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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    
11  PCRE(3)                                                                PCRE(3)  PCRE(3)                    Library Functions Manual                    PCRE(3)
12    
13    
14    
15  NAME  NAME
16         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
17    
   
18  INTRODUCTION  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.  The current implementation of PCRE (release         just  a few differences. Some features that appeared in Python and PCRE
23         6.x) corresponds approximately with Perl  5.8,  including  support  for         before they appeared in Perl are also available using the  Python  syn-
24         UTF-8 encoded strings and Unicode general category properties. However,         tax,  there  is  some  support for one or two .NET and Oniguruma syntax
25         this support has to be explicitly enabled; it is not the default.         items, and there is an option for requesting some  minor  changes  that
26           give better JavaScript compatibility.
27         In addition to the Perl-compatible matching function,  PCRE  also  con-  
28         tains  an  alternative matching function that matches the same compiled         Starting with release 8.30, it is possible to compile two separate PCRE
29         patterns in a different way. In certain circumstances, the  alternative         libraries:  the  original,  which  supports  8-bit  character   strings
30         function  has  some  advantages.  For  a discussion of the two matching         (including  UTF-8  strings),  and a second library that supports 16-bit
31         algorithms, see the pcrematching page.         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
55           correspond to Unicode release 6.2.0.
56    
57           In addition to the Perl-compatible matching function, PCRE contains  an
58           alternative  function that matches the same compiled patterns in a dif-
59           ferent way. In certain circumstances, the alternative function has some
60           advantages.   For  a discussion of the two matching algorithms, see the
61           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    
73         Details  of  exactly which Perl regular expression features are and are         Details of exactly which Perl regular expression features are  and  are
74         not supported by PCRE are given in separate documents. See the pcrepat-         not supported by PCRE are given in separate documents. See the pcrepat-
75         tern and pcrecompat pages.         tern and pcrecompat pages. There is a syntax summary in the  pcresyntax
76           page.
77    
78         Some  features  of  PCRE can be included, excluded, or changed when the         Some  features  of  PCRE can be included, excluded, or changed when the
79         library is built. The pcre_config() function makes it  possible  for  a         library is built. The pcre_config() function makes it  possible  for  a
80         client  to  discover  which  features are available. The features them-         client  to  discover  which  features are available. The features them-
81         selves are described in the pcrebuild page. Documentation about  build-         selves are described in the pcrebuild page. Documentation about  build-
82         ing  PCRE for various operating systems can be found in the README 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           One   way   of   guarding  against  this  possibility  is  to  use  the
110           pcre_fullinfo() function to check the compiled  pattern's  options  for
111           UTF.   Alternatively, from release 8.33, you can set the PCRE_NEVER_UTF
112           option at compile time. This causes an compile time error if a  pattern
113           contains a UTF-setting sequence.
114    
115           If  your  application  is one that supports UTF, be aware that validity
116           checking can take time. If the same data string is to be  matched  many
117           times, you can use the PCRE_NO_UTF[8|16|32]_CHECK option for the second
118           and subsequent matches to save redundant checks.
119    
120           Another way that performance can be hit is by running  a  pattern  that
121           has  a  very  large search tree against a string that will never match.
122           Nested unlimited repeats in a pattern are a common example.  PCRE  pro-
123           vides some protection against this: see the PCRE_EXTRA_MATCH_LIMIT fea-
124           ture in the pcreapi page.
125    
126    
127  USER DOCUMENTATION  USER DOCUMENTATION
# Line 63  USER DOCUMENTATION Line 129  USER DOCUMENTATION
129         The user documentation for PCRE comprises a number  of  different  sec-         The user documentation for PCRE comprises a number  of  different  sec-
130         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
131         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.
132         In  the  plain text format, all the sections are concatenated, for ease         In  the  plain  text format, all the sections, except the pcredemo sec-
133         of searching. The sections are as follows:         tion, are concatenated, for ease of searching. The sections are as fol-
134           lows:
135    
136           pcre              this document           pcre              this document
137             pcre16            details of the 16-bit library
138             pcre32            details of the 32-bit library
139             pcre-config       show PCRE installation configuration information
140           pcreapi           details of PCRE's native C API           pcreapi           details of PCRE's native C API
141           pcrebuild         options for building PCRE           pcrebuild         options for building PCRE
142           pcrecallout       details of the callout feature           pcrecallout       details of the callout feature
143           pcrecompat        discussion of Perl compatibility           pcrecompat        discussion of Perl compatibility
144           pcrecpp           details of the C++ wrapper           pcrecpp           details of the C++ wrapper for the 8-bit library
145           pcregrep          description of the pcregrep command           pcredemo          a demonstration C program that uses PCRE
146             pcregrep          description of the pcregrep command (8-bit only)
147             pcrejit           discussion of the just-in-time optimization support
148             pcrelimits        details of size and other limits
149           pcrematching      discussion of the two matching algorithms           pcrematching      discussion of the two matching algorithms
150           pcrepartial       details of the partial matching facility           pcrepartial       details of the partial matching facility
151           pcrepattern       syntax and semantics of supported           pcrepattern       syntax and semantics of supported
152                               regular expressions                               regular expressions
153           pcreperform       discussion of performance issues           pcreperform       discussion of performance issues
154           pcreposix         the POSIX-compatible C API           pcreposix         the POSIX-compatible C API for the 8-bit library
155           pcreprecompile    details of saving and re-using precompiled patterns           pcreprecompile    details of saving and re-using precompiled patterns
156           pcresample        discussion of the sample program           pcresample        discussion of the pcredemo program
157             pcrestack         discussion of stack usage
158             pcresyntax        quick syntax reference
159           pcretest          description of the pcretest testing command           pcretest          description of the pcretest testing command
160             pcreunicode       discussion of Unicode and UTF-8/16/32 support
161    
162         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
163         each C library function, listing its arguments and results.         each C library function, listing its arguments and results.
164    
165    
166  LIMITATIONS  AUTHOR
167    
168         There are some size limitations in PCRE but it is hoped that they  will         Philip Hazel
169         never in practice be relevant.         University Computing Service
170           Cambridge CB2 3QH, England.
171    
172         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,
173         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,
174         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 will be slower.  
   
        All values in repeating quantifiers must be less than 65536.  The maxi-  
        mum number of capturing subpatterns is 65535.  
   
        There is no limit to the number of non-capturing subpatterns,  but  the  
        maximum  depth  of  nesting  of  all kinds of parenthesized subpattern,  
        including capturing subpatterns, assertions, and other types of subpat-  
        tern, is 200.  
175    
        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.  
176    
177    REVISION
178    
179  UTF-8 AND UNICODE PROPERTY SUPPORT         Last updated: 26 April 2013
180           Copyright (c) 1997-2013 University of Cambridge.
181    ------------------------------------------------------------------------------
182    
183    
184    PCRE(3)                    Library Functions Manual                    PCRE(3)
185    
        From release 3.3, PCRE has  had  some  support  for  character  strings  
        encoded  in the UTF-8 format. For release 4.0 this was greatly extended  
        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 in several places, so should  
        not be very large.  
186    
        If PCRE is built with Unicode character property support (which implies  
        UTF-8  support),  the  escape sequences \p{..}, \P{..}, and \X are sup-  
        ported.  The available properties that can be tested are limited to the  
        general  category  properties such as Lu for an upper case letter or Nd  
        for a decimal number. A full list is given in the pcrepattern  documen-  
        tation. The PCRE library is increased in size by about 90K when Unicode  
        property support is included.  
   
        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. In a pattern, the escape sequence \x{...}, where the contents of the  
        braces  is  a  string  of hexadecimal digits, is interpreted as a UTF-8  
        character whose code number is the given hexadecimal number, for  exam-  
        ple:  \x{1234}.  If a non-hexadecimal digit appears between the braces,  
        the item is not recognized.  This escape sequence can be used either as  
        a literal, or within a character class.  
   
        3.  The  original hexadecimal escape sequence, \xhh, matches a two-byte  
        UTF-8 character if the value is greater than 127.  
   
        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}.  
187    
188         8.  Similarly,  characters that match the POSIX named character classes  NAME
189         are all low-valued characters.         PCRE - Perl-compatible regular expressions
190    
191           #include <pcre.h>
192    
193    
194    PCRE 16-BIT API BASIC FUNCTIONS
195    
196           pcre16 *pcre16_compile(PCRE_SPTR16 pattern, int options,
197                const char **errptr, int *erroffset,
198                const unsigned char *tableptr);
199    
200           pcre16 *pcre16_compile2(PCRE_SPTR16 pattern, int options,
201                int *errorcodeptr,
202                const char **errptr, int *erroffset,
203                const unsigned char *tableptr);
204    
205           pcre16_extra *pcre16_study(const pcre16 *code, int options,
206                const char **errptr);
207    
208           void pcre16_free_study(pcre16_extra *extra);
209    
210           int pcre16_exec(const pcre16 *code, const pcre16_extra *extra,
211                PCRE_SPTR16 subject, int length, int startoffset,
212                int options, int *ovector, int ovecsize);
213    
214           int pcre16_dfa_exec(const pcre16 *code, const pcre16_extra *extra,
215                PCRE_SPTR16 subject, int length, int startoffset,
216                int options, int *ovector, int ovecsize,
217                int *workspace, int wscount);
218    
219    
220    PCRE 16-BIT API STRING EXTRACTION FUNCTIONS
221    
222           int pcre16_copy_named_substring(const pcre16 *code,
223                PCRE_SPTR16 subject, int *ovector,
224                int stringcount, PCRE_SPTR16 stringname,
225                PCRE_UCHAR16 *buffer, int buffersize);
226    
227           int pcre16_copy_substring(PCRE_SPTR16 subject, int *ovector,
228                int stringcount, int stringnumber, PCRE_UCHAR16 *buffer,
229                int buffersize);
230    
231           int pcre16_get_named_substring(const pcre16 *code,
232                PCRE_SPTR16 subject, int *ovector,
233                int stringcount, PCRE_SPTR16 stringname,
234                PCRE_SPTR16 *stringptr);
235    
236           int pcre16_get_stringnumber(const pcre16 *code,
237                PCRE_SPTR16 name);
238    
239           int pcre16_get_stringtable_entries(const pcre16 *code,
240                PCRE_SPTR16 name, PCRE_UCHAR16 **first, PCRE_UCHAR16 **last);
241    
242           int pcre16_get_substring(PCRE_SPTR16 subject, int *ovector,
243                int stringcount, int stringnumber,
244                PCRE_SPTR16 *stringptr);
245    
246           int pcre16_get_substring_list(PCRE_SPTR16 subject,
247                int *ovector, int stringcount, PCRE_SPTR16 **listptr);
248    
249           void pcre16_free_substring(PCRE_SPTR16 stringptr);
250    
251           void pcre16_free_substring_list(PCRE_SPTR16 *stringptr);
252    
253    
254    PCRE 16-BIT API AUXILIARY FUNCTIONS
255    
256           pcre16_jit_stack *pcre16_jit_stack_alloc(int startsize, int maxsize);
257    
258           void pcre16_jit_stack_free(pcre16_jit_stack *stack);
259    
260           void pcre16_assign_jit_stack(pcre16_extra *extra,
261                pcre16_jit_callback callback, void *data);
262    
263           const unsigned char *pcre16_maketables(void);
264    
265           int pcre16_fullinfo(const pcre16 *code, const pcre16_extra *extra,
266                int what, void *where);
267    
268           int pcre16_refcount(pcre16 *code, int adjust);
269    
270           int pcre16_config(int what, void *where);
271    
272           const char *pcre16_version(void);
273    
274           int pcre16_pattern_to_host_byte_order(pcre16 *code,
275                pcre16_extra *extra, const unsigned char *tables);
276    
277    
278    PCRE 16-BIT API INDIRECTED FUNCTIONS
279    
280           void *(*pcre16_malloc)(size_t);
281    
282           void (*pcre16_free)(void *);
283    
284           void *(*pcre16_stack_malloc)(size_t);
285    
286           void (*pcre16_stack_free)(void *);
287    
288           int (*pcre16_callout)(pcre16_callout_block *);
289    
290    
291    PCRE 16-BIT API 16-BIT-ONLY FUNCTION
292    
293           int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *output,
294                PCRE_SPTR16 input, int length, int *byte_order,
295                int keep_boms);
296    
297    
298    THE PCRE 16-BIT LIBRARY
299    
300           Starting  with  release  8.30, it is possible to compile a PCRE library
301           that supports 16-bit character strings, including  UTF-16  strings,  as
302           well  as  or instead of the original 8-bit library. The majority of the
303           work to make  this  possible  was  done  by  Zoltan  Herczeg.  The  two
304           libraries contain identical sets of functions, used in exactly the same
305           way. Only the names of the functions and the data types of their  argu-
306           ments  and results are different. To avoid over-complication and reduce
307           the documentation maintenance load,  most  of  the  PCRE  documentation
308           describes  the  8-bit  library,  with only occasional references to the
309           16-bit library. This page describes what is different when you use  the
310           16-bit library.
311    
312           WARNING:  A  single  application can be linked with both libraries, but
313           you must take care when processing any particular pattern to use  func-
314           tions  from  just one library. For example, if you want to study a pat-
315           tern that was compiled with  pcre16_compile(),  you  must  do  so  with
316           pcre16_study(), not pcre_study(), and you must free the study data with
317           pcre16_free_study().
318    
319    
320    THE HEADER FILE
321    
322           There is only one header file, pcre.h. It contains prototypes  for  all
323           the functions in all libraries, as well as definitions of flags, struc-
324           tures, error codes, etc.
325    
326    
327    THE LIBRARY NAME
328    
329           In Unix-like systems, the 16-bit library is called libpcre16,  and  can
330           normally  be  accesss  by adding -lpcre16 to the command for linking an
331           application that uses PCRE.
332    
333    
334    STRING TYPES
335    
336           In the 8-bit library, strings are passed to PCRE library  functions  as
337           vectors  of  bytes  with  the  C  type "char *". In the 16-bit library,
338           strings are passed as vectors of unsigned 16-bit quantities. The  macro
339           PCRE_UCHAR16  specifies  an  appropriate  data type, and PCRE_SPTR16 is
340           defined as "const PCRE_UCHAR16 *". In very  many  environments,  "short
341           int" is a 16-bit data type. When PCRE is built, it defines PCRE_UCHAR16
342           as "unsigned short int", but checks that it really  is  a  16-bit  data
343           type.  If  it is not, the build fails with an error message telling the
344           maintainer to modify the definition appropriately.
345    
346    
347    STRUCTURE TYPES
348    
349           The types of the opaque structures that are used  for  compiled  16-bit
350           patterns  and  JIT stacks are pcre16 and pcre16_jit_stack respectively.
351           The  type  of  the  user-accessible  structure  that  is  returned   by
352           pcre16_study()  is  pcre16_extra, and the type of the structure that is
353           used for passing data to a callout  function  is  pcre16_callout_block.
354           These structures contain the same fields, with the same names, as their
355           8-bit counterparts. The only difference is that pointers  to  character
356           strings are 16-bit instead of 8-bit types.
357    
358    
359    16-BIT FUNCTIONS
360    
361           For  every function in the 8-bit library there is a corresponding func-
362           tion in the 16-bit library with a name that starts with pcre16_ instead
363           of  pcre_.  The  prototypes are listed above. In addition, there is one
364           extra function, pcre16_utf16_to_host_byte_order(). This  is  a  utility
365           function  that converts a UTF-16 character string to host byte order if
366           necessary. The other 16-bit  functions  expect  the  strings  they  are
367           passed to be in host byte order.
368    
369           The input and output arguments of pcre16_utf16_to_host_byte_order() may
370           point to the same address, that is, conversion in place  is  supported.
371           The output buffer must be at least as long as the input.
372    
373           The  length  argument  specifies the number of 16-bit data units in the
374           input string; a negative value specifies a zero-terminated string.
375    
376           If byte_order is NULL, it is assumed that the string starts off in host
377           byte  order. This may be changed by byte-order marks (BOMs) anywhere in
378           the string (commonly as the first character).
379    
380           If byte_order is not NULL, a non-zero value of the integer to which  it
381           points  means  that  the input starts off in host byte order, otherwise
382           the opposite order is assumed. Again, BOMs in  the  string  can  change
383           this. The final byte order is passed back at the end of processing.
384    
385           If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
386           copied into the output string. Otherwise they are discarded.
387    
388           The result of the function is the number of 16-bit  units  placed  into
389           the  output  buffer,  including  the  zero terminator if the string was
390           zero-terminated.
391    
392    
393    SUBJECT STRING OFFSETS
394    
395           The offsets within subject strings that are returned  by  the  matching
396           functions are in 16-bit units rather than bytes.
397    
398         9. Case-insensitive matching applies only to  characters  whose  values  
399         are  less than 128, unless PCRE is built with Unicode property support.  NAMED SUBPATTERNS
400         Even when Unicode property support is available, PCRE  still  uses  its  
401         own  character  tables when checking the case of low-valued characters,         The  name-to-number translation table that is maintained for named sub-
402         so as not to degrade performance.  The Unicode property information  is         patterns uses 16-bit characters.  The  pcre16_get_stringtable_entries()
403         used only for characters with higher values.         function returns the length of each entry in the table as the number of
404           16-bit data units.
405    
406    
407    OPTION NAMES
408    
409           There   are   two   new   general   option   names,   PCRE_UTF16    and
410           PCRE_NO_UTF16_CHECK,     which     correspond    to    PCRE_UTF8    and
411           PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
412           define  the  same bits in the options word. There is a discussion about
413           the validity of UTF-16 strings in the pcreunicode page.
414    
415           For the pcre16_config() function there is an  option  PCRE_CONFIG_UTF16
416           that  returns  1  if UTF-16 support is configured, otherwise 0. If this
417           option  is  given  to  pcre_config()  or  pcre32_config(),  or  if  the
418           PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF32  option is given to pcre16_con-
419           fig(), the result is the PCRE_ERROR_BADOPTION error.
420    
421    
422    CHARACTER CODES
423    
424           In 16-bit mode, when  PCRE_UTF16  is  not  set,  character  values  are
425           treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
426           that they can range from 0 to 0xffff instead of 0  to  0xff.  Character
427           types  for characters less than 0xff can therefore be influenced by the
428           locale in the same way as before.  Characters greater  than  0xff  have
429           only one case, and no "type" (such as letter or digit).
430    
431           In  UTF-16  mode,  the  character  code  is  Unicode, in the range 0 to
432           0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
433           because  those  are "surrogate" values that are used in pairs to encode
434           values greater than 0xffff.
435    
436           A UTF-16 string can indicate its endianness by special code knows as  a
437           byte-order mark (BOM). The PCRE functions do not handle this, expecting
438           strings  to  be  in  host  byte  order.  A  utility   function   called
439           pcre16_utf16_to_host_byte_order()  is  provided  to help with this (see
440           above).
441    
442    
443    ERROR NAMES
444    
445           The errors PCRE_ERROR_BADUTF16_OFFSET and PCRE_ERROR_SHORTUTF16  corre-
446           spond  to  their  8-bit  counterparts.  The error PCRE_ERROR_BADMODE is
447           given when a compiled pattern is passed to a  function  that  processes
448           patterns  in  the  other  mode, for example, if a pattern compiled with
449           pcre_compile() is passed to pcre16_exec().
450    
451           There are new error codes whose names  begin  with  PCRE_UTF16_ERR  for
452           invalid  UTF-16  strings,  corresponding to the PCRE_UTF8_ERR codes for
453           UTF-8 strings that are described in the section entitled "Reason  codes
454           for  invalid UTF-8 strings" in the main pcreapi page. The UTF-16 errors
455           are:
456    
457             PCRE_UTF16_ERR1  Missing low surrogate at end of string
458             PCRE_UTF16_ERR2  Invalid low surrogate follows high surrogate
459             PCRE_UTF16_ERR3  Isolated low surrogate
460             PCRE_UTF16_ERR4  Non-character
461    
462    
463    ERROR TEXTS
464    
465           If there is an error while compiling a pattern, the error text that  is
466           passed  back by pcre16_compile() or pcre16_compile2() is still an 8-bit
467           character string, zero-terminated.
468    
469    
470    CALLOUTS
471    
472           The subject and mark fields in the callout block that is  passed  to  a
473           callout function point to 16-bit vectors.
474    
475    
476    TESTING
477    
478           The  pcretest  program continues to operate with 8-bit input and output
479           files, but it can be used for testing the 16-bit library. If it is  run
480           with the command line option -16, patterns and subject strings are con-
481           verted from 8-bit to 16-bit before being passed to PCRE, and the 16-bit
482           library  functions  are used instead of the 8-bit ones. Returned 16-bit
483           strings are converted to 8-bit for output. If both the  8-bit  and  the
484           32-bit libraries were not compiled, pcretest defaults to 16-bit and the
485           -16 option is ignored.
486    
487           When PCRE is being built, the RunTest script that is  called  by  "make
488           check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
489           16-bit and 32-bit libraries has been built, and runs the  tests  appro-
490           priately.
491    
492    
493    NOT SUPPORTED IN 16-BIT MODE
494    
495           Not all the features of the 8-bit library are available with the 16-bit
496           library. The C++ and POSIX wrapper functions  support  only  the  8-bit
497           library, and the pcregrep program is at present 8-bit only.
498    
499    
500  AUTHOR  AUTHOR
501    
502         Philip Hazel         Philip Hazel
503         University Computing Service,         University Computing Service
504         Cambridge CB2 3QG, England.         Cambridge CB2 3QH, England.
505    
        Putting  an actual email address here seems to have been a spam magnet,  
        so I've taken it away. If you want to email me, use my initial and sur-  
        name, separated by a dot, at the domain ucs.cam.ac.uk.  
506    
507  Last updated: 07 March 2005  REVISION
 Copyright (c) 1997-2005 University of Cambridge.  
 ------------------------------------------------------------------------------  
508    
509           Last updated: 08 November 2012
510           Copyright (c) 1997-2012 University of Cambridge.
511    ------------------------------------------------------------------------------
512    
513    
514    PCRE(3)                    Library Functions Manual                    PCRE(3)
515    
 PCREBUILD(3)                                                      PCREBUILD(3)  
516    
517    
518  NAME  NAME
519         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
520    
521           #include <pcre.h>
522    
523    
524    PCRE 32-BIT API BASIC FUNCTIONS
525    
526           pcre32 *pcre32_compile(PCRE_SPTR32 pattern, int options,
527                const char **errptr, int *erroffset,
528                const unsigned char *tableptr);
529    
530           pcre32 *pcre32_compile2(PCRE_SPTR32 pattern, int options,
531                int *errorcodeptr,
532                const char **errptr, int *erroffset,
533                const unsigned char *tableptr);
534    
535           pcre32_extra *pcre32_study(const pcre32 *code, int options,
536                const char **errptr);
537    
538           void pcre32_free_study(pcre32_extra *extra);
539    
540           int pcre32_exec(const pcre32 *code, const pcre32_extra *extra,
541                PCRE_SPTR32 subject, int length, int startoffset,
542                int options, int *ovector, int ovecsize);
543    
544           int pcre32_dfa_exec(const pcre32 *code, const pcre32_extra *extra,
545                PCRE_SPTR32 subject, int length, int startoffset,
546                int options, int *ovector, int ovecsize,
547                int *workspace, int wscount);
548    
549    
550    PCRE 32-BIT API STRING EXTRACTION FUNCTIONS
551    
552           int pcre32_copy_named_substring(const pcre32 *code,
553                PCRE_SPTR32 subject, int *ovector,
554                int stringcount, PCRE_SPTR32 stringname,
555                PCRE_UCHAR32 *buffer, int buffersize);
556    
557           int pcre32_copy_substring(PCRE_SPTR32 subject, int *ovector,
558                int stringcount, int stringnumber, PCRE_UCHAR32 *buffer,
559                int buffersize);
560    
561           int pcre32_get_named_substring(const pcre32 *code,
562                PCRE_SPTR32 subject, int *ovector,
563                int stringcount, PCRE_SPTR32 stringname,
564                PCRE_SPTR32 *stringptr);
565    
566           int pcre32_get_stringnumber(const pcre32 *code,
567                PCRE_SPTR32 name);
568    
569           int pcre32_get_stringtable_entries(const pcre32 *code,
570                PCRE_SPTR32 name, PCRE_UCHAR32 **first, PCRE_UCHAR32 **last);
571    
572           int pcre32_get_substring(PCRE_SPTR32 subject, int *ovector,
573                int stringcount, int stringnumber,
574                PCRE_SPTR32 *stringptr);
575    
576           int pcre32_get_substring_list(PCRE_SPTR32 subject,
577                int *ovector, int stringcount, PCRE_SPTR32 **listptr);
578    
579           void pcre32_free_substring(PCRE_SPTR32 stringptr);
580    
581           void pcre32_free_substring_list(PCRE_SPTR32 *stringptr);
582    
583    
584    PCRE 32-BIT API AUXILIARY FUNCTIONS
585    
586           pcre32_jit_stack *pcre32_jit_stack_alloc(int startsize, int maxsize);
587    
588           void pcre32_jit_stack_free(pcre32_jit_stack *stack);
589    
590           void pcre32_assign_jit_stack(pcre32_extra *extra,
591                pcre32_jit_callback callback, void *data);
592    
593           const unsigned char *pcre32_maketables(void);
594    
595           int pcre32_fullinfo(const pcre32 *code, const pcre32_extra *extra,
596                int what, void *where);
597    
598           int pcre32_refcount(pcre32 *code, int adjust);
599    
600           int pcre32_config(int what, void *where);
601    
602           const char *pcre32_version(void);
603    
604           int pcre32_pattern_to_host_byte_order(pcre32 *code,
605                pcre32_extra *extra, const unsigned char *tables);
606    
607    
608    PCRE 32-BIT API INDIRECTED FUNCTIONS
609    
610           void *(*pcre32_malloc)(size_t);
611    
612           void (*pcre32_free)(void *);
613    
614           void *(*pcre32_stack_malloc)(size_t);
615    
616           void (*pcre32_stack_free)(void *);
617    
618           int (*pcre32_callout)(pcre32_callout_block *);
619    
620    
621    PCRE 32-BIT API 32-BIT-ONLY FUNCTION
622    
623           int pcre32_utf32_to_host_byte_order(PCRE_UCHAR32 *output,
624                PCRE_SPTR32 input, int length, int *byte_order,
625                int keep_boms);
626    
627    
628    THE PCRE 32-BIT LIBRARY
629    
630           Starting  with  release  8.32, it is possible to compile a PCRE library
631           that supports 32-bit character strings, including  UTF-32  strings,  as
632           well as or instead of the original 8-bit library. This work was done by
633           Christian Persch, based on the work done  by  Zoltan  Herczeg  for  the
634           16-bit  library.  All  three  libraries contain identical sets of func-
635           tions, used in exactly the same way.  Only the names of  the  functions
636           and  the  data  types  of their arguments and results are different. To
637           avoid over-complication and reduce the documentation maintenance  load,
638           most  of  the PCRE documentation describes the 8-bit library, with only
639           occasional references to the 16-bit and  32-bit  libraries.  This  page
640           describes what is different when you use the 32-bit library.
641    
642           WARNING:  A  single  application  can  be linked with all or any of the
643           three libraries, but you must take care when processing any  particular
644           pattern  to  use  functions  from just one library. For example, if you
645           want to study a pattern that was compiled  with  pcre32_compile(),  you
646           must do so with pcre32_study(), not pcre_study(), and you must free the
647           study data with pcre32_free_study().
648    
649    
650    THE HEADER FILE
651    
652           There is only one header file, pcre.h. It contains prototypes  for  all
653           the functions in all libraries, as well as definitions of flags, struc-
654           tures, error codes, etc.
655    
656    
657    THE LIBRARY NAME
658    
659           In Unix-like systems, the 32-bit library is called libpcre32,  and  can
660           normally  be  accesss  by adding -lpcre32 to the command for linking an
661           application that uses PCRE.
662    
663    
664    STRING TYPES
665    
666           In the 8-bit library, strings are passed to PCRE library  functions  as
667           vectors  of  bytes  with  the  C  type "char *". In the 32-bit library,
668           strings are passed as vectors of unsigned 32-bit quantities. The  macro
669           PCRE_UCHAR32  specifies  an  appropriate  data type, and PCRE_SPTR32 is
670           defined as "const PCRE_UCHAR32 *". In very many environments, "unsigned
671           int" is a 32-bit data type. When PCRE is built, it defines PCRE_UCHAR32
672           as "unsigned int", but checks that it really is a 32-bit data type.  If
673           it is not, the build fails with an error message telling the maintainer
674           to modify the definition appropriately.
675    
676    
677    STRUCTURE TYPES
678    
679           The types of the opaque structures that are used  for  compiled  32-bit
680           patterns  and  JIT stacks are pcre32 and pcre32_jit_stack respectively.
681           The  type  of  the  user-accessible  structure  that  is  returned   by
682           pcre32_study()  is  pcre32_extra, and the type of the structure that is
683           used for passing data to a callout  function  is  pcre32_callout_block.
684           These structures contain the same fields, with the same names, as their
685           8-bit counterparts. The only difference is that pointers  to  character
686           strings are 32-bit instead of 8-bit types.
687    
688    
689    32-BIT FUNCTIONS
690    
691           For  every function in the 8-bit library there is a corresponding func-
692           tion in the 32-bit library with a name that starts with pcre32_ instead
693           of  pcre_.  The  prototypes are listed above. In addition, there is one
694           extra function, pcre32_utf32_to_host_byte_order(). This  is  a  utility
695           function  that converts a UTF-32 character string to host byte order if
696           necessary. The other 32-bit  functions  expect  the  strings  they  are
697           passed to be in host byte order.
698    
699           The input and output arguments of pcre32_utf32_to_host_byte_order() may
700           point to the same address, that is, conversion in place  is  supported.
701           The output buffer must be at least as long as the input.
702    
703           The  length  argument  specifies the number of 32-bit data units in the
704           input string; a negative value specifies a zero-terminated string.
705    
706           If byte_order is NULL, it is assumed that the string starts off in host
707           byte  order. This may be changed by byte-order marks (BOMs) anywhere in
708           the string (commonly as the first character).
709    
710           If byte_order is not NULL, a non-zero value of the integer to which  it
711           points  means  that  the input starts off in host byte order, otherwise
712           the opposite order is assumed. Again, BOMs in  the  string  can  change
713           this. The final byte order is passed back at the end of processing.
714    
715           If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
716           copied into the output string. Otherwise they are discarded.
717    
718           The result of the function is the number of 32-bit  units  placed  into
719           the  output  buffer,  including  the  zero terminator if the string was
720           zero-terminated.
721    
722    
723    SUBJECT STRING OFFSETS
724    
725           The offsets within subject strings that are returned  by  the  matching
726           functions are in 32-bit units rather than bytes.
727    
728    
729    NAMED SUBPATTERNS
730    
731           The  name-to-number translation table that is maintained for named sub-
732           patterns uses 32-bit characters.  The  pcre32_get_stringtable_entries()
733           function returns the length of each entry in the table as the number of
734           32-bit data units.
735    
736    
737    OPTION NAMES
738    
739           There   are   two   new   general   option   names,   PCRE_UTF32    and
740           PCRE_NO_UTF32_CHECK,     which     correspond    to    PCRE_UTF8    and
741           PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
742           define  the  same bits in the options word. There is a discussion about
743           the validity of UTF-32 strings in the pcreunicode page.
744    
745           For the pcre32_config() function there is an  option  PCRE_CONFIG_UTF32
746           that  returns  1  if UTF-32 support is configured, otherwise 0. If this
747           option  is  given  to  pcre_config()  or  pcre16_config(),  or  if  the
748           PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF16  option is given to pcre32_con-
749           fig(), the result is the PCRE_ERROR_BADOPTION error.
750    
751    
752    CHARACTER CODES
753    
754           In 32-bit mode, when  PCRE_UTF32  is  not  set,  character  values  are
755           treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
756           that they can range from 0 to 0x7fffffff instead of 0 to 0xff.  Charac-
757           ter  types for characters less than 0xff can therefore be influenced by
758           the locale in the same way as before.   Characters  greater  than  0xff
759           have only one case, and no "type" (such as letter or digit).
760    
761           In  UTF-32  mode,  the  character  code  is  Unicode, in the range 0 to
762           0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
763           because those are "surrogate" values that are ill-formed in UTF-32.
764    
765           A  UTF-32 string can indicate its endianness by special code knows as a
766           byte-order mark (BOM). The PCRE functions do not handle this, expecting
767           strings   to   be  in  host  byte  order.  A  utility  function  called
768           pcre32_utf32_to_host_byte_order() is provided to help  with  this  (see
769           above).
770    
771    
772    ERROR NAMES
773    
774           The  error  PCRE_ERROR_BADUTF32  corresponds  to its 8-bit counterpart.
775           The error PCRE_ERROR_BADMODE is given when a compiled pattern is passed
776           to  a  function that processes patterns in the other mode, for example,
777           if a pattern compiled with pcre_compile() is passed to pcre32_exec().
778    
779           There are new error codes whose names  begin  with  PCRE_UTF32_ERR  for
780           invalid  UTF-32  strings,  corresponding to the PCRE_UTF8_ERR codes for
781           UTF-8 strings that are described in the section entitled "Reason  codes
782           for  invalid UTF-8 strings" in the main pcreapi page. The UTF-32 errors
783           are:
784    
785             PCRE_UTF32_ERR1  Surrogate character (range from 0xd800 to 0xdfff)
786             PCRE_UTF32_ERR2  Non-character
787             PCRE_UTF32_ERR3  Character > 0x10ffff
788    
789    
790    ERROR TEXTS
791    
792           If there is an error while compiling a pattern, the error text that  is
793           passed  back by pcre32_compile() or pcre32_compile2() is still an 8-bit
794           character string, zero-terminated.
795    
796    
797    CALLOUTS
798    
799           The subject and mark fields in the callout block that is  passed  to  a
800           callout function point to 32-bit vectors.
801    
802    
803    TESTING
804    
805           The  pcretest  program continues to operate with 8-bit input and output
806           files, but it can be used for testing the 32-bit library. If it is  run
807           with the command line option -32, patterns and subject strings are con-
808           verted from 8-bit to 32-bit before being passed to PCRE, and the 32-bit
809           library  functions  are used instead of the 8-bit ones. Returned 32-bit
810           strings are converted to 8-bit for output. If both the  8-bit  and  the
811           16-bit libraries were not compiled, pcretest defaults to 32-bit and the
812           -32 option is ignored.
813    
814           When PCRE is being built, the RunTest script that is  called  by  "make
815           check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
816           16-bit and 32-bit libraries has been built, and runs the  tests  appro-
817           priately.
818    
819    
820    NOT SUPPORTED IN 32-BIT MODE
821    
822           Not all the features of the 8-bit library are available with the 32-bit
823           library. The C++ and POSIX wrapper functions  support  only  the  8-bit
824           library, and the pcregrep program is at present 8-bit only.
825    
826    
827    AUTHOR
828    
829           Philip Hazel
830           University Computing Service
831           Cambridge CB2 3QH, England.
832    
833    
834    REVISION
835    
836           Last updated: 08 November 2012
837           Copyright (c) 1997-2012 University of Cambridge.
838    ------------------------------------------------------------------------------
839    
840    
841    PCREBUILD(3)               Library Functions Manual               PCREBUILD(3)
842    
843    
844    
845    NAME
846           PCRE - Perl-compatible regular expressions
847    
848  PCRE BUILD-TIME OPTIONS  PCRE BUILD-TIME OPTIONS
849    
850         This  document  describes  the  optional  features  of PCRE that can be         This  document  describes  the  optional  features  of PCRE that can be
851         selected when the library is compiled. They are all selected, or  dese-         selected when the library is compiled. It assumes use of the  configure
852         lected, by providing options to the configure script that is run before         script,  where the optional features are selected or deselected by pro-
853         the make command. The complete list of  options  for  configure  (which         viding options to configure before running the make  command.  However,
854         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
855         directory) can be obtained by running         environments using the GUI facility of cmake-gui if you are using CMake
856           instead of configure to build PCRE.
857    
858           There  is a lot more information about building PCRE without using con-
859           figure (including information about using CMake or building "by  hand")
860           in  the file called NON-AUTOTOOLS-BUILD, which is part of the PCRE dis-
861           tribution. You should consult this file as well as the README  file  if
862           you are building in a non-Unix-like environment.
863    
864           The complete list of options for configure (which includes the standard
865           ones such as the  selection  of  the  installation  directory)  can  be
866           obtained by running
867    
868           ./configure --help           ./configure --help
869    
870         The following sections describe certain options whose names begin  with         The  following  sections  include  descriptions  of options whose names
871         --enable  or  --disable. These settings specify changes to the defaults         begin with --enable or --disable. These settings specify changes to the
872         for the configure command. Because of the  way  that  configure  works,         defaults  for  the configure command. Because of the way that configure
873         --enable  and  --disable  always  come  in  pairs, so the complementary         works, --enable and --disable always come in pairs, so  the  complemen-
874         option always exists as well, but as it specifies the  default,  it  is         tary  option always exists as well, but as it specifies the default, it
875         not described.         is not described.
876    
877    
878    BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES
879    
880           By default, a library called libpcre  is  built,  containing  functions
881           that  take  string  arguments  contained in vectors of bytes, either as
882           single-byte characters, or interpreted as UTF-8 strings. You  can  also
883           build  a  separate library, called libpcre16, in which strings are con-
884           tained in vectors of 16-bit data units and interpreted either  as  sin-
885           gle-unit characters or UTF-16 strings, by adding
886    
887             --enable-pcre16
888    
889           to the configure command. You can also build a separate library, called
890           libpcre32, in which strings are contained in  vectors  of  32-bit  data
891           units  and  interpreted  either  as  single-unit  characters  or UTF-32
892           strings, by adding
893    
894             --enable-pcre32
895    
896           to the configure command. If you do not want the 8-bit library, add
897    
898             --disable-pcre8
899    
900           as well. At least one of the three libraries must be built.  Note  that
901           the  C++  and  POSIX  wrappers are for the 8-bit library only, and that
902           pcregrep is an 8-bit program. None of these are  built  if  you  select
903           only the 16-bit or 32-bit libraries.
904    
905    
906    BUILDING SHARED AND STATIC LIBRARIES
907    
908           The  PCRE building process uses libtool to build both shared and static
909           Unix libraries by default. You can suppress one of these by adding  one
910           of
911    
912             --disable-shared
913             --disable-static
914    
915           to the configure command, as required.
916    
917    
918  C++ SUPPORT  C++ SUPPORT
919    
920         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
921         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,
922         library for PCRE. You can disable this by adding         it  automatically  builds  the C++ wrapper library (which supports only
923           8-bit strings). You can disable this by adding
924    
925           --disable-cpp           --disable-cpp
926    
927         to the configure command.         to the configure command.
928    
929    
930  UTF-8 SUPPORT  UTF-8, UTF-16 AND UTF-32 SUPPORT
931    
932         To build PCRE with support for UTF-8 character strings, add         To build PCRE with support for UTF Unicode character strings, add
933    
934           --enable-utf8           --enable-utf
935    
936         to  the  configure  command.  Of  itself, this does not make PCRE treat         to the configure command. This setting applies to all three  libraries,
937         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
938         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
939         function.         library.  There  are no separate options for enabling UTF-8, UTF-16 and
940           UTF-32 independently because that would allow ridiculous settings  such
941           as  requesting UTF-16 support while building only the 8-bit library. It
942           is not possible to build one library with UTF support and another with-
943           out  in the same configuration. (For backwards compatibility, --enable-
944           utf8 is a synonym of --enable-utf.)
945    
946           Of itself, this setting does not make  PCRE  treat  strings  as  UTF-8,
947           UTF-16  or UTF-32. As well as compiling PCRE with this option, you also
948           have have to set the PCRE_UTF8, PCRE_UTF16  or  PCRE_UTF32  option  (as
949           appropriate) when you call one of the pattern compiling functions.
950    
951           If  you  set --enable-utf when compiling in an EBCDIC environment, PCRE
952           expects its input to be either ASCII or UTF-8 (depending  on  the  run-
953           time option). It is not possible to support both EBCDIC and UTF-8 codes
954           in the same version of  the  library.  Consequently,  --enable-utf  and
955           --enable-ebcdic are mutually exclusive.
956    
957    
958  UNICODE CHARACTER PROPERTY SUPPORT  UNICODE CHARACTER PROPERTY SUPPORT
959    
960         UTF-8 support allows PCRE to process character values greater than  255         UTF  support allows the libraries to process character codepoints up to
961         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
962         vide any facilities for accessing the properties of such characters. If         not provide any facilities for accessing the properties of such charac-
963         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,
964         refer to Unicode character properties, you must add         which refer to Unicode character properties, you must add
965    
966           --enable-unicode-properties           --enable-unicode-properties
967    
968         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
969         not explicitly requested it.         not explicitly requested it.
970    
971         Including  Unicode  property  support  adds around 90K of tables to the         Including Unicode property support adds around 30K  of  tables  to  the
972         PCRE library, approximately doubling its size. Only the  general  cate-         PCRE  library.  Only  the general category properties such as Lu and Nd
973         gory  properties  such as Lu and Nd are supported. Details are given in         are supported. Details are given in the pcrepattern documentation.
974         the pcrepattern documentation.  
975    
976    JUST-IN-TIME COMPILER SUPPORT
977    
978           Just-in-time compiler support is included in the build by specifying
979    
980             --enable-jit
981    
982           This support is available only for certain hardware  architectures.  If
983           this  option  is  set  for  an unsupported architecture, a compile time
984           error occurs.  See the pcrejit documentation for a  discussion  of  JIT
985           usage. When JIT support is enabled, pcregrep automatically makes use of
986           it, unless you add
987    
988             --disable-pcregrep-jit
989    
990           to the "configure" command.
991    
992    
993  CODE VALUE OF NEWLINE  CODE VALUE OF NEWLINE
994    
995         By default, PCRE treats character 10 (linefeed) as the newline  charac-         By default, PCRE interprets the linefeed (LF) character  as  indicating
996         ter. This is the normal newline character on Unix-like systems. You can         the  end  of  a line. This is the normal newline character on Unix-like
997         compile PCRE to use character 13 (carriage return) instead by adding         systems. You can compile PCRE to use carriage return (CR)  instead,  by
998           adding
999    
1000           --enable-newline-is-cr           --enable-newline-is-cr
1001    
1002         to the configure command. For completeness there is  also  a  --enable-         to  the  configure  command.  There  is  also  a --enable-newline-is-lf
1003         newline-is-lf  option,  which explicitly specifies linefeed as the new-         option, which explicitly specifies linefeed as the newline character.
        line character.  
1004    
1005           Alternatively, you can specify that line endings are to be indicated by
1006           the two character sequence CRLF. If you want this, add
1007    
1008  BUILDING SHARED AND STATIC LIBRARIES           --enable-newline-is-crlf
1009    
1010         The PCRE building process uses libtool to build both shared and  static         to the configure command. There is a fourth option, specified by
        Unix  libraries by default. You can suppress one of these by adding one  
        of  
1011    
1012           --disable-shared           --enable-newline-is-anycrlf
          --disable-static  
1013    
1014         to the configure command, as required.         which  causes  PCRE  to recognize any of the three sequences CR, LF, or
1015           CRLF as indicating a line ending. Finally, a fifth option, specified by
1016    
1017             --enable-newline-is-any
1018    
1019  POSIX MALLOC USAGE         causes PCRE to recognize any Unicode newline sequence.
1020    
1021         When PCRE is called through the POSIX interface (see the pcreposix doc-         Whatever line ending convention is selected when PCRE is built  can  be
1022         umentation),  additional  working  storage  is required for holding the         overridden  when  the library functions are called. At build time it is
1023         pointers to capturing substrings, because PCRE requires three  integers         conventional to use the standard for your operating system.
        per  substring,  whereas  the POSIX interface provides only two. If the  
        number of expected substrings is small, the wrapper function uses space  
        on the stack, because this is faster than using malloc() for each call.  
        The default threshold above which the stack is no longer used is 10; it  
        can be changed by adding a setting such as  
1024    
          --with-posix-malloc-threshold=20  
1025    
1026         to the configure command.  WHAT \R MATCHES
1027    
1028           By default, the sequence \R in a pattern matches  any  Unicode  newline
1029           sequence,  whatever  has  been selected as the line ending sequence. If
1030           you specify
1031    
1032  LIMITING PCRE RESOURCE USAGE           --enable-bsr-anycrlf
1033    
1034         Internally,  PCRE has a function called match(), which it calls repeat-         the default is changed so that \R matches only CR, LF, or  CRLF.  What-
1035         edly  (possibly  recursively)  when  matching  a   pattern   with   the         ever  is selected when PCRE is built can be overridden when the library
1036         pcre_exec()  function.  By controlling the maximum number of times this         functions are called.
        function may be called during a single matching operation, a limit  can  
        be  placed  on  the resources used by a single call to pcre_exec(). The  
        limit can be changed at run time, as described in the pcreapi  documen-  
        tation.  The default is 10 million, but this can be changed by adding a  
        setting such as  
1037    
          --with-match-limit=500000  
1038    
1039         to  the  configure  command.  This  setting  has  no  effect   on   the  POSIX MALLOC USAGE
1040         pcre_dfa_exec() matching function.  
1041           When the 8-bit library is called through the POSIX interface  (see  the
1042           pcreposix  documentation),  additional  working storage is required for
1043           holding the pointers to capturing  substrings,  because  PCRE  requires
1044           three integers per substring, whereas the POSIX interface provides only
1045           two. If the number of expected substrings is small, the  wrapper  func-
1046           tion  uses  space  on the stack, because this is faster than using mal-
1047           loc() for each call. The default threshold above which the stack is  no
1048           longer used is 10; it can be changed by adding a setting such as
1049    
1050             --with-posix-malloc-threshold=20
1051    
1052           to the configure command.
1053    
1054    
1055  HANDLING VERY LARGE PATTERNS  HANDLING VERY LARGE PATTERNS
1056    
1057         Within  a  compiled  pattern,  offset values are used to point from one         Within  a  compiled  pattern,  offset values are used to point from one
1058         part to another (for example, from an opening parenthesis to an  alter-         part to another (for example, from an opening parenthesis to an  alter-
1059         nation  metacharacter).  By default, two-byte values are used for these         nation  metacharacter).  By default, in the 8-bit and 16-bit libraries,
1060         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
1061         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
1062         Nevertheless, some people do want to process enormous patterns,  so  it         but the most gigantic patterns.  Nevertheless, some people do  want  to
1063         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
1064         adding a setting such as         use three-byte or four-byte offsets by adding a setting such as
1065    
1066           --with-link-size=3           --with-link-size=3
1067    
1068         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
1069         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,
1070         additional bytes when handling them.         using longer offsets slows down the operation of PCRE because it has to
1071           load  additional  data  when  handling them. For the 32-bit library the
1072         If you build PCRE with an increased link size, test 2 (and  test  5  if         value is always 4 and cannot be overridden; the value  of  --with-link-
1073         you  are using UTF-8) will fail. Part of the output of these tests is a         size is ignored.
        representation of the compiled pattern, and this changes with the  link  
        size.  
1074    
1075    
1076  AVOIDING EXCESSIVE STACK USAGE  AVOIDING EXCESSIVE STACK USAGE
# Line 365  AVOIDING EXCESSIVE STACK USAGE Line 1079  AVOIDING EXCESSIVE STACK USAGE
1079         ing by making recursive calls to an internal function  called  match().         ing by making recursive calls to an internal function  called  match().
1080         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-
1081         verely limit PCRE's operation. (The Unix environment does  not  usually         verely limit PCRE's operation. (The Unix environment does  not  usually
1082         suffer  from  this  problem.)  An alternative approach that uses memory         suffer from this problem, but it may sometimes be necessary to increase
1083         from the heap to remember data, instead  of  using  recursive  function         the maximum stack size.  There is a discussion in the  pcrestack  docu-
1084         calls,  has been implemented to work round this problem. If you want to         mentation.)  An alternative approach to recursion that uses memory from
1085         build a version of PCRE that works this way, add         the heap to remember data, instead of using recursive  function  calls,
1086           has  been  implemented to work round the problem of limited stack size.
1087           If you want to build a version of PCRE that works this way, add
1088    
1089           --disable-stack-for-recursion           --disable-stack-for-recursion
1090    
1091         to the configure command. With this configuration, PCRE  will  use  the         to the configure command. With this configuration, PCRE  will  use  the
1092         pcre_stack_malloc  and pcre_stack_free variables to call memory manage-         pcre_stack_malloc  and pcre_stack_free variables to call memory manage-
1093         ment functions. Separate functions are provided because  the  usage  is         ment functions. By default these point to malloc() and free(), but  you
1094         very  predictable:  the  block sizes requested are always the same, and         can replace the pointers so that your own functions are used instead.
1095         the blocks are always freed in reverse order. A calling  program  might  
1096         be  able  to implement optimized functions that perform better than the         Separate  functions  are  provided  rather  than  using pcre_malloc and
1097         standard malloc() and  free()  functions.  PCRE  runs  noticeably  more         pcre_free because the  usage  is  very  predictable:  the  block  sizes
1098         slowly when built in this way. This option affects only the pcre_exec()         requested  are  always  the  same,  and  the blocks are always freed in
1099         function; it is not relevant for the the pcre_dfa_exec() function.         reverse order. A calling program might be able to  implement  optimized
1100           functions  that  perform  better  than  malloc()  and free(). PCRE runs
1101           noticeably more slowly when built in this way. This option affects only
1102           the pcre_exec() function; it is not relevant for pcre_dfa_exec().
1103    
1104    
1105    LIMITING PCRE RESOURCE USAGE
1106    
1107           Internally,  PCRE has a function called match(), which it calls repeat-
1108           edly  (sometimes  recursively)  when  matching  a  pattern   with   the
1109           pcre_exec()  function.  By controlling the maximum number of times this
1110           function may be called during a single matching operation, a limit  can
1111           be  placed  on  the resources used by a single call to pcre_exec(). The
1112           limit can be changed at run time, as described in the pcreapi  documen-
1113           tation.  The default is 10 million, but this can be changed by adding a
1114           setting such as
1115    
1116             --with-match-limit=500000
1117    
1118           to  the  configure  command.  This  setting  has  no  effect   on   the
1119           pcre_dfa_exec() matching function.
1120    
1121           In  some  environments  it is desirable to limit the depth of recursive
1122           calls of match() more strictly than the total number of calls, in order
1123           to  restrict  the maximum amount of stack (or heap, if --disable-stack-
1124           for-recursion is specified) that is used. A second limit controls this;
1125           it  defaults  to  the  value  that is set for --with-match-limit, which
1126           imposes no additional constraints. However, you can set a  lower  limit
1127           by adding, for example,
1128    
1129             --with-match-limit-recursion=10000
1130    
1131           to  the  configure  command.  This  value can also be overridden at run
1132           time.
1133    
1134    
1135    CREATING CHARACTER TABLES AT BUILD TIME
1136    
1137           PCRE uses fixed tables for processing characters whose code values  are
1138           less  than 256. By default, PCRE is built with a set of tables that are
1139           distributed in the file pcre_chartables.c.dist. These  tables  are  for
1140           ASCII codes only. If you add
1141    
1142             --enable-rebuild-chartables
1143    
1144           to  the  configure  command, the distributed tables are no longer used.
1145           Instead, a program called dftables is compiled and  run.  This  outputs
1146           the source for new set of tables, created in the default locale of your
1147           C run-time system. (This method of replacing the tables does  not  work
1148           if  you are cross compiling, because dftables is run on the local host.
1149           If you need to create alternative tables when cross compiling, you will
1150           have to do so "by hand".)
1151    
1152    
1153  USING EBCDIC CODE  USING EBCDIC CODE
1154    
1155         PCRE assumes by default that it will run in an  environment  where  the         PCRE  assumes  by  default that it will run in an environment where the
1156         character  code  is  ASCII  (or Unicode, which is a superset of ASCII).         character code is ASCII (or Unicode, which is  a  superset  of  ASCII).
1157         PCRE can, however, be compiled to  run  in  an  EBCDIC  environment  by         This  is  the  case for most computer operating systems. PCRE can, how-
1158         adding         ever, be compiled to run in an EBCDIC environment by adding
1159    
1160           --enable-ebcdic           --enable-ebcdic
1161    
1162         to the configure command.         to the configure command. This setting implies --enable-rebuild-charta-
1163           bles.  You  should  only  use  it if you know that you are in an EBCDIC
1164           environment (for example,  an  IBM  mainframe  operating  system).  The
1165           --enable-ebcdic option is incompatible with --enable-utf.
1166    
1167           The EBCDIC character that corresponds to an ASCII LF is assumed to have
1168           the value 0x15 by default. However, in some EBCDIC  environments,  0x25
1169           is used. In such an environment you should use
1170    
1171             --enable-ebcdic-nl25
1172    
1173           as well as, or instead of, --enable-ebcdic. The EBCDIC character for CR
1174           has the same value as in ASCII, namely, 0x0d.  Whichever  of  0x15  and
1175           0x25 is not chosen as LF is made to correspond to the Unicode NEL char-
1176           acter (which, in Unicode, is 0x85).
1177    
1178           The options that select newline behaviour, such as --enable-newline-is-
1179           cr, and equivalent run-time options, refer to these character values in
1180           an EBCDIC environment.
1181    
1182    
1183    PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT
1184    
1185           By default, pcregrep reads all files as plain text. You can build it so
1186           that it recognizes files whose names end in .gz or .bz2, and reads them
1187           with libz or libbz2, respectively, by adding one or both of
1188    
1189             --enable-pcregrep-libz
1190             --enable-pcregrep-libbz2
1191    
1192           to the configure command. These options naturally require that the rel-
1193           evant  libraries  are installed on your system. Configuration will fail
1194           if they are not.
1195    
1196    
1197    PCREGREP BUFFER SIZE
1198    
1199           pcregrep uses an internal buffer to hold a "window" on the file  it  is
1200           scanning, in order to be able to output "before" and "after" lines when
1201           it finds a match. The size of the buffer is controlled by  a  parameter
1202           whose default value is 20K. The buffer itself is three times this size,
1203           but because of the way it is used for holding "before" lines, the long-
1204           est  line  that  is guaranteed to be processable is the parameter size.
1205           You can change the default parameter value by adding, for example,
1206    
1207             --with-pcregrep-bufsize=50K
1208    
1209           to the configure command. The caller of pcregrep can, however, override
1210           this value by specifying a run-time option.
1211    
1212    
1213    PCRETEST OPTION FOR LIBREADLINE SUPPORT
1214    
1215           If you add
1216    
1217             --enable-pcretest-libreadline
1218    
1219           to  the  configure  command,  pcretest  is  linked with the libreadline
1220           library, and when its input is from a terminal, it reads it  using  the
1221           readline() function. This provides line-editing and history facilities.
1222           Note that libreadline is GPL-licensed, so if you distribute a binary of
1223           pcretest linked in this way, there may be licensing issues.
1224    
1225           Setting  this  option  causes  the -lreadline option to be added to the
1226           pcretest build. In many operating environments with  a  sytem-installed
1227           libreadline this is sufficient. However, in some environments (e.g.  if
1228           an unmodified distribution version of readline is in use),  some  extra
1229           configuration  may  be necessary. The INSTALL file for libreadline says
1230           this:
1231    
1232             "Readline uses the termcap functions, but does not link with the
1233             termcap or curses library itself, allowing applications which link
1234             with readline the to choose an appropriate library."
1235    
1236           If your environment has not been set up so that an appropriate  library
1237           is automatically included, you may need to add something like
1238    
1239             LIBS="-ncurses"
1240    
1241           immediately before the configure command.
1242    
1243    
1244    DEBUGGING WITH VALGRIND SUPPORT
1245    
1246           By adding the
1247    
1248             --enable-valgrind
1249    
1250           option  to to the configure command, PCRE will use valgrind annotations
1251           to mark certain memory regions as  unaddressable.  This  allows  it  to
1252           detect invalid memory accesses, and is mostly useful for debugging PCRE
1253           itself.
1254    
1255    
1256    CODE COVERAGE REPORTING
1257    
1258           If your C compiler is gcc, you can build a version  of  PCRE  that  can
1259           generate a code coverage report for its test suite. To enable this, you
1260           must install lcov version 1.6 or above. Then specify
1261    
1262             --enable-coverage
1263    
1264           to the configure command and build PCRE in the usual way.
1265    
1266           Note that using ccache (a caching C compiler) is incompatible with code
1267           coverage  reporting. If you have configured ccache to run automatically
1268           on your system, you must set the environment variable
1269    
1270             CCACHE_DISABLE=1
1271    
1272           before running make to build PCRE, so that ccache is not used.
1273    
1274           When --enable-coverage is used,  the  following  addition  targets  are
1275           added to the Makefile:
1276    
1277             make coverage
1278    
1279           This  creates  a  fresh  coverage report for the PCRE test suite. It is
1280           equivalent to running "make coverage-reset", "make  coverage-baseline",
1281           "make check", and then "make coverage-report".
1282    
1283             make coverage-reset
1284    
1285           This zeroes the coverage counters, but does nothing else.
1286    
1287             make coverage-baseline
1288    
1289           This captures baseline coverage information.
1290    
1291             make coverage-report
1292    
1293           This creates the coverage report.
1294    
1295             make coverage-clean-report
1296    
1297           This  removes the generated coverage report without cleaning the cover-
1298           age data itself.
1299    
1300             make coverage-clean-data
1301    
1302           This removes the captured coverage data without removing  the  coverage
1303           files created at compile time (*.gcno).
1304    
1305             make coverage-clean
1306    
1307           This  cleans all coverage data including the generated coverage report.
1308           For more information about code coverage, see the gcov and  lcov  docu-
1309           mentation.
1310    
1311    
1312    SEE ALSO
1313    
1314           pcreapi(3), pcre16, pcre32, pcre_config(3).
1315    
1316    
1317    AUTHOR
1318    
1319           Philip Hazel
1320           University Computing Service
1321           Cambridge CB2 3QH, England.
1322    
1323    
1324    REVISION
1325    
1326  Last updated: 15 August 2005         Last updated: 30 October 2012
1327  Copyright (c) 1997-2005 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
1328  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1329    
1330    
1331    PCREMATCHING(3)            Library Functions Manual            PCREMATCHING(3)
1332    
1333    
 PCREMATCHING(3)                                                PCREMATCHING(3)  
   
1334    
1335  NAME  NAME
1336         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
1337    
   
1338  PCRE MATCHING ALGORITHMS  PCRE MATCHING ALGORITHMS
1339    
1340         This document describes the two different algorithms that are available         This document describes the two different algorithms that are available
1341         in PCRE for matching a compiled regular expression against a given sub-         in PCRE for matching a compiled regular expression against a given sub-
1342         ject  string.  The  "standard"  algorithm  is  the  one provided by the         ject  string.  The  "standard"  algorithm  is  the  one provided by the
1343         pcre_exec() function.  This works in the same was  as  Perl's  matching         pcre_exec(), pcre16_exec() and pcre32_exec() functions. These  work  in
1344         function, and provides a Perl-compatible matching operation.         the  same as as Perl's matching function, and provide a Perl-compatible
1345           matching  operation.   The  just-in-time  (JIT)  optimization  that  is
1346         An  alternative  algorithm is provided by the pcre_dfa_exec() function;         described  in  the pcrejit documentation is compatible with these func-
1347         this operates in a different way, and is not  Perl-compatible.  It  has         tions.
1348         advantages  and disadvantages compared with the standard algorithm, and  
1349         these are described below.         An  alternative  algorithm  is   provided   by   the   pcre_dfa_exec(),
1350           pcre16_dfa_exec()  and  pcre32_dfa_exec()  functions; they operate in a
1351           different way, and are not Perl-compatible. This alternative has advan-
1352           tages and disadvantages compared with the standard algorithm, and these
1353           are described below.
1354    
1355         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
1356         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 431  PCRE MATCHING ALGORITHMS Line 1364  PCRE MATCHING ALGORITHMS
1364           <something> <something else> <something further>           <something> <something else> <something further>
1365    
1366         there are three possible answers. The standard algorithm finds only one         there are three possible answers. The standard algorithm finds only one
1367         of them, whereas the DFA algorithm finds all three.         of them, whereas the alternative algorithm finds all three.
1368    
1369    
1370  REGULAR EXPRESSIONS AS TREES  REGULAR EXPRESSIONS AS TREES
# Line 440  REGULAR EXPRESSIONS AS TREES Line 1373  REGULAR EXPRESSIONS AS TREES
1373         resented  as  a  tree structure. An unlimited repetition in the pattern         resented  as  a  tree structure. An unlimited repetition in the pattern
1374         makes the tree of infinite size, but it is still a tree.  Matching  the         makes the tree of infinite size, but it is still a tree.  Matching  the
1375         pattern  to a given subject string (from a given starting point) can be         pattern  to a given subject string (from a given starting point) can be
1376         thought of as a search of the tree.  There are  two  standard  ways  to         thought of as a search of the tree.  There are two  ways  to  search  a
1377         search  a  tree: depth-first and breadth-first, and these correspond to         tree:  depth-first  and  breadth-first, and these correspond to the two
1378         the two matching algorithms provided by PCRE.         matching algorithms provided by PCRE.
1379    
1380    
1381  THE STANDARD MATCHING ALGORITHM  THE STANDARD MATCHING ALGORITHM
1382    
1383         In the terminology of Jeffrey Friedl's book Mastering  Regular  Expres-         In the terminology of Jeffrey Friedl's book "Mastering Regular  Expres-
1384         sions,  the  standard  algorithm  is  an "NFA algorithm". It conducts a         sions",  the  standard  algorithm  is an "NFA algorithm". It conducts a
1385         depth-first search of the pattern tree. That is, it  proceeds  along  a         depth-first search of the pattern tree. That is, it  proceeds  along  a
1386         single path through the tree, checking that the subject matches what is         single path through the tree, checking that the subject matches what is
1387         required. When there is a mismatch, the algorithm  tries  any  alterna-         required. When there is a mismatch, the algorithm  tries  any  alterna-
# Line 472  THE STANDARD MATCHING ALGORITHM Line 1405  THE STANDARD MATCHING ALGORITHM
1405         This provides support for capturing parentheses and back references.         This provides support for capturing parentheses and back references.
1406    
1407    
1408  THE DFA MATCHING ALGORITHM  THE ALTERNATIVE MATCHING ALGORITHM
1409    
1410         DFA stands for "deterministic finite automaton", but you do not need to         This algorithm conducts a breadth-first search of  the  tree.  Starting
1411         understand the origins of that name. This algorithm conducts a breadth-         from  the  first  matching  point  in the subject, it scans the subject
1412         first search of the tree. Starting from the first matching point in the         string from left to right, once, character by character, and as it does
1413         subject,  it scans the subject string from left to right, once, charac-         this,  it remembers all the paths through the tree that represent valid
1414         ter by character, and as it does  this,  it  remembers  all  the  paths         matches. In Friedl's terminology, this is a kind  of  "DFA  algorithm",
1415         through the tree that represent valid matches.         though  it is not implemented as a traditional finite state machine (it
1416           keeps multiple states active simultaneously).
1417         The  scan  continues until either the end of the subject is reached, or  
1418         there are no more unterminated paths. At this point,  terminated  paths         Although the general principle of this matching algorithm  is  that  it
1419         represent  the different matching possibilities (if there are none, the         scans  the subject string only once, without backtracking, there is one
1420         match has failed).  Thus, if there is more  than  one  possible  match,         exception: when a lookaround assertion is encountered,  the  characters
1421           following  or  preceding  the  current  point  have to be independently
1422           inspected.
1423    
1424           The scan continues until either the end of the subject is  reached,  or
1425           there  are  no more unterminated paths. At this point, terminated paths
1426           represent the different matching possibilities (if there are none,  the
1427           match  has  failed).   Thus,  if there is more than one possible match,
1428         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-
1429         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
1430         match (which is necessarily the shortest) has been found.         an option to stop the algorithm after the first match (which is  neces-
1431           sarily the shortest) is found.
1432    
1433         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
1434         subject. If the pattern         subject. If the pattern
1435    
1436           cat(er(pillar)?)           cat(er(pillar)?)?
1437    
1438         is matched against the string "the caterpillar catchment",  the  result         is matched against the string "the caterpillar catchment",  the  result
1439         will  be the three strings "cat", "cater", and "caterpillar" that start         will  be the three strings "caterpillar", "cater", and "cat" that start
1440         at the fourth character of the subject. The algorithm does not automat-         at the fifth character of the subject. The algorithm does not automati-
1441         ically move on to find matches that start at later positions.         cally move on to find matches that start at later positions.
1442    
1443         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
1444         supported by the DFA matching algorithm. They are as follows:         supported by the alternative matching algorithm. They are as follows:
1445    
1446         1. Because the algorithm finds all  possible  matches,  the  greedy  or         1. Because the algorithm finds all  possible  matches,  the  greedy  or
1447         ungreedy  nature  of repetition quantifiers is not relevant. Greedy and         ungreedy  nature  of repetition quantifiers is not relevant. Greedy and
1448         ungreedy quantifiers are treated in exactly the same way.         ungreedy quantifiers are treated in exactly the same way. However, pos-
1449           sessive  quantifiers can make a difference when what follows could also
1450           match what is quantified, for example in a pattern like this:
1451    
1452             ^a++\w!
1453    
1454           This pattern matches "aaab!" but not "aaa!", which would be matched  by
1455           a  non-possessive quantifier. Similarly, if an atomic group is present,
1456           it is matched as if it were a standalone pattern at the current  point,
1457           and  the  longest match is then "locked in" for the rest of the overall
1458           pattern.
1459    
1460         2. When dealing with multiple paths through the tree simultaneously, it         2. When dealing with multiple paths through the tree simultaneously, it
1461         is  not  straightforward  to  keep track of captured substrings for the         is  not  straightforward  to  keep track of captured substrings for the
# Line 516  THE DFA MATCHING ALGORITHM Line 1467  THE DFA MATCHING ALGORITHM
1467         tern are not supported, and cause errors if encountered.         tern are not supported, and cause errors if encountered.
1468    
1469         4.  For  the same reason, conditional expressions that use a backrefer-         4.  For  the same reason, conditional expressions that use a backrefer-
1470         ence as the condition are not supported.         ence as the condition or test for a specific group  recursion  are  not
1471           supported.
1472    
1473           5.  Because  many  paths  through the tree may be active, the \K escape
1474           sequence, which resets the start of the match when encountered (but may
1475           be  on  some  paths  and not on others), is not supported. It causes an
1476           error if encountered.
1477    
1478         5. 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
1479         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.
1480    
1481         6.  The \C escape sequence, which (in the standard algorithm) matches a         7.  The  \C  escape  sequence, which (in the standard algorithm) always
1482         single byte, even in UTF-8 mode, is not supported because the DFA algo-         matches a single data unit, even in UTF-8, UTF-16 or UTF-32  modes,  is
1483         rithm moves through the subject string one character at a time, for all         not  supported  in these modes, because the alternative algorithm moves
1484         active paths through the tree.         through the subject string one character (not data unit) at a time, for
1485           all active paths through the tree.
1486    
1487           8.  Except for (*FAIL), the backtracking control verbs such as (*PRUNE)
1488           are not supported. (*FAIL) is supported, and  behaves  like  a  failing
1489           negative assertion.
1490    
 ADVANTAGES OF THE DFA ALGORITHM  
1491    
1492         Using the DFA matching algorithm provides the following advantages:  ADVANTAGES OF THE ALTERNATIVE ALGORITHM
1493    
1494           Using  the alternative matching algorithm provides the following advan-
1495           tages:
1496    
1497         1. All possible matches (at a single point in the subject) are automat-         1. All possible matches (at a single point in the subject) are automat-
1498         ically  found,  and  in particular, the longest match is found. To find         ically  found,  and  in particular, the longest match is found. To find
1499         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
1500         things with callouts.         things with callouts.
1501    
1502         2.  There is much better support for partial matching. The restrictions         2.  Because  the  alternative  algorithm  scans the subject string just
1503         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-
1504         rithm  for partial matching do not apply to the DFA algorithm. For non-         sible  to  pass  very  long subject strings to the matching function in
1505         anchored patterns, the starting position of a partial match  is  avail-         several pieces, checking for partial matching each time. Although it is
1506         able.         possible  to  do multi-segment matching using the standard algorithm by
1507           retaining partially matched substrings, it  is  more  complicated.  The
1508         3.  Because  the  DFA algorithm scans the subject string just once, and         pcrepartial  documentation  gives  details of partial matching and dis-
1509         never needs to backtrack, it is possible  to  pass  very  long  subject         cusses multi-segment matching.
        strings  to  the matching function in several pieces, checking for par-  
        tial matching each time.  
1510    
1511    
1512  DISADVANTAGES OF THE DFA ALGORITHM  DISADVANTAGES OF THE ALTERNATIVE ALGORITHM
1513    
1514         The DFA algorithm suffers from a number of disadvantages:         The alternative algorithm suffers from a number of disadvantages:
1515    
1516         1. It is substantially slower than  the  standard  algorithm.  This  is         1. It is substantially slower than  the  standard  algorithm.  This  is
1517         partly  because  it has to search for all possible matches, but is also         partly  because  it has to search for all possible matches, but is also
# Line 558  DISADVANTAGES OF THE DFA ALGORITHM Line 1519  DISADVANTAGES OF THE DFA ALGORITHM
1519    
1520         2. Capturing parentheses and back references are not supported.         2. Capturing parentheses and back references are not supported.
1521    
1522         3. The "atomic group" feature of PCRE regular expressions is supported,         3. Although atomic groups are supported, their use does not provide the
1523         but  does not provide the advantage that it does for the standard algo-         performance advantage that it does for the standard algorithm.
1524         rithm.  
1525    
1526    AUTHOR
1527    
1528           Philip Hazel
1529           University Computing Service
1530           Cambridge CB2 3QH, England.
1531    
 Last updated: 28 February 2005  
 Copyright (c) 1997-2005 University of Cambridge.  
 ------------------------------------------------------------------------------  
1532    
1533    REVISION
1534    
1535           Last updated: 08 January 2012
1536           Copyright (c) 1997-2012 University of Cambridge.
1537    ------------------------------------------------------------------------------
1538    
1539    
1540    PCREAPI(3)                 Library Functions Manual                 PCREAPI(3)
1541    
 PCREAPI(3)                                                          PCREAPI(3)  
1542    
1543    
1544  NAME  NAME
1545         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
1546    
1547           #include <pcre.h>
1548    
 PCRE NATIVE API  
1549    
1550         #include <pcre.h>  PCRE NATIVE API BASIC FUNCTIONS
1551    
1552         pcre *pcre_compile(const char *pattern, int options,         pcre *pcre_compile(const char *pattern, int options,
1553              const char **errptr, int *erroffset,              const char **errptr, int *erroffset,
# Line 590  PCRE NATIVE API Line 1561  PCRE NATIVE API
1561         pcre_extra *pcre_study(const pcre *code, int options,         pcre_extra *pcre_study(const pcre *code, int options,
1562              const char **errptr);              const char **errptr);
1563    
1564           void pcre_free_study(pcre_extra *extra);
1565    
1566         int pcre_exec(const pcre *code, const pcre_extra *extra,         int pcre_exec(const pcre *code, const pcre_extra *extra,
1567              const char *subject, int length, int startoffset,              const char *subject, int length, int startoffset,
1568              int options, int *ovector, int ovecsize);              int options, int *ovector, int ovecsize);
# Line 599  PCRE NATIVE API Line 1572  PCRE NATIVE API
1572              int options, int *ovector, int ovecsize,              int options, int *ovector, int ovecsize,
1573              int *workspace, int wscount);              int *workspace, int wscount);
1574    
1575    
1576    PCRE NATIVE API STRING EXTRACTION FUNCTIONS
1577    
1578         int pcre_copy_named_substring(const pcre *code,         int pcre_copy_named_substring(const pcre *code,
1579              const char *subject, int *ovector,              const char *subject, int *ovector,
1580              int stringcount, const char *stringname,              int stringcount, const char *stringname,
# Line 616  PCRE NATIVE API Line 1592  PCRE NATIVE API
1592         int pcre_get_stringnumber(const pcre *code,         int pcre_get_stringnumber(const pcre *code,
1593              const char *name);              const char *name);
1594    
1595           int pcre_get_stringtable_entries(const pcre *code,
1596                const char *name, char **first, char **last);
1597    
1598         int pcre_get_substring(const char *subject, int *ovector,         int pcre_get_substring(const char *subject, int *ovector,
1599              int stringcount, int stringnumber,              int stringcount, int stringnumber,
1600              const char **stringptr);              const char **stringptr);
# Line 627  PCRE NATIVE API Line 1606  PCRE NATIVE API
1606    
1607         void pcre_free_substring_list(const char **stringptr);         void pcre_free_substring_list(const char **stringptr);
1608    
1609    
1610    PCRE NATIVE API AUXILIARY FUNCTIONS
1611    
1612           int pcre_jit_exec(const pcre *code, const pcre_extra *extra,
1613                const char *subject, int length, int startoffset,
1614                int options, int *ovector, int ovecsize,
1615                pcre_jit_stack *jstack);
1616    
1617           pcre_jit_stack *pcre_jit_stack_alloc(int startsize, int maxsize);
1618    
1619           void pcre_jit_stack_free(pcre_jit_stack *stack);
1620    
1621           void pcre_assign_jit_stack(pcre_extra *extra,
1622                pcre_jit_callback callback, void *data);
1623    
1624         const unsigned char *pcre_maketables(void);         const unsigned char *pcre_maketables(void);
1625    
1626         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
1627              int what, void *where);              int what, void *where);
1628    
        int pcre_info(const pcre *code, int *optptr, int *firstcharptr);  
   
1629         int pcre_refcount(pcre *code, int adjust);         int pcre_refcount(pcre *code, int adjust);
1630    
1631         int pcre_config(int what, void *where);         int pcre_config(int what, void *where);
1632    
1633         char *pcre_version(void);         const char *pcre_version(void);
1634    
1635           int pcre_pattern_to_host_byte_order(pcre *code,
1636                pcre_extra *extra, const unsigned char *tables);
1637    
1638    
1639    PCRE NATIVE API INDIRECTED FUNCTIONS
1640    
1641         void *(*pcre_malloc)(size_t);         void *(*pcre_malloc)(size_t);
1642    
# Line 651  PCRE NATIVE API Line 1649  PCRE NATIVE API
1649         int (*pcre_callout)(pcre_callout_block *);         int (*pcre_callout)(pcre_callout_block *);
1650    
1651    
1652    PCRE 8-BIT, 16-BIT, AND 32-BIT LIBRARIES
1653    
1654           As  well  as  support  for  8-bit character strings, PCRE also supports
1655           16-bit strings (from release 8.30) and  32-bit  strings  (from  release
1656           8.32),  by means of two additional libraries. They can be built as well
1657           as, or instead of, the 8-bit library. To avoid too  much  complication,
1658           this  document describes the 8-bit versions of the functions, with only
1659           occasional references to the 16-bit and 32-bit libraries.
1660    
1661           The 16-bit and 32-bit functions operate in the same way as their  8-bit
1662           counterparts;  they  just  use different data types for their arguments
1663           and results, and their names start with pcre16_ or pcre32_  instead  of
1664           pcre_.  For  every  option  that  has  UTF8  in  its name (for example,
1665           PCRE_UTF8), there are corresponding 16-bit and 32-bit names  with  UTF8
1666           replaced by UTF16 or UTF32, respectively. This facility is in fact just
1667           cosmetic; the 16-bit and 32-bit option names define the same  bit  val-
1668           ues.
1669    
1670           References to bytes and UTF-8 in this document should be read as refer-
1671           ences to 16-bit data  quantities  and  UTF-16  when  using  the  16-bit
1672           library,  or  32-bit  data  quantities and UTF-32 when using the 32-bit
1673           library, unless specified otherwise. More details of the specific  dif-
1674           ferences  for  the  16-bit and 32-bit libraries are given in the pcre16
1675           and pcre32 pages.
1676    
1677    
1678  PCRE API OVERVIEW  PCRE API OVERVIEW
1679    
1680         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
1681         is also a set of wrapper functions that correspond to the POSIX regular         are  also some wrapper functions (for the 8-bit library only) that cor-
1682         expression  API.  These  are  described in the pcreposix documentation.         respond to the POSIX regular expression  API,  but  they  do  not  give
1683         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
1684         distributed with PCRE. It is documented in the pcrecpp page.         documentation. Both of these APIs define a set of C function  calls.  A
1685           C++ wrapper (again for the 8-bit library only) is also distributed with
1686         The  native  API  C  function prototypes are defined in the header file         PCRE. It is documented in the pcrecpp page.
1687         pcre.h, and on Unix systems the library itself is called  libpcre.   It  
1688         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
1689         application  that  uses  PCRE.  The  header  file  defines  the  macros         pcre.h,  and  on Unix-like systems the (8-bit) library itself is called
1690         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
1691         bers for the library.  Applications can use these  to  include  support         for  linking an application that uses PCRE. The header file defines the
1692           macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release
1693           numbers  for the library. Applications can use these to include support
1694         for different releases of PCRE.         for different releases of PCRE.
1695    
1696         The   functions   pcre_compile(),  pcre_compile2(),  pcre_study(),  and         In a Windows environment, if you want to statically link an application
1697         pcre_exec() are used for compiling and matching regular expressions  in         program  against  a  non-dll  pcre.a  file, you must define PCRE_STATIC
1698         a  Perl-compatible  manner. A sample program that demonstrates the sim-         before including pcre.h or pcrecpp.h, because otherwise  the  pcre_mal-
1699         plest way of using them is provided in the file  called  pcredemo.c  in         loc()   and   pcre_free()   exported   functions   will   be   declared
1700         the  source distribution. The pcresample documentation describes how to         __declspec(dllimport), with unwanted results.
1701         run it.  
1702           The  functions  pcre_compile(),  pcre_compile2(),   pcre_study(),   and
1703           pcre_exec()  are used for compiling and matching regular expressions in
1704           a Perl-compatible manner. A sample program that demonstrates  the  sim-
1705           plest  way  of  using them is provided in the file called pcredemo.c in
1706           the PCRE source distribution. A listing of this program is given in the
1707           pcredemo  documentation, and the pcresample documentation describes how
1708           to compile and run it.
1709    
1710           Just-in-time compiler support is an optional feature of PCRE  that  can
1711           be built in appropriate hardware environments. It greatly speeds up the
1712           matching performance of  many  patterns.  Simple  programs  can  easily
1713           request  that  it  be  used  if available, by setting an option that is
1714           ignored when it is not relevant. More complicated programs  might  need
1715           to     make    use    of    the    functions    pcre_jit_stack_alloc(),
1716           pcre_jit_stack_free(), and pcre_assign_jit_stack() in order to  control
1717           the JIT code's memory usage.
1718    
1719           From  release  8.32 there is also a direct interface for JIT execution,
1720           which gives improved performance. The JIT-specific functions  are  dis-
1721           cussed in the pcrejit documentation.
1722    
1723         A second matching function, pcre_dfa_exec(), which is not Perl-compati-         A second matching function, pcre_dfa_exec(), which is not Perl-compati-
1724         ble,  is  also provided. This uses a different algorithm for the match-         ble, is also provided. This uses a different algorithm for  the  match-
1725         ing. This allows it to find all possible matches (at a given  point  in         ing.  The  alternative algorithm finds all possible matches (at a given
1726         the  subject),  not  just  one. However, this algorithm does not return         point in the subject), and scans the subject just  once  (unless  there
1727           are  lookbehind  assertions).  However,  this algorithm does not return
1728         captured substrings. A description of the two matching  algorithms  and         captured substrings. A description of the two matching  algorithms  and
1729         their  advantages  and disadvantages is given in the pcrematching docu-         their  advantages  and disadvantages is given in the pcrematching docu-
1730         mentation.         mentation.
# Line 692  PCRE API OVERVIEW Line 1739  PCRE API OVERVIEW
1739           pcre_get_named_substring()           pcre_get_named_substring()
1740           pcre_get_substring_list()           pcre_get_substring_list()
1741           pcre_get_stringnumber()           pcre_get_stringnumber()
1742             pcre_get_stringtable_entries()
1743    
1744         pcre_free_substring() and pcre_free_substring_list() are also provided,         pcre_free_substring() and pcre_free_substring_list() are also provided,
1745         to free the memory used for extracted strings.         to free the memory used for extracted strings.
# Line 704  PCRE API OVERVIEW Line 1752  PCRE API OVERVIEW
1752         built are used.         built are used.
1753    
1754         The function pcre_fullinfo() is used to find out  information  about  a         The function pcre_fullinfo() is used to find out  information  about  a
1755         compiled  pattern; pcre_info() is an obsolete version that returns only         compiled  pattern.  The  function pcre_version() returns a pointer to a
1756         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.  
1757    
1758         The function pcre_refcount() maintains a  reference  count  in  a  data         The function pcre_refcount() maintains a  reference  count  in  a  data
1759         block  containing  a compiled pattern. This is provided for the benefit         block  containing  a compiled pattern. This is provided for the benefit
# Line 723  PCRE API OVERVIEW Line 1769  PCRE API OVERVIEW
1769         indirections  to  memory  management functions. These special functions         indirections  to  memory  management functions. These special functions
1770         are used only when PCRE is compiled to use  the  heap  for  remembering         are used only when PCRE is compiled to use  the  heap  for  remembering
1771         data, instead of recursive function calls, when running the pcre_exec()         data, instead of recursive function calls, when running the pcre_exec()
1772         function. This is a non-standard way of building PCRE, for use in envi-         function. See the pcrebuild documentation for  details  of  how  to  do
1773         ronments that have limited stacks. Because of the greater use of memory         this.  It  is  a non-standard way of building PCRE, for use in environ-
1774         management, it runs more slowly.  Separate functions  are  provided  so         ments that have limited stacks. Because of the greater  use  of  memory
1775         that  special-purpose  external  code  can  be used for this case. When         management,  it  runs  more  slowly. Separate functions are provided so
1776         used, these functions are always called in a  stack-like  manner  (last         that special-purpose external code can be  used  for  this  case.  When
1777         obtained,  first freed), and always for memory blocks of the same size.         used,  these  functions  are always called in a stack-like manner (last
1778           obtained, first freed), and always for memory blocks of the same  size.
1779           There  is  a discussion about PCRE's stack usage in the pcrestack docu-
1780           mentation.
1781    
1782         The global variable pcre_callout initially contains NULL. It can be set         The global variable pcre_callout initially contains NULL. It can be set
1783         by  the  caller  to  a "callout" function, which PCRE will then call at         by  the  caller  to  a "callout" function, which PCRE will then call at
# Line 736  PCRE API OVERVIEW Line 1785  PCRE API OVERVIEW
1785         pcrecallout documentation.         pcrecallout documentation.
1786    
1787    
1788    NEWLINES
1789    
1790           PCRE  supports five different conventions for indicating line breaks in
1791           strings: a single CR (carriage return) character, a  single  LF  (line-
1792           feed) character, the two-character sequence CRLF, any of the three pre-
1793           ceding, or any Unicode newline sequence. The Unicode newline  sequences
1794           are  the  three just mentioned, plus the single characters VT (vertical
1795           tab, U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line
1796           separator, U+2028), and PS (paragraph separator, U+2029).
1797    
1798           Each  of  the first three conventions is used by at least one operating
1799           system as its standard newline sequence. When PCRE is built, a  default
1800           can  be  specified.  The default default is LF, which is the Unix stan-
1801           dard. When PCRE is run, the default can be overridden,  either  when  a
1802           pattern is compiled, or when it is matched.
1803    
1804           At compile time, the newline convention can be specified by the options
1805           argument of pcre_compile(), or it can be specified by special  text  at
1806           the start of the pattern itself; this overrides any other settings. See
1807           the pcrepattern page for details of the special character sequences.
1808    
1809           In the PCRE documentation the word "newline" is used to mean "the char-
1810           acter  or pair of characters that indicate a line break". The choice of
1811           newline convention affects the handling of  the  dot,  circumflex,  and
1812           dollar metacharacters, the handling of #-comments in /x mode, and, when
1813           CRLF is a recognized line ending sequence, the match position  advance-
1814           ment for a non-anchored pattern. There is more detail about this in the
1815           section on pcre_exec() options below.
1816    
1817           The choice of newline convention does not affect the interpretation  of
1818           the  \n  or  \r  escape  sequences, nor does it affect what \R matches,
1819           which is controlled in a similar way, but by separate options.
1820    
1821    
1822  MULTITHREADING  MULTITHREADING
1823    
1824         The  PCRE  functions  can be used in multi-threading applications, with         The PCRE functions can be used in  multi-threading  applications,  with
1825         the  proviso  that  the  memory  management  functions  pointed  to  by         the  proviso  that  the  memory  management  functions  pointed  to  by
1826         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
1827         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 747  MULTITHREADING Line 1830  MULTITHREADING
1830         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
1831         at once.         at once.
1832    
1833           If  the just-in-time optimization feature is being used, it needs sepa-
1834           rate memory stack areas for each thread. See the pcrejit  documentation
1835           for more details.
1836    
1837    
1838  SAVING PRECOMPILED PATTERNS FOR LATER USE  SAVING PRECOMPILED PATTERNS FOR LATER USE
1839    
1840         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
1841         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
1842         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
1843         pcreprecompile documentation.         pcreprecompile documentation,  which  includes  a  description  of  the
1844           pcre_pattern_to_host_byte_order()  function. However, compiling a regu-
1845           lar expression with one version of PCRE for use with a  different  ver-
1846           sion is not guaranteed to work and may cause crashes.
1847    
1848    
1849  CHECKING BUILD-TIME OPTIONS  CHECKING BUILD-TIME OPTIONS
1850    
1851         int pcre_config(int what, void *where);         int pcre_config(int what, void *where);
1852    
1853         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-
1854         cover which optional features have been compiled into the PCRE library.         cover which optional features have been compiled into the PCRE library.
1855         The pcrebuild documentation has more details about these optional  fea-         The  pcrebuild documentation has more details about these optional fea-
1856         tures.         tures.
1857    
1858         The  first  argument  for pcre_config() is an integer, specifying which         The first argument for pcre_config() is an  integer,  specifying  which
1859         information is required; the second argument is a pointer to a variable         information is required; the second argument is a pointer to a variable
1860         into  which  the  information  is  placed. The following information is         into which the information is placed. The returned  value  is  zero  on
1861           success,  or  the negative error code PCRE_ERROR_BADOPTION if the value
1862           in the first argument is not recognized. The following  information  is
1863         available:         available:
1864    
1865           PCRE_CONFIG_UTF8           PCRE_CONFIG_UTF8
1866    
1867         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-
1868         able; otherwise it is set to zero.         able; otherwise it is set to zero. This value should normally be  given
1869           to the 8-bit version of this function, pcre_config(). If it is given to
1870           the  16-bit  or  32-bit  version  of  this  function,  the  result   is
1871           PCRE_ERROR_BADOPTION.
1872    
1873             PCRE_CONFIG_UTF16
1874    
1875           The output is an integer that is set to one if UTF-16 support is avail-
1876           able; otherwise it is set to zero. This value should normally be  given
1877           to the 16-bit version of this function, pcre16_config(). If it is given
1878           to the 8-bit  or  32-bit  version  of  this  function,  the  result  is
1879           PCRE_ERROR_BADOPTION.
1880    
1881             PCRE_CONFIG_UTF32
1882    
1883           The output is an integer that is set to one if UTF-32 support is avail-
1884           able; otherwise it is set to zero. This value should normally be  given
1885           to the 32-bit version of this function, pcre32_config(). If it is given
1886           to the 8-bit  or  16-bit  version  of  this  function,  the  result  is
1887           PCRE_ERROR_BADOPTION.
1888    
1889           PCRE_CONFIG_UNICODE_PROPERTIES           PCRE_CONFIG_UNICODE_PROPERTIES
1890    
1891         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
1892         character properties is available; otherwise it is set to zero.         character properties is available; otherwise it is set to zero.
1893    
1894             PCRE_CONFIG_JIT
1895    
1896           The output is an integer that is set to one if support for just-in-time
1897           compiling is available; otherwise it is set to zero.
1898    
1899             PCRE_CONFIG_JITTARGET
1900    
1901           The  output is a pointer to a zero-terminated "const char *" string. If
1902           JIT support is available, the string contains the name of the architec-
1903           ture  for  which the JIT compiler is configured, for example "x86 32bit
1904           (little endian + unaligned)". If JIT  support  is  not  available,  the
1905           result is NULL.
1906    
1907           PCRE_CONFIG_NEWLINE           PCRE_CONFIG_NEWLINE
1908    
1909         The output is an integer that is set to the value of the code  that  is         The  output  is  an integer whose value specifies the default character
1910         used  for the newline character. It is either linefeed (10) or carriage         sequence that is recognized as meaning "newline". The values  that  are
1911         return (13), and should normally be the  standard  character  for  your         supported in ASCII/Unicode environments are: 10 for LF, 13 for CR, 3338
1912         operating system.         for CRLF, -2 for ANYCRLF, and -1 for ANY. In EBCDIC  environments,  CR,
1913           ANYCRLF,  and  ANY  yield the same values. However, the value for LF is
1914           normally 21, though some EBCDIC environments use 37. The  corresponding
1915           values  for  CRLF are 3349 and 3365. The default should normally corre-
1916           spond to the standard sequence for your operating system.
1917    
1918             PCRE_CONFIG_BSR
1919    
1920           The output is an integer whose value indicates what character sequences
1921           the  \R  escape sequence matches by default. A value of 0 means that \R
1922           matches any Unicode line ending sequence; a value of 1  means  that  \R
1923           matches only CR, LF, or CRLF. The default can be overridden when a pat-
1924           tern is compiled or matched.
1925    
1926           PCRE_CONFIG_LINK_SIZE           PCRE_CONFIG_LINK_SIZE
1927    
1928         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
1929         internal linkage in compiled regular expressions. The value is 2, 3, or         internal  linkage  in  compiled  regular  expressions.  For  the  8-bit
1930         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
1931         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
1932         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
1933         pattern to be up to 64K in size.         default value of 2 is sufficient for all but the most massive patterns,
1934           since it allows the compiled pattern to be up to 64K  in  size.  Larger
1935           values  allow larger regular expressions to be compiled, at the expense
1936           of slower matching.
1937    
1938           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
1939    
# Line 804  CHECKING BUILD-TIME OPTIONS Line 1943  CHECKING BUILD-TIME OPTIONS
1943    
1944           PCRE_CONFIG_MATCH_LIMIT           PCRE_CONFIG_MATCH_LIMIT
1945    
1946         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-
1947         internal  matching  function  calls in a pcre_exec() execution. Further         ber  of  internal  matching  function calls in a pcre_exec() execution.
1948         details are given with pcre_exec() below.         Further details are given with pcre_exec() below.
1949    
1950             PCRE_CONFIG_MATCH_LIMIT_RECURSION
1951    
1952           The output is a long integer that gives the default limit for the depth
1953           of   recursion  when  calling  the  internal  matching  function  in  a
1954           pcre_exec() execution.  Further  details  are  given  with  pcre_exec()
1955           below.
1956    
1957           PCRE_CONFIG_STACKRECURSE           PCRE_CONFIG_STACKRECURSE
1958    
1959         The output is an integer that is set to one if internal recursion  when         The  output is an integer that is set to one if internal recursion when
1960         running pcre_exec() is implemented by recursive function calls that use         running pcre_exec() is implemented by recursive function calls that use
1961         the stack to remember their state. This is the usual way that  PCRE  is         the  stack  to remember their state. This is the usual way that PCRE is
1962         compiled. The output is zero if PCRE was compiled to use blocks of data         compiled. The output is zero if PCRE was compiled to use blocks of data
1963         on the  heap  instead  of  recursive  function  calls.  In  this  case,         on  the  heap  instead  of  recursive  function  calls.  In  this case,
1964         pcre_stack_malloc  and  pcre_stack_free  are  called  to  manage memory         pcre_stack_malloc and  pcre_stack_free  are  called  to  manage  memory
1965         blocks on the heap, thus avoiding the use of the stack.         blocks on the heap, thus avoiding the use of the stack.
1966    
1967    
# Line 832  COMPILING A PATTERN Line 1978  COMPILING A PATTERN
1978    
1979         Either of the functions pcre_compile() or pcre_compile2() can be called         Either of the functions pcre_compile() or pcre_compile2() can be called
1980         to compile a pattern into an internal form. The only difference between         to compile a pattern into an internal form. The only difference between
1981         the two interfaces is that pcre_compile2() has an additional  argument,         the  two interfaces is that pcre_compile2() has an additional argument,
1982         errorcodeptr, via which a numerical error code can be returned.         errorcodeptr, via which a numerical error  code  can  be  returned.  To
1983           avoid  too  much repetition, we refer just to pcre_compile() below, but
1984           the information applies equally to pcre_compile2().
1985    
1986         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
1987         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
1988         obtained  via  pcre_malloc is returned. This contains the compiled code         obtained via pcre_malloc is returned. This contains the  compiled  code
1989         and related data. The pcre type is defined for the returned block; this         and related data. The pcre type is defined for the returned block; this
1990         is a typedef for a structure whose contents are not externally defined.         is a typedef for a structure whose contents are not externally defined.
1991         It is up to the caller  to  free  the  memory  when  it  is  no  longer         It is up to the caller to free the memory (via pcre_free) when it is no
1992         required.         longer required.
1993    
1994         Although  the compiled code of a PCRE regex is relocatable, that is, it         Although the compiled code of a PCRE regex is relocatable, that is,  it
1995         does not depend on memory location, the complete pcre data block is not         does not depend on memory location, the complete pcre data block is not
1996         fully  relocatable, because it may contain a copy of the tableptr argu-         fully relocatable, because it may contain a copy of the tableptr  argu-
1997         ment, which is an address (see below).         ment, which is an address (see below).
1998    
1999         The options argument contains independent bits that affect the compila-         The options argument contains various bit settings that affect the com-
2000         tion.  It  should  be  zero  if  no options are required. The available         pilation. It should be zero if no options are required.  The  available
2001         options are described below. Some of them, in  particular,  those  that         options  are  described  below. Some of them (in particular, those that
2002         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
2003         pattern (see the detailed description  in  the  pcrepattern  documenta-         unset  from  within  the  pattern  (see the detailed description in the
2004         tion).  For  these options, the contents of the options argument speci-         pcrepattern documentation). For those options that can be different  in
2005         fies their initial settings at the start of compilation and  execution.         different  parts  of  the pattern, the contents of the options argument
2006         The  PCRE_ANCHORED option can be set at the time of matching as well as         specifies their settings at the start of compilation and execution. The
2007         at compile time.         PCRE_ANCHORED,  PCRE_BSR_xxx, PCRE_NEWLINE_xxx, PCRE_NO_UTF8_CHECK, and
2008           PCRE_NO_START_OPTIMIZE options can be set at the time  of  matching  as
2009           well as at compile time.
2010    
2011         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,
2012         if  compilation  of  a  pattern fails, pcre_compile() returns NULL, and         if compilation of a pattern fails,  pcre_compile()  returns  NULL,  and
2013         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-
2014         sage.  The  offset from the start of the pattern to the character where         sage. This is a static string that is part of the library. You must not
2015         the error was discovered is  placed  in  the  variable  pointed  to  by         try  to  free it. Normally, the offset from the start of the pattern to
2016         erroffset,  which  must  not  be  NULL. If it is, an immediate error is         the byte that was being processed when  the  error  was  discovered  is
2017         given.         placed  in the variable pointed to by erroffset, which must not be NULL
2018           (if it is, an immediate error is given). However, for an invalid  UTF-8
2019           string, the offset is that of the first byte of the failing character.
2020    
2021           Some  errors are not detected until the whole pattern has been scanned;
2022           in these cases, the offset passed back is the length  of  the  pattern.
2023           Note  that  the offset is in bytes, not characters, even in UTF-8 mode.
2024           It may sometimes point into the middle of a UTF-8 character.
2025    
2026         If pcre_compile2() is used instead of pcre_compile(),  and  the  error-         If pcre_compile2() is used instead of pcre_compile(),  and  the  error-
2027         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 909  COMPILING A PATTERN Line 2066  COMPILING A PATTERN
2066         all with number 255, before each pattern item. For  discussion  of  the         all with number 255, before each pattern item. For  discussion  of  the
2067         callout facility, see the pcrecallout documentation.         callout facility, see the pcrecallout documentation.
2068    
2069             PCRE_BSR_ANYCRLF
2070             PCRE_BSR_UNICODE
2071    
2072           These options (which are mutually exclusive) control what the \R escape
2073           sequence matches. The choice is either to match only CR, LF,  or  CRLF,
2074           or to match any Unicode newline sequence. The default is specified when
2075           PCRE is built. It can be overridden from within the pattern, or by set-
2076           ting an option when a compiled pattern is matched.
2077    
2078           PCRE_CASELESS           PCRE_CASELESS
2079    
2080         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 926  COMPILING A PATTERN Line 2092  COMPILING A PATTERN
2092    
2093         If this bit is set, a dollar metacharacter in the pattern matches  only         If this bit is set, a dollar metacharacter in the pattern matches  only
2094         at  the  end  of the subject string. Without this option, a dollar also         at  the  end  of the subject string. Without this option, a dollar also
2095         matches immediately before the final character if it is a newline  (but         matches immediately before a newline at the end of the string (but  not
2096         not  before  any  other  newlines).  The  PCRE_DOLLAR_ENDONLY option is         before  any  other newlines). The PCRE_DOLLAR_ENDONLY option is ignored
2097         ignored if PCRE_MULTILINE is set. There is no equivalent to this option         if PCRE_MULTILINE is set.  There is no equivalent  to  this  option  in
2098         in Perl, and no way to set it within a pattern.         Perl, and no way to set it within a pattern.
2099    
2100           PCRE_DOTALL           PCRE_DOTALL
2101    
2102         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-
2103         acters, including newlines. Without it,  newlines  are  excluded.  This         acter of any value, including one that indicates a newline. However, it
2104         option  is equivalent to Perl's /s option, and it can be changed within         only  ever  matches  one character, even if newlines are coded as CRLF.
2105         a pattern by a (?s) option setting.  A  negative  class  such  as  [^a]         Without this option, a dot does not match when the current position  is
2106         always  matches a newline character, independent of the setting of this         at a newline. This option is equivalent to Perl's /s option, and it can
2107         option.         be changed within a pattern by a (?s) option setting. A negative  class
2108           such as [^a] always matches newline characters, independent of the set-
2109           ting of this option.
2110    
2111             PCRE_DUPNAMES
2112    
2113           If this bit is set, names used to identify capturing  subpatterns  need
2114           not be unique. This can be helpful for certain types of pattern when it
2115           is known that only one instance of the named  subpattern  can  ever  be
2116           matched.  There  are  more details of named subpatterns below; see also
2117           the pcrepattern documentation.
2118    
2119           PCRE_EXTENDED           PCRE_EXTENDED
2120    
2121         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
2122         totally ignored except when escaped or inside a character class. White-         totally  ignored except when escaped or inside a character class. White
2123         space does not include the VT character (code 11). In addition, charac-         space does not include the VT character (code 11). In addition, charac-
2124         ters between an unescaped # outside a character class and the next new-         ters between an unescaped # outside a character class and the next new-
2125         line character, inclusive, are also  ignored.  This  is  equivalent  to         line, inclusive, are also ignored. This  is  equivalent  to  Perl's  /x
2126         Perl's  /x  option,  and  it  can be changed within a pattern by a (?x)         option,  and  it  can be changed within a pattern by a (?x) option set-
2127         option setting.         ting.
2128    
2129         This option makes it possible to include  comments  inside  complicated         Which characters are interpreted  as  newlines  is  controlled  by  the
2130         patterns.   Note,  however,  that this applies only to data characters.         options  passed to pcre_compile() or by a special sequence at the start
2131         Whitespace  characters  may  never  appear  within  special   character         of the pattern, as described in the section entitled  "Newline  conven-
2132         sequences  in  a  pattern,  for  example  within the sequence (?( which         tions" in the pcrepattern documentation. Note that the end of this type
2133         introduces a conditional subpattern.         of comment is  a  literal  newline  sequence  in  the  pattern;  escape
2134           sequences that happen to represent a newline do not count.
2135    
2136           This  option  makes  it possible to include comments inside complicated
2137           patterns.  Note, however, that this applies only  to  data  characters.
2138           White  space  characters  may  never  appear  within  special character
2139           sequences in a pattern, for example within the sequence (?( that intro-
2140           duces a conditional subpattern.
2141    
2142           PCRE_EXTRA           PCRE_EXTRA
2143    
2144         This option was invented in order to turn on  additional  functionality         This  option  was invented in order to turn on additional functionality
2145         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
2146         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
2147         letter  that  has  no  special  meaning causes an error, thus reserving         letter that has no special meaning  causes  an  error,  thus  reserving
2148         these combinations for future expansion. By  default,  as  in  Perl,  a         these  combinations  for  future  expansion.  By default, as in Perl, a
2149         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
2150         literal. There are at present no  other  features  controlled  by  this         literal. (Perl can, however, be persuaded to give an error for this, by
2151         option. It can also be set by a (?X) option setting within a pattern.         running it with the -w option.) There are at present no other  features
2152           controlled  by this option. It can also be set by a (?X) option setting
2153           within a pattern.
2154    
2155           PCRE_FIRSTLINE           PCRE_FIRSTLINE
2156    
2157         If  this  option  is  set,  an  unanchored pattern is required to match         If this option is set, an  unanchored  pattern  is  required  to  match
2158         before or at the first newline character in the subject string,  though         before  or  at  the  first  newline  in  the subject string, though the
2159         the matched text may continue over the newline.         matched text may continue over the newline.
2160    
2161             PCRE_JAVASCRIPT_COMPAT
2162    
2163           If this option is set, PCRE's behaviour is changed in some ways so that
2164           it  is  compatible with JavaScript rather than Perl. The changes are as
2165           follows:
2166    
2167           (1) A lone closing square bracket in a pattern  causes  a  compile-time
2168           error,  because this is illegal in JavaScript (by default it is treated
2169           as a data character). Thus, the pattern AB]CD becomes illegal when this
2170           option is set.
2171    
2172           (2)  At run time, a back reference to an unset subpattern group matches
2173           an empty string (by default this causes the current  matching  alterna-
2174           tive  to  fail). A pattern such as (\1)(a) succeeds when this option is
2175           set (assuming it can find an "a" in the subject), whereas it  fails  by
2176           default, for Perl compatibility.
2177    
2178           (3) \U matches an upper case "U" character; by default \U causes a com-
2179           pile time error (Perl uses \U to upper case subsequent characters).
2180    
2181           (4) \u matches a lower case "u" character unless it is followed by four
2182           hexadecimal  digits,  in  which case the hexadecimal number defines the
2183           code point to match. By default, \u causes a compile time  error  (Perl
2184           uses it to upper case the following character).
2185    
2186           (5)  \x matches a lower case "x" character unless it is followed by two
2187           hexadecimal digits, in which case the hexadecimal  number  defines  the
2188           code  point  to  match. By default, as in Perl, a hexadecimal number is
2189           always expected after \x, but it may have zero, one, or two digits (so,
2190           for example, \xz matches a binary zero character followed by z).
2191    
2192           PCRE_MULTILINE           PCRE_MULTILINE
2193    
# Line 983  COMPILING A PATTERN Line 2199  COMPILING A PATTERN
2199         is set). This is the same as Perl.         is set). This is the same as Perl.
2200    
2201         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"
2202         constructs  match  immediately following or immediately before any new-         constructs  match  immediately following or immediately before internal
2203         line in the subject string, respectively, as well as at the very  start         newlines in the subject string, respectively, as well as  at  the  very
2204         and  end. This is equivalent to Perl's /m option, and it can be changed         start  and  end.  This is equivalent to Perl's /m option, and it can be
2205         within a pattern by a (?m) option setting. If there are no "\n" charac-         changed within a pattern by a (?m) option setting. If there are no new-
2206         ters  in  a  subject  string, or no occurrences of ^ or $ in a pattern,         lines  in  a  subject string, or no occurrences of ^ or $ in a pattern,
2207         setting PCRE_MULTILINE has no effect.         setting PCRE_MULTILINE has no effect.
2208    
2209             PCRE_NEVER_UTF
2210    
2211           This option locks out interpretation of the pattern as UTF-8 (or UTF-16
2212           or  UTF-32  in the 16-bit and 32-bit libraries). In particular, it pre-
2213           vents the creator of the pattern from switching to  UTF  interpretation
2214           by starting the pattern with (*UTF). This may be useful in applications
2215           that  process  patterns  from  external  sources.  The  combination  of
2216           PCRE_UTF8 and PCRE_NEVER_UTF also causes an error.
2217    
2218             PCRE_NEWLINE_CR
2219             PCRE_NEWLINE_LF
2220             PCRE_NEWLINE_CRLF
2221             PCRE_NEWLINE_ANYCRLF
2222             PCRE_NEWLINE_ANY
2223    
2224           These  options  override the default newline definition that was chosen
2225           when PCRE was built. Setting the first or the second specifies  that  a
2226           newline  is  indicated  by a single character (CR or LF, respectively).
2227           Setting PCRE_NEWLINE_CRLF specifies that a newline is indicated by  the
2228           two-character  CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF specifies
2229           that any of the three preceding sequences should be recognized. Setting
2230           PCRE_NEWLINE_ANY  specifies that any Unicode newline sequence should be
2231           recognized.
2232    
2233           In an ASCII/Unicode environment, the Unicode newline sequences are  the
2234           three  just  mentioned,  plus  the  single characters VT (vertical tab,
2235           U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line sep-
2236           arator,  U+2028),  and  PS (paragraph separator, U+2029). For the 8-bit
2237           library, the last two are recognized only in UTF-8 mode.
2238    
2239           When PCRE is compiled to run in an EBCDIC (mainframe) environment,  the
2240           code for CR is 0x0d, the same as ASCII. However, the character code for
2241           LF is normally 0x15, though in some EBCDIC environments 0x25  is  used.
2242           Whichever  of  these  is  not LF is made to correspond to Unicode's NEL
2243           character. EBCDIC codes are all less than 256. For  more  details,  see
2244           the pcrebuild documentation.
2245    
2246           The  newline  setting  in  the  options  word  uses three bits that are
2247           treated as a number, giving eight possibilities. Currently only six are
2248           used  (default  plus the five values above). This means that if you set
2249           more than one newline option, the combination may or may not be  sensi-
2250           ble. For example, PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to
2251           PCRE_NEWLINE_CRLF, but other combinations may yield unused numbers  and
2252           cause an error.
2253    
2254           The  only  time  that a line break in a pattern is specially recognized
2255           when compiling is when PCRE_EXTENDED is set. CR and LF are white  space
2256           characters,  and so are ignored in this mode. Also, an unescaped # out-
2257           side a character class indicates a comment that lasts until  after  the
2258           next  line break sequence. In other circumstances, line break sequences
2259           in patterns are treated as literal data.
2260    
2261           The newline option that is set at compile time becomes the default that
2262           is used for pcre_exec() and pcre_dfa_exec(), but it can be overridden.
2263    
2264           PCRE_NO_AUTO_CAPTURE           PCRE_NO_AUTO_CAPTURE
2265    
2266         If this option is set, it disables the use of numbered capturing paren-         If this option is set, it disables the use of numbered capturing paren-
2267         theses  in the pattern. Any opening parenthesis that is not followed by         theses in the pattern. Any opening parenthesis that is not followed  by
2268         ? behaves as if it were followed by ?: but named parentheses can  still         ?  behaves as if it were followed by ?: but named parentheses can still
2269         be  used  for  capturing  (and  they acquire numbers in the usual way).         be used for capturing (and they acquire  numbers  in  the  usual  way).
2270         There is no equivalent of this option in Perl.         There is no equivalent of this option in Perl.
2271    
2272             PCRE_NO_START_OPTIMIZE
2273    
2274           This  is an option that acts at matching time; that is, it is really an
2275           option for pcre_exec() or pcre_dfa_exec(). If  it  is  set  at  compile
2276           time,  it is remembered with the compiled pattern and assumed at match-
2277           ing time. This is necessary if you want to use JIT  execution,  because
2278           the  JIT  compiler needs to know whether or not this option is set. For
2279           details see the discussion of PCRE_NO_START_OPTIMIZE below.
2280    
2281             PCRE_UCP
2282    
2283           This option changes the way PCRE processes \B, \b, \D, \d, \S, \s,  \W,
2284           \w,  and  some  of  the POSIX character classes. By default, only ASCII
2285           characters are recognized, but if PCRE_UCP is set,  Unicode  properties
2286           are  used instead to classify characters. More details are given in the
2287           section on generic character types in the pcrepattern page. If you  set
2288           PCRE_UCP,  matching  one of the items it affects takes much longer. The
2289           option is available only if PCRE has been compiled with  Unicode  prop-
2290           erty support.
2291    
2292           PCRE_UNGREEDY           PCRE_UNGREEDY
2293    
2294         This option inverts the "greediness" of the quantifiers  so  that  they         This  option  inverts  the "greediness" of the quantifiers so that they
2295         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
2296         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
2297         within the pattern.         within the pattern.
2298    
2299           PCRE_UTF8           PCRE_UTF8
2300    
2301         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
2302         strings of UTF-8 characters instead of single-byte  character  strings.         strings of UTF-8 characters instead of single-byte strings. However, it
2303         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,
2304         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
2305         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.  
2306    
2307           PCRE_NO_UTF8_CHECK           PCRE_NO_UTF8_CHECK
2308    
2309         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
2310         automatically  checked. If an invalid UTF-8 sequence of bytes is found,         automatically  checked.  There  is  a  discussion about the validity of
2311         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
2312         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
2313         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-
2314         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
2315         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
2316         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
2317         ing of subject strings.         passed to pcre_exec() and pcre_dfa_exec(),  to  suppress  the  validity
2318           checking  of  subject strings only. If the same string is being matched
2319           many times, the option can be safely set for the second and  subsequent
2320           matchings to improve performance.
2321    
2322    
2323  COMPILATION ERROR CODES  COMPILATION ERROR CODES
2324    
2325         The following table lists the error  codes  than  may  be  returned  by         The  following  table  lists  the  error  codes than may be returned by
2326         pcre_compile2(),  along with the error messages that may be returned by         pcre_compile2(), along with the error messages that may be returned  by
2327         both compiling functions.         both  compiling  functions.  Note  that error messages are always 8-bit
2328           ASCII strings, even in 16-bit or 32-bit mode. As  PCRE  has  developed,
2329           some  error codes have fallen out of use. To avoid confusion, they have
2330           not been re-used.
2331    
2332            0  no error            0  no error
2333            1  \ at end of pattern            1  \ at end of pattern
# Line 1043  COMPILATION ERROR CODES Line 2339  COMPILATION ERROR CODES
2339            7  invalid escape sequence in character class            7  invalid escape sequence in character class
2340            8  range out of order in character class            8  range out of order in character class
2341            9  nothing to repeat            9  nothing to repeat
2342           10  operand of unlimited repeat could match the empty string           10  [this code is not in use]
2343           11  internal error: unexpected repeat           11  internal error: unexpected repeat
2344           12  unrecognized character after (?           12  unrecognized character after (? or (?-
2345           13  POSIX named classes are supported only within a class           13  POSIX named classes are supported only within a class
2346           14  missing )           14  missing )
2347           15  reference to non-existent subpattern           15  reference to non-existent subpattern
2348           16  erroffset passed as NULL           16  erroffset passed as NULL
2349           17  unknown option bit(s) set           17  unknown option bit(s) set
2350           18  missing ) after comment           18  missing ) after comment
2351           19  parentheses nested too deeply           19  [this code is not in use]
2352           20  regular expression too large           20  regular expression is too large
2353           21  failed to get memory           21  failed to get memory
2354           22  unmatched parentheses           22  unmatched parentheses
2355           23  internal error: code overflow           23  internal error: code overflow
2356           24  unrecognized character after (?<           24  unrecognized character after (?<
2357           25  lookbehind assertion is not fixed length           25  lookbehind assertion is not fixed length
2358           26  malformed number after (?(           26  malformed number or name after (?(
2359           27  conditional group contains more than two branches           27  conditional group contains more than two branches
2360           28  assertion expected after (?(           28  assertion expected after (?(
2361           29  (?R or (?digits must be followed by )           29  (?R or (?[+-]digits must be followed by )
2362           30  unknown POSIX class name           30  unknown POSIX class name
2363           31  POSIX collating elements are not supported           31  POSIX collating elements are not supported
2364           32  this version of PCRE is not compiled with PCRE_UTF8 support           32  this version of PCRE is compiled without UTF support
2365           33  spare error           33  [this code is not in use]
2366           34  character value in \x{...} sequence is too large           34  character value in \x{...} sequence is too large
2367           35  invalid condition (?(0)           35  invalid condition (?(0)
2368           36  \C not allowed in lookbehind assertion           36  \C not allowed in lookbehind assertion
2369           37  PCRE does not support \L, \l, \N, \U, or \u           37  PCRE does not support \L, \l, \N{name}, \U, or \u
2370           38  number after (?C is > 255           38  number after (?C is > 255
2371           39  closing ) for (?C expected           39  closing ) for (?C expected
2372           40  recursive call could loop indefinitely           40  recursive call could loop indefinitely
2373           41  unrecognized character after (?P           41  unrecognized character after (?P
2374           42  syntax error after (?P           42  syntax error in subpattern name (missing terminator)
2375           43  two named groups have the same name           43  two named subpatterns have the same name
2376           44  invalid UTF-8 string           44  invalid UTF-8 string (specifically UTF-8)
2377           45  support for \P, \p, and \X has not been compiled           45  support for \P, \p, and \X has not been compiled
2378           46  malformed \P or \p sequence           46  malformed \P or \p sequence
2379           47  unknown property name after \P or \p           47  unknown property name after \P or \p
2380             48  subpattern name is too long (maximum 32 characters)
2381             49  too many named subpatterns (maximum 10000)
2382             50  [this code is not in use]
2383             51  octal value is greater than \377 in 8-bit non-UTF-8 mode
2384             52  internal error: overran compiling workspace
2385             53  internal error: previously-checked referenced subpattern
2386                   not found
2387             54  DEFINE group contains more than one branch
2388             55  repeating a DEFINE group is not allowed
2389             56  inconsistent NEWLINE options
2390             57  \g is not followed by a braced, angle-bracketed, or quoted
2391                   name/number or by a plain number
2392             58  a numbered reference must not be zero
2393             59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
2394             60  (*VERB) not recognized or malformed
2395             61  number is too big
2396             62  subpattern name expected
2397             63  digit expected after (?+
2398             64  ] is an invalid data character in JavaScript compatibility mode
2399             65  different names for subpatterns of the same number are
2400                   not allowed
2401             66  (*MARK) must have an argument
2402             67  this version of PCRE is not compiled with Unicode property
2403                   support
2404             68  \c must be followed by an ASCII character
2405             69  \k is not followed by a braced, angle-bracketed, or quoted name
2406             70  internal error: unknown opcode in find_fixedlength()
2407             71  \N is not supported in a class
2408             72  too many forward references
2409             73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
2410             74  invalid UTF-16 string (specifically UTF-16)
2411             75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
2412             76  character value in \u.... sequence is too large
2413             77  invalid UTF-32 string (specifically UTF-32)
2414    
2415           The numbers 32 and 10000 in errors 48 and 49  are  defaults;  different
2416           values may be used if the limits were changed when PCRE was built.
2417    
2418    
2419  STUDYING A PATTERN  STUDYING A PATTERN
# Line 1088  STUDYING A PATTERN Line 2421  STUDYING A PATTERN
2421         pcre_extra *pcre_study(const pcre *code, int options         pcre_extra *pcre_study(const pcre *code, int options
2422              const char **errptr);              const char **errptr);
2423    
2424         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
2425         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
2426         matching. The function pcre_study() takes a pointer to a compiled  pat-         matching.  The function pcre_study() takes a pointer to a compiled pat-
2427         tern as its first argument. If studying the pattern produces additional         tern as its first argument. If studying the pattern produces additional
2428         information that will help speed up matching,  pcre_study()  returns  a         information  that  will  help speed up matching, pcre_study() returns a
2429         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
2430         the results of the study.         the results of the study.
2431    
2432         The  returned  value  from  pcre_study()  can  be  passed  directly  to         The  returned  value  from  pcre_study()  can  be  passed  directly  to
2433         pcre_exec().  However,  a  pcre_extra  block also contains other fields         pcre_exec() or pcre_dfa_exec(). However, a pcre_extra block  also  con-
2434         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
2435         described below in the section on matching a pattern.         passed; these are described below in the section on matching a pattern.
2436    
2437         If  studying  the  pattern  does not produce any additional information         If studying the  pattern  does  not  produce  any  useful  information,
2438         pcre_study() returns NULL. In that circumstance, if the calling program         pcre_study()  returns  NULL  by  default.  In that circumstance, if the
2439         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
2440         its own pcre_extra block.         pcre_dfa_exec(),  it  must set up its own pcre_extra block. However, if
2441           pcre_study() is called  with  the  PCRE_STUDY_EXTRA_NEEDED  option,  it
2442         The second argument of pcre_study() contains option bits.  At  present,         returns a pcre_extra block even if studying did not find any additional
2443         no options are defined, and this argument should always be zero.         information. It may still return NULL, however, if an error  occurs  in
2444           pcre_study().
2445         The  third argument for pcre_study() is a pointer for an error message.  
2446         If studying succeeds (even if no data is  returned),  the  variable  it         The  second  argument  of  pcre_study() contains option bits. There are
2447         points  to  is set to NULL. Otherwise it points to a textual error mes-         three further options in addition to PCRE_STUDY_EXTRA_NEEDED:
2448         sage. You should therefore test the error pointer for NULL after  call-  
2449         ing pcre_study(), to be sure that it has run successfully.           PCRE_STUDY_JIT_COMPILE
2450             PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
2451             PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
2452    
2453           If any of these are set, and the just-in-time  compiler  is  available,
2454           the  pattern  is  further compiled into machine code that executes much
2455           faster than the pcre_exec()  interpretive  matching  function.  If  the
2456           just-in-time  compiler is not available, these options are ignored. All
2457           undefined bits in the options argument must be zero.
2458    
2459           JIT compilation is a heavyweight optimization. It can  take  some  time
2460           for  patterns  to  be analyzed, and for one-off matches and simple pat-
2461           terns the benefit of faster execution might be offset by a much  slower
2462           study time.  Not all patterns can be optimized by the JIT compiler. For
2463           those that cannot be handled, matching automatically falls back to  the
2464           pcre_exec()  interpreter.  For more details, see the pcrejit documenta-
2465           tion.
2466    
2467         This is a typical call to pcre_study():         The third argument for pcre_study() is a pointer for an error  message.
2468           If  studying  succeeds  (even  if no data is returned), the variable it
2469           points to is set to NULL. Otherwise it is set to  point  to  a  textual
2470           error message. This is a static string that is part of the library. You
2471           must not try to free it. You should test the  error  pointer  for  NULL
2472           after calling pcre_study(), to be sure that it has run successfully.
2473    
2474           When  you are finished with a pattern, you can free the memory used for
2475           the study data by calling pcre_free_study(). This function was added to
2476           the  API  for  release  8.20. For earlier versions, the memory could be
2477           freed with pcre_free(), just like the pattern itself. This  will  still
2478           work  in  cases where JIT optimization is not used, but it is advisable
2479           to change to the new function when convenient.
2480    
2481           pcre_extra *pe;         This is a typical way in which pcre_study() is used (except that  in  a
2482           pe = pcre_study(         real application there should be tests for errors):
2483    
2484             int rc;
2485             pcre *re;
2486             pcre_extra *sd;
2487             re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
2488             sd = pcre_study(
2489             re,             /* result of pcre_compile() */             re,             /* result of pcre_compile() */
2490             0,              /* no options exist */             0,              /* no options */
2491             &error);        /* set to NULL or points to a message */             &error);        /* set to NULL or points to a message */
2492             rc = pcre_exec(   /* see below for details of pcre_exec() options */
2493               re, sd, "subject", 7, 0, 0, ovector, 30);
2494             ...
2495             pcre_free_study(sd);
2496             pcre_free(re);
2497    
2498           Studying a pattern does two things: first, a lower bound for the length
2499           of subject string that is needed to match the pattern is computed. This
2500           does not mean that there are any strings of that length that match, but
2501           it does guarantee that no shorter strings match. The value is  used  to
2502           avoid wasting time by trying to match strings that are shorter than the
2503           lower bound. You can find out the value in a calling  program  via  the
2504           pcre_fullinfo() function.
2505    
2506           Studying a pattern is also useful for non-anchored patterns that do not
2507           have a single fixed starting character. A bitmap of  possible  starting
2508           bytes  is  created. This speeds up finding a position in the subject at
2509           which to start matching. (In 16-bit mode, the bitmap is used for 16-bit
2510           values  less  than  256.  In 32-bit mode, the bitmap is used for 32-bit
2511           values less than 256.)
2512    
2513           These two optimizations apply to both pcre_exec() and  pcre_dfa_exec(),
2514           and  the  information  is also used by the JIT compiler.  The optimiza-
2515           tions can be disabled by  setting  the  PCRE_NO_START_OPTIMIZE  option.
2516           You  might want to do this if your pattern contains callouts or (*MARK)
2517           and you want to make use of these facilities in  cases  where  matching
2518           fails.
2519    
2520           PCRE_NO_START_OPTIMIZE  can be specified at either compile time or exe-
2521           cution  time.  However,  if   PCRE_NO_START_OPTIMIZE   is   passed   to
2522           pcre_exec(), (that is, after any JIT compilation has happened) JIT exe-
2523           cution is disabled. For JIT execution to work with  PCRE_NO_START_OPTI-
2524           MIZE, the option must be set at compile time.
2525    
2526         At present, studying a pattern is useful only for non-anchored patterns         There is a longer discussion of PCRE_NO_START_OPTIMIZE below.
        that do not have a single fixed starting character. A bitmap of  possi-  
        ble starting bytes is created.  
2527    
2528    
2529  LOCALE SUPPORT  LOCALE SUPPORT
2530    
2531         PCRE  handles  caseless matching, and determines whether characters are         PCRE  handles  caseless matching, and determines whether characters are
2532         letters digits, or whatever, by reference to a set of  tables,  indexed         letters, digits, or whatever, by reference to a set of tables,  indexed
2533         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
2534         characters with codes less than 128. Higher-valued  codes  never  match         characters with codes less than 128. By  default,  higher-valued  codes
2535         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
2536         with Unicode character property support.         PCRE is built with Unicode character property  support.  Alternatively,
2537           the  PCRE_UCP  option  can  be  set at compile time; this causes \w and
2538         An internal set of tables is created in the default C locale when  PCRE         friends to use Unicode property support instead of built-in tables. The
2539         is  built.  This  is  used when the final argument of pcre_compile() is         use of locales with Unicode is discouraged. If you are handling charac-
2540         NULL, and is sufficient for many applications. An  alternative  set  of         ters with codes greater than 128, you should either use UTF-8 and  Uni-
2541         tables  can,  however, be supplied. These may be created in a different         code, or use locales, but not try to mix the two.
2542         locale from the default. As more and more applications change to  using  
2543         Unicode, the need for this locale support is expected to die away.         PCRE  contains  an  internal set of tables that are used when the final
2544           argument of pcre_compile() is  NULL.  These  are  sufficient  for  many
2545           applications.  Normally, the internal tables recognize only ASCII char-
2546           acters. However, when PCRE is built, it is possible to cause the inter-
2547           nal tables to be rebuilt in the default "C" locale of the local system,
2548           which may cause them to be different.
2549    
2550           The internal tables can always be overridden by tables supplied by  the
2551           application that calls PCRE. These may be created in a different locale
2552           from the default. As more and more applications change  to  using  Uni-
2553           code, the need for this locale support is expected to die away.
2554    
2555         External  tables  are  built by calling the pcre_maketables() function,         External  tables  are  built by calling the pcre_maketables() function,
2556         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
# Line 1155  LOCALE SUPPORT Line 2563  LOCALE SUPPORT
2563           tables = pcre_maketables();           tables = pcre_maketables();
2564           re = pcre_compile(..., tables);           re = pcre_compile(..., tables);
2565    
2566         When pcre_maketables() runs, the tables are built  in  memory  that  is         The locale name "fr_FR" is used on Linux and other  Unix-like  systems;
2567         obtained  via  pcre_malloc. It is the caller's responsibility to ensure         if you are using Windows, the name for the French locale is "french".
2568         that the memory containing the tables remains available for as long  as  
2569           When  pcre_maketables()  runs,  the  tables are built in memory that is
2570           obtained via pcre_malloc. It is the caller's responsibility  to  ensure
2571           that  the memory containing the tables remains available for as long as
2572         it is needed.         it is needed.
2573    
2574         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
2575         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()
2576         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-
2577         tern, compilation, studying and matching all happen in the same locale,         tern, compilation, studying and matching all happen in the same locale,
2578         but different patterns can be compiled in different locales.         but different patterns can be compiled in different locales.
2579    
2580         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
2581         the internal tables) to pcre_exec(). Although  not  intended  for  this         the  internal  tables)  to  pcre_exec(). Although not intended for this
2582         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
2583         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
2584         run time is discussed below in the section on matching a pattern.         run time is discussed below in the section on matching a pattern.
2585    
# Line 1178  INFORMATION ABOUT A PATTERN Line 2589  INFORMATION ABOUT A PATTERN
2589         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
2590              int what, void *where);              int what, void *where);
2591    
2592         The  pcre_fullinfo() function returns information about a compiled pat-         The pcre_fullinfo() function returns information about a compiled  pat-
2593         tern. It replaces the obsolete pcre_info() function, which is neverthe-         tern.  It replaces the pcre_info() function, which was removed from the
2594         less retained for backwards compability (and is documented below).         library at version 8.30, after more than 10 years of obsolescence.
2595    
2596         The  first  argument  for  pcre_fullinfo() is a pointer to the compiled         The first argument for pcre_fullinfo() is a  pointer  to  the  compiled
2597         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
2598         the  pattern  was not studied. The third argument specifies which piece         the pattern was not studied. The third argument specifies  which  piece
2599         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
2600         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
2601         success, or one of the following negative numbers:         success, or one of the following negative numbers:
2602    
2603           PCRE_ERROR_NULL       the argument code was NULL           PCRE_ERROR_NULL           the argument code was NULL
2604                                 the argument where was NULL                                     the argument where was NULL
2605           PCRE_ERROR_BADMAGIC   the "magic number" was not found           PCRE_ERROR_BADMAGIC       the "magic number" was not found
2606           PCRE_ERROR_BADOPTION  the value of what was invalid           PCRE_ERROR_BADENDIANNESS  the pattern was compiled with different
2607                                       endianness
2608         The "magic number" is placed at the start of each compiled  pattern  as           PCRE_ERROR_BADOPTION      the value of what was invalid
2609         an  simple check against passing an arbitrary memory pointer. Here is a           PCRE_ERROR_UNSET          the requested field is not set
2610         typical call of pcre_fullinfo(), to obtain the length of  the  compiled  
2611         pattern:         The  "magic  number" is placed at the start of each compiled pattern as
2612           an simple check against passing an arbitrary memory pointer. The  endi-
2613           anness error can occur if a compiled pattern is saved and reloaded on a
2614           different host. Here is a typical call of  pcre_fullinfo(),  to  obtain
2615           the length of the compiled pattern:
2616    
2617           int rc;           int rc;
2618           unsigned long int length;           size_t length;
2619           rc = pcre_fullinfo(           rc = pcre_fullinfo(
2620             re,               /* result of pcre_compile() */             re,               /* result of pcre_compile() */
2621             pe,               /* result of pcre_study(), or NULL */             sd,               /* result of pcre_study(), or NULL */
2622             PCRE_INFO_SIZE,   /* what is required */             PCRE_INFO_SIZE,   /* what is required */
2623             &length);         /* where to put the data */             &length);         /* where to put the data */
2624    
# Line 1231  INFORMATION ABOUT A PATTERN Line 2646  INFORMATION ABOUT A PATTERN
2646    
2647           PCRE_INFO_FIRSTBYTE           PCRE_INFO_FIRSTBYTE
2648    
2649         Return  information  about  the first byte of any matched string, for a         Return information about the first data unit of any matched string, for
2650         non-anchored   pattern.   (This    option    used    to    be    called         a non-anchored pattern. (The name of this option refers  to  the  8-bit
2651         PCRE_INFO_FIRSTCHAR;  the  old  name  is still recognized for backwards         library,  where data units are bytes.) The fourth argument should point
2652         compatibility.)         to an int variable.
2653    
2654         If there is a fixed first byte, for example, from  a  pattern  such  as         If there is a fixed first value, for example, the  letter  "c"  from  a
2655         (cat|cow|coyote),  it  is  returned in the integer pointed to by where.         pattern  such  as (cat|cow|coyote), its value is returned. In the 8-bit
2656         Otherwise, if either         library, the value is always less than 256. In the 16-bit  library  the
2657           value can be up to 0xffff. In the 32-bit library the value can be up to
2658           0x10ffff.
2659    
2660           If there is no fixed first value, and if either
2661    
2662         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
2663         branch starts with "^", or         branch starts with "^", or
# Line 1250  INFORMATION ABOUT A PATTERN Line 2669  INFORMATION ABOUT A PATTERN
2669         of  a  subject string or after any newline within the string. Otherwise         of  a  subject string or after any newline within the string. Otherwise
2670         -2 is returned. For anchored patterns, -2 is returned.         -2 is returned. For anchored patterns, -2 is returned.
2671    
2672           Since for the 32-bit library using the non-UTF-32 mode,  this  function
2673           is  unable to return the full 32-bit range of the character, this value
2674           is   deprecated;   instead   the   PCRE_INFO_FIRSTCHARACTERFLAGS    and
2675           PCRE_INFO_FIRSTCHARACTER values should be used.
2676    
2677           PCRE_INFO_FIRSTTABLE           PCRE_INFO_FIRSTTABLE
2678    
2679         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
2680         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
2681         matching string, a pointer to the table is returned. Otherwise NULL  is         in  any  matching string, a pointer to the table is returned. Otherwise
2682         returned.  The fourth argument should point to an unsigned char * vari-         NULL is returned. The fourth argument should point to an unsigned  char
2683         able.         * variable.
2684    
2685             PCRE_INFO_HASCRORLF
2686    
2687           Return  1  if  the  pattern  contains any explicit matches for CR or LF
2688           characters, otherwise 0. The fourth argument should  point  to  an  int
2689           variable.  An explicit match is either a literal CR or LF character, or
2690           \r or \n.
2691    
2692             PCRE_INFO_JCHANGED
2693    
2694           Return 1 if the (?J) or (?-J) option setting is used  in  the  pattern,
2695           otherwise  0. The fourth argument should point to an int variable. (?J)
2696           and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
2697    
2698             PCRE_INFO_JIT
2699    
2700           Return 1 if the pattern was studied with one of the  JIT  options,  and
2701           just-in-time compiling was successful. The fourth argument should point
2702           to an int variable. A return value of 0 means that JIT support  is  not
2703           available  in this version of PCRE, or that the pattern was not studied
2704           with a JIT option, or that the JIT compiler could not handle this  par-
2705           ticular  pattern. See the pcrejit documentation for details of what can
2706           and cannot be handled.
2707    
2708             PCRE_INFO_JITSIZE
2709    
2710           If the pattern was successfully studied with a JIT option,  return  the
2711           size  of the JIT compiled code, otherwise return zero. The fourth argu-
2712           ment should point to a size_t variable.
2713    
2714           PCRE_INFO_LASTLITERAL           PCRE_INFO_LASTLITERAL
2715    
2716         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
2717         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
2718         recorded. The fourth argument should point to an int variable. If there         recorded. The fourth argument should point to an int variable. If there
2719         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
2720         byte is recorded only if it follows something of variable  length.  For         value is recorded only if it follows something of variable length.  For
2721         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
2722         /^a\dz\d/ the returned value is -1.         /^a\dz\d/ the returned value is -1.
2723    
2724           Since for the 32-bit library using the non-UTF-32 mode,  this  function
2725           is  unable to return the full 32-bit range of the character, this value
2726           is   deprecated;   instead    the    PCRE_INFO_REQUIREDCHARFLAGS    and
2727           PCRE_INFO_REQUIREDCHAR values should be used.
2728    
2729             PCRE_INFO_MATCHLIMIT
2730    
2731           If  the  pattern  set  a  match  limit by including an item of the form
2732           (*LIMIT_MATCH=nnnn) at the start, the value  is  returned.  The  fourth
2733           argument  should  point to an unsigned 32-bit integer. If no such value
2734           has  been  set,  the  call  to  pcre_fullinfo()   returns   the   error
2735           PCRE_ERROR_UNSET.
2736    
2737             PCRE_INFO_MAXLOOKBEHIND
2738    
2739           Return  the  number of characters (NB not bytes) in the longest lookbe-
2740           hind assertion in the pattern. This information is  useful  when  doing
2741           multi-segment matching using the partial matching facilities. Note that
2742           the simple assertions \b and \B require a one-character lookbehind.  \A
2743           also  registers a one-character lookbehind, though it does not actually
2744           inspect the previous character. This is to ensure  that  at  least  one
2745           character  from  the old segment is retained when a new segment is pro-
2746           cessed. Otherwise, if there are no lookbehinds in the pattern, \A might
2747           match incorrectly at the start of a new segment.
2748    
2749             PCRE_INFO_MINLENGTH
2750    
2751           If  the  pattern  was studied and a minimum length for matching subject
2752           strings was computed, its value is  returned.  Otherwise  the  returned
2753           value  is  -1. The value is a number of characters, which in UTF-8 mode
2754           may be different from the number of bytes. The fourth  argument  should
2755           point  to an int variable. A non-negative value is a lower bound to the
2756           length of any matching string. There may not be  any  strings  of  that
2757           length  that  do actually match, but every string that does match is at
2758           least that long.
2759    
2760           PCRE_INFO_NAMECOUNT           PCRE_INFO_NAMECOUNT
2761           PCRE_INFO_NAMEENTRYSIZE           PCRE_INFO_NAMEENTRYSIZE
2762           PCRE_INFO_NAMETABLE           PCRE_INFO_NAMETABLE
2763    
2764         PCRE supports the use of named as well as numbered capturing  parenthe-         PCRE supports the use of named as well as numbered capturing  parenthe-
2765         ses.  The names are just an additional way of identifying the parenthe-         ses.  The names are just an additional way of identifying the parenthe-
2766         ses,  which  still  acquire  numbers.  A  convenience  function  called         ses, which still acquire numbers. Several convenience functions such as
2767         pcre_get_named_substring()  is  provided  for  extracting an individual         pcre_get_named_substring()  are  provided  for extracting captured sub-
2768         captured substring by name. It is also possible  to  extract  the  data         strings by name. It is also possible to extract the data  directly,  by
2769         directly,  by  first converting the name to a number in order to access         first  converting  the  name to a number in order to access the correct
2770         the correct pointers in the output vector (described  with  pcre_exec()         pointers in the output vector (described with pcre_exec() below). To do
2771         below).  To  do the conversion, you need to use the name-to-number map,         the  conversion,  you  need  to  use  the  name-to-number map, which is
2772         which is described by these three values.         described by these three values.
2773    
2774         The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT         The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT
2775         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size
2776         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
2777         depends  on the length of the longest name. PCRE_INFO_NAMETABLE returns         depends  on the length of the longest name. PCRE_INFO_NAMETABLE returns
2778         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
2779         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-
2780         sis, most significant byte first. The rest of the entry is  the  corre-         ber of the capturing parenthesis, most significant byte first.  In  the
2781         sponding  name,  zero  terminated. The names are in alphabetical order.         16-bit  library,  the pointer points to 16-bit data units, the first of
2782         For example, consider the following pattern  (assume  PCRE_EXTENDED  is         which contains the parenthesis number.   In  the  32-bit  library,  the
2783           pointer  points  to  32-bit data units, the first of which contains the
2784           parenthesis number. The rest of the entry is  the  corresponding  name,
2785           zero terminated.
2786    
2787           The  names are in alphabetical order. Duplicate names may appear if (?|
2788           is used to create multiple groups with the same number, as described in
2789           the  section  on  duplicate subpattern numbers in the pcrepattern page.
2790           Duplicate names for subpatterns with different  numbers  are  permitted
2791           only  if  PCRE_DUPNAMES  is  set. In all cases of duplicate names, they
2792           appear in the table in the order in which they were found in  the  pat-
2793           tern.  In  the  absence  of (?| this is the order of increasing number;
2794           when (?| is used this is not necessarily the case because later subpat-
2795           terns may have lower numbers.
2796    
2797           As  a  simple  example of the name/number table, consider the following
2798           pattern after compilation by the 8-bit library (assume PCRE_EXTENDED is
2799         set, so white space - including newlines - is ignored):         set, so white space - including newlines - is ignored):
2800    
2801           (?P<date> (?P<year>(\d\d)?\d\d) -           (?<date> (?<year>(\d\d)?\d\d) -
2802           (?P<month>\d\d) - (?P<day>\d\d) )           (?<month>\d\d) - (?<day>\d\d) )
2803    
2804         There  are  four  named subpatterns, so the table has four entries, and         There  are  four  named subpatterns, so the table has four entries, and
2805         each entry in the table is eight bytes long. The table is  as  follows,         each entry in the table is eight bytes long. The table is  as  follows,
# Line 1307  INFORMATION ABOUT A PATTERN Line 2812  INFORMATION ABOUT A PATTERN
2812           00 02 y  e  a  r  00 ??           00 02 y  e  a  r  00 ??
2813    
2814         When writing code to extract data  from  named  subpatterns  using  the         When writing code to extract data  from  named  subpatterns  using  the
2815         name-to-number map, remember that the length of each entry is likely to         name-to-number  map,  remember that the length of the entries is likely
2816         be different for each compiled pattern.         to be different for each compiled pattern.
2817    
2818             PCRE_INFO_OKPARTIAL
2819    
2820           Return 1  if  the  pattern  can  be  used  for  partial  matching  with
2821           pcre_exec(),  otherwise  0.  The fourth argument should point to an int
2822           variable. From  release  8.00,  this  always  returns  1,  because  the
2823           restrictions  that  previously  applied  to  partial matching have been
2824           lifted. The pcrepartial documentation gives details of  partial  match-
2825           ing.
2826    
2827           PCRE_INFO_OPTIONS           PCRE_INFO_OPTIONS
2828    
2829         Return a copy of the options with which the pattern was  compiled.  The         Return  a  copy of the options with which the pattern was compiled. The
2830         fourth  argument  should  point to an unsigned long int variable. These         fourth argument should point to an unsigned long  int  variable.  These
2831         option bits are those specified in the call to pcre_compile(), modified         option bits are those specified in the call to pcre_compile(), modified
2832         by any top-level option settings within the pattern itself.         by any top-level option settings at the start of the pattern itself. In
2833           other  words,  they are the options that will be in force when matching
2834           starts. For example, if the pattern /(?im)abc(?-i)d/ is  compiled  with
2835           the  PCRE_EXTENDED option, the result is PCRE_CASELESS, PCRE_MULTILINE,
2836           and PCRE_EXTENDED.
2837    
2838         A  pattern  is  automatically  anchored by PCRE if all of its top-level         A pattern is automatically anchored by PCRE if  all  of  its  top-level
2839         alternatives begin with one of the following:         alternatives begin with one of the following:
2840    
2841           ^     unless PCRE_MULTILINE is set           ^     unless PCRE_MULTILINE is set
# Line 1329  INFORMATION ABOUT A PATTERN Line 2847  INFORMATION ABOUT A PATTERN
2847         For such patterns, the PCRE_ANCHORED bit is set in the options returned         For such patterns, the PCRE_ANCHORED bit is set in the options returned
2848         by pcre_fullinfo().         by pcre_fullinfo().
2849    
2850             PCRE_INFO_RECURSIONLIMIT
2851    
2852           If the pattern set a recursion limit by including an item of  the  form
2853           (*LIMIT_RECURSION=nnnn) at the start, the value is returned. The fourth
2854           argument should point to an unsigned 32-bit integer. If no  such  value
2855           has   been   set,   the  call  to  pcre_fullinfo()  returns  the  error
2856           PCRE_ERROR_UNSET.
2857    
2858           PCRE_INFO_SIZE           PCRE_INFO_SIZE
2859    
2860         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).
2861         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
2862         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
2863         size_t variable.         pcre_compile().  The  value that is passed as the argument to pcre_mal-
2864           loc() when pcre_compile() is getting memory in which to place the  com-
2865           piled  data  is  the value returned by this option plus the size of the
2866           pcre structure. Studying a compiled pattern, with or without JIT,  does
2867           not alter the value returned by this option.
2868    
2869           PCRE_INFO_STUDYSIZE           PCRE_INFO_STUDYSIZE
2870    
2871         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
2872         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
2873         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
2874         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
2875           information  that  will  speed  up  matching  (see the section entitled
2876           "Studying a pattern" above). The format of the study_data block is pri-
2877           vate,  but  its length is made available via this option so that it can
2878           be  saved  and  restored  (see  the  pcreprecompile  documentation  for
2879           details).
2880    
2881             PCRE_INFO_FIRSTCHARACTERFLAGS
2882    
2883           Return information about the first data unit of any matched string, for
2884           a non-anchored pattern. The fourth argument  should  point  to  an  int
2885         variable.         variable.
2886    
2887           If  there  is  a  fixed first value, for example, the letter "c" from a
2888           pattern such as (cat|cow|coyote), 1  is  returned,  and  the  character
2889           value can be retrieved using PCRE_INFO_FIRSTCHARACTER.
2890    
2891           If there is no fixed first value, and if either
2892    
2893           (a)  the pattern was compiled with the PCRE_MULTILINE option, and every
2894           branch starts with "^", or
2895    
2896           (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2897           set (if it were set, the pattern would be anchored),
2898    
2899           2 is returned, indicating that the pattern matches only at the start of
2900           a subject string or after any newline within the string. Otherwise 0 is
2901           returned. For anchored patterns, 0 is returned.
2902    
2903             PCRE_INFO_FIRSTCHARACTER
2904    
2905           Return  the  fixed  first character value, if PCRE_INFO_FIRSTCHARACTER-
2906           FLAGS returned 1; otherwise returns 0. The fourth argument should point
2907           to an uint_t variable.
2908    
2909           In  the 8-bit library, the value is always less than 256. In the 16-bit
2910           library the value can be up to 0xffff. In the 32-bit library in  UTF-32
2911           mode  the  value  can  be up to 0x10ffff, and up to 0xffffffff when not
2912           using UTF-32 mode.
2913    
2914           If there is no fixed first value, and if either
2915    
2916           (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
2917           branch starts with "^", or
2918    
2919           (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2920           set (if it were set, the pattern would be anchored),
2921    
2922  OBSOLETE INFO FUNCTION         -1 is returned, indicating that the pattern matches only at  the  start
2923           of  a  subject string or after any newline within the string. Otherwise
2924           -2 is returned. For anchored patterns, -2 is returned.
2925    
2926         int pcre_info(const pcre *code, int *optptr, int *firstcharptr);           PCRE_INFO_REQUIREDCHARFLAGS
2927    
2928         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
2929         restrictive  to return all the available data about a compiled pattern.         any matched string, other than at its start. The fourth argument should
2930         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
2931         pcre_info()  is the number of capturing subpatterns, or one of the fol-         returning  1,  the  character  value  itself  can  be  retrieved  using
2932         lowing negative numbers:         PCRE_INFO_REQUIREDCHAR.
2933    
2934           PCRE_ERROR_NULL       the argument code was NULL         For anchored patterns, a last literal value is recorded only if it fol-
2935           PCRE_ERROR_BADMAGIC   the "magic number" was not found         lows  something  of  variable  length.  For  example,  for  the pattern
2936           /^a\d+z\d+/  the   returned   value   1   (with   "z"   returned   from
2937         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.
2938         the  pattern  was  compiled  is placed in the integer it points to (see  
2939         PCRE_INFO_OPTIONS above).           PCRE_INFO_REQUIREDCHAR
2940    
2941         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
2942         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
2943         any matched string (see PCRE_INFO_FIRSTBYTE above).         recorded.  The fourth argument should point to an uint32_t variable. If
2944           there is no such value, 0 is returned.
2945    
2946    
2947  REFERENCE COUNTS  REFERENCE COUNTS
# Line 1395  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2972  MATCHING A PATTERN: THE TRADITIONAL FUNC
2972              const char *subject, int length, int startoffset,              const char *subject, int length, int startoffset,
2973              int options, int *ovector, int ovecsize);              int options, int *ovector, int ovecsize);
2974    
2975         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
2976         compiled  pattern, which is passed in the code argument. If the pattern         compiled pattern, which is passed in the code argument. If the  pattern
2977         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
2978         argument.  This  function is the main matching facility of the library,         argument. You can call pcre_exec() with the same code and  extra  argu-
2979         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
2980         an  alternative matching function, which is described below in the sec-         strings with the same pattern.
2981         tion about the pcre_dfa_exec() function.  
2982           This function is the main matching facility  of  the  library,  and  it
2983           operates  in  a  Perl-like  manner. For specialist use there is also an
2984           alternative matching function, which is described below in the  section
2985           about the pcre_dfa_exec() function.
2986    
2987         In most applications, the pattern will have been compiled (and  option-         In  most applications, the pattern will have been compiled (and option-
2988         ally  studied)  in the same process that calls pcre_exec(). However, it         ally studied) in the same process that calls pcre_exec().  However,  it
2989         is possible to save compiled patterns and study data, and then use them         is possible to save compiled patterns and study data, and then use them
2990         later  in  different processes, possibly even on different hosts. For a         later in different processes, possibly even on different hosts.  For  a
2991         discussion about this, see the pcreprecompile documentation.         discussion about this, see the pcreprecompile documentation.
2992    
2993         Here is an example of a simple call to pcre_exec():         Here is an example of a simple call to pcre_exec():
# Line 1425  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3006  MATCHING A PATTERN: THE TRADITIONAL FUNC
3006    
3007     Extra data for pcre_exec()     Extra data for pcre_exec()
3008    
3009         If the extra argument is not NULL, it must point to a  pcre_extra  data         If  the  extra argument is not NULL, it must point to a pcre_extra data
3010         block.  The pcre_study() function returns such a block (when it doesn't         block. The pcre_study() function returns such a block (when it  doesn't
3011         return NULL), but you can also create one for yourself, and pass  addi-         return  NULL), but you can also create one for yourself, and pass addi-
3012         tional  information in it. The fields in a pcre_extra block are as fol-         tional information in it. The pcre_extra block contains  the  following
3013         lows:         fields (not necessarily in this order):
3014    
3015           unsigned long int flags;           unsigned long int flags;
3016           void *study_data;           void *study_data;
3017             void *executable_jit;
3018           unsigned long int match_limit;           unsigned long int match_limit;
3019             unsigned long int match_limit_recursion;
3020           void *callout_data;           void *callout_data;
3021           const unsigned char *tables;           const unsigned char *tables;
3022             unsigned char **mark;
3023    
3024         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
3025         are set. The flag bits are:         "PCRE_UCHAR16 **".
3026    
3027           In the 32-bit version of  this  structure,  the  mark  field  has  type
3028           "PCRE_UCHAR32 **".
3029    
3030           The  flags  field is used to specify which of the other fields are set.
3031           The flag bits are:
3032    
          PCRE_EXTRA_STUDY_DATA  
          PCRE_EXTRA_MATCH_LIMIT  
3033           PCRE_EXTRA_CALLOUT_DATA           PCRE_EXTRA_CALLOUT_DATA
3034             PCRE_EXTRA_EXECUTABLE_JIT
3035             PCRE_EXTRA_MARK
3036             PCRE_EXTRA_MATCH_LIMIT
3037             PCRE_EXTRA_MATCH_LIMIT_RECURSION
3038             PCRE_EXTRA_STUDY_DATA
3039           PCRE_EXTRA_TABLES           PCRE_EXTRA_TABLES
3040    
3041         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-
3042         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
3043         the appropriate flag bit. You should not set this yourself, but you may         returned by pcre_study(), together with the appropriate flag bits.  You
3044         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
3045         flag bits.         other fields and their corresponding flag bits.
3046    
3047         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
3048         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
3049         match,  but  which  have  a very large number of possibilities in their         match, but which have a very large number  of  possibilities  in  their
3050         search trees. The classic  example  is  the  use  of  nested  unlimited         search  trees. The classic example is a pattern that uses nested unlim-
3051         repeats.         ited repeats.
3052    
3053         Internally,  PCRE uses a function called match() which it calls repeat-         Internally, pcre_exec() uses a function called match(), which it  calls
3054         edly (sometimes recursively). The limit is imposed  on  the  number  of         repeatedly  (sometimes  recursively).  The  limit set by match_limit is
3055         times  this  function is called during a match, which has the effect of         imposed on the number of times this function is called during a  match,
3056         limiting the amount of recursion and backtracking that can take  place.         which  has  the  effect of limiting the amount of backtracking that can
3057         For patterns that are not anchored, the count starts from zero for each         take place. For patterns that are not anchored, the count restarts from
3058         position in the subject string.         zero for each position in the subject string.
3059    
3060           When pcre_exec() is called with a pattern that was successfully studied
3061           with a JIT option, the way that the matching is  executed  is  entirely
3062           different.  However, there is still the possibility of runaway matching
3063           that goes on for a very long time, and so the match_limit value is also
3064           used in this case (but in a different way) to limit how long the match-
3065           ing can continue.
3066    
3067         The default limit for the library can be set when PCRE  is  built;  the         The default value for the limit can be set  when  PCRE  is  built;  the
3068         default  default  is 10 million, which handles all but the most extreme         default  default  is 10 million, which handles all but the most extreme
3069         cases. You can reduce  the  default  by  suppling  pcre_exec()  with  a         cases. You can override the default  by  suppling  pcre_exec()  with  a
3070         pcre_extra  block  in  which match_limit is set to a smaller value, and         pcre_extra     block    in    which    match_limit    is    set,    and
3071         PCRE_EXTRA_MATCH_LIMIT is set in the  flags  field.  If  the  limit  is         PCRE_EXTRA_MATCH_LIMIT is set in the  flags  field.  If  the  limit  is
3072         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
3073    
3074         The  pcre_callout  field is used in conjunction with the "callout" fea-         A  value  for  the  match  limit may also be supplied by an item at the
3075         ture, which is described in the pcrecallout documentation.         start of a pattern of the form
3076    
3077             (*LIMIT_MATCH=d)
3078    
3079         The tables field  is  used  to  pass  a  character  tables  pointer  to         where d is a decimal number. However, such a setting is ignored  unless
3080         pcre_exec();  this overrides the value that is stored with the compiled         d  is  less  than  the limit set by the caller of pcre_exec() or, if no
3081         pattern. A non-NULL value is stored with the compiled pattern  only  if         such limit is set, less than the default.
3082         custom  tables  were  supplied to pcre_compile() via its tableptr argu-  
3083           The match_limit_recursion field is similar to match_limit, but  instead
3084           of limiting the total number of times that match() is called, it limits
3085           the depth of recursion. The recursion depth is a  smaller  number  than
3086           the  total number of calls, because not all calls to match() are recur-
3087           sive.  This limit is of use only if it is set smaller than match_limit.
3088    
3089           Limiting the recursion depth limits the amount of  machine  stack  that
3090           can  be used, or, when PCRE has been compiled to use memory on the heap
3091           instead of the stack, the amount of heap memory that can be used.  This
3092           limit  is not relevant, and is ignored, when matching is done using JIT
3093           compiled code.
3094    
3095           The default value for match_limit_recursion can be  set  when  PCRE  is
3096           built;  the  default  default  is  the  same  value  as the default for
3097           match_limit. You can override the default by suppling pcre_exec()  with
3098           a   pcre_extra   block  in  which  match_limit_recursion  is  set,  and
3099           PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in  the  flags  field.  If  the
3100           limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.
3101    
3102           A  value for the recursion limit may also be supplied by an item at the
3103           start of a pattern of the form
3104    
3105             (*LIMIT_RECURSION=d)
3106    
3107           where d is a decimal number. However, such a setting is ignored  unless
3108           d  is  less  than  the limit set by the caller of pcre_exec() or, if no
3109           such limit is set, less than the default.
3110    
3111           The callout_data field is used in conjunction with the  "callout"  fea-
3112           ture, and is described in the pcrecallout documentation.
3113    
3114           The  tables  field  is  used  to  pass  a  character  tables pointer to
3115           pcre_exec(); this overrides the value that is stored with the  compiled
3116           pattern.  A  non-NULL value is stored with the compiled pattern only if
3117           custom tables were supplied to pcre_compile() via  its  tableptr  argu-
3118         ment.  If NULL is passed to pcre_exec() using this mechanism, it forces         ment.  If NULL is passed to pcre_exec() using this mechanism, it forces
3119         PCRE's  internal  tables  to be used. This facility is helpful when re-         PCRE's internal tables to be used. This facility is  helpful  when  re-
3120         using patterns that have been saved after compiling  with  an  external         using  patterns  that  have been saved after compiling with an external
3121         set  of  tables,  because  the  external tables might be at a different         set of tables, because the external tables  might  be  at  a  different
3122         address when pcre_exec() is called. See the  pcreprecompile  documenta-         address  when  pcre_exec() is called. See the pcreprecompile documenta-
3123         tion for a discussion of saving compiled patterns for later use.         tion for a discussion of saving compiled patterns for later use.
3124    
3125           If PCRE_EXTRA_MARK is set in the flags field, the mark  field  must  be
3126           set  to point to a suitable variable. If the pattern contains any back-
3127           tracking control verbs such as (*MARK:NAME), and the execution ends  up
3128           with  a  name  to  pass back, a pointer to the name string (zero termi-
3129           nated) is placed in the variable pointed to  by  the  mark  field.  The
3130           names  are  within  the  compiled pattern; if you wish to retain such a
3131           name you must copy it before freeing the memory of a compiled  pattern.
3132           If  there  is no name to pass back, the variable pointed to by the mark
3133           field is set to NULL. For details of the  backtracking  control  verbs,
3134           see the section entitled "Backtracking control" in the pcrepattern doc-
3135           umentation.
3136    
3137     Option bits for pcre_exec()     Option bits for pcre_exec()
3138    
3139         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.
3140         The  only  bits  that  may  be  set  are  PCRE_ANCHORED,   PCRE_NOTBOL,         The  only  bits  that  may  be set are PCRE_ANCHORED, PCRE_NEWLINE_xxx,
3141         PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.         PCRE_NOTBOL,   PCRE_NOTEOL,    PCRE_NOTEMPTY,    PCRE_NOTEMPTY_ATSTART,
3142           PCRE_NO_START_OPTIMIZE,   PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_HARD,  and
3143           PCRE_PARTIAL_SOFT.
3144    
3145           If the pattern was successfully studied with one  of  the  just-in-time
3146           (JIT) compile options, the only supported options for JIT execution are
3147           PCRE_NO_UTF8_CHECK,    PCRE_NOTBOL,     PCRE_NOTEOL,     PCRE_NOTEMPTY,
3148           PCRE_NOTEMPTY_ATSTART,  PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an
3149           unsupported option is used, JIT execution is disabled  and  the  normal
3150           interpretive code in pcre_exec() is run.
3151    
3152           PCRE_ANCHORED           PCRE_ANCHORED
3153    
# Line 1498  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3156  MATCHING A PATTERN: THE TRADITIONAL FUNC
3156         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
3157         unachored at matching time.         unachored at matching time.
3158    
3159             PCRE_BSR_ANYCRLF
3160             PCRE_BSR_UNICODE
3161    
3162           These options (which are mutually exclusive) control what the \R escape
3163           sequence  matches.  The choice is either to match only CR, LF, or CRLF,
3164           or to match any Unicode newline sequence. These  options  override  the
3165           choice that was made or defaulted when the pattern was compiled.
3166    
3167             PCRE_NEWLINE_CR
3168             PCRE_NEWLINE_LF
3169             PCRE_NEWLINE_CRLF
3170             PCRE_NEWLINE_ANYCRLF
3171             PCRE_NEWLINE_ANY
3172    
3173           These  options  override  the  newline  definition  that  was chosen or
3174           defaulted when the pattern was compiled. For details, see the  descrip-
3175           tion  of  pcre_compile()  above.  During  matching,  the newline choice
3176           affects the behaviour of the dot, circumflex,  and  dollar  metacharac-
3177           ters.  It may also alter the way the match position is advanced after a
3178           match failure for an unanchored pattern.
3179    
3180           When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF,  or  PCRE_NEWLINE_ANY  is
3181           set,  and a match attempt for an unanchored pattern fails when the cur-
3182           rent position is at a  CRLF  sequence,  and  the  pattern  contains  no
3183           explicit  matches  for  CR  or  LF  characters,  the  match position is
3184           advanced by two characters instead of one, in other words, to after the
3185           CRLF.
3186    
3187           The above rule is a compromise that makes the most common cases work as
3188           expected. For example, if the  pattern  is  .+A  (and  the  PCRE_DOTALL
3189           option is not set), it does not match the string "\r\nA" because, after
3190           failing at the start, it skips both the CR and the LF before  retrying.
3191           However,  the  pattern  [\r\n]A does match that string, because it con-
3192           tains an explicit CR or LF reference, and so advances only by one char-
3193           acter after the first failure.
3194    
3195           An explicit match for CR of LF is either a literal appearance of one of
3196           those characters, or one of the \r or  \n  escape  sequences.  Implicit
3197           matches  such  as [^X] do not count, nor does \s (which includes CR and
3198           LF in the characters that it matches).
3199    
3200           Notwithstanding the above, anomalous effects may still occur when  CRLF
3201           is a valid newline sequence and explicit \r or \n escapes appear in the
3202           pattern.
3203    
3204           PCRE_NOTBOL           PCRE_NOTBOL