the output from pcretest. To run pcretest on just one of the test files,
+give its number as an argument to RunTest, for example:
RunTest 3
The first and third test files can also be fed directly into the perltest
-program to check that Perl gives the same results. The third file requires the
+script to check that Perl gives the same results. The third file requires the
additional features of release 5.005, which is why it is kept separate from the
main test input, which needs only Perl 5.004. In the long run, when 5.005 is
widespread, these two test files may get amalgamated.
in the comparison output, it means that locale is not available on your system,
despite being listed by "locale". This does not mean that PCRE is broken.
-To install PCRE, copy libpcre.a to any suitable library directory (e.g.
-/usr/local/lib), pcre.h to any suitable include directory (e.g.
-/usr/local/include), and pcre.3 to any suitable man directory (e.g.
-/usr/local/man/man3).
-
-To install the pgrep command, copy it to any suitable binary directory, (e.g.
-/usr/local/bin) and pgrep.1 to any suitable man directory (e.g.
-/usr/local/man/man1).
-
PCRE has its own native API, but a set of "wrapper" functions that are based on
the POSIX API are also supplied in the library libpcreposix.a. Note that this
just provides a POSIX calling interface to PCRE: the regular expressions
PCRE uses four tables for manipulating and identifying characters. The final
argument of the pcre_compile() function is a pointer to a block of memory
-containing the concatenated tables. A call to pcre_maketables() is used to
-generate a set of tables in the current locale. However, if the final argument
-is passed as NULL, a set of default tables that is built into the binary is
-used.
+containing the concatenated tables. A call to pcre_maketables() can be used to
+generate a set of tables in the current locale. If the final argument for
+pcre_compile() is passed as NULL, a set of default tables that is built into
+the binary is used.
The source file called chartables.c contains the default set of tables. This is
not supplied in the distribution, but is built by the program dftables
(compiled from dftables.c), which uses the ANSI C character handling functions
such as isalnum(), isalpha(), isupper(), islower(), etc. to build the table
-sources. This means that the default C locale set your system will control the
-contents of the tables. You can change the default tables by editing
-chartables.c and then re-building PCRE. If you do this, you should probably
-also edit Makefile to ensure that the file doesn't ever get re-generated.
+sources. This means that the default C locale which is set for your system will
+control the contents of these default tables. You can change the default tables
+by editing chartables.c and then re-building PCRE. If you do this, you should
+probably also edit Makefile to ensure that the file doesn't ever get
+re-generated.
The first two 256-byte tables provide lower casing and case flipping functions,
respectively. The next table consists of three 32-byte bit maps which identify
/abc/\
-then a backslash is added to the end of the pattern. This provides a way of
-testing the error condition that arises if a pattern finishes with a backslash,
-because
+then a backslash is added to the end of the pattern. This is done to provide a
+way of testing the error condition that arises if a pattern finishes with a
+backslash, because
/abc\/
pcretest to read the next line as a continuation of the regular expression.
The pattern may be followed by i, m, s, or x to set the PCRE_CASELESS,
-PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively. These
-options have the same effect as they do in Perl.
+PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively. For
+example:
+
+ /caseless/i
-There are also some upper case options that do not match Perl options: /A, /E,
-and /X set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and PCRE_EXTRA respectively.
+These modifier letters have the same effect as they do in Perl. There are
+others which set PCRE options that do not correspond to anything in Perl: /A,
+/E, and /X set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and PCRE_EXTRA respectively.
-The /L option must be followed directly by the name of a locale, for example,
+Searching for all possible matches within each subject string can be requested
+by the /g or /G modifier. After finding a match, PCRE is called again to search
+the remainder of the subject string. The difference between /g and /G is that
+the former uses the startoffset argument to pcre_exec() to start searching at
+a new point within the entire string (which is in effect what Perl does),
+whereas the latter passes over a shortened substring. This makes a difference
+to the matching process if the pattern begins with a lookbehind assertion
+(including \b or \B).
+
+If any call to pcre_exec() in a /g or /G sequence matches an empty string, the
+next call is done with the PCRE_NOTEMPTY flag set so that it cannot match an
+empty string again. This imitates the way Perl handles such cases when using
+the /g modifier or the split() function.
+
+There are a number of other modifiers for controlling the way pcretest
+operates.
+
+The /+ modifier requests that as well as outputting the substring that matched
+the entire pattern, pcretest should in addition output the remainder of the
+subject string. This is useful for tests where the subject contains multiple
+copies of the same substring.
+
+The /L modifier must be followed directly by the name of a locale, for example,
/pattern/Lfr
-For this reason, it must be the last option letter. The given locale is set,
+For this reason, it must be the last modifier letter. The given locale is set,
pcre_maketables() is called to build a set of character tables for the locale,
and this is then passed to pcre_compile() when compiling the regular
-expression. Without an /L option, NULL is passed as the tables pointer; that
+expression. Without an /L modifier, NULL is passed as the tables pointer; that
is, /L applies only to the expression on which it appears.
-The /I option requests that pcretest output information about the compiled
+The /I modifier requests that pcretest output information about the compiled
expression (whether it is anchored, has a fixed first character, and so on). It
does this by calling pcre_info() after compiling an expression, and outputting
the information it gets back. If the pattern is studied, the results of that
are also output.
-The /D option is a PCRE debugging feature, which also assumes /I. It causes the
-internal form of compiled regular expressions to be output after compilation.
+The /D modifier is a PCRE debugging feature, which also assumes /I. It causes
+the internal form of compiled regular expressions to be output after
+compilation.
-The /S option causes pcre_study() to be called after the expression has been
+The /S modifier causes pcre_study() to be called after the expression has been
compiled, and the results used when the expression is matched.
-The /M option causes information about the size of memory block used to hold
-the compile pattern to be output.
+The /M modifier causes the size of memory block used to hold the compiled
+pattern to be output.
-Finally, the /P option causes pcretest to call PCRE via the POSIX wrapper API
-rather than its native API. When this is done, all other options except /i and
-/m are ignored. REG_ICASE is set if /i is present, and REG_NEWLINE is set if /m
-is present. The wrapper functions force PCRE_DOLLAR_ENDONLY always, and
-PCRE_DOTALL unless REG_NEWLINE is set.
+Finally, the /P modifier causes pcretest to call PCRE via the POSIX wrapper API
+rather than its native API. When this is done, all other modifiers except /i,
+/m, and /+ are ignored. REG_ICASE is set if /i is present, and REG_NEWLINE is
+set if /m is present. The wrapper functions force PCRE_DOLLAR_ENDONLY always,
+and PCRE_DOTALL unless REG_NEWLINE is set.
Before each data line is passed to pcre_exec(), leading and trailing whitespace
is removed, and it is then scanned for \ escapes. The following are recognized:
\Gdd call pcre_get_substring() for substring dd after a successful match
(any decimal number less than 32)
\L call pcre_get_substringlist() after a successful match
+ \N pass the PCRE_NOTEMPTY option to pcre_exec()
\Odd set the size of the output vector passed to pcre_exec() to dd
(any number of decimal digits)
\Z pass the PCRE_NOTEOL option to pcre_exec()
whole pattern. Here is an example of an interactive pcretest run.
$ pcretest
- Testing Perl-Compatible Regular Expressions
- PCRE version 0.90 08-Sep-1997
+ PCRE version 2.06 08-Jun-1999
re> /^abc(\d+)/
data> abc123
- 0: abc123
- 1: 123
+ 0: abc123
+ 1: 123
data> xyz
No match
+If the strings contain any non-printing characters, they are output as \0x
+escapes. If the pattern has the /+ modifier, then the output for substring 0 is
+followed by the the rest of the subject string, identified by "0+" like this:
+
+ re> /cat/+
+ data> cataract
+ 0: cat
+ 0+ aract
+
+If the pattern has the /g or /G modifier, the results of successive matching
+attempts are output in sequence, like this:
+
+ re> /\Bi(\w\w)/g
+ data> Mississippi
+ 0: iss
+ 1: ss
+ 0: iss
+ 1: ss
+ 0: ipp
+ 1: pp
+
+"No match" is output only if the first match attempt fails.
+
If any of \C, \G, or \L are present in a data line that is successfully
matched, the substrings extracted by the convenience functions are output with
C, G, or L after the string number instead of a colon. This is in addition to
The perltest program tests Perl's regular expressions; it has the same
specification as pcretest, and so can be given identical input, except that
-input patterns can be followed only by Perl's lower case options. The contents
-of testinput1 and testinput3 meet this condition.
-
-The data lines are processed as Perl strings, so if they contain $ or @
-characters, these have to be escaped. For this reason, all such characters in
-the testinput file are escaped so that it can be used for perltest as well as
-for pcretest, and the special upper case options such as /A that pcretest
-recognizes are not used in this file. The output should be identical, apart
-from the initial identifying banner.
-
-The testinput2 and testinput4 files are not suitable for feeding to Perltest,
-since they do make use of the special upper case options and escapes that
+input patterns can be followed only by Perl's lower case modifiers. The
+contents of testinput1 and testinput3 meet this condition.
+
+The data lines are processed as Perl double-quoted strings, so if they contain
+" \ $ or @ characters, these have to be escaped. For this reason, all such
+characters in testinput1 and testinput3 are escaped so that they can be used
+for perltest as well as for pcretest, and the special upper case modifiers such
+as /A that pcretest recognizes are not used in these files. The output should
+be identical, apart from the initial identifying banner.
+
+The testinput2 and testinput4 files are not suitable for feeding to perltest,
+since they do make use of the special upper case modifiers and escapes that
pcretest uses to test some features of PCRE. The first of these files also
contains malformed regular expressions, in order to check that PCRE diagnoses
them correctly.
Philip Hazel <ph10@cam.ac.uk>
-April 1999
+July 1999
* Perl-Compatible Regular Expressions *
*************************************************/
-/* This file is automatically written by the makechartables auxiliary
+/* This file is automatically written by the dftables auxiliary
program. If you edit it by hand, you might like to edit the Makefile to
prevent its ever being regenerated.
"/*************************************************\n"
"* Perl-Compatible Regular Expressions *\n"
"*************************************************/\n\n"
- "/* This file is automatically written by the makechartables auxiliary \n"
+ "/* This file is automatically written by the dftables auxiliary \n"
"program. If you edit it by hand, you might like to edit the Makefile to \n"
"prevent its ever being regenerated.\n\n"
"This file is #included in the compilation of pcre.c to build the default\n"
--- /dev/null
+# dll.mk - auxilary Makefile to easy build dll's for mingw32 target
+# ver. 0.6 of 1999-03-25
+#
+# Homepage of this makefile - http://www.is.lg.ua/~paul/devel/
+# Homepage of original mingw32 project -
+# http://www.fu.is.saga-u.ac.jp/~colin/gcc.html
+#
+# How to use:
+# This makefile can:
+# 1. Create automatical .def file from list of objects
+# 2. Create .dll from objects and .def file, either automatical, or your
+# hand-written (maybe) file, which must have same basename as dll
+# WARNING! There MUST be object, which name match dll's name. Make sux.
+# 3. Create import library from .def (as for .dll, only its name required,
+# not dll itself)
+# By convention implibs for dll have .dll.a suffix, e.g. libstuff.dll.a
+# Why not just libstuff.a? 'Cos that's name for static lib, ok?
+# Process divided into 3 phases because:
+# 1. Pre-existent .def possible
+# 2. Generating implib is enough time-consuming
+#
+# Variables:
+# DLL_LDLIBS - libs for linking dll
+# DLL_LDFLAGS - flags for linking dll
+#
+# By using $(DLL_SUFFIX) instead of 'dll', e.g. stuff.$(DLL_SUFFIX)
+# you may help porting makefiles to other platforms
+#
+# Put this file in your make's include path (e.g. main include dir, for
+# more information see include section in make doc). Put in the beginning
+# of your own Makefile line "include dll.mk". Specify dependences, e.g.:
+#
+# Do all stuff in one step
+# libstuff.dll.a: $(OBJECTS) stuff.def
+# stuff.def: $(OBJECTS)
+#
+# Steps separated, pre-provided .def, link with user32
+#
+# DLL_LDLIBS=-luser32
+# stuff.dll: $(OBJECTS)
+# libstuff.dll.a: $(OBJECTS)
+
+
+DLLWRAP=dllwrap
+DLLTOOL=dlltool
+
+DLL_SUFFIX=dll
+
+.SUFFIXES: .o .$(DLL_SUFFIX)
+
+_%.def: %.o
+ $(DLLTOOL) --export-all --output-def $@ $^
+
+%.$(DLL_SUFFIX): %.o
+ $(DLLWRAP) --dllname $(notdir $@) --driver-name $(CC) --def $*.def -o $@ $(filter %.o,$^) $(DLL_LDFLAGS) $(DLL_LDLIBS)
+
+lib%.$(DLL_SUFFIX).a:%.def
+ $(DLLTOOL) --dllname $(notdir $*.dll) --def $< --output-lib $@
+
+# End
*************************************************/
-#define PCRE_VERSION "2.05 21-Apr-1999"
-
-
/* This is a library of functions to support regular expressions whose syntax
and semantics are as close as possible to those of the Perl 5 language. See
the file Tech.Notes for some information on the internals.
#define PCRE_IMS (PCRE_CASELESS|PCRE_MULTILINE|PCRE_DOTALL)
-/* Private options flags start at the most significant end of the two bytes.
-The public options defined in pcre.h start at the least significant end. Make
-sure they don't overlap! */
+/* Private options flags start at the most significant end of the four bytes,
+but skip the top bit so we can use ints for convenience without getting tangled
+with negative values. The public options defined in pcre.h start at the least
+significant end. Make sure they don't overlap, though now that we have expanded
+to four bytes there is plenty of space. */
-#define PCRE_FIRSTSET 0x8000 /* first_char is set */
-#define PCRE_STARTLINE 0x4000 /* start after \n for multiline */
-#define PCRE_INGROUP 0x2000 /* compiling inside a group */
+#define PCRE_FIRSTSET 0x40000000 /* first_char is set */
+#define PCRE_REQCHSET 0x20000000 /* req_char is set */
+#define PCRE_STARTLINE 0x10000000 /* start after \n for multiline */
+#define PCRE_INGROUP 0x08000000 /* compiling inside a group */
+#define PCRE_ICHANGED 0x04000000 /* i option changes within regex */
/* Options for the "extra" block produced by pcre_study(). */
(PCRE_CASELESS|PCRE_EXTENDED|PCRE_ANCHORED|PCRE_MULTILINE| \
PCRE_DOTALL|PCRE_DOLLAR_ENDONLY|PCRE_EXTRA|PCRE_UNGREEDY)
-#define PUBLIC_EXEC_OPTIONS (PCRE_ANCHORED|PCRE_NOTBOL|PCRE_NOTEOL)
+#define PUBLIC_EXEC_OPTIONS \
+ (PCRE_ANCHORED|PCRE_NOTBOL|PCRE_NOTEOL|PCRE_NOTEMPTY)
#define PUBLIC_STUDY_OPTIONS 0 /* None defined */
typedef struct real_pcre {
unsigned long int magic_number;
const unsigned char *tables;
- unsigned short int options;
- unsigned char top_bracket;
- unsigned char top_backref;
- unsigned char first_char;
- unsigned char code[1];
+ unsigned long int options;
+ uschar top_bracket;
+ uschar top_backref;
+ uschar first_char;
+ uschar req_char;
+ uschar code[1];
} real_pcre;
/* The real format of the extra block returned by pcre_study(). */
typedef struct real_pcre_extra {
- unsigned char options;
- unsigned char start_bits[32];
+ uschar options;
+ uschar start_bits[32];
} real_pcre_extra;
typedef struct compile_data {
const uschar *lcc; /* Points to lower casing table */
- const uschar *fcc; /* Points to case-flippint table */
+ const uschar *fcc; /* Points to case-flipping table */
const uschar *cbits; /* Points to character type table */
const uschar *ctypes; /* Points to table of type maps */
} compile_data;
BOOL notbol; /* NOTBOL flag */
BOOL noteol; /* NOTEOL flag */
BOOL endonly; /* Dollar not before final \n */
+ BOOL notempty; /* Empty string match not wanted */
const uschar *start_subject; /* Start of the subject string */
const uschar *end_subject; /* End of the subject string */
+ const uschar *start_match; /* Start of this match attempt */
const uschar *end_match_ptr; /* Subject position at end match */
int end_offset_top; /* Highwater mark at end of match */
- uschar regprev; /* Character previous to subject string (Andrey Zmievski) */
} match_data;
/* Bit definitions for entries in the pcre_ctypes table. */
int i;
#ifndef DFTABLES
-yield = (pcre_malloc)(tables_length);
+yield = (unsigned char*)(pcre_malloc)(tables_length);
#else
-yield = malloc(tables_length);
+yield = (unsigned char*)malloc(tables_length);
#endif
if (yield == NULL) return NULL;
.br
.B int pcre_exec(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"
.ti +5n
-.B "const char *\fIsubject\fR," int \fIlength\fR, int \fIoptions\fR,
+.B "const char *\fIsubject\fR," int \fIlength\fR, int \fIstartoffset\fR,
.ti +5n
-.B int *\fIovector\fR, int \fIovecsize\fR);
+.B int \fIoptions\fR, int *\fIovector\fR, int \fIovecsize\fR);
.PP
.br
.B int pcre_copy_substring(const char *\fIsubject\fR, int *\fIovector\fR,
pattern matching using the same syntax and semantics as Perl 5, with just a few
differences (see below). The current implementation corresponds to Perl 5.005.
-PCRE has its own native API, which is described in this man page. There is also
-a set of wrapper functions that correspond to the POSIX API. See
-\fBpcreposix (3)\fR.
+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 API. These are
+described in the \fBpcreposix\fR documentation.
+
+The native API function prototypes are defined in the header file \fBpcre.h\fR,
+and on Unix systems the library itself is called \fBlibpcre.a\fR, so can be
+accessed by adding \fB-lpcre\fR to the command for linking an application which
+calls it.
The functions \fBpcre_compile()\fR, \fBpcre_study()\fR, and \fBpcre_exec()\fR
are used for compiling and matching regular expressions, while
An alternative set of tables can, however, be supplied. Such tables are built
by calling the \fBpcre_maketables()\fR function, which has no arguments, in the
-relevant locale. The result can then be passed to \fBpcre_compile()\ as often
+relevant locale. The result can then be passed to \fBpcre_compile()\fR as often
as necessary. For example, to build and use tables that are appropriate for the
French locale (where accented characters with codes greater than 128 are
treated as letters), the following code could be used:
The tables are built in memory that is obtained via \fBpcre_malloc\fR. The
pointer that is passed to \fBpcre_compile\fR is saved with the compiled
pattern, and the same tables are used via this pointer by \fBpcre_study()\fR
-and \fBpcre_match()\fR. Thus for any single pattern, compilation, studying and
+and \fBpcre_exec()\fR. Thus for any single pattern, compilation, studying and
matching all happen in the same locale, but different patterns can be compiled
in different locales. It is the caller's responsibility to ensure that the
memory containing the tables remains available for as long as it is needed.
(cat|cow|coyote), then it is returned in the integer pointed to by
\fIfirstcharptr\fR. Otherwise, if either
- (a) the pattern was compiled with the PCRE_MULTILINE option, and every branch
- starts with "^", or
+(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),
+(b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set
+(if it were set, the pattern would be anchored),
then -1 is returned, indicating that the pattern matches only at the
start of a subject string or after any "\\n" within the string. Otherwise -2 is
pattern has been studied, the result of the study should be passed in the
\fIextra\fR argument. Otherwise this must be NULL.
-The subject string is passed as a pointer in \fIsubject\fR and a length in
-\fIlength\fR. Unlike the pattern string, it may contain binary zero characters.
-
The PCRE_ANCHORED option can be passed in the \fIoptions\fR argument, whose
unused bits must be zero. However, if a pattern was compiled with
PCRE_ANCHORED, or turned out to be anchored by virtue of its contents, it
cannot be made unachored at matching time.
-There are also two further options that can be set only at matching time:
+There are also three further options that can be set only at matching time:
PCRE_NOTBOL
it. Setting this without PCRE_MULTILINE (at compile time) causes dollar never
to match.
+ PCRE_NOTEMPTY
+
+An empty string is not considered to be a valid match if this option is set. If
+there are alternatives in the pattern, they are tried. If all the alternatives
+match the empty string, the entire match fails. For example, if the pattern
+
+ a?b?
+
+is applied to a string not beginning with "a" or "b", it matches the empty
+string at the start of the subject. With PCRE_NOTEMPTY set, this match is not
+valid, so PCRE searches further into the string for occurrences of "a" or "b".
+Perl has no direct equivalent of this option, but it makes a special case of
+a pattern match of the empty string within its \fBsplit()\fR function, or when
+using the /g modifier. Using PCRE_NOTEMPTY it is possible to emulate this
+behaviour.
+
+The subject string is passed as a pointer in \fIsubject\fR, a length in
+\fIlength\fR, and a starting offset in \fIstartoffset\fR. Unlike the pattern
+string, it may contain binary zero characters. When the starting offset is
+zero, the search for a match starts at the beginning of the subject, and this
+is by far the most common case.
+
+A non-zero starting offset is useful when searching for another match in the
+same subject by calling \fBpcre_exec()\fR again after a previous success.
+Setting \fIstartoffset\fR differs from just passing over a shortened string and
+setting PCRE_NOTBOL in the case of a pattern that begins with any kind of
+lookbehind. For example, consider the pattern
+
+ \\Biss\\B
+
+which finds occurrences of "iss" in the middle of words. (\\B matches only if
+the current position in the subject is not a word boundary.) When applied to
+the string "Mississipi" the first call to \fBpcre_exec()\fR finds the first
+occurrence. If \fBpcre_exec()\fR is called again with just the remainder of the
+subject, namely "issipi", it does not match, because \\B is always false at the
+start of the subject, which is deemed to be a word boundary. However, if
+\fBpcre_exec()\fR is passed the entire string again, but with \fIstartoffset\fR
+set to 4, it finds the second occurrence of "iss" because it is able to look
+behind the starting point to discover that it is preceded by a letter.
+
+If a non-zero starting offset is passed when the pattern is anchored, one
+attempt to match at the given offset is tried. This can only succeed if the
+pattern does not require the match to be at the start of the subject.
+
In general, a pattern matches a certain portion of the subject, and in
addition, further substrings from the subject may be picked out by parts of the
pattern. Following the usage in Jeffrey Friedl's book, this is called
inverted, that is, by default they are not greedy, but if followed by a
question mark they are.
+(e) PCRE_ANCHORED can be used to force a pattern to be tried only at the start
+of the subject.
+
+(f) The PCRE_NOTBOL, PCRE_NOTEOL, and PCRE_NOTEMPTY options for
+\fBpcre_exec()\fR have no Perl equivalents.
+
.SH REGULAR EXPRESSION DETAILS
The syntax and semantics of the regular expressions supported by PCRE are
The \\A, \\Z, and \\z assertions differ from the traditional circumflex and
dollar (described below) in that they only ever match at the very start and end
of the subject string, whatever options are set. They are not affected by the
-PCRE_NOTBOL or PCRE_NOTEOL options. 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.
+PCRE_NOTBOL or PCRE_NOTEOL options. If the \fIstartoffset\fR argument of
+\fBpcre_exec()\fR is non-zero, \\A can never match. The difference between \\Z
+and \\z is that \\Z matches before a newline that is the last character of the
+string as well as at the end of the string, whereas \\z matches only at the
+end.
.SH CIRCUMFLEX AND DOLLAR
Outside a character class, in the default matching mode, the circumflex
character is an assertion which is true only if the current matching point is
-at the start of the subject string. Inside a character class, circumflex has an
-entirely different meaning (see below).
+at the start of the subject string. If the \fIstartoffset\fR argument of
+\fBpcre_exec()\fR is non-zero, circumflex can never match. Inside a character
+class, circumflex has an entirely different meaning (see below).
Circumflex need not be the first character of the pattern if a number of
alternatives are involved, but it should be the first thing in each alternative
addition to matching at the start and end of the subject string. For example,
the pattern /^abc$/ matches the subject string "def\\nabc" in multiline mode,
but not otherwise. Consequently, patterns that are anchored in single line mode
-because all branches start with "^" are not anchored in multiline mode. The
-PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is set.
+because all branches start with "^" are not anchored in multiline mode, and a
+match for circumflex is possible when the \fIstartoffset\fR argument of
+\fBpcre_exec()\fR is non-zero. The PCRE_DOLLAR_ENDONLY option is ignored if
+PCRE_MULTILINE is set.
Note that the sequences \\A, \\Z, and \\z can be used to match the start and
end of the subject in both modes, and if all branches of a pattern start with
(?<=\\d{3})(?<!999)foo
-matches "foo" preceded by three digits that are not "999". Furthermore,
-assertions can be nested in any combination. For example,
+matches "foo" preceded by three digits that are not "999". Notice that each of
+the assertions is applied independently at the same point in the subject
+string. First there is a check that the previous three characters are all
+digits, then there is a check that the same three characters are not "999".
+This pattern does \fInot\fR match "foo" preceded by six characters, the first
+of which are digits and the last three of which are not "999". For example, it
+doesn't match "123abcfoo". A pattern to do that is
+
+ (?<=\\d{3}...)(?<!999)foo
+
+This time the first assertion looks at the preceding six characters, checking
+that the first three are digits, and then the second assertion checks that the
+preceding three characters are not "999".
+
+Assertions can be nested in any combination. For example,
(?<=(?<!foo)bar)baz
matches an occurrence of "baz" that is preceded by "bar" which in turn is not
-preceded by "foo".
+preceded by "foo", while
+
+ (?<=\\d{3}(?!999)...)foo
+
+is another pattern which matches "foo" preceded by three digits and any three
+characters that are not "999".
Assertion subpatterns are not capturing subpatterns, and may not be repeated,
-because it makes no sense to assert the same thing several times. If an
-assertion contains capturing subpatterns within it, these are always counted
-for the purposes of numbering the capturing subpatterns in the whole pattern.
-Substring capturing is carried out for positive assertions, but it does not
-make sense for negative assertions.
+because it makes no sense to assert the same thing several times. If any kind
+of assertion contains capturing subpatterns within it, these are counted for
+the purposes of numbering the capturing subpatterns in the whole pattern.
+However, substring capturing is carried out only for positive assertions,
+because it does not make sense for negative assertions.
Assertions count towards the maximum of 200 parenthesized subpatterns.
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
+ (.*) second
matches the subject "first\\nand second" (where \\n stands for a newline
character) with the first captured substring being "and". In order to do this,
the pattern with ^.* to indicate explicit anchoring. That saves PCRE from
having to scan along the subject looking for a newline to restart at.
+Beware of patterns that contain nested indefinite repeats. These can take a
+long time to run when applied to a string that does not match. Consider the
+pattern fragment
+
+ (a+)*
+
+This can match "aaaa" in 33 different ways, and this number increases very
+rapidly as the string gets longer. (The * repeat can match 0, 1, 2, 3, or 4
+times, and for each of those cases other than 0, the + repeats can match
+different numbers of times.) When the remainder of the pattern is such that the
+entire match is going to fail, PCRE has in principle to try every possible
+variation, and this can take an extremely long time.
+
+An optimization catches some of the more simple cases such as
+
+ (a+)*b
+
+where a literal character follows. Before embarking on the standard matching
+procedure, PCRE checks that there is a "b" later in the subject string, and if
+there is not, it fails the match immediately. However, when there is no
+following literal this optimization cannot be used. You can see the difference
+by comparing the behaviour of
+
+ (a+)*\\d
+
+with the pattern above. The former gives a failure almost instantly when
+applied to a whole line of "a" characters, whereas the latter takes an
+appreciable time with strings longer than about 20 characters.
+
.SH AUTHOR
Philip Hazel <ph10@cam.ac.uk>
.br
.br
Phone: +44 1223 334714
+Last updated: 29 July 1999
+.br
Copyright (c) 1997-1999 University of Cambridge.
--- /dev/null
+<HTML>
+<HEAD>
+<TITLE>pcre specification</TITLE>
+</HEAD>
+<body bgcolor="#FFFFFF" text="#00005A">
+<H1>pcre specification</H1>
+This HTML document has been generated automatically from the original man page.
+If there is any nonsense in it, please consult the man page in case the
+conversion went wrong.
+<UL>
+<LI><A NAME="TOC1" HREF="#SEC1">NAME</A>
+<LI><A NAME="TOC2" HREF="#SEC2">SYNOPSIS</A>
+<LI><A NAME="TOC3" HREF="#SEC3">DESCRIPTION</A>
+<LI><A NAME="TOC4" HREF="#SEC4">MULTI-THREADING</A>
+<LI><A NAME="TOC5" HREF="#SEC5">COMPILING A PATTERN</A>
+<LI><A NAME="TOC6" HREF="#SEC6">STUDYING A PATTERN</A>
+<LI><A NAME="TOC7" HREF="#SEC7">LOCALE SUPPORT</A>
+<LI><A NAME="TOC8" HREF="#SEC8">INFORMATION ABOUT A PATTERN</A>
+<LI><A NAME="TOC9" HREF="#SEC9">MATCHING A PATTERN</A>
+<LI><A NAME="TOC10" HREF="#SEC10">EXTRACTING CAPTURED SUBSTRINGS</A>
+<LI><A NAME="TOC11" HREF="#SEC11">LIMITATIONS</A>
+<LI><A NAME="TOC12" HREF="#SEC12">DIFFERENCES FROM PERL</A>
+<LI><A NAME="TOC13" HREF="#SEC13">REGULAR EXPRESSION DETAILS</A>
+<LI><A NAME="TOC14" HREF="#SEC14">BACKSLASH</A>
+<LI><A NAME="TOC15" HREF="#SEC15">CIRCUMFLEX AND DOLLAR</A>
+<LI><A NAME="TOC16" HREF="#SEC16">FULL STOP (PERIOD, DOT)</A>
+<LI><A NAME="TOC17" HREF="#SEC17">SQUARE BRACKETS</A>
+<LI><A NAME="TOC18" HREF="#SEC18">VERTICAL BAR</A>
+<LI><A NAME="TOC19" HREF="#SEC19">INTERNAL OPTION SETTING</A>
+<LI><A NAME="TOC20" HREF="#SEC20">SUBPATTERNS</A>
+<LI><A NAME="TOC21" HREF="#SEC21">REPETITION</A>
+<LI><A NAME="TOC22" HREF="#SEC22">BACK REFERENCES</A>
+<LI><A NAME="TOC23" HREF="#SEC23">ASSERTIONS</A>
+<LI><A NAME="TOC24" HREF="#SEC24">ONCE-ONLY SUBPATTERNS</A>
+<LI><A NAME="TOC25" HREF="#SEC25">CONDITIONAL SUBPATTERNS</A>
+<LI><A NAME="TOC26" HREF="#SEC26">COMMENTS</A>
+<LI><A NAME="TOC27" HREF="#SEC27">PERFORMANCE</A>
+<LI><A NAME="TOC28" HREF="#SEC28">AUTHOR</A>
+</UL>
+<LI><A NAME="SEC1" HREF="#TOC1">NAME</A>
+<P>
+pcre - Perl-compatible regular expressions.
+</P>
+<LI><A NAME="SEC2" HREF="#TOC1">SYNOPSIS</A>
+<P>
+<B>#include <pcre.h></B>
+</P>
+<P>
+<B>pcre *pcre_compile(const char *<I>pattern</I>, int <I>options</I>,</B>
+<B>const char **<I>errptr</I>, int *<I>erroffset</I>,</B>
+<B>const unsigned char *<I>tableptr</I>);</B>
+</P>
+<P>
+<B>pcre_extra *pcre_study(const pcre *<I>code</I>, int <I>options</I>,</B>
+<B>const char **<I>errptr</I>);</B>
+</P>
+<P>
+<B>int pcre_exec(const pcre *<I>code</I>, const pcre_extra *<I>extra</I>,</B>
+<B>const char *<I>subject</I>, int <I>length</I>, int <I>startoffset</I>,</B>
+<B>int <I>options</I>, int *<I>ovector</I>, int <I>ovecsize</I>);</B>
+</P>
+<P>
+<B>int pcre_copy_substring(const char *<I>subject</I>, int *<I>ovector</I>,</B>
+<B>int <I>stringcount</I>, int <I>stringnumber</I>, char *<I>buffer</I>,</B>
+<B>int <I>buffersize</I>);</B>
+</P>
+<P>
+<B>int pcre_get_substring(const char *<I>subject</I>, int *<I>ovector</I>,</B>
+<B>int <I>stringcount</I>, int <I>stringnumber</I>,</B>
+<B>const char **<I>stringptr</I>);</B>
+</P>
+<P>
+<B>int pcre_get_substring_list(const char *<I>subject</I>,</B>
+<B>int *<I>ovector</I>, int <I>stringcount</I>, const char ***<I>listptr</I>);</B>
+</P>
+<P>
+<B>const unsigned char *pcre_maketables(void);</B>
+</P>
+<P>
+<B>int pcre_info(const pcre *<I>code</I>, int *<I>optptr</I>, int</B>
+<B>*<I>firstcharptr</I>);</B>
+</P>
+<P>
+<B>char *pcre_version(void);</B>
+</P>
+<P>
+<B>void *(*pcre_malloc)(size_t);</B>
+</P>
+<P>
+<B>void (*pcre_free)(void *);</B>
+</P>
+<LI><A NAME="SEC3" HREF="#TOC1">DESCRIPTION</A>
+<P>
+The PCRE library is a set of functions that implement regular expression
+pattern matching using the same syntax and semantics as Perl 5, with just a few
+differences (see below). The current implementation corresponds to Perl 5.005.
+</P>
+<P>
+PCRE has its own native API, which is described in this document. There is also
+a set of wrapper functions that correspond to the POSIX API. These are
+described in the <B>pcreposix</B> documentation.
+</P>
+<P>
+The native API function prototypes are defined in the header file <B>pcre.h</B>,
+and on Unix systems the library itself is called <B>libpcre.a</B>, so can be
+accessed by adding <B>-lpcre</B> to the command for linking an application which
+calls it.
+</P>
+<P>
+The functions <B>pcre_compile()</B>, <B>pcre_study()</B>, and <B>pcre_exec()</B>
+are used for compiling and matching regular expressions, while
+<B>pcre_copy_substring()</B>, <B>pcre_get_substring()</B>, and
+<B>pcre_get_substring_list()</B> are convenience functions for extracting
+captured substrings from a matched subject string. The function
+<B>pcre_maketables()</B> is used (optionally) to build a set of character tables
+in the current locale for passing to <B>pcre_compile()</B>.
+</P>
+<P>
+The function <B>pcre_info()</B> is used to find out information about a compiled
+pattern, while the function <B>pcre_version()</B> returns a pointer to a string
+containing the version of PCRE and its date of release.
+</P>
+<P>
+The global variables <B>pcre_malloc</B> and <B>pcre_free</B> initially contain
+the entry points of the standard <B>malloc()</B> and <B>free()</B> functions
+respectively. PCRE calls the memory management functions via these variables,
+so a calling program can replace them if it wishes to intercept the calls. This
+should be done before calling any PCRE functions.
+</P>
+<LI><A NAME="SEC4" HREF="#TOC1">MULTI-THREADING</A>
+<P>
+The PCRE functions can be used in multi-threading applications, with the
+proviso that the memory management functions pointed to by <B>pcre_malloc</B>
+and <B>pcre_free</B> are shared by all threads.
+</P>
+<P>
+The compiled form of a regular expression is not altered during matching, so
+the same compiled pattern can safely be used by several threads at once.
+</P>
+<LI><A NAME="SEC5" HREF="#TOC1">COMPILING A PATTERN</A>
+<P>
+The function <B>pcre_compile()</B> is called to compile a pattern into an
+internal form. The pattern is a C string terminated by a binary zero, and
+is passed in the argument <I>pattern</I>. A pointer to a single block of memory
+that is obtained via <B>pcre_malloc</B> is returned. This contains the
+compiled code and related data. The <B>pcre</B> type is defined for this for
+convenience, but in fact <B>pcre</B> is just a typedef for <B>void</B>, since the
+contents of the block are not externally defined. It is up to the caller to
+free the memory when it is no longer required.
+</P>
+<P>
+The size of a compiled pattern is roughly proportional to the length of the
+pattern string, except that each character class (other than those containing
+just a single character, negated or not) requires 33 bytes, and repeat
+quantifiers with a minimum greater than one or a bounded maximum cause the
+relevant portions of the compiled pattern to be replicated.
+</P>
+<P>
+The <I>options</I> argument contains independent bits that affect the
+compilation. It should be zero if no options are required. Some of the options,
+in particular, those that are compatible with Perl, can also be set and unset
+from within the pattern (see the detailed description of regular expressions
+below). For these options, the contents of the <I>options</I> argument specifies
+their initial settings at the start of compilation and execution. The
+PCRE_ANCHORED option can be set at the time of matching as well as at compile
+time.
+</P>
+<P>
+If <I>errptr</I> is NULL, <B>pcre_compile()</B> returns NULL immediately.
+Otherwise, if compilation of a pattern fails, <B>pcre_compile()</B> returns
+NULL, and sets the variable pointed to by <I>errptr</I> to point to a textual
+error message. The offset from the start of the pattern to the character where
+the error was discovered is placed in the variable pointed to by
+<I>erroffset</I>, which must not be NULL. If it is, an immediate error is given.
+</P>
+<P>
+If the final argument, <I>tableptr</I>, is NULL, PCRE uses a default set of
+character tables which are built when it is compiled, using the default C
+locale. Otherwise, <I>tableptr</I> must be the result of a call to
+<B>pcre_maketables()</B>. See the section on locale support below.
+</P>
+<P>
+The following option bits are defined in the header file:
+</P>
+<P>
+<PRE>
+ PCRE_ANCHORED
+</PRE>
+</P>
+<P>
+If this bit is set, the pattern is forced to be "anchored", that is, it is
+constrained to match only at the start of the string which is being searched
+(the "subject string"). This effect can also be achieved by appropriate
+constructs in the pattern itself, which is the only way to do it in Perl.
+</P>
+<P>
+<PRE>
+ PCRE_CASELESS
+</PRE>
+</P>
+<P>
+If this bit is set, letters in the pattern match both upper and lower case
+letters. It is equivalent to Perl's /i option.
+</P>
+<P>
+<PRE>
+ PCRE_DOLLAR_ENDONLY
+</PRE>
+</P>
+<P>
+If this bit is set, a dollar metacharacter in the pattern matches only at the
+end of the subject string. Without this option, a dollar also matches
+immediately before the final character if it is a newline (but not before any
+other newlines). The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is
+set. There is no equivalent to this option in Perl.
+</P>
+<P>
+<PRE>
+ PCRE_DOTALL
+</PRE>
+</P>
+<P>
+If this bit is set, a dot metacharater in the pattern matches all characters,
+including newlines. Without it, newlines are excluded. This option is
+equivalent to Perl's /s option. A negative class such as [^a] always matches a
+newline character, independent of the setting of this option.
+</P>
+<P>
+<PRE>
+ PCRE_EXTENDED
+</PRE>
+</P>
+<P>
+If this bit is set, whitespace data characters in the pattern are totally
+ignored except when escaped or inside a character class, and characters between
+an unescaped # outside a character class and the next newline character,
+inclusive, are also ignored. This is equivalent to Perl's /x option, and makes
+it possible to include comments inside complicated patterns. Note, however,
+that this applies only to data characters. Whitespace characters may never
+appear within special character sequences in a pattern, for example within the
+sequence (?( which introduces a conditional subpattern.
+</P>
+<P>
+<PRE>
+ PCRE_EXTRA
+</PRE>
+</P>
+<P>
+This option turns on additional functionality of PCRE that is incompatible with
+Perl. 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.
+</P>
+<P>
+<PRE>
+ PCRE_MULTILINE
+</PRE>
+</P>
+<P>
+By default, PCRE treats the subject string as consisting of a single "line" of
+characters (even if it actually contains several newlines). The "start of line"
+metacharacter (^) matches only at the start of the string, while the "end of
+line" metacharacter ($) matches only at the end of the string, or before a
+terminating newline (unless PCRE_DOLLAR_ENDONLY is set). This is the same as
+Perl.
+</P>
+<P>
+When PCRE_MULTILINE it is set, the "start of line" and "end of line" constructs
+match immediately following or immediately before any newline in the subject
+string, respectively, as well as at the very start and end. This is equivalent
+to Perl's /m option. If there are no "\n" characters in a subject string, or
+no occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no
+effect.
+</P>
+<P>
+<PRE>
+ PCRE_UNGREEDY
+</PRE>
+</P>
+<P>
+This option inverts the "greediness" of the quantifiers so that they are not
+greedy by default, but become greedy if followed by "?". It is not compatible
+with Perl. It can also be set by a (?U) option setting within the pattern.
+</P>
+<LI><A NAME="SEC6" HREF="#TOC1">STUDYING A PATTERN</A>
+<P>
+When a pattern is going to be used several times, it is worth spending more
+time analyzing it in order to speed up the time taken for matching. The
+function <B>pcre_study()</B> takes a pointer to a compiled pattern as its first
+argument, and returns a pointer to a <B>pcre_extra</B> block (another <B>void</B>
+typedef) containing additional information about the pattern; this can be
+passed to <B>pcre_exec()</B>. If no additional information is available, NULL
+is returned.
+</P>
+<P>
+The second argument contains option bits. At present, no options are defined
+for <B>pcre_study()</B>, and this argument should always be zero.
+</P>
+<P>
+The third argument for <B>pcre_study()</B> is a pointer to an error message. If
+studying succeeds (even if no data is returned), the variable it points to is
+set to NULL. Otherwise it points to a textual error message.
+</P>
+<P>
+At present, studying a pattern is useful only for non-anchored patterns that do
+not have a single fixed starting character. A bitmap of possible starting
+characters is created.
+</P>
+<LI><A NAME="SEC7" HREF="#TOC1">LOCALE SUPPORT</A>
+<P>
+PCRE handles caseless matching, and determines whether characters are letters,
+digits, or whatever, by reference to a set of tables. The library contains a
+default set of tables which is created in the default C locale when PCRE is
+compiled. This is used when the final argument of <B>pcre_compile()</B> is NULL,
+and is sufficient for many applications.
+</P>
+<P>
+An alternative set of tables can, however, be supplied. Such tables are built
+by calling the <B>pcre_maketables()</B> function, which has no arguments, in the
+relevant locale. The result can then be passed to <B>pcre_compile()</B> as often
+as necessary. For example, to build and use tables that are appropriate for the
+French locale (where accented characters with codes greater than 128 are
+treated as letters), the following code could be used:
+</P>
+<P>
+<PRE>
+ setlocale(LC_CTYPE, "fr");
+ tables = pcre_maketables();
+ re = pcre_compile(..., tables);
+</PRE>
+</P>
+<P>
+The tables are built in memory that is obtained via <B>pcre_malloc</B>. The
+pointer that is passed to <B>pcre_compile</B> is saved with the compiled
+pattern, and the same tables are used via this pointer by <B>pcre_study()</B>
+and <B>pcre_exec()</B>. Thus for any single pattern, compilation, studying and
+matching all happen in the same locale, but different patterns can be compiled
+in different locales. It is the caller's responsibility to ensure that the
+memory containing the tables remains available for as long as it is needed.
+</P>
+<LI><A NAME="SEC8" HREF="#TOC1">INFORMATION ABOUT A PATTERN</A>
+<P>
+The <B>pcre_info()</B> function returns information about a compiled pattern.
+Its yield is the number of capturing subpatterns, or one of the following
+negative numbers:
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_NULL the argument <I>code</I> was NULL
+ PCRE_ERROR_BADMAGIC the "magic number" was not found
+</PRE>
+</P>
+<P>
+If the <I>optptr</I> argument is not NULL, a copy of the options with which the
+pattern was compiled is placed in the integer it points to. These option bits
+are those specified in the call to <B>pcre_compile()</B>, modified by any
+top-level option settings within the pattern itself, and with the PCRE_ANCHORED
+bit set if the form of the pattern implies that it can match only at the start
+of a subject string.
+</P>
+<P>
+If the pattern is not anchored and the <I>firstcharptr</I> argument is not NULL,
+it is used to pass back information about the first character of any matched
+string. If there is a fixed first character, e.g. from a pattern such as
+(cat|cow|coyote), then it is returned in the integer pointed to by
+<I>firstcharptr</I>. Otherwise, if either
+</P>
+<P>
+(a) the pattern was compiled with the PCRE_MULTILINE option, and every branch
+starts with "^", or
+</P>
+<P>
+(b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set
+(if it were set, the pattern would be anchored),
+</P>
+<P>
+then -1 is returned, indicating that the pattern matches only at the
+start of a subject string or after any "\n" within the string. Otherwise -2 is
+returned.
+</P>
+<LI><A NAME="SEC9" HREF="#TOC1">MATCHING A PATTERN</A>
+<P>
+The function <B>pcre_exec()</B> is called to match a subject string against a
+pre-compiled pattern, which is passed in the <I>code</I> argument. If the
+pattern has been studied, the result of the study should be passed in the
+<I>extra</I> argument. Otherwise this must be NULL.
+</P>
+<P>
+The PCRE_ANCHORED option can be passed in the <I>options</I> argument, whose
+unused bits must be zero. However, if a pattern was compiled with
+PCRE_ANCHORED, or turned out to be anchored by virtue of its contents, it
+cannot be made unachored at matching time.
+</P>
+<P>
+There are also three further options that can be set only at matching time:
+</P>
+<P>
+<PRE>
+ PCRE_NOTBOL
+</PRE>
+</P>
+<P>
+The first character of the string is not the beginning of a line, so the
+circumflex metacharacter should not match before it. Setting this without
+PCRE_MULTILINE (at compile time) causes circumflex never to match.
+</P>
+<P>
+<PRE>
+ PCRE_NOTEOL
+</PRE>
+</P>
+<P>
+The end of the string is not the end of a line, so the dollar metacharacter
+should not match it nor (except in multiline mode) a newline immediately before
+it. Setting this without PCRE_MULTILINE (at compile time) causes dollar never
+to match.
+</P>
+<P>
+<PRE>
+ PCRE_NOTEMPTY
+</PRE>
+</P>
+<P>
+An empty string is not considered to be a valid match if this option is set. If
+there are alternatives in the pattern, they are tried. If all the alternatives
+match the empty string, the entire match fails. For example, if the pattern
+</P>
+<P>
+<PRE>
+ a?b?
+</PRE>
+</P>
+<P>
+is applied to a string not beginning with "a" or "b", it matches the empty
+string at the start of the subject. With PCRE_NOTEMPTY set, this match is not
+valid, so PCRE searches further into the string for occurrences of "a" or "b".
+Perl has no direct equivalent of this option, but it makes a special case of
+a pattern match of the empty string within its <B>split()</B> function, or when
+using the /g modifier. Using PCRE_NOTEMPTY it is possible to emulate this
+behaviour.
+</P>
+<P>
+The subject string is passed as a pointer in <I>subject</I>, a length in
+<I>length</I>, and a starting offset in <I>startoffset</I>. Unlike the pattern
+string, it may contain binary zero characters. When the starting offset is
+zero, the search for a match starts at the beginning of the subject, and this
+is by far the most common case.
+</P>
+<P>
+A non-zero starting offset is useful when searching for another match in the
+same subject by calling <B>pcre_exec()</B> again after a previous success.
+Setting <I>startoffset</I> differs from just passing over a shortened string and
+setting PCRE_NOTBOL in the case of a pattern that begins with any kind of
+lookbehind. For example, consider the pattern
+</P>
+<P>
+<PRE>
+ \Biss\B
+</PRE>
+</P>
+<P>
+which finds occurrences of "iss" in the middle of words. (\B matches only if
+the current position in the subject is not a word boundary.) When applied to
+the string "Mississipi" the first call to <B>pcre_exec()</B> finds the first
+occurrence. If <B>pcre_exec()</B> is called again with just the remainder of the
+subject, namely "issipi", it does not match, because \B is always false at the
+start of the subject, which is deemed to be a word boundary. However, if
+<B>pcre_exec()</B> is passed the entire string again, but with <I>startoffset</I>
+set to 4, it finds the second occurrence of "iss" because it is able to look
+behind the starting point to discover that it is preceded by a letter.
+</P>
+<P>
+If a non-zero starting offset is passed when the pattern is anchored, one
+attempt to match at the given offset is tried. This can only succeed if the
+pattern does not require the match to be at the start of the subject.
+</P>
+<P>
+In general, a pattern matches a certain portion of the subject, and in
+addition, further substrings from the subject may be picked out by parts of the
+pattern. Following the usage in Jeffrey Friedl's book, this is called
+"capturing" in what follows, and the phrase "capturing subpattern" is used for
+a fragment of a pattern that picks out a substring. PCRE supports several other
+kinds of parenthesized subpattern that do not cause substrings to be captured.
+</P>
+<P>
+Captured substrings are returned to the caller via a vector of integer offsets
+whose address is passed in <I>ovector</I>. The number of elements in the vector
+is passed in <I>ovecsize</I>. The first two-thirds of the vector is used to pass
+back captured substrings, each substring using a pair of integers. The
+remaining third of the vector is used as workspace by <B>pcre_exec()</B> while
+matching capturing subpatterns, and is not available for passing back
+information. The length passed in <I>ovecsize</I> should always be a multiple of
+three. If it is not, it is rounded down.
+</P>
+<P>
+When a match has been successful, information about captured substrings is
+returned in pairs of integers, starting at the beginning of <I>ovector</I>, and
+continuing up to two-thirds of its length at the most. The first element of a
+pair is set to the offset of the first character in a substring, and the second
+is set to the offset of the first character after the end of a substring. The
+first pair, <I>ovector[0]</I> and <I>ovector[1]</I>, identify the portion of the
+subject string matched by the entire pattern. The next pair is used for the
+first capturing subpattern, and so on. The value returned by <B>pcre_exec()</B>
+is the number of pairs that have been set. If there are no capturing
+subpatterns, the return value from a successful match is 1, indicating that
+just the first pair of offsets has been set.
+</P>
+<P>
+Some convenience functions are provided for extracting the captured substrings
+as separate strings. These are described in the following section.
+</P>
+<P>
+It is possible for an capturing subpattern number <I>n+1</I> to match some
+part of the subject when subpattern <I>n</I> has not been used at all. For
+example, if the string "abc" is matched against the pattern (a|(z))(bc)
+subpatterns 1 and 3 are matched, but 2 is not. When this happens, both offset
+values corresponding to the unused subpattern are set to -1.
+</P>
+<P>
+If a capturing subpattern is matched repeatedly, it is the last portion of the
+string that it matched that gets returned.
+</P>
+<P>
+If the vector is too small to hold all the captured substrings, it is used as
+far as possible (up to two-thirds of its length), and the function returns a
+value of zero. In particular, if the substring offsets are not of interest,
+<B>pcre_exec()</B> may be called with <I>ovector</I> passed as NULL and
+<I>ovecsize</I> as zero. However, if the pattern contains back references and
+the <I>ovector</I> isn't big enough to remember the related substrings, PCRE has
+to get additional memory for use during matching. Thus it is usually advisable
+to supply an <I>ovector</I>.
+</P>
+<P>
+Note that <B>pcre_info()</B> can be used to find out how many capturing
+subpatterns there are in a compiled pattern. The smallest size for
+<I>ovector</I> that will allow for <I>n</I> captured substrings in addition to
+the offsets of the substring matched by the whole pattern is (<I>n</I>+1)*3.
+</P>
+<P>
+If <B>pcre_exec()</B> fails, it returns a negative number. The following are
+defined in the header file:
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_NOMATCH (-1)
+</PRE>
+</P>
+<P>
+The subject string did not match the pattern.
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_NULL (-2)
+</PRE>
+</P>
+<P>
+Either <I>code</I> or <I>subject</I> was passed as NULL, or <I>ovector</I> was
+NULL and <I>ovecsize</I> was not zero.
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_BADOPTION (-3)
+</PRE>
+</P>
+<P>
+An unrecognized bit was set in the <I>options</I> argument.
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_BADMAGIC (-4)
+</PRE>
+</P>
+<P>
+PCRE stores a 4-byte "magic number" at the start of the compiled code, to catch
+the case when it is passed a junk pointer. This is the error it gives when the
+magic number isn't present.
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_UNKNOWN_NODE (-5)
+</PRE>
+</P>
+<P>
+While running the pattern match, an unknown item was encountered in the
+compiled pattern. This error could be caused by a bug in PCRE or by overwriting
+of the compiled pattern.
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_NOMEMORY (-6)
+</PRE>
+</P>
+<P>
+If a pattern contains back references, but the <I>ovector</I> that is passed to
+<B>pcre_exec()</B> is not big enough to remember the referenced substrings, PCRE
+gets a block of memory at the start of matching to use for this purpose. If the
+call via <B>pcre_malloc()</B> fails, this error is given. The memory is freed at
+the end of matching.
+</P>
+<LI><A NAME="SEC10" HREF="#TOC1">EXTRACTING CAPTURED SUBSTRINGS</A>
+<P>
+Captured substrings can be accessed directly by using the offsets returned by
+<B>pcre_exec()</B> in <I>ovector</I>. For convenience, the functions
+<B>pcre_copy_substring()</B>, <B>pcre_get_substring()</B>, and
+<B>pcre_get_substring_list()</B> are provided for extracting captured substrings
+as new, separate, zero-terminated strings. A substring that contains a binary
+zero is correctly extracted and has a further zero added on the end, but the
+result does not, of course, function as a C string.
+</P>
+<P>
+The first three arguments are the same for all three functions: <I>subject</I>
+is the subject string which has just been successfully matched, <I>ovector</I>
+is a pointer to the vector of integer offsets that was passed to
+<B>pcre_exec()</B>, and <I>stringcount</I> is the number of substrings that
+were captured by the match, including the substring that matched the entire
+regular expression. This is the value returned by <B>pcre_exec</B> if it
+is greater than zero. If <B>pcre_exec()</B> returned zero, indicating that it
+ran out of space in <I>ovector</I>, then the value passed as
+<I>stringcount</I> should be the size of the vector divided by three.
+</P>
+<P>
+The functions <B>pcre_copy_substring()</B> and <B>pcre_get_substring()</B>
+extract a single substring, whose number is given as <I>stringnumber</I>. A
+value of zero extracts the substring that matched the entire pattern, while
+higher values extract the captured substrings. For <B>pcre_copy_substring()</B>,
+the string is placed in <I>buffer</I>, whose length is given by
+<I>buffersize</I>, while for <B>pcre_get_substring()</B> a new block of store is
+obtained via <B>pcre_malloc</B>, and its address is returned via
+<I>stringptr</I>. The yield of the function is the length of the string, not
+including the terminating zero, or one of
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_NOMEMORY (-6)
+</PRE>
+</P>
+<P>
+The buffer was too small for <B>pcre_copy_substring()</B>, or the attempt to get
+memory failed for <B>pcre_get_substring()</B>.
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_NOSUBSTRING (-7)
+</PRE>
+</P>
+<P>
+There is no substring whose number is <I>stringnumber</I>.
+</P>
+<P>
+The <B>pcre_get_substring_list()</B> function extracts all available substrings
+and builds a list of pointers to them. All this is done in a single block of
+memory which is obtained via <B>pcre_malloc</B>. The address of the memory block
+is returned via <I>listptr</I>, which is also the start of the list of string
+pointers. The end of the list is marked by a NULL pointer. The yield of the
+function is zero if all went well, or
+</P>
+<P>
+<PRE>
+ PCRE_ERROR_NOMEMORY (-6)
+</PRE>
+</P>
+<P>
+if the attempt to get the memory block failed.
+</P>
+<P>
+When any of these functions encounter a substring that is unset, which can
+happen when capturing subpattern number <I>n+1</I> matches some part of the
+subject, but subpattern <I>n</I> has not been used at all, they return an empty
+string. This can be distinguished from a genuine zero-length substring by
+inspecting the appropriate offset in <I>ovector</I>, which is negative for unset
+substrings.
+</P>
+<LI><A NAME="SEC11" HREF="#TOC1">LIMITATIONS</A>
+<P>
+There are some size limitations in PCRE but it is hoped that they will never in
+practice be relevant.
+The maximum length of a compiled pattern is 65539 (sic) bytes.
+All values in repeating quantifiers must be less than 65536.
+The maximum number of capturing subpatterns is 99.
+The maximum number of all parenthesized subpatterns, including capturing
+subpatterns, assertions, and other types of subpattern, is 200.
+</P>
+<P>
+The maximum length of a subject string is the largest positive number that an
+integer variable can hold. However, PCRE uses recursion to handle subpatterns
+and indefinite repetition. This means that the available stack space may limit
+the size of a subject string that can be processed by certain patterns.
+</P>
+<LI><A NAME="SEC12" HREF="#TOC1">DIFFERENCES FROM PERL</A>
+<P>
+The differences described here are with respect to Perl 5.005.
+</P>
+<P>
+1. By default, a whitespace character is any character that the C library
+function <B>isspace()</B> recognizes, though it is possible to compile PCRE with
+alternative character type tables. Normally <B>isspace()</B> matches space,
+formfeed, newline, carriage return, horizontal tab, and vertical tab. Perl 5
+no longer includes vertical tab in its set of whitespace characters. The \v
+escape that was in the Perl documentation for a long time was never in fact
+recognized. However, the character itself was treated as whitespace at least
+up to 5.002. In 5.004 and 5.005 it does not match \s.
+</P>
+<P>
+2. PCRE does not allow repeat quantifiers on lookahead assertions. Perl permits
+them, but they do not mean what you might think. For example, (?!a){3} does
+not assert that the next three characters are not "a". It just asserts that the
+next character is not "a" three times.
+</P>
+<P>
+3. Capturing subpatterns that occur inside negative lookahead assertions are
+counted, but their entries in the offsets vector are never set. Perl sets its
+numerical variables from any such patterns that are matched before the
+assertion fails to match something (thereby succeeding), but only if the
+negative lookahead assertion contains just one branch.
+</P>
+<P>
+4. Though binary zero characters are supported in the subject string, they are
+not allowed in a pattern string because it is passed as a normal C string,
+terminated by zero. The escape sequence "\0" can be used in the pattern to
+represent a binary zero.
+</P>
+<P>
+5. The following Perl escape sequences are not supported: \l, \u, \L, \U,
+\E, \Q. In fact these are implemented by Perl's general string-handling and
+are not part of its pattern matching engine.
+</P>
+<P>
+6. The Perl \G assertion is not supported as it is not relevant to single
+pattern matches.
+</P>
+<P>
+7. Fairly obviously, PCRE does not support the (?{code}) construction.
+</P>
+<P>
+8. There are at the time of writing some oddities in Perl 5.005_02 concerned
+with the settings of captured strings when part of a pattern is repeated. For
+example, matching "aba" against the pattern /^(a(b)?)+$/ sets $2 to the value
+"b", but matching "aabbaa" against /^(aa(bb)?)+$/ leaves $2 unset. However, if
+the pattern is changed to /^(aa(b(b))?)+$/ then $2 (and $3) get set.
+</P>
+<P>
+In Perl 5.004 $2 is set in both cases, and that is also true of PCRE. If in the
+future Perl changes to a consistent state that is different, PCRE may change to
+follow.
+</P>
+<P>
+9. Another as yet unresolved discrepancy is that in Perl 5.005_02 the pattern
+/^(a)?(?(1)a|b)+$/ matches the string "a", whereas in PCRE it does not.
+However, in both Perl and PCRE /^(a)?a/ matched against "a" leaves $1 unset.
+</P>
+<P>
+10. PCRE provides some extensions to the Perl regular expression facilities:
+</P>
+<P>
+(a) Although lookbehind assertions must match fixed length strings, each
+alternative branch of a lookbehind assertion can match a different length of
+string. Perl 5.005 requires them all to have the same length.
+</P>
+<P>
+(b) If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not set, the $ meta-
+character matches only at the very end of the string.
+</P>
+<P>
+(c) If PCRE_EXTRA is set, a backslash followed by a letter with no special
+meaning is faulted.
+</P>
+<P>
+(d) If PCRE_UNGREEDY is set, the greediness of the repetition quantifiers is
+inverted, that is, by default they are not greedy, but if followed by a
+question mark they are.
+</P>
+<P>
+(e) PCRE_ANCHORED can be used to force a pattern to be tried only at the start
+of the subject.
+</P>
+<P>
+(f) The PCRE_NOTBOL, PCRE_NOTEOL, and PCRE_NOTEMPTY options for
+<B>pcre_exec()</B> have no Perl equivalents.
+</P>
+<LI><A NAME="SEC13" HREF="#TOC1">REGULAR EXPRESSION DETAILS</A>
+<P>
+The syntax and semantics of the regular expressions supported by PCRE are
+described below. Regular expressions are also described in the Perl
+documentation and in a number of other books, some of which have copious
+examples. Jeffrey Friedl's "Mastering Regular Expressions", published by
+O'Reilly (ISBN 1-56592-257-3), covers them in great detail. The description
+here is intended as reference documentation.
+</P>
+<P>
+A regular expression is a pattern that is matched against a subject string from
+left to right. Most characters stand for themselves in a pattern, and match the
+corresponding characters in the subject. As a trivial example, the pattern
+</P>
+<P>
+<PRE>
+ The quick brown fox
+</PRE>
+</P>
+<P>
+matches a portion of a subject string that is identical to itself. The power of
+regular expressions comes from the ability to include alternatives and
+repetitions in the pattern. These are encoded in the pattern by the use of
+<I>meta-characters</I>, which do not stand for themselves but instead are
+interpreted in some special way.
+</P>
+<P>
+There are two different sets of meta-characters: those that are recognized
+anywhere in the pattern except within square brackets, and those that are
+recognized in square brackets. Outside square brackets, the meta-characters are
+as follows:
+</P>
+<P>
+<PRE>
+ \ general escape character with several uses
+ ^ assert start of subject (or line, in multiline mode)
+ $ assert end of subject (or line, in multiline mode)
+ . match any character except newline (by default)
+ [ start character class definition
+ | start of alternative branch
+ ( start subpattern
+ ) end subpattern
+ ? extends the meaning of (
+ also 0 or 1 quantifier
+ also quantifier minimizer
+ * 0 or more quantifier
+ + 1 or more quantifier
+ { start min/max quantifier
+</PRE>
+</P>
+<P>
+Part of a pattern that is in square brackets is called a "character class". In
+a character class the only meta-characters are:
+</P>
+<P>
+<PRE>
+ \ general escape character
+ ^ negate the class, but only if the first character
+ - indicates character range
+ ] terminates the character class
+</PRE>
+</P>
+<P>
+The following sections describe the use of each of the meta-characters.
+</P>
+<LI><A NAME="SEC14" HREF="#TOC1">BACKSLASH</A>
+<P>
+The backslash character has several uses. Firstly, if it is followed by a
+non-alphameric character, it takes away any special meaning that character may
+have. This use of backslash as an escape character applies both inside and
+outside character classes.
+</P>
+<P>
+For example, if you want to match a "*" character, you write "\*" in the
+pattern. This applies whether or not the following character would otherwise be
+interpreted as a meta-character, so it is always safe to precede a
+non-alphameric with "\" to specify that it stands for itself. In particular,
+if you want to match a backslash, you write "\\".
+</P>
+<P>
+If a pattern is compiled with the PCRE_EXTENDED option, whitespace in the
+pattern (other than in a character class) and characters between a "#" outside
+a character class and the next newline character are ignored. An escaping
+backslash can be used to include a whitespace or "#" character as part of the
+pattern.
+</P>
+<P>
+A second use of backslash provides a way of encoding non-printing characters
+in patterns in a visible manner. There is no restriction on the appearance of
+non-printing characters, apart from the binary zero that terminates a pattern,
+but when a pattern is being prepared by text editing, it is usually easier to
+use one of the following escape sequences than the binary character it
+represents:
+</P>
+<P>
+<PRE>
+ \a alarm, that is, the BEL character (hex 07)
+ \cx "control-x", where x is any character
+ \e escape (hex 1B)
+ \f formfeed (hex 0C)
+ \n newline (hex 0A)
+ \r carriage return (hex 0D)
+ \t tab (hex 09)
+ \xhh character with hex code hh
+ \ddd character with octal code ddd, or backreference
+</PRE>
+</P>
+<P>
+The precise effect of "\cx" is as follows: if "x" is a lower case letter, it
+is converted to upper case. Then bit 6 of the character (hex 40) is inverted.
+Thus "\cz" becomes hex 1A, but "\c{" becomes hex 3B, while "\c;" becomes hex
+7B.
+</P>
+<P>
+After "\x", up to two hexadecimal digits are read (letters can be in upper or
+lower case).
+</P>
+<P>
+After "\0" up to two further octal digits are read. In both cases, if there
+are fewer than two digits, just those that are present are used. Thus the
+sequence "\0\x\07" specifies two binary zeros followed by a BEL character.
+Make sure you supply two digits after the initial zero if the character that
+follows is itself an octal digit.
+</P>
+<P>
+The handling of a backslash followed by a digit other than 0 is complicated.
+Outside a character class, PCRE reads it and any following digits as a decimal
+number. If the number is less than 10, or if there have been at least that many
+previous capturing left parentheses in the expression, the entire sequence is
+taken as a <I>back reference</I>. A description of how this works is given
+later, following the discussion of parenthesized subpatterns.
+</P>
+<P>
+Inside a character class, or if the decimal number is greater than 9 and there
+have not been that many capturing subpatterns, PCRE re-reads up to three octal
+digits following the backslash, and generates a single byte from the least
+significant 8 bits of the value. Any subsequent digits stand for themselves.
+For example:
+</P>
+<P>
+<PRE>
+ \040 is another way of writing a space
+ \40 is the same, provided there are fewer than 40
+ previous capturing subpatterns
+ \7 is always a back reference
+ \11 might be a back reference, or another way of
+ writing a tab
+ \011 is always a tab
+ \0113 is a tab followed by the character "3"
+ \113 is the character with octal code 113 (since there
+ can be no more than 99 back references)
+ \377 is a byte consisting entirely of 1 bits
+ \81 is either a back reference, or a binary zero
+ followed by the two characters "8" and "1"
+</PRE>
+</P>
+<P>
+Note that octal values of 100 or greater must not be introduced by a leading
+zero, because no more than three octal digits are ever read.
+</P>
+<P>
+All the sequences that define a single byte value can be used both inside and
+outside character classes. In addition, inside a character class, the sequence
+"\b" is interpreted as the backspace character (hex 08). Outside a character
+class it has a different meaning (see below).
+</P>
+<P>
+The third use of backslash is for specifying generic character types:
+</P>
+<P>
+<PRE>
+ \d any decimal digit
+ \D any character that is not a decimal digit
+ \s any whitespace character
+ \S any character that is not a whitespace character
+ \w any "word" character
+ \W any "non-word" character
+</PRE>
+</P>
+<P>
+Each pair of escape sequences partitions the complete set of characters into
+two disjoint sets. Any given character matches one, and only one, of each pair.
+</P>
+<P>
+A "word" character is any letter or digit or the underscore character, that is,
+any character which can be part of a Perl "word". The definition of letters and
+digits is controlled by PCRE's character tables, and may vary if locale-
+specific matching is taking place (see "Locale support" above). For example, in
+the "fr" (French) locale, some character codes greater than 128 are used for
+accented letters, and these are matched by \w.
+</P>
+<P>
+These character type sequences can appear both inside and outside character
+classes. They each match one character of the appropriate type. If the current
+matching point is at the end of the subject string, all of them fail, since
+there is no character to match.
+</P>
+<P>
+The fourth use of backslash is for certain simple assertions. An assertion
+specifies a condition that has to be met at a particular point in a match,
+without consuming any characters from the subject string. The use of
+subpatterns for more complicated assertions is described below. The backslashed
+assertions are
+</P>
+<P>
+<PRE>
+ \b word boundary
+ \B not a word boundary
+ \A start of subject (independent of multiline mode)
+ \Z end of subject or newline at end (independent of multiline mode)
+ \z end of subject (independent of multiline mode)
+</PRE>
+</P>
+<P>
+These assertions may not appear in character classes (but note that "\b" has a
+different meaning, namely the backspace character, inside a character class).
+</P>
+<P>
+A word boundary is a position in the subject string where the current character
+and the previous character do not both match \w or \W (i.e. one matches
+\w and the other matches \W), or the start or end of the string if the
+first or last character matches \w, respectively.
+</P>
+<P>
+The \A, \Z, and \z assertions differ from the traditional circumflex and
+dollar (described below) in that they only ever match at the very start and end
+of the subject string, whatever options are set. They are not affected by the
+PCRE_NOTBOL or PCRE_NOTEOL options. If the <I>startoffset</I> argument of
+<B>pcre_exec()</B> is non-zero, \A can never match. The difference between \Z
+and \z is that \Z matches before a newline that is the last character of the
+string as well as at the end of the string, whereas \z matches only at the
+end.
+</P>
+<LI><A NAME="SEC15" HREF="#TOC1">CIRCUMFLEX AND DOLLAR</A>
+<P>
+Outside a character class, in the default matching mode, the circumflex
+character is an assertion which is true only if the current matching point is
+at the start of the subject string. If the <I>startoffset</I> argument of
+<B>pcre_exec()</B> is non-zero, circumflex can never match. Inside a character
+class, circumflex has an entirely different meaning (see below).
+</P>
+<P>
+Circumflex need not be the first character of the pattern if a number of
+alternatives are involved, but it should be the first thing in each alternative
+in which it appears if the pattern is ever to match that branch. If all
+possible alternatives start with a circumflex, that is, if the pattern is
+constrained to match only at the start of the subject, it is said to be an
+"anchored" pattern. (There are also other constructs that can cause a pattern
+to be anchored.)
+</P>
+<P>
+A dollar character is an assertion which is true only if the current matching
+point is at the end of the subject string, or immediately before a newline
+character that is the last character in the string (by default). Dollar need
+not be the last character of the pattern if a number of alternatives are
+involved, but it should be the last item in any branch in which it appears.
+Dollar has no special meaning in a character class.
+</P>
+<P>
+The meaning of dollar can be changed so that it matches only at the very end of
+the string, by setting the PCRE_DOLLAR_ENDONLY option at compile or matching
+time. This does not affect the \Z assertion.
+</P>
+<P>
+The meanings of the circumflex and dollar characters are changed if the
+PCRE_MULTILINE option is set. When this is the case, they match immediately
+after and immediately before an internal "\n" character, respectively, in
+addition to matching at the start and end of the subject string. For example,
+the pattern /^abc$/ matches the subject string "def\nabc" in multiline mode,
+but not otherwise. Consequently, patterns that are anchored in single line mode
+because all branches start with "^" are not anchored in multiline mode, and a
+match for circumflex is possible when the <I>startoffset</I> argument of
+<B>pcre_exec()</B> is non-zero. The PCRE_DOLLAR_ENDONLY option is ignored if
+PCRE_MULTILINE is set.
+</P>
+<P>
+Note that the sequences \A, \Z, and \z can be used to match the start and
+end of the subject in both modes, and if all branches of a pattern start with
+\A is it always anchored, whether PCRE_MULTILINE is set or not.
+</P>
+<LI><A NAME="SEC16" HREF="#TOC1">FULL STOP (PERIOD, DOT)</A>
+<P>
+Outside a character class, a dot in the pattern matches any one character in
+the subject, including a non-printing character, but not (by default) newline.
+If the PCRE_DOTALL option is set, then dots match newlines as well. The
+handling of dot is entirely independent of the handling of circumflex and
+dollar, the only relationship being that they both involve newline characters.
+Dot has no special meaning in a character class.
+</P>
+<LI><A NAME="SEC17" HREF="#TOC1">SQUARE BRACKETS</A>
+<P>
+An opening square bracket introduces a character class, terminated by a closing
+square bracket. A closing square bracket on its own is not special. If a
+closing square bracket is required as a member of the class, it should be the
+first data character in the class (after an initial circumflex, if present) or
+escaped with a backslash.
+</P>
+<P>
+A character class matches a single character in the subject; the character must
+be in the set of characters defined by the class, unless the first character in
+the class is a circumflex, in which case the subject character must not be in
+the set defined by the class. If a circumflex is actually required as a member
+of the class, ensure it is not the first character, or escape it with a
+backslash.
+</P>
+<P>
+For example, the character class [aeiou] matches any lower case vowel, while
+[^aeiou] matches any character that is not a lower case vowel. Note that a
+circumflex is just a convenient notation for specifying the characters which
+are in the class by enumerating those that are not. It is not an assertion: it
+still consumes a character from the subject string, and fails if the current
+pointer is at the end of the string.
+</P>
+<P>
+When caseless matching is set, any letters in a class represent both their
+upper case and lower case versions, so for example, a caseless [aeiou] matches
+"A" as well as "a", and a caseless [^aeiou] does not match "A", whereas a
+caseful version would.
+</P>
+<P>
+The newline character is never treated in any special way in character classes,
+whatever the setting of the PCRE_DOTALL or PCRE_MULTILINE options is. A class
+such as [^a] will always match a newline.
+</P>
+<P>
+The minus (hyphen) character can be used to specify a range of characters in a
+character class. For example, [d-m] matches any letter between d and m,
+inclusive. If a minus character is required in a class, it must be escaped with
+a backslash or appear in a position where it cannot be interpreted as
+indicating a range, typically as the first or last character in the class.
+</P>
+<P>
+It is not possible to have the literal character "]" as the end character of a
+range. A pattern such as [W-]46] is interpreted as a class of two characters
+("W" and "-") followed by a literal string "46]", so it would match "W46]" or
+"-46]". However, if the "]" is escaped with a backslash it is interpreted as
+the end of range, so [W-\]46] is interpreted as a single class containing a
+range followed by two separate characters. The octal or hexadecimal
+representation of "]" can also be used to end a range.
+</P>
+<P>
+Ranges operate in ASCII collating sequence. They can also be used for
+characters specified numerically, for example [\000-\037]. If a range that
+includes letters is used when caseless matching is set, it matches the letters
+in either case. For example, [W-c] is equivalent to [][\^_`wxyzabc], matched
+caselessly, and if character tables for the "fr" locale are in use,
+[\xc8-\xcb] matches accented E characters in both cases.
+</P>
+<P>
+The character types \d, \D, \s, \S, \w, and \W may also appear in a
+character class, and add the characters that they match to the class. For
+example, [\dABCDEF] matches any hexadecimal digit. A circumflex can
+conveniently be used with the upper case character types to specify a more
+restricted set of characters than the matching lower case type. For example,
+the class [^\W_] matches any letter or digit, but not underscore.
+</P>
+<P>
+All non-alphameric characters other than \, -, ^ (at the start) and the
+terminating ] are non-special in character classes, but it does no harm if they
+are escaped.
+</P>
+<LI><A NAME="SEC18" HREF="#TOC1">VERTICAL BAR</A>
+<P>
+Vertical bar characters are used to separate alternative patterns. For example,
+the pattern
+</P>
+<P>
+<PRE>
+ gilbert|sullivan
+</PRE>
+</P>
+<P>
+matches either "gilbert" or "sullivan". Any number of alternatives may appear,
+and an empty alternative is permitted (matching the empty string).
+The matching process tries each alternative in turn, from left to right,
+and the first one that succeeds is used. If the alternatives are within a
+subpattern (defined below), "succeeds" means matching the rest of the main
+pattern as well as the alternative in the subpattern.
+</P>
+<LI><A NAME="SEC19" HREF="#TOC1">INTERNAL OPTION SETTING</A>
+<P>
+The settings of PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, and PCRE_EXTENDED
+can be changed from within the pattern by a sequence of Perl option letters
+enclosed between "(?" and ")". The option letters are
+</P>
+<P>
+<PRE>
+ i for PCRE_CASELESS
+ m for PCRE_MULTILINE
+ s for PCRE_DOTALL
+ x for PCRE_EXTENDED
+</PRE>
+</P>
+<P>
+For example, (?im) sets caseless, multiline matching. It is also possible to
+unset these options by preceding the letter with a hyphen, and a combined
+setting and unsetting such as (?im-sx), which sets PCRE_CASELESS and
+PCRE_MULTILINE while unsetting PCRE_DOTALL and PCRE_EXTENDED, is also
+permitted. If a letter appears both before and after the hyphen, the option is
+unset.
+</P>
+<P>
+The scope of these option changes depends on where in the pattern the setting
+occurs. For settings that are outside any subpattern (defined below), the
+effect is the same as if the options were set or unset at the start of
+matching. The following patterns all behave in exactly the same way:
+</P>
+<P>
+<PRE>
+ (?i)abc
+ a(?i)bc
+ ab(?i)c
+ abc(?i)
+</PRE>
+</P>
+<P>
+which in turn is the same as compiling the pattern abc with PCRE_CASELESS set.
+In other words, such "top level" settings apply to the whole pattern (unless
+there are other changes inside subpatterns). If there is more than one setting
+of the same option at top level, the rightmost setting is used.
+</P>
+<P>
+If an option change occurs inside a subpattern, the effect is different. This
+is a change of behaviour in Perl 5.005. An option change inside a subpattern
+affects only that part of the subpattern that follows it, so
+</P>
+<P>
+<PRE>
+ (a(?i)b)c
+</PRE>
+</P>
+<P>
+matches abc and aBc and no other strings (assuming PCRE_CASELESS is not used).
+By this means, options can be made to have different settings in different
+parts of the pattern. Any changes made in one alternative do carry on
+into subsequent branches within the same subpattern. For example,
+</P>
+<P>
+<PRE>
+ (a(?i)b|c)
+</PRE>
+</P>
+<P>
+matches "ab", "aB", "c", and "C", even though when matching "C" the first
+branch is abandoned before the option setting. This is because the effects of
+option settings happen at compile time. There would be some very weird
+behaviour otherwise.
+</P>
+<P>
+The PCRE-specific options PCRE_UNGREEDY and PCRE_EXTRA can be changed in the
+same way as the Perl-compatible options by using the characters U and X
+respectively. The (?X) flag setting is special in that it must always occur
+earlier in the pattern than any of the additional features it turns on, even
+when it is at top level. It is best put at the start.
+</P>
+<LI><A NAME="SEC20" HREF="#TOC1">SUBPATTERNS</A>
+<P>
+Subpatterns are delimited by parentheses (round brackets), which can be nested.
+Marking part of a pattern as a subpattern does two things:
+</P>
+<P>
+1. It localizes a set of alternatives. For example, the pattern
+</P>
+<P>
+<PRE>
+ cat(aract|erpillar|)
+</PRE>
+</P>
+<P>
+matches one of the words "cat", "cataract", or "caterpillar". Without the
+parentheses, it would match "cataract", "erpillar" or the empty string.
+</P>
+<P>
+2. It sets up the subpattern as a capturing subpattern (as defined above).
+When the whole pattern matches, that portion of the subject string that matched
+the subpattern is passed back to the caller via the <I>ovector</I> argument of
+<B>pcre_exec()</B>. Opening parentheses are counted from left to right (starting
+from 1) to obtain the numbers of the capturing subpatterns.
+</P>
+<P>
+For example, if the string "the red king" is matched against the pattern
+</P>
+<P>
+<PRE>
+ the ((red|white) (king|queen))
+</PRE>
+</P>
+<P>
+the captured substrings are "red king", "red", and "king", and are numbered 1,
+2, and 3.
+</P>
+<P>
+The fact that plain parentheses fulfil two functions is not always helpful.
+There are often times when a grouping subpattern is required without a
+capturing requirement. If an opening parenthesis is followed by "?:", the
+subpattern does not do any capturing, and is not counted when computing the
+number of any subsequent capturing subpatterns. For example, if the string "the
+white queen" is matched against the pattern
+</P>
+<P>
+<PRE>
+ the ((?:red|white) (king|queen))
+</PRE>
+</P>
+<P>
+the captured substrings are "white queen" and "queen", and are numbered 1 and
+2. The maximum number of captured substrings is 99, and the maximum number of
+all subpatterns, both capturing and non-capturing, is 200.
+</P>
+<P>
+As a convenient shorthand, if any option settings are required at the start of
+a non-capturing subpattern, the option letters may appear between the "?" and
+the ":". Thus the two patterns
+</P>
+<P>
+<PRE>
+ (?i:saturday|sunday)
+ (?:(?i)saturday|sunday)
+</PRE>
+</P>
+<P>
+match exactly the same set of strings. Because alternative branches are tried
+from left to right, and options are not reset until the end of the subpattern
+is reached, an option setting in one branch does affect subsequent branches, so
+the above patterns match "SUNDAY" as well as "Saturday".
+</P>
+<LI><A NAME="SEC21" HREF="#TOC1">REPETITION</A>
+<P>
+Repetition is specified by quantifiers, which can follow any of the following
+items:
+</P>
+<P>
+<PRE>
+ a single character, possibly escaped
+ the . metacharacter
+ a character class
+ a back reference (see next section)
+ a parenthesized subpattern (unless it is an assertion - see below)
+</PRE>
+</P>
+<P>
+The general repetition quantifier specifies a minimum and maximum number of
+permitted matches, by giving the two numbers in curly brackets (braces),
+separated by a comma. The numbers must be less than 65536, and the first must
+be less than or equal to the second. For example:
+</P>
+<P>
+<PRE>
+ z{2,4}
+</PRE>
+</P>
+<P>
+matches "zz", "zzz", or "zzzz". A closing brace on its own is not a special
+character. If the second number is omitted, but the comma is present, there is
+no upper limit; if the second number and the comma are both omitted, the
+quantifier specifies an exact number of required matches. Thus
+</P>
+<P>
+<PRE>
+ [aeiou]{3,}
+</PRE>
+</P>
+<P>
+matches at least 3 successive vowels, but may match many more, while
+</P>
+<P>
+<PRE>
+ \d{8}
+</PRE>
+</P>
+<P>
+matches exactly 8 digits. An opening curly bracket that appears in a position
+where a quantifier is not allowed, or one that does not match the syntax of a
+quantifier, is taken as a literal character. For example, {,6} is not a
+quantifier, but a literal string of four characters.
+</P>
+<P>
+The quantifier {0} is permitted, causing the expression to behave as if the
+previous item and the quantifier were not present.
+</P>
+<P>
+For convenience (and historical compatibility) the three most common
+quantifiers have single-character abbreviations:
+</P>
+<P>
+<PRE>
+ * is equivalent to {0,}
+ + is equivalent to {1,}
+ ? is equivalent to {0,1}
+</PRE>
+</P>
+<P>
+It is possible to construct infinite loops by following a subpattern that can
+match no characters with a quantifier that has no upper limit, for example:
+</P>
+<P>
+<PRE>
+ (a?)*
+</PRE>
+</P>
+<P>
+Earlier versions of Perl and PCRE used to give an error at compile time for
+such patterns. However, because there are cases where this can be useful, such
+patterns are now accepted, but if any repetition of the subpattern does in fact
+match no characters, the loop is forcibly broken.
+</P>
+<P>
+By default, the quantifiers are "greedy", that is, they match as much as
+possible (up to the maximum number of permitted times), without causing the
+rest of the pattern to fail. The classic example of where this gives problems
+is in trying to match comments in C programs. These appear between the
+sequences /* and */ and within the sequence, individual * and / characters may
+appear. An attempt to match C comments by applying the pattern
+</P>
+<P>
+<PRE>
+ /\*.*\*/
+</PRE>
+</P>
+<P>
+to the string
+</P>
+<P>
+<PRE>
+ /* first command */ not comment /* second comment */
+</PRE>
+</P>
+<P>
+fails, because it matches the entire string due to the greediness of the .*
+item.
+</P>
+<P>
+However, if a quantifier is followed by a question mark, then it ceases to be
+greedy, and instead matches the minimum number of times possible, so the
+pattern
+</P>
+<P>
+<PRE>
+ /\*.*?\*/
+</PRE>
+</P>
+<P>
+does the right thing with the C comments. The meaning of the various
+quantifiers is not otherwise changed, just the preferred number of matches.
+Do not confuse this use of question mark with its use as a quantifier in its
+own right. Because it has two uses, it can sometimes appear doubled, as in
+</P>
+<P>
+<PRE>
+ \d??\d
+</PRE>
+</P>
+<P>
+which matches one digit by preference, but can match two if that is the only
+way the rest of the pattern matches.
+</P>
+<P>
+If the PCRE_UNGREEDY option is set (an option which is not available in Perl)
+then the quantifiers are not greedy by default, but individual ones can be made
+greedy by following them with a question mark. In other words, it inverts the
+default behaviour.
+</P>
+<P>
+When a parenthesized subpattern is quantified with a minimum repeat count that
+is greater than 1 or with a limited maximum, more store is required for the
+compiled pattern, in proportion to the size of the minimum or maximum.
+</P>
+<P>
+If a pattern starts with .* or .{0,} and the PCRE_DOTALL option (equivalent
+to Perl's /s) is set, thus allowing the . to match newlines, then the pattern
+is implicitly anchored, because whatever follows will be tried against every
+character position in the subject string, so there is no point in retrying the
+overall match at any position after the first. PCRE treats such a pattern as
+though it were preceded by \A. In cases where it is known that the subject
+string contains no newlines, it is worth setting PCRE_DOTALL when the pattern
+begins with .* in order to obtain this optimization, or alternatively using ^
+to indicate anchoring explicitly.
+</P>
+<P>
+When a capturing subpattern is repeated, the value captured is the substring
+that matched the final iteration. For example, after
+</P>
+<P>
+<PRE>
+ (tweedle[dume]{3}\s*)+
+</PRE>
+</P>
+<P>
+has matched "tweedledum tweedledee" the value of the captured substring is
+"tweedledee". However, if there are nested capturing subpatterns, the
+corresponding captured values may have been set in previous iterations. For
+example, after
+</P>
+<P>
+<PRE>
+ /(a|(b))+/
+</PRE>
+</P>
+<P>
+matches "aba" the value of the second captured substring is "b".
+</P>
+<LI><A NAME="SEC22" HREF="#TOC1">BACK REFERENCES</A>
+<P>
+Outside a character class, a backslash followed by a digit greater than 0 (and
+possibly further digits) is a back reference to a capturing subpattern earlier
+(i.e. to its left) in the pattern, provided there have been that many previous
+capturing left parentheses.
+</P>
+<P>
+However, if the decimal number following the backslash is less than 10, it is
+always taken as a back reference, and causes an error only if there are not
+that many capturing left parentheses in the entire pattern. In other words, the
+parentheses that are referenced need not be to the left of the reference for
+numbers less than 10. See the section entitled "Backslash" above for further
+details of the handling of digits following a backslash.
+</P>
+<P>
+A back reference matches whatever actually matched the capturing subpattern in
+the current subject string, rather than anything matching the subpattern
+itself. So the pattern
+</P>
+<P>
+<PRE>
+ (sens|respons)e and \1ibility
+</PRE>
+</P>
+<P>
+matches "sense and sensibility" and "response and responsibility", but not
+"sense and responsibility". If caseful matching is in force at the time of the
+back reference, then the case of letters is relevant. For example,
+</P>
+<P>
+<PRE>
+ ((?i)rah)\s+\1
+</PRE>
+</P>
+<P>
+matches "rah rah" and "RAH RAH", but not "RAH rah", even though the original
+capturing subpattern is matched caselessly.
+</P>
+<P>
+There may be more than one back reference to the same subpattern. If a
+subpattern has not actually been used in a particular match, then any back
+references to it always fail. For example, the pattern
+</P>
+<P>
+<PRE>
+ (a|(bc))\2
+</PRE>
+</P>
+<P>
+always fails if it starts to match "a" rather than "bc". Because there may be
+up to 99 back references, all digits following the backslash are taken
+as part of a potential back reference number. If the pattern continues with a
+digit character, then some delimiter must be used to terminate the back
+reference. If the PCRE_EXTENDED option is set, this can be whitespace.
+Otherwise an empty comment can be used.
+</P>
+<P>
+A back reference that occurs inside the parentheses to which it refers fails
+when the subpattern is first used, so, for example, (a\1) never matches.
+However, such references can be useful inside repeated subpatterns. For
+example, the pattern
+</P>
+<P>
+<PRE>
+ (a|b\1)+
+</PRE>
+</P>
+<P>
+matches any number of "a"s and also "aba", "ababaa" etc. At each iteration of
+the subpattern, the back reference matches the character string corresponding
+to the previous iteration. In order for this to work, the pattern must be such
+that the first iteration does not need to match the back reference. This can be
+done using alternation, as in the example above, or by a quantifier with a
+minimum of zero.
+</P>
+<LI><A NAME="SEC23" HREF="#TOC1">ASSERTIONS</A>
+<P>
+An assertion is a test on the characters following or preceding the current
+matching point that does not actually consume any characters. The simple
+assertions coded as \b, \B, \A, \Z, \z, ^ and $ are described above. More
+complicated assertions are coded as subpatterns. There are two kinds: those
+that look ahead of the current position in the subject string, and those that
+look behind it.
+</P>
+<P>
+An assertion subpattern is matched in the normal way, except that it does not
+cause the current matching position to be changed. Lookahead assertions start
+with (?= for positive assertions and (?! for negative assertions. For example,
+</P>
+<P>
+<PRE>
+ \w+(?=;)
+</PRE>
+</P>
+<P>
+matches a word followed by a semicolon, but does not include the semicolon in
+the match, and
+</P>
+<P>
+<PRE>
+ foo(?!bar)
+</PRE>
+</P>
+<P>
+matches any occurrence of "foo" that is not followed by "bar". Note that the
+apparently similar pattern
+</P>
+<P>
+<PRE>
+ (?!foo)bar
+</PRE>
+</P>
+<P>
+does not find an occurrence of "bar" that is preceded by something other than
+"foo"; it finds any occurrence of "bar" whatsoever, because the assertion
+(?!foo) is always true when the next three characters are "bar". A
+lookbehind assertion is needed to achieve this effect.
+</P>
+<P>
+Lookbehind assertions start with (?<= for positive assertions and (?<! for
+negative assertions. For example,
+</P>
+<P>
+<PRE>
+ (?<!foo)bar
+</PRE>
+</P>
+<P>
+does find an occurrence of "bar" that is not preceded by "foo". The contents of
+a lookbehind assertion are restricted such that all the strings it matches must
+have a fixed length. However, if there are several alternatives, they do not
+all have to have the same fixed length. Thus
+</P>
+<P>
+<PRE>
+ (?<=bullock|donkey)
+</PRE>
+</P>
+<P>
+is permitted, but
+</P>
+<P>
+<PRE>
+ (?<!dogs?|cats?)
+</PRE>
+</P>
+<P>
+causes an error at compile time. Branches that match different length strings
+are permitted only at the top level of a lookbehind assertion. This is an
+extension compared with Perl 5.005, which requires all branches to match the
+same length of string. An assertion such as
+</P>
+<P>
+<PRE>
+ (?<=ab(c|de))
+</PRE>
+</P>
+<P>
+is not permitted, because its single top-level branch can match two different
+lengths, but it is acceptable if rewritten to use two top-level branches:
+</P>
+<P>
+<PRE>
+ (?<=abc|abde)
+</PRE>
+</P>
+<P>
+The implementation of lookbehind assertions is, for each alternative, to
+temporarily move the current position back by the fixed width and then try to
+match. If there are insufficient characters before the current position, the
+match is deemed to fail. Lookbehinds in conjunction with once-only subpatterns
+can be particularly useful for matching at the ends of strings; an example is
+given at the end of the section on once-only subpatterns.
+</P>
+<P>
+Several assertions (of any sort) may occur in succession. For example,
+</P>
+<P>
+<PRE>
+ (?<=\d{3})(?<!999)foo
+</PRE>
+</P>
+<P>
+matches "foo" preceded by three digits that are not "999". Notice that each of
+the assertions is applied independently at the same point in the subject
+string. First there is a check that the previous three characters are all
+digits, then there is a check that the same three characters are not "999".
+This pattern does <I>not</I> match "foo" preceded by six characters, the first
+of which are digits and the last three of which are not "999". For example, it
+doesn't match "123abcfoo". A pattern to do that is
+</P>
+<P>
+<PRE>
+ (?<=\d{3}...)(?<!999)foo
+</PRE>
+</P>
+<P>
+This time the first assertion looks at the preceding six characters, checking
+that the first three are digits, and then the second assertion checks that the
+preceding three characters are not "999".
+</P>
+<P>
+Assertions can be nested in any combination. For example,
+</P>
+<P>
+<PRE>
+ (?<=(?<!foo)bar)baz
+</PRE>
+</P>
+<P>
+matches an occurrence of "baz" that is preceded by "bar" which in turn is not
+preceded by "foo", while
+</P>
+<P>
+<PRE>
+ (?<=\d{3}(?!999)...)foo
+</PRE>
+</P>
+<P>
+is another pattern which matches "foo" preceded by three digits and any three
+characters that are not "999".
+</P>
+<P>
+Assertion subpatterns are not capturing subpatterns, and may not be repeated,
+because it makes no sense to assert the same thing several times. If any kind
+of assertion contains capturing subpatterns within it, these are counted for
+the purposes of numbering the capturing subpatterns in the whole pattern.
+However, substring capturing is carried out only for positive assertions,
+because it does not make sense for negative assertions.
+</P>
+<P>
+Assertions count towards the maximum of 200 parenthesized subpatterns.
+</P>
+<LI><A NAME="SEC24" HREF="#TOC1">ONCE-ONLY SUBPATTERNS</A>
+<P>
+With both maximizing and minimizing repetition, failure of what follows
+normally causes the repeated item to be re-evaluated to see if a different
+number of repeats allows the rest of the pattern to match. Sometimes it is
+useful to prevent this, either to change the nature of the match, or to cause
+it fail earlier than it otherwise might, when the author of the pattern knows
+there is no point in carrying on.
+</P>
+<P>
+Consider, for example, the pattern \d+foo when applied to the subject line
+</P>
+<P>
+<PRE>
+ 123456bar
+</PRE>
+</P>
+<P>
+After matching all 6 digits and then failing to match "foo", the normal
+action of the matcher is to try again with only 5 digits matching the \d+
+item, and then with 4, and so on, before ultimately failing. Once-only
+subpatterns provide the means for specifying that once a portion of the pattern
+has matched, it is not to be re-evaluated in this way, so the matcher would
+give up immediately on failing to match "foo" the first time. The notation is
+another kind of special parenthesis, starting with (?> as in this example:
+</P>
+<P>
+<PRE>
+ (?>\d+)bar
+</PRE>
+</P>
+<P>
+This kind of parenthesis "locks up" the part of the pattern it contains once
+it has matched, and a failure further into the pattern is prevented from
+backtracking into it. Backtracking past it to previous items, however, works as
+normal.
+</P>
+<P>
+An alternative description is that a subpattern of this type matches the string
+of characters that an identical standalone pattern would match, if anchored at
+the current point in the subject string.
+</P>
+<P>
+Once-only subpatterns are not capturing subpatterns. Simple cases such as the
+above example can be thought of as a maximizing repeat that must swallow
+everything it can. So, while both \d+ and \d+? are prepared to adjust the
+number of digits they match in order to make the rest of the pattern match,
+(?>\d+) can only match an entire sequence of digits.
+</P>
+<P>
+This construction can of course contain arbitrarily complicated subpatterns,
+and it can be nested.
+</P>
+<P>
+Once-only subpatterns can be used in conjunction with lookbehind assertions to
+specify efficient matching at the end of the subject string. Consider a simple
+pattern such as
+</P>
+<P>
+<PRE>
+ abcd$
+</PRE>
+</P>
+<P>
+when applied to a long string which does not match it. Because matching
+proceeds from left to right, PCRE will look for each "a" in the subject and
+then see if what follows matches the rest of the pattern. If the pattern is
+specified as
+</P>
+<P>
+<PRE>
+ ^.*abcd$
+</PRE>
+</P>
+<P>
+then the initial .* matches the entire string at first, but when this fails, it
+backtracks to match all but the last character, then all but the last two
+characters, and so on. Once again the search for "a" covers the entire string,
+from right to left, so we are no better off. However, if the pattern is written
+as
+</P>
+<P>
+<PRE>
+ ^(?>.*)(?<=abcd)
+</PRE>
+</P>
+<P>
+then there can be no backtracking for the .* item; it can match only the entire
+string. The subsequent lookbehind assertion does a single test on the last four
+characters. If it fails, the match fails immediately. For long strings, this
+approach makes a significant difference to the processing time.
+</P>
+<LI><A NAME="SEC25" HREF="#TOC1">CONDITIONAL SUBPATTERNS</A>
+<P>
+It is possible to cause the matching process to obey a subpattern
+conditionally or to choose between two alternative subpatterns, depending on
+the result of an assertion, or whether a previous capturing subpattern matched
+or not. The two possible forms of conditional subpattern are
+</P>
+<P>
+<PRE>
+ (?(condition)yes-pattern)
+ (?(condition)yes-pattern|no-pattern)
+</PRE>
+</P>
+<P>
+If the condition is satisfied, the yes-pattern is used; otherwise the
+no-pattern (if present) is used. If there are more than two alternatives in the
+subpattern, a compile-time error occurs.
+</P>
+<P>
+There are two kinds of condition. If the text between the parentheses consists
+of a sequence of digits, then the condition is satisfied if the capturing
+subpattern of that number has previously matched. Consider the following
+pattern, which contains non-significant white space to make it more readable
+(assume the PCRE_EXTENDED option) and to divide it into three parts for ease
+of discussion:
+</P>
+<P>
+<PRE>
+ ( \( )? [^()]+ (?(1) \) )
+</PRE>
+</P>
+<P>
+The first part matches an optional opening parenthesis, and if that
+character is present, sets it as the first captured substring. The second part
+matches one or more characters that are not parentheses. The third part is a
+conditional subpattern that tests whether the first set of parentheses matched
+or not. If they did, that is, if subject started with an opening parenthesis,
+the condition is true, and so the yes-pattern is executed and a closing
+parenthesis is required. Otherwise, since no-pattern is not present, the
+subpattern matches nothing. In other words, this pattern matches a sequence of
+non-parentheses, optionally enclosed in parentheses.
+</P>
+<P>
+If the condition is not a sequence of digits, it must be an assertion. This may
+be a positive or negative lookahead or lookbehind assertion. Consider this
+pattern, again containing non-significant white space, and with the two
+alternatives on the second line:
+</P>
+<P>
+<PRE>
+ (?(?=[^a-z]*[a-z])
+ \d{2}[a-z]{3}-\d{2} | \d{2}-\d{2}-\d{2} )
+</PRE>
+</P>
+<P>
+The condition is a positive lookahead assertion that matches an optional
+sequence of non-letters followed by a letter. In other words, it tests for the
+presence of at least one letter in the subject. If a letter is found, the
+subject is matched against the first alternative; otherwise it is matched
+against the second. This pattern matches strings in one of the two forms
+dd-aaa-dd or dd-dd-dd, where aaa are letters and dd are digits.
+</P>
+<LI><A NAME="SEC26" HREF="#TOC1">COMMENTS</A>
+<P>
+The sequence (?# marks the start of a comment which continues up to the next
+closing parenthesis. Nested parentheses are not permitted. The characters
+that make up a comment play no part in the pattern matching at all.
+</P>
+<P>
+If the PCRE_EXTENDED option is set, an unescaped # character outside a
+character class introduces a comment that continues up to the next newline
+character in the pattern.
+</P>
+<LI><A NAME="SEC27" HREF="#TOC1">PERFORMANCE</A>
+<P>
+Certain items that may appear in patterns are more efficient than others. It is
+more efficient to use a character class like [aeiou] than a set of alternatives
+such as (a|e|i|o|u). In general, the simplest construction that provides the
+required behaviour is usually the most efficient. Jeffrey Friedl's book
+contains a lot of discussion about optimizing regular expressions for efficient
+performance.
+</P>
+<P>
+When a pattern begins with .* and the PCRE_DOTALL option is set, the pattern is
+implicitly anchored by PCRE, since it can match only at the start of a subject
+string. However, if PCRE_DOTALL is not set, PCRE cannot make this optimization,
+because the . metacharacter does not then match a newline, and if the subject
+string contains newlines, the pattern may match from the character immediately
+following one of them instead of from the very start. For example, the pattern
+</P>
+<P>
+<PRE>
+ (.*) second
+</PRE>
+</P>
+<P>
+matches the subject "first\nand second" (where \n stands for a newline
+character) with the first captured substring being "and". In order to do this,
+PCRE has to retry the match starting after every newline in the subject.
+</P>
+<P>
+If you are using such a pattern with subject strings that do not contain
+newlines, the best performance is obtained by setting PCRE_DOTALL, or starting
+the pattern with ^.* to indicate explicit anchoring. That saves PCRE from
+having to scan along the subject looking for a newline to restart at.
+</P>
+<P>
+Beware of patterns that contain nested indefinite repeats. These can take a
+long time to run when applied to a string that does not match. Consider the
+pattern fragment
+</P>
+<P>
+<PRE>
+ (a+)*
+</PRE>
+</P>
+<P>
+This can match "aaaa" in 33 different ways, and this number increases very
+rapidly as the string gets longer. (The * repeat can match 0, 1, 2, 3, or 4
+times, and for each of those cases other than 0, the + repeats can match
+different numbers of times.) When the remainder of the pattern is such that the
+entire match is going to fail, PCRE has in principle to try every possible
+variation, and this can take an extremely long time.
+</P>
+<P>
+An optimization catches some of the more simple cases such as
+</P>
+<P>
+<PRE>
+ (a+)*b
+</PRE>
+</P>
+<P>
+where a literal character follows. Before embarking on the standard matching
+procedure, PCRE checks that there is a "b" later in the subject string, and if
+there is not, it fails the match immediately. However, when there is no
+following literal this optimization cannot be used. You can see the difference
+by comparing the behaviour of
+</P>
+<P>
+<PRE>
+ (a+)*\d
+</PRE>
+</P>
+<P>
+with the pattern above. The former gives a failure almost instantly when
+applied to a whole line of "a" characters, whereas the latter takes an
+appreciable time with strings longer than about 20 characters.
+</P>
+<LI><A NAME="SEC28" HREF="#TOC1">AUTHOR</A>
+<P>
+Philip Hazel <ph10@cam.ac.uk>
+<BR>
+University Computing Service,
+<BR>
+New Museums Site,
+<BR>
+Cambridge CB2 3QG, England.
+<BR>
+Phone: +44 1223 334714
+</P>
+<P>
+Last updated: 29 July 1999
+<BR>
+Copyright (c) 1997-1999 University of Cambridge.
--- /dev/null
+NAME
+ pcre - Perl-compatible regular expressions.
+
+
+
+SYNOPSIS
+ #include <pcre.h>
+
+ pcre *pcre_compile(const char *pattern, int options,
+ const char **errptr, int *erroffset,
+ const unsigned char *tableptr);
+
+ pcre_extra *pcre_study(const pcre *code, int options,
+ const char **errptr);
+
+ int pcre_exec(const pcre *code, const pcre_extra *extra,
+ const char *subject, int length, int startoffset,
+ int options, int *ovector, int ovecsize);
+
+ int pcre_copy_substring(const char *subject, int *ovector,
+ int stringcount, int stringnumber, char *buffer,
+ int buffersize);
+
+ int pcre_get_substring(const char *subject, int *ovector,
+ int stringcount, int stringnumber,
+ const char **stringptr);
+
+ int pcre_get_substring_list(const char *subject,
+ int *ovector, int stringcount, const char ***listptr);
+
+ const unsigned char *pcre_maketables(void);
+
+ int pcre_info(const pcre *code, int *optptr, *firstcharptr);
+
+ char *pcre_version(void);
+
+ void *(*pcre_malloc)(size_t);
+
+ void (*pcre_free)(void *);
+
+
+
+
+DESCRIPTION
+ The PCRE library is a set of functions that implement regu-
+ lar expression pattern matching using the same syntax and
+ semantics as Perl 5, with just a few differences (see
+ below). The current implementation corresponds to Perl
+ 5.005.
+
+ 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 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 functions pcre_compile(), pcre_study(), and pcre_exec()
+ are used for compiling and matching regular expressions,
+ while pcre_copy_substring(), pcre_get_substring(), and
+ pcre_get_substring_list() are convenience functions for
+ extracting captured substrings from a matched subject
+ string. The function pcre_maketables() is used (optionally)
+ to build a set of character tables in the current locale for
+ passing to pcre_compile().
+
+ The function pcre_info() is used to find out information
+ about a compiled pattern, while the function pcre_version()
+ returns a pointer to a string containing the version of PCRE
+ and its date of release.
+
+ The global variables pcre_malloc and pcre_free initially
+ contain the entry points of the standard malloc() and free()
+ functions respectively. PCRE calls the memory management
+ functions via these variables, so a calling program can
+ replace them if it wishes to intercept the calls. This
+ should be done before calling any PCRE functions.
+
+
+
+MULTI-THREADING
+ The PCRE functions can be used in multi-threading applica-
+ tions, with the proviso that the memory management functions
+ pointed to by pcre_malloc and pcre_free are shared by all
+ threads.
+
+ The compiled form of a regular expression is not altered
+ during matching, so the same compiled pattern can safely be
+ used by several threads at once.
+
+
+
+COMPILING A PATTERN
+ The function pcre_compile() is called to compile a pattern
+ into an internal form. The pattern is a C string terminated
+ by a binary zero, and is passed in the argument pattern. A
+ pointer to a single block of memory that is obtained via
+ pcre_malloc is returned. This contains the compiled code and
+ related data. The pcre type is defined for this for conveni-
+ ence, but in fact pcre is just a typedef for void, since the
+ contents of the block are not externally defined. It is up
+ to the caller to free the memory when it is no longer
+ required.
+
+ The size of a compiled pattern is roughly proportional to
+ the length of the pattern string, except that each character
+ class (other than those containing just a single character,
+ negated or not) requires 33 bytes, and repeat quantifiers
+ with a minimum greater than one or a bounded maximum cause
+ the relevant portions of the compiled pattern to be repli-
+ cated.
+
+ The options argument contains independent bits that affect
+ the compilation. It should be zero if no options are
+ required. Some of the options, in particular, those that are
+ compatible with Perl, can also be set and unset from within
+ the pattern (see the detailed description of regular expres-
+ sions below). For these options, the contents of the options
+ argument specifies their initial settings at the start of
+ compilation and execution. The PCRE_ANCHORED option can be
+ set at the time of matching as well as at compile time.
+
+ If errptr is NULL, pcre_compile() returns NULL immediately.
+ Otherwise, if compilation of a pattern fails, pcre_compile()
+ returns NULL, and sets the variable pointed to by errptr to
+ point to a textual error message. The offset from the start
+ of the pattern to the character where the error was
+ discovered is placed in the variable pointed to by
+ erroffset, which must not be NULL. If it is, an immediate
+ error is given.
+
+ If the final argument, tableptr, is NULL, PCRE uses a
+ default set of character tables which are built when it is
+ compiled, using the default C locale. Otherwise, tableptr
+ must be the result of a call to pcre_maketables(). See the
+ section on locale support below.
+
+ The following option bits are defined in the header file:
+
+ PCRE_ANCHORED
+
+ If this bit is set, the pattern is forced to be "anchored",
+ that is, it is constrained to match only at the start of the
+ string which is being searched (the "subject string"). This
+ effect can also be achieved by appropriate constructs in the
+ pattern itself, which is the only way to do it in Perl.
+
+ PCRE_CASELESS
+
+ If this bit is set, letters in the pattern match both upper
+ and lower case letters. It is equivalent to Perl's /i
+ option.
+
+ PCRE_DOLLAR_ENDONLY
+
+ If this bit is set, a dollar metacharacter in the pattern
+ matches only at the end of the subject string. Without this
+ option, a dollar also matches immediately before the final
+ character if it is a newline (but not before any other new-
+ lines). The PCRE_DOLLAR_ENDONLY option is ignored if
+ PCRE_MULTILINE is set. There is no equivalent to this option
+ in Perl.
+
+ PCRE_DOTALL
+
+ If this bit is set, a dot metacharater in the pattern
+ matches all characters, including newlines. Without it, new-
+ lines are excluded. This option is equivalent to Perl's /s
+ option. A negative class such as [^a] always matches a new-
+ line character, independent of the setting of this option.
+
+ PCRE_EXTENDED
+
+ If this bit is set, whitespace data characters in the pat-
+ tern are totally ignored except when escaped or inside a
+ character class, and characters between an unescaped # out-
+ side a character class and the next newline character,
+ inclusive, are also ignored. This is equivalent to Perl's /x
+ option, and makes it possible to include comments inside
+ complicated patterns. Note, however, that this applies only
+ to data characters. Whitespace characters may never appear
+ within special character sequences in a pattern, for example
+ within the sequence (?( which introduces a conditional sub-
+ pattern.
+
+ PCRE_EXTRA
+
+ This option turns on additional functionality of PCRE that
+ is incompatible with Perl. 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.
+
+ PCRE_MULTILINE
+
+ By default, PCRE treats the subject string as consisting of
+ a single "line" of characters (even if it actually contains
+ several newlines). The "start of line" metacharacter (^)
+ matches only at the start of the string, while the "end of
+ line" metacharacter ($) matches only at the end of the
+ string, or before a terminating newline (unless
+ PCRE_DOLLAR_ENDONLY is set). This is the same as Perl.
+
+ When PCRE_MULTILINE it is set, the "start of line" and "end
+ of line" constructs match immediately following or
+ immediately before any newline in the subject string,
+ respectively, as well as at the very start and end. This is
+ equivalent to Perl's /m option. If there are no "\n" charac-
+ ters in a subject string, or no occurrences of ^ or $ in a
+ pattern, setting PCRE_MULTILINE has no effect.
+
+ PCRE_UNGREEDY
+
+ This option inverts the "greediness" of the quantifiers so
+ that they are not greedy by default, but become greedy if
+ followed by "?". It is not compatible with Perl. It can also
+ be set by a (?U) option setting within the pattern.
+
+
+
+STUDYING A PATTERN
+ When a pattern is going to be used several times, it is
+ worth spending more time analyzing it in order to speed up
+ the time taken for matching. The function pcre_study() takes
+ a pointer to a compiled pattern as its first argument, and
+ returns a pointer to a pcre_extra block (another void
+ typedef) containing additional information about the pat-
+ tern; this can be passed to pcre_exec(). If no additional
+ information is available, NULL is returned.
+
+ The second argument contains option bits. At present, no
+ options are defined for pcre_study(), and this argument
+ should always be zero.
+
+ The third argument for pcre_study() is a pointer to an error
+ message. If studying succeeds (even if no data is returned),
+ the variable it points to is set to NULL. Otherwise it
+ points to a textual error message.
+
+ At present, studying a pattern is useful only for non-
+ anchored patterns that do not have a single fixed starting
+ character. A bitmap of possible starting characters is
+ created.
+
+
+
+LOCALE SUPPORT
+ PCRE handles caseless matching, and determines whether char-
+ acters are letters, digits, or whatever, by reference to a
+ set of tables. The library contains a default set of tables
+ which is created in the default C locale when PCRE is com-
+ piled. This is used when the final argument of
+ pcre_compile() is NULL, and is sufficient for many applica-
+ tions.
+
+ An alternative set of tables can, however, be supplied. Such
+ tables are built by calling the pcre_maketables() function,
+ which has no arguments, in the relevant locale. The result
+ can then be passed to pcre_compile() as often as necessary.
+ For example, to build and use tables that are appropriate
+ for the French locale (where accented characters with codes
+ greater than 128 are treated as letters), the following code
+ could be used:
+
+ setlocale(LC_CTYPE, "fr");
+ tables = pcre_maketables();
+ re = pcre_compile(..., tables);
+
+ The tables are built in memory that is obtained via
+ pcre_malloc. The pointer that is passed to pcre_compile is
+ saved with the compiled pattern, and the same tables are
+ used via this pointer by pcre_study() and pcre_exec(). Thus
+ for any single pattern, compilation, studying and matching
+ all happen in the same locale, but different patterns can be
+ compiled in different locales. It is the caller's responsi-
+ bility to ensure that the memory containing the tables
+ remains available for as long as it is needed.
+
+
+
+INFORMATION ABOUT A PATTERN
+ The pcre_info() function returns information about a com-
+ piled pattern. Its yield is the number of capturing subpat-
+ terns, or one of the following negative numbers:
+
+ PCRE_ERROR_NULL the argument code was NULL
+ PCRE_ERROR_BADMAGIC the "magic number" was not found
+
+ If the optptr argument is not NULL, a copy of the options
+ with which the pattern was compiled is placed in the integer
+ it points to. These option bits are those specified in the
+ call to pcre_compile(), modified by any top-level option
+ settings within the pattern itself, and with the
+ PCRE_ANCHORED bit set if the form of the pattern implies
+ that it can match only at the start of a subject string.
+
+ 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. If there is a fixed
+ first character, e.g. from a pattern such as
+ (cat|cow|coyote), then it is returned in the integer pointed
+ to by firstcharptr. Otherwise, if either
+
+ (a) the pattern was compiled with the PCRE_MULTILINE option,
+ and every branch starts with "^", or
+
+ (b) every branch of the pattern starts with ".*" and
+ PCRE_DOTALL is not set (if it were set, the pattern would be
+ anchored),
+ then -1 is returned, indicating that the pattern matches
+ only at the start of a subject string or after any "\n"
+ within the string. Otherwise -2 is returned.
+
+
+
+MATCHING A PATTERN
+ The function pcre_exec() is called to match a subject string
+ against a pre-compiled pattern, which is passed in the code
+ argument. If the pattern has been studied, the result of the
+ study should be passed in the extra argument. Otherwise this
+ must be NULL.
+
+ The PCRE_ANCHORED option can be passed in the options argu-
+ ment, whose unused bits must be zero. However, if a pattern
+ was compiled with PCRE_ANCHORED, or turned out to be
+ anchored by virtue of its contents, it cannot be made
+ unachored at matching time.
+
+ There are also three further options that can be set only at
+ matching time:
+
+ PCRE_NOTBOL
+
+ The first character of the string is not the beginning of a
+ line, so the circumflex metacharacter should not match
+ before it. Setting this without PCRE_MULTILINE (at compile
+ time) causes circumflex never to match.
+
+ PCRE_NOTEOL
+
+ The end of the string is not the end of a line, so the dol-
+ lar metacharacter should not match it nor (except in multi-
+ line mode) a newline immediately before it. Setting this
+ without PCRE_MULTILINE (at compile time) causes dollar never
+ to match.
+
+ PCRE_NOTEMPTY
+
+ An empty string is not considered to be a valid match if
+ this option is set. If there are alternatives in the pat-
+ tern, they are tried. If all the alternatives match the
+ empty string, the entire match fails. For example, if the
+ pattern
+
+ a?b?
+
+ is applied to a string not beginning with "a" or "b", it
+ matches the empty string at the start of the subject. With
+ PCRE_NOTEMPTY set, this match is not valid, so PCRE searches
+ further into the string for occurrences of "a" or "b". Perl
+ has no direct equivalent of this option, but it makes a
+ special case of a pattern match of the empty string within
+ its split() function, or when using the /g modifier. Using
+ PCRE_NOTEMPTY it is possible to emulate this behaviour.
+
+ The subject string is passed as a pointer in subject, a
+ length in length, and a starting offset in startoffset.
+ Unlike the pattern string, it may contain binary zero char-
+ acters. When the starting offset is zero, the search for a
+ match starts at the beginning of the subject, and this is by
+ far the most common case.
+
+ A non-zero starting offset is useful when searching for
+ another match in the same subject by calling pcre_exec()
+ again after a previous success. Setting startoffset differs
+ from just passing over a shortened string and setting
+ PCRE_NOTBOL in the case of a pattern that begins with any
+ kind of lookbehind. For example, consider the pattern
+
+ \Biss\B
+
+ which finds occurrences of "iss" in the middle of words. (\B
+ matches only if the current position in the subject is not a
+ word boundary.) When applied to the string "Mississipi" the
+ first call to pcre_exec() finds the first occurrence. If
+ pcre_exec() is called again with just the remainder of the
+ subject, namely "issipi", it does not match, because \B is
+ always false at the start of the subject, which is deemed to
+ be a word boundary. However, if pcre_exec() is passed the
+ entire string again, but with startoffset set to 4, it finds
+ the second occurrence of "iss" because it is able to look
+ behind the starting point to discover that it is preceded by
+ a letter.
+
+ If a non-zero starting offset is passed when the pattern is
+ anchored, one attempt to match at the given offset is tried.
+ This can only succeed if the pattern does not require the
+ match to be at the start of the subject.
+
+ In general, a pattern matches a certain portion of the sub-
+ ject, and in addition, further substrings from the subject
+ may be picked out by parts of the pattern. Following the
+ usage in Jeffrey Friedl's book, this is called "capturing"
+ in what follows, and the phrase "capturing subpattern" is
+ used for a fragment of a pattern that picks out a substring.
+ PCRE supports several other kinds of parenthesized subpat-
+ tern that do not cause substrings to be captured.
+
+ Captured substrings are returned to the caller via a vector
+ of integer offsets whose address is passed in ovector. The
+ number of elements in the vector is passed in ovecsize. The
+ first two-thirds of the vector is used to pass back captured
+ substrings, each substring using a pair of integers. The
+ remaining third of the vector is used as workspace by
+ pcre_exec() while matching capturing subpatterns, and is not
+ available for passing back information. The length passed in
+ ovecsize should always be a multiple of three. If it is not,
+ it is rounded down.
+
+ When a match has been successful, information about captured
+ substrings is returned in pairs of integers, starting at the
+ beginning of ovector, and continuing up to two-thirds of its
+ length at the most. The first element of a pair is set to
+ the offset of the first character in a substring, and the
+ second is set to the offset of the first character after the
+ end of a substring. The first pair, ovector[0] and ovec-
+ tor[1], identify the portion of the subject string matched
+ by the entire pattern. The next pair is used for the first
+ capturing subpattern, and so on. The value returned by
+ pcre_exec() is the number of pairs that have been set. If
+ there are no capturing subpatterns, the return value from a
+ successful match is 1, indicating that just the first pair
+ of offsets has been set.
+
+ Some convenience functions are provided for extracting the
+ captured substrings as separate strings. These are described
+ in the following section.
+
+ It is possible for an capturing subpattern number n+1 to
+ match some part of the subject when subpattern n has not
+ been used at all. For example, if the string "abc" is
+ matched against the pattern (a|(z))(bc) subpatterns 1 and 3
+ are matched, but 2 is not. When this happens, both offset
+ values corresponding to the unused subpattern are set to -1.
+
+ If a capturing subpattern is matched repeatedly, it is the
+ last portion of the string that it matched that gets
+ returned.
+
+ If the vector is too small to hold all the captured sub-
+ strings, it is used as far as possible (up to two-thirds of
+ its length), and the function returns a value of zero. In
+ particular, if the substring offsets are not of interest,
+ pcre_exec() may be called with ovector passed as NULL and
+ ovecsize as zero. However, if the pattern contains back
+ references and the ovector isn't big enough to remember the
+ related substrings, PCRE has to get additional memory for
+ use during matching. Thus it is usually advisable to supply
+ an ovector.
+
+ Note that pcre_info() can be used to find out how many cap-
+ turing subpatterns there are in a compiled pattern. The
+ smallest size for ovector that will allow for n captured
+ substrings in addition to the offsets of the substring
+ matched by the whole pattern is (n+1)*3.
+ If pcre_exec() fails, it returns a negative number. The fol-
+ lowing are defined in the header file:
+
+ PCRE_ERROR_NOMATCH (-1)
+
+ The subject string did not match the pattern.
+
+ PCRE_ERROR_NULL (-2)
+
+ Either code or subject was passed as NULL, or ovector was
+ NULL and ovecsize was not zero.
+
+ PCRE_ERROR_BADOPTION (-3)
+
+ An unrecognized bit was set in the options argument.
+
+ PCRE_ERROR_BADMAGIC (-4)
+
+ PCRE stores a 4-byte "magic number" at the start of the com-
+ piled code, to catch the case when it is passed a junk
+ pointer. This is the error it gives when the magic number
+ isn't present.
+
+ PCRE_ERROR_UNKNOWN_NODE (-5)
+
+ While running the pattern match, an unknown item was encoun-
+ tered in the compiled pattern. This error could be caused by
+ a bug in PCRE or by overwriting of the compiled pattern.
+
+ PCRE_ERROR_NOMEMORY (-6)
+
+ If a pattern contains back references, but the ovector that
+ is passed to pcre_exec() is not big enough to remember the
+ referenced substrings, PCRE gets a block of memory at the
+ start of matching to use for this purpose. If the call via
+ pcre_malloc() fails, this error is given. The memory is
+ freed at the end of matching.
+
+
+
+EXTRACTING CAPTURED SUBSTRINGS
+ Captured substrings can be accessed directly by using the
+ offsets returned by pcre_exec() in ovector. For convenience,
+ the functions pcre_copy_substring(), pcre_get_substring(),
+ and pcre_get_substring_list() are provided for extracting
+ captured substrings as new, separate, zero-terminated
+ strings. A substring that contains a binary zero is
+ correctly extracted and has a further zero added on the end,
+ but the result does not, of course, function as a C string.
+
+ The first three arguments are the same for all three func-
+ tions: subject is the subject string which has just been
+ successfully matched, ovector is a pointer to the vector of
+ integer offsets that was passed to pcre_exec(), and
+ stringcount is the number of substrings that were captured
+ by the match, including the substring that matched the
+ entire regular expression. This is the value returned by
+ pcre_exec if it is greater than zero. If pcre_exec()
+ returned zero, indicating that it ran out of space in ovec-
+ tor, then the value passed as stringcount should be the size
+ of the vector divided by three.
+
+ The functions pcre_copy_substring() and pcre_get_substring()
+ extract a single substring, whose number is given as string-
+ number. A value of zero extracts the substring that matched
+ the entire pattern, while higher values extract the captured
+ substrings. For pcre_copy_substring(), the string is placed
+ in buffer, whose length is given by buffersize, while for
+ pcre_get_substring() a new block of store is obtained via
+ pcre_malloc, and its address is returned via stringptr. The
+ yield of the function is the length of the string, not
+ including the terminating zero, or one of
+
+ PCRE_ERROR_NOMEMORY (-6)
+
+ The buffer was too small for pcre_copy_substring(), or the
+ attempt to get memory failed for pcre_get_substring().
+
+ PCRE_ERROR_NOSUBSTRING (-7)
+
+ There is no substring whose number is stringnumber.
+
+ The pcre_get_substring_list() function extracts all avail-
+ able substrings and builds a list of pointers to them. All
+ this is done in a single block of memory which is obtained
+ via pcre_malloc. The address of the memory block is returned
+ via listptr, which is also the start of the list of string
+ pointers. The end of the list is marked by a NULL pointer.
+ The yield of the function is zero if all went well, or
+
+ PCRE_ERROR_NOMEMORY (-6)
+
+ if the attempt to get the memory block failed.
+
+ When any of these functions encounter a substring that is
+ unset, which can happen when capturing subpattern number n+1
+ matches some part of the subject, but subpattern n has not
+ been used at all, they return an empty string. This can be
+ distinguished from a genuine zero-length substring by
+ inspecting the appropriate offset in ovector, which is nega-
+ tive for unset substrings.
+
+
+
+LIMITATIONS
+ There are some size limitations in PCRE but it is hoped that
+ they will never in practice be relevant. The maximum length
+ of a compiled pattern is 65539 (sic) bytes. All values in
+ repeating quantifiers must be less than 65536. The maximum
+ number of capturing subpatterns is 99. The maximum number
+ of all parenthesized subpatterns, including capturing sub-
+ patterns, assertions, and other types of subpattern, is 200.
+
+ The maximum length of a subject string is the largest posi-
+ tive number that an integer variable can hold. However, PCRE
+ uses recursion to handle subpatterns and indefinite repeti-
+ tion. This means that the available stack space may limit
+ the size of a subject string that can be processed by cer-
+ tain patterns.
+
+
+
+DIFFERENCES FROM PERL
+ The differences described here are with respect to Perl
+ 5.005.
+
+ 1. By default, a whitespace character is any character that
+ the C library function isspace() recognizes, though it is
+ possible to compile PCRE with alternative character type
+ tables. Normally isspace() matches space, formfeed, newline,
+ carriage return, horizontal tab, and vertical tab. Perl 5 no
+ longer includes vertical tab in its set of whitespace char-
+ acters. The \v escape that was in the Perl documentation for
+ a long time was never in fact recognized. However, the char-
+ acter itself was treated as whitespace at least up to 5.002.
+ In 5.004 and 5.005 it does not match \s.
+
+ 2. PCRE does not allow repeat quantifiers on lookahead
+ assertions. Perl permits them, but they do not mean what you
+ might think. For example, (?!a){3} does not assert that the
+ next three characters are not "a". It just asserts that the
+ next character is not "a" three times.
+
+ 3. Capturing subpatterns that occur inside negative looka-
+ head assertions are counted, but their entries in the
+ offsets vector are never set. Perl sets its numerical vari-
+ ables from any such patterns that are matched before the
+ assertion fails to match something (thereby succeeding), but
+ only if the negative lookahead assertion contains just one
+ branch.
+
+ 4. Though binary zero characters are supported in the sub-
+ ject string, they are not allowed in a pattern string
+ because it is passed as a normal C string, terminated by
+ zero. The escape sequence "\0" can be used in the pattern to
+ represent a binary zero.
+ 5. The following Perl escape sequences are not supported:
+ \l, \u, \L, \U, \E, \Q. In fact these are implemented by
+ Perl's general string-handling and are not part of its pat-
+ tern matching engine.
+
+ 6. The Perl \G assertion is not supported as it is not
+ relevant to single pattern matches.
+
+ 7. Fairly obviously, PCRE does not support the (?{code})
+ construction.
+
+ 8. There are at the time of writing some oddities in Perl
+ 5.005_02 concerned with the settings of captured strings
+ when part of a pattern is repeated. For example, matching
+ "aba" against the pattern /^(a(b)?)+$/ sets $2 to the value
+ "b", but matching "aabbaa" against /^(aa(bb)?)+$/ leaves $2
+ unset. However, if the pattern is changed to
+ /^(aa(b(b))?)+$/ then $2 (and $3) get set.
+
+ In Perl 5.004 $2 is set in both cases, and that is also true
+ of PCRE. If in the future Perl changes to a consistent state
+ that is different, PCRE may change to follow.
+
+ 9. Another as yet unresolved discrepancy is that in Perl
+ 5.005_02 the pattern /^(a)?(?(1)a|b)+$/ matches the string
+ "a", whereas in PCRE it does not. However, in both Perl and
+ PCRE /^(a)?a/ matched against "a" leaves $1 unset.
+
+ 10. PCRE provides some extensions to the Perl regular
+ expression facilities:
+
+ (a) Although lookbehind assertions must match fixed length
+ strings, each alternative branch of a lookbehind assertion
+ can match a different length of string. Perl 5.005 requires
+ them all to have the same length.
+
+ (b) If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not
+ set, the $ meta- character matches only at the very end of
+ the string.
+
+ (c) If PCRE_EXTRA is set, a backslash followed by a letter
+ with no special meaning is faulted.
+
+ (d) If PCRE_UNGREEDY is set, the greediness of the repeti-
+ tion quantifiers is inverted, that is, by default they are
+ not greedy, but if followed by a question mark they are.
+
+ (e) PCRE_ANCHORED can be used to force a pattern to be tried
+ only at the start of the subject.
+
+ (f) The PCRE_NOTBOL, PCRE_NOTEOL, and PCRE_NOTEMPTY options
+ for pcre_exec() have no Perl equivalents.
+
+
+
+REGULAR EXPRESSION DETAILS
+ The syntax and semantics of the regular expressions sup-
+ ported by PCRE are described below. Regular expressions are
+ also described in the Perl documentation and in a number of
+ other books, some of which have copious examples. Jeffrey
+ Friedl's "Mastering Regular Expressions", published by
+ O'Reilly (ISBN 1-56592-257-3), covers them in great detail.
+ The description here is intended as reference documentation.
+
+ A regular expression is a pattern that is matched against a
+ subject string from left to right. Most characters stand for
+ themselves in a pattern, and match the corresponding charac-
+ ters in the subject. As a trivial example, the pattern
+
+ The quick brown fox
+
+ matches a portion of a subject string that is identical to
+ itself. The power of regular expressions comes from the
+ ability to include alternatives and repetitions in the pat-
+ tern. These are encoded in the pattern by the use of meta-
+ characters, which do not stand for themselves but instead
+ are interpreted in some special way.
+
+ There are two different sets of meta-characters: those that
+ are recognized anywhere in the pattern except within square
+ brackets, and those that are recognized in square brackets.
+ Outside square brackets, the meta-characters are as follows:
+
+ \ general escape character with several uses
+ ^ assert start of subject (or line, in multiline
+ mode)
+ $ assert end of subject (or line, in multiline mode)
+ . match any character except newline (by default)
+ [ start character class definition
+ | start of alternative branch
+ ( start subpattern
+ ) end subpattern
+ ? extends the meaning of (
+ also 0 or 1 quantifier
+ also quantifier minimizer
+ * 0 or more quantifier
+ + 1 or more quantifier
+ { start min/max quantifier
+
+ Part of a pattern that is in square brackets is called a
+ "character class". In a character class the only meta-
+ characters are:
+
+ \ general escape character
+ ^ negate the class, but only if the first character
+ - indicates character range
+ ] terminates the character class
+
+ The following sections describe the use of each of the
+ meta-characters.
+
+
+
+BACKSLASH
+ The backslash character has several uses. Firstly, if it is
+ followed by a non-alphameric character, it takes away any
+ special meaning that character may have. This use of
+ backslash as an escape character applies both inside and
+ outside character classes.
+
+ For example, if you want to match a "*" character, you write
+ "\*" in the pattern. This applies whether or not the follow-
+ ing character would otherwise be interpreted as a meta-
+ character, so it is always safe to precede a non-alphameric
+ with "\" to specify that it stands for itself. In particu-
+ lar, if you want to match a backslash, you write "\\".
+
+ If a pattern is compiled with the PCRE_EXTENDED option, whi-
+ tespace in the pattern (other than in a character class) and
+ characters between a "#" outside a character class and the
+ next newline character are ignored. An escaping backslash
+ can be used to include a whitespace or "#" character as part
+ of the pattern.
+
+ A second use of backslash provides a way of encoding non-
+ printing characters in patterns in a visible manner. There
+ is no restriction on the appearance of non-printing charac-
+ ters, apart from the binary zero that terminates a pattern,
+ but when a pattern is being prepared by text editing, it is
+ usually easier to use one of the following escape sequences
+ than the binary character it represents:
+
+ \a alarm, that is, the BEL character (hex 07)
+ \cx "control-x", where x is any character
+ \e escape (hex 1B)
+ \f formfeed (hex 0C)
+ \n newline (hex 0A)
+ \r carriage return (hex 0D)
+ \t tab (hex 09)
+ \xhh character with hex code hh
+ \ddd character with octal code ddd, or backreference
+
+ The precise effect of "\cx" is as follows: if "x" is a lower
+ case letter, it is converted to upper case. Then bit 6 of
+ the character (hex 40) is inverted. Thus "\cz" becomes hex
+ 1A, but "\c{" becomes hex 3B, while "\c;" becomes hex 7B.
+
+ After "\x", up to two hexadecimal digits are read (letters
+ can be in upper or lower case).
+
+ After "\0" up to two further octal digits are read. In both
+ cases, if there are fewer than two digits, just those that
+ are present are used. Thus the sequence "\0\x\07" specifies
+ two binary zeros followed by a BEL character. Make sure you
+ supply two digits after the initial zero if the character
+ that follows is itself an octal digit.
+
+ The handling of a backslash followed by a digit other than 0
+ is complicated. Outside a character class, PCRE reads it
+ and any following digits as a decimal number. If the number
+ is less than 10, or if there have been at least that many
+ previous capturing left parentheses in the expression, the
+ entire sequence is taken as a back reference. A description
+ of how this works is given later, following the discussion
+ of parenthesized subpatterns.
+
+ Inside a character class, or if the decimal number is
+ greater than 9 and there have not been that many capturing
+ subpatterns, PCRE re-reads up to three octal digits follow-
+ ing the backslash, and generates a single byte from the
+ least significant 8 bits of the value. Any subsequent digits
+ stand for themselves. For example:
+
+ \040 is another way of writing a space
+ \40 is the same, provided there are fewer than 40
+ previous capturing subpatterns
+ \7 is always a back reference
+ \11 might be a back reference, or another way of
+ writing a tab
+ \011 is always a tab
+ \0113 is a tab followed by the character "3"
+ \113 is the character with octal code 113 (since there
+ can be no more than 99 back references)
+ \377 is a byte consisting entirely of 1 bits
+ \81 is either a back reference, or a binary zero
+ followed by the two characters "8" and "1"
+
+ Note that octal values of 100 or greater must not be intro-
+ duced by a leading zero, because no more than three octal
+ digits are ever read.
+
+ All the sequences that define a single byte value can be
+ used both inside and outside character classes. In addition,
+ inside a character class, the sequence "\b" is interpreted
+ as the backspace character (hex 08). Outside a character
+ class it has a different meaning (see below).
+
+ The third use of backslash is for specifying generic charac-
+ ter types:
+
+ \d any decimal digit
+ \D any character that is not a decimal digit
+ any whitespace character
+ \S any character that is not a whitespace character
+ \w any "word" character
+ \W any "non-word" character
+
+ Each pair of escape sequences partitions the complete set of
+ characters into two disjoint sets. Any given character
+ matches one, and only one, of each pair.
+
+ A "word" character is any letter or digit or the underscore
+ character, that is, any character which can be part of a
+ Perl "word". The definition of letters and digits is con-
+ trolled by PCRE's character tables, and may vary if locale-
+ specific matching is taking place (see "Locale support"
+ above). For example, in the "fr" (French) locale, some char-
+ acter codes greater than 128 are used for accented letters,
+ and these are matched by \w.
+
+ These character type sequences can appear both inside and
+ outside character classes. They each match one character of
+ the appropriate type. If the current matching point is at
+ the end of the subject string, all of them fail, since there
+ is no character to match.
+
+ The fourth use of backslash is for certain simple asser-
+ tions. An assertion specifies a condition that has to be met
+ at a particular point in a match, without consuming any
+ characters from the subject string. The use of subpatterns
+ for more complicated assertions is described below. The
+ backslashed assertions are
+
+ \b word boundary
+ \B not a word boundary
+ \A start of subject (independent of multiline mode)
+ \Z end of subject or newline at end (independent of
+ multiline mode)
+ \z end of subject (independent of multiline mode)
+
+ These assertions may not appear in character classes (but
+ note that "\b" has a different meaning, namely the backspace
+ character, inside a character class).
+
+ A word boundary is a position in the subject string where
+ the current character and the previous character do not both
+ match \w or \W (i.e. one matches \w and the other matches
+ \W), or the start or end of the string if the first or last
+ character matches \w, respectively.
+
+ The \A, \Z, and \z assertions differ from the traditional
+ circumflex and dollar (described below) in that they only
+ ever match at the very start and end of the subject string,
+ whatever options are set. They are not affected by the
+ PCRE_NOTBOL or PCRE_NOTEOL options. If the startoffset argu-
+ ment of pcre_exec() is non-zero, \A can never match. The
+ difference between \Z and \z is that \Z matches before a
+ newline that is the last character of the string as well as
+ at the end of the string, whereas \z matches only at the
+ end.
+
+
+
+CIRCUMFLEX AND DOLLAR
+ Outside a character class, in the default matching mode, the
+ circumflex character is an assertion which is true only if
+ the current matching point is at the start of the subject
+ string. If the startoffset argument of pcre_exec() is non-
+ zero, circumflex can never match. Inside a character class,
+ circumflex has an entirely different meaning (see below).
+
+ Circumflex need not be the first character of the pattern if
+ a number of alternatives are involved, but it should be the
+ first thing in each alternative in which it appears if the
+ pattern is ever to match that branch. If all possible alter-
+ natives start with a circumflex, that is, if the pattern is
+ constrained to match only at the start of the subject, it is
+ said to be an "anchored" pattern. (There are also other con-
+ structs that can cause a pattern to be anchored.)
+
+ A dollar character is an assertion which is true only if the
+ current matching point is at the end of the subject string,
+ or immediately before a newline character that is the last
+ character in the string (by default). Dollar need not be the
+ last character of the pattern if a number of alternatives
+ are involved, but it should be the last item in any branch
+ in which it appears. Dollar has no special meaning in a
+ character class.
+
+ The meaning of dollar can be changed so that it matches only
+ at the very end of the string, by setting the
+ PCRE_DOLLAR_ENDONLY option at compile or matching time. This
+ does not affect the \Z assertion.
+
+ The meanings of the circumflex and dollar characters are
+ changed if the PCRE_MULTILINE option is set. When this is
+ the case, they match immediately after and immediately
+ before an internal "\n" character, respectively, in addition
+ to matching at the start and end of the subject string. For
+ example, the pattern /^abc$/ matches the subject string
+ "def\nabc" in multiline mode, but not otherwise. Conse-
+ quently, patterns that are anchored in single line mode
+ because all branches start with "^" are not anchored in mul-
+ tiline mode, and a match for circumflex is possible when the
+ startoffset argument of pcre_exec() is non-zero. The
+ PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is
+ set.
+
+ Note that the sequences \A, \Z, and \z can be used to match
+ the start and end of the subject in both modes, and if all
+ branches of a pattern start with \A is it always anchored,
+ whether PCRE_MULTILINE is set or not.
+
+
+
+FULL STOP (PERIOD, DOT)
+ Outside a character class, a dot in the pattern matches any
+ one character in the subject, including a non-printing char-
+ acter, but not (by default) newline. If the PCRE_DOTALL
+ option is set, then dots match newlines as well. The han-
+ dling of dot is entirely independent of the handling of cir-
+ cumflex and dollar, the only relationship being that they
+ both involve newline characters. Dot has no special meaning
+ in a character class.
+
+
+
+SQUARE BRACKETS
+ An opening square bracket introduces a character class, ter-
+ minated by a closing square bracket. A closing square
+ bracket on its own is not special. If a closing square
+ bracket is required as a member of the class, it should be
+ the first data character in the class (after an initial cir-
+ cumflex, if present) or escaped with a backslash.
+
+ A character class matches a single character in the subject;
+ the character must be in the set of characters defined by
+ the class, unless the first character in the class is a cir-
+ cumflex, in which case the subject character must not be in
+ the set defined by the class. If a circumflex is actually
+ required as a member of the class, ensure it is not the
+ first character, or escape it with a backslash.
+
+ For example, the character class [aeiou] matches any lower
+ case vowel, while [^aeiou] matches any character that is not
+ a lower case vowel. Note that a circumflex is just a con-
+ venient notation for specifying the characters which are in
+ the class by enumerating those that are not. It is not an
+ assertion: it still consumes a character from the subject
+ string, and fails if the current pointer is at the end of
+ the string.
+
+ When caseless matching is set, any letters in a class
+ represent both their upper case and lower case versions, so
+ for example, a caseless [aeiou] matches "A" as well as "a",
+ and a caseless [^aeiou] does not match "A", whereas a case-
+ ful version would.
+
+ The newline character is never treated in any special way in
+ character classes, whatever the setting of the PCRE_DOTALL
+ or PCRE_MULTILINE options is. A class such as [^a] will
+ always match a newline.
+
+ The minus (hyphen) character can be used to specify a range
+ of characters in a character class. For example, [d-m]
+ matches any letter between d and m, inclusive. If a minus
+ character is required in a class, it must be escaped with a
+ backslash or appear in a position where it cannot be inter-
+ preted as indicating a range, typically as the first or last
+ character in the class.
+
+ It is not possible to have the literal character "]" as the
+ end character of a range. A pattern such as [W-]46] is
+ interpreted as a class of two characters ("W" and "-") fol-
+ lowed by a literal string "46]", so it would match "W46]" or
+ "-46]". However, if the "]" is escaped with a backslash it
+ is interpreted as the end of range, so [W-\]46] is inter-
+ preted as a single class containing a range followed by two
+ separate characters. The octal or hexadecimal representation
+ of "]" can also be used to end a range.
+
+ Ranges operate in ASCII collating sequence. They can also be
+ used for characters specified numerically, for example
+ [\000-\037]. If a range that includes letters is used when
+ caseless matching is set, it matches the letters in either
+ case. For example, [W-c] is equivalent to [][\^_`wxyzabc],
+ matched caselessly, and if character tables for the "fr"
+ locale are in use, [\xc8-\xcb] matches accented E characters
+ in both cases.
+
+ The character types \d, \D, \s, \S, \w, and \W may also
+ appear in a character class, and add the characters that
+ they match to the class. For example, [\dABCDEF] matches any
+ hexadecimal digit. A circumflex can conveniently be used
+ with the upper case character types to specify a more res-
+ tricted set of characters than the matching lower case type.
+ For example, the class [^\W_] matches any letter or digit,
+ but not underscore.
+
+ All non-alphameric characters other than \, -, ^ (at the
+ start) and the terminating ] are non-special in character
+ classes, but it does no harm if they are escaped.
+
+
+
+VERTICAL BAR
+ Vertical bar characters are used to separate alternative
+ patterns. For example, the pattern
+
+ gilbert|sullivan
+
+ matches either "gilbert" or "sullivan". Any number of alter-
+ natives may appear, and an empty alternative is permitted
+ (matching the empty string). The matching process tries
+ each alternative in turn, from left to right, and the first
+ one that succeeds is used. If the alternatives are within a
+ subpattern (defined below), "succeeds" means matching the
+ rest of the main pattern as well as the alternative in the
+ subpattern.
+
+
+
+INTERNAL OPTION SETTING
+ The settings of PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL,
+ and PCRE_EXTENDED can be changed from within the pattern by
+ a sequence of Perl option letters enclosed between "(?" and
+ ")". The option letters are
+
+ i for PCRE_CASELESS
+ m for PCRE_MULTILINE
+ s for PCRE_DOTALL
+ x for PCRE_EXTENDED
+
+ For example, (?im) sets caseless, multiline matching. It is
+ also possible to unset these options by preceding the letter
+ with a hyphen, and a combined setting and unsetting such as
+ (?im-sx), which sets PCRE_CASELESS and PCRE_MULTILINE while
+ unsetting PCRE_DOTALL and PCRE_EXTENDED, is also permitted.
+ If a letter appears both before and after the hyphen, the
+ option is unset.
+
+ The scope of these option changes depends on where in the
+ pattern the setting occurs. For settings that are outside
+ any subpattern (defined below), the effect is the same as if
+ the options were set or unset at the start of matching. The
+ following patterns all behave in exactly the same way:
+
+ (?i)abc
+ a(?i)bc
+ ab(?i)c
+ abc(?i)
+
+ which in turn is the same as compiling the pattern abc with
+ PCRE_CASELESS set. In other words, such "top level" set-
+ tings apply to the whole pattern (unless there are other
+ changes inside subpatterns). If there is more than one set-
+ ting of the same option at top level, the rightmost setting
+ is used.
+
+ If an option change occurs inside a subpattern, the effect
+ is different. This is a change of behaviour in Perl 5.005.
+ An option change inside a subpattern affects only that part
+ of the subpattern that follows it, so
+
+ (a(?i)b)c
+
+ matches abc and aBc and no other strings (assuming
+ PCRE_CASELESS is not used). By this means, options can be
+ made to have different settings in different parts of the
+ pattern. Any changes made in one alternative do carry on
+ into subsequent branches within the same subpattern. For
+ example,
+
+ (a(?i)b|c)
+
+ matches "ab", "aB", "c", and "C", even though when matching
+ "C" the first branch is abandoned before the option setting.
+ This is because the effects of option settings happen at
+ compile time. There would be some very weird behaviour oth-
+ erwise.
+
+ The PCRE-specific options PCRE_UNGREEDY and PCRE_EXTRA can
+ be changed in the same way as the Perl-compatible options by
+ using the characters U and X respectively. The (?X) flag
+ setting is special in that it must always occur earlier in
+ the pattern than any of the additional features it turns on,
+ even when it is at top level. It is best put at the start.
+
+
+
+SUBPATTERNS
+ Subpatterns are delimited by parentheses (round brackets),
+ which can be nested. Marking part of a pattern as a subpat-
+ tern does two things:
+
+ 1. It localizes a set of alternatives. For example, the pat-
+ tern
+
+ cat(aract|erpillar|)
+
+ matches one of the words "cat", "cataract", or "caterpil-
+ lar". Without the parentheses, it would match "cataract",
+ "erpillar" or the empty string.
+
+ 2. It sets up the subpattern as a capturing subpattern (as
+ defined above). When the whole pattern matches, that por-
+ tion of the subject string that matched the subpattern is
+ passed back to the caller via the ovector argument of
+ pcre_exec(). Opening parentheses are counted from left to
+ right (starting from 1) to obtain the numbers of the captur-
+ ing subpatterns.
+
+ For example, if the string "the red king" is matched against
+ the pattern
+
+ the ((red|white) (king|queen))
+
+ the captured substrings are "red king", "red", and "king",
+ and are numbered 1, 2, and 3.
+
+ The fact that plain parentheses fulfil two functions is not
+ always helpful. There are often times when a grouping sub-
+ pattern is required without a capturing requirement. If an
+ opening parenthesis is followed by "?:", the subpattern does
+ not do any capturing, and is not counted when computing the
+ number of any subsequent capturing subpatterns. For example,
+ if the string "the white queen" is matched against the pat-
+ tern
+
+ the ((?:red|white) (king|queen))
+
+ the captured substrings are "white queen" and "queen", and
+ are numbered 1 and 2. The maximum number of captured sub-
+ strings is 99, and the maximum number of all subpatterns,
+ both capturing and non-capturing, is 200.
+
+ As a convenient shorthand, if any option settings are
+ required at the start of a non-capturing subpattern, the
+ option letters may appear between the "?" and the ":". Thus
+ the two patterns
+
+ (?i:saturday|sunday)
+ (?:(?i)saturday|sunday)
+
+ match exactly the same set of strings. Because alternative
+ branches are tried from left to right, and options are not
+ reset until the end of the subpattern is reached, an option
+ setting in one branch does affect subsequent branches, so
+ the above patterns match "SUNDAY" as well as "Saturday".
+
+
+
+REPETITION
+ Repetition is specified by quantifiers, which can follow any
+ of the following items:
+
+ a single character, possibly escaped
+ the . metacharacter
+ a character class
+ a back reference (see next section)
+ a parenthesized subpattern (unless it is an assertion -
+ see below)
+
+ The general repetition quantifier specifies a minimum and
+ maximum number of permitted matches, by giving the two
+ numbers in curly brackets (braces), separated by a comma.
+ The numbers must be less than 65536, and the first must be
+ less than or equal to the second. For example:
+
+ z{2,4}
+
+ matches "zz", "zzz", or "zzzz". A closing brace on its own
+ is not a special character. If the second number is omitted,
+ but the comma is present, there is no upper limit; if the
+ second number and the comma are both omitted, the quantifier
+ specifies an exact number of required matches. Thus
+
+ [aeiou]{3,}
+
+ matches at least 3 successive vowels, but may match many
+ more, while
+
+ \d{8}
+
+ matches exactly 8 digits. An opening curly bracket that
+ appears in a position where a quantifier is not allowed, or
+ one that does not match the syntax of a quantifier, is taken
+ as a literal character. For example, {,6} is not a quantif-
+ ier, but a literal string of four characters.
+
+ The quantifier {0} is permitted, causing the expression to
+ behave as if the previous item and the quantifier were not
+ present.
+
+ For convenience (and historical compatibility) the three
+ most common quantifiers have single-character abbreviations:
+
+ * is equivalent to {0,}
+ + is equivalent to {1,}
+ ? is equivalent to {0,1}
+
+ It is possible to construct infinite loops by following a
+ subpattern that can match no characters with a quantifier
+ that has no upper limit, for example:
+
+ (a?)*
+
+ Earlier versions of Perl and PCRE used to give an error at
+ compile time for such patterns. However, because there are
+ cases where this can be useful, such patterns are now
+ accepted, but if any repetition of the subpattern does in
+ fact match no characters, the loop is forcibly broken.
+
+ By default, the quantifiers are "greedy", that is, they
+ match as much as possible (up to the maximum number of per-
+ mitted times), without causing the rest of the pattern to
+ fail. The classic example of where this gives problems is in
+ trying to match comments in C programs. These appear between
+ the sequences /* and */ and within the sequence, individual
+ * and / characters may appear. An attempt to match C com-
+ ments by applying the pattern
+
+ /\*.*\*/
+
+ to the string
+
+ /* first command */ not comment /* second comment */
+
+ fails, because it matches the entire string due to the
+ greediness of the .* item.
+
+ However, if a quantifier is followed by a question mark,
+ then it ceases to be greedy, and instead matches the minimum
+ number of times possible, so the pattern
+
+ /\*.*?\*/
+
+ does the right thing with the C comments. The meaning of the
+ various quantifiers is not otherwise changed, just the pre-
+ ferred number of matches. Do not confuse this use of ques-
+ tion mark with its use as a quantifier in its own right.
+ Because it has two uses, it can sometimes appear doubled, as
+ in
+
+ \d??\d
+
+ which matches one digit by preference, but can match two if
+ that is the only way the rest of the pattern matches.
+
+ If the PCRE_UNGREEDY option is set (an option which is not
+ available in Perl) then the quantifiers are not greedy by
+ default, but individual ones can be made greedy by following
+ them with a question mark. In other words, it inverts the
+ default behaviour.
+
+ When a parenthesized subpattern is quantified with a minimum
+ repeat count that is greater than 1 or with a limited max-
+ imum, more store is required for the compiled pattern, in
+ proportion to the size of the minimum or maximum.
+
+ If a pattern starts with .* or .{0,} and the PCRE_DOTALL
+ option (equivalent to Perl's /s) is set, thus allowing the .
+ to match newlines, then the pattern is implicitly anchored,
+ because whatever follows will be tried against every charac-
+ ter position in the subject string, so there is no point in
+ retrying the overall match at any position after the first.
+ PCRE treats such a pattern as though it were preceded by \A.
+ In cases where it is known that the subject string contains
+ no newlines, it is worth setting PCRE_DOTALL when the pat-
+ tern begins with .* in order to obtain this optimization, or
+ alternatively using ^ to indicate anchoring explicitly.
+
+ When a capturing subpattern is repeated, the value captured
+ is the substring that matched the final iteration. For
+ example, after
+
+ (tweedle[dume]{3}\s*)+
+
+ has matched "tweedledum tweedledee" the value of the cap-
+ tured substring is "tweedledee". However, if there are
+ nested capturing subpatterns, the corresponding captured
+ values may have been set in previous iterations. For exam-
+ ple, after
+
+ /(a|(b))+/
+
+ matches "aba" the value of the second captured substring is
+ "b".
+
+
+
+BACK REFERENCES
+ Outside a character class, a backslash followed by a digit
+ greater than 0 (and possibly further digits) is a back
+ reference to a capturing subpattern earlier (i.e. to its
+ left) in the pattern, provided there have been that many
+ previous capturing left parentheses.
+
+ However, if the decimal number following the backslash is
+ less than 10, it is always taken as a back reference, and
+ causes an error only if there are not that many capturing
+ left parentheses in the entire pattern. In other words, the
+ parentheses that are referenced need not be to the left of
+ the reference for numbers less than 10. See the section
+ entitled "Backslash" above for further details of the han-
+ dling of digits following a backslash.
+
+ A back reference matches whatever actually matched the cap-
+ turing subpattern in the current subject string, rather than
+ anything matching the subpattern itself. So the pattern
+
+ (sens|respons)e and \1ibility
+
+ matches "sense and sensibility" and "response and responsi-
+ bility", but not "sense and responsibility". If caseful
+ matching is in force at the time of the back reference, then
+ the case of letters is relevant. For example,
+
+ ((?i)rah)\s+\1
+
+ matches "rah rah" and "RAH RAH", but not "RAH rah", even
+ though the original capturing subpattern is matched case-
+ lessly.
+
+ There may be more than one back reference to the same sub-
+ pattern. If a subpattern has not actually been used in a
+ particular match, then any back references to it always
+ fail. For example, the pattern
+
+ (a|(bc))\2
+
+ always fails if it starts to match "a" rather than "bc".
+ Because there may be up to 99 back references, all digits
+ following the backslash are taken as part of a potential
+ back reference number. If the pattern continues with a digit
+ character, then some delimiter must be used to terminate the
+ back reference. If the PCRE_EXTENDED option is set, this can
+ be whitespace. Otherwise an empty comment can be used.
+
+ A back reference that occurs inside the parentheses to which
+ it refers fails when the subpattern is first used, so, for
+ example, (a\1) never matches. However, such references can
+ be useful inside repeated subpatterns. For example, the pat-
+ tern
+
+ (a|b\1)+
+
+ matches any number of "a"s and also "aba", "ababaa" etc. At
+ each iteration of the subpattern, the back reference matches
+ the character string corresponding to the previous itera-
+ tion. In order for this to work, the pattern must be such
+ that the first iteration does not need to match the back
+ reference. This can be done using alternation, as in the
+ example above, or by a quantifier with a minimum of zero.
+
+
+
+ASSERTIONS
+ An assertion is a test on the characters following or
+ preceding the current matching point that does not actually
+ consume any characters. The simple assertions coded as \b,
+ \B, \A, \Z, \z, ^ and $ are described above. More compli-
+ cated assertions are coded as subpatterns. There are two
+ kinds: those that look ahead of the current position in the
+ subject string, and those that look behind it.
+
+ An assertion subpattern is matched in the normal way, except
+ that it does not cause the current matching position to be
+ changed. Lookahead assertions start with (?= for positive
+ assertions and (?! for negative assertions. For example,
+
+ \w+(?=;)
+
+ matches a word followed by a semicolon, but does not include
+ the semicolon in the match, and
+
+ foo(?!bar)
+
+ matches any occurrence of "foo" that is not followed by
+ "bar". Note that the apparently similar pattern
+
+ (?!foo)bar
+
+ does not find an occurrence of "bar" that is preceded by
+ something other than "foo"; it finds any occurrence of "bar"
+ whatsoever, because the assertion (?!foo) is always true
+ when the next three characters are "bar". A lookbehind
+ assertion is needed to achieve this effect.
+
+ Lookbehind assertions start with (?<= for positive asser-
+ tions and (?<! for negative assertions. For example,
+
+ (?<!foo)bar
+
+ does find an occurrence of "bar" that is not preceded by
+ "foo". The contents of a lookbehind assertion are restricted
+ such that all the strings it matches must have a fixed
+ length. However, if there are several alternatives, they do
+ not all have to have the same fixed length. Thus
+
+ (?<=bullock|donkey)
+
+ is permitted, but
+
+ (?<!dogs?|cats?)
+
+ causes an error at compile time. Branches that match dif-
+ ferent length strings are permitted only at the top level of
+ a lookbehind assertion. This is an extension compared with
+ Perl 5.005, which requires all branches to match the same
+ length of string. An assertion such as
+
+ (?<=ab(c|de))
+
+ is not permitted, because its single top-level branch can
+ match two different lengths, but it is acceptable if rewrit-
+ ten to use two top-level branches:
+
+ (?<=abc|abde)
+
+ The implementation of lookbehind assertions is, for each
+ alternative, to temporarily move the current position back
+ by the fixed width and then try to match. If there are
+ insufficient characters before the current position, the
+ match is deemed to fail. Lookbehinds in conjunction with
+ once-only subpatterns can be particularly useful for match-
+ ing at the ends of strings; an example is given at the end
+ of the section on once-only subpatterns.
+
+ Several assertions (of any sort) may occur in succession.
+ For example,
+
+ (?<=\d{3})(?<!999)foo
+
+ matches "foo" preceded by three digits that are not "999".
+ Notice that each of the assertions is applied independently
+ at the same point in the subject string. First there is a
+ check that the previous three characters are all digits,
+ then there is a check that the same three characters are not
+ "999". This pattern does not match "foo" preceded by six
+ characters, the first of which are digits and the last three
+ of which are not "999". For example, it doesn't match
+ "123abcfoo". A pattern to do that is
+
+ (?<=\d{3}...)(?<!999)foo
+
+ This time the first assertion looks at the preceding six
+ characters, checking that the first three are digits, and
+ then the second assertion checks that the preceding three
+ characters are not "999".
+
+ Assertions can be nested in any combination. For example,
+
+ (?<=(?<!foo)bar)baz
+
+ matches an occurrence of "baz" that is preceded by "bar"
+ which in turn is not preceded by "foo", while
+
+ (?<=\d{3}(?!999)...)foo
+
+ is another pattern which matches "foo" preceded by three
+ digits and any three characters that are not "999".
+
+ Assertion subpatterns are not capturing subpatterns, and may
+ not be repeated, because it makes no sense to assert the
+ same thing several times. If any kind of assertion contains
+ capturing subpatterns within it, these are counted for the
+ purposes of numbering the capturing subpatterns in the whole
+ pattern. However, substring capturing is carried out only
+ for positive assertions, because it does not make sense for
+ negative assertions.
+
+ Assertions count towards the maximum of 200 parenthesized
+ subpatterns.
+
+
+
+ONCE-ONLY SUBPATTERNS
+ With both maximizing and minimizing repetition, failure of
+ what follows normally causes the repeated item to be re-
+ evaluated to see if a different number of repeats allows the
+ rest of the pattern to match. Sometimes it is useful to
+ prevent this, either to change the nature of the match, or
+ to cause it fail earlier than it otherwise might, when the
+ author of the pattern knows there is no point in carrying
+ on.
+
+ Consider, for example, the pattern \d+foo when applied to
+ the subject line
+
+ 123456bar
+
+ After matching all 6 digits and then failing to match "foo",
+ the normal action of the matcher is to try again with only 5
+ digits matching the \d+ item, and then with 4, and so on,
+ before ultimately failing. Once-only subpatterns provide the
+ means for specifying that once a portion of the pattern has
+ matched, it is not to be re-evaluated in this way, so the
+ matcher would give up immediately on failing to match "foo"
+ the first time. The notation is another kind of special
+ parenthesis, starting with (?> as in this example:
+
+ (?>\d+)bar
+
+ This kind of parenthesis "locks up" the part of the pattern
+ it contains once it has matched, and a failure further into
+ the pattern is prevented from backtracking into it. Back-
+ tracking past it to previous items, however, works as nor-
+ mal.
+
+ An alternative description is that a subpattern of this type
+ matches the string of characters that an identical stan-
+ dalone pattern would match, if anchored at the current point
+ in the subject string.
+
+ Once-only subpatterns are not capturing subpatterns. Simple
+ cases such as the above example can be thought of as a max-
+ imizing repeat that must swallow everything it can. So,
+ while both \d+ and \d+? are prepared to adjust the number of
+ digits they match in order to make the rest of the pattern
+ match, (?>\d+) can only match an entire sequence of digits.
+
+ This construction can of course contain arbitrarily compli-
+ cated subpatterns, and it can be nested.
+
+ Once-only subpatterns can be used in conjunction with look-
+ behind assertions to specify efficient matching at the end
+ of the subject string. Consider a simple pattern such as
+
+ abcd$
+
+ when applied to a long string which does not match it.
+ Because matching proceeds from left to right, PCRE will look
+ for each "a" in the subject and then see if what follows
+ matches the rest of the pattern. If the pattern is specified
+ as
+
+ ^.*abcd$
+
+ then the initial .* matches the entire string at first, but
+ when this fails, 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 pat-
+ tern is written as
+
+ ^(?>.*)(?<=abcd)
+
+ then there can be no backtracking for the .* item; it can
+ match only the entire string. The subsequent lookbehind
+ assertion does a single test on the last four characters. If
+ it fails, the match fails immediately. For long strings,
+ this approach makes a significant difference to the process-
+ ing time.
+
+
+
+CONDITIONAL SUBPATTERNS
+ It is possible to cause the matching process to obey a sub-
+ pattern conditionally or to choose between two alternative
+ subpatterns, depending on the result of an assertion, or
+ whether a previous capturing subpattern matched or not. The
+ two possible forms of conditional subpattern are
+
+ (?(condition)yes-pattern)
+ (?(condition)yes-pattern|no-pattern)
+
+ If the condition is satisfied, the yes-pattern is used; oth-
+ erwise the no-pattern (if present) is used. If there are
+ more than two alternatives in the subpattern, a compile-time
+ error occurs.
+
+ There are two kinds of condition. If the text between the
+ parentheses consists of a sequence of digits, then the con-
+ dition is satisfied if the capturing subpattern of that
+ number has previously matched. Consider the following pat-
+ tern, which contains non-significant white space to make it
+ more readable (assume the PCRE_EXTENDED option) and to
+ divide it into three parts for ease of discussion:
+
+ ( \( )? [^()]+ (?(1) \) )
+
+ The first part matches an optional opening parenthesis, and
+ if that character is present, sets it as the first captured
+ substring. The second part matches one or more characters
+ that are not parentheses. The third part is a conditional
+ subpattern that tests whether the first set of parentheses
+ matched or not. If they did, that is, if subject started
+ with an opening parenthesis, the condition is true, and so
+ the yes-pattern is executed and a closing parenthesis is
+ required. Otherwise, since no-pattern is not present, the
+ subpattern matches nothing. In other words, this pattern
+ matches a sequence of non-parentheses, optionally enclosed
+ in parentheses.
+
+ If the condition is not a sequence of digits, it must be an
+ assertion. This may be a positive or negative lookahead or
+ lookbehind assertion. Consider this pattern, again contain-
+ ing non-significant white space, and with the two alterna-
+ tives on the second line:
+
+ (?(?=[^a-z]*[a-z])
+ \d{2}[a-z]{3}-\d{2} | \d{2}-\d{2}-\d{2} )
+
+ The condition is a positive lookahead assertion that matches
+ an optional sequence of non-letters followed by a letter. In
+ other words, it tests for the presence of at least one
+ letter in the subject. If a letter is found, the subject is
+ matched against the first alternative; otherwise it is
+ matched against the second. This pattern matches strings in
+ one of the two forms dd-aaa-dd or dd-dd-dd, where aaa are
+ letters and dd are digits.
+
+
+
+COMMENTS
+ The sequence (?# marks the start of a comment which contin-
+ ues up to the next closing parenthesis. Nested parentheses
+ are not permitted. The characters that make up a comment
+ play no part in the pattern matching at all.
+
+ If the PCRE_EXTENDED option is set, an unescaped # character
+ outside a character class introduces a comment that contin-
+ ues up to the next newline character in the pattern.
+
+
+
+PERFORMANCE
+ Certain items that may appear in patterns are more efficient
+ than others. It is more efficient to use a character class
+ like [aeiou] than a set of alternatives such as (a|e|i|o|u).
+ In general, the simplest construction that provides the
+ required behaviour is usually the most efficient. Jeffrey
+ Friedl's book contains a lot of discussion about optimizing
+ regular expressions for efficient performance.
+
+ When a pattern begins with .* and the PCRE_DOTALL option is
+ set, the pattern is implicitly anchored by PCRE, since it
+ can match only at the start of a subject string. However, if
+ PCRE_DOTALL is not set, PCRE cannot make this optimization,
+ because the . metacharacter does not then match a newline,
+ and if the subject string contains newlines, the pattern may
+ match from the character immediately following one of them
+ instead of from the very start. For example, the pattern
+
+ (.*) second
+
+ matches the subject "first\nand second" (where \n stands for
+ a newline character) with the first captured substring being
+ "and". In order to do this, PCRE has to retry the match
+ starting after every newline in the subject.
+
+ If you are using such a pattern with subject strings that do
+ not contain newlines, the best performance is obtained by
+ setting PCRE_DOTALL, or starting the pattern with ^.* to
+ indicate explicit anchoring. That saves PCRE from having to
+ scan along the subject looking for a newline to restart at.
+
+ Beware of patterns that contain nested indefinite repeats.
+ These can take a long time to run when applied to a string
+ that does not match. Consider the pattern fragment
+
+ (a+)*
+
+ This can match "aaaa" in 33 different ways, and this number
+ increases very rapidly as the string gets longer. (The *
+ repeat can match 0, 1, 2, 3, or 4 times, and for each of
+ those cases other than 0, the + repeats can match different
+ numbers of times.) When the remainder of the pattern is such
+ that the entire match is going to fail, PCRE has in princi-
+ ple to try every possible variation, and this can take an
+ extremely long time.
+
+ An optimization catches some of the more simple cases such
+ as
+
+ (a+)*b
+
+ where a literal character follows. Before embarking on the
+ standard matching procedure, PCRE checks that there is a "b"
+ later in the subject string, and if there is not, it fails
+ the match immediately. However, when there is no following
+ literal this optimization cannot be used. You can see the
+ difference by comparing the behaviour of
+
+ (a+)*\d
+
+ with the pattern above. The former gives a failure almost
+ instantly when applied to a whole line of "a" characters,
+ whereas the latter takes an appreciable time with strings
+ longer than about 20 characters.
+
+
+
+AUTHOR
+ Philip Hazel <ph10@cam.ac.uk>
+ University Computing Service,
+ New Museums Site,
+ Cambridge CB2 3QG, England.
+ Phone: +44 1223 334714
+
+ Last updated: 29 July 1999
+ Copyright (c) 1997-1999 University of Cambridge.
static BOOL
compile_regex(int, int, int *, uschar **, const uschar **, const char **,
- BOOL, int, compile_data *);
+ BOOL, int, int *, int *, compile_data *);
* Return version string *
*************************************************/
+#define STRING(a) # a
+#define XSTRING(s) STRING(s)
+
const char *
pcre_version(void)
{
-return PCRE_VERSION;
+return XSTRING(PCRE_MAJOR) "." XSTRING(PCRE_MINOR) " " XSTRING(PCRE_DATE);
}
*************************************************/
/* This function picks potentially useful data out of the private
-structure.
+structure. The public options are passed back in an int - though the
+re->options field has been expanded to a long int, all the public options
+at the low end of it, and so even on 16-bit systems this will still be OK.
+Therefore, I haven't changed the API for pcre_info().
Arguments:
external_re points to compiled code
const real_pcre *re = (const real_pcre *)external_re;
if (re == NULL) return PCRE_ERROR_NULL;
if (re->magic_number != MAGIC_NUMBER) return PCRE_ERROR_BADMAGIC;
-if (optptr != NULL) *optptr = (re->options & PUBLIC_OPTIONS);
+if (optptr != NULL) *optptr = (int)(re->options & PUBLIC_OPTIONS);
if (first_char != NULL)
*first_char = ((re->options & PCRE_FIRSTSET) != 0)? re->first_char :
((re->options & PCRE_STARTLINE) != 0)? -1 : -2;
case OP_REVERSE:
cc++;
+ /* Fall through */
case OP_CREF:
case OP_OPT:
ptrptr points to the current pattern pointer
errorptr points to pointer to error message
optchanged set to the value of the last OP_OPT item compiled
+ reqchar set to the last literal character required, else -1
+ countlits set to count of mandatory literal characters
cd contains pointers to tables
Returns: TRUE on success
static BOOL
compile_branch(int options, int *brackets, uschar **codeptr,
const uschar **ptrptr, const char **errorptr, int *optchanged,
- compile_data *cd)
+ int *reqchar, int *countlits, compile_data *cd)
{
int repeat_type, op_type;
int repeat_min, repeat_max;
int bravalue, length;
int greedy_default, greedy_non_default;
+int prevreqchar;
+int condcount = 0;
+int subcountlits = 0;
register int c;
register uschar *code = *codeptr;
uschar *tempcode;
greedy_default = ((options & PCRE_UNGREEDY) != 0);
greedy_non_default = greedy_default ^ 1;
+/* Initialize no required char, and count of literals */
+
+*reqchar = prevreqchar = -1;
+*countlits = 0;
+
/* Switch on next character until the end of the branch */
for (;; ptr++)
int class_lastchar;
int newoptions;
int condref;
+ int subreqchar;
c = *ptr;
if ((options & PCRE_EXTENDED) != 0)
{ repeat_type = greedy_non_default; ptr++; }
else repeat_type = greedy_default;
- /* If the maximum is zero then the minimum must also be zero; Perl allows
- this case, so we do too - by simply omitting the item altogether. */
-
- if (repeat_max == 0) code = previous;
-
/* If previous was a string of characters, chop off the last one and use it
as the subject of the repeat. If there was only one character, we can
- abolish the previous item altogether. */
+ abolish the previous item altogether. A repeat with a zero minimum wipes
+ out any reqchar setting, backing up to the previous value. We must also
+ adjust the countlits value. */
- else if (*previous == OP_CHARS)
+ if (*previous == OP_CHARS)
{
int len = previous[1];
+
+ if (repeat_min == 0) *reqchar = prevreqchar;
+ *countlits += repeat_min - 1;
+
if (len == 1)
{
c = previous[2];
code = previous;
OUTPUT_SINGLE_REPEAT:
- repeat_type += op_type; /* Combine both values for many cases */
+
+ /* If the maximum is zero then the minimum must also be zero; Perl allows
+ this case, so we do too - by simply omitting the item altogether. */
+
+ if (repeat_max == 0) goto END_REPEAT;
+
+ /* Combine the op_type with the repeat_type */
+
+ repeat_type += op_type;
/* A minimum of zero is handled either as the special case * or ?, or as
an UPTO, with the maximum given. */
}
/* If previous was a character class or a back reference, we put the repeat
- stuff after it. */
+ stuff after it, but just skip the item if the repeat was {0,0}. */
else if (*previous == OP_CLASS || *previous == OP_REF)
{
+ if (repeat_max == 0)
+ {
+ code = previous;
+ goto END_REPEAT;
+ }
if (repeat_min == 0 && repeat_max == -1)
*code++ = OP_CRSTAR + repeat_type;
else if (repeat_min == 1 && repeat_max == -1)
if (repeat_min == 0)
{
+ /* If we set up a required char from the bracket, we must back off
+ to the previous value and reset the countlits value too. */
+
+ if (subcountlits > 0)
+ {
+ *reqchar = prevreqchar;
+ *countlits -= subcountlits;
+ }
+
/* If the maximum is also zero, we just omit the group from the output
altogether. */
if (repeat_max == 0)
{
code = previous;
- previous = NULL;
- break;
+ goto END_REPEAT;
}
/* If the maximum is 1 or unlimited, we just have to stick in the
correct offset was computed above. */
else code[-ketoffset] = OP_KETRMAX + repeat_type;
-
-
-#ifdef NEVER
- /* If the minimum is greater than zero, and the maximum is unlimited or
- equal to the minimum, the first copy remains where it is, and is
- replicated up to the minimum number of times. This case includes the +
- repeat, but of course no replication is needed in that case. */
-
- if (repeat_min > 0 && (repeat_max == -1 || repeat_max == repeat_min))
- {
- for (i = 1; i < repeat_min; i++)
- {
- memcpy(code, previous, len);
- code += len;
- }
- }
-
- /* If the minimum is zero, stick BRAZERO in front of the first copy.
- Then, if there is a fixed upper limit, replicated up to that many times,
- sticking BRAZERO in front of all the optional ones. */
-
- else
- {
- if (repeat_min == 0)
- {
- memmove(previous+1, previous, len);
- code++;
- *previous++ = OP_BRAZERO + repeat_type;
- }
-
- for (i = 1; i < repeat_min; i++)
- {
- memcpy(code, previous, len);
- code += len;
- }
-
- for (i = (repeat_min > 0)? repeat_min : 1; i < repeat_max; i++)
- {
- *code++ = OP_BRAZERO + repeat_type;
- memcpy(code, previous, len);
- code += len;
- }
- }
-
- /* If the maximum is unlimited, set a repeater in the final copy. We
- can't just offset backwards from the current code point, because we
- don't know if there's been an options resetting after the ket. The
- correct offset was computed above. */
-
- if (repeat_max == -1) code[-ketoffset] = OP_KETRMAX + repeat_type;
-#endif
-
-
}
/* Else there's some kind of shambles */
/* In all case we no longer have a previous item. */
+ END_REPEAT:
previous = NULL;
break;
(bravalue == OP_ASSERTBACK ||
bravalue == OP_ASSERTBACK_NOT), /* TRUE if back assert */
condref, /* Condition reference number */
+ &subreqchar, /* For possible last char */
+ &subcountlits, /* For literal count */
cd)) /* Tables block */
goto FAILED;
if (bravalue == OP_COND)
{
- int branchcount = 0;
uschar *tc = code;
+ condcount = 0;
do {
- branchcount++;
+ condcount++;
tc += (tc[1] << 8) | tc[2];
}
while (*tc != OP_KET);
- if (branchcount > 2)
+ if (condcount > 2)
{
*errorptr = ERR27;
goto FAILED;
}
}
+ /* Handle updating of the required character. If the subpattern didn't
+ set one, leave it as it was. Otherwise, update it for normal brackets of
+ all kinds, forward assertions, and conditions with two branches. Don't
+ update the literal count for forward assertions, however. If the bracket
+ is followed by a quantifier with zero repeat, we have to back off. Hence
+ the definition of prevreqchar and subcountlits outside the main loop so
+ that they can be accessed for the back off. */
+
+ if (subreqchar > 0 &&
+ (bravalue >= OP_BRA || bravalue == OP_ONCE || bravalue == OP_ASSERT ||
+ (bravalue == OP_COND && condcount == 2)))
+ {
+ prevreqchar = *reqchar;
+ *reqchar = subreqchar;
+ if (bravalue != OP_ASSERT) *countlits += subcountlits;
+ }
+
/* Now update the main code pointer to the end of the group. */
code = tempcode;
while (length < 255 && (cd->ctypes[c = *(++ptr)] & ctype_meta) == 0);
+ /* Update the last character and the count of literals */
+
+ prevreqchar = (length > 1)? code[-2] : *reqchar;
+ *reqchar = code[-1];
+ *countlits += length;
+
/* Compute the length and set it in the data vector, and advance to
the next state. */
errorptr -> pointer to error message
lookbehind TRUE if this is a lookbehind assertion
condref > 0 for OPT_CREF setting at start of conditional group
+ reqchar -> place to put the last required character, or a negative number
+ countlits -> place to put the shortest literal count of any branch
cd points to the data block with tables pointers
Returns: TRUE on success
static BOOL
compile_regex(int options, int optchanged, int *brackets, uschar **codeptr,
const uschar **ptrptr, const char **errorptr, BOOL lookbehind, int condref,
- compile_data *cd)
+ int *reqchar, int *countlits, compile_data *cd)
{
const uschar *ptr = *ptrptr;
uschar *code = *codeptr;
uschar *start_bracket = code;
uschar *reverse_count = NULL;
int oldoptions = options & PCRE_IMS;
+int branchreqchar, branchcountlits;
+*reqchar = -1;
+*countlits = INT_MAX;
code += 3;
/* At the start of a reference-based conditional group, insert the reference
/* Now compile the branch */
- if (!compile_branch(options,brackets,&code,&ptr,errorptr,&optchanged,cd))
+ if (!compile_branch(options, brackets, &code, &ptr, errorptr, &optchanged,
+ &branchreqchar, &branchcountlits, cd))
{
*ptrptr = ptr;
return FALSE;
last_branch[1] = length >> 8;
last_branch[2] = length & 255;
+ /* Save the last required character if all branches have the same; a current
+ value of -1 means unset, while -2 means "previous branch had no last required
+ char". */
+
+ if (*reqchar != -2)
+ {
+ if (branchreqchar >= 0)
+ {
+ if (*reqchar == -1) *reqchar = branchreqchar;
+ else if (*reqchar != branchreqchar) *reqchar = -2;
+ }
+ else *reqchar = -2;
+ }
+
+ /* Keep the shortest literal count */
+
+ if (branchcountlits < *countlits) *countlits = branchcountlits;
+ DPRINTF(("literal count = %d min=%d\n", branchcountlits, *countlits));
+
/* If lookbehind, check that this branch matches a fixed-length string,
and put the length into the OP_REVERSE item. Temporarily mark the end of
the branch with OP_END. */
code += 2;
break;
+ case OP_WORD_BOUNDARY:
+ case OP_NOT_WORD_BOUNDARY:
+ code++;
+ break;
+
case OP_ASSERT_NOT:
case OP_ASSERTBACK:
case OP_ASSERTBACK_NOT:
real_pcre *re;
int length = 3; /* For initial BRA plus length */
int runlength;
-int c, size;
+int c, size, reqchar, countlits;
int bracount = 0;
int top_backref = 0;
int branch_extra = 0;
will lead to an over-estimate on the length, but this shouldn't
matter very much. We also have to allow for resetting options at
the start of any alternations, which we do by setting
- branch_newextra to 2. */
+ branch_newextra to 2. Finally, we record whether the case-dependent
+ flag ever changes within the regex. This is used by the "required
+ character" code. */
case ':':
if (((set|unset) & PCRE_IMS) != 0)
{
length += 4;
branch_newextra = 2;
+ if (((set|unset) & PCRE_CASELESS) != 0) options |= PCRE_ICHANGED;
}
goto END_OPTIONS;
*code = OP_BRA;
bracount = 0;
(void)compile_regex(options, -1, &bracount, &code, &ptr, errorptr, FALSE, -1,
- &compile_block);
+ &reqchar, &countlits, &compile_block);
re->top_bracket = bracount;
re->top_backref = top_backref;
}
}
+/* Save the last required character if there are at least two literal
+characters on all paths, or if there is no first character setting. */
+
+if (reqchar >= 0 && (countlits > 1 || (re->options & PCRE_FIRSTSET) == 0))
+ {
+ re->req_char = reqchar;
+ re->options |= PCRE_REQCHSET;
+ }
+
/* Print out the compiled data for debugging */
#ifdef DEBUG
if (re->options != 0)
{
- printf("%s%s%s%s%s%s%s%s\n",
+ printf("%s%s%s%s%s%s%s%s%s\n",
((re->options & PCRE_ANCHORED) != 0)? "anchored " : "",
((re->options & PCRE_CASELESS) != 0)? "caseless " : "",
+ ((re->options & PCRE_ICHANGED) != 0)? "case state changed " : "",
((re->options & PCRE_EXTENDED) != 0)? "extended " : "",
((re->options & PCRE_MULTILINE) != 0)? "multiline " : "",
((re->options & PCRE_DOTALL) != 0)? "dotall " : "",
else printf("First char = \\x%02x\n", re->first_char);
}
+if ((re->options & PCRE_REQCHSET) != 0)
+ {
+ if (isprint(re->req_char)) printf("Req char = %c\n", re->req_char);
+ else printf("Req char = \\x%02x\n", re->req_char);
+ }
+
code_end = code;
code_base = code = re->code;
static BOOL
match_ref(int offset, register const uschar *eptr, int length, match_data *md,
- int ims)
+ unsigned long int ims)
{
const uschar *p = md->start_subject + md->offset_vector[offset];
static BOOL
match(register const uschar *eptr, register const uschar *ecode,
- int offset_top, match_data *md, int ims, BOOL condassert, const uschar *eptrb)
+ int offset_top, match_data *md, unsigned long int ims, BOOL condassert,
+ const uschar *eptrb)
{
-int original_ims = ims; /* Save for resetting on ')' */
+unsigned long int original_ims = ims; /* Save for resetting on ')' */
for (;;)
{
ecode += 2;
break;
- /* End of the pattern */
+ /* End of the pattern. If PCRE_NOTEMPTY is set, fail if we have matched
+ an empty string - recursion will then try other alternatives, if any. */
case OP_END:
+ if (md->notempty && eptr == md->start_match) return FALSE;
md->end_match_ptr = eptr; /* Record where we ended */
md->end_offset_top = offset_top; /* and how many extracts were taken */
return TRUE;
case OP_OPT:
ims = ecode[1];
ecode += 2;
- DPRINTF(("ims set to %02x\n", ims));
+ DPRINTF(("ims set to %02lx\n", ims));
break;
/* Assertion brackets. Check the alternative branches in turn - the
if (ecode[3] == OP_OPT)
{
ims = (ims & ~PCRE_IMS) | ecode[4];
- DPRINTF(("ims set to %02x at group repeat\n", ims));
+ DPRINTF(("ims set to %02lx at group repeat\n", ims));
}
if (*ecode == OP_KETRMIN)
the group. */
ims = original_ims;
- DPRINTF(("ims reset to %02x\n", ims));
+ DPRINTF(("ims reset to %02lx\n", ims));
/* For a non-repeating ket, just continue at this level. This also
happens for a repeating ket if no characters were matched in the group.
case OP_NOT_WORD_BOUNDARY:
case OP_WORD_BOUNDARY:
{
- /* Modified the next line to check previous character
- in case we're not at the beginning of the whole string
- (Andrey Zmievski) */
- BOOL prev_is_word = (eptr != md->start_subject) ?
- ((md->ctypes[eptr[-1]] & ctype_word) != 0) :
- ((md->ctypes[md->regprev] & ctype_word) != 0);
+ BOOL prev_is_word = (eptr != md->start_subject) &&
+ ((md->ctypes[eptr[-1]] & ctype_word) != 0);
BOOL cur_is_word = (eptr < md->end_subject) &&
((md->ctypes[*eptr] & ctype_word) != 0);
if ((*ecode++ == OP_WORD_BOUNDARY)?
external_extra points to "hints" from pcre_study() or is NULL
subject points to the subject string
length length of subject string (may contain binary zeros)
+ start_offset where to start in the subject string
options option bits
offsets points to a vector of ints to be filled in with offsets
offsetcount the number of elements in the vector
int
pcre_exec(const pcre *external_re, const pcre_extra *external_extra,
- const char *subject, int length, const char *strbeg, int options,
- int *offsets, int offsetcount, int minlen)
+ const char *subject, int length, int start_offset, int options, int *offsets,
+ int offsetcount)
{
int resetcount, ocount;
int first_char = -1;
-int ims = 0;
+int req_char = -1;
+int req_char2 = -1;
+unsigned long int ims = 0;
match_data match_block;
const uschar *start_bits = NULL;
-const uschar *start_match = (const uschar *)subject;
+const uschar *start_match = (const uschar *)subject + start_offset;
const uschar *end_subject;
+const uschar *req_char_ptr = start_match - 1;
const real_pcre *re = (const real_pcre *)external_re;
const real_pcre_extra *extra = (const real_pcre_extra *)external_extra;
BOOL using_temporary_offsets = FALSE;
match_block.notbol = (options & PCRE_NOTBOL) != 0;
match_block.noteol = (options & PCRE_NOTEOL) != 0;
+match_block.notempty = (options & PCRE_NOTEMPTY) != 0;
match_block.errorcode = PCRE_ERROR_NOMATCH; /* Default error */
match_block.lcc = re->tables + lcc_offset;
match_block.ctypes = re->tables + ctypes_offset;
-/* Setup previous character (Andrey Zmievski) */
-if (subject == strbeg)
- match_block.regprev = '\n';
-else {
- match_block.regprev = subject[-1];
- if (!(re->options & PCRE_MULTILINE) && match_block.regprev == '\n')
- match_block.regprev = '\0';
-}
-
/* 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. */
start_bits = extra->start_bits;
}
-/* Loop for unanchored matches; for anchored regexps the loop runs just once. */
+/* For anchored or unanchored matches, there may be a "last known required
+character" set. If the PCRE_CASELESS is set, implying that the match starts
+caselessly, or if there are any changes of this flag within the regex, set up
+both cases of the character. Otherwise set the two values the same, which will
+avoid duplicate testing (which takes significant time). This covers the vast
+majority of cases. It will be suboptimal when the case flag changes in a regex
+and the required character in fact is caseful. */
+
+if ((re->options & PCRE_REQCHSET) != 0)
+ {
+ req_char = re->req_char;
+ req_char2 = ((re->options & (PCRE_CASELESS | PCRE_ICHANGED)) != 0)?
+ (re->tables + fcc_offset)[req_char] : req_char;
+ }
+
+/* Loop for handling unanchored repeated matching attempts; for anchored regexs
+the loop runs just once. */
do
{
else if (startline)
{
- if (start_match > match_block.start_subject)
+ if (start_match > match_block.start_subject + start_offset)
{
while (start_match < end_subject && start_match[-1] != '\n')
start_match++;
}
}
- /* Or to a non-unique first char */
+ /* Or to a non-unique first char after study */
else if (start_bits != NULL)
{
printf("\n");
#endif
+ /* If req_char is set, we know that that character must appear in the subject
+ for the match to succeed. If the first character is set, req_char must be
+ later in the subject; otherwise the test starts at the match point. This
+ optimization can save a huge amount of backtracking in patterns with nested
+ unlimited repeats that aren't going to match. We don't know what the state of
+ case matching may be when this character is hit, so test for it in both its
+ cases if necessary. However, the different cased versions will not be set up
+ unless PCRE_CASELESS was given or the casing state changes within the regex.
+ Writing separate code makes it go faster, as does using an autoincrement and
+ backing off on a match. */
+
+ if (req_char >= 0)
+ {
+ register const uschar *p = start_match + ((first_char >= 0)? 1 : 0);
+
+ /* We don't need to repeat the search if we haven't yet reached the
+ place we found it at last time. */
+
+ if (p > req_char_ptr)
+ {
+ /* Do a single test if no case difference is set up */
+
+ if (req_char == req_char2)
+ {
+ while (p < end_subject)
+ {
+ if (*p++ == req_char) { p--; break; }
+ }
+ }
+
+ /* Otherwise test for either case */
+
+ else
+ {
+ while (p < end_subject)
+ {
+ register int pp = *p++;
+ if (pp == req_char || pp == req_char2) { p--; break; }
+ }
+ }
+
+ /* If we can't find the required character, break the matching loop */
+
+ if (p >= end_subject) break;
+
+ /* If we have found the required character, save the point where we
+ found it, so that we don't search again next time round the loop if
+ the start hasn't passed this character yet. */
+
+ req_char_ptr = p;
+ }
+ }
+
/* When a match occurs, substrings will be set for all internal extractions;
we just need to set up the whole thing as substring 0 before returning. If
there were too many extractions, set the return code to zero. In the case
those back references that we can. In this case there need not be overflow
if certain parts of the pattern were not used. */
+ match_block.start_match = start_match;
if (!match(start_match, re->code, 2, &match_block, ims, FALSE, start_match))
continue;
- /* Check that the match is not closer than minlen (Andrey Zmievski) */
- if (start_match - match_block.start_subject < minlen)
- continue;
-
/* Copy the offset information from temporary store if necessary */
if (using_temporary_offsets)
--- /dev/null
+EXPORTS
+
+pcre_malloc DATA
+pcre_free DATA
+
+pcre_compile
+pcre_copy_substring
+pcre_exec
+pcre_get_substring
+pcre_get_substring_list
+pcre_info
+pcre_maketables
+pcre_study
+pcre_version
+
+regcomp
+regexec
+regerror
+regfree
#ifndef _PCRE_H
#define _PCRE_H
+#define PCRE_MAJOR 2
+#define PCRE_MINOR 08
+#define PCRE_DATE 31-Aug-1999
+
+/* Win32 uses DLL by default */
+
+#ifdef _WIN32
+# ifdef STATIC
+# define PCRE_DL_IMPORT
+# else
+# define PCRE_DL_IMPORT __declspec(dllimport)
+# endif
+#else
+# define PCRE_DL_IMPORT
+#endif
+
/* Have to include stdlib.h in order to ensure that size_t is defined;
it is needed here for malloc. */
#define PCRE_NOTBOL 0x0080
#define PCRE_NOTEOL 0x0100
#define PCRE_UNGREEDY 0x0200
+#define PCRE_NOTEMPTY 0x0400
/* Exec-time and get-time error codes */
typedef void pcre_extra;
/* Store get and free functions. These can be set to alternative malloc/free
-functions if required. */
+functions if required. Some magic is required for Win32 DLL; it is null on
+other OS. */
+
+PCRE_DL_IMPORT extern void *(*pcre_malloc)(size_t);
+PCRE_DL_IMPORT extern void (*pcre_free)(void *);
-extern void *(*pcre_malloc)(size_t);
-extern void (*pcre_free)(void *);
+#undef PCRE_DL_IMPORT
/* Functions */
const unsigned char *);
extern int pcre_copy_substring(const char *, int *, int, int, char *, int);
extern int pcre_exec(const pcre *, const pcre_extra *, const char *,
- int, const char *, int, int *, int, int);
+ int, int, int, int *, int);
extern int pcre_get_substring(const char *, int *, int, int, const char **);
extern int pcre_get_substring_list(const char *, int *, int, const char ***);
extern int pcre_info(const pcre *, int *, int *);
.SH DESCRIPTION
This set of functions provides a POSIX-style API to the PCRE regular expression
-package. See \fBpcre (3)\fR for a description of the native API, which contains
-additional functionality. The functions described here are just wrapper
-functions that ultimately call the native API.
+package. See the \fBpcre\fR documentation for a description of the native API,
+which contains additional functionality.
+
+The functions described here are just wrapper functions that ultimately call
+the native API. Their prototypes are defined in the \fBpcreposix.h\fR header
+file, and on Unix systems the library itself is called \fBpcreposix.a\fR, so
+can be accessed by adding \fB-lpcreposix\fR to the command for linking an
+application which uses them. Because the POSIX functions call the native ones,
+it is also necessary to add \fR-lpcre\fR.
As I am pretty ignorant about POSIX, these functions must be considered as
experimental. I have implemented only those option bits that can be reasonably
--- /dev/null
+<HTML>
+<HEAD>
+<TITLE>pcreposix specification</TITLE>
+</HEAD>
+<body bgcolor="#FFFFFF" text="#00005A">
+<H1>pcreposix specification</H1>
+This HTML document has been generated automatically from the original man page.
+If there is any nonsense in it, please consult the man page in case the
+conversion went wrong.
+<UL>
+<LI><A NAME="TOC1" HREF="#SEC1">NAME</A>
+<LI><A NAME="TOC2" HREF="#SEC2">SYNOPSIS</A>
+<LI><A NAME="TOC3" HREF="#SEC3">DESCRIPTION</A>
+<LI><A NAME="TOC4" HREF="#SEC4">COMPILING A PATTERN</A>
+<LI><A NAME="TOC5" HREF="#SEC5">MATCHING A PATTERN</A>
+<LI><A NAME="TOC6" HREF="#SEC6">ERROR MESSAGES</A>
+<LI><A NAME="TOC7" HREF="#SEC7">STORAGE</A>
+<LI><A NAME="TOC8" HREF="#SEC8">AUTHOR</A>
+</UL>
+<LI><A NAME="SEC1" HREF="#TOC1">NAME</A>
+<P>
+pcreposix - POSIX API for Perl-compatible regular expressions.
+</P>
+<LI><A NAME="SEC2" HREF="#TOC1">SYNOPSIS</A>
+<P>
+<B>#include <pcreposix.h></B>
+</P>
+<P>
+<B>int regcomp(regex_t *<I>preg</I>, const char *<I>pattern</I>,</B>
+<B>int <I>cflags</I>);</B>
+</P>
+<P>
+<B>int regexec(regex_t *<I>preg</I>, const char *<I>string</I>,</B>
+<B>size_t <I>nmatch</I>, regmatch_t <I>pmatch</I>[], int <I>eflags</I>);</B>
+</P>
+<P>
+<B>size_t regerror(int <I>errcode</I>, const regex_t *<I>preg</I>,</B>
+<B>char *<I>errbuf</I>, size_t <I>errbuf_size</I>);</B>
+</P>
+<P>
+<B>void regfree(regex_t *<I>preg</I>);</B>
+</P>
+<LI><A NAME="SEC3" HREF="#TOC1">DESCRIPTION</A>
+<P>
+This set of functions provides a POSIX-style API to the PCRE regular expression
+package. See the <B>pcre</B> documentation for a description of the native API,
+which contains additional functionality.
+</P>
+<P>
+The functions described here are just wrapper functions that ultimately call
+the native API. Their prototypes are defined in the <B>pcreposix.h</B> header
+file, and on Unix systems the library itself is called <B>pcreposix.a</B>, so
+can be accessed by adding <B>-lpcreposix</B> to the command for linking an
+application which uses them. Because the POSIX functions call the native ones,
+it is also necessary to add \fR-lpcre\fR.
+</P>
+<P>
+As I am pretty ignorant about POSIX, these functions must be considered as
+experimental. I have implemented only those option bits that can be reasonably
+mapped to PCRE native options. Other POSIX options are not even defined. It may
+be that it is useful to define, but ignore, other options. Feedback from more
+knowledgeable folk may cause this kind of detail to change.
+</P>
+<P>
+When PCRE is called via these functions, it is only the API that is POSIX-like
+in style. The syntax and semantics of the regular expressions themselves are
+still those of Perl, subject to the setting of various PCRE options, as
+described below.
+</P>
+<P>
+The header for these functions is supplied as <B>pcreposix.h</B> to avoid any
+potential clash with other POSIX libraries. It can, of course, be renamed or
+aliased as <B>regex.h</B>, which is the "correct" name. It provides two
+structure types, <I>regex_t</I> for compiled internal forms, and
+<I>regmatch_t</I> for returning captured substrings. It also defines some
+constants whose names start with "REG_"; these are used for setting options and
+identifying error codes.
+</P>
+<LI><A NAME="SEC4" HREF="#TOC1">COMPILING A PATTERN</A>
+<P>
+The function <B>regcomp()</B> is called to compile a pattern into an
+internal form. The pattern is a C string terminated by a binary zero, and
+is passed in the argument <I>pattern</I>. The <I>preg</I> argument is a pointer
+to a regex_t structure which is used as a base for storing information about
+the compiled expression.
+</P>
+<P>
+The argument <I>cflags</I> is either zero, or contains one or more of the bits
+defined by the following macros:
+</P>
+<P>
+<PRE>
+ REG_ICASE
+</PRE>
+</P>
+<P>
+The PCRE_CASELESS option is set when the expression is passed for compilation
+to the native function.
+</P>
+<P>
+<PRE>
+ REG_NEWLINE
+</PRE>
+</P>
+<P>
+The PCRE_MULTILINE option is set when the expression is passed for compilation
+to the native function.
+</P>
+<P>
+The yield of <B>regcomp()</B> is zero on success, and non-zero otherwise. The
+<I>preg</I> structure is filled in on success, and one member of the structure
+is publicized: <I>re_nsub</I> contains the number of capturing subpatterns in
+the regular expression. Various error codes are defined in the header file.
+</P>
+<LI><A NAME="SEC5" HREF="#TOC1">MATCHING A PATTERN</A>
+<P>
+The function <B>regexec()</B> is called to match a pre-compiled pattern
+<I>preg</I> against a given <I>string</I>, which is terminated by a zero byte,
+subject to the options in <I>eflags</I>. These can be:
+</P>
+<P>
+<PRE>
+ REG_NOTBOL
+</PRE>
+</P>
+<P>
+The PCRE_NOTBOL option is set when calling the underlying PCRE matching
+function.
+</P>
+<P>
+<PRE>
+ REG_NOTEOL
+</PRE>
+</P>
+<P>
+The PCRE_NOTEOL option is set when calling the underlying PCRE matching
+function.
+</P>
+<P>
+The portion of the string that was matched, and also any captured substrings,
+are returned via the <I>pmatch</I> argument, which points to an array of
+<I>nmatch</I> structures of type <I>regmatch_t</I>, containing the members
+<I>rm_so</I> and <I>rm_eo</I>. These contain the offset to the first character of
+each substring and the offset to the first character after the end of each
+substring, respectively. The 0th element of the vector relates to the entire
+portion of <I>string</I> that was matched; subsequent elements relate to the
+capturing subpatterns of the regular expression. Unused entries in the array
+have both structure members set to -1.
+</P>
+<P>
+A successful match yields a zero return; various error codes are defined in the
+header file, of which REG_NOMATCH is the "expected" failure code.
+</P>
+<LI><A NAME="SEC6" HREF="#TOC1">ERROR MESSAGES</A>
+<P>
+The <B>regerror()</B> function maps a non-zero errorcode from either
+<B>regcomp</B> or <B>regexec</B> to a printable message. If <I>preg</I> is not
+NULL, the error should have arisen from the use of that structure. A message
+terminated by a binary zero is placed in <I>errbuf</I>. The length of the
+message, including the zero, is limited to <I>errbuf_size</I>. The yield of the
+function is the size of buffer needed to hold the whole message.
+</P>
+<LI><A NAME="SEC7" HREF="#TOC1">STORAGE</A>
+<P>
+Compiling a regular expression causes memory to be allocated and associated
+with the <I>preg</I> structure. The function <B>regfree()</B> frees all such
+memory, after which <I>preg</I> may no longer be used as a compiled expression.
+</P>
+<LI><A NAME="SEC8" HREF="#TOC1">AUTHOR</A>
+<P>
+Philip Hazel <ph10@cam.ac.uk>
+<BR>
+University Computing Service,
+<BR>
+New Museums Site,
+<BR>
+Cambridge CB2 3QG, England.
+<BR>
+Phone: +44 1223 334714
+</P>
+<P>
+Copyright (c) 1997-1999 University of Cambridge.
--- /dev/null
+NAME
+ pcreposix - POSIX API for Perl-compatible regular expres-
+ sions.
+
+
+
+SYNOPSIS
+ #include <pcreposix.h>
+
+ int regcomp(regex_t *preg, const char *pattern,
+ int cflags);
+
+ int regexec(regex_t *preg, const char *string,
+ size_t nmatch, regmatch_t pmatch[], int eflags);
+
+ size_t regerror(int errcode, const regex_t *preg,
+ char *errbuf, size_t errbuf_size);
+
+ void regfree(regex_t *preg);
+
+
+
+DESCRIPTION
+ This set of functions provides a POSIX-style API to the PCRE
+ regular expression package. See the pcre documentation for a
+ description of the native API, which contains additional
+ functionality.
+
+ The functions described here are just wrapper functions that
+ ultimately call the native API. Their prototypes are defined
+ in the pcreposix.h header file, and on Unix systems the
+ library itself is called pcreposix.a, so can be accessed by
+ adding -lpcreposix to the command for linking an application
+ which uses them. Because the POSIX functions call the native
+ ones, it is also necessary to add -lpcre.
+
+ As I am pretty ignorant about POSIX, these functions must be
+ considered as experimental. I have implemented only those
+ option bits that can be reasonably mapped to PCRE native
+ options. Other POSIX options are not even defined. It may be
+ that it is useful to define, but ignore, other options.
+ Feedback from more knowledgeable folk may cause this kind of
+ detail to change.
+
+ When PCRE is called via these functions, it is only the API
+ that is POSIX-like in style. The syntax and semantics of the
+ regular expressions themselves are still those of Perl, sub-
+ ject to the setting of various PCRE options, as described
+ below.
+
+ The header for these functions is supplied as pcreposix.h to
+ avoid any potential clash with other POSIX libraries. It
+ can, of course, be renamed or aliased as regex.h, which is
+ the "correct" name. It provides two structure types, regex_t
+ for compiled internal forms, and regmatch_t for returning
+ captured substrings. It also defines some constants whose
+ names start with "REG_"; these are used for setting options
+ and identifying error codes.
+
+
+
+COMPILING A PATTERN
+ The function regcomp() is called to compile a pattern into
+ an internal form. The pattern is a C string terminated by a
+ binary zero, and is passed in the argument pattern. The preg
+ argument is a pointer to a regex_t structure which is used
+ as a base for storing information about the compiled expres-
+ sion.
+
+ The argument cflags is either zero, or contains one or more
+ of the bits defined by the following macros:
+
+ REG_ICASE
+
+ The PCRE_CASELESS option is set when the expression is
+ passed for compilation to the native function.
+
+ REG_NEWLINE
+
+ The PCRE_MULTILINE option is set when the expression is
+ passed for compilation to the native function.
+
+ The yield of regcomp() is zero on success, and non-zero oth-
+ erwise. The preg structure is filled in on success, and one
+ member of the structure is publicized: re_nsub contains the
+ number of capturing subpatterns in the regular expression.
+ Various error codes are defined in the header file.
+
+
+
+MATCHING A PATTERN
+ The function regexec() is called to match a pre-compiled
+ pattern preg against a given string, which is terminated by
+ a zero byte, subject to the options in eflags. These can be:
+
+ REG_NOTBOL
+
+ The PCRE_NOTBOL option is set when calling the underlying
+ PCRE matching function.
+
+ REG_NOTEOL
+
+ The PCRE_NOTEOL option is set when calling the underlying
+ PCRE matching function.
+
+ The portion of the string that was matched, and also any
+ captured substrings, are returned via the pmatch argument,
+ which points to an array of nmatch structures of type
+ regmatch_t, containing the members rm_so and rm_eo. These
+ contain the offset to the first character of each substring
+ and the offset to the first character after the end of each
+ substring, respectively. The 0th element of the vector
+ relates to the entire portion of string that was matched;
+ subsequent elements relate to the capturing subpatterns of
+ the regular expression. Unused entries in the array have
+ both structure members set to -1.
+
+ A successful match yields a zero return; various error codes
+ are defined in the header file, of which REG_NOMATCH is the
+ "expected" failure code.
+
+
+
+ERROR MESSAGES
+ The regerror() function maps a non-zero errorcode from
+ either regcomp or regexec to a printable message. If preg is
+ not NULL, the error should have arisen from the use of that
+ structure. A message terminated by a binary zero is placed
+ in errbuf. The length of the message, including the zero, is
+ limited to errbuf_size. The yield of the function is the
+ size of buffer needed to hold the whole message.
+
+
+
+STORAGE
+ Compiling a regular expression causes memory to be allocated
+ and associated with the preg structure. The function reg-
+ free() frees all such memory, after which preg may no longer
+ be used as a compiled expression.
+
+
+
+AUTHOR
+ Philip Hazel <ph10@cam.ac.uk>
+ University Computing Service,
+ New Museums Site,
+ Cambridge CB2 3QG, England.
+ Phone: +44 1223 334714
+
+ Copyright (c) 1997-1999 University of Cambridge.
preg->re_erroffset = (size_t)(-1); /* Only has meaning after compile */
-rc = pcre_exec(preg->re_pcre, NULL, string, (int)strlen(string),
- string, // const char *strbeg (added for vi-like 'g' replace flag)
- options, (int *)pmatch, nmatch * 2,
- 0); // int minlen (added for vi-like 'g' replace flag)
+rc = pcre_exec(preg->re_pcre, NULL, string, (int)strlen(string), 0, options,
+ (int *)pmatch, nmatch * 2);
if (rc == 0) return 0; /* All pmatch were filled in */
/* Use the internal info for displaying the results of pcre_study(). */
#include "internal.h"
+
+/* It is possible to compile this test program without including support for
+testing the POSIX interface, though this is not available via the standard
+Makefile. */
+
+#if !defined NOPOSIX
#include "pcreposix.h"
+#endif
#ifndef CLOCKS_PER_SEC
#ifdef CLK_TCK
};
-static void print_internals(pcre *re, FILE *outfile)
+static void print_internals(pcre *re)
{
unsigned char *code = ((real_pcre *)re)->code;
static void *new_malloc(size_t size)
{
if (log_store)
- fprintf(outfile, "Memory allocation request: %d (code space %d)\n",
- (int)size, (int)size - offsetof(real_pcre, code[0]));
+ fprintf(outfile, "Memory allocation (code space): %d\n",
+ (int)((int)size - offsetof(real_pcre, code[0])));
return malloc(size);
}
{
pcre *re = NULL;
pcre_extra *extra = NULL;
+
+#if !defined NOPOSIX /* There are still compilers that require no indent */
regex_t preg;
+#endif
+
const char *error;
unsigned char *p, *pp, *ppp;
unsigned const char *tables = NULL;
int do_study = 0;
int do_debug = debug;
+ int do_G = 0;
+ int do_g = 0;
int do_showinfo = showinfo;
+ int do_showrest = 0;
int do_posix = 0;
int erroroffset, len, delimiter;
{
switch (*pp++)
{
+ case 'g': do_g = 1; break;
case 'i': options |= PCRE_CASELESS; break;
case 'm': options |= PCRE_MULTILINE; break;
case 's': options |= PCRE_DOTALL; break;
case 'x': options |= PCRE_EXTENDED; break;
+ case '+': do_showrest = 1; break;
case 'A': options |= PCRE_ANCHORED; break;
case 'D': do_debug = do_showinfo = 1; break;
case 'E': options |= PCRE_DOLLAR_ENDONLY; break;
+ case 'G': do_G = 1; break;
case 'I': do_showinfo = 1; break;
case 'M': log_store = 1; break;
+
+#if !defined NOPOSIX
case 'P': do_posix = 1; break;
+#endif
+
case 'S': do_study = 1; break;
case 'U': options |= PCRE_UNGREEDY; break;
case 'X': options |= PCRE_EXTRA; break;
timing, showing, or debugging options, nor the ability to pass over
local character tables. */
+#if !defined NOPOSIX
if (posix || do_posix)
{
int rc;
/* Handle compiling via the native interface */
else
+#endif /* !defined NOPOSIX */
+
{
if (timeit)
{
{
int first_char, count;
- if (do_debug) print_internals(re, outfile);
+ if (do_debug) print_internals(re);
count = pcre_info(re, &options, &first_char);
if (count < 0) fprintf(outfile,
((options & PCRE_DOLLAR_ENDONLY) != 0)? " dollar_endonly" : "",
((options & PCRE_EXTRA) != 0)? " extra" : "",
((options & PCRE_UNGREEDY) != 0)? " ungreedy" : "");
+
+ if (((((real_pcre *)re)->options) & PCRE_ICHANGED) != 0)
+ fprintf(outfile, "Case state changes\n");
+
if (first_char == -1)
{
fprintf(outfile, "First char at start or follows \\n\n");
else
fprintf(outfile, "First char = %d\n", first_char);
}
+
+ if (((((real_pcre *)re)->options) & PCRE_REQCHSET) != 0)
+ {
+ int req_char = ((real_pcre *)re)->req_char;
+ if (isprint(req_char))
+ fprintf(outfile, "Req char = \'%c\'\n", req_char);
+ else
+ fprintf(outfile, "Req char = %d\n", req_char);
+ }
+ else fprintf(outfile, "No req char\n");
}
}
for (;;)
{
unsigned char *q;
+ unsigned char *bptr = dbuffer;
int count, c;
int copystrings = 0;
int getstrings = 0;
int getlist = 0;
+ int gmatched = 0;
+ int start_offset = 0;
int offsets[45];
int size_offsets = sizeof(offsets)/sizeof(int);
options = 0;
- if (infile == stdin) printf(" data> ");
+ if (infile == stdin) printf("data> ");
if (fgets((char *)buffer, sizeof(buffer), infile) == NULL)
{
done = 1;
getlist = 1;
continue;
+ case 'N':
+ options |= PCRE_NOTEMPTY;
+ continue;
+
case 'O':
while(isdigit(*p)) n = n * 10 + *p++ - '0';
if (n <= (int)(sizeof(offsets)/sizeof(int))) size_offsets = n;
/* Handle matching via the POSIX interface, which does not
support timing. */
+#if !defined NOPOSIX
if (posix || do_posix)
{
int rc;
if ((options & PCRE_NOTBOL) != 0) eflags |= REG_NOTBOL;
if ((options & PCRE_NOTEOL) != 0) eflags |= REG_NOTEOL;
- rc = regexec(&preg, (char *)dbuffer, sizeof(pmatch)/sizeof(regmatch_t),
- pmatch, eflags);
+ rc = regexec(&preg, (const char *)bptr,
+ sizeof(pmatch)/sizeof(regmatch_t), pmatch, eflags);
if (rc != 0)
{
pchars(dbuffer + pmatch[i].rm_so,
pmatch[i].rm_eo - pmatch[i].rm_so);
fprintf(outfile, "\n");
+ if (i == 0 && do_showrest)
+ {
+ fprintf(outfile, " 0+ ");
+ pchars(dbuffer + pmatch[i].rm_eo, len - pmatch[i].rm_eo);
+ fprintf(outfile, "\n");
+ }
}
}
}
}
- /* Handle matching via the native interface */
+ /* Handle matching via the native interface - repeats for /g and /G */
else
+#endif /* !defined NOPOSIX */
+
+ for (;; gmatched++) /* Loop for /g or /G */
{
if (timeit)
{
clock_t time_taken;
clock_t start_time = clock();
for (i = 0; i < LOOPREPEAT; i++)
- count = pcre_exec(re, extra, (char *)dbuffer, len, options, offsets,
- size_offsets);
+ count = pcre_exec(re, extra, (char *)bptr, len,
+ start_offset, options, offsets, size_offsets);
time_taken = clock() - start_time;
fprintf(outfile, "Execute time %.3f milliseconds\n",
((double)time_taken * 1000.0)/
((double)LOOPREPEAT * (double)CLOCKS_PER_SEC));
}
- count = pcre_exec(re, extra, (char *)dbuffer, len, options, offsets,
- size_offsets);
+ count = pcre_exec(re, extra, (char *)bptr, len,
+ start_offset, options, offsets, size_offsets);
if (count == 0)
{
count = size_offsets/3;
}
+ /* Matched */
+
if (count >= 0)
{
int i;
else
{
fprintf(outfile, "%2d: ", i/2);
- pchars(dbuffer + offsets[i], offsets[i+1] - offsets[i]);
+ pchars(bptr + offsets[i], offsets[i+1] - offsets[i]);
fprintf(outfile, "\n");
+ if (i == 0)
+ {
+ if (do_showrest)
+ {
+ fprintf(outfile, " 0+ ");
+ pchars(bptr + offsets[i+1], len - offsets[i+1]);
+ fprintf(outfile, "\n");
+ }
+ }
}
}
{
if ((copystrings & (1 << i)) != 0)
{
- char buffer[16];
- int rc = pcre_copy_substring((char *)dbuffer, offsets, count,
- i, buffer, sizeof(buffer));
+ char copybuffer[16];
+ int rc = pcre_copy_substring((char *)bptr, offsets, count,
+ i, copybuffer, sizeof(copybuffer));
if (rc < 0)
fprintf(outfile, "copy substring %d failed %d\n", i, rc);
else
- fprintf(outfile, "%2dC %s (%d)\n", i, buffer, rc);
+ fprintf(outfile, "%2dC %s (%d)\n", i, copybuffer, rc);
}
}
if ((getstrings & (1 << i)) != 0)
{
const char *substring;
- int rc = pcre_get_substring((char *)dbuffer, offsets, count,
+ int rc = pcre_get_substring((char *)bptr, offsets, count,
i, &substring);
if (rc < 0)
fprintf(outfile, "get substring %d failed %d\n", i, rc);
if (getlist)
{
const char **stringlist;
- int rc = pcre_get_substring_list((char *)dbuffer, offsets, count,
+ int rc = pcre_get_substring_list((char *)bptr, offsets, count,
&stringlist);
if (rc < 0)
fprintf(outfile, "get substring list failed %d\n", rc);
free((void *)stringlist);
}
}
+ }
+
+ /* Failed to match */
+ else
+ {
+ if (gmatched == 0)
+ {
+ if (count == -1) fprintf(outfile, "No match\n");
+ else fprintf(outfile, "Error %d\n", count);
+ }
+ break; /* Out of the /g loop */
}
+
+ /* If not /g or /G we are done */
+
+ if (!do_g && !do_G) break;
+
+ /* If we have matched an empty string, set PCRE_NOTEMPTY for the next
+ match. This mimics what Perl's /g option does. */
+
+ if (offsets[1] == offsets[0])
+ options |= PCRE_NOTEMPTY;
+ else
+ options &= ~PCRE_NOTEMPTY;
+
+ /* For /g, update the start offset, leaving the rest alone */
+
+ if (do_g) start_offset = offsets[1];
+
+ /* For /G, update the pointer and length */
+
else
{
- if (count == -1) fprintf(outfile, "No match\n");
- else fprintf(outfile, "Error %d\n", count);
+ bptr += offsets[1];
+ len -= offsets[1];
}
- }
- }
+ } /* End of loop for /g and /G */
+ } /* End of loop for data lines */
CONTINUE:
+
+#if !defined NOPOSIX
if (posix || do_posix) regfree(&preg);
+#endif
+
if (re != NULL) free(re);
if (extra != NULL) free(extra);
if (tables != NULL)
.SH NAME
pgrep - a grep with Perl-compatible regular expressions.
.SH SYNOPSIS
-.B pgrep [-chilnsvx] pattern [file] ...
+.B pgrep [-Vchilnsvx] pattern [file] ...
.SH DESCRIPTION
.SH OPTIONS
.TP 10
+\fB-V\fR
+Write the version number of the PCRE library being used to the standard error
+stream.
+.TP
\fB-c\fR
Do not print individual lines; instead just print a count of the number of
lines that would otherwise have been printed. If several files are given, a
--- /dev/null
+<HTML>
+<HEAD>
+<TITLE>pgrep specification</TITLE>
+</HEAD>
+<body bgcolor="#FFFFFF" text="#00005A">
+<H1>pgrep specification</H1>
+This HTML document has been generated automatically from the original man page.
+If there is any nonsense in it, please consult the man page in case the
+conversion went wrong.
+<UL>
+<LI><A NAME="TOC1" HREF="#SEC1">NAME</A>
+<LI><A NAME="TOC2" HREF="#SEC2">SYNOPSIS</A>
+<LI><A NAME="TOC3" HREF="#SEC3">DESCRIPTION</A>
+<LI><A NAME="TOC4" HREF="#SEC4">OPTIONS</A>
+<LI><A NAME="TOC5" HREF="#SEC5">SEE ALSO</A>
+<LI><A NAME="TOC6" HREF="#SEC6">DIAGNOSTICS</A>
+<LI><A NAME="TOC7" HREF="#SEC7">AUTHOR</A>
+</UL>
+<LI><A NAME="SEC1" HREF="#TOC1">NAME</A>
+<P>
+pgrep - a grep with Perl-compatible regular expressions.
+</P>
+<LI><A NAME="SEC2" HREF="#TOC1">SYNOPSIS</A>
+<P>
+<B>pgrep [-Vchilnsvx] pattern [file] ...</B>
+</P>
+<LI><A NAME="SEC3" HREF="#TOC1">DESCRIPTION</A>
+<P>
+<B>pgrep</B> searches files for character patterns, in the same way as other
+grep commands do, but it uses the PCRE regular expression library to support
+patterns that are compatible with the regular expressions of Perl 5. See
+<B>pcre(3)</B> for a full description of syntax and semantics.
+</P>
+<P>
+If no files are specified, <B>pgrep</B> reads the standard input. By default,
+each line that matches the pattern is copied to the standard output, and if
+there is more than one file, the file name is printed before each line of
+output. However, there are options that can change how <B>pgrep</B> behaves.
+</P>
+<P>
+Lines are limited to BUFSIZ characters. BUFSIZ is defined in <B><stdio.h></B>.
+The newline character is removed from the end of each line before it is matched
+against the pattern.
+</P>
+<LI><A NAME="SEC4" HREF="#TOC1">OPTIONS</A>
+<P>
+<B>-V</B>
+Write the version number of the PCRE library being used to the standard error
+stream.
+</P>
+<P>
+<B>-c</B>
+Do not print individual lines; instead just print a count of the number of
+lines that would otherwise have been printed. If several files are given, a
+count is printed for each of them.
+</P>
+<P>
+<B>-h</B>
+Suppress printing of filenames when searching multiple files.
+</P>
+<P>
+<B>-i</B>
+Ignore upper/lower case distinctions during comparisons.
+</P>
+<P>
+<B>-l</B>
+Instead of printing lines from the files, just print the names of the files
+containing lines that would have been printed. Each file name is printed
+once, on a separate line.
+</P>
+<P>
+<B>-n</B>
+Precede each line by its line number in the file.
+</P>
+<P>
+<B>-s</B>
+Work silently, that is, display nothing except error messages.
+The exit status indicates whether any matches were found.
+</P>
+<P>
+<B>-v</B>
+Invert the sense of the match, so that lines which do <I>not</I> match the
+pattern are now the ones that are found.
+</P>
+<P>
+<B>-x</B>
+Force the pattern to be anchored (it must start matching at the beginning of
+the line) and in addition, require it to match the entire line. This is
+equivalent to having ^ and $ characters at the start and end of each
+alternative branch in the regular expression.
+</P>
+<LI><A NAME="SEC5" HREF="#TOC1">SEE ALSO</A>
+<P>
+<B>pcre(3)</B>, Perl 5 documentation
+</P>
+<LI><A NAME="SEC6" HREF="#TOC1">DIAGNOSTICS</A>
+<P>
+Exit status is 0 if any matches were found, 1 if no matches were found, and 2
+for syntax errors or inacessible files (even if matches were found).
+</P>
+<LI><A NAME="SEC7" HREF="#TOC1">AUTHOR</A>
+<P>
+Philip Hazel <ph10@cam.ac.uk>
+<BR>
+Copyright (c) 1997-1999 University of Cambridge.
--- /dev/null
+NAME
+ pgrep - a grep with Perl-compatible regular expressions.
+
+
+
+SYNOPSIS
+ pgrep [-Vchilnsvx] pattern [file] ...
+
+
+
+DESCRIPTION
+ pgrep searches files for character patterns, in the same way
+ as other grep commands do, but it uses the PCRE regular
+ expression library to support patterns that are compatible
+ with the regular expressions of Perl 5. See pcre(3) for a
+ full description of syntax and semantics.
+
+ If no files are specified, pgrep reads the standard input.
+ By default, each line that matches the pattern is copied to
+ the standard output, and if there is more than one file, the
+ file name is printed before each line of output. However,
+ there are options that can change how pgrep behaves.
+
+ Lines are limited to BUFSIZ characters. BUFSIZ is defined in
+ <stdio.h>. The newline character is removed from the end of
+ each line before it is matched against the pattern.
+
+
+
+OPTIONS
+ -V Write the version number of the PCRE library being
+ used to the standard error stream.
+
+ -c Do not print individual lines; instead just print
+ a count of the number of lines that would other-
+ wise have been printed. If several files are
+ given, a count is printed for each of them.
+
+ -h Suppress printing of filenames when searching mul-
+ tiple files.
+
+ -i Ignore upper/lower case distinctions during com-
+ parisons.
+
+ -l Instead of printing lines from the files, just
+ print the names of the files containing lines that
+ would have been printed. Each file name is printed
+ once, on a separate line.
+
+ -n Precede each line by its line number in the file.
+
+ -s Work silently, that is, display nothing except
+ error messages. The exit status indicates whether
+ any matches were found.
+
+ -v Invert the sense of the match, so that lines which
+ do not match the pattern are now the ones that are
+ found.
+
+ -x Force the pattern to be anchored (it must start
+ matching at the beginning of the line) and in
+ addition, require it to match the entire line.
+ This is equivalent to having ^ and $ characters at
+ the start and end of each alternative branch in
+ the regular expression.
+
+
+
+SEE ALSO
+ pcre(3), Perl 5 documentation
+
+
+
+
+
+DIAGNOSTICS
+ Exit status is 0 if any matches were found, 1 if no matches
+ were found, and 2 for syntax errors or inacessible files
+ (even if matches were found).
+
+
+
+AUTHOR
+ Philip Hazel <ph10@cam.ac.uk>
+ Copyright (c) 1997-1999 University of Cambridge.
+
if (length > 0 && buffer[length-1] == '\n') buffer[--length] = 0;
linenumber++;
- match = pcre_exec(pattern, hints, buffer, length, 0, offsets, 99) >= 0;
+ match = pcre_exec(pattern, hints, buffer, length, 0, 0, offsets, 99) >= 0;
if (match && whole_lines && offsets[1] != length) match = FALSE;
if (match != invert)
static int
usage(int rc)
{
-fprintf(stderr, "Usage: pgrep [-chilnsvx] pattern [file] ...\n");
+fprintf(stderr, "Usage: pgrep [-Vchilnsvx] pattern [file] ...\n");
return rc;
}
case 's': silent = TRUE; break;
case 'v': invert = TRUE; break;
case 'x': whole_lines = TRUE; options |= PCRE_ANCHORED; break;
+
+ case 'V':
+ fprintf(stderr, "PCRE version %s\n", pcre_version());
+ break;
+
default:
fprintf(stderr, "pgrep: unknown option %c\n", s[-1]);
return usage(2);
*** Failers
abcde\nBar
+/^.*B/
+ **** Failers
+ abc\nB
+
+/(?s)^.*B/
+ abc\nB
+
+/(?m)^.*B/
+ abc\nB
+
+/(?ms)^.*B/
+ abc\nB
+
+/(?ms)^B/
+ abc\nB
+
+/(?s)B$/
+ B\n
+
+/^[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]/
+ 123456654321
+
+/^\d\d\d\d\d\d\d\d\d\d\d\d/
+ 123456654321
+
+/^[\d][\d][\d][\d][\d][\d][\d][\d][\d][\d][\d][\d]/
+ 123456654321
+
+/^[abc]{12}/
+ abcabcabcabc
+
+/^[a-c]{12}/
+ abcabcabcabc
+
+/^(a|b|c){12}/
+ abcabcabcabc
+
+/^[abcdefghijklmnopqrstuvwxy0123456789]/
+ n
+ *** Failers
+ z
+
+/abcde{0,0}/
+ abcd
+ *** Failers
+ abce
+
+/ab[cd]{0,0}e/
+ abe
+ *** Failers
+ abcde
+
+/ab(c){0,0}d/
+ abd
+ *** Failers
+ abcd
+
+/a(b*)/
+ a
+ ab
+ abbbb
+ *** Failers
+ bbbbb
+
+/ab\d{0}e/
+ abe
+ *** Failers
+ ab1e
+
+/"([^\\"]+|\\.)*"/
+ the \"quick\" brown fox
+ \"the \\\"quick\\\" brown fox\"
+
/ End of test input /
/(?s:.*X|^B)/D
+/\Biss\B/+
+ Mississippi
+
+/\Biss\B/+P
+ Mississippi
+
+/iss/G+
+ Mississippi
+
+/\Biss\B/G+
+ Mississippi
+
+/\Biss\B/g+
+ Mississippi
+ *** Failers
+ Mississippi\A
+
+/(?<=[Ms])iss/g+
+ Mississippi
+
+/(?<=[Ms])iss/G+
+ Mississippi
+
+/^iss/g+
+ ississippi
+
+/.*iss/g+
+ abciss\nxyzisspqr
+
+/.i./+g
+ Mississippi
+ Mississippi\A
+ Missouri river
+ Missouri river\A
+
+/^.is/+g
+ Mississippi
+
+/^ab\n/g+
+ ab\nab\ncd
+
+/^ab\n/mg+
+ ab\nab\ncd
+
+/abc/
+
+/abc|bac/
+
+/(abc|bac)/
+
+/(abc|(c|dc))/
+
+/(abc|(d|de)c)/
+
+/a*/
+
+/a+/
+
+/(baa|a+)/
+
+/a{0,3}/
+
+/baa{3,}/
+
+/"([^\\"]+|\\.)*"/
+
+/(abc|ab[cd])/
+
+/(a|.)/
+
+/a|ba|\w/
+
+/abc(?=pqr)/
+
+/...(?<=abc)/
+
+/abc(?!pqr)/
+
+/ab./
+
+/ab[xyz]/
+
+/abc*/
+
+/ab.c*/
+
+/a.c*/
+
+/.c*/
+
+/ac*/
+
+/(a.c*|b.c*)/
+
+/a.c*|aba/
+
+/.+a/
+
+/(?=abcda)a.*/
+
+/(?=a)a.*/
+
+/a(b)*/
+
+/a\d*/
+
+/ab\d*/
+
+/a(\d)*/
+
+/abcde{0,0}/
+
+/ab\d+/
+
+/a(?(1)b)/
+
+/a(?(1)bag|big)/
+
+/a(?(1)bag|big)*/
+
+/a(?(1)bag|big)+/
+
+/a(?(1)b..|b..)/
+
+/ab\d{0}e/
+
+/a?b?/
+ a
+ b
+ ab
+ \
+ *** Failers
+ \N
+
+/|-/
+ abcd
+ -abc
+ \Nab-c
+ *** Failers
+ \Nabc
+
+/.*?/g+
+ abc
+
/ End of test input /
/word (?>[a-zA-Z0-9]+ ){0,30}otherword/
word cat dog elephant mussel cow horse canary baboon snake shark the quick brown fox and the lazy dog and several other words getting close to thirty by now I hope
+/(?<=\d{3}(?!999))foo/
+ 999foo
+ 123999foo
+ *** Failers
+ 123abcfoo
+
+/(?<=(?!...999)\d{3})foo/
+ 999foo
+ 123999foo
+ *** Failers
+ 123abcfoo
+
+/(?<=\d{3}(?!999)...)foo/
+ 123abcfoo
+ 123456foo
+ *** Failers
+ 123999foo
+
+/(?<=\d{3}...)(?<!999)foo/
+ 123abcfoo
+ 123456foo
+ *** Failers
+ 123999foo
+
+/<a[\s]+href[\s]*=[\s]* # find <a href=
+ ([\"\'])? # find single or double quote
+ (?(1) (.*?)\1 | ([^\s]+)) # if quote found, match up to next matching
+ # quote, otherwise match up to next space
+/isx
+ <a href=abcd xyz
+ <a href=\"abcd xyz pqr\" cats
+ <a href=\'abcd xyz pqr\' cats
+
+/<a\s+href\s*=\s* # find <a href=
+ (["'])? # find single or double quote
+ (?(1) (.*?)\1 | (\S+)) # if quote found, match up to next matching
+ # quote, otherwise match up to next space
+/isx
+ <a href=abcd xyz
+ <a href=\"abcd xyz pqr\" cats
+ <a href = \'abcd xyz pqr\' cats
+
+/<a\s+href(?>\s*)=(?>\s*) # find <a href=
+ (["'])? # find single or double quote
+ (?(1) (.*?)\1 | (\S+)) # if quote found, match up to next matching
+ # quote, otherwise match up to next space
+/isx
+ <a href=abcd xyz
+ <a href=\"abcd xyz pqr\" cats
+ <a href = \'abcd xyz pqr\' cats
+
/ End of test input /
-PCRE version 2.05 21-Apr-1999
+PCRE version 2.08 31-Aug-1999
/the quick brown fox/
the quick brown fox
abcde\nBar
No match
+/^.*B/
+ **** Failers
+No match
+ abc\nB
+No match
+
+/(?s)^.*B/
+ abc\nB
+ 0: abc\x0aB
+
+/(?m)^.*B/
+ abc\nB
+ 0: B
+
+/(?ms)^.*B/
+ abc\nB
+ 0: abc\x0aB
+
+/(?ms)^B/
+ abc\nB
+ 0: B
+
+/(?s)B$/
+ B\n
+ 0: B
+
+/^[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]/
+ 123456654321
+ 0: 123456654321
+
+/^\d\d\d\d\d\d\d\d\d\d\d\d/
+ 123456654321
+ 0: 123456654321
+
+/^[\d][\d][\d][\d][\d][\d][\d][\d][\d][\d][\d][\d]/
+ 123456654321
+ 0: 123456654321
+
+/^[abc]{12}/
+ abcabcabcabc
+ 0: abcabcabcabc
+
+/^[a-c]{12}/
+ abcabcabcabc
+ 0: abcabcabcabc
+
+/^(a|b|c){12}/
+ abcabcabcabc
+ 0: abcabcabcabc
+ 1: c
+
+/^[abcdefghijklmnopqrstuvwxy0123456789]/
+ n
+ 0: n
+ *** Failers
+No match
+ z
+No match
+
+/abcde{0,0}/
+ abcd
+ 0: abcd
+ *** Failers
+No match
+ abce
+No match
+
+/ab[cd]{0,0}e/
+ abe
+ 0: abe
+ *** Failers
+No match
+ abcde
+No match
+
+/ab(c){0,0}d/
+ abd
+ 0: abd
+ *** Failers
+No match
+ abcd
+No match
+
+/a(b*)/
+ a
+ 0: a
+ 1:
+ ab
+ 0: ab
+ 1: b
+ abbbb
+ 0: abbbb
+ 1: bbbb
+ *** Failers
+ 0: a
+ 1:
+ bbbbb
+No match
+
+/ab\d{0}e/
+ abe
+ 0: abe
+ *** Failers
+No match
+ ab1e
+No match
+
+/"([^\\"]+|\\.)*"/
+ the \"quick\" brown fox
+ 0: "quick"
+ 1: quick
+ \"the \\\"quick\\\" brown fox\"
+ 0: "the \"quick\" brown fox"
+ 1: brown fox
+
/ End of test input /
-PCRE version 2.05 21-Apr-1999
+PCRE version 2.08 31-Aug-1999
/(a)b|/
Identifying subpattern count = 1
No options
No first char
+No req char
/abc/
Identifying subpattern count = 0
No options
First char = 'a'
+Req char = 'c'
abc
0: abc
defabc
Identifying subpattern count = 0
Options: anchored
No first char
+Req char = 'c'
abc
0: abc
\Aabc
Identifying subpattern count = 0
No options
First char = 'a'
+Req char = 'c'
/a*bc/
Identifying subpattern count = 0
No options
No first char
+Req char = 'c'
/a{3}bc/
Identifying subpattern count = 0
No options
First char = 'a'
+Req char = 'c'
/(abc|a+z)/
Identifying subpattern count = 1
No options
First char = 'a'
+No req char
/^abc$/
Identifying subpattern count = 0
Options: anchored
No first char
+Req char = 'c'
abc
0: abc
*** Failers
Identifying subpattern count = 0
No options
First char at start or follows \n
+Req char = 'b'
/.*?b/
Identifying subpattern count = 0
No options
First char at start or follows \n
+Req char = 'b'
/cat|dog|elephant/
Identifying subpattern count = 0
No options
No first char
+No req char
this sentence eventually mentions a cat
0: cat
this sentences rambles on and on for a while and then reaches elephant
Identifying subpattern count = 0
No options
No first char
+No req char
Starting character set: c d e
this sentence eventually mentions a cat
0: cat
Identifying subpattern count = 0
Options: caseless
No first char
+No req char
Starting character set: C D E c d e
this sentence eventually mentions a CAT cat
0: CAT
Identifying subpattern count = 0
No options
No first char
+No req char
Starting character set: a b c d
/(a|[^\dZ])/S
Identifying subpattern count = 1
No options
No first char
+No req char
Starting character set: \x00 \x01 \x02 \x03 \x04 \x05 \x06 \x07 \x08 \x09 \x0a
\x0b \x0c \x0d \x0e \x0f \x10 \x11 \x12 \x13 \x14 \x15 \x16 \x17 \x18 \x19
\x1a \x1b \x1c \x1d \x1e \x1f \x20 ! " # $ % & ' ( ) * + , - . / : ; < = >
Identifying subpattern count = 1
No options
No first char
+No req char
Starting character set: \x09 \x0a \x0b \x0c \x0d \x20 a b
/(ab\2)/
Identifying subpattern count = 3
No options
First char = 'a'
+Req char = 'c'
abcb
0: abcb
1: a
Identifying subpattern count = 3
No options
First char = 'a'
+No req char
abc
0: abc
1: a
Identifying subpattern count = 0
Options: dollar_endonly
First char = 'a'
+Req char = 'c'
abc
0: abc
*** Failers
Identifying subpattern count = 0
No options
First char = 't'
+Req char = 'x'
the quick brown fox
0: the quick brown fox
this is a line with the quick brown fox
Identifying subpattern count = 0
Options: anchored
No first char
+Req char = 'x'
the quick brown fox
0: the quick brown fox
*** Failers
Identifying subpattern count = 0
No options
No first char
+No req char
abcdef
0: abc
abcdef\B
Identifying subpattern count = 3
No options
First char at start or follows \n
+No req char
defabc
0: defabc
1: abc
Identifying subpattern count = 0
No options
No first char
+No req char
co-processors, and for
0: -pr
Identifying subpattern count = 0
No options
First char = '<'
+Req char = '>'
abc<def>ghi<klm>nop
0: <def>ghi<klm>
Identifying subpattern count = 0
No options
First char = '<'
+Req char = '>'
abc<def>ghi<klm>nop
0: <def>
Identifying subpattern count = 0
Options: ungreedy
First char = '<'
+Req char = '>'
abc<def>ghi<klm>nop
0: <def>
Identifying subpattern count = 0
Options: ungreedy
First char = '<'
+Req char = '>'
abc<def>ghi<klm>nop
0: <def>
Identifying subpattern count = 0
Options: ungreedy
First char = '<'
+Req char = '>'
abc<def>ghi<klm>nop
0: <def>ghi<klm>
Identifying subpattern count = 0
Options: ungreedy
First char = '='
+Req char = '='
abc========def
0: ===
Identifying subpattern count = 0
Options: ungreedy
First char = '='
+Req char = '='
abc========def
0: ========
Identifying subpattern count = 0
No options
First char = 'f'
+Req char = 'o'
foo
0: foo
catfoo
Identifying subpattern count = 0
Options: caseless
First char = 'a'
+Req char = 'c'
/(a|(?m)a)/
Identifying subpattern count = 1
No options
First char = 'a'
+No req char
/(?i)^1234/
Identifying subpattern count = 0
Options: anchored caseless
No first char
+Req char = '4'
/(^b|(?i)^d)/
Identifying subpattern count = 1
Options: anchored
+Case state changes
No first char
+No req char
/(?s).*/
Identifying subpattern count = 0
Options: anchored dotall
No first char
+No req char
/[abcd]/S
Identifying subpattern count = 0
No options
No first char
+No req char
Starting character set: a b c d
/(?i)[abcd]/S
Identifying subpattern count = 0
Options: caseless
No first char
+No req char
Starting character set: A B C D a b c d
/(?m)[xy]|(b|c)/S
Identifying subpattern count = 1
Options: multiline
No first char
+No req char
Starting character set: b c x y
/(^a|^b)/m
Identifying subpattern count = 1
Options: multiline
First char at start or follows \n
+No req char
/(?i)(^a|^b)/m
Identifying subpattern count = 1
Options: caseless multiline
First char at start or follows \n
+No req char
/(a)(?(1)a|b|c)/
Failed: conditional group contains more than two branches at offset 13
Identifying subpattern count = 1
No options
First char = 'b'
+Req char = 'h'
/((?i)blah)\s+\1/
Identifying subpattern count = 1
No options
+Case state changes
No first char
+Req char = 'h'
/((?i)b)/DS
------------------------------------------------------------------
------------------------------------------------------------------
Identifying subpattern count = 1
No options
+Case state changes
No first char
+Req char = 'b'
Starting character set: B b
/(a*b|(?i:c*(?-i)d))/S
Identifying subpattern count = 1
No options
+Case state changes
No first char
+No req char
Starting character set: C a b c d
/a$/
Identifying subpattern count = 0
No options
First char = 'a'
+No req char
a
0: a
a\n
Identifying subpattern count = 0
Options: multiline
First char = 'a'
+No req char
a
0: a
a\n
Identifying subpattern count = 0
Options: anchored multiline
No first char
+Req char = 'c'
/^abc/m
Identifying subpattern count = 0
Options: multiline
First char at start or follows \n
+Req char = 'c'
/^((a+)(?U)([ab]+)(?-U)([bc]+)(\w*))/
Identifying subpattern count = 5
Options: anchored
No first char
+Req char = 'a'
aaaaabbbbbcccccdef
0: aaaaabbbbbcccccdef
1: aaaaabbbbbcccccdef
Identifying subpattern count = 0
No options
No first char
+No req char
Starting character set: a b
/(?<!foo)(alpha|omega)/S
Identifying subpattern count = 1
No options
No first char
+Req char = 'a'
Starting character set: a o
/(?!alphabet)[ab]/S
Identifying subpattern count = 0
No options
No first char
+No req char
Starting character set: a b
/(?<=foo\n)^bar/m
Identifying subpattern count = 0
Options: multiline
First char at start or follows \n
+Req char = 'r'
/(?>^abc)/m
Identifying subpattern count = 0
Options: multiline
First char at start or follows \n
+Req char = 'c'
abc
0: abc
def\nabc
Identifying subpattern count = 0
No options
First char = 'T'
+Req char = 's'
/(?<=bullock|donkey)-cart/
Identifying subpattern count = 0
No options
First char = '-'
+Req char = 't'
the bullock-cart
0: -cart
a donkey-cart race
/(?<=ab(?i)x|y|z)/
Identifying subpattern count = 0
No options
+Case state changes
No first char
+No req char
/(?>.*)(?<=(abcd)|(xyz))/
Identifying subpattern count = 2
No options
First char at start or follows \n
+No req char
alphabetabcd
0: alphabetabcd
1: abcd
/(?<=ab(?i)x(?-i)y|(?i)z|b)ZZ/
Identifying subpattern count = 0
No options
+Case state changes
First char = 'Z'
+Req char = 'Z'
abxyZZ
0: ZZ
abXyZZ
Identifying subpattern count = 1
No options
First char = 'b'
+Req char = 'r'
bar
0: bar
foobbar
Identifying subpattern count = 0
No options
First char = 'T'
+Req char = 't'
/^(a)?(?(1)a|b)+$/
Identifying subpattern count = 1
Options: anchored
No first char
+No req char
*** Failers
No match
a
Identifying subpattern count = 0
No options
First char = 'T'
+Req char = 'g'
/^(a\1?){4}$/
Identifying subpattern count = 1
Options: anchored
No first char
+Req char = 'a'
aaaaaa
0: aaaaaa
1: aa
Identifying subpattern count = 0
No options
First char = 'T'
+Req char = '5'
/a[b-a]/
Failed: range out of order in character class at offset 4
Identifying subpattern count = 2
No options
First char = 'a'
+Req char = 'd'
abcd
0: abcd
1: a
Identifying subpattern count = 1
No options
No first char
+No req char
abcdefghijklmnopqrstuvwxyz
0: abcdefghijklmnopqrst
1: abcdefghijklmnopqrst
Identifying subpattern count = 1
No options
No first char
+No req char
abcdefghijklmnopqrstuvwxyz
0: abcdefghijklmno
1: abcdefghijklmno
Identifying subpattern count = 1
No options
No first char
+No req char
abcdefghijklmnopqrstuvwxyz
0: abcdefghijklmnop
1: abcdefghijklmnop
Identifying subpattern count = 3
Options: anchored
No first char
+Req char = 'f'
adef\G1\G2\G3\G4\L
0: adef
1: a
Identifying subpattern count = 0
Options: anchored
No first char
+Req char = 'f'
abc\00def\L\C0
0: abc\x00def
0C abc (7)
/word ((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+
)((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+ )((?:[a-zA-Z0-9]+
)?)?)?)?)?)?)?)?)?otherword/M
-Memory allocation request: 441 (code space 428)
+Memory allocation (code space): 428
Identifying subpattern count = 8
No options
First char = 'w'
+Req char = 'd'
/.*X/D
------------------------------------------------------------------
Identifying subpattern count = 0
No options
First char at start or follows \n
+Req char = 'X'
/.*X/Ds
------------------------------------------------------------------
Identifying subpattern count = 0
Options: anchored dotall
No first char
+Req char = 'X'
/(.*X|^B)/D
------------------------------------------------------------------
Identifying subpattern count = 1
No options
First char at start or follows \n
+No req char
/(.*X|^B)/Ds
------------------------------------------------------------------
Identifying subpattern count = 1
Options: anchored dotall
No first char
+No req char
/(?s)(.*X|^B)/D
------------------------------------------------------------------
Identifying subpattern count = 1
Options: anchored dotall
No first char
+No req char
/(?s:.*X|^B)/D
------------------------------------------------------------------
Identifying subpattern count = 0
No options
First char at start or follows \n
+No req char
+
+/\Biss\B/+
+Identifying subpattern count = 0
+No options
+First char = 'i'
+Req char = 's'
+ Mississippi
+ 0: iss
+ 0+ issippi
+
+/\Biss\B/+P
+ Mississippi
+ 0: iss
+ 0+ issippi
+
+/iss/G+
+Identifying subpattern count = 0
+No options
+First char = 'i'
+Req char = 's'
+ Mississippi
+ 0: iss
+ 0+ issippi
+ 0: iss
+ 0+ ippi
+
+/\Biss\B/G+
+Identifying subpattern count = 0
+No options
+First char = 'i'
+Req char = 's'
+ Mississippi
+ 0: iss
+ 0+ issippi
+
+/\Biss\B/g+
+Identifying subpattern count = 0
+No options
+First char = 'i'
+Req char = 's'
+ Mississippi
+ 0: iss
+ 0+ issippi
+ 0: iss
+ 0+ ippi
+ *** Failers
+No match
+ Mississippi\A
+No match
+
+/(?<=[Ms])iss/g+
+Identifying subpattern count = 0
+No options
+First char = 'i'
+Req char = 's'
+ Mississippi
+ 0: iss
+ 0+ issippi
+ 0: iss
+ 0+ ippi
+
+/(?<=[Ms])iss/G+
+Identifying subpattern count = 0
+No options
+First char = 'i'
+Req char = 's'
+ Mississippi
+ 0: iss
+ 0+ issippi
+
+/^iss/g+
+Identifying subpattern count = 0
+Options: anchored
+No first char
+Req char = 's'
+ ississippi
+ 0: iss
+ 0+ issippi
+
+/.*iss/g+
+Identifying subpattern count = 0
+No options
+First char at start or follows \n
+Req char = 's'
+ abciss\nxyzisspqr
+ 0: abciss
+ 0+ \x0axyzisspqr
+ 0: xyziss
+ 0+ pqr
+
+/.i./+g
+Identifying subpattern count = 0
+No options
+No first char
+Req char = 'i'
+ Mississippi
+ 0: Mis
+ 0+ sissippi
+ 0: sis
+ 0+ sippi
+ 0: sip
+ 0+ pi
+ Mississippi\A
+ 0: Mis
+ 0+ sissippi
+ 0: sis
+ 0+ sippi
+ 0: sip
+ 0+ pi
+ Missouri river
+ 0: Mis
+ 0+ souri river
+ 0: ri
+ 0+ river
+ 0: riv
+ 0+ er
+ Missouri river\A
+ 0: Mis
+ 0+ souri river
+
+/^.is/+g
+Identifying subpattern count = 0
+Options: anchored
+No first char
+Req char = 's'
+ Mississippi
+ 0: Mis
+ 0+ sissippi
+
+/^ab\n/g+
+Identifying subpattern count = 0
+Options: anchored
+No first char
+Req char = 10
+ ab\nab\ncd
+ 0: ab\x0a
+ 0+ ab\x0acd
+
+/^ab\n/mg+
+Identifying subpattern count = 0
+Options: multiline
+First char at start or follows \n
+Req char = 10
+ ab\nab\ncd
+ 0: ab\x0a
+ 0+ ab\x0acd
+ 0: ab\x0a
+ 0+ cd
+
+/abc/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+Req char = 'c'
+
+/abc|bac/
+Identifying subpattern count = 0
+No options
+No first char
+Req char = 'c'
+
+/(abc|bac)/
+Identifying subpattern count = 1
+No options
+No first char
+Req char = 'c'
+
+/(abc|(c|dc))/
+Identifying subpattern count = 2
+No options
+No first char
+Req char = 'c'
+
+/(abc|(d|de)c)/
+Identifying subpattern count = 2
+No options
+No first char
+Req char = 'c'
+
+/a*/
+Identifying subpattern count = 0
+No options
+No first char
+No req char
+
+/a+/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+No req char
+
+/(baa|a+)/
+Identifying subpattern count = 1
+No options
+No first char
+Req char = 'a'
+
+/a{0,3}/
+Identifying subpattern count = 0
+No options
+No first char
+No req char
+
+/baa{3,}/
+Identifying subpattern count = 0
+No options
+First char = 'b'
+Req char = 'a'
+
+/"([^\\"]+|\\.)*"/
+Identifying subpattern count = 1
+No options
+First char = '"'
+Req char = '"'
+
+/(abc|ab[cd])/
+Identifying subpattern count = 1
+No options
+First char = 'a'
+No req char
+
+/(a|.)/
+Identifying subpattern count = 1
+No options
+No first char
+No req char
+
+/a|ba|\w/
+Identifying subpattern count = 0
+No options
+No first char
+No req char
+
+/abc(?=pqr)/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+Req char = 'r'
+
+/...(?<=abc)/
+Identifying subpattern count = 0
+No options
+No first char
+No req char
+
+/abc(?!pqr)/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+Req char = 'c'
+
+/ab./
+Identifying subpattern count = 0
+No options
+First char = 'a'
+Req char = 'b'
+
+/ab[xyz]/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+Req char = 'b'
+
+/abc*/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+Req char = 'b'
+
+/ab.c*/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+Req char = 'b'
+
+/a.c*/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+No req char
+
+/.c*/
+Identifying subpattern count = 0
+No options
+No first char
+No req char
+
+/ac*/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+No req char
+
+/(a.c*|b.c*)/
+Identifying subpattern count = 1
+No options
+No first char
+No req char
+
+/a.c*|aba/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+No req char
+
+/.+a/
+Identifying subpattern count = 0
+No options
+No first char
+Req char = 'a'
+
+/(?=abcda)a.*/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+No req char
+
+/(?=a)a.*/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+No req char
+
+/a(b)*/
+Identifying subpattern count = 1
+No options
+First char = 'a'
+No req char
+
+/a\d*/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+No req char
+
+/ab\d*/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+Req char = 'b'
+
+/a(\d)*/
+Identifying subpattern count = 1
+No options
+First char = 'a'
+No req char
+
+/abcde{0,0}/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+Req char = 'd'
+
+/ab\d+/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+Req char = 'b'
+
+/a(?(1)b)/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+No req char
+
+/a(?(1)bag|big)/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+Req char = 'g'
+
+/a(?(1)bag|big)*/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+No req char
+
+/a(?(1)bag|big)+/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+Req char = 'g'
+
+/a(?(1)b..|b..)/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+Req char = 'b'
+
+/ab\d{0}e/
+Identifying subpattern count = 0
+No options
+First char = 'a'
+Req char = 'e'
+
+/a?b?/
+Identifying subpattern count = 0
+No options
+No first char
+No req char
+ a
+ 0: a
+ b
+ 0: b
+ ab
+ 0: ab
+ \
+ 0:
+ *** Failers
+ 0:
+ \N
+No match
+
+/|-/
+Identifying subpattern count = 0
+No options
+No first char
+No req char
+ abcd
+ 0:
+ -abc
+ 0:
+ \Nab-c
+ 0: -
+ *** Failers
+ 0:
+ \Nabc
+No match
+
+/.*?/g+
+Identifying subpattern count = 0
+No options
+First char at start or follows \n
+No req char
+ abc
+ 0:
+ 0+ abc
+ 0: a
+ 0+ bc
+ 0:
+ 0+ bc
+ 0: b
+ 0+ c
+ 0:
+ 0+ c
+ 0: c
+ 0+
+ 0:
+ 0+
/ End of test input /
Identifying subpattern count = 0
No options
First char = ' '
+Req char = ' '
-PCRE version 2.05 21-Apr-1999
+PCRE version 2.08 31-Aug-1999
/(?<!bar)foo/
foo
word cat dog elephant mussel cow horse canary baboon snake shark the quick brown fox and the lazy dog and several other words getting close to thirty by now I hope
No match
+/(?<=\d{3}(?!999))foo/
+ 999foo
+ 0: foo
+ 123999foo
+ 0: foo
+ *** Failers
+No match
+ 123abcfoo
+No match
+
+/(?<=(?!...999)\d{3})foo/
+ 999foo
+ 0: foo
+ 123999foo
+ 0: foo
+ *** Failers
+No match
+ 123abcfoo
+No match
+
+/(?<=\d{3}(?!999)...)foo/
+ 123abcfoo
+ 0: foo
+ 123456foo
+ 0: foo
+ *** Failers
+No match
+ 123999foo
+No match
+
+/(?<=\d{3}...)(?<!999)foo/
+ 123abcfoo
+ 0: foo
+ 123456foo
+ 0: foo
+ *** Failers
+No match
+ 123999foo
+No match
+
+/<a[\s]+href[\s]*=[\s]* # find <a href=
+ ([\"\'])? # find single or double quote
+ (?(1) (.*?)\1 | ([^\s]+)) # if quote found, match up to next matching
+ # quote, otherwise match up to next space
+/isx
+ <a href=abcd xyz
+ 0: <a href=abcd
+ 1: <unset>
+ 2: <unset>
+ 3: abcd
+ <a href=\"abcd xyz pqr\" cats
+ 0: <a href="abcd xyz pqr"
+ 1: "
+ 2: abcd xyz pqr
+ <a href=\'abcd xyz pqr\' cats
+ 0: <a href='abcd xyz pqr'
+ 1: '
+ 2: abcd xyz pqr
+
+/<a\s+href\s*=\s* # find <a href=
+ (["'])? # find single or double quote
+ (?(1) (.*?)\1 | (\S+)) # if quote found, match up to next matching
+ # quote, otherwise match up to next space
+/isx
+ <a href=abcd xyz
+ 0: <a href=abcd
+ 1: <unset>
+ 2: <unset>
+ 3: abcd
+ <a href=\"abcd xyz pqr\" cats
+ 0: <a href="abcd xyz pqr"
+ 1: "
+ 2: abcd xyz pqr
+ <a href = \'abcd xyz pqr\' cats
+ 0: <a href = 'abcd xyz pqr'
+ 1: '
+ 2: abcd xyz pqr
+
+/<a\s+href(?>\s*)=(?>\s*) # find <a href=
+ (["'])? # find single or double quote
+ (?(1) (.*?)\1 | (\S+)) # if quote found, match up to next matching
+ # quote, otherwise match up to next space
+/isx
+ <a href=abcd xyz
+ 0: <a href=abcd
+ 1: <unset>
+ 2: <unset>
+ 3: abcd
+ <a href=\"abcd xyz pqr\" cats
+ 0: <a href="abcd xyz pqr"
+ 1: "
+ 2: abcd xyz pqr
+ <a href = \'abcd xyz pqr\' cats
+ 0: <a href = 'abcd xyz pqr'
+ 1: '
+ 2: abcd xyz pqr
+
/ End of test input /
-PCRE version 2.05 21-Apr-1999
+PCRE version 2.08 31-Aug-1999
/^[\w]+/
*** Failers
Identifying subpattern count = 0
No options
No first char
+No req char
Starting character set: 0 1 2 3 4 5 6 7 8 9 A B C D E F G H I J K L M N O P
Q R S T U V W X Y Z _ a b c d e f g h i j k l m n o p q r s t u v w x y z
Identifying subpattern count = 0
No options
No first char
+No req char
Starting character set: 0 1 2 3 4 5 6 7 8 9 A B C D E F G H I J K L M N O P
Q R S T U V W X Y Z _ a b c d e f g h i j k l m n o p q r s t u v w x y z
À Á Â Ã Ä Å Æ Ç È É Ê Ë Ì Í Î Ï Ð Ñ Ò Ó Ô Õ Ö Ø Ù Ú Û Ü Ý Þ ß à á â ã ä å
/* $Id$ */
+/*
+ TODO:
+ - Allow user to set PCRE_NOTEMPTY, PCRE_ANCHORED at execution time
+ - Have an option for preg_split() to not return empty strings
+*/
+
#include "php.h"
#include "php_globals.h"
+#include "php_pcre.h"
-#if HAVE_PCRE
+#if HAVE_PCRE || HAVE_BUNDLED_PCRE
-#include "php_pcre.h"
#include "ext/standard/php3_string.h"
#define PREG_PATTERN_ORDER 0
int *offsets; /* Array of subpattern offsets */
int num_subpats; /* Number of captured subpatterns */
int size_offsets; /* Size of the offsets array */
+ int start_offset; /* Where the new search starts */
int matched; /* Has anything matched */
int i;
int subpats_order_val = 0; /* Integer value of subpats_order */
+ int g_notempty = 0; /* If the match should not be empty */
const char **stringlist; /* Used to hold list of subpatterns */
- char *match, /* The current match */
- *piece, /* The current piece of subject */
- *subject_end; /* Points to the end of the subject */
+ char *match; /* The current match */
/* Get function parameters and do error-checking. */
}
/* Start from the beginning of the string */
- piece = subject->value.str.val;
- subject_end = piece + subject->value.str.len;
+ start_offset = 0;
match = NULL;
matched = 0;
do {
/* Execute the regular expression. */
- count = pcre_exec(re, extra, piece,
- subject_end-piece, subject->value.str.val,
- (piece==subject->value.str.val ? exoptions : exoptions|PCRE_NOTBOL),
- offsets, size_offsets, (piece == match));
+ count = pcre_exec(re, extra, subject->value.str.val,
+ subject->value.str.len, start_offset,
+ exoptions|g_notempty, offsets, size_offsets);
/* Check for too many substrings condition. */
if (count == 0) {
/* If something has matched */
if (count >= 0) {
matched++;
- match = piece + offsets[0];
+ match = subject->value.str.val + offsets[0];
/* If subpatters array has been passed, fill it in with values. */
if (subpats != NULL) {
/* Try to get the list of substrings and display a warning if failed. */
- if (pcre_get_substring_list(piece, offsets, count, &stringlist) < 0) {
+ if (pcre_get_substring_list(subject->value.str.val,
+ offsets, count, &stringlist) < 0) {
efree(offsets);
efree(re);
zend_error(E_WARNING, "Get subpatterns list failed");
}
php_pcre_free((void *) stringlist);
-
- /* Advance to the position right after the last full match */
- piece += offsets[1];
}
}
- } while (global && count >= 0);
+ else { /* Failed to match */
+ /* If we previously set PCRE_NOTEMPTY after a null match,
+ this is not necessarily the end. We need to advance
+ the start offset, and continue. Fudge the offset values
+ to achieve this, unless we're already at the end of the string. */
+ if (g_notempty != 0 && start_offset < subject->value.str.len) {
+ offsets[0] = start_offset;
+ offsets[1] = start_offset + 1;
+ } else
+ break;
+ }
+
+ /* If we have matched an empty string, mimic what Perl's /g options does.
+ This turns out to be rather cunning. First we set PCRE_NOTEMPTY and try
+ the match again at the same point. If this fails (picked up above) we
+ advance to the next character. */
+ g_notempty = (offsets[1] == offsets[0])? PCRE_NOTEMPTY : 0;
+
+ /* Advance to the position right after the last full match */
+ start_offset = offsets[1];
+ } while (global);
/* Add the match sets to the output array and clean up */
if (global && subpats_order_val == PREG_PATTERN_ORDER) {
int match_len; /* Length of the current match */
int backref; /* Backreference number */
int eval; /* If the replacement string should be eval'ed */
+ int start_offset; /* Where the new search starts */
+ int g_notempty = 0; /* If the match should not be empty */
char *result, /* Result of replacement */
*new_buf, /* Temporary buffer for re-allocation */
*walkbuf, /* Location of current replacement in the result */
*walk, /* Used to walk the replacement string */
*match, /* The current match */
*piece, /* The current piece of subject */
- *subject_end, /* Points to the end of the subject */
*eval_result; /* Result of eval */
/* Compile regex or get it from cache. */
/* Initialize */
match = NULL;
result[0] = '\0';
- piece = subject;
- subject_end = subject + subject_len;
+ start_offset = 0;
eval = preg_options & PREG_REPLACE_EVAL;
- while (count >= 0) {
+ while (1) {
/* Execute the regular expression. */
- count = pcre_exec(re, extra, piece,
- subject_end-piece, subject,
- (piece==subject ? exoptions : exoptions|PCRE_NOTBOL),
- offsets, size_offsets, (piece == match));
+ count = pcre_exec(re, extra, subject, subject_len, start_offset,
+ exoptions|g_notempty, offsets, size_offsets);
/* Check for too many substrings condition. */
if (count == 0) {
count = size_offsets/3;
}
+ piece = &subject[start_offset];
+
if (count > 0) {
- /* Set the match location in piece */
- match = piece + offsets[0];
+ /* Set the match location in subject */
+ match = subject + offsets[0];
- new_len = strlen(result) + offsets[0]; /* part before the match */
+ new_len = strlen(result) + offsets[0] - start_offset; /* part before the match */
/* If evaluating, do it and add the return string's length */
if (eval) {
strncat(result, piece, match-piece);
/* copy replacement and backrefs */
- walkbuf = &result[result_len + offsets[0]];
+ walkbuf = &result[result_len + offsets[0] - start_offset];
/* If evaluating, copy result to the buffer and clean up */
if (eval) {
*walkbuf++ = *walk++;
}
*walkbuf = '\0';
-
- /* Advance to the next piece */
- piece += offsets[1];
- } else {
- new_len = strlen(result) + subject_end-piece;
- if (new_len + 1 > alloc_len) {
- alloc_len = new_len + 1; /* now we know exactly how long it is */
- new_buf = emalloc(alloc_len * sizeof(char));
- strcpy(new_buf, result);
- efree(result);
- result = new_buf;
+ } else { /* Failed to match */
+ /* If we previously set PCRE_NOTEMPTY after a null match,
+ this is not necessarily the end. We need to advance
+ the start offset, and continue. Fudge the offset values
+ to achieve this, unless we're already at the end of the string. */
+ if (g_notempty != 0 && start_offset < subject_len) {
+ offsets[0] = start_offset;
+ offsets[1] = start_offset + 1;
+ strncat(result, piece, 1);
+ }
+ else {
+ new_len = strlen(result) + subject_len - start_offset;
+ if (new_len + 1 > alloc_len) {
+ alloc_len = new_len + 1; /* now we know exactly how long it is */
+ new_buf = emalloc(alloc_len * sizeof(char));
+ strcpy(new_buf, result);
+ efree(result);
+ result = new_buf;
+ }
+ /* stick that last bit of string on our output */
+ strcat(result, piece);
+ break;
}
- /* stick that last bit of string on our output */
- strcat(result, piece);
}
+
+ /* If we have matched an empty string, mimic what Perl's /g options does.
+ This turns out to be rather cunning. First we set PCRE_NOTEMPTY and try
+ the match again at the same point. If this fails (picked up above) we
+ advance to the next character. */
+ g_notempty = (offsets[1] == offsets[0])? PCRE_NOTEMPTY : 0;
+
+ /* Advance to the next piece */
+ start_offset = offsets[1];
}
efree(offsets);
int argc; /* Argument count */
int limit_val; /* Integer value of limit */
int count = 0; /* Count of matched subpatterns */
+ int start_offset; /* Where the new search starts */
+ int g_notempty = 0; /* If the match should not be empty */
char *match, /* The current match */
- *piece, /* The current piece of subject */
- *subject_end; /* Points to the end of subject string */
+ *last_match; /* Location of last match */
/* Get function parameters and do error checking */
argc = ARG_COUNT(ht);
offsets = (int *)emalloc(size_offsets * sizeof(int));
/* Start at the beginning of the string */
- piece = subject->value.str.val;
- subject_end = piece + subject->value.str.len;
+ start_offset = 0;
+ last_match = subject->value.str.val;
match = NULL;
/* Get next piece if no limit or limit not yet reached and something matched*/
- while ((limit_val == -1 || limit_val > 1) && count >= 0) {
- count = pcre_exec(re, extra, piece,
- subject_end-piece, subject->value.str.val,
- (piece==subject->value.str.val ? exoptions : exoptions|PCRE_NOTBOL),
- offsets, size_offsets, (piece==match));
+ while ((limit_val == -1 || limit_val > 1)) {
+ count = pcre_exec(re, extra, subject->value.str.val,
+ subject->value.str.len, start_offset,
+ exoptions|g_notempty, offsets, size_offsets);
/* Check for too many substrings condition. */
if (count == 0) {
zend_error(E_NOTICE, "Matched, but too many substrings\n");
count = size_offsets/3;
}
-
+
/* If something matched */
if (count > 0) {
- match = piece + offsets[0];
-
+ match = subject->value.str.val + offsets[0];
+
/* Add the piece to the return value */
- add_next_index_stringl(return_value,
- piece,
- offsets[0], 1);
+ add_next_index_stringl(return_value, last_match,
+ &subject->value.str.val[offsets[0]]-last_match, 1);
- /* Advance to next position */
- piece += offsets[1];
+ last_match = &subject->value.str.val[offsets[1]];
/* One less left to do */
if (limit_val != -1)
limit_val--;
+ } else { /* Failed to match */
+ /* If we previously set PCRE_NOTEMPTY after a null match,
+ this is not necessarily the end. We need to advance
+ the start offset, and continue. Fudge the offset values
+ to achieve this, unless we're already at the end of the string. */
+ if (g_notempty != 0 && start_offset < subject->value.str.len) {
+ offsets[0] = start_offset;
+ offsets[1] = start_offset + 1;
+ } else
+ break;
}
+
+ /* If we have matched an empty string, mimic what Perl's /g options does.
+ This turns out to be rather cunning. First we set PCRE_NOTEMPTY and try
+ the match again at the same point. If this fails (picked up above) we
+ advance to the next character. */
+ g_notempty = (offsets[1] == offsets[0])? PCRE_NOTEMPTY : 0;
+
+ /* Advance to the position right after the last full match */
+ start_offset = offsets[1];
}
/* Add the last piece to the return value */
- add_next_index_stringl(return_value,
- piece,
- subject_end-piece, 1);
+ add_next_index_string(return_value,
+ &subject->value.str.val[start_offset], 1);
/* Clean up */
efree(offsets);
/* Perform the match */
count = pcre_exec(re, extra, entry->value.str.val,
- entry->value.str.len, entry->value.str.val,
- 0, offsets, size_offsets, 0);
+ entry->value.str.len, 0,
+ 0, offsets, size_offsets);
/* Check for too many substrings condition. */
if (count == 0) {
};
zend_module_entry pcre_module_entry = {
- "PCRE", pcre_functions, PHP_MINIT(pcre), PHP_MSHUTDOWN(pcre),
- PHP_RINIT(pcre), NULL,
- PHP_MINFO(pcre), STANDARD_MODULE_PROPERTIES
+ "PCRE", pcre_functions,
+ PHP_MINIT(pcre),
+ PHP_MSHUTDOWN(pcre),
+ PHP_RINIT(pcre),
+ NULL,
+ PHP_MINFO(pcre),
+ STANDARD_MODULE_PROPERTIES
};
/* }}} */
-#endif /* HAVE_PCRE */
+#endif /* HAVE_PCRE || HAVE_BUNDLED_PCRE */
/*
* Local variables:
#ifndef _PHP_PCRE_H
#define _PHP_PCRE_H
-#if HAVE_PCRE
+#if HAVE_PCRE || HAVE_BUNDLED_PCRE
+#if HAVE_BUNDLED_PCRE
#include "pcrelib/pcre.h"
+#else
+#include "pcre.h"
+#endif
+
#if HAVE_LOCALE_H
#include <locale.h>
#endif
#define pcre_module_ptr NULL
-#endif /* HAVE_PCRE */
+#endif /* HAVE_PCRE || HAVE_BUNDLED_PCRE */
#define phpext_pcre_ptr pcre_module_ptr
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