/[pcre]/code/trunk/doc/pcre.txt

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-revision 83 by nigel,
Sat Feb 24 21:41:06 2007 UTC
+revision 512 by ph10,
Tue Mar 30 11:11:52 2010 UTC
 Line 2
  This file contains a concatenation of the PCRE man pages, converted to plain
  text format for ease of searching with a text editor, or for use on systems
  that do not have a man page processor. The small individual files that give
- synopses of each function in the library have not been included. There are
+ synopses of each function in the library have not been included. Neither has
- separate text files for the pcregrep and pcretest commands.
+ the pcredemo program. There are separate text files for the pcregrep and
+ pcretest commands.
  -----------------------------------------------------------------------------
-Line 18 
 INTRODUCTION
+Line 19 
 INTRODUCTION
         The  PCRE  library is a set of functions that implement regular expres-
         sion pattern matching using the same syntax and semantics as Perl, with
-        just  a  few  differences.  The current implementation of PCRE (release
+        just  a few differences. Some features that appeared in Python and PCRE
-.x) corresponds approximately with Perl  5.8,  including  support  for
+        before they appeared in Perl are also available using the  Python  syn-
-        UTF-8 encoded strings and Unicode general category properties. However,
+        tax,  there  is  some  support for one or two .NET and Oniguruma syntax
-        this support has to be explicitly enabled; it is not the default.
+        items, and there is an option for requesting some  minor  changes  that
+        give better JavaScript compatibility.
-        In addition to the Perl-compatible matching function,  PCRE  also  con-
-        tains  an  alternative matching function that matches the same compiled
+        The  current implementation of PCRE corresponds approximately with Perl
-        patterns in a different way. In certain circumstances, the  alternative
+.10, including support for UTF-8 encoded strings and  Unicode  general
-        function  has  some  advantages.  For  a discussion of the two matching
+        category  properties.  However,  UTF-8  and  Unicode  support has to be
-        algorithms, see the pcrematching page.
+        explicitly enabled; it is not the default. The  Unicode  tables  corre-
+        spond to Unicode release 5.2.0.
-        PCRE is written in C and released as a C library. A  number  of  people
-        have  written  wrappers and interfaces of various kinds. In particular,
+        In  addition to the Perl-compatible matching function, PCRE contains an
-        Google Inc.  have provided a comprehensive C++  wrapper.  This  is  now
+        alternative function that matches the same compiled patterns in a  dif-
+        ferent way. In certain circumstances, the alternative function has some
+        advantages.  For a discussion of the two matching algorithms,  see  the
+        pcrematching page.
+        PCRE  is  written  in C and released as a C library. A number of people
+        have written wrappers and interfaces of various kinds.  In  particular,
+        Google  Inc.   have  provided  a comprehensive C++ wrapper. This is now
         included as part of the PCRE distribution. The pcrecpp page has details
-        of this interface. Other people's contributions can  be  found  in  the
+        of  this  interface.  Other  people's contributions can be found in the
         Contrib directory at the primary FTP site, which is:
         ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre
-        Details  of  exactly which Perl regular expression features are and are
+        Details of exactly which Perl regular expression features are  and  are
         not supported by PCRE are given in separate documents. See the pcrepat-
-        tern and pcrecompat pages.
+        tern and pcrecompat pages. There is a syntax summary in the  pcresyntax
+        page.
         Some  features  of  PCRE can be included, excluded, or changed when the
         library is built. The pcre_config() function makes it  possible  for  a
         client  to  discover  which  features are available. The features them-
         selves are described in the pcrebuild page. Documentation about  build-
-        ing  PCRE for various operating systems can be found in the README file
+        ing  PCRE  for various operating systems can be found in the README and
-        in the source distribution.
+        NON-UNIX-USE files in the source distribution.
         The library contains a number of undocumented  internal  functions  and
         data  tables  that  are  used by more than one of the exported external
-Line 63 
 USER DOCUMENTATION
+Line 72 
 USER DOCUMENTATION
         The user documentation for PCRE comprises a number  of  different  sec-
         tions.  In the "man" format, each of these is a separate "man page". In
         the HTML format, each is a separate page, linked from the  index  page.
-        In  the  plain text format, all the sections are concatenated, for ease
+        In  the  plain  text format, all the sections, except the pcredemo sec-
-        of searching. The sections are as follows:
+        tion, are concatenated, for ease of searching. The sections are as fol-
+        lows:
           pcre              this document
+          pcre-config       show PCRE installation configuration information
           pcreapi           details of PCRE's native C API
           pcrebuild         options for building PCRE
           pcrecallout       details of the callout feature
           pcrecompat        discussion of Perl compatibility
           pcrecpp           details of the C++ wrapper
+          pcredemo          a demonstration C program that uses PCRE
           pcregrep          description of the pcregrep command
           pcrematching      discussion of the two matching algorithms
           pcrepartial       details of the partial matching facility
-Line 80 
 USER DOCUMENTATION
+Line 92 
 USER DOCUMENTATION
           pcreperform       discussion of performance issues
           pcreposix         the POSIX-compatible C API
           pcreprecompile    details of saving and re-using precompiled patterns
-          pcresample        discussion of the sample program
+          pcresample        discussion of the pcredemo program
+          pcrestack         discussion of stack usage
+          pcresyntax        quick syntax reference
           pcretest          description of the pcretest testing command
         In  addition,  in the "man" and HTML formats, there is a short page for
-Line 98 
 LIMITATIONS
+Line 112 
 LIMITATIONS
         PCRE with an internal linkage size of 3 or 4 (see the  README  file  in
         the  source  distribution and the pcrebuild documentation for details).
         In these cases the limit is substantially larger.  However,  the  speed
-        of execution will be slower.
+        of execution is slower.
-        All values in repeating quantifiers must be less than 65536.  The maxi-
+        All values in repeating quantifiers must be less than 65536.
-        mum number of capturing subpatterns is 65535.
-        There is no limit to the number of non-capturing subpatterns,  but  the
+        There is no limit to the number of parenthesized subpatterns, but there
-        maximum  depth  of  nesting  of  all kinds of parenthesized subpattern,
+        can be no more than 65535 capturing subpatterns.
-        including capturing subpatterns, assertions, and other types of subpat-
-        tern, is 200.
+        The maximum length of name for a named subpattern is 32 characters, and
+        the maximum number of named subpatterns is 10000.
         The  maximum  length of a subject string is the largest positive number
         that an integer variable can hold. However, when using the  traditional
         matching function, PCRE uses recursion to handle subpatterns and indef-
         inite repetition.  This means that the available stack space may  limit
         the size of a subject string that can be processed by certain patterns.
+        For a discussion of stack issues, see the pcrestack documentation.
  UTF-8 AND UNICODE PROPERTY SUPPORT
-Line 124 
 UTF-8 AND UNICODE PROPERTY SUPPORT
+Line 139 
 UTF-8 AND UNICODE PROPERTY SUPPORT
         In  order  process  UTF-8 strings, you must build PCRE to include UTF-8
         support in the code, and, in addition,  you  must  call  pcre_compile()
-        with  the PCRE_UTF8 option flag. When you do this, both the pattern and
+        with  the  PCRE_UTF8  option  flag,  or the pattern must start with the
-        any subject strings that are matched against it are  treated  as  UTF-8
+        sequence (*UTF8). When either of these is the case,  both  the  pattern
-        strings instead of just strings of bytes.
+        and  any  subject  strings  that  are matched against it are treated as
+        UTF-8 strings instead of strings of 1-byte characters.
-        If  you compile PCRE with UTF-8 support, but do not use it at run time,
-        the library will be a bit bigger, but the additional run time  overhead
+        If you compile PCRE with UTF-8 support, but do not use it at run  time,
-        is  limited  to testing the PCRE_UTF8 flag in several places, so should
+        the  library will be a bit bigger, but the additional run time overhead
-        not be very large.
+        is limited to testing the PCRE_UTF8 flag occasionally, so should not be
+        very big.
         If PCRE is built with Unicode character property support (which implies
-        UTF-8  support),  the  escape sequences \p{..}, \P{..}, and \X are sup-
+        UTF-8 support), the escape sequences \p{..}, \P{..}, and  \X  are  sup-
         ported.  The available properties that can be tested are limited to the
-        general  category  properties such as Lu for an upper case letter or Nd
+        general category properties such as Lu for an upper case letter  or  Nd
-        for a decimal number. A full list is given in the pcrepattern  documen-
+        for  a  decimal number, the Unicode script names such as Arabic or Han,
-        tation. The PCRE library is increased in size by about 90K when Unicode
+        and the derived properties Any and L&. A full  list  is  given  in  the
-        property support is included.
+        pcrepattern documentation. Only the short names for properties are sup-
+        ported. For example, \p{L} matches a letter. Its Perl synonym,  \p{Let-
-        The following comments apply when PCRE is running in UTF-8 mode:
+        ter},  is  not  supported.   Furthermore,  in Perl, many properties may
+        optionally be prefixed by "Is", for compatibility with Perl  5.6.  PCRE
-. When you set the PCRE_UTF8 flag, the strings passed as patterns  and
+        does not support this.
-        subjects  are  checked for validity on entry to the relevant functions.
-        If an invalid UTF-8 string is passed, an error return is given. In some
+    Validity of UTF-8 strings
-        situations,  you  may  already  know  that  your strings are valid, and
-        therefore want to skip these checks in order to improve performance. If
+        When  you  set  the  PCRE_UTF8 flag, the strings passed as patterns and
-        you  set  the  PCRE_NO_UTF8_CHECK  flag at compile time or at run time,
+        subjects are (by default) checked for validity on entry to the relevant
-        PCRE assumes that the pattern or subject  it  is  given  (respectively)
+        functions.  From  release 7.3 of PCRE, the check is according the rules
-        contains  only valid UTF-8 codes. In this case, it does not diagnose an
+        of RFC 3629, which are themselves derived from the  Unicode  specifica-
-        invalid UTF-8 string. If you pass an invalid UTF-8 string to PCRE  when
+        tion.  Earlier  releases  of PCRE followed the rules of RFC 2279, which
-        PCRE_NO_UTF8_CHECK  is set, the results are undefined. Your program may
+        allows the full range of 31-bit values (0 to 0x7FFFFFFF).  The  current
-        crash.
+        check allows only values in the range U+0 to U+10FFFF, excluding U+D800
+        to U+DFFF.
-. In a pattern, the escape sequence \x{...}, where the contents of the
-        braces  is  a  string  of hexadecimal digits, is interpreted as a UTF-8
+        The excluded code points are the "Low Surrogate Area"  of  Unicode,  of
-        character whose code number is the given hexadecimal number, for  exam-
+        which  the Unicode Standard says this: "The Low Surrogate Area does not
-        ple:  \x{1234}.  If a non-hexadecimal digit appears between the braces,
+        contain any  character  assignments,  consequently  no  character  code
-        the item is not recognized.  This escape sequence can be used either as
+        charts or namelists are provided for this area. Surrogates are reserved
-        a literal, or within a character class.
+        for use with UTF-16 and then must be used in pairs."  The  code  points
+        that  are  encoded  by  UTF-16  pairs are available as independent code
+        points in the UTF-8 encoding. (In  other  words,  the  whole  surrogate
+        thing is a fudge for UTF-16 which unfortunately messes up UTF-8.)
+        If  an  invalid  UTF-8  string  is  passed  to  PCRE,  an  error return
+        (PCRE_ERROR_BADUTF8) is given. In some situations, you may already know
+        that your strings are valid, and therefore want to skip these checks in
+        order to improve performance. If you set the PCRE_NO_UTF8_CHECK flag at
+        compile  time  or at run time, PCRE assumes that the pattern or subject
+        it is given (respectively) contains only valid  UTF-8  codes.  In  this
+        case, it does not diagnose an invalid UTF-8 string.
+        If  you  pass  an  invalid UTF-8 string when PCRE_NO_UTF8_CHECK is set,
+        what happens depends on why the string is invalid. If the  string  con-
+        forms to the "old" definition of UTF-8 (RFC 2279), it is processed as a
+        string of characters in the range 0  to  0x7FFFFFFF.  In  other  words,
+        apart from the initial validity test, PCRE (when in UTF-8 mode) handles
+        strings according to the more liberal rules of RFC  2279.  However,  if
+        the  string does not even conform to RFC 2279, the result is undefined.
+        Your program may crash.
+        If you want to process strings  of  values  in  the  full  range  0  to
+x7FFFFFFF,  encoded in a UTF-8-like manner as per the old RFC, you can
+        set PCRE_NO_UTF8_CHECK to bypass the more restrictive test. However, in
+        this situation, you will have to apply your own validity check.
+    General comments about UTF-8 mode
+.  An  unbraced  hexadecimal  escape sequence (such as \xb3) matches a
+        two-byte UTF-8 character if the value is greater than 127.
-.  The  original hexadecimal escape sequence, \xhh, matches a two-byte
+. Octal numbers up to \777 are recognized, and  match  two-byte  UTF-8
-        UTF-8 character if the value is greater than 127.
+        characters for values greater than \177.
-. Repeat quantifiers apply to complete UTF-8 characters, not to  indi-
+.  Repeat quantifiers apply to complete UTF-8 characters, not to indi-
         vidual bytes, for example: \x{100}{3}.
-.  The dot metacharacter matches one UTF-8 character instead of a sin-
+. The dot metacharacter matches one UTF-8 character instead of a  sin-
         gle byte.
-. The escape sequence \C can be used to match a single byte  in  UTF-8
+.  The  escape sequence \C can be used to match a single byte in UTF-8
-        mode,  but  its  use can lead to some strange effects. This facility is
+        mode, but its use can lead to some strange effects.  This  facility  is
         not available in the alternative matching function, pcre_dfa_exec().
-. The character escapes \b, \B, \d, \D, \s, \S, \w, and  \W  correctly
+.  The  character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly
-        test  characters of any code value, but the characters that PCRE recog-
+        test characters of any code value, but the characters that PCRE  recog-
-        nizes as digits, spaces, or word characters  remain  the  same  set  as
+        nizes  as  digits,  spaces,  or  word characters remain the same set as
         before, all with values less than 256. This remains true even when PCRE
-        includes Unicode property support, because to do otherwise  would  slow
+        includes  Unicode  property support, because to do otherwise would slow
-        down  PCRE in many common cases. If you really want to test for a wider
+        down PCRE in many common cases. If you really want to test for a  wider
-        sense of, say, "digit", you must use Unicode  property  tests  such  as
+        sense  of,  say,  "digit",  you must use Unicode property tests such as
-        \p{Nd}.
+        \p{Nd}. Note that this also applies to \b, because  it  is  defined  in
+        terms of \w and \W.
 .  Similarly,  characters that match the POSIX named character classes
         are all low-valued characters.
+. However, the Perl 5.10 horizontal and vertical  whitespace  matching
+        escapes (\h, \H, \v, and \V) do match all the appropriate Unicode char-
+        acters.
 . Case-insensitive matching applies only to  characters  whose  values
         are  less than 128, unless PCRE is built with Unicode property support.
         Even when Unicode property support is available, PCRE  still  uses  its
         own  character  tables when checking the case of low-valued characters,
         so as not to degrade performance.  The Unicode property information  is
-        used only for characters with higher values.
+        used only for characters with higher values. Even when Unicode property
+        support is available, PCRE supports case-insensitive matching only when
+        there  is  a  one-to-one  mapping between a letter's cases. There are a
+        small number of many-to-one mappings in Unicode;  these  are  not  sup-
+        ported by PCRE.
  AUTHOR
         Philip Hazel
-        University Computing Service,
+        University Computing Service
-        Cambridge CB2 3QG, England.
+        Cambridge CB2 3QH, England.
         Putting  an actual email address here seems to have been a spam magnet,
-        so I've taken it away. If you want to email me, use my initial and sur-
+        so I've taken it away. If you want to email me, use  my  two  initials,
-        name, separated by a dot, at the domain ucs.cam.ac.uk.
+        followed by the two digits 10, at the domain cam.ac.uk.
- Last updated: 07 March 2005
+ REVISION
- Copyright (c) 1997-2005 University of Cambridge.
+        Last updated: 01 March 2010
+        Copyright (c) 1997-2010 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 220 
 NAME
+Line 278 
 NAME
  PCRE BUILD-TIME OPTIONS
         This  document  describes  the  optional  features  of PCRE that can be
-        selected when the library is compiled. They are all selected, or  dese-
+        selected when the library is compiled. It assumes use of the  configure
-        lected, by providing options to the configure script that is run before
+        script,  where the optional features are selected or deselected by pro-
-        the make command. The complete list of  options  for  configure  (which
+        viding options to configure before running the make  command.  However,
-        includes  the  standard  ones such as the selection of the installation
+        the  same  options  can be selected in both Unix-like and non-Unix-like
-        directory) can be obtained by running
+        environments using the GUI facility of cmake-gui if you are using CMake
+        instead of configure to build PCRE.
+        There  is  a  lot more information about building PCRE in non-Unix-like
+        environments in the file called NON_UNIX_USE, which is part of the PCRE
+        distribution.  You  should consult this file as well as the README file
+        if you are building in a non-Unix-like environment.
+        The complete list of options for configure (which includes the standard
+        ones  such  as  the  selection  of  the  installation directory) can be
+        obtained by running
           ./configure --help
-        The following sections describe certain options whose names begin  with
+        The following sections include  descriptions  of  options  whose  names
-        --enable  or  --disable. These settings specify changes to the defaults
+        begin with --enable or --disable. These settings specify changes to the
-        for the configure command. Because of the  way  that  configure  works,
+        defaults for the configure command. Because of the way  that  configure
-        --enable  and  --disable  always  come  in  pairs, so the complementary
+        works,  --enable  and --disable always come in pairs, so the complemen-
-        option always exists as well, but as it specifies the  default,  it  is
+        tary option always exists as well, but as it specifies the default,  it
-        not described.
+        is not described.
  C++ SUPPORT
-Line 249 
 C++ SUPPORT
+Line 317 
 C++ SUPPORT
  UTF-8 SUPPORT
-        To build PCRE with support for UTF-8 character strings, add
+        To build PCRE with support for UTF-8 Unicode character strings, add
           --enable-utf8
         to  the  configure  command.  Of  itself, this does not make PCRE treat
         strings as UTF-8. As well as compiling PCRE with this option, you  also
         have  have to set the PCRE_UTF8 option when you call the pcre_compile()
-        function.
+        or pcre_compile2() functions.
+        If you set --enable-utf8 when compiling in an EBCDIC environment,  PCRE
+        expects its input to be either ASCII or UTF-8 (depending on the runtime
+        option). It is not possible to support both EBCDIC and UTF-8  codes  in
+        the  same  version  of  the  library.  Consequently,  --enable-utf8 and
+        --enable-ebcdic are mutually exclusive.
  UNICODE CHARACTER PROPERTY SUPPORT
-Line 272 
 UNICODE CHARACTER PROPERTY SUPPORT
+Line 346 
 UNICODE CHARACTER PROPERTY SUPPORT
         to the configure command. This implies UTF-8 support, even if you  have
         not explicitly requested it.
-        Including  Unicode  property  support  adds around 90K of tables to the
+        Including  Unicode  property  support  adds around 30K of tables to the
-        PCRE library, approximately doubling its size. Only the  general  cate-
+        PCRE library. Only the general category properties such as  Lu  and  Nd
-        gory  properties  such as Lu and Nd are supported. Details are given in
+        are supported. Details are given in the pcrepattern documentation.
-        the pcrepattern documentation.
  CODE VALUE OF NEWLINE
-        By default, PCRE treats character 10 (linefeed) as the newline  charac-
+        By  default,  PCRE interprets the linefeed (LF) character as indicating
-        ter. This is the normal newline character on Unix-like systems. You can
+        the end of a line. This is the normal newline  character  on  Unix-like
-        compile PCRE to use character 13 (carriage return) instead by adding
+        systems.  You  can compile PCRE to use carriage return (CR) instead, by
+        adding
           --enable-newline-is-cr
-        to the configure command. For completeness there is  also  a  --enable-
+        to the  configure  command.  There  is  also  a  --enable-newline-is-lf
-        newline-is-lf  option,  which explicitly specifies linefeed as the new-
+        option, which explicitly specifies linefeed as the newline character.
-        line character.
+        Alternatively, you can specify that line endings are to be indicated by
+        the two character sequence CRLF. If you want this, add
+          --enable-newline-is-crlf
+        to the configure command. There is a fourth option, specified by
+          --enable-newline-is-anycrlf
+        which causes PCRE to recognize any of the three sequences  CR,  LF,  or
+        CRLF as indicating a line ending. Finally, a fifth option, specified by
+          --enable-newline-is-any
+        causes PCRE to recognize any Unicode newline sequence.
+        Whatever  line  ending convention is selected when PCRE is built can be
+        overridden when the library functions are called. At build time  it  is
+        conventional to use the standard for your operating system.
+ WHAT \R MATCHES
+        By  default,  the  sequence \R in a pattern matches any Unicode newline
+        sequence, whatever has been selected as the line  ending  sequence.  If
+        you specify
+          --enable-bsr-anycrlf
+        the  default  is changed so that \R matches only CR, LF, or CRLF. What-
+        ever is selected when PCRE is built can be overridden when the  library
+        functions are called.
  BUILDING SHARED AND STATIC LIBRARIES
-        The PCRE building process uses libtool to build both shared and  static
+        The  PCRE building process uses libtool to build both shared and static
-        Unix  libraries by default. You can suppress one of these by adding one
+        Unix libraries by default. You can suppress one of these by adding  one
         of
           --disable-shared
-Line 306 
 BUILDING SHARED AND STATIC LIBRARIES
+Line 412 
 BUILDING SHARED AND STATIC LIBRARIES
  POSIX MALLOC USAGE
         When PCRE is called through the POSIX interface (see the pcreposix doc-
-        umentation),  additional  working  storage  is required for holding the
+        umentation), additional working storage is  required  for  holding  the
-        pointers to capturing substrings, because PCRE requires three  integers
+        pointers  to capturing substrings, because PCRE requires three integers
-        per  substring,  whereas  the POSIX interface provides only two. If the
+        per substring, whereas the POSIX interface provides only  two.  If  the
         number of expected substrings is small, the wrapper function uses space
         on the stack, because this is faster than using malloc() for each call.
         The default threshold above which the stack is no longer used is 10; it
-Line 319 
 POSIX MALLOC USAGE
+Line 425 
 POSIX MALLOC USAGE
         to the configure command.
+ HANDLING VERY LARGE PATTERNS
+        Within a compiled pattern, offset values are used  to  point  from  one
+        part  to another (for example, from an opening parenthesis to an alter-
+        nation metacharacter). By default, two-byte values are used  for  these
+        offsets,  leading  to  a  maximum size for a compiled pattern of around
+K. This is sufficient to handle all but the most  gigantic  patterns.
+        Nevertheless,  some  people do want to process truyl enormous patterns,
+        so it is possible to compile PCRE to use three-byte or  four-byte  off-
+        sets by adding a setting such as
+          --with-link-size=3
+        to  the  configure  command.  The value given must be 2, 3, or 4. Using
+        longer offsets slows down the operation of PCRE because it has to  load
+        additional bytes when handling them.
+ AVOIDING EXCESSIVE STACK USAGE
+        When matching with the pcre_exec() function, PCRE implements backtrack-
+        ing by making recursive calls to an internal function  called  match().
+        In  environments  where  the size of the stack is limited, this can se-
+        verely limit PCRE's operation. (The Unix environment does  not  usually
+        suffer from this problem, but it may sometimes be necessary to increase
+        the maximum stack size.  There is a discussion in the  pcrestack  docu-
+        mentation.)  An alternative approach to recursion that uses memory from
+        the heap to remember data, instead of using recursive  function  calls,
+        has  been  implemented to work round the problem of limited stack size.
+        If you want to build a version of PCRE that works this way, add
+          --disable-stack-for-recursion
+        to the configure command. With this configuration, PCRE  will  use  the
+        pcre_stack_malloc  and pcre_stack_free variables to call memory manage-
+        ment functions. By default these point to malloc() and free(), but  you
+        can replace the pointers so that your own functions are used instead.
+        Separate  functions  are  provided  rather  than  using pcre_malloc and
+        pcre_free because the  usage  is  very  predictable:  the  block  sizes
+        requested  are  always  the  same,  and  the blocks are always freed in
+        reverse order. A calling program might be able to  implement  optimized
+        functions  that  perform  better  than  malloc()  and free(). PCRE runs
+        noticeably more slowly when built in this way. This option affects only
+        the pcre_exec() function; it is not relevant for pcre_dfa_exec().
  LIMITING PCRE RESOURCE USAGE
         Internally,  PCRE has a function called match(), which it calls repeat-
-        edly  (possibly  recursively)  when  matching  a   pattern   with   the
+        edly  (sometimes  recursively)  when  matching  a  pattern   with   the
         pcre_exec()  function.  By controlling the maximum number of times this
         function may be called during a single matching operation, a limit  can
         be  placed  on  the resources used by a single call to pcre_exec(). The
-Line 335 
 LIMITING PCRE RESOURCE USAGE
+Line 488 
 LIMITING PCRE RESOURCE USAGE
         to  the  configure  command.  This  setting  has  no  effect   on   the
         pcre_dfa_exec() matching function.
+        In  some  environments  it is desirable to limit the depth of recursive
+        calls of match() more strictly than the total number of calls, in order
+        to  restrict  the maximum amount of stack (or heap, if --disable-stack-
+        for-recursion is specified) that is used. A second limit controls this;
+        it  defaults  to  the  value  that is set for --with-match-limit, which
+        imposes no additional constraints. However, you can set a  lower  limit
+        by adding, for example,
+          --with-match-limit-recursion=10000
+        to  the  configure  command.  This  value can also be overridden at run
+        time.
+ CREATING CHARACTER TABLES AT BUILD TIME
+        PCRE uses fixed tables for processing characters whose code values  are
+        less  than 256. By default, PCRE is built with a set of tables that are
+        distributed in the file pcre_chartables.c.dist. These  tables  are  for
+        ASCII codes only. If you add
+          --enable-rebuild-chartables
+        to  the  configure  command, the distributed tables are no longer used.
+        Instead, a program called dftables is compiled and  run.  This  outputs
+        the source for new set of tables, created in the default locale of your
+        C runtime system. (This method of replacing the tables does not work if
+        you  are cross compiling, because dftables is run on the local host. If
+        you need to create alternative tables when cross  compiling,  you  will
+        have to do so "by hand".)
- HANDLING VERY LARGE PATTERNS
-        Within  a  compiled  pattern,  offset values are used to point from one
+ USING EBCDIC CODE
-        part to another (for example, from an opening parenthesis to an  alter-
-        nation  metacharacter).  By default, two-byte values are used for these
-        offsets, leading to a maximum size for a  compiled  pattern  of  around
-K.  This  is sufficient to handle all but the most gigantic patterns.
-        Nevertheless, some people do want to process enormous patterns,  so  it
-        is  possible  to compile PCRE to use three-byte or four-byte offsets by
-        adding a setting such as
-          --with-link-size=3
+        PCRE  assumes  by  default that it will run in an environment where the
+        character code is ASCII (or Unicode, which is  a  superset  of  ASCII).
+        This  is  the  case for most computer operating systems. PCRE can, how-
+        ever, be compiled to run in an EBCDIC environment by adding
-        to the configure command. The value given must be 2,  3,  or  4.  Using
+          --enable-ebcdic
-        longer  offsets slows down the operation of PCRE because it has to load
-        additional bytes when handling them.
-        If you build PCRE with an increased link size, test 2 (and  test  5  if
+        to the configure command. This setting implies --enable-rebuild-charta-
-        you  are using UTF-8) will fail. Part of the output of these tests is a
+        bles.  You  should  only  use  it if you know that you are in an EBCDIC
-        representation of the compiled pattern, and this changes with the  link
+        environment (for example,  an  IBM  mainframe  operating  system).  The
-        size.
+        --enable-ebcdic option is incompatible with --enable-utf8.
- AVOIDING EXCESSIVE STACK USAGE
+ PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT
-        When matching with the pcre_exec() function, PCRE implements backtrack-
+        By default, pcregrep reads all files as plain text. You can build it so
-        ing by making recursive calls to an internal function  called  match().
+        that it recognizes files whose names end in .gz or .bz2, and reads them
-        In  environments  where  the size of the stack is limited, this can se-
+        with libz or libbz2, respectively, by adding one or both of
-        verely limit PCRE's operation. (The Unix environment does  not  usually
-        suffer  from  this  problem.)  An alternative approach that uses memory
-        from the heap to remember data, instead  of  using  recursive  function
-        calls,  has been implemented to work round this problem. If you want to
-        build a version of PCRE that works this way, add
-          --disable-stack-for-recursion
+          --enable-pcregrep-libz
+          --enable-pcregrep-libbz2
-        to the configure command. With this configuration, PCRE  will  use  the
+        to the configure command. These options naturally require that the rel-
-        pcre_stack_malloc  and pcre_stack_free variables to call memory manage-
+        evant libraries are installed on your system. Configuration  will  fail
-        ment functions. Separate functions are provided because  the  usage  is
+        if they are not.
-        very  predictable:  the  block sizes requested are always the same, and
-        the blocks are always freed in reverse order. A calling  program  might
-        be  able  to implement optimized functions that perform better than the
-        standard malloc() and  free()  functions.  PCRE  runs  noticeably  more
-        slowly when built in this way. This option affects only the pcre_exec()
-        function; it is not relevant for the the pcre_dfa_exec() function.
- USING EBCDIC CODE
+ PCRETEST OPTION FOR LIBREADLINE SUPPORT
-        PCRE assumes by default that it will run in an  environment  where  the
+        If you add
-        character  code  is  ASCII  (or Unicode, which is a superset of ASCII).
-        PCRE can, however, be compiled to  run  in  an  EBCDIC  environment  by
-        adding
-          --enable-ebcdic
+          --enable-pcretest-libreadline
+        to  the  configure  command,  pcretest  is  linked with the libreadline
+        library, and when its input is from a terminal, it reads it  using  the
+        readline() function. This provides line-editing and history facilities.
+        Note that libreadline is GPL-licensed, so if you distribute a binary of
+        pcretest linked in this way, there may be licensing issues.
+        Setting  this  option  causes  the -lreadline option to be added to the
+        pcretest build. In many operating environments with  a  sytem-installed
+        libreadline this is sufficient. However, in some environments (e.g.  if
+        an unmodified distribution version of readline is in use),  some  extra
+        configuration  may  be necessary. The INSTALL file for libreadline says
+        this:
+          "Readline uses the termcap functions, but does not link with the
+          termcap or curses library itself, allowing applications which link
+          with readline the to choose an appropriate library."
+        If your environment has not been set up so that an appropriate  library
+        is automatically included, you may need to add something like
+          LIBS="-ncurses"
+        immediately before the configure command.
+ SEE ALSO
+        pcreapi(3), pcre_config(3).
+ AUTHOR
+        Philip Hazel
+        University Computing Service
+        Cambridge CB2 3QH, England.
-        to the configure command.
- Last updated: 15 August 2005
+ REVISION
- Copyright (c) 1997-2005 University of Cambridge.
+        Last updated: 29 September 2009
+        Copyright (c) 1997-2009 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 431 
 PCRE MATCHING ALGORITHMS
+Line 631 
 PCRE MATCHING ALGORITHMS
           <something> <something else> <something further>
         there are three possible answers. The standard algorithm finds only one
-        of them, whereas the DFA algorithm finds all three.
+        of them, whereas the alternative algorithm finds all three.
  REGULAR EXPRESSIONS AS TREES
-Line 440 
 REGULAR EXPRESSIONS AS TREES
+Line 640 
 REGULAR EXPRESSIONS AS TREES
         resented  as  a  tree structure. An unlimited repetition in the pattern
         makes the tree of infinite size, but it is still a tree.  Matching  the
         pattern  to a given subject string (from a given starting point) can be
-        thought of as a search of the tree.  There are  two  standard  ways  to
+        thought of as a search of the tree.  There are two  ways  to  search  a
-        search  a  tree: depth-first and breadth-first, and these correspond to
+        tree:  depth-first  and  breadth-first, and these correspond to the two
-        the two matching algorithms provided by PCRE.
+        matching algorithms provided by PCRE.
  THE STANDARD MATCHING ALGORITHM
-        In the terminology of Jeffrey Friedl's book Mastering  Regular  Expres-
+        In the terminology of Jeffrey Friedl's book "Mastering Regular  Expres-
-        sions,  the  standard  algorithm  is  an "NFA algorithm". It conducts a
+        sions",  the  standard  algorithm  is an "NFA algorithm". It conducts a
         depth-first search of the pattern tree. That is, it  proceeds  along  a
         single path through the tree, checking that the subject matches what is
         required. When there is a mismatch, the algorithm  tries  any  alterna-
-Line 472 
 THE STANDARD MATCHING ALGORITHM
+Line 672 
 THE STANDARD MATCHING ALGORITHM
         This provides support for capturing parentheses and back references.
- THE DFA MATCHING ALGORITHM
+ THE ALTERNATIVE MATCHING ALGORITHM
-        DFA stands for "deterministic finite automaton", but you do not need to
+        This algorithm conducts a breadth-first search of  the  tree.  Starting
-        understand the origins of that name. This algorithm conducts a breadth-
+        from  the  first  matching  point  in the subject, it scans the subject
-        first search of the tree. Starting from the first matching point in the
+        string from left to right, once, character by character, and as it does
-        subject,  it scans the subject string from left to right, once, charac-
+        this,  it remembers all the paths through the tree that represent valid
-        ter by character, and as it does  this,  it  remembers  all  the  paths
+        matches. In Friedl's terminology, this is a kind  of  "DFA  algorithm",
-        through the tree that represent valid matches.
+        though  it is not implemented as a traditional finite state machine (it
+        keeps multiple states active simultaneously).
-        The  scan  continues until either the end of the subject is reached, or
-        there are no more unterminated paths. At this point,  terminated  paths
+        Although the general principle of this matching algorithm  is  that  it
-        represent  the different matching possibilities (if there are none, the
+        scans  the subject string only once, without backtracking, there is one
-        match has failed).  Thus, if there is more  than  one  possible  match,
+        exception: when a lookaround assertion is encountered,  the  characters
+        following  or  preceding  the  current  point  have to be independently
+        inspected.
+        The scan continues until either the end of the subject is  reached,  or
+        there  are  no more unterminated paths. At this point, terminated paths
+        represent the different matching possibilities (if there are none,  the
+        match  has  failed).   Thus,  if there is more than one possible match,
         this algorithm finds all of them, and in particular, it finds the long-
-        est. In PCRE, there is an option to stop the algorithm after the  first
+        est.  There  is  an  option to stop the algorithm after the first match
-        match (which is necessarily the shortest) has been found.
+        (which is necessarily the shortest) is found.
         Note that all the matches that are found start at the same point in the
         subject. If the pattern
           cat(er(pillar)?)
-        is matched against the string "the caterpillar catchment",  the  result
+        is  matched  against the string "the caterpillar catchment", the result
-        will  be the three strings "cat", "cater", and "caterpillar" that start
+        will be the three strings "cat", "cater", and "caterpillar" that  start
         at the fourth character of the subject. The algorithm does not automat-
         ically move on to find matches that start at later positions.
         There are a number of features of PCRE regular expressions that are not
-        supported by the DFA matching algorithm. They are as follows:
+        supported by the alternative matching algorithm. They are as follows:
-. Because the algorithm finds all  possible  matches,  the  greedy  or
+.  Because  the  algorithm  finds  all possible matches, the greedy or
-        ungreedy  nature  of repetition quantifiers is not relevant. Greedy and
+        ungreedy nature of repetition quantifiers is not relevant.  Greedy  and
-        ungreedy quantifiers are treated in exactly the same way.
+        ungreedy quantifiers are treated in exactly the same way. However, pos-
+        sessive quantifiers can make a difference when what follows could  also
+        match what is quantified, for example in a pattern like this:
+          ^a++\w!
+        This  pattern matches "aaab!" but not "aaa!", which would be matched by
+        a non-possessive quantifier. Similarly, if an atomic group is  present,
+        it  is matched as if it were a standalone pattern at the current point,
+        and the longest match is then "locked in" for the rest of  the  overall
+        pattern.
 . When dealing with multiple paths through the tree simultaneously, it
-        is  not  straightforward  to  keep track of captured substrings for the
+        is not straightforward to keep track of  captured  substrings  for  the
-        different matching possibilities, and  PCRE's  implementation  of  this
+        different  matching  possibilities,  and  PCRE's implementation of this
         algorithm does not attempt to do this. This means that no captured sub-
         strings are available.
-. Because no substrings are captured, back references within the  pat-
+.  Because no substrings are captured, back references within the pat-
         tern are not supported, and cause errors if encountered.
-.  For  the same reason, conditional expressions that use a backrefer-
+. For the same reason, conditional expressions that use  a  backrefer-
-        ence as the condition are not supported.
+        ence  as  the  condition or test for a specific group recursion are not
+        supported.
+. Because many paths through the tree may be  active,  the  \K  escape
+        sequence, which resets the start of the match when encountered (but may
+        be on some paths and not on others), is not  supported.  It  causes  an
+        error if encountered.
-. Callouts are supported, but the value of the  capture_top  field  is
+.  Callouts  are  supported, but the value of the capture_top field is
         always 1, and the value of the capture_last field is always -1.
-.  The \C escape sequence, which (in the standard algorithm) matches a
+. The \C escape sequence, which (in the standard algorithm) matches  a
-        single byte, even in UTF-8 mode, is not supported because the DFA algo-
+        single  byte, even in UTF-8 mode, is not supported because the alterna-
-        rithm moves through the subject string one character at a time, for all
+        tive algorithm moves through the subject  string  one  character  at  a
-        active paths through the tree.
+        time, for all active paths through the tree.
+.  Except for (*FAIL), the backtracking control verbs such as (*PRUNE)
+        are not supported. (*FAIL) is supported, and  behaves  like  a  failing
+        negative assertion.
- ADVANTAGES OF THE DFA ALGORITHM
-        Using the DFA matching algorithm provides the following advantages:
+ ADVANTAGES OF THE ALTERNATIVE ALGORITHM
+        Using  the alternative matching algorithm provides the following advan-
+        tages:
 . All possible matches (at a single point in the subject) are automat-
         ically  found,  and  in particular, the longest match is found. To find
         more than one match using the standard algorithm, you have to do kludgy
         things with callouts.
-.  There is much better support for partial matching. The restrictions
+.  Because  the  alternative  algorithm  scans the subject string just
-        on the content of the pattern that apply when using the standard  algo-
+        once, and never needs to backtrack, it is possible to  pass  very  long
-        rithm  for partial matching do not apply to the DFA algorithm. For non-
+        subject  strings  to  the matching function in several pieces, checking
-        anchored patterns, the starting position of a partial match  is  avail-
+        for partial matching each time.  The  pcrepartial  documentation  gives
-        able.
+        details of partial matching.
-.  Because  the  DFA algorithm scans the subject string just once, and
-        never needs to backtrack, it is possible  to  pass  very  long  subject
-        strings  to  the matching function in several pieces, checking for par-
-        tial matching each time.
- DISADVANTAGES OF THE DFA ALGORITHM
+ DISADVANTAGES OF THE ALTERNATIVE ALGORITHM
-        The DFA algorithm suffers from a number of disadvantages:
+        The alternative algorithm suffers from a number of disadvantages:
-. It is substantially slower than  the  standard  algorithm.  This  is
+.  It  is  substantially  slower  than the standard algorithm. This is
-        partly  because  it has to search for all possible matches, but is also
+        partly because it has to search for all possible matches, but  is  also
         because it is less susceptible to optimization.
 . Capturing parentheses and back references are not supported.
-. The "atomic group" feature of PCRE regular expressions is supported,
+. Although atomic groups are supported, their use does not provide the
-        but  does not provide the advantage that it does for the standard algo-
+        performance advantage that it does for the standard algorithm.
-        rithm.
+ AUTHOR
+        Philip Hazel
+        University Computing Service
+        Cambridge CB2 3QH, England.
- Last updated: 28 February 2005
+ REVISION
- Copyright (c) 1997-2005 University of Cambridge.
+        Last updated: 29 September 2009
+        Copyright (c) 1997-2009 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 616 
 PCRE NATIVE API
+Line 848 
 PCRE NATIVE API
         int pcre_get_stringnumber(const pcre *code,
              const char *name);
+        int pcre_get_stringtable_entries(const pcre *code,
+             const char *name, char **first, char **last);
         int pcre_get_substring(const char *subject, int *ovector,
              int stringcount, int stringnumber,
              const char **stringptr);
-Line 654 
 PCRE NATIVE API
+Line 889 
 PCRE NATIVE API
  PCRE API OVERVIEW
         PCRE has its own native API, which is described in this document. There
-        is also a set of wrapper functions that correspond to the POSIX regular
+        are also some wrapper functions that correspond to  the  POSIX  regular
         expression  API.  These  are  described in the pcreposix documentation.
         Both of these APIs define a set of C function calls. A C++  wrapper  is
         distributed with PCRE. It is documented in the pcrecpp page.
-Line 671 
 PCRE API OVERVIEW
+Line 906 
 PCRE API OVERVIEW
         pcre_exec() are used for compiling and matching regular expressions  in
         a  Perl-compatible  manner. A sample program that demonstrates the sim-
         plest way of using them is provided in the file  called  pcredemo.c  in
-        the  source distribution. The pcresample documentation describes how to
+        the PCRE source distribution. A listing of this program is given in the
-        run it.
+        pcredemo documentation, and the pcresample documentation describes  how
+        to compile and run it.
         A second matching function, pcre_dfa_exec(), which is not Perl-compati-
-        ble,  is  also provided. This uses a different algorithm for the match-
+        ble, is also provided. This uses a different algorithm for  the  match-
-        ing. This allows it to find all possible matches (at a given  point  in
+        ing.  The  alternative algorithm finds all possible matches (at a given
-        the  subject),  not  just  one. However, this algorithm does not return
+        point in the subject), and scans the subject just  once  (unless  there
+        are  lookbehind  assertions).  However,  this algorithm does not return
         captured substrings. A description of the two matching  algorithms  and
         their  advantages  and disadvantages is given in the pcrematching docu-
         mentation.
-Line 692 
 PCRE API OVERVIEW
+Line 929 
 PCRE API OVERVIEW
           pcre_get_named_substring()
           pcre_get_substring_list()
           pcre_get_stringnumber()
+          pcre_get_stringtable_entries()
         pcre_free_substring() and pcre_free_substring_list() are also provided,
         to free the memory used for extracted strings.
-Line 723 
 PCRE API OVERVIEW
+Line 961 
 PCRE API OVERVIEW
         indirections  to  memory  management functions. These special functions
         are used only when PCRE is compiled to use  the  heap  for  remembering
         data, instead of recursive function calls, when running the pcre_exec()
-        function. This is a non-standard way of building PCRE, for use in envi-
+        function. See the pcrebuild documentation for  details  of  how  to  do
-        ronments that have limited stacks. Because of the greater use of memory
+        this.  It  is  a non-standard way of building PCRE, for use in environ-
-        management, it runs more slowly.  Separate functions  are  provided  so
+        ments that have limited stacks. Because of the greater  use  of  memory
-        that  special-purpose  external  code  can  be used for this case. When
+        management,  it  runs  more  slowly. Separate functions are provided so
-        used, these functions are always called in a  stack-like  manner  (last
+        that special-purpose external code can be  used  for  this  case.  When
-        obtained,  first freed), and always for memory blocks of the same size.
+        used,  these  functions  are always called in a stack-like manner (last
+        obtained, first freed), and always for memory blocks of the same  size.
+        There  is  a discussion about PCRE's stack usage in the pcrestack docu-
+        mentation.
         The global variable pcre_callout initially contains NULL. It can be set
         by  the  caller  to  a "callout" function, which PCRE will then call at
-Line 736 
 PCRE API OVERVIEW
+Line 977 
 PCRE API OVERVIEW
         pcrecallout documentation.
+ NEWLINES
+        PCRE  supports five different conventions for indicating line breaks in
+        strings: a single CR (carriage return) character, a  single  LF  (line-
+        feed) character, the two-character sequence CRLF, any of the three pre-
+        ceding, or any Unicode newline sequence. The Unicode newline  sequences
+        are  the  three just mentioned, plus the single characters VT (vertical
+        tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS  (line
+        separator, U+2028), and PS (paragraph separator, U+2029).
+        Each  of  the first three conventions is used by at least one operating
+        system as its standard newline sequence. When PCRE is built, a  default
+        can  be  specified.  The default default is LF, which is the Unix stan-
+        dard. When PCRE is run, the default can be overridden,  either  when  a
+        pattern is compiled, or when it is matched.
+        At compile time, the newline convention can be specified by the options
+        argument of pcre_compile(), or it can be specified by special  text  at
+        the start of the pattern itself; this overrides any other settings. See
+        the pcrepattern page for details of the special character sequences.
+        In the PCRE documentation the word "newline" is used to mean "the char-
+        acter  or pair of characters that indicate a line break". The choice of
+        newline convention affects the handling of  the  dot,  circumflex,  and
+        dollar metacharacters, the handling of #-comments in /x mode, and, when
+        CRLF is a recognized line ending sequence, the match position  advance-
+        ment for a non-anchored pattern. There is more detail about this in the
+        section on pcre_exec() options below.
+        The choice of newline convention does not affect the interpretation  of
+        the  \n  or  \r  escape  sequences, nor does it affect what \R matches,
+        which is controlled in a similar way, but by separate options.
  MULTITHREADING
-        The  PCRE  functions  can be used in multi-threading applications, with
+        The PCRE functions can be used in  multi-threading  applications,  with
         the  proviso  that  the  memory  management  functions  pointed  to  by
         pcre_malloc, pcre_free, pcre_stack_malloc, and pcre_stack_free, and the
         callout function pointed to by pcre_callout, are shared by all threads.
-Line 753 
 SAVING PRECOMPILED PATTERNS FOR LATER US
+Line 1028 
 SAVING PRECOMPILED PATTERNS FOR LATER US
         The compiled form of a regular expression can be saved and re-used at a
         later time, possibly by a different program, and even on a  host  other
         than  the  one  on  which  it  was  compiled.  Details are given in the
-        pcreprecompile documentation.
+        pcreprecompile documentation. However, compiling a  regular  expression
+        with  one version of PCRE for use with a different version is not guar-
+        anteed to work and may cause crashes.
  CHECKING BUILD-TIME OPTIONS
-Line 782 
 CHECKING BUILD-TIME OPTIONS
+Line 1059 
 CHECKING BUILD-TIME OPTIONS
           PCRE_CONFIG_NEWLINE
-        The output is an integer that is set to the value of the code  that  is
+        The output is an integer whose value specifies  the  default  character
-        used  for the newline character. It is either linefeed (10) or carriage
+        sequence  that is recognized as meaning "newline". The four values that
-        return (13), and should normally be the  standard  character  for  your
+        are supported are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF,
-        operating system.
+        and  -1  for  ANY.  Though they are derived from ASCII, the same values
+        are returned in EBCDIC environments. The default should normally corre-
+        spond to the standard sequence for your operating system.
+          PCRE_CONFIG_BSR
+        The output is an integer whose value indicates what character sequences
+        the \R escape sequence matches by default. A value of 0 means  that  \R
+        matches  any  Unicode  line ending sequence; a value of 1 means that \R
+        matches only CR, LF, or CRLF. The default can be overridden when a pat-
+        tern is compiled or matched.
           PCRE_CONFIG_LINK_SIZE
-Line 804 
 CHECKING BUILD-TIME OPTIONS
+Line 1091 
 CHECKING BUILD-TIME OPTIONS
           PCRE_CONFIG_MATCH_LIMIT
-        The output is an integer that gives the default limit for the number of
+        The output is a long integer that gives the default limit for the  num-
-        internal  matching  function  calls in a pcre_exec() execution. Further
+        ber  of  internal  matching  function calls in a pcre_exec() execution.
-        details are given with pcre_exec() below.
+        Further details are given with pcre_exec() below.
+          PCRE_CONFIG_MATCH_LIMIT_RECURSION
+        The output is a long integer that gives the default limit for the depth
+        of   recursion  when  calling  the  internal  matching  function  in  a
+        pcre_exec() execution.  Further  details  are  given  with  pcre_exec()
+        below.
           PCRE_CONFIG_STACKRECURSE
-        The output is an integer that is set to one if internal recursion  when
+        The  output is an integer that is set to one if internal recursion when
         running pcre_exec() is implemented by recursive function calls that use
-        the stack to remember their state. This is the usual way that  PCRE  is
+        the  stack  to remember their state. This is the usual way that PCRE is
         compiled. The output is zero if PCRE was compiled to use blocks of data
-        on the  heap  instead  of  recursive  function  calls.  In  this  case,
+        on  the  heap  instead  of  recursive  function  calls.  In  this case,
-        pcre_stack_malloc  and  pcre_stack_free  are  called  to  manage memory
+        pcre_stack_malloc and  pcre_stack_free  are  called  to  manage  memory
         blocks on the heap, thus avoiding the use of the stack.
-Line 832 
 COMPILING A PATTERN
+Line 1126 
 COMPILING A PATTERN
         Either of the functions pcre_compile() or pcre_compile2() can be called
         to compile a pattern into an internal form. The only difference between
-        the two interfaces is that pcre_compile2() has an additional  argument,
+        the  two interfaces is that pcre_compile2() has an additional argument,
-        errorcodeptr, via which a numerical error code can be returned.
+        errorcodeptr, via which a numerical error  code  can  be  returned.  To
+        avoid  too  much repetition, we refer just to pcre_compile() below, but
+        the information applies equally to pcre_compile2().
         The pattern is a C string terminated by a binary zero, and is passed in
-        the pattern argument. A pointer to a single block  of  memory  that  is
+        the  pattern  argument.  A  pointer to a single block of memory that is
-        obtained  via  pcre_malloc is returned. This contains the compiled code
+        obtained via pcre_malloc is returned. This contains the  compiled  code
         and related data. The pcre type is defined for the returned block; this
         is a typedef for a structure whose contents are not externally defined.
-        It is up to the caller  to  free  the  memory  when  it  is  no  longer
+        It is up to the caller to free the memory (via pcre_free) when it is no
-        required.
+        longer required.
-        Although  the compiled code of a PCRE regex is relocatable, that is, it
+        Although the compiled code of a PCRE regex is relocatable, that is,  it
         does not depend on memory location, the complete pcre data block is not
-        fully  relocatable, because it may contain a copy of the tableptr argu-
+        fully relocatable, because it may contain a copy of the tableptr  argu-
         ment, which is an address (see below).
-        The options argument contains independent bits that affect the compila-
+        The options argument contains various bit settings that affect the com-
-        tion.  It  should  be  zero  if  no options are required. The available
+        pilation. It should be zero if no options are required.  The  available
-        options are described below. Some of them, in  particular,  those  that
+        options  are  described  below. Some of them (in particular, those that
-        are  compatible  with  Perl,  can also be set and unset from within the
+        are compatible with Perl, but some others as well) can also be set  and
-        pattern (see the detailed description  in  the  pcrepattern  documenta-
+        unset  from  within  the  pattern  (see the detailed description in the
-        tion).  For  these options, the contents of the options argument speci-
+        pcrepattern documentation). For those options that can be different  in
-        fies their initial settings at the start of compilation and  execution.
+        different  parts  of  the pattern, the contents of the options argument
-        The  PCRE_ANCHORED option can be set at the time of matching as well as
+        specifies their settings at the start of compilation and execution. The
-        at compile time.
+        PCRE_ANCHORED, PCRE_BSR_xxx, and PCRE_NEWLINE_xxx options can be set at
+        the time of matching as well as at compile time.
         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,
         if  compilation  of  a  pattern fails, pcre_compile() returns NULL, and
         sets the variable pointed to by errptr to point to a textual error mes-
-        sage.  The  offset from the start of the pattern to the character where
+        sage. This is a static string that is part of the library. You must not
-        the error was discovered is  placed  in  the  variable  pointed  to  by
+        try to free it. The byte offset from the start of the  pattern  to  the
-        erroffset,  which  must  not  be  NULL. If it is, an immediate error is
+        character  that  was  being  processed when the error was discovered is
-        given.
+        placed in the variable pointed to by erroffset, which must not be NULL.
+        If  it  is,  an  immediate error is given. Some errors are not detected
-        If pcre_compile2() is used instead of pcre_compile(),  and  the  error-
+        until checks are carried out when the whole pattern has  been  scanned;
-        codeptr  argument is not NULL, a non-zero error code number is returned
+        in this case the offset is set to the end of the pattern.
-        via this argument in the event of an error. This is in addition to  the
+        If  pcre_compile2()  is  used instead of pcre_compile(), and the error-
+        codeptr argument is not NULL, a non-zero error code number is  returned
+        via  this argument in the event of an error. This is in addition to the
         textual error message. Error codes and messages are listed below.
-        If  the  final  argument, tableptr, is NULL, PCRE uses a default set of
+        If the final argument, tableptr, is NULL, PCRE uses a  default  set  of
-        character tables that are  built  when  PCRE  is  compiled,  using  the
+        character  tables  that  are  built  when  PCRE  is compiled, using the
-        default  C  locale.  Otherwise, tableptr must be an address that is the
+        default C locale. Otherwise, tableptr must be an address  that  is  the
-        result of a call to pcre_maketables(). This value is  stored  with  the
+        result  of  a  call to pcre_maketables(). This value is stored with the
-        compiled  pattern,  and used again by pcre_exec(), unless another table
+        compiled pattern, and used again by pcre_exec(), unless  another  table
         pointer is passed to it. For more discussion, see the section on locale
         support below.
-        This  code  fragment  shows a typical straightforward call to pcre_com-
+        This code fragment shows a typical straightforward  call  to  pcre_com-
         pile():
           pcre *re;
-Line 892 
 COMPILING A PATTERN
+Line 1192 
 COMPILING A PATTERN
             &erroffset,       /* for error offset */
             NULL);            /* use default character tables */
-        The following names for option bits are defined in  the  pcre.h  header
+        The  following  names  for option bits are defined in the pcre.h 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 first matching point in the  string
+        is  constrained to match only at the first matching point in the string
-        that  is being searched (the "subject string"). This effect can also be
+        that is being searched (the "subject string"). This effect can also  be
-        achieved by appropriate constructs in the pattern itself, which is  the
+        achieved  by appropriate constructs in the pattern itself, which is the
         only way to do it in Perl.
           PCRE_AUTO_CALLOUT
         If this bit is set, pcre_compile() automatically inserts callout items,
-        all with number 255, before each pattern item. For  discussion  of  the
+        all  with  number  255, before each pattern item. For discussion of the
         callout facility, see the pcrecallout documentation.
+          PCRE_BSR_ANYCRLF
+          PCRE_BSR_UNICODE
+        These options (which are mutually exclusive) control what the \R escape
+        sequence  matches.  The choice is either to match only CR, LF, or CRLF,
+        or to match any Unicode newline sequence. The default is specified when
+        PCRE is built. It can be overridden from within the pattern, or by set-
+        ting an option when a compiled pattern is matched.
           PCRE_CASELESS
-        If  this  bit is set, letters in the pattern match both upper and lower
+        If this bit is set, letters in the pattern match both upper  and  lower
-        case letters. It is equivalent to Perl's  /i  option,  and  it  can  be
+        case  letters.  It  is  equivalent  to  Perl's /i option, and it can be
-        changed  within a pattern by a (?i) option setting. In UTF-8 mode, PCRE
+        changed within a pattern by a (?i) option setting. In UTF-8 mode,  PCRE
-        always understands the concept of case for characters whose values  are
+        always  understands the concept of case for characters whose values are
-        less  than 128, so caseless matching is always possible. For characters
+        less than 128, so caseless matching is always possible. For  characters
-        with higher values, the concept of case is supported if  PCRE  is  com-
+        with  higher  values,  the concept of case is supported if PCRE is com-
-        piled  with Unicode property support, but not otherwise. If you want to
+        piled with Unicode property support, but not otherwise. If you want  to
-        use caseless matching for characters 128 and  above,  you  must  ensure
+        use  caseless  matching  for  characters 128 and above, you must ensure
-        that  PCRE  is  compiled  with Unicode property support as well as with
+        that PCRE is compiled with Unicode property support  as  well  as  with
         UTF-8 support.
           PCRE_DOLLAR_ENDONLY
-        If this bit is set, a dollar metacharacter in the pattern matches  only
+        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
+        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
+        matches  immediately before a newline at the end of the string (but not
-        not  before  any  other  newlines).  The  PCRE_DOLLAR_ENDONLY option is
+        before any other newlines). The PCRE_DOLLAR_ENDONLY option  is  ignored
-        ignored if PCRE_MULTILINE is set. There is no equivalent to this option
+        if  PCRE_MULTILINE  is  set.   There is no equivalent to this option in
-        in Perl, and no way to set it within a pattern.
+        Perl, and no way to set it within a pattern.
           PCRE_DOTALL
         If this bit is set, a dot metacharater in the pattern matches all char-
-        acters, including newlines. Without it,  newlines  are  excluded.  This
+        acters,  including  those that indicate newline. Without it, a dot does
-        option  is equivalent to Perl's /s option, and it can be changed within
+        not match when the current position is at a  newline.  This  option  is
-        a pattern by a (?s) option setting.  A  negative  class  such  as  [^a]
+        equivalent  to Perl's /s option, and it can be changed within a pattern
-        always  matches a newline character, independent of the setting of this
+        by a (?s) option setting. A negative class such as [^a] always  matches
-        option.
+        newline characters, independent of the setting of this option.
+          PCRE_DUPNAMES
+        If  this  bit is set, names used to identify capturing subpatterns need
+        not be unique. This can be helpful for certain types of pattern when it
+        is  known  that  only  one instance of the named subpattern can ever be
+        matched. There are more details of named subpatterns  below;  see  also
+        the pcrepattern documentation.
           PCRE_EXTENDED
-        If this bit is set, whitespace  data  characters  in  the  pattern  are
+        If  this  bit  is  set,  whitespace  data characters in the pattern are
         totally ignored except when escaped or inside a character class. White-
         space does not include the VT character (code 11). In addition, charac-
         ters between an unescaped # outside a character class and the next new-
-        line character, inclusive, are also  ignored.  This  is  equivalent  to
+        line,  inclusive,  are  also  ignored.  This is equivalent to Perl's /x
-        Perl's  /x  option,  and  it  can be changed within a pattern by a (?x)
+        option, and it can be changed within a pattern by a  (?x)  option  set-
-        option setting.
+        ting.
-        This option makes it possible to include  comments  inside  complicated
+        This  option  makes  it possible to include comments inside complicated
-        patterns.   Note,  however,  that this applies only to data characters.
+        patterns.  Note, however, that this applies only  to  data  characters.
-        Whitespace  characters  may  never  appear  within  special   character
+        Whitespace   characters  may  never  appear  within  special  character
-        sequences  in  a  pattern,  for  example  within the sequence (?( which
+        sequences in a pattern, for  example  within  the  sequence  (?(  which
         introduces a conditional subpattern.
           PCRE_EXTRA
-        This option was invented in order to turn on  additional  functionality
+        This  option  was invented in order to turn on additional functionality
-        of  PCRE  that  is  incompatible with Perl, but it is currently of very
+        of PCRE that is incompatible with Perl, but it  is  currently  of  very
-        little use. When set, any backslash in a pattern that is followed by  a
+        little  use. When set, any backslash in a pattern that is followed by a
-        letter  that  has  no  special  meaning causes an error, thus reserving
+        letter that has no special meaning  causes  an  error,  thus  reserving
-        these combinations for future expansion. By  default,  as  in  Perl,  a
+        these  combinations  for  future  expansion.  By default, as in Perl, a
-        backslash  followed by a letter with no special meaning is treated as 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
+        literal.  (Perl can, however, be persuaded to give a warning for this.)
-        option. It can also be set by a (?X) option setting within a pattern.
+        There are at present no other features controlled by  this  option.  It
+        can also be set by a (?X) option setting within a pattern.
           PCRE_FIRSTLINE
         If  this  option  is  set,  an  unanchored pattern is required to match
-        before or at the first newline character in the subject string,  though
+        before or at the first  newline  in  the  subject  string,  though  the
-        the matched text may continue over the newline.
+        matched text may continue over the newline.
+          PCRE_JAVASCRIPT_COMPAT
+        If this option is set, PCRE's behaviour is changed in some ways so that
+        it is compatible with JavaScript rather than Perl. The changes  are  as
+        follows:
+        (1)  A  lone  closing square bracket in a pattern causes a compile-time
+        error, because this is illegal in JavaScript (by default it is  treated
+        as a data character). Thus, the pattern AB]CD becomes illegal when this
+        option is set.
+        (2) At run time, a back reference to an unset subpattern group  matches
+        an  empty  string (by default this causes the current matching alterna-
+        tive to fail). A pattern such as (\1)(a) succeeds when this  option  is
+        set  (assuming  it can find an "a" in the subject), whereas it fails by
+        default, for Perl compatibility.
           PCRE_MULTILINE
-        By  default,  PCRE  treats the subject string as consisting of a single
+        By default, PCRE treats the subject string as consisting  of  a  single
-        line of characters (even if it actually contains newlines). The  "start
+        line  of characters (even if it actually contains newlines). The "start
-        of  line"  metacharacter  (^)  matches only at the start of the string,
+        of line" metacharacter (^) matches only at the  start  of  the  string,
-        while the "end of line" metacharacter ($) matches only at  the  end  of
+        while  the  "end  of line" metacharacter ($) 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"
+        When  PCRE_MULTILINE  it  is set, the "start of line" and "end of line"
-        constructs  match  immediately following or immediately before any new-
+        constructs match immediately following or immediately  before  internal
-        line in the subject string, respectively, as well as at the very  start
+        newlines  in  the  subject string, respectively, as well as at the very
-        and  end. This is equivalent to Perl's /m option, and it can be changed
+        start and end. This is equivalent to Perl's /m option, and  it  can  be
-        within a pattern by a (?m) option setting. If there are no "\n" charac-
+        changed within a pattern by a (?m) option setting. If there are no new-
-        ters  in  a  subject  string, or no occurrences of ^ or $ in a pattern,
+        lines in a subject string, or no occurrences of ^ or $  in  a  pattern,
         setting PCRE_MULTILINE has no effect.
+          PCRE_NEWLINE_CR
+          PCRE_NEWLINE_LF
+          PCRE_NEWLINE_CRLF
+          PCRE_NEWLINE_ANYCRLF
+          PCRE_NEWLINE_ANY
+        These  options  override the default newline definition that was chosen
+        when PCRE was built. Setting the first or the second specifies  that  a
+        newline  is  indicated  by a single character (CR or LF, respectively).
+        Setting PCRE_NEWLINE_CRLF specifies that a newline is indicated by  the
+        two-character  CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF specifies
+        that any of the three preceding sequences should be recognized. Setting
+        PCRE_NEWLINE_ANY  specifies that any Unicode newline sequence should be
+        recognized. The Unicode newline sequences are the three just mentioned,
+        plus  the  single  characters  VT (vertical tab, U+000B), FF (formfeed,
+        U+000C), NEL (next line, U+0085), LS (line separator, U+2028),  and  PS
+        (paragraph  separator,  U+2029).  The  last  two are recognized only in
+        UTF-8 mode.
+        The newline setting in the  options  word  uses  three  bits  that  are
+        treated as a number, giving eight possibilities. Currently only six are
+        used (default plus the five values above). This means that if  you  set
+        more  than one newline option, the combination may or may not be sensi-
+        ble. For example, PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to
+        PCRE_NEWLINE_CRLF,  but other combinations may yield unused numbers and
+        cause an error.
+        The only time that a line break is specially recognized when  compiling
+        a  pattern  is  if  PCRE_EXTENDED  is set, and an unescaped # outside a
+        character class is encountered. This indicates  a  comment  that  lasts
+        until  after the next line break sequence. In other circumstances, line
+        break  sequences  are  treated  as  literal  data,   except   that   in
+        PCRE_EXTENDED mode, both CR and LF are treated as whitespace characters
+        and are therefore ignored.
+        The newline option that is set at compile time becomes the default that
+        is used for pcre_exec() and pcre_dfa_exec(), but it can be overridden.
           PCRE_NO_AUTO_CAPTURE
         If this option is set, it disables the use of numbered capturing paren-
-        theses  in the pattern. Any opening parenthesis that is not followed by
+        theses in the pattern. Any opening parenthesis that is not followed  by
-        ? behaves as if it were followed by ?: but named parentheses can  still
+        ?  behaves as if it were followed by ?: but named parentheses can still
-        be  used  for  capturing  (and  they acquire numbers in the usual way).
+        be used for capturing (and they acquire  numbers  in  the  usual  way).
         There is no equivalent of this option in Perl.
           PCRE_UNGREEDY
-        This option inverts the "greediness" of the quantifiers  so  that  they
+        This  option  inverts  the "greediness" of the quantifiers so that they
-        are  not greedy by default, but become greedy if followed by "?". It is
+        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
+        not  compatible  with Perl. It can also be set by a (?U) option setting
         within the pattern.
           PCRE_UTF8
-        This  option  causes PCRE to regard both the pattern and the subject as
+        This option causes PCRE to regard both the pattern and the  subject  as
-        strings of UTF-8 characters instead of single-byte  character  strings.
+        strings  of  UTF-8 characters instead of single-byte character strings.
-        However,  it is available only when PCRE is built to include UTF-8 sup-
+        However, it is available only when PCRE is built to include UTF-8  sup-
-        port. If not, the use of this option provokes an error. Details of  how
+        port.  If not, the use of this option provokes an error. Details of how
-        this  option  changes the behaviour of PCRE are given in the section on
+        this option changes the behaviour of PCRE are given in the  section  on
         UTF-8 support in the main pcre page.
           PCRE_NO_UTF8_CHECK
         When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
-        automatically  checked. If an invalid UTF-8 sequence of bytes is found,
+        automatically checked. There is a  discussion  about  the  validity  of
-        pcre_compile() returns an error. If you already know that your  pattern
+        UTF-8  strings  in  the main pcre page. If an invalid UTF-8 sequence of
-        is  valid, and you want to skip this check for performance reasons, you
+        bytes is found, pcre_compile() returns an error. If  you  already  know
-        can set the PCRE_NO_UTF8_CHECK option. When it is set,  the  effect  of
+        that your pattern is valid, and you want to skip this check for perfor-
-        passing an invalid UTF-8 string as a pattern is undefined. It may cause
+        mance reasons, you can set the PCRE_NO_UTF8_CHECK option.  When  it  is
-        your program to crash.  Note that this option can  also  be  passed  to
+        set,  the  effect  of  passing  an invalid UTF-8 string as a pattern is
-        pcre_exec()  and pcre_dfa_exec(), to suppress the UTF-8 validity check-
+        undefined. It may cause your program to crash. Note  that  this  option
-        ing of subject strings.
+        can  also be passed to pcre_exec() and pcre_dfa_exec(), to suppress the
+        UTF-8 validity checking of subject strings.
  COMPILATION ERROR CODES
         The following table lists the error  codes  than  may  be  returned  by
         pcre_compile2(),  along with the error messages that may be returned by
-        both compiling functions.
+        both compiling functions. As PCRE has developed, some error codes  have
+        fallen out of use. To avoid confusion, they have not been re-used.
  no error
  \ at end of pattern
-Line 1043 
 COMPILATION ERROR CODES
+Line 1418 
 COMPILATION ERROR CODES
  invalid escape sequence in character class
  range out of order in character class
  nothing to repeat
- operand of unlimited repeat could match the empty string
+ [this code is not in use]
  internal error: unexpected repeat
- unrecognized character after (?
+ unrecognized character after (? or (?-
  POSIX named classes are supported only within a class
  missing )
  reference to non-existent subpattern
  erroffset passed as NULL
  unknown option bit(s) set
  missing ) after comment
- parentheses nested too deeply
+ [this code is not in use]
- regular expression too large
+ regular expression is too large
  failed to get memory
  unmatched parentheses
  internal error: code overflow
  unrecognized character after (?<
  lookbehind assertion is not fixed length
- malformed number after (?(
+ malformed number or name after (?(
  conditional group contains more than two branches
  assertion expected after (?(
- (?R or (?digits must be followed by )
+ (?R or (?[+-]digits must be followed by )
  unknown POSIX class name
  POSIX collating elements are not supported
  this version of PCRE is not compiled with PCRE_UTF8 support
- spare error
+ [this code is not in use]
  character value in \x{...} sequence is too large
  invalid condition (?(0)
  \C not allowed in lookbehind assertion
-Line 1075 
 COMPILATION ERROR CODES
+Line 1450 
 COMPILATION ERROR CODES
  closing ) for (?C expected
  recursive call could loop indefinitely
  unrecognized character after (?P
- syntax error after (?P
+ syntax error in subpattern name (missing terminator)
- two named groups have the same name
+ two named subpatterns have the same name
  invalid UTF-8 string
  support for \P, \p, and \X has not been compiled
  malformed \P or \p sequence
  unknown property name after \P or \p
+ subpattern name is too long (maximum 32 characters)
+ too many named subpatterns (maximum 10000)
+ [this code is not in use]
+ octal value is greater than \377 (not in UTF-8 mode)
+ internal error: overran compiling workspace
+  internal  error:  previously-checked  referenced  subpattern not
+        found
+ DEFINE group contains more than one branch
+ repeating a DEFINE group is not allowed
+ inconsistent NEWLINE options
+ \g is not followed by a braced, angle-bracketed, or quoted
+                name/number or by a plain number
+ a numbered reference must not be zero
+ an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
+ (*VERB) not recognized
+ number is too big
+ subpattern name expected
+ digit expected after (?+
+ ] is an invalid data character in JavaScript compatibility mode
+ different names for  subpatterns  of  the  same  number  are  not
+        allowed
+ (*MARK) must have an argument
+        The  numbers  32  and 10000 in errors 48 and 49 are defaults; different
+        values may be used if the limits were changed when PCRE was built.
  STUDYING A PATTERN
-Line 1097 
 STUDYING A PATTERN
+Line 1497 
 STUDYING A PATTERN
         the results of the study.
         The  returned  value  from  pcre_study()  can  be  passed  directly  to
-        pcre_exec().  However,  a  pcre_extra  block also contains other fields
+        pcre_exec()  or  pcre_dfa_exec(). However, a pcre_extra block also con-
-        that can be set by the caller before the block  is  passed;  these  are
+        tains other fields that can be set by the caller before  the  block  is
-        described below in the section on matching a pattern.
+        passed; these are described below in the section on matching a pattern.
-        If  studying  the  pattern  does not produce any additional information
+        If  studying  the  pattern  does  not  produce  any useful information,
         pcre_study() returns NULL. In that circumstance, if the calling program
-        wants  to  pass  any of the other fields to pcre_exec(), it must set up
+        wants   to   pass   any   of   the   other  fields  to  pcre_exec()  or
-        its own pcre_extra block.
+        pcre_dfa_exec(), it must set up its own pcre_extra block.
         The second argument of pcre_study() contains option bits.  At  present,
         no options are defined, and this argument should always be zero.
         The  third argument for pcre_study() is a pointer for an error message.
         If studying succeeds (even if no data is  returned),  the  variable  it
-        points  to  is set to NULL. Otherwise it points to a textual error mes-
+        points  to  is  set  to NULL. Otherwise it is set to point to a textual
-        sage. You should therefore test the error pointer for NULL after  call-
+        error message. This is a static string that is part of the library. You
-        ing pcre_study(), to be sure that it has run successfully.
+        must  not  try  to  free it. You should test the error pointer for NULL
+        after calling pcre_study(), to be sure that it has run successfully.
         This is a typical call to pcre_study():
-Line 1123 
 STUDYING A PATTERN
+Line 1524 
 STUDYING A PATTERN
 ,              /* no options exist */
             &error);        /* set to NULL or points to a message */
-        At present, studying a pattern is useful only for non-anchored patterns
+        Studying a pattern does two things: first, a lower bound for the length
-        that do not have a single fixed starting character. A bitmap of  possi-
+        of subject string that is needed to match the pattern is computed. This
-        ble starting bytes is created.
+        does not mean that there are any strings of that length that match, but
+        it  does  guarantee that no shorter strings match. The value is used by
+        pcre_exec() and pcre_dfa_exec() to avoid  wasting  time  by  trying  to
+        match  strings  that are shorter than the lower bound. You can find out
+        the value in a calling program via the pcre_fullinfo() function.
+        Studying a pattern is also useful for non-anchored patterns that do not
+        have  a  single fixed starting character. A bitmap of possible starting
+        bytes is created. This speeds up finding a position in the  subject  at
+        which to start matching.
  LOCALE SUPPORT
         PCRE  handles  caseless matching, and determines whether characters are
-        letters digits, or whatever, by reference to a set of  tables,  indexed
+        letters, digits, or whatever, by reference to a set of tables,  indexed
         by  character  value.  When running in UTF-8 mode, this applies only to
         characters with codes less than 128. Higher-valued  codes  never  match
         escapes  such  as  \w or \d, but can be tested with \p if PCRE is built
-        with Unicode character property support.
+        with Unicode character property support. The use of locales  with  Uni-
+        code  is discouraged. If you are handling characters with codes greater
-        An internal set of tables is created in the default C locale when  PCRE
+        than 128, you should either use UTF-8 and Unicode, or use locales,  but
-        is  built.  This  is  used when the final argument of pcre_compile() is
+        not try to mix the two.
-        NULL, and is sufficient for many applications. An  alternative  set  of
-        tables  can,  however, be supplied. These may be created in a different
+        PCRE  contains  an  internal set of tables that are used when the final
-        locale from the default. As more and more applications change to  using
+        argument of pcre_compile() is  NULL.  These  are  sufficient  for  many
-        Unicode, the need for this locale support is expected to die away.
+        applications.  Normally, the internal tables recognize only ASCII char-
+        acters. However, when PCRE is built, it is possible to cause the inter-
+        nal tables to be rebuilt in the default "C" locale of the local system,
+        which may cause them to be different.
+        The internal tables can always be overridden by tables supplied by  the
+        application that calls PCRE. These may be created in a different locale
+        from the default. As more and more applications change  to  using  Uni-
+        code, the need for this locale support is expected to die away.
         External  tables  are  built by calling the pcre_maketables() function,
         which has no arguments, in the relevant locale. The result can then  be
-Line 1155 
 LOCALE SUPPORT
+Line 1573 
 LOCALE SUPPORT
           tables = pcre_maketables();
           re = pcre_compile(..., tables);
-        When pcre_maketables() runs, the tables are built  in  memory  that  is
+        The locale name "fr_FR" is used on Linux and other  Unix-like  systems;
-        obtained  via  pcre_malloc. It is the caller's responsibility to ensure
+        if you are using Windows, the name for the French locale is "french".
-        that the memory containing the tables remains available for as long  as
+        When  pcre_maketables()  runs,  the  tables are built in memory that is
+        obtained via pcre_malloc. It is the caller's responsibility  to  ensure
+        that  the memory containing the tables remains available for as long as
         it is needed.
         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()
+        pattern,  and the same tables are used via this pointer by pcre_study()
         and normally also by pcre_exec(). Thus, by default, for any single pat-
         tern, compilation, studying and matching all happen in the same locale,
         but different patterns can be compiled in different locales.
-        It  is  possible to pass a table pointer or NULL (indicating the use of
+        It is possible to pass a table pointer or NULL (indicating the  use  of
-        the internal tables) to pcre_exec(). Although  not  intended  for  this
+        the  internal  tables)  to  pcre_exec(). Although not intended for this
-        purpose,  this facility could be used to match a pattern in a different
+        purpose, this facility could be used to match a pattern in a  different
         locale from the one in which it was compiled. Passing table pointers at
         run time is discussed below in the section on matching a pattern.
-Line 1178 
 INFORMATION ABOUT A PATTERN
+Line 1599 
 INFORMATION ABOUT A PATTERN
         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
              int what, void *where);
-        The  pcre_fullinfo() function returns information about a compiled pat-
+        The pcre_fullinfo() function returns information about a compiled  pat-
         tern. It replaces the obsolete pcre_info() function, which is neverthe-
         less retained for backwards compability (and is documented below).
-        The  first  argument  for  pcre_fullinfo() is a pointer to the compiled
+        The first argument for pcre_fullinfo() is a  pointer  to  the  compiled
-        pattern. The second argument is the result of pcre_study(), or NULL  if
+        pattern.  The second argument is the result of pcre_study(), or NULL if
-        the  pattern  was not studied. The third argument specifies which piece
+        the pattern was not studied. The third argument specifies  which  piece
-        of information is required, and the fourth argument is a pointer  to  a
+        of  information  is required, and the fourth argument is a pointer to a
-        variable  to  receive  the  data. The yield of the function is zero for
+        variable to receive the data. The yield of the  function  is  zero  for
         success, or one of the following negative numbers:
           PCRE_ERROR_NULL       the argument code was NULL
-Line 1194 
 INFORMATION ABOUT A PATTERN
+Line 1615 
 INFORMATION ABOUT A PATTERN
           PCRE_ERROR_BADMAGIC   the "magic number" was not found
           PCRE_ERROR_BADOPTION  the value of what was invalid
-        The "magic number" is placed at the start of each compiled  pattern  as
+        The  "magic  number" is placed at the start of each compiled pattern as
-        an  simple check against passing an arbitrary memory pointer. Here is a
+        an simple check against passing an arbitrary memory pointer. Here is  a
-        typical call of pcre_fullinfo(), to obtain the length of  the  compiled
+        typical  call  of pcre_fullinfo(), to obtain the length of the compiled
         pattern:
           int rc;
-          unsigned long int length;
+          size_t length;
           rc = pcre_fullinfo(
             re,               /* result of pcre_compile() */
             pe,               /* result of pcre_study(), or NULL */
             PCRE_INFO_SIZE,   /* what is required */
             &length);         /* where to put the data */
-        The  possible  values for the third argument are defined in pcre.h, and
+        The possible values for the third argument are defined in  pcre.h,  and
         are as follows:
           PCRE_INFO_BACKREFMAX
-        Return the number of the highest back reference  in  the  pattern.  The
+        Return  the  number  of  the highest back reference in the pattern. The
-        fourth  argument  should  point to an int variable. Zero is returned if
+        fourth argument should point to an int variable. Zero  is  returned  if
         there are no back references.
           PCRE_INFO_CAPTURECOUNT
-        Return the number of capturing subpatterns in the pattern.  The  fourth
+        Return  the  number of capturing subpatterns in the pattern. The fourth
         argument should point to an int variable.
           PCRE_INFO_DEFAULT_TABLES
-        Return  a pointer to the internal default character tables within PCRE.
+        Return a pointer to the internal default character tables within  PCRE.
-        The fourth argument should point to an unsigned char *  variable.  This
+        The  fourth  argument should point to an unsigned char * variable. This
         information call is provided for internal use by the pcre_study() func-
-        tion. External callers can cause PCRE to use  its  internal  tables  by
+        tion.  External  callers  can  cause PCRE to use its internal tables by
         passing a NULL table pointer.
           PCRE_INFO_FIRSTBYTE
-        Return  information  about  the first byte of any matched string, for a
+        Return information about the first byte of any matched  string,  for  a
-        non-anchored   pattern.   (This    option    used    to    be    called
+        non-anchored  pattern. The fourth argument should point to an int vari-
-        PCRE_INFO_FIRSTCHAR;  the  old  name  is still recognized for backwards
+        able. (This option used to be called PCRE_INFO_FIRSTCHAR; the old  name
-        compatibility.)
+        is still recognized for backwards compatibility.)
-        If there is a fixed first byte, for example, from  a  pattern  such  as
+        If  there  is  a  fixed first byte, for example, from a pattern such as
-        (cat|cow|coyote),  it  is  returned in the integer pointed to by where.
+        (cat|cow|coyote), its value is returned. Otherwise, if either
-        Otherwise, if either
         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
         branch starts with "^", or
-Line 1258 
 INFORMATION ABOUT A PATTERN
+Line 1678 
 INFORMATION ABOUT A PATTERN
         returned.  The fourth argument should point to an unsigned char * vari-
         able.
+          PCRE_INFO_HASCRORLF
+        Return 1 if the pattern contains any explicit  matches  for  CR  or  LF
+        characters,  otherwise  0.  The  fourth argument should point to an int
+        variable. An explicit match is either a literal CR or LF character,  or
+        \r or \n.
+          PCRE_INFO_JCHANGED
+        Return  1  if  the (?J) or (?-J) option setting is used in the pattern,
+        otherwise 0. The fourth argument should point to an int variable.  (?J)
+        and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
           PCRE_INFO_LASTLITERAL
-        Return the value of the rightmost literal byte that must exist  in  any
+        Return  the  value of the rightmost literal byte that must exist in any
-        matched  string,  other  than  at  its  start,  if such a byte has been
+        matched string, other than at its  start,  if  such  a  byte  has  been
         recorded. The fourth argument should point to an int variable. If there
-        is  no such byte, -1 is returned. For anchored patterns, a last literal
+        is no such byte, -1 is returned. For anchored patterns, a last  literal
-        byte is recorded only if it follows something of variable  length.  For
+        byte  is  recorded only if it follows something of variable length. For
         example, for the pattern /^a\d+z\d+/ the returned value is "z", but for
         /^a\dz\d/ the returned value is -1.
+          PCRE_INFO_MINLENGTH
+        If  the  pattern  was studied and a minimum length for matching subject
+        strings was computed, its value is  returned.  Otherwise  the  returned
+        value  is  -1. The value is a number of characters, not bytes (this may
+        be relevant in UTF-8 mode). The fourth argument should point to an  int
+        variable.  A  non-negative  value is a lower bound to the length of any
+        matching string. There may not be any strings of that  length  that  do
+        actually match, but every string that does match is at least that long.
           PCRE_INFO_NAMECOUNT
           PCRE_INFO_NAMEENTRYSIZE
           PCRE_INFO_NAMETABLE
-        PCRE supports the use of named as well as numbered capturing  parenthe-
+        PCRE  supports the use of named as well as numbered capturing parenthe-
-        ses.  The names are just an additional way of identifying the parenthe-
+        ses. The names are just an additional way of identifying the  parenthe-
-        ses,  which  still  acquire  numbers.  A  convenience  function  called
+        ses, which still acquire numbers. Several convenience functions such as
-        pcre_get_named_substring()  is  provided  for  extracting an individual
+        pcre_get_named_substring() are provided for  extracting  captured  sub-
-        captured substring by name. It is also possible  to  extract  the  data
+        strings  by  name. It is also possible to extract the data directly, by
-        directly,  by  first converting the name to a number in order to access
+        first converting the name to a number in order to  access  the  correct
-        the correct pointers in the output vector (described  with  pcre_exec()
+        pointers in the output vector (described with pcre_exec() below). To do
-        below).  To  do the conversion, you need to use the name-to-number map,
+        the conversion, you need  to  use  the  name-to-number  map,  which  is
-        which is described by these three values.
+        described by these three values.
         The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT
         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size
-        of each entry; both of these  return  an  int  value.  The  entry  size
+        of  each  entry;  both  of  these  return  an int value. The entry size
-        depends  on the length of the longest name. PCRE_INFO_NAMETABLE returns
+        depends on the length of the longest name. PCRE_INFO_NAMETABLE  returns
-        a pointer to the first entry of the table  (a  pointer  to  char).  The
+        a  pointer  to  the  first  entry of the table (a pointer to char). The
         first two bytes of each entry are the number of the capturing parenthe-
-        sis, most significant byte first. The rest of the entry is  the  corre-
+        sis,  most  significant byte first. The rest of the entry is the corre-
-        sponding  name,  zero  terminated. The names are in alphabetical order.
+        sponding name, zero terminated.
-        For example, consider the following pattern  (assume  PCRE_EXTENDED  is
-        set, so white space - including newlines - is ignored):
+        The names are in alphabetical order. Duplicate names may appear if  (?|
+        is used to create multiple groups with the same number, as described in
+        the section on duplicate subpattern numbers in  the  pcrepattern  page.
+        Duplicate  names  for  subpatterns with different numbers are permitted
+        only if PCRE_DUPNAMES is set. In all cases  of  duplicate  names,  they
+        appear  in  the table in the order in which they were found in the pat-
+        tern. In the absence of (?| this is the  order  of  increasing  number;
+        when (?| is used this is not necessarily the case because later subpat-
+        terns may have lower numbers.
+        As a simple example of the name/number table,  consider  the  following
+        pattern  (assume  PCRE_EXTENDED is set, so white space - including new-
+        lines - is ignored):
-          (?P<date> (?P<year>(\d\d)?\d\d) -
+          (?<date> (?<year>(\d\d)?\d\d) -
-          (?P<month>\d\d) - (?P<day>\d\d) )
+          (?<month>\d\d) - (?<day>\d\d) )
-        There  are  four  named subpatterns, so the table has four entries, and
+        There are four named subpatterns, so the table has  four  entries,  and
-        each entry in the table is eight bytes long. The table is  as  follows,
+        each  entry  in the table is eight bytes long. The table is as follows,
         with non-printing bytes shows in hexadecimal, and undefined bytes shown
         as ??:
-Line 1306 
 INFORMATION ABOUT A PATTERN
+Line 1761 
 INFORMATION ABOUT A PATTERN
 04 m  o  n  t  h  00
 02 y  e  a  r  00 ??
-        When writing code to extract data  from  named  subpatterns  using  the
+        When  writing  code  to  extract  data from named subpatterns using the
-        name-to-number map, remember that the length of each entry is likely to
+        name-to-number map, remember that the length of the entries  is  likely
-        be different for each compiled pattern.
+        to be different for each compiled pattern.
+          PCRE_INFO_OKPARTIAL
+        Return  1  if  the  pattern  can  be  used  for  partial  matching with
+        pcre_exec(), otherwise 0. The fourth argument should point  to  an  int
+        variable.  From  release  8.00,  this  always  returns  1,  because the
+        restrictions that previously applied  to  partial  matching  have  been
+        lifted.  The  pcrepartial documentation gives details of partial match-
+        ing.
           PCRE_INFO_OPTIONS
         Return a copy of the options with which the pattern was  compiled.  The
         fourth  argument  should  point to an unsigned long int variable. These
         option bits are those specified in the call to pcre_compile(), modified
-        by any top-level option settings within the pattern itself.
+        by any top-level option settings at the start of the pattern itself. In
+        other words, they are the options that will be in force  when  matching
+        starts.  For  example, if the pattern /(?im)abc(?-i)d/ is compiled with
+        the PCRE_EXTENDED option, the result is PCRE_CASELESS,  PCRE_MULTILINE,
+        and PCRE_EXTENDED.
         A  pattern  is  automatically  anchored by PCRE if all of its top-level
         alternatives begin with one of the following:
-Line 1341 
 INFORMATION ABOUT A PATTERN
+Line 1809 
 INFORMATION ABOUT A PATTERN
         Return the size of the data block pointed to by the study_data field in
         a  pcre_extra  block.  That  is,  it  is  the  value that was passed to
         pcre_malloc() when PCRE was getting memory into which to place the data
-        created  by  pcre_study(). The fourth argument should point to a size_t
+        created  by  pcre_study().  If pcre_extra is NULL, or there is no study
+        data, zero is returned. The fourth argument should point  to  a  size_t
         variable.
-Line 1349 
 OBSOLETE INFO FUNCTION
+Line 1818 
 OBSOLETE INFO FUNCTION
         int pcre_info(const pcre *code, int *optptr, int *firstcharptr);
-        The pcre_info() function is now obsolete because its interface  is  too
+        The  pcre_info()  function is now obsolete because its interface is too
-        restrictive  to return all the available data about a compiled pattern.
+        restrictive to return all the available data about a compiled  pattern.
-        New  programs  should  use  pcre_fullinfo()  instead.  The   yield   of
+        New   programs   should  use  pcre_fullinfo()  instead.  The  yield  of
-        pcre_info()  is the number of capturing subpatterns, or one of the fol-
+        pcre_info() is the number of capturing subpatterns, or one of the  fol-
         lowing negative numbers:
           PCRE_ERROR_NULL       the argument code was NULL
           PCRE_ERROR_BADMAGIC   the "magic number" was not found
-        If the optptr argument is not NULL, a copy of the  options  with  which
+        If  the  optptr  argument is not NULL, a copy of the options with which
-        the  pattern  was  compiled  is placed in the integer it points to (see
+        the pattern was compiled is placed in the integer  it  points  to  (see
         PCRE_INFO_OPTIONS above).
-        If the pattern is not anchored and the  firstcharptr  argument  is  not
+        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
+        NULL, it is used to pass back information about the first character  of
         any matched string (see PCRE_INFO_FIRSTBYTE above).
-Line 1371 
 REFERENCE COUNTS
+Line 1840 
 REFERENCE COUNTS
         int pcre_refcount(pcre *code, int adjust);
-        The pcre_refcount() function is used to maintain a reference  count  in
+        The  pcre_refcount()  function is used to maintain a reference count in
         the data block that contains a compiled pattern. It is provided for the
-        benefit of applications that  operate  in  an  object-oriented  manner,
+        benefit  of  applications  that  operate  in an object-oriented manner,
         where different parts of the application may be using the same compiled
         pattern, but you want to free the block when they are all done.
         When a pattern is compiled, the reference count field is initialized to
-        zero.   It is changed only by calling this function, whose action is to
+        zero.  It is changed only by calling this function, whose action is  to
-        add the adjust value (which may be positive or  negative)  to  it.  The
+        add  the  adjust  value  (which may be positive or negative) to it. The
         yield of the function is the new value. However, the value of the count
-        is constrained to lie between 0 and 65535, inclusive. If the new  value
+        is  constrained to lie between 0 and 65535, inclusive. If the new value
         is outside these limits, it is forced to the appropriate limit value.
-        Except  when it is zero, the reference count is not correctly preserved
+        Except when it is zero, the reference count is not correctly  preserved
-        if a pattern is compiled on one host and then  transferred  to  a  host
+        if  a  pattern  is  compiled on one host and then transferred to a host
         whose byte-order is different. (This seems a highly unlikely scenario.)
-Line 1397 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 1866 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
         The function pcre_exec() is called to match a subject string against  a
         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
+        was studied, the result of the study should  be  passed  in  the  extra
         argument.  This  function is the main matching facility of the library,
         and it operates in a Perl-like manner. For specialist use there is also
         an  alternative matching function, which is described below in the sec-
-Line 1428 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 1897 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
         If the extra argument is not NULL, it must point to a  pcre_extra  data
         block.  The pcre_study() function returns such a block (when it doesn't
         return NULL), but you can also create one for yourself, and pass  addi-
-        tional  information in it. The fields in a pcre_extra block are as fol-
+        tional  information  in it. The pcre_extra block contains the following
-        lows:
+        fields (not necessarily in this order):
           unsigned long int flags;
           void *study_data;
           unsigned long int match_limit;
+          unsigned long int match_limit_recursion;
           void *callout_data;
           const unsigned char *tables;
+          unsigned char **mark;
         The flags field is a bitmap that specifies which of  the  other  fields
         are set. The flag bits are:
           PCRE_EXTRA_STUDY_DATA
           PCRE_EXTRA_MATCH_LIMIT
+          PCRE_EXTRA_MATCH_LIMIT_RECURSION
           PCRE_EXTRA_CALLOUT_DATA
           PCRE_EXTRA_TABLES
+          PCRE_EXTRA_MARK
         Other  flag  bits should be set to zero. The study_data field is set in
         the pcre_extra block that is returned by  pcre_study(),  together  with
-Line 1454 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 1927 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
         The match_limit field provides a means of preventing PCRE from using up
         a vast amount of resources when running patterns that are not going  to
         match,  but  which  have  a very large number of possibilities in their
-        search trees. The classic  example  is  the  use  of  nested  unlimited
+        search trees. The classic example is a pattern that uses nested  unlim-
-        repeats.
+        ited repeats.
         Internally,  PCRE uses a function called match() which it calls repeat-
-        edly (sometimes recursively). The limit is imposed  on  the  number  of
+        edly (sometimes recursively). The limit set by match_limit  is  imposed
-        times  this  function is called during a match, which has the effect of
+        on  the  number  of times this function is called during a match, which
-        limiting the amount of recursion and backtracking that can take  place.
+        has the effect of limiting the amount of  backtracking  that  can  take
-        For patterns that are not anchored, the count starts from zero for each
+        place. For patterns that are not anchored, the count restarts from zero
-        position in the subject string.
+        for each position in the subject string.
-        The default limit for the library can be set when PCRE  is  built;  the
+        The default value for the limit can be set  when  PCRE  is  built;  the
         default  default  is 10 million, which handles all but the most extreme
-        cases. You can reduce  the  default  by  suppling  pcre_exec()  with  a
+        cases. You can override the default  by  suppling  pcre_exec()  with  a
-        pcre_extra  block  in  which match_limit is set to a smaller value, and
+        pcre_extra     block    in    which    match_limit    is    set,    and
         PCRE_EXTRA_MATCH_LIMIT is set in the  flags  field.  If  the  limit  is
         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
-        The  pcre_callout  field is used in conjunction with the "callout" fea-
+        The  match_limit_recursion field is similar to match_limit, but instead
-        ture, which is described in the pcrecallout documentation.
+        of limiting the total number of times that match() is called, it limits
+        the  depth  of  recursion. The recursion depth is a smaller number than
-        The tables field  is  used  to  pass  a  character  tables  pointer  to
+        the total number of calls, because not all calls to match() are  recur-
-        pcre_exec();  this overrides the value that is stored with the compiled
+        sive.  This limit is of use only if it is set smaller than match_limit.
-        pattern. A non-NULL value is stored with the compiled pattern  only  if
-        custom  tables  were  supplied to pcre_compile() via its tableptr argu-
+        Limiting  the  recursion  depth  limits the amount of stack that can be
+        used, or, when PCRE has been compiled to use memory on the heap instead
+        of the stack, the amount of heap memory that can be used.
+        The  default  value  for  match_limit_recursion can be set when PCRE is
+        built; the default default  is  the  same  value  as  the  default  for
+        match_limit.  You can override the default by suppling pcre_exec() with
+        a  pcre_extra  block  in  which  match_limit_recursion  is   set,   and
+        PCRE_EXTRA_MATCH_LIMIT_RECURSION  is  set  in  the  flags field. If the
+        limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.
+        The callout_data field is used in conjunction with the  "callout"  fea-
+        ture, and is described in the pcrecallout documentation.
+        The  tables  field  is  used  to  pass  a  character  tables pointer to
+        pcre_exec(); this overrides the value that is stored with the  compiled
+        pattern.  A  non-NULL value is stored with the compiled pattern only if
+        custom tables were supplied to pcre_compile() via  its  tableptr  argu-
         ment.  If NULL is passed to pcre_exec() using this mechanism, it forces
-        PCRE's  internal  tables  to be used. This facility is helpful when re-
+        PCRE's internal tables to be used. This facility is  helpful  when  re-
-        using patterns that have been saved after compiling  with  an  external
+        using  patterns  that  have been saved after compiling with an external
-        set  of  tables,  because  the  external tables might be at a different
+        set of tables, because the external tables  might  be  at  a  different
-        address when pcre_exec() is called. See the  pcreprecompile  documenta-
+        address  when  pcre_exec() is called. See the pcreprecompile documenta-
         tion for a discussion of saving compiled patterns for later use.
+        If PCRE_EXTRA_MARK is set in the flags field, the mark  field  must  be
+        set  to  point  to a char * variable. If the pattern contains any back-
+        tracking control verbs such as (*MARK:NAME), and the execution ends  up
+        with  a  name  to  pass back, a pointer to the name string (zero termi-
+        nated) is placed in the variable pointed to  by  the  mark  field.  The
+        names  are  within  the  compiled pattern; if you wish to retain such a
+        name you must copy it before freeing the memory of a compiled  pattern.
+        If  there  is no name to pass back, the variable pointed to by the mark
+        field set to NULL. For details of the backtracking control  verbs,  see
+        the section entitled "Backtracking control" in the pcrepattern documen-
+        tation.
     Option bits for pcre_exec()
-        The  unused  bits of the options argument for pcre_exec() must be zero.
+        The unused bits of the options argument for pcre_exec() must  be  zero.
-        The  only  bits  that  may  be  set  are  PCRE_ANCHORED,   PCRE_NOTBOL,
+        The  only  bits  that  may  be set are PCRE_ANCHORED, PCRE_NEWLINE_xxx,
-        PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.
+        PCRE_NOTBOL,   PCRE_NOTEOL,    PCRE_NOTEMPTY,    PCRE_NOTEMPTY_ATSTART,
+        PCRE_NO_START_OPTIMIZE,   PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_SOFT,  and
+        PCRE_PARTIAL_HARD.
           PCRE_ANCHORED
-        The  PCRE_ANCHORED  option  limits pcre_exec() to matching at the first
+        The PCRE_ANCHORED option limits pcre_exec() to matching  at  the  first
-        matching position. If a pattern was  compiled  with  PCRE_ANCHORED,  or
+        matching  position.  If  a  pattern was compiled with PCRE_ANCHORED, or
-        turned  out to be anchored by virtue of its contents, it cannot be made
+        turned out to be anchored by virtue of its contents, it cannot be  made
         unachored at matching time.
+          PCRE_BSR_ANYCRLF
+          PCRE_BSR_UNICODE
+        These options (which are mutually exclusive) control what the \R escape
+        sequence matches. The choice is either to match only CR, LF,  or  CRLF,
+        or  to  match  any Unicode newline sequence. These options override the
+        choice that was made or defaulted when the pattern was compiled.
+          PCRE_NEWLINE_CR
+          PCRE_NEWLINE_LF
+          PCRE_NEWLINE_CRLF
+          PCRE_NEWLINE_ANYCRLF
+          PCRE_NEWLINE_ANY
+        These options override  the  newline  definition  that  was  chosen  or
+        defaulted  when the pattern was compiled. For details, see the descrip-
+        tion of pcre_compile()  above.  During  matching,  the  newline  choice
+        affects  the  behaviour  of the dot, circumflex, and dollar metacharac-
+        ters. It may also alter the way the match position is advanced after  a
+        match failure for an unanchored pattern.
+        When  PCRE_NEWLINE_CRLF,  PCRE_NEWLINE_ANYCRLF,  or PCRE_NEWLINE_ANY is
+        set, and a match attempt for an unanchored pattern fails when the  cur-
+        rent  position  is  at  a  CRLF  sequence,  and the pattern contains no
+        explicit matches for  CR  or  LF  characters,  the  match  position  is
+        advanced by two characters instead of one, in other words, to after the
+        CRLF.
+        The above rule is a compromise that makes the most common cases work as
+        expected.  For  example,  if  the  pattern  is .+A (and the PCRE_DOTALL
+        option is not set), it does not match the string "\r\nA" because, after
+        failing  at the start, it skips both the CR and the LF before retrying.
+        However, the pattern [\r\n]A does match that string,  because  it  con-
+        tains an explicit CR or LF reference, and so advances only by one char-
+        acter after the first failure.
+        An explicit match for CR of LF is either a literal appearance of one of
+        those  characters,  or  one  of the \r or \n escape sequences. Implicit
+        matches such as [^X] do not count, nor does \s (which includes  CR  and
+        LF in the characters that it matches).
+        Notwithstanding  the above, anomalous effects may still occur when CRLF
+        is a valid newline sequence and explicit \r or \n escapes appear in the
+        pattern.
           PCRE_NOTBOL
         This option specifies that first character of the subject string is not
-        the  beginning  of  a  line, so the circumflex metacharacter should not
+        the beginning of a line, so the  circumflex  metacharacter  should  not
-        match before it. Setting this without PCRE_MULTILINE (at compile  time)
+        match  before it. Setting this without PCRE_MULTILINE (at compile time)
-        causes  circumflex  never to match. This option affects only the behav-
+        causes circumflex never to match. This option affects only  the  behav-
         iour of the circumflex metacharacter. It does not affect \A.
           PCRE_NOTEOL
         This option specifies that the end of the subject string is not the end
-        of  a line, so the dollar metacharacter should not match it nor (except
+        of a line, so the dollar metacharacter should not match it nor  (except
-        in multiline mode) a newline immediately before it. Setting this  with-
+        in  multiline mode) a newline immediately before it. Setting this with-
         out PCRE_MULTILINE (at compile time) causes dollar never to match. This
-        option affects only the behaviour of the dollar metacharacter. It  does
+        option  affects only the behaviour of the dollar metacharacter. It does
         not affect \Z or \z.
           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
+        set.  If  there are alternatives in the pattern, they are tried. If all
-        the  alternatives  match  the empty string, the entire match fails. For
+        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
+        is  applied  to  a  string not beginning with "a" or "b", it matches an
-        empty  string at the start of the subject. With PCRE_NOTEMPTY set, this
+        empty string at the start of the subject. With PCRE_NOTEMPTY set,  this
         match is not valid, so PCRE searches further into the string for occur-
         rences of "a" or "b".
-        Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a spe-
+          PCRE_NOTEMPTY_ATSTART
-        cial case of a pattern match of the empty  string  within  its  split()
-        function,  and  when  using  the /g modifier. It is possible to emulate
+        This is like PCRE_NOTEMPTY, except that an empty string match  that  is
-        Perl's behaviour after matching a null string by first trying the match
+        not  at  the  start  of  the  subject  is  permitted. If the pattern is
-        again at the same offset with PCRE_NOTEMPTY and PCRE_ANCHORED, and then
+        anchored, such a match can occur only if the pattern contains \K.
-        if that fails by advancing the starting offset (see below)  and  trying
-        an ordinary match again. There is some code that demonstrates how to do
+        Perl    has    no    direct    equivalent    of    PCRE_NOTEMPTY     or
-        this in the pcredemo.c sample program.
+        PCRE_NOTEMPTY_ATSTART,  but  it  does  make a special case of a pattern
+        match of the empty string within its split() function, and  when  using
+        the  /g  modifier.  It  is  possible  to emulate Perl's behaviour after
+        matching a null string by first trying the match again at the same off-
+        set  with  PCRE_NOTEMPTY_ATSTART  and  PCRE_ANCHORED,  and then if that
+        fails, by advancing the starting offset (see below) and trying an ordi-
+        nary  match  again. There is some code that demonstrates how to do this
+        in the pcredemo sample program.
+          PCRE_NO_START_OPTIMIZE
+        There are a number of optimizations that pcre_exec() uses at the  start
+        of  a  match,  in  order to speed up the process. For example, if it is
+        known that a match must start with a specific  character,  it  searches
+        the subject for that character, and fails immediately if it cannot find
+        it, without actually running the main matching function. When  callouts
+        are  in  use,  these  optimizations  can cause them to be skipped. This
+        option disables the "start-up" optimizations,  causing  performance  to
+        suffer, but ensuring that the callouts do occur.
           PCRE_NO_UTF8_CHECK
         When PCRE_UTF8 is set at compile time, the validity of the subject as a
-        UTF-8  string is automatically checked when pcre_exec() is subsequently
+        UTF-8 string is automatically checked when pcre_exec() is  subsequently
-        called.  The value of startoffset is also checked  to  ensure  that  it
+        called.   The  value  of  startoffset is also checked to ensure that it
-        points  to the start of a UTF-8 character. If an invalid UTF-8 sequence
+        points to the start of a UTF-8 character. There is a  discussion  about
-        of bytes is found, pcre_exec() returns the error PCRE_ERROR_BADUTF8. If
+        the  validity  of  UTF-8 strings in the section on UTF-8 support in the
-        startoffset  contains  an  invalid  value, PCRE_ERROR_BADUTF8_OFFSET is
+        main pcre page. If  an  invalid  UTF-8  sequence  of  bytes  is  found,
-        returned.
+        pcre_exec()  returns  the error PCRE_ERROR_BADUTF8. If startoffset con-
+        tains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.
         If you already know that your subject is valid, and you  want  to  skip
         these    checks    for   performance   reasons,   you   can   set   the
-Line 1559 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 2127 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
         value of startoffset that does not point to the start of a UTF-8  char-
         acter, is undefined. Your program may crash.
-          PCRE_PARTIAL
+          PCRE_PARTIAL_HARD
+          PCRE_PARTIAL_SOFT
-        This  option  turns  on  the  partial  matching feature. If the subject
+        These  options turn on the partial matching feature. For backwards com-
-        string fails to match the pattern, but at some point during the  match-
+        patibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A  partial
-        ing  process  the  end of the subject was reached (that is, the subject
+        match  occurs if the end of the subject string is reached successfully,
-        partially matches the pattern and the failure to  match  occurred  only
+        but there are not enough subject characters to complete the  match.  If
-        because  there were not enough subject characters), pcre_exec() returns
+        this  happens  when  PCRE_PARTIAL_HARD  is set, pcre_exec() immediately
-        PCRE_ERROR_PARTIAL instead of PCRE_ERROR_NOMATCH. When PCRE_PARTIAL  is
+        returns PCRE_ERROR_PARTIAL. Otherwise,  if  PCRE_PARTIAL_SOFT  is  set,
-        used,  there  are restrictions on what may appear in the pattern. These
+        matching  continues by testing any other alternatives. Only if they all
-        are discussed in the pcrepartial documentation.
+        fail is PCRE_ERROR_PARTIAL returned  (instead  of  PCRE_ERROR_NOMATCH).
+        The portion of the string that was inspected when the partial match was
+        found is set as the first matching string. There  is  a  more  detailed
+        discussion in the pcrepartial documentation.
     The string to be matched by pcre_exec()
-        The subject string is passed to pcre_exec() as a pointer in subject,  a
+        The  subject string is passed to pcre_exec() as a pointer in subject, a
-        length  in  length, and a starting byte offset in startoffset. In UTF-8
+        length (in bytes) in length, and a starting byte offset in startoffset.
-        mode, the byte offset must point to the start  of  a  UTF-8  character.
+        In UTF-8 mode, the byte offset must point to the start of a UTF-8 char-
-        Unlike  the  pattern string, the subject may contain binary zero bytes.
+        acter. Unlike the pattern string, the subject may contain  binary  zero
-        When the starting offset is zero, the search for a match starts at  the
+        bytes.  When the starting offset is zero, the search for a match starts
-        beginning of the subject, and this is by far the most common case.
+        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  suc-
-Line 1613 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 2186 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
         string. PCRE supports several other kinds of  parenthesized  subpattern
         that do not cause substrings to be captured.
-        Captured  substrings are returned to the caller via a vector of integer
+        Captured substrings are returned to the caller via a vector of integers
-        offsets whose address is passed in ovector. The number of  elements  in
+        whose address is passed in ovector. The number of elements in the  vec-
-        the  vector is passed in ovecsize, which must be a non-negative number.
+        tor  is  passed in ovecsize, which must be a non-negative number. Note:
-        Note: this argument is NOT the size of ovector in bytes.
+        this argument is NOT the size of ovector in bytes.
         The first two-thirds of the vector is used to pass back  captured  sub-
         strings,  each  substring using a pair of integers. The remaining third
         of the vector is used as workspace by pcre_exec() while  matching  cap-
         turing  subpatterns, and is not available for passing back information.
-        The length passed in ovecsize should always be a multiple of three.  If
+        The number passed in ovecsize should always be a multiple of three.  If
         it is not, it is rounded down.
         When  a  match  is successful, information about captured substrings is
         returned in pairs of integers, starting at the  beginning  of  ovector,
         and  continuing  up  to two-thirds of its length at the most. The first
-        element of a pair is set to the offset of the first character in a sub-
+        element of each pair is set to the byte offset of the  first  character
-        string,  and  the  second  is  set to the offset of the first character
+        in  a  substring, and the second is set to the byte offset of the first
-        after the end of a substring. The  first  pair,  ovector[0]  and  ovec-
+        character after the end of a substring. Note: these values  are  always
-        tor[1],  identify  the  portion  of  the  subject string matched by the
+        byte offsets, even in UTF-8 mode. They are not character counts.
-        entire pattern. The next pair is used for the first  capturing  subpat-
-        tern,  and  so  on.  The value returned by pcre_exec() is the number of
+        The  first  pair  of  integers, ovector[0] and ovector[1], identify the
-        pairs that have been set. If there are no  capturing  subpatterns,  the
+        portion of the subject string matched by the entire pattern.  The  next
-        return  value  from  a  successful match is 1, indicating that just the
+        pair  is  used for the first capturing subpattern, and so on. The value
-        first pair of offsets has been set.
+        returned by pcre_exec() is one more than the highest numbered pair that
+        has  been  set.  For example, if two substrings have been captured, the
-        Some convenience functions are provided  for  extracting  the  captured
+        returned value is 3. If there are no capturing subpatterns, the  return
-        substrings  as  separate  strings. These are described in the following
+        value from a successful match is 1, indicating that just the first pair
-        section.
+        of offsets has been set.
-        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 is returned.
         If  the vector is too small to hold all the captured substring offsets,
         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 off-
+        function  returns  a value of zero. If the substring offsets are not of
-        sets are not of interest, pcre_exec() may be called with ovector passed
+        interest, pcre_exec() may be called with ovector  passed  as  NULL  and
-        as  NULL  and  ovecsize  as zero. However, if the pattern contains back
+        ovecsize  as zero. However, if the pattern contains back references and
-        references and the ovector is not big enough to  remember  the  related
+        the ovector is not big enough to remember the related substrings,  PCRE
-        substrings,  PCRE has to get additional memory for use during matching.
+        has  to  get additional memory for use during matching. Thus it is usu-
-        Thus it is usually advisable to supply an ovector.
+        ally advisable to supply an ovector.
-        Note that pcre_info() can be used to find out how many  capturing  sub-
+        The pcre_fullinfo() function can be used to find out how many capturing
-        patterns there are in a compiled pattern. The smallest size for ovector
+        subpatterns  there  are  in  a  compiled pattern. The smallest size for
-        that will allow for n captured substrings, in addition to  the  offsets
+        ovector that will allow for n captured substrings, in addition  to  the
-        of the substring matched by the whole pattern, is (n+1)*3.
+        offsets of the substring matched by the whole pattern, is (n+1)*3.
+        It  is  possible for 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) the
+        return from the function is 4, and subpatterns 1 and 3 are matched, but
+ is  not.  When  this happens, both values in the offset pairs corre-
+        sponding to unused subpatterns are set to -1.
+        Offset values that correspond to unused subpatterns at the end  of  the
+        expression  are  also  set  to  -1. For example, if the string "abc" is
+        matched against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are  not
+        matched.  The  return  from the function is 2, because the highest used
+        capturing subpattern number is 1. However, you can refer to the offsets
+        for  the  second  and third capturing subpatterns if you wish (assuming
+        the vector is large enough, of course).
+        Some convenience functions are provided  for  extracting  the  captured
+        substrings as separate strings. These are described below.
-    Return values from pcre_exec()
+    Error return values from pcre_exec()
         If  pcre_exec()  fails, it returns a negative number. The following are
         defined in the header file:
-Line 1691 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 2276 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
         an environment with the other endianness. This is the error  that  PCRE
         gives when the magic number is not present.
-          PCRE_ERROR_UNKNOWN_NODE   (-5)
+          PCRE_ERROR_UNKNOWN_OPCODE (-5)
         While running the pattern match, an unknown item was encountered in the
         compiled pattern. This error could be caused by a bug  in  PCRE  or  by
-Line 1713 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 2298 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
           PCRE_ERROR_MATCHLIMIT     (-8)
-        The  recursion  and backtracking limit, as specified by the match_limit
+        The  backtracking  limit,  as  specified  by the match_limit field in a
-        field in a pcre_extra structure (or defaulted)  was  reached.  See  the
+        pcre_extra structure (or defaulted) was reached.  See  the  description
-        description above.
+        above.
           PCRE_ERROR_CALLOUT        (-9)
-Line 1741 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 2326 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
           PCRE_ERROR_BADPARTIAL     (-13)
-        The  PCRE_PARTIAL  option  was  used with a compiled pattern containing
+        This  code  is  no  longer  in  use.  It was formerly returned when the
-        items that are not supported for partial matching. See the  pcrepartial
+        PCRE_PARTIAL option was used with a compiled pattern  containing  items
-        documentation for details of partial matching.
+        that  were  not  supported  for  partial  matching.  From  release 8.00
+        onwards, there are no restrictions on partial matching.
           PCRE_ERROR_INTERNAL       (-14)
-        An  unexpected  internal error has occurred. This error could be caused
+        An unexpected internal error has occurred. This error could  be  caused
         by a bug in PCRE or by overwriting of the compiled pattern.
           PCRE_ERROR_BADCOUNT       (-15)
-        This error is given if the value of the ovecsize argument is  negative.
+        This error is given if the value of the ovecsize argument is negative.
+          PCRE_ERROR_RECURSIONLIMIT (-21)
+        The internal recursion limit, as specified by the match_limit_recursion
+        field in a pcre_extra structure (or defaulted)  was  reached.  See  the
+        description above.
+          PCRE_ERROR_BADNEWLINE     (-23)
+        An invalid combination of PCRE_NEWLINE_xxx options was given.
+        Error numbers -16 to -20 and -22 are not used by pcre_exec().
  EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
-Line 1774 
 EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
+Line 2372 
 EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
         string_list() are provided for extracting captured substrings  as  new,
         separate,  zero-terminated strings. These functions identify substrings
         by number. The next section describes functions  for  extracting  named
-        substrings.  A  substring  that  contains  a  binary  zero is correctly
+        substrings.
-        extracted and has a further zero added on the end, but  the  result  is
-        not, of course, a C string.
+        A  substring that contains a binary zero is correctly extracted and has
+        a further zero added on the end, but the result is not, of course, a  C
+        string.   However,  you  can  process such a string by referring to the
+        length that is  returned  by  pcre_copy_substring()  and  pcre_get_sub-
+        string().  Unfortunately, the interface to pcre_get_substring_list() is
+        not adequate for handling strings containing binary zeros, because  the
+        end of the final string is not independently indicated.
         The  first  three  arguments  are the same for all three of these func-
         tions: subject is the subject string that has  just  been  successfully
-Line 1796 
 EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
+Line 2400 
 EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
         buffersize, while for pcre_get_substring() a new  block  of  memory  is
         obtained  via  pcre_malloc,  and its address is returned via stringptr.
         The yield of the function is the length of the  string,  not  including
-        the terminating zero, or one of
+        the terminating zero, or one of these error codes:
           PCRE_ERROR_NOMEMORY       (-6)
-Line 1812 
 EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
+Line 2416 
 EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
         single block of memory that 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
+        pointer.  The  yield  of  the function is zero if all went well, or the
+        error code
           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
+        When any of these functions encounter a substring that is unset,  which
-        can happen when capturing subpattern number n+1 matches  some  part  of
+        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
+        the subject, but subpattern n has not been used at all, they return  an
         empty string. This can be distinguished from a genuine zero-length sub-
-        string  by inspecting the appropriate offset in ovector, which is nega-
+        string by inspecting the appropriate offset in ovector, which is  nega-
         tive for unset substrings.
-        The two convenience functions pcre_free_substring() and  pcre_free_sub-
+        The  two convenience functions pcre_free_substring() and pcre_free_sub-
-        string_list()  can  be  used  to free the memory returned by a previous
+        string_list() can be used to free the memory  returned  by  a  previous
         call  of  pcre_get_substring()  or  pcre_get_substring_list(),  respec-
-        tively.  They  do  nothing  more  than  call the function pointed to by
+        tively. They do nothing more than  call  the  function  pointed  to  by
-        pcre_free, which of course could be called directly from a  C  program.
+        pcre_free,  which  of course could be called directly from a C program.
-        However,  PCRE is used in some situations where it is linked via a spe-
+        However, PCRE is used in some situations where it is linked via a  spe-
-        cial  interface  to  another  programming  language  which  cannot  use
+        cial   interface  to  another  programming  language  that  cannot  use
-        pcre_free  directly;  it is for these cases that the functions are pro-
+        pcre_free directly; it is for these cases that the functions  are  pro-
         vided.
-Line 1851 
 EXTRACTING CAPTURED SUBSTRINGS BY NAME
+Line 2456 
 EXTRACTING CAPTURED SUBSTRINGS BY NAME
              int stringcount, const char *stringname,
              const char **stringptr);
-        To extract a substring by name, you first have to find associated  num-
+        To  extract a substring by name, you first have to find associated num-
         ber.  For example, for this pattern
-          (a+)b(?P<xxx>\d+)...
+          (a+)b(?<xxx>\d+)...
-        the number of the subpattern called "xxx" is 2. You can find the number
+        the number of the subpattern called "xxx" is 2. If the name is known to
-        from the name by calling pcre_get_stringnumber(). The first argument is
+        be unique (PCRE_DUPNAMES was not set), you can find the number from the
-        the  compiled  pattern,  and  the  second is the name. The yield of the
+        name by calling pcre_get_stringnumber(). The first argument is the com-
-        function is the subpattern number, or  PCRE_ERROR_NOSUBSTRING  (-7)  if
+        piled pattern, and the second is the name. The yield of the function is
-        there is no subpattern of that name.
+        the subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if  there  is  no
+        subpattern of that name.
         Given the number, you can extract the substring directly, or use one of
         the functions described in the previous section. For convenience, there
-Line 1879 
 EXTRACTING CAPTURED SUBSTRINGS BY NAME
+Line 2485 
 EXTRACTING CAPTURED SUBSTRINGS BY NAME
         These functions call pcre_get_stringnumber(), and if it succeeds,  they
         then  call  pcre_copy_substring() or pcre_get_substring(), as appropri-
-        ate.
+        ate. NOTE: If PCRE_DUPNAMES is set and there are duplicate  names,  the
+        behaviour may not be what you want (see the next section).
+        Warning: If the pattern uses the (?| feature to set up multiple subpat-
+        terns with the same number, as described in the  section  on  duplicate
+        subpattern  numbers  in  the  pcrepattern page, you cannot use names to
+        distinguish the different subpatterns, because names are  not  included
+        in  the compiled code. The matching process uses only numbers. For this
+        reason, the use of different names for subpatterns of the  same  number
+        causes an error at compile time.
+ DUPLICATE SUBPATTERN NAMES
+        int pcre_get_stringtable_entries(const pcre *code,
+             const char *name, char **first, char **last);
+        When  a  pattern  is  compiled with the PCRE_DUPNAMES option, names for
+        subpatterns are not required to be unique. (Duplicate names are  always
+        allowed  for subpatterns with the same number, created by using the (?|
+        feature. Indeed, if such subpatterns are named, they  are  required  to
+        use the same names.)
+        Normally, patterns with duplicate names are such that in any one match,
+        only one of the named subpatterns participates. An example is shown  in
+        the pcrepattern documentation.
+        When    duplicates   are   present,   pcre_copy_named_substring()   and
+        pcre_get_named_substring() return the first substring corresponding  to
+        the  given  name  that  is set. If none are set, PCRE_ERROR_NOSUBSTRING
+        (-7) is returned; no  data  is  returned.  The  pcre_get_stringnumber()
+        function  returns one of the numbers that are associated with the name,
+        but it is not defined which it is.
+        If you want to get full details of all captured substrings for a  given
+        name,  you  must  use  the pcre_get_stringtable_entries() function. The
+        first argument is the compiled pattern, and the second is the name. The
+        third  and  fourth  are  pointers to variables which are updated by the
+        function. After it has run, they point to the first and last entries in
+        the  name-to-number  table  for  the  given  name.  The function itself
+        returns the length of each entry,  or  PCRE_ERROR_NOSUBSTRING  (-7)  if
+        there  are none. The format of the table is described above in the sec-
+        tion entitled Information about a  pattern.   Given  all  the  relevant
+        entries  for the name, you can extract each of their numbers, and hence
+        the captured data, if any.
  FINDING ALL POSSIBLE MATCHES
-Line 1908 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
+Line 2558 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
              int *workspace, int wscount);
         The  function  pcre_dfa_exec()  is  called  to  match  a subject string
-        against a compiled pattern, using a "DFA" matching algorithm. This  has
+        against a compiled pattern, using a matching algorithm that  scans  the
-        different  characteristics to the normal algorithm, and is not compati-
+        subject  string  just  once, and does not backtrack. This has different
-        ble with Perl. Some of the features of PCRE patterns are not supported.
+        characteristics to the normal algorithm, and  is  not  compatible  with
-        Nevertheless, there are times when this kind of matching can be useful.
+        Perl.  Some  of the features of PCRE patterns are not supported. Never-
-        For a discussion of the two matching algorithms, see  the  pcrematching
+        theless, there are times when this kind of matching can be useful.  For
-        documentation.
+        a  discussion  of  the  two matching algorithms, and a list of features
+        that pcre_dfa_exec() does not support, see the pcrematching  documenta-
+        tion.
         The  arguments  for  the  pcre_dfa_exec()  function are the same as for
         pcre_exec(), plus two extras. The ovector argument is used in a differ-
-Line 1925 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
+Line 2577 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
         workspace vector should contain at least 20 elements. It  is  used  for
         keeping  track  of  multiple  paths  through  the  pattern  tree.  More
         workspace will be needed for patterns and subjects where  there  are  a
-        lot of possible matches.
+        lot of potential matches.
-        Here is an example of a simple call to pcre_exec():
+        Here is an example of a simple call to pcre_dfa_exec():
           int rc;
           int ovector[10];
           int wspace[20];
-          rc = pcre_exec(
+          rc = pcre_dfa_exec(
             re,             /* result of pcre_compile() */
             NULL,           /* we didn't study the pattern */
             "some string",  /* the subject string */
-Line 1947 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
+Line 2599 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
     Option bits for pcre_dfa_exec()
         The  unused  bits  of  the options argument for pcre_dfa_exec() must be
-        zero. The only bits that may be  set  are  PCRE_ANCHORED,  PCRE_NOTBOL,
+        zero. The only bits  that  may  be  set  are  PCRE_ANCHORED,  PCRE_NEW-
-        PCRE_NOTEOL,     PCRE_NOTEMPTY,    PCRE_NO_UTF8_CHECK,    PCRE_PARTIAL,
+        LINE_xxx,        PCRE_NOTBOL,        PCRE_NOTEOL,        PCRE_NOTEMPTY,
-        PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All  but  the  last  three  of
+        PCRE_NOTEMPTY_ATSTART, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD, PCRE_PAR-
-        these  are  the  same  as  for pcre_exec(), so their description is not
+        TIAL_SOFT,  PCRE_DFA_SHORTEST,  and  PCRE_DFA_RESTART. All but the last
-        repeated here.
+        four of these are  exactly  the  same  as  for  pcre_exec(),  so  their
+        description is not repeated here.
-          PCRE_PARTIAL
+          PCRE_PARTIAL_HARD
-        This has the same general effect as it does for  pcre_exec(),  but  the
+          PCRE_PARTIAL_SOFT
-        details   are   slightly   different.  When  PCRE_PARTIAL  is  set  for
-        pcre_dfa_exec(), the return code PCRE_ERROR_NOMATCH is  converted  into
+        These  have the same general effect as they do for pcre_exec(), but the
-        PCRE_ERROR_PARTIAL  if  the  end  of the subject is reached, there have
+        details are slightly  different.  When  PCRE_PARTIAL_HARD  is  set  for
-        been no complete matches, but there is still at least one matching pos-
+        pcre_dfa_exec(),  it  returns PCRE_ERROR_PARTIAL if the end of the sub-
-        sibility.  The portion of the string that provided the partial match is
+        ject is reached and there is still at least  one  matching  possibility
-        set as the first matching string.
+        that requires additional characters. This happens even if some complete
+        matches have also been found. When PCRE_PARTIAL_SOFT is set, the return
+        code PCRE_ERROR_NOMATCH is converted into PCRE_ERROR_PARTIAL if the end
+        of the subject is reached, there have been  no  complete  matches,  but
+        there  is  still  at least one matching possibility. The portion of the
+        string that was inspected when the longest partial match was  found  is
+        set as the first matching string in both cases.
           PCRE_DFA_SHORTEST
-        Setting the PCRE_DFA_SHORTEST option causes the matching  algorithm  to
+        Setting  the  PCRE_DFA_SHORTEST option causes the matching algorithm to
-        stop  as  soon  as  it  has found one match. Because of the way the DFA
+        stop as soon as it has found one match. Because of the way the alterna-
-        algorithm works, this is necessarily the shortest possible match at the
+        tive  algorithm  works, this is necessarily the shortest possible match
-        first possible matching point in the subject string.
+        at the first possible matching point in the subject string.
           PCRE_DFA_RESTART
-        When  pcre_dfa_exec()  is  called  with  the  PCRE_PARTIAL  option, and
+        When pcre_dfa_exec() returns a partial match, it is possible to call it
-        returns a partial match, it is possible to call it  again,  with  addi-
+        again,  with  additional  subject characters, and have it continue with
-        tional  subject  characters,  and have it continue with the same match.
+        the same match. The PCRE_DFA_RESTART option requests this action;  when
-        The PCRE_DFA_RESTART option requests this action; when it is  set,  the
+        it  is  set,  the workspace and wscount options must reference the same
-        workspace  and wscount options must reference the same vector as before
+        vector as before because data about the match so far is  left  in  them
-        because data about the match so far is left in  them  after  a  partial
+        after a partial match. There is more discussion of this facility in the
-        match.  There  is  more  discussion of this facility in the pcrepartial
+        pcrepartial documentation.
-        documentation.
     Successful returns from pcre_dfa_exec()
-Line 2004 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
+Line 2661 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
         On success, the yield of the function is a number  greater  than  zero,
         which  is  the  number of matched substrings. The substrings themselves
         are returned in ovector. Each string uses two elements;  the  first  is
-        the  offset  to the start, and the second is the offset to the end. All
+        the  offset  to  the start, and the second is the offset to the end. In
-        the strings have the same start offset. (Space could have been saved by
+        fact, all the strings have the same start  offset.  (Space  could  have
-        giving  this only once, but it was decided to retain some compatibility
+        been  saved by giving this only once, but it was decided to retain some
-        with the way pcre_exec() returns data, even though the meaning  of  the
+        compatibility with the way pcre_exec() returns data,  even  though  the
-        strings is different.)
+        meaning of the strings is different.)
         The strings are returned in reverse order of length; that is, the long-
         est matching string is given first. If there were too many  matches  to
-Line 2030 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
+Line 2687 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
           PCRE_ERROR_DFA_UCOND      (-17)
-        This  return is given if pcre_dfa_exec() encounters a condition item in
+        This  return  is  given  if pcre_dfa_exec() encounters a condition item
-        a pattern that uses a back reference for the  condition.  This  is  not
+        that uses a back reference for the condition, or a test  for  recursion
-        supported.
+        in a specific group. These are not supported.
           PCRE_ERROR_DFA_UMLIMIT    (-18)
-Line 2052 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
+Line 2709 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
         This error is given if the output vector  is  not  large  enough.  This
         should be extremely rare, as a vector of size 1000 is used.
- Last updated: 16 May 2005
- Copyright (c) 1997-2005 University of Cambridge.
+ SEE ALSO
+        pcrebuild(3),  pcrecallout(3), pcrecpp(3)(3), pcrematching(3), pcrepar-
+        tial(3), pcreposix(3), pcreprecompile(3), pcresample(3), pcrestack(3).
+ AUTHOR
+        Philip Hazel
+        University Computing Service
+        Cambridge CB2 3QH, England.
+ REVISION
+        Last updated: 26 March 2010
+        Copyright (c) 1997-2010 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 2080 
 PCRE CALLOUTS
+Line 2753 
 PCRE CALLOUTS
         default value is zero.  For  example,  this  pattern  has  two  callout
         points:
-          (?C1)eabc(?C2)def
+          (?C1)abc(?C2)def
-        If  the  PCRE_AUTO_CALLOUT  option  bit  is  set when pcre_compile() is
+        If  the  PCRE_AUTO_CALLOUT  option  bit  is  set when pcre_compile() or
-        called, PCRE automatically  inserts  callouts,  all  with  number  255,
+        pcre_compile2() is called, PCRE  automatically  inserts  callouts,  all
-        before  each  item in the pattern. For example, if PCRE_AUTO_CALLOUT is
+        with  number  255,  before  each  item  in the pattern. For example, if
-        used with the pattern
+        PCRE_AUTO_CALLOUT is used with the pattern
           A(\d{2}|--)
-Line 2104 
 PCRE CALLOUTS
+Line 2777 
 PCRE CALLOUTS
  MISSING CALLOUTS
         You  should  be  aware  that,  because of optimizations in the way PCRE
-        matches patterns, callouts sometimes do not happen. For example, if the
+        matches patterns by default, callouts  sometimes  do  not  happen.  For
-        pattern is
+        example, if the pattern is
           ab(?C4)cd
-Line 2114 
 MISSING CALLOUTS
+Line 2787 
 MISSING CALLOUTS
         ever  start,  and  the  callout is never reached. However, with "abyd",
         though the result is still no match, the callout is obeyed.
+        If the pattern is studied, PCRE knows the minimum length of a  matching
+        string,  and will immediately give a "no match" return without actually
+        running a match if the subject is not long enough, or,  for  unanchored
+        patterns, if it has been scanned far enough.
+        You  can disable these optimizations by passing the PCRE_NO_START_OPTI-
+        MIZE option to pcre_exec() or  pcre_dfa_exec().  This  slows  down  the
+        matching  process,  but  does  ensure that callouts such as the example
+        above are obeyed.
  THE CALLOUT INTERFACE
-Line 2141 
 THE CALLOUT INTERFACE
+Line 2824 
 THE CALLOUT INTERFACE
         version number will change again in future  if  additional  fields  are
         added, but the intention is never to remove any of the existing fields.
-        The callout_number field contains the number of the  callout,  as  com-
+        The  callout_number  field  contains the number of the callout, as com-
-        piled  into  the pattern (that is, the number after ?C for manual call-
+        piled into the pattern (that is, the number after ?C for  manual  call-
         outs, and 255 for automatically generated callouts).
-        The offset_vector field is a pointer to the vector of offsets that  was
+        The  offset_vector field is a pointer to the vector of offsets that was
-        passed   by   the   caller  to  pcre_exec()  or  pcre_dfa_exec().  When
+        passed  by  the  caller  to  pcre_exec()   or   pcre_dfa_exec().   When
-        pcre_exec() is used, the contents can be inspected in order to  extract
+        pcre_exec()  is used, the contents can be inspected in order to extract
-        substrings  that  have  been  matched  so  far,  in the same way as for
+        substrings that have been matched so  far,  in  the  same  way  as  for
-        extracting substrings after a match has completed. For  pcre_dfa_exec()
+        extracting  substrings after a match has completed. For pcre_dfa_exec()
         this field is not useful.
         The subject and subject_length fields contain copies of the values that
         were passed to pcre_exec().
-        The start_match field contains the offset within the subject  at  which
+        The  start_match  field normally contains the offset within the subject
-        the  current match attempt started. If the pattern is not anchored, the
+        at which the current match attempt  started.  However,  if  the  escape
-        callout function may be called several times from the same point in the
+        sequence  \K has been encountered, this value is changed to reflect the
-        pattern for different starting points in the subject.
+        modified starting point. If the pattern is not  anchored,  the  callout
+        function may be called several times from the same point in the pattern
+        for different starting points in the subject.
-        The  current_position  field  contains the offset within the subject of
+        The current_position field contains the offset within  the  subject  of
         the current match pointer.
-        When the pcre_exec() function is used, the capture_top  field  contains
+        When  the  pcre_exec() function is used, the capture_top field contains
-        one  more than the number of the highest numbered captured substring so
+        one more than the number of the highest numbered captured substring  so
-        far. If no substrings have been captured, the value of  capture_top  is
+        far.  If  no substrings have been captured, the value of capture_top is
-        one.  This  is always the case when pcre_dfa_exec() is used, because it
+        one. This is always the case when pcre_dfa_exec() is used,  because  it
         does not support captured substrings.
-        The capture_last field contains the number of the  most  recently  cap-
+        The  capture_last  field  contains the number of the most recently cap-
-        tured  substring. If no substrings have been captured, its value is -1.
+        tured substring. If no substrings have been captured, its value is  -1.
         This is always the case when pcre_dfa_exec() is used.
-        The callout_data field contains a value that is passed  to  pcre_exec()
+        The  callout_data  field contains a value that is passed to pcre_exec()
-        or  pcre_dfa_exec() specifically so that it can be passed back in call-
+        or pcre_dfa_exec() specifically so that it can be passed back in  call-
-        outs. It is passed in the pcre_callout field  of  the  pcre_extra  data
+        outs.  It  is  passed  in the pcre_callout field of the pcre_extra data
-        structure.  If  no such data was passed, the value of callout_data in a
+        structure. If no such data was passed, the value of callout_data  in  a
-        pcre_callout block is NULL. There is a description  of  the  pcre_extra
+        pcre_callout  block  is  NULL. There is a description of the pcre_extra
         structure in the pcreapi documentation.
-        The  pattern_position field is present from version 1 of the pcre_call-
+        The pattern_position field is present from version 1 of the  pcre_call-
         out structure. It contains the offset to the next item to be matched in
         the pattern string.
-        The  next_item_length field is present from version 1 of the pcre_call-
+        The next_item_length field is present from version 1 of the  pcre_call-
         out structure. It contains the length of the next item to be matched in
-        the  pattern  string. When the callout immediately precedes an alterna-
+        the pattern string. When the callout immediately precedes  an  alterna-
-        tion bar, a closing parenthesis, or the end of the pattern, the  length
+        tion  bar, a closing parenthesis, or the end of the pattern, the length
-        is  zero.  When the callout precedes an opening parenthesis, the length
+        is zero. When the callout precedes an opening parenthesis,  the  length
         is that of the entire subpattern.
-        The pattern_position and next_item_length fields are intended  to  help
+        The  pattern_position  and next_item_length fields are intended to help
-        in  distinguishing between different automatic callouts, which all have
+        in distinguishing between different automatic callouts, which all  have
         the same callout number. However, they are set for all callouts.
  RETURN VALUES
-        The external callout function returns an integer to PCRE. If the  value
+        The  external callout function returns an integer to PCRE. If the value
-        is  zero,  matching  proceeds  as  normal. If the value is greater than
+        is zero, matching proceeds as normal. If  the  value  is  greater  than
-        zero, matching fails at the current point, but  the  testing  of  other
+        zero,  matching  fails  at  the current point, but the testing of other
         matching possibilities goes ahead, just as if a lookahead assertion had
-        failed. If the value is less than zero, the  match  is  abandoned,  and
+        failed.  If  the  value  is less than zero, the match is abandoned, and
-        pcre_exec() (or pcre_dfa_exec()) returns the negative value.
+        pcre_exec() or pcre_dfa_exec() returns the negative value.
-        Negative   values   should   normally   be   chosen  from  the  set  of
+        Negative  values  should  normally  be   chosen   from   the   set   of
         PCRE_ERROR_xxx values. In particular, PCRE_ERROR_NOMATCH forces a stan-
-        dard  "no  match"  failure.   The  error  number  PCRE_ERROR_CALLOUT is
+        dard "no  match"  failure.   The  error  number  PCRE_ERROR_CALLOUT  is
-        reserved for use by callout functions; it will never be  used  by  PCRE
+        reserved  for  use  by callout functions; it will never be used by PCRE
         itself.
- Last updated: 28 February 2005
- Copyright (c) 1997-2005 University of Cambridge.
+ AUTHOR
+        Philip Hazel
+        University Computing Service
+        Cambridge CB2 3QH, England.
+ REVISION
+        Last updated: 29 September 2009
+        Copyright (c) 1997-2009 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 2227 
 DIFFERENCES BETWEEN PCRE AND PERL
+Line 2922 
 DIFFERENCES BETWEEN PCRE AND PERL
         This  document describes the differences in the ways that PCRE and Perl
         handle regular expressions. The differences  described  here  are  with
-        respect to Perl 5.8.
+        respect to Perl 5.10.
-.  PCRE does not have full UTF-8 support. Details of what it does have
+.  PCRE has only a subset of Perl's UTF-8 and Unicode support. Details
-        are given in the section on UTF-8 support in the main pcre page.
+        of what it does have are given in the section on UTF-8 support  in  the
+        main pcre page.
 . PCRE does not allow repeat quantifiers on lookahead assertions. Perl
-        permits  them,  but they do not mean what you might think. For example,
+        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.
-.  Capturing  subpatterns  that occur inside negative lookahead asser-
+. Capturing subpatterns that occur inside  negative  lookahead  asser-
-        tions are counted, but their entries in the offsets  vector  are  never
+        tions  are  counted,  but their entries in the offsets vector are never
-        set.  Perl sets its numerical variables from any such patterns that are
+        set. Perl sets its numerical variables from any such patterns that  are
         matched before the assertion fails to match something (thereby succeed-
-        ing),  but  only  if the negative lookahead assertion contains just one
+        ing), but only if the negative lookahead assertion  contains  just  one
         branch.
-. Though binary zero characters are supported in the  subject  string,
+.  Though  binary zero characters are supported in the subject string,
         they are not allowed in a pattern string because it is passed as a nor-
         mal C string, terminated by zero. The escape sequence \0 can be used in
         the pattern to represent a binary zero.
-.  The  following Perl escape sequences are not supported: \l, \u, \L,
+. The following Perl escape sequences are not supported: \l,  \u,  \L,
         \U, and \N. In fact these are implemented by Perl's general string-han-
-        dling  and are not part of its pattern matching engine. If any of these
+        dling and are not part of its pattern matching engine. If any of  these
         are encountered by PCRE, an error is generated.
-. The Perl escape sequences \p, \P, and \X are supported only if  PCRE
+.  The Perl escape sequences \p, \P, and \X are supported only if PCRE
-        is  built  with Unicode character property support. The properties that
+        is built with Unicode character property support. The  properties  that
-        can be tested with \p and \P are limited to the general category  prop-
+        can  be tested with \p and \P are limited to the general category prop-
-        erties such as Lu and Nd.
+        erties such as Lu and Nd, script names such as Greek or  Han,  and  the
+        derived  properties  Any  and  L&. PCRE does support the Cs (surrogate)
+        property, which Perl does not; the  Perl  documentation  says  "Because
+        Perl hides the need for the user to understand the internal representa-
+        tion of Unicode characters, there is no need to implement the  somewhat
+        messy concept of surrogates."
 . PCRE does support the \Q...\E escape for quoting substrings. Charac-
         ters in between are treated as literals.  This  is  slightly  different
-Line 2275 
 DIFFERENCES BETWEEN PCRE AND PERL
+Line 2976 
 DIFFERENCES BETWEEN PCRE AND PERL
         The  \Q...\E  sequence  is recognized both inside and outside character
         classes.
-. Fairly obviously, PCRE does not support the (?{code}) and (?p{code})
+. Fairly obviously, PCRE does not support the (?{code}) and (??{code})
-        constructions.  However,  there is support for recursive patterns using
+        constructions.  However,  there is support for recursive patterns. This
-        the non-Perl items (?R),  (?number),  and  (?P>name).  Also,  the  PCRE
+        is not available in Perl 5.8, but it is in Perl 5.10.  Also,  the  PCRE
         "callout"  feature allows an external function to be called during pat-
         tern matching. See the pcrecallout documentation for details.
-. There are some differences that are concerned with the  settings  of
+. Subpatterns that are called  recursively  or  as  "subroutines"  are
+        always  treated  as  atomic  groups  in  PCRE. This is like Python, but
+        unlike Perl. There is a discussion of an example that explains this  in
+        more  detail  in  the section on recursion differences from Perl in the
+        pcrepattern page.
+. There are some differences that are concerned with the settings  of
         captured  strings  when  part  of  a  pattern is repeated. For example,
         matching "aba" against the  pattern  /^(a(b)?)+$/  in  Perl  leaves  $2
         unset, but in PCRE it is set to "b".
-. PCRE provides some extensions to the Perl regular expression facil-
+.  PCRE  does  support  Perl  5.10's  backtracking  verbs  (*ACCEPT),
-        ities:
+        (*FAIL), (*F), (*COMMIT), (*PRUNE), (*SKIP), and (*THEN), but  only  in
+        the forms without an argument. PCRE does not support (*MARK).
-        (a) Although lookbehind assertions must  match  fixed  length  strings,
-        each alternative branch of a lookbehind assertion can match a different
+.  PCRE's handling of duplicate subpattern numbers and duplicate sub-
-        length of string. Perl requires them all to have the same length.
+        pattern names is not as general as Perl's. This is a consequence of the
+        fact the PCRE works internally just with numbers, using an external ta-
+        ble to translate between numbers and names. In  particular,  a  pattern
+        such  as  (?|(?<a>A)|(?<b)B),  where the two capturing parentheses have
+        the same number but different names, is not supported,  and  causes  an
+        error  at compile time. If it were allowed, it would not be possible to
+        distinguish which parentheses matched, because both names map  to  cap-
+        turing subpattern number 1. To avoid this confusing situation, an error
+        is given at compile time.
+. PCRE provides some extensions to the Perl regular expression facil-
+        ities.   Perl  5.10  includes new features that are not in earlier ver-
+        sions of Perl, some of which (such as named parentheses) have  been  in
+        PCRE for some time. This list is with respect to Perl 5.10:
+        (a)  Although  lookbehind  assertions  in  PCRE must match fixed length
+        strings, each alternative branch of a lookbehind assertion can match  a
+        different  length  of  string.  Perl requires them all to have the same
+        length.
         (b) If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not set, the  $
         meta-character matches only at the very end of the string.
         (c) If PCRE_EXTRA is set, a backslash followed by a letter with no spe-
-        cial meaning is faulted.
+        cial meaning is faulted. Otherwise, like Perl, the backslash is quietly
+        ignored.  (Perl can be made to issue a warning.)
-        (d) If PCRE_UNGREEDY is set, the greediness of the  repetition  quanti-
+        (d)  If  PCRE_UNGREEDY is set, the greediness of the repetition quanti-
         fiers is inverted, that is, by default they are not greedy, but if fol-
         lowed by a question mark they are.
         (e) PCRE_ANCHORED can be used at matching time to force a pattern to be
         tried only at the first matching position in the subject string.
-        (f)  The PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and PCRE_NO_AUTO_CAP-
+        (f) The PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
-        TURE options for pcre_exec() have no Perl equivalents.
+        and  PCRE_NO_AUTO_CAPTURE  options for pcre_exec() have no Perl equiva-
+        lents.
-        (g) The (?R), (?number), and (?P>name) constructs allows for  recursive
+        (g) The \R escape sequence can be restricted to match only CR,  LF,  or
-        pattern  matching  (Perl  can  do  this using the (?p{code}) construct,
+        CRLF by the PCRE_BSR_ANYCRLF option.
-        which PCRE cannot support.)
-        (h) PCRE supports named capturing substrings, using the Python  syntax.
+        (h) The callout facility is PCRE-specific.
-        (i)  PCRE  supports  the  possessive quantifier "++" syntax, taken from
+        (i) The partial matching facility is PCRE-specific.
-        Sun's Java package.
-        (j) The (R) condition, for testing recursion, is a PCRE extension.
+        (j) Patterns compiled by PCRE can be saved and re-used at a later time,
+        even on different hosts that have the other endianness.
-        (k) The callout facility is PCRE-specific.
+        (k) The alternative matching function (pcre_dfa_exec())  matches  in  a
+        different way and is not Perl-compatible.
-        (l) The partial matching facility is PCRE-specific.
+        (l)  PCRE  recognizes some special sequences such as (*CR) at the start
+        of a pattern that set overall options that cannot be changed within the
+        pattern.
-        (m) Patterns compiled by PCRE can be saved and re-used at a later time,
-        even on different hosts that have the other endianness.
-        (n)  The  alternative  matching function (pcre_dfa_exec()) matches in a
+ AUTHOR
-        different way and is not Perl-compatible.
- Last updated: 28 February 2005
+        Philip Hazel
- Copyright (c) 1997-2005 University of Cambridge.
+        University Computing Service
+        Cambridge CB2 3QH, England.
+ REVISION
+        Last updated: 04 October 2009
+        Copyright (c) 1997-2009 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 2344 
 NAME
+Line 3077 
 NAME
  PCRE REGULAR EXPRESSION DETAILS
-        The  syntax  and semantics of the regular expressions supported by PCRE
+        The  syntax and semantics of the regular expressions that are supported
-        are described below. Regular expressions are also described in the Perl
+        by PCRE are described in detail below. There is a quick-reference  syn-
-        documentation  and  in  a  number  of books, some of which have copious
+        tax summary in the pcresyntax page. PCRE tries to match Perl syntax and
-        examples.  Jeffrey Friedl's "Mastering Regular Expressions",  published
+        semantics as closely as it can. PCRE  also  supports  some  alternative
-        by  O'Reilly, covers regular expressions in great detail. This descrip-
+        regular  expression  syntax (which does not conflict with the Perl syn-
-        tion of PCRE's regular expressions is intended as reference material.
+        tax) in order to provide some compatibility with regular expressions in
+        Python, .NET, and Oniguruma.
+        Perl's  regular expressions are described in its own documentation, and
+        regular expressions in general are covered in a number of  books,  some
+        of  which  have  copious  examples. Jeffrey Friedl's "Mastering Regular
+        Expressions", published by  O'Reilly,  covers  regular  expressions  in
+        great  detail.  This  description  of  PCRE's  regular  expressions  is
+        intended as reference material.
         The original operation of PCRE was on strings of  one-byte  characters.
         However,  there is now also support for UTF-8 character strings. To use
-        this, you must build PCRE to  include  UTF-8  support,  and  then  call
+        this, PCRE must be built to include UTF-8 support, and  you  must  call
-        pcre_compile()  with  the  PCRE_UTF8  option.  How this affects pattern
+        pcre_compile()  or  pcre_compile2() with the PCRE_UTF8 option. There is
-        matching is mentioned in several places below. There is also a  summary
+        also a special sequence that can be given at the start of a pattern:
-        of  UTF-8  features  in  the  section on UTF-8 support in the main pcre
-        page.
+          (*UTF8)
+        Starting a pattern with this sequence  is  equivalent  to  setting  the
+        PCRE_UTF8  option.  This  feature  is  not Perl-compatible. How setting
+        UTF-8 mode affects pattern matching  is  mentioned  in  several  places
+        below.  There  is  also  a  summary of UTF-8 features in the section on
+        UTF-8 support in the main pcre page.
         The remainder of this document discusses the  patterns  that  are  sup-
         ported  by  PCRE when its main matching function, pcre_exec(), is used.
         From  release  6.0,   PCRE   offers   a   second   matching   function,
         pcre_dfa_exec(),  which matches using a different algorithm that is not
-        Perl-compatible. The advantages and disadvantages  of  the  alternative
+        Perl-compatible. Some of the features discussed below are not available
-        function, and how it differs from the normal function, are discussed in
+        when  pcre_dfa_exec()  is used. The advantages and disadvantages of the
-        the pcrematching page.
+        alternative function, and how it differs from the normal function,  are
+        discussed in the pcrematching page.
-        A regular expression is a pattern that is  matched  against  a  subject
-        string  from  left  to right. Most characters stand for themselves in a
-        pattern, and match the corresponding characters in the  subject.  As  a
+ NEWLINE CONVENTIONS
+        PCRE  supports five different conventions for indicating line breaks in
+        strings: a single CR (carriage return) character, a  single  LF  (line-
+        feed) character, the two-character sequence CRLF, any of the three pre-
+        ceding, or any Unicode newline sequence. The pcreapi page  has  further
+        discussion  about newlines, and shows how to set the newline convention
+        in the options arguments for the compiling and matching functions.
+        It is also possible to specify a newline convention by starting a  pat-
+        tern string with one of the following five sequences:
+          (*CR)        carriage return
+          (*LF)        linefeed
+          (*CRLF)      carriage return, followed by linefeed
+          (*ANYCRLF)   any of the three above
+          (*ANY)       all Unicode newline sequences
+        These  override  the default and the options given to pcre_compile() or
+        pcre_compile2(). For example, on a Unix system where LF is the  default
+        newline sequence, the pattern
+          (*CR)a.b
+        changes the convention to CR. That pattern matches "a\nb" because LF is
+        no longer a newline. Note that these special settings,  which  are  not
+        Perl-compatible,  are  recognized  only at the very start of a pattern,
+        and that they must be in upper case.  If  more  than  one  of  them  is
+        present, the last one is used.
+        The  newline  convention  does  not  affect what the \R escape sequence
+        matches. By default, this is any Unicode  newline  sequence,  for  Perl
+        compatibility.  However, this can be changed; see the description of \R
+        in the section entitled "Newline sequences" below. A change of \R  set-
+        ting can be combined with a change of newline convention.
+ CHARACTERS AND METACHARACTERS
+        A  regular  expression  is  a pattern that is matched against a subject
+        string from left to right. Most characters stand for  themselves  in  a
+        pattern,  and  match  the corresponding characters in the subject. As a
         trivial example, the pattern
           The quick brown fox
         matches a portion of a subject string that is identical to itself. When
-        caseless matching is specified (the PCRE_CASELESS option), letters  are
+        caseless  matching is specified (the PCRE_CASELESS option), letters are
-        matched  independently  of case. In UTF-8 mode, PCRE always understands
+        matched independently of case. In UTF-8 mode, PCRE  always  understands
-        the concept of case for characters whose values are less than  128,  so
+        the  concept  of case for characters whose values are less than 128, so
-        caseless  matching  is always possible. For characters with higher val-
+        caseless matching is always possible. For characters with  higher  val-
-        ues, the concept of case is supported if PCRE is compiled with  Unicode
+        ues,  the concept of case is supported if PCRE is compiled with Unicode
-        property  support,  but  not  otherwise.   If  you want to use caseless
+        property support, but not otherwise.   If  you  want  to  use  caseless
-        matching for characters 128 and above, you must  ensure  that  PCRE  is
+        matching  for  characters  128  and above, you must ensure that PCRE is
         compiled with Unicode property support as well as with UTF-8 support.
-        The  power  of  regular  expressions  comes from the ability to include
+        The power of regular expressions comes  from  the  ability  to  include
-        alternatives and repetitions in the pattern. These are encoded  in  the
+        alternatives  and  repetitions in the pattern. These are encoded in the
         pattern by the use of metacharacters, which do not stand for themselves
         but instead are interpreted in some special way.
-        There are two different sets of metacharacters: those that  are  recog-
+        There  are  two different sets of metacharacters: those that are recog-
-        nized  anywhere in the pattern except within square brackets, and those
+        nized anywhere in the pattern except within square brackets, and  those
-        that are recognized in square brackets. Outside  square  brackets,  the
+        that  are  recognized  within square brackets. Outside square brackets,
-        metacharacters are as follows:
+        the metacharacters are as follows:
           \      general escape character with several uses
           ^      assert start of string (or line, in multiline mode)
-Line 2410 
 PCRE REGULAR EXPRESSION DETAILS
+Line 3198 
 PCRE REGULAR EXPRESSION DETAILS
                  also "possessive quantifier"
           {      start min/max quantifier
-        Part  of  a  pattern  that is in square brackets is called a "character
+        Part of a pattern that is in square brackets  is  called  a  "character
         class". In a character class the only metacharacters are:
           \      general escape character
-Line 2420 
 PCRE REGULAR EXPRESSION DETAILS
+Line 3208 
 PCRE REGULAR EXPRESSION DETAILS
                    syntax)
           ]      terminates the character class
-        The following sections describe the use of each of the  metacharacters.
+        The following sections describe the use of each of the metacharacters.
  BACKSLASH
-Line 2439 
 BACKSLASH
+Line 3227 
 BACKSLASH
         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.
+        # outside a character class and the next newline are ignored. An escap-
-        An escaping backslash can be used to include a whitespace or #  charac-
+        ing backslash can be used to include a whitespace  or  #  character  as
-        ter as part of the pattern.
+        part of the pattern.
         If  you  want  to remove the special meaning from a sequence of charac-
         ters, you can do so by putting them between \Q and \E. This is  differ-
-Line 2465 
 BACKSLASH
+Line 3253 
 BACKSLASH
         acters  in patterns in a visible manner. There is no restriction on the
         appearance of non-printing characters, apart from the binary zero  that
         terminates  a  pattern,  but  when  a pattern is being prepared by text
-        editing, it is usually easier  to  use  one  of  the  following  escape
+        editing, it is  often  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)
+          \n        linefeed (hex 0A)
           \r        carriage return (hex 0D)
           \t        tab (hex 09)
-          \ddd      character with octal code ddd, or backreference
+          \ddd      character with octal code ddd, or back reference
           \xhh      character with hex code hh
-          \x{hhh..} character with hex code hhh... (UTF-8 mode only)
+          \x{hhh..} character with hex code hhh..
         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
-Line 2485 
 BACKSLASH
+Line 3273 
 BACKSLASH
         becomes hex 7B.
         After \x, from zero to two hexadecimal digits are read (letters can  be
-        in  upper or lower case). In UTF-8 mode, any number of hexadecimal dig-
+        in  upper  or  lower case). Any number of hexadecimal digits may appear
-        its may appear between \x{ and }, but the value of the  character  code
+        between \x{ and }, but the value of the character  code  must  be  less
-        must  be  less  than  2**31  (that is, the maximum hexadecimal value is
+        than 256 in non-UTF-8 mode, and less than 2**31 in UTF-8 mode. That is,
-FFFFFFF). If characters other than hexadecimal digits  appear  between
+        the maximum value in hexadecimal is 7FFFFFFF. Note that this is  bigger
-        \x{  and }, or if there is no terminating }, this form of escape is not
+        than the largest Unicode code point, which is 10FFFF.
-        recognized. Instead, the initial \x will  be  interpreted  as  a  basic
-        hexadecimal  escape, with no following digits, giving a character whose
+        If  characters  other than hexadecimal digits appear between \x{ and },
-        value is zero.
+        or if there is no terminating }, this form of escape is not recognized.
+        Instead,  the  initial  \x  will  be interpreted as a basic hexadecimal
+        escape, with no following digits, giving a  character  whose  value  is
+        zero.
         Characters whose value is less than 256 can be defined by either of the
-        two  syntaxes for \x when PCRE is in UTF-8 mode. There is no difference
+        two syntaxes for \x. There is no difference in the way  they  are  han-
-        in the way they are handled. For example, \xdc is exactly the  same  as
+        dled. For example, \xdc is exactly the same as \x{dc}.
-        \x{dc}.
+        After  \0  up  to two further octal digits are read. If there are fewer
-        After  \0  up  to  two further octal digits are read. In both cases, if
+        than two digits, just  those  that  are  present  are  used.  Thus  the
-        there are fewer than two digits, just those that are present are  used.
+        sequence \0\x\07 specifies two binary zeros followed by a BEL character
-        Thus  the sequence \0\x\07 specifies two binary zeros followed by a BEL
+        (code value 7). Make sure you supply two digits after the initial  zero
-        character (code value 7). Make sure you supply  two  digits  after  the
+        if the pattern character that follows is itself an octal digit.
-        initial  zero  if the pattern character that follows is itself an octal
-        digit.
         The handling of a backslash followed by a digit other than 0 is compli-
         cated.  Outside a character class, PCRE reads it and any following dig-
-        its as a decimal number. If the number is less than  10,  or  if  there
+        its  as  a  decimal  number. If the number is less than 10, or if there
         have been at least that many previous capturing left parentheses in the
-        expression, the entire  sequence  is  taken  as  a  back  reference.  A
+        expression,  the  entire  sequence  is  taken  as  a  back reference. A
-        description  of how this works is given later, following the discussion
+        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
+        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
+        and there have not been that many capturing subpatterns, PCRE  re-reads
-        up to three octal digits following the backslash, and generates a  sin-
+        up to three octal digits following the backslash, and uses them to gen-
-        gle byte from the least significant 8 bits of the value. Any subsequent
+        erate a data character. Any subsequent digits stand for themselves.  In
-        digits stand for themselves.  For example:
+        non-UTF-8  mode,  the  value  of a character specified in octal must be
+        less than \400. In UTF-8 mode, values up to  \777  are  permitted.  For
+        example:
           \040   is another way of writing a space
           \40    is the same, provided there are fewer than 40
-Line 2535 
 BACKSLASH
+Line 3326 
 BACKSLASH
           \81    is either a back reference, or a binary zero
                     followed by the two characters "8" and "1"
-        Note that octal values of 100 or greater must not be  introduced  by  a
+        Note  that  octal  values of 100 or greater must not be introduced by a
         leading zero, because no more than three octal digits are ever read.
-        All  the  sequences  that  define a single byte value or a single UTF-8
+        All the sequences that define a single character value can be used both
-        character (in UTF-8 mode) can be used both inside and outside character
+        inside  and  outside character classes. In addition, inside a character
-        classes.  In  addition,  inside  a  character class, the sequence \b is
+        class, the sequence \b is interpreted as the backspace  character  (hex
-        interpreted as the backspace character (hex 08), and the sequence \X is
+),  and the sequences \R and \X are interpreted as the characters "R"
-        interpreted  as  the  character  "X".  Outside a character class, these
+        and "X", respectively. Outside a character class, these sequences  have
-        sequences have different meanings (see below).
+        different meanings (see below).
+    Absolute and relative back references
+        The  sequence  \g followed by an unsigned or a negative number, option-
+        ally enclosed in braces, is an absolute or relative back  reference.  A
+        named back reference can be coded as \g{name}. Back references are dis-
+        cussed later, following the discussion of parenthesized subpatterns.
+    Absolute and relative subroutine calls
+        For compatibility with Oniguruma, the non-Perl syntax \g followed by  a
+        name or a number enclosed either in angle brackets or single quotes, is
+        an alternative syntax for referencing a subpattern as  a  "subroutine".
+        Details  are  discussed  later.   Note  that  \g{...} (Perl syntax) and
+        \g<...> (Oniguruma syntax) are not synonymous. The  former  is  a  back
+        reference; the latter is a subroutine call.
     Generic character types
-        The third use of backslash is for specifying generic  character  types.
+        Another use of backslash is for specifying generic character types. The
-        The following are always recognized:
+        following are always recognized:
           \d     any decimal digit
           \D     any character that is not a decimal digit
+          \h     any horizontal whitespace character
+          \H     any character that is not a horizontal whitespace character
           \s     any whitespace character
           \S     any character that is not a whitespace character
+          \v     any vertical whitespace character
+          \V     any character that is not a vertical 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,
+        into  two disjoint sets. Any given character matches one, and only one,
         of each pair.
         These character type sequences can appear both inside and outside char-
-        acter classes. They each match one character of the  appropriate  type.
+        acter  classes.  They each match one character of the appropriate type.
-        If  the current matching point is at the end of the subject string, all
+        If the current matching point is at the end of the subject string,  all
         of them fail, since there is no character to match.
-        For compatibility with Perl, \s does not match the VT  character  (code
+        For  compatibility  with Perl, \s does not match the VT character (code
-).   This makes it different from the the POSIX "space" class. The \s
+).  This makes it different from the the POSIX "space" class. The  \s
-        characters are HT (9), LF (10), FF (12), CR (13), and space (32).
+        characters  are  HT  (9), LF (10), FF (12), CR (13), and space (32). If
+        "use locale;" is included in a Perl script, \s may match the VT charac-
+        ter. In PCRE, it never does.
+        In  UTF-8 mode, characters with values greater than 128 never match \d,
+        \s, or \w, and always match \D, \S, and \W. This is true even when Uni-
+        code  character  property  support is available. These sequences retain
+        their original meanings from before UTF-8 support was available, mainly
+        for  efficiency  reasons. Note that this also affects \b, because it is
+        defined in terms of \w and \W.
+        The sequences \h, \H, \v, and \V are Perl 5.10 features. In contrast to
+        the  other  sequences, these do match certain high-valued codepoints in
+        UTF-8 mode.  The horizontal space characters are:
+          U+0009     Horizontal tab
+          U+0020     Space
+          U+00A0     Non-break space
+          U+1680     Ogham space mark
+          U+180E     Mongolian vowel separator
+          U+2000     En quad
+          U+2001     Em quad
+          U+2002     En space
+          U+2003     Em space
+          U+2004     Three-per-em space
+          U+2005     Four-per-em space
+          U+2006     Six-per-em space
+          U+2007     Figure space
+          U+2008     Punctuation space
+          U+2009     Thin space
+          U+200A     Hair space
+          U+202F     Narrow no-break space
+          U+205F     Medium mathematical space
+          U+3000     Ideographic space
+        The vertical space characters are:
+          U+000A     Linefeed
+          U+000B     Vertical tab
+          U+000C     Formfeed
+          U+000D     Carriage return
+          U+0085     Next line
+          U+2028     Line separator
+          U+2029     Paragraph separator
         A "word" character is an underscore or any character less than 256 that
         is  a  letter  or  digit.  The definition of letters and digits is con-
         trolled by PCRE's low-valued character tables, and may vary if  locale-
         specific  matching is taking place (see "Locale support" in the pcreapi
-        page). For example, in the  "fr_FR"  (French)  locale,  some  character
+        page). For example, in a French locale such  as  "fr_FR"  in  Unix-like
-        codes  greater  than  128  are used for accented letters, and these are
+        systems,  or "french" in Windows, some character codes greater than 128
-        matched by \w.
+        are used for accented letters, and these are matched by \w. The use  of
+        locales with Unicode is discouraged.
+    Newline sequences
+        Outside  a  character class, by default, the escape sequence \R matches
+        any Unicode newline sequence. This is a Perl 5.10 feature. In non-UTF-8
+        mode \R is equivalent to the following:
+          (?>\r\n|\n|\x0b|\f|\r|\x85)
+        This  is  an  example  of an "atomic group", details of which are given
+        below.  This particular group matches either the two-character sequence
+        CR  followed  by  LF,  or  one  of  the single characters LF (linefeed,
+        U+000A), VT (vertical tab, U+000B), FF (formfeed, U+000C), CR (carriage
+        return, U+000D), or NEL (next line, U+0085). The two-character sequence
+        is treated as a single unit that cannot be split.
+        In UTF-8 mode, two additional characters whose codepoints  are  greater
+        than 255 are added: LS (line separator, U+2028) and PS (paragraph sepa-
+        rator, U+2029).  Unicode character property support is not  needed  for
+        these characters to be recognized.
+        It is possible to restrict \R to match only CR, LF, or CRLF (instead of
+        the complete set  of  Unicode  line  endings)  by  setting  the  option
+        PCRE_BSR_ANYCRLF either at compile time or when the pattern is matched.
+        (BSR is an abbrevation for "backslash R".) This can be made the default
+        when  PCRE  is  built;  if this is the case, the other behaviour can be
+        requested via the PCRE_BSR_UNICODE option.   It  is  also  possible  to
+        specify  these  settings  by  starting a pattern string with one of the
+        following sequences:
+          (*BSR_ANYCRLF)   CR, LF, or CRLF only
+          (*BSR_UNICODE)   any Unicode newline sequence
+        These override the default and the options given to  pcre_compile()  or
+        pcre_compile2(),  but  they  can  be  overridden  by  options  given to
+        pcre_exec() or pcre_dfa_exec(). Note that these special settings, which
+        are  not  Perl-compatible,  are  recognized only at the very start of a
+        pattern, and that they must be in upper case. If more than one of  them
+        is present, the last one is used. They can be combined with a change of
+        newline convention, for example, a pattern can start with:
-        In UTF-8 mode, characters with values greater than 128 never match  \d,
+          (*ANY)(*BSR_ANYCRLF)
-        \s, or \w, and always match \D, \S, and \W. This is true even when Uni-
-        code character property support is available.
+        Inside a character class, \R matches the letter "R".
     Unicode character properties
         When PCRE is built with Unicode character property support, three addi-
-        tional  escape sequences to match generic character types are available
+        tional  escape sequences that match characters with specific properties
-        when UTF-8 mode is selected. They are:
+        are available.  When not in UTF-8 mode, these sequences are  of  course
+        limited  to  testing characters whose codepoints are less than 256, but
-         \p{xx}   a character with the xx property
+        they do work in this mode.  The extra escape sequences are:
-         \P{xx}   a character without the xx property
-         \X       an extended Unicode sequence
+          \p{xx}   a character with the xx property
+          \P{xx}   a character without the xx property
+          \X       an extended Unicode sequence