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

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-revision 155 by ph10,
Tue Apr 24 13:36:11 2007 UTC
+revision 261 by ph10,
Fri Sep 21 08:37:48 2007 UTC
 Line 45 
 INTRODUCTION
         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
+        Some  features  of  PCRE can be included, excluded, or changed when the
-        library  is  built.  The pcre_config() function makes it possible for a
+        library is built. The pcre_config() function makes it  possible  for  a
-        client to discover which features are  available.  The  features  them-
+        client  to  discover  which  features are available. The features them-
-        selves  are described in the pcrebuild page. Documentation about build-
+        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 file
         in the source distribution.
-        The  library  contains  a number of undocumented internal functions and
+        The library contains a number of undocumented  internal  functions  and
-        data tables that are used by more than one  of  the  exported  external
+        data  tables  that  are  used by more than one of the exported external
-        functions,  but  which  are  not  intended for use by external callers.
+        functions, but which are not intended  for  use  by  external  callers.
-        Their names all begin with "_pcre_", which hopefully will  not  provoke
+        Their  names  all begin with "_pcre_", which hopefully will not provoke
         any name clashes. In some environments, it is possible to control which
-        external symbols are exported when a shared library is  built,  and  in
+        external  symbols  are  exported when a shared library is built, and in
         these cases the undocumented symbols are not exported.
  USER DOCUMENTATION
-        The  user  documentation  for PCRE comprises a number of different sec-
+        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
+        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.
+        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 are concatenated, for ease
         of searching. The sections are as follows:
           pcre              this document
-Line 83 
 USER DOCUMENTATION
+Line 84 
 USER DOCUMENTATION
           pcrepartial       details of the partial matching facility
           pcrepattern       syntax and semantics of supported
                               regular expressions
+          pcresyntax        quick syntax reference
           pcreperform       discussion of performance issues
           pcreposix         the POSIX-compatible C API
           pcreprecompile    details of saving and re-using precompiled patterns
-Line 90 
 USER DOCUMENTATION
+Line 92 
 USER DOCUMENTATION
           pcrestack         discussion of stack usage
           pcretest          description of the pcretest testing command
-        In addition, in the "man" and HTML formats, there is a short  page  for
+        In  addition,  in the "man" and HTML formats, there is a short page for
         each C library function, listing its arguments and results.
  LIMITATIONS
-        There  are some size limitations in PCRE but it is hoped that they will
+        There are some size limitations in PCRE but it is hoped that they  will
         never in practice be relevant.
-        The maximum length of a compiled pattern is 65539 (sic) bytes  if  PCRE
+        The  maximum  length of a compiled pattern is 65539 (sic) bytes if PCRE
         is compiled with the default internal linkage size of 2. If you want to
-        process regular expressions that are truly enormous,  you  can  compile
+        process  regular  expressions  that are truly enormous, you can compile
-        PCRE  with  an  internal linkage size of 3 or 4 (see the README file in
+        PCRE with an internal linkage size of 3 or 4 (see the  README  file  in
-        the source distribution and the pcrebuild documentation  for  details).
+        the  source  distribution and the pcrebuild documentation for details).
-        In  these  cases the limit is substantially larger.  However, the speed
+        In these cases the limit is substantially larger.  However,  the  speed
         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  compiled  length  of  subpattern  with an explicit repeat count is
-bytes. The maximum number of capturing subpatterns is 65535.
         There is no limit to the number of parenthesized subpatterns, but there
         can be no more than 65535 capturing subpatterns.
 Line 117 
 LIMITATIONS
         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
+        The  maximum  length of a subject string is the largest positive number
-        that  an integer variable can hold. However, when using the traditional
+        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
+        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
-        From  release  3.3,  PCRE  has  had  some support for character strings
+        From release 3.3, PCRE has  had  some  support  for  character  strings
-        encoded in the UTF-8 format. For release 4.0 this was greatly  extended
+        encoded  in the UTF-8 format. For release 4.0 this was greatly extended
-        to  cover  most common requirements, and in release 5.0 additional sup-
+        to cover most common requirements, and in release 5.0  additional  sup-
         port for Unicode general category properties was added.
-        In order process UTF-8 strings, you must build PCRE  to  include  UTF-8
+        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()
+        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. When you do this, both the pattern and
-        any  subject  strings  that are matched against it are treated as UTF-8
+        any subject strings that are matched against it are  treated  as  UTF-8
         strings instead of just strings of bytes.
-        If you compile PCRE with UTF-8 support, but do not use it at run  time,
+        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
+        the library will be a bit bigger, but the additional run time  overhead
         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, the Unicode script names such as Arabic or Han,
+        for a decimal number, the Unicode script names such as Arabic  or  Han,
-        and the derived properties Any and L&. A full  list  is  given  in  the
+        and  the  derived  properties  Any  and L&. A full list is given in the
         pcrepattern documentation. Only the short names for properties are sup-
-        ported. For example, \p{L} matches a letter. Its Perl synonym,  \p{Let-
+        ported.  For example, \p{L} matches a letter. Its Perl synonym, \p{Let-
-        ter},  is  not  supported.   Furthermore,  in Perl, many properties may
+        ter}, is not supported.  Furthermore,  in  Perl,  many  properties  may
-        optionally be prefixed by "Is", for compatibility with Perl  5.6.  PCRE
+        optionally  be  prefixed by "Is", for compatibility with Perl 5.6. PCRE
         does not support this.
-        The following comments apply when PCRE is running in UTF-8 mode:
+    Validity of UTF-8 strings
+        When you set the PCRE_UTF8 flag, the strings  passed  as  patterns  and
+        subjects are (by default) checked for validity on entry to the relevant
+        functions. From release 7.3 of PCRE, the check is according  the  rules
+        of  RFC  3629, which are themselves derived from the Unicode specifica-
+        tion. Earlier releases of PCRE followed the rules of  RFC  2279,  which
+        allows  the  full range of 31-bit values (0 to 0x7FFFFFFF). The current
+        check allows only values in the range U+0 to U+10FFFF, excluding U+D800
+        to U+DFFF.
+        The  excluded  code  points are the "Low Surrogate Area" of Unicode, of
+        which the Unicode Standard says this: "The Low Surrogate Area does  not
+        contain  any  character  assignments,  consequently  no  character code
+        charts or namelists are provided for this area. Surrogates are reserved
+        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.
-.  When you set the PCRE_UTF8 flag, the strings passed as patterns and
+    General comments about UTF-8 mode
-        subjects are checked for validity on entry to the  relevant  functions.
-        If an invalid UTF-8 string is passed, an error return is given. In some
-        situations, you may already know  that  your  strings  are  valid,  and
-        therefore want to skip these checks in order to improve performance. If
-        you set the PCRE_NO_UTF8_CHECK flag at compile time  or  at  run  time,
-        PCRE  assumes  that  the  pattern or subject it is given (respectively)
-        contains only valid UTF-8 codes. In this case, it does not diagnose  an
-        invalid  UTF-8 string. If you pass an invalid UTF-8 string to PCRE when
-        PCRE_NO_UTF8_CHECK is set, the results are undefined. Your program  may
-        crash.
-.  An  unbraced  hexadecimal  escape sequence (such as \xb3) matches a
+. An unbraced hexadecimal escape sequence (such  as  \xb3)  matches  a
         two-byte UTF-8 character if the value is greater than 127.
-. Octal numbers up to \777 are recognized, and  match  two-byte  UTF-8
+.  Octal  numbers  up to \777 are recognized, and match two-byte UTF-8
         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}.
-. Similarly, characters that match the POSIX named  character  classes
+.  Similarly,  characters that match the POSIX named character classes
         are all low-valued characters.
-.  Case-insensitive  matching  applies only to characters whose values
+. However, the Perl 5.10 horizontal and vertical  whitespace  matching
-        are less than 128, unless PCRE is built with Unicode property  support.
+        escapes (\h, \H, \v, and \V) do match all the appropriate Unicode char-
-        Even  when  Unicode  property support is available, PCRE still uses its
+        acters.
-        own character tables when checking the case of  low-valued  characters,
-        so  as not to degrade performance.  The Unicode property information is
+. 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. 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
+        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-
+        small number of many-to-one mappings in Unicode;  these  are  not  sup-
         ported by PCRE.
-Line 215 
 AUTHOR
+Line 249 
 AUTHOR
         University Computing Service
         Cambridge CB2 3QH, England.
-        Putting an actual email address here seems to have been a spam  magnet,
+        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 two initials,
+        so I've taken it away. If you want to email me, use  my  two  initials,
         followed by the two digits 10, at the domain cam.ac.uk.
  REVISION
-        Last updated: 18 April 2007
+        Last updated: 09 August 2007
         Copyright (c) 1997-2007 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 237 
 NAME
+Line 271 
 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  CMakeSetup  if  you  are  using
+        CMake instead of configure to build PCRE.
+        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 include  descriptions  of  options  whose  names
+        The  following  sections  include  descriptions  of options whose names
         begin with --enable or --disable. These settings specify changes to the
-        defaults for the configure command. Because of the way  that  configure
+        defaults  for  the configure command. Because of the way that configure
-        works,  --enable  and --disable always come in pairs, so the complemen-
+        works, --enable and --disable always come in pairs, so  the  complemen-
-        tary option always exists as well, but as it specifies the default,  it
+        tary  option always exists as well, but as it specifies the default, it
         is not described.
-Line 270 
 UTF-8 SUPPORT
+Line 309 
 UTF-8 SUPPORT
           --enable-utf8
-        to  the  configure  command.  Of  itself, this does not make PCRE treat
+        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
+        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()
+        have have to set the PCRE_UTF8 option when you call the  pcre_compile()
         function.
  UNICODE CHARACTER PROPERTY SUPPORT
-        UTF-8 support allows PCRE to process character values greater than  255
+        UTF-8  support allows PCRE to process character values greater than 255
-        in  the  strings that it handles. On its own, however, it does not pro-
+        in the strings that it handles. On its own, however, it does  not  pro-
         vide any facilities for accessing the properties of such characters. If
-        you  want  to  be able to use the pattern escapes \P, \p, and \X, which
+        you want to be able to use the pattern escapes \P, \p,  and  \X,  which
         refer to Unicode character properties, you must add
           --enable-unicode-properties
-        to the configure command. This implies UTF-8 support, even if you  have
+        to  the configure command. This implies UTF-8 support, even if you have
         not explicitly requested it.
-        Including  Unicode  property  support  adds around 30K of tables to the
+        Including Unicode property support adds around 30K  of  tables  to  the
-        PCRE library. Only the general category properties such as  Lu  and  Nd
+        PCRE  library.  Only  the general category properties such as Lu and Nd
         are supported. Details are given in the pcrepattern documentation.
  CODE VALUE OF NEWLINE
-        By  default,  PCRE interprets character 10 (linefeed, LF) as indicating
+        By default, PCRE interprets character 10 (linefeed, LF)  as  indicating
-        the end of a line. This is the normal newline  character  on  Unix-like
+        the  end  of  a line. This is the normal newline character on Unix-like
         systems. You can compile PCRE to use character 13 (carriage return, CR)
         instead, by adding
           --enable-newline-is-cr
-        to the  configure  command.  There  is  also  a  --enable-newline-is-lf
+        to  the  configure  command.  There  is  also  a --enable-newline-is-lf
         option, which explicitly specifies linefeed as the newline character.
         Alternatively, you can specify that line endings are to be indicated by
-Line 315 
 CODE VALUE OF NEWLINE
+Line 354 
 CODE VALUE OF NEWLINE
           --enable-newline-is-anycrlf
-        which causes PCRE to recognize any of the three sequences  CR,  LF,  or
+        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
+        Whatever  line  ending convention is selected when PCRE is built can be
-        overridden  when  the library functions are called. At build time it is
+        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 342 
 BUILDING SHARED AND STATIC LIBRARIES
+Line 394 
 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 357 
 POSIX MALLOC USAGE
+Line 409 
 POSIX MALLOC USAGE
  HANDLING VERY LARGE PATTERNS
-        Within  a  compiled  pattern,  offset values are used to point from one
+        Within a compiled pattern, offset values are used  to  point  from  one
-        part to another (for example, from an opening parenthesis to an  alter-
+        part  to another (for example, from an opening parenthesis to an alter-
-        nation  metacharacter).  By default, two-byte values are used for these
+        nation metacharacter). By default, two-byte values are used  for  these
-        offsets, leading to a maximum size for a  compiled  pattern  of  around
+        offsets,  leading  to  a  maximum size for a compiled pattern of around
-K.  This  is sufficient to handle all but the most gigantic patterns.
+K. This is sufficient to handle all but the most  gigantic  patterns.
-        Nevertheless, some people do want to process enormous patterns,  so  it
+        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
+        is possible to compile PCRE to use three-byte or four-byte  offsets  by
         adding a setting such as
           --with-link-size=3
-        to the configure command. The value given must be 2,  3,  or  4.  Using
+        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
+        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().
+        ing by making recursive calls to an internal function  called  match().
-        In environments where the size of the stack is limited,  this  can  se-
+        In  environments  where  the size of the stack is limited, this can se-
-        verely  limit  PCRE's operation. (The Unix environment does not usually
+        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-
+        the maximum stack size.  There is a discussion in the  pcrestack  docu-
-        mentation.) An alternative approach to recursion that uses memory  from
+        mentation.)  An alternative approach to recursion that uses memory from
-        the  heap  to remember data, instead of using recursive function calls,
+        the heap to remember data, instead of using recursive  function  calls,
-        has been implemented to work round the problem of limited  stack  size.
+        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
+        to the configure command. With this configuration, PCRE  will  use  the
-        pcre_stack_malloc and pcre_stack_free variables to call memory  manage-
+        pcre_stack_malloc  and pcre_stack_free variables to call memory manage-
-        ment  functions.  Separate  functions are provided because the usage is
+        ment functions. By default these point to malloc() and free(), but  you
-        very predictable: the block sizes requested are always  the  same,  and
+        can replace the pointers so that your own functions are used.
-        the  blocks  are always freed in reverse order. A calling program might
-        be able to implement optimized functions that perform better  than  the
+        Separate  functions  are  provided  rather  than  using pcre_malloc and
-        standard  malloc()  and  free()  functions.  PCRE  runs noticeably more
+        pcre_free because the  usage  is  very  predictable:  the  block  sizes
-        slowly when built in this way. This option affects only the pcre_exec()
+        requested  are  always  the  same,  and  the blocks are always freed in
-        function; it is not relevant for the the pcre_dfa_exec() function.
+        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  the  the
+        pcre_dfa_exec() function.
  LIMITING PCRE RESOURCE USAGE
-        Internally,  PCRE has a function called match(), which it calls repeat-
+        Internally, PCRE has a function called match(), which it calls  repeat-
-        edly  (sometimes  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
+        pcre_exec() function. By controlling the maximum number of  times  this
-        function may be called during a single matching operation, a limit  can
+        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
+        be placed on the resources used by a single call  to  pcre_exec().  The
-        limit can be changed at run time, as described in the pcreapi  documen-
+        limit  can be changed at run time, as described in the pcreapi documen-
-        tation.  The default is 10 million, but this can be changed by adding a
+        tation. The default is 10 million, but this can be changed by adding  a
         setting such as
           --with-match-limit=500000
-        to  the  configure  command.  This  setting  has  no  effect   on   the
+        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
+        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-
+        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
+        it defaults to the value that  is  set  for  --with-match-limit,  which
-        imposes no additional constraints. However, you can set a  lower  limit
+        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
+        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
+        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
+        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
+        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.
+        to the configure command, the distributed tables are  no  longer  used.
-        Instead, a program called dftables is compiled and  run.  This  outputs
+        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 are cross compiling, because dftables is run on the local host.  If
-        you need to create alternative tables when cross  compiling,  you  will
+        you  need  to  create alternative tables when cross compiling, you will
         have to do so "by hand".)
  USING EBCDIC CODE
-        PCRE  assumes  by  default that it will run in an environment where the
+        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).
+        character  code  is  ASCII  (or Unicode, which is a superset of ASCII).
-        PCRE  can,  however,  be  compiled  to  run in an EBCDIC environment by
+        This is the case for most computer operating systems.  PCRE  can,  how-
-        adding
+        ever, be compiled to run in an EBCDIC environment by adding
           --enable-ebcdic
         to the configure command. This setting implies --enable-rebuild-charta-
-        bles.
+        bles. You should only use it if you know that  you  are  in  an  EBCDIC
+        environment (for example, an IBM mainframe operating system).
  SEE ALSO
-Line 474 
 AUTHOR
+Line 531 
 AUTHOR
  REVISION
-        Last updated: 16 April 2007
+        Last updated: 21 September 2007
         Copyright (c) 1997-2007 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 610 
 THE ALTERNATIVE MATCHING ALGORITHM
+Line 667 
 THE ALTERNATIVE MATCHING ALGORITHM
         ence  as  the  condition or test for a specific group recursion are not
         supported.
-. Callouts are supported, but the value of the  capture_top  field  is
+. 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
         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  alterna-
+        single  byte, even in UTF-8 mode, is not supported because the alterna-
-        tive  algorithm  moves  through  the  subject string one character at a
+        tive algorithm moves through the subject  string  one  character  at  a
         time, for all active paths through the tree.
+.  None  of  the  backtracking control verbs such as (*PRUNE) are sup-
+        ported.
  ADVANTAGES OF THE ALTERNATIVE ALGORITHM
-Line 664 
 AUTHOR
+Line 729 
 AUTHOR
  REVISION
-        Last updated: 06 March 2007
+        Last updated: 08 August 2007
         Copyright (c) 1997-2007 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 861 
 NEWLINES
+Line 926 
 NEWLINES
         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
+        acter  or pair of characters that indicate a line break". The choice of
-        newline  convention  affects  the  handling of the dot, circumflex, and
+        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-
+        CRLF is a recognized line ending sequence, the match position  advance-
-        ment for a non-anchored pattern. The choice of newline convention  does
+        ment for a non-anchored pattern. There is more detail about this in the
-        not affect the interpretation of the \n or \r escape sequences.
+        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.
-        The  compiled form of a regular expression is not altered during match-
+        The compiled form of a regular expression is not altered during  match-
         ing, so the same compiled pattern can safely be used by several threads
         at once.
-Line 885 
 MULTITHREADING
+Line 959 
 MULTITHREADING
  SAVING PRECOMPILED PATTERNS FOR LATER USE
         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
+        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
+        than the one on which  it  was  compiled.  Details  are  given  in  the
-        pcreprecompile documentation. However, compiling a  regular  expression
+        pcreprecompile  documentation.  However, compiling a regular expression
-        with  one version of PCRE for use with a different version is not guar-
+        with one version of PCRE for use with a different version is not  guar-
         anteed to work and may cause crashes.
-Line 896 
 CHECKING BUILD-TIME OPTIONS
+Line 970 
 CHECKING BUILD-TIME OPTIONS
         int pcre_config(int what, void *where);
-        The function pcre_config() makes it possible for a PCRE client to  dis-
+        The  function pcre_config() makes it possible for a PCRE client to dis-
         cover which optional features have been compiled into the PCRE library.
-        The pcrebuild documentation has more details about these optional  fea-
+        The  pcrebuild documentation has more details about these optional fea-
         tures.
-        The  first  argument  for pcre_config() is an integer, specifying which
+        The first argument for pcre_config() is an  integer,  specifying  which
         information is required; the second argument is a pointer to a variable
-        into  which  the  information  is  placed. The following information is
+        into which the information is  placed.  The  following  information  is
         available:
           PCRE_CONFIG_UTF8
-        The output is an integer that is set to one if UTF-8 support is  avail-
+        The  output is an integer that is set to one if UTF-8 support is avail-
         able; otherwise it is set to zero.
           PCRE_CONFIG_UNICODE_PROPERTIES
-        The  output  is  an  integer  that is set to one if support for Unicode
+        The output is an integer that is set to  one  if  support  for  Unicode
         character properties is available; otherwise it is set to zero.
           PCRE_CONFIG_NEWLINE
-        The output is an integer whose value specifies  the  default  character
+        The  output  is  an integer whose value specifies the default character
-        sequence  that is recognized as meaning "newline". The four values that
+        sequence that is recognized as meaning "newline". The four values  that
         are supported are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF,
-        and  -1  for  ANY. The default should normally be the standard sequence
+        and -1 for ANY. The default should normally be  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
-        The output is an integer that contains the number  of  bytes  used  for
+        The  output  is  an  integer that contains the number of bytes used for
         internal linkage in compiled regular expressions. The value is 2, 3, or
-. Larger values allow larger regular expressions to  be  compiled,  at
+.  Larger  values  allow larger regular expressions to be compiled, at
-        the  expense  of  slower matching. The default value of 2 is sufficient
+        the expense of slower matching. The default value of  2  is  sufficient
-        for all but the most massive patterns, since  it  allows  the  compiled
+        for  all  but  the  most massive patterns, since it allows the compiled
         pattern to be up to 64K in size.
           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
-        The  output  is  an integer that contains the threshold above which the
+        The output is an integer that contains the threshold  above  which  the
-        POSIX interface uses malloc() for output vectors. Further  details  are
+        POSIX  interface  uses malloc() for output vectors. Further details are
         given in the pcreposix documentation.
           PCRE_CONFIG_MATCH_LIMIT
         The output is an integer that gives the default limit for the number of
-        internal matching function calls in a  pcre_exec()  execution.  Further
+        internal  matching  function  calls in a pcre_exec() execution. Further
         details are given with pcre_exec() below.
           PCRE_CONFIG_MATCH_LIMIT_RECURSION
-        The  output is an integer that gives the default limit for the depth of
+        The output is an integer that gives the default limit for the depth  of
-        recursion when calling the internal matching function in a  pcre_exec()
+        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 975 
 COMPILING A PATTERN
+Line 1057 
 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.
         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 (via pcre_free) when it is no
         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 various bit settings that affect the com-
-        pilation. 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,  can also be set and unset from within the
-        pattern  (see  the  detailed  description in the pcrepattern documenta-
+        pattern (see the detailed description  in  the  pcrepattern  documenta-
-        tion). For these options, the contents of the options  argument  speci-
+        tion).  For  these options, the contents of the options argument speci-
-        fies  their initial settings at the start of compilation and execution.
+        fies their initial settings at the start of compilation and  execution.
-        The PCRE_ANCHORED and PCRE_NEWLINE_xxx options can be set at  the  time
+        The  PCRE_ANCHORED  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
+        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. This is a static string that is part of the library. You must not
         try to free it. The offset from the start of the pattern to the charac-
         ter where the error was discovered is placed in the variable pointed to
-        by  erroffset,  which must not be NULL. If it is, an immediate error is
+        by erroffset, which must not be NULL. If it is, an immediate  error  is
         given.
-        If pcre_compile2() is used instead of pcre_compile(),  and  the  error-
+        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
+        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
+        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 1036 
 COMPILING A PATTERN
+Line 1118 
 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 a newline at the end of the string (but  not
+        matches  immediately before a newline at the end of the string (but not
-        before  any  other newlines). The PCRE_DOLLAR_ENDONLY option is ignored
+        before any other newlines). The PCRE_DOLLAR_ENDONLY option  is  ignored
-        if PCRE_MULTILINE is set.  There is no equivalent  to  this  option  in
+        if  PCRE_MULTILINE  is  set.   There is no equivalent to this option in
         Perl, and no way to set it within a pattern.
           PCRE_DOTALL
         If this bit is set, a dot metacharater in the pattern matches all char-
-        acters, including those that indicate newline. Without it, a  dot  does
+        acters,  including  those that indicate newline. Without it, a dot does
-        not  match  when  the  current position is at a newline. This option is
+        not match when the current position is at a  newline.  This  option  is
-        equivalent to Perl's /s option, and it can be changed within a  pattern
+        equivalent  to Perl's /s option, and it can be changed within a pattern
-        by  a (?s) option setting. A negative class such as [^a] always matches
+        by a (?s) option setting. A negative class such as [^a] always  matches
         newline characters, independent of the setting of this option.
           PCRE_DUPNAMES
-        If this bit is set, names used to identify capturing  subpatterns  need
+        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
+        is  known  that  only  one instance of the named subpattern can ever be
-        matched.  There  are  more details of named subpatterns below; see also
+        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, inclusive, are also ignored. This  is  equivalent  to  Perl's  /x
+        line,  inclusive,  are  also  ignored.  This is equivalent to Perl's /x
-        option,  and  it  can be changed within a pattern by a (?x) option set-
+        option, and it can be changed within a pattern by a  (?x)  option  set-
         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. (Perl can, however, be persuaded to give a warning for  this.)
+        literal.  (Perl can, however, be persuaded to give a warning for this.)
-        There  are  at  present no other features controlled by this option. It
+        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
+        If  this  option  is  set,  an  unanchored pattern is required to match
-        before  or  at  the  first  newline  in  the subject string, though the
+        before or at the first  newline  in  the  subject  string,  though  the
         matched text may continue over the newline.
           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  internal
+        constructs  match  immediately following or immediately before internal
-        newlines  in  the  subject string, respectively, as well as at the very
+        newlines in the subject string, respectively, as well as  at  the  very
-        start and end. This is equivalent to Perl's /m option, and  it  can  be
+        start  and  end.  This is equivalent to Perl's /m option, and it can be
         changed within a pattern by a (?m) option setting. If there are no new-
-        lines 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
-Line 1149 
 COMPILING A PATTERN
+Line 1240 
 COMPILING A PATTERN
           PCRE_NEWLINE_ANYCRLF
           PCRE_NEWLINE_ANY
-        These  options  override the default newline definition that was chosen
+        These options override the default newline definition that  was  chosen
-        when PCRE was built. Setting the first or the second specifies  that  a
+        when  PCRE  was built. Setting the first or the second specifies that a
-        newline  is  indicated  by a single character (CR or LF, respectively).
+        newline is indicated by a single character (CR  or  LF,  respectively).
-        Setting PCRE_NEWLINE_CRLF specifies that a newline is indicated by  the
+        Setting  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the
-        two-character  CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF specifies
+        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
+        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,
+        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
+        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
+        (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
+        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
+        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-
+        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
+        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
+        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
+        a pattern is if PCRE_EXTENDED is set, and  an  unescaped  #  outside  a
-        character class is encountered. This indicates  a  comment  that  lasts
+        character  class  is  encountered.  This indicates a comment that lasts
-        until  after the next line break sequence. In other circumstances, line
+        until after the next line break sequence. In other circumstances,  line
-        break  sequences  are  treated  as  literal  data,   except   that   in
+        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.
+        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
-Line 1254 
 COMPILATION ERROR CODES
+Line 1346 
 COMPILATION ERROR CODES
  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
-Line 1275 
 COMPILATION ERROR CODES
+Line 1367 
 COMPILATION ERROR CODES
  unknown property name after \P or \p
  subpattern name is too long (maximum 32 characters)
  too many named subpatterns (maximum 10,000)
- repeated subpattern is too long
+ [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"
+ inconsistent NEWLINE options
+ \g is not followed by a braced name or an optionally braced
+                non-zero number
+ (?+ or (?- or (?(+ or (?(- must be followed by a non-zero number
  STUDYING A PATTERN
-Line 1471 
 INFORMATION ABOUT A PATTERN
+Line 1566 
 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) option setting is used in the  pattern,  otherwise
+. The fourth argument should point to an int variable. The (?J) inter-
+        nal option setting changes the local PCRE_DUPNAMES option.
           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.
-Line 1485 
 INFORMATION ABOUT A PATTERN
+Line 1593 
 INFORMATION ABOUT A PATTERN
           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. Several convenience functions such as
-        pcre_get_named_substring() are provided for  extracting  captured  sub-
+        pcre_get_named_substring()  are  provided  for extracting captured sub-
-        strings  by  name. It is also possible to extract the data directly, by
+        strings by name. It is also possible to extract the data  directly,  by
-        first converting the name to a number in order to  access  the  correct
+        first  converting  the  name to a number in order to access the correct
         pointers in the output vector (described with pcre_exec() below). To do
-        the conversion, you need  to  use  the  name-to-number  map,  which  is
+        the  conversion,  you  need  to  use  the  name-to-number map, which is
         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. The names are in alphabetical order.
         When PCRE_DUPNAMES is set, duplicate names are in order of their paren-
-        theses numbers. For example, consider  the  following  pattern  (assume
+        theses  numbers.  For  example,  consider the following pattern (assume
-        PCRE_EXTENDED  is  set,  so  white  space  -  including  newlines  - is
+        PCRE_EXTENDED is  set,  so  white  space  -  including  newlines  -  is
         ignored):
           (?<date> (?<year>(\d\d)?\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 1521 
 INFORMATION ABOUT A PATTERN
+Line 1629 
 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 the entries  is  likely
+        name-to-number  map,  remember that the length of the entries is likely
         to be different for each compiled pattern.
+          PCRE_INFO_OKPARTIAL
+        Return 1 if the pattern can be used for partial matching, otherwise  0.
+        The  fourth  argument  should point to an int variable. The pcrepartial
+        documentation lists the restrictions that apply to patterns  when  par-
+        tial matching is used.
           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 1733 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 1852 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
         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
+        These  options  override  the  newline  definition  that  was chosen or
-        defaulted  when the pattern was compiled. For details, see the descrip-
+        defaulted when the pattern was compiled. For details, see the  descrip-
-        tion of pcre_compile()  above.  During  matching,  the  newline  choice
+        tion  of  pcre_compile()  above.  During  matching,  the newline choice
-        affects  the  behaviour  of the dot, circumflex, and dollar metacharac-
+        affects the behaviour of the dot, circumflex,  and  dollar  metacharac-
-        ters. It may also alter the way the match position is advanced after  a
+        ters.  It may also alter the way the match position is advanced after a
-        match  failure  for  an  unanchored  pattern.  When  PCRE_NEWLINE_CRLF,
+        match failure for an unanchored pattern.
-        PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a  match  attempt
-        fails  when the current position is at a CRLF sequence, the match posi-
+        When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF,  or  PCRE_NEWLINE_ANY  is
-        tion is advanced by two characters instead of one, in other  words,  to
+        set,  and a match attempt for an unanchored pattern fails when the cur-
-        after the CRLF.
+        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  the
-        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-
-        cial  case  of  a  pattern match of the empty string within its split()
+        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
+        function,  and  when  using  the /g modifier. It is possible to emulate
         Perl's behaviour after matching a null string by first trying the match
         again at the same offset with PCRE_NOTEMPTY and PCRE_ANCHORED, and then
-        if  that  fails by advancing the starting offset (see below) and trying
+        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
         this in the pcredemo.c sample program.
           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 2021 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 2169 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
         field in a pcre_extra structure (or defaulted)  was  reached.  See  the
         description above.
-          PCRE_ERROR_NULLWSLIMIT    (-22)
-        When  a  group  that  can  match an empty substring is repeated with an
-        unbounded upper limit, the subject position at the start of  the  group
-        must be remembered, so that a test for an empty string can be made when
-        the end of the group is reached. Some workspace is required  for  this;
-        if it runs out, this error is given.
           PCRE_ERROR_BADNEWLINE     (-23)
         An invalid combination of PCRE_NEWLINE_xxx options was given.
-        Error numbers -16 to -20 are not used by pcre_exec().
+        Error numbers -16 to -20 and -22 are not used by pcre_exec().
  EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
-Line 2181 
 DUPLICATE SUBPATTERN NAMES
+Line 2321 
 DUPLICATE SUBPATTERN NAMES
         subpatterns are not required to  be  unique.  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  docu-
-        mentation. When duplicates are present, pcre_copy_named_substring() and
+        mentation.
+        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, an empty string is
+        the  given  name  that  is set. If none are set, PCRE_ERROR_NOSUBSTRING
-        returned.  The pcre_get_stringnumber() function returns one of the num-
+        (-7) is returned; no  data  is  returned.  The  pcre_get_stringnumber()
-        bers  that are associated with the name, but it is not defined which it
+        function  returns one of the numbers that are associated with the name,
-        is.
+        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
-Line 2388 
 AUTHOR
+Line 2530 
 AUTHOR
  REVISION
-        Last updated: 24 April 2007
+        Last updated: 11 September 2007
         Copyright (c) 1997-2007 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 2491 
 THE CALLOUT INTERFACE
+Line 2633 
 THE CALLOUT INTERFACE
         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 match pointer.
-Line 2557 
 AUTHOR
+Line 2701 
 AUTHOR
  REVISION
-        Last updated: 06 March 2007
+        Last updated: 29 May 2007
         Copyright (c) 1997-2007 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 2573 
 DIFFERENCES BETWEEN PCRE AND PERL
+Line 2717 
 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  mainly
-        with  respect  to  Perl 5.8, though PCRE version 7.0 contains some fea-
+        with  respect  to  Perl 5.8, though PCRE versions 7.0 and later contain
-        tures that are expected to be in the forthcoming Perl 5.10.
+        some features that are expected to be in the forthcoming Perl 5.10.
 . PCRE has only a subset of Perl's UTF-8 and Unicode support.  Details
         of  what  it does have are given in the section on UTF-8 support in the
-Line 2639 
 DIFFERENCES BETWEEN PCRE AND PERL
+Line 2783 
 DIFFERENCES BETWEEN PCRE AND PERL
         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),
+        (*FAIL),  (*F),  (*COMMIT), (*PRUNE), (*SKIP), and (*THEN), but only in
+        the forms without an  argument.  PCRE  does  not  support  (*MARK).  If
+        (*ACCEPT)  is within capturing parentheses, PCRE does not set that cap-
+        ture group; this is different to Perl.
+. PCRE provides some extensions to the Perl regular expression facil-
         ities.   Perl  5.10  will  include new features that are not in earlier
         versions, some of which (such as named parentheses) have been  in  PCRE
         for some time. This list is with respect to Perl 5.10:
-Line 2652 
 DIFFERENCES BETWEEN PCRE AND PERL
+Line 2802 
 DIFFERENCES BETWEEN PCRE AND PERL
         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.  Otherwise,  like  Perl,  the  backslash is
+        cial meaning is faulted. Otherwise, like Perl, the backslash is quietly
-        ignored. (Perl can be made to issue a warning.)
+        ignored.  (Perl can be made to issue a warning.)
         (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-
-Line 2665 
 DIFFERENCES BETWEEN PCRE AND PERL
+Line 2815 
 DIFFERENCES BETWEEN PCRE AND PERL
         (f)  The PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and PCRE_NO_AUTO_CAP-
         TURE options for pcre_exec() have no Perl equivalents.
-        (g) The callout facility is PCRE-specific.
+        (g) The \R escape sequence can be restricted to match only CR,  LF,  or
+        CRLF by the PCRE_BSR_ANYCRLF option.
+        (h) The callout facility is PCRE-specific.
-        (h) The partial matching facility is PCRE-specific.
+        (i) The partial matching facility is PCRE-specific.
-        (i) Patterns compiled by PCRE can be saved and re-used at a later time,
+        (j) Patterns compiled by PCRE can be saved and re-used at a later time,
         even on different hosts that have the other endianness.
-        (j)  The  alternative  matching function (pcre_dfa_exec()) matches in a
+        (k) The alternative matching function (pcre_dfa_exec())  matches  in  a
         different way and is not Perl-compatible.
+        (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.
  AUTHOR
-Line 2685 
 AUTHOR
+Line 2842 
 AUTHOR
  REVISION
-        Last updated: 06 March 2007
+        Last updated: 11 September 2007
         Copyright (c) 1997-2007 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 2699 
 NAME
+Line 2856 
 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. Perl's regular expressions are
-        examples.  Jeffrey Friedl's "Mastering Regular Expressions",  published
+        described in its own documentation, and regular expressions in  general
-        by  O'Reilly, covers regular expressions in great detail. This descrip-
+        are  covered in a number of books, some of which have copious examples.
-        tion of PCRE's regular expressions is intended as reference material.
+        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
-Line 2718 
 PCRE REGULAR EXPRESSION DETAILS
+Line 2877 
 PCRE REGULAR EXPRESSION DETAILS
         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.
+ 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(). 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
+        A  regular  expression  is  a pattern that is matched against a subject
-        string  from  left  to right. Most characters stand for themselves in a
+        string from left to right. Most characters stand for  themselves  in  a
-        pattern, and match the corresponding characters in the  subject.  As  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 within square brackets.  Outside  square  brackets,
+        that  are  recognized  within square brackets. Outside square brackets,
         the metacharacters are as follows:
           \      general escape character with several uses
-Line 2768 
 CHARACTERS AND METACHARACTERS
+Line 2965 
 CHARACTERS AND METACHARACTERS
                  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 2778 
 CHARACTERS AND METACHARACTERS
+Line 2975 
 CHARACTERS AND METACHARACTERS
                    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
         The backslash character has several uses. Firstly, if it is followed by
-        a non-alphanumeric character, it takes away any  special  meaning  that
+        a  non-alphanumeric  character,  it takes away any special meaning that
-        character  may  have.  This  use  of  backslash  as an escape character
+        character may have. This  use  of  backslash  as  an  escape  character
         applies both inside and outside character classes.
-        For example, if you want to match a * character, you write  \*  in  the
+        For  example,  if  you want to match a * character, you write \* in the
-        pattern.   This  escaping  action  applies whether or not the following
+        pattern.  This escaping action applies whether  or  not  the  following
-        character would otherwise be interpreted as a metacharacter, so  it  is
+        character  would  otherwise be interpreted as a metacharacter, so it is
-        always  safe  to  precede  a non-alphanumeric with backslash to specify
+        always safe to precede a non-alphanumeric  with  backslash  to  specify
-        that it stands for itself. In particular, if you want to match a  back-
+        that  it stands for itself. In particular, if you want to match a back-
         slash, you write \\.
-        If  a  pattern is compiled with the PCRE_EXTENDED option, whitespace in
+        If a pattern is compiled with the PCRE_EXTENDED option,  whitespace  in
-        the pattern (other than in a character class) and characters between  a
+        the  pattern (other than in a character class) and characters between a
         # outside a character class and the next newline are ignored. An escap-
-        ing backslash can be used to include a whitespace  or  #  character  as
+        ing  backslash  can  be  used to include a whitespace or # character as
         part of the pattern.
-        If  you  want  to remove the special meaning from a sequence of charac-
+        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-
+        ters,  you can do so by putting them between \Q and \E. This is differ-
-        ent  from  Perl  in  that  $  and  @ are handled as literals in \Q...\E
+        ent from Perl in that $ and  @  are  handled  as  literals  in  \Q...\E
-        sequences in PCRE, whereas in Perl, $ and @ cause  variable  interpola-
+        sequences  in  PCRE, whereas in Perl, $ and @ cause variable interpola-
         tion. Note the following examples:
           Pattern            PCRE matches   Perl matches
-Line 2814 
 BACKSLASH
+Line 3011 
 BACKSLASH
           \Qabc\$xyz\E       abc\$xyz       abc\$xyz
           \Qabc\E\$\Qxyz\E   abc$xyz        abc$xyz
-        The  \Q...\E  sequence  is recognized both inside and outside character
+        The \Q...\E sequence is recognized both inside  and  outside  character
         classes.
     Non-printing characters
         A second use of backslash provides a way of encoding non-printing char-
-        acters  in patterns in a visible manner. There is no restriction on the
+        acters in patterns in a visible manner. There is no restriction on  the
-        appearance of non-printing characters, apart from the binary zero  that
+        appearance  of non-printing characters, apart from the binary zero that
-        terminates  a  pattern,  but  when  a pattern is being prepared by text
+        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  usually  easier  to  use  one of the following escape
         sequences than the binary character it represents:
           \a        alarm, that is, the BEL character (hex 07)
           \cx       "control-x", where x is any character
           \e        escape (hex 1B)
           \f        formfeed (hex 0C)
-          \n        newline (hex 0A)
+          \n        linefeed (hex 0A)
           \r        carriage return (hex 0D)
           \t        tab (hex 09)
           \ddd      character with octal code ddd, or backreference
           \xhh      character with hex code hh
           \x{hhh..} character with hex code hhh..
-        The  precise  effect of \cx is as follows: if x is a lower case letter,
+        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
+        it  is converted to upper case. Then bit 6 of the character (hex 40) is
-        inverted.   Thus  \cz becomes hex 1A, but \c{ becomes hex 3B, while \c;
+        inverted.  Thus \cz becomes hex 1A, but \c{ becomes hex 3B,  while  \c;
         becomes hex 7B.
-        After \x, from zero to two hexadecimal digits are read (letters can  be
+        After  \x, from zero to two hexadecimal digits are read (letters can be
-        in  upper  or  lower case). Any number of hexadecimal digits may appear
+        in upper or lower case). Any number of hexadecimal  digits  may  appear
-        between \x{ and }, but the value of the character  code  must  be  less
+        between  \x{  and  },  but the value of the character code must be less
-        than 256 in non-UTF-8 mode, and less than 2**31 in UTF-8 mode (that is,
+        than 256 in non-UTF-8 mode, and less than 2**31 in UTF-8 mode. That is,
-        the maximum hexadecimal value is 7FFFFFFF). If  characters  other  than
+        the  maximum value in hexadecimal is 7FFFFFFF. Note that this is bigger
-        hexadecimal  digits  appear between \x{ and }, or if there is no termi-
+        than the largest Unicode code point, which is 10FFFF.
-        nating }, this form of escape is not recognized.  Instead, the  initial
-        \x will be interpreted as a basic hexadecimal escape, with no following
+        If characters other than hexadecimal digits appear between \x{  and  },
-        digits, giving a character whose 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. There is no difference in the way they are han-
-Line 2905 
 BACKSLASH
+Line 3105 
 BACKSLASH
     Absolute and relative back references
-        The sequence \g followed by a positive or negative  number,  optionally
+        The sequence \g followed by an unsigned or a negative  number,  option-
-        enclosed  in  braces,  is  an absolute or relative back reference. Back
+        ally  enclosed  in braces, is an absolute or relative back reference. A
-        references are discussed later, following the discussion  of  parenthe-
+        named back reference can be coded as \g{name}. Back references are dis-
-        sized subpatterns.
+        cussed later, following the discussion of parenthesized subpatterns.
     Generic character types
-Line 2917 
 BACKSLASH
+Line 3117 
 BACKSLASH
           \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
-Line 2933 
 BACKSLASH
+Line 3137 
 BACKSLASH
         For  compatibility  with Perl, \s does not match the VT character (code
 ).  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). (If
+        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.)
+        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.
+        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-
-Line 2943 
 BACKSLASH
+Line 3187 
 BACKSLASH
         specific matching is taking place (see "Locale support" in the  pcreapi
         page).  For  example,  in  a French locale such as "fr_FR" in Unix-like
         systems, or "french" in Windows, some character codes greater than  128
-        are used for accented letters, and these are matched by \w.
+        are  used for accented letters, and these are matched by \w. The use of
+        locales with Unicode is discouraged.
-        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. The use of locales with
-        Unicode is discouraged.
     Newline sequences
-        Outside a character class, the escape sequence \R matches  any  Unicode
+        Outside a character class, by default, the escape sequence  \R  matches
-        newline sequence. This is an extension to Perl. In non-UTF-8 mode \R is
+        any Unicode newline sequence. This is a Perl 5.10 feature. In non-UTF-8
-        equivalent to the following:
+        mode \R is equivalent to the following:
           (?>\r\n|\n|\x0b|\f|\r|\x85)
-Line 2970 
 BACKSLASH
+Line 3210 
 BACKSLASH
         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(), but
+        they can be overridden by options given to pcre_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:
+          (*ANY)(*BSR_ANYCRLF)
         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 character properties 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
+        they do work in this mode.  The extra escape sequences are:
           \p{xx}   a character with the xx property
           \P{xx}   a character without the xx property
           \X       an extended Unicode sequence
-        The property names represented by xx above are limited to  the  Unicode
+        The  property  names represented by xx above are limited to the Unicode
         script names, the general category properties, and "Any", which matches
         any character (including newline). Other properties such as "InMusical-
-        Symbols"  are  not  currently supported by PCRE. Note that \P{Any} does
+        Symbols" are not currently supported by PCRE. Note  that  \P{Any}  does
         not match any characters, so always causes a match failure.
         Sets of Unicode characters are defined as belonging to certain scripts.
-        A  character from one of these sets can be matched using a script name.
+        A character from one of these sets can be matched using a script  name.
         For example:
           \p{Greek}
           \P{Han}
-        Those that are not part of an identified script are lumped together  as
+        Those  that are not part of an identified script are lumped together as
         "Common". The current list of scripts is:
         Arabic,  Armenian,  Balinese,  Bengali,  Bopomofo,  Braille,  Buginese,
-        Buhid,  Canadian_Aboriginal,  Cherokee,  Common,   Coptic,   Cuneiform,
+        Buhid,   Canadian_Aboriginal,   Cherokee,  Common,  Coptic,  Cuneiform,
         Cypriot, Cyrillic, Deseret, Devanagari, Ethiopic, Georgian, Glagolitic,
-        Gothic, Greek, Gujarati, Gurmukhi, Han, Hangul, Hanunoo, Hebrew,  Hira-
+        Gothic,  Greek, Gujarati, Gurmukhi, Han, Hangul, Hanunoo, Hebrew, Hira-
-        gana,  Inherited,  Kannada,  Katakana,  Kharoshthi,  Khmer, Lao, Latin,
+        gana, Inherited, Kannada,  Katakana,  Kharoshthi,  Khmer,  Lao,  Latin,
         Limbu,  Linear_B,  Malayalam,  Mongolian,  Myanmar,  New_Tai_Lue,  Nko,
-        Ogham,  Old_Italic,  Old_Persian, Oriya, Osmanya, Phags_Pa, Phoenician,
+        Ogham, Old_Italic, Old_Persian, Oriya, Osmanya,  Phags_Pa,  Phoenician,
         Runic,  Shavian,  Sinhala,  Syloti_Nagri,  Syriac,  Tagalog,  Tagbanwa,
         Tai_Le, Tamil, Telugu, Thaana, Thai, Tibetan, Tifinagh, Ugaritic, Yi.
-        Each  character has exactly one general category property, specified by
+        Each character has exactly one general category property, specified  by
         a two-letter abbreviation. For compatibility with Perl, negation can be
-        specified  by  including a circumflex between the opening brace and the
+        specified by including a circumflex between the opening brace  and  the
         property name. For example, \p{^Lu} is the same as \P{Lu}.
         If only one letter is specified with \p or \P, it includes all the gen-
-        eral  category properties that start with that letter. In this case, in
+        eral category properties that start with that letter. In this case,  in
-        the absence of negation, the curly brackets in the escape sequence  are
+        the  absence of negation, the curly brackets in the escape sequence are
         optional; these two examples have the same effect:
           \p{L}
-Line 3067 
 BACKSLASH
+Line 3331 
 BACKSLASH
           Zp    Paragraph separator
           Zs    Space separator
-        The  special property L& is also supported: it matches a character that
+        The special property L& is also supported: it matches a character  that
-        has the Lu, Ll, or Lt property, in other words, a letter  that  is  not
+        has  the  Lu,  Ll, or Lt property, in other words, a letter that is not
         classified as a modifier or "other".
-        The  long  synonyms  for  these  properties that Perl supports (such as
+        The Cs (Surrogate) property applies only to  characters  in  the  range
-        \p{Letter}) are not supported by PCRE, nor is it  permitted  to  prefix
+        U+D800  to  U+DFFF. Such characters are not valid in UTF-8 strings (see
+        RFC 3629) and so cannot be tested by PCRE, unless UTF-8 validity check-
+        ing  has  been  turned off (see the discussion of PCRE_NO_UTF8_CHECK in
+        the pcreapi page).
+        The long synonyms for these properties  that  Perl  supports  (such  as
+        \p{Letter})  are  not  supported by PCRE, nor is it permitted to prefix
         any of these properties with "Is".
         No character that is in the Unicode table has the Cn (unassigned) prop-
         erty.  Instead, this property is assumed for any code point that is not
         in the Unicode table.
-        Specifying  caseless  matching  does not affect these escape sequences.
+        Specifying caseless matching does not affect  these  escape  sequences.
         For example, \p{Lu} always matches only upper case letters.
-        The \X escape matches any number of Unicode  characters  that  form  an
+        The  \X  escape  matches  any number of Unicode characters that form an
         extended Unicode sequence. \X is equivalent to
           (?>\PM\pM*)
-        That  is,  it matches a character without the "mark" property, followed
+        That is, it matches a character without the "mark"  property,  followed
-        by zero or more characters with the "mark"  property,  and  treats  the
+        by  zero  or  more  characters with the "mark" property, and treats the
-        sequence  as  an  atomic group (see below).  Characters with the "mark"
+        sequence as an atomic group (see below).  Characters  with  the  "mark"
-        property are typically accents that affect the preceding character.
+        property  are  typically  accents  that affect the preceding character.
+        None of them have codepoints less than 256, so  in  non-UTF-8  mode  \X
+        matches any one character.
-        Matching characters by Unicode property is not fast, because  PCRE  has
+        Matching  characters  by Unicode property is not fast, because PCRE has
-        to  search  a  structure  that  contains data for over fifteen thousand
+        to search a structure that contains  data  for  over  fifteen  thousand
         characters. That is why the traditional escape sequences such as \d and
         \w do not use Unicode properties in PCRE.
+    Resetting the match start
+        The escape sequence \K, which is a Perl 5.10 feature, causes any previ-
+        ously  matched  characters  not  to  be  included  in the final matched
+        sequence. For example, the pattern:
+          foo\Kbar
+        matches "foobar", but reports that it has matched "bar".  This  feature
+        is  similar  to  a lookbehind assertion (described below).  However, in
+        this case, the part of the subject before the real match does not  have
+        to  be of fixed length, as lookbehind assertions do. The use of \K does
+        not interfere with the setting of captured  substrings.   For  example,
+        when the pattern
+          (foo)\Kbar
+        matches "foobar", the first substring is still set to "foo".
     Simple assertions
         The  final use of backslash is for certain simple assertions. An asser-
-Line 3396 
 VERTICAL BAR
+Line 3687 
 VERTICAL BAR
  INTERNAL OPTION SETTING
         The  settings  of  the  PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, and
-        PCRE_EXTENDED options can be changed  from  within  the  pattern  by  a
+        PCRE_EXTENDED options (which are Perl-compatible) can be  changed  from
-        sequence  of  Perl  option  letters  enclosed between "(?" and ")". The
+        within  the  pattern  by  a  sequence  of  Perl option letters enclosed
-        option letters are
+        between "(?" and ")".  The option letters are
           i  for PCRE_CASELESS
           m  for PCRE_MULTILINE
-Line 3412 
 INTERNAL OPTION SETTING
+Line 3703 
 INTERNAL OPTION SETTING
         is also permitted. If a  letter  appears  both  before  and  after  the
         hyphen, the option is unset.
+        The  PCRE-specific options PCRE_DUPNAMES, PCRE_UNGREEDY, and PCRE_EXTRA
+        can be changed in the same way as the Perl-compatible options by  using
+        the characters J, U and X respectively.
         When  an option change occurs at top level (that is, not inside subpat-
         tern parentheses), the change applies to the remainder of  the  pattern
         that follows.  If the change is placed right at the start of a pattern,
-Line 3437 
 INTERNAL OPTION SETTING
+Line 3732 
 INTERNAL OPTION SETTING
         the  effects  of option settings happen at compile time. There would be
         some very weird behaviour otherwise.
-        The PCRE-specific options PCRE_DUPNAMES, PCRE_UNGREEDY, and  PCRE_EXTRA
+        Note: There are other PCRE-specific options that  can  be  set  by  the
-        can  be changed in the same way as the Perl-compatible options by using
+        application  when  the  compile  or match functions are called. In some
-        the characters J, U and X respectively.
+        cases the pattern can contain special  leading  sequences  to  override
+        what  the  application  has set or what has been defaulted. Details are
+        given in the section entitled "Newline sequences" above.
  SUBPATTERNS
-Line 3497 
 SUBPATTERNS
+Line 3794 
 SUBPATTERNS
         "Saturday".
+ DUPLICATE SUBPATTERN NUMBERS
+        Perl 5.10 introduced a feature whereby each alternative in a subpattern
+        uses the same numbers for its capturing parentheses. Such a  subpattern
+        starts  with (?| and is itself a non-capturing subpattern. For example,
+        consider this pattern:
+          (?|(Sat)ur|(Sun))day
+        Because the two alternatives are inside a (?| group, both sets of  cap-
+        turing  parentheses  are  numbered one. Thus, when the pattern matches,
+        you can look at captured substring number  one,  whichever  alternative
+        matched.  This  construct  is useful when you want to capture part, but
+        not all, of one of a number of alternatives. Inside a (?| group, paren-
+        theses  are  numbered as usual, but the number is reset at the start of
+        each branch. The numbers of any capturing buffers that follow the  sub-
+        pattern  start after the highest number used in any branch. The follow-
+        ing example is taken from the Perl documentation.  The  numbers  under-
+        neath show in which buffer the captured content will be stored.
+          # before  ---------------branch-reset----------- after
+          / ( a )  (?| x ( y ) z | (p (q) r) | (t) u (v) ) ( z ) /x
+          # 1            2         2  3        2     3     4
+        A  backreference  or  a  recursive call to a numbered subpattern always
+        refers to the first one in the pattern with the given number.
+        An alternative approach to using this "branch reset" feature is to  use
+        duplicate named subpatterns, as described in the next section.
  NAMED SUBPATTERNS
         Identifying  capturing  parentheses  by number is simple, but it can be
-Line 3536 
 NAMED SUBPATTERNS
+Line 3864 
 NAMED SUBPATTERNS
           (?<DN>Sat)(?:urday)?
         There  are  five capturing substrings, but only one is ever set after a
-        match.  The convenience  function  for  extracting  the  data  by  name
+        match.  (An alternative way of solving this problem is to use a "branch
-        returns  the  substring  for  the first (and in this example, the only)
+        reset" subpattern, as described in the previous section.)
-        subpattern of that name that matched.  This  saves  searching  to  find
-        which  numbered  subpattern  it  was. If you make a reference to a non-
+        The  convenience  function  for extracting the data by name returns the
-        unique named subpattern from elsewhere in the  pattern,  the  one  that
+        substring for the first (and in this example, the only)  subpattern  of
-        corresponds  to  the  lowest number is used. For further details of the
+        that  name  that  matched.  This saves searching to find which numbered
-        interfaces for handling named subpatterns, see the  pcreapi  documenta-
+        subpattern it was. If you make a reference to a non-unique  named  sub-
-        tion.
+        pattern  from elsewhere in the pattern, the one that corresponds to the
+        lowest number is used. For further details of the interfaces  for  han-
+        dling named subpatterns, see the pcreapi documentation.
  REPETITION
-Line 3748 
 ATOMIC GROUPING AND POSSESSIVE QUANTIFIE
+Line 4078 
 ATOMIC GROUPING AND POSSESSIVE QUANTIFIE
           \d++foo
-        Possessive  quantifiers  are  always  greedy;  the   setting   of   the
+        Note that a possessive quantifier can be used with an entire group, for
+        example:
+          (abc|xyz){2,3}+
+        Possessive   quantifiers   are   always  greedy;  the  setting  of  the
         PCRE_UNGREEDY option is ignored. They are a convenient notation for the
-        simpler forms of atomic group. However, there is no difference  in  the
+        simpler  forms  of atomic group. However, there is no difference in the
-        meaning  of  a  possessive  quantifier and the equivalent atomic group,
+        meaning of a possessive quantifier and  the  equivalent  atomic  group,
-        though there may be a performance  difference;  possessive  quantifiers
+        though  there  may  be a performance difference; possessive quantifiers
         should be slightly faster.
-        The  possessive  quantifier syntax is an extension to the Perl 5.8 syn-
+        The possessive quantifier syntax is an extension to the Perl  5.8  syn-
-        tax.  Jeffrey Friedl originated the idea (and the name)  in  the  first
+        tax.   Jeffrey  Friedl  originated the idea (and the name) in the first
         edition of his book. Mike McCloskey liked it, so implemented it when he
-        built Sun's Java package, and PCRE copied it from there. It  ultimately
+        built  Sun's Java package, and PCRE copied it from there. It ultimately
         found its way into Perl at release 5.10.
         PCRE has an optimization that automatically "possessifies" certain sim-
-        ple pattern constructs. For example, the sequence  A+B  is  treated  as
+        ple  pattern  constructs.  For  example, the sequence A+B is treated as
-        A++B  because  there is no point in backtracking into a sequence of A's
+        A++B because there is no point in backtracking into a sequence  of  A's
         when B must follow.
-        When a pattern contains an unlimited repeat inside  a  subpattern  that
+        When  a  pattern  contains an unlimited repeat inside a subpattern that
-        can  itself  be  repeated  an  unlimited number of times, the use of an
+        can itself be repeated an unlimited number of  times,  the  use  of  an
-        atomic group is the only way to avoid some  failing  matches  taking  a
+        atomic  group  is  the  only way to avoid some failing matches taking a
         very long time indeed. The pattern
           (\D+|<\d+>)*[!?]
-        matches  an  unlimited number of substrings that either consist of non-
+        matches an unlimited number of substrings that either consist  of  non-
-        digits, or digits enclosed in <>, followed by either ! or  ?.  When  it
+        digits,  or  digits  enclosed in <>, followed by either ! or ?. When it
         matches, it runs quickly. However, if it is applied to
           aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
-        it  takes  a  long  time  before reporting failure. This is because the
+        it takes a long time before reporting  failure.  This  is  because  the
-        string can be divided between the internal \D+ repeat and the  external
+        string  can be divided between the internal \D+ repeat and the external
-        *  repeat  in  a  large  number of ways, and all have to be tried. (The
+        * repeat in a large number of ways, and all  have  to  be  tried.  (The
-        example uses [!?] rather than a single character at  the  end,  because
+        example  uses  [!?]  rather than a single character at the end, because
-        both  PCRE  and  Perl have an optimization that allows for fast failure
+        both PCRE and Perl have an optimization that allows  for  fast  failure
-        when a single character is used. They remember the last single  charac-
+        when  a single character is used. They remember the last single charac-
-        ter  that  is required for a match, and fail early if it is not present
+        ter that is required for a match, and fail early if it is  not  present
-        in the string.) If the pattern is changed so that  it  uses  an  atomic
+        in  the  string.)  If  the pattern is changed so that it uses an atomic
         group, like this:
           ((?>\D+)|<\d+>)*[!?]
-        sequences  of non-digits cannot be broken, and failure happens quickly.
+        sequences of non-digits cannot be broken, and failure happens  quickly.
  BACK REFERENCES
         Outside a character class, a backslash followed by a digit greater than
 (and possibly further digits) is a back reference to a capturing sub-
-        pattern earlier (that is, to its left) in the pattern,  provided  there
+        pattern  earlier  (that is, to its left) in the pattern, provided there
         have been that many previous capturing left parentheses.
         However, if the decimal number following the backslash is less than 10,
-        it is always taken as a back reference, and causes  an  error  only  if
+        it  is  always  taken  as a back reference, and causes an error only if
-        there  are  not that many capturing left parentheses in the entire pat-
+        there are not that many capturing left parentheses in the  entire  pat-
-        tern. In other words, the parentheses that are referenced need  not  be
+        tern.  In  other words, the parentheses that are referenced need not be
-        to  the left of the reference for numbers less than 10. A "forward back
+        to the left of the reference for numbers less than 10. A "forward  back
-        reference" of this type can make sense when a  repetition  is  involved
+        reference"  of  this  type can make sense when a repetition is involved
-        and  the  subpattern to the right has participated in an earlier itera-
+        and the subpattern to the right has participated in an  earlier  itera-
         tion.
-        It is not possible to have a numerical "forward back  reference"  to  a
+        It  is  not  possible to have a numerical "forward back reference" to a
-        subpattern  whose  number  is  10  or  more using this syntax because a
+        subpattern whose number is 10 or  more  using  this  syntax  because  a
-        sequence such as \50 is interpreted as a character  defined  in  octal.
+        sequence  such  as  \50 is interpreted as a character defined in octal.
         See the subsection entitled "Non-printing characters" above for further
-        details of the handling of digits following a backslash.  There  is  no
+        details  of  the  handling of digits following a backslash. There is no
-        such  problem  when named parentheses are used. A back reference to any
+        such problem when named parentheses are used. A back reference  to  any
         subpattern is possible using named parentheses (see below).
-        Another way of avoiding the ambiguity inherent in  the  use  of  digits
+        Another  way  of  avoiding  the ambiguity inherent in the use of digits
         following a backslash is to use the \g escape sequence, which is a fea-
-        ture introduced in Perl 5.10. This escape must be followed by  a  posi-
+        ture  introduced  in  Perl  5.10.  This  escape  must be followed by an
-        tive  or  a negative number, optionally enclosed in braces. These exam-
+        unsigned number or a negative number, optionally  enclosed  in  braces.
-        ples are all identical:
+        These examples are all identical:
           (ring), \1
           (ring), \g1
           (ring), \g{1}
-        A positive number specifies an absolute reference without the ambiguity
+        An  unsigned number specifies an absolute reference without the ambigu-
-        that  is  present  in  the older syntax. It is also useful when literal
+        ity that is present in the older syntax. It is also useful when literal
         digits follow the reference. A negative number is a relative reference.
         Consider this example:
           (abc(def)ghi)\g{-1}
         The sequence \g{-1} is a reference to the most recently started captur-
-        ing subpattern before \g, that is, is it equivalent to  \2.  Similarly,
+        ing  subpattern  before \g, that is, is it equivalent to \2. Similarly,
         \g{-2} would be equivalent to \1. The use of relative references can be
-        helpful in long patterns, and also in  patterns  that  are  created  by
+        helpful  in  long  patterns,  and  also in patterns that are created by
         joining together fragments that contain references within themselves.
-        A  back  reference matches whatever actually matched the capturing sub-
+        A back reference matches whatever actually matched the  capturing  sub-
-        pattern in the current subject string, rather  than  anything  matching
+        pattern  in  the  current subject string, rather than anything matching
         the subpattern itself (see "Subpatterns as subroutines" below for a way
         of doing that). So the pattern
           (sens|respons)e and \1ibility
-        matches "sense and sensibility" and "response and responsibility",  but
+        matches  "sense and sensibility" and "response and responsibility", but
-        not  "sense and responsibility". If caseful matching is in force at the
+        not "sense and responsibility". If caseful matching is in force at  the
-        time of the back reference, the case of letters is relevant. For  exam-
+        time  of the back reference, the case of letters is relevant. For exam-
         ple,
           ((?i)rah)\s+\1
-        matches  "rah  rah"  and  "RAH RAH", but not "RAH rah", even though the
+        matches "rah rah" and "RAH RAH", but not "RAH  rah",  even  though  the
         original capturing subpattern is matched caselessly.
-        Back references to named subpatterns use the Perl  syntax  \k<name>  or
+        There  are  several  different ways of writing back references to named
-        \k'name'  or  the  Python  syntax (?P=name). We could rewrite the above
+        subpatterns. The .NET syntax \k{name} and the Perl syntax  \k<name>  or
-        example in either of the following ways:
+        \k'name'  are supported, as is the Python syntax (?P=name). Perl 5.10's
+        unified back reference syntax, in which \g can be used for both numeric
+        and  named  references,  is  also supported. We could rewrite the above
+        example in any of the following ways:
           (?<p1>(?i)rah)\s+\k<p1>
+          (?'p1'(?i)rah)\s+\k{p1}
           (?P<p1>(?i)rah)\s+(?P=p1)
+          (?<p1>(?i)rah)\s+\g{p1}
         A subpattern that is referenced by  name  may  appear  in  the  pattern
         before or after the reference.
-Line 3978 
 ASSERTIONS
+Line 4318 
 ASSERTIONS
           (?<=abc|abde)
+        In some cases, the Perl 5.10 escape sequence \K (see above) can be used
+        instead  of  a lookbehind assertion; this is not restricted to a fixed-
+        length.
         The implementation of lookbehind assertions is, for  each  alternative,
         to  temporarily  move the current position back by the fixed length and
         then try to match. If there are insufficient characters before the cur-
-Line 4071 
 CONDITIONAL SUBPATTERNS
+Line 4415 
 CONDITIONAL SUBPATTERNS
         If  the  text between the parentheses consists of a sequence of digits,
         the condition is true if the capturing subpattern of  that  number  has
-        previously matched.
+        previously  matched.  An  alternative notation is to precede the digits
+        with a plus or minus sign. In this case, the subpattern number is rela-
+        tive rather than absolute.  The most recently opened parentheses can be
+        referenced by (?(-1), the next most recent by (?(-2),  and  so  on.  In
+        looping constructs it can also make sense to refer to subsequent groups
+        with constructs such as (?(+2).
-        Consider  the  following  pattern, which contains non-significant white
+        Consider the following pattern, which  contains  non-significant  white
         space to make it more readable (assume the PCRE_EXTENDED option) and to
         divide it into three parts for ease of discussion:
           ( \( )?    [^()]+    (?(1) \) )
-        The  first  part  matches  an optional opening parenthesis, and if that
+        The first part matches an optional opening  parenthesis,  and  if  that
         character is present, sets it as the first captured substring. The sec-
-        ond  part  matches one or more characters that are not parentheses. The
+        ond part matches one or more characters that are not  parentheses.  The
         third part is a conditional subpattern that tests whether the first set
         of parentheses matched or not. If they did, that is, if subject started
         with an opening parenthesis, the condition is true, and so the yes-pat-
-        tern  is  executed  and  a  closing parenthesis is required. Otherwise,
+        tern is executed and a  closing  parenthesis  is  required.  Otherwise,
-        since no-pattern is not present, the  subpattern  matches  nothing.  In
+        since  no-pattern  is  not  present, the subpattern matches nothing. In
-        other  words,  this  pattern  matches  a  sequence  of non-parentheses,
+        other words,  this  pattern  matches  a  sequence  of  non-parentheses,
         optionally enclosed in parentheses.
+        If  you  were  embedding  this pattern in a larger one, you could use a
+        relative reference:
+          ...other stuff... ( \( )?    [^()]+    (?(-1) \) ) ...
+        This makes the fragment independent of the parentheses  in  the  larger
+        pattern.
     Checking for a used subpattern by name
-        Perl uses the syntax (?(<name>)...) or (?('name')...)  to  test  for  a
+        Perl  uses  the  syntax  (?(<name>)...) or (?('name')...) to test for a
-        used  subpattern  by  name.  For compatibility with earlier versions of
+        used subpattern by name. For compatibility  with  earlier  versions  of
-        PCRE, which had this facility before Perl, the syntax  (?(name)...)  is
+        PCRE,  which  had this facility before Perl, the syntax (?(name)...) is
-        also  recognized. However, there is a possible ambiguity with this syn-
+        also recognized. However, there is a possible ambiguity with this  syn-
-        tax, because subpattern names may  consist  entirely  of  digits.  PCRE
+        tax,  because  subpattern  names  may  consist entirely of digits. PCRE
-        looks  first for a named subpattern; if it cannot find one and the name
+        looks first for a named subpattern; if it cannot find one and the  name
-        consists entirely of digits, PCRE looks for a subpattern of  that  num-
+        consists  entirely  of digits, PCRE looks for a subpattern of that num-
-        ber,  which must be greater than zero. Using subpattern names that con-
+        ber, which must be greater than zero. Using subpattern names that  con-
         sist entirely of digits is not recommended.
         Rewriting the above example to use a named subpattern gives this:
-Line 4110 
 CONDITIONAL SUBPATTERNS
+Line 4467 
 CONDITIONAL SUBPATTERNS
     Checking for pattern recursion
         If the condition is the string (R), and there is no subpattern with the
-        name  R, the condition is true if a recursive call to the whole pattern
+        name R, the condition is true if a recursive call to the whole  pattern
         or any subpattern has been made. If digits or a name preceded by amper-
         sand follow the letter R, for example:
           (?(R3)...) or (?(R&name)...)
-        the  condition is true if the most recent recursion is into the subpat-
+        the condition is true if the most recent recursion is into the  subpat-
-        tern whose number or name is given. This condition does not  check  the
+        tern  whose  number or name is given. This condition does not check the
         entire recursion stack.
-        At  "top  level", all these recursion test conditions are false. Recur-
+        At "top level", all these recursion test conditions are  false.  Recur-
         sive patterns are described below.
     Defining subpatterns for use by reference only
-        If the condition is the string (DEFINE), and  there  is  no  subpattern
+        If  the  condition  is  the string (DEFINE), and there is no subpattern
-        with  the  name  DEFINE,  the  condition is always false. In this case,
+        with the name DEFINE, the condition is  always  false.  In  this  case,
-        there may be only one alternative  in  the  subpattern.  It  is  always
+        there  may  be  only  one  alternative  in the subpattern. It is always
-        skipped  if  control  reaches  this  point  in the pattern; the idea of
+        skipped if control reaches this point  in  the  pattern;  the  idea  of
-        DEFINE is that it can be used to define "subroutines" that can be  ref-
+        DEFINE  is that it can be used to define "subroutines" that can be ref-
-        erenced  from elsewhere. (The use of "subroutines" is described below.)
+        erenced from elsewhere. (The use of "subroutines" is described  below.)
-        For example, a pattern to match an IPv4 address could be  written  like
+        For  example,  a pattern to match an IPv4 address could be written like
         this (ignore whitespace and line breaks):
           (?(DEFINE) (?<byte> 2[0-4]\d | 25[0-5] | 1\d\d | [1-9]?\d) )
           \b (?&byte) (\.(?&byte)){3} \b
-        The  first part of the pattern is a DEFINE group inside which a another
+        The first part of the pattern is a DEFINE group inside which a  another
-        group named "byte" is defined. This matches an individual component  of
+        group  named "byte" is defined. This matches an individual component of
-        an  IPv4  address  (a number less than 256). When matching takes place,
+        an IPv4 address (a number less than 256). When  matching  takes  place,
-        this part of the pattern is skipped because DEFINE acts  like  a  false
+        this  part  of  the pattern is skipped because DEFINE acts like a false
         condition.
         The rest of the pattern uses references to the named group to match the
-        four dot-separated components of an IPv4 address, insisting on  a  word
+        four  dot-separated  components of an IPv4 address, insisting on a word
         boundary at each end.
     Assertion conditions
-        If  the  condition  is  not  in any of the above formats, it must be an
+        If the condition is not in any of the above  formats,  it  must  be  an
-        assertion.  This may be a positive or negative lookahead or  lookbehind
+        assertion.   This may be a positive or negative lookahead or lookbehind
-        assertion.  Consider  this  pattern,  again  containing non-significant
+        assertion. Consider  this  pattern,  again  containing  non-significant
         white space, and with the two alternatives on the second line:
           (?(?=[^a-z]*[a-z])
           \d{2}-[a-z]{3}-\d{2}  |  \d{2}-\d{2}-\d{2} )
-        The condition  is  a  positive  lookahead  assertion  that  matches  an
+        The  condition  is  a  positive  lookahead  assertion  that  matches an
-        optional  sequence of non-letters followed by a letter. In other words,
+        optional sequence of non-letters followed by a letter. In other  words,
-        it tests for the presence of at least one letter in the subject.  If  a
+        it  tests  for the presence of at least one letter in the subject. If a
-        letter  is found, the subject is matched against the first alternative;
+        letter is found, the subject is matched against the first  alternative;
-        otherwise it is  matched  against  the  second.  This  pattern  matches
+        otherwise  it  is  matched  against  the  second.  This pattern matches
-        strings  in  one  of the two forms dd-aaa-dd or dd-dd-dd, where aaa are
+        strings in one of the two forms dd-aaa-dd or dd-dd-dd,  where  aaa  are
         letters and dd are digits.
  COMMENTS
-        The sequence (?# marks the start of a comment that continues up to  the
+        The  sequence (?# marks the start of a comment that continues up to the
-        next  closing  parenthesis.  Nested  parentheses are not permitted. The
+        next closing parenthesis. Nested parentheses  are  not  permitted.  The
-        characters that make up a comment play no part in the pattern  matching
+        characters  that make up a comment play no part in the pattern matching
         at all.
-        If  the PCRE_EXTENDED option is set, an unescaped # character outside a
+        If the PCRE_EXTENDED option is set, an unescaped # character outside  a
-        character class introduces a  comment  that  continues  to  immediately
+        character  class  introduces  a  comment  that continues to immediately
         after the next newline in the pattern.
  RECURSIVE PATTERNS
-        Consider  the problem of matching a string in parentheses, allowing for
+        Consider the problem of matching a string in parentheses, allowing  for
-        unlimited nested parentheses. Without the use of  recursion,  the  best
+        unlimited  nested  parentheses.  Without the use of recursion, the best
-        that  can  be  done  is  to use a pattern that matches up to some fixed
+        that can be done is to use a pattern that  matches  up  to  some  fixed
-        depth of nesting. It is not possible to  handle  an  arbitrary  nesting
+        depth  of  nesting.  It  is not possible to handle an arbitrary nesting
         depth.
         For some time, Perl has provided a facility that allows regular expres-
-        sions to recurse (amongst other things). It does this by  interpolating
+        sions  to recurse (amongst other things). It does this by interpolating
-        Perl  code in the expression at run time, and the code can refer to the
+        Perl code in the expression at run time, and the code can refer to  the
         expression itself. A Perl pattern using code interpolation to solve the
         parentheses problem can be created like this:
-Line 4198 
 RECURSIVE PATTERNS
+Line 4555 
 RECURSIVE PATTERNS
         refers recursively to the pattern in which it appears.
         Obviously, PCRE cannot support the interpolation of Perl code. Instead,
-        it  supports  special  syntax  for recursion of the entire pattern, and
+        it supports special syntax for recursion of  the  entire  pattern,  and
-        also for individual subpattern recursion.  After  its  introduction  in
+        also  for  individual  subpattern  recursion. After its introduction in
-        PCRE  and  Python,  this  kind of recursion was introduced into Perl at
+        PCRE and Python, this kind of recursion was  introduced  into  Perl  at
         release 5.10.
-        A special item that consists of (? followed by a  number  greater  than
+        A  special  item  that consists of (? followed by a number greater than
         zero and a closing parenthesis is a recursive call of the subpattern of
-        the given number, provided that it occurs inside that  subpattern.  (If
+        the  given  number, provided that it occurs inside that subpattern. (If
-        not,  it  is  a  "subroutine" call, which is described in the next sec-
+        not, it is a "subroutine" call, which is described  in  the  next  sec-
-        tion.) The special item (?R) or (?0) is a recursive call of the  entire
+        tion.)  The special item (?R) or (?0) is a recursive call of the entire
         regular expression.
-        In  PCRE (like Python, but unlike Perl), a recursive subpattern call is
+        In PCRE (like Python, but unlike Perl), a recursive subpattern call  is
         always treated as an atomic group. That is, once it has matched some of
         the subject string, it is never re-entered, even if it contains untried
         alternatives and there is a subsequent matching failure.
-        This PCRE pattern solves the nested  parentheses  problem  (assume  the
+        This  PCRE  pattern  solves  the nested parentheses problem (assume the
         PCRE_EXTENDED option is set so that white space is ignored):
           \( ( (?>[^()]+) | (?R) )* \)
-        First  it matches an opening parenthesis. Then it matches any number of
+        First it matches an opening parenthesis. Then it matches any number  of
-        substrings which can either be a  sequence  of  non-parentheses,  or  a
+        substrings  which  can  either  be  a sequence of non-parentheses, or a
-        recursive  match  of the pattern itself (that is, a correctly parenthe-
+        recursive match of the pattern itself (that is, a  correctly  parenthe-
         sized substring).  Finally there is a closing parenthesis.
-        If this were part of a larger pattern, you would not  want  to  recurse
+        If  this  were  part of a larger pattern, you would not want to recurse
         the entire pattern, so instead you could use this:
           ( \( ( (?>[^()]+) | (?1) )* \) )
-        We  have  put the pattern into parentheses, and caused the recursion to
+        We have put the pattern into parentheses, and caused the  recursion  to
-        refer to them instead of the whole pattern. In a larger pattern,  keep-
+        refer to them instead of the whole pattern.
-        ing  track  of parenthesis numbers can be tricky. It may be more conve-
-        nient to use named parentheses instead. The Perl  syntax  for  this  is
+        In  a  larger  pattern,  keeping  track  of  parenthesis numbers can be
-        (?&name);  PCRE's  earlier syntax (?P>name) is also supported. We could
+        tricky. This is made easier by the use of relative references. (A  Perl
-        rewrite the above example as follows:
+.10  feature.)   Instead  of  (?1)  in the pattern above you can write
+        (?-2) to refer to the second most recently opened parentheses preceding
+        the  recursion.  In  other  words,  a  negative number counts capturing
+        parentheses leftwards from the point at which it is encountered.
+        It is also possible to refer to  subsequently  opened  parentheses,  by
+        writing  references  such  as (?+2). However, these cannot be recursive
+        because the reference is not inside the  parentheses  that  are  refer-
+        enced.  They  are  always  "subroutine" calls, as described in the next
+        section.
+        An alternative approach is to use named parentheses instead.  The  Perl
+        syntax  for  this  is (?&name); PCRE's earlier syntax (?P>name) is also
+        supported. We could rewrite the above example as follows:
           (?<pn> \( ( (?>[^()]+) | (?&pn) )* \) )
         If there is more than one subpattern with the same name,  the  earliest
-        one  is used. This particular example pattern contains nested unlimited
+        one is used.
-        repeats, and so the use of atomic grouping for matching strings of non-
-        parentheses  is  important when applying the pattern to strings that do
+        This  particular  example pattern that we have been looking at contains
-        not match. For example, when this pattern is applied to
+        nested unlimited repeats, and so the use of atomic grouping for  match-
+        ing  strings  of non-parentheses is important when applying the pattern
+        to strings that do not match. For example, when this pattern is applied
+        to
           (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa()
-        it yields "no match" quickly. However, if atomic grouping is not  used,
+        it  yields "no match" quickly. However, if atomic grouping is not used,
-        the  match  runs  for a very long time indeed because there are so many
+        the match runs for a very long time indeed because there  are  so  many
-        different ways the + and * repeats can carve up the  subject,  and  all
+        different  ways  the  + and * repeats can carve up the subject, and all
         have to be tested before failure can be reported.
         At the end of a match, the values set for any capturing subpatterns are
         those from the outermost level of the recursion at which the subpattern
-        value  is  set.   If  you want to obtain intermediate values, a callout
+        value is set.  If you want to obtain  intermediate  values,  a  callout
-        function can be used (see below and the pcrecallout documentation).  If
+        function  can be used (see below and the pcrecallout documentation). If
         the pattern above is matched against
           (ab(cd)ef)
-        the  value  for  the  capturing  parentheses is "ef", which is the last
+        the value for the capturing parentheses is  "ef",  which  is  the  last
-        value taken on at the top level. If additional parentheses  are  added,
+        value  taken  on at the top level. If additional parentheses are added,
         giving
           \( ( ( (?>[^()]+) | (?R) )* ) \)
              ^                        ^
              ^                        ^
-        the  string  they  capture is "ab(cd)ef", the contents of the top level
+        the string they capture is "ab(cd)ef", the contents of  the  top  level
-        parentheses. If there are more than 15 capturing parentheses in a  pat-
+        parentheses.  If there are more than 15 capturing parentheses in a pat-
         tern, PCRE has to obtain extra memory to store data during a recursion,
-        which it does by using pcre_malloc, freeing  it  via  pcre_free  after-
+        which  it  does  by  using pcre_malloc, freeing it via pcre_free after-
-        wards.  If  no  memory  can  be  obtained,  the  match  fails  with the
+        wards. If  no  memory  can  be  obtained,  the  match  fails  with  the
         PCRE_ERROR_NOMEMORY error.
-        Do not confuse the (?R) item with the condition (R),  which  tests  for
+        Do  not  confuse  the (?R) item with the condition (R), which tests for
-        recursion.   Consider  this pattern, which matches text in angle brack-
+        recursion.  Consider this pattern, which matches text in  angle  brack-
-        ets, allowing for arbitrary nesting. Only digits are allowed in  nested
+        ets,  allowing for arbitrary nesting. Only digits are allowed in nested
-        brackets  (that is, when recursing), whereas any characters are permit-
+        brackets (that is, when recursing), whereas any characters are  permit-
         ted at the outer level.
           < (?: (?(R) \d++  | [^<>]*+) | (?R)) * >
-        In this pattern, (?(R) is the start of a conditional  subpattern,  with
+        In  this  pattern, (?(R) is the start of a conditional subpattern, with
-        two  different  alternatives for the recursive and non-recursive cases.
+        two different alternatives for the recursive and  non-recursive  cases.
         The (?R) item is the actual recursive call.
  SUBPATTERNS AS SUBROUTINES
         If the syntax for a recursive subpattern reference (either by number or
-        by  name)  is used outside the parentheses to which it refers, it oper-
+        by name) is used outside the parentheses to which it refers,  it  oper-
-        ates like a subroutine in a programming language. The "called"  subpat-
+        ates  like a subroutine in a programming language. The "called" subpat-
-        tern  may  be defined before or after the reference. An earlier example
+        tern may be defined before or after the reference. A numbered reference
-        pointed out that the pattern
+        can be absolute or relative, as in these examples:
+          (...(absolute)...)...(?2)...
+          (...(relative)...)...(?-1)...
+          (...(?+1)...(relative)...
+        An earlier example pointed out that the pattern
           (sens|respons)e and \1ibility
-        matches "sense and sensibility" and "response and responsibility",  but
+        matches  "sense and sensibility" and "response and responsibility", but
         not "sense and responsibility". If instead the pattern
           (sens|respons)e and (?1)ibility
-        is  used, it does match "sense and responsibility" as well as the other
+        is used, it does match "sense and responsibility" as well as the  other
-        two strings. Another example is  given  in  the  discussion  of  DEFINE
+        two  strings.  Another  example  is  given  in the discussion of DEFINE
         above.
         Like recursive subpatterns, a "subroutine" call is always treated as an
-        atomic group. That is, once it has matched some of the subject  string,
+        atomic  group. That is, once it has matched some of the subject string,
-        it  is  never  re-entered, even if it contains untried alternatives and
+        it is never re-entered, even if it contains  untried  alternatives  and
         there is a subsequent matching failure.
-        When a subpattern is used as a subroutine, processing options  such  as
+        When  a  subpattern is used as a subroutine, processing options such as
         case-independence are fixed when the subpattern is defined. They cannot
         be changed for different calls. For example, consider this pattern:
-          (abc)(?i:(?1))
+          (abc)(?i:(?-1))
-        It matches "abcabc". It does not match "abcABC" because the  change  of
+        It  matches  "abcabc". It does not match "abcABC" because the change of
         processing option does not affect the called subpattern.
  CALLOUTS
         Perl has a feature whereby using the sequence (?{...}) causes arbitrary
-        Perl code to be obeyed in the middle of matching a regular  expression.
+        Perl  code to be obeyed in the middle of matching a regular expression.
         This makes it possible, amongst other things, to extract different sub-
         strings that match the same pair of parentheses when there is a repeti-
         tion.
         PCRE provides a similar feature, but of course it cannot obey arbitrary
         Perl code. The feature is called "callout". The caller of PCRE provides
-        an  external function by putting its entry point in the global variable
+        an external function by putting its entry point in the global  variable
-        pcre_callout.  By default, this variable contains NULL, which  disables
+        pcre_callout.   By default, this variable contains NULL, which disables
         all calling out.
-        Within  a  regular  expression,  (?C) indicates the points at which the
+        Within a regular expression, (?C) indicates the  points  at  which  the
-        external function is to be called. If you want  to  identify  different
+        external  function  is  to be called. If you want to identify different
-        callout  points, you can put a number less than 256 after the letter C.
+        callout points, you can put a number less than 256 after the letter  C.
-        The default value is zero.  For example, this pattern has  two  callout
+        The  default  value is zero.  For example, this pattern has two callout
         points:
           (?C1)abc(?C2)def
         If the PCRE_AUTO_CALLOUT flag is passed to pcre_compile(), callouts are
-        automatically installed before each item in the pattern. They  are  all
+        automatically  installed  before each item in the pattern. They are all
         numbered 255.
         During matching, when PCRE reaches a callout point (and pcre_callout is
-        set), the external function is called. It is provided with  the  number
+        set),  the  external function is called. It is provided with the number
-        of  the callout, the position in the pattern, and, optionally, one item
+        of the callout, the position in the pattern, and, optionally, one  item
-        of data originally supplied by the caller of pcre_exec().  The  callout
+        of  data  originally supplied by the caller of pcre_exec(). The callout
-        function  may cause matching to proceed, to backtrack, or to fail alto-
+        function may cause matching to proceed, to backtrack, or to fail  alto-
         gether. A complete description of the interface to the callout function
         is given in the pcrecallout documentation.
+ BACKTRACKING CONTROL
+        Perl 5.10 introduced a number of "Special Backtracking Control  Verbs",
+        which are described in the Perl documentation as "experimental and sub-
+        ject to change or removal in a future version of Perl". It goes  on  to
+        say:  "Their usage in production code should be noted to avoid problems
+        during upgrades." The same remarks apply to the PCRE features described
+        in this section.
+        Since these verbs are specifically related to backtracking, they can be
+        used only when the pattern is to be matched  using  pcre_exec(),  which
+        uses  a  backtracking  algorithm. They cause an error if encountered by
+        pcre_dfa_exec().
+        The new verbs make use of what was previously invalid syntax: an  open-
+        ing parenthesis followed by an asterisk. In Perl, they are generally of
+        the form (*VERB:ARG) but PCRE does not support the use of arguments, so
+        its  general  form is just (*VERB). Any number of these verbs may occur
+        in a pattern. There are two kinds:
+    Verbs that act immediately
+        The following verbs act as soon as they are encountered:
+           (*ACCEPT)
+        This verb causes the match to end successfully, skipping the  remainder
+        of  the pattern. When inside a recursion, only the innermost pattern is
+        ended immediately. PCRE differs  from  Perl  in  what  happens  if  the
+        (*ACCEPT)  is inside capturing parentheses. In Perl, the data so far is
+        captured: in PCRE no data is captured. For example:
+          A(A|B(*ACCEPT)|C)D
+        This matches "AB", "AAD", or "ACD", but when it matches "AB",  no  data
+        is captured.
+          (*FAIL) or (*F)
+        This  verb  causes the match to fail, forcing backtracking to occur. It
+        is equivalent to (?!) but easier to read. The Perl documentation  notes
+        that  it  is  probably  useful only when combined with (?{}) or (??{}).
+        Those are, of course, Perl features that are not present in  PCRE.  The
+        nearest  equivalent is the callout feature, as for example in this pat-
+        tern:
+          a+(?C)(*FAIL)
+        A match with the string "aaaa" always fails, but the callout  is  taken
+        before each backtrack happens (in this example, 10 times).
+    Verbs that act after backtracking
+        The following verbs do nothing when they are encountered. Matching con-
+        tinues with what follows, but if there is no subsequent match, a  fail-
+        ure  is  forced.   The  verbs  differ  in  exactly what kind of failure
+        occurs.
+          (*COMMIT)
+        This verb causes the whole match to fail outright if the  rest  of  the
+        pattern  does  not match. Even if the pattern is unanchored, no further
+        attempts to find a match by advancing the start point take place.  Once
+        (*COMMIT)  has been passed, pcre_exec() is committed to finding a match
+        at the current starting point, or not at all. For example:
+          a+(*COMMIT)b
+        This matches "xxaab" but not "aacaab". It can be thought of as  a  kind
+        of dynamic anchor, or "I've started, so I must finish."
+          (*PRUNE)
+        This  verb causes the match to fail at the current position if the rest
+        of the pattern does not match. If the pattern is unanchored, the normal
+        "bumpalong"  advance to the next starting character then happens. Back-
+        tracking can occur as usual to the left of (*PRUNE), or  when  matching
+        to  the right of (*PRUNE), but if there is no match to the right, back-
+        tracking cannot cross (*PRUNE).  In simple cases, the use  of  (*PRUNE)
+        is just an alternative to an atomic group or possessive quantifier, but
+        there are some uses of (*PRUNE) that cannot be expressed in  any  other
+        way.
+          (*SKIP)
+        This  verb  is like (*PRUNE), except that if the pattern is unanchored,
+        the "bumpalong" advance is not to the next character, but to the  posi-
+        tion  in  the  subject where (*SKIP) was encountered. (*SKIP) signifies
+        that whatever text was matched leading up to it cannot  be  part  of  a
+        successful match. Consider:
+          a+(*SKIP)b
+        If  the  subject  is  "aaaac...",  after  the first match attempt fails
+        (starting at the first character in the  string),  the  starting  point
+        skips on to start the next attempt at "c". Note that a possessive quan-
+        tifer does not have the same effect in this example; although it  would
+        suppress  backtracking  during  the  first  match  attempt,  the second
+        attempt would start at the second character instead of skipping  on  to
+        "c".
+          (*THEN)
+        This verb causes a skip to the next alternation if the rest of the pat-
+        tern does not match. That is, it cancels pending backtracking, but only
+        within  the  current  alternation.  Its name comes from the observation
+        that it can be used for a pattern-based if-then-else block:
+          ( COND1 (*THEN) FOO | COND2 (*THEN) BAR | COND3 (*THEN) BAZ ) ...
+        If the COND1 pattern matches, FOO is tried (and possibly further  items
+        after  the  end  of  the group if FOO succeeds); on failure the matcher
+        skips to the second alternative and tries COND2,  without  backtracking
+        into  COND1.  If  (*THEN)  is  used outside of any alternation, it acts
+        exactly like (*PRUNE).
  SEE ALSO
         pcreapi(3), pcrecallout(3), pcrematching(3), pcre(3).
-Line 4371 
 AUTHOR
+Line 4867 
 AUTHOR
  REVISION
-        Last updated: 06 March 2007
+        Last updated: 17 September 2007
+        Copyright (c) 1997-2007 University of Cambridge.
+ ------------------------------------------------------------------------------
+ PCRESYNTAX(3)                                                    PCRESYNTAX(3)
+ NAME
+        PCRE - Perl-compatible regular expressions
+ PCRE REGULAR EXPRESSION SYNTAX SUMMARY
+        The  full syntax and semantics of the regular expressions that are sup-
+        ported by PCRE are described in  the  pcrepattern  documentation.  This
+        document contains just a quick-reference summary of the syntax.
+ QUOTING
+          \x         where x is non-alphanumeric is a literal x
+          \Q...\E    treat enclosed characters as literal
+ CHARACTERS
+          \a         alarm, that is, the BEL character (hex 07)
+          \cx        "control-x", where x is any character
+          \e         escape (hex 1B)
+          \f         formfeed (hex 0C)
+          \n         newline (hex 0A)
+          \r         carriage return (hex 0D)
+          \t         tab (hex 09)
+          \ddd       character with octal code ddd, or backreference
+          \xhh       character with hex code hh
+          \x{hhh..}  character with hex code hhh..
+ CHARACTER TYPES
+          .          any character except newline;
+                       in dotall mode, any character whatsoever
+          \C         one byte, even in UTF-8 mode (best avoided)
+          \d         a decimal digit
+          \D         a character that is not a decimal digit
+          \h         a horizontal whitespace character
+          \H         a character that is not a horizontal whitespace character
+          \p{xx}     a character with the xx property
+          \P{xx}     a character without the xx property
+          \R         a newline sequence
+          \s         a whitespace character
+          \S         a character that is not a whitespace character
+          \v         a vertical whitespace character
+          \V         a character that is not a vertical whitespace character
+          \w         a "word" character
+          \W         a "non-word" character
+          \X         an extended Unicode sequence
+        In PCRE, \d, \D, \s, \S, \w, and \W recognize only ASCII characters.
+ GENERAL CATEGORY PROPERTY CODES FOR \p and \P
+          C          Other
+          Cc         Control
+          Cf         Format
+          Cn         Unassigned
+          Co         Private use
+          Cs         Surrogate
+          L          Letter
+          Ll         Lower case letter
+          Lm         Modifier letter
+          Lo         Other letter
+          Lt         Title case letter
+          Lu         Upper case letter
+          L&         Ll, Lu, or Lt
+          M          Mark
+          Mc         Spacing mark
+          Me         Enclosing mark
+          Mn         Non-spacing mark
+          N          Number
+          Nd         Decimal number
+          Nl         Letter number
+          No         Other number
+          P          Punctuation
+          Pc         Connector punctuation
+          Pd         Dash punctuation
+          Pe         Close punctuation
+          Pf         Final punctuation
+          Pi         Initial punctuation
+          Po         Other punctuation
+          Ps         Open punctuation
+          S          Symbol
+          Sc         Currency symbol
+          Sk         Modifier symbol
+          Sm         Mathematical symbol
+          So         Other symbol
+          Z          Separator
+          Zl         Line separator
+          Zp         Paragraph separator
+          Zs         Space separator
+ SCRIPT NAMES FOR \p AND \P
+        Arabic,  Armenian,  Balinese,  Bengali,  Bopomofo,  Braille,  Buginese,
+        Buhid,  Canadian_Aboriginal,  Cherokee,  Common,   Coptic,   Cuneiform,
+        Cypriot, Cyrillic, Deseret, Devanagari, Ethiopic, Georgian, Glagolitic,
+        Gothic, Greek, Gujarati, Gurmukhi, Han, Hangul, Hanunoo, Hebrew,  Hira-
+        gana,  Inherited,  Kannada,  Katakana,  Kharoshthi,  Khmer, Lao, Latin,
+        Limbu,  Linear_B,  Malayalam,  Mongolian,  Myanmar,  New_Tai_Lue,  Nko,
+        Ogham,  Old_Italic,  Old_Persian, Oriya, Osmanya, Phags_Pa, Phoenician,
+        Runic,  Shavian,  Sinhala,  Syloti_Nagri,  Syriac,  Tagalog,  Tagbanwa,
+        Tai_Le, Tamil, Telugu, Thaana, Thai, Tibetan, Tifinagh, Ugaritic, Yi.
+ CHARACTER CLASSES
+          [...]       positive character class
+          [^...]      negative character class
+          [x-y]       range (can be used for hex characters)
+          [[:xxx:]]   positive POSIX named set
+          [[^:xxx:]]  negative POSIX named set
+          alnum       alphanumeric
+          alpha       alphabetic
+          ascii       0-127
+          blank       space or tab
+          cntrl       control character
+          digit       decimal digit
+          graph       printing, excluding space
+          lower       lower case letter
+          print       printing, including space
+          punct       printing, excluding alphanumeric
+          space       whitespace
+          upper       upper case letter
+          word        same as \w
+          xdigit      hexadecimal digit
+        In PCRE, POSIX character set names recognize only ASCII characters. You
+        can use \Q...\E inside a character class.
+ QUANTIFIERS
+          ?           0 or 1, greedy
+          ?+          0 or 1, possessive
+          ??          0 or 1, lazy
+          *           0 or more, greedy
+          *+          0 or more, possessive
+          *?          0 or more, lazy
+          +           1 or more, greedy
+          ++          1 or more, possessive
+          +?          1 or more, lazy
+          {n}         exactly n
+          {n,m}       at least n, no more than m, greedy
+          {n,m}+      at least n, no more than m, possessive
+          {n,m}?      at least n, no more than m, lazy
+          {n,}        n or more, greedy
+          {n,}+       n or more, possessive
+          {n,}?       n or more, lazy
+ ANCHORS AND SIMPLE ASSERTIONS
+          \b          word boundary
+          \B          not a word boundary
+          ^           start of subject
+                       also after internal newline in multiline mode
+          \A          start of subject
+          $           end of subject
+                       also before newline at end of subject
+                       also before internal newline in multiline mode
+          \Z          end of subject
+                       also before newline at end of subject
+          \z          end of subject
+          \G          first matching position in subject
+ MATCH POINT RESET
+          \K          reset start of match
+ ALTERNATION
+          expr|expr|expr...
+ CAPTURING
+          (...)          capturing group
+          (?<name>...)   named capturing group (Perl)
+          (?'name'...)   named capturing group (Perl)
+          (?P<name>...)  named capturing group (Python)
+          (?:...)        non-capturing group
+          (?|...)        non-capturing group; reset group numbers for
+                          capturing groups in each alternative
+ ATOMIC GROUPS
+          (?>...)        atomic, non-capturing group
+ COMMENT
+          (?#....)       comment (not nestable)
+ OPTION SETTING
+          (?i)           caseless
+          (?J)           allow duplicate names
+          (?m)           multiline
+          (?s)           single line (dotall)
+          (?U)           default ungreedy (lazy)
+          (?x)           extended (ignore white space)
+          (?-...)        unset option(s)
+ LOOKAHEAD AND LOOKBEHIND ASSERTIONS
+          (?=...)        positive look ahead
+          (?!...)        negative look ahead
+          (?<=...)       positive look behind
+          (?<!...)       negative look behind
+        Each top-level branch of a look behind must be of a fixed length.
+ BACKREFERENCES
+          \n             reference by number (can be ambiguous)
+          \gn            reference by number
+          \g{n}          reference by number
+          \g{-n}         relative reference by number
+          \k<name>       reference by name (Perl)
+          \k'name'       reference by name (Perl)
+          \g{name}       reference by name (Perl)
+          \k{name}       reference by name (.NET)
+          (?P=name)      reference by name (Python)
+ SUBROUTINE REFERENCES (POSSIBLY RECURSIVE)
+          (?R)           recurse whole pattern
+          (?n)           call subpattern by absolute number
+          (?+n)          call subpattern by relative number
+          (?-n)          call subpattern by relative number
+          (?&name)       call subpattern by name (Perl)
+          (?P>name)      call subpattern by name (Python)
+ CONDITIONAL PATTERNS
+          (?(condition)yes-pattern)
+          (?(condition)yes-pattern|no-pattern)
+          (?(n)...       absolute reference condition
+          (?(+n)...      relative reference condition
+          (?(-n)...      relative reference condition
+          (?(<name>)...  named reference condition (Perl)
+          (?('name')...  named reference condition (Perl)
+          (?(name)...    named reference condition (PCRE)
+          (?(R)...       overall recursion condition
+          (?(Rn)...      specific group recursion condition
+          (?(R&name)...  specific recursion condition
+          (?(DEFINE)...  define subpattern for reference
+          (?(assert)...  assertion condition
+ BACKTRACKING CONTROL
+        The following act immediately they are reached:
+          (*ACCEPT)      force successful match
+          (*FAIL)        force backtrack; synonym (*F)
+        The following act only when a subsequent match failure causes  a  back-
+        track to reach them. They all force a match failure, but they differ in
+        what happens afterwards. Those that advance the start-of-match point do
+        so only if the pattern is not anchored.
+          (*COMMIT)      overall failure, no advance of starting point
+          (*PRUNE)       advance to next starting character
+          (*SKIP)        advance start to current matching position
+          (*THEN)        local failure, backtrack to next alternation
+ NEWLINE CONVENTIONS
+        These  are  recognized only at the very start of the pattern or after a
+        (*BSR_...) option.
+          (*CR)
+          (*LF)
+          (*CRLF)
+          (*ANYCRLF)
+          (*ANY)
+ WHAT \R MATCHES
+        These are recognized only at the very start of the pattern or  after  a
+        (*...) option that sets the newline convention.
+          (*BSR_ANYCRLF)
+          (*BSR_UNICODE)
+ CALLOUTS
+          (?C)      callout
+          (?Cn)     callout with data n
+ SEE ALSO
+        pcrepattern(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcre(3).
+ AUTHOR
+        Philip Hazel
+        University Computing Service
+        Cambridge CB2 3QH, England.
+ REVISION
+        Last updated: 21 September 2007
         Copyright (c) 1997-2007 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 4452 
 RESTRICTED PATTERNS FOR PCRE_PARTIAL
+Line 5286 
 RESTRICTED PATTERNS FOR PCRE_PARTIAL
         If PCRE_PARTIAL is set for a pattern  that  does  not  conform  to  the
         restrictions,  pcre_exec() returns the error code PCRE_ERROR_BADPARTIAL
-        (-13).
+        (-13).  You can use the PCRE_INFO_OKPARTIAL call to pcre_fullinfo()  to
+        find out if a compiled pattern can be used for partial matching.
  EXAMPLE OF PARTIAL MATCHING USING PCRETEST
-        If the escape sequence \P is present  in  a  pcretest  data  line,  the
+        If  the  escape  sequence  \P  is  present in a pcretest data line, the
         PCRE_PARTIAL flag is used for the match. Here is a run of pcretest that
         uses the date example quoted above:
-Line 4474 
 EXAMPLE OF PARTIAL MATCHING USING PCRETE
+Line 5309 
 EXAMPLE OF PARTIAL MATCHING USING PCRETE
           data> j\P
           No match
-        The first data string is matched  completely,  so  pcretest  shows  the
+        The  first  data  string  is  matched completely, so pcretest shows the
-        matched  substrings.  The  remaining four strings do not match the com-
+        matched substrings. The remaining four strings do not  match  the  com-
-        plete pattern, but the first two are partial matches.  The  same  test,
+        plete  pattern,  but  the first two are partial matches. The same test,
-        using  pcre_dfa_exec()  matching  (by means of the \D escape sequence),
+        using pcre_dfa_exec() matching (by means of the  \D  escape  sequence),
         produces the following output:
             re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
-Line 4492 
 EXAMPLE OF PARTIAL MATCHING USING PCRETE
+Line 5327 
 EXAMPLE OF PARTIAL MATCHING USING PCRETE
           data> j\P\D
           No match
-        Notice that in this case the portion of the string that was matched  is
+        Notice  that in this case the portion of the string that was matched is
         made available.
  MULTI-SEGMENT MATCHING WITH pcre_dfa_exec()
         When a partial match has been found using pcre_dfa_exec(), it is possi-
-        ble to continue the match by  providing  additional  subject  data  and
+        ble  to  continue  the  match  by providing additional subject data and
-        calling  pcre_dfa_exec()  again  with the same compiled regular expres-
+        calling pcre_dfa_exec() again with the same  compiled  regular  expres-
         sion, this time setting the PCRE_DFA_RESTART option. You must also pass
-        the  same working space as before, because this is where details of the
+        the same working space as before, because this is where details of  the
-        previous partial match are stored. Here is an example  using  pcretest,
+        previous  partial  match are stored. Here is an example using pcretest,
         using the \R escape sequence to set the PCRE_DFA_RESTART option (\P and
         \D are as above):
-Line 4513 
 MULTI-SEGMENT MATCHING WITH pcre_dfa_exe
+Line 5348 
 MULTI-SEGMENT MATCHING WITH pcre_dfa_exe
           data> n05\R\D
 : n05
-        The first call has "23ja" as the subject, and requests  partial  match-
+        The  first  call has "23ja" as the subject, and requests partial match-
-        ing;  the  second  call  has  "n05"  as  the  subject for the continued
+        ing; the second call  has  "n05"  as  the  subject  for  the  continued
-        (restarted) match.  Notice that when the match is  complete,  only  the
+        (restarted)  match.   Notice  that when the match is complete, only the
-        last  part  is  shown;  PCRE  does not retain the previously partially-
+        last part is shown; PCRE does  not  retain  the  previously  partially-
-        matched string. It is up to the calling program to do that if it  needs
+        matched  string. It is up to the calling program to do that if it needs
         to.
-        You  can  set  PCRE_PARTIAL  with  PCRE_DFA_RESTART to continue partial
+        You can set PCRE_PARTIAL  with  PCRE_DFA_RESTART  to  continue  partial
         matching over multiple segments. This facility can be used to pass very
-        long  subject  strings to pcre_dfa_exec(). However, some care is needed
+        long subject strings to pcre_dfa_exec(). However, some care  is  needed
         for certain types of pattern.
-. If the pattern contains tests for the beginning or end  of  a  line,
+.  If  the  pattern contains tests for the beginning or end of a line,
-        you  need  to pass the PCRE_NOTBOL or PCRE_NOTEOL options, as appropri-
+        you need to pass the PCRE_NOTBOL or PCRE_NOTEOL options,  as  appropri-
-        ate, when the subject string for any call does not contain  the  begin-
+        ate,  when  the subject string for any call does not contain the begin-
         ning or end of a line.
-.  If  the  pattern contains backward assertions (including \b or \B),
+. If the pattern contains backward assertions (including  \b  or  \B),
-        you need to arrange for some overlap in the subject  strings  to  allow
+        you  need  to  arrange for some overlap in the subject strings to allow
-        for  this.  For  example, you could pass the subject in chunks that are
+        for this. For example, you could pass the subject in  chunks  that  are
-bytes long, but in a buffer of 700 bytes, with the starting  offset
+ bytes long, but in a buffer of 700 bytes, with the starting offset
         set to 200 and the previous 200 bytes at the start of the buffer.
-.  Matching a subject string that is split into multiple segments does
+. Matching a subject string that is split into multiple segments  does
-        not always produce exactly the same result as matching over one  single
+        not  always produce exactly the same result as matching over one single
-        long  string.   The  difference arises when there are multiple matching
+        long string.  The difference arises when there  are  multiple  matching
-        possibilities, because a partial match result is given only when  there
+        possibilities,  because a partial match result is given only when there
-        are  no completed matches in a call to pcre_dfa_exec(). This means that
+        are no completed matches in a call to pcre_dfa_exec(). This means  that
-        as soon as the shortest match has been found,  continuation  to  a  new
+        as  soon  as  the  shortest match has been found, continuation to a new
         subject segment is no longer possible.  Consider this pcretest example:
             re> /dog(sbody)?/
-Line 4553 
 MULTI-SEGMENT MATCHING WITH pcre_dfa_exe
+Line 5388 
 MULTI-SEGMENT MATCHING WITH pcre_dfa_exe
 : dogsbody
 : dog
-        The pattern matches the words "dog" or "dogsbody". When the subject  is
+        The  pattern matches the words "dog" or "dogsbody". When the subject is
-        presented  in  several  parts  ("do" and "gsb" being the first two) the
+        presented in several parts ("do" and "gsb" being  the  first  two)  the
-        match stops when "dog" has been found, and it is not possible  to  con-
+        match  stops  when "dog" has been found, and it is not possible to con-
-        tinue.  On  the  other  hand,  if  "dogsbody"  is presented as a single
+        tinue. On the other hand,  if  "dogsbody"  is  presented  as  a  single
         string, both matches are found.
-        Because of this phenomenon, it does not usually make  sense  to  end  a
+        Because  of  this  phenomenon,  it does not usually make sense to end a
         pattern that is going to be matched in this way with a variable repeat.
 . Patterns that contain alternatives at the top level which do not all
-Line 4568 
 MULTI-SEGMENT MATCHING WITH pcre_dfa_exe
+Line 5403 
 MULTI-SEGMENT MATCHING WITH pcre_dfa_exe
 |3789
-        If the first part of the subject is "ABC123", a partial  match  of  the
+        If  the  first  part of the subject is "ABC123", a partial match of the
-        first  alternative  is found at offset 3. There is no partial match for
+        first alternative is found at offset 3. There is no partial  match  for
         the second alternative, because such a match does not start at the same
-        point  in  the  subject  string. Attempting to continue with the string
+        point in the subject string. Attempting to  continue  with  the  string
         "789" does not yield a match because only those alternatives that match
-        at  one point in the subject are remembered. The problem arises because
+        at one point in the subject are remembered. The problem arises  because
-        the start of the second alternative matches within the  first  alterna-
+        the  start  of the second alternative matches within the first alterna-
         tive. There is no problem with anchored patterns or patterns such as:
 |ABCD
-Line 4591 
 AUTHOR
+Line 5426 
 AUTHOR
  REVISION
-        Last updated: 06 March 2007
+        Last updated: 04 June 2007
         Copyright (c) 1997-2007 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 4701 
 RE-USING A PRECOMPILED PATTERN
+Line 5536 
 RE-USING A PRECOMPILED PATTERN
  COMPATIBILITY WITH DIFFERENT PCRE RELEASES
-        The layout of the control block that is at the start of the  data  that
+        In general, it is safest to  recompile  all  saved  patterns  when  you
-        makes  up  a  compiled pattern was changed for release 5.0. If you have
+        update  to  a new PCRE release, though not all updates actually require
-        any saved patterns that were compiled with  previous  releases  (not  a
+        this. Recompiling is definitely needed for release 7.2.
-        facility  that  was  previously advertised), you will have to recompile
-        them for release 5.0 and above.
-        If you have any saved patterns in UTF-8 mode that use  \p  or  \P  that
-        were  compiled  with any release up to and including 6.4, you will have
-        to recompile them for release 6.5 and above.
-        All saved patterns from earlier releases must be recompiled for release
-.0  or  higher,  because  there was an internal reorganization at that
-        release.
  AUTHOR
-Line 4725 
 AUTHOR
+Line 5550 
 AUTHOR
  REVISION
-        Last updated: 24 April 2007
+        Last updated: 13 June 2007
         Copyright (c) 1997-2007 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 5460 
 PCRE SAMPLE PROGRAM
+Line 6285 
 PCRE SAMPLE PROGRAM
         bility  of  matching an empty string. Comments in the code explain what
         is going on.
-        If PCRE is installed in the standard include  and  library  directories
+        The demonstration program is automatically built if you use  "./config-
-        for  your  system, you should be able to compile the demonstration pro-
+        ure;make"  to  build PCRE. Otherwise, if PCRE is installed in the stan-
-        gram using this command:
+        dard include and library directories for your  system,  you  should  be
+        able to compile the demonstration program using this command:
           gcc -o pcredemo pcredemo.c -lpcre
-        If PCRE is installed elsewhere, you may need to add additional  options
+        If  PCRE is installed elsewhere, you may need to add additional options
-        to  the  command line. For example, on a Unix-like system that has PCRE
+        to the command line. For example, on a Unix-like system that  has  PCRE
-        installed in /usr/local, you  can  compile  the  demonstration  program
+        installed  in  /usr/local,  you  can  compile the demonstration program
         using a command like this:
           gcc -o pcredemo -I/usr/local/include pcredemo.c \
               -L/usr/local/lib -lpcre
-        Once  you  have  compiled the demonstration program, you can run simple
+        Once you have compiled the demonstration program, you  can  run  simple
         tests like this:
           ./pcredemo 'cat|dog' 'the cat sat on the mat'
           ./pcredemo -g 'cat|dog' 'the dog sat on the cat'
-        Note that there is a  much  more  comprehensive  test  program,  called
+        Note  that  there  is  a  much  more comprehensive test program, called
-        pcretest,  which  supports  many  more  facilities  for testing regular
+        pcretest, which supports  many  more  facilities  for  testing  regular
         expressions and the PCRE library. The pcredemo program is provided as a
         simple coding example.
-Line 5489 
 PCRE SAMPLE PROGRAM
+Line 6315 
 PCRE SAMPLE PROGRAM
         the standard library directory, you may get an error like this when you
         try to run pcredemo:
-          ld.so.1:  a.out:  fatal:  libpcre.so.0:  open failed: No such file or
+          ld.so.1: a.out: fatal: libpcre.so.0: open failed:  No  such  file  or
         directory
-        This is caused by the way shared library support works  on  those  sys-
+        This  is  caused  by the way shared library support works on those sys-
         tems. You need to add
           -R/usr/local/lib
-Line 5509 
 AUTHOR
+Line 6335 
 AUTHOR
  REVISION
-        Last updated: 06 March 2007
+        Last updated: 13 June 2007
         Copyright (c) 1997-2007 University of Cambridge.
  ------------------------------------------------------------------------------
  PCRESTACK(3)                                                      PCRESTACK(3)
-Line 5579 
 PCRE DISCUSSION OF STACK USAGE
+Line 6405 
 PCRE DISCUSSION OF STACK USAGE
         In environments where stack memory is constrained, you  might  want  to
         compile  PCRE to use heap memory instead of stack for remembering back-
         up points. This makes it run a lot more slowly, however. Details of how
-        to do this are given in the pcrebuild documentation.
+        to do this are given in the pcrebuild documentation. When built in this
+        way, instead of using the stack, PCRE obtains and frees memory by call-
-        In  Unix-like environments, there is not often a problem with the stack
+        ing  the  functions  that  are  pointed to by the pcre_stack_malloc and
-        unless very long strings are involved,  though  the  default  limit  on
+        pcre_stack_free variables. By default,  these  point  to  malloc()  and
-        stack  size  varies  from system to system. Values from 8Mb to 64Mb are
+        free(),  but you can replace the pointers to cause PCRE to use your own
+        functions. Since the block sizes are always the same,  and  are  always
+        freed in reverse order, it may be possible to implement customized mem-
+        ory handlers that are more efficient than the standard functions.
+        In Unix-like environments, there is not often a problem with the  stack
+        unless  very  long  strings  are  involved, though the default limit on
+        stack size varies from system to system. Values from 8Mb  to  64Mb  are
         common. You can find your default limit by running the command:
           ulimit -s
-        Unfortunately, the effect of running out of  stack  is  often  SIGSEGV,
+        Unfortunately,  the  effect  of  running out of stack is often SIGSEGV,
-        though  sometimes  a more explicit error message is given. You can nor-
+        though sometimes a more explicit error message is given. You  can  nor-
         mally increase the limit on stack size by code such as this:
           struct rlimit rlim;
-Line 5597 
 PCRE DISCUSSION OF STACK USAGE
+Line 6430 
 PCRE DISCUSSION OF STACK USAGE
           rlim.rlim_cur = 100*1024*1024;
           setrlimit(RLIMIT_STACK, &rlim);
-        This reads the current limits (soft and hard) using  getrlimit(),  then
+        This  reads  the current limits (soft and hard) using getrlimit(), then
-        attempts  to  increase  the  soft limit to 100Mb using setrlimit(). You
+        attempts to increase the soft limit to  100Mb  using  setrlimit().  You
         must do this before calling pcre_exec().
-        PCRE has an internal counter that can be used to  limit  the  depth  of
+        PCRE  has  an  internal  counter that can be used to limit the depth of
-        recursion,  and  thus cause pcre_exec() to give an error code before it
+        recursion, and thus cause pcre_exec() to give an error code  before  it
-        runs out of stack. By default, the limit is very  large,  and  unlikely
+        runs  out  of  stack. By default, the limit is very large, and unlikely
-        ever  to operate. It can be changed when PCRE is built, and it can also
+        ever to operate. It can be changed when PCRE is built, and it can  also
         be set when pcre_exec() is called. For details of these interfaces, see
         the pcrebuild and pcreapi documentation.
         As a very rough rule of thumb, you should reckon on about 500 bytes per
-        recursion. Thus, if you want to limit your  stack  usage  to  8Mb,  you
+        recursion.  Thus,  if  you  want  to limit your stack usage to 8Mb, you
-        should  set  the  limit at 16000 recursions. A 64Mb stack, on the other
+        should set the limit at 16000 recursions. A 64Mb stack,  on  the  other
-        hand, can support around 128000 recursions. The pcretest  test  program
+        hand,  can  support around 128000 recursions. The pcretest test program
         has a command line option (-S) that can be used to increase the size of
         its stack.
-Line 5625 
 AUTHOR
+Line 6458 
 AUTHOR
  REVISION
-        Last updated: 12 March 2007
+        Last updated: 05 June 2007
         Copyright (c) 1997-2007 University of Cambridge.
  ------------------------------------------------------------------------------

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