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2  This file contains a concatenation of the PCRE man pages, converted to plain  This file contains a concatenation of the PCRE man pages, converted to plain
3  text format for ease of searching with a text editor, or for use on systems  text format for ease of searching with a text editor, or for use on systems
4  that do not have a man page processor. The small individual files that give  that do not have a man page processor. The small individual files that give
5  synopses of each function in the library have not been included. There are  synopses of each function in the library have not been included. Neither has
6  separate text files for the pcregrep and pcretest commands.  the pcredemo program. There are separate text files for the pcregrep and
7    pcretest commands.
8  -----------------------------------------------------------------------------  -----------------------------------------------------------------------------
9    
10    
# Line 18  INTRODUCTION Line 19  INTRODUCTION
19    
20         The  PCRE  library is a set of functions that implement regular expres-         The  PCRE  library is a set of functions that implement regular expres-
21         sion pattern matching using the same syntax and semantics as Perl, with         sion pattern matching using the same syntax and semantics as Perl, with
22         just  a  few differences. (Certain features that appeared in Python and         just  a few differences. Some features that appeared in Python and PCRE
23         PCRE before they appeared in Perl are also available using  the  Python         before they appeared in Perl are also available using the  Python  syn-
24         syntax.)         tax,  there  is  some  support for one or two .NET and Oniguruma syntax
25           items, and there is an option for requesting some  minor  changes  that
26         The  current  implementation of PCRE (release 7.x) corresponds approxi-         give better JavaScript compatibility.
27         mately with Perl 5.10, including support for UTF-8 encoded strings  and  
28         Unicode general category properties. However, UTF-8 and Unicode support         Starting with release 8.30, it is possible to compile two separate PCRE
29           libraries:  the  original,  which  supports  8-bit  character   strings
30           (including  UTF-8  strings),  and a second library that supports 16-bit
31           character strings (including UTF-16 strings). The build process  allows
32           either  one  or both to be built. The majority of the work to make this
33           possible was done by Zoltan Herczeg.
34    
35           Starting with release 8.32 it is possible to compile a  third  separate
36           PCRE library, which supports 32-bit character strings (including UTF-32
37           strings). The build process allows any set of the 8-,  16-  and  32-bit
38           libraries. The work to make this possible was done by Christian Persch.
39    
40           The  three  libraries  contain identical sets of functions, except that
41           the names in the 16-bit library start with pcre16_  instead  of  pcre_,
42           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           nance load, most of the documentation describes the 8-bit library, with
45           the differences for the 16-bit and  32-bit  libraries  described  sepa-
46           rately  in  the  pcre16  and  pcre32  pages. References to functions or
47           structures of the  form  pcre[16|32]_xxx  should  be  read  as  meaning
48           "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         has to be explicitly enabled; it is not the default. The Unicode tables
55         correspond to Unicode release 5.0.0.         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 matching function that matches the same  compiled  patterns         alternative  function that matches the same compiled patterns in a dif-
59         in  a different way. In certain circumstances, the alternative function         ferent way. In certain circumstances, the alternative function has some
60         has some advantages. For a discussion of the two  matching  algorithms,         advantages.   For  a discussion of the two matching algorithms, see the
61         see the 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. This is now         Google Inc.  have provided a comprehensive C++ wrapper  for  the  8-bit
66         included as part of the PCRE distribution. The pcrecpp page has details         library.  This  is  now  included as part of the PCRE distribution. The
67         of  this  interface.  Other  people's contributions can be found in the         pcrecpp page has details of this interface.  Other  people's  contribu-
68         Contrib directory at the primary FTP site, which is:         tions  can  be  found in the Contrib directory at the primary FTP site,
69           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    
# Line 52  INTRODUCTION Line 79  INTRODUCTION
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 file         ing  PCRE  for various operating systems can be found in the README and
83         in the source distribution.         NON-AUTOTOOLS_BUILD files in the source distribution.
84    
85         The library 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_", which hopefully will not provoke         Their  names all begin with "_pcre_" or "_pcre16_" or "_pcre32_", which
89         any name clashes. In some environments, it is possible to control which         hopefully will not provoke any name clashes. In some  environments,  it
90         external  symbols  are  exported when a shared library is built, and in         is  possible  to  control  which  external  symbols are exported when a
91         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)" or "(*UTF)" turns on UTF-8 mode,
102           which interprets patterns and subjects as strings of  UTF-8  characters
103           instead  of  individual 8-bit characters.  This causes both the pattern
104           and any data against which it is matched to be checked for UTF-8 valid-
105           ity.  If  the  data  string is very long, such a check might use suffi-
106           ciently many resources as to cause your  application  to  lose  perfor-
107           mance.
108    
109           The  best  way  of  guarding  against  this  possibility  is to use the
110           pcre_fullinfo() function to check the compiled  pattern's  options  for
111           UTF.
112    
113           If  your  application  is one that supports UTF, be aware that validity
114           checking can take time. If the same data string is to be  matched  many
115           times, you can use the PCRE_NO_UTF[8|16|32]_CHECK option for the second
116           and subsequent matches to save redundant checks.
117    
118           Another way that performance can be hit is by running  a  pattern  that
119           has  a  very  large search tree against a string that will never match.
120           Nested unlimited repeats in a pattern are a common example.  PCRE  pro-
121           vides some protection against this: see the PCRE_EXTRA_MATCH_LIMIT fea-
122           ture in the pcreapi page.
123    
124    
125  USER DOCUMENTATION  USER DOCUMENTATION
# Line 69  USER DOCUMENTATION Line 127  USER DOCUMENTATION
127         The user documentation for PCRE comprises a number  of  different  sec-         The user documentation for PCRE comprises a number  of  different  sec-
128         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
129         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.
130         In  the  plain text format, all the sections are concatenated, for ease         In  the  plain  text format, all the sections, except the pcredemo sec-
131         of searching. The sections are as follows:         tion, are concatenated, for ease of searching. The sections are as fol-
132           lows:
133    
134           pcre              this document           pcre              this document
135             pcre16            details of the 16-bit library
136             pcre32            details of the 32-bit library
137           pcre-config       show PCRE installation configuration information           pcre-config       show PCRE installation configuration information
138           pcreapi           details of PCRE's native C API           pcreapi           details of PCRE's native C API
139           pcrebuild         options for building PCRE           pcrebuild         options for building PCRE
140           pcrecallout       details of the callout feature           pcrecallout       details of the callout feature
141           pcrecompat        discussion of Perl compatibility           pcrecompat        discussion of Perl compatibility
142           pcrecpp           details of the C++ wrapper           pcrecpp           details of the C++ wrapper for the 8-bit library
143           pcregrep          description of the pcregrep command           pcredemo          a demonstration C program that uses PCRE
144             pcregrep          description of the pcregrep command (8-bit only)
145             pcrejit           discussion of the just-in-time optimization support
146             pcrelimits        details of size and other limits
147           pcrematching      discussion of the two matching algorithms           pcrematching      discussion of the two matching algorithms
148           pcrepartial       details of the partial matching facility           pcrepartial       details of the partial matching facility
149           pcrepattern       syntax and semantics of supported           pcrepattern       syntax and semantics of supported
150                               regular expressions                               regular expressions
          pcresyntax        quick syntax reference  
151           pcreperform       discussion of performance issues           pcreperform       discussion of performance issues
152           pcreposix         the POSIX-compatible C API           pcreposix         the POSIX-compatible C API for the 8-bit library
153           pcreprecompile    details of saving and re-using precompiled patterns           pcreprecompile    details of saving and re-using precompiled patterns
154           pcresample        discussion of the sample program           pcresample        discussion of the pcredemo program
155           pcrestack         discussion of stack usage           pcrestack         discussion of stack usage
156             pcresyntax        quick syntax reference
157           pcretest          description of the pcretest testing command           pcretest          description of the pcretest testing command
158             pcreunicode       discussion of Unicode and UTF-8/16/32 support
159    
160         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
161         each C library function, listing its arguments and results.         each C library function, listing its arguments and results.
162    
163    
164  LIMITATIONS  AUTHOR
165    
166         There are some size limitations in PCRE but it is hoped that they  will         Philip Hazel
167         never in practice be relevant.         University Computing Service
168           Cambridge CB2 3QH, England.
169    
170         The  maximum  length of a compiled pattern is 65539 (sic) bytes if PCRE         Putting an actual email address here seems to have been a spam  magnet,
171         is compiled with the default internal linkage size of 2. If you want to         so  I've  taken  it away. If you want to email me, use my two initials,
172         process  regular  expressions  that are truly enormous, you can compile         followed by the two digits 10, at the domain cam.ac.uk.
        PCRE with an internal linkage size of 3 or 4 (see the  README  file  in  
        the  source  distribution and the pcrebuild documentation for details).  
        In these cases the limit is substantially larger.  However,  the  speed  
        of execution is slower.  
173    
        All values in repeating quantifiers must be less than 65536.  
174    
175         There is no limit to the number of parenthesized subpatterns, but there  REVISION
        can be no more than 65535 capturing subpatterns.  
176    
177         The maximum length of name for a named subpattern is 32 characters, and         Last updated: 11 November 2012
178         the maximum number of named subpatterns is 10000.         Copyright (c) 1997-2012 University of Cambridge.
179    ------------------------------------------------------------------------------
180    
        The  maximum  length of a subject string is the largest positive number  
        that an integer variable can hold. However, when using the  traditional  
        matching function, PCRE uses recursion to handle subpatterns and indef-  
        inite repetition.  This means that the available stack space may  limit  
        the size of a subject string that can be processed by certain patterns.  
        For a discussion of stack issues, see the pcrestack documentation.  
181    
182    PCRE(3)                                                                PCRE(3)
183    
184    
185    NAME
186           PCRE - Perl-compatible regular expressions
187    
188           #include <pcre.h>
189    
190    
191    PCRE 16-BIT API BASIC FUNCTIONS
192    
193           pcre16 *pcre16_compile(PCRE_SPTR16 pattern, int options,
194                const char **errptr, int *erroffset,
195                const unsigned char *tableptr);
196    
197           pcre16 *pcre16_compile2(PCRE_SPTR16 pattern, int options,
198                int *errorcodeptr,
199                const char **errptr, int *erroffset,
200                const unsigned char *tableptr);
201    
202           pcre16_extra *pcre16_study(const pcre16 *code, int options,
203                const char **errptr);
204    
205           void pcre16_free_study(pcre16_extra *extra);
206    
207           int pcre16_exec(const pcre16 *code, const pcre16_extra *extra,
208                PCRE_SPTR16 subject, int length, int startoffset,
209                int options, int *ovector, int ovecsize);
210    
211           int pcre16_dfa_exec(const pcre16 *code, const pcre16_extra *extra,
212                PCRE_SPTR16 subject, int length, int startoffset,
213                int options, int *ovector, int ovecsize,
214                int *workspace, int wscount);
215    
216    
217    PCRE 16-BIT API STRING EXTRACTION FUNCTIONS
218    
219           int pcre16_copy_named_substring(const pcre16 *code,
220                PCRE_SPTR16 subject, int *ovector,
221                int stringcount, PCRE_SPTR16 stringname,
222                PCRE_UCHAR16 *buffer, int buffersize);
223    
224           int pcre16_copy_substring(PCRE_SPTR16 subject, int *ovector,
225                int stringcount, int stringnumber, PCRE_UCHAR16 *buffer,
226                int buffersize);
227    
228           int pcre16_get_named_substring(const pcre16 *code,
229                PCRE_SPTR16 subject, int *ovector,
230                int stringcount, PCRE_SPTR16 stringname,
231                PCRE_SPTR16 *stringptr);
232    
233           int pcre16_get_stringnumber(const pcre16 *code,
234                PCRE_SPTR16 name);
235    
236           int pcre16_get_stringtable_entries(const pcre16 *code,
237                PCRE_SPTR16 name, PCRE_UCHAR16 **first, PCRE_UCHAR16 **last);
238    
239           int pcre16_get_substring(PCRE_SPTR16 subject, int *ovector,
240                int stringcount, int stringnumber,
241                PCRE_SPTR16 *stringptr);
242    
243           int pcre16_get_substring_list(PCRE_SPTR16 subject,
244                int *ovector, int stringcount, PCRE_SPTR16 **listptr);
245    
246           void pcre16_free_substring(PCRE_SPTR16 stringptr);
247    
248           void pcre16_free_substring_list(PCRE_SPTR16 *stringptr);
249    
250    
251    PCRE 16-BIT API AUXILIARY FUNCTIONS
252    
253           pcre16_jit_stack *pcre16_jit_stack_alloc(int startsize, int maxsize);
254    
255           void pcre16_jit_stack_free(pcre16_jit_stack *stack);
256    
257           void pcre16_assign_jit_stack(pcre16_extra *extra,
258                pcre16_jit_callback callback, void *data);
259    
260           const unsigned char *pcre16_maketables(void);
261    
262           int pcre16_fullinfo(const pcre16 *code, const pcre16_extra *extra,
263                int what, void *where);
264    
265           int pcre16_refcount(pcre16 *code, int adjust);
266    
267           int pcre16_config(int what, void *where);
268    
269           const char *pcre16_version(void);
270    
271           int pcre16_pattern_to_host_byte_order(pcre16 *code,
272                pcre16_extra *extra, const unsigned char *tables);
273    
274    
275    PCRE 16-BIT API INDIRECTED FUNCTIONS
276    
277           void *(*pcre16_malloc)(size_t);
278    
279           void (*pcre16_free)(void *);
280    
281           void *(*pcre16_stack_malloc)(size_t);
282    
283           void (*pcre16_stack_free)(void *);
284    
285           int (*pcre16_callout)(pcre16_callout_block *);
286    
287    
288    PCRE 16-BIT API 16-BIT-ONLY FUNCTION
289    
290           int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *output,
291                PCRE_SPTR16 input, int length, int *byte_order,
292                int keep_boms);
293    
294    
295    THE PCRE 16-BIT LIBRARY
296    
297           Starting  with  release  8.30, it is possible to compile a PCRE library
298           that supports 16-bit character strings, including  UTF-16  strings,  as
299           well  as  or instead of the original 8-bit library. The majority of the
300           work to make  this  possible  was  done  by  Zoltan  Herczeg.  The  two
301           libraries contain identical sets of functions, used in exactly the same
302           way. Only the names of the functions and the data types of their  argu-
303           ments  and results are different. To avoid over-complication and reduce
304           the documentation maintenance load,  most  of  the  PCRE  documentation
305           describes  the  8-bit  library,  with only occasional references to the
306           16-bit library. This page describes what is different when you use  the
307           16-bit library.
308    
309           WARNING:  A  single  application can be linked with both libraries, but
310           you must take care when processing any particular pattern to use  func-
311           tions  from  just one library. For example, if you want to study a pat-
312           tern that was compiled with  pcre16_compile(),  you  must  do  so  with
313           pcre16_study(), not pcre_study(), and you must free the study data with
314           pcre16_free_study().
315    
316    
317    THE HEADER FILE
318    
319           There is only one header file, pcre.h. It contains prototypes  for  all
320           the functions in all libraries, as well as definitions of flags, struc-
321           tures, error codes, etc.
322    
323    
324    THE LIBRARY NAME
325    
326           In Unix-like systems, the 16-bit library is called libpcre16,  and  can
327           normally  be  accesss  by adding -lpcre16 to the command for linking an
328           application that uses PCRE.
329    
330    
331    STRING TYPES
332    
333           In the 8-bit library, strings are passed to PCRE library  functions  as
334           vectors  of  bytes  with  the  C  type "char *". In the 16-bit library,
335           strings are passed as vectors of unsigned 16-bit quantities. The  macro
336           PCRE_UCHAR16  specifies  an  appropriate  data type, and PCRE_SPTR16 is
337           defined as "const PCRE_UCHAR16 *". In very  many  environments,  "short
338           int" is a 16-bit data type. When PCRE is built, it defines PCRE_UCHAR16
339           as "unsigned short int", but checks that it really  is  a  16-bit  data
340           type.  If  it is not, the build fails with an error message telling the
341           maintainer to modify the definition appropriately.
342    
343    
344    STRUCTURE TYPES
345    
346           The types of the opaque structures that are used  for  compiled  16-bit
347           patterns  and  JIT stacks are pcre16 and pcre16_jit_stack respectively.
348           The  type  of  the  user-accessible  structure  that  is  returned   by
349           pcre16_study()  is  pcre16_extra, and the type of the structure that is
350           used for passing data to a callout  function  is  pcre16_callout_block.
351           These structures contain the same fields, with the same names, as their
352           8-bit counterparts. The only difference is that pointers  to  character
353           strings are 16-bit instead of 8-bit types.
354    
355    
356    16-BIT FUNCTIONS
357    
358           For  every function in the 8-bit library there is a corresponding func-
359           tion in the 16-bit library with a name that starts with pcre16_ instead
360           of  pcre_.  The  prototypes are listed above. In addition, there is one
361           extra function, pcre16_utf16_to_host_byte_order(). This  is  a  utility
362           function  that converts a UTF-16 character string to host byte order if
363           necessary. The other 16-bit  functions  expect  the  strings  they  are
364           passed to be in host byte order.
365    
366           The input and output arguments of pcre16_utf16_to_host_byte_order() may
367           point to the same address, that is, conversion in place  is  supported.
368           The output buffer must be at least as long as the input.
369    
370           The  length  argument  specifies the number of 16-bit data units in the
371           input string; a negative value specifies a zero-terminated string.
372    
373           If byte_order is NULL, it is assumed that the string starts off in host
374           byte  order. This may be changed by byte-order marks (BOMs) anywhere in
375           the string (commonly as the first character).
376    
377           If byte_order is not NULL, a non-zero value of the integer to which  it
378           points  means  that  the input starts off in host byte order, otherwise
379           the opposite order is assumed. Again, BOMs in  the  string  can  change
380           this. The final byte order is passed back at the end of processing.
381    
382           If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
383           copied into the output string. Otherwise they are discarded.
384    
385           The result of the function is the number of 16-bit  units  placed  into
386           the  output  buffer,  including  the  zero terminator if the string was
387           zero-terminated.
388    
389    
390    SUBJECT STRING OFFSETS
391    
392           The offsets within subject strings that are returned  by  the  matching
393           functions are in 16-bit units rather than bytes.
394    
395    
396    NAMED SUBPATTERNS
397    
398           The  name-to-number translation table that is maintained for named sub-
399           patterns uses 16-bit characters.  The  pcre16_get_stringtable_entries()
400           function returns the length of each entry in the table as the number of
401           16-bit data units.
402    
403    
404    OPTION NAMES
405    
406           There   are   two   new   general   option   names,   PCRE_UTF16    and
407           PCRE_NO_UTF16_CHECK,     which     correspond    to    PCRE_UTF8    and
408           PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
409           define  the  same bits in the options word. There is a discussion about
410           the validity of UTF-16 strings in the pcreunicode page.
411    
412           For the pcre16_config() function there is an  option  PCRE_CONFIG_UTF16
413           that  returns  1  if UTF-16 support is configured, otherwise 0. If this
414           option  is  given  to  pcre_config()  or  pcre32_config(),  or  if  the
415           PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF32  option is given to pcre16_con-
416           fig(), the result is the PCRE_ERROR_BADOPTION error.
417    
418    
419    CHARACTER CODES
420    
421           In 16-bit mode, when  PCRE_UTF16  is  not  set,  character  values  are
422           treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
423           that they can range from 0 to 0xffff instead of 0  to  0xff.  Character
424           types  for characters less than 0xff can therefore be influenced by the
425           locale in the same way as before.  Characters greater  than  0xff  have
426           only one case, and no "type" (such as letter or digit).
427    
428           In  UTF-16  mode,  the  character  code  is  Unicode, in the range 0 to
429           0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
430           because  those  are "surrogate" values that are used in pairs to encode
431           values greater than 0xffff.
432    
433           A UTF-16 string can indicate its endianness by special code knows as  a
434           byte-order mark (BOM). The PCRE functions do not handle this, expecting
435           strings  to  be  in  host  byte  order.  A  utility   function   called
436           pcre16_utf16_to_host_byte_order()  is  provided  to help with this (see
437           above).
438    
439    
440    ERROR NAMES
441    
442           The errors PCRE_ERROR_BADUTF16_OFFSET and PCRE_ERROR_SHORTUTF16  corre-
443           spond  to  their  8-bit  counterparts.  The error PCRE_ERROR_BADMODE is
444           given when a compiled pattern is passed to a  function  that  processes
445           patterns  in  the  other  mode, for example, if a pattern compiled with
446           pcre_compile() is passed to pcre16_exec().
447    
448           There are new error codes whose names  begin  with  PCRE_UTF16_ERR  for
449           invalid  UTF-16  strings,  corresponding to the PCRE_UTF8_ERR codes for
450           UTF-8 strings that are described in the section entitled "Reason  codes
451           for  invalid UTF-8 strings" in the main pcreapi page. The UTF-16 errors
452           are:
453    
454             PCRE_UTF16_ERR1  Missing low surrogate at end of string
455             PCRE_UTF16_ERR2  Invalid low surrogate follows high surrogate
456             PCRE_UTF16_ERR3  Isolated low surrogate
457             PCRE_UTF16_ERR4  Non-character
458    
459    
460    ERROR TEXTS
461    
462           If there is an error while compiling a pattern, the error text that  is
463           passed  back by pcre16_compile() or pcre16_compile2() is still an 8-bit
464           character string, zero-terminated.
465    
466    
467    CALLOUTS
468    
469           The subject and mark fields in the callout block that is  passed  to  a
470           callout function point to 16-bit vectors.
471    
472    
473    TESTING
474    
475           The  pcretest  program continues to operate with 8-bit input and output
476           files, but it can be used for testing the 16-bit library. If it is  run
477           with the command line option -16, patterns and subject strings are con-
478           verted from 8-bit to 16-bit before being passed to PCRE, and the 16-bit
479           library  functions  are used instead of the 8-bit ones. Returned 16-bit
480           strings are converted to 8-bit for output. If both the  8-bit  and  the
481           32-bit libraries were not compiled, pcretest defaults to 16-bit and the
482           -16 option is ignored.
483    
484           When PCRE is being built, the RunTest script that is  called  by  "make
485           check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
486           16-bit and 32-bit libraries has been built, and runs the  tests  appro-
487           priately.
488    
489    
490    NOT SUPPORTED IN 16-BIT MODE
491    
492           Not all the features of the 8-bit library are available with the 16-bit
493           library. The C++ and POSIX wrapper functions  support  only  the  8-bit
494           library, and the pcregrep program is at present 8-bit only.
495    
496    
497    AUTHOR
498    
499           Philip Hazel
500           University Computing Service
501           Cambridge CB2 3QH, England.
502    
503    
504    REVISION
505    
506           Last updated: 08 November 2012
507           Copyright (c) 1997-2012 University of Cambridge.
508    ------------------------------------------------------------------------------
509    
510    
511    PCRE(3)                                                                PCRE(3)
512    
513    
514    NAME
515           PCRE - Perl-compatible regular expressions
516    
517           #include <pcre.h>
518    
519    
520    PCRE 32-BIT API BASIC FUNCTIONS
521    
522           pcre32 *pcre32_compile(PCRE_SPTR32 pattern, int options,
523                const char **errptr, int *erroffset,
524                const unsigned char *tableptr);
525    
526           pcre32 *pcre32_compile2(PCRE_SPTR32 pattern, int options,
527                int *errorcodeptr,
528                const char **errptr, int *erroffset,
529                const unsigned char *tableptr);
530    
531           pcre32_extra *pcre32_study(const pcre32 *code, int options,
532                const char **errptr);
533    
534           void pcre32_free_study(pcre32_extra *extra);
535    
536           int pcre32_exec(const pcre32 *code, const pcre32_extra *extra,
537                PCRE_SPTR32 subject, int length, int startoffset,
538                int options, int *ovector, int ovecsize);
539    
540           int pcre32_dfa_exec(const pcre32 *code, const pcre32_extra *extra,
541                PCRE_SPTR32 subject, int length, int startoffset,
542                int options, int *ovector, int ovecsize,
543                int *workspace, int wscount);
544    
545    
546    PCRE 32-BIT API STRING EXTRACTION FUNCTIONS
547    
548           int pcre32_copy_named_substring(const pcre32 *code,
549                PCRE_SPTR32 subject, int *ovector,
550                int stringcount, PCRE_SPTR32 stringname,
551                PCRE_UCHAR32 *buffer, int buffersize);
552    
553           int pcre32_copy_substring(PCRE_SPTR32 subject, int *ovector,
554                int stringcount, int stringnumber, PCRE_UCHAR32 *buffer,
555                int buffersize);
556    
557           int pcre32_get_named_substring(const pcre32 *code,
558                PCRE_SPTR32 subject, int *ovector,
559                int stringcount, PCRE_SPTR32 stringname,
560                PCRE_SPTR32 *stringptr);
561    
562           int pcre32_get_stringnumber(const pcre32 *code,
563                PCRE_SPTR32 name);
564    
565           int pcre32_get_stringtable_entries(const pcre32 *code,
566                PCRE_SPTR32 name, PCRE_UCHAR32 **first, PCRE_UCHAR32 **last);
567    
568           int pcre32_get_substring(PCRE_SPTR32 subject, int *ovector,
569                int stringcount, int stringnumber,
570                PCRE_SPTR32 *stringptr);
571    
572           int pcre32_get_substring_list(PCRE_SPTR32 subject,
573                int *ovector, int stringcount, PCRE_SPTR32 **listptr);
574    
575           void pcre32_free_substring(PCRE_SPTR32 stringptr);
576    
577           void pcre32_free_substring_list(PCRE_SPTR32 *stringptr);
578    
579    
580    PCRE 32-BIT API AUXILIARY FUNCTIONS
581    
582           pcre32_jit_stack *pcre32_jit_stack_alloc(int startsize, int maxsize);
583    
584           void pcre32_jit_stack_free(pcre32_jit_stack *stack);
585    
586           void pcre32_assign_jit_stack(pcre32_extra *extra,
587                pcre32_jit_callback callback, void *data);
588    
589           const unsigned char *pcre32_maketables(void);
590    
591           int pcre32_fullinfo(const pcre32 *code, const pcre32_extra *extra,
592                int what, void *where);
593    
594           int pcre32_refcount(pcre32 *code, int adjust);
595    
596           int pcre32_config(int what, void *where);
597    
598           const char *pcre32_version(void);
599    
600           int pcre32_pattern_to_host_byte_order(pcre32 *code,
601                pcre32_extra *extra, const unsigned char *tables);
602    
603    
604    PCRE 32-BIT API INDIRECTED FUNCTIONS
605    
606           void *(*pcre32_malloc)(size_t);
607    
608           void (*pcre32_free)(void *);
609    
610           void *(*pcre32_stack_malloc)(size_t);
611    
612           void (*pcre32_stack_free)(void *);
613    
614           int (*pcre32_callout)(pcre32_callout_block *);
615    
616    
617    PCRE 32-BIT API 32-BIT-ONLY FUNCTION
618    
619           int pcre32_utf32_to_host_byte_order(PCRE_UCHAR32 *output,
620                PCRE_SPTR32 input, int length, int *byte_order,
621                int keep_boms);
622    
623    
624    THE PCRE 32-BIT LIBRARY
625    
626           Starting  with  release  8.32, it is possible to compile a PCRE library
627           that supports 32-bit character strings, including  UTF-32  strings,  as
628           well as or instead of the original 8-bit library. This work was done by
629           Christian Persch, based on the work done  by  Zoltan  Herczeg  for  the
630           16-bit  library.  All  three  libraries contain identical sets of func-
631           tions, used in exactly the same way.  Only the names of  the  functions
632           and  the  data  types  of their arguments and results are different. To
633           avoid over-complication and reduce the documentation maintenance  load,
634           most  of  the PCRE documentation describes the 8-bit library, with only
635           occasional references to the 16-bit and  32-bit  libraries.  This  page
636           describes what is different when you use the 32-bit library.
637    
638           WARNING:  A  single  application  can  be linked with all or any of the
639           three libraries, but you must take care when processing any  particular
640           pattern  to  use  functions  from just one library. For example, if you
641           want to study a pattern that was compiled  with  pcre32_compile(),  you
642           must do so with pcre32_study(), not pcre_study(), and you must free the
643           study data with pcre32_free_study().
644    
645    
646    THE HEADER FILE
647    
648           There is only one header file, pcre.h. It contains prototypes  for  all
649           the functions in all libraries, as well as definitions of flags, struc-
650           tures, error codes, etc.
651    
652    
653    THE LIBRARY NAME
654    
655           In Unix-like systems, the 32-bit library is called libpcre32,  and  can
656           normally  be  accesss  by adding -lpcre32 to the command for linking an
657           application that uses PCRE.
658    
659    
660    STRING TYPES
661    
662           In the 8-bit library, strings are passed to PCRE library  functions  as
663           vectors  of  bytes  with  the  C  type "char *". In the 32-bit library,
664           strings are passed as vectors of unsigned 32-bit quantities. The  macro
665           PCRE_UCHAR32  specifies  an  appropriate  data type, and PCRE_SPTR32 is
666           defined as "const PCRE_UCHAR32 *". In very many environments, "unsigned
667           int" is a 32-bit data type. When PCRE is built, it defines PCRE_UCHAR32
668           as "unsigned int", but checks that it really is a 32-bit data type.  If
669           it is not, the build fails with an error message telling the maintainer
670           to modify the definition appropriately.
671    
672    
673    STRUCTURE TYPES
674    
675           The types of the opaque structures that are used  for  compiled  32-bit
676           patterns  and  JIT stacks are pcre32 and pcre32_jit_stack respectively.
677           The  type  of  the  user-accessible  structure  that  is  returned   by
678           pcre32_study()  is  pcre32_extra, and the type of the structure that is
679           used for passing data to a callout  function  is  pcre32_callout_block.
680           These structures contain the same fields, with the same names, as their
681           8-bit counterparts. The only difference is that pointers  to  character
682           strings are 32-bit instead of 8-bit types.
683    
684    
685    32-BIT FUNCTIONS
686    
687           For  every function in the 8-bit library there is a corresponding func-
688           tion in the 32-bit library with a name that starts with pcre32_ instead
689           of  pcre_.  The  prototypes are listed above. In addition, there is one
690           extra function, pcre32_utf32_to_host_byte_order(). This  is  a  utility
691           function  that converts a UTF-32 character string to host byte order if
692           necessary. The other 32-bit  functions  expect  the  strings  they  are
693           passed to be in host byte order.
694    
695           The input and output arguments of pcre32_utf32_to_host_byte_order() may
696           point to the same address, that is, conversion in place  is  supported.
697           The output buffer must be at least as long as the input.
698    
699           The  length  argument  specifies the number of 32-bit data units in the
700           input string; a negative value specifies a zero-terminated string.
701    
702           If byte_order is NULL, it is assumed that the string starts off in host
703           byte  order. This may be changed by byte-order marks (BOMs) anywhere in
704           the string (commonly as the first character).
705    
706           If byte_order is not NULL, a non-zero value of the integer to which  it
707           points  means  that  the input starts off in host byte order, otherwise
708           the opposite order is assumed. Again, BOMs in  the  string  can  change
709           this. The final byte order is passed back at the end of processing.
710    
711           If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
712           copied into the output string. Otherwise they are discarded.
713    
714           The result of the function is the number of 32-bit  units  placed  into
715           the  output  buffer,  including  the  zero terminator if the string was
716           zero-terminated.
717    
718    
719    SUBJECT STRING OFFSETS
720    
721           The offsets within subject strings that are returned  by  the  matching
722           functions are in 32-bit units rather than bytes.
723    
724    
725    NAMED SUBPATTERNS
726    
727           The  name-to-number translation table that is maintained for named sub-
728           patterns uses 32-bit characters.  The  pcre32_get_stringtable_entries()
729           function returns the length of each entry in the table as the number of
730           32-bit data units.
731    
732    
733    OPTION NAMES
734    
735           There   are   two   new   general   option   names,   PCRE_UTF32    and
736           PCRE_NO_UTF32_CHECK,     which     correspond    to    PCRE_UTF8    and
737           PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
738           define  the  same bits in the options word. There is a discussion about
739           the validity of UTF-32 strings in the pcreunicode page.
740    
741           For the pcre32_config() function there is an  option  PCRE_CONFIG_UTF32
742           that  returns  1  if UTF-32 support is configured, otherwise 0. If this
743           option  is  given  to  pcre_config()  or  pcre16_config(),  or  if  the
744           PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF16  option is given to pcre32_con-
745           fig(), the result is the PCRE_ERROR_BADOPTION error.
746    
747    
748    CHARACTER CODES
749    
750           In 32-bit mode, when  PCRE_UTF32  is  not  set,  character  values  are
751           treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
752           that they can range from 0 to 0x7fffffff instead of 0 to 0xff.  Charac-
753           ter  types for characters less than 0xff can therefore be influenced by
754           the locale in the same way as before.   Characters  greater  than  0xff
755           have only one case, and no "type" (such as letter or digit).
756    
757           In  UTF-32  mode,  the  character  code  is  Unicode, in the range 0 to
758           0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
759           because those are "surrogate" values that are ill-formed in UTF-32.
760    
761           A  UTF-32 string can indicate its endianness by special code knows as a
762           byte-order mark (BOM). The PCRE functions do not handle this, expecting
763           strings   to   be  in  host  byte  order.  A  utility  function  called
764           pcre32_utf32_to_host_byte_order() is provided to help  with  this  (see
765           above).
766    
767    
768    ERROR NAMES
769    
770           The  error  PCRE_ERROR_BADUTF32  corresponds  to its 8-bit counterpart.
771           The error PCRE_ERROR_BADMODE is given when a compiled pattern is passed
772           to  a  function that processes patterns in the other mode, for example,
773           if a pattern compiled with pcre_compile() is passed to pcre32_exec().
774    
775           There are new error codes whose names  begin  with  PCRE_UTF32_ERR  for
776           invalid  UTF-32  strings,  corresponding to the PCRE_UTF8_ERR codes for
777           UTF-8 strings that are described in the section entitled "Reason  codes
778           for  invalid UTF-8 strings" in the main pcreapi page. The UTF-32 errors
779           are:
780    
781             PCRE_UTF32_ERR1  Surrogate character (range from 0xd800 to 0xdfff)
782             PCRE_UTF32_ERR2  Non-character
783             PCRE_UTF32_ERR3  Character > 0x10ffff
784    
785    
786    ERROR TEXTS
787    
788           If there is an error while compiling a pattern, the error text that  is
789           passed  back by pcre32_compile() or pcre32_compile2() is still an 8-bit
790           character string, zero-terminated.
791    
792    
793    CALLOUTS
794    
795           The subject and mark fields in the callout block that is  passed  to  a
796           callout function point to 32-bit vectors.
797    
798    
799    TESTING
800    
801           The  pcretest  program continues to operate with 8-bit input and output
802           files, but it can be used for testing the 32-bit library. If it is  run
803           with the command line option -32, patterns and subject strings are con-
804           verted from 8-bit to 32-bit before being passed to PCRE, and the 32-bit
805           library  functions  are used instead of the 8-bit ones. Returned 32-bit
806           strings are converted to 8-bit for output. If both the  8-bit  and  the
807           16-bit libraries were not compiled, pcretest defaults to 32-bit and the
808           -32 option is ignored.
809    
810           When PCRE is being built, the RunTest script that is  called  by  "make
811           check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
812           16-bit and 32-bit libraries has been built, and runs the  tests  appro-
813           priately.
814    
 UTF-8 AND UNICODE PROPERTY SUPPORT  
815    
816         From release 3.3, PCRE has  had  some  support  for  character  strings  NOT SUPPORTED IN 32-BIT MODE
        encoded  in the UTF-8 format. For release 4.0 this was greatly extended  
        to cover most common requirements, and in release 5.0  additional  sup-  
        port for Unicode general category properties was added.  
   
        In  order  process  UTF-8 strings, you must build PCRE to include UTF-8  
        support in the code, and, in addition,  you  must  call  pcre_compile()  
        with  the PCRE_UTF8 option flag. When you do this, both the pattern and  
        any subject strings that are matched against it are  treated  as  UTF-8  
        strings instead of just strings of bytes.  
   
        If  you compile PCRE with UTF-8 support, but do not use it at run time,  
        the library will be a bit bigger, but the additional run time  overhead  
        is limited to testing the PCRE_UTF8 flag occasionally, so should not be  
        very big.  
817    
818         If PCRE is built with Unicode character property support (which implies         Not all the features of the 8-bit library are available with the 32-bit
819         UTF-8  support),  the  escape sequences \p{..}, \P{..}, and \X are sup-         library. The C++ and POSIX wrapper functions  support  only  the  8-bit
820         ported.  The available properties that can be tested are limited to the         library, and the pcregrep program is at present 8-bit only.
        general  category  properties such as Lu for an upper case letter or Nd  
        for a decimal number, the Unicode script names such as Arabic  or  Han,  
        and  the  derived  properties  Any  and L&. A full list is given in the  
        pcrepattern documentation. Only the short names for properties are sup-  
        ported.  For example, \p{L} matches a letter. Its Perl synonym, \p{Let-  
        ter}, is not supported.  Furthermore,  in  Perl,  many  properties  may  
        optionally  be  prefixed by "Is", for compatibility with Perl 5.6. PCRE  
        does not support this.  
   
        The following comments apply when PCRE is running in UTF-8 mode:  
   
        1. When you set the PCRE_UTF8 flag, the strings passed as patterns  and  
        subjects  are  checked for validity on entry to the relevant functions.  
        If an invalid UTF-8 string is passed, an error return is given. In some  
        situations,  you  may  already  know  that  your strings are valid, and  
        therefore want to skip these checks in order to improve performance. If  
        you  set  the  PCRE_NO_UTF8_CHECK  flag at compile time or at run time,  
        PCRE assumes that the pattern or subject  it  is  given  (respectively)  
        contains  only valid UTF-8 codes. In this case, it does not diagnose an  
        invalid UTF-8 string. If you pass an invalid UTF-8 string to PCRE  when  
        PCRE_NO_UTF8_CHECK  is set, the results are undefined. Your program may  
        crash.  
   
        2. An unbraced hexadecimal escape sequence (such  as  \xb3)  matches  a  
        two-byte UTF-8 character if the value is greater than 127.  
   
        3.  Octal  numbers  up to \777 are recognized, and match two-byte UTF-8  
        characters for values greater than \177.  
   
        4. Repeat quantifiers apply to complete UTF-8 characters, not to  indi-  
        vidual bytes, for example: \x{100}{3}.  
   
        5.  The dot metacharacter matches one UTF-8 character instead of a sin-  
        gle byte.  
   
        6. The escape sequence \C can be used to match a single byte  in  UTF-8  
        mode,  but  its  use can lead to some strange effects. This facility is  
        not available in the alternative matching function, pcre_dfa_exec().  
   
        7. The character escapes \b, \B, \d, \D, \s, \S, \w, and  \W  correctly  
        test  characters of any code value, but the characters that PCRE recog-  
        nizes as digits, spaces, or word characters  remain  the  same  set  as  
        before, all with values less than 256. This remains true even when PCRE  
        includes Unicode property support, because to do otherwise  would  slow  
        down  PCRE in many common cases. If you really want to test for a wider  
        sense of, say, "digit", you must use Unicode  property  tests  such  as  
        \p{Nd}.  
   
        8.  Similarly,  characters that match the POSIX named character classes  
        are all low-valued characters.  
   
        9. However, the Perl 5.10 horizontal and vertical  whitespace  matching  
        escapes (\h, \H, \v, and \V) do match all the appropriate Unicode char-  
        acters.  
   
        10. Case-insensitive matching applies only to characters  whose  values  
        are  less than 128, unless PCRE is built with Unicode property support.  
        Even when Unicode property support is available, PCRE  still  uses  its  
        own  character  tables when checking the case of low-valued characters,  
        so as not to degrade performance.  The Unicode property information  is  
        used only for characters with higher values. Even when Unicode property  
        support is available, PCRE supports case-insensitive matching only when  
        there  is  a  one-to-one  mapping between a letter's cases. There are a  
        small number of many-to-one mappings in Unicode;  these  are  not  sup-  
        ported by PCRE.  
821    
822    
823  AUTHOR  AUTHOR
# Line 219  AUTHOR Line 826  AUTHOR
826         University Computing Service         University Computing Service
827         Cambridge CB2 3QH, England.         Cambridge CB2 3QH, England.
828    
        Putting  an actual email address here seems to have been a spam magnet,  
        so I've taken it away. If you want to email me, use  my  two  initials,  
        followed by the two digits 10, at the domain cam.ac.uk.  
   
829    
830  REVISION  REVISION
831    
832         Last updated: 06 August 2007         Last updated: 08 November 2012
833         Copyright (c) 1997-2007 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
834  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
835    
836    
# Line 241  NAME Line 844  NAME
844  PCRE BUILD-TIME OPTIONS  PCRE BUILD-TIME OPTIONS
845    
846         This  document  describes  the  optional  features  of PCRE that can be         This  document  describes  the  optional  features  of PCRE that can be
847         selected when the library is compiled. They are all selected, or  dese-         selected when the library is compiled. It assumes use of the  configure
848         lected, by providing options to the configure script that is run before         script,  where the optional features are selected or deselected by pro-
849         the make command. The complete list of  options  for  configure  (which         viding options to configure before running the make  command.  However,
850         includes  the  standard  ones such as the selection of the installation         the  same  options  can be selected in both Unix-like and non-Unix-like
851         directory) can be obtained by running         environments using the GUI facility of cmake-gui if you are using CMake
852           instead of configure to build PCRE.
853    
854           There  is a lot more information about building PCRE without using con-
855           figure (including information about using CMake or building "by  hand")
856           in  the file called NON-AUTOTOOLS-BUILD, which is part of the PCRE dis-
857           tribution. You should consult this file as well as the README  file  if
858           you are building in a non-Unix-like environment.
859    
860           The complete list of options for configure (which includes the standard
861           ones such as the  selection  of  the  installation  directory)  can  be
862           obtained by running
863    
864           ./configure --help           ./configure --help
865    
866         The following sections include  descriptions  of  options  whose  names         The  following  sections  include  descriptions  of options whose names
867         begin with --enable or --disable. These settings specify changes to the         begin with --enable or --disable. These settings specify changes to the
868         defaults for the configure command. Because of the way  that  configure         defaults  for  the configure command. Because of the way that configure
869         works,  --enable  and --disable always come in pairs, so the complemen-         works, --enable and --disable always come in pairs, so  the  complemen-
870         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
871         is not described.         is not described.
872    
873    
874    BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES
875    
876           By default, a library called libpcre  is  built,  containing  functions
877           that  take  string  arguments  contained in vectors of bytes, either as
878           single-byte characters, or interpreted as UTF-8 strings. You  can  also
879           build  a  separate library, called libpcre16, in which strings are con-
880           tained in vectors of 16-bit data units and interpreted either  as  sin-
881           gle-unit characters or UTF-16 strings, by adding
882    
883             --enable-pcre16
884    
885           to the configure command. You can also build a separate library, called
886           libpcre32, in which strings are contained in  vectors  of  32-bit  data
887           units  and  interpreted  either  as  single-unit  characters  or UTF-32
888           strings, by adding
889    
890             --enable-pcre32
891    
892           to the configure command. If you do not want the 8-bit library, add
893    
894             --disable-pcre8
895    
896           as well. At least one of the three libraries must be built.  Note  that
897           the  C++  and  POSIX  wrappers are for the 8-bit library only, and that
898           pcregrep is an 8-bit program. None of these are  built  if  you  select
899           only the 16-bit or 32-bit libraries.
900    
901    
902    BUILDING SHARED AND STATIC LIBRARIES
903    
904           The  PCRE building process uses libtool to build both shared and static
905           Unix libraries by default. You can suppress one of these by adding  one
906           of
907    
908             --disable-shared
909             --disable-static
910    
911           to the configure command, as required.
912    
913    
914  C++ SUPPORT  C++ SUPPORT
915    
916         By default, the configure script will search for a C++ compiler and C++         By  default,  if the 8-bit library is being built, the configure script
917         header files. If it finds them, it automatically builds the C++ wrapper         will search for a C++ compiler and C++ header files. If it finds  them,
918         library for PCRE. You can disable this by adding         it  automatically  builds  the C++ wrapper library (which supports only
919           8-bit strings). You can disable this by adding
920    
921           --disable-cpp           --disable-cpp
922    
923         to the configure command.         to the configure command.
924    
925    
926  UTF-8 SUPPORT  UTF-8, UTF-16 AND UTF-32 SUPPORT
927    
928         To build PCRE with support for UTF-8 character strings, add         To build PCRE with support for UTF Unicode character strings, add
929    
930           --enable-utf8           --enable-utf
931    
932         to  the  configure  command.  Of  itself, this does not make PCRE treat         to the configure command. This setting applies to all three  libraries,
933         strings as UTF-8. As well as compiling PCRE with this option, you  also         adding  support  for  UTF-8 to the 8-bit library, support for UTF-16 to
934         have  have to set the PCRE_UTF8 option when you call the pcre_compile()         the 16-bit library, and  support  for  UTF-32  to  the  to  the  32-bit
935         function.         library.  There  are no separate options for enabling UTF-8, UTF-16 and
936           UTF-32 independently because that would allow ridiculous settings  such
937           as  requesting UTF-16 support while building only the 8-bit library. It
938           is not possible to build one library with UTF support and another with-
939           out  in the same configuration. (For backwards compatibility, --enable-
940           utf8 is a synonym of --enable-utf.)
941    
942           Of itself, this setting does not make  PCRE  treat  strings  as  UTF-8,
943           UTF-16  or UTF-32. As well as compiling PCRE with this option, you also
944           have have to set the PCRE_UTF8, PCRE_UTF16  or  PCRE_UTF32  option  (as
945           appropriate) when you call one of the pattern compiling functions.
946    
947           If  you  set --enable-utf when compiling in an EBCDIC environment, PCRE
948           expects its input to be either ASCII or UTF-8 (depending  on  the  run-
949           time option). It is not possible to support both EBCDIC and UTF-8 codes
950           in the same version of  the  library.  Consequently,  --enable-utf  and
951           --enable-ebcdic are mutually exclusive.
952    
953    
954  UNICODE CHARACTER PROPERTY SUPPORT  UNICODE CHARACTER PROPERTY SUPPORT
955    
956         UTF-8 support allows PCRE to process character values greater than  255         UTF  support allows the libraries to process character codepoints up to
957         in  the  strings that it handles. On its own, however, it does not pro-         0x10ffff in the strings that they handle. On its own, however, it  does
958         vide any facilities for accessing the properties of such characters. If         not provide any facilities for accessing the properties of such charac-
959         you  want  to  be able to use the pattern escapes \P, \p, and \X, which         ters. If you want to be able to use the pattern escapes \P, \p, and \X,
960         refer to Unicode character properties, you must add         which refer to Unicode character properties, you must add
961    
962           --enable-unicode-properties           --enable-unicode-properties
963    
964         to the configure command. This implies UTF-8 support, even if you  have         to  the  configure  command. This implies UTF support, even if you have
965         not explicitly requested it.         not explicitly requested it.
966    
967         Including  Unicode  property  support  adds around 30K of tables to the         Including Unicode property support adds around 30K  of  tables  to  the
968         PCRE library. Only the general category properties such as  Lu  and  Nd         PCRE  library.  Only  the general category properties such as Lu and Nd
969         are supported. Details are given in the pcrepattern documentation.         are supported. Details are given in the pcrepattern documentation.
970    
971    
972    JUST-IN-TIME COMPILER SUPPORT
973    
974           Just-in-time compiler support is included in the build by specifying
975    
976             --enable-jit
977    
978           This support is available only for certain hardware  architectures.  If
979           this  option  is  set  for  an unsupported architecture, a compile time
980           error occurs.  See the pcrejit documentation for a  discussion  of  JIT
981           usage. When JIT support is enabled, pcregrep automatically makes use of
982           it, unless you add
983    
984             --disable-pcregrep-jit
985    
986           to the "configure" command.
987    
988    
989  CODE VALUE OF NEWLINE  CODE VALUE OF NEWLINE
990    
991         By  default,  PCRE interprets character 10 (linefeed, LF) as indicating         By default, PCRE interprets the linefeed (LF) character  as  indicating
992         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
993         systems. You can compile PCRE to use character 13 (carriage return, CR)         systems. You can compile PCRE to use carriage return (CR)  instead,  by
994         instead, by adding         adding
995    
996           --enable-newline-is-cr           --enable-newline-is-cr
997    
998         to the  configure  command.  There  is  also  a  --enable-newline-is-lf         to  the  configure  command.  There  is  also  a --enable-newline-is-lf
999         option, which explicitly specifies linefeed as the newline character.         option, which explicitly specifies linefeed as the newline character.
1000    
1001         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 319  CODE VALUE OF NEWLINE Line 1007  CODE VALUE OF NEWLINE
1007    
1008           --enable-newline-is-anycrlf           --enable-newline-is-anycrlf
1009    
1010         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
1011         CRLF as indicating a line ending. Finally, a fifth option, specified by         CRLF as indicating a line ending. Finally, a fifth option, specified by
1012    
1013           --enable-newline-is-any           --enable-newline-is-any
# Line 331  CODE VALUE OF NEWLINE Line 1019  CODE VALUE OF NEWLINE
1019         conventional to use the standard for your operating system.         conventional to use the standard for your operating system.
1020    
1021    
1022  BUILDING SHARED AND STATIC LIBRARIES  WHAT \R MATCHES
1023    
1024         The PCRE building process uses libtool to build both shared and  static         By default, the sequence \R in a pattern matches  any  Unicode  newline
1025         Unix  libraries by default. You can suppress one of these by adding one         sequence,  whatever  has  been selected as the line ending sequence. If
1026         of         you specify
1027    
1028           --disable-shared           --enable-bsr-anycrlf
          --disable-static  
1029    
1030         to the configure command, as required.         the default is changed so that \R matches only CR, LF, or  CRLF.  What-
1031           ever  is selected when PCRE is built can be overridden when the library
1032           functions are called.
1033    
1034    
1035  POSIX MALLOC USAGE  POSIX MALLOC USAGE
1036    
1037         When PCRE is called through the POSIX interface (see the pcreposix doc-         When the 8-bit library is called through the POSIX interface  (see  the
1038         umentation),  additional  working  storage  is required for holding the         pcreposix  documentation),  additional  working storage is required for
1039         pointers to capturing substrings, because PCRE requires three  integers         holding the pointers to capturing  substrings,  because  PCRE  requires
1040         per  substring,  whereas  the POSIX interface provides only two. If the         three integers per substring, whereas the POSIX interface provides only
1041         number of expected substrings is small, the wrapper function uses space         two. If the number of expected substrings is small, the  wrapper  func-
1042         on the stack, because this is faster than using malloc() for each call.         tion  uses  space  on the stack, because this is faster than using mal-
1043         The default threshold above which the stack is no longer used is 10; it         loc() for each call. The default threshold above which the stack is  no
1044         can be changed by adding a setting such as         longer used is 10; it can be changed by adding a setting such as
1045    
1046           --with-posix-malloc-threshold=20           --with-posix-malloc-threshold=20
1047    
# Line 363  HANDLING VERY LARGE PATTERNS Line 1052  HANDLING VERY LARGE PATTERNS
1052    
1053         Within  a  compiled  pattern,  offset values are used to point from one         Within  a  compiled  pattern,  offset values are used to point from one
1054         part to another (for example, from an opening parenthesis to an  alter-         part to another (for example, from an opening parenthesis to an  alter-
1055         nation  metacharacter).  By default, two-byte values are used for these         nation  metacharacter).  By default, in the 8-bit and 16-bit libraries,
1056         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
1057         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
1058         Nevertheless, some people do want to process enormous patterns,  so  it         but the most gigantic patterns.  Nevertheless, some people do  want  to
1059         is  possible  to compile PCRE to use three-byte or four-byte offsets by         process  truly  enormous patterns, so it is possible to compile PCRE to
1060         adding a setting such as         use three-byte or four-byte offsets by adding a setting such as
1061    
1062           --with-link-size=3           --with-link-size=3
1063    
1064         to the configure command. The value given must be 2,  3,  or  4.  Using         to the configure command. The value given must be 2, 3, or 4.  For  the
1065         longer  offsets slows down the operation of PCRE because it has to load         16-bit  library,  a  value of 3 is rounded up to 4. In these libraries,
1066         additional bytes when handling them.         using longer offsets slows down the operation of PCRE because it has to
1067           load  additional  data  when  handling them. For the 32-bit library the
1068           value is always 4 and cannot be overridden; the value  of  --with-link-
1069           size is ignored.
1070    
1071    
1072  AVOIDING EXCESSIVE STACK USAGE  AVOIDING EXCESSIVE STACK USAGE
1073    
1074         When matching with the pcre_exec() function, PCRE implements backtrack-         When matching with the pcre_exec() function, PCRE implements backtrack-
1075         ing  by  making recursive calls to an internal function called match().         ing by making recursive calls to an internal function  called  match().
1076         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-
1077         verely  limit  PCRE's operation. (The Unix environment does not usually         verely limit PCRE's operation. (The Unix environment does  not  usually
1078         suffer from this problem, but it may sometimes be necessary to increase         suffer from this problem, but it may sometimes be necessary to increase
1079         the  maximum  stack size.  There is a discussion in the pcrestack docu-         the maximum stack size.  There is a discussion in the  pcrestack  docu-
1080         mentation.) An alternative approach to recursion that uses memory  from         mentation.)  An alternative approach to recursion that uses memory from
1081         the  heap  to remember data, instead of using recursive function calls,         the heap to remember data, instead of using recursive  function  calls,
1082         has been implemented to work round the problem of limited  stack  size.         has  been  implemented to work round the problem of limited stack size.
1083         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
1084    
1085           --disable-stack-for-recursion           --disable-stack-for-recursion
1086    
1087         to  the  configure  command. With this configuration, PCRE will use the         to the configure command. With this configuration, PCRE  will  use  the
1088         pcre_stack_malloc and pcre_stack_free variables to call memory  manage-         pcre_stack_malloc  and pcre_stack_free variables to call memory manage-
1089         ment  functions. By default these point to malloc() and free(), but you         ment functions. By default these point to malloc() and free(), but  you
1090         can replace the pointers so that your own functions are used.         can replace the pointers so that your own functions are used instead.
1091    
1092         Separate functions are  provided  rather  than  using  pcre_malloc  and         Separate  functions  are  provided  rather  than  using pcre_malloc and
1093         pcre_free  because  the  usage  is  very  predictable:  the block sizes         pcre_free because the  usage  is  very  predictable:  the  block  sizes
1094         requested are always the same, and  the  blocks  are  always  freed  in         requested  are  always  the  same,  and  the blocks are always freed in
1095         reverse  order.  A calling program might be able to implement optimized         reverse order. A calling program might be able to  implement  optimized
1096         functions that perform better  than  malloc()  and  free().  PCRE  runs         functions  that  perform  better  than  malloc()  and free(). PCRE runs
1097         noticeably more slowly when built in this way. This option affects only         noticeably more slowly when built in this way. This option affects only
1098         the  pcre_exec()  function;  it   is   not   relevant   for   the   the         the pcre_exec() function; it is not relevant for pcre_dfa_exec().
        pcre_dfa_exec() function.  
1099    
1100    
1101  LIMITING PCRE RESOURCE USAGE  LIMITING PCRE RESOURCE USAGE
# Line 449  CREATING CHARACTER TABLES AT BUILD TIME Line 1140  CREATING CHARACTER TABLES AT BUILD TIME
1140         to  the  configure  command, the distributed tables are no longer used.         to  the  configure  command, the distributed tables are no longer used.
1141         Instead, a program called dftables is compiled and  run.  This  outputs         Instead, a program called dftables is compiled and  run.  This  outputs
1142         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
1143         C runtime system. (This method of replacing the tables does not work if         C run-time system. (This method of replacing the tables does  not  work
1144         you  are cross compiling, because dftables is run on the local host. If         if  you are cross compiling, because dftables is run on the local host.
1145         you need to create alternative tables when cross  compiling,  you  will         If you need to create alternative tables when cross compiling, you will
1146         have to do so "by hand".)         have to do so "by hand".)
1147    
1148    
# Line 466  USING EBCDIC CODE Line 1157  USING EBCDIC CODE
1157    
1158         to the configure command. This setting implies --enable-rebuild-charta-         to the configure command. This setting implies --enable-rebuild-charta-
1159         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
1160         environment (for example, an IBM mainframe operating system).         environment (for example,  an  IBM  mainframe  operating  system).  The
1161           --enable-ebcdic option is incompatible with --enable-utf.
1162    
1163           The EBCDIC character that corresponds to an ASCII LF is assumed to have
1164           the value 0x15 by default. However, in some EBCDIC  environments,  0x25
1165           is used. In such an environment you should use
1166    
1167             --enable-ebcdic-nl25
1168    
1169           as well as, or instead of, --enable-ebcdic. The EBCDIC character for CR
1170           has the same value as in ASCII, namely, 0x0d.  Whichever  of  0x15  and
1171           0x25 is not chosen as LF is made to correspond to the Unicode NEL char-
1172           acter (which, in Unicode, is 0x85).
1173    
1174           The options that select newline behaviour, such as --enable-newline-is-
1175           cr, and equivalent run-time options, refer to these character values in
1176           an EBCDIC environment.
1177    
1178    
1179    PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT
1180    
1181           By default, pcregrep reads all files as plain text. You can build it so
1182           that it recognizes files whose names end in .gz or .bz2, and reads them
1183           with libz or libbz2, respectively, by adding one or both of
1184    
1185             --enable-pcregrep-libz
1186             --enable-pcregrep-libbz2
1187    
1188           to the configure command. These options naturally require that the rel-
1189           evant  libraries  are installed on your system. Configuration will fail
1190           if they are not.
1191    
1192    
1193    PCREGREP BUFFER SIZE
1194    
1195           pcregrep uses an internal buffer to hold a "window" on the file  it  is
1196           scanning, in order to be able to output "before" and "after" lines when
1197           it finds a match. The size of the buffer is controlled by  a  parameter
1198           whose default value is 20K. The buffer itself is three times this size,
1199           but because of the way it is used for holding "before" lines, the long-
1200           est  line  that  is guaranteed to be processable is the parameter size.
1201           You can change the default parameter value by adding, for example,
1202    
1203             --with-pcregrep-bufsize=50K
1204    
1205           to the configure command. The caller of pcregrep can, however, override
1206           this value by specifying a run-time option.
1207    
1208    
1209    PCRETEST OPTION FOR LIBREADLINE SUPPORT
1210    
1211           If you add
1212    
1213             --enable-pcretest-libreadline
1214    
1215           to  the  configure  command,  pcretest  is  linked with the libreadline
1216           library, and when its input is from a terminal, it reads it  using  the
1217           readline() function. This provides line-editing and history facilities.
1218           Note that libreadline is GPL-licensed, so if you distribute a binary of
1219           pcretest linked in this way, there may be licensing issues.
1220    
1221           Setting  this  option  causes  the -lreadline option to be added to the
1222           pcretest build. In many operating environments with  a  sytem-installed
1223           libreadline this is sufficient. However, in some environments (e.g.  if
1224           an unmodified distribution version of readline is in use),  some  extra
1225           configuration  may  be necessary. The INSTALL file for libreadline says
1226           this:
1227    
1228             "Readline uses the termcap functions, but does not link with the
1229             termcap or curses library itself, allowing applications which link
1230             with readline the to choose an appropriate library."
1231    
1232           If your environment has not been set up so that an appropriate  library
1233           is automatically included, you may need to add something like
1234    
1235             LIBS="-ncurses"
1236    
1237           immediately before the configure command.
1238    
1239    
1240    DEBUGGING WITH VALGRIND SUPPORT
1241    
1242           By adding the
1243    
1244             --enable-valgrind
1245    
1246           option  to to the configure command, PCRE will use valgrind annotations
1247           to mark certain memory regions as  unaddressable.  This  allows  it  to
1248           detect invalid memory accesses, and is mostly useful for debugging PCRE
1249           itself.
1250    
1251    
1252    CODE COVERAGE REPORTING
1253    
1254           If your C compiler is gcc, you can build a version  of  PCRE  that  can
1255           generate a code coverage report for its test suite. To enable this, you
1256           must install lcov version 1.6 or above. Then specify
1257    
1258             --enable-coverage
1259    
1260           to the configure command and build PCRE in the usual way.
1261    
1262           Note that using ccache (a caching C compiler) is incompatible with code
1263           coverage  reporting. If you have configured ccache to run automatically
1264           on your system, you must set the environment variable
1265    
1266             CCACHE_DISABLE=1
1267    
1268           before running make to build PCRE, so that ccache is not used.
1269    
1270           When --enable-coverage is used,  the  following  addition  targets  are
1271           added to the Makefile:
1272    
1273             make coverage
1274    
1275           This  creates  a  fresh  coverage report for the PCRE test suite. It is
1276           equivalent to running "make coverage-reset", "make  coverage-baseline",
1277           "make check", and then "make coverage-report".
1278    
1279             make coverage-reset
1280    
1281           This zeroes the coverage counters, but does nothing else.
1282    
1283             make coverage-baseline
1284    
1285           This captures baseline coverage information.
1286    
1287             make coverage-report
1288    
1289           This creates the coverage report.
1290    
1291             make coverage-clean-report
1292    
1293           This  removes the generated coverage report without cleaning the cover-
1294           age data itself.
1295    
1296             make coverage-clean-data
1297    
1298           This removes the captured coverage data without removing  the  coverage
1299           files created at compile time (*.gcno).
1300    
1301             make coverage-clean
1302    
1303           This  cleans all coverage data including the generated coverage report.
1304           For more information about code coverage, see the gcov and  lcov  docu-
1305           mentation.
1306    
1307    
1308  SEE ALSO  SEE ALSO
1309    
1310         pcreapi(3), pcre_config(3).         pcreapi(3), pcre16, pcre32, pcre_config(3).
1311    
1312    
1313  AUTHOR  AUTHOR
# Line 483  AUTHOR Line 1319  AUTHOR
1319    
1320  REVISION  REVISION
1321    
1322         Last updated: 30 July 2007         Last updated: 30 October 2012
1323         Copyright (c) 1997-2007 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
1324  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1325    
1326    
# Line 500  PCRE MATCHING ALGORITHMS Line 1336  PCRE MATCHING ALGORITHMS
1336         This document describes the two different algorithms that are available         This document describes the two different algorithms that are available
1337         in PCRE for matching a compiled regular expression against a given sub-         in PCRE for matching a compiled regular expression against a given sub-
1338         ject  string.  The  "standard"  algorithm  is  the  one provided by the         ject  string.  The  "standard"  algorithm  is  the  one provided by the
1339         pcre_exec() function.  This works in the same was  as  Perl's  matching         pcre_exec(), pcre16_exec() and pcre32_exec() functions. These  work  in
1340         function, and provides a Perl-compatible matching operation.         the  same as as Perl's matching function, and provide a Perl-compatible
1341           matching  operation.   The  just-in-time  (JIT)  optimization  that  is
1342         An  alternative  algorithm is provided by the pcre_dfa_exec() function;         described  in  the pcrejit documentation is compatible with these func-
1343         this operates in a different way, and is not  Perl-compatible.  It  has         tions.
1344         advantages  and disadvantages compared with the standard algorithm, and  
1345         these are described below.         An  alternative  algorithm  is   provided   by   the   pcre_dfa_exec(),
1346           pcre16_dfa_exec()  and  pcre32_dfa_exec()  functions; they operate in a
1347           different way, and are not Perl-compatible. This alternative has advan-
1348           tages and disadvantages compared with the standard algorithm, and these
1349           are described below.
1350    
1351         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
1352         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 571  THE ALTERNATIVE MATCHING ALGORITHM Line 1411  THE ALTERNATIVE MATCHING ALGORITHM
1411         though  it is not implemented as a traditional finite state machine (it         though  it is not implemented as a traditional finite state machine (it
1412         keeps multiple states active simultaneously).         keeps multiple states active simultaneously).
1413    
1414           Although the general principle of this matching algorithm  is  that  it
1415           scans  the subject string only once, without backtracking, there is one
1416           exception: when a lookaround assertion is encountered,  the  characters
1417           following  or  preceding  the  current  point  have to be independently
1418           inspected.
1419    
1420         The scan continues until either the end of the subject is  reached,  or         The scan continues until either the end of the subject is  reached,  or
1421         there  are  no more unterminated paths. At this point, terminated paths         there  are  no more unterminated paths. At this point, terminated paths
1422         represent the different matching possibilities (if there are none,  the         represent the different matching possibilities (if there are none,  the
1423         match  has  failed).   Thus,  if there is more than one possible match,         match  has  failed).   Thus,  if there is more than one possible match,
1424         this algorithm finds all of them, and in particular, it finds the long-         this algorithm finds all of them, and in particular, it finds the long-
1425         est.  In PCRE, there is an option to stop the algorithm after the first         est.  The  matches are returned in decreasing order of length. There is
1426         match (which is necessarily the shortest) has been found.         an option to stop the algorithm after the first match (which is  neces-
1427           sarily the shortest) is found.
1428    
1429         Note that all the matches that are found start at the same point in the         Note that all the matches that are found start at the same point in the
1430         subject. If the pattern         subject. If the pattern
1431    
1432           cat(er(pillar)?)           cat(er(pillar)?)?
1433    
1434         is  matched  against the string "the caterpillar catchment", the result         is matched against the string "the caterpillar catchment",  the  result
1435         will be the three strings "cat", "cater", and "caterpillar" that  start         will  be the three strings "caterpillar", "cater", and "cat" that start
1436         at the fourth character of the subject. The algorithm does not automat-         at the fifth character of the subject. The algorithm does not automati-
1437         ically move on to find matches that start at later positions.         cally move on to find matches that start at later positions.
1438    
1439         There are a number of features of PCRE regular expressions that are not         There are a number of features of PCRE regular expressions that are not
1440         supported by the alternative matching algorithm. They are as follows:         supported by the alternative matching algorithm. They are as follows:
1441    
1442         1.  Because  the  algorithm  finds  all possible matches, the greedy or         1. Because the algorithm finds all  possible  matches,  the  greedy  or
1443         ungreedy nature of repetition quantifiers is not relevant.  Greedy  and         ungreedy  nature  of repetition quantifiers is not relevant. Greedy and
1444         ungreedy quantifiers are treated in exactly the same way. However, pos-         ungreedy quantifiers are treated in exactly the same way. However, pos-
1445         sessive quantifiers can make a difference when what follows could  also         sessive  quantifiers can make a difference when what follows could also
1446         match what is quantified, for example in a pattern like this:         match what is quantified, for example in a pattern like this:
1447    
1448           ^a++\w!           ^a++\w!
1449    
1450         This  pattern matches "aaab!" but not "aaa!", which would be matched by         This pattern matches "aaab!" but not "aaa!", which would be matched  by
1451         a non-possessive quantifier. Similarly, if an atomic group is  present,         a  non-possessive quantifier. Similarly, if an atomic group is present,
1452         it  is matched as if it were a standalone pattern at the current point,         it is matched as if it were a standalone pattern at the current  point,
1453         and the longest match is then "locked in" for the rest of  the  overall         and  the  longest match is then "locked in" for the rest of the overall
1454         pattern.         pattern.
1455    
1456         2. When dealing with multiple paths through the tree simultaneously, it         2. When dealing with multiple paths through the tree simultaneously, it
1457         is not straightforward to keep track of  captured  substrings  for  the         is  not  straightforward  to  keep track of captured substrings for the
1458         different  matching  possibilities,  and  PCRE's implementation of this         different matching possibilities, and  PCRE's  implementation  of  this
1459         algorithm does not attempt to do this. This means that no captured sub-         algorithm does not attempt to do this. This means that no captured sub-
1460         strings are available.         strings are available.
1461    
1462         3.  Because no substrings are captured, back references within the pat-         3. Because no substrings are captured, back references within the  pat-
1463         tern are not supported, and cause errors if encountered.         tern are not supported, and cause errors if encountered.
1464    
1465         4. For the same reason, conditional expressions that use  a  backrefer-         4.  For  the same reason, conditional expressions that use a backrefer-
1466         ence  as  the  condition or test for a specific group recursion are not         ence as the condition or test for a specific group  recursion  are  not
1467         supported.         supported.
1468    
1469         5. Because many paths through the tree may be  active,  the  \K  escape         5.  Because  many  paths  through the tree may be active, the \K escape
1470         sequence, which resets the start of the match when encountered (but may         sequence, which resets the start of the match when encountered (but may
1471         be on some paths and not on others), is not  supported.  It  causes  an         be  on  some  paths  and not on others), is not supported. It causes an
1472         error if encountered.         error if encountered.
1473    
1474         6.  Callouts  are  supported, but the value of the capture_top field is         6. Callouts are supported, but the value of the  capture_top  field  is
1475         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.
1476    
1477         7.  The \C escape sequence, which (in the standard algorithm) matches a         7.  The  \C  escape  sequence, which (in the standard algorithm) always
1478         single  byte, even in UTF-8 mode, is not supported because the alterna-         matches a single data unit, even in UTF-8, UTF-16 or UTF-32  modes,  is
1479         tive algorithm moves through the subject  string  one  character  at  a         not  supported  in these modes, because the alternative algorithm moves
1480         time, for all active paths through the tree.         through the subject string one character (not data unit) at a time, for
1481           all active paths through the tree.
1482    
1483           8.  Except for (*FAIL), the backtracking control verbs such as (*PRUNE)
1484           are not supported. (*FAIL) is supported, and  behaves  like  a  failing
1485           negative assertion.
1486    
1487    
1488  ADVANTAGES OF THE ALTERNATIVE ALGORITHM  ADVANTAGES OF THE ALTERNATIVE ALGORITHM
# Line 643  ADVANTAGES OF THE ALTERNATIVE ALGORITHM Line 1495  ADVANTAGES OF THE ALTERNATIVE ALGORITHM
1495         more than one match using the standard algorithm, you have to do kludgy         more than one match using the standard algorithm, you have to do kludgy
1496         things with callouts.         things with callouts.
1497    
1498         2.  There is much better support for partial matching. The restrictions         2.  Because  the  alternative  algorithm  scans the subject string just
1499         on the content of the pattern that apply when using the standard  algo-         once, and never needs to backtrack (except for lookbehinds), it is pos-
1500         rithm  for  partial matching do not apply to the alternative algorithm.         sible  to  pass  very  long subject strings to the matching function in
1501         For non-anchored patterns, the starting position of a partial match  is         several pieces, checking for partial matching each time. Although it is
1502         available.         possible  to  do multi-segment matching using the standard algorithm by
1503           retaining partially matched substrings, it  is  more  complicated.  The
1504         3.  Because  the  alternative  algorithm  scans the subject string just         pcrepartial  documentation  gives  details of partial matching and dis-
1505         once, and never needs to backtrack, it is possible to  pass  very  long         cusses multi-segment matching.
        subject  strings  to  the matching function in several pieces, checking  
        for partial matching each time.  
1506    
1507    
1508  DISADVANTAGES OF THE ALTERNATIVE ALGORITHM  DISADVANTAGES OF THE ALTERNATIVE ALGORITHM
# Line 678  AUTHOR Line 1528  AUTHOR
1528    
1529  REVISION  REVISION
1530    
1531         Last updated: 29 May 2007         Last updated: 08 January 2012
1532         Copyright (c) 1997-2007 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
1533  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1534    
1535    
# Line 689  PCREAPI(3) Line 1539  PCREAPI(3)
1539  NAME  NAME
1540         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
1541    
1542           #include <pcre.h>
1543    
 PCRE NATIVE API  
1544    
1545         #include <pcre.h>  PCRE NATIVE API BASIC FUNCTIONS
1546    
1547         pcre *pcre_compile(const char *pattern, int options,         pcre *pcre_compile(const char *pattern, int options,
1548              const char **errptr, int *erroffset,              const char **errptr, int *erroffset,
# Line 706  PCRE NATIVE API Line 1556  PCRE NATIVE API
1556         pcre_extra *pcre_study(const pcre *code, int options,         pcre_extra *pcre_study(const pcre *code, int options,
1557              const char **errptr);              const char **errptr);
1558    
1559           void pcre_free_study(pcre_extra *extra);
1560    
1561         int pcre_exec(const pcre *code, const pcre_extra *extra,         int pcre_exec(const pcre *code, const pcre_extra *extra,
1562              const char *subject, int length, int startoffset,              const char *subject, int length, int startoffset,
1563              int options, int *ovector, int ovecsize);              int options, int *ovector, int ovecsize);
# Line 715  PCRE NATIVE API Line 1567  PCRE NATIVE API
1567              int options, int *ovector, int ovecsize,              int options, int *ovector, int ovecsize,
1568              int *workspace, int wscount);              int *workspace, int wscount);
1569    
1570    
1571    PCRE NATIVE API STRING EXTRACTION FUNCTIONS
1572    
1573         int pcre_copy_named_substring(const pcre *code,         int pcre_copy_named_substring(const pcre *code,
1574              const char *subject, int *ovector,              const char *subject, int *ovector,
1575              int stringcount, const char *stringname,              int stringcount, const char *stringname,
# Line 746  PCRE NATIVE API Line 1601  PCRE NATIVE API
1601    
1602         void pcre_free_substring_list(const char **stringptr);         void pcre_free_substring_list(const char **stringptr);
1603    
1604    
1605    PCRE NATIVE API AUXILIARY FUNCTIONS
1606    
1607           int pcre_jit_exec(const pcre *code, const pcre_extra *extra,
1608                const char *subject, int length, int startoffset,
1609                int options, int *ovector, int ovecsize,
1610                pcre_jit_stack *jstack);
1611    
1612           pcre_jit_stack *pcre_jit_stack_alloc(int startsize, int maxsize);
1613    
1614           void pcre_jit_stack_free(pcre_jit_stack *stack);
1615    
1616           void pcre_assign_jit_stack(pcre_extra *extra,
1617                pcre_jit_callback callback, void *data);
1618    
1619         const unsigned char *pcre_maketables(void);         const unsigned char *pcre_maketables(void);
1620    
1621         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
1622              int what, void *where);              int what, void *where);
1623    
        int pcre_info(const pcre *code, int *optptr, int *firstcharptr);  
   
1624         int pcre_refcount(pcre *code, int adjust);         int pcre_refcount(pcre *code, int adjust);
1625    
1626         int pcre_config(int what, void *where);         int pcre_config(int what, void *where);
1627    
1628         char *pcre_version(void);         const char *pcre_version(void);
1629    
1630           int pcre_pattern_to_host_byte_order(pcre *code,
1631                pcre_extra *extra, const unsigned char *tables);
1632    
1633    
1634    PCRE NATIVE API INDIRECTED FUNCTIONS
1635    
1636         void *(*pcre_malloc)(size_t);         void *(*pcre_malloc)(size_t);
1637    
# Line 770  PCRE NATIVE API Line 1644  PCRE NATIVE API
1644         int (*pcre_callout)(pcre_callout_block *);         int (*pcre_callout)(pcre_callout_block *);
1645    
1646    
1647    PCRE 8-BIT, 16-BIT, AND 32-BIT LIBRARIES
1648    
1649           As  well  as  support  for  8-bit character strings, PCRE also supports
1650           16-bit strings (from release 8.30) and  32-bit  strings  (from  release
1651           8.32),  by means of two additional libraries. They can be built as well
1652           as, or instead of, the 8-bit library. To avoid too  much  complication,
1653           this  document describes the 8-bit versions of the functions, with only
1654           occasional references to the 16-bit and 32-bit libraries.
1655    
1656           The 16-bit and 32-bit functions operate in the same way as their  8-bit
1657           counterparts;  they  just  use different data types for their arguments
1658           and results, and their names start with pcre16_ or pcre32_  instead  of
1659           pcre_.  For  every  option  that  has  UTF8  in  its name (for example,
1660           PCRE_UTF8), there are corresponding 16-bit and 32-bit names  with  UTF8
1661           replaced by UTF16 or UTF32, respectively. This facility is in fact just
1662           cosmetic; the 16-bit and 32-bit option names define the same  bit  val-
1663           ues.
1664    
1665           References to bytes and UTF-8 in this document should be read as refer-
1666           ences to 16-bit data  quantities  and  UTF-16  when  using  the  16-bit
1667           library,  or  32-bit  data  quantities and UTF-32 when using the 32-bit
1668           library, unless specified otherwise. More details of the specific  dif-
1669           ferences  for  the  16-bit and 32-bit libraries are given in the pcre16
1670           and pcre32 pages.
1671    
1672    
1673  PCRE API OVERVIEW  PCRE API OVERVIEW
1674    
1675         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
1676         are also some wrapper functions that correspond to  the  POSIX  regular         are  also some wrapper functions (for the 8-bit library only) that cor-
1677         expression  API.  These  are  described in the pcreposix documentation.         respond to the POSIX regular expression  API,  but  they  do  not  give
1678         Both of these APIs define a set of C function calls. A C++  wrapper  is         access  to  all  the functionality. They are described in the pcreposix
1679         distributed with PCRE. It is documented in the pcrecpp page.         documentation. Both of these APIs define a set of C function  calls.  A
1680           C++ wrapper (again for the 8-bit library only) is also distributed with
1681         The  native  API  C  function prototypes are defined in the header file         PCRE. It is documented in the pcrecpp page.
1682         pcre.h, and on Unix systems the library itself is called  libpcre.   It  
1683         can normally be accessed by adding -lpcre to the command for linking an         The native API C function prototypes are defined  in  the  header  file
1684         application  that  uses  PCRE.  The  header  file  defines  the  macros         pcre.h,  and  on Unix-like systems the (8-bit) library itself is called
1685         PCRE_MAJOR  and  PCRE_MINOR to contain the major and minor release num-         libpcre. It can normally be accessed by adding -lpcre  to  the  command
1686         bers for the library.  Applications can use these  to  include  support         for  linking an application that uses PCRE. The header file defines the
1687           macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release
1688           numbers  for the library. Applications can use these to include support
1689         for different releases of PCRE.         for different releases of PCRE.
1690    
1691         The   functions   pcre_compile(),  pcre_compile2(),  pcre_study(),  and         In a Windows environment, if you want to statically link an application
1692         pcre_exec() are used for compiling and matching regular expressions  in         program  against  a  non-dll  pcre.a  file, you must define PCRE_STATIC
1693         a  Perl-compatible  manner. A sample program that demonstrates the sim-         before including pcre.h or pcrecpp.h, because otherwise  the  pcre_mal-
1694         plest way of using them is provided in the file  called  pcredemo.c  in         loc()   and   pcre_free()   exported   functions   will   be   declared
1695         the  source distribution. The pcresample documentation describes how to         __declspec(dllimport), with unwanted results.
1696         run it.  
1697           The  functions  pcre_compile(),  pcre_compile2(),   pcre_study(),   and
1698           pcre_exec()  are used for compiling and matching regular expressions in
1699           a Perl-compatible manner. A sample program that demonstrates  the  sim-
1700           plest  way  of  using them is provided in the file called pcredemo.c in
1701           the PCRE source distribution. A listing of this program is given in the
1702           pcredemo  documentation, and the pcresample documentation describes how
1703           to compile and run it.
1704    
1705           Just-in-time compiler support is an optional feature of PCRE  that  can
1706           be built in appropriate hardware environments. It greatly speeds up the
1707           matching performance of  many  patterns.  Simple  programs  can  easily
1708           request  that  it  be  used  if available, by setting an option that is
1709           ignored when it is not relevant. More complicated programs  might  need
1710           to     make    use    of    the    functions    pcre_jit_stack_alloc(),
1711           pcre_jit_stack_free(), and pcre_assign_jit_stack() in order to  control
1712           the JIT code's memory usage.
1713    
1714           From  release  8.32 there is also a direct interface for JIT execution,
1715           which gives improved performance. The JIT-specific functions  are  dis-
1716           cussed in the pcrejit documentation.
1717    
1718         A second matching function, pcre_dfa_exec(), which is not Perl-compati-         A second matching function, pcre_dfa_exec(), which is not Perl-compati-
1719         ble,  is  also provided. This uses a different algorithm for the match-         ble, is also provided. This uses a different algorithm for  the  match-
1720         ing. The alternative algorithm finds all possible matches (at  a  given         ing.  The  alternative algorithm finds all possible matches (at a given
1721         point  in  the subject), and scans the subject just once. However, this         point in the subject), and scans the subject just  once  (unless  there
1722         algorithm does not return captured substrings. A description of the two         are  lookbehind  assertions).  However,  this algorithm does not return
1723         matching  algorithms and their advantages and disadvantages is given in         captured substrings. A description of the two matching  algorithms  and
1724         the pcrematching documentation.         their  advantages  and disadvantages is given in the pcrematching docu-
1725           mentation.
1726    
1727         In addition to the main compiling and  matching  functions,  there  are         In addition to the main compiling and  matching  functions,  there  are
1728         convenience functions for extracting captured substrings from a subject         convenience functions for extracting captured substrings from a subject
# Line 824  PCRE API OVERVIEW Line 1747  PCRE API OVERVIEW
1747         built are used.         built are used.
1748    
1749         The function pcre_fullinfo() is used to find out  information  about  a         The function pcre_fullinfo() is used to find out  information  about  a
1750         compiled  pattern; pcre_info() is an obsolete version that returns only         compiled  pattern.  The  function pcre_version() returns a pointer to a
1751         some of the available information, but is retained for  backwards  com-         string containing the version of PCRE and its date of release.
        patibility.   The function pcre_version() returns a pointer to a string  
        containing the version of PCRE and its date of release.  
1752    
1753         The function pcre_refcount() maintains a  reference  count  in  a  data         The function pcre_refcount() maintains a  reference  count  in  a  data
1754         block  containing  a compiled pattern. This is provided for the benefit         block  containing  a compiled pattern. This is provided for the benefit
# Line 866  NEWLINES Line 1787  NEWLINES
1787         feed) character, the two-character sequence CRLF, any of the three pre-         feed) character, the two-character sequence CRLF, any of the three pre-
1788         ceding, or any Unicode newline sequence. The Unicode newline  sequences         ceding, or any Unicode newline sequence. The Unicode newline  sequences
1789         are  the  three just mentioned, plus the single characters VT (vertical         are  the  three just mentioned, plus the single characters VT (vertical
1790         tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS  (line         tab, U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line
1791         separator, U+2028), and PS (paragraph separator, U+2029).         separator, U+2028), and PS (paragraph separator, U+2029).
1792    
1793         Each  of  the first three conventions is used by at least one operating         Each  of  the first three conventions is used by at least one operating
# Line 875  NEWLINES Line 1796  NEWLINES
1796         dard. When PCRE is run, the default can be overridden,  either  when  a         dard. When PCRE is run, the default can be overridden,  either  when  a
1797         pattern is compiled, or when it is matched.         pattern is compiled, or when it is matched.
1798    
1799           At compile time, the newline convention can be specified by the options
1800           argument of pcre_compile(), or it can be specified by special  text  at
1801           the start of the pattern itself; this overrides any other settings. See
1802           the pcrepattern page for details of the special character sequences.
1803    
1804         In the PCRE documentation the word "newline" is used to mean "the char-         In the PCRE documentation the word "newline" is used to mean "the char-
1805         acter or pair of characters that indicate a line break". The choice  of         acter  or pair of characters that indicate a line break". The choice of
1806         newline  convention  affects  the  handling of the dot, circumflex, and         newline convention affects the handling of  the  dot,  circumflex,  and
1807         dollar metacharacters, the handling of #-comments in /x mode, and, when         dollar metacharacters, the handling of #-comments in /x mode, and, when
1808         CRLF  is a recognized line ending sequence, the match position advance-         CRLF is a recognized line ending sequence, the match position  advance-
1809         ment for a non-anchored pattern. The choice of newline convention  does         ment for a non-anchored pattern. There is more detail about this in the
1810         not affect the interpretation of the \n or \r escape sequences.         section on pcre_exec() options below.
1811    
1812           The choice of newline convention does not affect the interpretation  of
1813           the  \n  or  \r  escape  sequences, nor does it affect what \R matches,
1814           which is controlled in a similar way, but by separate options.
1815    
1816    
1817  MULTITHREADING  MULTITHREADING
1818    
1819         The  PCRE  functions  can be used in multi-threading applications, with         The PCRE functions can be used in  multi-threading  applications,  with
1820         the  proviso  that  the  memory  management  functions  pointed  to  by         the  proviso  that  the  memory  management  functions  pointed  to  by
1821         pcre_malloc, pcre_free, pcre_stack_malloc, and pcre_stack_free, and the         pcre_malloc, pcre_free, pcre_stack_malloc, and pcre_stack_free, and the
1822         callout function pointed to by pcre_callout, are shared by all threads.         callout function pointed to by pcre_callout, are shared by all threads.
# Line 895  MULTITHREADING Line 1825  MULTITHREADING
1825         ing, so the same compiled pattern can safely be used by several threads         ing, so the same compiled pattern can safely be used by several threads
1826         at once.         at once.
1827    
1828           If  the just-in-time optimization feature is being used, it needs sepa-
1829           rate memory stack areas for each thread. See the pcrejit  documentation
1830           for more details.
1831    
1832    
1833  SAVING PRECOMPILED PATTERNS FOR LATER USE  SAVING PRECOMPILED PATTERNS FOR LATER USE
1834    
1835         The compiled form of a regular expression can be saved and re-used at a         The compiled form of a regular expression can be saved and re-used at a
1836         later time, possibly by a different program, and even on a  host  other         later time, possibly by a different program, and even on a  host  other
1837         than  the  one  on  which  it  was  compiled.  Details are given in the         than  the  one  on  which  it  was  compiled.  Details are given in the
1838         pcreprecompile documentation. However, compiling a  regular  expression         pcreprecompile documentation,  which  includes  a  description  of  the
1839         with  one version of PCRE for use with a different version is not guar-         pcre_pattern_to_host_byte_order()  function. However, compiling a regu-
1840         anteed to work and may cause crashes.         lar expression with one version of PCRE for use with a  different  ver-
1841           sion is not guaranteed to work and may cause crashes.
1842    
1843    
1844  CHECKING BUILD-TIME OPTIONS  CHECKING BUILD-TIME OPTIONS
1845    
1846         int pcre_config(int what, void *where);         int pcre_config(int what, void *where);
1847    
1848         The function pcre_config() makes it possible for a PCRE client to  dis-         The  function pcre_config() makes it possible for a PCRE client to dis-
1849         cover which optional features have been compiled into the PCRE library.         cover which optional features have been compiled into the PCRE library.
1850         The pcrebuild documentation has more details about these optional  fea-         The  pcrebuild documentation has more details about these optional fea-
1851         tures.         tures.
1852    
1853         The  first  argument  for pcre_config() is an integer, specifying which         The first argument for pcre_config() is an  integer,  specifying  which
1854         information is required; the second argument is a pointer to a variable         information is required; the second argument is a pointer to a variable
1855         into  which  the  information  is  placed. The following information is         into which the information is placed. The returned  value  is  zero  on
1856           success,  or  the negative error code PCRE_ERROR_BADOPTION if the value
1857           in the first argument is not recognized. The following  information  is
1858         available:         available:
1859    
1860           PCRE_CONFIG_UTF8           PCRE_CONFIG_UTF8
1861    
1862         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-
1863         able; otherwise it is set to zero.         able; otherwise it is set to zero. This value should normally be  given
1864           to the 8-bit version of this function, pcre_config(). If it is given to
1865           the  16-bit  or  32-bit  version  of  this  function,  the  result   is
1866           PCRE_ERROR_BADOPTION.
1867    
1868             PCRE_CONFIG_UTF16
1869    
1870           The output is an integer that is set to one if UTF-16 support is avail-
1871           able; otherwise it is set to zero. This value should normally be  given
1872           to the 16-bit version of this function, pcre16_config(). If it is given
1873           to the 8-bit  or  32-bit  version  of  this  function,  the  result  is
1874           PCRE_ERROR_BADOPTION.
1875    
1876             PCRE_CONFIG_UTF32
1877    
1878           The output is an integer that is set to one if UTF-32 support is avail-
1879           able; otherwise it is set to zero. This value should normally be  given
1880           to the 32-bit version of this function, pcre32_config(). If it is given
1881           to the 8-bit  or  16-bit  version  of  this  function,  the  result  is
1882           PCRE_ERROR_BADOPTION.
1883    
1884           PCRE_CONFIG_UNICODE_PROPERTIES           PCRE_CONFIG_UNICODE_PROPERTIES
1885    
1886         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
1887         character properties is available; otherwise it is set to zero.         character properties is available; otherwise it is set to zero.
1888    
1889             PCRE_CONFIG_JIT
1890    
1891           The output is an integer that is set to one if support for just-in-time
1892           compiling is available; otherwise it is set to zero.
1893    
1894             PCRE_CONFIG_JITTARGET
1895    
1896           The  output is a pointer to a zero-terminated "const char *" string. If
1897           JIT support is available, the string contains the name of the architec-
1898           ture  for  which the JIT compiler is configured, for example "x86 32bit
1899           (little endian + unaligned)". If JIT  support  is  not  available,  the
1900           result is NULL.
1901    
1902           PCRE_CONFIG_NEWLINE           PCRE_CONFIG_NEWLINE
1903    
1904         The output is an integer whose value specifies  the  default  character         The  output  is  an integer whose value specifies the default character
1905         sequence  that is recognized as meaning "newline". The four values that         sequence that is recognized as meaning "newline". The values  that  are
1906         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
1907         and  -1  for  ANY. The default should normally be the standard sequence         for CRLF, -2 for ANYCRLF, and -1 for ANY. In EBCDIC  environments,  CR,
1908         for your operating system.         ANYCRLF,  and  ANY  yield the same values. However, the value for LF is
1909           normally 21, though some EBCDIC environments use 37. The  corresponding
1910           values  for  CRLF are 3349 and 3365. The default should normally corre-
1911           spond to the standard sequence for your operating system.
1912    
1913             PCRE_CONFIG_BSR
1914    
1915           The output is an integer whose value indicates what character sequences
1916           the  \R  escape sequence matches by default. A value of 0 means that \R
1917           matches any Unicode line ending sequence; a value of 1  means  that  \R
1918           matches only CR, LF, or CRLF. The default can be overridden when a pat-
1919           tern is compiled or matched.
1920    
1921           PCRE_CONFIG_LINK_SIZE           PCRE_CONFIG_LINK_SIZE
1922    
1923         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
1924         internal linkage in compiled regular expressions. The value is 2, 3, or         internal  linkage  in  compiled  regular  expressions.  For  the  8-bit
1925         4. Larger values allow larger regular expressions to  be  compiled,  at         library, the value can be 2, 3, or 4. For the 16-bit library, the value
1926         the  expense  of  slower matching. The default value of 2 is sufficient         is  either  2  or  4  and  is  still  a number of bytes. For the 32-bit
1927         for all but the most massive patterns, since  it  allows  the  compiled         library, the value is either 2 or 4 and is still a number of bytes. The
1928         pattern to be up to 64K in size.         default value of 2 is sufficient for all but the most massive patterns,
1929           since it allows the compiled pattern to be up to 64K  in  size.  Larger
1930           values  allow larger regular expressions to be compiled, at the expense
1931           of slower matching.
1932    
1933           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
1934    
1935         The  output  is  an integer that contains the threshold above which the         The output is an integer that contains the threshold  above  which  the
1936         POSIX interface uses malloc() for output vectors. Further  details  are         POSIX  interface  uses malloc() for output vectors. Further details are
1937         given in the pcreposix documentation.         given in the pcreposix documentation.
1938    
1939           PCRE_CONFIG_MATCH_LIMIT           PCRE_CONFIG_MATCH_LIMIT
1940    
1941         The output is an integer that gives the default limit for the number of         The output is a long integer that gives the default limit for the  num-
1942         internal matching function calls in a  pcre_exec()  execution.  Further         ber  of  internal  matching  function calls in a pcre_exec() execution.
1943         details are given with pcre_exec() below.         Further details are given with pcre_exec() below.
1944    
1945           PCRE_CONFIG_MATCH_LIMIT_RECURSION           PCRE_CONFIG_MATCH_LIMIT_RECURSION
1946    
1947         The  output is an integer that gives the default limit for the depth of         The output is a long integer that gives the default limit for the depth
1948         recursion when calling the internal matching function in a  pcre_exec()         of   recursion  when  calling  the  internal  matching  function  in  a
1949         execution. Further details are given with pcre_exec() below.         pcre_exec() execution.  Further  details  are  given  with  pcre_exec()
1950           below.
1951    
1952           PCRE_CONFIG_STACKRECURSE           PCRE_CONFIG_STACKRECURSE
1953    
# Line 990  COMPILING A PATTERN Line 1974  COMPILING A PATTERN
1974         Either of the functions pcre_compile() or pcre_compile2() can be called         Either of the functions pcre_compile() or pcre_compile2() can be called
1975         to compile a pattern into an internal form. The only difference between         to compile a pattern into an internal form. The only difference between
1976         the  two interfaces is that pcre_compile2() has an additional argument,         the  two interfaces is that pcre_compile2() has an additional argument,
1977         errorcodeptr, via which a numerical error code can be returned.         errorcodeptr, via which a numerical error  code  can  be  returned.  To
1978           avoid  too  much repetition, we refer just to pcre_compile() below, but
1979           the information applies equally to pcre_compile2().
1980    
1981         The pattern is a C string terminated by a binary zero, and is passed in         The pattern is a C string terminated by a binary zero, and is passed in
1982         the  pattern  argument.  A  pointer to a single block of memory that is         the  pattern  argument.  A  pointer to a single block of memory that is
# Line 1007  COMPILING A PATTERN Line 1993  COMPILING A PATTERN
1993    
1994         The options argument contains various bit settings that affect the com-         The options argument contains various bit settings that affect the com-
1995         pilation. It should be zero if no options are required.  The  available         pilation. It should be zero if no options are required.  The  available
1996         options  are  described  below. Some of them, in particular, those that         options  are  described  below. Some of them (in particular, those that
1997         are compatible with Perl, can also be set and  unset  from  within  the         are compatible with Perl, but some others as well) can also be set  and
1998         pattern  (see  the  detailed  description in the pcrepattern documenta-         unset  from  within  the  pattern  (see the detailed description in the
1999         tion). For these options, the contents of the options  argument  speci-         pcrepattern documentation). For those options that can be different  in
2000         fies  their initial settings at the start of compilation and execution.         different  parts  of  the pattern, the contents of the options argument
2001         The PCRE_ANCHORED and PCRE_NEWLINE_xxx options can be set at  the  time         specifies their settings at the start of compilation and execution. The
2002         of matching as well as at compile time.         PCRE_ANCHORED,  PCRE_BSR_xxx, PCRE_NEWLINE_xxx, PCRE_NO_UTF8_CHECK, and
2003           PCRE_NO_START_OPTIMIZE options can be set at the time  of  matching  as
2004           well as at compile time.
2005    
2006         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,
2007         if compilation of a pattern fails,  pcre_compile()  returns  NULL,  and         if compilation of a pattern fails,  pcre_compile()  returns  NULL,  and
2008         sets the variable pointed to by errptr to point to a textual error mes-         sets the variable pointed to by errptr to point to a textual error mes-
2009         sage. This is a static string that is part of the library. You must not         sage. This is a static string that is part of the library. You must not
2010         try to free it. The offset from the start of the pattern to the charac-         try  to  free it. Normally, the offset from the start of the pattern to
2011         ter where the error was discovered is placed in the variable pointed to         the byte that was being processed when  the  error  was  discovered  is
2012         by  erroffset,  which must not be NULL. If it is, an immediate error is         placed  in the variable pointed to by erroffset, which must not be NULL
2013         given.         (if it is, an immediate error is given). However, for an invalid  UTF-8
2014           string, the offset is that of the first byte of the failing character.
2015    
2016           Some  errors are not detected until the whole pattern has been scanned;
2017           in these cases, the offset passed back is the length  of  the  pattern.
2018           Note  that  the offset is in bytes, not characters, even in UTF-8 mode.
2019           It may sometimes point into the middle of a UTF-8 character.
2020    
2021         If pcre_compile2() is used instead of pcre_compile(),  and  the  error-         If pcre_compile2() is used instead of pcre_compile(),  and  the  error-
2022         codeptr  argument is not NULL, a non-zero error code number is returned         codeptr  argument is not NULL, a non-zero error code number is returned
# Line 1067  COMPILING A PATTERN Line 2061  COMPILING A PATTERN
2061         all with number 255, before each pattern item. For  discussion  of  the         all with number 255, before each pattern item. For  discussion  of  the
2062         callout facility, see the pcrecallout documentation.         callout facility, see the pcrecallout documentation.
2063    
2064             PCRE_BSR_ANYCRLF
2065             PCRE_BSR_UNICODE
2066    
2067           These options (which are mutually exclusive) control what the \R escape
2068           sequence matches. The choice is either to match only CR, LF,  or  CRLF,
2069           or to match any Unicode newline sequence. The default is specified when
2070           PCRE is built. It can be overridden from within the pattern, or by set-
2071           ting an option when a compiled pattern is matched.
2072    
2073           PCRE_CASELESS           PCRE_CASELESS
2074    
2075         If  this  bit is set, letters in the pattern match both upper and lower         If  this  bit is set, letters in the pattern match both upper and lower
# Line 1091  COMPILING A PATTERN Line 2094  COMPILING A PATTERN
2094    
2095           PCRE_DOTALL           PCRE_DOTALL
2096    
2097         If this bit is set, a dot metacharater in the pattern matches all char-         If  this bit is set, a dot metacharacter in the pattern matches a char-
2098         acters, including those that indicate newline. Without it, a  dot  does         acter of any value, including one that indicates a newline. However, it
2099         not  match  when  the  current position is at a newline. This option is         only  ever  matches  one character, even if newlines are coded as CRLF.
2100         equivalent to Perl's /s option, and it can be changed within a  pattern         Without this option, a dot does not match when the current position  is
2101         by  a (?s) option setting. A negative class such as [^a] always matches         at a newline. This option is equivalent to Perl's /s option, and it can
2102         newline characters, independent of the setting of this option.         be changed within a pattern by a (?s) option setting. A negative  class
2103           such as [^a] always matches newline characters, independent of the set-
2104           ting of this option.
2105    
2106           PCRE_DUPNAMES           PCRE_DUPNAMES
2107    
# Line 1108  COMPILING A PATTERN Line 2113  COMPILING A PATTERN
2113    
2114           PCRE_EXTENDED           PCRE_EXTENDED
2115    
2116         If this bit is set, whitespace  data  characters  in  the  pattern  are         If this bit is set, white space data  characters  in  the  pattern  are
2117         totally ignored except when escaped or inside a character class. White-         totally  ignored except when escaped or inside a character class. White
2118         space does not include the VT character (code 11). In addition, charac-         space does not include the VT character (code 11). In addition, charac-
2119         ters between an unescaped # outside a character class and the next new-         ters between an unescaped # outside a character class and the next new-
2120         line, inclusive, are also ignored. This  is  equivalent  to  Perl's  /x         line, inclusive, are also ignored. This  is  equivalent  to  Perl's  /x
2121         option,  and  it  can be changed within a pattern by a (?x) option set-         option,  and  it  can be changed within a pattern by a (?x) option set-
2122         ting.         ting.
2123    
2124         This option makes it possible to include  comments  inside  complicated         Which characters are interpreted  as  newlines  is  controlled  by  the
2125         patterns.   Note,  however,  that this applies only to data characters.         options  passed to pcre_compile() or by a special sequence at the start
2126         Whitespace  characters  may  never  appear  within  special   character         of the pattern, as described in the section entitled  "Newline  conven-
2127         sequences  in  a  pattern,  for  example  within the sequence (?( which         tions" in the pcrepattern documentation. Note that the end of this type
2128         introduces a conditional subpattern.         of comment is  a  literal  newline  sequence  in  the  pattern;  escape
2129           sequences that happen to represent a newline do not count.
2130    
2131           This  option  makes  it possible to include comments inside complicated
2132           patterns.  Note, however, that this applies only  to  data  characters.
2133           White  space  characters  may  never  appear  within  special character
2134           sequences in a pattern, for example within the sequence (?( that intro-
2135           duces a conditional subpattern.
2136    
2137           PCRE_EXTRA           PCRE_EXTRA
2138    
2139         This option was invented in order to turn on  additional  functionality         This  option  was invented in order to turn on additional functionality
2140         of  PCRE  that  is  incompatible with Perl, but it is currently of very         of PCRE that is incompatible with Perl, but it  is  currently  of  very
2141         little use. When set, any backslash in a pattern that is followed by  a         little  use. When set, any backslash in a pattern that is followed by a
2142         letter  that  has  no  special  meaning causes an error, thus reserving         letter that has no special meaning  causes  an  error,  thus  reserving
2143         these combinations for future expansion. By  default,  as  in  Perl,  a         these  combinations  for  future  expansion.  By default, as in Perl, a
2144         backslash  followed by a letter with no special meaning is treated as a         backslash followed by a letter with no special meaning is treated as  a
2145         literal. (Perl can, however, be persuaded to give a warning for  this.)         literal. (Perl can, however, be persuaded to give an error for this, by
2146         There  are  at  present no other features controlled by this option. It         running it with the -w option.) There are at present no other  features
2147         can also be set by a (?X) option setting within a pattern.         controlled  by this option. It can also be set by a (?X) option setting
2148           within a pattern.
2149    
2150           PCRE_FIRSTLINE           PCRE_FIRSTLINE
2151    
# Line 1140  COMPILING A PATTERN Line 2153  COMPILING A PATTERN
2153         before  or  at  the  first  newline  in  the subject string, though the         before  or  at  the  first  newline  in  the subject string, though the
2154         matched text may continue over the newline.         matched text may continue over the newline.
2155    
2156             PCRE_JAVASCRIPT_COMPAT
2157    
2158           If this option is set, PCRE's behaviour is changed in some ways so that
2159           it  is  compatible with JavaScript rather than Perl. The changes are as
2160           follows:
2161    
2162           (1) A lone closing square bracket in a pattern  causes  a  compile-time
2163           error,  because this is illegal in JavaScript (by default it is treated
2164           as a data character). Thus, the pattern AB]CD becomes illegal when this
2165           option is set.
2166    
2167           (2)  At run time, a back reference to an unset subpattern group matches
2168           an empty string (by default this causes the current  matching  alterna-
2169           tive  to  fail). A pattern such as (\1)(a) succeeds when this option is
2170           set (assuming it can find an "a" in the subject), whereas it  fails  by
2171           default, for Perl compatibility.
2172    
2173           (3) \U matches an upper case "U" character; by default \U causes a com-
2174           pile time error (Perl uses \U to upper case subsequent characters).
2175    
2176           (4) \u matches a lower case "u" character unless it is followed by four
2177           hexadecimal  digits,  in  which case the hexadecimal number defines the
2178           code point to match. By default, \u causes a compile time  error  (Perl
2179           uses it to upper case the following character).
2180    
2181           (5)  \x matches a lower case "x" character unless it is followed by two
2182           hexadecimal digits, in which case the hexadecimal  number  defines  the
2183           code  point  to  match. By default, as in Perl, a hexadecimal number is
2184           always expected after \x, but it may have zero, one, or two digits (so,
2185           for example, \xz matches a binary zero character followed by z).
2186    
2187           PCRE_MULTILINE           PCRE_MULTILINE
2188    
2189         By default, PCRE treats the subject string as consisting  of  a  single         By  default,  PCRE  treats the subject string as consisting of a single
2190         line  of characters (even if it actually contains newlines). The "start         line of characters (even if it actually contains newlines). The  "start
2191         of line" metacharacter (^) matches only at the  start  of  the  string,         of  line"  metacharacter  (^)  matches only at the start of the string,
2192         while  the  "end  of line" metacharacter ($) matches only at the end of         while the "end of line" metacharacter ($) matches only at  the  end  of
2193         the string, or before a terminating newline (unless PCRE_DOLLAR_ENDONLY         the string, or before a terminating newline (unless PCRE_DOLLAR_ENDONLY
2194         is set). This is the same as Perl.         is set). This is the same as Perl.
2195    
2196         When  PCRE_MULTILINE  it  is set, the "start of line" and "end of line"         When PCRE_MULTILINE it is set, the "start of line" and  "end  of  line"
2197         constructs match immediately following or immediately  before  internal         constructs  match  immediately following or immediately before internal
2198         newlines  in  the  subject string, respectively, as well as at the very         newlines in the subject string, respectively, as well as  at  the  very
2199         start and end. This is equivalent to Perl's /m option, and  it  can  be         start  and  end.  This is equivalent to Perl's /m option, and it can be
2200         changed within a pattern by a (?m) option setting. If there are no new-         changed within a pattern by a (?m) option setting. If there are no new-
2201         lines in a subject string, or no occurrences of ^ or $  in  a  pattern,         lines  in  a  subject string, or no occurrences of ^ or $ in a pattern,
2202         setting PCRE_MULTILINE has no effect.         setting PCRE_MULTILINE has no effect.
2203    
2204           PCRE_NEWLINE_CR           PCRE_NEWLINE_CR
# Line 1163  COMPILING A PATTERN Line 2207  COMPILING A PATTERN
2207           PCRE_NEWLINE_ANYCRLF           PCRE_NEWLINE_ANYCRLF
2208           PCRE_NEWLINE_ANY           PCRE_NEWLINE_ANY
2209    
2210         These  options  override the default newline definition that was chosen         These options override the default newline definition that  was  chosen
2211         when PCRE was built. Setting the first or the second specifies  that  a         when  PCRE  was built. Setting the first or the second specifies that a
2212         newline  is  indicated  by a single character (CR or LF, respectively).         newline is indicated by a single character (CR  or  LF,  respectively).
2213         Setting PCRE_NEWLINE_CRLF specifies that a newline is indicated by  the         Setting  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the
2214         two-character  CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF specifies         two-character CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF  specifies
2215         that any of the three preceding sequences should be recognized. Setting         that any of the three preceding sequences should be recognized. Setting
2216         PCRE_NEWLINE_ANY  specifies that any Unicode newline sequence should be         PCRE_NEWLINE_ANY specifies that any Unicode newline sequence should  be
2217         recognized. The Unicode newline sequences are the three just mentioned,         recognized.
2218         plus  the  single  characters  VT (vertical tab, U+000B), FF (formfeed,  
2219         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
2220         (paragraph  separator,  U+2029).  The  last  two are recognized only in         three just mentioned, plus the  single  characters  VT  (vertical  tab,
2221         UTF-8 mode.         U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line sep-
2222           arator, U+2028), and PS (paragraph separator, U+2029).  For  the  8-bit
2223           library, the last two are recognized only in UTF-8 mode.
2224    
2225           When  PCRE is compiled to run in an EBCDIC (mainframe) environment, the
2226           code for CR is 0x0d, the same as ASCII. However, the character code for
2227           LF  is  normally 0x15, though in some EBCDIC environments 0x25 is used.
2228           Whichever of these is not LF is made to  correspond  to  Unicode's  NEL
2229           character.  EBCDIC  codes  are all less than 256. For more details, see
2230           the pcrebuild documentation.
2231    
2232         The newline setting in the  options  word  uses  three  bits  that  are         The newline setting in the  options  word  uses  three  bits  that  are
2233         treated as a number, giving eight possibilities. Currently only six are         treated as a number, giving eight possibilities. Currently only six are
# Line 1184  COMPILING A PATTERN Line 2237  COMPILING A PATTERN
2237         PCRE_NEWLINE_CRLF,  but other combinations may yield unused numbers and         PCRE_NEWLINE_CRLF,  but other combinations may yield unused numbers and
2238         cause an error.         cause an error.
2239    
2240         The only time that a line break is specially recognized when  compiling         The only time that a line break in a pattern  is  specially  recognized
2241         a  pattern  is  if  PCRE_EXTENDED  is set, and an unescaped # outside a         when  compiling is when PCRE_EXTENDED is set. CR and LF are white space
2242         character class is encountered. This indicates  a  comment  that  lasts         characters, and so are ignored in this mode. Also, an unescaped #  out-
2243         until  after the next line break sequence. In other circumstances, line         side  a  character class indicates a comment that lasts until after the
2244         break  sequences  are  treated  as  literal  data,   except   that   in         next line break sequence. In other circumstances, line break  sequences
2245         PCRE_EXTENDED mode, both CR and LF are treated as whitespace characters         in patterns are treated as literal data.
        and are therefore ignored.  
2246    
2247         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
2248         is  used for pcre_exec() and pcre_dfa_exec(), but it can be overridden.         is used for pcre_exec() and pcre_dfa_exec(), but it can be overridden.
2249    
2250           PCRE_NO_AUTO_CAPTURE           PCRE_NO_AUTO_CAPTURE
2251    
# Line 1203  COMPILING A PATTERN Line 2255  COMPILING A PATTERN
2255         be  used  for  capturing  (and  they acquire numbers in the usual way).         be  used  for  capturing  (and  they acquire numbers in the usual way).
2256         There is no equivalent of this option in Perl.         There is no equivalent of this option in Perl.
2257    
2258             NO_START_OPTIMIZE
2259    
2260           This is an option that acts at matching time; that is, it is really  an
2261           option  for  pcre_exec()  or  pcre_dfa_exec().  If it is set at compile
2262           time, it is remembered with the compiled pattern and assumed at  match-
2263           ing  time.  For  details  see  the discussion of PCRE_NO_START_OPTIMIZE
2264           below.
2265    
2266             PCRE_UCP
2267    
2268           This option changes the way PCRE processes \B, \b, \D, \d, \S, \s,  \W,
2269           \w,  and  some  of  the POSIX character classes. By default, only ASCII
2270           characters are recognized, but if PCRE_UCP is set,  Unicode  properties
2271           are  used instead to classify characters. More details are given in the
2272           section on generic character types in the pcrepattern page. If you  set
2273           PCRE_UCP,  matching  one of the items it affects takes much longer. The
2274           option is available only if PCRE has been compiled with  Unicode  prop-
2275           erty support.
2276    
2277           PCRE_UNGREEDY           PCRE_UNGREEDY
2278    
2279         This option inverts the "greediness" of the quantifiers  so  that  they         This  option  inverts  the "greediness" of the quantifiers so that they
2280         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
2281         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
2282         within the pattern.         within the pattern.
2283    
2284           PCRE_UTF8           PCRE_UTF8
2285    
2286         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
2287         strings of UTF-8 characters instead of single-byte  character  strings.         strings of UTF-8 characters instead of single-byte strings. However, it
2288         However,  it is available only when PCRE is built to include UTF-8 sup-         is available only when PCRE is built to include UTF  support.  If  not,
2289         port. If not, the use of this option provokes an error. Details of  how         the  use  of  this option provokes an error. Details of how this option
2290         this  option  changes the behaviour of PCRE are given in the section on         changes the behaviour of PCRE are given in the pcreunicode page.
        UTF-8 support in the main pcre page.  
2291    
2292           PCRE_NO_UTF8_CHECK           PCRE_NO_UTF8_CHECK
2293    
2294         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
2295         automatically  checked. If an invalid UTF-8 sequence of bytes is found,         automatically  checked.  There  is  a  discussion about the validity of
2296         pcre_compile() returns an error. If you already know that your  pattern         UTF-8 strings in the pcreunicode page. If an invalid UTF-8 sequence  is
2297         is  valid, and you want to skip this check for performance reasons, you         found,  pcre_compile()  returns an error. If you already know that your
2298         can set the PCRE_NO_UTF8_CHECK option. When it is set,  the  effect  of         pattern is valid, and you want to skip this check for performance  rea-
2299         passing an invalid UTF-8 string as a pattern is undefined. It may cause         sons,  you  can set the PCRE_NO_UTF8_CHECK option.  When it is set, the
2300         your program to crash.  Note that this option can  also  be  passed  to         effect of passing an invalid UTF-8 string as a pattern is undefined. It
2301         pcre_exec()  and pcre_dfa_exec(), to suppress the UTF-8 validity check-         may  cause  your  program  to  crash. Note that this option can also be
2302         ing of subject strings.         passed to pcre_exec() and pcre_dfa_exec(),  to  suppress  the  validity
2303           checking  of  subject strings only. If the same string is being matched
2304           many times, the option can be safely set for the second and  subsequent
2305           matchings to improve performance.
2306    
2307    
2308  COMPILATION ERROR CODES  COMPILATION ERROR CODES
2309    
2310         The following table lists the error  codes  than  may  be  returned  by         The  following  table  lists  the  error  codes than may be returned by
2311         pcre_compile2(),  along with the error messages that may be returned by         pcre_compile2(), along with the error messages that may be returned  by
2312         both compiling functions. As PCRE has developed, some error codes  have         both  compiling  functions.  Note  that error messages are always 8-bit
2313         fallen out of use. To avoid confusion, they have not been re-used.         ASCII strings, even in 16-bit or 32-bit mode. As  PCRE  has  developed,
2314           some  error codes have fallen out of use. To avoid confusion, they have
2315           not been re-used.
2316    
2317            0  no error            0  no error
2318            1  \ at end of pattern            1  \ at end of pattern
# Line 1251  COMPILATION ERROR CODES Line 2326  COMPILATION ERROR CODES
2326            9  nothing to repeat            9  nothing to repeat
2327           10  [this code is not in use]           10  [this code is not in use]
2328           11  internal error: unexpected repeat           11  internal error: unexpected repeat
2329           12  unrecognized character after (?           12  unrecognized character after (? or (?-
2330           13  POSIX named classes are supported only within a class           13  POSIX named classes are supported only within a class
2331           14  missing )           14  missing )
2332           15  reference to non-existent subpattern           15  reference to non-existent subpattern
# Line 1259  COMPILATION ERROR CODES Line 2334  COMPILATION ERROR CODES
2334           17  unknown option bit(s) set           17  unknown option bit(s) set
2335           18  missing ) after comment           18  missing ) after comment
2336           19  [this code is not in use]           19  [this code is not in use]
2337           20  regular expression too large           20  regular expression is too large
2338           21  failed to get memory           21  failed to get memory
2339           22  unmatched parentheses           22  unmatched parentheses
2340           23  internal error: code overflow           23  internal error: code overflow
# Line 1271  COMPILATION ERROR CODES Line 2346  COMPILATION ERROR CODES
2346           29  (?R or (?[+-]digits must be followed by )           29  (?R or (?[+-]digits must be followed by )
2347           30  unknown POSIX class name           30  unknown POSIX class name
2348           31  POSIX collating elements are not supported           31  POSIX collating elements are not supported
2349           32  this version of PCRE is not compiled with PCRE_UTF8 support           32  this version of PCRE is compiled without UTF support
2350           33  [this code is not in use]           33  [this code is not in use]
2351           34  character value in \x{...} sequence is too large           34  character value in \x{...} sequence is too large
2352           35  invalid condition (?(0)           35  invalid condition (?(0)
2353           36  \C not allowed in lookbehind assertion           36  \C not allowed in lookbehind assertion
2354           37  PCRE does not support \L, \l, \N, \U, or \u           37  PCRE does not support \L, \l, \N{name}, \U, or \u
2355           38  number after (?C is > 255           38  number after (?C is > 255
2356           39  closing ) for (?C expected           39  closing ) for (?C expected
2357           40  recursive call could loop indefinitely           40  recursive call could loop indefinitely
2358           41  unrecognized character after (?P           41  unrecognized character after (?P
2359           42  syntax error in subpattern name (missing terminator)           42  syntax error in subpattern name (missing terminator)
2360           43  two named subpatterns have the same name           43  two named subpatterns have the same name
2361           44  invalid UTF-8 string           44  invalid UTF-8 string (specifically UTF-8)
2362           45  support for \P, \p, and \X has not been compiled           45  support for \P, \p, and \X has not been compiled
2363           46  malformed \P or \p sequence           46  malformed \P or \p sequence
2364           47  unknown property name after \P or \p           47  unknown property name after \P or \p
2365           48  subpattern name is too long (maximum 32 characters)           48  subpattern name is too long (maximum 32 characters)
2366           49  too many named subpatterns (maximum 10,000)           49  too many named subpatterns (maximum 10000)
2367           50  [this code is not in use]           50  [this code is not in use]
2368           51  octal value is greater than \377 (not in UTF-8 mode)           51  octal value is greater than \377 in 8-bit non-UTF-8 mode
2369           52  internal error: overran compiling workspace           52  internal error: overran compiling workspace
2370           53   internal  error:  previously-checked  referenced  subpattern not           53  internal error: previously-checked referenced subpattern
2371         found                 not found
2372           54  DEFINE group contains more than one branch           54  DEFINE group contains more than one branch
2373           55  repeating a DEFINE group is not allowed           55  repeating a DEFINE group is not allowed
2374           56  inconsistent NEWLINE options"           56  inconsistent NEWLINE options
2375           57  \g is not followed by a braced name or an optionally braced           57  \g is not followed by a braced, angle-bracketed, or quoted
2376                 non-zero number                 name/number or by a plain number
2377           58  (?+ or (?- or (?(+ or (?(- must be followed by a non-zero number           58  a numbered reference must not be zero
2378             59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
2379             60  (*VERB) not recognized
2380             61  number is too big
2381             62  subpattern name expected
2382             63  digit expected after (?+
2383             64  ] is an invalid data character in JavaScript compatibility mode
2384             65  different names for subpatterns of the same number are
2385                   not allowed
2386             66  (*MARK) must have an argument
2387             67  this version of PCRE is not compiled with Unicode property
2388                   support
2389             68  \c must be followed by an ASCII character
2390             69  \k is not followed by a braced, angle-bracketed, or quoted name
2391             70  internal error: unknown opcode in find_fixedlength()
2392             71  \N is not supported in a class
2393             72  too many forward references
2394             73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
2395             74  invalid UTF-16 string (specifically UTF-16)
2396             75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
2397             76  character value in \u.... sequence is too large
2398             77  invalid UTF-32 string (specifically UTF-32)
2399    
2400           The numbers 32 and 10000 in errors 48 and 49  are  defaults;  different
2401           values may be used if the limits were changed when PCRE was built.
2402    
2403    
2404  STUDYING A PATTERN  STUDYING A PATTERN
# Line 1307  STUDYING A PATTERN Line 2406  STUDYING A PATTERN
2406         pcre_extra *pcre_study(const pcre *code, int options         pcre_extra *pcre_study(const pcre *code, int options
2407              const char **errptr);              const char **errptr);
2408    
2409         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
2410         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
2411         matching. The function pcre_study() takes a pointer to a compiled  pat-         matching.  The function pcre_study() takes a pointer to a compiled pat-
2412         tern as its first argument. If studying the pattern produces additional         tern as its first argument. If studying the pattern produces additional
2413         information that will help speed up matching,  pcre_study()  returns  a         information  that  will  help speed up matching, pcre_study() returns a
2414         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
2415         the results of the study.         the results of the study.
2416    
2417         The  returned  value  from  pcre_study()  can  be  passed  directly  to         The  returned  value  from  pcre_study()  can  be  passed  directly  to
2418         pcre_exec().  However,  a  pcre_extra  block also contains other fields         pcre_exec() or pcre_dfa_exec(). However, a pcre_extra block  also  con-
2419         that can be set by the caller before the block  is  passed;  these  are         tains  other  fields  that can be set by the caller before the block is
2420         described below in the section on matching a pattern.         passed; these are described below in the section on matching a pattern.
2421    
2422         If  studying  the  pattern  does not produce any additional information         If studying the  pattern  does  not  produce  any  useful  information,
2423         pcre_study() returns NULL. In that circumstance, if the calling program         pcre_study()  returns  NULL  by  default.  In that circumstance, if the
2424         wants  to  pass  any of the other fields to pcre_exec(), it must set up         calling program wants to pass any of the other fields to pcre_exec() or
2425         its own pcre_extra block.         pcre_dfa_exec(),  it  must set up its own pcre_extra block. However, if
2426           pcre_study() is called  with  the  PCRE_STUDY_EXTRA_NEEDED  option,  it
2427         The second argument of pcre_study() contains option bits.  At  present,         returns a pcre_extra block even if studying did not find any additional
2428         no options are defined, and this argument should always be zero.         information. It may still return NULL, however, if an error  occurs  in
2429           pcre_study().
2430         The  third argument for pcre_study() is a pointer for an error message.  
2431         If studying succeeds (even if no data is  returned),  the  variable  it         The  second  argument  of  pcre_study() contains option bits. There are
2432         points  to  is  set  to NULL. Otherwise it is set to point to a textual         three further options in addition to PCRE_STUDY_EXTRA_NEEDED:
2433    
2434             PCRE_STUDY_JIT_COMPILE
2435             PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
2436             PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
2437    
2438           If any of these are set, and the just-in-time  compiler  is  available,
2439           the  pattern  is  further compiled into machine code that executes much
2440           faster than the pcre_exec()  interpretive  matching  function.  If  the
2441           just-in-time  compiler is not available, these options are ignored. All
2442           undefined bits in the options argument must be zero.
2443    
2444           JIT compilation is a heavyweight optimization. It can  take  some  time
2445           for  patterns  to  be analyzed, and for one-off matches and simple pat-
2446           terns the benefit of faster execution might be offset by a much  slower
2447           study time.  Not all patterns can be optimized by the JIT compiler. For
2448           those that cannot be handled, matching automatically falls back to  the
2449           pcre_exec()  interpreter.  For more details, see the pcrejit documenta-
2450           tion.
2451    
2452           The third argument for pcre_study() is a pointer for an error  message.
2453           If  studying  succeeds  (even  if no data is returned), the variable it
2454           points to is set to NULL. Otherwise it is set to  point  to  a  textual
2455         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
2456         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
2457         after calling pcre_study(), to be sure that it has run successfully.         after calling pcre_study(), to be sure that it has run successfully.
2458    
2459         This is a typical call to pcre_study():         When  you are finished with a pattern, you can free the memory used for
2460           the study data by calling pcre_free_study(). This function was added to
2461           the  API  for  release  8.20. For earlier versions, the memory could be
2462           freed with pcre_free(), just like the pattern itself. This  will  still
2463           work  in  cases where JIT optimization is not used, but it is advisable
2464           to change to the new function when convenient.
2465    
2466           This is a typical way in which pcre_study() is used (except that  in  a
2467           real application there should be tests for errors):
2468    
2469           pcre_extra *pe;           int rc;
2470           pe = pcre_study(           pcre *re;
2471             pcre_extra *sd;
2472             re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
2473             sd = pcre_study(
2474             re,             /* result of pcre_compile() */             re,             /* result of pcre_compile() */
2475             0,              /* no options exist */             0,              /* no options */
2476             &error);        /* set to NULL or points to a message */             &error);        /* set to NULL or points to a message */
2477             rc = pcre_exec(   /* see below for details of pcre_exec() options */
2478         At present, studying a pattern is useful only for non-anchored patterns             re, sd, "subject", 7, 0, 0, ovector, 30);
2479         that  do not have a single fixed starting character. A bitmap of possi-           ...
2480         ble starting bytes is created.           pcre_free_study(sd);
2481             pcre_free(re);
2482    
2483           Studying a pattern does two things: first, a lower bound for the length
2484           of subject string that is needed to match the pattern is computed. This
2485           does not mean that there are any strings of that length that match, but
2486           it does guarantee that no shorter strings match. The value is  used  to
2487           avoid wasting time by trying to match strings that are shorter than the
2488           lower bound. You can find out the value in a calling  program  via  the
2489           pcre_fullinfo() function.
2490    
2491           Studying a pattern is also useful for non-anchored patterns that do not
2492           have a single fixed starting character. A bitmap of  possible  starting
2493           bytes  is  created. This speeds up finding a position in the subject at
2494           which to start matching. (In 16-bit mode, the bitmap is used for 16-bit
2495           values  less  than  256.  In 32-bit mode, the bitmap is used for 32-bit
2496           values less than 256.)
2497    
2498           These two optimizations apply to both pcre_exec() and  pcre_dfa_exec(),
2499           and  the  information  is also used by the JIT compiler.  The optimiza-
2500           tions can be disabled by setting the PCRE_NO_START_OPTIMIZE option when
2501           calling pcre_exec() or pcre_dfa_exec(), but if this is done, JIT execu-
2502           tion is also disabled. You might want to do this if your  pattern  con-
2503           tains  callouts or (*MARK) and you want to make use of these facilities
2504           in   cases   where   matching   fails.   See    the    discussion    of
2505           PCRE_NO_START_OPTIMIZE below.
2506    
2507    
2508  LOCALE SUPPORT  LOCALE SUPPORT
2509    
2510         PCRE handles caseless matching, and determines whether  characters  are         PCRE  handles  caseless matching, and determines whether characters are
2511         letters,  digits, or whatever, by reference to a set of tables, indexed         letters, digits, or whatever, by reference to a set of tables,  indexed
2512         by character value. When running in UTF-8 mode, this  applies  only  to         by  character  value.  When running in UTF-8 mode, this applies only to
2513         characters  with  codes  less than 128. Higher-valued codes never match         characters with codes less than 128. By  default,  higher-valued  codes
2514         escapes such as \w or \d, but can be tested with \p if  PCRE  is  built         never match escapes such as \w or \d, but they can be tested with \p if
2515         with  Unicode  character property support. The use of locales with Uni-         PCRE is built with Unicode character property  support.  Alternatively,
2516         code is discouraged. If you are handling characters with codes  greater         the  PCRE_UCP  option  can  be  set at compile time; this causes \w and
2517         than  128, you should either use UTF-8 and Unicode, or use locales, but         friends to use Unicode property support instead of built-in tables. The
2518         not try to mix the two.         use of locales with Unicode is discouraged. If you are handling charac-
2519           ters with codes greater than 128, you should either use UTF-8 and  Uni-
2520           code, or use locales, but not try to mix the two.
2521    
2522         PCRE contains an internal set of tables that are used  when  the  final         PCRE  contains  an  internal set of tables that are used when the final
2523         argument  of  pcre_compile()  is  NULL.  These  are sufficient for many         argument of pcre_compile() is  NULL.  These  are  sufficient  for  many
2524         applications.  Normally, the internal tables recognize only ASCII char-         applications.  Normally, the internal tables recognize only ASCII char-
2525         acters. However, when PCRE is built, it is possible to cause the inter-         acters. However, when PCRE is built, it is possible to cause the inter-
2526         nal tables to be rebuilt in the default "C" locale of the local system,         nal tables to be rebuilt in the default "C" locale of the local system,
2527         which may cause them to be different.         which may cause them to be different.
2528    
2529         The  internal tables can always be overridden by tables supplied by the         The internal tables can always be overridden by tables supplied by  the
2530         application that calls PCRE. These may be created in a different locale         application that calls PCRE. These may be created in a different locale
2531         from  the  default.  As more and more applications change to using Uni-         from the default. As more and more applications change  to  using  Uni-
2532         code, the need for this locale support is expected to die away.         code, the need for this locale support is expected to die away.
2533    
2534         External tables are built by calling  the  pcre_maketables()  function,         External  tables  are  built by calling the pcre_maketables() function,
2535         which  has no arguments, in the relevant locale. The result can then be         which has no arguments, in the relevant locale. The result can then  be
2536         passed to pcre_compile() or pcre_exec()  as  often  as  necessary.  For         passed  to  pcre_compile()  or  pcre_exec()  as often as necessary. For
2537         example,  to  build  and use tables that are appropriate for the French         example, to build and use tables that are appropriate  for  the  French
2538         locale (where accented characters with  values  greater  than  128  are         locale  (where  accented  characters  with  values greater than 128 are
2539         treated as letters), the following code could be used:         treated as letters), the following code could be used:
2540    
2541           setlocale(LC_CTYPE, "fr_FR");           setlocale(LC_CTYPE, "fr_FR");
2542           tables = pcre_maketables();           tables = pcre_maketables();
2543           re = pcre_compile(..., tables);           re = pcre_compile(..., tables);
2544    
2545         The  locale  name "fr_FR" is used on Linux and other Unix-like systems;         The locale name "fr_FR" is used on Linux and other  Unix-like  systems;
2546         if you are using Windows, the name for the French locale is "french".         if you are using Windows, the name for the French locale is "french".
2547    
2548         When pcre_maketables() runs, the tables are built  in  memory  that  is         When  pcre_maketables()  runs,  the  tables are built in memory that is
2549         obtained  via  pcre_malloc. It is the caller's responsibility to ensure         obtained via pcre_malloc. It is the caller's responsibility  to  ensure
2550         that the memory containing the tables remains available for as long  as         that  the memory containing the tables remains available for as long as
2551         it is needed.         it is needed.
2552    
2553         The pointer that is passed to pcre_compile() is saved with the compiled         The pointer that is passed to pcre_compile() is saved with the compiled
2554         pattern, and the same tables are used via this pointer by  pcre_study()         pattern,  and the same tables are used via this pointer by pcre_study()
2555         and normally also by pcre_exec(). Thus, by default, for any single pat-         and normally also by pcre_exec(). Thus, by default, for any single pat-
2556         tern, compilation, studying and matching all happen in the same locale,         tern, compilation, studying and matching all happen in the same locale,
2557         but different patterns can be compiled in different locales.         but different patterns can be compiled in different locales.
2558    
2559         It  is  possible to pass a table pointer or NULL (indicating the use of         It is possible to pass a table pointer or NULL (indicating the  use  of
2560         the internal tables) to pcre_exec(). Although  not  intended  for  this         the  internal  tables)  to  pcre_exec(). Although not intended for this
2561         purpose,  this facility could be used to match a pattern in a different         purpose, this facility could be used to match a pattern in a  different
2562         locale from the one in which it was compiled. Passing table pointers at         locale from the one in which it was compiled. Passing table pointers at
2563         run time is discussed below in the section on matching a pattern.         run time is discussed below in the section on matching a pattern.
2564    
# Line 1409  INFORMATION ABOUT A PATTERN Line 2568  INFORMATION ABOUT A PATTERN
2568         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
2569              int what, void *where);              int what, void *where);
2570    
2571         The  pcre_fullinfo() function returns information about a compiled pat-         The pcre_fullinfo() function returns information about a compiled  pat-
2572         tern. It replaces the obsolete pcre_info() function, which is neverthe-         tern.  It replaces the pcre_info() function, which was removed from the
2573         less retained for backwards compability (and is documented below).         library at version 8.30, after more than 10 years of obsolescence.
2574    
2575         The  first  argument  for  pcre_fullinfo() is a pointer to the compiled         The first argument for pcre_fullinfo() is a  pointer  to  the  compiled
2576         pattern. The second argument is the result of pcre_study(), or NULL  if         pattern.  The second argument is the result of pcre_study(), or NULL if
2577         the  pattern  was not studied. The third argument specifies which piece         the pattern was not studied. The third argument specifies  which  piece
2578         of information is required, and the fourth argument is a pointer  to  a         of  information  is required, and the fourth argument is a pointer to a
2579         variable  to  receive  the  data. The yield of the function is zero for         variable to receive the data. The yield of the  function  is  zero  for
2580         success, or one of the following negative numbers:         success, or one of the following negative numbers:
2581    
2582           PCRE_ERROR_NULL       the argument code was NULL           PCRE_ERROR_NULL           the argument code was NULL
2583                                 the argument where was NULL                                     the argument where was NULL
2584           PCRE_ERROR_BADMAGIC   the "magic number" was not found           PCRE_ERROR_BADMAGIC       the "magic number" was not found
2585           PCRE_ERROR_BADOPTION  the value of what was invalid           PCRE_ERROR_BADENDIANNESS  the pattern was compiled with different
2586                                       endianness
2587         The "magic number" is placed at the start of each compiled  pattern  as           PCRE_ERROR_BADOPTION      the value of what was invalid
2588         an  simple check against passing an arbitrary memory pointer. Here is a  
2589         typical call of pcre_fullinfo(), to obtain the length of  the  compiled         The  "magic  number" is placed at the start of each compiled pattern as
2590         pattern:         an simple check against passing an arbitrary memory pointer. The  endi-
2591           anness error can occur if a compiled pattern is saved and reloaded on a
2592           different host. Here is a typical call of  pcre_fullinfo(),  to  obtain
2593           the length of the compiled pattern:
2594    
2595           int rc;           int rc;
2596           size_t length;           size_t length;
2597           rc = pcre_fullinfo(           rc = pcre_fullinfo(
2598             re,               /* result of pcre_compile() */             re,               /* result of pcre_compile() */
2599             pe,               /* result of pcre_study(), or NULL */             sd,               /* result of pcre_study(), or NULL */
2600             PCRE_INFO_SIZE,   /* what is required */             PCRE_INFO_SIZE,   /* what is required */
2601             &length);         /* where to put the data */             &length);         /* where to put the data */
2602    
# Line 1462  INFORMATION ABOUT A PATTERN Line 2624  INFORMATION ABOUT A PATTERN
2624    
2625           PCRE_INFO_FIRSTBYTE           PCRE_INFO_FIRSTBYTE
2626    
2627         Return  information  about  the first byte of any matched string, for a         Return information about the first data unit of any matched string, for
2628         non-anchored pattern. The fourth argument should point to an int  vari-         a non-anchored pattern. (The name of this option refers  to  the  8-bit
2629         able.  (This option used to be called PCRE_INFO_FIRSTCHAR; the old name         library,  where data units are bytes.) The fourth argument should point
2630         is still recognized for backwards compatibility.)         to an int variable.
2631    
2632           If there is a fixed first value, for example, the  letter  "c"  from  a
2633           pattern  such  as (cat|cow|coyote), its value is returned. In the 8-bit
2634           library, the value is always less than 256. In the 16-bit  library  the
2635           value can be up to 0xffff. In the 32-bit library the value can be up to
2636           0x10ffff.
2637    
2638         If there is a fixed first byte, for example, from  a  pattern  such  as         If there is no fixed first value, and if either
        (cat|cow|coyote), its value is returned. Otherwise, if either  
2639    
2640         (a)  the pattern was compiled with the PCRE_MULTILINE option, and every         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
2641         branch starts with "^", or         branch starts with "^", or
2642    
2643         (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
2644         set (if it were set, the pattern would be anchored),         set (if it were set, the pattern would be anchored),
2645    
2646         -1  is  returned, indicating that the pattern matches only at the start         -1 is returned, indicating that the pattern matches only at  the  start
2647         of a subject string or after any newline within the  string.  Otherwise         of  a  subject string or after any newline within the string. Otherwise
2648         -2 is returned. For anchored patterns, -2 is returned.         -2 is returned. For anchored patterns, -2 is returned.
2649    
2650           Since for the 32-bit library using the non-UTF-32 mode,  this  function
2651           is  unable to return the full 32-bit range of the character, this value
2652           is   deprecated;   instead   the   PCRE_INFO_FIRSTCHARACTERFLAGS    and
2653           PCRE_INFO_FIRSTCHARACTER values should be used.
2654    
2655           PCRE_INFO_FIRSTTABLE           PCRE_INFO_FIRSTTABLE
2656    
2657         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
2658         256-bit table indicating a fixed set of bytes for the first byte in any         256-bit table indicating a fixed set of values for the first data  unit
2659         matching  string, a pointer to the table is returned. Otherwise NULL is         in  any  matching string, a pointer to the table is returned. Otherwise
2660         returned. The fourth argument should point to an unsigned char *  vari-         NULL is returned. The fourth argument should point to an unsigned  char
2661         able.         * variable.
2662    
2663             PCRE_INFO_HASCRORLF
2664    
2665           Return  1  if  the  pattern  contains any explicit matches for CR or LF
2666           characters, otherwise 0. The fourth argument should  point  to  an  int
2667           variable.  An explicit match is either a literal CR or LF character, or
2668           \r or \n.
2669    
2670           PCRE_INFO_JCHANGED           PCRE_INFO_JCHANGED
2671    
2672         Return  1  if the (?J) option setting is used in the pattern, otherwise         Return 1 if the (?J) or (?-J) option setting is used  in  the  pattern,
2673         0. The fourth argument should point to an int variable. The (?J) inter-         otherwise  0. The fourth argument should point to an int variable. (?J)
2674         nal option setting changes the local PCRE_DUPNAMES option.         and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
2675    
2676             PCRE_INFO_JIT
2677    
2678           Return 1 if the pattern was studied with one of the  JIT  options,  and
2679           just-in-time compiling was successful. The fourth argument should point
2680           to an int variable. A return value of 0 means that JIT support  is  not
2681           available  in this version of PCRE, or that the pattern was not studied
2682           with a JIT option, or that the JIT compiler could not handle this  par-
2683           ticular  pattern. See the pcrejit documentation for details of what can
2684           and cannot be handled.
2685    
2686             PCRE_INFO_JITSIZE
2687    
2688           If the pattern was successfully studied with a JIT option,  return  the
2689           size  of the JIT compiled code, otherwise return zero. The fourth argu-
2690           ment should point to a size_t variable.
2691    
2692           PCRE_INFO_LASTLITERAL           PCRE_INFO_LASTLITERAL
2693    
2694         Return  the  value of the rightmost literal byte that must exist in any         Return the value of the rightmost literal data unit that must exist  in
2695         matched string, other than at its  start,  if  such  a  byte  has  been         any  matched  string, other than at its start, if such a value has been
2696         recorded. The fourth argument should point to an int variable. If there         recorded. The fourth argument should point to an int variable. If there
2697         is no such byte, -1 is returned. For anchored patterns, a last  literal         is no such value, -1 is returned. For anchored patterns, a last literal
2698         byte  is  recorded only if it follows something of variable length. For         value is recorded only if it follows something of variable length.  For
2699         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
2700         /^a\dz\d/ the returned value is -1.         /^a\dz\d/ the returned value is -1.
2701    
2702           Since for the 32-bit library using the non-UTF-32 mode,  this  function
2703           is  unable to return the full 32-bit range of the character, this value
2704           is   deprecated;   instead    the    PCRE_INFO_REQUIREDCHARFLAGS    and
2705           PCRE_INFO_REQUIREDCHAR values should be used.
2706    
2707             PCRE_INFO_MAXLOOKBEHIND
2708    
2709           Return  the  number of characters (NB not bytes) in the longest lookbe-
2710           hind assertion in the pattern. Note that the simple assertions  \b  and
2711           \B  require a one-character lookbehind. This information is useful when
2712           doing multi-segment matching using the partial matching facilities.
2713    
2714             PCRE_INFO_MINLENGTH
2715    
2716           If the pattern was studied and a minimum length  for  matching  subject
2717           strings  was  computed,  its  value is returned. Otherwise the returned
2718           value is -1. The value is a number of characters, which in  UTF-8  mode
2719           may  be  different from the number of bytes. The fourth argument should
2720           point to an int variable. A non-negative value is a lower bound to  the
2721           length  of  any  matching  string. There may not be any strings of that
2722           length that do actually match, but every string that does match  is  at
2723           least that long.
2724    
2725           PCRE_INFO_NAMECOUNT           PCRE_INFO_NAMECOUNT
2726           PCRE_INFO_NAMEENTRYSIZE           PCRE_INFO_NAMEENTRYSIZE
2727           PCRE_INFO_NAMETABLE           PCRE_INFO_NAMETABLE
# Line 1522  INFORMATION ABOUT A PATTERN Line 2740  INFORMATION ABOUT A PATTERN
2740         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size
2741         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
2742         depends on the length of the longest name. PCRE_INFO_NAMETABLE  returns         depends on the length of the longest name. PCRE_INFO_NAMETABLE  returns
2743         a  pointer  to  the  first  entry of the table (a pointer to char). The         a pointer to the first entry of the table. This is a pointer to char in
2744         first two bytes of each entry are the number of the capturing parenthe-         the 8-bit library, where the first two bytes of each entry are the num-
2745         sis,  most  significant byte first. The rest of the entry is the corre-         ber  of  the capturing parenthesis, most significant byte first. In the
2746         sponding name, zero terminated. The names are  in  alphabetical  order.         16-bit library, the pointer points to 16-bit data units, the  first  of
2747         When PCRE_DUPNAMES is set, duplicate names are in order of their paren-         which  contains  the  parenthesis  number.   In the 32-bit library, the
2748         theses numbers. For example, consider  the  following  pattern  (assume         pointer points to 32-bit data units, the first of  which  contains  the
2749         PCRE_EXTENDED  is  set,  so  white  space  -  including  newlines  - is         parenthesis  number.  The  rest of the entry is the corresponding name,
2750         ignored):         zero terminated.
2751    
2752           The names are in alphabetical order. Duplicate names may appear if  (?|
2753           is used to create multiple groups with the same number, as described in
2754           the section on duplicate subpattern numbers in  the  pcrepattern  page.
2755           Duplicate  names  for  subpatterns with different numbers are permitted
2756           only if PCRE_DUPNAMES is set. In all cases  of  duplicate  names,  they
2757           appear  in  the table in the order in which they were found in the pat-
2758           tern. In the absence of (?| this is the  order  of  increasing  number;
2759           when (?| is used this is not necessarily the case because later subpat-
2760           terns may have lower numbers.
2761    
2762           As a simple example of the name/number table,  consider  the  following
2763           pattern after compilation by the 8-bit library (assume PCRE_EXTENDED is
2764           set, so white space - including newlines - is ignored):
2765    
2766           (?<date> (?<year>(\d\d)?\d\d) -           (?<date> (?<year>(\d\d)?\d\d) -
2767           (?<month>\d\d) - (?<day>\d\d) )           (?<month>\d\d) - (?<day>\d\d) )
# Line 1550  INFORMATION ABOUT A PATTERN Line 2782  INFORMATION ABOUT A PATTERN
2782    
2783           PCRE_INFO_OKPARTIAL           PCRE_INFO_OKPARTIAL
2784    
2785         Return  1 if the pattern can be used for partial matching, otherwise 0.         Return  1  if  the  pattern  can  be  used  for  partial  matching with
2786         The fourth argument should point to an int  variable.  The  pcrepartial         pcre_exec(), otherwise 0. The fourth argument should point  to  an  int
2787         documentation  lists  the restrictions that apply to patterns when par-         variable.  From  release  8.00,  this  always  returns  1,  because the
2788         tial matching is used.         restrictions that previously applied  to  partial  matching  have  been
2789           lifted.  The  pcrepartial documentation gives details of partial match-
2790           ing.
2791    
2792           PCRE_INFO_OPTIONS           PCRE_INFO_OPTIONS
2793    
# Line 1580  INFORMATION ABOUT A PATTERN Line 2814  INFORMATION ABOUT A PATTERN
2814    
2815           PCRE_INFO_SIZE           PCRE_INFO_SIZE
2816    
2817         Return  the  size  of the compiled pattern, that is, the value that was         Return  the size of the compiled pattern in bytes (for both libraries).
2818         passed as the argument to pcre_malloc() when PCRE was getting memory in         The fourth argument should point to a size_t variable. This value  does
2819         which to place the compiled data. The fourth argument should point to a         not  include  the  size  of  the  pcre  structure  that  is returned by
2820         size_t variable.         pcre_compile(). The value that is passed as the argument  to  pcre_mal-
2821           loc()  when pcre_compile() is getting memory in which to place the com-
2822           piled data is the value returned by this option plus the  size  of  the
2823           pcre  structure. Studying a compiled pattern, with or without JIT, does
2824           not alter the value returned by this option.
2825    
2826           PCRE_INFO_STUDYSIZE           PCRE_INFO_STUDYSIZE
2827    
2828         Return the size of the data block pointed to by the study_data field in         Return the size in bytes of the data block pointed to by the study_data
2829         a  pcre_extra  block.  That  is,  it  is  the  value that was passed to         field  in  a  pcre_extra  block.  If pcre_extra is NULL, or there is no
2830         pcre_malloc() when PCRE was getting memory into which to place the data         study data, zero is returned. The fourth argument  should  point  to  a
2831         created  by  pcre_study(). The fourth argument should point to a size_t         size_t  variable. The study_data field is set by pcre_study() to record
2832           information that will speed  up  matching  (see  the  section  entitled
2833           "Studying a pattern" above). The format of the study_data block is pri-
2834           vate, but its length is made available via this option so that  it  can
2835           be  saved  and  restored  (see  the  pcreprecompile  documentation  for
2836           details).
2837    
2838             PCRE_INFO_FIRSTCHARACTERFLAGS
2839    
2840           Return information about the first data unit of any matched string, for
2841           a  non-anchored  pattern.  The  fourth  argument should point to an int
2842         variable.         variable.
2843    
2844           If there is a fixed first value, for example, the  letter  "c"  from  a
2845           pattern  such  as  (cat|cow|coyote),  1  is returned, and the character
2846           value can be retrieved using PCRE_INFO_FIRSTCHARACTER.
2847    
2848           If there is no fixed first value, and if either
2849    
2850           (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
2851           branch starts with "^", or
2852    
2853           (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2854           set (if it were set, the pattern would be anchored),
2855    
2856           2 is returned, indicating that the pattern matches only at the start of
2857           a subject string or after any newline within the string. Otherwise 0 is
2858           returned. For anchored patterns, 0 is returned.
2859    
2860             PCRE_INFO_FIRSTCHARACTER
2861    
2862           Return the fixed first character  value,  if  PCRE_INFO_FIRSTCHARACTER-
2863           FLAGS returned 1; otherwise returns 0. The fourth argument should point
2864           to an uint_t variable.
2865    
2866           In the 8-bit library, the value is always less than 256. In the  16-bit
2867           library  the value can be up to 0xffff. In the 32-bit library in UTF-32
2868           mode the value can be up to 0x10ffff, and up  to  0xffffffff  when  not
2869           using UTF-32 mode.
2870    
2871           If there is no fixed first value, and if either
2872    
2873           (a)  the pattern was compiled with the PCRE_MULTILINE option, and every
2874           branch starts with "^", or
2875    
2876           (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2877           set (if it were set, the pattern would be anchored),
2878    
2879  OBSOLETE INFO FUNCTION         -1  is  returned, indicating that the pattern matches only at the start
2880           of a subject string or after any newline within the  string.  Otherwise
2881           -2 is returned. For anchored patterns, -2 is returned.
2882    
2883         int pcre_info(const pcre *code, int *optptr, int *firstcharptr);           PCRE_INFO_REQUIREDCHARFLAGS
2884    
2885         The pcre_info() function is now obsolete because its interface  is  too         Returns  1 if there is a rightmost literal data unit that must exist in
2886         restrictive  to return all the available data about a compiled pattern.         any matched string, other than at its start. The fourth argument should
2887         New  programs  should  use  pcre_fullinfo()  instead.  The   yield   of         point  to an int variable. If there is no such value, 0 is returned. If
2888         pcre_info()  is the number of capturing subpatterns, or one of the fol-         returning  1,  the  character  value  itself  can  be  retrieved  using
2889         lowing negative numbers:         PCRE_INFO_REQUIREDCHAR.
2890    
2891           PCRE_ERROR_NULL       the argument code was NULL         For anchored patterns, a last literal value is recorded only if it fol-
2892           PCRE_ERROR_BADMAGIC   the "magic number" was not found         lows something  of  variable  length.  For  example,  for  the  pattern
2893           /^a\d+z\d+/   the   returned   value   1   (with   "z"   returned  from
2894         If the optptr argument is not NULL, a copy of the  options  with  which         PCRE_INFO_REQUIREDCHAR), but for /^a\dz\d/ the returned value is 0.
2895         the  pattern  was  compiled  is placed in the integer it points to (see  
2896         PCRE_INFO_OPTIONS above).           PCRE_INFO_REQUIREDCHAR
2897    
2898         If the pattern is not anchored and the  firstcharptr  argument  is  not         Return the value of the rightmost literal data unit that must exist  in
2899         NULL,  it is used to pass back information about the first character of         any  matched  string, other than at its start, if such a value has been
2900         any matched string (see PCRE_INFO_FIRSTBYTE above).         recorded. The fourth argument should point to an uint32_t variable.  If
2901           there is no such value, 0 is returned.
2902    
2903    
2904  REFERENCE COUNTS  REFERENCE COUNTS
2905    
2906         int pcre_refcount(pcre *code, int adjust);         int pcre_refcount(pcre *code, int adjust);
2907    
2908         The pcre_refcount() function is used to maintain a reference  count  in         The  pcre_refcount()  function is used to maintain a reference count in
2909         the data block that contains a compiled pattern. It is provided for the         the data block that contains a compiled pattern. It is provided for the
2910         benefit of applications that  operate  in  an  object-oriented  manner,         benefit  of  applications  that  operate  in an object-oriented manner,
2911         where different parts of the application may be using the same compiled         where different parts of the application may be using the same compiled
2912         pattern, but you want to free the block when they are all done.         pattern, but you want to free the block when they are all done.
2913    
2914         When a pattern is compiled, the reference count field is initialized to         When a pattern is compiled, the reference count field is initialized to
2915         zero.   It is changed only by calling this function, whose action is to         zero.  It is changed only by calling this function, whose action is  to
2916         add the adjust value (which may be positive or  negative)  to  it.  The         add  the  adjust  value  (which may be positive or negative) to it. The
2917         yield of the function is the new value. However, the value of the count         yield of the function is the new value. However, the value of the count
2918         is constrained to lie between 0 and 65535, inclusive. If the new  value         is  constrained to lie between 0 and 65535, inclusive. If the new value
2919         is outside these limits, it is forced to the appropriate limit value.         is outside these limits, it is forced to the appropriate limit value.
2920    
2921         Except  when it is zero, the reference count is not correctly preserved         Except when it is zero, the reference count is not correctly  preserved
2922         if a pattern is compiled on one host and then  transferred  to  a  host         if  a  pattern  is  compiled on one host and then transferred to a host
2923         whose byte-order is different. (This seems a highly unlikely scenario.)         whose byte-order is different. (This seems a highly unlikely scenario.)
2924    
2925    
# Line 1646  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2931  MATCHING A PATTERN: THE TRADITIONAL FUNC
2931    
2932         The function pcre_exec() is called to match a subject string against  a         The function pcre_exec() is called to match a subject string against  a
2933         compiled  pattern, which is passed in the code argument. If the pattern         compiled  pattern, which is passed in the code argument. If the pattern
2934         has been studied, the result of the study should be passed in the extra         was studied, the result of the study should  be  passed  in  the  extra
2935         argument.  This  function is the main matching facility of the library,         argument.  You  can call pcre_exec() with the same code and extra argu-
2936         and it operates in a Perl-like manner. For specialist use there is also         ments as many times as you like, in order to  match  different  subject
2937         an  alternative matching function, which is described below in the sec-         strings with the same pattern.
2938         tion about the pcre_dfa_exec() function.  
2939           This  function  is  the  main  matching facility of the library, and it
2940           operates in a Perl-like manner. For specialist use  there  is  also  an
2941           alternative  matching function, which is described below in the section
2942           about the pcre_dfa_exec() function.
2943    
2944         In most applications, the pattern will have been compiled (and  option-         In most applications, the pattern will have been compiled (and  option-
2945         ally  studied)  in the same process that calls pcre_exec(). However, it         ally  studied)  in the same process that calls pcre_exec(). However, it
# Line 1682  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2971  MATCHING A PATTERN: THE TRADITIONAL FUNC
2971    
2972           unsigned long int flags;           unsigned long int flags;
2973           void *study_data;           void *study_data;
2974             void *executable_jit;
2975           unsigned long int match_limit;           unsigned long int match_limit;
2976           unsigned long int match_limit_recursion;           unsigned long int match_limit_recursion;
2977           void *callout_data;           void *callout_data;
2978           const unsigned char *tables;           const unsigned char *tables;
2979             unsigned char **mark;
2980    
2981         The flags field is a bitmap that specifies which of  the  other  fields         In the 16-bit version of  this  structure,  the  mark  field  has  type
2982         are set. The flag bits are:         "PCRE_UCHAR16 **".
2983    
2984           PCRE_EXTRA_STUDY_DATA         In  the  32-bit  version  of  this  structure,  the mark field has type
2985           "PCRE_UCHAR32 **".
2986    
2987           The flags field is used to specify which of the other fields  are  set.
2988           The flag bits are:
2989    
2990             PCRE_EXTRA_CALLOUT_DATA
2991             PCRE_EXTRA_EXECUTABLE_JIT
2992             PCRE_EXTRA_MARK
2993           PCRE_EXTRA_MATCH_LIMIT           PCRE_EXTRA_MATCH_LIMIT
2994           PCRE_EXTRA_MATCH_LIMIT_RECURSION           PCRE_EXTRA_MATCH_LIMIT_RECURSION
2995           PCRE_EXTRA_CALLOUT_DATA           PCRE_EXTRA_STUDY_DATA
2996           PCRE_EXTRA_TABLES           PCRE_EXTRA_TABLES
2997    
2998         Other  flag  bits should be set to zero. The study_data field is set in         Other  flag  bits should be set to zero. The study_data field and some-
2999         the pcre_extra block that is returned by  pcre_study(),  together  with         times the executable_jit field are set in the pcre_extra block that  is
3000         the appropriate flag bit. You should not set this yourself, but you may         returned  by pcre_study(), together with the appropriate flag bits. You
3001         add to the block by setting the other fields  and  their  corresponding         should not set these yourself, but you may add to the block by  setting
3002         flag bits.         other fields and their corresponding flag bits.
3003    
3004         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
3005         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
3006         match,  but  which  have  a very large number of possibilities in their         match,  but  which  have  a very large number of possibilities in their
3007         search trees. The classic  example  is  the  use  of  nested  unlimited         search trees. The classic example is a pattern that uses nested  unlim-
3008         repeats.         ited repeats.
3009    
3010         Internally,  PCRE uses a function called match() which it calls repeat-         Internally,  pcre_exec() uses a function called match(), which it calls
3011         edly (sometimes recursively). The limit set by match_limit  is  imposed         repeatedly (sometimes recursively). The limit  set  by  match_limit  is
3012         on  the  number  of times this function is called during a match, which         imposed  on the number of times this function is called during a match,
3013         has the effect of limiting the amount of  backtracking  that  can  take         which has the effect of limiting the amount of  backtracking  that  can
3014         place. For patterns that are not anchored, the count restarts from zero         take place. For patterns that are not anchored, the count restarts from
3015         for each position in the subject string.         zero for each position in the subject string.
3016    
3017         The default value for the limit can be set  when  PCRE  is  built;  the         When pcre_exec() is called with a pattern that was successfully studied
3018         default  default  is 10 million, which handles all but the most extreme         with  a  JIT  option, the way that the matching is executed is entirely
3019         cases. You can override the default  by  suppling  pcre_exec()  with  a         different.  However, there is still the possibility of runaway matching
3020         pcre_extra     block    in    which    match_limit    is    set,    and         that goes on for a very long time, and so the match_limit value is also
3021         PCRE_EXTRA_MATCH_LIMIT is set in the  flags  field.  If  the  limit  is         used in this case (but in a different way) to limit how long the match-
3022           ing can continue.
3023    
3024           The  default  value  for  the  limit can be set when PCRE is built; the
3025           default default is 10 million, which handles all but the  most  extreme
3026           cases.  You  can  override  the  default by suppling pcre_exec() with a
3027           pcre_extra    block    in    which    match_limit    is    set,     and
3028           PCRE_EXTRA_MATCH_LIMIT  is  set  in  the  flags  field. If the limit is
3029         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
3030    
3031         The  match_limit_recursion field is similar to match_limit, but instead         The match_limit_recursion field is similar to match_limit, but  instead
3032         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
3033         the  depth  of  recursion. The recursion depth is a smaller number than         the depth of recursion. The recursion depth is a  smaller  number  than
3034         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-
3035         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.
3036    
3037         Limiting the recursion depth limits the amount of  stack  that  can  be         Limiting the recursion depth limits the amount of  machine  stack  that
3038         used, or, when PCRE has been compiled to use memory on the heap instead         can  be used, or, when PCRE has been compiled to use memory on the heap
3039         of the stack, the amount of heap memory that can be used.         instead of the stack, the amount of heap memory that can be used.  This
3040           limit  is not relevant, and is ignored, when matching is done using JIT
3041           compiled code.
3042    
3043         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
3044         built;  the  default  default  is  the  same  value  as the default for         built;  the  default  default  is  the  same  value  as the default for
# Line 1739  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3047  MATCHING A PATTERN: THE TRADITIONAL FUNC
3047         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
3048         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.
3049    
3050         The  pcre_callout  field is used in conjunction with the "callout" fea-         The  callout_data  field is used in conjunction with the "callout" fea-
3051         ture, which is described in the pcrecallout documentation.         ture, and is described in the pcrecallout documentation.
3052    
3053         The tables field  is  used  to  pass  a  character  tables  pointer  to         The tables field  is  used  to  pass  a  character  tables  pointer  to
3054         pcre_exec();  this overrides the value that is stored with the compiled         pcre_exec();  this overrides the value that is stored with the compiled
# Line 1753  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3061  MATCHING A PATTERN: THE TRADITIONAL FUNC
3061         address when pcre_exec() is called. See the  pcreprecompile  documenta-         address when pcre_exec() is called. See the  pcreprecompile  documenta-
3062         tion for a discussion of saving compiled patterns for later use.         tion for a discussion of saving compiled patterns for later use.
3063    
3064           If  PCRE_EXTRA_MARK  is  set in the flags field, the mark field must be
3065           set to point to a suitable variable. If the pattern contains any  back-
3066           tracking  control verbs such as (*MARK:NAME), and the execution ends up
3067           with a name to pass back, a pointer to the  name  string  (zero  termi-
3068           nated)  is  placed  in  the  variable pointed to by the mark field. The
3069           names are within the compiled pattern; if you wish  to  retain  such  a
3070           name  you must copy it before freeing the memory of a compiled pattern.
3071           If there is no name to pass back, the variable pointed to by  the  mark
3072           field  is  set  to NULL. For details of the backtracking control verbs,
3073           see the section entitled "Backtracking control" in the pcrepattern doc-
3074           umentation.
3075    
3076     Option bits for pcre_exec()     Option bits for pcre_exec()
3077    
3078         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.
3079         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,
3080         PCRE_NOTBOL,   PCRE_NOTEOL,   PCRE_NOTEMPTY,   PCRE_NO_UTF8_CHECK   and         PCRE_NOTBOL,    PCRE_NOTEOL,    PCRE_NOTEMPTY,   PCRE_NOTEMPTY_ATSTART,
3081         PCRE_PARTIAL.         PCRE_NO_START_OPTIMIZE,  PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_HARD,   and
3082           PCRE_PARTIAL_SOFT.
3083    
3084           If  the  pattern  was successfully studied with one of the just-in-time
3085           (JIT) compile options, the only supported options for JIT execution are
3086           PCRE_NO_UTF8_CHECK,     PCRE_NOTBOL,     PCRE_NOTEOL,    PCRE_NOTEMPTY,
3087           PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If  an
3088           unsupported  option  is  used, JIT execution is disabled and the normal
3089           interpretive code in pcre_exec() is run.
3090    
3091           PCRE_ANCHORED           PCRE_ANCHORED
3092    
# Line 1767  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3095  MATCHING A PATTERN: THE TRADITIONAL FUNC
3095         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
3096         unachored at matching time.         unachored at matching time.
3097    
3098             PCRE_BSR_ANYCRLF
3099             PCRE_BSR_UNICODE
3100    
3101           These options (which are mutually exclusive) control what the \R escape
3102           sequence matches. The choice is either to match only CR, LF,  or  CRLF,
3103           or  to  match  any Unicode newline sequence. These options override the
3104           choice that was made or defaulted when the pattern was compiled.
3105    
3106           PCRE_NEWLINE_CR           PCRE_NEWLINE_CR
3107           PCRE_NEWLINE_LF           PCRE_NEWLINE_LF
3108           PCRE_NEWLINE_CRLF           PCRE_NEWLINE_CRLF
3109           PCRE_NEWLINE_ANYCRLF           PCRE_NEWLINE_ANYCRLF
3110           PCRE_NEWLINE_ANY           PCRE_NEWLINE_ANY
3111    
3112         These  options  override  the  newline  definition  that  was chosen or         These options override  the  newline  definition  that  was  chosen  or
3113         defaulted when the pattern was compiled. For details, see the  descrip-         defaulted  when the pattern was compiled. For details, see the descrip-
3114         tion  of  pcre_compile()  above.  During  matching,  the newline choice         tion of pcre_compile()  above.  During  matching,  the  newline  choice
3115         affects the behaviour of the dot, circumflex,  and  dollar  metacharac-         affects  the  behaviour  of the dot, circumflex, and dollar metacharac-
3116         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
3117         match  failure  for  an  unanchored  pattern.  When  PCRE_NEWLINE_CRLF,         match failure for an unanchored pattern.
3118         PCRE_NEWLINE_ANYCRLF,  or  PCRE_NEWLINE_ANY is set, and a match attempt  
3119         fails when the current position is at a CRLF sequence, the match  posi-         When  PCRE_NEWLINE_CRLF,  PCRE_NEWLINE_ANYCRLF,  or PCRE_NEWLINE_ANY is
3120         tion  is  advanced by two characters instead of one, in other words, to         set, and a match attempt for an unanchored pattern fails when the  cur-
3121         after the CRLF.         rent  position  is  at  a  CRLF  sequence,  and the pattern contains no
3122           explicit matches for  CR  or  LF  characters,  the  match  position  is
3123           advanced by two characters instead of one, in other words, to after the
3124           CRLF.
3125    
3126           The above rule is a compromise that makes the most common cases work as
3127           expected.  For  example,  if  the  pattern  is .+A (and the PCRE_DOTALL
3128           option is not set), it does not match the string "\r\nA" because, after
3129           failing  at the start, it skips both the CR and the LF before retrying.
3130           However, the pattern [\r\n]A does match that string,  because  it  con-
3131           tains an explicit CR or LF reference, and so advances only by one char-
3132           acter after the first failure.
3133    
3134           An explicit match for CR of LF is either a literal appearance of one of
3135           those  characters,  or  one  of the \r or \n escape sequences. Implicit
3136           matches such as [^X] do not count, nor does \s (which includes  CR  and
3137           LF in the characters that it matches).
3138    
3139           Notwithstanding  the above, anomalous effects may still occur when CRLF
3140           is a valid newline sequence and explicit \r or \n escapes appear in the
3141           pattern.
3142    
3143           PCRE_NOTBOL           PCRE_NOTBOL
3144    
3145         This option specifies that first character of the subject string is not         This option specifies that first character of the subject string is not
3146         the  beginning  of  a  line, so the circumflex metacharacter should not         the beginning of a line, so the  circumflex  metacharacter  should  not
3147         match before it. Setting this without PCRE_MULTILINE (at compile  time)         match  before it. Setting this without PCRE_MULTILINE (at compile time)
3148         causes  circumflex  never to match. This option affects only the behav-         causes circumflex never to match. This option affects only  the  behav-
3149         iour of the circumflex metacharacter. It does not affect \A.         iour of the circumflex metacharacter. It does not affect \A.
3150    
3151           PCRE_NOTEOL           PCRE_NOTEOL
3152    
3153         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
3154         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
3155         in multiline mode) a newline immediately before it. Setting this  with-         in  multiline mode) a newline immediately before it. Setting this with-
3156         out PCRE_MULTILINE (at compile time) causes dollar never to match. This         out PCRE_MULTILINE (at compile time) causes dollar never to match. This
3157         option affects only the behaviour of the dollar metacharacter. It  does         option  affects only the behaviour of the dollar metacharacter. It does
3158         not affect \Z or \z.         not affect \Z or \z.
3159    
3160           PCRE_NOTEMPTY           PCRE_NOTEMPTY
3161    
3162         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
3163         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
3164         the  alternatives  match  the empty string, the entire match fails. For         the alternatives match the empty string, the entire  match  fails.  For
3165         example, if the pattern         example, if the pattern
3166    
3167           a?b?           a?b?
3168    
3169         is applied to a string not beginning with "a" or "b",  it  matches  the         is  applied  to  a  string not beginning with "a" or "b", it matches an
3170         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
3171         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-
3172         rences of "a" or "b".         rences of "a" or "b".
3173    
3174         Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a spe-           PCRE_NOTEMPTY_ATSTART
3175         cial case of a pattern match of the empty  string  within  its  split()  
3176         function,  and  when  using  the /g modifier. It is possible to emulate         This is like PCRE_NOTEMPTY, except that an empty string match  that  is
3177         Perl's behaviour after matching a null string by first trying the match         not  at  the  start  of  the  subject  is  permitted. If the pattern is
3178         again at the same offset with PCRE_NOTEMPTY and PCRE_ANCHORED, and then         anchored, such a match can occur only if the pattern contains \K.
3179         if that fails by advancing the starting offset (see below)  and  trying  
3180         an ordinary match again. There is some code that demonstrates how to do         Perl    has    no    direct    equivalent    of    PCRE_NOTEMPTY     or
3181         this in the pcredemo.c sample program.         PCRE_NOTEMPTY_ATSTART,  but  it  does  make a special case of a pattern
3182           match of the empty string within its split() function, and  when  using
3183           the  /g  modifier.  It  is  possible  to emulate Perl's behaviour after
3184           matching a null string by first trying the match again at the same off-
3185           set  with  PCRE_NOTEMPTY_ATSTART  and  PCRE_ANCHORED,  and then if that
3186           fails, by advancing the starting offset (see below) and trying an ordi-
3187           nary  match  again. There is some code that demonstrates how to do this
3188           in the pcredemo sample program. In the most general case, you  have  to
3189           check  to  see  if the newline convention recognizes CRLF as a newline,
3190           and if so, and the current character is CR followed by LF, advance  the
3191           starting offset by two characters instead of one.
3192    
3193             PCRE_NO_START_OPTIMIZE
3194    
3195           There  are a number of optimizations that pcre_exec() uses at the start
3196           of a match, in order to speed up the process. For  example,  if  it  is
3197           known that an unanchored match must start with a specific character, it
3198           searches the subject for that character, and fails  immediately  if  it
3199           cannot  find  it,  without actually running the main matching function.
3200           This means that a special item such as (*COMMIT) at the start of a pat-
3201           tern  is  not  considered until after a suitable starting point for the
3202           match has been found. When callouts or (*MARK) items are in use,  these
3203           "start-up" optimizations can cause them to be skipped if the pattern is
3204           never actually used. The start-up optimizations are in  effect  a  pre-
3205           scan of the subject that takes place before the pattern is run.
3206    
3207           The  PCRE_NO_START_OPTIMIZE option disables the start-up optimizations,
3208           possibly causing performance to suffer,  but  ensuring  that  in  cases
3209           where  the  result is "no match", the callouts do occur, and that items
3210           such as (*COMMIT) and (*MARK) are considered at every possible starting
3211           position  in  the  subject  string. If PCRE_NO_START_OPTIMIZE is set at
3212           compile time,  it  cannot  be  unset  at  matching  time.  The  use  of
3213           PCRE_NO_START_OPTIMIZE disables JIT execution; when it is set, matching
3214           is always done using interpretively.
3215    
3216           Setting PCRE_NO_START_OPTIMIZE can change the  outcome  of  a  matching
3217           operation.  Consider the pattern
3218    
3219             (*COMMIT)ABC
3220    
3221           When  this  is  compiled, PCRE records the fact that a match must start
3222           with the character "A". Suppose the subject  string  is  "DEFABC".  The
3223           start-up  optimization  scans along the subject, finds "A" and runs the
3224           first match attempt from there. The (*COMMIT) item means that the  pat-
3225           tern  must  match the current starting position, which in this case, it
3226           does. However, if the same match  is  run  with  PCRE_NO_START_OPTIMIZE
3227           set,  the  initial  scan  along the subject string does not happen. The
3228           first match attempt is run starting  from  "D"  and  when  this  fails,
3229           (*COMMIT)  prevents  any  further  matches  being tried, so the overall
3230           result is "no match". If the pattern is studied,  more  start-up  opti-
3231           mizations  may  be  used. For example, a minimum length for the subject
3232           may be recorded. Consider the pattern
3233    
3234             (*MARK:A)(X|Y)
3235    
3236           The minimum length for a match is one  character.  If  the  subject  is
3237           "ABC",  there  will  be  attempts  to  match "ABC", "BC", "C", and then
3238           finally an empty string.  If the pattern is studied, the final  attempt
3239           does  not take place, because PCRE knows that the subject is too short,
3240           and so the (*MARK) is never encountered.  In this  case,  studying  the
3241           pattern  does  not  affect the overall match result, which is still "no
3242           match", but it does affect the auxiliary information that is returned.
3243    
3244           PCRE_NO_UTF8_CHECK           PCRE_NO_UTF8_CHECK
3245    
3246         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
3247         UTF-8  string is automatically checked when pcre_exec() is subsequently         UTF-8  string is automatically checked when pcre_exec() is subsequently
3248         called.  The value of startoffset is also checked  to  ensure  that  it         called.  The entire string is checked before any other processing takes
3249         points  to the start of a UTF-8 character. If an invalid UTF-8 sequence         place.  The  value  of  startoffset  is  also checked to ensure that it
3250         of bytes is found, pcre_exec() returns the error PCRE_ERROR_BADUTF8. If         points to the start of a UTF-8 character. There is a  discussion  about
3251         startoffset  contains  an  invalid  value, PCRE_ERROR_BADUTF8_OFFSET is         the  validity  of  UTF-8 strings in the pcreunicode page. If an invalid
3252         returned.         sequence  of  bytes   is   found,   pcre_exec()   returns   the   error
3253           PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a
3254         If you already know that your subject is valid, and you  want  to  skip         truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
3255         these    checks    for   performance   reasons,   you   can   set   the         both  cases, information about the precise nature of the error may also
3256         PCRE_NO_UTF8_CHECK option when calling pcre_exec(). You might  want  to         be returned (see the descriptions of these errors in the section  enti-
3257         do  this  for the second and subsequent calls to pcre_exec() if you are         tled  Error return values from pcre_exec() below).  If startoffset con-
3258         making repeated calls to find all  the  matches  in  a  single  subject         tains a value that does not point to the start of a UTF-8 character (or
3259         string.  However,  you  should  be  sure  that the value of startoffset         to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is returned.
3260         points to the start of a UTF-8 character.  When  PCRE_NO_UTF8_CHECK  is  
3261         set,  the  effect of passing an invalid UTF-8 string as a subject, or a         If  you  already  know that your subject is valid, and you want to skip
3262         value of startoffset that does not point to the start of a UTF-8  char-         these   checks   for   performance   reasons,   you   can    set    the
3263         acter, is undefined. Your program may crash.         PCRE_NO_UTF8_CHECK  option  when calling pcre_exec(). You might want to
3264           do this for the second and subsequent calls to pcre_exec() if  you  are
3265           PCRE_PARTIAL         making  repeated  calls  to  find  all  the matches in a single subject
3266           string. However, you should be  sure  that  the  value  of  startoffset
3267         This  option  turns  on  the  partial  matching feature. If the subject         points  to  the  start of a character (or the end of the subject). When
3268         string fails to match the pattern, but at some point during the  match-         PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid string as a
3269         ing  process  the  end of the subject was reached (that is, the subject         subject  or  an invalid value of startoffset is undefined. Your program
3270         partially matches the pattern and the failure to  match  occurred  only         may crash.
3271         because  there were not enough subject characters), pcre_exec() returns  
3272         PCRE_ERROR_PARTIAL instead of PCRE_ERROR_NOMATCH. When PCRE_PARTIAL  is           PCRE_PARTIAL_HARD
3273         used,  there  are restrictions on what may appear in the pattern. These           PCRE_PARTIAL_SOFT
3274         are discussed in the pcrepartial documentation.  
3275           These options turn on the partial matching feature. For backwards  com-
3276           patibility,  PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial
3277           match occurs if the end of the subject string is reached  successfully,
3278           but  there  are not enough subject characters to complete the match. If
3279           this happens when PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set,
3280           matching  continues  by  testing any remaining alternatives. Only if no
3281           complete match can be found is PCRE_ERROR_PARTIAL returned  instead  of
3282           PCRE_ERROR_NOMATCH.  In  other  words,  PCRE_PARTIAL_SOFT says that the
3283           caller is prepared to handle a partial match, but only if  no  complete
3284           match can be found.
3285    
3286           If  PCRE_PARTIAL_HARD  is  set, it overrides PCRE_PARTIAL_SOFT. In this
3287           case, if a partial match  is  found,  pcre_exec()  immediately  returns
3288           PCRE_ERROR_PARTIAL,  without  considering  any  other  alternatives. In
3289           other words, when PCRE_PARTIAL_HARD is set, a partial match is  consid-
3290           ered to be more important that an alternative complete match.
3291    
3292           In  both  cases,  the portion of the string that was inspected when the
3293           partial match was found is set as the first matching string. There is a
3294           more  detailed  discussion  of partial and multi-segment matching, with
3295           examples, in the pcrepartial documentation.
3296    
3297     The string to be matched by pcre_exec()     The string to be matched by pcre_exec()
3298    
3299         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
3300         length  in  length, and a starting byte offset in startoffset. In UTF-8         length  in  bytes in length, and a starting byte offset in startoffset.
3301         mode, the byte offset must point to the start  of  a  UTF-8  character.         If this is  negative  or  greater  than  the  length  of  the  subject,
3302         Unlike  the  pattern string, the subject may contain binary zero bytes.         pcre_exec()  returns  PCRE_ERROR_BADOFFSET. When the starting offset is
3303         When the starting offset is zero, the search for a match starts at  the         zero, the search for a match starts at the beginning  of  the  subject,
3304         beginning of the subject, and this is by far the most common case.         and this is by far the most common case. In UTF-8 mode, the byte offset
3305           must point to the start of a UTF-8 character (or the end  of  the  sub-
3306         A  non-zero  starting offset is useful when searching for another match         ject).  Unlike  the pattern string, the subject may contain binary zero
3307         in the same subject by calling pcre_exec() again after a previous  suc-         bytes.
3308         cess.   Setting  startoffset differs from just passing over a shortened  
3309         string and setting PCRE_NOTBOL in the case of  a  pattern  that  begins         A non-zero starting offset is useful when searching for  another  match
3310           in  the same subject by calling pcre_exec() again after a previous suc-
3311           cess.  Setting startoffset differs from just passing over  a  shortened
3312           string  and  setting  PCRE_NOTBOL  in the case of a pattern that begins
3313         with any kind of lookbehind. For example, consider the pattern         with any kind of lookbehind. For example, consider the pattern
3314    
3315           \Biss\B           \Biss\B
3316    
3317         which  finds  occurrences  of "iss" in the middle of words. (\B matches         which finds occurrences of "iss" in the middle of  words.  (\B  matches
3318         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.)
3319         When  applied  to the string "Mississipi" the first call to pcre_exec()         When applied to the string "Mississipi" the first call  to  pcre_exec()
3320         finds the first occurrence. If pcre_exec() is called  again  with  just         finds  the  first  occurrence. If pcre_exec() is called again with just
3321         the  remainder  of  the  subject,  namely  "issipi", it does not match,         the remainder of the subject,  namely  "issipi",  it  does  not  match,
3322         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
3323         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
3324         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-
3325         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
3326         discover that it is preceded by a letter.         discover that it is preceded by a letter.
3327    
3328           Finding  all  the  matches  in a subject is tricky when the pattern can
3329           match an empty string. It is possible to emulate Perl's /g behaviour by
3330           first   trying   the   match   again  at  the  same  offset,  with  the
3331           PCRE_NOTEMPTY_ATSTART and  PCRE_ANCHORED  options,  and  then  if  that
3332           fails,  advancing  the  starting  offset  and  trying an ordinary match
3333           again. There is some code that demonstrates how to do this in the pcre-
3334           demo sample program. In the most general case, you have to check to see
3335           if the newline convention recognizes CRLF as a newline, and if so,  and
3336           the current character is CR followed by LF, advance the starting offset
3337           by two characters instead of one.
3338    
3339         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,
3340         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
3341         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
# Line 1899  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3351  MATCHING A PATTERN: THE TRADITIONAL FUNC
3351         string. PCRE supports several other kinds of  parenthesized  subpattern         string. PCRE supports several other kinds of  parenthesized  subpattern
3352         that do not cause substrings to be captured.         that do not cause substrings to be captured.
3353    
3354         Captured  substrings are returned to the caller via a vector of integer         Captured substrings are returned to the caller via a vector of integers
3355         offsets whose address is passed in ovector. The number of  elements  in         whose address is passed in ovector. The number of elements in the  vec-
3356         the  vector is passed in ovecsize, which must be a non-negative number.         tor  is  passed in ovecsize, which must be a non-negative number. Note:
3357         Note: this argument is NOT the size of ovector in bytes.         this argument is NOT the size of ovector in bytes.
3358    
3359         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-
3360         strings,  each  substring using a pair of integers. The remaining third         strings,  each  substring using a pair of integers. The remaining third
3361         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-
3362         turing  subpatterns, and is not available for passing back information.         turing  subpatterns, and is not available for passing back information.
3363         The length passed in ovecsize should always be a multiple of three.  If         The number passed in ovecsize should always be a multiple of three.  If
3364         it is not, it is rounded down.         it is not, it is rounded down.
3365    
3366         When  a  match  is successful, information about captured substrings is         When  a  match  is successful, information about captured substrings is
3367         returned in pairs of integers, starting at the  beginning  of  ovector,         returned in pairs of integers, starting at the  beginning  of  ovector,
3368         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
3369         element of a pair is set to the offset of the first character in a sub-         element of each pair is set to the byte offset of the  first  character
3370         string,  and  the  second  is  set to the offset of the first character         in  a  substring, and the second is set to the byte offset of the first
3371         after the end of a substring. The  first  pair,  ovector[0]  and  ovec-         character after the end of a substring. Note: these values  are  always
3372         tor[1],  identify  the  portion  of  the  subject string matched by the         byte offsets, even in UTF-8 mode. They are not character counts.
3373         entire pattern. The next pair is used for the first  capturing  subpat-  
3374         tern, and so on. The value returned by pcre_exec() is one more than the         The  first  pair  of  integers, ovector[0] and ovector[1], identify the
3375         highest numbered pair that has been set. For example, if two substrings         portion of the subject string matched by the entire pattern.  The  next
3376         have  been captured, the returned value is 3. If there are no capturing         pair  is  used for the first capturing subpattern, and so on. The value
3377         subpatterns, the return value from a successful match is 1,  indicating         returned by pcre_exec() is one more than the highest numbered pair that
3378         that just the first pair of offsets has been set.         has  been  set.  For example, if two substrings have been captured, the
3379           returned value is 3. If there are no capturing subpatterns, the  return
3380           value from a successful match is 1, indicating that just the first pair
3381           of offsets has been set.
3382    
3383         If a capturing subpattern is matched repeatedly, it is the last portion         If a capturing subpattern is matched repeatedly, it is the last portion
3384         of the string that it matched that is returned.         of the string that it matched that is returned.
3385    
3386         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,
3387         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
3388         function returns a value of zero. In particular, if the substring  off-         function  returns a value of zero. If neither the actual string matched
3389         sets are not of interest, pcre_exec() may be called with ovector passed         nor any captured substrings are of interest, pcre_exec() may be  called
3390         as NULL and ovecsize as zero. However, if  the  pattern  contains  back         with  ovector passed as NULL and ovecsize as zero. However, if the pat-
3391         references  and  the  ovector is not big enough to remember the related         tern contains back references and the ovector  is  not  big  enough  to
3392         substrings, PCRE has to get additional memory for use during  matching.         remember  the related substrings, PCRE has to get additional memory for
3393         Thus it is usually advisable to supply an ovector.         use during matching. Thus it is usually advisable to supply an  ovector
3394           of reasonable size.
3395         The  pcre_info()  function  can  be used to find out how many capturing  
3396         subpatterns there are in a compiled  pattern.  The  smallest  size  for         There  are  some  cases where zero is returned (indicating vector over-
3397         ovector  that  will allow for n captured substrings, in addition to the         flow) when in fact the vector is exactly the right size for  the  final
3398           match. For example, consider the pattern
3399    
3400             (a)(?:(b)c|bd)
3401    
3402           If  a  vector of 6 elements (allowing for only 1 captured substring) is
3403           given with subject string "abd", pcre_exec() will try to set the second
3404           captured string, thereby recording a vector overflow, before failing to