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# Line 32  INTRODUCTION Line 32  INTRODUCTION
32         either  one  or both to be built. The majority of the work to make this         either  one  or both to be built. The majority of the work to make this
33         possible was done by Zoltan Herczeg.         possible was done by Zoltan Herczeg.
34    
35         The two libraries contain identical sets of functions, except that  the         Starting with release 8.32 it is possible to compile a  third  separate
36         names  in  the  16-bit  library start with pcre16_ instead of pcre_. To         PCRE library, which supports 32-bit character strings (including UTF-32
37         avoid over-complication and reduce the documentation maintenance  load,         strings). The build process allows any set of the 8-,  16-  and  32-bit
38         most of the documentation describes the 8-bit library, with the differ-         libraries. The work to make this possible was done by Christian Persch.
39         ences for the 16-bit library described separately in the  pcre16  page.  
40         References  to  functions or structures of the form pcre[16]_xxx should         The  three  libraries  contain identical sets of functions, except that
41         be  read  as  meaning  "pcre_xxx  when  using  the  8-bit  library  and         the names in the 16-bit library start with pcre16_  instead  of  pcre_,
42         pcre16_xxx when using the 16-bit library".         and  the  names  in  the  32-bit  library start with pcre32_ instead of
43           pcre_. To avoid over-complication and reduce the documentation  mainte-
44         The  current implementation of PCRE corresponds approximately with Perl         nance load, most of the documentation describes the 8-bit library, with
45         5.12, including support for UTF-8/16 encoded strings and  Unicode  gen-         the differences for the 16-bit and  32-bit  libraries  described  sepa-
46         eral  category properties. However, UTF-8/16 and Unicode support has to         rately  in  the  pcre16  and  pcre32  pages. References to functions or
47         be explicitly enabled; it is not the default. The Unicode tables corre-         structures of the  form  pcre[16|32]_xxx  should  be  read  as  meaning
48         spond to Unicode release 6.0.0.         "pcre_xxx  when  using  the  8-bit  library,  pcre16_xxx when using the
49           16-bit library, or pcre32_xxx when using the 32-bit library".
50    
51           The current implementation of PCRE corresponds approximately with  Perl
52           5.12,  including  support  for  UTF-8/16/32 encoded strings and Unicode
53           general category properties. However, UTF-8/16/32 and  Unicode  support
54           has to be explicitly enabled; it is not the default. The Unicode tables
55           correspond to Unicode release 6.2.0.
56    
57         In  addition to the Perl-compatible matching function, PCRE contains an         In addition to the Perl-compatible matching function, PCRE contains  an
58         alternative function that matches the same compiled patterns in a  dif-         alternative  function that matches the same compiled patterns in a dif-
59         ferent way. In certain circumstances, the alternative function has some         ferent way. In certain circumstances, the alternative function has some
60         advantages.  For a discussion of the two matching algorithms,  see  the         advantages.   For  a discussion of the two matching algorithms, see the
61         pcrematching page.         pcrematching page.
62    
63         PCRE  is  written  in C and released as a C library. A number of people         PCRE is written in C and released as a C library. A  number  of  people
64         have written wrappers and interfaces of various kinds.  In  particular,         have  written  wrappers and interfaces of various kinds. In particular,
65         Google  Inc.   have  provided a comprehensive C++ wrapper for the 8-bit         Google Inc.  have provided a comprehensive C++ wrapper  for  the  8-bit
66         library. This is now included as part of  the  PCRE  distribution.  The         library.  This  is  now  included as part of the PCRE distribution. The
67         pcrecpp  page  has  details of this interface. Other people's contribu-         pcrecpp page has details of this interface.  Other  people's  contribu-
68         tions can be found in the Contrib directory at the  primary  FTP  site,         tions  can  be  found in the Contrib directory at the primary FTP site,
69         which is:         which is:
70    
71         ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre         ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre
72    
73         Details  of  exactly which Perl regular expression features are and are         Details of exactly which Perl regular expression features are  and  are
74         not supported by PCRE are given in separate documents. See the pcrepat-         not supported by PCRE are given in separate documents. See the pcrepat-
75         tern  and pcrecompat pages. There is a syntax summary in the pcresyntax         tern and pcrecompat pages. There is a syntax summary in the  pcresyntax
76         page.         page.
77    
78         Some features of PCRE can be included, excluded, or  changed  when  the         Some  features  of  PCRE can be included, excluded, or changed when the
79         library  is  built.  The pcre_config() function makes it possible for a         library is built. The pcre_config() function makes it  possible  for  a
80         client to discover which features are  available.  The  features  them-         client  to  discover  which  features are available. The features them-
81         selves  are described in the pcrebuild page. Documentation about build-         selves are described in the pcrebuild page. Documentation about  build-
82         ing PCRE for various operating systems can be found in the  README  and         ing  PCRE  for various operating systems can be found in the README and
83         NON-UNIX-USE files in the source distribution.         NON-AUTOTOOLS_BUILD files in the source distribution.
84    
85         The  libraries contains a number of undocumented internal functions and         The libraries contains a number of undocumented internal functions  and
86         data tables that are used by more than one  of  the  exported  external         data  tables  that  are  used by more than one of the exported external
87         functions,  but  which  are  not  intended for use by external callers.         functions, but which are not intended  for  use  by  external  callers.
88         Their names all begin with "_pcre_" or "_pcre16_", which hopefully will         Their  names all begin with "_pcre_" or "_pcre16_" or "_pcre32_", which
89         not  provoke  any name clashes. In some environments, it is possible to         hopefully will not provoke any name clashes. In some  environments,  it
90         control which external symbols are exported when a  shared  library  is         is  possible  to  control  which  external  symbols are exported when a
91         built, and in these cases the undocumented symbols are not exported.         shared library is built, and in these cases  the  undocumented  symbols
92           are not exported.
93    
94    
95    SECURITY CONSIDERATIONS
96    
97           If  you  are  using PCRE in a non-UTF application that permits users to
98           supply arbitrary patterns for compilation, you should  be  aware  of  a
99           feature that allows users to turn on UTF support from within a pattern,
100           provided that PCRE was built with UTF support. For  example,  an  8-bit
101           pattern  that  begins  with  "(*UTF8)" turns on UTF-8 mode. This causes
102           both the pattern and any data against which it is matched to be checked
103           for UTF-8 validity. If the data string is very long, such a check might
104           use sufficiently many resources as to cause your  application  to  lose
105           performance.
106    
107           The  best  way  of  guarding  against  this  possibility  is to use the
108           pcre_fullinfo() function to check the compiled  pattern's  options  for
109           UTF.
110    
111           If  your  application  is one that supports UTF, be aware that validity
112           checking can take time. If the same data string is to be  matched  many
113           times, you can use the PCRE_NO_UTF[8|16|32]_CHECK option for the second
114           and subsequent matches to save redundant checks.
115    
116           Another way that performance can be hit is by running  a  pattern  that
117           has  a  very  large search tree against a string that will never match.
118           Nested unlimited repeats in a pattern are a common example.  PCRE  pro-
119           vides some protection against this: see the PCRE_EXTRA_MATCH_LIMIT fea-
120           ture in the pcreapi page.
121    
122    
123  USER DOCUMENTATION  USER DOCUMENTATION
124    
125         The  user  documentation  for PCRE comprises a number of different sec-         The user documentation for PCRE comprises a number  of  different  sec-
126         tions. In the "man" format, each of these is a separate "man page".  In         tions.  In the "man" format, each of these is a separate "man page". In
127         the  HTML  format, each is a separate page, linked from the index page.         the HTML format, each is a separate page, linked from the  index  page.
128         In the plain text format, all the sections, except  the  pcredemo  sec-         In  the  plain  text format, all the sections, except the pcredemo sec-
129         tion, are concatenated, for ease of searching. The sections are as fol-         tion, are concatenated, for ease of searching. The sections are as fol-
130         lows:         lows:
131    
132           pcre              this document           pcre              this document
133           pcre16            details of the 16-bit library           pcre16            details of the 16-bit library
134             pcre32            details of the 32-bit library
135           pcre-config       show PCRE installation configuration information           pcre-config       show PCRE installation configuration information
136           pcreapi           details of PCRE's native C API           pcreapi           details of PCRE's native C API
137           pcrebuild         options for building PCRE           pcrebuild         options for building PCRE
# Line 116  USER DOCUMENTATION Line 153  USER DOCUMENTATION
153           pcrestack         discussion of stack usage           pcrestack         discussion of stack usage
154           pcresyntax        quick syntax reference           pcresyntax        quick syntax reference
155           pcretest          description of the pcretest testing command           pcretest          description of the pcretest testing command
156           pcreunicode       discussion of Unicode and UTF-8/16 support           pcreunicode       discussion of Unicode and UTF-8/16/32 support
157    
158         In addition, in the "man" and HTML formats, there is a short  page  for         In  addition,  in the "man" and HTML formats, there is a short page for
159         each 8-bit C library function, listing its arguments and results.         each C library function, listing its arguments and results.
160    
161    
162  AUTHOR  AUTHOR
# Line 128  AUTHOR Line 165  AUTHOR
165         University Computing Service         University Computing Service
166         Cambridge CB2 3QH, England.         Cambridge CB2 3QH, England.
167    
168         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,
169         so I've taken it away. If you want to email me, use  my  two  initials,         so  I've  taken  it away. If you want to email me, use my two initials,
170         followed by the two digits 10, at the domain cam.ac.uk.         followed by the two digits 10, at the domain cam.ac.uk.
171    
172    
173  REVISION  REVISION
174    
175         Last updated: 10 January 2012         Last updated: 30 October 2012
176         Copyright (c) 1997-2012 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
177  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
178    
179    
180  PCRE(3)                                                                PCRE(3)  PCRE(3)                                                                PCRE(3)
181    
182    
# Line 372  OPTION NAMES Line 409  OPTION NAMES
409    
410         For the pcre16_config() function there is an  option  PCRE_CONFIG_UTF16         For the pcre16_config() function there is an  option  PCRE_CONFIG_UTF16
411         that  returns  1  if UTF-16 support is configured, otherwise 0. If this         that  returns  1  if UTF-16 support is configured, otherwise 0. If this
412         option is given to pcre_config(), or if the PCRE_CONFIG_UTF8 option  is         option  is  given  to  pcre_config()  or  pcre32_config(),  or  if  the
413         given to pcre16_config(), the result is the PCRE_ERROR_BADOPTION error.         PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF32  option is given to pcre16_con-
414           fig(), the result is the PCRE_ERROR_BADOPTION error.
415    
416    
417  CHARACTER CODES  CHARACTER CODES
418    
419         In  16-bit  mode,  when  PCRE_UTF16  is  not  set, character values are         In 16-bit mode, when  PCRE_UTF16  is  not  set,  character  values  are
420         treated in the same way as in 8-bit, non UTF-8 mode, except, of course,         treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
421         that  they  can  range from 0 to 0xffff instead of 0 to 0xff. Character         that they can range from 0 to 0xffff instead of 0  to  0xff.  Character
422         types for characters less than 0xff can therefore be influenced by  the         types  for characters less than 0xff can therefore be influenced by the
423         locale  in  the  same way as before.  Characters greater than 0xff have         locale in the same way as before.  Characters greater  than  0xff  have
424         only one case, and no "type" (such as letter or digit).         only one case, and no "type" (such as letter or digit).
425    
426         In UTF-16 mode, the character code  is  Unicode,  in  the  range  0  to         In  UTF-16  mode,  the  character  code  is  Unicode, in the range 0 to
427         0x10ffff,  with  the  exception of values in the range 0xd800 to 0xdfff         0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
428         because those are "surrogate" values that are used in pairs  to  encode         because  those  are "surrogate" values that are used in pairs to encode
429         values greater than 0xffff.         values greater than 0xffff.
430    
431         A  UTF-16 string can indicate its endianness by special code knows as a         A UTF-16 string can indicate its endianness by special code knows as  a
432         byte-order mark (BOM). The PCRE functions do not handle this, expecting         byte-order mark (BOM). The PCRE functions do not handle this, expecting
433         strings   to   be  in  host  byte  order.  A  utility  function  called         strings  to  be  in  host  byte  order.  A  utility   function   called
434         pcre16_utf16_to_host_byte_order() is provided to help  with  this  (see         pcre16_utf16_to_host_byte_order()  is  provided  to help with this (see
435         above).         above).
436    
437    
438  ERROR NAMES  ERROR NAMES
439    
440         The  errors PCRE_ERROR_BADUTF16_OFFSET and PCRE_ERROR_SHORTUTF16 corre-         The errors PCRE_ERROR_BADUTF16_OFFSET and PCRE_ERROR_SHORTUTF16  corre-
441         spond to their 8-bit  counterparts.  The  error  PCRE_ERROR_BADMODE  is         spond  to  their  8-bit  counterparts.  The error PCRE_ERROR_BADMODE is
442         given  when  a  compiled pattern is passed to a function that processes         given when a compiled pattern is passed to a  function  that  processes
443         patterns in the other mode, for example, if  a  pattern  compiled  with         patterns  in  the  other  mode, for example, if a pattern compiled with
444         pcre_compile() is passed to pcre16_exec().         pcre_compile() is passed to pcre16_exec().
445    
446         There  are  new  error  codes whose names begin with PCRE_UTF16_ERR for         There are new error codes whose names  begin  with  PCRE_UTF16_ERR  for
447         invalid UTF-16 strings, corresponding to the  PCRE_UTF8_ERR  codes  for         invalid  UTF-16  strings,  corresponding to the PCRE_UTF8_ERR codes for
448         UTF-8  strings that are described in the section entitled "Reason codes         UTF-8 strings that are described in the section entitled "Reason  codes
449         for invalid UTF-8 strings" in the main pcreapi page. The UTF-16  errors         for  invalid UTF-8 strings" in the main pcreapi page. The UTF-16 errors
450         are:         are:
451    
452           PCRE_UTF16_ERR1  Missing low surrogate at end of string           PCRE_UTF16_ERR1  Missing low surrogate at end of string
453           PCRE_UTF16_ERR2  Invalid low surrogate follows high surrogate           PCRE_UTF16_ERR2  Invalid low surrogate follows high surrogate
454           PCRE_UTF16_ERR3  Isolated low surrogate           PCRE_UTF16_ERR3  Isolated low surrogate
455           PCRE_UTF16_ERR4  Invalid character 0xfffe           PCRE_UTF16_ERR4  Non-character
456    
457    
458  ERROR TEXTS  ERROR TEXTS
459    
460         If  there is an error while compiling a pattern, the error text that is         If there is an error while compiling a pattern, the error text that  is
461         passed back by pcre16_compile() or pcre16_compile2() is still an  8-bit         passed  back by pcre16_compile() or pcre16_compile2() is still an 8-bit
462         character string, zero-terminated.         character string, zero-terminated.
463    
464    
465  CALLOUTS  CALLOUTS
466    
467         The  subject  and  mark fields in the callout block that is passed to a         The subject and mark fields in the callout block that is  passed  to  a
468         callout function point to 16-bit vectors.         callout function point to 16-bit vectors.
469    
470    
471  TESTING  TESTING
472    
473         The pcretest program continues to operate with 8-bit input  and  output         The  pcretest  program continues to operate with 8-bit input and output
474         files,  but it can be used for testing the 16-bit library. If it is run         files, but it can be used for testing the 16-bit library. If it is  run
475         with the command line option -16, patterns and subject strings are con-         with the command line option -16, patterns and subject strings are con-
476         verted from 8-bit to 16-bit before being passed to PCRE, and the 16-bit         verted from 8-bit to 16-bit before being passed to PCRE, and the 16-bit
477         library functions are used instead of the 8-bit ones.  Returned  16-bit         library  functions  are used instead of the 8-bit ones. Returned 16-bit
478         strings are converted to 8-bit for output. If the 8-bit library was not         strings are converted to 8-bit for output. If both the  8-bit  and  the
479         compiled, pcretest defaults to 16-bit and the -16 option is ignored.         32-bit libraries were not compiled, pcretest defaults to 16-bit and the
480           -16 option is ignored.
481    
482         When PCRE is being built, the RunTest script that is  called  by  "make         When PCRE is being built, the RunTest script that is  called  by  "make
483         check"  uses  the pcretest -C option to discover which of the 8-bit and         check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
484         16-bit libraries has been built, and runs the tests appropriately.         16-bit and 32-bit libraries has been built, and runs the  tests  appro-
485           priately.
486    
487    
488  NOT SUPPORTED IN 16-BIT MODE  NOT SUPPORTED IN 16-BIT MODE
489    
490         Not all the features of the 8-bit library are available with the 16-bit         Not all the features of the 8-bit library are available with the 16-bit
491         library.  The  C++  and  POSIX wrapper functions support only the 8-bit         library. The C++ and POSIX wrapper functions  support  only  the  8-bit
492         library, and the pcregrep program is at present 8-bit only.         library, and the pcregrep program is at present 8-bit only.
493    
494    
# Line 464  REVISION Line 504  REVISION
504         Last updated: 14 April 2012         Last updated: 14 April 2012
505         Copyright (c) 1997-2012 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
506  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
507    
508    
509    PCRE(3)                                                                PCRE(3)
510    
511    
512    NAME
513           PCRE - Perl-compatible regular expressions
514    
515           #include <pcre.h>
516    
517    
518    PCRE 32-BIT API BASIC FUNCTIONS
519    
520           pcre32 *pcre32_compile(PCRE_SPTR32 pattern, int options,
521                const char **errptr, int *erroffset,
522                const unsigned char *tableptr);
523    
524           pcre32 *pcre32_compile2(PCRE_SPTR32 pattern, int options,
525                int *errorcodeptr,
526                const char **errptr, int *erroffset,
527                const unsigned char *tableptr);
528    
529           pcre32_extra *pcre32_study(const pcre32 *code, int options,
530                const char **errptr);
531    
532           void pcre32_free_study(pcre32_extra *extra);
533    
534           int pcre32_exec(const pcre32 *code, const pcre32_extra *extra,
535                PCRE_SPTR32 subject, int length, int startoffset,
536                int options, int *ovector, int ovecsize);
537    
538           int pcre32_dfa_exec(const pcre32 *code, const pcre32_extra *extra,
539                PCRE_SPTR32 subject, int length, int startoffset,
540                int options, int *ovector, int ovecsize,
541                int *workspace, int wscount);
542    
543    
544    PCRE 32-BIT API STRING EXTRACTION FUNCTIONS
545    
546           int pcre32_copy_named_substring(const pcre32 *code,
547                PCRE_SPTR32 subject, int *ovector,
548                int stringcount, PCRE_SPTR32 stringname,
549                PCRE_UCHAR32 *buffer, int buffersize);
550    
551           int pcre32_copy_substring(PCRE_SPTR32 subject, int *ovector,
552                int stringcount, int stringnumber, PCRE_UCHAR32 *buffer,
553                int buffersize);
554    
555           int pcre32_get_named_substring(const pcre32 *code,
556                PCRE_SPTR32 subject, int *ovector,
557                int stringcount, PCRE_SPTR32 stringname,
558                PCRE_SPTR32 *stringptr);
559    
560           int pcre32_get_stringnumber(const pcre32 *code,
561                PCRE_SPTR32 name);
562    
563           int pcre32_get_stringtable_entries(const pcre32 *code,
564                PCRE_SPTR32 name, PCRE_UCHAR32 **first, PCRE_UCHAR32 **last);
565    
566           int pcre32_get_substring(PCRE_SPTR32 subject, int *ovector,
567                int stringcount, int stringnumber,
568                PCRE_SPTR32 *stringptr);
569    
570           int pcre32_get_substring_list(PCRE_SPTR32 subject,
571                int *ovector, int stringcount, PCRE_SPTR32 **listptr);
572    
573           void pcre32_free_substring(PCRE_SPTR32 stringptr);
574    
575           void pcre32_free_substring_list(PCRE_SPTR32 *stringptr);
576    
577    
578    PCRE 32-BIT API AUXILIARY FUNCTIONS
579    
580           pcre32_jit_stack *pcre32_jit_stack_alloc(int startsize, int maxsize);
581    
582           void pcre32_jit_stack_free(pcre32_jit_stack *stack);
583    
584           void pcre32_assign_jit_stack(pcre32_extra *extra,
585                pcre32_jit_callback callback, void *data);
586    
587           const unsigned char *pcre32_maketables(void);
588    
589           int pcre32_fullinfo(const pcre32 *code, const pcre32_extra *extra,
590                int what, void *where);
591    
592           int pcre32_refcount(pcre32 *code, int adjust);
593    
594           int pcre32_config(int what, void *where);
595    
596           const char *pcre32_version(void);
597    
598           int pcre32_pattern_to_host_byte_order(pcre32 *code,
599                pcre32_extra *extra, const unsigned char *tables);
600    
601    
602    PCRE 32-BIT API INDIRECTED FUNCTIONS
603    
604           void *(*pcre32_malloc)(size_t);
605    
606           void (*pcre32_free)(void *);
607    
608           void *(*pcre32_stack_malloc)(size_t);
609    
610           void (*pcre32_stack_free)(void *);
611    
612           int (*pcre32_callout)(pcre32_callout_block *);
613    
614    
615    PCRE 32-BIT API 32-BIT-ONLY FUNCTION
616    
617           int pcre32_utf32_to_host_byte_order(PCRE_UCHAR32 *output,
618                PCRE_SPTR32 input, int length, int *byte_order,
619                int keep_boms);
620    
621    
622    THE PCRE 32-BIT LIBRARY
623    
624           Starting  with  release  8.32, it is possible to compile a PCRE library
625           that supports 32-bit character strings, including  UTF-32  strings,  as
626           well as or instead of the original 8-bit library. This work was done by
627           Christian Persch, based on the work done  by  Zoltan  Herczeg  for  the
628           16-bit  library.  All  three  libraries contain identical sets of func-
629           tions, used in exactly the same way.  Only the names of  the  functions
630           and  the  data  types  of their arguments and results are different. To
631           avoid over-complication and reduce the documentation maintenance  load,
632           most  of  the PCRE documentation describes the 8-bit library, with only
633           occasional references to the 16-bit and  32-bit  libraries.  This  page
634           describes what is different when you use the 32-bit library.
635    
636           WARNING:  A  single  application  can  be linked with all or any of the
637           three libraries, but you must take care when processing any  particular
638           pattern  to  use  functions  from just one library. For example, if you
639           want to study a pattern that was compiled  with  pcre32_compile(),  you
640           must do so with pcre32_study(), not pcre_study(), and you must free the
641           study data with pcre32_free_study().
642    
643    
644    THE HEADER FILE
645    
646           There is only one header file, pcre.h. It contains prototypes  for  all
647           the  functions  in  both  libraries,  as  well as definitions of flags,
648           structures, error codes, etc.
649    
650    
651    THE LIBRARY NAME
652    
653           In Unix-like systems, the 32-bit library is called libpcre32,  and  can
654           normally  be  accesss  by adding -lpcre32 to the command for linking an
655           application that uses PCRE.
656    
657    
658    STRING TYPES
659    
660           In the 8-bit library, strings are passed to PCRE library  functions  as
661           vectors  of  bytes  with  the  C  type "char *". In the 32-bit library,
662           strings are passed as vectors of unsigned 32-bit quantities. The  macro
663           PCRE_UCHAR32  specifies  an  appropriate  data type, and PCRE_SPTR32 is
664           defined as "const PCRE_UCHAR32 *". In very many environments, "unsigned
665           int" is a 32-bit data type. When PCRE is built, it defines PCRE_UCHAR32
666           as "unsigned int", but checks that it really is a 32-bit data type.  If
667           it is not, the build fails with an error message telling the maintainer
668           to modify the definition appropriately.
669    
670    
671    STRUCTURE TYPES
672    
673           The types of the opaque structures that are used  for  compiled  32-bit
674           patterns  and  JIT stacks are pcre32 and pcre32_jit_stack respectively.
675           The  type  of  the  user-accessible  structure  that  is  returned   by
676           pcre32_study()  is  pcre32_extra, and the type of the structure that is
677           used for passing data to a callout  function  is  pcre32_callout_block.
678           These structures contain the same fields, with the same names, as their
679           8-bit counterparts. The only difference is that pointers  to  character
680           strings are 32-bit instead of 8-bit types.
681    
682    
683    32-BIT FUNCTIONS
684    
685           For  every function in the 8-bit library there is a corresponding func-
686           tion in the 32-bit library with a name that starts with pcre32_ instead
687           of  pcre_.  The  prototypes are listed above. In addition, there is one
688           extra function, pcre32_utf32_to_host_byte_order(). This  is  a  utility
689           function  that converts a UTF-32 character string to host byte order if
690           necessary. The other 32-bit  functions  expect  the  strings  they  are
691           passed to be in host byte order.
692    
693           The input and output arguments of pcre32_utf32_to_host_byte_order() may
694           point to the same address, that is, conversion in place  is  supported.
695           The output buffer must be at least as long as the input.
696    
697           The  length  argument  specifies the number of 32-bit data units in the
698           input string; a negative value specifies a zero-terminated string.
699    
700           If byte_order is NULL, it is assumed that the string starts off in host
701           byte  order. This may be changed by byte-order marks (BOMs) anywhere in
702           the string (commonly as the first character).
703    
704           If byte_order is not NULL, a non-zero value of the integer to which  it
705           points  means  that  the input starts off in host byte order, otherwise
706           the opposite order is assumed. Again, BOMs in  the  string  can  change
707           this. The final byte order is passed back at the end of processing.
708    
709           If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
710           copied into the output string. Otherwise they are discarded.
711    
712           The result of the function is the number of 32-bit  units  placed  into
713           the  output  buffer,  including  the  zero terminator if the string was
714           zero-terminated.
715    
716    
717    SUBJECT STRING OFFSETS
718    
719           The offsets within subject strings that are returned  by  the  matching
720           functions are in 32-bit units rather than bytes.
721    
722    
723    NAMED SUBPATTERNS
724    
725           The  name-to-number translation table that is maintained for named sub-
726           patterns uses 32-bit characters.  The  pcre32_get_stringtable_entries()
727           function returns the length of each entry in the table as the number of
728           32-bit data units.
729    
730    
731    OPTION NAMES
732    
733           There   are   two   new   general   option   names,   PCRE_UTF32    and
734           PCRE_NO_UTF32_CHECK,     which     correspond    to    PCRE_UTF8    and
735           PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
736           define  the  same bits in the options word. There is a discussion about
737           the validity of UTF-32 strings in the pcreunicode page.
738    
739           For the pcre32_config() function there is an  option  PCRE_CONFIG_UTF32
740           that  returns  1  if UTF-32 support is configured, otherwise 0. If this
741           option  is  given  to  pcre_config()  or  pcre16_config(),  or  if  the
742           PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF16  option is given to pcre32_con-
743           fig(), the result is the PCRE_ERROR_BADOPTION error.
744    
745    
746    CHARACTER CODES
747    
748           In 32-bit mode, when  PCRE_UTF32  is  not  set,  character  values  are
749           treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
750           that they can range from 0 to 0x7fffffff instead of 0 to 0xff.  Charac-
751           ter  types for characters less than 0xff can therefore be influenced by
752           the locale in the same way as before.   Characters  greater  than  0xff
753           have only one case, and no "type" (such as letter or digit).
754    
755           In  UTF-32  mode,  the  character  code  is  Unicode, in the range 0 to
756           0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
757           because those are "surrogate" values that are ill-formed in UTF-32.
758    
759           A  UTF-32 string can indicate its endianness by special code knows as a
760           byte-order mark (BOM). The PCRE functions do not handle this, expecting
761           strings   to   be  in  host  byte  order.  A  utility  function  called
762           pcre32_utf32_to_host_byte_order() is provided to help  with  this  (see
763           above).
764    
765    
766    ERROR NAMES
767    
768           The  error  PCRE_ERROR_BADUTF32  corresponds  to its 8-bit counterpart.
769           The error PCRE_ERROR_BADMODE is given when a compiled pattern is passed
770           to  a  function that processes patterns in the other mode, for example,
771           if a pattern compiled with pcre_compile() is passed to pcre32_exec().
772    
773           There are new error codes whose names  begin  with  PCRE_UTF32_ERR  for
774           invalid  UTF-32  strings,  corresponding to the PCRE_UTF8_ERR codes for
775           UTF-8 strings that are described in the section entitled "Reason  codes
776           for  invalid UTF-8 strings" in the main pcreapi page. The UTF-32 errors
777           are:
778    
779             PCRE_UTF32_ERR1  Surrogate character (range from 0xd800 to 0xdfff)
780             PCRE_UTF32_ERR2  Non-character
781             PCRE_UTF32_ERR3  Character > 0x10ffff
782    
783    
784    ERROR TEXTS
785    
786           If there is an error while compiling a pattern, the error text that  is
787           passed  back by pcre32_compile() or pcre32_compile2() is still an 8-bit
788           character string, zero-terminated.
789    
790    
791    CALLOUTS
792    
793           The subject and mark fields in the callout block that is  passed  to  a
794           callout function point to 32-bit vectors.
795    
796    
797    TESTING
798    
799           The  pcretest  program continues to operate with 8-bit input and output
800           files, but it can be used for testing the 32-bit library. If it is  run
801           with the command line option -32, patterns and subject strings are con-
802           verted from 8-bit to 32-bit before being passed to PCRE, and the 32-bit
803           library  functions  are used instead of the 8-bit ones. Returned 32-bit
804           strings are converted to 8-bit for output. If both the  8-bit  and  the
805           16-bit libraries were not compiled, pcretest defaults to 32-bit and the
806           -32 option is ignored.
807    
808           When PCRE is being built, the RunTest script that is  called  by  "make
809           check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
810           16-bit and 32-bit libraries has been built, and runs the  tests  appro-
811           priately.
812    
813    
814    NOT SUPPORTED IN 32-BIT MODE
815    
816           Not all the features of the 8-bit library are available with the 32-bit
817           library. The C++ and POSIX wrapper functions  support  only  the  8-bit
818           library, and the pcregrep program is at present 8-bit only.
819    
820    
821    AUTHOR
822    
823           Philip Hazel
824           University Computing Service
825           Cambridge CB2 3QH, England.
826    
827    
828    REVISION
829    
830           Last updated: 24 June 2012
831           Copyright (c) 1997-2012 University of Cambridge.
832    ------------------------------------------------------------------------------
833    
834    
835  PCREBUILD(3)                                                      PCREBUILD(3)  PCREBUILD(3)                                                      PCREBUILD(3)
836    
837    
# Line 483  PCRE BUILD-TIME OPTIONS Line 849  PCRE BUILD-TIME OPTIONS
849         environments using the GUI facility of cmake-gui if you are using CMake         environments using the GUI facility of cmake-gui if you are using CMake
850         instead of configure to build PCRE.         instead of configure to build PCRE.
851    
852         There  is  a  lot more information about building PCRE in non-Unix-like         There  is a lot more information about building PCRE without using con-
853         environments in the file called NON_UNIX_USE, which is part of the PCRE         figure (including information about using CMake or building "by  hand")
854         distribution.  You  should consult this file as well as the README file         in  the file called NON-AUTOTOOLS-BUILD, which is part of the PCRE dis-
855         if you are building in a non-Unix-like environment.         tribution. You should consult this file as well as the README  file  if
856           you are building in a non-Unix-like environment.
857    
858         The complete list of options for configure (which includes the standard         The complete list of options for configure (which includes the standard
859         ones  such  as  the  selection  of  the  installation directory) can be         ones such as the  selection  of  the  installation  directory)  can  be
860         obtained by running         obtained by running
861    
862           ./configure --help           ./configure --help
863    
864         The following sections include  descriptions  of  options  whose  names         The  following  sections  include  descriptions  of options whose names
865         begin with --enable or --disable. These settings specify changes to the         begin with --enable or --disable. These settings specify changes to the
866         defaults for the configure command. Because of the way  that  configure         defaults  for  the configure command. Because of the way that configure
867         works,  --enable  and --disable always come in pairs, so the complemen-         works, --enable and --disable always come in pairs, so  the  complemen-
868         tary option always exists as well, but as it specifies the default,  it         tary  option always exists as well, but as it specifies the default, it
869         is not described.         is not described.
870    
871    
872  BUILDING 8-BIT and 16-BIT LIBRARIES  BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES
873    
874         By  default,  a  library  called libpcre is built, containing functions         By default, a library called libpcre  is  built,  containing  functions
875         that take string arguments contained in vectors  of  bytes,  either  as         that  take  string  arguments  contained in vectors of bytes, either as
876         single-byte  characters,  or interpreted as UTF-8 strings. You can also         single-byte characters, or interpreted as UTF-8 strings. You  can  also
877         build a separate library, called libpcre16, in which strings  are  con-         build  a  separate library, called libpcre16, in which strings are con-
878         tained  in  vectors of 16-bit data units and interpreted either as sin-         tained in vectors of 16-bit data units and interpreted either  as  sin-
879         gle-unit characters or UTF-16 strings, by adding         gle-unit characters or UTF-16 strings, by adding
880    
881           --enable-pcre16           --enable-pcre16
882    
883           to the configure command. You can also build a separate library, called
884           libpcre32, in which strings are contained in  vectors  of  32-bit  data
885           units  and  interpreted  either  as  single-unit  characters  or UTF-32
886           strings, by adding
887    
888             --enable-pcre32
889    
890         to the configure command. If you do not want the 8-bit library, add         to the configure command. If you do not want the 8-bit library, add
891    
892           --disable-pcre8           --disable-pcre8
893    
894         as well. At least one of the two libraries must be built. Note that the         as well. At least one of the three libraries must be built.  Note  that
895         C++  and  POSIX wrappers are for the 8-bit library only, and that pcre-         the  C++  and  POSIX  wrappers are for the 8-bit library only, and that
896         grep is an 8-bit program. None of these are built if  you  select  only         pcregrep is an 8-bit program. None of these are  built  if  you  select
897         the 16-bit library.         only the 16-bit or 32-bit libraries.
898    
899    
900  BUILDING SHARED AND STATIC LIBRARIES  BUILDING SHARED AND STATIC LIBRARIES
# Line 547  C++ SUPPORT Line 921  C++ SUPPORT
921         to the configure command.         to the configure command.
922    
923    
924  UTF-8 and UTF-16 SUPPORT  UTF-8, UTF-16 AND UTF-32 SUPPORT
925    
926         To build PCRE with support for UTF Unicode character strings, add         To build PCRE with support for UTF Unicode character strings, add
927    
928           --enable-utf           --enable-utf
929    
930         to the configure command.  This  setting  applies  to  both  libraries,         to the configure command. This setting applies to all three  libraries,
931         adding support for UTF-8 to the 8-bit library and support for UTF-16 to         adding  support  for  UTF-8 to the 8-bit library, support for UTF-16 to
932         the 16-bit library. There are no separate options  for  enabling  UTF-8         the 16-bit library, and  support  for  UTF-32  to  the  to  the  32-bit
933         and  UTF-16  independently because that would allow ridiculous settings         library.  There  are no separate options for enabling UTF-8, UTF-16 and
934         such as  requesting  UTF-16  support  while  building  only  the  8-bit         UTF-32 independently because that would allow ridiculous settings  such
935         library.  It  is not possible to build one library with UTF support and         as  requesting UTF-16 support while building only the 8-bit library. It
936         the other without in the same configuration. (For backwards compatibil-         is not possible to build one library with UTF support and another with-
937         ity, --enable-utf8 is a synonym of --enable-utf.)         out  in the same configuration. (For backwards compatibility, --enable-
938           utf8 is a synonym of --enable-utf.)
939         Of  itself,  this  setting does not make PCRE treat strings as UTF-8 or  
940         UTF-16. As well as compiling PCRE with this option, you also have  have         Of itself, this setting does not make  PCRE  treat  strings  as  UTF-8,
941         to set the PCRE_UTF8 or PCRE_UTF16 option when you call one of the pat-         UTF-16  or UTF-32. As well as compiling PCRE with this option, you also
942         tern compiling functions.         have have to set the PCRE_UTF8, PCRE_UTF16  or  PCRE_UTF32  option  (as
943           appropriate) when you call one of the pattern compiling functions.
944    
945         If you set --enable-utf when compiling in an EBCDIC  environment,  PCRE         If  you  set --enable-utf when compiling in an EBCDIC environment, PCRE
946         expects  its  input  to be either ASCII or UTF-8 (depending on the run-         expects its input to be either ASCII or UTF-8 (depending  on  the  run-
947         time option). It is not possible to support both EBCDIC and UTF-8 codes         time option). It is not possible to support both EBCDIC and UTF-8 codes
948         in  the  same  version  of  the library. Consequently, --enable-utf and         in the same version of  the  library.  Consequently,  --enable-utf  and
949         --enable-ebcdic are mutually exclusive.         --enable-ebcdic are mutually exclusive.
950    
951    
952  UNICODE CHARACTER PROPERTY SUPPORT  UNICODE CHARACTER PROPERTY SUPPORT
953    
954         UTF support allows the libraries to process character codepoints up  to         UTF  support allows the libraries to process character codepoints up to
955         0x10ffff  in the strings that they handle. On its own, however, it does         0x10ffff in the strings that they handle. On its own, however, it  does
956         not provide any facilities for accessing the properties of such charac-         not provide any facilities for accessing the properties of such charac-
957         ters. If you want to be able to use the pattern escapes \P, \p, and \X,         ters. If you want to be able to use the pattern escapes \P, \p, and \X,
958         which refer to Unicode character properties, you must add         which refer to Unicode character properties, you must add
959    
960           --enable-unicode-properties           --enable-unicode-properties
961    
962         to the configure command. This implies UTF support, even  if  you  have         to  the  configure  command. This implies UTF support, even if you have
963         not explicitly requested it.         not explicitly requested it.
964    
965         Including  Unicode  property  support  adds around 30K of tables to the         Including Unicode property support adds around 30K  of  tables  to  the
966         PCRE library. Only the general category properties such as  Lu  and  Nd         PCRE  library.  Only  the general category properties such as Lu and Nd
967         are supported. Details are given in the pcrepattern documentation.         are supported. Details are given in the pcrepattern documentation.
968    
969    
# Line 598  JUST-IN-TIME COMPILER SUPPORT Line 973  JUST-IN-TIME COMPILER SUPPORT
973    
974           --enable-jit           --enable-jit
975    
976         This  support  is available only for certain hardware architectures. If         This support is available only for certain hardware  architectures.  If
977         this option is set for an  unsupported  architecture,  a  compile  time         this  option  is  set  for  an unsupported architecture, a compile time
978         error  occurs.   See  the pcrejit documentation for a discussion of JIT         error occurs.  See the pcrejit documentation for a  discussion  of  JIT
979         usage. When JIT support is enabled, pcregrep automatically makes use of         usage. When JIT support is enabled, pcregrep automatically makes use of
980         it, unless you add         it, unless you add
981    
# Line 611  JUST-IN-TIME COMPILER SUPPORT Line 986  JUST-IN-TIME COMPILER SUPPORT
986    
987  CODE VALUE OF NEWLINE  CODE VALUE OF NEWLINE
988    
989         By  default,  PCRE interprets the linefeed (LF) character as indicating         By default, PCRE interprets the linefeed (LF) character  as  indicating
990         the end of a line. This is the normal newline  character  on  Unix-like         the  end  of  a line. This is the normal newline character on Unix-like
991         systems.  You  can compile PCRE to use carriage return (CR) instead, by         systems. You can compile PCRE to use carriage return (CR)  instead,  by
992         adding         adding
993    
994           --enable-newline-is-cr           --enable-newline-is-cr
995    
996         to the  configure  command.  There  is  also  a  --enable-newline-is-lf         to  the  configure  command.  There  is  also  a --enable-newline-is-lf
997         option, which explicitly specifies linefeed as the newline character.         option, which explicitly specifies linefeed as the newline character.
998    
999         Alternatively, you can specify that line endings are to be indicated by         Alternatively, you can specify that line endings are to be indicated by
# Line 630  CODE VALUE OF NEWLINE Line 1005  CODE VALUE OF NEWLINE
1005    
1006           --enable-newline-is-anycrlf           --enable-newline-is-anycrlf
1007    
1008         which causes PCRE to recognize any of the three sequences  CR,  LF,  or         which  causes  PCRE  to recognize any of the three sequences CR, LF, or
1009         CRLF as indicating a line ending. Finally, a fifth option, specified by         CRLF as indicating a line ending. Finally, a fifth option, specified by
1010    
1011           --enable-newline-is-any           --enable-newline-is-any
1012    
1013         causes PCRE to recognize any Unicode newline sequence.         causes PCRE to recognize any Unicode newline sequence.
1014    
1015         Whatever  line  ending convention is selected when PCRE is built can be         Whatever line ending convention is selected when PCRE is built  can  be
1016         overridden when the library functions are called. At build time  it  is         overridden  when  the library functions are called. At build time it is
1017         conventional to use the standard for your operating system.         conventional to use the standard for your operating system.
1018    
1019    
1020  WHAT \R MATCHES  WHAT \R MATCHES
1021    
1022         By  default,  the  sequence \R in a pattern matches any Unicode newline         By default, the sequence \R in a pattern matches  any  Unicode  newline
1023         sequence, whatever has been selected as the line  ending  sequence.  If         sequence,  whatever  has  been selected as the line ending sequence. If
1024         you specify         you specify
1025    
1026           --enable-bsr-anycrlf           --enable-bsr-anycrlf
1027    
1028         the  default  is changed so that \R matches only CR, LF, or CRLF. What-         the default is changed so that \R matches only CR, LF, or  CRLF.  What-
1029         ever is selected when PCRE is built can be overridden when the  library         ever  is selected when PCRE is built can be overridden when the library
1030         functions are called.         functions are called.
1031    
1032    
1033  POSIX MALLOC USAGE  POSIX MALLOC USAGE
1034    
1035         When  the  8-bit library is called through the POSIX interface (see the         When the 8-bit library is called through the POSIX interface  (see  the
1036         pcreposix documentation), additional working storage  is  required  for         pcreposix  documentation),  additional  working storage is required for
1037         holding  the  pointers  to  capturing substrings, because PCRE requires         holding the pointers to capturing  substrings,  because  PCRE  requires
1038         three integers per substring, whereas the POSIX interface provides only         three integers per substring, whereas the POSIX interface provides only
1039         two.  If  the number of expected substrings is small, the wrapper func-         two. If the number of expected substrings is small, the  wrapper  func-
1040         tion uses space on the stack, because this is faster  than  using  mal-         tion  uses  space  on the stack, because this is faster than using mal-
1041         loc()  for each call. The default threshold above which the stack is no         loc() for each call. The default threshold above which the stack is  no
1042         longer used is 10; it can be changed by adding a setting such as         longer used is 10; it can be changed by adding a setting such as
1043    
1044           --with-posix-malloc-threshold=20           --with-posix-malloc-threshold=20
# Line 673  POSIX MALLOC USAGE Line 1048  POSIX MALLOC USAGE
1048    
1049  HANDLING VERY LARGE PATTERNS  HANDLING VERY LARGE PATTERNS
1050    
1051         Within a compiled pattern, offset values are used  to  point  from  one         Within  a  compiled  pattern,  offset values are used to point from one
1052         part  to another (for example, from an opening parenthesis to an alter-         part to another (for example, from an opening parenthesis to an  alter-
1053         nation metacharacter). By default, two-byte values are used  for  these         nation  metacharacter).  By default, in the 8-bit and 16-bit libraries,
1054         offsets,  leading  to  a  maximum size for a compiled pattern of around         two-byte values are used for these offsets, leading to a  maximum  size
1055         64K. This is sufficient to handle all but the most  gigantic  patterns.         for  a compiled pattern of around 64K. This is sufficient to handle all
1056         Nevertheless,  some  people do want to process truly enormous patterns,         but the most gigantic patterns.  Nevertheless, some people do  want  to
1057         so it is possible to compile PCRE to use three-byte or  four-byte  off-         process  truly  enormous patterns, so it is possible to compile PCRE to
1058         sets by adding a setting such as         use three-byte or four-byte offsets by adding a setting such as
1059    
1060           --with-link-size=3           --with-link-size=3
1061    
1062         to  the  configure command. The value given must be 2, 3, or 4. For the         to the configure command. The value given must be 2, 3, or 4.  For  the
1063         16-bit library, a value of 3 is rounded up to 4. Using  longer  offsets         16-bit  library,  a  value of 3 is rounded up to 4. In these libraries,
1064         slows down the operation of PCRE because it has to load additional data         using longer offsets slows down the operation of PCRE because it has to
1065         when handling them.         load  additional  data  when  handling them. For the 32-bit library the
1066           value is always 4 and cannot be overridden; the value  of  --with-link-
1067           size is ignored.
1068    
1069    
1070  AVOIDING EXCESSIVE STACK USAGE  AVOIDING EXCESSIVE STACK USAGE
1071    
1072         When matching with the pcre_exec() function, PCRE implements backtrack-         When matching with the pcre_exec() function, PCRE implements backtrack-
1073         ing  by  making recursive calls to an internal function called match().         ing by making recursive calls to an internal function  called  match().
1074         In environments where the size of the stack is limited,  this  can  se-         In  environments  where  the size of the stack is limited, this can se-
1075         verely  limit  PCRE's operation. (The Unix environment does not usually         verely limit PCRE's operation. (The Unix environment does  not  usually
1076         suffer from this problem, but it may sometimes be necessary to increase         suffer from this problem, but it may sometimes be necessary to increase
1077         the  maximum  stack size.  There is a discussion in the pcrestack docu-         the maximum stack size.  There is a discussion in the  pcrestack  docu-
1078         mentation.) An alternative approach to recursion that uses memory  from         mentation.)  An alternative approach to recursion that uses memory from
1079         the  heap  to remember data, instead of using recursive function calls,         the heap to remember data, instead of using recursive  function  calls,
1080         has been implemented to work round the problem of limited  stack  size.         has  been  implemented to work round the problem of limited stack size.
1081         If you want to build a version of PCRE that works this way, add         If you want to build a version of PCRE that works this way, add
1082    
1083           --disable-stack-for-recursion           --disable-stack-for-recursion
1084    
1085         to  the  configure  command. With this configuration, PCRE will use the         to the configure command. With this configuration, PCRE  will  use  the
1086         pcre_stack_malloc and pcre_stack_free variables to call memory  manage-         pcre_stack_malloc  and pcre_stack_free variables to call memory manage-
1087         ment  functions. By default these point to malloc() and free(), but you         ment functions. By default these point to malloc() and free(), but  you
1088         can replace the pointers so that your own functions are used instead.         can replace the pointers so that your own functions are used instead.
1089    
1090         Separate functions are  provided  rather  than  using  pcre_malloc  and         Separate  functions  are  provided  rather  than  using pcre_malloc and
1091         pcre_free  because  the  usage  is  very  predictable:  the block sizes         pcre_free because the  usage  is  very  predictable:  the  block  sizes
1092         requested are always the same, and  the  blocks  are  always  freed  in         requested  are  always  the  same,  and  the blocks are always freed in
1093         reverse  order.  A calling program might be able to implement optimized         reverse order. A calling program might be able to  implement  optimized
1094         functions that perform better  than  malloc()  and  free().  PCRE  runs         functions  that  perform  better  than  malloc()  and free(). PCRE runs
1095         noticeably more slowly when built in this way. This option affects only         noticeably more slowly when built in this way. This option affects only
1096         the pcre_exec() function; it is not relevant for pcre_dfa_exec().         the pcre_exec() function; it is not relevant for pcre_dfa_exec().
1097    
1098    
1099  LIMITING PCRE RESOURCE USAGE  LIMITING PCRE RESOURCE USAGE
1100    
1101         Internally, PCRE has a function called match(), which it calls  repeat-         Internally,  PCRE has a function called match(), which it calls repeat-
1102         edly   (sometimes   recursively)  when  matching  a  pattern  with  the         edly  (sometimes  recursively)  when  matching  a  pattern   with   the
1103         pcre_exec() function. By controlling the maximum number of  times  this         pcre_exec()  function.  By controlling the maximum number of times this
1104         function  may be called during a single matching operation, a limit can         function may be called during a single matching operation, a limit  can
1105         be placed on the resources used by a single call  to  pcre_exec().  The         be  placed  on  the resources used by a single call to pcre_exec(). The
1106         limit  can be changed at run time, as described in the pcreapi documen-         limit can be changed at run time, as described in the pcreapi  documen-
1107         tation. The default is 10 million, but this can be changed by adding  a         tation.  The default is 10 million, but this can be changed by adding a
1108         setting such as         setting such as
1109    
1110           --with-match-limit=500000           --with-match-limit=500000
1111    
1112         to   the   configure  command.  This  setting  has  no  effect  on  the         to  the  configure  command.  This  setting  has  no  effect   on   the
1113         pcre_dfa_exec() matching function.         pcre_dfa_exec() matching function.
1114    
1115         In some environments it is desirable to limit the  depth  of  recursive         In  some  environments  it is desirable to limit the depth of recursive
1116         calls of match() more strictly than the total number of calls, in order         calls of match() more strictly than the total number of calls, in order
1117         to restrict the maximum amount of stack (or heap,  if  --disable-stack-         to  restrict  the maximum amount of stack (or heap, if --disable-stack-
1118         for-recursion is specified) that is used. A second limit controls this;         for-recursion is specified) that is used. A second limit controls this;
1119         it defaults to the value that  is  set  for  --with-match-limit,  which         it  defaults  to  the  value  that is set for --with-match-limit, which
1120         imposes  no  additional constraints. However, you can set a lower limit         imposes no additional constraints. However, you can set a  lower  limit
1121         by adding, for example,         by adding, for example,
1122    
1123           --with-match-limit-recursion=10000           --with-match-limit-recursion=10000
1124    
1125         to the configure command. This value can  also  be  overridden  at  run         to  the  configure  command.  This  value can also be overridden at run
1126         time.         time.
1127    
1128    
1129  CREATING CHARACTER TABLES AT BUILD TIME  CREATING CHARACTER TABLES AT BUILD TIME
1130    
1131         PCRE  uses fixed tables for processing characters whose code values are         PCRE uses fixed tables for processing characters whose code values  are
1132         less than 256. By default, PCRE is built with a set of tables that  are         less  than 256. By default, PCRE is built with a set of tables that are
1133         distributed  in  the  file pcre_chartables.c.dist. These tables are for         distributed in the file pcre_chartables.c.dist. These  tables  are  for
1134         ASCII codes only. If you add         ASCII codes only. If you add
1135    
1136           --enable-rebuild-chartables           --enable-rebuild-chartables
1137    
1138         to the configure command, the distributed tables are  no  longer  used.         to  the  configure  command, the distributed tables are no longer used.
1139         Instead,  a  program  called dftables is compiled and run. This outputs         Instead, a program called dftables is compiled and  run.  This  outputs
1140         the source for new set of tables, created in the default locale of your         the source for new set of tables, created in the default locale of your
1141         C  run-time  system. (This method of replacing the tables does not work         C run-time system. (This method of replacing the tables does  not  work
1142         if you are cross compiling, because dftables is run on the local  host.         if  you are cross compiling, because dftables is run on the local host.
1143         If you need to create alternative tables when cross compiling, you will         If you need to create alternative tables when cross compiling, you will
1144         have to do so "by hand".)         have to do so "by hand".)
1145    
1146    
1147  USING EBCDIC CODE  USING EBCDIC CODE
1148    
1149         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
1150         character  code  is  ASCII  (or Unicode, which is a superset of ASCII).         character code is ASCII (or Unicode, which is  a  superset  of  ASCII).
1151         This is the case for most computer operating systems.  PCRE  can,  how-         This  is  the  case for most computer operating systems. PCRE can, how-
1152         ever, be compiled to run in an EBCDIC environment by adding         ever, be compiled to run in an EBCDIC environment by adding
1153    
1154           --enable-ebcdic           --enable-ebcdic
1155    
1156         to the configure command. This setting implies --enable-rebuild-charta-         to the configure command. This setting implies --enable-rebuild-charta-
1157         bles. You should only use it if you know that  you  are  in  an  EBCDIC         bles.  You  should  only  use  it if you know that you are in an EBCDIC
1158         environment  (for  example,  an  IBM  mainframe  operating system). The         environment (for example,  an  IBM  mainframe  operating  system).  The
1159         --enable-ebcdic option is incompatible with --enable-utf.         --enable-ebcdic option is incompatible with --enable-utf.
1160    
1161           The EBCDIC character that corresponds to an ASCII LF is assumed to have
1162           the value 0x15 by default. However, in some EBCDIC  environments,  0x25
1163           is used. In such an environment you should use
1164    
1165             --enable-ebcdic-nl25
1166    
1167           as well as, or instead of, --enable-ebcdic. The EBCDIC character for CR
1168           has the same value as in ASCII, namely, 0x0d.  Whichever  of  0x15  and
1169           0x25 is not chosen as LF is made to correspond to the Unicode NEL char-
1170           acter (which, in Unicode, is 0x85).
1171    
1172           The options that select newline behaviour, such as --enable-newline-is-
1173           cr, and equivalent run-time options, refer to these character values in
1174           an EBCDIC environment.
1175    
1176    
1177  PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT  PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT
1178    
# Line 843  PCRETEST OPTION FOR LIBREADLINE SUPPORT Line 1235  PCRETEST OPTION FOR LIBREADLINE SUPPORT
1235         immediately before the configure command.         immediately before the configure command.
1236    
1237    
1238    DEBUGGING WITH VALGRIND SUPPORT
1239    
1240           By adding the
1241    
1242             --enable-valgrind
1243    
1244           option  to to the configure command, PCRE will use valgrind annotations
1245           to mark certain memory regions as  unaddressable.  This  allows  it  to
1246           detect invalid memory accesses, and is mostly useful for debugging PCRE
1247           itself.
1248    
1249    
1250    CODE COVERAGE REPORTING
1251    
1252           If your C compiler is gcc, you can build a version  of  PCRE  that  can
1253           generate a code coverage report for its test suite. To enable this, you
1254           must install lcov version 1.6 or above. Then specify
1255    
1256             --enable-coverage
1257    
1258           to the configure command and build PCRE in the usual way.
1259    
1260           Note that using ccache (a caching C compiler) is incompatible with code
1261           coverage  reporting. If you have configured ccache to run automatically
1262           on your system, you must set the environment variable
1263    
1264             CCACHE_DISABLE=1
1265    
1266           before running make to build PCRE, so that ccache is not used.
1267    
1268           When --enable-coverage is used,  the  following  addition  targets  are
1269           added to the Makefile:
1270    
1271             make coverage
1272    
1273           This  creates  a  fresh  coverage report for the PCRE test suite. It is
1274           equivalent to running "make coverage-reset", "make  coverage-baseline",
1275           "make check", and then "make coverage-report".
1276    
1277             make coverage-reset
1278    
1279           This zeroes the coverage counters, but does nothing else.
1280    
1281             make coverage-baseline
1282    
1283           This captures baseline coverage information.
1284    
1285             make coverage-report
1286    
1287           This creates the coverage report.
1288    
1289             make coverage-clean-report
1290    
1291           This  removes the generated coverage report without cleaning the cover-
1292           age data itself.
1293    
1294             make coverage-clean-data
1295    
1296           This removes the captured coverage data without removing  the  coverage
1297           files created at compile time (*.gcno).
1298    
1299             make coverage-clean
1300    
1301           This  cleans all coverage data including the generated coverage report.
1302           For more information about code coverage, see the gcov and  lcov  docu-
1303           mentation.
1304    
1305    
1306  SEE ALSO  SEE ALSO
1307    
1308         pcreapi(3), pcre16, pcre_config(3).         pcreapi(3), pcre16, pcre32, pcre_config(3).
1309    
1310    
1311  AUTHOR  AUTHOR
# Line 857  AUTHOR Line 1317  AUTHOR
1317    
1318  REVISION  REVISION
1319    
1320         Last updated: 07 January 2012         Last updated: 30 October 2012
1321         Copyright (c) 1997-2012 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
1322  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1323    
1324    
1325  PCREMATCHING(3)                                                PCREMATCHING(3)  PCREMATCHING(3)                                                PCREMATCHING(3)
1326    
1327    
# Line 874  PCRE MATCHING ALGORITHMS Line 1334  PCRE MATCHING ALGORITHMS
1334         This document describes the two different algorithms that are available         This document describes the two different algorithms that are available
1335         in PCRE for matching a compiled regular expression against a given sub-         in PCRE for matching a compiled regular expression against a given sub-
1336         ject  string.  The  "standard"  algorithm  is  the  one provided by the         ject  string.  The  "standard"  algorithm  is  the  one provided by the
1337         pcre_exec() and pcre16_exec() functions. These work in the same was  as         pcre_exec(), pcre16_exec() and pcre32_exec() functions. These  work  in
1338         Perl's matching function, and provide a Perl-compatible matching opera-         the  same as as Perl's matching function, and provide a Perl-compatible
1339         tion. The just-in-time (JIT) optimization  that  is  described  in  the         matching  operation.   The  just-in-time  (JIT)  optimization  that  is
1340         pcrejit documentation is compatible with these functions.         described  in  the pcrejit documentation is compatible with these func-
1341           tions.
1342         An  alternative  algorithm  is  provided  by  the  pcre_dfa_exec()  and  
1343         pcre16_dfa_exec() functions; they operate in a different way,  and  are         An  alternative  algorithm  is   provided   by   the   pcre_dfa_exec(),
1344         not  Perl-compatible. This alternative has advantages and disadvantages         pcre16_dfa_exec()  and  pcre32_dfa_exec()  functions; they operate in a
1345         compared with the standard algorithm, and these are described below.         different way, and are not Perl-compatible. This alternative has advan-
1346           tages and disadvantages compared with the standard algorithm, and these
1347           are described below.
1348    
1349         When there is only one possible way in which a given subject string can         When there is only one possible way in which a given subject string can
1350         match  a pattern, the two algorithms give the same answer. A difference         match  a pattern, the two algorithms give the same answer. A difference
# Line 1011  THE ALTERNATIVE MATCHING ALGORITHM Line 1473  THE ALTERNATIVE MATCHING ALGORITHM
1473         always 1, and the value of the capture_last field is always -1.         always 1, and the value of the capture_last field is always -1.
1474    
1475         7.  The  \C  escape  sequence, which (in the standard algorithm) always         7.  The  \C  escape  sequence, which (in the standard algorithm) always
1476         matches a single data unit, even in UTF-8 or UTF-16 modes, is not  sup-         matches a single data unit, even in UTF-8, UTF-16 or UTF-32  modes,  is
1477         ported  in these modes, because the alternative algorithm moves through         not  supported  in these modes, because the alternative algorithm moves
1478         the subject string one character (not data unit) at  a  time,  for  all         through the subject string one character (not data unit) at a time, for
1479         active paths through the tree.         all active paths through the tree.
1480    
1481         8.  Except for (*FAIL), the backtracking control verbs such as (*PRUNE)         8.  Except for (*FAIL), the backtracking control verbs such as (*PRUNE)
1482         are not supported. (*FAIL) is supported, and  behaves  like  a  failing         are not supported. (*FAIL) is supported, and  behaves  like  a  failing
# Line 1067  REVISION Line 1529  REVISION
1529         Last updated: 08 January 2012         Last updated: 08 January 2012
1530         Copyright (c) 1997-2012 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
1531  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1532    
1533    
1534  PCREAPI(3)                                                          PCREAPI(3)  PCREAPI(3)                                                          PCREAPI(3)
1535    
1536    
# Line 1140  PCRE NATIVE API STRING EXTRACTION FUNCTI Line 1602  PCRE NATIVE API STRING EXTRACTION FUNCTI
1602    
1603  PCRE NATIVE API AUXILIARY FUNCTIONS  PCRE NATIVE API AUXILIARY FUNCTIONS
1604    
1605           int pcre_jit_exec(const pcre *code, const pcre_extra *extra,
1606                const char *subject, int length, int startoffset,
1607                int options, int *ovector, int ovecsize,
1608                pcre_jit_stack *jstack);
1609    
1610         pcre_jit_stack *pcre_jit_stack_alloc(int startsize, int maxsize);         pcre_jit_stack *pcre_jit_stack_alloc(int startsize, int maxsize);
1611    
1612         void pcre_jit_stack_free(pcre_jit_stack *stack);         void pcre_jit_stack_free(pcre_jit_stack *stack);
# Line 1175  PCRE NATIVE API INDIRECTED FUNCTIONS Line 1642  PCRE NATIVE API INDIRECTED FUNCTIONS
1642         int (*pcre_callout)(pcre_callout_block *);         int (*pcre_callout)(pcre_callout_block *);
1643    
1644    
1645  PCRE 8-BIT AND 16-BIT LIBRARIES  PCRE 8-BIT, 16-BIT AND 32-BIT LIBRARIES
1646    
1647         From  release  8.30,  PCRE  can  be  compiled as a library for handling         From  release  8.30,  PCRE  can  be  compiled as a library for handling
1648         16-bit character strings as  well  as,  or  instead  of,  the  original         16-bit character strings as  well  as,  or  instead  of,  the  original
1649         library that handles 8-bit character strings. To avoid too much compli-         library  that  handles 8-bit character strings. From release 8.32, PCRE
1650         cation, this document describes the 8-bit versions  of  the  functions,         can also be  compiled  as  a  library  for  handling  32-bit  character
1651         with only occasional references to the 16-bit library.         strings.  To  avoid  too much complication, this document describes the
1652           8-bit versions of the functions, with only occasional references to the
1653         The  16-bit  functions  operate in the same way as their 8-bit counter-         16-bit and 32-bit libraries.
1654         parts; they just use different  data  types  for  their  arguments  and  
1655         results, and their names start with pcre16_ instead of pcre_. For every         The  16-bit and 32-bit functions operate in the same way as their 8-bit
1656         option that has UTF8 in its name (for example, PCRE_UTF8), there  is  a         counterparts; they just use different data types  for  their  arguments
1657         corresponding 16-bit name with UTF8 replaced by UTF16. This facility is         and  results,  and their names start with pcre16_ or pcre32_ instead of
1658         in fact just cosmetic; the 16-bit option names define the same bit val-         pcre_. For every option  that  has  UTF8  in  its  name  (for  example,
1659           PCRE_UTF8),  there  are corresponding 16-bit and 32-bit names with UTF8
1660           replaced by UTF16 or UTF32, respectively. This facility is in fact just
1661           cosmetic;  the  16-bit and 32-bit option names define the same bit val-
1662         ues.         ues.
1663    
1664         References to bytes and UTF-8 in this document should be read as refer-         References to bytes and UTF-8 in this document should be read as refer-
1665         ences to 16-bit data  quantities  and  UTF-16  when  using  the  16-bit         ences  to  16-bit  data  quantities  and  UTF-16  when using the 16-bit
1666           library, or 32-bit data quantities and UTF-32  when  using  the  32-bit
1667         library,  unless specified otherwise. More details of the specific dif-         library,  unless specified otherwise. More details of the specific dif-
1668         ferences for the 16-bit library are given in the pcre16 page.         ferences for the 16-bit and 32-bit libraries are given  in  the  pcre16
1669           and pcre32 pages.
1670    
1671    
1672  PCRE API OVERVIEW  PCRE API OVERVIEW
1673    
1674         PCRE has its own native API, which is described in this document. There         PCRE has its own native API, which is described in this document. There
1675         are  also some wrapper functions (for the 8-bit library only) that cor-         are also some wrapper functions (for the 8-bit library only) that  cor-
1676         respond to the POSIX regular expression  API,  but  they  do  not  give         respond  to  the  POSIX  regular  expression  API, but they do not give
1677         access  to  all  the functionality. They are described in the pcreposix         access to all the functionality. They are described  in  the  pcreposix
1678         documentation. Both of these APIs define a set of C function  calls.  A         documentation.  Both  of these APIs define a set of C function calls. A
1679         C++ wrapper (again for the 8-bit library only) is also distributed with         C++ wrapper (again for the 8-bit library only) is also distributed with
1680         PCRE. It is documented in the pcrecpp page.         PCRE. It is documented in the pcrecpp page.
1681    
1682         The native API C function prototypes are defined  in  the  header  file         The  native  API  C  function prototypes are defined in the header file
1683         pcre.h,  and  on Unix-like systems the (8-bit) library itself is called         pcre.h, and on Unix-like systems the (8-bit) library itself  is  called
1684         libpcre. It can normally be accessed by adding -lpcre  to  the  command         libpcre.  It  can  normally be accessed by adding -lpcre to the command
1685         for  linking an application that uses PCRE. The header file defines the         for linking an application that uses PCRE. The header file defines  the
1686         macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release         macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release
1687         numbers  for the library. Applications can use these to include support         numbers for the library. Applications can use these to include  support
1688         for different releases of PCRE.         for different releases of PCRE.
1689    
1690         In a Windows environment, if you want to statically link an application         In a Windows environment, if you want to statically link an application
1691         program  against  a  non-dll  pcre.a  file, you must define PCRE_STATIC         program against a non-dll pcre.a  file,  you  must  define  PCRE_STATIC
1692         before including pcre.h or pcrecpp.h, because otherwise  the  pcre_mal-         before  including  pcre.h or pcrecpp.h, because otherwise the pcre_mal-
1693         loc()   and   pcre_free()   exported   functions   will   be   declared         loc()   and   pcre_free()   exported   functions   will   be   declared
1694         __declspec(dllimport), with unwanted results.         __declspec(dllimport), with unwanted results.
1695    
1696         The  functions  pcre_compile(),  pcre_compile2(),   pcre_study(),   and         The   functions   pcre_compile(),  pcre_compile2(),  pcre_study(),  and
1697         pcre_exec()  are used for compiling and matching regular expressions in         pcre_exec() are used for compiling and matching regular expressions  in
1698         a Perl-compatible manner. A sample program that demonstrates  the  sim-         a  Perl-compatible  manner. A sample program that demonstrates the sim-
1699         plest  way  of  using them is provided in the file called pcredemo.c in         plest way of using them is provided in the file  called  pcredemo.c  in
1700         the PCRE source distribution. A listing of this program is given in the         the PCRE source distribution. A listing of this program is given in the
1701         pcredemo  documentation, and the pcresample documentation describes how         pcredemo documentation, and the pcresample documentation describes  how
1702         to compile and run it.         to compile and run it.
1703    
1704         Just-in-time compiler support is an optional feature of PCRE  that  can         Just-in-time  compiler  support is an optional feature of PCRE that can
1705         be built in appropriate hardware environments. It greatly speeds up the         be built in appropriate hardware environments. It greatly speeds up the
1706         matching performance of  many  patterns.  Simple  programs  can  easily         matching  performance  of  many  patterns.  Simple  programs can easily
1707         request  that  it  be  used  if available, by setting an option that is         request that it be used if available, by  setting  an  option  that  is
1708         ignored when it is not relevant. More complicated programs  might  need         ignored  when  it is not relevant. More complicated programs might need
1709         to     make    use    of    the    functions    pcre_jit_stack_alloc(),         to    make    use    of    the    functions     pcre_jit_stack_alloc(),
1710         pcre_jit_stack_free(), and pcre_assign_jit_stack() in order to  control         pcre_jit_stack_free(),  and pcre_assign_jit_stack() in order to control
1711         the  JIT  code's  memory  usage.   These functions are discussed in the         the JIT code's memory usage.
1712         pcrejit documentation.  
1713           From release 8.32 there is also a direct interface for  JIT  execution,
1714           which  gives  improved performance. The JIT-specific functions are dis-
1715           cussed in the pcrejit documentation.
1716    
1717         A second matching function, pcre_dfa_exec(), which is not Perl-compati-         A second matching function, pcre_dfa_exec(), which is not Perl-compati-
1718         ble,  is  also provided. This uses a different algorithm for the match-         ble,  is  also provided. This uses a different algorithm for the match-
# Line 1384  CHECKING BUILD-TIME OPTIONS Line 1859  CHECKING BUILD-TIME OPTIONS
1859           PCRE_CONFIG_UTF8           PCRE_CONFIG_UTF8
1860    
1861         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-
1862         able;  otherwise  it  is  set  to  zero. If this option is given to the         able;  otherwise it is set to zero. This value should normally be given
1863         16-bit  version  of  this  function,  pcre16_config(),  the  result  is         to the 8-bit version of this function, pcre_config(). If it is given to
1864           the   16-bit  or  32-bit  version  of  this  function,  the  result  is
1865         PCRE_ERROR_BADOPTION.         PCRE_ERROR_BADOPTION.
1866    
1867           PCRE_CONFIG_UTF16           PCRE_CONFIG_UTF16
1868    
1869         The output is an integer that is set to one if UTF-16 support is avail-         The output is an integer that is set to one if UTF-16 support is avail-
1870         able; otherwise it is set to zero. This value should normally be  given         able;  otherwise it is set to zero. This value should normally be given
1871         to the 16-bit version of this function, pcre16_config(). If it is given         to the 16-bit version of this function, pcre16_config(). If it is given
1872         to the 8-bit version of this function, the result is  PCRE_ERROR_BADOP-         to  the  8-bit  or  32-bit  version  of  this  function,  the result is
1873         TION.         PCRE_ERROR_BADOPTION.
1874    
1875             PCRE_CONFIG_UTF32
1876    
1877           The output is an integer that is set to one if UTF-32 support is avail-
1878           able;  otherwise it is set to zero. This value should normally be given
1879           to the 32-bit version of this function, pcre32_config(). If it is given
1880           to  the  8-bit  or  16-bit  version  of  this  function,  the result is
1881           PCRE_ERROR_BADOPTION.
1882    
1883           PCRE_CONFIG_UNICODE_PROPERTIES           PCRE_CONFIG_UNICODE_PROPERTIES
1884    
1885         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
1886         character properties is available; otherwise it is set to zero.         character properties is available; otherwise it is set to zero.
1887    
1888           PCRE_CONFIG_JIT           PCRE_CONFIG_JIT
# Line 1408  CHECKING BUILD-TIME OPTIONS Line 1892  CHECKING BUILD-TIME OPTIONS
1892    
1893           PCRE_CONFIG_JITTARGET           PCRE_CONFIG_JITTARGET
1894    
1895         The  output is a pointer to a zero-terminated "const char *" string. If         The output is a pointer to a zero-terminated "const char *" string.  If
1896         JIT support is available, the string contains the name of the architec-         JIT support is available, the string contains the name of the architec-
1897         ture  for  which the JIT compiler is configured, for example "x86 32bit         ture for which the JIT compiler is configured, for example  "x86  32bit
1898         (little endian + unaligned)". If JIT  support  is  not  available,  the         (little  endian  +  unaligned)".  If  JIT support is not available, the
1899         result is NULL.         result is NULL.
1900    
1901           PCRE_CONFIG_NEWLINE           PCRE_CONFIG_NEWLINE
1902    
1903         The  output  is  an integer whose value specifies the default character         The output is an integer whose value specifies  the  default  character
1904         sequence that is recognized as meaning "newline". The four values  that         sequence  that  is recognized as meaning "newline". The values that are
1905         are supported are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF,         supported in ASCII/Unicode environments are: 10 for LF, 13 for CR, 3338
1906         and -1 for ANY.  Though they are derived from ASCII,  the  same  values         for  CRLF,  -2 for ANYCRLF, and -1 for ANY. In EBCDIC environments, CR,
1907         are returned in EBCDIC environments. The default should normally corre-         ANYCRLF, and ANY yield the same values. However, the value  for  LF  is
1908           normally  21, though some EBCDIC environments use 37. The corresponding
1909           values for CRLF are 3349 and 3365. The default should  normally  corre-
1910         spond to the standard sequence for your operating system.         spond to the standard sequence for your operating system.
1911    
1912           PCRE_CONFIG_BSR           PCRE_CONFIG_BSR
1913    
1914         The output is an integer whose value indicates what character sequences         The output is an integer whose value indicates what character sequences
1915         the  \R  escape sequence matches by default. A value of 0 means that \R         the \R escape sequence matches by default. A value of 0 means  that  \R
1916         matches any Unicode line ending sequence; a value of 1  means  that  \R         matches  any  Unicode  line ending sequence; a value of 1 means that \R
1917         matches only CR, LF, or CRLF. The default can be overridden when a pat-         matches only CR, LF, or CRLF. The default can be overridden when a pat-
1918         tern is compiled or matched.         tern is compiled or matched.
1919    
1920           PCRE_CONFIG_LINK_SIZE           PCRE_CONFIG_LINK_SIZE
1921    
1922         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
1923         internal  linkage  in  compiled  regular  expressions.  For  the  8-bit         internal  linkage  in  compiled  regular  expressions.  For  the  8-bit
1924         library, the value can be 2, 3, or 4. For the 16-bit library, the value         library, the value can be 2, 3, or 4. For the 16-bit library, the value
1925         is either 2 or 4 and is still a number of bytes. The default value of 2         is either 2 or 4 and is  still  a  number  of  bytes.  For  the  32-bit
1926         is sufficient for all but the most massive patterns,  since  it  allows         library, the value is either 2 or 4 and is still a number of bytes. The
1927         the  compiled  pattern  to  be  up to 64K in size.  Larger values allow         default value of 2 is sufficient for all but the most massive patterns,
1928         larger regular expressions to be compiled, at  the  expense  of  slower         since  it  allows  the compiled pattern to be up to 64K in size. Larger
1929         matching.         values allow larger regular expressions to be compiled, at the  expense
1930           of slower matching.
1931    
1932           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
1933    
# Line 1726  COMPILING A PATTERN Line 2213  COMPILING A PATTERN
2213         two-character  CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF specifies         two-character  CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF specifies
2214         that any of the three preceding sequences should be recognized. Setting         that any of the three preceding sequences should be recognized. Setting
2215         PCRE_NEWLINE_ANY  specifies that any Unicode newline sequence should be         PCRE_NEWLINE_ANY  specifies that any Unicode newline sequence should be
2216         recognized. The Unicode newline sequences are the three just mentioned,         recognized.
2217         plus  the  single  characters VT (vertical tab, U+000B), FF (form feed,  
2218         U+000C), NEL (next line, U+0085), LS (line separator, U+2028),  and  PS         In an ASCII/Unicode environment, the Unicode newline sequences are  the
2219         (paragraph  separator, U+2029). For the 8-bit library, the last two are         three  just  mentioned,  plus  the  single characters VT (vertical tab,
2220         recognized only in UTF-8 mode.         U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line sep-
2221           arator,  U+2028),  and  PS (paragraph separator, U+2029). For the 8-bit
2222           library, the last two are recognized only in UTF-8 mode.
2223    
2224           When PCRE is compiled to run in an EBCDIC (mainframe) environment,  the
2225           code for CR is 0x0d, the same as ASCII. However, the character code for
2226           LF is normally 0x15, though in some EBCDIC environments 0x25  is  used.
2227           Whichever  of  these  is  not LF is made to correspond to Unicode's NEL
2228           character. EBCDIC codes are all less than 256. For  more  details,  see
2229           the pcrebuild documentation.
2230    
2231         The newline setting in the  options  word  uses  three  bits  that  are         The  newline  setting  in  the  options  word  uses three bits that are
2232         treated as a number, giving eight possibilities. Currently only six are         treated as a number, giving eight possibilities. Currently only six are
2233         used (default plus the five values above). This means that if  you  set         used  (default  plus the five values above). This means that if you set
2234         more  than one newline option, the combination may or may not be sensi-         more than one newline option, the combination may or may not be  sensi-
2235         ble. For example, PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to         ble. For example, PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to
2236         PCRE_NEWLINE_CRLF,  but other combinations may yield unused numbers and         PCRE_NEWLINE_CRLF, but other combinations may yield unused numbers  and
2237         cause an error.         cause an error.
2238    
2239         The only time that a line break in a pattern  is  specially  recognized         The  only  time  that a line break in a pattern is specially recognized
2240         when  compiling is when PCRE_EXTENDED is set. CR and LF are white space         when compiling is when PCRE_EXTENDED is set. CR and LF are white  space
2241         characters, and so are ignored in this mode. Also, an unescaped #  out-         characters,  and so are ignored in this mode. Also, an unescaped # out-
2242         side  a  character class indicates a comment that lasts until after the         side a character class indicates a comment that lasts until  after  the
2243         next line break sequence. In other circumstances, line break  sequences         next  line break sequence. In other circumstances, line break sequences
2244         in patterns are treated as literal data.         in patterns are treated as literal data.
2245    
2246         The newline option that is set at compile time becomes the default that         The newline option that is set at compile time becomes the default that
# Line 1753  COMPILING A PATTERN Line 2249  COMPILING A PATTERN
2249           PCRE_NO_AUTO_CAPTURE           PCRE_NO_AUTO_CAPTURE
2250    
2251         If this option is set, it disables the use of numbered capturing paren-         If this option is set, it disables the use of numbered capturing paren-
2252         theses  in the pattern. Any opening parenthesis that is not followed by         theses in the pattern. Any opening parenthesis that is not followed  by
2253         ? behaves as if it were followed by ?: but named parentheses can  still         ?  behaves as if it were followed by ?: but named parentheses can still
2254         be  used  for  capturing  (and  they acquire numbers in the usual way).         be used for capturing (and they acquire  numbers  in  the  usual  way).
2255         There is no equivalent of this option in Perl.         There is no equivalent of this option in Perl.
2256    
2257           NO_START_OPTIMIZE           NO_START_OPTIMIZE
2258    
2259         This is an option that acts at matching time; that is, it is really  an         This  is an option that acts at matching time; that is, it is really an
2260         option  for  pcre_exec()  or  pcre_dfa_exec().  If it is set at compile         option for pcre_exec() or pcre_dfa_exec(). If  it  is  set  at  compile
2261         time, it is remembered with the compiled pattern and assumed at  match-         time,  it is remembered with the compiled pattern and assumed at match-
2262         ing  time.  For  details  see  the discussion of PCRE_NO_START_OPTIMIZE         ing time. For details  see  the  discussion  of  PCRE_NO_START_OPTIMIZE
2263         below.         below.
2264    
2265           PCRE_UCP           PCRE_UCP
2266    
2267         This option changes the way PCRE processes \B, \b, \D, \d, \S, \s,  \W,         This  option changes the way PCRE processes \B, \b, \D, \d, \S, \s, \W,
2268         \w,  and  some  of  the POSIX character classes. By default, only ASCII         \w, and some of the POSIX character classes.  By  default,  only  ASCII
2269         characters are recognized, but if PCRE_UCP is set,  Unicode  properties         characters  are  recognized, but if PCRE_UCP is set, Unicode properties
2270         are  used instead to classify characters. More details are given in the         are used instead to classify characters. More details are given in  the
2271         section on generic character types in the pcrepattern page. If you  set         section  on generic character types in the pcrepattern page. If you set
2272         PCRE_UCP,  matching  one of the items it affects takes much longer. The         PCRE_UCP, matching one of the items it affects takes much  longer.  The
2273         option is available only if PCRE has been compiled with  Unicode  prop-         option  is  available only if PCRE has been compiled with Unicode prop-
2274         erty support.         erty support.
2275    
2276           PCRE_UNGREEDY           PCRE_UNGREEDY
2277    
2278         This  option  inverts  the "greediness" of the quantifiers so that they         This option inverts the "greediness" of the quantifiers  so  that  they
2279         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
2280         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
2281         within the pattern.         within the pattern.
2282    
2283           PCRE_UTF8           PCRE_UTF8
2284    
2285         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
2286         strings of UTF-8 characters instead of single-byte strings. However, it         strings of UTF-8 characters instead of single-byte strings. However, it
2287         is available only when PCRE is built to include UTF  support.  If  not,         is  available  only  when PCRE is built to include UTF support. If not,
2288         the  use  of  this option provokes an error. Details of how this option         the use of this option provokes an error. Details of  how  this  option
2289         changes the behaviour of PCRE are given in the pcreunicode page.         changes the behaviour of PCRE are given in the pcreunicode page.
2290    
2291           PCRE_NO_UTF8_CHECK           PCRE_NO_UTF8_CHECK
2292    
2293         When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is         When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
2294         automatically  checked.  There  is  a  discussion about the validity of         automatically checked. There is a  discussion  about  the  validity  of
2295         UTF-8 strings in the pcreunicode page. If an invalid UTF-8 sequence  is         UTF-8  strings in the pcreunicode page. If an invalid UTF-8 sequence is
2296         found,  pcre_compile()  returns an error. If you already know that your         found, pcre_compile() returns an error. If you already know  that  your
2297         pattern is valid, and you want to skip this check for performance  rea-         pattern  is valid, and you want to skip this check for performance rea-
2298         sons,  you  can set the PCRE_NO_UTF8_CHECK option.  When it is set, the         sons, you can set the PCRE_NO_UTF8_CHECK option.  When it is  set,  the
2299         effect of passing an invalid UTF-8 string as a pattern is undefined. It         effect of passing an invalid UTF-8 string as a pattern is undefined. It
2300         may  cause  your  program  to  crash. Note that this option can also be         may cause your program to crash. Note that  this  option  can  also  be
2301         passed to pcre_exec() and pcre_dfa_exec(),  to  suppress  the  validity         passed  to  pcre_exec()  and  pcre_dfa_exec(), to suppress the validity
2302         checking of subject strings.         checking of subject strings only. If the same string is  being  matched
2303           many  times, the option can be safely set for the second and subsequent
2304           matchings to improve performance.
2305    
2306    
2307  COMPILATION ERROR CODES  COMPILATION ERROR CODES
2308    
2309         The  following  table  lists  the  error  codes than may be returned by         The following table lists the error  codes  than  may  be  returned  by
2310         pcre_compile2(), along with the error messages that may be returned  by         pcre_compile2(),  along with the error messages that may be returned by
2311         both  compiling  functions.  Note  that error messages are always 8-bit         both compiling functions. Note that error  messages  are  always  8-bit
2312         ASCII strings, even in 16-bit mode. As PCRE has developed,  some  error         ASCII  strings,  even  in 16-bit or 32-bit mode. As PCRE has developed,
2313         codes  have  fallen  out of use. To avoid confusion, they have not been         some error codes have fallen out of use. To avoid confusion, they  have
2314         re-used.         not been re-used.
2315    
2316            0  no error            0  no error
2317            1  \ at end of pattern            1  \ at end of pattern
# Line 1896  COMPILATION ERROR CODES Line 2394  COMPILATION ERROR CODES
2394           74  invalid UTF-16 string (specifically UTF-16)           74  invalid UTF-16 string (specifically UTF-16)
2395           75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)           75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
2396           76  character value in \u.... sequence is too large           76  character value in \u.... sequence is too large
2397             77  invalid UTF-32 string (specifically UTF-32)
2398    
2399         The numbers 32 and 10000 in errors 48 and 49  are  defaults;  different         The  numbers  32  and 10000 in errors 48 and 49 are defaults; different
2400         values may be used if the limits were changed when PCRE was built.         values may be used if the limits were changed when PCRE was built.
2401    
2402    
# Line 1906  STUDYING A PATTERN Line 2405  STUDYING A PATTERN
2405         pcre_extra *pcre_study(const pcre *code, int options         pcre_extra *pcre_study(const pcre *code, int options
2406              const char **errptr);              const char **errptr);
2407    
2408         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
2409         spending more time analyzing it in order to speed up the time taken for         spending more time analyzing it in order to speed up the time taken for
2410         matching.  The function pcre_study() takes a pointer to a compiled pat-         matching. The function pcre_study() takes a pointer to a compiled  pat-
2411         tern as its first argument. If studying the pattern produces additional         tern as its first argument. If studying the pattern produces additional
2412         information  that  will  help speed up matching, pcre_study() returns a         information that will help speed up matching,  pcre_study()  returns  a
2413         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
2414         the results of the study.         the results of the study.
2415    
2416         The  returned  value  from  pcre_study()  can  be  passed  directly  to         The  returned  value  from  pcre_study()  can  be  passed  directly  to
2417         pcre_exec() or pcre_dfa_exec(). However, a pcre_extra block  also  con-         pcre_exec()  or  pcre_dfa_exec(). However, a pcre_extra block also con-
2418         tains  other  fields  that can be set by the caller before the block is         tains other fields that can be set by the caller before  the  block  is
2419         passed; these are described below in the section on matching a pattern.         passed; these are described below in the section on matching a pattern.
2420    
2421         If studying the  pattern  does  not  produce  any  useful  information,         If  studying  the  pattern  does  not  produce  any useful information,
2422         pcre_study() returns NULL. In that circumstance, if the calling program         pcre_study() returns NULL by default.  In  that  circumstance,  if  the
2423         wants  to  pass  any  of   the   other   fields   to   pcre_exec()   or         calling program wants to pass any of the other fields to pcre_exec() or
2424         pcre_dfa_exec(), it must set up its own pcre_extra block.         pcre_dfa_exec(), it must set up its own pcre_extra block.  However,  if
2425           pcre_study()  is  called  with  the  PCRE_STUDY_EXTRA_NEEDED option, it
2426           returns a pcre_extra block even if studying did not find any additional
2427           information.  It  may still return NULL, however, if an error occurs in
2428           pcre_study().
2429    
2430         The  second  argument  of  pcre_study() contains option bits. There are         The second argument of pcre_study() contains  option  bits.  There  are
2431         three options:         three further options in addition to PCRE_STUDY_EXTRA_NEEDED:
2432    
2433           PCRE_STUDY_JIT_COMPILE           PCRE_STUDY_JIT_COMPILE
2434           PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE           PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
2435           PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE           PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
2436    
2437         If any of these are set, and the just-in-time  compiler  is  available,         If  any  of  these are set, and the just-in-time compiler is available,
2438         the  pattern  is  further compiled into machine code that executes much         the pattern is further compiled into machine code  that  executes  much
2439         faster than the pcre_exec()  interpretive  matching  function.  If  the         faster  than  the  pcre_exec()  interpretive  matching function. If the
2440         just-in-time  compiler is not available, these options are ignored. All         just-in-time compiler is not available, these options are ignored.  All
2441         other bits in the options argument must be zero.         undefined bits in the options argument must be zero.
2442    
2443         JIT compilation is a heavyweight optimization. It can  take  some  time         JIT  compilation  is  a heavyweight optimization. It can take some time
2444         for  patterns  to  be analyzed, and for one-off matches and simple pat-         for patterns to be analyzed, and for one-off matches  and  simple  pat-
2445         terns the benefit of faster execution might be offset by a much  slower         terns  the benefit of faster execution might be offset by a much slower
2446         study time.  Not all patterns can be optimized by the JIT compiler. For         study time.  Not all patterns can be optimized by the JIT compiler. For
2447         those that cannot be handled, matching automatically falls back to  the         those  that cannot be handled, matching automatically falls back to the
2448         pcre_exec()  interpreter.  For more details, see the pcrejit documenta-         pcre_exec() interpreter. For more details, see the  pcrejit  documenta-
2449         tion.         tion.
2450    
2451         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.
2452         If  studying  succeeds  (even  if no data is returned), the variable it         If studying succeeds (even if no data is  returned),  the  variable  it
2453         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
2454         error message. This is a static string that is part of the library. You         error message. This is a static string that is part of the library. You
2455         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
2456         after calling pcre_study(), to be sure that it has run successfully.         after calling pcre_study(), to be sure that it has run successfully.
2457    
2458         When  you are finished with a pattern, you can free the memory used for         When you are finished with a pattern, you can free the memory used  for
2459         the study data by calling pcre_free_study(). This function was added to         the study data by calling pcre_free_study(). This function was added to
2460         the  API  for  release  8.20. For earlier versions, the memory could be         the API for release 8.20. For earlier versions,  the  memory  could  be
2461         freed with pcre_free(), just like the pattern itself. This  will  still         freed  with  pcre_free(), just like the pattern itself. This will still
2462         work  in  cases where JIT optimization is not used, but it is advisable         work in cases where JIT optimization is not used, but it  is  advisable
2463         to change to the new function when convenient.         to change to the new function when convenient.
2464    
2465         This is a typical way in which pcre_study() is used (except that  in  a         This  is  a typical way in which pcre_study() is used (except that in a
2466         real application there should be tests for errors):         real application there should be tests for errors):
2467    
2468           int rc;           int rc;
# Line 1979  STUDYING A PATTERN Line 2482  STUDYING A PATTERN
2482         Studying a pattern does two things: first, a lower bound for the length         Studying a pattern does two things: first, a lower bound for the length
2483         of subject string that is needed to match the pattern is computed. This         of subject string that is needed to match the pattern is computed. This
2484         does not mean that there are any strings of that length that match, but         does not mean that there are any strings of that length that match, but
2485         it does guarantee that no shorter strings match. The value is  used  by         it  does  guarantee that no shorter strings match. The value is used to
2486         pcre_exec()  and  pcre_dfa_exec()  to  avoid  wasting time by trying to         avoid wasting time by trying to match strings that are shorter than the
2487         match strings that are shorter than the lower bound. You can  find  out         lower  bound.  You  can find out the value in a calling program via the
2488         the value in a calling program via the pcre_fullinfo() function.         pcre_fullinfo() function.
2489    
2490         Studying a pattern is also useful for non-anchored patterns that do not         Studying a pattern is also useful for non-anchored patterns that do not
2491         have a single fixed starting character. A bitmap of  possible  starting         have  a  single fixed starting character. A bitmap of possible starting
2492         bytes  is  created. This speeds up finding a position in the subject at         bytes is created. This speeds up finding a position in the  subject  at
2493         which to start matching. (In 16-bit mode, the bitmap is used for 16-bit         which to start matching. (In 16-bit mode, the bitmap is used for 16-bit
2494           values less than 256.  In 32-bit mode, the bitmap is  used  for  32-bit
2495         values less than 256.)         values less than 256.)
2496    
2497         These  two optimizations apply to both pcre_exec() and pcre_dfa_exec(),         These  two optimizations apply to both pcre_exec() and pcre_dfa_exec(),
# Line 2126  INFORMATION ABOUT A PATTERN Line 2630  INFORMATION ABOUT A PATTERN
2630    
2631         If  there  is  a  fixed first value, for example, the letter "c" from a         If  there  is  a  fixed first value, for example, the letter "c" from a
2632         pattern such as (cat|cow|coyote), its value is returned. In  the  8-bit         pattern such as (cat|cow|coyote), its value is returned. In  the  8-bit
2633         library,  the  value is always less than 256; in the 16-bit library the         library,  the  value is always less than 256. In the 16-bit library the
2634         value can be up to 0xffff.         value can be up to 0xffff. In the 32-bit library the value can be up to
2635           0x10ffff.
2636    
2637         If there is no fixed first value, and if either         If there is no fixed first value, and if either
2638    
2639         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every         (a)  the pattern was compiled with the PCRE_MULTILINE option, and every
2640         branch starts with "^", or         branch starts with "^", or
2641    
2642         (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not         (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2643         set (if it were set, the pattern would be anchored),         set (if it were set, the pattern would be anchored),
2644    
2645         -1 is returned, indicating that the pattern matches only at  the  start         -1  is  returned, indicating that the pattern matches only at the start
2646         of  a  subject string or after any newline within the string. Otherwise         of a subject string or after any newline within the  string.  Otherwise
2647         -2 is returned. For anchored patterns, -2 is returned.         -2 is returned. For anchored patterns, -2 is returned.
2648    
2649           Since  for  the 32-bit library using the non-UTF-32 mode, this function
2650           is unable to return the full 32-bit range of the character, this  value
2651           is    deprecated;   instead   the   PCRE_INFO_FIRSTCHARACTERFLAGS   and
2652           PCRE_INFO_FIRSTCHARACTER values should be used.
2653    
2654           PCRE_INFO_FIRSTTABLE           PCRE_INFO_FIRSTTABLE
2655    
2656         If the pattern was studied, and this resulted in the construction of  a         If the pattern was studied, and this resulted in the construction of  a
# Line 2188  INFORMATION ABOUT A PATTERN Line 2698  INFORMATION ABOUT A PATTERN
2698         example, for the pattern /^a\d+z\d+/ the returned value is "z", but for         example, for the pattern /^a\d+z\d+/ the returned value is "z", but for
2699         /^a\dz\d/ the returned value is -1.         /^a\dz\d/ the returned value is -1.
2700    
2701           Since  for  the 32-bit library using the non-UTF-32 mode, this function
2702           is unable to return the full 32-bit range of the character, this  value
2703           is    deprecated;    instead    the   PCRE_INFO_REQUIREDCHARFLAGS   and
2704           PCRE_INFO_REQUIREDCHAR values should be used.
2705    
2706           PCRE_INFO_MAXLOOKBEHIND           PCRE_INFO_MAXLOOKBEHIND
2707    
2708         Return  the  number of characters (NB not bytes) in the longest lookbe-         Return the number of characters (NB not bytes) in the  longest  lookbe-
2709         hind assertion in the pattern. Note that the simple assertions  \b  and         hind  assertion  in the pattern. Note that the simple assertions \b and
2710         \B  require a one-character lookbehind. This information is useful when         \B require a one-character lookbehind. This information is useful  when
2711         doing multi-segment matching using the partial matching facilities.         doing multi-segment matching using the partial matching facilities.
2712    
2713           PCRE_INFO_MINLENGTH           PCRE_INFO_MINLENGTH
2714    
2715         If the pattern was studied and a minimum length  for  matching  subject         If  the  pattern  was studied and a minimum length for matching subject
2716         strings  was  computed,  its  value is returned. Otherwise the returned         strings was computed, its value is  returned.  Otherwise  the  returned
2717         value is -1. The value is a number of characters, which in  UTF-8  mode         value  is  -1. The value is a number of characters, which in UTF-8 mode
2718         may  be  different from the number of bytes. The fourth argument should         may be different from the number of bytes. The fourth  argument  should
2719         point to an int variable. A non-negative value is a lower bound to  the         point  to an int variable. A non-negative value is a lower bound to the
2720         length  of  any  matching  string. There may not be any strings of that         length of any matching string. There may not be  any  strings  of  that
2721         length that do actually match, but every string that does match  is  at         length  that  do actually match, but every string that does match is at
2722         least that long.         least that long.
2723    
2724           PCRE_INFO_NAMECOUNT           PCRE_INFO_NAMECOUNT
2725           PCRE_INFO_NAMEENTRYSIZE           PCRE_INFO_NAMEENTRYSIZE
2726           PCRE_INFO_NAMETABLE           PCRE_INFO_NAMETABLE
2727    
2728         PCRE  supports the use of named as well as numbered capturing parenthe-         PCRE supports the use of named as well as numbered capturing  parenthe-
2729         ses. The names are just an additional way of identifying the  parenthe-         ses.  The names are just an additional way of identifying the parenthe-
2730         ses, which still acquire numbers. Several convenience functions such as         ses, which still acquire numbers. Several convenience functions such as
2731         pcre_get_named_substring() are provided for  extracting  captured  sub-         pcre_get_named_substring()  are  provided  for extracting captured sub-
2732         strings  by  name. It is also possible to extract the data directly, by         strings by name. It is also possible to extract the data  directly,  by
2733         first converting the name to a number in order to  access  the  correct         first  converting  the  name to a number in order to access the correct
2734         pointers in the output vector (described with pcre_exec() below). To do         pointers in the output vector (described with pcre_exec() below). To do
2735         the conversion, you need  to  use  the  name-to-number  map,  which  is         the  conversion,  you  need  to  use  the  name-to-number map, which is
2736         described by these three values.         described by these three values.
2737    
2738         The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT         The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT
2739         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size
2740         of  each  entry;  both  of  these  return  an int value. The entry size         of each entry; both of these  return  an  int  value.  The  entry  size
2741         depends on the length of the longest name. PCRE_INFO_NAMETABLE  returns         depends  on the length of the longest name. PCRE_INFO_NAMETABLE returns
2742         a pointer to the first entry of the table. This is a pointer to char in         a pointer to the first entry of the table. This is a pointer to char in
2743         the 8-bit library, where the first two bytes of each entry are the num-         the 8-bit library, where the first two bytes of each entry are the num-
2744         ber  of  the capturing parenthesis, most significant byte first. In the         ber of the capturing parenthesis, most significant byte first.  In  the
2745         16-bit library, the pointer points to 16-bit data units, the  first  of         16-bit  library,  the pointer points to 16-bit data units, the first of
2746         which  contains  the  parenthesis  number. The rest of the entry is the         which contains the parenthesis number.   In  the  32-bit  library,  the
2747         corresponding name, zero terminated.         pointer  points  to  32-bit data units, the first of which contains the
2748           parenthesis number. The rest of the entry is  the  corresponding  name,
2749           zero terminated.
2750    
2751         The names are in alphabetical order. Duplicate names may appear if  (?|         The  names are in alphabetical order. Duplicate names may appear if (?|
2752         is used to create multiple groups with the same number, as described in         is used to create multiple groups with the same number, as described in
2753         the section on duplicate subpattern numbers in  the  pcrepattern  page.         the  section  on  duplicate subpattern numbers in the pcrepattern page.
2754         Duplicate  names  for  subpatterns with different numbers are permitted         Duplicate names for subpatterns with different  numbers  are  permitted
2755         only if PCRE_DUPNAMES is set. In all cases  of  duplicate  names,  they         only  if  PCRE_DUPNAMES  is  set. In all cases of duplicate names, they
2756         appear  in  the table in the order in which they were found in the pat-         appear in the table in the order in which they were found in  the  pat-
2757         tern. In the absence of (?| this is the  order  of  increasing  number;         tern.  In  the  absence  of (?| this is the order of increasing number;
2758         when (?| is used this is not necessarily the case because later subpat-         when (?| is used this is not necessarily the case because later subpat-
2759         terns may have lower numbers.         terns may have lower numbers.
2760    
2761         As a simple example of the name/number table,  consider  the  following         As  a  simple  example of the name/number table, consider the following
2762         pattern after compilation by the 8-bit library (assume PCRE_EXTENDED is         pattern after compilation by the 8-bit library (assume PCRE_EXTENDED is
2763         set, so white space - including newlines - is ignored):         set, so white space - including newlines - is ignored):
2764    
2765           (?<date> (?<year>(\d\d)?\d\d) -           (?<date> (?<year>(\d\d)?\d\d) -
2766           (?<month>\d\d) - (?<day>\d\d) )           (?<month>\d\d) - (?<day>\d\d) )
2767    
2768         There are four named subpatterns, so the table has  four  entries,  and         There  are  four  named subpatterns, so the table has four entries, and
2769         each  entry  in the table is eight bytes long. The table is as follows,         each entry in the table is eight bytes long. The table is  as  follows,
2770         with non-printing bytes shows in hexadecimal, and undefined bytes shown         with non-printing bytes shows in hexadecimal, and undefined bytes shown
2771         as ??:         as ??:
2772    
# Line 2258  INFORMATION ABOUT A PATTERN Line 2775  INFORMATION ABOUT A PATTERN
2775           00 04 m  o  n  t  h  00           00 04 m  o  n  t  h  00
2776           00 02 y  e  a  r  00 ??           00 02 y  e  a  r  00 ??
2777    
2778         When  writing  code  to  extract  data from named subpatterns using the         When writing code to extract data  from  named  subpatterns  using  the
2779         name-to-number map, remember that the length of the entries  is  likely         name-to-number  map,  remember that the length of the entries is likely
2780         to be different for each compiled pattern.         to be different for each compiled pattern.
2781    
2782           PCRE_INFO_OKPARTIAL           PCRE_INFO_OKPARTIAL
2783    
2784         Return  1  if  the  pattern  can  be  used  for  partial  matching with         Return 1  if  the  pattern  can  be  used  for  partial  matching  with
2785         pcre_exec(), otherwise 0. The fourth argument should point  to  an  int         pcre_exec(),  otherwise  0.  The fourth argument should point to an int
2786         variable.  From  release  8.00,  this  always  returns  1,  because the         variable. From  release  8.00,  this  always  returns  1,  because  the
2787         restrictions that previously applied  to  partial  matching  have  been         restrictions  that  previously  applied  to  partial matching have been
2788         lifted.  The  pcrepartial documentation gives details of partial match-         lifted. The pcrepartial documentation gives details of  partial  match-
2789         ing.         ing.
2790    
2791           PCRE_INFO_OPTIONS           PCRE_INFO_OPTIONS
2792    
2793         Return a copy of the options with which the pattern was  compiled.  The         Return  a  copy of the options with which the pattern was compiled. The
2794         fourth  argument  should  point to an unsigned long int variable. These         fourth argument should point to an unsigned long  int  variable.  These
2795         option bits are those specified in the call to pcre_compile(), modified         option bits are those specified in the call to pcre_compile(), modified
2796         by any top-level option settings at the start of the pattern itself. In         by any top-level option settings at the start of the pattern itself. In
2797         other words, they are the options that will be in force  when  matching         other  words,  they are the options that will be in force when matching
2798         starts.  For  example, if the pattern /(?im)abc(?-i)d/ is compiled with         starts. For example, if the pattern /(?im)abc(?-i)d/ is  compiled  with
2799         the PCRE_EXTENDED option, the result is PCRE_CASELESS,  PCRE_MULTILINE,         the  PCRE_EXTENDED option, the result is PCRE_CASELESS, PCRE_MULTILINE,
2800         and PCRE_EXTENDED.         and PCRE_EXTENDED.
2801    
2802         A  pattern  is  automatically  anchored by PCRE if all of its top-level         A pattern is automatically anchored by PCRE if  all  of  its  top-level
2803         alternatives begin with one of the following:         alternatives begin with one of the following:
2804    
2805           ^     unless PCRE_MULTILINE is set           ^     unless PCRE_MULTILINE is set
# Line 2296  INFORMATION ABOUT A PATTERN Line 2813  INFORMATION ABOUT A PATTERN
2813    
2814           PCRE_INFO_SIZE           PCRE_INFO_SIZE
2815    
2816         Return  the size of the compiled pattern in bytes (for both libraries).         Return the size of the compiled pattern in bytes (for both  libraries).
2817         The fourth argument should point to a size_t variable. This value  does         The  fourth argument should point to a size_t variable. This value does
2818         not  include  the  size  of  the  pcre  structure  that  is returned by         not include the  size  of  the  pcre  structure  that  is  returned  by
2819         pcre_compile(). The value that is passed as the argument  to  pcre_mal-         pcre_compile().  The  value that is passed as the argument to pcre_mal-
2820         loc()  when pcre_compile() is getting memory in which to place the com-         loc() when pcre_compile() is getting memory in which to place the  com-
2821         piled data is the value returned by this option plus the  size  of  the         piled  data  is  the value returned by this option plus the size of the
2822         pcre  structure. Studying a compiled pattern, with or without JIT, does         pcre structure. Studying a compiled pattern, with or without JIT,  does
2823         not alter the value returned by this option.         not alter the value returned by this option.
2824    
2825           PCRE_INFO_STUDYSIZE           PCRE_INFO_STUDYSIZE
2826    
2827         Return the size in bytes of the data block pointed to by the study_data         Return the size in bytes of the data block pointed to by the study_data
2828         field  in  a  pcre_extra  block.  If pcre_extra is NULL, or there is no         field in a pcre_extra block. If pcre_extra is  NULL,  or  there  is  no
2829         study data, zero is returned. The fourth argument  should  point  to  a         study  data,  zero  is  returned. The fourth argument should point to a
2830         size_t  variable. The study_data field is set by pcre_study() to record         size_t variable. The study_data field is set by pcre_study() to  record
2831         information that will speed  up  matching  (see  the  section  entitled         information  that  will  speed  up  matching  (see the section entitled
2832         "Studying a pattern" above). The format of the study_data block is pri-         "Studying a pattern" above). The format of the study_data block is pri-
2833         vate, but its length is made available via this option so that  it  can         vate,  but  its length is made available via this option so that it can
2834         be  saved  and  restored  (see  the  pcreprecompile  documentation  for         be  saved  and  restored  (see  the  pcreprecompile  documentation  for
2835         details).         details).
2836    
2837             PCRE_INFO_FIRSTCHARACTERFLAGS
2838    
2839           Return information about the first data unit of any matched string, for
2840           a non-anchored pattern. The fourth argument  should  point  to  an  int
2841           variable.
2842    
2843           If  there  is  a  fixed first value, for example, the letter "c" from a
2844           pattern such as (cat|cow|coyote), 1  is  returned,  and  the  character
2845           value can be retrieved using PCRE_INFO_FIRSTCHARACTER.
2846    
2847           If there is no fixed first value, and if either
2848    
2849           (a)  the pattern was compiled with the PCRE_MULTILINE option, and every
2850           branch starts with "^", or
2851    
2852           (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2853           set (if it were set, the pattern would be anchored),
2854    
2855           2 is returned, indicating that the pattern matches only at the start of
2856           a subject string or after any newline within the string. Otherwise 0 is
2857           returned. For anchored patterns, 0 is returned.
2858    
2859             PCRE_INFO_FIRSTCHARACTER
2860    
2861           Return  the  fixed  first character value, if PCRE_INFO_FIRSTCHARACTER-
2862           FLAGS returned 1; otherwise returns 0. The fourth argument should point
2863           to an uint_t variable.
2864    
2865           In  the 8-bit library, the value is always less than 256. In the 16-bit
2866           library the value can be up to 0xffff. In the 32-bit library in  UTF-32
2867           mode  the  value  can  be up to 0x10ffff, and up to 0xffffffff when not
2868           using UTF-32 mode.
2869    
2870           If there is no fixed first value, and if either
2871    
2872           (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
2873           branch starts with "^", or
2874    
2875           (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2876           set (if it were set, the pattern would be anchored),
2877    
2878           -1 is returned, indicating that the pattern matches only at  the  start
2879           of  a  subject string or after any newline within the string. Otherwise
2880           -2 is returned. For anchored patterns, -2 is returned.
2881    
2882             PCRE_INFO_REQUIREDCHARFLAGS
2883    
2884           Returns 1 if there is a rightmost literal data unit that must exist  in
2885           any matched string, other than at its start. The fourth argument should
2886           point to an int variable. If there is no such value, 0 is returned.  If
2887           returning  1,  the  character  value  itself  can  be  retrieved  using
2888           PCRE_INFO_REQUIREDCHAR.
2889    
2890           For anchored patterns, a last literal value is recorded only if it fol-
2891           lows  something  of  variable  length.  For  example,  for  the pattern
2892           /^a\d+z\d+/  the   returned   value   1   (with   "z"   returned   from
2893           PCRE_INFO_REQUIREDCHAR), but for /^a\dz\d/ the returned value is 0.
2894    
2895             PCRE_INFO_REQUIREDCHAR
2896    
2897           Return  the value of the rightmost literal data unit that must exist in
2898           any matched string, other than at its start, if such a value  has  been
2899           recorded.  The fourth argument should point to an uint32_t variable. If
2900           there is no such value, 0 is returned.
2901    
2902    
2903  REFERENCE COUNTS  REFERENCE COUNTS
2904    
# Line 2398  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2980  MATCHING A PATTERN: THE TRADITIONAL FUNC
2980         In  the  16-bit  version  of  this  structure,  the mark field has type         In  the  16-bit  version  of  this  structure,  the mark field has type
2981         "PCRE_UCHAR16 **".         "PCRE_UCHAR16 **".
2982    
2983         The flags field is used to specify which of the other fields  are  set.         In the 32-bit version of  this  structure,  the  mark  field  has  type
2984           "PCRE_UCHAR32 **".
2985    
2986           The  flags  field is used to specify which of the other fields are set.
2987         The flag bits are:         The flag bits are:
2988    
2989           PCRE_EXTRA_CALLOUT_DATA           PCRE_EXTRA_CALLOUT_DATA
# Line 2409  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2994  MATCHING A PATTERN: THE TRADITIONAL FUNC
2994           PCRE_EXTRA_STUDY_DATA           PCRE_EXTRA_STUDY_DATA
2995           PCRE_EXTRA_TABLES           PCRE_EXTRA_TABLES
2996    
2997         Other  flag  bits should be set to zero. The study_data field and some-         Other flag bits should be set to zero. The study_data field  and  some-
2998         times the executable_jit field are set in the pcre_extra block that  is         times  the executable_jit field are set in the pcre_extra block that is
2999         returned  by pcre_study(), together with the appropriate flag bits. You         returned by pcre_study(), together with the appropriate flag bits.  You
3000         should not set these yourself, but you may add to the block by  setting         should  not set these yourself, but you may add to the block by setting
3001         other fields and their corresponding flag bits.         other fields and their corresponding flag bits.
3002    
3003         The match_limit field provides a means of preventing PCRE from using up         The match_limit field provides a means of preventing PCRE from using up
3004         a vast amount of resources when running patterns that are not going  to         a  vast amount of resources when running patterns that are not going to
3005         match,  but  which  have  a very large number of possibilities in their         match, but which have a very large number  of  possibilities  in  their
3006         search trees. The classic example is a pattern that uses nested  unlim-         search  trees. The classic example is a pattern that uses nested unlim-
3007         ited repeats.         ited repeats.
3008    
3009         Internally,  pcre_exec() uses a function called match(), which it calls         Internally, pcre_exec() uses a function called match(), which it  calls
3010         repeatedly (sometimes recursively). The limit  set  by  match_limit  is         repeatedly  (sometimes  recursively).  The  limit set by match_limit is
3011         imposed  on the number of times this function is called during a match,         imposed on the number of times this function is called during a  match,
3012         which has the effect of limiting the amount of  backtracking  that  can         which  has  the  effect of limiting the amount of backtracking that can
3013         take place. For patterns that are not anchored, the count restarts from         take place. For patterns that are not anchored, the count restarts from
3014         zero for each position in the subject string.         zero for each position in the subject string.
3015    
3016         When pcre_exec() is called with a pattern that was successfully studied         When pcre_exec() is called with a pattern that was successfully studied
3017         with  a  JIT  option, the way that the matching is executed is entirely         with a JIT option, the way that the matching is  executed  is  entirely
3018         different.  However, there is still the possibility of runaway matching         different.  However, there is still the possibility of runaway matching
3019         that goes on for a very long time, and so the match_limit value is also         that goes on for a very long time, and so the match_limit value is also
3020         used in this case (but in a different way) to limit how long the match-         used in this case (but in a different way) to limit how long the match-
3021         ing can continue.         ing can continue.
3022    
3023         The  default  value  for  the  limit can be set when PCRE is built; the         The default value for the limit can be set  when  PCRE  is  built;  the
3024         default default is 10 million, which handles all but the  most  extreme         default  default  is 10 million, which handles all but the most extreme
3025         cases.  You  can  override  the  default by suppling pcre_exec() with a         cases. You can override the default  by  suppling  pcre_exec()  with  a
3026         pcre_extra    block    in    which    match_limit    is    set,     and         pcre_extra     block    in    which    match_limit    is    set,    and
3027         PCRE_EXTRA_MATCH_LIMIT  is  set  in  the  flags  field. If the limit is         PCRE_EXTRA_MATCH_LIMIT is set in the  flags  field.  If  the  limit  is
3028         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
3029    
3030         The match_limit_recursion field is similar to match_limit, but  instead         The  match_limit_recursion field is similar to match_limit, but instead
3031         of limiting the total number of times that match() is called, it limits         of limiting the total number of times that match() is called, it limits
3032         the depth of recursion. The recursion depth is a  smaller  number  than         the  depth  of  recursion. The recursion depth is a smaller number than
3033         the  total number of calls, because not all calls to match() are recur-         the total number of calls, because not all calls to match() are  recur-
3034         sive.  This limit is of use only if it is set smaller than match_limit.         sive.  This limit is of use only if it is set smaller than match_limit.
3035    
3036         Limiting the recursion depth limits the amount of  machine  stack  that         Limiting  the  recursion  depth limits the amount of machine stack that
3037         can  be used, or, when PCRE has been compiled to use memory on the heap         can be used, or, when PCRE has been compiled to use memory on the  heap
3038         instead of the stack, the amount of heap memory that can be used.  This         instead  of the stack, the amount of heap memory that can be used. This
3039         limit  is not relevant, and is ignored, when matching is done using JIT         limit is not relevant, and is ignored, when matching is done using  JIT
3040         compiled code.         compiled code.
3041    
3042         The default value for match_limit_recursion can be  set  when  PCRE  is         The  default  value  for  match_limit_recursion can be set when PCRE is
3043         built;  the  default  default  is  the  same  value  as the default for         built; the default default  is  the  same  value  as  the  default  for
3044         match_limit. You can override the default by suppling pcre_exec()  with         match_limit.  You can override the default by suppling pcre_exec() with
3045         a   pcre_extra   block  in  which  match_limit_recursion  is  set,  and         a  pcre_extra  block  in  which  match_limit_recursion  is   set,   and
3046         PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in  the  flags  field.  If  the         PCRE_EXTRA_MATCH_LIMIT_RECURSION  is  set  in  the  flags field. If the
3047         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.
3048    
3049         The  callout_data  field is used in conjunction with the "callout" fea-         The callout_data field is used in conjunction with the  "callout"  fea-
3050         ture, and is described in the pcrecallout documentation.         ture, and is described in the pcrecallout documentation.
3051    
3052         The tables field  is  used  to  pass  a  character  tables  pointer  to         The  tables  field  is  used  to  pass  a  character  tables pointer to
3053         pcre_exec();  this overrides the value that is stored with the compiled         pcre_exec(); this overrides the value that is stored with the  compiled
3054         pattern. A non-NULL value is stored with the compiled pattern  only  if         pattern.  A  non-NULL value is stored with the compiled pattern only if
3055         custom  tables  were  supplied to pcre_compile() via its tableptr argu-         custom tables were supplied to pcre_compile() via  its  tableptr  argu-
3056         ment.  If NULL is passed to pcre_exec() using this mechanism, it forces         ment.  If NULL is passed to pcre_exec() using this mechanism, it forces
3057         PCRE's  internal  tables  to be used. This facility is helpful when re-         PCRE's internal tables to be used. This facility is  helpful  when  re-
3058         using patterns that have been saved after compiling  with  an  external         using  patterns  that  have been saved after compiling with an external
3059         set  of  tables,  because  the  external tables might be at a different         set of tables, because the external tables  might  be  at  a  different
3060         address when pcre_exec() is called. See the  pcreprecompile  documenta-         address  when  pcre_exec() is called. See the pcreprecompile documenta-
3061         tion for a discussion of saving compiled patterns for later use.         tion for a discussion of saving compiled patterns for later use.
3062    
3063         If  PCRE_EXTRA_MARK  is  set in the flags field, the mark field must be         If PCRE_EXTRA_MARK is set in the flags field, the mark  field  must  be
3064         set to point to a suitable variable. If the pattern contains any  back-         set  to point to a suitable variable. If the pattern contains any back-
3065         tracking  control verbs such as (*MARK:NAME), and the execution ends up         tracking control verbs such as (*MARK:NAME), and the execution ends  up
3066         with a name to pass back, a pointer to the  name  string  (zero  termi-         with  a  name  to  pass back, a pointer to the name string (zero termi-
3067         nated)  is  placed  in  the  variable pointed to by the mark field. The         nated) is placed in the variable pointed to  by  the  mark  field.  The
3068         names are within the compiled pattern; if you wish  to  retain  such  a         names  are  within  the  compiled pattern; if you wish to retain such a
3069         name  you must copy it before freeing the memory of a compiled pattern.         name you must copy it before freeing the memory of a compiled  pattern.
3070         If there is no name to pass back, the variable pointed to by  the  mark         If  there  is no name to pass back, the variable pointed to by the mark
3071         field  is  set  to NULL. For details of the backtracking control verbs,         field is set to NULL. For details of the  backtracking  control  verbs,
3072         see the section entitled "Backtracking control" in the pcrepattern doc-         see the section entitled "Backtracking control" in the pcrepattern doc-
3073         umentation.         umentation.
3074    
3075     Option bits for pcre_exec()     Option bits for pcre_exec()
3076    
3077         The  unused  bits of the options argument for pcre_exec() must be zero.         The unused bits of the options argument for pcre_exec() must  be  zero.
3078         The only bits that may  be  set  are  PCRE_ANCHORED,  PCRE_NEWLINE_xxx,         The  only  bits  that  may  be set are PCRE_ANCHORED, PCRE_NEWLINE_xxx,
3079         PCRE_NOTBOL,    PCRE_NOTEOL,    PCRE_NOTEMPTY,   PCRE_NOTEMPTY_ATSTART,         PCRE_NOTBOL,   PCRE_NOTEOL,    PCRE_NOTEMPTY,    PCRE_NOTEMPTY_ATSTART,
3080         PCRE_NO_START_OPTIMIZE,  PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_HARD,   and         PCRE_NO_START_OPTIMIZE,   PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_HARD,  and
3081         PCRE_PARTIAL_SOFT.         PCRE_PARTIAL_SOFT.
3082    
3083         If  the  pattern  was successfully studied with one of the just-in-time         If the pattern was successfully studied with one  of  the  just-in-time
3084         (JIT) compile options, the only supported options for JIT execution are         (JIT) compile options, the only supported options for JIT execution are
3085         PCRE_NO_UTF8_CHECK,     PCRE_NOTBOL,     PCRE_NOTEOL,    PCRE_NOTEMPTY,         PCRE_NO_UTF8_CHECK,    PCRE_NOTBOL,     PCRE_NOTEOL,     PCRE_NOTEMPTY,
3086         PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If  an         PCRE_NOTEMPTY_ATSTART,  PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an
3087         unsupported  option  is  used, JIT execution is disabled and the normal         unsupported option is used, JIT execution is disabled  and  the  normal
3088         interpretive code in pcre_exec() is run.         interpretive code in pcre_exec() is run.
3089    
3090           PCRE_ANCHORED           PCRE_ANCHORED
3091    
3092         The PCRE_ANCHORED option limits pcre_exec() to matching  at  the  first         The  PCRE_ANCHORED  option  limits pcre_exec() to matching at the first
3093         matching  position.  If  a  pattern was compiled with PCRE_ANCHORED, or         matching position. If a pattern was  compiled  with  PCRE_ANCHORED,  or
3094         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
3095         unachored at matching time.         unachored at matching time.
3096    
3097           PCRE_BSR_ANYCRLF           PCRE_BSR_ANYCRLF
3098           PCRE_BSR_UNICODE           PCRE_BSR_UNICODE
3099    
3100         These options (which are mutually exclusive) control what the \R escape         These options (which are mutually exclusive) control what the \R escape
3101         sequence matches. The choice is either to match only CR, LF,  or  CRLF,         sequence  matches.  The choice is either to match only CR, LF, or CRLF,
3102         or  to  match  any Unicode newline sequence. These options override the         or to match any Unicode newline sequence. These  options  override  the
3103         choice that was made or defaulted when the pattern was compiled.         choice that was made or defaulted when the pattern was compiled.
3104    
3105           PCRE_NEWLINE_CR           PCRE_NEWLINE_CR
# Line 2523  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3108  MATCHING A PATTERN: THE TRADITIONAL FUNC
3108           PCRE_NEWLINE_ANYCRLF           PCRE_NEWLINE_ANYCRLF
3109           PCRE_NEWLINE_ANY           PCRE_NEWLINE_ANY
3110    
3111         These options override  the  newline  definition  that  was  chosen  or         These  options  override  the  newline  definition  that  was chosen or
3112         defaulted  when the pattern was compiled. For details, see the descrip-         defaulted when the pattern was compiled. For details, see the  descrip-
3113         tion of pcre_compile()  above.  During  matching,  the  newline  choice         tion  of  pcre_compile()  above.  During  matching,  the newline choice
3114         affects  the  behaviour  of the dot, circumflex, and dollar metacharac-         affects the behaviour of the dot, circumflex,  and  dollar  metacharac-
3115         ters. It may also alter the way the match position is advanced after  a         ters.  It may also alter the way the match position is advanced after a
3116         match failure for an unanchored pattern.         match failure for an unanchored pattern.
3117    
3118         When  PCRE_NEWLINE_CRLF,  PCRE_NEWLINE_ANYCRLF,  or PCRE_NEWLINE_ANY is         When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF,  or  PCRE_NEWLINE_ANY  is
3119         set, and a match attempt for an unanchored pattern fails when the  cur-         set,  and a match attempt for an unanchored pattern fails when the cur-
3120         rent  position  is  at  a  CRLF  sequence,  and the pattern contains no         rent position is at a  CRLF  sequence,  and  the  pattern  contains  no
3121         explicit matches for  CR  or  LF  characters,  the  match  position  is         explicit  matches  for  CR  or  LF  characters,  the  match position is
3122         advanced by two characters instead of one, in other words, to after the         advanced by two characters instead of one, in other words, to after the
3123         CRLF.         CRLF.
3124    
3125         The above rule is a compromise that makes the most common cases work as         The above rule is a compromise that makes the most common cases work as
3126         expected.  For  example,  if  the  pattern  is .+A (and the PCRE_DOTALL         expected. For example, if the  pattern  is  .+A  (and  the  PCRE_DOTALL
3127         option is not set), it does not match the string "\r\nA" because, after         option is not set), it does not match the string "\r\nA" because, after
3128         failing  at the start, it skips both the CR and the LF before retrying.         failing at the start, it skips both the CR and the LF before  retrying.
3129         However, the pattern [\r\n]A does match that string,  because  it  con-         However,  the  pattern  [\r\n]A does match that string, because it con-
3130         tains an explicit CR or LF reference, and so advances only by one char-         tains an explicit CR or LF reference, and so advances only by one char-
3131         acter after the first failure.         acter after the first failure.
3132    
3133         An explicit match for CR of LF is either a literal appearance of one of         An explicit match for CR of LF is either a literal appearance of one of
3134         those  characters,  or  one  of the \r or \n escape sequences. Implicit         those characters, or one of the \r or  \n  escape  sequences.  Implicit
3135         matches such as [^X] do not count, nor does \s (which includes  CR  and         matches  such  as [^X] do not count, nor does \s (which includes CR and
3136         LF in the characters that it matches).         LF in the characters that it matches).
3137    
3138         Notwithstanding  the above, anomalous effects may still occur when CRLF         Notwithstanding the above, anomalous effects may still occur when  CRLF
3139         is a valid newline sequence and explicit \r or \n escapes appear in the         is a valid newline sequence and explicit \r or \n escapes appear in the
3140         pattern.         pattern.
3141    
3142           PCRE_NOTBOL           PCRE_NOTBOL
3143    
3144         This option specifies that first character of the subject string is not         This option specifies that first character of the subject string is not
3145         the beginning of a line, so the  circumflex  metacharacter  should  not         the  beginning  of  a  line, so the circumflex metacharacter should not
3146         match  before it. Setting this without PCRE_MULTILINE (at compile time)         match before it. Setting this without PCRE_MULTILINE (at compile  time)
3147         causes circumflex never to match. This option affects only  the  behav-         causes  circumflex  never to match. This option affects only the behav-
3148         iour of the circumflex metacharacter. It does not affect \A.         iour of the circumflex metacharacter. It does not affect \A.
3149    
3150           PCRE_NOTEOL           PCRE_NOTEOL
3151    
3152         This option specifies that the end of the subject string is not the end         This option specifies that the end of the subject string is not the end
3153         of a line, so the dollar metacharacter should not match it nor  (except         of  a line, so the dollar metacharacter should not match it nor (except
3154         in  multiline mode) a newline immediately before it. Setting this with-         in multiline mode) a newline immediately before it. Setting this  with-
3155         out PCRE_MULTILINE (at compile time) causes dollar never to match. This         out PCRE_MULTILINE (at compile time) causes dollar never to match. This
3156         option  affects only the behaviour of the dollar metacharacter. It does         option affects only the behaviour of the dollar metacharacter. It  does
3157         not affect \Z or \z.         not affect \Z or \z.
3158    
3159           PCRE_NOTEMPTY           PCRE_NOTEMPTY
3160    
3161         An empty string is not considered to be a valid match if this option is         An empty string is not considered to be a valid match if this option is
3162         set.  If  there are alternatives in the pattern, they are tried. If all         set. If there are alternatives in the pattern, they are tried.  If  all
3163         the alternatives match the empty string, the entire  match  fails.  For         the  alternatives  match  the empty string, the entire match fails. For
3164         example, if the pattern         example, if the pattern
3165    
3166           a?b?           a?b?
3167    
3168         is  applied  to  a  string not beginning with "a" or "b", it matches an         is applied to a string not beginning with "a" or  "b",  it  matches  an
3169         empty string at the start of the subject. With PCRE_NOTEMPTY set,  this         empty  string at the start of the subject. With PCRE_NOTEMPTY set, this
3170         match is not valid, so PCRE searches further into the string for occur-         match is not valid, so PCRE searches further into the string for occur-
3171         rences of "a" or "b".         rences of "a" or "b".
3172    
3173           PCRE_NOTEMPTY_ATSTART           PCRE_NOTEMPTY_ATSTART
3174    
3175         This is like PCRE_NOTEMPTY, except that an empty string match  that  is         This  is  like PCRE_NOTEMPTY, except that an empty string match that is
3176         not  at  the  start  of  the  subject  is  permitted. If the pattern is         not at the start of  the  subject  is  permitted.  If  the  pattern  is
3177         anchored, such a match can occur only if the pattern contains \K.         anchored, such a match can occur only if the pattern contains \K.
3178    
3179         Perl    has    no    direct    equivalent    of    PCRE_NOTEMPTY     or         Perl     has    no    direct    equivalent    of    PCRE_NOTEMPTY    or
3180         PCRE_NOTEMPTY_ATSTART,  but  it  does  make a special case of a pattern         PCRE_NOTEMPTY_ATSTART, but it does make a special  case  of  a  pattern
3181         match of the empty string within its split() function, and  when  using         match  of  the empty string within its split() function, and when using
3182         the  /g  modifier.  It  is  possible  to emulate Perl's behaviour after         the /g modifier. It is  possible  to  emulate  Perl's  behaviour  after
3183         matching a null string by first trying the match again at the same off-         matching a null string by first trying the match again at the same off-
3184         set  with  PCRE_NOTEMPTY_ATSTART  and  PCRE_ANCHORED,  and then if that         set with PCRE_NOTEMPTY_ATSTART and  PCRE_ANCHORED,  and  then  if  that
3185         fails, by advancing the starting offset (see below) and trying an ordi-         fails, by advancing the starting offset (see below) and trying an ordi-
3186         nary  match  again. There is some code that demonstrates how to do this         nary match again. There is some code that demonstrates how to  do  this
3187         in the pcredemo sample program. In the most general case, you  have  to         in  the  pcredemo sample program. In the most general case, you have to
3188         check  to  see  if the newline convention recognizes CRLF as a newline,         check to see if the newline convention recognizes CRLF  as  a  newline,
3189         and if so, and the current character is CR followed by LF, advance  the         and  if so, and the current character is CR followed by LF, advance the
3190         starting offset by two characters instead of one.         starting offset by two characters instead of one.
3191    
3192           PCRE_NO_START_OPTIMIZE           PCRE_NO_START_OPTIMIZE
3193    
3194         There  are a number of optimizations that pcre_exec() uses at the start         There are a number of optimizations that pcre_exec() uses at the  start
3195         of a match, in order to speed up the process. For  example,  if  it  is         of  a  match,  in  order to speed up the process. For example, if it is
3196         known that an unanchored match must start with a specific character, it         known that an unanchored match must start with a specific character, it
3197         searches the subject for that character, and fails  immediately  if  it         searches  the  subject  for that character, and fails immediately if it
3198         cannot  find  it,  without actually running the main matching function.         cannot find it, without actually running the  main  matching  function.
3199         This means that a special item such as (*COMMIT) at the start of a pat-         This means that a special item such as (*COMMIT) at the start of a pat-
3200         tern  is  not  considered until after a suitable starting point for the         tern is not considered until after a suitable starting  point  for  the
3201         match has been found. When callouts or (*MARK) items are in use,  these         match  has been found. When callouts or (*MARK) items are in use, these
3202         "start-up" optimizations can cause them to be skipped if the pattern is         "start-up" optimizations can cause them to be skipped if the pattern is
3203         never actually used. The start-up optimizations are in  effect  a  pre-         never  actually  used.  The start-up optimizations are in effect a pre-
3204         scan of the subject that takes place before the pattern is run.         scan of the subject that takes place before the pattern is run.
3205    
3206         The  PCRE_NO_START_OPTIMIZE option disables the start-up optimizations,         The PCRE_NO_START_OPTIMIZE option disables the start-up  optimizations,
3207         possibly causing performance to suffer,  but  ensuring  that  in  cases         possibly  causing  performance  to  suffer,  but ensuring that in cases
3208         where  the  result is "no match", the callouts do occur, and that items         where the result is "no match", the callouts do occur, and  that  items
3209         such as (*COMMIT) and (*MARK) are considered at every possible starting         such as (*COMMIT) and (*MARK) are considered at every possible starting
3210         position  in  the  subject  string. If PCRE_NO_START_OPTIMIZE is set at         position in the subject string. If  PCRE_NO_START_OPTIMIZE  is  set  at
3211         compile time,  it  cannot  be  unset  at  matching  time.  The  use  of         compile  time,  it  cannot  be  unset  at  matching  time.  The  use of
3212         PCRE_NO_START_OPTIMIZE disables JIT execution; when it is set, matching         PCRE_NO_START_OPTIMIZE disables JIT execution; when it is set, matching
3213         is always done using interpretively.         is always done using interpretively.
3214    
3215         Setting PCRE_NO_START_OPTIMIZE can change the  outcome  of  a  matching         Setting  PCRE_NO_START_OPTIMIZE  can  change  the outcome of a matching
3216         operation.  Consider the pattern         operation.  Consider the pattern
3217    
3218           (*COMMIT)ABC           (*COMMIT)ABC
3219    
3220         When  this  is  compiled, PCRE records the fact that a match must start         When this is compiled, PCRE records the fact that a  match  must  start
3221         with the character "A". Suppose the subject  string  is  "DEFABC".  The         with  the  character  "A".  Suppose the subject string is "DEFABC". The
3222         start-up  optimization  scans along the subject, finds "A" and runs the         start-up optimization scans along the subject, finds "A" and  runs  the
3223         first match attempt from there. The (*COMMIT) item means that the  pat-         first  match attempt from there. The (*COMMIT) item means that the pat-
3224         tern  must  match the current starting position, which in this case, it         tern must match the current starting position, which in this  case,  it
3225         does. However, if the same match  is  run  with  PCRE_NO_START_OPTIMIZE         does.  However,  if  the  same match is run with PCRE_NO_START_OPTIMIZE
3226         set,  the  initial  scan  along the subject string does not happen. The         set, the initial scan along the subject string  does  not  happen.  The
3227         first match attempt is run starting  from  "D"  and  when  this  fails,         first  match  attempt  is  run  starting  from "D" and when this fails,
3228         (*COMMIT)  prevents  any  further  matches  being tried, so the overall         (*COMMIT) prevents any further matches  being  tried,  so  the  overall
3229         result is "no match". If the pattern is studied,  more  start-up  opti-         result  is  "no  match". If the pattern is studied, more start-up opti-
3230         mizations  may  be  used. For example, a minimum length for the subject         mizations may be used. For example, a minimum length  for  the  subject
3231         may be recorded. Consider the pattern         may be recorded. Consider the pattern
3232    
3233           (*MARK:A)(X|Y)           (*MARK:A)(X|Y)
3234    
3235         The minimum length for a match is one  character.  If  the  subject  is         The  minimum  length  for  a  match is one character. If the subject is
3236         "ABC",  there  will  be  attempts  to  match "ABC", "BC", "C", and then         "ABC", there will be attempts to  match  "ABC",  "BC",  "C",  and  then
3237         finally an empty string.  If the pattern is studied, the final  attempt         finally  an empty string.  If the pattern is studied, the final attempt
3238         does  not take place, because PCRE knows that the subject is too short,         does not take place, because PCRE knows that the subject is too  short,
3239         and so the (*MARK) is never encountered.  In this  case,  studying  the         and  so  the  (*MARK) is never encountered.  In this case, studying the
3240         pattern  does  not  affect the overall match result, which is still "no         pattern does not affect the overall match result, which  is  still  "no
3241         match", but it does affect the auxiliary information that is returned.         match", but it does affect the auxiliary information that is returned.
3242    
3243           PCRE_NO_UTF8_CHECK           PCRE_NO_UTF8_CHECK
3244    
3245         When PCRE_UTF8 is set at compile time, the validity of the subject as a         When PCRE_UTF8 is set at compile time, the validity of the subject as a
3246         UTF-8  string is automatically checked when pcre_exec() is subsequently         UTF-8 string is automatically checked when pcre_exec() is  subsequently
3247         called.  The entire string is checked before any other processing takes         called.  The entire string is checked before any other processing takes
3248         place.  The  value  of  startoffset  is  also checked to ensure that it         place. The value of startoffset is  also  checked  to  ensure  that  it
3249         points to the start of a UTF-8 character. There is a  discussion  about         points  to  the start of a UTF-8 character. There is a discussion about
3250         the  validity  of  UTF-8 strings in the pcreunicode page. If an invalid         the validity of UTF-8 strings in the pcreunicode page.  If  an  invalid
3251         sequence  of  bytes   is   found,   pcre_exec()   returns   the   error         sequence   of   bytes   is   found,   pcre_exec()   returns  the  error
3252         PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a         PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a
3253         truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In         truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
3254         both  cases, information about the precise nature of the error may also         both cases, information about the precise nature of the error may  also
3255         be returned (see the descriptions of these errors in the section  enti-         be  returned (see the descriptions of these errors in the section enti-
3256         tled  Error return values from pcre_exec() below).  If startoffset con-         tled Error return values from pcre_exec() below).  If startoffset  con-
3257         tains a value that does not point to the start of a UTF-8 character (or         tains a value that does not point to the start of a UTF-8 character (or
3258         to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is returned.         to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is returned.
3259    
3260         If  you  already  know that your subject is valid, and you want to skip         If you already know that your subject is valid, and you  want  to  skip
3261         these   checks   for   performance   reasons,   you   can    set    the         these    checks    for   performance   reasons,   you   can   set   the
3262         PCRE_NO_UTF8_CHECK  option  when calling pcre_exec(). You might want to         PCRE_NO_UTF8_CHECK option when calling pcre_exec(). You might  want  to
3263         do this for the second and subsequent calls to pcre_exec() if  you  are         do  this  for the second and subsequent calls to pcre_exec() if you are
3264         making  repeated  calls  to  find  all  the matches in a single subject         making repeated calls to find all  the  matches  in  a  single  subject
3265         string. However, you should be  sure  that  the  value  of  startoffset         string.  However,  you  should  be  sure  that the value of startoffset
3266         points  to  the  start of a character (or the end of the subject). When         points to the start of a character (or the end of  the  subject).  When
3267         PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid string as a         PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid string as a
3268         subject  or  an invalid value of startoffset is undefined. Your program         subject or an invalid value of startoffset is undefined.  Your  program
3269         may crash.         may crash.
3270    
3271           PCRE_PARTIAL_HARD           PCRE_PARTIAL_HARD
3272           PCRE_PARTIAL_SOFT           PCRE_PARTIAL_SOFT
3273    
3274         These options turn on the partial matching feature. For backwards  com-         These  options turn on the partial matching feature. For backwards com-
3275         patibility,  PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial         patibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A  partial
3276         match occurs if the end of the subject string is reached  successfully,         match  occurs if the end of the subject string is reached successfully,
3277         but  there  are not enough subject characters to complete the match. If         but there are not enough subject characters to complete the  match.  If
3278         this happens when PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set,         this happens when PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set,
3279         matching  continues  by  testing any remaining alternatives. Only if no         matching continues by testing any remaining alternatives.  Only  if  no
3280         complete match can be found is PCRE_ERROR_PARTIAL returned  instead  of         complete  match  can be found is PCRE_ERROR_PARTIAL returned instead of
3281         PCRE_ERROR_NOMATCH.  In  other  words,  PCRE_PARTIAL_SOFT says that the         PCRE_ERROR_NOMATCH. In other words,  PCRE_PARTIAL_SOFT  says  that  the
3282         caller is prepared to handle a partial match, but only if  no  complete         caller  is  prepared to handle a partial match, but only if no complete
3283         match can be found.         match can be found.
3284    
3285         If  PCRE_PARTIAL_HARD  is  set, it overrides PCRE_PARTIAL_SOFT. In this         If PCRE_PARTIAL_HARD is set, it overrides  PCRE_PARTIAL_SOFT.  In  this
3286         case, if a partial match  is  found,  pcre_exec()  immediately  returns         case,  if  a  partial  match  is found, pcre_exec() immediately returns
3287         PCRE_ERROR_PARTIAL,  without  considering  any  other  alternatives. In         PCRE_ERROR_PARTIAL, without  considering  any  other  alternatives.  In
3288         other words, when PCRE_PARTIAL_HARD is set, a partial match is  consid-         other  words, when PCRE_PARTIAL_HARD is set, a partial match is consid-
3289         ered to be more important that an alternative complete match.         ered to be more important that an alternative complete match.
3290    
3291         In  both  cases,  the portion of the string that was inspected when the         In both cases, the portion of the string that was  inspected  when  the
3292         partial match was found is set as the first matching string. There is a         partial match was found is set as the first matching string. There is a
3293         more  detailed  discussion  of partial and multi-segment matching, with         more detailed discussion of partial and  multi-segment  matching,  with
3294         examples, in the pcrepartial documentation.         examples, in the pcrepartial documentation.
3295    
3296     The string to be matched by pcre_exec()     The string to be matched by pcre_exec()
3297    
3298         The subject string is passed to pcre_exec() as a pointer in subject,  a         The  subject string is passed to pcre_exec() as a pointer in subject, a
3299         length  in  bytes in length, and a starting byte offset in startoffset.         length in bytes in length, and a starting byte offset  in  startoffset.
3300         If this is  negative  or  greater  than  the  length  of  the  subject,         If  this  is  negative  or  greater  than  the  length  of the subject,
3301         pcre_exec()  returns  PCRE_ERROR_BADOFFSET. When the starting offset is         pcre_exec() returns PCRE_ERROR_BADOFFSET. When the starting  offset  is
3302         zero, the search for a match starts at the beginning  of  the  subject,         zero,  the  search  for a match starts at the beginning of the subject,
3303         and this is by far the most common case. In UTF-8 mode, the byte offset         and this is by far the most common case. In UTF-8 mode, the byte offset
3304         must point to the start of a UTF-8 character (or the end  of  the  sub-         must  point  to  the start of a UTF-8 character (or the end of the sub-
3305         ject).  Unlike  the pattern string, the subject may contain binary zero         ject). Unlike the pattern string, the subject may contain  binary  zero
3306         bytes.         bytes.
3307    
3308         A non-zero starting offset is useful when searching for  another  match         A  non-zero  starting offset is useful when searching for another match
3309         in  the same subject by calling pcre_exec() again after a previous suc-         in the same subject by calling pcre_exec() again after a previous  suc-
3310         cess.  Setting startoffset differs from just passing over  a  shortened         cess.   Setting  startoffset differs from just passing over a shortened
3311         string  and  setting  PCRE_NOTBOL  in the case of a pattern that begins         string and setting PCRE_NOTBOL in the case of  a  pattern  that  begins
3312         with any kind of lookbehind. For example, consider the pattern         with any kind of lookbehind. For example, consider the pattern
3313    
3314           \Biss\B           \Biss\B
3315    
3316         which finds occurrences of "iss" in the middle of  words.  (\B  matches         which  finds  occurrences  of "iss" in the middle of words. (\B matches
3317         only  if  the  current position in the subject is not a word boundary.)         only if the current position in the subject is not  a  word  boundary.)
3318         When applied to the string "Mississipi" the first call  to  pcre_exec()         When  applied  to the string "Mississipi" the first call to pcre_exec()
3319         finds  the  first  occurrence. If pcre_exec() is called again with just         finds the first occurrence. If pcre_exec() is called  again  with  just
3320         the remainder of the subject,  namely  "issipi",  it  does  not  match,         the  remainder  of  the  subject,  namely  "issipi", it does not match,
3321         because \B is always false at the start of the subject, which is deemed         because \B is always false at the start of the subject, which is deemed
3322         to be a word boundary. However, if pcre_exec()  is  passed  the  entire         to  be  a  word  boundary. However, if pcre_exec() is passed the entire
3323         string again, but with startoffset set to 4, it finds the second occur-         string again, but with startoffset set to 4, it finds the second occur-
3324         rence of "iss" because it is able to look behind the starting point  to         rence  of "iss" because it is able to look behind the starting point to
3325         discover that it is preceded by a letter.         discover that it is preceded by a letter.
3326    
3327         Finding  all  the  matches  in a subject is tricky when the pattern can         Finding all the matches in a subject is tricky  when  the  pattern  can
3328         match an empty string. It is possible to emulate Perl's /g behaviour by         match an empty string. It is possible to emulate Perl's /g behaviour by
3329         first   trying   the   match   again  at  the  same  offset,  with  the         first  trying  the  match  again  at  the   same   offset,   with   the
3330         PCRE_NOTEMPTY_ATSTART and  PCRE_ANCHORED  options,  and  then  if  that         PCRE_NOTEMPTY_ATSTART  and  PCRE_ANCHORED  options,  and  then  if that
3331         fails,  advancing  the  starting  offset  and  trying an ordinary match         fails, advancing the starting  offset  and  trying  an  ordinary  match
3332         again. There is some code that demonstrates how to do this in the pcre-         again. There is some code that demonstrates how to do this in the pcre-
3333         demo sample program. In the most general case, you have to check to see         demo sample program. In the most general case, you have to check to see
3334         if the newline convention recognizes CRLF as a newline, and if so,  and         if  the newline convention recognizes CRLF as a newline, and if so, and
3335         the current character is CR followed by LF, advance the starting offset         the current character is CR followed by LF, advance the starting offset
3336         by two characters instead of one.         by two characters instead of one.
3337    
3338         If a non-zero starting offset is passed when the pattern  is  anchored,         If  a  non-zero starting offset is passed when the pattern is anchored,
3339         one attempt to match at the given offset is made. This can only succeed         one attempt to match at the given offset is made. This can only succeed
3340         if the pattern does not require the match to be at  the  start  of  the         if  the  pattern  does  not require the match to be at the start of the
3341         subject.         subject.
3342    
3343     How pcre_exec() returns captured substrings     How pcre_exec() returns captured substrings
3344    
3345         In  general, a pattern matches a certain portion of the subject, and in         In general, a pattern matches a certain portion of the subject, and  in
3346         addition, further substrings from the subject  may  be  picked  out  by         addition,  further  substrings  from  the  subject may be picked out by
3347         parts  of  the  pattern.  Following the usage in Jeffrey Friedl's book,         parts of the pattern. Following the usage  in  Jeffrey  Friedl's  book,
3348         this is called "capturing" in what follows, and the  phrase  "capturing         this  is  called "capturing" in what follows, and the phrase "capturing
3349         subpattern"  is  used for a fragment of a pattern that picks out a sub-         subpattern" is used for a fragment of a pattern that picks out  a  sub-
3350         string. PCRE supports several other kinds of  parenthesized  subpattern         string.  PCRE  supports several other kinds of parenthesized subpattern
3351         that do not cause substrings to be captured.         that do not cause substrings to be captured.
3352    
3353         Captured substrings are returned to the caller via a vector of integers         Captured substrings are returned to the caller via a vector of integers
3354         whose address is passed in ovector. The number of elements in the  vec-         whose  address is passed in ovector. The number of elements in the vec-
3355         tor  is  passed in ovecsize, which must be a non-negative number. Note:         tor is passed in ovecsize, which must be a non-negative  number.  Note:
3356         this argument is NOT the size of ovector in bytes.         this argument is NOT the size of ovector in bytes.
3357    
3358         The first two-thirds of the vector is used to pass back  captured  sub-         The  first  two-thirds of the vector is used to pass back captured sub-
3359         strings,  each  substring using a pair of integers. The remaining third         strings, each substring using a pair of integers. The  remaining  third
3360         of the vector is used as workspace by pcre_exec() while  matching  cap-         of  the  vector is used as workspace by pcre_exec() while matching cap-
3361         turing  subpatterns, and is not available for passing back information.         turing subpatterns, and is not available for passing back  information.
3362         The number passed in ovecsize should always be a multiple of three.  If         The  number passed in ovecsize should always be a multiple of three. If
3363         it is not, it is rounded down.         it is not, it is rounded down.
3364    
3365         When  a  match  is successful, information about captured substrings is         When a match is successful, information about  captured  substrings  is
3366         returned in pairs of integers, starting at the  beginning  of  ovector,         returned  in  pairs  of integers, starting at the beginning of ovector,
3367         and  continuing  up  to two-thirds of its length at the most. The first         and continuing up to two-thirds of its length at the  most.  The  first
3368         element of each pair is set to the byte offset of the  first  character         element  of  each pair is set to the byte offset of the first character
3369         in  a  substring, and the second is set to the byte offset of the first         in a substring, and the second is set to the byte offset of  the  first
3370         character after the end of a substring. Note: these values  are  always         character  after  the end of a substring. Note: these values are always
3371         byte offsets, even in UTF-8 mode. They are not character counts.         byte offsets, even in UTF-8 mode. They are not character counts.
3372    
3373         The  first  pair  of  integers, ovector[0] and ovector[1], identify the         The first pair of integers, ovector[0]  and  ovector[1],  identify  the
3374         portion of the subject string matched by the entire pattern.  The  next         portion  of  the subject string matched by the entire pattern. The next
3375         pair  is  used for the first capturing subpattern, and so on. The value         pair is used for the first capturing subpattern, and so on.  The  value
3376         returned by pcre_exec() is one more than the highest numbered pair that         returned by pcre_exec() is one more than the highest numbered pair that
3377         has  been  set.  For example, if two substrings have been captured, the         has been set.  For example, if two substrings have been  captured,  the
3378         returned value is 3. If there are no capturing subpatterns, the  return         returned  value is 3. If there are no capturing subpatterns, the return
3379         value from a successful match is 1, indicating that just the first pair         value from a successful match is 1, indicating that just the first pair
3380         of offsets has been set.         of offsets has been set.
3381    
3382         If a capturing subpattern is matched repeatedly, it is the last portion         If a capturing subpattern is matched repeatedly, it is the last portion
3383         of the string that it matched that is returned.         of the string that it matched that is returned.
3384    
3385         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,
3386         it is used as far as possible (up to two-thirds of its length), and the         it is used as far as possible (up to two-thirds of its length), and the
3387         function  returns a value of zero. If neither the actual string matched         function returns a value of zero. If neither the actual string  matched
3388         nor any captured substrings are of interest, pcre_exec() may be  called         nor  any captured substrings are of interest, pcre_exec() may be called
3389         with  ovector passed as NULL and ovecsize as zero. However, if the pat-         with ovector passed as NULL and ovecsize as zero. However, if the  pat-
3390         tern contains back references and the ovector  is  not  big  enough  to         tern  contains  back  references  and  the ovector is not big enough to
3391         remember  the related substrings, PCRE has to get additional memory for         remember the related substrings, PCRE has to get additional memory  for
3392         use during matching. Thus it is usually advisable to supply an  ovector         use  during matching. Thus it is usually advisable to supply an ovector
3393         of reasonable size.         of reasonable size.
3394    
3395         There  are  some  cases where zero is returned (indicating vector over-         There are some cases where zero is returned  (indicating  vector  over-
3396         flow) when in fact the vector is exactly the right size for  the  final         flow)  when  in fact the vector is exactly the right size for the final
3397         match. For example, consider the pattern         match. For example, consider the pattern
3398    
3399           (a)(?:(b)c|bd)           (a)(?:(b)c|bd)
3400    
3401         If  a  vector of 6 elements (allowing for only 1 captured substring) is         If a vector of 6 elements (allowing for only 1 captured  substring)  is
3402         given with subject string "abd", pcre_exec() will try to set the second         given with subject string "abd", pcre_exec() will try to set the second
3403         captured string, thereby recording a vector overflow, before failing to         captured string, thereby recording a vector overflow, before failing to
3404         match "c" and backing up  to  try  the  second  alternative.  The  zero         match  "c"  and  backing  up  to  try  the second alternative. The zero
3405         return,  however,  does  correctly  indicate that the maximum number of         return, however, does correctly indicate that  the  maximum  number  of
3406         slots (namely 2) have been filled. In similar cases where there is tem-         slots (namely 2) have been filled. In similar cases where there is tem-
3407         porary  overflow,  but  the final number of used slots is actually less         porary overflow, but the final number of used slots  is  actually  less
3408         than the maximum, a non-zero value is returned.         than the maximum, a non-zero value is returned.
3409    
3410         The pcre_fullinfo() function can be used to find out how many capturing         The pcre_fullinfo() function can be used to find out how many capturing
3411         subpatterns  there  are  in  a  compiled pattern. The smallest size for         subpatterns there are in a compiled  pattern.  The  smallest  size  for
3412         ovector that will allow for n captured substrings, in addition  to  the         ovector  that  will allow for n captured substrings, in addition to the
3413         offsets 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.
3414    
3415         It  is  possible for capturing subpattern number n+1 to match some part         It is possible for capturing subpattern number n+1 to match  some  part
3416         of the subject when subpattern n has not been used at all. For example,         of the subject when subpattern n has not been used at all. For example,
3417         if  the  string  "abc"  is  matched against the pattern (a|(z))(bc) the         if the string "abc" is matched  against  the  pattern  (a|(z))(bc)  the
3418         return from the function is 4, and subpatterns 1 and 3 are matched, but         return from the function is 4, and subpatterns 1 and 3 are matched, but
3419         2  is  not.  When  this happens, both values in the offset pairs corre-         2 is not. When this happens, both values in  the  offset  pairs  corre-
3420         sponding to unused subpatterns are set to -1.         sponding to unused subpatterns are set to -1.
3421    
3422         Offset values that correspond to unused subpatterns at the end  of  the         Offset  values  that correspond to unused subpatterns at the end of the
3423         expression  are  also  set  to  -1. For example, if the string "abc" is         expression are also set to -1. For example,  if  the  string  "abc"  is
3424         matched against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are  not         matched  against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not
3425         matched.  The  return  from the function is 2, because the highest used         matched. The return from the function is 2, because  the  highest  used
3426         capturing subpattern number is 1, and the offsets for  for  the  second         capturing  subpattern  number  is 1, and the offsets for for the second
3427         and  third  capturing subpatterns (assuming the vector is large enough,         and third capturing subpatterns (assuming the vector is  large  enough,
3428         of course) are set to -1.         of course) are set to -1.
3429    
3430         Note: Elements in the first two-thirds of ovector that  do  not  corre-         Note:  Elements  in  the first two-thirds of ovector that do not corre-
3431         spond  to  capturing parentheses in the pattern are never changed. That         spond to capturing parentheses in the pattern are never  changed.  That
3432         is, if a pattern contains n capturing parentheses, no more  than  ovec-         is,  if  a pattern contains n capturing parentheses, no more than ovec-
3433         tor[0]  to ovector[2n+1] are set by pcre_exec(). The other elements (in         tor[0] to ovector[2n+1] are set by pcre_exec(). The other elements  (in
3434         the first two-thirds) retain whatever values they previously had.         the first two-thirds) retain whatever values they previously had.
3435    
3436         Some convenience functions are provided  for  extracting  the  captured         Some  convenience  functions  are  provided for extracting the captured
3437         substrings as separate strings. These are described below.         substrings as separate strings. These are described below.
3438    
3439     Error return values from pcre_exec()     Error return values from pcre_exec()
3440    
3441         If  pcre_exec()  fails, it returns a negative number. The following are         If pcre_exec() fails, it returns a negative number. The  following  are
3442         defined in the header file:         defined in the header file:
3443    
3444           PCRE_ERROR_NOMATCH        (-1)           PCRE_ERROR_NOMATCH        (-1)
# Line 2862  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3447  MATCHING A PATTERN: THE TRADITIONAL FUNC
3447    
3448           PCRE_ERROR_NULL           (-2)           PCRE_ERROR_NULL           (-2)
3449    
3450         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
3451         ovecsize was not zero.         ovecsize was not zero.
3452    
3453           PCRE_ERROR_BADOPTION      (-3)           PCRE_ERROR_BADOPTION      (-3)
# Line 2871  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3456  MATCHING A PATTERN: THE TRADITIONAL FUNC
3456    
3457           PCRE_ERROR_BADMAGIC       (-4)           PCRE_ERROR_BADMAGIC       (-4)
3458    
3459         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,
3460         to catch the case when it is passed a junk pointer and to detect when a         to catch the case when it is passed a junk pointer and to detect when a
3461         pattern that was compiled in an environment of one endianness is run in         pattern that was compiled in an environment of one endianness is run in
3462         an environment with the other endianness. This is the error  that  PCRE         an  environment  with the other endianness. This is the error that PCRE
3463         gives when the magic number is not present.         gives when the magic number is not present.
3464    
3465           PCRE_ERROR_UNKNOWN_OPCODE (-5)           PCRE_ERROR_UNKNOWN_OPCODE (-5)
3466    
3467         While running the pattern match, an unknown item was encountered in the         While running the pattern match, an unknown item was encountered in the
3468         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
3469         overwriting of the compiled pattern.         overwriting of the compiled pattern.
3470    
3471           PCRE_ERROR_NOMEMORY       (-6)           PCRE_ERROR_NOMEMORY       (-6)
3472    
3473         If  a  pattern contains back references, but the ovector that is passed         If a pattern contains back references, but the ovector that  is  passed
3474         to pcre_exec() is not big enough to remember the referenced substrings,         to pcre_exec() is not big enough to remember the referenced substrings,
3475         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
3476         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
3477         memory is automatically freed at the end of matching.         memory is automatically freed at the end of matching.
3478    
3479         This  error  is also given if pcre_stack_malloc() fails in pcre_exec().         This error is also given if pcre_stack_malloc() fails  in  pcre_exec().
3480         This can happen only when PCRE has been compiled with  --disable-stack-         This  can happen only when PCRE has been compiled with --disable-stack-
3481         for-recursion.         for-recursion.
3482    
3483           PCRE_ERROR_NOSUBSTRING    (-7)           PCRE_ERROR_NOSUBSTRING    (-7)
3484    
3485         This  error is used by the pcre_copy_substring(), pcre_get_substring(),         This error is used by the pcre_copy_substring(),  pcre_get_substring(),
3486         and  pcre_get_substring_list()  functions  (see  below).  It  is  never         and  pcre_get_substring_list()  functions  (see  below).  It  is  never
3487         returned by pcre_exec().         returned by pcre_exec().
3488    
3489           PCRE_ERROR_MATCHLIMIT     (-8)           PCRE_ERROR_MATCHLIMIT     (-8)
3490    
3491         The  backtracking  limit,  as  specified  by the match_limit field in a         The backtracking limit, as specified by  the  match_limit  field  in  a
3492         pcre_extra structure (or defaulted) was reached.  See  the  description         pcre_extra  structure  (or  defaulted) was reached. See the description
3493         above.         above.
3494    
3495           PCRE_ERROR_CALLOUT        (-9)           PCRE_ERROR_CALLOUT        (-9)
3496    
3497         This error is never generated by pcre_exec() itself. It is provided for         This error is never generated by pcre_exec() itself. It is provided for
3498         use by callout functions that want to yield a distinctive  error  code.         use  by  callout functions that want to yield a distinctive error code.
3499         See the pcrecallout documentation for details.         See the pcrecallout documentation for details.
3500    
3501           PCRE_ERROR_BADUTF8        (-10)           PCRE_ERROR_BADUTF8        (-10)
3502    
3503         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
3504         subject, and the PCRE_NO_UTF8_CHECK option was not set. If the size  of         subject,  and the PCRE_NO_UTF8_CHECK option was not set. If the size of
3505         the  output  vector  (ovecsize)  is  at least 2, the byte offset to the         the output vector (ovecsize) is at least 2,  the  byte  offset  to  the
3506         start of the the invalid UTF-8 character is placed in  the  first  ele-         start  of  the  the invalid UTF-8 character is placed in the first ele-
3507         ment,  and  a  reason  code is placed in the second element. The reason         ment, and a reason code is placed in the  second  element.  The  reason
3508         codes are listed in the following section.  For backward compatibility,         codes are listed in the following section.  For backward compatibility,
3509         if  PCRE_PARTIAL_HARD is set and the problem is a truncated UTF-8 char-         if PCRE_PARTIAL_HARD is set and the problem is a truncated UTF-8  char-
3510         acter  at  the  end  of  the   subject   (reason   codes   1   to   5),         acter   at   the   end   of   the   subject  (reason  codes  1  to  5),
3511         PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.         PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
3512    
3513           PCRE_ERROR_BADUTF8_OFFSET (-11)           PCRE_ERROR_BADUTF8_OFFSET (-11)
3514    
3515         The  UTF-8  byte  sequence that was passed as a subject was checked and         The UTF-8 byte sequence that was passed as a subject  was  checked  and
3516         found to be valid (the PCRE_NO_UTF8_CHECK option was not set), but  the         found  to be valid (the PCRE_NO_UTF8_CHECK option was not set), but the
3517         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-
3518         ter or the end of the subject.         ter or the end of the subject.
3519    
3520           PCRE_ERROR_PARTIAL        (-12)           PCRE_ERROR_PARTIAL        (-12)
3521    
3522         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
3523         pcrepartial documentation for details of partial matching.         pcrepartial documentation for details of partial matching.
3524    
3525           PCRE_ERROR_BADPARTIAL     (-13)           PCRE_ERROR_BADPARTIAL     (-13)
3526    
3527         This  code  is  no  longer  in  use.  It was formerly returned when the         This code is no longer in  use.  It  was  formerly  returned  when  the
3528         PCRE_PARTIAL option was used with a compiled pattern  containing  items         PCRE_PARTIAL  option  was used with a compiled pattern containing items
3529         that  were  not  supported  for  partial  matching.  From  release 8.00         that were  not  supported  for  partial  matching.  From  release  8.00
3530         onwards, there are no restrictions on partial matching.         onwards, there are no restrictions on partial matching.
3531    
3532           PCRE_ERROR_INTERNAL       (-14)           PCRE_ERROR_INTERNAL       (-14)
3533    
3534         An unexpected internal error has occurred. This error could  be  caused         An  unexpected  internal error has occurred. This error could be caused
3535         by a bug in PCRE or by overwriting of the compiled pattern.         by a bug in PCRE or by overwriting of the compiled pattern.
3536    
3537           PCRE_ERROR_BADCOUNT       (-15)           PCRE_ERROR_BADCOUNT       (-15)
# Line 2956  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3541  MATCHING A PATTERN: THE TRADITIONAL FUNC
3541           PCRE_ERROR_RECURSIONLIMIT (-21)           PCRE_ERROR_RECURSIONLIMIT (-21)
3542    
3543         The internal recursion limit, as specified by the match_limit_recursion         The internal recursion limit, as specified by the match_limit_recursion
3544         field in a pcre_extra structure (or defaulted)  was  reached.  See  the         field  in  a  pcre_extra  structure (or defaulted) was reached. See the
3545         description above.         description above.
3546    
3547           PCRE_ERROR_BADNEWLINE     (-23)           PCRE_ERROR_BADNEWLINE     (-23)
# Line 2970  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3555  MATCHING A PATTERN: THE TRADITIONAL FUNC
3555    
3556           PCRE_ERROR_SHORTUTF8      (-25)           PCRE_ERROR_SHORTUTF8      (-25)
3557    
3558         This error is returned instead of PCRE_ERROR_BADUTF8 when  the  subject         This  error  is returned instead of PCRE_ERROR_BADUTF8 when the subject
3559         string  ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD         string ends with a truncated UTF-8 character and the  PCRE_PARTIAL_HARD
3560         option is set.  Information  about  the  failure  is  returned  as  for         option  is  set.   Information  about  the  failure  is returned as for
3561         PCRE_ERROR_BADUTF8.  It  is in fact sufficient to detect this case, but         PCRE_ERROR_BADUTF8. It is in fact sufficient to detect this  case,  but
3562         this special error code for PCRE_PARTIAL_HARD precedes the  implementa-         this  special error code for PCRE_PARTIAL_HARD precedes the implementa-
3563         tion  of returned information; it is retained for backwards compatibil-         tion of returned information; it is retained for backwards  compatibil-
3564         ity.         ity.
3565    
3566           PCRE_ERROR_RECURSELOOP    (-26)           PCRE_ERROR_RECURSELOOP    (-26)
3567    
3568         This error is returned when pcre_exec() detects a recursion loop within         This error is returned when pcre_exec() detects a recursion loop within
3569         the  pattern. Specifically, it means that either the whole pattern or a         the pattern. Specifically, it means that either the whole pattern or  a
3570         subpattern has been called recursively for the second time at the  same         subpattern  has been called recursively for the second time at the same
3571         position in the subject string. Some simple patterns that might do this         position in the subject string. Some simple patterns that might do this
3572         are detected and faulted at compile time, but more  complicated  cases,         are  detected  and faulted at compile time, but more complicated cases,
3573         in particular mutual recursions between two different subpatterns, can-         in particular mutual recursions between two different subpatterns, can-
3574         not be detected until run time.         not be detected until run time.
3575    
3576           PCRE_ERROR_JIT_STACKLIMIT (-27)           PCRE_ERROR_JIT_STACKLIMIT (-27)
3577    
3578         This error is returned when a pattern  that  was  successfully  studied         This  error  is  returned  when a pattern that was successfully studied
3579         using  a  JIT compile option is being matched, but the memory available         using a JIT compile option is being matched, but the  memory  available
3580         for the just-in-time processing stack is  not  large  enough.  See  the         for  the  just-in-time  processing  stack  is not large enough. See the
3581         pcrejit documentation for more details.         pcrejit documentation for more details.
3582    
3583           PCRE_ERROR_BADMODE        (-28)           PCRE_ERROR_BADMODE        (-28)
3584    
3585         This error is given if a pattern that was compiled by the 8-bit library         This error is given if a pattern that was compiled by the 8-bit library
3586         is passed to a 16-bit library function, or vice versa.         is passed to a 16-bit or 32-bit library function, or vice versa.
3587    
3588           PCRE_ERROR_BADENDIANNESS  (-29)           PCRE_ERROR_BADENDIANNESS  (-29)
3589    
3590         This error is given if  a  pattern  that  was  compiled  and  saved  is         This  error  is  given  if  a  pattern  that  was compiled and saved is
3591         reloaded  on  a  host  with  different endianness. The utility function         reloaded on a host with  different  endianness.  The  utility  function
3592         pcre_pattern_to_host_byte_order() can be used to convert such a pattern         pcre_pattern_to_host_byte_order() can be used to convert such a pattern
3593         so that it runs on the new host.         so that it runs on the new host.
3594    
3595         Error numbers -16 to -20, -22, and -30 are not used by pcre_exec().           PCRE_ERROR_JIT_BADOPTION
3596    
3597           This error is returned when a pattern  that  was  successfully  studied
3598           using  a  JIT  compile  option  is being matched, but the matching mode
3599           (partial or complete match) does not correspond to any JIT  compilation
3600           mode.  When  the JIT fast path function is used, this error may be also
3601           given for invalid options.  See  the  pcrejit  documentation  for  more
3602           details.
3603    
3604             PCRE_ERROR_BADLENGTH      (-32)
3605    
3606           This  error is given if pcre_exec() is called with a negative value for
3607           the length argument.
3608    
3609           Error numbers -16 to -20, -22, and 30 are not used by pcre_exec().
3610    
3611     Reason codes for invalid UTF-8 strings     Reason codes for invalid UTF-8 strings
3612    
3613         This  section  applies  only  to  the  8-bit library. The corresponding         This section applies only  to  the  8-bit  library.  The  corresponding
3614         information for the 16-bit library is given in the pcre16 page.         information  for  the  16-bit  library is given in the pcre16 page. The
3615           corresponding information for the 32-bit library is given in the pcre32
3616           page.
3617    
3618         When pcre_exec() returns either PCRE_ERROR_BADUTF8 or PCRE_ERROR_SHORT-         When pcre_exec() returns either PCRE_ERROR_BADUTF8 or PCRE_ERROR_SHORT-
3619         UTF8,  and  the size of the output vector (ovecsize) is at least 2, the         UTF8, and the size of the output vector (ovecsize) is at least  2,  the
3620         offset of the start of the invalid UTF-8 character  is  placed  in  the         offset  of  the  start  of the invalid UTF-8 character is placed in the
3621         first output vector element (ovector[0]) and a reason code is placed in         first output vector element (ovector[0]) and a reason code is placed in
3622         the second element (ovector[1]). The reason codes are  given  names  in         the  second  element  (ovector[1]). The reason codes are given names in
3623         the pcre.h header file:         the pcre.h header file:
3624    
3625           PCRE_UTF8_ERR1           PCRE_UTF8_ERR1
# Line 3027  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3628  MATCHING A PATTERN: THE TRADITIONAL FUNC
3628           PCRE_UTF8_ERR4           PCRE_UTF8_ERR4
3629           PCRE_UTF8_ERR5           PCRE_UTF8_ERR5
3630    
3631         The  string  ends  with a truncated UTF-8 character; the code specifies         The string ends with a truncated UTF-8 character;  the  code  specifies
3632         how many bytes are missing (1 to 5). Although RFC 3629 restricts  UTF-8         how  many bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8
3633         characters  to  be  no longer than 4 bytes, the encoding scheme (origi-         characters to be no longer than 4 bytes, the  encoding  scheme  (origi-
3634         nally defined by RFC 2279) allows for  up  to  6  bytes,  and  this  is         nally  defined  by  RFC  2279)  allows  for  up to 6 bytes, and this is
3635         checked first; hence the possibility of 4 or 5 missing bytes.         checked first; hence the possibility of 4 or 5 missing bytes.
3636    
3637           PCRE_UTF8_ERR6           PCRE_UTF8_ERR6
# Line 3040  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3641  MATCHING A PATTERN: THE TRADITIONAL FUNC
3641           PCRE_UTF8_ERR10           PCRE_UTF8_ERR10
3642    
3643         The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of         The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of
3644         the character do not have the binary value 0b10 (that  is,  either  the         the  character  do  not have the binary value 0b10 (that is, either the
3645         most significant bit is 0, or the next bit is 1).         most significant bit is 0, or the next bit is 1).
3646    
3647           PCRE_UTF8_ERR11           PCRE_UTF8_ERR11
3648           PCRE_UTF8_ERR12           PCRE_UTF8_ERR12
3649    
3650         A  character that is valid by the RFC 2279 rules is either 5 or 6 bytes         A character that is valid by the RFC 2279 rules is either 5 or 6  bytes
3651         long; these code points are excluded by RFC 3629.         long; these code points are excluded by RFC 3629.
3652    
3653           PCRE_UTF8_ERR13           PCRE_UTF8_ERR13
3654    
3655         A 4-byte character has a value greater than 0x10fff; these code  points         A  4-byte character has a value greater than 0x10fff; these code points
3656         are excluded by RFC 3629.         are excluded by RFC 3629.
3657    
3658           PCRE_UTF8_ERR14           PCRE_UTF8_ERR14
3659    
3660         A  3-byte  character  has  a  value in the range 0xd800 to 0xdfff; this         A 3-byte character has a value in the  range  0xd800  to  0xdfff;  this
3661         range of code points are reserved by RFC 3629 for use with UTF-16,  and         range  of code points are reserved by RFC 3629 for use with UTF-16, and
3662         so are excluded from UTF-8.         so are excluded from UTF-8.
3663    
3664           PCRE_UTF8_ERR15           PCRE_UTF8_ERR15
# Line 3066  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3667  MATCHING A PATTERN: THE TRADITIONAL FUNC
3667           PCRE_UTF8_ERR18           PCRE_UTF8_ERR18
3668           PCRE_UTF8_ERR19           PCRE_UTF8_ERR19
3669    
3670         A  2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes         A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it  codes
3671         for a value that can be represented by fewer bytes, which  is  invalid.         for  a  value that can be represented by fewer bytes, which is invalid.
3672         For  example,  the two bytes 0xc0, 0xae give the value 0x2e, whose cor-         For example, the two bytes 0xc0, 0xae give the value 0x2e,  whose  cor-
3673         rect coding uses just one byte.         rect coding uses just one byte.
3674    
3675           PCRE_UTF8_ERR20           PCRE_UTF8_ERR20
3676    
3677         The two most significant bits of the first byte of a character have the         The two most significant bits of the first byte of a character have the
3678         binary  value 0b10 (that is, the most significant bit is 1 and the sec-         binary value 0b10 (that is, the most significant bit is 1 and the  sec-
3679         ond is 0). Such a byte can only validly occur as the second  or  subse-         ond  is  0). Such a byte can only validly occur as the second or subse-
3680         quent byte of a multi-byte character.         quent byte of a multi-byte character.
3681    
3682           PCRE_UTF8_ERR21           PCRE_UTF8_ERR21
3683    
3684         The  first byte of a character has the value 0xfe or 0xff. These values         The first byte of a character has the value 0xfe or 0xff. These  values
3685         can never occur in a valid UTF-8 string.         can never occur in a valid UTF-8 string.
3686    
3687             PCRE_UTF8_ERR2
3688    
3689           Non-character. These are the last two characters in each plane (0xfffe,
3690           0xffff, 0x1fffe, 0x1ffff .. 0x10fffe,  0x10ffff),  and  the  characters
3691           0xfdd0..0xfdef.
3692    
3693    
3694  EXTRACTING CAPTURED SUBSTRINGS BY NUMBER  EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
3695    
# Line 3097  EXTRACTING CAPTURED SUBSTRINGS BY NUMBER Line 3704  EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
3704         int pcre_get_substring_list(const char *subject,         int pcre_get_substring_list(const char *subject,
3705              int *ovector, int stringcount, const char ***listptr);              int *ovector, int stringcount, const char ***listptr);
3706    
3707         Captured substrings can be  accessed  directly  by  using  the  offsets         Captured  substrings  can  be  accessed  directly  by using the offsets
3708         returned  by  pcre_exec()  in  ovector.  For convenience, the functions         returned by pcre_exec() in  ovector.  For  convenience,  the  functions
3709         pcre_copy_substring(),    pcre_get_substring(),    and    pcre_get_sub-         pcre_copy_substring(),    pcre_get_substring(),    and    pcre_get_sub-
3710         string_list()  are  provided for extracting captured substrings as new,         string_list() are provided for extracting captured substrings  as  new,
3711         separate, zero-terminated strings. These functions identify  substrings         separate,  zero-terminated strings. These functions identify substrings
3712         by  number.  The  next section describes functions for extracting named         by number. The next section describes functions  for  extracting  named
3713         substrings.         substrings.
3714    
3715         A substring that contains a binary zero is correctly extracted and  has         A  substring that contains a binary zero is correctly extracted and has
3716         a  further zero added on the end, but the result is not, of course, a C         a further zero added on the end, but the result is not, of course, a  C
3717         string.  However, you can process such a string  by  referring  to  the         string.   However,  you  can  process such a string by referring to the
3718         length  that  is  returned  by  pcre_copy_substring() and pcre_get_sub-         length that is  returned  by  pcre_copy_substring()  and  pcre_get_sub-
3719         string().  Unfortunately, the interface to pcre_get_substring_list() is         string().  Unfortunately, the interface to pcre_get_substring_list() is
3720         not  adequate for handling strings containing binary zeros, because the         not adequate for handling strings containing binary zeros, because  the
3721         end of the final string is not independently indicated.         end of the final string is not independently indicated.
3722    
3723         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-
3724         tions:  subject  is  the subject string that has just been successfully         tions: subject is the subject string that has  just  been  successfully
3725         matched, ovector is a pointer to the vector of integer offsets that was         matched, ovector is a pointer to the vector of integer offsets that was
3726         passed to pcre_exec(), and stringcount is the number of substrings that         passed to pcre_exec(), and stringcount is the number of substrings that
3727         were captured by the match, including the substring  that  matched  the         were  captured  by  the match, including the substring that matched the
3728         entire regular expression. This is the value returned by pcre_exec() if         entire regular expression. This is the value returned by pcre_exec() if
3729         it is greater than zero. If pcre_exec() returned zero, indicating  that         it  is greater than zero. If pcre_exec() returned zero, indicating that
3730         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
3731         be the number of elements in the vector divided by three.         be the number of elements in the vector divided by three.
3732    
3733         The functions pcre_copy_substring() and pcre_get_substring() extract  a         The  functions pcre_copy_substring() and pcre_get_substring() extract a
3734         single  substring,  whose  number  is given as stringnumber. A value of         single substring, whose number is given as  stringnumber.  A  value  of
3735         zero extracts the substring that matched the  entire  pattern,  whereas         zero  extracts  the  substring that matched the entire pattern, whereas
3736         higher  values  extract  the  captured  substrings.  For pcre_copy_sub-         higher values  extract  the  captured  substrings.  For  pcre_copy_sub-
3737         string(), the string is placed in buffer,  whose  length  is  given  by         string(),  the  string  is  placed  in buffer, whose length is given by
3738         buffersize,  while  for  pcre_get_substring()  a new block of memory is         buffersize, while for pcre_get_substring() a new  block  of  memory  is
3739         obtained via pcre_malloc, and its address is  returned  via  stringptr.         obtained  via  pcre_malloc,  and its address is returned via stringptr.
3740         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
3741         the terminating zero, or one of these error codes:         the terminating zero, or one of these error codes:
3742    
3743           PCRE_ERROR_NOMEMORY       (-6)           PCRE_ERROR_NOMEMORY       (-6)
3744    
3745         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
3746         get memory failed for pcre_get_substring().         get memory failed for pcre_get_substring().
3747    
3748           PCRE_ERROR_NOSUBSTRING    (-7)           PCRE_ERROR_NOSUBSTRING    (-7)
3749    
3750         There is no substring whose number is stringnumber.         There is no substring whose number is stringnumber.
3751    
3752         The  pcre_get_substring_list()  function  extracts  all  available sub-         The pcre_get_substring_list()  function  extracts  all  available  sub-
3753         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
3754         single block of memory that is obtained via pcre_malloc. The address of         single block of memory that is obtained via pcre_malloc. The address of
3755         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
3756         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
3757         pointer. The yield of the function is zero if all  went  well,  or  the         pointer.  The  yield  of  the function is zero if all went well, or the
3758         error code         error code
3759    
3760           PCRE_ERROR_NOMEMORY       (-6)           PCRE_ERROR_NOMEMORY       (-6)
3761    
3762         if the attempt to get the memory block failed.         if the attempt to get the memory block failed.
3763    
3764         When  any of these functions encounter a substring that is unset, which         When any of these functions encounter a substring that is unset,  which
3765         can happen when capturing subpattern number n+1 matches  some  part  of         can  happen  when  capturing subpattern number n+1 matches some part of
3766         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
3767         empty string. This can be distinguished from a genuine zero-length sub-         empty string. This can be distinguished from a genuine zero-length sub-
3768         string  by inspecting the appropriate offset in ovector, which is nega-         string by inspecting the appropriate offset in ovector, which is  nega-
3769         tive for unset substrings.         tive for unset substrings.
3770    
3771         The two convenience functions pcre_free_substring() and  pcre_free_sub-         The  two convenience functions pcre_free_substring() and pcre_free_sub-
3772         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
3773         call  of  pcre_get_substring()  or  pcre_get_substring_list(),  respec-         call  of  pcre_get_substring()  or  pcre_get_substring_list(),  respec-
3774         tively.  They  do  nothing  more  than  call the function pointed to by         tively. They do nothing more than  call  the  function  pointed  to  by
3775         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.
3776         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-
3777         cial  interface  to  another  programming  language  that  cannot   use         cial   interface  to  another  programming  language  that  cannot  use
3778         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-
3779         vided.         vided.
3780    
3781    
# Line 3187  EXTRACTING CAPTURED SUBSTRINGS BY NAME Line 3794  EXTRACTING CAPTURED SUBSTRINGS BY NAME
3794              int stringcount, const char *stringname,              int stringcount, const char *stringname,
3795              const char **stringptr);              const char **stringptr);
3796    
3797         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-
3798         ber.  For example, for this pattern         ber.  For example, for this pattern
3799    
3800           (a+)b(?<xxx>\d+)...           (a+)b(?<xxx>\d+)...
# Line 3196  EXTRACTING CAPTURED SUBSTRINGS BY NAME Line 3803  EXTRACTING CAPTURED SUBSTRINGS BY NAME
3803         be unique (PCRE_DUPNAMES was not set), you can find the number from the         be unique (PCRE_DUPNAMES was not set), you can find the number from the
3804         name by calling pcre_get_stringnumber(). The first argument is the com-         name by calling pcre_get_stringnumber(). The first argument is the com-
3805         piled pattern, and the second is the name. The yield of the function is         piled pattern, and the second is the name. The yield of the function is
3806         the  subpattern  number,  or PCRE_ERROR_NOSUBSTRING (-7) if there is no         the subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if  there  is  no
3807         subpattern of that name.         subpattern of that name.
3808    
3809         Given the number, you can extract the substring directly, or use one of         Given the number, you can extract the substring directly, or use one of
3810         the functions described in the previous section. For convenience, there         the functions described in the previous section. For convenience, there
3811         are also two functions that do the whole job.         are also two functions that do the whole job.
3812    
3813         Most   of   the   arguments    of    pcre_copy_named_substring()    and         Most    of    the    arguments   of   pcre_copy_named_substring()   and
3814         pcre_get_named_substring()  are  the  same  as  those for the similarly         pcre_get_named_substring() are the same  as  those  for  the  similarly
3815         named functions that extract by number. As these are described  in  the         named  functions  that extract by number. As these are described in the
3816         previous  section,  they  are not re-described here. There are just two         previous section, they are not re-described here. There  are  just  two
3817         differences:         differences:
3818    
3819         First, instead of a substring number, a substring name is  given.  Sec-         First,  instead  of a substring number, a substring name is given. Sec-
3820         ond, there is an extra argument, given at the start, which is a pointer         ond, there is an extra argument, given at the start, which is a pointer
3821         to the compiled pattern. This is needed in order to gain access to  the         to  the compiled pattern. This is needed in order to gain access to the
3822         name-to-number translation table.         name-to-number translation table.
3823    
3824         These  functions call pcre_get_stringnumber(), and if it succeeds, they         These functions call pcre_get_stringnumber(), and if it succeeds,  they
3825         then call pcre_copy_substring() or pcre_get_substring(),  as  appropri-         then  call  pcre_copy_substring() or pcre_get_substring(), as appropri-
3826         ate.  NOTE:  If PCRE_DUPNAMES is set and there are duplicate names, the         ate. NOTE: If PCRE_DUPNAMES is set and there are duplicate  names,  the
3827         behaviour may not be what you want (see the next section).         behaviour may not be what you want (see the next section).
3828    
3829         Warning: If the pattern uses the (?| feature to set up multiple subpat-         Warning: If the pattern uses the (?| feature to set up multiple subpat-
3830         terns  with  the  same number, as described in the section on duplicate         terns with the same number, as described in the  section  on  duplicate
3831         subpattern numbers in the pcrepattern page, you  cannot  use  names  to         subpattern  numbers  in  the  pcrepattern page, you cannot use names to
3832         distinguish  the  different subpatterns, because names are not included         distinguish the different subpatterns, because names are  not  included
3833         in the compiled code. The matching process uses only numbers. For  this         in  the compiled code. The matching process uses only numbers. For this
3834         reason,  the  use of different names for subpatterns of the same number         reason, the use of different names for subpatterns of the  same  number
3835         causes an error at compile time.         causes an error at compile time.
3836    
3837    
# Line 3233  DUPLICATE SUBPATTERN NAMES Line 3840  DUPLICATE SUBPATTERN NAMES
3840         int pcre_get_stringtable_entries(const pcre *code,         int pcre_get_stringtable_entries(const pcre *code,
3841              const char *name, char **first, char **last);              const char *name, char **first, char **last);
3842    
3843         When a pattern is compiled with the  PCRE_DUPNAMES  option,  names  for         When  a  pattern  is  compiled with the PCRE_DUPNAMES option, names for
3844         subpatterns  are not required to be unique. (Duplicate names are always         subpatterns are not required to be unique. (Duplicate names are  always
3845         allowed for subpatterns with the same number, created by using the  (?|         allowed  for subpatterns with the same number, created by using the (?|
3846         feature.  Indeed,  if  such subpatterns are named, they are required to         feature. Indeed, if such subpatterns are named, they  are  required  to
3847         use the same names.)         use the same names.)
3848    
3849         Normally, patterns with duplicate names are such that in any one match,         Normally, patterns with duplicate names are such that in any one match,
3850         only  one of the named subpatterns participates. An example is shown in         only one of the named subpatterns participates. An example is shown  in
3851         the pcrepattern documentation.         the pcrepattern documentation.
3852    
3853         When   duplicates   are   present,   pcre_copy_named_substring()    and         When    duplicates   are   present,   pcre_copy_named_substring()   and
3854         pcre_get_named_substring()  return the first substring corresponding to         pcre_get_named_substring() return the first substring corresponding  to
3855         the given name that is set. If  none  are  set,  PCRE_ERROR_NOSUBSTRING         the  given  name  that  is set. If none are set, PCRE_ERROR_NOSUBSTRING
3856         (-7)  is  returned;  no  data  is returned. The pcre_get_stringnumber()         (-7) is returned; no  data  is  returned.  The  pcre_get_stringnumber()
3857         function returns one of the numbers that are associated with the  name,         function  returns one of the numbers that are associated with the name,
3858         but it is not defined which it is.         but it is not defined which it is.
3859    
3860         If  you want to get full details of all captured substrings for a given         If you want to get full details of all captured substrings for a  given
3861         name, you must use  the  pcre_get_stringtable_entries()  function.  The         name,  you  must  use  the pcre_get_stringtable_entries() function. The
3862         first argument is the compiled pattern, and the second is the name. The         first argument is the compiled pattern, and the second is the name. The
3863         third and fourth are pointers to variables which  are  updated  by  the         third  and  fourth  are  pointers to variables which are updated by the
3864         function. After it has run, they point to the first and last entries in         function. After it has run, they point to the first and last entries in
3865         the name-to-number table  for  the  given  name.  The  function  itself         the  name-to-number  table  for  the  given  name.  The function itself
3866         returns  the  length  of  each entry, or PCRE_ERROR_NOSUBSTRING (-7) if         returns the length of each entry,  or  PCRE_ERROR_NOSUBSTRING  (-7)  if
3867         there are none. The format of the table is described above in the  sec-         there  are none. The format of the table is described above in the sec-
3868         tion  entitled  Information about a pattern above.  Given all the rele-         tion entitled Information about a pattern above.  Given all  the  rele-
3869         vant entries for the name, you can extract each of their  numbers,  and         vant  entries  for the name, you can extract each of their numbers, and
3870         hence the captured data, if any.         hence the captured data, if any.
3871    
3872    
3873  FINDING ALL POSSIBLE MATCHES  FINDING ALL POSSIBLE MATCHES
3874    
3875         The  traditional  matching  function  uses a similar algorithm to Perl,         The traditional matching function uses a  similar  algorithm  to  Perl,
3876         which stops when it finds the first match, starting at a given point in         which stops when it finds the first match, starting at a given point in
3877         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
3878         possible match, consider using the alternative matching  function  (see         possible  match,  consider using the alternative matching function (see
3879         below)  instead.  If you cannot use the alternative function, but still         below) instead. If you cannot use the alternative function,  but  still
3880         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
3881         of the callout facility, which is described in the pcrecallout documen-         of the callout facility, which is described in the pcrecallout documen-
3882         tation.         tation.
3883    
3884         What you have to do is to insert a callout right at the end of the pat-         What you have to do is to insert a callout right at the end of the pat-
3885         tern.   When your callout function is called, extract and save the cur-         tern.  When your callout function is called, extract and save the  cur-
3886         rent matched substring. Then return  1,  which  forces  pcre_exec()  to         rent  matched  substring.  Then  return  1, which forces pcre_exec() to
3887         backtrack  and  try other alternatives. Ultimately, when it runs out of         backtrack and try other alternatives. Ultimately, when it runs  out  of
3888         matches, pcre_exec() will yield PCRE_ERROR_NOMATCH.         matches, pcre_exec() will yield PCRE_ERROR_NOMATCH.
3889    
3890    
3891  OBTAINING AN ESTIMATE OF STACK USAGE  OBTAINING AN ESTIMATE OF STACK USAGE
3892    
3893         Matching certain patterns using pcre_exec() can use a  lot  of  process         Matching  certain  patterns  using pcre_exec() can use a lot of process
3894         stack,  which  in  certain  environments can be rather limited in size.         stack, which in certain environments can be  rather  limited  in  size.
3895         Some users find it helpful to have an estimate of the amount  of  stack         Some  users  find it helpful to have an estimate of the amount of stack
3896         that  is  used  by  pcre_exec(),  to help them set recursion limits, as         that is used by pcre_exec(), to help  them  set  recursion  limits,  as
3897         described in the pcrestack documentation. The estimate that  is  output         described  in  the pcrestack documentation. The estimate that is output
3898         by pcretest when called with the -m and -C options is obtained by call-         by pcretest when called with the -m and -C options is obtained by call-
3899         ing pcre_exec with the values NULL, NULL, NULL, -999, and -999 for  its         ing  pcre_exec with the values NULL, NULL, NULL, -999, and -999 for its
3900         first five arguments.         first five arguments.
3901    
3902         Normally,  if  its  first  argument  is  NULL,  pcre_exec() immediately         Normally, if  its  first  argument  is  NULL,  pcre_exec()  immediately
3903         returns the negative error code PCRE_ERROR_NULL, but with this  special         returns  the negative error code PCRE_ERROR_NULL, but with this special
3904         combination  of  arguments,  it returns instead a negative number whose         combination of arguments, it returns instead a  negative  number  whose
3905         absolute value is the approximate stack frame size in bytes.  (A  nega-         absolute  value  is the approximate stack frame size in bytes. (A nega-
3906         tive  number  is  used so that it is clear that no match has happened.)         tive number is used so that it is clear that no  match  has  happened.)
3907         The value is approximate because in  some  cases,  recursive  calls  to         The  value  is  approximate  because  in some cases, recursive calls to
3908         pcre_exec() occur when there are one or two additional variables on the         pcre_exec() occur when there are one or two additional variables on the
3909         stack.         stack.
3910    
3911         If PCRE has been compiled to use the heap  instead  of  the  stack  for         If  PCRE  has  been  compiled  to use the heap instead of the stack for
3912         recursion,  the  value  returned  is  the  size  of  each block that is         recursion, the value returned  is  the  size  of  each  block  that  is
3913         obtained from the heap.         obtained from the heap.
3914    
3915    
# Line 3313  MATCHING A PATTERN: THE ALTERNATIVE FUNC Line 3920  MATCHING A PATTERN: THE ALTERNATIVE FUNC
3920              int options, int *ovector, int ovecsize,              int options, int *ovector, int ovecsize,
3921              int *workspace, int wscount);              int *workspace, int wscount);
3922    
3923         The function pcre_dfa_exec()  is  called  to  match  a  subject  string         The  function  pcre_dfa_exec()  is  called  to  match  a subject string
3924         against  a  compiled pattern, using a matching algorithm that scans the         against a compiled pattern, using a matching algorithm that  scans  the
3925         subject string just once, and does not backtrack.  This  has  different         subject  string  just  once, and does not backtrack. This has different
3926         characteristics  to  the  normal  algorithm, and is not compatible with         characteristics to the normal algorithm, and  is  not  compatible  with
3927         Perl. Some of the features of PCRE patterns are not  supported.  Never-         Perl.  Some  of the features of PCRE patterns are not supported. Never-
3928         theless,  there are times when this kind of matching can be useful. For         theless, there are times when this kind of matching can be useful.  For
3929         a discussion of the two matching algorithms, and  a  list  of  features         a  discussion  of  the  two matching algorithms, and a list of features
3930         that  pcre_dfa_exec() does not support, see the pcrematching documenta-         that pcre_dfa_exec() does not support, see the pcrematching  documenta-
3931         tion.         tion.
3932    
3933         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
3934         pcre_exec(), plus two extras. The ovector argument is used in a differ-         pcre_exec(), plus two extras. The ovector argument is used in a differ-
3935         ent way, and this is described below. The other  common  arguments  are         ent  way,  and  this is described below. The other common arguments are
3936         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
3937         repeated here.         repeated here.
3938    
3939         The two additional arguments provide workspace for  the  function.  The         The  two  additional  arguments provide workspace for the function. The
3940         workspace  vector  should  contain at least 20 elements. It is used for         workspace vector should contain at least 20 elements. It  is  used  for
3941         keeping  track  of  multiple  paths  through  the  pattern  tree.  More         keeping  track  of  multiple  paths  through  the  pattern  tree.  More
3942         workspace  will  be  needed for patterns and subjects where there are a         workspace will be needed for patterns and subjects where  there  are  a
3943         lot of potential matches.         lot of potential matches.
3944    
3945         Here is an example of a simple call to pcre_dfa_exec():         Here is an example of a simple call to pcre_dfa_exec():
# Line 3354  MATCHING A PATTERN: THE ALTERNATIVE FUNC Line 3961  MATCHING A PATTERN: THE ALTERNATIVE FUNC
3961    
3962     Option bits for pcre_dfa_exec()     Option bits for pcre_dfa_exec()
3963    
3964         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
3965         zero.  The  only  bits  that  may  be  set are PCRE_ANCHORED, PCRE_NEW-         zero. The only bits  that  may  be  set  are  PCRE_ANCHORED,  PCRE_NEW-
3966         LINE_xxx,        PCRE_NOTBOL,        PCRE_NOTEOL,        PCRE_NOTEMPTY,         LINE_xxx,        PCRE_NOTBOL,        PCRE_NOTEOL,        PCRE_NOTEMPTY,
3967         PCRE_NOTEMPTY_ATSTART,       PCRE_NO_UTF8_CHECK,      PCRE_BSR_ANYCRLF,         PCRE_NOTEMPTY_ATSTART,      PCRE_NO_UTF8_CHECK,       PCRE_BSR_ANYCRLF,
3968         PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE, PCRE_PARTIAL_HARD,  PCRE_PAR-         PCRE_BSR_UNICODE,  PCRE_NO_START_OPTIMIZE, PCRE_PARTIAL_HARD, PCRE_PAR-
3969         TIAL_SOFT,  PCRE_DFA_SHORTEST,  and PCRE_DFA_RESTART.  All but the last         TIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART.  All but  the  last
3970         four of these are  exactly  the  same  as  for  pcre_exec(),  so  their         four  of  these  are  exactly  the  same  as  for pcre_exec(), so their
3971         description is not repeated here.         description is not repeated here.
3972    
3973           PCRE_PARTIAL_HARD           PCRE_PARTIAL_HARD
3974           PCRE_PARTIAL_SOFT           PCRE_PARTIAL_SOFT
3975    
3976         These  have the same general effect as they do for pcre_exec(), but the         These have the same general effect as they do for pcre_exec(), but  the
3977         details are slightly  different.  When  PCRE_PARTIAL_HARD  is  set  for         details  are  slightly  different.  When  PCRE_PARTIAL_HARD  is set for
3978         pcre_dfa_exec(),  it  returns PCRE_ERROR_PARTIAL if the end of the sub-         pcre_dfa_exec(), it returns PCRE_ERROR_PARTIAL if the end of  the  sub-
3979         ject is reached and there is still at least  one  matching  possibility         ject  is  reached  and there is still at least one matching possibility
3980         that requires additional characters. This happens even if some complete         that requires additional characters. This happens even if some complete
3981         matches have also been found. When PCRE_PARTIAL_SOFT is set, the return         matches have also been found. When PCRE_PARTIAL_SOFT is set, the return
3982         code PCRE_ERROR_NOMATCH is converted into PCRE_ERROR_PARTIAL if the end         code PCRE_ERROR_NOMATCH is converted into PCRE_ERROR_PARTIAL if the end
3983         of the subject is reached, there have been  no  complete  matches,  but         of  the  subject  is  reached, there have been no complete matches, but
3984         there  is  still  at least one matching possibility. The portion of the         there is still at least one matching possibility. The  portion  of  the
3985         string that was inspected when the longest partial match was  found  is         string  that  was inspected when the longest partial match was found is
3986         set  as  the  first  matching  string  in  both cases.  There is a more         set as the first matching string  in  both  cases.   There  is  a  more
3987         detailed discussion of partial and multi-segment matching,  with  exam-         detailed  discussion  of partial and multi-segment matching, with exam-
3988         ples, in the pcrepartial documentation.         ples, in the pcrepartial documentation.
3989    
3990           PCRE_DFA_SHORTEST           PCRE_DFA_SHORTEST
3991    
3992         Setting  the  PCRE_DFA_SHORTEST option causes the matching algorithm to         Setting the PCRE_DFA_SHORTEST option causes the matching  algorithm  to
3993         stop as soon as it has found one match. Because of the way the alterna-         stop as soon as it has found one match. Because of the way the alterna-
3994         tive  algorithm  works, this is necessarily the shortest possible match         tive algorithm works, this is necessarily the shortest  possible  match
3995         at the first possible matching point in the subject string.         at the first possible matching point in the subject string.
3996    
3997           PCRE_DFA_RESTART           PCRE_DFA_RESTART
3998    
3999         When pcre_dfa_exec() returns a partial match, it is possible to call it         When pcre_dfa_exec() returns a partial match, it is possible to call it
4000         again,  with  additional  subject characters, and have it continue with         again, with additional subject characters, and have  it  continue  with
4001         the same match. The PCRE_DFA_RESTART option requests this action;  when         the  same match. The PCRE_DFA_RESTART option requests this action; when
4002         it  is  set,  the workspace and wscount options must reference the same         it is set, the workspace and wscount options must  reference  the  same
4003         vector as before because data about the match so far is  left  in  them         vector  as  before  because data about the match so far is left in them
4004         after a partial match. There is more discussion of this facility in the         after a partial match. There is more discussion of this facility in the
4005         pcrepartial documentation.         pcrepartial documentation.
4006    
4007     Successful returns from pcre_dfa_exec()     Successful returns from pcre_dfa_exec()
4008    
4009         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-
4010         string in the subject. Note, however, that all the matches from one run         string in the subject. Note, however, that all the matches from one run
4011         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
4012         matches  are all initial substrings of the longer matches. For example,         matches are all initial substrings of the longer matches. For  example,
4013         if the pattern         if the pattern
4014    
4015           <.*>           <.*>
# Line 3417  MATCHING A PATTERN: THE ALTERNATIVE FUNC Line 4024  MATCHING A PATTERN: THE ALTERNATIVE FUNC
4024           <something> <something else>           <something> <something else>
4025           <something> <something else> <something further>           <something> <something else> <something further>
4026    
4027         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,
4028         which  is  the  number of matched substrings. The substrings themselves         which is the number of matched substrings.  The  substrings  themselves
4029         are returned in ovector. Each string uses two elements;  the  first  is         are  returned  in  ovector. Each string uses two elements; the first is
4030         the  offset  to  the start, and the second is the offset to the end. In         the offset to the start, and the second is the offset to  the  end.  In
4031         fact, all the strings have the same start  offset.  (Space  could  have         fact,  all  the  strings  have the same start offset. (Space could have
4032         been  saved by giving this only once, but it was decided to retain some         been saved by giving this only once, but it was decided to retain  some
4033         compatibility with the way pcre_exec() returns data,  even  though  the         compatibility  with  the  way pcre_exec() returns data, even though the
4034         meaning of the strings is different.)         meaning of the strings is different.)
4035    
4036         The strings are returned in reverse order of length; that is, the long-         The strings are returned in reverse order of length; that is, the long-
4037         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
4038         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
4039         filled with the longest matches.  Unlike  pcre_exec(),  pcre_dfa_exec()         filled  with  the  longest matches. Unlike pcre_exec(), pcre_dfa_exec()
4040         can use the entire ovector for returning matched strings.         can use the entire ovector for returning matched strings.
4041    
4042     Error returns from pcre_dfa_exec()     Error returns from pcre_dfa_exec()
4043    
4044         The  pcre_dfa_exec()  function returns a negative number when it fails.         The pcre_dfa_exec() function returns a negative number when  it  fails.
4045         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
4046         described  above.   There are in addition the following errors that are         described above.  There are in addition the following errors  that  are
4047         specific to pcre_dfa_exec():         specific to pcre_dfa_exec():
4048    
4049           PCRE_ERROR_DFA_UITEM      (-16)           PCRE_ERROR_DFA_UITEM      (-16)
4050    
4051         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-
4052         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
4053         reference.         reference.
4054    
4055           PCRE_ERROR_DFA_UCOND      (-17)           PCRE_ERROR_DFA_UCOND      (-17)
4056    
4057         This return is given if pcre_dfa_exec()  encounters  a  condition  item         This  return  is  given  if pcre_dfa_exec() encounters a condition item
4058         that  uses  a back reference for the condition, or a test for recursion         that uses a back reference for the condition, or a test  for  recursion
4059         in a specific group. These are not supported.         in a specific group. These are not supported.
4060    
4061           PCRE_ERROR_DFA_UMLIMIT    (-18)           PCRE_ERROR_DFA_UMLIMIT    (-18)
4062    
4063         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
4064         that  contains  a  setting  of the match_limit or match_limit_recursion         that contains a setting of  the  match_limit  or  match_limit_recursion
4065         fields. This is not supported (these fields  are  meaningless  for  DFA         fields.  This  is  not  supported (these fields are meaningless for DFA
4066         matching).         matching).
4067    
4068           PCRE_ERROR_DFA_WSSIZE     (-19)           PCRE_ERROR_DFA_WSSIZE     (-19)
4069    
4070         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
4071         workspace vector.         workspace vector.
4072    
4073           PCRE_ERROR_DFA_RECURSE    (-20)           PCRE_ERROR_DFA_RECURSE    (-20)
4074    
4075         When a recursive subpattern is processed, the matching  function  calls         When  a  recursive subpattern is processed, the matching function calls
4076         itself  recursively,  using  private vectors for ovector and workspace.         itself recursively, using private vectors for  ovector  and  workspace.
4077         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
4078         should be extremely rare, as a vector of size 1000 is used.         should be extremely rare, as a vector of size 1000 is used.
4079    
4080           PCRE_ERROR_DFA_BADRESTART (-30)           PCRE_ERROR_DFA_BADRESTART (-30)
4081    
4082         When  pcre_dfa_exec()  is called with the PCRE_DFA_RESTART option, some         When pcre_dfa_exec() is called with the PCRE_DFA_RESTART  option,  some
4083         plausibility checks are made on the contents of  the  workspace,  which         plausibility  checks  are  made on the contents of the workspace, which
4084         should  contain  data about the previous partial match. If any of these         should contain data about the previous partial match. If any  of  these
4085         checks fail, this error is given.         checks fail, this error is given.
4086    
4087    
4088  SEE ALSO  SEE ALSO
4089    
4090         pcre16(3),  pcrebuild(3),  pcrecallout(3),  pcrecpp(3)(3),   pcrematch-         pcre16(3),   pcre32(3),  pcrebuild(3),  pcrecallout(3),  pcrecpp(3)(3),
4091         ing(3), pcrepartial(3), pcreposix(3), pcreprecompile(3), pcresample(3),         pcrematching(3), pcrepartial(3), pcreposix(3), pcreprecompile(3), pcre-
4092         pcrestack(3).         sample(3), pcrestack(3).
4093    
4094    
4095  AUTHOR  AUTHOR
# Line 3494  AUTHOR Line 4101  AUTHOR
4101    
4102  REVISION  REVISION
4103    
4104         Last updated: 17 June 2012         Last updated: 31 October 2012
4105         Copyright (c) 1997-2012 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
4106  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
4107    
4108    
4109  PCRECALLOUT(3)                                                  PCRECALLOUT(3)  PCRECALLOUT(3)                                                  PCRECALLOUT(3)
4110    
4111    
# Line 3506  NAME Line 4113  NAME
4113         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
4114    
4115    
4116  PCRE CALLOUTS  SYNOPSIS
4117    
4118           #include <pcre.h>
4119    
4120         int (*pcre_callout)(pcre_callout_block *);         int (*pcre_callout)(pcre_callout_block *);
4121    
4122         int (*pcre16_callout)(pcre16_callout_block *);         int (*pcre16_callout)(pcre16_callout_block *);
4123    
4124           int (*pcre32_callout)(pcre32_callout_block *);
4125    
4126    
4127    DESCRIPTION
4128    
4129         PCRE provides a feature called "callout", which is a means of temporar-         PCRE provides a feature called "callout", which is a means of temporar-
4130         ily passing control to the caller of PCRE  in  the  middle  of  pattern         ily passing control to the caller of PCRE  in  the  middle  of  pattern
4131         matching.  The  caller of PCRE provides an external function by putting         matching.  The  caller of PCRE provides an external function by putting
4132         its entry point in the global variable pcre_callout (pcre16_callout for         its entry point in the global variable pcre_callout (pcre16_callout for
4133         the  16-bit  library).  By  default, this variable contains NULL, which         the 16-bit library, pcre32_callout for the 32-bit library). By default,
4134         disables all calling out.         this variable contains NULL, which disables all calling out.
4135    
4136         Within a regular expression, (?C) indicates the  points  at  which  the         Within a regular expression, (?C) indicates the  points  at  which  the
4137         external  function  is  to  be  called. Different callout points can be         external  function  is  to  be  called. Different callout points can be
# Line 3577  MISSING CALLOUTS Line 4191  MISSING CALLOUTS
4191  THE CALLOUT INTERFACE  THE CALLOUT INTERFACE
4192    
4193         During  matching, when PCRE reaches a callout point, the external func-         During  matching, when PCRE reaches a callout point, the external func-
4194         tion defined by pcre_callout or pcre16_callout  is  called  (if  it  is         tion defined by pcre_callout or pcre[16|32]_callout is called (if it is
4195         set).   This applies to both normal and DFA matching. The only argument         set).  This  applies to both normal and DFA matching. The only argument
4196         to the callout function is a pointer to a pcre_callout or  pcre16_call-         to  the  callout  function  is  a  pointer   to   a   pcre_callout   or
4197         out block.  These structures contains the following fields:         pcre[16|32]_callout  block.   These  structures  contains the following
4198           fields:
4199    
4200           int           version;           int           version;
4201           int           callout_number;           int           callout_number;
4202           int          *offset_vector;           int          *offset_vector;
4203           const char   *subject;           (8-bit version)           const char   *subject;           (8-bit version)
4204           PCRE_SPTR16   subject;           (16-bit version)           PCRE_SPTR16   subject;           (16-bit version)
4205             PCRE_SPTR32   subject;           (32-bit version)
4206           int           subject_length;           int           subject_length;
4207           int           start_match;           int           start_match;
4208           int           current_position;           int           current_position;
# Line 3597  THE CALLOUT INTERFACE Line 4213  THE CALLOUT INTERFACE
4213           int           next_item_length;           int           next_item_length;
4214           const unsigned char *mark;       (8-bit version)           const unsigned char *mark;       (8-bit version)
4215           const PCRE_UCHAR16  *mark;       (16-bit version)           const PCRE_UCHAR16  *mark;       (16-bit version)
4216             const PCRE_UCHAR32  *mark;       (32-bit version)
4217    
4218         The  version  field  is an integer containing the version number of the         The version field is an integer containing the version  number  of  the
4219         block format. The initial version was 0; the current version is 2.  The         block  format. The initial version was 0; the current version is 2. The
4220         version  number  will  change  again in future if additional fields are         version number will change again in future  if  additional  fields  are
4221         added, but the intention is never to remove any of the existing fields.         added, but the intention is never to remove any of the existing fields.
4222    
4223         The callout_number field contains the number of the  callout,  as  com-         The  callout_number  field  contains the number of the callout, as com-
4224         piled  into  the pattern (that is, the number after ?C for manual call-         piled into the pattern (that is, the number after ?C for  manual  call-
4225         outs, and 255 for automatically generated callouts).         outs, and 255 for automatically generated callouts).
4226    
4227         The offset_vector field is a pointer to the vector of offsets that  was         The  offset_vector field is a pointer to the vector of offsets that was
4228         passed  by  the  caller  to  the matching function. When pcre_exec() or         passed by the caller to the  matching  function.  When  pcre_exec()  or
4229         pcre16_exec() is used, the contents  can  be  inspected,  in  order  to         pcre[16|32]_exec()  is used, the contents can be inspected, in order to
4230         extract  substrings  that  have been matched so far, in the same way as         extract substrings that have been matched so far, in the  same  way  as
4231         for extracting substrings after a match  has  completed.  For  the  DFA         for  extracting  substrings  after  a  match has completed. For the DFA
4232         matching functions, this field is not useful.         matching functions, this field is not useful.
4233    
4234         The subject and subject_length fields contain copies of the values that         The subject and subject_length fields contain copies of the values that
4235         were passed to the matching function.         were passed to the matching function.
4236    
4237         The start_match field normally contains the offset within  the  subject         The  start_match  field normally contains the offset within the subject
4238         at  which  the  current  match  attempt started. However, if the escape         at which the current match attempt  started.  However,  if  the  escape
4239         sequence \K has been encountered, this value is changed to reflect  the         sequence  \K has been encountered, this value is changed to reflect the
4240         modified  starting  point.  If the pattern is not anchored, the callout         modified starting point. If the pattern is not  anchored,  the  callout
4241         function may be called several times from the same point in the pattern         function may be called several times from the same point in the pattern
4242         for different starting points in the subject.         for different starting points in the subject.
4243    
4244         The  current_position  field  contains the offset within the subject of         The current_position field contains the offset within  the  subject  of
4245         the current match pointer.         the current match pointer.
4246    
4247         When the pcre_exec() or pcre16_exec() is used,  the  capture_top  field         When  the  pcre_exec()  or  pcre[16|32]_exec() is used, the capture_top
4248         contains one more than the number of the highest numbered captured sub-         field contains one more than the number of the  highest  numbered  cap-
4249         string so far. If no substrings have been captured, the value  of  cap-         tured  substring so far. If no substrings have been captured, the value
4250         ture_top  is  one.  This  is always the case when the DFA functions are         of capture_top is one. This is always the case when the  DFA  functions
4251         used, because they do not support captured substrings.         are used, because they do not support captured substrings.
4252    
4253         The capture_last field contains the number of the  most  recently  cap-         The  capture_last  field  contains the number of the most recently cap-
4254         tured  substring. If no substrings have been captured, its value is -1.         tured substring. If no substrings have been captured, its value is  -1.
4255         This is always the case for the DFA matching functions.         This is always the case for the DFA matching functions.
4256    
4257         The callout_data field contains a value that is passed  to  a  matching         The  callout_data  field  contains a value that is passed to a matching
4258         function  specifically so that it can be passed back in callouts. It is         function specifically so that it can be passed back in callouts. It  is
4259         passed in the callout_data field of a pcre_extra or  pcre16_extra  data         passed  in  the callout_data field of a pcre_extra or pcre[16|32]_extra
4260         structure.  If  no such data was passed, the value of callout_data in a         data structure. If no such data was passed, the value  of  callout_data
4261         callout block is NULL. There is a description of the pcre_extra  struc-         in  a  callout  block is NULL. There is a description of the pcre_extra
4262         ture in the pcreapi documentation.         structure in the pcreapi documentation.
4263    
4264         The  pattern_position  field  is  present from version 1 of the callout         The pattern_position field is present from version  1  of  the  callout
4265         structure. It contains the offset to the next item to be matched in the         structure. It contains the offset to the next item to be matched in the
4266         pattern string.         pattern string.
4267    
4268         The  next_item_length  field  is  present from version 1 of the callout         The next_item_length field is present from version  1  of  the  callout
4269         structure. It contains the length of the next item to be matched in the         structure. It contains the length of the next item to be matched in the
4270         pattern  string.  When  the callout immediately precedes an alternation         pattern string. When the callout immediately  precedes  an  alternation
4271         bar, a closing parenthesis, or the end of the pattern,  the  length  is         bar,  a  closing  parenthesis, or the end of the pattern, the length is
4272         zero.  When  the callout precedes an opening parenthesis, the length is         zero. When the callout precedes an opening parenthesis, the  length  is
4273         that of the entire subpattern.         that of the entire subpattern.
4274    
4275         The pattern_position and next_item_length fields are intended  to  help         The  pattern_position  and next_item_length fields are intended to help
4276         in  distinguishing between different automatic callouts, which all have         in distinguishing between different automatic callouts, which all  have
4277         the same callout number. However, they are set for all callouts.         the same callout number. However, they are set for all callouts.
4278    
4279         The mark field is present from version 2 of the callout  structure.  In         The  mark  field is present from version 2 of the callout structure. In
4280         callouts from pcre_exec() or pcre16_exec() it contains a pointer to the         callouts from pcre_exec() or pcre[16|32]_exec() it contains  a  pointer
4281         zero-terminated name of the most recently passed (*MARK), (*PRUNE),  or         to  the  zero-terminated  name  of  the  most  recently passed (*MARK),
4282         (*THEN)  item  in the match, or NULL if no such items have been passed.         (*PRUNE), or (*THEN) item in the match, or NULL if no such  items  have
4283         Instances of (*PRUNE) or (*THEN) without a name  do  not  obliterate  a         been  passed.  Instances  of  (*PRUNE) or (*THEN) without a name do not
4284         previous  (*MARK).  In  callouts  from  the DFA matching functions this         obliterate a previous (*MARK). In callouts from the DFA matching  func-
4285         field always contains NULL.         tions this field always contains NULL.
4286    
4287    
4288  RETURN VALUES  RETURN VALUES
4289    
4290         The external callout function returns an integer to PCRE. If the  value         The  external callout function returns an integer to PCRE. If the value
4291         is  zero,  matching  proceeds  as  normal. If the value is greater than         is zero, matching proceeds as normal. If  the  value  is  greater  than
4292         zero, matching fails at the current point, but  the  testing  of  other         zero,  matching  fails  at  the current point, but the testing of other
4293         matching possibilities goes ahead, just as if a lookahead assertion had         matching possibilities goes ahead, just as if a lookahead assertion had
4294         failed. If the value is less than zero, the  match  is  abandoned,  the         failed.  If  the  value  is less than zero, the match is abandoned, the
4295         matching function returns the negative value.         matching function returns the negative value.
4296    
4297         Negative   values   should   normally   be   chosen  from  the  set  of         Negative  values  should  normally  be   chosen   from   the   set   of
4298         PCRE_ERROR_xxx values. In particular, PCRE_ERROR_NOMATCH forces a stan-         PCRE_ERROR_xxx values. In particular, PCRE_ERROR_NOMATCH forces a stan-
4299         dard  "no  match"  failure.   The  error  number  PCRE_ERROR_CALLOUT is         dard "no  match"  failure.   The  error  number  PCRE_ERROR_CALLOUT  is
4300         reserved for use by callout functions; it will never be  used  by  PCRE         reserved  for  use  by callout functions; it will never be used by PCRE
4301         itself.         itself.
4302    
4303    
# Line 3693  AUTHOR Line 4310  AUTHOR
4310    
4311  REVISION  REVISION
4312    
4313         Last updated: 08 Janurary 2012         Last updated: 24 June 2012
4314         Copyright (c) 1997-2012 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
4315  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
4316    
4317    
4318  PCRECOMPAT(3)                                                    PCRECOMPAT(3)  PCRECOMPAT(3)                                                    PCRECOMPAT(3)
4319    
4320    
# Line 3752  DIFFERENCES BETWEEN PCRE AND PERL Line 4369  DIFFERENCES BETWEEN PCRE AND PERL
4369         tion  of Unicode characters, there is no need to implement the somewhat         tion  of Unicode characters, there is no need to implement the somewhat
4370         messy concept of surrogates."         messy concept of surrogates."
4371    
4372         7. PCRE implements a simpler version of \X than Perl, which changed  to         7. PCRE does support the \Q...\E escape for quoting substrings. Charac-
4373         make  \X  match what Unicode calls an "extended grapheme cluster". This         ters  in  between  are  treated as literals. This is slightly different
4374         is more complicated than an extended Unicode sequence,  which  is  what         from Perl in that $ and @ are  also  handled  as  literals  inside  the
4375         PCRE matches.         quotes.  In Perl, they cause variable interpolation (but of course PCRE
   
        8. PCRE does support the \Q...\E escape for quoting substrings. Charac-  
        ters in between are treated as literals.  This  is  slightly  different  
        from  Perl  in  that  $  and  @ are also handled as literals inside the  
        quotes. In Perl, they cause variable interpolation (but of course  PCRE  
4376         does not have variables). Note the following examples:         does not have variables). Note the following examples:
4377    
4378             Pattern            PCRE matches      Perl matches             Pattern            PCRE matches      Perl matches
# Line 3770  DIFFERENCES BETWEEN PCRE AND PERL Line 4382  DIFFERENCES BETWEEN PCRE AND PERL
4382             \Qabc\$xyz\E       abc\$xyz          abc\$xyz             \Qabc\$xyz\E       abc\$xyz          abc\$xyz
4383             \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz             \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
4384    
4385         The  \Q...\E  sequence  is recognized both inside and outside character         The \Q...\E sequence is recognized both inside  and  outside  character
4386         classes.         classes.
4387    
4388         9. Fairly obviously, PCRE does not support the (?{code}) and (??{code})         8. Fairly obviously, PCRE does not support the (?{code}) and (??{code})
4389         constructions.  However,  there is support for recursive patterns. This         constructions. However, there is support for recursive  patterns.  This
4390         is not available in Perl 5.8, but it is in Perl 5.10.  Also,  the  PCRE         is  not  available  in Perl 5.8, but it is in Perl 5.10. Also, the PCRE
4391         "callout"  feature allows an external function to be called during pat-         "callout" feature allows an external function to be called during  pat-
4392         tern matching. See the pcrecallout documentation for details.         tern matching. See the pcrecallout documentation for details.
4393    
4394         10. Subpatterns that are called as subroutines (whether or  not  recur-         9.  Subpatterns  that  are called as subroutines (whether or not recur-
4395         sively)  are  always  treated  as  atomic  groups in PCRE. This is like         sively) are always treated as atomic  groups  in  PCRE.  This  is  like
4396         Python, but unlike Perl.  Captured values that are set outside  a  sub-         Python,  but  unlike Perl.  Captured values that are set outside a sub-
4397         routine  call  can  be  reference from inside in PCRE, but not in Perl.         routine call can be reference from inside in PCRE,  but  not  in  Perl.
4398         There is a discussion that explains these differences in more detail in         There is a discussion that explains these differences in more detail in
4399         the section on recursion differences from Perl in the pcrepattern page.         the section on recursion differences from Perl in the pcrepattern page.
4400    
4401         11.  If  any of the backtracking control verbs are used in an assertion         10. If any of the backtracking control verbs are used in  an  assertion
4402         or in a subpattern that is called  as  a  subroutine  (whether  or  not         or  in  a  subpattern  that  is  called as a subroutine (whether or not
4403         recursively),  their effect is confined to that subpattern; it does not         recursively), their effect is confined to that subpattern; it does  not
4404         extend to the surrounding pattern. This is not always the case in Perl.         extend to the surrounding pattern. This is not always the case in Perl.
4405         In  particular,  if  (*THEN)  is present in a group that is called as a         In particular, if (*THEN) is present in a group that  is  called  as  a
4406         subroutine, its action is limited to that group, even if the group does         subroutine, its action is limited to that group, even if the group does
4407         not  contain any | characters. There is one exception to this: the name         not contain any | characters. There is one exception to this: the  name
4408         from a *(MARK), (*PRUNE), or (*THEN) that is encountered in a  success-         from  a *(MARK), (*PRUNE), or (*THEN) that is encountered in a success-
4409         ful  positive  assertion  is passed back when a match succeeds (compare         ful positive assertion is passed back when a  match  succeeds  (compare
4410         capturing parentheses in assertions). Note that  such  subpatterns  are         capturing  parentheses  in  assertions). Note that such subpatterns are
4411         processed as anchored at the point where they are tested.         processed as anchored at the point where they are tested.
4412    
4413         12.  There are some differences that are concerned with the settings of         11. There are some differences that are concerned with the settings  of
4414         captured strings when part of  a  pattern  is  repeated.  For  example,         captured  strings  when  part  of  a  pattern is repeated. For example,
4415         matching  "aba"  against  the  pattern  /^(a(b)?)+$/  in Perl leaves $2         matching "aba" against the  pattern  /^(a(b)?)+$/  in  Perl  leaves  $2
4416         unset, but in PCRE it is set to "b".         unset, but in PCRE it is set to "b".
4417    
4418         13. PCRE's handling of duplicate subpattern numbers and duplicate  sub-         12.  PCRE's handling of duplicate subpattern numbers and duplicate sub-
4419         pattern names is not as general as Perl's. This is a consequence of the         pattern names is not as general as Perl's. This is a consequence of the
4420         fact the PCRE works internally just with numbers, using an external ta-         fact the PCRE works internally just with numbers, using an external ta-
4421         ble  to  translate  between numbers and names. In particular, a pattern         ble to translate between numbers and names. In  particular,  a  pattern
4422         such as (?|(?<a>A)|(?<b)B), where the two  capturing  parentheses  have         such  as  (?|(?<a>A)|(?<b)B),  where the two capturing parentheses have
4423         the  same  number  but different names, is not supported, and causes an         the same number but different names, is not supported,  and  causes  an
4424         error at compile time. If it were allowed, it would not be possible  to         error  at compile time. If it were allowed, it would not be possible to
4425         distinguish  which  parentheses matched, because both names map to cap-         distinguish which parentheses matched, because both names map  to  cap-
4426         turing subpattern number 1. To avoid this confusing situation, an error         turing subpattern number 1. To avoid this confusing situation, an error
4427         is given at compile time.         is given at compile time.
4428    
4429         14.  Perl  recognizes  comments  in some places that PCRE does not, for         13. Perl recognizes comments in some places that  PCRE  does  not,  for
4430         example, between the ( and ? at the start of a subpattern.  If  the  /x         example,  between  the  ( and ? at the start of a subpattern. If the /x
4431         modifier is set, Perl allows white space between ( and ? but PCRE never         modifier is set, Perl allows white space between ( and ? but PCRE never
4432         does, even if the PCRE_EXTENDED option is set.         does, even if the PCRE_EXTENDED option is set.
4433    
4434         15. PCRE provides some extensions to the Perl regular expression facil-         14. PCRE provides some extensions to the Perl regular expression facil-
4435         ities.   Perl  5.10  includes new features that are not in earlier ver-         ities.  Perl 5.10 includes new features that are not  in  earlier  ver-
4436         sions of Perl, some of which (such as named parentheses) have  been  in         sions  of  Perl, some of which (such as named parentheses) have been in
4437         PCRE for some time. This list is with respect to Perl 5.10:         PCRE for some time. This list is with respect to Perl 5.10:
4438    
4439         (a)  Although  lookbehind  assertions  in  PCRE must match fixed length         (a) Although lookbehind assertions in  PCRE  must  match  fixed  length
4440         strings, each alternative branch of a lookbehind assertion can match  a         strings,  each alternative branch of a lookbehind assertion can match a
4441         different  length  of  string.  Perl requires them all to have the same         different length of string. Perl requires them all  to  have  the  same
4442         length.         length.
4443    
4444         (b) If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not set, the  $         (b)  If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not set, the $
4445         meta-character matches only at the very end of the string.         meta-character matches only at the very end of the string.
4446    
4447         (c) If PCRE_EXTRA is set, a backslash followed by a letter with no spe-         (c) If PCRE_EXTRA is set, a backslash followed by a letter with no spe-
4448         cial meaning is faulted. Otherwise, like Perl, the backslash is quietly         cial meaning is faulted. Otherwise, like Perl, the backslash is quietly
4449         ignored.  (Perl can be made to issue a warning.)         ignored.  (Perl can be made to issue a warning.)
4450    
4451         (d)  If  PCRE_UNGREEDY is set, the greediness of the repetition quanti-         (d) If PCRE_UNGREEDY is set, the greediness of the  repetition  quanti-
4452         fiers is inverted, that is, by default they are not greedy, but if fol-         fiers is inverted, that is, by default they are not greedy, but if fol-
4453         lowed by a question mark they are.         lowed by a question mark they are.
4454    
# Line 3844  DIFFERENCES BETWEEN PCRE AND PERL Line 4456  DIFFERENCES BETWEEN PCRE AND PERL
4456         tried only at the first matching position in the subject string.         tried only at the first matching position in the subject string.
4457    
4458         (f) The PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,         (f) The PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
4459         and  PCRE_NO_AUTO_CAPTURE  options for pcre_exec() have no Perl equiva-         and PCRE_NO_AUTO_CAPTURE options for pcre_exec() have no  Perl  equiva-
4460         lents.         lents.
4461    
4462         (g) The \R escape sequence can be restricted to match only CR,  LF,  or         (g)  The  \R escape sequence can be restricted to match only CR, LF, or
4463         CRLF by the PCRE_BSR_ANYCRLF option.         CRLF by the PCRE_BSR_ANYCRLF option.
4464    
4465         (h) The callout facility is PCRE-specific.         (h) The callout facility is PCRE-specific.
# Line 3855  DIFFERENCES BETWEEN PCRE AND PERL Line 4467  DIFFERENCES BETWEEN PCRE AND PERL
4467         (i) The partial matching facility is PCRE-specific.         (i) The partial matching facility is PCRE-specific.
4468    
4469         (j) Patterns compiled by PCRE can be saved and re-used at a later time,         (j) Patterns compiled by PCRE can be saved and re-used at a later time,
4470         even on different hosts that have the other endianness.  However,  this         even  on  different hosts that have the other endianness. However, this
4471         does not apply to optimized data created by the just-in-time compiler.         does not apply to optimized data created by the just-in-time compiler.
4472    
4473         (k)   The   alternative   matching   functions   (pcre_dfa_exec()   and         (k)    The    alternative    matching    functions    (pcre_dfa_exec(),
4474         pcre16_dfa_exec()) match in a different way and are  not  Perl-compati-         pcre16_dfa_exec()  and pcre32_dfa_exec(),) match in a different way and
4475         ble.         are not Perl-compatible.
4476    
4477         (l)  PCRE  recognizes some special sequences such as (*CR) at the start         (l) PCRE recognizes some special sequences such as (*CR) at  the  start
4478         of a pattern that set overall options that cannot be changed within the         of a pattern that set overall options that cannot be changed within the
4479         pattern.         pattern.
4480    
# Line 3876  AUTHOR Line 4488  AUTHOR
4488    
4489  REVISION  REVISION
4490    
4491         Last updated: 01 June 2012         Last updated: 25 August 2012
4492         Copyright (c) 1997-2012 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
4493  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
4494    
4495    
4496  PCREPATTERN(3)                                                  PCREPATTERN(3)  PCREPATTERN(3)                                                  PCREPATTERN(3)
4497    
4498    
# Line 3907  PCRE REGULAR EXPRESSION DETAILS Line 4519