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

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-revision 90 by nigel,
Sat Feb 24 21:41:21 2007 UTC
+revision 91 by nigel,
Sat Feb 24 21:41:34 2007 UTC
 Line 81 
 USER DOCUMENTATION
           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
-Line 100 
 LIMITATIONS
+Line 101 
 LIMITATIONS
         In these cases the limit is substantially larger.  However,  the  speed
         of execution will be slower.
-        All values in repeating quantifiers must be less than 65536.  The 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
+        There  is  no limit to the number of non-capturing subpatterns, but the
-        maximum  depth  of  nesting  of  all kinds of parenthesized subpattern,
+        maximum depth of nesting of  all  kinds  of  parenthesized  subpattern,
         including capturing subpatterns, assertions, and other types of subpat-
         tern, is 200.
+        The maximum length of name for a named subpattern is 32, and the  maxi-
+        mum number of named subpatterns is 10000.
         The  maximum  length of a subject string is the largest positive number
         that an integer variable can hold. However, when using the  traditional
         matching function, PCRE uses recursion to handle subpatterns and indef-
         inite repetition.  This means that the available stack space may  limit
         the size of a subject string that can be processed by certain patterns.
+        For a discussion of stack issues, see the pcrestack documentation.
  UTF-8 AND UNICODE PROPERTY SUPPORT
-Line 162 
 UTF-8 AND UNICODE PROPERTY SUPPORT
+Line 168 
 UTF-8 AND UNICODE PROPERTY SUPPORT
 . An unbraced hexadecimal escape sequence (such  as  \xb3)  matches  a
         two-byte UTF-8 character if the value is greater than 127.
-.  Repeat quantifiers apply to complete UTF-8 characters, not to indi-
+.  Octal  numbers  up to \777 are recognized, and match two-byte UTF-8
+        characters for values greater than \177.
+. Repeat quantifiers apply to complete UTF-8 characters, not to  indi-
         vidual bytes, for example: \x{100}{3}.
-. The dot metacharacter matches one UTF-8 character instead of a  sin-
+.  The dot metacharacter matches one UTF-8 character instead of a sin-
         gle byte.
-.  The  escape sequence \C can be used to match a single byte in UTF-8
+. The escape sequence \C can be used to match a single byte  in  UTF-8
-        mode, but its use can lead to some strange effects.  This  facility  is
+        mode,  but  its  use can lead to some strange effects. This facility is
         not available in the alternative matching function, pcre_dfa_exec().
-.  The  character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly
+. The character escapes \b, \B, \d, \D, \s, \S, \w, and  \W  correctly
-        test characters of any code value, but the characters that PCRE  recog-
+        test  characters of any code value, but the characters that PCRE recog-
-        nizes  as  digits,  spaces,  or  word characters remain the same set as
+        nizes as digits, spaces, or word characters  remain  the  same  set  as
         before, all with values less than 256. This remains true even when PCRE
-        includes  Unicode  property support, because to do otherwise would slow
+        includes Unicode property support, because to do otherwise  would  slow
-        down PCRE in many common cases. If you really want to test for a  wider
+        down  PCRE in many common cases. If you really want to test for a wider
-        sense  of,  say,  "digit",  you must use Unicode property tests such as
+        sense of, say, "digit", you must use Unicode  property  tests  such  as
         \p{Nd}.
-. Similarly, characters that match the POSIX named  character  classes
+.  Similarly,  characters that match the POSIX named character classes
         are all low-valued characters.
-.  Case-insensitive  matching  applies only to characters whose values
+. 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. Even when Unicode property
         support is available, PCRE supports case-insensitive matching only when
-        there is a one-to-one mapping between a letter's  cases.  There  are  a
+        there  is  a  one-to-one  mapping between a letter's cases. There are a
-        small  number  of  many-to-one  mappings in Unicode; these are not sup-
+        small number of many-to-one mappings in Unicode;  these  are  not  sup-
         ported by PCRE.
-Line 202 
 AUTHOR
+Line 211 
 AUTHOR
         University Computing Service,
         Cambridge CB2 3QG, England.
-        Putting an actual email address here seems to have been a spam  magnet,
+        Putting  an actual email address here seems to have been a spam magnet,
         so I've taken it away. If you want to email me, use my initial and sur-
         name, separated by a dot, at the domain ucs.cam.ac.uk.
- Last updated: 24 January 2006
+ Last updated: 05 June 2006
  Copyright (c) 1997-2006 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 281 
 UNICODE CHARACTER PROPERTY SUPPORT
+Line 290 
 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. 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
-Line 320 
 POSIX MALLOC USAGE
+Line 339 
 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   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.
  HANDLING VERY LARGE PATTERNS
         Within  a  compiled  pattern,  offset values are used to point from one
-Line 366 
 AVOIDING EXCESSIVE STACK USAGE
+Line 368 
 AVOIDING EXCESSIVE STACK USAGE
         ing by making recursive calls to an internal function  called  match().
         In  environments  where  the size of the stack is limited, this can se-
         verely limit PCRE's operation. (The Unix environment does  not  usually
-        suffer  from  this  problem.)  An alternative approach that uses memory
+        suffer from this problem, but it may sometimes be necessary to increase
-        from the heap to remember data, instead  of  using  recursive  function
+        the maximum stack size.  There is a discussion in the  pcrestack  docu-
-        calls,  has been implemented to work round this problem. If you want to
+        mentation.)  An alternative approach to recursion that uses memory from
-        build a version of PCRE that works 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
-Line 384 
 AVOIDING EXCESSIVE STACK USAGE
+Line 388 
 AVOIDING EXCESSIVE STACK USAGE
         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: 15 August 2005
+ Last updated: 06 June 2006
- Copyright (c) 1997-2005 University of Cambridge.
+ Copyright (c) 1997-2006 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 441 
 REGULAR EXPRESSIONS AS TREES
+Line 475 
 REGULAR EXPRESSIONS AS TREES
         resented  as  a  tree structure. An unlimited repetition in the pattern
         makes the tree of infinite size, but it is still a tree.  Matching  the
         pattern  to a given subject string (from a given starting point) can be
-        thought of as a search of the tree.  There are  two  standard  ways  to
+        thought of as a search of the tree.  There are two  ways  to  search  a
-        search  a  tree: depth-first and breadth-first, and these correspond to
+        tree:  depth-first  and  breadth-first, and these correspond to the two
-        the two matching algorithms provided by PCRE.
+        matching algorithms provided by PCRE.
  THE STANDARD MATCHING ALGORITHM
-Line 563 
 DISADVANTAGES OF THE DFA ALGORITHM
+Line 597 
 DISADVANTAGES OF THE DFA ALGORITHM
         but  does not provide the advantage that it does for the standard algo-
         rithm.
- Last updated: 28 February 2005
+ Last updated: 06 June 2006
- Copyright (c) 1997-2005 University of Cambridge.
+ Copyright (c) 1997-2006 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 617 
 PCRE NATIVE API
+Line 651 
 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 677 
 PCRE API OVERVIEW
+Line 714 
 PCRE API OVERVIEW
         A second matching function, pcre_dfa_exec(), which is not Perl-compati-
         ble,  is  also provided. This uses a different algorithm for the match-
-        ing. This allows it to find all possible matches (at a given  point  in
+        ing. The alternative algorithm finds all possible matches (at  a  given
-        the  subject),  not  just  one. However, this algorithm does not return
+        point in the subject). However, this algorithm does not return captured
-        captured substrings. A description of the two matching  algorithms  and
+        substrings. A description of the  two  matching  algorithms  and  their
-        their  advantages  and disadvantages is given in the pcrematching docu-
+        advantages  and  disadvantages  is given in the pcrematching documenta-
-        mentation.
+        tion.
         In addition to the main compiling and  matching  functions,  there  are
         convenience functions for extracting captured substrings from a subject
-Line 693 
 PCRE API OVERVIEW
+Line 730 
 PCRE API OVERVIEW
           pcre_get_named_substring()
           pcre_get_substring_list()
           pcre_get_stringnumber()
+          pcre_get_stringtable_entries()
         pcre_free_substring() and pcre_free_substring_list() are also provided,
         to free the memory used for extracted strings.
-Line 724 
 PCRE API OVERVIEW
+Line 762 
 PCRE API OVERVIEW
         indirections  to  memory  management functions. These special functions
         are used only when PCRE is compiled to use  the  heap  for  remembering
         data, instead of recursive function calls, when running the pcre_exec()
-        function. This is a non-standard way of building PCRE, for use in envi-
+        function. See the pcrebuild documentation for  details  of  how  to  do
-        ronments that have limited stacks. Because of the greater use of memory
+        this.  It  is  a non-standard way of building PCRE, for use in environ-
-        management, it runs more slowly.  Separate functions  are  provided  so
+        ments that have limited stacks. Because of the greater  use  of  memory
-        that  special-purpose  external  code  can  be used for this case. When
+        management,  it  runs  more  slowly. Separate functions are provided so
-        used, these functions are always called in a  stack-like  manner  (last
+        that special-purpose external code can be  used  for  this  case.  When
-        obtained,  first freed), and always for memory blocks of the same size.
+        used,  these  functions  are always called in a stack-like manner (last
+        obtained, first freed), and always for memory blocks of the same  size.
+        There  is  a discussion about PCRE's stack usage in the pcrestack docu-
+        mentation.
         The global variable pcre_callout initially contains NULL. It can be set
         by  the  caller  to  a "callout" function, which PCRE will then call at
-Line 737 
 PCRE API OVERVIEW
+Line 778 
 PCRE API OVERVIEW
         pcrecallout documentation.
+ NEWLINES
+        PCRE supports three different conventions for indicating line breaks in
+        strings: a single CR character, a single LF character, or the two-char-
+        acter  sequence  CRLF.  All  three  are used as "standard" by different
+        operating systems.  When PCRE is built, a default can be specified. The
+        default  default  is  LF, which is the Unix standard. 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".
  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 752 
 MULTITHREADING
+Line 806 
 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 761 
 CHECKING BUILD-TIME OPTIONS
+Line 815 
 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 three values that
-        return (13), and should normally be the  standard  character  for  your
+        are supported are: 10 for LF, 13 for CR, and 3338 for CRLF. The default
-        operating system.
+        should normally be the standard sequence for your operating system.
           PCRE_CONFIG_LINK_SIZE
-        The  output  is  an  integer that contains the number of bytes used for
+        The output is an integer that contains the number  of  bytes  used  for
         internal linkage in compiled regular expressions. The value is 2, 3, or
-.  Larger  values  allow larger regular expressions to be compiled, at
+. Larger values allow larger regular expressions to  be  compiled,  at
-        the expense of slower matching. The default value of  2  is  sufficient
+        the  expense  of  slower matching. The default value of 2 is sufficient
-        for  all  but  the  most massive patterns, since it allows the compiled
+        for all but the most massive patterns, since  it  allows  the  compiled
         pattern to be up to 64K in size.
           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
-        The output is an integer that contains the threshold  above  which  the
+        The  output  is  an integer that contains the threshold above which the
-        POSIX  interface  uses malloc() for output vectors. Further details are
+        POSIX interface uses malloc() for output vectors. Further  details  are
         given in the pcreposix documentation.
           PCRE_CONFIG_MATCH_LIMIT
         The output is an integer that gives the default limit for the number of
-        internal  matching  function  calls in a pcre_exec() execution. Further
+        internal matching function calls in a  pcre_exec()  execution.  Further
         details are given with pcre_exec() below.
           PCRE_CONFIG_MATCH_LIMIT_RECURSION
-        The output is an integer that gives the default limit for the depth  of
+        The  output is an integer that gives the default limit for the depth of
-        recursion  when calling the internal matching function in a pcre_exec()
+        recursion when calling the internal matching function in a  pcre_exec()
         execution. Further details are given with pcre_exec() below.
           PCRE_CONFIG_STACKRECURSE
-        The output is an integer that is set to one if internal recursion  when
+        The  output is an integer that is set to one if internal recursion when
         running pcre_exec() is implemented by recursive function calls that use
-        the stack to remember their state. This is the usual way that  PCRE  is
+        the  stack  to remember their state. This is the usual way that PCRE is
         compiled. The output is zero if PCRE was compiled to use blocks of data
-        on the  heap  instead  of  recursive  function  calls.  In  this  case,
+        on  the  heap  instead  of  recursive  function  calls.  In  this case,
-        pcre_stack_malloc  and  pcre_stack_free  are  called  to  manage memory
+        pcre_stack_malloc and  pcre_stack_free  are  called  to  manage  memory
         blocks on the heap, thus avoiding the use of the stack.
-Line 839 
 COMPILING A PATTERN
+Line 893 
 COMPILING A PATTERN
         Either of the functions pcre_compile() or pcre_compile2() can be called
         to compile a pattern into an internal form. The only difference between
-        the two interfaces is that pcre_compile2() has an additional  argument,
+        the  two interfaces is that pcre_compile2() has an additional argument,
         errorcodeptr, via which a numerical error code can be returned.
         The pattern is a C string terminated by a binary zero, and is passed in
-        the pattern argument. A pointer to a single block  of  memory  that  is
+        the  pattern  argument.  A  pointer to a single block of memory that is
-        obtained  via  pcre_malloc is returned. This contains the compiled code
+        obtained via pcre_malloc is returned. This contains the  compiled  code
         and related data. The pcre type is defined for the returned block; this
         is a typedef for a structure whose contents are not externally defined.
-        It is up to the caller  to  free  the  memory  when  it  is  no  longer
+        It is up to the caller to free the memory (via pcre_free) when it is no
-        required.
+        longer required.
-        Although  the compiled code of a PCRE regex is relocatable, that is, it
+        Although the compiled code of a PCRE regex is relocatable, that is,  it
         does not depend on memory location, the complete pcre data block is not
-        fully  relocatable, because it may contain a copy of the tableptr argu-
+        fully relocatable, because it may contain a copy of the tableptr  argu-
         ment, which is an address (see below).
         The options argument contains independent bits that affect the compila-
-        tion.  It  should  be  zero  if  no options are required. The available
+        tion. It should be zero if  no  options  are  required.  The  available
-        options are described below. Some of them, in  particular,  those  that
+        options  are  described  below. Some of them, in particular, those that
-        are  compatible  with  Perl,  can also be set and unset from within the
+        are compatible with Perl, can also be set and  unset  from  within  the
-        pattern (see the detailed description  in  the  pcrepattern  documenta-
+        pattern  (see  the  detailed  description in the pcrepattern documenta-
-        tion).  For  these options, the contents of the options argument speci-
+        tion). For these options, the contents of the options  argument  speci-
-        fies their initial settings at the start of compilation and  execution.
+        fies  their initial settings at the start of compilation and execution.
-        The  PCRE_ANCHORED 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
+        if compilation of a pattern fails,  pcre_compile()  returns  NULL,  and
         sets the variable pointed to by errptr to point to a textual error mes-
         sage. This is a static string that is part of the library. You must not
         try to free it. The offset from the start of the pattern to the charac-
         ter where the error was discovered is placed in the variable pointed to
-        by erroffset, which must not be NULL. If it is, an immediate  error  is
+        by  erroffset,  which must not be NULL. If it is, an immediate error is
         given.
-        If  pcre_compile2()  is  used instead of pcre_compile(), and the error-
+        If pcre_compile2() is used instead of pcre_compile(),  and  the  error-
-        codeptr argument is not NULL, a non-zero error code number is  returned
+        codeptr  argument is not NULL, a non-zero error code number is returned
-        via  this argument in the event of an error. This is in addition to the
+        via this argument in the event of an error. This is in addition to  the
         textual error message. Error codes and messages are listed below.
-        If the final argument, tableptr, is NULL, PCRE uses a  default  set  of
+        If  the  final  argument, tableptr, is NULL, PCRE uses a default set of
-        character  tables  that  are  built  when  PCRE  is compiled, using the
+        character tables that are  built  when  PCRE  is  compiled,  using  the
-        default C locale. Otherwise, tableptr must be an address  that  is  the
+        default  C  locale.  Otherwise, tableptr must be an address that is the
-        result  of  a  call to pcre_maketables(). This value is stored with the
+        result of a call to pcre_maketables(). This value is  stored  with  the
-        compiled pattern, and used again by pcre_exec(), unless  another  table
+        compiled  pattern,  and used again by pcre_exec(), unless another table
         pointer is passed to it. For more discussion, see the section on locale
         support below.
-        This code fragment shows a typical straightforward  call  to  pcre_com-
+        This  code  fragment  shows a typical straightforward call to pcre_com-
         pile():
           pcre *re;
-Line 900 
 COMPILING A PATTERN
+Line 954 
 COMPILING A PATTERN
             &erroffset,       /* for error offset */
             NULL);            /* use default character tables */
-        The  following  names  for option bits are defined in the pcre.h header
+        The following names for option bits are defined in  the  pcre.h  header
         file:
           PCRE_ANCHORED
         If this bit is set, the pattern is forced to be "anchored", that is, it
-        is  constrained to match only at the first matching point in the string
+        is constrained to match only at the first matching point in the  string
-        that is being searched (the "subject string"). This effect can also  be
+        that  is being searched (the "subject string"). This effect can also be
-        achieved  by appropriate constructs in the pattern itself, which is the
+        achieved by appropriate constructs in the pattern itself, which is  the
         only way to do it in Perl.
           PCRE_AUTO_CALLOUT
         If this bit is set, pcre_compile() automatically inserts callout items,
-        all  with  number  255, before each pattern item. For discussion of the
+        all with number 255, before each pattern item. For  discussion  of  the
         callout facility, see the pcrecallout documentation.
           PCRE_CASELESS
-        If this bit is set, letters in the pattern match both upper  and  lower
+        If  this  bit is set, letters in the pattern match both upper and lower
-        case  letters.  It  is  equivalent  to  Perl's /i option, and it can be
+        case letters. It is equivalent to Perl's  /i  option,  and  it  can  be
-        changed within a pattern by a (?i) option setting. In UTF-8 mode,  PCRE
+        changed  within a pattern by a (?i) option setting. In UTF-8 mode, PCRE
-        always  understands the concept of case for characters whose values are
+        always understands the concept of case for characters whose values  are
-        less than 128, so caseless matching is always possible. For  characters
+        less  than 128, so caseless matching is always possible. For characters
-        with  higher  values,  the concept of case is supported if PCRE is com-
+        with higher values, the concept of case is supported if  PCRE  is  com-
-        piled with Unicode property support, but not otherwise. If you want  to
+        piled  with Unicode property support, but not otherwise. If you want to
-        use  caseless  matching  for  characters 128 and above, you must ensure
+        use caseless matching for characters 128 and  above,  you  must  ensure
-        that PCRE is compiled with Unicode property support  as  well  as  with
+        that  PCRE  is  compiled  with Unicode property support as well as with
         UTF-8 support.
           PCRE_DOLLAR_ENDONLY
-        If  this bit is set, a dollar metacharacter in the pattern matches only
+        If this bit is set, a dollar metacharacter in the pattern matches  only
-        at the end of the subject string. Without this option,  a  dollar  also
+        at  the  end  of the subject string. Without this option, a dollar also
-        matches  immediately before the final character if it is a newline (but
+        matches immediately before a newline at the end of the string (but  not
-        not before any  other  newlines).  The  PCRE_DOLLAR_ENDONLY  option  is
+        before  any  other newlines). The PCRE_DOLLAR_ENDONLY option is ignored
-        ignored if PCRE_MULTILINE is set. There is no equivalent to this option
+        if PCRE_MULTILINE is set.  There is no equivalent  to  this  option  in
-        in Perl, and no way to set it within a pattern.
+        Perl, and no way to set it within a pattern.
           PCRE_DOTALL
         If this bit is set, a dot metacharater in the pattern matches all char-
-        acters,  including  newlines.  Without  it, newlines are excluded. This
+        acters, including those that indicate newline. Without it, a  dot  does
-        option is equivalent to Perl's /s option, and it can be changed  within
+        not  match  when  the  current position is at a newline. This option is
-        a  pattern  by  a  (?s)  option  setting. A negative class such as [^a]
+        equivalent to Perl's /s option, and it can be changed within a  pattern
-        always matches a newline character, independent of the setting of  this
+        by  a (?s) option setting. A negative class such as [^a] always matches
-        option.
+        newlines, independent of the setting of this option.
+          PCRE_DUPNAMES
+        If this bit is set, names used to identify capturing  subpatterns  need
+        not be unique. This can be helpful for certain types of pattern when it
+        is known that only one instance of the named  subpattern  can  ever  be
+        matched.  There  are  more details of named subpatterns below; see also
+        the pcrepattern documentation.
           PCRE_EXTENDED
-        If  this  bit  is  set,  whitespace  data characters in the pattern are
+        If this bit is set, whitespace  data  characters  in  the  pattern  are
         totally ignored except when escaped or inside a character class. White-
         space does not include the VT character (code 11). In addition, charac-
         ters between an unescaped # outside a character class and the next new-
-        line  character,  inclusive,  are  also  ignored. This is equivalent to
+        line, inclusive, are also ignored. This  is  equivalent  to  Perl's  /x
-        Perl's /x option, and it can be changed within  a  pattern  by  a  (?x)
+        option,  and  it  can be changed within a pattern by a (?x) option set-
-        option setting.
+        ting.
-        This  option  makes  it possible to include comments inside complicated
+        This option makes it possible to include  comments  inside  complicated
-        patterns.  Note, however, that this applies only  to  data  characters.
+        patterns.   Note,  however,  that this applies only to data characters.
-        Whitespace   characters  may  never  appear  within  special  character
+        Whitespace  characters  may  never  appear  within  special   character
-        sequences in a pattern, for  example  within  the  sequence  (?(  which
+        sequences  in  a  pattern,  for  example  within the sequence (?( which
         introduces a conditional subpattern.
           PCRE_EXTRA
-        This  option  was invented in order to turn on additional functionality
+        This option was invented in order to turn on  additional  functionality
-        of PCRE that is incompatible with Perl, but it  is  currently  of  very
+        of  PCRE  that  is  incompatible with Perl, but it is currently of very
-        little  use. When set, any backslash in a pattern that is followed by a
+        little use. When set, any backslash in a pattern that is followed by  a
-        letter that has no special meaning  causes  an  error,  thus  reserving
+        letter  that  has  no  special  meaning causes an error, thus reserving
-        these  combinations  for  future  expansion.  By default, as in Perl, a
+        these combinations for future expansion. By  default,  as  in  Perl,  a
-        backslash followed by a letter with no special meaning is treated as  a
+        backslash  followed by a letter with no special meaning is treated as a
-        literal.  There  are  at  present  no other features controlled by this
+        literal. (Perl can, however, be persuaded to give a warning for  this.)
-        option. It can also be set by a (?X) option setting within a pattern.
+        There  are  at  present no other features controlled by this option. It
+        can also be set by a (?X) option setting within a pattern.
           PCRE_FIRSTLINE
         If this option is set, an  unanchored  pattern  is  required  to  match
-        before  or at the first newline character in the subject string, though
+        before  or  at  the  first  newline  in  the subject string, though the
-        the matched text may continue over the newline.
+        matched text may continue over the newline.
           PCRE_MULTILINE
-Line 991 
 COMPILING A PATTERN
+Line 1054 
 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
+        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 both of them specifies that a newline is indicated by the  two-
+        character  CRLF sequence. For convenience, PCRE_NEWLINE_CRLF is defined
+        to contain both bits. The only time that a line break is relevant  when
+        compiling a pattern is if PCRE_EXTENDED is set, and an unescaped # out-
+        side a character class is encountered. This indicates  a  comment  that
+        lasts until after the next newline.
+        The newline option 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() and pcre_dfa_exec(), to suppress the UTF-8 validity  check-
+        pcre_exec()  and pcre_dfa_exec(), to suppress the UTF-8 validity check-
         ing of subject strings.
  COMPILATION ERROR CODES
-        The  following  table  lists  the  error  codes than may be returned by
+        The following table lists the error  codes  than  may  be  returned  by
-        pcre_compile2(), along with the error messages that may be returned  by
+        pcre_compile2(),  along with the error messages that may be returned by
         both compiling functions.
  no error
-Line 1067 
 COMPILATION ERROR CODES
+Line 1147 
 COMPILATION ERROR CODES
  internal error: code overflow
  unrecognized character after (?<
  lookbehind assertion is not fixed length
- malformed number after (?(
+ malformed number or name after (?(
  conditional group contains more than two branches
  assertion expected after (?(
  (?R or (?digits must be followed by )
-Line 1084 
 COMPILATION ERROR CODES
+Line 1164 
 COMPILATION ERROR CODES
  recursive call could loop indefinitely
  unrecognized character after (?P
  syntax error after (?P
- two named groups have the same name
+ two named subpatterns have the same name
  invalid UTF-8 string
  support for \P, \p, and \X has not been compiled
  malformed \P or \p sequence
  unknown property name after \P or \p
+ subpattern name is too long (maximum 32 characters)
+ too many named subpatterns (maximum 10,000)
+ repeated subpattern is too long
+ octal value is greater than \377 (not in UTF-8 mode)
  STUDYING A PATTERN
-Line 1096 
 STUDYING A PATTERN
+Line 1180 
 STUDYING A PATTERN
         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 is set to  point  to  a  textual
+        points  to  is  set  to NULL. Otherwise it is set to point to a textual
         error message. This is a static string that is part of the library. You
-        must not try to free it. You should test the  error  pointer  for  NULL
+        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 1133 
 STUDYING A PATTERN
+Line 1217 
 STUDYING A PATTERN
             &error);        /* set to NULL or points to a message */
         At present, studying a pattern is useful only for non-anchored patterns
-        that do not have a single fixed starting character. A bitmap of  possi-
+        that  do not have a single fixed starting character. A bitmap of possi-
         ble starting bytes is created.
  LOCALE SUPPORT
-        PCRE  handles  caseless matching, and determines whether characters are
+        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
+        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
+        escapes such as \w or \d, but can be tested with \p if  PCRE  is  built
-        with Unicode character property support. The use of locales  with  Uni-
+        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 1188 
 INFORMATION ABOUT A PATTERN
+Line 1272 
 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 1204 
 INFORMATION ABOUT A PATTERN
+Line 1288 
 INFORMATION ABOUT A PATTERN
           PCRE_ERROR_BADMAGIC   the "magic number" was not found
           PCRE_ERROR_BADOPTION  the value of what was invalid
-        The  "magic  number" is placed at the start of each compiled pattern as
+        The "magic number" is placed at the start of each compiled  pattern  as
-        an simple check against passing an arbitrary memory pointer. Here is  a
+        an  simple check against passing an arbitrary memory pointer. Here is a
-        typical  call  of pcre_fullinfo(), to obtain the length of the compiled
+        typical call of pcre_fullinfo(), to obtain the length of  the  compiled
         pattern:
           int rc;
-          unsigned long int length;
+          size_t length;
           rc = pcre_fullinfo(
             re,               /* result of pcre_compile() */
             pe,               /* result of pcre_study(), or NULL */
             PCRE_INFO_SIZE,   /* what is required */
             &length);         /* where to put the data */
-        The possible values for the third argument are defined in  pcre.h,  and
+        The  possible  values for the third argument are defined in pcre.h, and
         are as follows:
           PCRE_INFO_BACKREFMAX
-        Return  the  number  of  the highest back reference in the pattern. The
+        Return the number of the highest back reference  in  the  pattern.  The
-        fourth argument should point to an int variable. Zero  is  returned  if
+        fourth  argument  should  point to an int variable. Zero is returned if
         there are no back references.
           PCRE_INFO_CAPTURECOUNT
-        Return  the  number of capturing subpatterns in the pattern. The fourth
+        Return the number of capturing subpatterns in the pattern.  The  fourth
         argument should point to an int variable.
           PCRE_INFO_DEFAULT_TABLES
-        Return a pointer to the internal default character tables within  PCRE.
+        Return  a pointer to the internal default character tables within PCRE.
-        The  fourth  argument should point to an unsigned char * variable. This
+        The fourth argument should point to an unsigned char *  variable.  This
         information call is provided for internal use by the pcre_study() func-
-        tion.  External  callers  can  cause PCRE to use its internal tables by
+        tion. External callers can cause PCRE to use  its  internal  tables  by
         passing a NULL table pointer.
           PCRE_INFO_FIRSTBYTE
-        Return information about the first byte of any matched  string,  for  a
+        Return  information  about  the first byte of any matched string, for a
-        non-anchored    pattern.    (This    option    used    to   be   called
+        non-anchored pattern. The fourth argument should point to an int  vari-
-        PCRE_INFO_FIRSTCHAR; the old name is  still  recognized  for  backwards
+        able.  (This option used to be called PCRE_INFO_FIRSTCHAR; the old name
-        compatibility.)
+        is still recognized for backwards compatibility.)
-        If  there  is  a  fixed first byte, for example, from a pattern such as
+        If there is a fixed first byte, for example, from  a  pattern  such  as
-        (cat|cow|coyote), it is returned in the integer pointed  to  by  where.
+        (cat|cow|coyote). Otherwise, if either
-        Otherwise, if either
         (a)  the pattern was compiled with the PCRE_MULTILINE option, and every
         branch starts with "^", or
-Line 1284 
 INFORMATION ABOUT A PATTERN
+Line 1367 
 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 1300 
 INFORMATION ABOUT A PATTERN
+Line 1383 
 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) -
           (?P<month>\d\d) - (?P<day>\d\d) )
-Line 1317 
 INFORMATION ABOUT A PATTERN
+Line 1402 
 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 1517 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 1602 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
     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
+        These options override  the  newline  definition  that  was  chosen  or
+        defaulted  when the pattern was compiled. For details, see the descrip-
+        tion pcre_compile() above. During matching, the newline choice  affects
+        the behaviour of the dot, circumflex, and dollar metacharacters.
           PCRE_NOTBOL
         This option specifies that first character of the subject string is not
-Line 1662 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 1757 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
         after  the  end  of  a  substring. The first pair, ovector[0] and ovec-
         tor[1], identify the portion of  the  subject  string  matched  by  the
         entire  pattern.  The next pair is used for the first capturing subpat-
-        tern, and so on. The value returned by pcre_exec()  is  the  number  of
+        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.
-        If the vector is too small to hold all the captured substring  offsets,
+        If  the vector is too small to hold all the captured substring offsets,
         it is used as far as possible (up to two-thirds of its length), and the
-        function returns a value of zero. In particular, if the substring  off-
+        function  returns a value of zero. In particular, if the substring off-
         sets are not of interest, pcre_exec() may be called with ovector passed
-        as NULL and ovecsize as zero. However, if  the  pattern  contains  back
+        as  NULL  and  ovecsize  as zero. However, if the pattern contains back
-        references  and  the  ovector is not big enough to remember the related
+        references and the ovector is not big enough to  remember  the  related
-        substrings, PCRE has to get additional memory for use during  matching.
+        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
+        If  pcre_exec()  fails, it returns a negative number. The following are
         defined in the header file:
           PCRE_ERROR_NOMATCH        (-1)
-Line 1705 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 1809 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
           PCRE_ERROR_NULL           (-2)
-        Either  code  or  subject  was  passed as NULL, or ovector was NULL and
+        Either code or subject was passed as NULL,  or  ovector  was  NULL  and
         ovecsize was not zero.
           PCRE_ERROR_BADOPTION      (-3)
-Line 1714 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 1818 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
           PCRE_ERROR_BADMAGIC       (-4)
-        PCRE stores a 4-byte "magic number" at the start of the compiled  code,
+        PCRE  stores a 4-byte "magic number" at the start of the compiled code,
         to catch the case when it is passed a junk pointer and to detect when a
         pattern that was compiled in an environment of one endianness is run in
-        an  environment  with the other endianness. This is the error that PCRE
+        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)
         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
+        compiled pattern. This error could be caused by a bug  in  PCRE  or  by
         overwriting of the compiled pattern.
           PCRE_ERROR_NOMEMORY       (-6)
-        If a pattern contains back references, but the ovector that  is  passed
+        If  a  pattern contains back references, but the ovector that is passed
         to pcre_exec() is not big enough to remember the referenced substrings,
-        PCRE gets a block of memory at the start of matching to  use  for  this
+        PCRE  gets  a  block of memory at the start of matching to use for this
-        purpose.  If the call via pcre_malloc() fails, this error is given. The
+        purpose. If the call via pcre_malloc() fails, this error is given.  The
         memory is automatically freed at the end of matching.
           PCRE_ERROR_NOSUBSTRING    (-7)
-        This error is used by the pcre_copy_substring(),  pcre_get_substring(),
+        This  error is used by the pcre_copy_substring(), pcre_get_substring(),
         and  pcre_get_substring_list()  functions  (see  below).  It  is  never
         returned by pcre_exec().
           PCRE_ERROR_MATCHLIMIT     (-8)
-        The backtracking limit, as specified by  the  match_limit  field  in  a
+        The  backtracking  limit,  as  specified  by the match_limit field in a
-        pcre_extra  structure  (or  defaulted) was reached. See the description
+        pcre_extra structure (or defaulted) was reached.  See  the  description
         above.
           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
+        field in a pcre_extra structure (or defaulted)  was  reached.  See  the
         description above.
           PCRE_ERROR_CALLOUT        (-9)
         This error is never generated by pcre_exec() itself. It is provided for
-        use  by  callout functions that want to yield a distinctive error code.
+        use by callout functions that want to yield a distinctive  error  code.
         See the pcrecallout documentation for details.
           PCRE_ERROR_BADUTF8        (-10)
-        A string that contains an invalid UTF-8 byte sequence was passed  as  a
+        A  string  that contains an invalid UTF-8 byte sequence was passed as a
         subject.
           PCRE_ERROR_BADUTF8_OFFSET (-11)
         The UTF-8 byte sequence that was passed as a subject was valid, but the
-        value of startoffset did not point to the beginning of a UTF-8  charac-
+        value  of startoffset did not point to the beginning of a UTF-8 charac-
         ter.
           PCRE_ERROR_PARTIAL        (-12)
-        The  subject  string did not match, but it did match partially. See the
+        The subject string did not match, but it did match partially.  See  the
         pcrepartial documentation for details of partial matching.
           PCRE_ERROR_BADPARTIAL     (-13)
-        The PCRE_PARTIAL option was used with  a  compiled  pattern  containing
+        The  PCRE_PARTIAL  option  was  used with a compiled pattern containing
-        items  that are not supported for partial matching. See the pcrepartial
+        items that are not supported for partial matching. See the  pcrepartial
         documentation for details of partial matching.
           PCRE_ERROR_INTERNAL       (-14)
-        An unexpected internal error has occurred. This error could  be  caused
+        An  unexpected  internal error has occurred. This error could be caused
         by a bug in PCRE or by overwriting of the compiled pattern.
           PCRE_ERROR_BADCOUNT       (-15)
-        This  error is given if the value of the ovecsize argument is negative.
+        This error is given if the value of the ovecsize argument is  negative.
  EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
-Line 1803 
 EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
+Line 1907 
 EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
         int pcre_get_substring_list(const char *subject,
              int *ovector, int stringcount, const char ***listptr);
-        Captured substrings can be  accessed  directly  by  using  the  offsets
+        Captured  substrings  can  be  accessed  directly  by using the offsets
-        returned  by  pcre_exec()  in  ovector.  For convenience, the functions
+        returned by pcre_exec() in  ovector.  For  convenience,  the  functions
         pcre_copy_substring(),    pcre_get_substring(),    and    pcre_get_sub-
-        string_list()  are  provided for extracting captured substrings as new,
+        string_list() are provided for extracting captured substrings  as  new,
-        separate, zero-terminated strings. These functions identify  substrings
+        separate,  zero-terminated strings. These functions identify substrings
-        by  number.  The  next section describes functions for extracting named
+        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-
+        The  first  three  arguments  are the same for all three of these func-
-        tions:  subject  is  the subject string that has just been successfully
+        tions: subject is the subject string that has  just  been  successfully
         matched, ovector is a pointer to the vector of integer offsets that was
         passed to pcre_exec(), and stringcount is the number of substrings that
-        were captured by the match, including the substring  that  matched  the
+        were  captured  by  the match, including the substring that matched the
         entire regular expression. This is the value returned by pcre_exec() if
-        it is greater than zero. If pcre_exec() returned zero, indicating  that
+        it  is greater than zero. If pcre_exec() returned zero, indicating that
-        it  ran out of space in ovector, the value passed as stringcount should
+        it ran out of space in ovector, the value passed as stringcount  should
         be the number of elements in the vector divided by three.
-        The functions pcre_copy_substring() and pcre_get_substring() extract  a
+        The  functions pcre_copy_substring() and pcre_get_substring() extract a
-        single  substring,  whose  number  is given as stringnumber. A value of
+        single substring, whose number is given as  stringnumber.  A  value  of
-        zero extracts the substring that matched the  entire  pattern,  whereas
+        zero  extracts  the  substring that matched the entire pattern, whereas
-        higher  values  extract  the  captured  substrings.  For pcre_copy_sub-
+        higher values  extract  the  captured  substrings.  For  pcre_copy_sub-
-        string(), the string is placed in buffer,  whose  length  is  given  by
+        string(),  the  string  is  placed  in buffer, whose length is given by
-        buffersize,  while  for  pcre_get_substring()  a new block of memory is
+        buffersize, while for pcre_get_substring() a new  block  of  memory  is
-        obtained via pcre_malloc, and its address is  returned  via  stringptr.
+        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 yield of the function is the length of the  string,  not  including
         the terminating zero, or one of
           PCRE_ERROR_NOMEMORY       (-6)
-        The buffer was too small for pcre_copy_substring(), or the  attempt  to
+        The  buffer  was too small for pcre_copy_substring(), or the attempt to
         get memory failed for pcre_get_substring().
           PCRE_ERROR_NOSUBSTRING    (-7)
         There is no substring whose number is stringnumber.
-        The  pcre_get_substring_list()  function  extracts  all  available sub-
+        The pcre_get_substring_list()  function  extracts  all  available  sub-
-        strings and builds a list of pointers to them. All this is  done  in  a
+        strings  and  builds  a list of pointers to them. All this is done in a
         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  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
+        the list of string pointers. The end of the list is marked  by  a  NULL
         pointer. The yield of the function is zero if all went well, or
           PCRE_ERROR_NOMEMORY       (-6)
         if the attempt to get the memory block failed.
-        When any of these functions encounter a substring that is unset,  which
+        When  any of these functions encounter a substring that is unset, which
-        can  happen  when  capturing subpattern number n+1 matches some part of
+        can happen when capturing subpattern number n+1 matches  some  part  of
-        the subject, but subpattern n has not been used at all, they return  an
+        the  subject, but subpattern n has not been used at all, they return an
         empty string. This can be distinguished from a genuine zero-length sub-
-        string by inspecting the appropriate offset in ovector, which is  nega-
+        string  by inspecting the appropriate offset in ovector, which is nega-
         tive for unset substrings.
-        The  two convenience functions pcre_free_substring() and pcre_free_sub-
+        The two convenience functions pcre_free_substring() and  pcre_free_sub-
-        string_list() can be used to free the memory  returned  by  a  previous
+        string_list()  can  be  used  to free the memory returned by a previous
         call  of  pcre_get_substring()  or  pcre_get_substring_list(),  respec-
-        tively. They do nothing more than  call  the  function  pointed  to  by
+        tively.  They  do  nothing  more  than  call the function pointed to by
-        pcre_free,  which  of course could be called directly from a C program.
+        pcre_free, which of course could be called directly from a  C  program.
-        However, PCRE is used in some situations where it is linked via a  spe-
+        However,  PCRE is used in some situations where it is linked via a spe-
-        cial  interface  to  another  programming  language  which  cannot  use
+        cial  interface  to  another  programming  language  that  cannot   use
-        pcre_free directly; it is for these cases that the functions  are  pro-
+        pcre_free  directly;  it is for these cases that the functions are pro-
         vided.
-Line 1886 
 EXTRACTING CAPTURED SUBSTRINGS BY NAME
+Line 1996 
 EXTRACTING CAPTURED SUBSTRINGS BY NAME
              int stringcount, const char *stringname,
              const char **stringptr);
-        To  extract a substring by name, you first have to find associated num-
+        To extract a substring by name, you first have to find associated  num-
         ber.  For example, for this pattern
           (a+)b(?P<xxx>\d+)...
-        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 1917 
 EXTRACTING CAPTURED SUBSTRINGS BY NAME
+Line 2028 
 EXTRACTING CAPTURED SUBSTRINGS BY NAME
         ate.
+ 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  if  there
+        are  none.  The  format  of the table is described above in the section
+        entitled Information about a pattern. Given all  the  relevant  entries
+        for the name, you can extract each of their numbers, and hence the cap-
+        tured data, if any.
  FINDING ALL POSSIBLE MATCHES
-        The  traditional  matching  function  uses a similar algorithm to Perl,
+        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
+        the subject. If you want to find all possible matches, or  the  longest
-        possible match, consider using the alternative matching  function  (see
+        possible  match,  consider using the alternative matching function (see
-        below)  instead.  If you cannot use the alternative function, but still
+        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
+        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-
+        tern.  When your callout function is called, extract and save the  cur-
-        rent matched substring. Then return  1,  which  forces  pcre_exec()  to
+        rent  matched  substring.  Then  return  1, which forces pcre_exec() to
-        backtrack  and  try other alternatives. Ultimately, when it runs out of
+        backtrack and try other alternatives. Ultimately, when it runs  out  of
         matches, pcre_exec() will yield PCRE_ERROR_NOMATCH.
-Line 1942 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
+Line 2082 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
              int options, int *ovector, int ovecsize,
              int *workspace, int wscount);
-        The function pcre_dfa_exec()  is  called  to  match  a  subject  string
+        The  function  pcre_dfa_exec()  is  called  to  match  a subject string
-        against  a compiled pattern, using a "DFA" matching algorithm. This has
+        against a compiled pattern, using a "DFA" matching algorithm. This  has
-        different characteristics to the normal algorithm, and is not  compati-
+        different  characteristics to the normal algorithm, and is not compati-
         ble with Perl. Some of the features of PCRE patterns are not supported.
         Nevertheless, there are times when this kind of matching can be useful.
-        For  a  discussion of the two matching algorithms, see the pcrematching
+        For a discussion of the two matching algorithms, see  the  pcrematching
         documentation.
-        The arguments for the pcre_dfa_exec() function  are  the  same  as  for
+        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
+        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
+        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
+        The  two  additional  arguments provide workspace for the function. The
-        workspace  vector  should  contain at least 20 elements. It is used for
+        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
+        workspace will be needed for patterns and subjects where  there  are  a
-        lot of possible matches.
+        lot of potential matches.
         Here is an example of a simple call to pcre_dfa_exec():
-Line 1981 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
+Line 2121 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
     Option bits for pcre_dfa_exec()
-        The unused bits of the options argument  for  pcre_dfa_exec()  must  be
+        The  unused  bits  of  the options argument for pcre_dfa_exec() must be
-        zero.  The  only  bits  that may be set are PCRE_ANCHORED, PCRE_NOTBOL,
+        zero. The only bits  that  may  be  set  are  PCRE_ANCHORED,  PCRE_NEW-
-        PCRE_NOTEOL,    PCRE_NOTEMPTY,    PCRE_NO_UTF8_CHECK,     PCRE_PARTIAL,
+        LINE_xxx,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK,
-        PCRE_DFA_SHORTEST,  and  PCRE_DFA_RESTART.  All  but  the last three of
+        PCRE_PARTIAL, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last
-        these are the same as for pcre_exec(),  so  their  description  is  not
+        three of these are the same as for pcre_exec(), so their description is
-        repeated here.
+        not repeated here.
           PCRE_PARTIAL
-        This  has  the  same general effect as it does for pcre_exec(), but the
+        This has the same general effect as it does for  pcre_exec(),  but  the
-        details  are  slightly  different.  When  PCRE_PARTIAL   is   set   for
+        details   are   slightly   different.  When  PCRE_PARTIAL  is  set  for
-        pcre_dfa_exec(),  the  return code PCRE_ERROR_NOMATCH is converted into
+        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
+        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
+        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
+        Setting the PCRE_DFA_SHORTEST option causes the matching  algorithm  to
-        stop as soon as it has found one match. Because  of  the  way  the  DFA
+        stop  as  soon  as  it  has found one match. Because of the way the DFA
         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
+        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-
+        returns a partial match, it is possible to call it  again,  with  addi-
-        tional subject characters, and have it continue with  the  same  match.
+        tional  subject  characters,  and have it continue with the same match.
-        The  PCRE_DFA_RESTART  option requests this action; when it is set, the
+        The PCRE_DFA_RESTART option requests this action; when it is  set,  the
-        workspace and wscount options must reference the same vector as  before
+        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
+        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
+        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-
+        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
+        of the function start at the same point in  the  subject.  The  shorter
-        matches are all initial substrings of the longer matches. For  example,
+        matches  are all initial substrings of the longer matches. For example,
         if the pattern
           <.*>
-Line 2036 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
+Line 2176 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
           <something> <something else>
           <something> <something else> <something further>
-        On  success,  the  yield of the function is a number greater than zero,
+        On success, the yield of the function is a number  greater  than  zero,
-        which is the number of matched substrings.  The  substrings  themselves
+        which  is  the  number of matched substrings. The substrings themselves
-        are  returned  in  ovector. Each string uses two elements; the first is
+        are returned in ovector. Each string uses two elements;  the  first  is
-        the offset to the start, and the second is the offset to the  end.  All
+        the  offset  to the start, and the second is the offset to the end. 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
+        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
+        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
+        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
+        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.
+        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
+        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
+        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-
+        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
+        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  in
+        This  return is given if pcre_dfa_exec() encounters a condition item in
-        a  pattern  that  uses  a back reference for the condition. This is not
+        a pattern that uses a back reference for the  condition.  This  is  not
         supported.
           PCRE_ERROR_DFA_UMLIMIT    (-18)
-        This return is given if pcre_dfa_exec() is called with an  extra  block
+        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
+        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
+        When a recursive subpattern is processed, the matching  function  calls
-        itself recursively, using private vectors for  ovector  and  workspace.
+        itself  recursively,  using  private vectors for ovector and workspace.
-        This  error  is  given  if  the output vector is not large enough. This
+        This error is given if the output vector  is  not  large  enough.  This
         should be extremely rare, as a vector of size 1000 is used.
- Last updated: 18 January 2006
+ Last updated: 08 June 2006
  Copyright (c) 1997-2006 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 2334 
 DIFFERENCES BETWEEN PCRE AND PERL
+Line 2474 
 DIFFERENCES BETWEEN PCRE AND PERL
         meta-character matches only at the very end of the string.
         (c) If PCRE_EXTRA is set, a backslash followed by a letter with no spe-
-        cial meaning is faulted.
+        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-
+        (d)  If  PCRE_UNGREEDY is set, the greediness of the repetition quanti-
         fiers is inverted, that is, by default they are not greedy, but if fol-
         lowed by a question mark they are.
         (e) PCRE_ANCHORED can be used at matching time to force a pattern to be
         tried only at the first matching position in the subject string.
-        (f)  The PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and PCRE_NO_AUTO_CAP-
+        (f) The PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, 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 (?R), (?number), and (?P>name) constructs allows for recursive
-        pattern  matching  (Perl  can  do  this using the (?p{code}) construct,
+        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.
+        (h)  PCRE supports named capturing substrings, using the Python syntax.
-        (i)  PCRE  supports  the  possessive quantifier "++" syntax, taken from
+        (i) PCRE supports the possessive quantifier  "++"  syntax,  taken  from
         Sun's Java package.
         (j) The (R) condition, for testing recursion, is a PCRE extension.
-Line 2364 
 DIFFERENCES BETWEEN PCRE AND PERL
+Line 2505 
 DIFFERENCES BETWEEN PCRE AND PERL
         (m) Patterns compiled by PCRE can be saved and re-used at a later time,
         even on different hosts that have the other endianness.
-        (n)  The  alternative  matching function (pcre_dfa_exec()) matches in a
+        (n) The alternative matching function (pcre_dfa_exec())  matches  in  a
         different way and is not Perl-compatible.
- Last updated: 24 January 2006
+ Last updated: 06 June 2006
  Copyright (c) 1997-2006 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 2476 
 BACKSLASH
+Line 2617 
 BACKSLASH
         If  a  pattern is compiled with the PCRE_EXTENDED option, whitespace in
         the pattern (other than in a character class) and characters between  a
-        # outside a character class and the next newline character are ignored.
+        # outside a character class and the next newline are ignored. An escap-
-        An escaping backslash can be used to include a whitespace or #  charac-
+        ing backslash can be used to include a whitespace  or  #  character  as
-        ter as part of the pattern.
+        part of the pattern.
         If  you  want  to remove the special meaning from a sequence of charac-
         ters, you can do so by putting them between \Q and \E. This is  differ-
-Line 2535 
 BACKSLASH
+Line 2676 
 BACKSLASH
         two  syntaxes  for  \x. There is no difference in the way they are han-
         dled. For example, \xdc is exactly the same as \x{dc}.
-        After \0 up to two further octal digits are read.  In  both  cases,  if
+        After \0 up to two further octal digits are read. If  there  are  fewer
-        there  are fewer than two digits, just those that are present are used.
+        than  two  digits,  just  those  that  are  present  are used. Thus the
-        Thus the sequence \0\x\07 specifies two binary zeros followed by a  BEL
+        sequence \0\x\07 specifies two binary zeros followed by a BEL character
-        character  (code  value  7).  Make sure you supply two digits after the
+        (code  value 7). Make sure you supply two digits after the initial zero
-        initial zero if the pattern character that follows is itself  an  octal
+        if the pattern character that follows is itself an octal digit.
-        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, ane 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 2571 
 BACKSLASH
+Line 2713 
 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 sequence \X is interpreted as the character "X". Outside a
-        interpreted as the character "X".  Outside  a  character  class,  these
+        character class, these sequences have different meanings (see below).
-        sequences have different meanings (see below).
     Generic character types
-Line 2604 
 BACKSLASH
+Line 2745 
 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 2719 
 BACKSLASH
+Line 2862 
 BACKSLASH
         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 is  permitted  to  prefix
+        \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-
-Line 2777 
 BACKSLASH
+Line 2920 
 BACKSLASH
         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
-        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  \G assertion is true only when the current matching position is at
+        the  start point of the match, as specified by the startoffset argument
-        the start point of the match, as specified by the startoffset  argument
+        of pcre_exec(). It differs from \A when the  value  of  startoffset  is
-        of  pcre_exec().  It  differs  from \A when the value of startoffset is
+        non-zero.  By calling pcre_exec() multiple times with appropriate argu-
-        non-zero. By calling pcre_exec() multiple times with appropriate  argu-
         ments, you can mimic Perl's /g option, and it is in this kind of imple-
         mentation where \G can be useful.
-        Note, however, that PCRE's interpretation of \G, as the  start  of  the
+        Note,  however,  that  PCRE's interpretation of \G, as the start of the
         current match, is subtly different from Perl's, which defines it as the
-        end of the previous match. In Perl, these can  be  different  when  the
+        end  of  the  previous  match. In Perl, these can be different when the
-        previously  matched  string was empty. Because PCRE does just one match
+        previously matched string was empty. Because PCRE does just  one  match
         at a time, it cannot reproduce this behaviour.
-        If all the alternatives of a pattern begin with \G, the  expression  is
+        If  all  the alternatives of a pattern begin with \G, the expression is
         anchored to the starting match position, and the "anchored" flag is set
         in the compiled regular expression.
-Line 2802 
 BACKSLASH
+Line 2944 
 BACKSLASH
  CIRCUMFLEX AND DOLLAR
         Outside a character class, in the default matching mode, the circumflex
-        character  is  an  assertion  that is true only if the current matching
+        character is an assertion that is true only  if  the  current  matching
-        point is at the start of the subject string. If the  startoffset  argu-
+        point  is  at the start of the subject string. If the startoffset argu-
-        ment  of  pcre_exec()  is  non-zero,  circumflex can never match if the
+        ment of pcre_exec() is non-zero, circumflex  can  never  match  if  the
-        PCRE_MULTILINE option is unset. Inside a  character  class,  circumflex
+        PCRE_MULTILINE  option  is  unset. Inside a character class, circumflex
         has an entirely different meaning (see below).
-        Circumflex  need  not be the first character of the pattern if a number
+        Circumflex need not be the first character of the pattern if  a  number
-        of alternatives are involved, but it should be the first thing in  each
+        of  alternatives are involved, but it should be the first thing in each
-        alternative  in  which  it appears if the pattern is ever to match that
+        alternative in which it appears if the pattern is ever  to  match  that
-        branch. If all possible alternatives start with a circumflex, that  is,
+        branch.  If all possible alternatives start with a circumflex, that is,
-        if  the  pattern  is constrained to match only at the start of the sub-
+        if the pattern is constrained to match only at the start  of  the  sub-
-        ject, it is said to be an "anchored" pattern.  (There  are  also  other
+        ject,  it  is  said  to be an "anchored" pattern. (There are also other
         constructs that can cause a pattern to be anchored.)
-        A  dollar  character  is  an assertion that is true only if the current
+        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
+        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
         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
-        Note  that  the sequences \A, \Z, and \z can be used to match the start
+        all  branches  start  with  ^ are not anchored in multiline mode, and a
-        and end of the subject in both modes, and if all branches of a  pattern
+        match for circumflex is  possible  when  the  startoffset  argument  of
-        start  with  \A it is always anchored, whether PCRE_MULTILINE is set or
+        pcre_exec()  is  non-zero. The PCRE_DOLLAR_ENDONLY option is ignored if
-        not.
+        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 or not  PCRE_MULTILINE  is
+        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. When a line ending  is  defined  as  a  single
-        the PCRE_DOTALL option is set, dots match newlines as  well.  The  han-
+        character  (CR  or LF), dot never matches that character; when the two-
-        dling  of dot is entirely independent of the handling of circumflex and
+        character sequence CRLF is used, dot does not match CR if it is immedi-
-        dollar, the only relationship being  that  they  both  involve  newline
+        ately  followed by LF, but otherwise it matches all characters (includ-
-        characters. Dot has no special meaning in a character class.
+        ing isolated CRs and LFs).
+        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 newline is defined as the two-character sequence CRLF, 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  CR  and
-        The  feature  is provided in Perl in order to match individual bytes in
+        LF.  The feature is provided in Perl in order to match individual bytes
-        UTF-8 mode. Because it  breaks  up  UTF-8  characters  into  individual
+        in UTF-8 mode.  Because it breaks up UTF-8 characters  into  individual
         bytes,  what remains in the string may be a malformed UTF-8 string. For
         this reason, the \C escape sequence is best avoided.
-Line 2912 
 SQUARE BRACKETS AND CHARACTER CLASSES
+Line 3067 
 SQUARE BRACKETS AND CHARACTER CLASSES
         PCRE  is  compiled  with Unicode property support as well as with UTF-8
         support.
-        The newline character is never treated in any special way in  character
+        Characters that might indicate  line  breaks  (CR  and  LF)  are  never
-        classes,  whatever  the  setting  of  the PCRE_DOTALL or PCRE_MULTILINE
+        treated  in  any  special way when matching character classes, whatever
-        options is. A class such as [^a] will always match a newline.
+        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 3015 
 VERTICAL BAR
+Line 3172 
 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 3065 
 INTERNAL OPTION SETTING
+Line 3221 
 INTERNAL OPTION SETTING
         the effects of option settings happen at compile time. There  would  be
         some very weird behaviour otherwise.
-        The  PCRE-specific  options PCRE_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 3082 
 SUBPATTERNS
+Line 3235 
 SUBPATTERNS
           cat(aract|erpillar|)
-        matches  one  of the words "cat", "cataract", or "caterpillar". Without
+        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 the empty
         string.
-.  It  sets  up  the  subpattern as a capturing subpattern. This means
+. It sets up the subpattern as  a  capturing  subpattern.  This  means
-        that, when the whole pattern  matches,  that  portion  of  the  subject
+        that,  when  the  whole  pattern  matches,  that portion of the subject
         string that matched the subpattern is passed back to the caller via the
-        ovector argument of pcre_exec(). Opening parentheses are  counted  from
+        ovector  argument  of pcre_exec(). Opening parentheses are counted from
-        left  to  right  (starting  from 1) to obtain numbers for the capturing
+        left to right (starting from 1) to obtain  numbers  for  the  capturing
         subpatterns.
-        For example, if the string "the red king" is matched against  the  pat-
+        For  example,  if the string "the red king" is matched against the pat-
         tern
           the ((red|white) (king|queen))
-Line 3101 
 SUBPATTERNS
+Line 3254 
 SUBPATTERNS
         the captured substrings are "red king", "red", and "king", and are num-
         bered 1, 2, and 3, respectively.
-        The fact that plain parentheses fulfil  two  functions  is  not  always
+        The  fact  that  plain  parentheses  fulfil two functions is not always
-        helpful.   There are often times when a grouping subpattern is required
+        helpful.  There are often times when a grouping subpattern is  required
-        without a capturing requirement. If an opening parenthesis is  followed
+        without  a capturing requirement. If an opening parenthesis is followed
-        by  a question mark and a colon, the subpattern does not do any captur-
+        by a question mark and a colon, the subpattern does not do any  captur-
-        ing, and is not counted when computing the  number  of  any  subsequent
+        ing,  and  is  not  counted when computing the number of any subsequent
-        capturing  subpatterns. For example, if the string "the white queen" is
+        capturing subpatterns. For example, if the string "the white queen"  is
         matched against the pattern
           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, and  the
-        maximum depth of nesting of all subpatterns, both  capturing  and  non-
+        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
+        As a convenient shorthand, if any option settings are required  at  the
-        start of a non-capturing subpattern,  the  option  letters  may  appear
+        start  of  a  non-capturing  subpattern,  the option letters may appear
         between the "?" and the ":". Thus the two patterns
           (?i:saturday|sunday)
           (?:(?i)saturday|sunday)
         match exactly the same set of strings. Because alternative branches are
-        tried from left to right, and options are not reset until  the  end  of
+        tried  from  left  to right, and options are not reset until the end of
-        the  subpattern is reached, an option setting in one branch does affect
+        the subpattern is reached, an option setting in one branch does  affect
-        subsequent branches, so the above patterns match "SUNDAY"  as  well  as
+        subsequent  branches,  so  the above patterns match "SUNDAY" as well as
         "Saturday".
  NAMED SUBPATTERNS
-        Identifying  capturing  parentheses  by number is simple, but it can be
+        Identifying capturing parentheses by number is simple, but  it  can  be
-        very hard to keep track of the numbers in complicated  regular  expres-
+        very  hard  to keep track of the numbers in complicated regular expres-
-        sions.  Furthermore,  if  an  expression  is  modified, the numbers may
+        sions. Furthermore, if an  expression  is  modified,  the  numbers  may
-        change. To help with this difficulty, PCRE supports the naming of  sub-
+        change.  To help with this difficulty, PCRE supports the naming of sub-
-        patterns,  something  that  Perl  does  not  provide. The Python syntax
+        patterns, something that Perl  does  not  provide.  The  Python  syntax
-        (?P<name>...) is used. Names consist  of  alphanumeric  characters  and
+        (?P<name>...)  is  used. References to capturing parentheses from other
-        underscores, and must be unique within a pattern.
+        parts of the pattern, such as  backreferences,  recursion,  and  condi-
+        tions, can be made by name as well as by number.
-        Named  capturing  parentheses  are  still  allocated numbers as well as
+        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-
-        number  translation table from a compiled pattern. There is also a con-
+        number translation table from a compiled pattern. There is also a  con-
-        venience function for extracting a captured substring by name. For fur-
+        venience function for extracting a captured substring by name.
-        ther details see the pcreapi documentation.
+        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:
+          (?P<DN>Mon|Fri|Sun)(?:day)?|
+          (?P<DN>Tue)(?:sday)?|
+          (?P<DN>Wed)(?:nesday)?|
+          (?P<DN>Thu)(?:rsday)?|
+          (?P<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 3353 
 ATOMIC GROUPING AND POSSESSIVE QUANTIFIE
+Line 3531 
 ATOMIC GROUPING AND POSSESSIVE QUANTIFIE
         meaning  or  processing  of  a possessive quantifier and the equivalent
         atomic group.
-        The possessive quantifier syntax is an extension to the Perl syntax. It
+        The possessive quantifier syntax is an extension to  the  Perl  syntax.
-        originates in Sun's Java package.
+        Jeffrey  Friedl originated the idea (and the name) in the first edition
+        of his book.  Mike McCloskey liked it, so implemented it when he  built
+        Sun's Java package, and PCRE copied it from there.
         When  a  pattern  contains an unlimited repeat inside a subpattern that
         can itself be repeated an unlimited number of  times,  the  use  of  an
-Line 3395 
 BACK REFERENCES
+Line 3575 
 BACK REFERENCES
         it  is  always  taken  as a back reference, and causes an error only if
         there are not that many capturing left parentheses in the  entire  pat-
         tern.  In  other words, the parentheses that are referenced need not be
-        to the left of the reference for numbers less than 10. See the  subsec-
+        to the left of the reference for numbers less than 10. A "forward  back
-        tion  entitled  "Non-printing  characters" above for further details of
+        reference"  of  this  type can make sense when a repetition is involved
-        the handling of digits following a backslash.
+        and the subpattern to the right has participated in an  earlier  itera-
+        tion.
+        It is not possible to have a numerical "forward back reference" to sub-
+        pattern whose number is 10 or more. However, a back  reference  to  any
+        subpattern  is  possible  using named parentheses (see below). See also
+        the subsection entitled "Non-printing  characters"  above  for  further
+        details of the handling of digits following a backslash.
-        A back reference matches whatever actually matched the  capturing  sub-
+        A  back  reference matches whatever actually matched the capturing sub-
-        pattern  in  the  current subject string, rather than anything matching
+        pattern in the current subject string, rather  than  anything  matching
         the subpattern itself (see "Subpatterns as subroutines" below for a way
         of doing that). So the pattern
           (sens|respons)e and \1ibility
-        matches  "sense and sensibility" and "response and responsibility", but
+        matches "sense and sensibility" and "response and responsibility",  but
-        not "sense and responsibility". If caseful matching is in force at  the
+        not  "sense and responsibility". If caseful matching is in force at the
-        time  of the back reference, the case of letters is relevant. For exam-
+        time of the back reference, the case of letters is relevant. For  exam-
         ple,
           ((?i)rah)\s+\1
-        matches "rah rah" and "RAH RAH", but not "RAH  rah",  even  though  the
+        matches  "rah  rah"  and  "RAH RAH", but not "RAH rah", even though the
         original capturing subpattern is matched caselessly.
-        Back  references  to named subpatterns use the Python syntax (?P=name).
+        Back references to named subpatterns use the Python  syntax  (?P=name).
         We could rewrite the above example as follows:
-          (?<p1>(?i)rah)\s+(?P=p1)
+          (?P<p1>(?i)rah)\s+(?P=p1)
+        A  subpattern  that  is  referenced  by  name may appear in the pattern
+        before or after the reference.
         There may be more than one back reference to the same subpattern. If  a
         subpattern  has  not actually been used in a particular match, any back
-Line 3508 
 ASSERTIONS
+Line 3698 
 ASSERTIONS
         does  find  an  occurrence  of "bar" that is not preceded by "foo". The
         contents of a lookbehind assertion are restricted  such  that  all  the
         strings it matches must have a fixed length. However, if there are sev-
-        eral alternatives, they do not all have to have the same fixed  length.
+        eral top-level alternatives, they do not all  have  to  have  the  same
-        Thus
+        fixed length. Thus
           (?<=bullock|donkey)
-Line 3622 
 CONDITIONAL SUBPATTERNS
+Line 3812 
 CONDITIONAL SUBPATTERNS
         tives in the subpattern, a compile-time error occurs.
         There are three kinds of condition. If the text between the parentheses
-        consists of a sequence of digits, the condition  is  satisfied  if  the
+        consists of a sequence of digits, or a sequence of alphanumeric charac-
-        capturing  subpattern of that number has previously matched. The number
+        ters  and underscores, the condition is satisfied if the capturing sub-
-        must be greater than zero. Consider the following pattern,  which  con-
+        pattern of that number or name has previously matched. There is a  pos-
-        tains  non-significant white space to make it more readable (assume the
+        sible  ambiguity here, because subpattern names may consist entirely of
-        PCRE_EXTENDED option) and to divide it into three  parts  for  ease  of
+        digits. PCRE looks first for a named subpattern; if it cannot find  one
-        discussion:
+        and  the text consists entirely of digits, it looks for a subpattern of
+        that number, which must be greater than zero.  Using  subpattern  names
+        that consist entirely of digits is not recommended.
+        Consider  the  following  pattern, which contains non-significant white
+        space to make it more readable (assume the PCRE_EXTENDED option) and to
+        divide it into three parts for ease of discussion:
           ( \( )?    [^()]+    (?(1) \) )
-Line 3640 
 CONDITIONAL SUBPATTERNS
+Line 3836 
 CONDITIONAL SUBPATTERNS
         tern  is  executed  and  a  closing parenthesis is required. Otherwise,
         since no-pattern is not present, the  subpattern  matches  nothing.  In
         other  words,  this  pattern  matches  a  sequence  of non-parentheses,
-        optionally enclosed in parentheses.
+        optionally enclosed in parentheses. Rewriting it to use a named subpat-
+        tern gives this:
+          (?P<OPEN> \( )?    [^()]+    (?(OPEN) \) )
-        If the condition is the string (R), it is satisfied if a recursive call
+        If the condition is the string (R), and there is no subpattern with the
-        to  the pattern or subpattern has been made. At "top level", the condi-
+        name R, the condition is satisfied if a recursive call to  the  pattern
-        tion is false.  This  is  a  PCRE  extension.  Recursive  patterns  are
+        or  subpattern  has  been made. At "top level", the condition is false.
-        described in the next section.
+        This is a PCRE extension.  Recursive patterns are described in the next
+        section.
         If  the  condition  is  not  a sequence of digits or (R), it must be an
         assertion.  This may be a positive or negative lookahead or  lookbehind
-Line 3672 
 COMMENTS
+Line 3872 
 COMMENTS
         at all.
         If  the PCRE_EXTENDED option is set, an unescaped # character outside a
-        character class introduces a comment that continues up to the next new-
+        character class introduces a  comment  that  continues  to  immediately
-        line character in the pattern.
+        after the next newline in the pattern.
  RECURSIVE PATTERNS
-Line 3796 
 SUBPATTERNS AS SUBROUTINES
+Line 3996 
 SUBPATTERNS AS SUBROUTINES
           (sens|respons)e and (?1)ibility
         is  used, it does match "sense and responsibility" as well as the other
-        two strings. Such references must, however, follow  the  subpattern  to
+        two strings. Such references, if given  numerically,  must  follow  the
-        which they refer.
+        subpattern  to which they refer. However, named references can refer to
+        later subpatterns.
         Like recursive subpatterns, a "subroutine" call is always treated as an
-        atomic group. That is, once it has matched some of the subject  string,
+        atomic  group. That is, once it has matched some of the subject string,
-        it  is  never  re-entered, even if it contains untried alternatives and
+        it is never re-entered, even if it contains  untried  alternatives  and
         there is a subsequent matching failure.
  CALLOUTS
         Perl has a feature whereby using the sequence (?{...}) causes arbitrary
-        Perl  code to be obeyed in the middle of matching a regular expression.
+        Perl code to be obeyed in the middle of matching a regular  expression.
         This makes it possible, amongst other things, to extract different sub-
         strings that match the same pair of parentheses when there is a repeti-
         tion.
         PCRE provides a similar feature, but of course it cannot obey arbitrary
         Perl code. The feature is called "callout". The caller of PCRE provides
-        an external function by putting its entry point in the global  variable
+        an  external function by putting its entry point in the global variable
-        pcre_callout.   By default, this variable contains NULL, which disables
+        pcre_callout.  By default, this variable contains NULL, which  disables
         all calling out.
-        Within a regular expression, (?C) indicates the  points  at  which  the
+        Within  a  regular  expression,  (?C) indicates the points at which the
-        external  function  is  to be called. If you want to identify different
+        external function is to be called. If you want  to  identify  different
-        callout points, you can put a number less than 256 after the letter  C.
+        callout  points, you can put a number less than 256 after the letter C.
-        The  default  value is zero.  For example, this pattern has two callout
+        The default value is zero.  For example, this pattern has  two  callout
         points:
           (?C1)abc(?C2)def
         If the PCRE_AUTO_CALLOUT flag is passed to pcre_compile(), callouts are
-        automatically  installed  before each item in the pattern. They are all
+        automatically installed before each item in the pattern. They  are  all
         numbered 255.
         During matching, when PCRE reaches a callout point (and pcre_callout is
-        set),  the  external function is called. It is provided with the number
+        set), the external function is called. It is provided with  the  number
-        of the callout, the position in the pattern, and, optionally, one  item
+        of  the callout, the position in the pattern, and, optionally, one item
-        of  data  originally supplied by the caller of pcre_exec(). The callout
+        of data originally supplied by the caller of pcre_exec().  The  callout
-        function may cause matching to proceed, to backtrack, or to fail  alto-
+        function  may cause matching to proceed, to backtrack, or to fail alto-
         gether. A complete description of the interface to the callout function
         is given in the pcrecallout documentation.
- Last updated: 24 January 2006
+ Last updated: 06 June 2006
  Copyright (c) 1997-2006 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 4847 
 PCRE SAMPLE PROGRAM
+Line 5048 
 PCRE SAMPLE PROGRAM
  Last updated: 09 September 2004
  Copyright (c) 1997-2004 University of Cambridge.
  ------------------------------------------------------------------------------
+ PCRESTACK(3)                                                      PCRESTACK(3)
+ NAME
+        PCRE - Perl-compatible regular expressions
+ PCRE DISCUSSION OF STACK USAGE
+        When  you call pcre_exec(), it makes use of an internal function called
+        match(). This calls itself recursively at branch points in the pattern,
+        in  order to remember the state of the match so that it can back up and
+        try a different alternative if the first one fails.  As  matching  pro-
+        ceeds  deeper  and deeper into the tree of possibilities, the recursion
+        depth increases.
+        Not all calls of match() increase the recursion depth; for an item such
+        as  a* it may be called several times at the same level, after matching
+        different numbers of a's. Furthermore, in a number of cases  where  the
+        result  of  the  recursive call would immediately be passed back as the
+        result of the current call (a "tail recursion"), the function  is  just
+        restarted instead.
+        The pcre_dfa_exec() function operates in an entirely different way, and
+        hardly uses recursion at all. The limit on its complexity is the amount
+        of  workspace  it  is  given.  The comments that follow do NOT apply to
+        pcre_dfa_exec(); they are relevant only for pcre_exec().
+        You can set limits on the number of times that match() is called,  both
+        in  total  and  recursively. If the limit is exceeded, an error occurs.
+        For details, see the section on  extra  data  for  pcre_exec()  in  the
+        pcreapi documentation.
+        Each  time  that match() is actually called recursively, it uses memory
+        from the process stack. For certain kinds of  pattern  and  data,  very
+        large  amounts of stack may be needed, despite the recognition of "tail
+        recursion".  You can often reduce the amount of recursion,  and  there-
+        fore  the  amount of stack used, by modifying the pattern that is being
+        matched. Consider, for example, this pattern:
+          ([^<]|<(?!inet))+
+        It matches from wherever it starts until it encounters "<inet"  or  the
+        end  of  the  data,  and is the kind of pattern that might be used when
+        processing an XML file. Each iteration of the outer parentheses matches
+        either  one  character that is not "<" or a "<" that is not followed by
+        "inet". However, each time a  parenthesis  is  processed,  a  recursion
+        occurs, so this formulation uses a stack frame for each matched charac-
+        ter. For a long string, a lot of stack is required. Consider  now  this
+        rewritten pattern, which matches exactly the same strings:
+          ([^<]++|<(?!inet))
+        This  uses very much less stack, because runs of characters that do not
+        contain "<" are "swallowed" in one item inside the parentheses.  Recur-
+        sion  happens  only when a "<" character that is not followed by "inet"
+        is encountered (and we assume this is relatively  rare).  A  possessive
+        quantifier  is  used  to stop any backtracking into the runs of non-"<"
+        characters, but that is not related to stack usage.
+        In environments where stack memory is constrained, you  might  want  to
+        compile  PCRE to use heap memory instead of stack for remembering back-
+        up points. This makes it run a lot more slowly, however. Details of how
+        to do this are given in the pcrebuild documentation.
+        In Unix-like environments, there is not often a problem with the stack,
+        though the default limit on stack size varies from  system  to  system.
+        Values  from 8Mb to 64Mb are common. You can find your default limit by
+        running the command:
+          ulimit -s
+        The effect of running out of stack is often SIGSEGV,  though  sometimes
+        an error message is given. You can normally increase the limit on stack
+        size by code such as this:
+          struct rlimit rlim;
+          getrlimit(RLIMIT_STACK, &rlim);
+          rlim.rlim_cur = 100*1024*1024;
+          setrlimit(RLIMIT_STACK, &rlim);
+        This reads the current limits (soft and hard) using  getrlimit(),  then
+        attempts  to  increase  the  soft limit to 100Mb using setrlimit(). You
+        must do this before calling pcre_exec().
+        PCRE has an internal counter that can be used to  limit  the  depth  of
+        recursion,  and  thus cause pcre_exec() to give an error code before it
+        runs out of stack. By default, the limit is very  large,  and  unlikely
+        ever  to operate. It can be changed when PCRE is built, and it can also
+        be set when pcre_exec() is called. For details of these interfaces, see
+        the pcrebuild and pcreapi documentation.
+        As a very rough rule of thumb, you should reckon on about 500 bytes per
+        recursion. Thus, if you want to limit your  stack  usage  to  8Mb,  you
+        should  set  the  limit at 16000 recursions. A 64Mb stack, on the other
+        hand, can support around 128000 recursions. The pcretest  test  program
+        has  a command line option (-S) that can be used to increase its stack.
+ Last updated: 29 June 2006
+ Copyright (c) 1997-2006 University of Cambridge.
+ ------------------------------------------------------------------------------

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