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

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-revision 75 by nigel,
Sat Feb 24 21:40:37 2007 UTC
+revision 96 by nigel,
Fri Mar  2 13:10:43 2007 UTC
 Line 6 
 synopses of each function in the library
  separate text files for the pcregrep and pcretest commands.
  -----------------------------------------------------------------------------
- PCRE(3)                                                                PCRE(3)
+ PCRE(3)                                                                PCRE(3)
  NAME
         PCRE - Perl-compatible regular expressions
  INTRODUCTION
         The  PCRE  library is a set of functions that implement regular expres-
         sion pattern matching using the same syntax and semantics as Perl, with
-        just  a  few  differences.  The current implementation of PCRE (release
+        just  a  few differences. (Certain features that appeared in Python and
-.x) corresponds approximately with Perl  5.8,  including  support  for
+        PCRE before they appeared in Perl are also available using  the  Python
-        UTF-8 encoded strings and Unicode general category properties. However,
+        syntax.)
-        this support has to be explicitly enabled; it is not the default.
+        The  current  implementation of PCRE (release 7.x) corresponds approxi-
-        PCRE is written in C and released as a C library. A  number  of  people
+        mately with Perl 5.10, including support for UTF-8 encoded strings  and
-        have  written  wrappers and interfaces of various kinds. A C++ class is
+        Unicode general category properties. However, UTF-8 and Unicode support
-        included in these contributions, which can  be  found  in  the  Contrib
+        has to be explicitly enabled; it is not the default. The Unicode tables
-        directory at the primary FTP site, which is:
+        correspond to Unicode release 5.0.0.
+        In  addition to the Perl-compatible matching function, PCRE contains an
+        alternative matching function that matches the same  compiled  patterns
+        in  a different way. In certain circumstances, the alternative function
+        has some advantages. For a discussion of the two  matching  algorithms,
+        see the pcrematching page.
+        PCRE  is  written  in C and released as a C library. A number of people
+        have written wrappers and interfaces of various kinds.  In  particular,
+        Google  Inc.   have  provided  a comprehensive C++ wrapper. This is now
+        included as part of the PCRE distribution. The pcrecpp page has details
+        of  this  interface.  Other  people's contributions can be found in the
+        Contrib directory at the primary FTP site, which is:
         ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre
-        Details  of  exactly which Perl regular expression features are and are
+        Details of exactly which Perl regular expression features are  and  are
         not supported by PCRE are given in separate documents. See the pcrepat-
         tern and pcrecompat pages.
-        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
+        data tables that are used by more than one  of  the  exported  external
+        functions,  but  which  are  not  intended for use by external callers.
+        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
+        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
-          pcreapi           details of PCRE's native API
+          pcreapi           details of PCRE's native C API
           pcrebuild         options for building PCRE
           pcrecallout       details of the callout feature
           pcrecompat        discussion of Perl compatibility
+          pcrecpp           details of the C++ wrapper
           pcregrep          description of the pcregrep command
+          pcrematching      discussion of the two matching algorithms
           pcrepartial       details of the partial matching facility
           pcrepattern       syntax and semantics of supported
                               regular expressions
           pcreperform       discussion of performance issues
-          pcreposix         the POSIX-compatible API
+          pcreposix         the POSIX-compatible C API
           pcreprecompile    details of saving and re-using precompiled patterns
           pcresample        discussion of the sample program
+          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 library function, listing its arguments and results.
+        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 will be slower.
+        of execution is slower.
-        All values in repeating quantifiers must be less than 65536.  The maxi-
+        All values in repeating quantifiers must be less than 65536. The  maxi-
-        mum number of capturing subpatterns is 65535.
+        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 non-capturing subpatterns,  but  the
-        maximum  depth  of  nesting  of  all kinds of parenthesized subpattern,
+        There is no limit to the number of parenthesized subpatterns, but there
-        including capturing subpatterns, assertions, and other types of subpat-
+        can be no more than 65535 capturing subpatterns.
-        tern, is 200.
+        The maximum length of name for a named subpattern is 32 characters, and
-        The  maximum  length of a subject string is the largest positive number
+        the maximum number of named subpatterns is 10000.
-        that an integer variable can hold. However, PCRE uses recursion to han-
-        dle  subpatterns  and indefinite repetition. This means that the avail-
+        The maximum length of a subject string is the largest  positive  number
-        able stack space may limit the size of a subject  string  that  can  be
+        that  an integer variable can hold. However, when using the traditional
-        processed by certain patterns.
+        matching function, PCRE uses recursion to handle subpatterns and indef-
+        inite  repetition.  This means that the available stack space may limit
+        the size of a subject string that can be processed by certain patterns.
+        For a discussion of stack issues, see the pcrestack documentation.
  UTF-8 AND UNICODE PROPERTY SUPPORT
-Line 111 
 UTF-8 AND UNICODE PROPERTY SUPPORT
+Line 139 
 UTF-8 AND UNICODE PROPERTY SUPPORT
         If you compile PCRE with UTF-8 support, but do not use it at run  time,
         the  library will be a bit bigger, but the additional run time overhead
-        is limited to testing the PCRE_UTF8 flag in several places,  so  should
+        is limited to testing the PCRE_UTF8 flag occasionally, so should not be
-        not be very large.
+        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-
         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
-        for  a decimal number. A full list is given in the pcrepattern documen-
+        for  a  decimal number, the Unicode script names such as Arabic or Han,
-        tation. The PCRE library is increased in size by about 90K when Unicode
+        and the derived properties Any and L&. A full  list  is  given  in  the
-        property support is included.
+        pcrepattern documentation. Only the short names for properties are sup-
+        ported. For example, \p{L} matches a letter. Its Perl synonym,  \p{Let-
+        ter},  is  not  supported.   Furthermore,  in Perl, many properties may
+        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:
-Line 136 
 UTF-8 AND UNICODE PROPERTY SUPPORT
+Line 168 
 UTF-8 AND UNICODE PROPERTY SUPPORT
         PCRE_NO_UTF8_CHECK is set, the results are undefined. Your program  may
         crash.
-. In a pattern, the escape sequence \x{...}, where the contents of the
+.  An  unbraced  hexadecimal  escape sequence (such as \xb3) matches a
-        braces is a string of hexadecimal digits, is  interpreted  as  a  UTF-8
+        two-byte UTF-8 character if the value is greater than 127.
-        character  whose code number is the given hexadecimal number, for exam-
-        ple: \x{1234}. If a non-hexadecimal digit appears between  the  braces,
-        the item is not recognized.  This escape sequence can be used either as
-        a literal, or within a character class.
-. The original hexadecimal escape sequence, \xhh, matches  a  two-byte
+. Octal numbers up to \777 are recognized, and  match  two-byte  UTF-8
-        UTF-8 character if the value is greater than 127.
+        characters for values greater than \177.
 .  Repeat quantifiers apply to complete UTF-8 characters, not to indi-
         vidual bytes, for example: \x{100}{3}.
-Line 153 
 UTF-8 AND UNICODE PROPERTY SUPPORT
+Line 181 
 UTF-8 AND UNICODE PROPERTY SUPPORT
         gle byte.
 .  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.
+        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
+.  Case-insensitive  matching  applies only to characters whose values
-        are  less than 128, unless PCRE is built with Unicode property support.
+        are less than 128, unless PCRE is built with Unicode property  support.
-        Even when Unicode property support is available, PCRE  still  uses  its
+        Even  when  Unicode  property support is available, PCRE still uses its
-        own  character  tables when checking the case of low-valued characters,
+        own character tables when checking the case of  low-valued  characters,
-        so as not to degrade performance.  The Unicode property information  is
+        so  as not to degrade performance.  The Unicode property information is
-        used only for characters with higher values.
+        used only for characters with higher values. Even when Unicode property
+        support is available, PCRE supports case-insensitive matching only when
+        there is a one-to-one mapping between a letter's  cases.  There  are  a
+        small  number  of  many-to-one  mappings in Unicode; these are not sup-
+        ported by PCRE.
  AUTHOR
-        Philip Hazel <ph10@cam.ac.uk>
+        Philip Hazel
         University Computing Service,
-        Cambridge CB2 3QG, England.
+        Cambridge CB2 3QH, England.
-        Phone: +44 1223 334714
- Last updated: 09 September 2004
+        Putting an actual email address here seems to have been a spam  magnet,
- Copyright (c) 1997-2004 University of Cambridge.
+        so I've taken it away. If you want to email me, use my initial and sur-
- -----------------------------------------------------------------------------
+        name, separated by a dot, at the domain ucs.cam.ac.uk.
+ Last updated: 23 November 2006
+ Copyright (c) 1997-2006 University of Cambridge.
+ ------------------------------------------------------------------------------
- PCRE(3)                                                                PCRE(3)
+ PCREBUILD(3)                                                      PCREBUILD(3)
  NAME
         PCRE - Perl-compatible regular expressions
  PCRE BUILD-TIME OPTIONS
         This  document  describes  the  optional  features  of PCRE that can be
-Line 212 
 PCRE BUILD-TIME OPTIONS
+Line 249 
 PCRE BUILD-TIME OPTIONS
         not described.
+ C++ SUPPORT
+        By default, the configure script will search for a C++ compiler and C++
+        header files. If it finds them, it automatically builds the C++ wrapper
+        library for PCRE. You can disable this by adding
+          --disable-cpp
+        to the configure command.
  UTF-8 SUPPORT
         To build PCRE with support for UTF-8 character strings, add
-Line 245 
 UNICODE CHARACTER PROPERTY SUPPORT
+Line 293 
 UNICODE CHARACTER PROPERTY SUPPORT
  CODE VALUE OF NEWLINE
-        By default, PCRE treats character 10 (linefeed) as the newline  charac-
+        By default, PCRE interprets character 10 (linefeed, LF)  as  indicating
-        ter. This is the normal newline character on Unix-like systems. You can
+        the  end  of  a line. This is the normal newline character on Unix-like
-        compile PCRE to use character 13 (carriage return) instead by adding
+        systems. You can compile PCRE to use character 13 (carriage return, CR)
+        instead, by adding
           --enable-newline-is-cr
-        to the configure command. For completeness there is  also  a  --enable-
+        to  the  configure  command.  There  is  also  a --enable-newline-is-lf
-        newline-is-lf  option,  which explicitly specifies linefeed as the new-
+        option, which explicitly specifies linefeed as the newline character.
-        line character.
+        Alternatively, you can specify that line endings are to be indicated by
+        the two character sequence CRLF. If you want this, add
+          --enable-newline-is-crlf
+        to the configure command. There is a fourth option, specified by
+          --enable-newline-is-any
+        which causes PCRE to recognize any Unicode newline sequence.
+        Whatever  line  ending convention is selected when PCRE is built can be
+        overridden when the library functions are called. At build time  it  is
+        conventional to use the standard for your operating system.
  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 271 
 BUILDING SHARED AND STATIC LIBRARIES
+Line 334 
 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 284 
 POSIX MALLOC USAGE
+Line 347 
 POSIX MALLOC USAGE
         to the configure command.
- LIMITING PCRE RESOURCE USAGE
-        Internally,  PCRE has a function called match(), which it calls repeat-
-        edly (possibly recursively) when matching a pattern. By controlling the
-        maximum  number  of  times  this function may be called during a single
-        matching operation, a limit can be placed on the resources  used  by  a
-        single  call  to  pcre_exec(). The limit can be changed at run time, as
-        described in the pcreapi documentation. The default is 10 million,  but
-        this can be changed by adding a setting such as
-          --with-match-limit=500000
-        to the configure command.
  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.
-        If you build PCRE with an increased link size, test 2 (and  test  5  if
+        If  you  build  PCRE with an increased link size, test 2 (and test 5 if
-        you  are using UTF-8) will fail. Part of the output of these tests is a
+        you are using UTF-8) will fail. Part of the output of these tests is  a
-        representation of the compiled pattern, and this changes with the  link
+        representation  of the compiled pattern, and this changes with the link
         size.
  AVOIDING EXCESSIVE STACK USAGE
-        PCRE  implements  backtracking while matching by making recursive calls
+        When matching with the pcre_exec() function, PCRE implements backtrack-
-        to an internal function called match(). In environments where the  size
+        ing  by  making recursive calls to an internal function called match().
-        of the stack is limited, this can severely limit PCRE's operation. (The
+        In environments where the size of the stack is limited,  this  can  se-
-        Unix environment does not usually suffer from this problem.) An  alter-
+        verely  limit  PCRE's operation. (The Unix environment does not usually
-        native  approach  that  uses  memory  from  the  heap to remember data,
+        suffer from this problem, but it may sometimes be necessary to increase
-        instead of using recursive function calls, has been implemented to work
+        the  maximum  stack size.  There is a discussion in the pcrestack docu-
-        round  this  problem. If you want to build a version of PCRE that works
+        mentation.) An alternative approach to recursion that uses memory  from
-        this way, add
+        the  heap  to remember data, instead of using recursive function calls,
+        has been implemented to work round the problem of limited  stack  size.
+        If you want to build a version of PCRE that works this way, add
           --disable-stack-for-recursion
-        to the configure command. With this configuration, PCRE  will  use  the
+        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.  Separate  functions are provided because the usage is
-        very  predictable:  the  block sizes requested are always the same, and
+        very predictable: the block sizes requested are always  the  same,  and
-        the blocks are always freed in reverse order. A calling  program  might
+        the  blocks  are always freed in reverse order. A calling program might
-        be  able  to implement optimized functions that perform better than the
+        be able to implement optimized functions that perform better  than  the
-        standard malloc() and  free()  functions.  PCRE  runs  noticeably  more
+        standard  malloc()  and  free()  functions.  PCRE  runs noticeably more
-        slowly when built in this way.
+        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-
+        edly  (sometimes  recursively)  when  matching  a  pattern   with   the
+        pcre_exec()  function.  By controlling the maximum number of times this
+        function may be called during a single matching operation, a limit  can
+        be  placed  on  the resources used by a single call to pcre_exec(). The
+        limit can be changed at run time, as described in the pcreapi  documen-
+        tation.  The default is 10 million, but this can be changed by adding a
+        setting such as
+          --with-match-limit=500000
+        to  the  configure  command.  This  setting  has  no  effect   on   the
+        pcre_dfa_exec() matching function.
+        In  some  environments  it is desirable to limit the depth of recursive
+        calls of match() more strictly than the total number of calls, in order
+        to  restrict  the maximum amount of stack (or heap, if --disable-stack-
+        for-recursion is specified) that is used. A second limit controls this;
+        it  defaults  to  the  value  that is set for --with-match-limit, which
+        imposes no additional constraints. However, you can set a  lower  limit
+        by adding, for example,
+          --with-match-limit-recursion=10000
+        to  the  configure  command.  This  value can also be overridden at run
+        time.
  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
+        PCRE can, however, be compiled to  run  in  an  EBCDIC  environment  by
         adding
           --enable-ebcdic
         to the configure command.
- Last updated: 09 September 2004
- Copyright (c) 1997-2004 University of Cambridge.
- -----------------------------------------------------------------------------
- PCRE(3)                                                                PCRE(3)
+ SEE ALSO
+        pcreapi(3), pcre_config(3).
+ Last updated: 30 November 2006
+ Copyright (c) 1997-2006 University of Cambridge.
+ ------------------------------------------------------------------------------
+ PCREMATCHING(3)                                                PCREMATCHING(3)
  NAME
         PCRE - Perl-compatible regular expressions
+ PCRE MATCHING ALGORITHMS
+        This document describes the two different algorithms that are available
+        in PCRE for matching a compiled regular expression against a given sub-
+        ject  string.  The  "standard"  algorithm  is  the  one provided by the
+        pcre_exec() function.  This works in the same was  as  Perl's  matching
+        function, and provides a Perl-compatible matching operation.
+        An  alternative  algorithm is provided by the pcre_dfa_exec() function;
+        this operates in a different way, and is not  Perl-compatible.  It  has
+        advantages  and disadvantages compared with the standard algorithm, and
+        these are described below.
+        When there is only one possible way in which a given subject string can
+        match  a pattern, the two algorithms give the same answer. A difference
+        arises, however, when there are multiple possibilities. For example, if
+        the pattern
+          ^<.*>
+        is matched against the string
+          <something> <something else> <something further>
+        there are three possible answers. The standard algorithm finds only one
+        of them, whereas the alternative algorithm finds all three.
+ REGULAR EXPRESSIONS AS TREES
+        The set of strings that are matched by a regular expression can be rep-
+        resented  as  a  tree structure. An unlimited repetition in the pattern
+        makes the tree of infinite size, but it is still a tree.  Matching  the
+        pattern  to a given subject string (from a given starting point) can be
+        thought of as a search of the tree.  There are two  ways  to  search  a
+        tree:  depth-first  and  breadth-first, and these correspond to the two
+        matching algorithms provided by PCRE.
+ THE STANDARD MATCHING ALGORITHM
+        In the terminology of Jeffrey Friedl's book Mastering  Regular  Expres-
+        sions,  the  standard  algorithm  is  an "NFA algorithm". It conducts a
+        depth-first search of the pattern tree. That is, it  proceeds  along  a
+        single path through the tree, checking that the subject matches what is
+        required. When there is a mismatch, the algorithm  tries  any  alterna-
+        tives  at  the  current point, and if they all fail, it backs up to the
+        previous branch point in the  tree,  and  tries  the  next  alternative
+        branch  at  that  level.  This often involves backing up (moving to the
+        left) in the subject string as well.  The  order  in  which  repetition
+        branches  are  tried  is controlled by the greedy or ungreedy nature of
+        the quantifier.
+        If a leaf node is reached, a matching string has  been  found,  and  at
+        that  point the algorithm stops. Thus, if there is more than one possi-
+        ble match, this algorithm returns the first one that it finds.  Whether
+        this  is the shortest, the longest, or some intermediate length depends
+        on the way the greedy and ungreedy repetition quantifiers are specified
+        in the pattern.
+        Because  it  ends  up  with a single path through the tree, it is rela-
+        tively straightforward for this algorithm to keep  track  of  the  sub-
+        strings  that  are  matched  by portions of the pattern in parentheses.
+        This provides support for capturing parentheses and back references.
+ THE ALTERNATIVE MATCHING ALGORITHM
+        This algorithm conducts a breadth-first search of  the  tree.  Starting
+        from  the  first  matching  point  in the subject, it scans the subject
+        string from left to right, once, character by character, and as it does
+        this,  it remembers all the paths through the tree that represent valid
+        matches. In Friedl's terminology, this is a kind  of  "DFA  algorithm",
+        though  it is not implemented as a traditional finite state machine (it
+        keeps multiple states active simultaneously).
+        The scan continues until either the end of the subject is  reached,  or
+        there  are  no more unterminated paths. At this point, terminated paths
+        represent the different matching possibilities (if there are none,  the
+        match  has  failed).   Thus,  if there is more than one possible match,
+        this algorithm finds all of them, and in particular, it finds the long-
+        est.  In PCRE, there is an option to stop the algorithm after the first
+        match (which is necessarily the shortest) has been found.
+        Note that all the matches that are found start at the same point in the
+        subject. If the pattern
+          cat(er(pillar)?)
+        is  matched  against the string "the caterpillar catchment", the result
+        will be the three strings "cat", "cater", and "caterpillar" that  start
+        at the fourth character of the subject. The algorithm does not automat-
+        ically move on to find matches that start at later positions.
+        There are a number of features of PCRE regular expressions that are not
+        supported by the alternative matching algorithm. They are as follows:
+.  Because  the  algorithm  finds  all possible matches, the greedy or
+        ungreedy nature of repetition quantifiers is not relevant.  Greedy  and
+        ungreedy quantifiers are treated in exactly the same way. However, pos-
+        sessive quantifiers can make a difference when what follows could  also
+        match what is quantified, for example in a pattern like this:
+          ^a++\w!
+        This  pattern matches "aaab!" but not "aaa!", which would be matched by
+        a non-possessive quantifier. Similarly, if an atomic group is  present,
+        it  is matched as if it were a standalone pattern at the current point,
+        and the longest match is then "locked in" for the rest of  the  overall
+        pattern.
+. When dealing with multiple paths through the tree simultaneously, it
+        is not straightforward to keep track of  captured  substrings  for  the
+        different  matching  possibilities,  and  PCRE's implementation of this
+        algorithm does not attempt to do this. This means that no captured sub-
+        strings are available.
+.  Because no substrings are captured, back references within the pat-
+        tern are not supported, and cause errors if encountered.
+. For the same reason, conditional expressions that use  a  backrefer-
+        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
+        always 1, and the value of the capture_last field is always -1.
+.  The \C escape sequence, which (in the standard algorithm) matches a
+        single byte, even in UTF-8 mode, is not supported because the  alterna-
+        tive  algorithm  moves  through  the  subject string one character at a
+        time, for all active paths through the tree.
+ ADVANTAGES OF THE ALTERNATIVE ALGORITHM
+        Using the alternative matching algorithm provides the following  advan-
+        tages:
+. All possible matches (at a single point in the subject) are automat-
+        ically found, and in particular, the longest match is  found.  To  find
+        more than one match using the standard algorithm, you have to do kludgy
+        things with callouts.
+. There is much better support for partial matching. The  restrictions
+        on  the content of the pattern that apply when using the standard algo-
+        rithm for partial matching do not apply to the  alternative  algorithm.
+        For  non-anchored patterns, the starting position of a partial match is
+        available.
+. Because the alternative algorithm  scans  the  subject  string  just
+        once,  and  never  needs to backtrack, it is possible to pass very long
+        subject strings to the matching function in  several  pieces,  checking
+        for partial matching each time.
+ DISADVANTAGES OF THE ALTERNATIVE ALGORITHM
+        The alternative algorithm suffers from a number of disadvantages:
+.  It  is  substantially  slower  than the standard algorithm. This is
+        partly because it has to search for all possible matches, but  is  also
+        because it is less susceptible to optimization.
+. Capturing parentheses and back references are not supported.
+. Although atomic groups are supported, their use does not provide the
+        performance advantage that it does for the standard algorithm.
+ Last updated: 24 November 2006
+ Copyright (c) 1997-2006 University of Cambridge.
+ ------------------------------------------------------------------------------
+ PCREAPI(3)                                                          PCREAPI(3)
+ NAME
+        PCRE - Perl-compatible regular expressions
  PCRE NATIVE API
         #include <pcre.h>
-Line 375 
 PCRE NATIVE API
+Line 642 
 PCRE NATIVE API
              const char **errptr, int *erroffset,
              const unsigned char *tableptr);
+        pcre *pcre_compile2(const char *pattern, int options,
+             int *errorcodeptr,
+             const char **errptr, int *erroffset,
+             const unsigned char *tableptr);
         pcre_extra *pcre_study(const pcre *code, int options,
              const char **errptr);
-Line 382 
 PCRE NATIVE API
+Line 654 
 PCRE NATIVE API
              const char *subject, int length, int startoffset,
              int options, int *ovector, int ovecsize);
+        int pcre_dfa_exec(const pcre *code, const pcre_extra *extra,
+             const char *subject, int length, int startoffset,
+             int options, int *ovector, int ovecsize,
+             int *workspace, int wscount);
         int pcre_copy_named_substring(const pcre *code,
              const char *subject, int *ovector,
              int stringcount, const char *stringname,
-Line 399 
 PCRE NATIVE API
+Line 676 
 PCRE NATIVE API
         int pcre_get_stringnumber(const pcre *code,
              const char *name);
+        int pcre_get_stringtable_entries(const pcre *code,
+             const char *name, char **first, char **last);
         int pcre_get_substring(const char *subject, int *ovector,
              int stringcount, int stringnumber,
              const char **stringptr);
-Line 417 
 PCRE NATIVE API
+Line 697 
 PCRE NATIVE API
         int pcre_info(const pcre *code, int *optptr, int *firstcharptr);
+        int pcre_refcount(pcre *code, int adjust);
         int pcre_config(int what, void *where);
         char *pcre_version(void);
-Line 435 
 PCRE NATIVE API
+Line 717 
 PCRE NATIVE API
  PCRE API OVERVIEW
         PCRE has its own native API, which is described in this document. There
-        is also a set of wrapper functions that correspond to the POSIX regular
+        are also some wrapper functions that correspond to  the  POSIX  regular
-        expression API.  These are described in the pcreposix documentation.
+        expression  API.  These  are  described in the pcreposix documentation.
+        Both of these APIs define a set of C function calls. A C++  wrapper  is
+        distributed with PCRE. It is documented in the pcrecpp page.
-        The  native  API  function  prototypes  are  defined in the header file
+        The  native  API  C  function prototypes are defined in the header file
-        pcre.h, and on Unix systems the library itself is  called  libpcre.  It
+        pcre.h, and on Unix systems the library itself is called  libpcre.   It
         can normally be accessed by adding -lpcre to the command for linking an
         application  that  uses  PCRE.  The  header  file  defines  the  macros
         PCRE_MAJOR  and  PCRE_MINOR to contain the major and minor release num-
         bers for the library.  Applications can use these  to  include  support
         for different releases of PCRE.
-        The  functions  pcre_compile(),  pcre_study(), and pcre_exec() are used
+        The   functions   pcre_compile(),  pcre_compile2(),  pcre_study(),  and
-        for compiling and matching regular expressions. A sample  program  that
+        pcre_exec() are used for compiling and matching regular expressions  in
-        demonstrates  the  simplest  way  of using them is provided in the file
+        a  Perl-compatible  manner. A sample program that demonstrates the sim-
-        called pcredemo.c in the source distribution. The pcresample documenta-
+        plest way of using them is provided in the file  called  pcredemo.c  in
-        tion describes how to run it.
+        the  source distribution. The pcresample documentation describes how to
+        run it.
-        In  addition  to  the  main compiling and matching functions, there are
-        convenience functions for extracting captured substrings from a matched
+        A second matching function, pcre_dfa_exec(), which is not Perl-compati-
-        subject string.  They are:
+        ble,  is  also provided. This uses a different algorithm for the match-
+        ing. The alternative algorithm finds all possible matches (at  a  given
+        point  in  the subject), and scans the subject just once. However, this
+        algorithm does not return captured substrings. A description of the two
+        matching  algorithms and their advantages and disadvantages is given in
+        the pcrematching documentation.
+        In addition to the main compiling and  matching  functions,  there  are
+        convenience functions for extracting captured substrings from a subject
+        string that is matched by pcre_exec(). They are:
           pcre_copy_substring()
           pcre_copy_named_substring()
-Line 462 
 PCRE API OVERVIEW
+Line 755 
 PCRE API OVERVIEW
           pcre_get_named_substring()
           pcre_get_substring_list()
           pcre_get_stringnumber()
+          pcre_get_stringtable_entries()
         pcre_free_substring() and pcre_free_substring_list() are also provided,
         to free the memory used for extracted strings.
-        The function pcre_maketables() is used to  build  a  set  of  character
+        The  function  pcre_maketables()  is  used  to build a set of character
-        tables   in  the  current  locale  for  passing  to  pcre_compile()  or
+        tables  in  the  current  locale   for   passing   to   pcre_compile(),
-        pcre_exec().  This is an optional facility that is  provided  for  spe-
+        pcre_exec(),  or  pcre_dfa_exec(). This is an optional facility that is
-        cialist use. Most commonly, no special tables are passed, in which case
+        provided for specialist use.  Most  commonly,  no  special  tables  are
-        internal tables that are generated when PCRE is built are used.
+        passed,  in  which case internal tables that are generated when PCRE is
+        built are used.
         The function pcre_fullinfo() is used to find out  information  about  a
         compiled  pattern; pcre_info() is an obsolete version that returns only
-Line 478 
 PCRE API OVERVIEW
+Line 773 
 PCRE API OVERVIEW
         patibility.   The function pcre_version() returns a pointer to a string
         containing the version of PCRE and its date of release.
+        The function pcre_refcount() maintains a  reference  count  in  a  data
+        block  containing  a compiled pattern. This is provided for the benefit
+        of object-oriented applications.
         The global variables pcre_malloc and pcre_free  initially  contain  the
         entry  points  of  the  standard malloc() and free() functions, respec-
         tively. PCRE calls the memory management functions via these variables,
-Line 487 
 PCRE API OVERVIEW
+Line 786 
 PCRE API OVERVIEW
         The global variables pcre_stack_malloc  and  pcre_stack_free  are  also
         indirections  to  memory  management functions. These special functions
         are used only when PCRE is compiled to use  the  heap  for  remembering
-        data,  instead  of recursive function calls. This is a non-standard way
+        data, instead of recursive function calls, when running the pcre_exec()
-        of building PCRE, for use in environments  that  have  limited  stacks.
+        function. See the pcrebuild documentation for  details  of  how  to  do
-        Because  of  the greater use of memory management, it runs more slowly.
+        this.  It  is  a non-standard way of building PCRE, for use in environ-
-        Separate functions are provided so that special-purpose  external  code
+        ments that have limited stacks. Because of the greater  use  of  memory
-        can be used for this case. When used, these functions are always called
+        management,  it  runs  more  slowly. Separate functions are provided so
-        in a stack-like manner (last obtained, first  freed),  and  always  for
+        that special-purpose external code can be  used  for  this  case.  When
-        memory blocks of the same size.
+        used,  these  functions  are always called in a stack-like manner (last
+        obtained, first freed), and always for memory blocks of the same  size.
+        There  is  a discussion about PCRE's stack usage in the pcrestack docu-
+        mentation.
         The global variable pcre_callout initially contains NULL. It can be set
-        by the caller to a "callout" function, which PCRE  will  then  call  at
+        by  the  caller  to  a "callout" function, which PCRE will then call at
-        specified  points during a matching operation. Details are given in the
+        specified points during a matching operation. Details are given in  the
         pcrecallout documentation.
+ NEWLINES
+        PCRE  supports four 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, or any Unicode new-
+        line sequence.  The Unicode newline sequences are the three  just  men-
+        tioned, plus the single characters VT (vertical tab, U+000B), FF (form-
+        feed, U+000C), NEL (next line, U+0085), LS  (line  separator,  U+2028),
+        and PS (paragraph separator, U+2029).
+        Each  of  the first three conventions is used by at least one operating
+        system as its standard newline sequence. When PCRE is built, a  default
+        can  be  specified.  The default default is LF, which is the Unix stan-
+        dard. When PCRE is run, the default can be overridden,  either  when  a
+        pattern is compiled, or when it is matched.
+        In the PCRE documentation the word "newline" is used to mean "the char-
+        acter or pair of characters that indicate a line break". The choice  of
+        newline  convention  affects  the  handling of the dot, circumflex, and
+        dollar metacharacters, the handling of #-comments in /x mode, and, when
+        CRLF  is a recognized line ending sequence, the match position advance-
+        ment for a non-anchored pattern. The choice of newline convention  does
+        not affect the interpretation of the \n or \r escape sequences.
  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 516 
 MULTITHREADING
+Line 843 
 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.
-Line 525 
 CHECKING BUILD-TIME OPTIONS
+Line 852 
 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 that is set to the value of the code that is
+        The output is an integer whose value specifies  the  default  character
-        used for the newline character. It is either linefeed (10) or  carriage
+        sequence  that is recognized as meaning "newline". The four values that
-        return  (13),  and  should  normally be the standard character for your
+        are supported are: 10 for LF, 13 for CR, 3338 for CRLF, and -1 for ANY.
-        operating system.
+        The default should normally be the standard sequence for your operating
+        system.
           PCRE_CONFIG_LINK_SIZE
-Line 573 
 CHECKING BUILD-TIME OPTIONS
+Line 901 
 CHECKING BUILD-TIME OPTIONS
         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
+        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 is
+        The  output is an integer that is set to one if internal recursion when
-        implemented by recursive function calls that use the stack to  remember
+        running pcre_exec() is implemented by recursive function calls that use
-        their state. This is the usual way that PCRE is compiled. The output is
+        the  stack  to remember their state. This is the usual way that PCRE is
-        zero if PCRE was compiled to use blocks of data on the heap instead  of
+        compiled. The output is zero if PCRE was compiled to use blocks of data
-        recursive   function   calls.   In  this  case,  pcre_stack_malloc  and
+        on  the  heap  instead  of  recursive  function  calls.  In  this case,
-        pcre_stack_free are called to manage memory blocks on  the  heap,  thus
+        pcre_stack_malloc and  pcre_stack_free  are  called  to  manage  memory
-        avoiding the use of the stack.
+        blocks on the heap, thus avoiding the use of the stack.
  COMPILING A PATTERN
-Line 590 
 COMPILING A PATTERN
+Line 924 
 COMPILING A PATTERN
              const char **errptr, int *erroffset,
              const unsigned char *tableptr);
-        The  function  pcre_compile()  is  called  to compile a pattern into an
+        pcre *pcre_compile2(const char *pattern, int options,
-        internal form. The pattern is a C string terminated by a  binary  zero,
+             int *errorcodeptr,
-        and  is  passed in the pattern argument. A pointer to a single block of
+             const char **errptr, int *erroffset,
-        memory that is obtained via pcre_malloc is returned. This contains  the
+             const unsigned char *tableptr);
-        compiled  code  and  related  data.  The  pcre  type is defined for the
-        returned block; this is a typedef for a structure  whose  contents  are
+        Either of the functions pcre_compile() or pcre_compile2() can be called
-        not  externally defined. It is up to the caller to free the memory when
+        to compile a pattern into an internal form. The only difference between
-        it is no longer required.
+        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
+        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
         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-
         ment, which is an address (see below).
-        The options argument contains independent bits that affect the compila-
+        The options argument contains various bit settings that affect the com-
-        tion. It should be zero if  no  options  are  required.  The  available
+        pilation. It should be zero if no options are required.  The  available
         options  are  described  below. Some of them, in particular, those that
         are compatible with Perl, can also be set and  unset  from  within  the
         pattern  (see  the  detailed  description in the pcrepattern documenta-
         tion). For these options, the contents of the options  argument  speci-
         fies  their initial settings at the start of compilation and execution.
-        The PCRE_ANCHORED option can be set at the time of matching as well  as
+        The PCRE_ANCHORED and PCRE_NEWLINE_xxx options can be set at  the  time
-        at compile time.
+        of matching as well as at compile time.
         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,
         if compilation of a pattern fails,  pcre_compile()  returns  NULL,  and
         sets the variable pointed to by errptr to point to a textual error mes-
-        sage. The offset from the start of the pattern to the  character  where
+        sage. This is a static string that is part of the library. You must not
-        the  error  was  discovered  is  placed  in  the variable pointed to by
+        try to free it. The offset from the start of the pattern to the charac-
-        erroffset, which must not be NULL. If it  is,  an  immediate  error  is
+        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
         given.
+        If pcre_compile2() is used instead of pcre_compile(),  and  the  error-
+        codeptr  argument is not NULL, a non-zero error code number is returned
+        via this argument in the event of an error. This is in addition to  the
+        textual error message. Error codes and messages are listed below.
         If  the  final  argument, tableptr, is NULL, PCRE uses a default set of
         character tables that are  built  when  PCRE  is  compiled,  using  the
         default  C  locale.  Otherwise, tableptr must be an address that is the
-Line 664 
 COMPILING A PATTERN
+Line 1013 
 COMPILING A PATTERN
         If  this  bit is set, letters in the pattern match both upper and lower
         case letters. It is equivalent to Perl's  /i  option,  and  it  can  be
-        changed  within  a  pattern  by  a (?i) option setting. When running in
+        changed  within a pattern by a (?i) option setting. In UTF-8 mode, PCRE
-        UTF-8 mode, case support for high-valued characters is  available  only
+        always understands the concept of case for characters whose values  are
-        when PCRE is built with Unicode character property support.
+        less  than 128, so caseless matching is always possible. For characters
+        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
+        use caseless matching for characters 128 and  above,  you  must  ensure
+        that  PCRE  is  compiled  with Unicode property support as well as with
+        UTF-8 support.
           PCRE_DOLLAR_ENDONLY
-        If  this bit is set, a dollar metacharacter in the pattern matches only
+        If this bit is set, a dollar metacharacter in the pattern matches  only
-        at the end of the subject string. Without this option,  a  dollar  also
+        at  the  end  of the subject string. Without this option, a dollar also
-        matches  immediately before the final character if it is a newline (but
+        matches immediately before a newline at the end of the string (but  not
-        not before any  other  newlines).  The  PCRE_DOLLAR_ENDONLY  option  is
+        before  any  other newlines). The PCRE_DOLLAR_ENDONLY option is ignored
-        ignored if PCRE_MULTILINE is set. There is no equivalent to this option
+        if PCRE_MULTILINE is set.  There is no equivalent  to  this  option  in
-        in Perl, and no way to set it within a pattern.
+        Perl, and no way to set it within a pattern.
           PCRE_DOTALL
         If this bit is set, a dot metacharater in the pattern matches all char-
-        acters,  including  newlines.  Without  it, newlines are excluded. This
+        acters, including those that indicate newline. Without it, a  dot  does
-        option is equivalent to Perl's /s option, and it can be changed  within
+        not  match  when  the  current position is at a newline. This option is
-        a  pattern  by  a  (?s)  option  setting. A negative class such as [^a]
+        equivalent to Perl's /s option, and it can be changed within a  pattern
-        always matches a newline character, independent of the setting of  this
+        by  a (?s) option setting. A negative class such as [^a] always matches
-        option.
+        newline characters, independent of the setting of this option.
+          PCRE_DUPNAMES
+        If this bit is set, names used to identify capturing  subpatterns  need
+        not be unique. This can be helpful for certain types of pattern when it
+        is known that only one instance of the named  subpattern  can  ever  be
+        matched.  There  are  more details of named subpatterns below; see also
+        the pcrepattern documentation.
           PCRE_EXTENDED
-        If  this  bit  is  set,  whitespace  data characters in the pattern are
+        If this bit is set, whitespace  data  characters  in  the  pattern  are
-        totally ignored except  when  escaped  or  inside  a  character  class.
+        totally ignored except when escaped or inside a character class. White-
-        Whitespace  does  not  include the VT character (code 11). In addition,
+        space does not include the VT character (code 11). In addition, charac-
-        characters between an unescaped # outside a  character  class  and  the
+        ters between an unescaped # outside a character class and the next new-
-        next newline character, inclusive, are also ignored. This is equivalent
+        line, inclusive, are also ignored. This  is  equivalent  to  Perl's  /x
-        to Perl's /x option, and it can be changed within a pattern by  a  (?x)
+        option,  and  it  can be changed within a pattern by a (?x) option set-
-        option setting.
+        ting.
-        This  option  makes  it possible to include comments inside complicated
+        This option makes it possible to include  comments  inside  complicated
-        patterns.  Note, however, that this applies only  to  data  characters.
+        patterns.   Note,  however,  that this applies only to data characters.
-        Whitespace   characters  may  never  appear  within  special  character
+        Whitespace  characters  may  never  appear  within  special   character
-        sequences in a pattern, for  example  within  the  sequence  (?(  which
+        sequences  in  a  pattern,  for  example  within the sequence (?( which
         introduces a conditional subpattern.
           PCRE_EXTRA
-        This  option  was invented in order to turn on additional functionality
+        This option was invented in order to turn on  additional  functionality
-        of PCRE that is incompatible with Perl, but it  is  currently  of  very
+        of  PCRE  that  is  incompatible with Perl, but it is currently of very
-        little  use. When set, any backslash in a pattern that is followed by a
+        little use. When set, any backslash in a pattern that is followed by  a
-        letter that has no special meaning  causes  an  error,  thus  reserving
+        letter  that  has  no  special  meaning causes an error, thus reserving
-        these  combinations  for  future  expansion.  By default, as in Perl, a
+        these combinations for future expansion. By  default,  as  in  Perl,  a
-        backslash followed by a letter with no special meaning is treated as  a
+        backslash  followed by a letter with no special meaning is treated as a
-        literal.  There  are  at  present  no other features controlled by this
+        literal. (Perl can, however, be persuaded to give a warning for  this.)
-        option. It can also be set by a (?X) option setting within a pattern.
+        There  are  at  present no other features controlled by this option. It
+        can also be set by a (?X) option setting within a pattern.
+          PCRE_FIRSTLINE
+        If this option is set, an  unanchored  pattern  is  required  to  match
+        before  or  at  the  first  newline  in  the subject string, though the
+        matched text may continue over the newline.
           PCRE_MULTILINE
-Line 723 
 COMPILING A PATTERN
+Line 1092 
 COMPILING A PATTERN
         is set). This is the same as Perl.
         When  PCRE_MULTILINE  it  is set, the "start of line" and "end of line"
-        constructs match immediately following or immediately before  any  new-
+        constructs match immediately following or immediately  before  internal
-        line  in the subject string, respectively, as well as at the very start
+        newlines  in  the  subject string, respectively, as well as at the very
-        and end. This is equivalent to Perl's /m option, and it can be  changed
+        start and end. This is equivalent to Perl's /m option, and  it  can  be
-        within a pattern by a (?m) option setting. If there are no "\n" charac-
+        changed within a pattern by a (?m) option setting. If there are no new-
-        ters in a subject string, or no occurrences of ^ or  $  in  a  pattern,
+        lines in a subject string, or no occurrences of ^ or $  in  a  pattern,
         setting PCRE_MULTILINE has no effect.
+          PCRE_NEWLINE_CR
+          PCRE_NEWLINE_LF
+          PCRE_NEWLINE_CRLF
+          PCRE_NEWLINE_ANY
+        These  options  override the default newline definition that was chosen
+        when PCRE was built. Setting the first or the second specifies  that  a
+        newline  is  indicated  by a single character (CR or LF, respectively).
+        Setting PCRE_NEWLINE_CRLF specifies that a newline is indicated by  the
+        two-character  CRLF  sequence.  Setting PCRE_NEWLINE_ANY specifies that
+        any Unicode newline sequence should be recognized. The Unicode  newline
+        sequences  are  the three just mentioned, plus the single characters VT
+        (vertical tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085),
+        LS  (line separator, U+2028), and PS (paragraph separator, U+2029). The
+        last two are recognized only in UTF-8 mode.
+        The newline setting in the  options  word  uses  three  bits  that  are
+        treated  as  a  number, giving eight possibilities. Currently only five
+        are used (default plus the four values above). This means that  if  you
+        set  more  than  one  newline option, the combination may or may not be
+        sensible. For example, PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is  equiva-
+        lent  to PCRE_NEWLINE_CRLF, but other combinations yield unused numbers
+        and cause an error.
+        The only time that a line break is specially recognized when  compiling
+        a  pattern  is  if  PCRE_EXTENDED  is set, and an unescaped # outside a
+        character class is encountered. This indicates  a  comment  that  lasts
+        until  after the next line break sequence. In other circumstances, line
+        break  sequences  are  treated  as  literal  data,   except   that   in
+        PCRE_EXTENDED mode, both CR and LF are treated as whitespace characters
+        and are therefore ignored.
+        The newline option that is set at compile time becomes the default that
+        is  used for pcre_exec() and pcre_dfa_exec(), but it can be overridden.
           PCRE_NO_AUTO_CAPTURE
         If this option is set, it disables the use of numbered capturing paren-
-        theses in the pattern. Any opening parenthesis that is not followed  by
+        theses  in the pattern. Any opening parenthesis that is not followed by
-        ?  behaves as if it were followed by ?: but named parentheses can still
+        ? behaves as if it were followed by ?: but named parentheses can  still
-        be used for capturing (and they acquire  numbers  in  the  usual  way).
+        be  used  for  capturing  (and  they acquire numbers in the usual way).
         There is no equivalent of this option in Perl.
           PCRE_UNGREEDY
-        This  option  inverts  the "greediness" of the quantifiers so that they
+        This option inverts the "greediness" of the quantifiers  so  that  they
-        are not greedy by default, but become greedy if followed by "?". It  is
+        are  not greedy by default, but become greedy if followed by "?". It is
-        not  compatible  with Perl. It can also be set by a (?U) option setting
+        not compatible with Perl. It can also be set by a (?U)  option  setting
         within the pattern.
           PCRE_UTF8
-        This option causes PCRE to regard both the pattern and the  subject  as
+        This  option  causes PCRE to regard both the pattern and the subject as
-        strings  of  UTF-8 characters instead of single-byte character strings.
+        strings of UTF-8 characters instead of single-byte  character  strings.
-        However, it is available only when PCRE is built to include UTF-8  sup-
+        However,  it is available only when PCRE is built to include UTF-8 sup-
-        port.  If not, the use of this option provokes an error. Details of how
+        port. If not, the use of this option provokes an error. Details of  how
-        this option changes the behaviour of PCRE are given in the  section  on
+        this  option  changes the behaviour of PCRE are given in the section on
         UTF-8 support in the main pcre page.
           PCRE_NO_UTF8_CHECK
         When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
-        automatically checked. If an invalid UTF-8 sequence of bytes is  found,
+        automatically  checked. If an invalid UTF-8 sequence of bytes is found,
-        pcre_compile()  returns an error. If you already know that your pattern
+        pcre_compile() returns an error. If you already know that your  pattern
-        is valid, and you want to skip this check for performance reasons,  you
+        is  valid, and you want to skip this check for performance reasons, you
-        can  set  the  PCRE_NO_UTF8_CHECK option. When it is set, the effect of
+        can set the PCRE_NO_UTF8_CHECK option. When it is set,  the  effect  of
         passing an invalid UTF-8 string as a pattern is undefined. It may cause
-        your  program  to  crash.   Note that this option can also be passed to
+        your program to crash.  Note that this option can  also  be  passed  to
-        pcre_exec(),  to  suppress  the  UTF-8  validity  checking  of  subject
+        pcre_exec()  and pcre_dfa_exec(), to suppress the UTF-8 validity check-
-        strings.
+        ing of subject strings.
+ COMPILATION ERROR CODES
+        The following table lists the error  codes  than  may  be  returned  by
+        pcre_compile2(),  along with the error messages that may be returned by
+        both compiling functions. As PCRE has developed, some error codes  have
+        fallen out of use. To avoid confusion, they have not been re-used.
+ no error
+ \ at end of pattern
+ \c at end of pattern
+ unrecognized character follows \
+ numbers out of order in {} quantifier
+ number too big in {} quantifier
+ missing terminating ] for character class
+ invalid escape sequence in character class
+ range out of order in character class
+ nothing to repeat
+ [this code is not in use]
+ internal error: unexpected repeat
+ unrecognized character after (?
+ POSIX named classes are supported only within a class
+ missing )
+ reference to non-existent subpattern
+ erroffset passed as NULL
+ unknown option bit(s) set
+ missing ) after comment
+ [this code is not in use]
+ regular expression too large
+ failed to get memory
+ unmatched parentheses
+ internal error: code overflow
+ unrecognized character after (?<
+ lookbehind assertion is not fixed length
+ malformed number or name after (?(
+ conditional group contains more than two branches
+ assertion expected after (?(
+ (?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
+ [this code is not in use]
+ character value in \x{...} sequence is too large
+ invalid condition (?(0)
+ \C not allowed in lookbehind assertion
+ PCRE does not support \L, \l, \N, \U, or \u
+ number after (?C is > 255
+ closing ) for (?C expected
+ recursive call could loop indefinitely
+ unrecognized character after (?P
+ syntax error in subpattern name (missing terminator)
+ two named subpatterns have the same name
+ invalid UTF-8 string
+ support for \P, \p, and \X has not been compiled
+ malformed \P or \p sequence
+ unknown property name after \P or \p
+ subpattern name is too long (maximum 32 characters)
+ too many named subpatterns (maximum 10,000)
+ repeated subpattern is too long
+ 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"
  STUDYING A PATTERN
-        pcre_extra *pcre_study(const pcre *code, int options,
+        pcre_extra *pcre_study(const pcre *code, int options
              const char **errptr);
-        If  a  compiled  pattern is going to be used several times, it is worth
+        If a compiled pattern is going to be used several times,  it  is  worth
         spending more time analyzing it in order to speed up the time taken for
-        matching.  The function pcre_study() takes a pointer to a compiled pat-
+        matching. The function pcre_study() takes a pointer to a compiled  pat-
         tern as its first argument. If studying the pattern produces additional
-        information  that  will  help speed up matching, pcre_study() returns a
+        information that will help speed up matching,  pcre_study()  returns  a
-        pointer to a pcre_extra block, in which the study_data field points  to
+        pointer  to a pcre_extra block, in which the study_data field points to
         the results of the study.
         The  returned  value  from  pcre_study()  can  be  passed  directly  to
-        pcre_exec(). However, a pcre_extra block  also  contains  other  fields
+        pcre_exec().  However,  a  pcre_extra  block also contains other fields
-        that  can  be  set  by the caller before the block is passed; these are
+        that can be set by the caller before the block  is  passed;  these  are
         described below in the section on matching a pattern.
-        If studying the pattern does not produce  any  additional  information,
+        If  studying  the  pattern  does not produce any additional information
         pcre_study() returns NULL. In that circumstance, if the calling program
-        wants to pass any of the other fields to pcre_exec(), it  must  set  up
+        wants  to  pass  any of the other fields to pcre_exec(), it must set up
         its own pcre_extra block.
-        The  second  argument of pcre_study() contains option bits. At present,
+        The second argument of pcre_study() contains option bits.  At  present,
         no options are defined, and this argument should always be zero.
-        The third argument for pcre_study() is a pointer for an error  message.
+        The  third argument for pcre_study() is a pointer for an error message.
-        If  studying  succeeds  (even  if no data is returned), the variable it
+        If studying succeeds (even if no data is  returned),  the  variable  it
-        points to is set to NULL. Otherwise it points to a textual  error  mes-
+        points  to  is  set  to NULL. Otherwise it is set to point to a textual
-        sage.  You should therefore test the error pointer for NULL after call-
+        error message. This is a static string that is part of the library. You
-        ing pcre_study(), to be sure that it has run successfully.
+        must  not  try  to  free it. You should test the error pointer for NULL
+        after calling pcre_study(), to be sure that it has run successfully.
         This is a typical call to pcre_study():
-Line 815 
 STUDYING A PATTERN
+Line 1287 
 STUDYING A PATTERN
  LOCALE SUPPORT
         PCRE handles caseless matching, and determines whether  characters  are
-        letters,  digits, or whatever, by reference to a set of tables, indexed
+        letters  digits,  or whatever, by reference to a set of tables, indexed
-        by character value. (When running in UTF-8 mode, this applies  only  to
+        by character value. When running in UTF-8 mode, this  applies  only  to
         characters  with  codes  less than 128. Higher-valued codes never match
         escapes such as \w or \d, but can be tested with \p if  PCRE  is  built
-        with Unicode character property support.)
+        with  Unicode  character property support. The use of locales with Uni-
+        code is discouraged.
-        An  internal set of tables is created in the default C locale when PCRE
+        An internal set of tables is created in the default C locale when  PCRE
-        is built. This is used when the final  argument  of  pcre_compile()  is
+        is  built.  This  is  used when the final argument of pcre_compile() is
-        NULL,  and  is  sufficient for many applications. An alternative set of
+        NULL, and is sufficient for many applications. An  alternative  set  of
-        tables can, however, be supplied. These may be created in  a  different
+        tables  can,  however, be supplied. These may be created in a different
-        locale  from the default. As more and more applications change to using
+        locale from the default. As more and more applications change to  using
         Unicode, the need for this locale support is expected to die away.
-        External tables are built by calling  the  pcre_maketables()  function,
+        External  tables  are  built by calling the pcre_maketables() function,
-        which  has no arguments, in the relevant locale. The result can then be
+        which has no arguments, in the relevant locale. The result can then  be
-        passed to pcre_compile() or pcre_exec()  as  often  as  necessary.  For
+        passed  to  pcre_compile()  or  pcre_exec()  as often as necessary. For
-        example,  to  build  and use tables that are appropriate for the French
+        example, to build and use tables that are appropriate  for  the  French
-        locale (where accented characters with  values  greater  than  128  are
+        locale  (where  accented  characters  with  values greater than 128 are
         treated as letters), the following code could be used:
           setlocale(LC_CTYPE, "fr_FR");
           tables = pcre_maketables();
           re = pcre_compile(..., tables);
-        When  pcre_maketables()  runs,  the  tables are built in memory that is
+        When pcre_maketables() runs, the tables are built  in  memory  that  is
-        obtained via pcre_malloc. It is the caller's responsibility  to  ensure
+        obtained  via  pcre_malloc. It is the caller's responsibility to ensure
-        that  the memory containing the tables remains available for as long as
+        that the memory containing the tables remains available for as long  as
         it is needed.
         The pointer that is passed to pcre_compile() is saved with the compiled
-        pattern,  and the same tables are used via this pointer by pcre_study()
+        pattern, and the same tables are used via this pointer by  pcre_study()
         and normally also by pcre_exec(). Thus, by default, for any single pat-
         tern, compilation, studying and matching all happen in the same locale,
         but different patterns can be compiled in different locales.
-        It is possible to pass a table pointer or NULL (indicating the  use  of
+        It  is  possible to pass a table pointer or NULL (indicating the use of
-        the  internal  tables)  to  pcre_exec(). Although not intended for this
+        the internal tables) to pcre_exec(). Although  not  intended  for  this
-        purpose, this facility could be used to match a pattern in a  different
+        purpose,  this facility could be used to match a pattern in a different
         locale from the one in which it was compiled. Passing table pointers at
         run time is discussed below in the section on matching a pattern.
-Line 862 
 INFORMATION ABOUT A PATTERN
+Line 1335 
 INFORMATION ABOUT A PATTERN
         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
              int what, void *where);
-        The pcre_fullinfo() function returns information about a compiled  pat-
+        The  pcre_fullinfo() function returns information about a compiled pat-
         tern. It replaces the obsolete pcre_info() function, which is neverthe-
         less retained for backwards compability (and is documented below).
-        The first argument for pcre_fullinfo() is a  pointer  to  the  compiled
+        The  first  argument  for  pcre_fullinfo() is a pointer to the compiled
-        pattern.  The second argument is the result of pcre_study(), or NULL if
+        pattern. The second argument is the result of pcre_study(), or NULL  if
-        the pattern was not studied. The third argument specifies  which  piece
+        the  pattern  was not studied. The third argument specifies which piece
-        of  information  is required, and the fourth argument is a pointer to a
+        of information is required, and the fourth argument is a pointer  to  a
-        variable to receive the data. The yield of the  function  is  zero  for
+        variable  to  receive  the  data. The yield of the function is zero for
         success, or one of the following negative numbers:
           PCRE_ERROR_NULL       the argument code was NULL
-Line 878 
 INFORMATION ABOUT A PATTERN
+Line 1351 
 INFORMATION ABOUT A PATTERN
           PCRE_ERROR_BADMAGIC   the "magic number" was not found
           PCRE_ERROR_BADOPTION  the value of what was invalid
-        The  "magic  number" is placed at the start of each compiled pattern as
+        The "magic number" is placed at the start of each compiled  pattern  as
-        an simple check against passing an arbitrary memory pointer. Here is  a
+        an  simple check against passing an arbitrary memory pointer. Here is a
-        typical  call  of pcre_fullinfo(), to obtain the length of the compiled
+        typical call of pcre_fullinfo(), to obtain the length of  the  compiled
         pattern:
           int rc;
-          unsigned long int length;
+          size_t length;
           rc = pcre_fullinfo(
             re,               /* result of pcre_compile() */
             pe,               /* result of pcre_study(), or NULL */
             PCRE_INFO_SIZE,   /* what is required */
             &length);         /* where to put the data */
-        The possible values for the third argument are defined in  pcre.h,  and
+        The  possible  values for the third argument are defined in pcre.h, and
         are as follows:
           PCRE_INFO_BACKREFMAX
-        Return  the  number  of  the highest back reference in the pattern. The
+        Return the number of the highest back reference  in  the  pattern.  The
-        fourth argument should point to an int variable. Zero  is  returned  if
+        fourth  argument  should  point to an int variable. Zero is returned if
         there are no back references.
           PCRE_INFO_CAPTURECOUNT
-        Return  the  number of capturing subpatterns in the pattern. The fourth
+        Return the number of capturing subpatterns in the pattern.  The  fourth
         argument should point to an int variable.
-          PCRE_INFO_DEFAULTTABLES
+          PCRE_INFO_DEFAULT_TABLES
-        Return a pointer to the internal default character tables within  PCRE.
+        Return  a pointer to the internal default character tables within PCRE.
-        The  fourth  argument should point to an unsigned char * variable. This
+        The fourth argument should point to an unsigned char *  variable.  This
         information call is provided for internal use by the pcre_study() func-
-        tion.  External  callers  can  cause PCRE to use its internal tables by
+        tion. External callers can cause PCRE to use  its  internal  tables  by
         passing a NULL table pointer.
           PCRE_INFO_FIRSTBYTE
-        Return information about the first byte of any matched  string,  for  a
+        Return  information  about  the first byte of any matched string, for a
-        non-anchored    pattern.    (This    option    used    to   be   called
+        non-anchored pattern. The fourth argument should point to an int  vari-
-        PCRE_INFO_FIRSTCHAR; the old name is  still  recognized  for  backwards
+        able.  (This option used to be called PCRE_INFO_FIRSTCHAR; the old name
-        compatibility.)
+        is still recognized for backwards compatibility.)
-        If  there  is  a  fixed first byte, for example, from a pattern such as
+        If there is a fixed first byte, for example, from  a  pattern  such  as
-        (cat|cow|coyote), it is returned in the integer pointed  to  by  where.
+        (cat|cow|coyote), its value is returned. Otherwise, if either
-        Otherwise, if either
         (a)  the pattern was compiled with the PCRE_MULTILINE option, and every
         branch starts with "^", or
-Line 958 
 INFORMATION ABOUT A PATTERN
+Line 1430 
 INFORMATION ABOUT A PATTERN
         PCRE  supports the use of named as well as numbered capturing parenthe-
         ses. The names are just an additional way of identifying the  parenthe-
-        ses,  which  still  acquire  numbers.  A  convenience  function  called
+        ses, which still acquire numbers. Several convenience functions such as
-        pcre_get_named_substring() is provided  for  extracting  an  individual
+        pcre_get_named_substring() are provided for  extracting  captured  sub-
-        captured  substring  by  name.  It is also possible to extract the data
+        strings  by  name. It is also possible to extract the data directly, by
-        directly, by first converting the name to a number in order  to  access
+        first converting the name to a number in order to  access  the  correct
-        the  correct  pointers in the output vector (described with pcre_exec()
+        pointers in the output vector (described with pcre_exec() below). To do
-        below). To do the conversion, you need to use the  name-to-number  map,
+        the conversion, you need  to  use  the  name-to-number  map,  which  is
-        which is described by these three values.
+        described by these three values.
         The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT
         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size
-Line 974 
 INFORMATION ABOUT A PATTERN
+Line 1446 
 INFORMATION ABOUT A PATTERN
         first two bytes of each entry are the number of the capturing parenthe-
         sis,  most  significant byte first. The rest of the entry is the corre-
         sponding name, zero terminated. The names are  in  alphabetical  order.
-        For  example,  consider  the following pattern (assume PCRE_EXTENDED is
+        When PCRE_DUPNAMES is set, duplicate names are in order of their paren-
-        set, so white space - including newlines - is ignored):
+        theses numbers. For example, consider  the  following  pattern  (assume
+        PCRE_EXTENDED  is  set,  so  white  space  -  including  newlines  - is
+        ignored):
-          (?P<date> (?P<year>(\d\d)?\d\d) -
+          (?<date> (?<year>(\d\d)?\d\d) -
-          (?P<month>\d\d) - (?P<day>\d\d) )
+          (?<month>\d\d) - (?<day>\d\d) )
         There are four named subpatterns, so the table has  four  entries,  and
         each  entry  in the table is eight bytes long. The table is as follows,
-Line 991 
 INFORMATION ABOUT A PATTERN
+Line 1465 
 INFORMATION ABOUT A PATTERN
 02 y  e  a  r  00 ??
         When  writing  code  to  extract  data from named subpatterns using the
-        name-to-number map, remember that the length of each entry is likely to
+        name-to-number map, remember that the length of the entries  is  likely
-        be different for each compiled pattern.
+        to be different for each compiled pattern.
           PCRE_INFO_OPTIONS
-Line 1051 
 OBSOLETE INFO FUNCTION
+Line 1525 
 OBSOLETE INFO FUNCTION
         any matched string (see PCRE_INFO_FIRSTBYTE above).
- MATCHING A PATTERN
+ REFERENCE COUNTS
+        int pcre_refcount(pcre *code, int adjust);
+        The  pcre_refcount()  function is used to maintain a reference count in
+        the data block that contains a compiled pattern. It is provided for the
+        benefit  of  applications  that  operate  in an object-oriented manner,
+        where different parts of the application may be using the same compiled
+        pattern, but you want to free the block when they are all done.
+        When a pattern is compiled, the reference count field is initialized to
+        zero.  It is changed only by calling this function, whose action is  to
+        add  the  adjust  value  (which may be positive or negative) to it. The
+        yield of the function is the new value. However, the value of the count
+        is  constrained to lie between 0 and 65535, inclusive. If the new value
+        is outside these limits, it is forced to the appropriate limit value.
+        Except when it is zero, the reference count is not correctly  preserved
+        if  a  pattern  is  compiled on one host and then transferred to a host
+        whose byte-order is different. (This seems a highly unlikely scenario.)
+ MATCHING A PATTERN: THE TRADITIONAL FUNCTION
         int pcre_exec(const pcre *code, const pcre_extra *extra,
              const char *subject, int length, int startoffset,
-Line 1060 
 MATCHING A PATTERN
+Line 1556 
 MATCHING A PATTERN
         The  function pcre_exec() is called to match a subject string against a
         compiled pattern, which is passed in the code argument. If the  pattern
         has been studied, the result of the study should be passed in the extra
-        argument.
+        argument. This function is the main matching facility of  the  library,
+        and it operates in a Perl-like manner. For specialist use there is also
+        an alternative matching function, which is described below in the  sec-
+        tion about the pcre_dfa_exec() function.
-        In most applications, the pattern will have been compiled (and  option-
+        In  most applications, the pattern will have been compiled (and option-
-        ally  studied)  in the same process that calls pcre_exec(). However, it
+        ally studied) in the same process that calls pcre_exec().  However,  it
         is possible to save compiled patterns and study data, and then use them
-        later  in  different processes, possibly even on different hosts. For a
+        later in different processes, possibly even on different hosts.  For  a
         discussion about this, see the pcreprecompile documentation.
         Here is an example of a simple call to pcre_exec():
-Line 1080 
 MATCHING A PATTERN
+Line 1579 
 MATCHING A PATTERN
 ,              /* start at offset 0 in the subject */
 ,              /* default options */
             ovector,        /* vector of integers for substring information */
-);            /* number of elements in the vector  (NOT  size  in
+);            /* number of elements (NOT size in bytes) */
-        bytes) */
     Extra data for pcre_exec()
         If  the  extra argument is not NULL, it must point to a pcre_extra data
         block. The pcre_study() function returns such a block (when it  doesn't
         return  NULL), but you can also create one for yourself, and pass addi-
-        tional information in it. The fields in a pcre_extra block are as  fol-
+        tional information in it. The pcre_extra block contains  the  following
-        lows:
+        fields (not necessarily in this order):
           unsigned long int flags;
           void *study_data;
           unsigned long int match_limit;
+          unsigned long int match_limit_recursion;
           void *callout_data;
           const unsigned char *tables;
-Line 1102 
 MATCHING A PATTERN
+Line 1601 
 MATCHING A PATTERN
           PCRE_EXTRA_STUDY_DATA
           PCRE_EXTRA_MATCH_LIMIT
+          PCRE_EXTRA_MATCH_LIMIT_RECURSION
           PCRE_EXTRA_CALLOUT_DATA
           PCRE_EXTRA_TABLES
-Line 1118 
 MATCHING A PATTERN
+Line 1618 
 MATCHING A PATTERN
         repeats.
         Internally, PCRE uses a function called match() which it calls  repeat-
-        edly  (sometimes  recursively).  The  limit is imposed on the number of
+        edly  (sometimes  recursively). The limit set by match_limit is imposed
-        times this function is called during a match, which has the  effect  of
+        on the number of times this function is called during  a  match,  which
-        limiting  the amount of recursion and backtracking that can take place.
+        has  the  effect  of  limiting the amount of backtracking that can take
-        For patterns that are not anchored, the count starts from zero for each
+        place. For patterns that are not anchored, the count restarts from zero
-        position in the subject string.
+        for each position in the subject string.
-        The  default  limit  for the library can be set when PCRE is built; the
+        The  default  value  for  the  limit can be set when PCRE is built; the
         default default is 10 million, which handles all but the  most  extreme
-        cases.  You  can  reduce  the  default  by  suppling pcre_exec() with a
+        cases.  You  can  override  the  default by suppling pcre_exec() with a
-        pcre_extra block in which match_limit is set to a  smaller  value,  and
+        pcre_extra    block    in    which    match_limit    is    set,     and
         PCRE_EXTRA_MATCH_LIMIT  is  set  in  the  flags  field. If the limit is
         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
+        The match_limit_recursion field is similar to match_limit, but  instead
+        of limiting the total number of times that match() is called, it limits
+        the depth of recursion. The recursion depth is a  smaller  number  than
+        the  total number of calls, because not all calls to match() are recur-
+        sive.  This limit is of use only if it is set smaller than match_limit.
+        Limiting  the  recursion  depth  limits the amount of stack that can be
+        used, or, when PCRE has been compiled to use memory on the heap instead
+        of the stack, the amount of heap memory that can be used.
+        The  default  value  for  match_limit_recursion can be set when PCRE is
+        built; the default default  is  the  same  value  as  the  default  for
+        match_limit.  You can override the default by suppling pcre_exec() with
+        a  pcre_extra  block  in  which  match_limit_recursion  is   set,   and
+        PCRE_EXTRA_MATCH_LIMIT_RECURSION  is  set  in  the  flags field. If the
+        limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.
         The pcre_callout field is used in conjunction with the  "callout"  fea-
         ture, which is described in the pcrecallout documentation.
-Line 1148 
 MATCHING A PATTERN
+Line 1665 
 MATCHING A PATTERN
     Option bits for pcre_exec()
         The unused bits of the options argument for pcre_exec() must  be  zero.
-        The   only  bits  that  may  be  set  are  PCRE_ANCHORED,  PCRE_NOTBOL,
+        The  only  bits  that  may  be set are PCRE_ANCHORED, PCRE_NEWLINE_xxx,
-        PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.
+        PCRE_NOTBOL,   PCRE_NOTEOL,   PCRE_NOTEMPTY,   PCRE_NO_UTF8_CHECK   and
+        PCRE_PARTIAL.
           PCRE_ANCHORED
-        The PCRE_ANCHORED option limits pcre_exec() to matching  at  the  first
+        The  PCRE_ANCHORED  option  limits pcre_exec() to matching at the first
-        matching  position.  If  a  pattern was compiled with PCRE_ANCHORED, or
+        matching position. If a pattern was  compiled  with  PCRE_ANCHORED,  or
-        turned out to be anchored by virtue of its contents, it cannot be  made
+        turned  out to be anchored by virtue of its contents, it cannot be made
         unachored at matching time.
+          PCRE_NEWLINE_CR
+          PCRE_NEWLINE_LF
+          PCRE_NEWLINE_CRLF
+          PCRE_NEWLINE_ANY
+        These options override  the  newline  definition  that  was  chosen  or
+        defaulted  when the pattern was compiled. For details, see the descrip-
+        tion of pcre_compile()  above.  During  matching,  the  newline  choice
+        affects  the  behaviour  of the dot, circumflex, and dollar metacharac-
+        ters. It may also alter the way the match position is advanced after  a
+        match  failure  for  an  unanchored  pattern. When PCRE_NEWLINE_CRLF or
+        PCRE_NEWLINE_ANY is set, and a match attempt  fails  when  the  current
+        position  is  at a CRLF sequence, the match position is advanced by two
+        characters instead of one, in other words, to after the CRLF.
           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
+        causes  circumflex  never to match. This option affects only the behav-
-        behaviour of the circumflex metacharacter. It does not affect \A.
+        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. If an invalid UTF-8 sequence
         of bytes is found, pcre_exec() returns the error PCRE_ERROR_BADUTF8. If
-        startoffset contains an  invalid  value,  PCRE_ERROR_BADUTF8_OFFSET  is
+        startoffset  contains  an  invalid  value, PCRE_ERROR_BADUTF8_OFFSET is
         returned.
-        If  you  already  know that your subject is valid, and you want to skip
+        If you already know that your subject is valid, and you  want  to  skip
-        these   checks   for   performance   reasons,   you   can    set    the
+        these    checks    for   performance   reasons,   you   can   set   the
-        PCRE_NO_UTF8_CHECK  option  when calling pcre_exec(). You might want to
+        PCRE_NO_UTF8_CHECK option when calling pcre_exec(). You might  want  to
-        do this for the second and subsequent calls to pcre_exec() if  you  are
+        do  this  for the second and subsequent calls to pcre_exec() if you are
-        making  repeated  calls  to  find  all  the matches in a single subject
+        making repeated calls to find all  the  matches  in  a  single  subject
-        string. However, you should be  sure  that  the  value  of  startoffset
+        string.  However,  you  should  be  sure  that the value of startoffset
-        points  to  the  start of a UTF-8 character. When PCRE_NO_UTF8_CHECK is
+        points to the start of a UTF-8 character.  When  PCRE_NO_UTF8_CHECK  is
-        set, the effect of passing an invalid UTF-8 string as a subject,  or  a
+        set,  the  effect of passing an invalid UTF-8 string as a subject, or a
-        value  of startoffset that does not point to the start of a UTF-8 char-
+        value of startoffset that does not point to the start of a UTF-8  char-
         acter, is undefined. Your program may crash.
           PCRE_PARTIAL
-        This option turns on the  partial  matching  feature.  If  the  subject
+        This  option  turns  on  the  partial  matching feature. If the subject
-        string  fails to match the pattern, but at some point during the match-
+        string fails to match the pattern, but at some point during the  match-
-        ing process the end of the subject was reached (that  is,  the  subject
+        ing  process  the  end of the subject was reached (that is, the subject
-        partially  matches  the  pattern and the failure to match occurred only
+        partially matches the pattern and the failure to  match  occurred  only
-        because there were not enough subject characters), pcre_exec()  returns
+        because  there were not enough subject characters), pcre_exec() returns
-        PCRE_ERROR_PARTIAL  instead of PCRE_ERROR_NOMATCH. When PCRE_PARTIAL is
+        PCRE_ERROR_PARTIAL instead of PCRE_ERROR_NOMATCH. When PCRE_PARTIAL  is
-        used, there are restrictions on what may appear in the  pattern.  These
+        used,  there  are restrictions on what may appear in the pattern. These
         are discussed in the pcrepartial documentation.
     The string to be matched by pcre_exec()
-        The  subject string is passed to pcre_exec() as a pointer in subject, a
+        The subject string is passed to pcre_exec() as a pointer in subject,  a
-        length in length, and a starting byte offset in startoffset.  In  UTF-8
+        length  in  length, and a starting byte offset in startoffset. In UTF-8
-        mode,  the  byte  offset  must point to the start of a UTF-8 character.
+        mode, the byte offset must point to the start  of  a  UTF-8  character.
-        Unlike the pattern string, the subject may contain binary  zero  bytes.
+        Unlike  the  pattern string, the subject may contain binary zero bytes.
-        When  the starting offset is zero, the search for a match starts at the
+        When the starting offset is zero, the search for a match starts at  the
         beginning of the subject, and this is by far the most common case.
-        A non-zero starting offset is useful when searching for  another  match
+        A  non-zero  starting offset is useful when searching for another match
-        in  the same subject by calling pcre_exec() again after a previous suc-
+        in the same subject by calling pcre_exec() again after a previous  suc-
-        cess.  Setting startoffset differs from just passing over  a  shortened
+        cess.   Setting  startoffset differs from just passing over a shortened
-        string  and  setting  PCRE_NOTBOL  in the case of a pattern that begins
+        string and setting PCRE_NOTBOL in the case of  a  pattern  that  begins
         with any kind of lookbehind. For example, consider the pattern
           \Biss\B
-        which finds occurrences of "iss" in the middle of  words.  (\B  matches
+        which  finds  occurrences  of "iss" in the middle of words. (\B matches
-        only  if  the  current position in the subject is not a word boundary.)
+        only if the current position in the subject is not  a  word  boundary.)
-        When applied to the string "Mississipi" the first call  to  pcre_exec()
+        When  applied  to the string "Mississipi" the first call to pcre_exec()
-        finds  the  first  occurrence. If pcre_exec() is called again with just
+        finds the first occurrence. If pcre_exec() is called  again  with  just
-        the remainder of the subject,  namely  "issipi",  it  does  not  match,
+        the  remainder  of  the  subject,  namely  "issipi", it does not match,
         because \B is always false at the start of the subject, which is deemed
-        to be a word boundary. However, if pcre_exec()  is  passed  the  entire
+        to  be  a  word  boundary. However, if pcre_exec() is passed the entire
         string again, but with startoffset set to 4, it finds the second occur-
-        rence of "iss" because it is able to look behind the starting point  to
+        rence  of "iss" because it is able to look behind the starting point to
         discover that it is preceded by a letter.
-        If  a  non-zero starting offset is passed when the pattern is anchored,
+        If a non-zero starting offset is passed when the pattern  is  anchored,
         one attempt to match at the given offset is made. This can only succeed
-        if  the  pattern  does  not require the match to be at the start of the
+        if the pattern does not require the match to be at  the  start  of  the
         subject.
     How pcre_exec() returns captured substrings
-        In general, a pattern matches a certain portion of the subject, and  in
+        In  general, a pattern matches a certain portion of the subject, and in
-        addition,  further  substrings  from  the  subject may be picked out by
+        addition, further substrings from the subject  may  be  picked  out  by
-        parts of the pattern. Following the usage  in  Jeffrey  Friedl's  book,
+        parts  of  the  pattern.  Following the usage in Jeffrey Friedl's book,
-        this  is  called "capturing" in what follows, and the phrase "capturing
+        this is called "capturing" in what follows, and the  phrase  "capturing
-        subpattern" is used for a fragment of a pattern that picks out  a  sub-
+        subpattern"  is  used for a fragment of a pattern that picks out a sub-
-        string.  PCRE  supports several other kinds of parenthesized subpattern
+        string. PCRE supports several other kinds of  parenthesized  subpattern
         that do not cause substrings to be captured.
-        Captured substrings are returned to the caller via a vector of  integer
+        Captured  substrings are returned to the caller via a vector of integer
-        offsets  whose  address is passed in ovector. The number of elements in
+        offsets whose address is passed in ovector. The number of  elements  in
-        the vector is passed in ovecsize, which must be a non-negative  number.
+        the  vector is passed in ovecsize, which must be a non-negative number.
         Note: this argument is NOT the size of ovector in bytes.
-        The  first  two-thirds of the vector is used to pass back captured sub-
+        The first two-thirds of the vector is used to pass back  captured  sub-
-        strings, each substring using a pair of integers. The  remaining  third
+        strings,  each  substring using a pair of integers. The remaining third
-        of  the  vector is used as workspace by pcre_exec() while matching cap-
+        of the vector is used as workspace by pcre_exec() while  matching  cap-
-        turing subpatterns, and is not available for passing back  information.
+        turing  subpatterns, and is not available for passing back information.
-        The  length passed in ovecsize should always be a multiple of three. If
+        The length passed in ovecsize should always be a multiple of three.  If
         it is not, it is rounded down.
-        When a match is successful, information about  captured  substrings  is
+        When  a  match  is successful, information about captured substrings is
-        returned  in  pairs  of integers, starting at the beginning of ovector,
+        returned in pairs of integers, starting at the  beginning  of  ovector,
-        and continuing up to two-thirds of its length at the  most.  The  first
+        and  continuing  up  to two-thirds of its length at the most. The first
         element of a pair is set to the offset of the first character in a sub-
-        string, and the second is set to the  offset  of  the  first  character
+        string,  and  the  second  is  set to the offset of the first character
-        after  the  end  of  a  substring. The first pair, ovector[0] and ovec-
+        after the end of a substring. The  first  pair,  ovector[0]  and  ovec-
-        tor[1], identify the portion of  the  subject  string  matched  by  the
+        tor[1],  identify  the  portion  of  the  subject string matched by the
-        entire  pattern.  The next pair is used for the first capturing subpat-
+        entire pattern. The next pair is used for the first  capturing  subpat-
-        tern, and so on. The value returned by pcre_exec()  is  the  number  of
+        tern, and so on. The value returned by pcre_exec() is one more than the
-        pairs  that  have  been set. If there are no capturing subpatterns, the
+        highest numbered pair that has been set. For example, if two substrings
-        return value from a successful match is 1,  indicating  that  just  the
+        have  been captured, the returned value is 3. If there are no capturing
-        first pair of offsets has been set.
+        subpatterns, the return value from a successful match is 1,  indicating
+        that just the first pair of offsets has been set.
-        Some  convenience  functions  are  provided for extracting the captured
-        substrings as separate strings. These are described  in  the  following
-        section.
-        It  is  possible  for  an capturing subpattern number n+1 to match some
-        part of the subject when subpattern n has not been  used  at  all.  For
-        example, if the string "abc" is matched against the pattern (a|(z))(bc)
-        subpatterns 1 and 3 are matched, but 2 is not. When this happens,  both
-        offset values corresponding to the unused subpattern are set to -1.
         If a capturing subpattern is matched repeatedly, it is the last portion
         of the string that it matched that is returned.
-Line 1320 
 MATCHING A PATTERN
+Line 1844 
 MATCHING A PATTERN
         substrings, PCRE has to get additional memory for use during  matching.
         Thus it is usually advisable to supply an ovector.
-        Note  that  pcre_info() can be used to find out how many capturing sub-
+        The  pcre_info()  function  can  be used to find out how many capturing
-        patterns there are in a compiled pattern. The smallest size for ovector
+        subpatterns there are in a compiled  pattern.  The  smallest  size  for
-        that  will  allow for n captured substrings, in addition to the offsets
+        ovector  that  will allow for n captured substrings, in addition to the
-        of the substring matched by the whole pattern, is (n+1)*3.
+        offsets of the substring matched by the whole pattern, is (n+1)*3.
+        It is possible for capturing subpattern number n+1 to match  some  part
+        of the subject when subpattern n has not been used at all. For example,
+        if the string "abc" is matched  against  the  pattern  (a|(z))(bc)  the
+        return from the function is 4, and subpatterns 1 and 3 are matched, but
+is not. When this happens, both values in  the  offset  pairs  corre-
+        sponding to unused subpatterns are set to -1.
+        Offset  values  that correspond to unused subpatterns at the end of the
+        expression are also set to -1. For example,  if  the  string  "abc"  is
+        matched  against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not
+        matched. The return from the function is 2, because  the  highest  used
+        capturing subpattern number is 1. However, you can refer to the offsets
+        for the second and third capturing subpatterns if  you  wish  (assuming
+        the vector is large enough, of course).
+        Some  convenience  functions  are  provided for extracting the captured
+        substrings as separate strings. These are described below.
-    Return values from pcre_exec()
+    Error return values from pcre_exec()
         If pcre_exec() fails, it returns a negative number. The  following  are
         defined in the header file:
-Line 1351 
 MATCHING A PATTERN
+Line 1893 
 MATCHING A PATTERN
         an  environment  with the other endianness. This is the error that PCRE
         gives when the magic number is not present.
-          PCRE_ERROR_UNKNOWN_NODE   (-5)
+          PCRE_ERROR_UNKNOWN_OPCODE (-5)
         While running the pattern match, an unknown item was encountered in the
         compiled  pattern.  This  error  could be caused by a bug in PCRE or by
-Line 1373 
 MATCHING A PATTERN
+Line 1915 
 MATCHING A PATTERN
           PCRE_ERROR_MATCHLIMIT     (-8)
-        The recursion and backtracking limit, as specified by  the  match_limit
+        The backtracking limit, as specified by  the  match_limit  field  in  a
-        field  in  a  pcre_extra  structure (or defaulted) was reached. See the
+        pcre_extra  structure  (or  defaulted) was reached. See the description
-        description above.
+        above.
           PCRE_ERROR_CALLOUT        (-9)
-Line 1394 
 MATCHING A PATTERN
+Line 1936 
 MATCHING A PATTERN
         value of startoffset did not point to the beginning of a UTF-8  charac-
         ter.
-          PCRE_ERROR_PARTIAL (-12)
+          PCRE_ERROR_PARTIAL        (-12)
         The  subject  string did not match, but it did match partially. See the
         pcrepartial documentation for details of partial matching.
-          PCRE_ERROR_BAD_PARTIAL (-13)
+          PCRE_ERROR_BADPARTIAL     (-13)
         The PCRE_PARTIAL option was used with  a  compiled  pattern  containing
         items  that are not supported for partial matching. See the pcrepartial
         documentation for details of partial matching.
-          PCRE_ERROR_INTERNAL (-14)
+          PCRE_ERROR_INTERNAL       (-14)
         An unexpected internal error has occurred. This error could  be  caused
         by a bug in PCRE or by overwriting of the compiled pattern.
-          PCRE_ERROR_BADCOUNT (-15)
+          PCRE_ERROR_BADCOUNT       (-15)
         This  error is given if the value of the ovecsize argument is negative.
+          PCRE_ERROR_RECURSIONLIMIT (-21)
+        The internal recursion limit, as specified by the match_limit_recursion
+        field  in  a  pcre_extra  structure (or defaulted) was reached. See the
+        description above.
+          PCRE_ERROR_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().
  EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
-Line 1434 
 EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
+Line 1996 
 EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
         string_list()  are  provided for extracting captured substrings as new,
         separate, zero-terminated strings. These functions identify  substrings
         by  number.  The  next section describes functions for extracting named
-        substrings. A substring  that  contains  a  binary  zero  is  correctly
+        substrings.
-        extracted  and  has  a further zero added on the end, but the result is
-        not, of course, a C string.
+        A substring that contains a binary zero is correctly extracted and  has
+        a  further zero added on the end, but the result is not, of course, a C
+        string.  However, you can process such a string  by  referring  to  the
+        length  that  is  returned  by  pcre_copy_substring() and pcre_get_sub-
+        string().  Unfortunately, the interface to pcre_get_substring_list() is
+        not  adequate for handling strings containing binary zeros, because the
+        end of the final string is not independently indicated.
         The first three arguments are the same for all  three  of  these  func-
         tions:  subject  is  the subject string that has just been successfully
-Line 1456 
 EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
+Line 2024 
 EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
         buffersize,  while  for  pcre_get_substring()  a new block of memory is
         obtained via pcre_malloc, and its address is  returned  via  stringptr.
         The  yield  of  the function is the length of the string, not including
-        the terminating zero, or one of
+        the terminating zero, or one of these error codes:
           PCRE_ERROR_NOMEMORY       (-6)
-Line 1472 
 EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
+Line 2040 
 EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
         single block of memory that is obtained via pcre_malloc. The address of
         the memory block is returned via listptr, which is also  the  start  of
         the  list  of  string pointers. The end of the list is marked by a NULL
-        pointer. The yield of the function is zero if all went well, or
+        pointer. The yield of the function is zero if all  went  well,  or  the
+        error code
           PCRE_ERROR_NOMEMORY       (-6)
         if the attempt to get the memory block failed.
-        When any of these functions encounter a substring that is unset,  which
+        When  any of these functions encounter a substring that is unset, which
-        can  happen  when  capturing subpattern number n+1 matches some part of
+        can happen when capturing subpattern number n+1 matches  some  part  of
-        the subject, but subpattern n has not been used at all, they return  an
+        the  subject, but subpattern n has not been used at all, they return an
         empty string. This can be distinguished from a genuine zero-length sub-
-        string by inspecting the appropriate offset in ovector, which is  nega-
+        string  by inspecting the appropriate offset in ovector, which is nega-
         tive for unset substrings.
-        The  two convenience functions pcre_free_substring() and pcre_free_sub-
+        The two convenience functions pcre_free_substring() and  pcre_free_sub-
-        string_list() can be used to free the memory  returned  by  a  previous
+        string_list()  can  be  used  to free the memory returned by a previous
         call  of  pcre_get_substring()  or  pcre_get_substring_list(),  respec-
-        tively. They do nothing more than  call  the  function  pointed  to  by
+        tively.  They  do  nothing  more  than  call the function pointed to by
-        pcre_free,  which  of course could be called directly from a C program.
+        pcre_free, which of course could be called directly from a  C  program.
-        However, PCRE is used in some situations where it is linked via a  spe-
+        However,  PCRE is used in some situations where it is linked via a spe-
-        cial  interface  to  another  programming  language  which  cannot  use
+        cial  interface  to  another  programming  language  that  cannot   use
-        pcre_free directly; it is  for  these  cases  that  the  functions  are
+        pcre_free  directly;  it is for these cases that the functions are pro-
-        provided.
+        vided.
  EXTRACTING CAPTURED SUBSTRINGS BY NAME
-Line 1511 
 EXTRACTING CAPTURED SUBSTRINGS BY NAME
+Line 2080 
 EXTRACTING CAPTURED SUBSTRINGS BY NAME
              int stringcount, const char *stringname,
              const char **stringptr);
-        To  extract a substring by name, you first have to find associated num-
+        To extract a substring by name, you first have to find associated  num-
         ber.  For example, for this pattern
           (a+)b(?<xxx>\d+)...
-        the number of the subpattern called "xxx" is 2. You can find the number
+        the number of the subpattern called "xxx" is 2. If the name is known to
-        from the name by calling pcre_get_stringnumber(). The first argument is
+        be unique (PCRE_DUPNAMES was not set), you can find the number from the
-        the compiled pattern, and the second is the  name.  The  yield  of  the
+        name by calling pcre_get_stringnumber(). The first argument is the com-
-        function  is  the  subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if
+        piled pattern, and the second is the name. The yield of the function is
-        there is no subpattern of that name.
+        the  subpattern  number,  or PCRE_ERROR_NOSUBSTRING (-7) if there is no
+        subpattern of that name.
         Given the number, you can extract the substring directly, or use one of
         the functions described in the previous section. For convenience, there
-Line 1541 
 EXTRACTING CAPTURED SUBSTRINGS BY NAME
+Line 2111 
 EXTRACTING CAPTURED SUBSTRINGS BY NAME
         then call pcre_copy_substring() or pcre_get_substring(),  as  appropri-
         ate.
- Last updated: 09 September 2004
- Copyright (c) 1997-2004 University of Cambridge.
- -----------------------------------------------------------------------------
- PCRE(3)                                                                PCRE(3)
+ DUPLICATE SUBPATTERN NAMES
+        int pcre_get_stringtable_entries(const pcre *code,
+             const char *name, char **first, char **last);
+        When  a  pattern  is  compiled with the PCRE_DUPNAMES option, names for
+        subpatterns are not required to  be  unique.  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
+        pcre_get_named_substring() return the first substring corresponding  to
+        the  given  name  that  is  set.  If  none  are set, an empty string is
+        returned.  The pcre_get_stringnumber() function returns one of the num-
+        bers  that are associated with the name, but it is not defined which it
+        is.
+        If you want to get full details of all captured substrings for a  given
+        name,  you  must  use  the pcre_get_stringtable_entries() function. The
+        first argument is the compiled pattern, and the second is the name. The
+        third  and  fourth  are  pointers to variables which are updated by the
+        function. After it has run, they point to the first and last entries in
+        the  name-to-number  table  for  the  given  name.  The function itself
+        returns the length of each entry,  or  PCRE_ERROR_NOSUBSTRING  (-7)  if
+        there  are none. The format of the table is described above in the sec-
+        tion entitled Information about a  pattern.   Given  all  the  relevant
+        entries  for the name, you can extract each of their numbers, and hence
+        the captured data, if any.
+ FINDING ALL POSSIBLE MATCHES
+        The traditional matching function uses a  similar  algorithm  to  Perl,
+        which stops when it finds the first match, starting at a given point in
+        the subject. If you want to find all possible matches, or  the  longest
+        possible  match,  consider using the alternative matching function (see
+        below) instead. If you cannot use the alternative function,  but  still
+        need  to  find all possible matches, you can kludge it up by making use
+        of the callout facility, which is described in the pcrecallout documen-
+        tation.
+        What you have to do is to insert a callout right at the end of the pat-
+        tern.  When your callout function is called, extract and save the  cur-
+        rent  matched  substring.  Then  return  1, which forces pcre_exec() to
+        backtrack and try other alternatives. Ultimately, when it runs  out  of
+        matches, pcre_exec() will yield PCRE_ERROR_NOMATCH.
+ MATCHING A PATTERN: THE ALTERNATIVE FUNCTION
+        int pcre_dfa_exec(const pcre *code, const pcre_extra *extra,
+             const char *subject, int length, int startoffset,
+             int options, int *ovector, int ovecsize,
+             int *workspace, int wscount);
+        The  function  pcre_dfa_exec()  is  called  to  match  a subject string
+        against a compiled pattern, using a matching algorithm that  scans  the
+        subject  string  just  once, and does not backtrack. This has different
+        characteristics to the normal algorithm, and  is  not  compatible  with
+        Perl.  Some  of the features of PCRE patterns are not supported. Never-
+        theless, there are times when this kind of matching can be useful.  For
+        a discussion of the two matching algorithms, see the pcrematching docu-
+        mentation.
+        The arguments for the pcre_dfa_exec() function  are  the  same  as  for
+        pcre_exec(), plus two extras. The ovector argument is used in a differ-
+        ent way, and this is described below. The other  common  arguments  are
+        used  in  the  same way as for pcre_exec(), so their description is not
+        repeated here.
+        The two additional arguments provide workspace for  the  function.  The
+        workspace  vector  should  contain at least 20 elements. It is used for
+        keeping  track  of  multiple  paths  through  the  pattern  tree.  More
+        workspace  will  be  needed for patterns and subjects where there are a
+        lot of potential matches.
+        Here is an example of a simple call to pcre_dfa_exec():
+          int rc;
+          int ovector[10];
+          int wspace[20];
+          rc = pcre_dfa_exec(
+            re,             /* result of pcre_compile() */
+            NULL,           /* we didn't study the pattern */
+            "some string",  /* the subject string */
+,             /* the length of the subject string */
+,              /* start at offset 0 in the subject */
+,              /* default options */
+            ovector,        /* vector of integers for substring information */
+,             /* number of elements (NOT size in bytes) */
+            wspace,         /* working space vector */
+);            /* number of elements (NOT size in bytes) */
+    Option bits for pcre_dfa_exec()
+        The unused bits of the options argument  for  pcre_dfa_exec()  must  be
+        zero.  The  only  bits  that  may  be  set are PCRE_ANCHORED, PCRE_NEW-
+        LINE_xxx, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY,  PCRE_NO_UTF8_CHECK,
+        PCRE_PARTIAL, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last
+        three of these are the same as for pcre_exec(), so their description is
+        not repeated here.
+          PCRE_PARTIAL
+        This  has  the  same general effect as it does for pcre_exec(), but the
+        details  are  slightly  different.  When  PCRE_PARTIAL   is   set   for
+        pcre_dfa_exec(),  the  return code PCRE_ERROR_NOMATCH is converted into
+        PCRE_ERROR_PARTIAL if the end of the subject  is  reached,  there  have
+        been no complete matches, but there is still at least one matching pos-
+        sibility. The portion of the string that provided the partial match  is
+        set as the first matching string.
+          PCRE_DFA_SHORTEST
+        Setting  the  PCRE_DFA_SHORTEST option causes the matching algorithm to
+        stop as soon as it has found one match. Because of the way the alterna-
+        tive  algorithm  works, this is necessarily the shortest possible match
+        at the first possible matching point in the subject string.
+          PCRE_DFA_RESTART
+        When pcre_dfa_exec()  is  called  with  the  PCRE_PARTIAL  option,  and
+        returns  a  partial  match, it is possible to call it again, with addi-
+        tional subject characters, and have it continue with  the  same  match.
+        The  PCRE_DFA_RESTART  option requests this action; when it is set, the
+        workspace and wscount options must reference the same vector as  before
+        because  data  about  the  match so far is left in them after a partial
+        match. There is more discussion of this  facility  in  the  pcrepartial
+        documentation.
+    Successful returns from pcre_dfa_exec()
+        When  pcre_dfa_exec()  succeeds, it may have matched more than one sub-
+        string in the subject. Note, however, that all the matches from one run
+        of  the  function  start  at the same point in the subject. The shorter
+        matches are all initial substrings of the longer matches. For  example,
+        if the pattern
+          <.*>
+        is matched against the string
+          This is <something> <something else> <something further> no more
+        the three matched strings are
+          <something>
+          <something> <something else>
+          <something> <something else> <something further>
+        On  success,  the  yield of the function is a number greater than zero,
+        which is the number of matched substrings.  The  substrings  themselves
+        are  returned  in  ovector. Each string uses two elements; the first is
+        the offset to the start, and the second is the offset to  the  end.  In
+        fact,  all  the  strings  have the same start offset. (Space could have
+        been saved by giving this only once, but it was decided to retain  some
+        compatibility  with  the  way pcre_exec() returns data, even though the
+        meaning of the strings is different.)
+        The strings are returned in reverse order of length; that is, the long-
+        est  matching  string is given first. If there were too many matches to
+        fit into ovector, the yield of the function is zero, and the vector  is
+        filled with the longest matches.
+    Error returns from pcre_dfa_exec()
+        The  pcre_dfa_exec()  function returns a negative number when it fails.
+        Many of the errors are the same  as  for  pcre_exec(),  and  these  are
+        described  above.   There are in addition the following errors that are
+        specific to pcre_dfa_exec():
+          PCRE_ERROR_DFA_UITEM      (-16)
+        This return is given if pcre_dfa_exec() encounters an item in the  pat-
+        tern  that  it  does not support, for instance, the use of \C or a back
+        reference.
+          PCRE_ERROR_DFA_UCOND      (-17)
+        This return is given if pcre_dfa_exec()  encounters  a  condition  item
+        that  uses  a back reference for the condition, or a test for recursion
+        in a specific group. These are not supported.
+          PCRE_ERROR_DFA_UMLIMIT    (-18)
+        This return is given if pcre_dfa_exec() is called with an  extra  block
+        that contains a setting of the match_limit field. This is not supported
+        (it is meaningless).
+          PCRE_ERROR_DFA_WSSIZE     (-19)
+        This return is given if  pcre_dfa_exec()  runs  out  of  space  in  the
+        workspace vector.
+          PCRE_ERROR_DFA_RECURSE    (-20)
+        When  a  recursive subpattern is processed, the matching function calls
+        itself recursively, using private vectors for  ovector  and  workspace.
+        This  error  is  given  if  the output vector is not large enough. This
+        should be extremely rare, as a vector of size 1000 is used.
+ SEE ALSO
+        pcrebuild(3), pcrecallout(3), pcrecpp(3)(3), pcrematching(3),  pcrepar-
+        tial(3),  pcreposix(3), pcreprecompile(3), pcresample(3), pcrestack(3).
+ Last updated: 30 November 2006
+ Copyright (c) 1997-2006 University of Cambridge.
+ ------------------------------------------------------------------------------
+ PCRECALLOUT(3)                                                  PCRECALLOUT(3)
  NAME
         PCRE - Perl-compatible regular expressions
  PCRE CALLOUTS
         int (*pcre_callout)(pcre_callout_block *);
-Line 1606 
 MISSING CALLOUTS
+Line 2384 
 MISSING CALLOUTS
  THE CALLOUT INTERFACE
         During matching, when PCRE reaches a callout point, the external  func-
-        tion  defined  by pcre_callout is called (if it is set). The only argu-
+        tion  defined by pcre_callout is called (if it is set). This applies to
-        ment is a pointer to a pcre_callout block. This structure contains  the
+        both the pcre_exec() and the pcre_dfa_exec()  matching  functions.  The
-        following fields:
+        only  argument  to  the callout function is a pointer to a pcre_callout
+        block. This structure contains the following fields:
           int          version;
           int          callout_number;
-Line 1623 
 THE CALLOUT INTERFACE
+Line 2402 
 THE CALLOUT INTERFACE
           int          pattern_position;
           int          next_item_length;
-        The  version  field  is an integer containing the version number of the
+        The version field is an integer containing the version  number  of  the
-        block format. The initial version was 0; the current version is 1.  The
+        block  format. The initial version was 0; the current version is 1. The
-        version  number  will  change  again in future if additional fields are
+        version number will change again in future  if  additional  fields  are
         added, but the intention is never to remove any of the existing fields.
-        The  callout_number  field  contains the number of the callout, as com-
+        The callout_number field contains the number of the  callout,  as  com-
-        piled into the pattern (that is, the number after ?C for  manual  call-
+        piled  into  the pattern (that is, the number after ?C for manual call-
         outs, and 255 for automatically generated callouts).
-        The  offset_vector field is a pointer to the vector of offsets that was
+        The offset_vector field is a pointer to the vector of offsets that  was
-        passed by the caller to pcre_exec(). The contents can be  inspected  in
+        passed   by   the   caller  to  pcre_exec()  or  pcre_dfa_exec().  When
-        order  to extract substrings that have been matched so far, in the same
+        pcre_exec() is used, the contents can be inspected in order to  extract
-        way as for extracting substrings after a match has completed.
+        substrings  that  have  been  matched  so  far,  in the same way as for
+        extracting substrings after a match has completed. For  pcre_dfa_exec()
+        this field is not useful.
         The subject and subject_length fields contain copies of the values that
         were passed to pcre_exec().
-        The  start_match  field contains the offset within the subject at which
+        The start_match field contains the offset within the subject  at  which
-        the current match attempt started. If the pattern is not anchored,  the
+        the  current match attempt started. If the pattern is not anchored, the
         callout function may be called several times from the same point in the
         pattern for different starting points in the subject.
-        The current_position field contains the offset within  the  subject  of
+        The  current_position  field  contains the offset within the subject of
         the current match pointer.
-        The  capture_top field contains one more than the number of the highest
+        When the pcre_exec() function is used, the capture_top  field  contains
-        numbered captured substring so far. If no  substrings  have  been  cap-
+        one  more than the number of the highest numbered captured substring so
-        tured, the value of capture_top is one.
+        far. If no substrings have been captured, the value of  capture_top  is
+        one.  This  is always the case when pcre_dfa_exec() is used, because it
-        The  capture_last  field  contains the number of the most recently cap-
+        does not support captured substrings.
-        tured substring. If no substrings have been captured, its value is  -1.
+        The capture_last field contains the number of the  most  recently  cap-
-        The  callout_data  field contains a value that is passed to pcre_exec()
+        tured  substring. If no substrings have been captured, its value is -1.
-        by the caller specifically so that it can be passed back  in  callouts.
+        This is always the case when pcre_dfa_exec() is used.
-        It  is  passed  in the pcre_callout field of the pcre_extra data struc-
-        ture. If no such data was  passed,  the  value  of  callout_data  in  a
+        The callout_data field contains a value that is passed  to  pcre_exec()
-        pcre_callout  block  is  NULL. There is a description of the pcre_extra
+        or  pcre_dfa_exec() specifically so that it can be passed back in call-
+        outs. It is passed in the pcre_callout field  of  the  pcre_extra  data
+        structure.  If  no such data was passed, the value of callout_data in a
+        pcre_callout block is NULL. There is a description  of  the  pcre_extra
         structure in the pcreapi documentation.
-        The pattern_position field is present from version 1 of the  pcre_call-
+        The  pattern_position field is present from version 1 of the pcre_call-
         out structure. It contains the offset to the next item to be matched in
         the pattern string.
-        The next_item_length field is present from version 1 of the  pcre_call-
+        The  next_item_length field is present from version 1 of the pcre_call-
         out structure. It contains the length of the next item to be matched in
-        the pattern string. When the callout immediately precedes  an  alterna-
+        the  pattern  string. When the callout immediately precedes an alterna-
-        tion  bar, a closing parenthesis, or the end of the pattern, the length
+        tion bar, a closing parenthesis, or the end of the pattern, the  length
-        is zero. When the callout precedes an opening parenthesis,  the  length
+        is  zero.  When the callout precedes an opening parenthesis, the length
         is that of the entire subpattern.
-        The  pattern_position  and next_item_length fields are intended to help
+        The pattern_position and next_item_length fields are intended  to  help
-        in distinguishing between different automatic callouts, which all  have
+        in  distinguishing between different automatic callouts, which all have
         the same callout number. However, they are set for all callouts.
  RETURN VALUES
-        The  external callout function returns an integer to PCRE. If the value
+        The external callout function returns an integer to PCRE. If the  value
-        is zero, matching proceeds as normal. If  the  value  is  greater  than
+        is  zero,  matching  proceeds  as  normal. If the value is greater than
-        zero,  matching  fails  at  the current point, but backtracking to test
+        zero, matching fails at the current point, but  the  testing  of  other
-        other matching possibilities goes ahead, just as if a lookahead  asser-
+        matching possibilities goes ahead, just as if a lookahead assertion had
-        tion  had  failed.  If  the value is less than zero, the match is aban-
+        failed. If the value is less than zero, the  match  is  abandoned,  and
-        doned, and pcre_exec() returns the negative value.
+        pcre_exec() (or pcre_dfa_exec()) returns the negative value.
-        Negative  values  should  normally  be   chosen   from   the   set   of
+        Negative   values   should   normally   be   chosen  from  the  set  of
         PCRE_ERROR_xxx values. In particular, PCRE_ERROR_NOMATCH forces a stan-
-        dard "no  match"  failure.   The  error  number  PCRE_ERROR_CALLOUT  is
+        dard  "no  match"  failure.   The  error  number  PCRE_ERROR_CALLOUT is
-        reserved  for  use  by callout functions; it will never be used by PCRE
+        reserved for use by callout functions; it will never be  used  by  PCRE
         itself.
- Last updated: 09 September 2004
+ Last updated: 28 February 2005
- Copyright (c) 1997-2004 University of Cambridge.
+ Copyright (c) 1997-2005 University of Cambridge.
- -----------------------------------------------------------------------------
+ ------------------------------------------------------------------------------
- PCRE(3)                                                                PCRE(3)
+ PCRECOMPAT(3)                                                    PCRECOMPAT(3)
  NAME
         PCRE - Perl-compatible regular expressions
  DIFFERENCES BETWEEN PCRE AND PERL
         This  document describes the differences in the ways that PCRE and Perl
-        handle regular expressions. The differences  described  here  are  with
+        handle regular expressions. The differences described here  are  mainly
-        respect to Perl 5.8.
+        with  respect  to  Perl 5.8, though PCRE version 7.0 contains some fea-
+        tures that are expected to be in the forthcoming Perl 5.10.
-.  PCRE does not have full UTF-8 support. Details of what it does have
-        are given in the section on UTF-8 support in the main pcre page.
+. 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
+        main pcre page.
 . PCRE does not allow repeat quantifiers on lookahead assertions. Perl
         permits  them,  but they do not mean what you might think. For example,
-Line 1738 
 DIFFERENCES BETWEEN PCRE AND PERL
+Line 2525 
 DIFFERENCES BETWEEN PCRE AND PERL
 . The Perl escape sequences \p, \P, and \X are supported only if  PCRE
         is  built  with Unicode character property support. The properties that
         can be tested with \p and \P are limited to the general category  prop-
-        erties such as Lu and Nd.
+        erties  such  as  Lu and Nd, script names such as Greek or Han, and the
+        derived properties Any and L&.
 . PCRE does support the \Q...\E escape for quoting substrings. Charac-
-        ters in between are treated as literals.  This  is  slightly  different
+        ters  in  between  are  treated as literals. This is slightly different
-        from  Perl  in  that  $  and  @ are also handled as literals inside the
+        from Perl in that $ and @ are  also  handled  as  literals  inside  the
-        quotes. In Perl, they cause variable interpolation (but of course  PCRE
+        quotes.  In Perl, they cause variable interpolation (but of course PCRE
         does not have variables). Note the following examples:
             Pattern            PCRE matches      Perl matches
-Line 1753 
 DIFFERENCES BETWEEN PCRE AND PERL
+Line 2541 
 DIFFERENCES BETWEEN PCRE AND PERL
             \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.
-. Fairly obviously, PCRE does not support the (?{code}) and (?p{code})
+. Fairly obviously, PCRE does not support the (?{code}) and (??{code})
-        constructions.  However,  there is support for recursive patterns using
+        constructions. However, there is support for recursive  patterns.  This
-        the non-Perl items (?R),  (?number),  and  (?P>name).  Also,  the  PCRE
+        is  not available in Perl 5.8, but will be in Perl 5.10. Also, the PCRE
-        "callout"  feature allows an external function to be called during pat-
+        "callout" feature allows an external function to be called during  pat-
         tern matching. See the pcrecallout documentation for details.
-. There are some differences that are concerned with the  settings  of
+.  Subpatterns  that  are  called  recursively or as "subroutines" are
-        captured  strings  when  part  of  a  pattern is repeated. For example,
+        always treated as atomic groups in  PCRE.  This  is  like  Python,  but
-        matching "aba" against the  pattern  /^(a(b)?)+$/  in  Perl  leaves  $2
+        unlike Perl.
+.  There are some differences that are concerned with the settings of
+        captured strings when part of  a  pattern  is  repeated.  For  example,
+        matching  "aba"  against  the  pattern  /^(a(b)?)+$/  in Perl leaves $2
         unset, but in PCRE it is set to "b".
 . PCRE provides some extensions to the Perl regular expression facil-
-        ities:
+        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:
-        (a) Although lookbehind assertions must  match  fixed  length  strings,
+        (a)  Although  lookbehind  assertions  must match fixed length strings,
         each alternative branch of a lookbehind assertion can match a different
         length of string. Perl requires them all to have the same length.
-        (b) If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not set, the  $
+        (b)  If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not set, the $
         meta-character matches only at the very end of the string.
         (c) If PCRE_EXTRA is set, a backslash followed by a letter with no spe-
-        cial meaning is faulted.
+        cial  meaning  is  faulted.  Otherwise,  like  Perl,  the  backslash is
+        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 1790 
 DIFFERENCES BETWEEN PCRE AND PERL
+Line 2585 
 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 (?R), (?number), and (?P>name) constructs allows for  recursive
+        (g) The callout facility is PCRE-specific.
-        pattern  matching  (Perl  can  do  this using the (?p{code}) construct,
-        which PCRE cannot support.)
-        (h) PCRE supports named capturing substrings, using the Python  syntax.
-        (i)  PCRE  supports  the  possessive quantifier "++" syntax, taken from
-        Sun's Java package.
-        (j) The (R) condition, for testing recursion, is a PCRE extension.
-        (k) The callout facility is PCRE-specific.
+        (h) The partial matching facility is PCRE-specific.
-        (l) The partial matching facility is PCRE-specific.
+        (i) Patterns compiled by PCRE can be saved and re-used at a later time,
-        (m) Patterns compiled by PCRE can be saved and re-used at a later time,
         even on different hosts that have the other endianness.
- Last updated: 09 September 2004
+        (j)  The  alternative  matching function (pcre_dfa_exec()) matches in a
- Copyright (c) 1997-2004 University of Cambridge.
+        different way and is not Perl-compatible.
- -----------------------------------------------------------------------------
+ Last updated: 28 November 2006
+ Copyright (c) 1997-2006 University of Cambridge.
+ ------------------------------------------------------------------------------
- PCRE(3)                                                                PCRE(3)
+ PCREPATTERN(3)                                                  PCREPATTERN(3)
  NAME
         PCRE - Perl-compatible regular expressions
  PCRE REGULAR EXPRESSION DETAILS
         The  syntax  and semantics of the regular expressions supported by PCRE
-Line 1836 
 PCRE REGULAR EXPRESSION DETAILS
+Line 2624 
 PCRE REGULAR EXPRESSION DETAILS
         of  UTF-8  features  in  the  section on UTF-8 support in the main pcre
         page.
+        The remainder of this document discusses the  patterns  that  are  sup-
+        ported  by  PCRE when its main matching function, pcre_exec(), is used.
+        From  release  6.0,   PCRE   offers   a   second   matching   function,
+        pcre_dfa_exec(),  which matches using a different algorithm that is not
+        Perl-compatible. The advantages and disadvantages  of  the  alternative
+        function, and how it differs from the normal function, are discussed in
+        the pcrematching page.
+ CHARACTERS AND METACHARACTERS
         A regular expression is a pattern that is  matched  against  a  subject
         string  from  left  to right. Most characters stand for themselves in a
         pattern, and match the corresponding characters in the  subject.  As  a
-Line 1843 
 PCRE REGULAR EXPRESSION DETAILS
+Line 2642 
 PCRE REGULAR EXPRESSION DETAILS
           The quick brown fox
-        matches  a portion of a subject string that is identical to itself. The
+        matches a portion of a subject string that is identical to itself. When
-        power of regular expressions comes from the ability to include alterna-
+        caseless matching is specified (the PCRE_CASELESS option), letters  are
-        tives  and repetitions in the pattern. These are encoded in the pattern
+        matched  independently  of case. In UTF-8 mode, PCRE always understands
-        by the use of metacharacters, which do not  stand  for  themselves  but
+        the concept of case for characters whose values are less than  128,  so
-        instead are interpreted in some special way.
+        caseless  matching  is always possible. For characters with higher val-
+        ues, the concept of case is supported if PCRE is compiled with  Unicode
-        There  are  two different sets of metacharacters: those that are recog-
+        property  support,  but  not  otherwise.   If  you want to use caseless
-        nized anywhere in the pattern except within square brackets, and  those
+        matching for characters 128 and above, you must  ensure  that  PCRE  is
-        that  are  recognized  in square brackets. Outside square brackets, the
+        compiled with Unicode property support as well as with UTF-8 support.
-        metacharacters are as follows:
+        The  power  of  regular  expressions  comes from the ability to include
+        alternatives and repetitions in the pattern. These are encoded  in  the
+        pattern by the use of 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-
+        nized  anywhere in the pattern except within square brackets, and those
+        that are recognized within square brackets.  Outside  square  brackets,
+        the metacharacters are as follows:
           \      general escape character with several uses
           ^      assert start of string (or line, in multiline mode)
-Line 1870 
 PCRE REGULAR EXPRESSION DETAILS
+Line 2678 
 PCRE REGULAR EXPRESSION DETAILS
                  also "possessive quantifier"
           {      start min/max quantifier
-        Part of a pattern that is in square brackets  is  called  a  "character
+        Part  of  a  pattern  that is in square brackets is called a "character
         class". In a character class the only metacharacters are:
           \      general escape character
-Line 1880 
 PCRE REGULAR EXPRESSION DETAILS
+Line 2688 
 PCRE REGULAR EXPRESSION DETAILS
                    syntax)
           ]      terminates the character class
-        The  following sections describe the use of each of the metacharacters.
+        The following sections describe the use of each of the  metacharacters.
  BACKSLASH
         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 character are ignored.
+        # outside a character class and the next newline are ignored. An escap-
-        An  escaping backslash can be used to include a whitespace or # charac-
+        ing backslash can be used to include a whitespace  or  #  character  as
-        ter as part of the pattern.
+        part of the pattern.
-        If you want to remove the special meaning from a  sequence  of  charac-
+        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 1916 
 BACKSLASH
+Line 2724 
 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)
-Line 1937 
 BACKSLASH
+Line 2745 
 BACKSLASH
           \t        tab (hex 09)
           \ddd      character with octal code ddd, or backreference
           \xhh      character with hex code hh
-          \x{hhh..} character with hex code hhh... (UTF-8 mode only)
+          \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). In UTF-8 mode, any number of hexadecimal  dig-
+        in  upper  or  lower case). Any number of hexadecimal digits may appear
-        its  may  appear between \x{ and }, but the value of the character code
+        between \x{ and }, but the value of the character  code  must  be  less
-        must be less than 2**31 (that is,  the  maximum  hexadecimal  value  is
+        than 256 in non-UTF-8 mode, and less than 2**31 in UTF-8 mode (that is,
-FFFFFFF).  If  characters other than hexadecimal digits appear between
+        the maximum hexadecimal value is 7FFFFFFF). If  characters  other  than
-        \x{ and }, or if there is no terminating }, this form of escape is  not
+        hexadecimal  digits  appear between \x{ and }, or if there is no termi-
-        recognized. Instead, the initial \x will be interpreted as a basic hex-
+        nating }, this form of escape is not recognized.  Instead, the  initial
-        adecimal escape, with no following digits,  giving  a  character  whose
+        \x will be interpreted as a basic hexadecimal escape, with no following
-        value is zero.
+        digits, giving a character whose value is zero.
         Characters whose value is less than 256 can be defined by either of the
-        two syntaxes for \x when PCRE is in UTF-8 mode. There is no  difference
+        two  syntaxes  for  \x. There is no difference in the way they are han-
-        in  the  way they are handled. For example, \xdc is exactly the same as
+        dled. For example, \xdc is exactly the same as \x{dc}.
-        \x{dc}.
+        After \0 up to two further octal digits are read. If  there  are  fewer
-        After \0 up to two further octal digits are read.  In  both  cases,  if
+        than  two  digits,  just  those  that  are  present  are used. Thus the
-        there  are fewer than two digits, just those that are present are used.
+        sequence \0\x\07 specifies two binary zeros followed by a BEL character
-        Thus the sequence \0\x\07 specifies two binary zeros followed by a  BEL
+        (code  value 7). Make sure you supply two digits after the initial zero
-        character  (code  value  7).  Make sure you supply two digits after the
+        if the pattern character that follows is itself an octal digit.
-        initial zero if the pattern character that follows is itself  an  octal
-        digit.
         The handling of a backslash followed by a digit other than 0 is compli-
         cated.  Outside a character class, PCRE reads it and any following dig-
-        its  as  a  decimal  number. If the number is less than 10, or if there
+        its as a decimal number. If the number is less than  10,  or  if  there
         have been at least that many previous capturing left parentheses in the
-        expression,  the  entire  sequence  is  taken  as  a  back reference. A
+        expression, the entire  sequence  is  taken  as  a  back  reference.  A
-        description of how this works is given later, following the  discussion
+        description  of how this works is given later, following the discussion
         of parenthesized subpatterns.
-        Inside  a  character  class, or if the decimal number is greater than 9
+        Inside a character class, or if the decimal number is  greater  than  9
-        and there have not been that many capturing subpatterns, PCRE  re-reads
+        and  there have not been that many capturing subpatterns, PCRE re-reads
-        up  to three octal digits following the backslash, and generates a sin-
+        up to three octal digits following the backslash, and uses them to gen-
-        gle byte from the least significant 8 bits of the value. Any subsequent
+        erate  a data character. Any subsequent digits stand for themselves. In
-        digits stand for themselves.  For example:
+        non-UTF-8 mode, the value of a character specified  in  octal  must  be
+        less  than  \400.  In  UTF-8 mode, values up to \777 are permitted. For
+        example:
           \040   is another way of writing a space
           \40    is the same, provided there are fewer than 40
-Line 1995 
 BACKSLASH
+Line 2803 
 BACKSLASH
           \81    is either a back reference, or a binary zero
                     followed by the two characters "8" and "1"
-        Note  that  octal  values of 100 or greater must not be introduced by a
+        Note that octal values of 100 or greater must not be  introduced  by  a
         leading zero, because no more than three octal digits are ever read.
-        All the sequences that define a single byte value  or  a  single  UTF-8
+        All the sequences that define a single character value can be used both
-        character (in UTF-8 mode) can be used both inside and outside character
+        inside and outside character classes. In addition, inside  a  character
-        classes. In addition, inside a character  class,  the  sequence  \b  is
+        class,  the  sequence \b is interpreted as the backspace character (hex
-        interpreted as the backspace character (hex 08), and the sequence \X is
+), and the sequences \R and \X are interpreted as the characters  "R"
-        interpreted as the character "X".  Outside  a  character  class,  these
+        and  "X", respectively. Outside a character class, these sequences have
-        sequences have different meanings (see below).
+        different meanings (see below).
+    Absolute and relative back references
+        The sequence \g followed by a positive or negative  number,  optionally
+        enclosed  in  braces,  is  an absolute or relative back reference. Back
+        references are discussed later, following the discussion  of  parenthe-
+        sized subpatterns.
     Generic character types
-        The  third  use of backslash is for specifying generic character types.
+        Another use of backslash is for specifying generic character types. The
-        The following are always recognized:
+        following are always recognized:
           \d     any decimal digit
           \D     any character that is not a decimal digit
-Line 2028 
 BACKSLASH
+Line 2843 
 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).
+        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.)
         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 2040 
 BACKSLASH
+Line 2857 
 BACKSLASH
         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.
+        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
+        newline sequence. This is an extension to Perl. In non-UTF-8 mode \R is
+        equivalent to the following:
+          (?>\r\n|\n|\x0b|\f|\r|\x85)
+        This is an example of an "atomic group", details  of  which  are  given
+        below.  This particular group matches either the two-character sequence
+        CR followed by LF, or  one  of  the  single  characters  LF  (linefeed,
+        U+000A), VT (vertical tab, U+000B), FF (formfeed, U+000C), CR (carriage
+        return, U+000D), or NEL (next line, U+0085). The two-character sequence
+        is treated as a single unit that cannot be split.
+        In  UTF-8  mode, two additional characters whose codepoints are greater
+        than 255 are added: LS (line separator, U+2028) and PS (paragraph sepa-
+        rator,  U+2029).   Unicode character property support is not needed for
+        these characters to be recognized.
+        Inside a character class, \R matches the letter "R".
     Unicode character properties
         When PCRE is built with Unicode character property support, three addi-
-        tional escape sequences to match generic character types are  available
+        tional  escape  sequences  to  match character properties are available
         when UTF-8 mode is selected. They are:
-         \p{xx}   a character with the xx property
+          \p{xx}   a character with the xx property
-         \P{xx}   a character without the xx property
+          \P{xx}   a character without the xx property
-         \X       an extended Unicode sequence
+          \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
-        general category properties. Each character has exactly one such  prop-
+        script names, the general category properties, and "Any", which matches
-        erty,  specified  by  a two-letter abbreviation. For compatibility with
+        any character (including newline). Other properties such as "InMusical-
-        Perl, negation can be specified by including a circumflex  between  the
+        Symbols"  are  not  currently supported by PCRE. Note that \P{Any} does
-        opening  brace  and the property name. For example, \p{^Lu} is the same
+        not match any characters, so always causes a match failure.
-        as \P{Lu}.
+        Sets of Unicode characters are defined as belonging to certain scripts.
-        If only one letter is specified with \p or  \P,  it  includes  all  the
+        A  character from one of these sets can be matched using a script name.
-        properties that start with that letter. In this case, in the absence of
+        For example:
-        negation, the curly brackets in the escape sequence are optional; these
-        two examples have the same effect:
+          \p{Greek}
+          \P{Han}
+        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,
+        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.
+        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
+        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
+        the absence of negation, the curly brackets in the escape sequence  are
+        optional; these two examples have the same effect:
           \p{L}
           \pL
-        The following property codes are supported:
+        The following general category property codes are supported:
           C     Other
           Cc    Control
-Line 2113 
 BACKSLASH
+Line 2977 
 BACKSLASH
           Zp    Paragraph separator
           Zs    Space separator
-        Extended  properties such as "Greek" or "InMusicalSymbols" are not sup-
+        The  special property L& is also supported: it matches a character that
-        ported by PCRE.
+        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
+        \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.
-        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.
     Simple assertions
-        The fourth use of backslash is for certain simple assertions. An asser-
+        The  final use of backslash is for certain simple assertions. An asser-
-        tion  specifies a condition that has to be met at a particular point in
+        tion specifies a condition that has to be met at a particular point  in
-        a match, without consuming any characters from the subject string.  The
+        a  match, without consuming any characters from the subject string. The
-        use  of subpatterns for more complicated assertions is described below.
+        use of subpatterns for more complicated assertions is described  below.
         The backslashed assertions are:
           \b     matches at a word boundary
           \B     matches when not at a word boundary
-          \A     matches at start of subject
+          \A     matches at the start of the subject
-          \Z     matches at end of subject or before newline at end
+          \Z     matches at the end of the subject
-          \z     matches at end of subject
+                  also matches before a newline at the end of the subject
-          \G     matches at first matching position in subject
+          \z     matches only at the end of the subject
+          \G     matches at the first matching position in the subject
-        These assertions may not appear in character classes (but note that  \b
+        These  assertions may not appear in character classes (but note that \b
         has a different meaning, namely the backspace character, inside a char-
         acter class).
-        A word boundary is a position in the subject string where  the  current
+        A  word  boundary is a position in the subject string where the current
-        character  and  the previous character do not both match \w or \W (i.e.
+        character and the previous character do not both match \w or  \W  (i.e.
-        one matches \w and the other matches \W), or the start or  end  of  the
+        one  matches  \w  and the other matches \W), or the start or end of the
         string if the first or last character matches \w, respectively.
-        The  \A,  \Z,  and \z assertions differ from the traditional circumflex
+        The \A, \Z, and \z assertions differ from  the  traditional  circumflex
         and dollar (described in the next section) in that they only ever match
-        at  the  very start and end of the subject string, whatever options are
+        at the very start and end of the subject string, whatever  options  are
-        set. Thus, they are independent of multiline mode. These  three  asser-
+        set.  Thus,  they are independent of multiline mode. These three asser-
         tions are not affected by the PCRE_NOTBOL or PCRE_NOTEOL options, which
-        affect only the behaviour of the circumflex and dollar  metacharacters.
+        affect  only the behaviour of the circumflex and dollar metacharacters.
-        However,  if the startoffset argument of pcre_exec() is non-zero, indi-
+        However, if the startoffset argument of pcre_exec() is non-zero,  indi-
         cating that matching is to start at a point other than the beginning of
-        the  subject,  \A  can never match. The difference between \Z and \z is
+        the subject, \A can never match. The difference between \Z  and  \z  is
-        that \Z matches before a newline that is  the  last  character  of  the
+        that \Z matches before a newline at the end of the string as well as at
-        string  as well as at the end of the string, whereas \z matches only at
+        the very end, whereas \z matches only at the end.
-        the end.
         The \G assertion is true only when the current matching position is  at
         the  start point of the match, as specified by the startoffset argument
-Line 2208 
 CIRCUMFLEX AND DOLLAR
+Line 3081 
 CIRCUMFLEX AND DOLLAR
         A dollar character is an assertion that is true  only  if  the  current
         matching  point  is  at  the  end of the subject string, or immediately
-        before a newline character that is the last character in the string (by
+        before a newline at the end of the string (by default). Dollar need not
-        default).  Dollar  need  not  be the last character of the pattern if a
+        be  the  last  character of the pattern if a number of alternatives are
-        number of alternatives are involved, but it should be the last item  in
+        involved, but it should be the last item in  any  branch  in  which  it
-        any  branch  in  which  it appears.  Dollar has no special meaning in a
+        appears. Dollar has no special meaning in a character class.
-        character class.
-        The meaning of dollar can be changed so that it  matches  only  at  the
+        The  meaning  of  dollar  can be changed so that it matches only at the
-        very  end  of  the string, by setting the PCRE_DOLLAR_ENDONLY option at
+        very end of the string, by setting the  PCRE_DOLLAR_ENDONLY  option  at
         compile time. This does not affect the \Z assertion.
         The meanings of the circumflex and dollar characters are changed if the
-        PCRE_MULTILINE option is set. When this is the case, they match immedi-
+        PCRE_MULTILINE option is set. When  this  is  the  case,  a  circumflex
-        ately after and  immediately  before  an  internal  newline  character,
+        matches  immediately after internal newlines as well as at the start of
-        respectively,  in addition to matching at the start and end of the sub-
+        the subject string. It does not match after a  newline  that  ends  the
-        ject string. For example,  the  pattern  /^abc$/  matches  the  subject
+        string.  A dollar matches before any newlines in the string, as well as
-        string  "def\nabc"  (where \n represents a newline character) in multi-
+        at the very end, when PCRE_MULTILINE is set. When newline is  specified
-        line mode, but not otherwise.  Consequently, patterns that are anchored
+        as  the  two-character  sequence CRLF, isolated CR and LF characters do
-        in  single line mode because all branches start with ^ are not anchored
+        not indicate newlines.
-        in multiline mode, and a match for  circumflex  is  possible  when  the
-        startoffset   argument   of  pcre_exec()  is  non-zero.  The  PCRE_DOL-
+        For example, the pattern /^abc$/ matches the subject string  "def\nabc"
-        LAR_ENDONLY option is ignored if PCRE_MULTILINE is set.
+        (where  \n  represents a newline) in multiline mode, but not otherwise.
+        Consequently, patterns that are anchored in single  line  mode  because
+        all  branches  start  with  ^ are not anchored in multiline mode, and a
+        match for circumflex is  possible  when  the  startoffset  argument  of
+        pcre_exec()  is  non-zero. The PCRE_DOLLAR_ENDONLY option is ignored if
+        PCRE_MULTILINE is set.
         Note that the sequences \A, \Z, and \z can be used to match  the  start
         and  end of the subject in both modes, and if all branches of a pattern
-        start with \A it is always anchored, whether PCRE_MULTILINE is  set  or
+        start with \A it is always anchored, whether or not  PCRE_MULTILINE  is
-        not.
+        set.
  FULL STOP (PERIOD, DOT)
         Outside a character class, a dot in the pattern matches any one charac-
-        ter in the subject, including a non-printing  character,  but  not  (by
+        ter in the subject string except (by default) a character  that  signi-
-        default)  newline.   In  UTF-8 mode, a dot matches any UTF-8 character,
+        fies  the  end  of  a line. In UTF-8 mode, the matched character may be
-        which might be more than one byte long, except (by default) newline. If
+        more than one byte long.
-        the  PCRE_DOTALL  option  is set, dots match newlines as well. The han-
-        dling of dot is entirely independent of the handling of circumflex  and
+        When a line ending is defined as a single character, dot never  matches
-        dollar,  the  only  relationship  being  that they both involve newline
+        that  character; when the two-character sequence CRLF is used, dot does
-        characters. Dot has no special meaning in a character class.
+        not match CR if it is immediately followed  by  LF,  but  otherwise  it
+        matches  all characters (including isolated CRs and LFs). When any Uni-
+        code line endings are being recognized, dot does not match CR or LF  or
+        any of the other line ending characters.
+        The  behaviour  of  dot  with regard to newlines can be changed. If the
+        PCRE_DOTALL option is set, a dot matches  any  one  character,  without
+        exception. If the two-character sequence CRLF is present in the subject
+        string, it takes two dots to match it.
+        The handling of dot is entirely independent of the handling of  circum-
+        flex  and  dollar,  the  only relationship being that they both involve
+        newlines. Dot has no special meaning in a character class.
  MATCHING A SINGLE BYTE
         Outside a character class, the escape sequence \C matches any one byte,
-        both  in  and  out of UTF-8 mode. Unlike a dot, it can match a newline.
+        both  in  and  out  of  UTF-8 mode. Unlike a dot, it always matches any
-        The feature is provided in Perl in order to match individual  bytes  in
+        line-ending characters. The feature is provided in  Perl  in  order  to
-        UTF-8  mode.  Because  it  breaks  up  UTF-8 characters into individual
+        match  individual bytes in UTF-8 mode. Because it breaks up UTF-8 char-
-        bytes, what remains in the string may be a malformed UTF-8 string.  For
+        acters into individual bytes, what remains in the string may be a  mal-
-        this reason, the \C escape sequence is best avoided.
+        formed  UTF-8  string.  For this reason, the \C escape sequence is best
+        avoided.
-        PCRE  does  not  allow \C to appear in lookbehind assertions (described
+        PCRE does not allow \C to appear in  lookbehind  assertions  (described
-        below), because in UTF-8 mode this would make it impossible  to  calcu-
+        below),  because  in UTF-8 mode this would make it impossible to calcu-
         late the length of the lookbehind.
-Line 2267 
 SQUARE BRACKETS AND CHARACTER CLASSES
+Line 3157 
 SQUARE BRACKETS AND CHARACTER CLASSES
         An opening square bracket introduces a character class, terminated by a
         closing square bracket. A closing square bracket on its own is not spe-
         cial. If a closing square bracket is required as a member of the class,
-        it should be the first data character in the class  (after  an  initial
+        it  should  be  the first data character in the class (after an initial
         circumflex, if present) or escaped with a backslash.
-        A  character  class matches a single character in the subject. In UTF-8
+        A character class matches a single character in the subject.  In  UTF-8
-        mode, the character may occupy more than one byte. A matched  character
+        mode,  the character may occupy more than one byte. A matched character
         must be in the set of characters defined by the class, unless the first
-        character in the class definition is a circumflex, in  which  case  the
+        character  in  the  class definition is a circumflex, in which case the
-        subject  character  must  not  be in the set defined by the class. If a
+        subject character must not be in the set defined by  the  class.  If  a
-        circumflex is actually required as a member of the class, ensure it  is
+        circumflex  is actually required as a member of the class, ensure it is
         not the first character, or escape it with a backslash.
-        For  example, the character class [aeiou] matches any lower case vowel,
+        For example, the character class [aeiou] matches any lower case  vowel,
-        while [^aeiou] matches any character that is not a  lower  case  vowel.
+        while  [^aeiou]  matches  any character that is not a lower case vowel.
         Note that a circumflex is just a convenient notation for specifying the
-        characters that are in the class by enumerating those that are  not.  A
+        characters  that  are in the class by enumerating those that are not. A
-        class  that starts with a circumflex is not an assertion: it still con-
+        class that starts with a circumflex is not an assertion: it still  con-
-        sumes a character from the subject string, and therefore  it  fails  if
+        sumes  a  character  from the subject string, and therefore it fails if
         the current pointer is at the end of the string.
-        In  UTF-8 mode, characters with values greater than 255 can be included
+        In UTF-8 mode, characters with values greater than 255 can be  included
-        in a class as a literal string of bytes, or by using the  \x{  escaping
+        in  a  class as a literal string of bytes, or by using the \x{ escaping
         mechanism.
-        When  caseless  matching  is set, any letters in a class represent both
+        When caseless matching is set, any letters in a  class  represent  both
-        their upper case and lower case versions, so for  example,  a  caseless
+        their  upper  case  and lower case versions, so for example, a caseless
-        [aeiou]  matches  "A"  as well as "a", and a caseless [^aeiou] does not
+        [aeiou] matches "A" as well as "a", and a caseless  [^aeiou]  does  not
-        match "A", whereas a caseful version would. When running in UTF-8 mode,
+        match  "A", whereas a caseful version would. In UTF-8 mode, PCRE always
-        PCRE  supports  the  concept of case for characters with values greater
+        understands the concept of case for characters whose  values  are  less
-        than 128 only when it is compiled with Unicode property support.
+        than  128, so caseless matching is always possible. For characters with
+        higher values, the concept of case is supported  if  PCRE  is  compiled
-        The newline character is never treated in any special way in  character
+        with  Unicode  property support, but not otherwise.  If you want to use
-        classes,  whatever  the  setting  of  the PCRE_DOTALL or PCRE_MULTILINE
+        caseless matching for characters 128 and above, you  must  ensure  that
-        options is. A class such as [^a] will always match a newline.
+        PCRE  is  compiled  with Unicode property support as well as with UTF-8
+        support.
+        Characters that might indicate line breaks are  never  treated  in  any
+        special  way  when  matching  character  classes,  whatever line-ending
+        sequence is in  use,  and  whatever  setting  of  the  PCRE_DOTALL  and
+        PCRE_MULTILINE options is used. A class such as [^a] always matches one
+        of these characters.
         The minus (hyphen) character can be used to specify a range of  charac-
         ters  in  a  character  class.  For  example,  [d-m] matches any letter
-Line 2400 
 VERTICAL BAR
+Line 3297 
 VERTICAL BAR
         matches  either "gilbert" or "sullivan". Any number of alternatives may
         appear, and an empty  alternative  is  permitted  (matching  the  empty
-        string).   The  matching  process  tries each alternative in turn, from
+        string). The matching process tries each alternative in turn, from left
-        left to right, and the first one that succeeds is used. If the alterna-
+        to right, and the first one that succeeds is used. If the  alternatives
-        tives  are within a subpattern (defined below), "succeeds" means match-
+        are  within a subpattern (defined below), "succeeds" means matching the
-        ing the rest of the main pattern as well as the alternative in the sub-
+        rest of the main pattern as well as the alternative in the  subpattern.
-        pattern.
  INTERNAL OPTION SETTING
-Line 2432 
 INTERNAL OPTION SETTING
+Line 3328 
 INTERNAL OPTION SETTING
         PCRE extracts it into the global options (and it will therefore show up
         in data extracted by the pcre_fullinfo() function).
-        An option change within a subpattern affects only that part of the cur-
+        An  option  change  within a subpattern (see below for a description of
-        rent pattern that follows it, so
+        subpatterns) affects only that part of the current pattern that follows
+        it, so
           (a(?i)b)c
         matches abc and aBc and no other strings (assuming PCRE_CASELESS is not
-        used).   By  this means, options can be made to have different settings
+        used).  By this means, options can be made to have  different  settings
-        in different parts of the pattern. Any changes made in one  alternative
+        in  different parts of the pattern. Any changes made in one alternative
-        do  carry  on  into subsequent branches within the same subpattern. For
+        do carry on into subsequent branches within the  same  subpattern.  For
         example,
           (a(?i)b|c)
-        matches "ab", "aB", "c", and "C", even though  when  matching  "C"  the
+        matches  "ab",  "aB",  "c",  and "C", even though when matching "C" the
-        first  branch  is  abandoned before the option setting. This is because
+        first branch is abandoned before the option setting.  This  is  because
-        the effects of option settings happen at compile time. There  would  be
+        the  effects  of option settings happen at compile time. There would be
         some very weird behaviour otherwise.
-        The  PCRE-specific  options PCRE_UNGREEDY and PCRE_EXTRA can be changed
+        The PCRE-specific options PCRE_DUPNAMES, PCRE_UNGREEDY, and  PCRE_EXTRA
-        in the same way as the Perl-compatible options by using the  characters
+        can  be changed in the same way as the Perl-compatible options by using
-        U  and X respectively. The (?X) flag setting is special in that it must
+        the characters J, U and X respectively.
-        always occur earlier in the pattern than any of the additional features
-        it  turns on, even when it is at top level. It is best to put it at the
-        start.
  SUBPATTERNS
-Line 2468 
 SUBPATTERNS
+Line 3362 
 SUBPATTERNS
           cat(aract|erpillar|)
         matches  one  of the words "cat", "cataract", or "caterpillar". Without
-        the parentheses, it would match "cataract",  "erpillar"  or  the  empty
+        the parentheses, it would match  "cataract",  "erpillar"  or  an  empty
         string.
 .  It  sets  up  the  subpattern as a capturing subpattern. This means
-Line 2497 
 SUBPATTERNS
+Line 3391 
 SUBPATTERNS
           the ((?:red|white) (king|queen))
         the captured substrings are "white queen" and "queen", and are numbered
- and 2. The maximum number of capturing subpatterns is 65535, and the
+and 2. The maximum number of capturing subpatterns is 65535.
-        maximum depth of nesting of all subpatterns, both  capturing  and  non-
-        capturing, is 200.
         As  a  convenient shorthand, if any option settings are required at the
         start of a non-capturing subpattern,  the  option  letters  may  appear
-Line 2521 
 NAMED SUBPATTERNS
+Line 3413 
 NAMED SUBPATTERNS
         very hard to keep track of the numbers in complicated  regular  expres-
         sions.  Furthermore,  if  an  expression  is  modified, the numbers may
         change. To help with this difficulty, PCRE supports the naming of  sub-
-        patterns,  something  that  Perl  does  not  provide. The Python syntax
+        patterns. This feature was not added to Perl until release 5.10. Python
-        (?P<name>...) is used. Names consist  of  alphanumeric  characters  and
+        had the feature earlier, and PCRE introduced it at release  4.0,  using
-        underscores, and must be unique within a pattern.
+        the  Python syntax. PCRE now supports both the Perl and the Python syn-
+        tax.
+        In PCRE, a subpattern can be named in one of three  ways:  (?<name>...)
+        or  (?'name'...)  as in Perl, or (?P<name>...) as in Python. References
+        to capturing parentheses from other parts of the pattern, such as back-
+        references,  recursion,  and conditions, can be made by name as well as
+        by number.
+        Names consist of up to  32  alphanumeric  characters  and  underscores.
         Named  capturing  parentheses  are  still  allocated numbers as well as
-        names. The PCRE API provides function calls for extracting the name-to-
+        names, exactly as if the names were not present. The PCRE API  provides
-        number  translation table from a compiled pattern. There is also a con-
+        function calls for extracting the name-to-number translation table from
-        venience function for extracting a captured substring by name. For fur-
+        a compiled pattern. There is also a convenience function for extracting
-        ther details see the pcreapi documentation.
+        a captured substring by name.
+        By  default, a name must be unique within a pattern, but it is possible
+        to relax this constraint by setting the PCRE_DUPNAMES option at compile
+        time.  This  can  be useful for patterns where only one instance of the
+        named parentheses can match. Suppose you want to match the  name  of  a
+        weekday,  either as a 3-letter abbreviation or as the full name, and in
+        both cases you want to extract the abbreviation. This pattern (ignoring
+        the line breaks) does the job:
+          (?<DN>Mon|Fri|Sun)(?:day)?|
+          (?<DN>Tue)(?:sday)?|
+          (?<DN>Wed)(?:nesday)?|
+          (?<DN>Thu)(?:rsday)?|
+          (?<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
+        returns  the  substring  for  the first (and in this example, the only)
+        subpattern of that name that matched.  This  saves  searching  to  find
+        which  numbered  subpattern  it  was. If you make a reference to a non-
+        unique named subpattern from elsewhere in the  pattern,  the  one  that
+        corresponds  to  the  lowest number is used. For further details of the
+        interfaces for handling named subpatterns, see the  pcreapi  documenta-
+        tion.
  REPETITION
-Line 2538 
 REPETITION
+Line 3462 
 REPETITION
         following items:
           a literal data character
-          the . metacharacter
+          the dot metacharacter
           the \C escape sequence
           the \X escape sequence (in UTF-8 mode with Unicode properties)
+          the \R escape sequence
           an escape such as \d that matches a single character
           a character class
           a back reference (see next section)
-Line 2580 
 REPETITION
+Line 3505 
 REPETITION
         The quantifier {0} is permitted, causing the expression to behave as if
         the previous item and the quantifier were not present.
-        For  convenience  (and  historical compatibility) the three most common
+        For  convenience, the three most common quantifiers have single-charac-
-        quantifiers have single-character abbreviations:
+        ter abbreviations:
           *    is equivalent to {0,}
           +    is equivalent to {1,}
-Line 2633 
 REPETITION
+Line 3558 
 REPETITION
         which matches one digit by preference, but can match two if that is the
         only way the rest of the pattern matches.
-        If the PCRE_UNGREEDY option is set (an option which is not available in
+        If the PCRE_UNGREEDY option is set (an option that is not available  in
         Perl),  the  quantifiers are not greedy by default, but individual ones
         can be made greedy by following them with a  question  mark.  In  other
         words, it inverts the default behaviour.
-Line 2644 
 REPETITION
+Line 3569 
 REPETITION
         minimum or maximum.
         If a pattern starts with .* or .{0,} and the PCRE_DOTALL option (equiv-
-        alent  to Perl's /s) is set, thus allowing the . to match newlines, the
+        alent  to  Perl's  /s) is set, thus allowing the dot to match newlines,
-        pattern is implicitly anchored, because whatever follows will be  tried
+        the pattern is implicitly anchored, because whatever  follows  will  be
-        against  every character position in the subject string, so there is no
+        tried  against every character position in the subject string, so there
-        point in retrying the overall match at any position  after  the  first.
+        is no point in retrying the overall match at  any  position  after  the
-        PCRE normally treats such a pattern as though it were preceded by \A.
+        first.  PCRE  normally treats such a pattern as though it were preceded
+        by \A.
-        In  cases  where  it  is known that the subject string contains no new-
+        In cases where it is known that the subject  string  contains  no  new-
-        lines, it is worth setting PCRE_DOTALL in order to  obtain  this  opti-
+        lines,  it  is  worth setting PCRE_DOTALL in order to obtain this opti-
         mization, or alternatively using ^ to indicate anchoring explicitly.
-        However,  there is one situation where the optimization cannot be used.
+        However, there is one situation where the optimization cannot be  used.
-        When .*  is inside capturing parentheses that  are  the  subject  of  a
+        When  .*   is  inside  capturing  parentheses that are the subject of a
-        backreference  elsewhere in the pattern, a match at the start may fail,
+        backreference elsewhere in the pattern, a match at the start  may  fail
-        and a later one succeed. Consider, for example:
+        where a later one succeeds. Consider, for example:
           (.*)abc\1
-        If the subject is "xyz123abc123" the match point is the fourth  charac-
+        If  the subject is "xyz123abc123" the match point is the fourth charac-
         ter. For this reason, such a pattern is not implicitly anchored.
         When a capturing subpattern is repeated, the value captured is the sub-
-Line 2670 
 REPETITION
+Line 3596 
 REPETITION
           (tweedle[dume]{3}\s*)+
         has matched "tweedledum tweedledee" the value of the captured substring
-        is  "tweedledee".  However,  if there are nested capturing subpatterns,
+        is "tweedledee". However, if there are  nested  capturing  subpatterns,
-        the corresponding captured values may have been set in previous  itera-
+        the  corresponding captured values may have been set in previous itera-
         tions. For example, after
           /(a|(b))+/
-Line 2681 
 REPETITION
+Line 3607 
 REPETITION
  ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS
-        With both maximizing and minimizing repetition, failure of what follows
+        With both maximizing ("greedy") and minimizing ("ungreedy"  or  "lazy")
-        normally causes the repeated item to be re-evaluated to see if  a  dif-
+        repetition,  failure  of what follows normally causes the repeated item
-        ferent number of repeats allows the rest of the pattern to match. Some-
+        to be re-evaluated to see if a different number of repeats  allows  the
-        times it is useful to prevent this, either to change the nature of  the
+        rest  of  the pattern to match. Sometimes it is useful to prevent this,
-        match,  or  to  cause it fail earlier than it otherwise might, when the
+        either to change the nature of the match, or to cause it  fail  earlier
-        author of the pattern knows there is no point in carrying on.
+        than  it otherwise might, when the author of the pattern knows there is
+        no point in carrying on.
         Consider, for example, the pattern \d+foo when applied to  the  subject
         line
-Line 2700 
 ATOMIC GROUPING AND POSSESSIVE QUANTIFIE
+Line 3627 
 ATOMIC GROUPING AND POSSESSIVE QUANTIFIE
         the  means for specifying that once a subpattern has matched, it is not
         to be re-evaluated in this way.
-        If we use atomic grouping for the previous example, the  matcher  would
+        If we use atomic grouping for the previous example, the  matcher  gives
-        give up immediately on failing to match "foo" the first time. The nota-
+        up  immediately  on failing to match "foo" the first time. The notation
-        tion is a kind of special parenthesis, starting with  (?>  as  in  this
+        is a kind of special parenthesis, starting with (?> as in this example:
-        example:
           (?>\d+)foo
-Line 2735 
 ATOMIC GROUPING AND POSSESSIVE QUANTIFIE
+Line 3661 
 ATOMIC GROUPING AND POSSESSIVE QUANTIFIE
         Possessive  quantifiers  are  always  greedy;  the   setting   of   the
         PCRE_UNGREEDY option is ignored. They are a convenient notation for the
         simpler forms of atomic group. However, there is no difference  in  the
-        meaning  or  processing  of  a possessive quantifier and the equivalent
+        meaning  of  a  possessive  quantifier and the equivalent atomic group,
-        atomic group.
+        though there may be a performance  difference;  possessive  quantifiers
+        should be slightly faster.
-        The possessive quantifier syntax is an extension to the Perl syntax. It
-        originates in Sun's Java package.
+        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
-        When  a  pattern  contains an unlimited repeat inside a subpattern that
+        edition of his book. Mike McCloskey liked it, so implemented it when he
-        can itself be repeated an unlimited number of  times,  the  use  of  an
+        built Sun's Java package, and PCRE copied it from there. It  ultimately
-        atomic  group  is  the  only way to avoid some failing matches taking a
+        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
+        A++B  because  there is no point in backtracking into a sequence of A's
+        when B must follow.