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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. (Certain features that appeared in Python and         just  a few differences. Some features that appeared in Python and PCRE
23         PCRE before they appeared in Perl are also available using  the  Python         before they appeared in Perl are also available using the  Python  syn-
24         syntax.)         tax,  there  is  some  support for one or two .NET and Oniguruma syntax
25           items, and there is an option for requesting some  minor  changes  that
26         The  current  implementation of PCRE (release 7.x) corresponds approxi-         give better JavaScript compatibility.
27         mately with Perl 5.10, including support for UTF-8 encoded strings  and  
28         Unicode general category properties. However, UTF-8 and Unicode support         Starting with release 8.30, it is possible to compile two separate PCRE
29           libraries:  the  original,  which  supports  8-bit  character   strings
30           (including  UTF-8  strings),  and a second library that supports 16-bit
31           character strings (including UTF-16 strings). The build process  allows
32           either  one  or both to be built. The majority of the work to make this
33           possible was done by Zoltan Herczeg.
34    
35           Starting with release 8.32 it is possible to compile a  third  separate
36           PCRE  library  that supports 32-bit character strings (including UTF-32
37           strings). The build process allows any combination of the 8-,  16-  and
38           32-bit  libraries. The work to make this possible was done by Christian
39           Persch.
40    
41           The three libraries contain identical sets of  functions,  except  that
42           the  names  in  the 16-bit library start with pcre16_ instead of pcre_,
43           and the names in the 32-bit  library  start  with  pcre32_  instead  of
44           pcre_.  To avoid over-complication and reduce the documentation mainte-
45           nance load, most of the documentation describes the 8-bit library, with
46           the  differences  for  the  16-bit and 32-bit libraries described sepa-
47           rately in the pcre16 and  pcre32  pages.  References  to  functions  or
48           structures  of  the  form  pcre[16|32]_xxx  should  be  read as meaning
49           "pcre_xxx when using the  8-bit  library,  pcre16_xxx  when  using  the
50           16-bit library, or pcre32_xxx when using the 32-bit library".
51    
52           The  current implementation of PCRE corresponds approximately with Perl
53           5.12, including support for UTF-8/16/32  encoded  strings  and  Unicode
54           general  category  properties. However, UTF-8/16/32 and Unicode support
55         has to be explicitly enabled; it is not the default. The Unicode tables         has to be explicitly enabled; it is not the default. The Unicode tables
56         correspond to Unicode release 5.0.0.         correspond to Unicode release 6.3.0.
57    
58         In  addition to the Perl-compatible matching function, PCRE contains an         In  addition to the Perl-compatible matching function, PCRE contains an
59         alternative matching function that matches the same  compiled  patterns         alternative function that matches the same compiled patterns in a  dif-
60         in  a different way. In certain circumstances, the alternative function         ferent way. In certain circumstances, the alternative function has some
61         has some advantages. For a discussion of the two  matching  algorithms,         advantages.  For a discussion of the two matching algorithms,  see  the
62         see the pcrematching page.         pcrematching page.
63    
64         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
65         have written wrappers and interfaces of various kinds.  In  particular,         have written wrappers and interfaces of various kinds.  In  particular,
66         Google  Inc.   have  provided  a comprehensive C++ wrapper. This is now         Google  Inc.   have  provided a comprehensive C++ wrapper for the 8-bit
67         included as part of the PCRE distribution. The pcrecpp page has details         library. This is now included as part of  the  PCRE  distribution.  The
68         of  this  interface.  Other  people's contributions can be found in the         pcrecpp  page  has  details of this interface. Other people's contribu-
69         Contrib directory at the primary FTP site, which is:         tions can be found in the Contrib directory at the  primary  FTP  site,
70           which is:
71    
72         ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre         ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre
73    
74         Details of exactly which Perl regular expression features are  and  are         Details  of  exactly which Perl regular expression features are and are
75         not supported by PCRE are given in separate documents. See the pcrepat-         not supported by PCRE are given in separate documents. See the pcrepat-
76         tern and pcrecompat pages.         tern  and pcrecompat pages. There is a syntax summary in the pcresyntax
77           page.
78    
79         Some features of PCRE can be included, excluded, or  changed  when  the         Some features of PCRE can be included, excluded, or  changed  when  the
80         library  is  built.  The pcre_config() function makes it possible for a         library  is  built.  The pcre_config() function makes it possible for a
81         client to discover which features are  available.  The  features  them-         client to discover which features are  available.  The  features  them-
82         selves  are described in the pcrebuild page. Documentation about build-         selves  are described in the pcrebuild page. Documentation about build-
83         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
84         in the source distribution.         NON-AUTOTOOLS_BUILD files in the source distribution.
85    
86         The  library  contains  a number of undocumented internal functions and         The  libraries contains a number of undocumented internal functions and
87         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
88         functions,  but  which  are  not  intended for use by external callers.         functions,  but  which  are  not  intended for use by external callers.
89         Their names all begin with "_pcre_", which hopefully will  not  provoke         Their names all begin with "_pcre_" or "_pcre16_" or "_pcre32_",  which
90         any name clashes. In some environments, it is possible to control which         hopefully  will  not provoke any name clashes. In some environments, it
91         external symbols are exported when a shared library is  built,  and  in         is possible to control which  external  symbols  are  exported  when  a
92         these cases the undocumented symbols are not exported.         shared  library  is  built, and in these cases the undocumented symbols
93           are not exported.
94    
95    
96    SECURITY CONSIDERATIONS
97    
98           If you are using PCRE in a non-UTF application that  permits  users  to
99           supply  arbitrary  patterns  for  compilation, you should be aware of a
100           feature that allows users to turn on UTF support from within a pattern,
101           provided  that  PCRE  was built with UTF support. For example, an 8-bit
102           pattern that begins with "(*UTF8)" or "(*UTF)"  turns  on  UTF-8  mode,
103           which  interprets  patterns and subjects as strings of UTF-8 characters
104           instead of individual 8-bit characters.  This causes both  the  pattern
105           and any data against which it is matched to be checked for UTF-8 valid-
106           ity. If the data string is very long, such a  check  might  use  suffi-
107           ciently  many  resources  as  to cause your application to lose perfor-
108           mance.
109    
110           One  way  of  guarding  against  this  possibility  is   to   use   the
111           pcre_fullinfo()  function  to  check the compiled pattern's options for
112           UTF.  Alternatively, from release 8.33, you can set the  PCRE_NEVER_UTF
113           option  at compile time. This causes an compile time error if a pattern
114           contains a UTF-setting sequence.
115    
116           If your application is one that supports UTF, be  aware  that  validity
117           checking  can  take time. If the same data string is to be matched many
118           times, you can use the PCRE_NO_UTF[8|16|32]_CHECK option for the second
119           and subsequent matches to save redundant checks.
120    
121           Another  way  that  performance can be hit is by running a pattern that
122           has a very large search tree against a string that  will  never  match.
123           Nested  unlimited  repeats in a pattern are a common example. PCRE pro-
124           vides some protection against this: see the PCRE_EXTRA_MATCH_LIMIT fea-
125           ture in the pcreapi page.
126    
127    
128  USER DOCUMENTATION  USER DOCUMENTATION
# Line 68  USER DOCUMENTATION Line 130  USER DOCUMENTATION
130         The  user  documentation  for PCRE comprises a number of different sec-         The  user  documentation  for PCRE comprises a number of different sec-
131         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
132         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.
133         In the plain text format, all the sections are concatenated,  for  ease         In the plain text format, all the sections, except  the  pcredemo  sec-
134         of searching. The sections are as follows:         tion, are concatenated, for ease of searching. The sections are as fol-
135           lows:
136    
137           pcre              this document           pcre              this document
138           pcre-config       show PCRE installation configuration information           pcre-config       show PCRE installation configuration information
139             pcre16            details of the 16-bit library
140             pcre32            details of the 32-bit library
141           pcreapi           details of PCRE's native C API           pcreapi           details of PCRE's native C API
142           pcrebuild         options for building PCRE           pcrebuild         building PCRE
143           pcrecallout       details of the callout feature           pcrecallout       details of the callout feature
144           pcrecompat        discussion of Perl compatibility           pcrecompat        discussion of Perl compatibility
145           pcrecpp           details of the C++ wrapper           pcrecpp           details of the C++ wrapper for the 8-bit library
146           pcregrep          description of the pcregrep command           pcredemo          a demonstration C program that uses PCRE
147             pcregrep          description of the pcregrep command (8-bit only)
148             pcrejit           discussion of the just-in-time optimization support
149             pcrelimits        details of size and other limits
150           pcrematching      discussion of the two matching algorithms           pcrematching      discussion of the two matching algorithms
151           pcrepartial       details of the partial matching facility           pcrepartial       details of the partial matching facility
152           pcrepattern       syntax and semantics of supported           pcrepattern       syntax and semantics of supported
153                               regular expressions                               regular expressions
154           pcreperform       discussion of performance issues           pcreperform       discussion of performance issues
155           pcreposix         the POSIX-compatible C API           pcreposix         the POSIX-compatible C API for the 8-bit library
156           pcreprecompile    details of saving and re-using precompiled patterns           pcreprecompile    details of saving and re-using precompiled patterns
157           pcresample        discussion of the sample program           pcresample        discussion of the pcredemo program
158           pcrestack         discussion of stack usage           pcrestack         discussion of stack usage
159             pcresyntax        quick syntax reference
160           pcretest          description of the pcretest testing command           pcretest          description of the pcretest testing command
161             pcreunicode       discussion of Unicode and UTF-8/16/32 support
162    
163         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
164         each C library function, listing its arguments and results.         each C library function, listing its arguments and results.
165    
166    
167  LIMITATIONS  AUTHOR
168    
169         There  are some size limitations in PCRE but it is hoped that they will         Philip Hazel
170         never in practice be relevant.         University Computing Service
171           Cambridge CB2 3QH, England.
172    
173         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,
174         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,
175         process regular expressions that are truly enormous,  you  can  compile         followed by the two digits 10, at the domain cam.ac.uk.
        PCRE  with  an  internal linkage size of 3 or 4 (see the README file in  
        the source distribution and the pcrebuild documentation  for  details).  
        In  these  cases the limit is substantially larger.  However, the speed  
        of execution is slower.  
   
        All values in repeating quantifiers must be less than 65536. The  maxi-  
        mum  compiled  length  of  subpattern  with an explicit repeat count is  
        30000 bytes. The maximum number of capturing subpatterns is 65535.  
176    
        There is no limit to the number of parenthesized subpatterns, but there  
        can be no more than 65535 capturing subpatterns.  
177    
178         The maximum length of name for a named subpattern is 32 characters, and  REVISION
        the maximum number of named subpatterns is 10000.  
179    
180         The maximum length of a subject string is the largest  positive  number         Last updated: 13 May 2013
181         that  an integer variable can hold. However, when using the traditional         Copyright (c) 1997-2013 University of Cambridge.
182         matching function, PCRE uses recursion to handle subpatterns and indef-  ------------------------------------------------------------------------------
        inite  repetition.  This means that the available stack space may limit  
        the size of a subject string that can be processed by certain patterns.  
        For a discussion of stack issues, see the pcrestack documentation.  
183    
184    
185  UTF-8 AND UNICODE PROPERTY SUPPORT  PCRE(3)                    Library Functions Manual                    PCRE(3)
186    
        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.  
187    
        If you compile PCRE with UTF-8 support, but do not use it at run  time,  
        the  library will be a bit bigger, but the additional run time overhead  
        is limited to testing the PCRE_UTF8 flag occasionally, so should not be  
        very big.  
188    
189         If PCRE is built with Unicode character property support (which implies  NAME
190         UTF-8 support), the escape sequences \p{..}, \P{..}, and  \X  are  sup-         PCRE - Perl-compatible regular expressions
191         ported.  The available properties that can be tested are limited to the  
192         general category properties such as Lu for an upper case letter  or  Nd         #include <pcre.h>
193         for  a  decimal number, the Unicode script names such as Arabic or Han,  
194         and the derived properties Any and L&. A full  list  is  given  in  the  
195         pcrepattern documentation. Only the short names for properties are sup-  PCRE 16-BIT API BASIC FUNCTIONS
196         ported. For example, \p{L} matches a letter. Its Perl synonym,  \p{Let-  
197         ter},  is  not  supported.   Furthermore,  in Perl, many properties may         pcre16 *pcre16_compile(PCRE_SPTR16 pattern, int options,
198         optionally be prefixed by "Is", for compatibility with Perl  5.6.  PCRE              const char **errptr, int *erroffset,
199         does not support this.              const unsigned char *tableptr);
200    
201         The following comments apply when PCRE is running in UTF-8 mode:         pcre16 *pcre16_compile2(PCRE_SPTR16 pattern, int options,
202                int *errorcodeptr,
203         1.  When you set the PCRE_UTF8 flag, the strings passed as patterns and              const char **errptr, int *erroffset,
204         subjects are checked for validity on entry to the  relevant  functions.              const unsigned char *tableptr);
205         If an invalid UTF-8 string is passed, an error return is given. In some  
206         situations, you may already know  that  your  strings  are  valid,  and         pcre16_extra *pcre16_study(const pcre16 *code, int options,
207         therefore want to skip these checks in order to improve performance. If              const char **errptr);
208         you set the PCRE_NO_UTF8_CHECK flag at compile time  or  at  run  time,  
209         PCRE  assumes  that  the  pattern or subject it is given (respectively)         void pcre16_free_study(pcre16_extra *extra);
210         contains only valid UTF-8 codes. In this case, it does not diagnose  an  
211         invalid  UTF-8 string. If you pass an invalid UTF-8 string to PCRE when         int pcre16_exec(const pcre16 *code, const pcre16_extra *extra,
212         PCRE_NO_UTF8_CHECK is set, the results are undefined. Your program  may              PCRE_SPTR16 subject, int length, int startoffset,
213         crash.              int options, int *ovector, int ovecsize);
214    
215         2.  An  unbraced  hexadecimal  escape sequence (such as \xb3) matches a         int pcre16_dfa_exec(const pcre16 *code, const pcre16_extra *extra,
216         two-byte UTF-8 character if the value is greater than 127.              PCRE_SPTR16 subject, int length, int startoffset,
217                int options, int *ovector, int ovecsize,
218         3. Octal numbers up to \777 are recognized, and  match  two-byte  UTF-8              int *workspace, int wscount);
219         characters for values greater than \177.  
220    
221         4.  Repeat quantifiers apply to complete UTF-8 characters, not to indi-  PCRE 16-BIT API STRING EXTRACTION FUNCTIONS
222         vidual bytes, for example: \x{100}{3}.  
223           int pcre16_copy_named_substring(const pcre16 *code,
224         5. The dot metacharacter matches one UTF-8 character instead of a  sin-              PCRE_SPTR16 subject, int *ovector,
225         gle byte.              int stringcount, PCRE_SPTR16 stringname,
226                PCRE_UCHAR16 *buffer, int buffersize);
227         6.  The  escape sequence \C can be used to match a single byte in UTF-8  
228         mode, but its use can lead to some strange effects.  This  facility  is         int pcre16_copy_substring(PCRE_SPTR16 subject, int *ovector,
229         not available in the alternative matching function, pcre_dfa_exec().              int stringcount, int stringnumber, PCRE_UCHAR16 *buffer,
230                int buffersize);
231         7.  The  character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly  
232         test characters of any code value, but the characters that PCRE  recog-         int pcre16_get_named_substring(const pcre16 *code,
233         nizes  as  digits,  spaces,  or  word characters remain the same set as              PCRE_SPTR16 subject, int *ovector,
234         before, all with values less than 256. This remains true even when PCRE              int stringcount, PCRE_SPTR16 stringname,
235         includes  Unicode  property support, because to do otherwise would slow              PCRE_SPTR16 *stringptr);
236         down PCRE in many common cases. If you really want to test for a  wider  
237         sense  of,  say,  "digit",  you must use Unicode property tests such as         int pcre16_get_stringnumber(const pcre16 *code,
238         \p{Nd}.              PCRE_SPTR16 name);
239    
240         8. Similarly, characters that match the POSIX named  character  classes         int pcre16_get_stringtable_entries(const pcre16 *code,
241         are all low-valued characters.              PCRE_SPTR16 name, PCRE_UCHAR16 **first, PCRE_UCHAR16 **last);
242    
243         9.  Case-insensitive  matching  applies only to characters whose values         int pcre16_get_substring(PCRE_SPTR16 subject, int *ovector,
244         are less than 128, unless PCRE is built with Unicode property  support.              int stringcount, int stringnumber,
245         Even  when  Unicode  property support is available, PCRE still uses its              PCRE_SPTR16 *stringptr);
246         own character tables when checking the case of  low-valued  characters,  
247         so  as not to degrade performance.  The Unicode property information is         int pcre16_get_substring_list(PCRE_SPTR16 subject,
248         used only for characters with higher values. Even when Unicode property              int *ovector, int stringcount, PCRE_SPTR16 **listptr);
249         support is available, PCRE supports case-insensitive matching only when  
250         there is a one-to-one mapping between a letter's  cases.  There  are  a         void pcre16_free_substring(PCRE_SPTR16 stringptr);
251         small  number  of  many-to-one  mappings in Unicode; these are not sup-  
252         ported by PCRE.         void pcre16_free_substring_list(PCRE_SPTR16 *stringptr);
253    
254    
255    PCRE 16-BIT API AUXILIARY FUNCTIONS
256    
257           pcre16_jit_stack *pcre16_jit_stack_alloc(int startsize, int maxsize);
258    
259           void pcre16_jit_stack_free(pcre16_jit_stack *stack);
260    
261           void pcre16_assign_jit_stack(pcre16_extra *extra,
262                pcre16_jit_callback callback, void *data);
263    
264           const unsigned char *pcre16_maketables(void);
265    
266           int pcre16_fullinfo(const pcre16 *code, const pcre16_extra *extra,
267                int what, void *where);
268    
269           int pcre16_refcount(pcre16 *code, int adjust);
270    
271           int pcre16_config(int what, void *where);
272    
273           const char *pcre16_version(void);
274    
275           int pcre16_pattern_to_host_byte_order(pcre16 *code,
276                pcre16_extra *extra, const unsigned char *tables);
277    
278    
279    PCRE 16-BIT API INDIRECTED FUNCTIONS
280    
281           void *(*pcre16_malloc)(size_t);
282    
283           void (*pcre16_free)(void *);
284    
285           void *(*pcre16_stack_malloc)(size_t);
286    
287           void (*pcre16_stack_free)(void *);
288    
289           int (*pcre16_callout)(pcre16_callout_block *);
290    
291    
292    PCRE 16-BIT API 16-BIT-ONLY FUNCTION
293    
294           int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *output,
295                PCRE_SPTR16 input, int length, int *byte_order,
296                int keep_boms);
297    
298    
299    THE PCRE 16-BIT LIBRARY
300    
301           Starting  with  release  8.30, it is possible to compile a PCRE library
302           that supports 16-bit character strings, including  UTF-16  strings,  as
303           well  as  or instead of the original 8-bit library. The majority of the
304           work to make  this  possible  was  done  by  Zoltan  Herczeg.  The  two
305           libraries contain identical sets of functions, used in exactly the same
306           way. Only the names of the functions and the data types of their  argu-
307           ments  and results are different. To avoid over-complication and reduce
308           the documentation maintenance load,  most  of  the  PCRE  documentation
309           describes  the  8-bit  library,  with only occasional references to the
310           16-bit library. This page describes what is different when you use  the
311           16-bit library.
312    
313           WARNING:  A  single  application can be linked with both libraries, but
314           you must take care when processing any particular pattern to use  func-
315           tions  from  just one library. For example, if you want to study a pat-
316           tern that was compiled with  pcre16_compile(),  you  must  do  so  with
317           pcre16_study(), not pcre_study(), and you must free the study data with
318           pcre16_free_study().
319    
320    
321    THE HEADER FILE
322    
323           There is only one header file, pcre.h. It contains prototypes  for  all
324           the functions in all libraries, as well as definitions of flags, struc-
325           tures, error codes, etc.
326    
327    
328    THE LIBRARY NAME
329    
330           In Unix-like systems, the 16-bit library is called libpcre16,  and  can
331           normally  be  accesss  by adding -lpcre16 to the command for linking an
332           application that uses PCRE.
333    
334    
335    STRING TYPES
336    
337           In the 8-bit library, strings are passed to PCRE library  functions  as
338           vectors  of  bytes  with  the  C  type "char *". In the 16-bit library,
339           strings are passed as vectors of unsigned 16-bit quantities. The  macro
340           PCRE_UCHAR16  specifies  an  appropriate  data type, and PCRE_SPTR16 is
341           defined as "const PCRE_UCHAR16 *". In very  many  environments,  "short
342           int" is a 16-bit data type. When PCRE is built, it defines PCRE_UCHAR16
343           as "unsigned short int", but checks that it really  is  a  16-bit  data
344           type.  If  it is not, the build fails with an error message telling the
345           maintainer to modify the definition appropriately.
346    
347    
348    STRUCTURE TYPES
349    
350           The types of the opaque structures that are used  for  compiled  16-bit
351           patterns  and  JIT stacks are pcre16 and pcre16_jit_stack respectively.
352           The  type  of  the  user-accessible  structure  that  is  returned   by
353           pcre16_study()  is  pcre16_extra, and the type of the structure that is
354           used for passing data to a callout  function  is  pcre16_callout_block.
355           These structures contain the same fields, with the same names, as their
356           8-bit counterparts. The only difference is that pointers  to  character
357           strings are 16-bit instead of 8-bit types.
358    
359    
360    16-BIT FUNCTIONS
361    
362           For  every function in the 8-bit library there is a corresponding func-
363           tion in the 16-bit library with a name that starts with pcre16_ instead
364           of  pcre_.  The  prototypes are listed above. In addition, there is one
365           extra function, pcre16_utf16_to_host_byte_order(). This  is  a  utility
366           function  that converts a UTF-16 character string to host byte order if
367           necessary. The other 16-bit  functions  expect  the  strings  they  are
368           passed to be in host byte order.
369    
370           The input and output arguments of pcre16_utf16_to_host_byte_order() may
371           point to the same address, that is, conversion in place  is  supported.
372           The output buffer must be at least as long as the input.
373    
374           The  length  argument  specifies the number of 16-bit data units in the
375           input string; a negative value specifies a zero-terminated string.
376    
377           If byte_order is NULL, it is assumed that the string starts off in host
378           byte  order. This may be changed by byte-order marks (BOMs) anywhere in
379           the string (commonly as the first character).
380    
381           If byte_order is not NULL, a non-zero value of the integer to which  it
382           points  means  that  the input starts off in host byte order, otherwise
383           the opposite order is assumed. Again, BOMs in  the  string  can  change
384           this. The final byte order is passed back at the end of processing.
385    
386           If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
387           copied into the output string. Otherwise they are discarded.
388    
389           The result of the function is the number of 16-bit  units  placed  into
390           the  output  buffer,  including  the  zero terminator if the string was
391           zero-terminated.
392    
393    
394    SUBJECT STRING OFFSETS
395    
396           The lengths and starting offsets of subject strings must  be  specified
397           in  16-bit  data units, and the offsets within subject strings that are
398           returned by the matching functions are in also 16-bit units rather than
399           bytes.
400    
401    
402    NAMED SUBPATTERNS
403    
404           The  name-to-number translation table that is maintained for named sub-
405           patterns uses 16-bit characters.  The  pcre16_get_stringtable_entries()
406           function returns the length of each entry in the table as the number of
407           16-bit data units.
408    
409    
410    OPTION NAMES
411    
412           There   are   two   new   general   option   names,   PCRE_UTF16    and
413           PCRE_NO_UTF16_CHECK,     which     correspond    to    PCRE_UTF8    and
414           PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
415           define  the  same bits in the options word. There is a discussion about
416           the validity of UTF-16 strings in the pcreunicode page.
417    
418           For the pcre16_config() function there is an  option  PCRE_CONFIG_UTF16
419           that  returns  1  if UTF-16 support is configured, otherwise 0. If this
420           option  is  given  to  pcre_config()  or  pcre32_config(),  or  if  the
421           PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF32  option is given to pcre16_con-
422           fig(), the result is the PCRE_ERROR_BADOPTION error.
423    
424    
425    CHARACTER CODES
426    
427           In 16-bit mode, when  PCRE_UTF16  is  not  set,  character  values  are
428           treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
429           that they can range from 0 to 0xffff instead of 0  to  0xff.  Character
430           types  for characters less than 0xff can therefore be influenced by the
431           locale in the same way as before.  Characters greater  than  0xff  have
432           only one case, and no "type" (such as letter or digit).
433    
434           In  UTF-16  mode,  the  character  code  is  Unicode, in the range 0 to
435           0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
436           because  those  are "surrogate" values that are used in pairs to encode
437           values greater than 0xffff.
438    
439           A UTF-16 string can indicate its endianness by special code knows as  a
440           byte-order mark (BOM). The PCRE functions do not handle this, expecting
441           strings  to  be  in  host  byte  order.  A  utility   function   called
442           pcre16_utf16_to_host_byte_order()  is  provided  to help with this (see
443           above).
444    
445    
446    ERROR NAMES
447    
448           The errors PCRE_ERROR_BADUTF16_OFFSET and PCRE_ERROR_SHORTUTF16  corre-
449           spond  to  their  8-bit  counterparts.  The error PCRE_ERROR_BADMODE is
450           given when a compiled pattern is passed to a  function  that  processes
451           patterns  in  the  other  mode, for example, if a pattern compiled with
452           pcre_compile() is passed to pcre16_exec().
453    
454           There are new error codes whose names  begin  with  PCRE_UTF16_ERR  for
455           invalid  UTF-16  strings,  corresponding to the PCRE_UTF8_ERR codes for
456           UTF-8 strings that are described in the section entitled "Reason  codes
457           for  invalid UTF-8 strings" in the main pcreapi page. The UTF-16 errors
458           are:
459    
460             PCRE_UTF16_ERR1  Missing low surrogate at end of string
461             PCRE_UTF16_ERR2  Invalid low surrogate follows high surrogate
462             PCRE_UTF16_ERR3  Isolated low surrogate
463             PCRE_UTF16_ERR4  Non-character
464    
465    
466    ERROR TEXTS
467    
468           If there is an error while compiling a pattern, the error text that  is
469           passed  back by pcre16_compile() or pcre16_compile2() is still an 8-bit
470           character string, zero-terminated.
471    
472    
473    CALLOUTS
474    
475           The subject and mark fields in the callout block that is  passed  to  a
476           callout function point to 16-bit vectors.
477    
478    
479    TESTING
480    
481           The  pcretest  program continues to operate with 8-bit input and output
482           files, but it can be used for testing the 16-bit library. If it is  run
483           with the command line option -16, patterns and subject strings are con-
484           verted from 8-bit to 16-bit before being passed to PCRE, and the 16-bit
485           library  functions  are used instead of the 8-bit ones. Returned 16-bit
486           strings are converted to 8-bit for output. If both the  8-bit  and  the
487           32-bit libraries were not compiled, pcretest defaults to 16-bit and the
488           -16 option is ignored.
489    
490           When PCRE is being built, the RunTest script that is  called  by  "make
491           check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
492           16-bit and 32-bit libraries has been built, and runs the  tests  appro-
493           priately.
494    
495    
496    NOT SUPPORTED IN 16-BIT MODE
497    
498           Not all the features of the 8-bit library are available with the 16-bit
499           library. The C++ and POSIX wrapper functions  support  only  the  8-bit
500           library, and the pcregrep program is at present 8-bit only.
501    
502    
503  AUTHOR  AUTHOR
# Line 215  AUTHOR Line 506  AUTHOR
506         University Computing Service         University Computing Service
507         Cambridge CB2 3QH, England.         Cambridge CB2 3QH, England.
508    
509         Putting an actual email address here seems to have been a spam  magnet,  
510         so  I've  taken  it away. If you want to email me, use my two initials,  REVISION
511         followed by the two digits 10, at the domain cam.ac.uk.  
512           Last updated: 12 May 2013
513           Copyright (c) 1997-2013 University of Cambridge.
514    ------------------------------------------------------------------------------
515    
516    
517    PCRE(3)                    Library Functions Manual                    PCRE(3)
518    
519    
520    
521    NAME
522           PCRE - Perl-compatible regular expressions
523    
524           #include <pcre.h>
525    
526    
527    PCRE 32-BIT API BASIC FUNCTIONS
528    
529           pcre32 *pcre32_compile(PCRE_SPTR32 pattern, int options,
530                const char **errptr, int *erroffset,
531                const unsigned char *tableptr);
532    
533           pcre32 *pcre32_compile2(PCRE_SPTR32 pattern, int options,
534                int *errorcodeptr,
535                const unsigned char *tableptr);
536    
537           pcre32_extra *pcre32_study(const pcre32 *code, int options,
538                const char **errptr);
539    
540           void pcre32_free_study(pcre32_extra *extra);
541    
542           int pcre32_exec(const pcre32 *code, const pcre32_extra *extra,
543                PCRE_SPTR32 subject, int length, int startoffset,
544                int options, int *ovector, int ovecsize);
545    
546           int pcre32_dfa_exec(const pcre32 *code, const pcre32_extra *extra,
547                PCRE_SPTR32 subject, int length, int startoffset,
548                int options, int *ovector, int ovecsize,
549                int *workspace, int wscount);
550    
551    
552    PCRE 32-BIT API STRING EXTRACTION FUNCTIONS
553    
554           int pcre32_copy_named_substring(const pcre32 *code,
555                PCRE_SPTR32 subject, int *ovector,
556                int stringcount, PCRE_SPTR32 stringname,
557                PCRE_UCHAR32 *buffer, int buffersize);
558    
559           int pcre32_copy_substring(PCRE_SPTR32 subject, int *ovector,
560                int stringcount, int stringnumber, PCRE_UCHAR32 *buffer,
561                int buffersize);
562    
563           int pcre32_get_named_substring(const pcre32 *code,
564                PCRE_SPTR32 subject, int *ovector,
565                int stringcount, PCRE_SPTR32 stringname,
566                PCRE_SPTR32 *stringptr);
567    
568           int pcre32_get_stringnumber(const pcre32 *code,
569                PCRE_SPTR32 name);
570    
571           int pcre32_get_stringtable_entries(const pcre32 *code,
572                PCRE_SPTR32 name, PCRE_UCHAR32 **first, PCRE_UCHAR32 **last);
573    
574           int pcre32_get_substring(PCRE_SPTR32 subject, int *ovector,
575                int stringcount, int stringnumber,
576                PCRE_SPTR32 *stringptr);
577    
578           int pcre32_get_substring_list(PCRE_SPTR32 subject,
579                int *ovector, int stringcount, PCRE_SPTR32 **listptr);
580    
581           void pcre32_free_substring(PCRE_SPTR32 stringptr);
582    
583           void pcre32_free_substring_list(PCRE_SPTR32 *stringptr);
584    
585    
586    PCRE 32-BIT API AUXILIARY FUNCTIONS
587    
588           pcre32_jit_stack *pcre32_jit_stack_alloc(int startsize, int maxsize);
589    
590           void pcre32_jit_stack_free(pcre32_jit_stack *stack);
591    
592           void pcre32_assign_jit_stack(pcre32_extra *extra,
593                pcre32_jit_callback callback, void *data);
594    
595           const unsigned char *pcre32_maketables(void);
596    
597           int pcre32_fullinfo(const pcre32 *code, const pcre32_extra *extra,
598                int what, void *where);
599    
600           int pcre32_refcount(pcre32 *code, int adjust);
601    
602           int pcre32_config(int what, void *where);
603    
604           const char *pcre32_version(void);
605    
606           int pcre32_pattern_to_host_byte_order(pcre32 *code,
607                pcre32_extra *extra, const unsigned char *tables);
608    
609    
610    PCRE 32-BIT API INDIRECTED FUNCTIONS
611    
612           void *(*pcre32_malloc)(size_t);
613    
614           void (*pcre32_free)(void *);
615    
616           void *(*pcre32_stack_malloc)(size_t);
617    
618           void (*pcre32_stack_free)(void *);
619    
620           int (*pcre32_callout)(pcre32_callout_block *);
621    
622    
623    PCRE 32-BIT API 32-BIT-ONLY FUNCTION
624    
625           int pcre32_utf32_to_host_byte_order(PCRE_UCHAR32 *output,
626                PCRE_SPTR32 input, int length, int *byte_order,
627                int keep_boms);
628    
629    
630    THE PCRE 32-BIT LIBRARY
631    
632           Starting  with  release  8.32, it is possible to compile a PCRE library
633           that supports 32-bit character strings, including  UTF-32  strings,  as
634           well as or instead of the original 8-bit library. This work was done by
635           Christian Persch, based on the work done  by  Zoltan  Herczeg  for  the
636           16-bit  library.  All  three  libraries contain identical sets of func-
637           tions, used in exactly the same way.  Only the names of  the  functions
638           and  the  data  types  of their arguments and results are different. To
639           avoid over-complication and reduce the documentation maintenance  load,
640           most  of  the PCRE documentation describes the 8-bit library, with only
641           occasional references to the 16-bit and  32-bit  libraries.  This  page
642           describes what is different when you use the 32-bit library.
643    
644           WARNING:  A  single  application  can  be linked with all or any of the
645           three libraries, but you must take care when processing any  particular
646           pattern  to  use  functions  from just one library. For example, if you
647           want to study a pattern that was compiled  with  pcre32_compile(),  you
648           must do so with pcre32_study(), not pcre_study(), and you must free the
649           study data with pcre32_free_study().
650    
651    
652    THE HEADER FILE
653    
654           There is only one header file, pcre.h. It contains prototypes  for  all
655           the functions in all libraries, as well as definitions of flags, struc-
656           tures, error codes, etc.
657    
658    
659    THE LIBRARY NAME
660    
661           In Unix-like systems, the 32-bit library is called libpcre32,  and  can
662           normally  be  accesss  by adding -lpcre32 to the command for linking an
663           application that uses PCRE.
664    
665    
666    STRING TYPES
667    
668           In the 8-bit library, strings are passed to PCRE library  functions  as
669           vectors  of  bytes  with  the  C  type "char *". In the 32-bit library,
670           strings are passed as vectors of unsigned 32-bit quantities. The  macro
671           PCRE_UCHAR32  specifies  an  appropriate  data type, and PCRE_SPTR32 is
672           defined as "const PCRE_UCHAR32 *". In very many environments, "unsigned
673           int" is a 32-bit data type. When PCRE is built, it defines PCRE_UCHAR32
674           as "unsigned int", but checks that it really is a 32-bit data type.  If
675           it is not, the build fails with an error message telling the maintainer
676           to modify the definition appropriately.
677    
678    
679    STRUCTURE TYPES
680    
681           The types of the opaque structures that are used  for  compiled  32-bit
682           patterns  and  JIT stacks are pcre32 and pcre32_jit_stack respectively.
683           The  type  of  the  user-accessible  structure  that  is  returned   by
684           pcre32_study()  is  pcre32_extra, and the type of the structure that is
685           used for passing data to a callout  function  is  pcre32_callout_block.
686           These structures contain the same fields, with the same names, as their
687           8-bit counterparts. The only difference is that pointers  to  character
688           strings are 32-bit instead of 8-bit types.
689    
690    
691    32-BIT FUNCTIONS
692    
693           For  every function in the 8-bit library there is a corresponding func-
694           tion in the 32-bit library with a name that starts with pcre32_ instead
695           of  pcre_.  The  prototypes are listed above. In addition, there is one
696           extra function, pcre32_utf32_to_host_byte_order(). This  is  a  utility
697           function  that converts a UTF-32 character string to host byte order if
698           necessary. The other 32-bit  functions  expect  the  strings  they  are
699           passed to be in host byte order.
700    
701           The input and output arguments of pcre32_utf32_to_host_byte_order() may
702           point to the same address, that is, conversion in place  is  supported.
703           The output buffer must be at least as long as the input.
704    
705           The  length  argument  specifies the number of 32-bit data units in the
706           input string; a negative value specifies a zero-terminated string.
707    
708           If byte_order is NULL, it is assumed that the string starts off in host
709           byte  order. This may be changed by byte-order marks (BOMs) anywhere in
710           the string (commonly as the first character).
711    
712           If byte_order is not NULL, a non-zero value of the integer to which  it
713           points  means  that  the input starts off in host byte order, otherwise
714           the opposite order is assumed. Again, BOMs in  the  string  can  change
715           this. The final byte order is passed back at the end of processing.
716    
717           If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
718           copied into the output string. Otherwise they are discarded.
719    
720           The result of the function is the number of 32-bit  units  placed  into
721           the  output  buffer,  including  the  zero terminator if the string was
722           zero-terminated.
723    
724    
725    SUBJECT STRING OFFSETS
726    
727           The lengths and starting offsets of subject strings must  be  specified
728           in  32-bit  data units, and the offsets within subject strings that are
729           returned by the matching functions are in also 32-bit units rather than
730           bytes.
731    
732    
733    NAMED SUBPATTERNS
734    
735           The  name-to-number translation table that is maintained for named sub-
736           patterns uses 32-bit characters.  The  pcre32_get_stringtable_entries()
737           function returns the length of each entry in the table as the number of
738           32-bit data units.
739    
740    
741    OPTION NAMES
742    
743           There   are   two   new   general   option   names,   PCRE_UTF32    and
744           PCRE_NO_UTF32_CHECK,     which     correspond    to    PCRE_UTF8    and
745           PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
746           define  the  same bits in the options word. There is a discussion about
747           the validity of UTF-32 strings in the pcreunicode page.
748    
749           For the pcre32_config() function there is an  option  PCRE_CONFIG_UTF32
750           that  returns  1  if UTF-32 support is configured, otherwise 0. If this
751           option  is  given  to  pcre_config()  or  pcre16_config(),  or  if  the
752           PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF16  option is given to pcre32_con-
753           fig(), the result is the PCRE_ERROR_BADOPTION error.
754    
755    
756    CHARACTER CODES
757    
758           In 32-bit mode, when  PCRE_UTF32  is  not  set,  character  values  are
759           treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
760           that they can range from 0 to 0x7fffffff instead of 0 to 0xff.  Charac-
761           ter  types for characters less than 0xff can therefore be influenced by
762           the locale in the same way as before.   Characters  greater  than  0xff
763           have only one case, and no "type" (such as letter or digit).
764    
765           In  UTF-32  mode,  the  character  code  is  Unicode, in the range 0 to
766           0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
767           because those are "surrogate" values that are ill-formed in UTF-32.
768    
769           A  UTF-32 string can indicate its endianness by special code knows as a
770           byte-order mark (BOM). The PCRE functions do not handle this, expecting
771           strings   to   be  in  host  byte  order.  A  utility  function  called
772           pcre32_utf32_to_host_byte_order() is provided to help  with  this  (see
773           above).
774    
775    
776    ERROR NAMES
777    
778           The  error  PCRE_ERROR_BADUTF32  corresponds  to its 8-bit counterpart.
779           The error PCRE_ERROR_BADMODE is given when a compiled pattern is passed
780           to  a  function that processes patterns in the other mode, for example,
781           if a pattern compiled with pcre_compile() is passed to pcre32_exec().
782    
783           There are new error codes whose names  begin  with  PCRE_UTF32_ERR  for
784           invalid  UTF-32  strings,  corresponding to the PCRE_UTF8_ERR codes for
785           UTF-8 strings that are described in the section entitled "Reason  codes
786           for  invalid UTF-8 strings" in the main pcreapi page. The UTF-32 errors
787           are:
788    
789             PCRE_UTF32_ERR1  Surrogate character (range from 0xd800 to 0xdfff)
790             PCRE_UTF32_ERR2  Non-character
791             PCRE_UTF32_ERR3  Character > 0x10ffff
792    
793    
794    ERROR TEXTS
795    
796           If there is an error while compiling a pattern, the error text that  is
797           passed  back by pcre32_compile() or pcre32_compile2() is still an 8-bit
798           character string, zero-terminated.
799    
800    
801    CALLOUTS
802    
803           The subject and mark fields in the callout block that is  passed  to  a
804           callout function point to 32-bit vectors.
805    
806    
807    TESTING
808    
809           The  pcretest  program continues to operate with 8-bit input and output
810           files, but it can be used for testing the 32-bit library. If it is  run
811           with the command line option -32, patterns and subject strings are con-
812           verted from 8-bit to 32-bit before being passed to PCRE, and the 32-bit
813           library  functions  are used instead of the 8-bit ones. Returned 32-bit
814           strings are converted to 8-bit for output. If both the  8-bit  and  the
815           16-bit libraries were not compiled, pcretest defaults to 32-bit and the
816           -32 option is ignored.
817    
818           When PCRE is being built, the RunTest script that is  called  by  "make
819           check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
820           16-bit and 32-bit libraries has been built, and runs the  tests  appro-
821           priately.
822    
823    
824    NOT SUPPORTED IN 32-BIT MODE
825    
826           Not all the features of the 8-bit library are available with the 32-bit
827           library. The C++ and POSIX wrapper functions  support  only  the  8-bit
828           library, and the pcregrep program is at present 8-bit only.
829    
830    
831    AUTHOR
832    
833           Philip Hazel
834           University Computing Service
835           Cambridge CB2 3QH, England.
836    
837    
838  REVISION  REVISION
839    
840         Last updated: 18 April 2007         Last updated: 12 May 2013
841         Copyright (c) 1997-2007 University of Cambridge.         Copyright (c) 1997-2013 University of Cambridge.
842  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
843    
844    
845  PCREBUILD(3)                                                      PCREBUILD(3)  PCREBUILD(3)               Library Functions Manual               PCREBUILD(3)
846    
847    
848    
849  NAME  NAME
850         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
851    
852    BUILDING PCRE
853    
854           PCRE  is  distributed with a configure script that can be used to build
855           the library in Unix-like environments using the applications  known  as
856           Autotools.   Also  in  the  distribution  are files to support building
857           using CMake instead of configure. The text file README contains general
858           information  about  building  with Autotools (some of which is repeated
859           below), and also has some comments about building on various  operating
860           systems.  There  is  a lot more information about building PCRE without
861           using Autotools (including information about using CMake  and  building
862           "by  hand")  in  the  text file called NON-AUTOTOOLS-BUILD.  You should
863           consult this file as well as the README file if you are building  in  a
864           non-Unix-like environment.
865    
866    
867  PCRE BUILD-TIME OPTIONS  PCRE BUILD-TIME OPTIONS
868    
869         This  document  describes  the  optional  features  of PCRE that can be         The  rest of this document describes the optional features of PCRE that
870         selected when the library is compiled. They are all selected, or  dese-         can be selected when the library is compiled. It  assumes  use  of  the
871         lected, by providing options to the configure script that is run before         configure  script,  where  the  optional features are selected or dese-
872         the make command. The complete list of  options  for  configure  (which         lected by providing options to configure before running the  make  com-
873         includes  the  standard  ones such as the selection of the installation         mand.  However,  the same options can be selected in both Unix-like and
874         directory) can be obtained by running         non-Unix-like environments using the GUI facility of cmake-gui  if  you
875           are using CMake instead of configure to build PCRE.
876    
877           If  you  are not using Autotools or CMake, option selection can be done
878           by editing the config.h file, or by passing parameter settings  to  the
879           compiler, as described in NON-AUTOTOOLS-BUILD.
880    
881           The complete list of options for configure (which includes the standard
882           ones such as the  selection  of  the  installation  directory)  can  be
883           obtained by running
884    
885           ./configure --help           ./configure --help
886    
887         The following sections include  descriptions  of  options  whose  names         The  following  sections  include  descriptions  of options whose names
888         begin with --enable or --disable. These settings specify changes to the         begin with --enable or --disable. These settings specify changes to the
889         defaults for the configure command. Because of the way  that  configure         defaults  for  the configure command. Because of the way that configure
890         works,  --enable  and --disable always come in pairs, so the complemen-         works, --enable and --disable always come in pairs, so  the  complemen-
891         tary option always exists as well, but as it specifies the default,  it         tary  option always exists as well, but as it specifies the default, it
892         is not described.         is not described.
893    
894    
895    BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES
896    
897           By default, a library called libpcre  is  built,  containing  functions
898           that  take  string  arguments  contained in vectors of bytes, either as
899           single-byte characters, or interpreted as UTF-8 strings. You  can  also
900           build  a  separate library, called libpcre16, in which strings are con-
901           tained in vectors of 16-bit data units and interpreted either  as  sin-
902           gle-unit characters or UTF-16 strings, by adding
903    
904             --enable-pcre16
905    
906           to  the  configure  command.  You  can  also build yet another separate
907           library, called libpcre32, in which strings are contained in vectors of
908           32-bit  data  units and interpreted either as single-unit characters or
909           UTF-32 strings, by adding
910    
911             --enable-pcre32
912    
913           to the configure command. If you do not want the 8-bit library, add
914    
915             --disable-pcre8
916    
917           as well. At least one of the three libraries must be built.  Note  that
918           the  C++  and  POSIX  wrappers are for the 8-bit library only, and that
919           pcregrep is an 8-bit program. None of these are  built  if  you  select
920           only the 16-bit or 32-bit libraries.
921    
922    
923    BUILDING SHARED AND STATIC LIBRARIES
924    
925           The  Autotools  PCRE building process uses libtool to build both shared
926           and static libraries by default. You  can  suppress  one  of  these  by
927           adding one of
928    
929             --disable-shared
930             --disable-static
931    
932           to the configure command, as required.
933    
934    
935  C++ SUPPORT  C++ SUPPORT
936    
937         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
938         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,
939         library for PCRE. You can disable this by adding         it  automatically  builds  the C++ wrapper library (which supports only
940           8-bit strings). You can disable this by adding
941    
942           --disable-cpp           --disable-cpp
943    
944         to the configure command.         to the configure command.
945    
946    
947  UTF-8 SUPPORT  UTF-8, UTF-16 AND UTF-32 SUPPORT
948    
949         To build PCRE with support for UTF-8 character strings, add         To build PCRE with support for UTF Unicode character strings, add
950    
951           --enable-utf8           --enable-utf
952    
953         to  the  configure  command.  Of  itself, this does not make PCRE treat         to the configure command. This setting applies to all three  libraries,
954         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
955         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
956         function.         library.  There  are no separate options for enabling UTF-8, UTF-16 and
957           UTF-32 independently because that would allow ridiculous settings  such
958           as  requesting UTF-16 support while building only the 8-bit library. It
959           is not possible to build one library with UTF support and another with-
960           out  in the same configuration. (For backwards compatibility, --enable-
961           utf8 is a synonym of --enable-utf.)
962    
963           Of itself, this setting does not make  PCRE  treat  strings  as  UTF-8,
964           UTF-16  or UTF-32. As well as compiling PCRE with this option, you also
965           have have to set the PCRE_UTF8, PCRE_UTF16  or  PCRE_UTF32  option  (as
966           appropriate) when you call one of the pattern compiling functions.
967    
968           If  you  set --enable-utf when compiling in an EBCDIC environment, PCRE
969           expects its input to be either ASCII or UTF-8 (depending  on  the  run-
970           time option). It is not possible to support both EBCDIC and UTF-8 codes
971           in the same version of  the  library.  Consequently,  --enable-utf  and
972           --enable-ebcdic are mutually exclusive.
973    
974    
975  UNICODE CHARACTER PROPERTY SUPPORT  UNICODE CHARACTER PROPERTY SUPPORT
976    
977         UTF-8 support allows PCRE to process character values greater than  255         UTF  support allows the libraries to process character codepoints up to
978         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
979         vide any facilities for accessing the properties of such characters. If         not provide any facilities for accessing the properties of such charac-
980         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,
981         refer to Unicode character properties, you must add         which refer to Unicode character properties, you must add
982    
983           --enable-unicode-properties           --enable-unicode-properties
984    
985         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
986         not explicitly requested it.         not explicitly requested it.
987    
988         Including  Unicode  property  support  adds around 30K of tables to the         Including Unicode property support adds around 30K  of  tables  to  the
989         PCRE library. Only the general category properties such as  Lu  and  Nd         PCRE  library.  Only  the general category properties such as Lu and Nd
990         are supported. Details are given in the pcrepattern documentation.         are supported. Details are given in the pcrepattern documentation.
991    
992    
993    JUST-IN-TIME COMPILER SUPPORT
994    
995           Just-in-time compiler support is included in the build by specifying
996    
997             --enable-jit
998    
999           This support is available only for certain hardware  architectures.  If
1000           this  option  is  set  for  an unsupported architecture, a compile time
1001           error occurs.  See the pcrejit documentation for a  discussion  of  JIT
1002           usage. When JIT support is enabled, pcregrep automatically makes use of
1003           it, unless you add
1004    
1005             --disable-pcregrep-jit
1006    
1007           to the "configure" command.
1008    
1009    
1010  CODE VALUE OF NEWLINE  CODE VALUE OF NEWLINE
1011    
1012         By  default,  PCRE interprets character 10 (linefeed, LF) as indicating         By default, PCRE interprets the linefeed (LF) character  as  indicating
1013         the end of a line. This is the normal newline  character  on  Unix-like         the  end  of  a line. This is the normal newline character on Unix-like
1014         systems. You can compile PCRE to use character 13 (carriage return, CR)         systems. You can compile PCRE to use carriage return (CR)  instead,  by
1015         instead, by adding         adding
1016    
1017           --enable-newline-is-cr           --enable-newline-is-cr
1018    
1019         to the  configure  command.  There  is  also  a  --enable-newline-is-lf         to  the  configure  command.  There  is  also  a --enable-newline-is-lf
1020         option, which explicitly specifies linefeed as the newline character.         option, which explicitly specifies linefeed as the newline character.
1021    
1022         Alternatively, you can specify that line endings are to be indicated by         Alternatively, you can specify that line endings are to be indicated by
# Line 315  CODE VALUE OF NEWLINE Line 1028  CODE VALUE OF NEWLINE
1028    
1029           --enable-newline-is-anycrlf           --enable-newline-is-anycrlf
1030    
1031         which causes PCRE to recognize any of the three sequences  CR,  LF,  or         which  causes  PCRE  to recognize any of the three sequences CR, LF, or
1032         CRLF as indicating a line ending. Finally, a fifth option, specified by         CRLF as indicating a line ending. Finally, a fifth option, specified by
1033    
1034           --enable-newline-is-any           --enable-newline-is-any
# Line 327  CODE VALUE OF NEWLINE Line 1040  CODE VALUE OF NEWLINE
1040         conventional to use the standard for your operating system.         conventional to use the standard for your operating system.
1041    
1042    
1043  BUILDING SHARED AND STATIC LIBRARIES  WHAT \R MATCHES
1044    
1045         The PCRE building process uses libtool to build both shared and  static         By default, the sequence \R in a pattern matches  any  Unicode  newline
1046         Unix  libraries by default. You can suppress one of these by adding one         sequence,  whatever  has  been selected as the line ending sequence. If
1047         of         you specify
1048    
1049           --disable-shared           --enable-bsr-anycrlf
          --disable-static  
1050    
1051         to the configure command, as required.         the default is changed so that \R matches only CR, LF, or  CRLF.  What-
1052           ever  is selected when PCRE is built can be overridden when the library
1053           functions are called.
1054    
1055    
1056  POSIX MALLOC USAGE  POSIX MALLOC USAGE
1057    
1058         When PCRE is called through the POSIX interface (see the pcreposix doc-         When the 8-bit library is called through the POSIX interface  (see  the
1059         umentation),  additional  working  storage  is required for holding the         pcreposix  documentation),  additional  working storage is required for
1060         pointers to capturing substrings, because PCRE requires three  integers         holding the pointers to capturing  substrings,  because  PCRE  requires
1061         per  substring,  whereas  the POSIX interface provides only two. If the         three integers per substring, whereas the POSIX interface provides only
1062         number of expected substrings is small, the wrapper function uses space         two. If the number of expected substrings is small, the  wrapper  func-
1063         on the stack, because this is faster than using malloc() for each call.         tion  uses  space  on the stack, because this is faster than using mal-
1064         The default threshold above which the stack is no longer used is 10; it         loc() for each call. The default threshold above which the stack is  no
1065         can be changed by adding a setting such as         longer used is 10; it can be changed by adding a setting such as
1066    
1067           --with-posix-malloc-threshold=20           --with-posix-malloc-threshold=20
1068    
# Line 359  HANDLING VERY LARGE PATTERNS Line 1073  HANDLING VERY LARGE PATTERNS
1073    
1074         Within  a  compiled  pattern,  offset values are used to point from one         Within  a  compiled  pattern,  offset values are used to point from one
1075         part to another (for example, from an opening parenthesis to an  alter-         part to another (for example, from an opening parenthesis to an  alter-
1076         nation  metacharacter).  By default, two-byte values are used for these         nation  metacharacter).  By default, in the 8-bit and 16-bit libraries,
1077         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
1078         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
1079         Nevertheless, some people do want to process enormous patterns,  so  it         but the most gigantic patterns.  Nevertheless, some people do  want  to
1080         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
1081         adding a setting such as         use three-byte or four-byte offsets by adding a setting such as
1082    
1083           --with-link-size=3           --with-link-size=3
1084    
1085         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
1086         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,
1087         additional bytes when handling them.         using longer offsets slows down the operation of PCRE because it has to
1088           load  additional  data  when  handling them. For the 32-bit library the
1089           value is always 4 and cannot be overridden; the value  of  --with-link-
1090           size is ignored.
1091    
1092    
1093  AVOIDING EXCESSIVE STACK USAGE  AVOIDING EXCESSIVE STACK USAGE
1094    
1095         When matching with the pcre_exec() function, PCRE implements backtrack-         When matching with the pcre_exec() function, PCRE implements backtrack-
1096         ing  by  making recursive calls to an internal function called match().         ing by making recursive calls to an internal function  called  match().
1097         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-
1098         verely  limit  PCRE's operation. (The Unix environment does not usually         verely limit PCRE's operation. (The Unix environment does  not  usually
1099         suffer from this problem, but it may sometimes be necessary to increase         suffer from this problem, but it may sometimes be necessary to increase
1100         the  maximum  stack size.  There is a discussion in the pcrestack docu-         the maximum stack size.  There is a discussion in the  pcrestack  docu-
1101         mentation.) An alternative approach to recursion that uses memory  from         mentation.)  An alternative approach to recursion that uses memory from
1102         the  heap  to remember data, instead of using recursive function calls,         the heap to remember data, instead of using recursive  function  calls,
1103         has been implemented to work round the problem of limited  stack  size.         has  been  implemented to work round the problem of limited stack size.
1104         If you want to build a version of PCRE that works this way, add         If you want to build a version of PCRE that works this way, add
1105    
1106           --disable-stack-for-recursion           --disable-stack-for-recursion
1107    
1108         to  the  configure  command. With this configuration, PCRE will use the         to the configure command. With this configuration, PCRE  will  use  the
1109         pcre_stack_malloc and pcre_stack_free variables to call memory  manage-         pcre_stack_malloc  and pcre_stack_free variables to call memory manage-
1110         ment  functions.  Separate  functions are provided because the usage is         ment functions. By default these point to malloc() and free(), but  you
1111         very predictable: the block sizes requested are always  the  same,  and         can replace the pointers so that your own functions are used instead.
1112         the  blocks  are always freed in reverse order. A calling program might  
1113         be able to implement optimized functions that perform better  than  the         Separate  functions  are  provided  rather  than  using pcre_malloc and
1114         standard  malloc()  and  free()  functions.  PCRE  runs noticeably more         pcre_free because the  usage  is  very  predictable:  the  block  sizes
1115         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
1116         function; it is not relevant for the the pcre_dfa_exec() function.         reverse order. A calling program might be able to  implement  optimized
1117           functions  that  perform  better  than  malloc()  and free(). PCRE runs
1118           noticeably more slowly when built in this way. This option affects only
1119           the pcre_exec() function; it is not relevant for pcre_dfa_exec().
1120    
1121    
1122  LIMITING PCRE RESOURCE USAGE  LIMITING PCRE RESOURCE USAGE
1123    
1124         Internally,  PCRE has a function called match(), which it calls repeat-         Internally,  PCRE has a function called match(), which it calls repeat-
1125         edly  (sometimes  recursively)  when  matching  a  pattern   with   the         edly  (sometimes  recursively)  when  matching  a  pattern   with   the
1126         pcre_exec()  function.  By controlling the maximum number of times this         pcre_exec()  function.  By controlling the maximum number of times this
1127         function may be called during a single matching operation, a limit  can         function may be called during a single matching operation, a limit  can
1128         be  placed  on  the resources used by a single call to pcre_exec(). The         be  placed  on  the resources used by a single call to pcre_exec(). The
1129         limit can be changed at run time, as described in the pcreapi  documen-         limit can be changed at run time, as described in the pcreapi  documen-
1130         tation.  The default is 10 million, but this can be changed by adding a         tation.  The default is 10 million, but this can be changed by adding a
1131         setting such as         setting such as
1132    
1133             --with-match-limit=500000
1134    
1135           to  the  configure  command.  This  setting  has  no  effect   on   the
1136           pcre_dfa_exec() matching function.
1137    
1138           In  some  environments  it is desirable to limit the depth of recursive
1139           calls of match() more strictly than the total number of calls, in order
1140           to  restrict  the maximum amount of stack (or heap, if --disable-stack-
1141           for-recursion is specified) that is used. A second limit controls this;
1142           it  defaults  to  the  value  that is set for --with-match-limit, which
1143           imposes no additional constraints. However, you can set a  lower  limit
1144           by adding, for example,
1145    
1146             --with-match-limit-recursion=10000
1147    
1148           to  the  configure  command.  This  value can also be overridden at run
1149           time.
1150    
1151    
1152    CREATING CHARACTER TABLES AT BUILD TIME
1153    
1154           PCRE uses fixed tables for processing characters whose code values  are
1155           less  than 256. By default, PCRE is built with a set of tables that are
1156           distributed in the file pcre_chartables.c.dist. These  tables  are  for
1157           ASCII codes only. If you add
1158    
1159             --enable-rebuild-chartables
1160    
1161           to  the  configure  command, the distributed tables are no longer used.
1162           Instead, a program called dftables is compiled and  run.  This  outputs
1163           the source for new set of tables, created in the default locale of your
1164           C run-time system. (This method of replacing the tables does  not  work
1165           if  you are cross compiling, because dftables is run on the local host.
1166           If you need to create alternative tables when cross compiling, you will
1167           have to do so "by hand".)
1168    
1169    
1170    USING EBCDIC CODE
1171    
1172           PCRE  assumes  by  default that it will run in an environment where the
1173           character code is ASCII (or Unicode, which is  a  superset  of  ASCII).
1174           This  is  the  case for most computer operating systems. PCRE can, how-
1175           ever, be compiled to run in an EBCDIC environment by adding
1176    
1177             --enable-ebcdic
1178    
1179           to the configure command. This setting implies --enable-rebuild-charta-
1180           bles.  You  should  only  use  it if you know that you are in an EBCDIC
1181           environment (for example,  an  IBM  mainframe  operating  system).  The
1182           --enable-ebcdic option is incompatible with --enable-utf.
1183    
1184           The EBCDIC character that corresponds to an ASCII LF is assumed to have
1185           the value 0x15 by default. However, in some EBCDIC  environments,  0x25
1186           is used. In such an environment you should use
1187    
1188             --enable-ebcdic-nl25
1189    
1190           as well as, or instead of, --enable-ebcdic. The EBCDIC character for CR
1191           has the same value as in ASCII, namely, 0x0d.  Whichever  of  0x15  and
1192           0x25 is not chosen as LF is made to correspond to the Unicode NEL char-
1193           acter (which, in Unicode, is 0x85).
1194    
1195           The options that select newline behaviour, such as --enable-newline-is-
1196           cr, and equivalent run-time options, refer to these character values in
1197           an EBCDIC environment.
1198    
1199    
1200    PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT
1201    
1202           By default, pcregrep reads all files as plain text. You can build it so
1203           that it recognizes files whose names end in .gz or .bz2, and reads them
1204           with libz or libbz2, respectively, by adding one or both of
1205    
1206             --enable-pcregrep-libz
1207             --enable-pcregrep-libbz2
1208    
1209           to the configure command. These options naturally require that the rel-
1210           evant  libraries  are installed on your system. Configuration will fail
1211           if they are not.
1212    
1213    
1214    PCREGREP BUFFER SIZE
1215    
1216           pcregrep uses an internal buffer to hold a "window" on the file  it  is
1217           scanning, in order to be able to output "before" and "after" lines when
1218           it finds a match. The size of the buffer is controlled by  a  parameter
1219           whose default value is 20K. The buffer itself is three times this size,
1220           but because of the way it is used for holding "before" lines, the long-
1221           est  line  that  is guaranteed to be processable is the parameter size.
1222           You can change the default parameter value by adding, for example,
1223    
1224             --with-pcregrep-bufsize=50K
1225    
1226           to the configure command. The caller of pcregrep can, however, override
1227           this value by specifying a run-time option.
1228    
1229    
1230    PCRETEST OPTION FOR LIBREADLINE SUPPORT
1231    
1232           If you add
1233    
1234             --enable-pcretest-libreadline
1235    
1236           to  the  configure  command,  pcretest  is  linked with the libreadline
1237           library, and when its input is from a terminal, it reads it  using  the
1238           readline() function. This provides line-editing and history facilities.
1239           Note that libreadline is GPL-licensed, so if you distribute a binary of
1240           pcretest linked in this way, there may be licensing issues.
1241    
1242           Setting  this  option  causes  the -lreadline option to be added to the
1243           pcretest build. In many operating environments with  a  sytem-installed
1244           libreadline this is sufficient. However, in some environments (e.g.  if
1245           an unmodified distribution version of readline is in use),  some  extra
1246           configuration  may  be necessary. The INSTALL file for libreadline says
1247           this:
1248    
1249             "Readline uses the termcap functions, but does not link with the
1250             termcap or curses library itself, allowing applications which link
1251             with readline the to choose an appropriate library."
1252    
1253           If your environment has not been set up so that an appropriate  library
1254           is automatically included, you may need to add something like
1255    
1256             LIBS="-ncurses"
1257    
1258           immediately before the configure command.
1259    
1260    
1261    DEBUGGING WITH VALGRIND SUPPORT
1262    
1263           By adding the
1264    
1265             --enable-valgrind
1266    
1267           option  to to the configure command, PCRE will use valgrind annotations
1268           to mark certain memory regions as  unaddressable.  This  allows  it  to
1269           detect invalid memory accesses, and is mostly useful for debugging PCRE
1270           itself.
1271    
1272    
1273    CODE COVERAGE REPORTING
1274    
1275           If your C compiler is gcc, you can build a version  of  PCRE  that  can
1276           generate a code coverage report for its test suite. To enable this, you
1277           must install lcov version 1.6 or above. Then specify
1278    
1279             --enable-coverage
1280    
1281           to the configure command and build PCRE in the usual way.
1282    
1283           Note that using ccache (a caching C compiler) is incompatible with code
1284           coverage  reporting. If you have configured ccache to run automatically
1285           on your system, you must set the environment variable
1286    
1287             CCACHE_DISABLE=1
1288    
1289           before running make to build PCRE, so that ccache is not used.
1290    
1291           --with-match-limit=500000         When --enable-coverage is used,  the  following  addition  targets  are
1292           added to the Makefile:
1293    
1294         to  the  configure  command.  This  setting  has  no  effect   on   the           make coverage
        pcre_dfa_exec() matching function.  
1295    
1296         In  some  environments  it is desirable to limit the depth of recursive         This  creates  a  fresh  coverage report for the PCRE test suite. It is
1297         calls of match() more strictly than the total number of calls, in order         equivalent to running "make coverage-reset", "make  coverage-baseline",
1298         to  restrict  the maximum amount of stack (or heap, if --disable-stack-         "make check", and then "make coverage-report".
        for-recursion is specified) that is used. A second limit controls this;  
        it  defaults  to  the  value  that is set for --with-match-limit, which  
        imposes no additional constraints. However, you can set a  lower  limit  
        by adding, for example,  
1299    
1300           --with-match-limit-recursion=10000           make coverage-reset
1301    
1302         to  the  configure  command.  This  value can also be overridden at run         This zeroes the coverage counters, but does nothing else.
        time.  
1303    
1304             make coverage-baseline
1305    
1306  CREATING CHARACTER TABLES AT BUILD TIME         This captures baseline coverage information.
1307    
1308         PCRE uses fixed tables for processing characters whose code values  are           make coverage-report
        less  than 256. By default, PCRE is built with a set of tables that are  
        distributed in the file pcre_chartables.c.dist. These  tables  are  for  
        ASCII codes only. If you add  
1309    
1310           --enable-rebuild-chartables         This creates the coverage report.
1311    
1312         to  the  configure  command, the distributed tables are no longer used.           make coverage-clean-report
        Instead, a program called dftables is compiled and  run.  This  outputs  
        the source for new set of tables, created in the default locale of your  
        C runtime system. (This method of replacing the tables does not work if  
        you  are cross compiling, because dftables is run on the local host. If  
        you need to create alternative tables when cross  compiling,  you  will  
        have to do so "by hand".)  
1313    
1314           This  removes the generated coverage report without cleaning the cover-
1315           age data itself.
1316    
1317  USING EBCDIC CODE           make coverage-clean-data
1318    
1319         PCRE  assumes  by  default that it will run in an environment where the         This removes the captured coverage data without removing  the  coverage
1320         character code is ASCII (or Unicode, which is  a  superset  of  ASCII).         files created at compile time (*.gcno).
        PCRE  can,  however,  be  compiled  to  run in an EBCDIC environment by  
        adding  
1321    
1322           --enable-ebcdic           make coverage-clean
1323    
1324         to the configure command. This setting implies --enable-rebuild-charta-         This  cleans all coverage data including the generated coverage report.
1325         bles.         For more information about code coverage, see the gcov and  lcov  docu-
1326           mentation.
1327    
1328    
1329  SEE ALSO  SEE ALSO
1330    
1331         pcreapi(3), pcre_config(3).         pcreapi(3), pcre16, pcre32, pcre_config(3).
1332    
1333    
1334  AUTHOR  AUTHOR
# Line 474  AUTHOR Line 1340  AUTHOR
1340    
1341  REVISION  REVISION
1342    
1343         Last updated: 16 April 2007         Last updated: 12 May 2013
1344         Copyright (c) 1997-2007 University of Cambridge.         Copyright (c) 1997-2013 University of Cambridge.
1345  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1346    
1347    
1348  PCREMATCHING(3)                                                PCREMATCHING(3)  PCREMATCHING(3)            Library Functions Manual            PCREMATCHING(3)
1349    
1350    
1351    
1352  NAME  NAME
1353         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
1354    
   
1355  PCRE MATCHING ALGORITHMS  PCRE MATCHING ALGORITHMS
1356    
1357         This document describes the two different algorithms that are available         This document describes the two different algorithms that are available
1358         in PCRE for matching a compiled regular expression against a given sub-         in PCRE for matching a compiled regular expression against a given sub-
1359         ject  string.  The  "standard"  algorithm  is  the  one provided by the         ject  string.  The  "standard"  algorithm  is  the  one provided by the
1360         pcre_exec() function.  This works in the same was  as  Perl's  matching         pcre_exec(), pcre16_exec() and pcre32_exec() functions. These  work  in
1361         function, and provides a Perl-compatible matching operation.         the  same as as Perl's matching function, and provide a Perl-compatible
1362           matching  operation.   The  just-in-time  (JIT)  optimization  that  is
1363         An  alternative  algorithm is provided by the pcre_dfa_exec() function;         described  in  the pcrejit documentation is compatible with these func-
1364         this operates in a different way, and is not  Perl-compatible.  It  has         tions.
1365         advantages  and disadvantages compared with the standard algorithm, and  
1366         these are described below.         An  alternative  algorithm  is   provided   by   the   pcre_dfa_exec(),
1367           pcre16_dfa_exec()  and  pcre32_dfa_exec()  functions; they operate in a
1368           different way, and are not Perl-compatible. This alternative has advan-
1369           tages and disadvantages compared with the standard algorithm, and these
1370           are described below.
1371    
1372         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
1373         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 562  THE ALTERNATIVE MATCHING ALGORITHM Line 1432  THE ALTERNATIVE MATCHING ALGORITHM
1432         though  it is not implemented as a traditional finite state machine (it         though  it is not implemented as a traditional finite state machine (it
1433         keeps multiple states active simultaneously).         keeps multiple states active simultaneously).
1434    
1435           Although the general principle of this matching algorithm  is  that  it
1436           scans  the subject string only once, without backtracking, there is one
1437           exception: when a lookaround assertion is encountered,  the  characters
1438           following  or  preceding  the  current  point  have to be independently
1439           inspected.
1440    
1441         The scan continues until either the end of the subject is  reached,  or         The scan continues until either the end of the subject is  reached,  or
1442         there  are  no more unterminated paths. At this point, terminated paths         there  are  no more unterminated paths. At this point, terminated paths
1443         represent the different matching possibilities (if there are none,  the         represent the different matching possibilities (if there are none,  the
1444         match  has  failed).   Thus,  if there is more than one possible match,         match  has  failed).   Thus,  if there is more than one possible match,
1445         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-
1446         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
1447         match (which is necessarily the shortest) has been found.         an option to stop the algorithm after the first match (which is  neces-
1448           sarily the shortest) is found.
1449    
1450         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
1451         subject. If the pattern         subject. If the pattern
1452    
1453           cat(er(pillar)?)           cat(er(pillar)?)?
1454    
1455         is  matched  against the string "the caterpillar catchment", the result         is matched against the string "the caterpillar catchment",  the  result
1456         will be the three strings "cat", "cater", and "caterpillar" that  start         will  be the three strings "caterpillar", "cater", and "cat" that start
1457         at the fourth character of the subject. The algorithm does not automat-         at the fifth character of the subject. The algorithm does not automati-
1458         ically move on to find matches that start at later positions.         cally move on to find matches that start at later positions.
1459    
1460           PCRE's  "auto-possessification" optimization usually applies to charac-
1461           ter repeats at the end of a pattern (as well as internally). For  exam-
1462           ple, the pattern "a\d+" is compiled as if it were "a\d++" because there
1463           is no point even considering the possibility of backtracking  into  the
1464           repeated  digits.  For  DFA matching, this means that only one possible
1465           match is found. If you really do want multiple matches in  such  cases,
1466           either use an ungreedy repeat ("a\d+?") or set the PCRE_NO_AUTO_POSSESS
1467           option when compiling.
1468    
1469         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
1470         supported by the alternative matching algorithm. They are as follows:         supported by the alternative matching algorithm. They are as follows:
# Line 618  THE ALTERNATIVE MATCHING ALGORITHM Line 1504  THE ALTERNATIVE MATCHING ALGORITHM
1504         6.  Callouts  are  supported, but the value of the capture_top field is         6.  Callouts  are  supported, but the value of the capture_top field is
1505         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.
1506    
1507         7.  The \C escape sequence, which (in the standard algorithm) matches a         7. The \C escape sequence, which (in  the  standard  algorithm)  always
1508         single  byte, even in UTF-8 mode, is not supported because the alterna-         matches  a  single data unit, even in UTF-8, UTF-16 or UTF-32 modes, is
1509         tive algorithm moves through the subject  string  one  character  at  a         not supported in these modes, because the alternative  algorithm  moves
1510         time, for all active paths through the tree.         through the subject string one character (not data unit) at a time, for
1511           all active paths through the tree.
1512    
1513           8. Except for (*FAIL), the backtracking control verbs such as  (*PRUNE)
1514           are  not  supported.  (*FAIL)  is supported, and behaves like a failing
1515           negative assertion.
1516    
1517    
1518  ADVANTAGES OF THE ALTERNATIVE ALGORITHM  ADVANTAGES OF THE ALTERNATIVE ALGORITHM
1519    
1520         Using  the alternative matching algorithm provides the following advan-         Using the alternative matching algorithm provides the following  advan-
1521         tages:         tages:
1522    
1523         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-
1524         ically  found,  and  in particular, the longest match is found. To find         ically found, and in particular, the longest match is  found.  To  find
1525         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
1526         things with callouts.         things with callouts.
1527    
1528         2.  There is much better support for partial matching. The restrictions         2. Because the alternative algorithm  scans  the  subject  string  just
1529         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-
1530         rithm  for  partial matching do not apply to the alternative algorithm.         sible to pass very long subject strings to  the  matching  function  in
1531         For non-anchored patterns, the starting position of a partial match  is         several pieces, checking for partial matching each time. Although it is
1532         available.         possible to do multi-segment matching using the standard  algorithm  by
1533           retaining  partially  matched  substrings,  it is more complicated. The
1534         3.  Because  the  alternative  algorithm  scans the subject string just         pcrepartial documentation gives details of partial  matching  and  dis-
1535         once, and never needs to backtrack, it is possible to  pass  very  long         cusses multi-segment matching.
        subject  strings  to  the matching function in several pieces, checking  
        for partial matching each time.  
1536    
1537    
1538  DISADVANTAGES OF THE ALTERNATIVE ALGORITHM  DISADVANTAGES OF THE ALTERNATIVE ALGORITHM
1539    
1540         The alternative algorithm suffers from a number of disadvantages:         The alternative algorithm suffers from a number of disadvantages:
1541    
1542         1. It is substantially slower than  the  standard  algorithm.  This  is         1.  It  is  substantially  slower  than the standard algorithm. This is
1543         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
1544         because it is less susceptible to optimization.         because it is less susceptible to optimization.
1545    
1546         2. Capturing parentheses and back references are not supported.         2. Capturing parentheses and back references are not supported.
# Line 669  AUTHOR Line 1558  AUTHOR
1558    
1559  REVISION  REVISION
1560    
1561         Last updated: 29 May 2007         Last updated: 12 November 2013
1562         Copyright (c) 1997-2007 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
1563  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1564    
1565    
1566  PCREAPI(3)                                                          PCREAPI(3)  PCREAPI(3)                 Library Functions Manual                 PCREAPI(3)
1567    
1568    
1569    
1570  NAME  NAME
1571         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
1572    
1573           #include <pcre.h>
1574    
 PCRE NATIVE API  
1575    
1576         #include <pcre.h>  PCRE NATIVE API BASIC FUNCTIONS
1577    
1578         pcre *pcre_compile(const char *pattern, int options,         pcre *pcre_compile(const char *pattern, int options,
1579              const char **errptr, int *erroffset,              const char **errptr, int *erroffset,
# Line 697  PCRE NATIVE API Line 1587  PCRE NATIVE API
1587         pcre_extra *pcre_study(const pcre *code, int options,         pcre_extra *pcre_study(const pcre *code, int options,
1588              const char **errptr);              const char **errptr);
1589    
1590           void pcre_free_study(pcre_extra *extra);
1591    
1592         int pcre_exec(const pcre *code, const pcre_extra *extra,         int pcre_exec(const pcre *code, const pcre_extra *extra,
1593              const char *subject, int length, int startoffset,              const char *subject, int length, int startoffset,
1594              int options, int *ovector, int ovecsize);              int options, int *ovector, int ovecsize);
# Line 706  PCRE NATIVE API Line 1598  PCRE NATIVE API
1598              int options, int *ovector, int ovecsize,              int options, int *ovector, int ovecsize,
1599              int *workspace, int wscount);              int *workspace, int wscount);
1600    
1601    
1602    PCRE NATIVE API STRING EXTRACTION FUNCTIONS
1603    
1604         int pcre_copy_named_substring(const pcre *code,         int pcre_copy_named_substring(const pcre *code,
1605              const char *subject, int *ovector,              const char *subject, int *ovector,
1606              int stringcount, const char *stringname,              int stringcount, const char *stringname,
# Line 737  PCRE NATIVE API Line 1632  PCRE NATIVE API
1632    
1633         void pcre_free_substring_list(const char **stringptr);         void pcre_free_substring_list(const char **stringptr);
1634    
1635    
1636    PCRE NATIVE API AUXILIARY FUNCTIONS
1637    
1638           int pcre_jit_exec(const pcre *code, const pcre_extra *extra,
1639                const char *subject, int length, int startoffset,
1640                int options, int *ovector, int ovecsize,
1641                pcre_jit_stack *jstack);
1642    
1643           pcre_jit_stack *pcre_jit_stack_alloc(int startsize, int maxsize);
1644    
1645           void pcre_jit_stack_free(pcre_jit_stack *stack);
1646    
1647           void pcre_assign_jit_stack(pcre_extra *extra,
1648                pcre_jit_callback callback, void *data);
1649    
1650         const unsigned char *pcre_maketables(void);         const unsigned char *pcre_maketables(void);
1651    
1652         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
1653              int what, void *where);              int what, void *where);
1654    
        int pcre_info(const pcre *code, int *optptr, int *firstcharptr);  
   
1655         int pcre_refcount(pcre *code, int adjust);         int pcre_refcount(pcre *code, int adjust);
1656    
1657         int pcre_config(int what, void *where);         int pcre_config(int what, void *where);
1658    
1659         char *pcre_version(void);         const char *pcre_version(void);
1660    
1661           int pcre_pattern_to_host_byte_order(pcre *code,
1662                pcre_extra *extra, const unsigned char *tables);
1663    
1664    
1665    PCRE NATIVE API INDIRECTED FUNCTIONS
1666    
1667         void *(*pcre_malloc)(size_t);         void *(*pcre_malloc)(size_t);
1668    
# Line 761  PCRE NATIVE API Line 1675  PCRE NATIVE API
1675         int (*pcre_callout)(pcre_callout_block *);         int (*pcre_callout)(pcre_callout_block *);
1676    
1677    
1678    PCRE 8-BIT, 16-BIT, AND 32-BIT LIBRARIES
1679    
1680           As  well  as  support  for  8-bit character strings, PCRE also supports
1681           16-bit strings (from release 8.30) and  32-bit  strings  (from  release
1682           8.32),  by means of two additional libraries. They can be built as well
1683           as, or instead of, the 8-bit library. To avoid too  much  complication,
1684           this  document describes the 8-bit versions of the functions, with only
1685           occasional references to the 16-bit and 32-bit libraries.
1686    
1687           The 16-bit and 32-bit functions operate in the same way as their  8-bit
1688           counterparts;  they  just  use different data types for their arguments
1689           and results, and their names start with pcre16_ or pcre32_  instead  of
1690           pcre_.  For  every  option  that  has  UTF8  in  its name (for example,
1691           PCRE_UTF8), there are corresponding 16-bit and 32-bit names  with  UTF8
1692           replaced by UTF16 or UTF32, respectively. This facility is in fact just
1693           cosmetic; the 16-bit and 32-bit option names define the same  bit  val-
1694           ues.
1695    
1696           References to bytes and UTF-8 in this document should be read as refer-
1697           ences to 16-bit data units and UTF-16 when using the 16-bit library, or
1698           32-bit  data  units  and  UTF-32  when using the 32-bit library, unless
1699           specified otherwise.  More details of the specific differences for  the
1700           16-bit and 32-bit libraries are given in the pcre16 and pcre32 pages.
1701    
1702    
1703  PCRE API OVERVIEW  PCRE API OVERVIEW
1704    
1705         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
1706         are also some wrapper functions that correspond to  the  POSIX  regular         are also some wrapper functions (for the 8-bit library only) that  cor-
1707         expression  API.  These  are  described in the pcreposix documentation.         respond  to  the  POSIX  regular  expression  API, but they do not give
1708         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
1709         distributed with PCRE. It is documented in the pcrecpp page.         documentation.  Both  of these APIs define a set of C function calls. A
1710           C++ wrapper (again for the 8-bit library only) is also distributed with
1711           PCRE. It is documented in the pcrecpp page.
1712    
1713         The  native  API  C  function prototypes are defined in the header file         The  native  API  C  function prototypes are defined in the header file
1714         pcre.h, and on Unix systems the library itself is called  libpcre.   It         pcre.h, and on Unix-like systems the (8-bit) library itself  is  called
1715         can normally be accessed by adding -lpcre to the command for linking an         libpcre.  It  can  normally be accessed by adding -lpcre to the command
1716         application  that  uses  PCRE.  The  header  file  defines  the  macros         for linking an application that uses PCRE. The header file defines  the
1717         PCRE_MAJOR  and  PCRE_MINOR to contain the major and minor release num-         macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release
1718         bers for the library.  Applications can use these  to  include  support         numbers for the library. Applications can use these to include  support
1719         for different releases of PCRE.         for different releases of PCRE.
1720    
1721           In a Windows environment, if you want to statically link an application
1722           program against a non-dll pcre.a  file,  you  must  define  PCRE_STATIC
1723           before  including  pcre.h or pcrecpp.h, because otherwise the pcre_mal-
1724           loc()   and   pcre_free()   exported   functions   will   be   declared
1725           __declspec(dllimport), with unwanted results.
1726    
1727         The   functions   pcre_compile(),  pcre_compile2(),  pcre_study(),  and         The   functions   pcre_compile(),  pcre_compile2(),  pcre_study(),  and
1728         pcre_exec() are used for compiling and matching regular expressions  in         pcre_exec() are used for compiling and matching regular expressions  in
1729         a  Perl-compatible  manner. A sample program that demonstrates the sim-         a  Perl-compatible  manner. A sample program that demonstrates the sim-
1730         plest way of using them is provided in the file  called  pcredemo.c  in         plest way of using them is provided in the file  called  pcredemo.c  in
1731         the  source distribution. The pcresample documentation describes how to         the PCRE source distribution. A listing of this program is given in the
1732         run it.         pcredemo documentation, and the pcresample documentation describes  how
1733           to compile and run it.
1734    
1735           Just-in-time  compiler  support is an optional feature of PCRE that can
1736           be built in appropriate hardware environments. It greatly speeds up the
1737           matching  performance  of  many  patterns.  Simple  programs can easily
1738           request that it be used if available, by  setting  an  option  that  is
1739           ignored  when  it is not relevant. More complicated programs might need
1740           to    make    use    of    the    functions     pcre_jit_stack_alloc(),
1741           pcre_jit_stack_free(),  and pcre_assign_jit_stack() in order to control
1742           the JIT code's memory usage.
1743    
1744           From release 8.32 there is also a direct interface for  JIT  execution,
1745           which  gives  improved performance. The JIT-specific functions are dis-
1746           cussed in the pcrejit documentation.
1747    
1748         A second matching function, pcre_dfa_exec(), which is not Perl-compati-         A second matching function, pcre_dfa_exec(), which is not Perl-compati-
1749         ble,  is  also provided. This uses a different algorithm for the match-         ble,  is  also provided. This uses a different algorithm for the match-
1750         ing. The alternative algorithm finds all possible matches (at  a  given         ing. The alternative algorithm finds all possible matches (at  a  given
1751         point  in  the subject), and scans the subject just once. However, this         point  in  the  subject), and scans the subject just once (unless there
1752         algorithm does not return captured substrings. A description of the two         are lookbehind assertions). However, this  algorithm  does  not  return
1753         matching  algorithms and their advantages and disadvantages is given in         captured  substrings.  A description of the two matching algorithms and
1754         the pcrematching documentation.         their advantages and disadvantages is given in the  pcrematching  docu-
1755           mentation.
1756    
1757         In addition to the main compiling and  matching  functions,  there  are         In  addition  to  the  main compiling and matching functions, there are
1758         convenience functions for extracting captured substrings from a subject         convenience functions for extracting captured substrings from a subject
1759         string that is matched by pcre_exec(). They are:         string that is matched by pcre_exec(). They are:
1760    
# Line 807  PCRE API OVERVIEW Line 1769  PCRE API OVERVIEW
1769         pcre_free_substring() and pcre_free_substring_list() are also provided,         pcre_free_substring() and pcre_free_substring_list() are also provided,
1770         to free the memory used for extracted strings.         to free the memory used for extracted strings.
1771    
1772         The  function  pcre_maketables()  is  used  to build a set of character         The function pcre_maketables() is used to  build  a  set  of  character
1773         tables  in  the  current  locale   for   passing   to   pcre_compile(),         tables   in   the   current   locale  for  passing  to  pcre_compile(),
1774         pcre_exec(),  or  pcre_dfa_exec(). This is an optional facility that is         pcre_exec(), or pcre_dfa_exec(). This is an optional facility  that  is
1775         provided for specialist use.  Most  commonly,  no  special  tables  are         provided  for  specialist  use.  Most  commonly,  no special tables are
1776         passed,  in  which case internal tables that are generated when PCRE is         passed, in which case internal tables that are generated when  PCRE  is
1777         built are used.         built are used.
1778    
1779         The function pcre_fullinfo() is used to find out  information  about  a         The  function  pcre_fullinfo()  is used to find out information about a
1780         compiled  pattern; pcre_info() is an obsolete version that returns only         compiled pattern. The function pcre_version() returns a  pointer  to  a
1781         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.  
1782    
1783         The function pcre_refcount() maintains a  reference  count  in  a  data         The  function  pcre_refcount()  maintains  a  reference count in a data
1784         block  containing  a compiled pattern. This is provided for the benefit         block containing a compiled pattern. This is provided for  the  benefit
1785         of object-oriented applications.         of object-oriented applications.
1786    
1787         The global variables pcre_malloc and pcre_free  initially  contain  the         The  global  variables  pcre_malloc and pcre_free initially contain the
1788         entry  points  of  the  standard malloc() and free() functions, respec-         entry points of the standard malloc()  and  free()  functions,  respec-
1789         tively. PCRE calls the memory management functions via these variables,         tively. PCRE calls the memory management functions via these variables,
1790         so  a  calling  program  can replace them if it wishes to intercept the         so a calling program can replace them if it  wishes  to  intercept  the
1791         calls. This should be done before calling any PCRE functions.         calls. This should be done before calling any PCRE functions.
1792    
1793         The global variables pcre_stack_malloc  and  pcre_stack_free  are  also         The  global  variables  pcre_stack_malloc  and pcre_stack_free are also
1794         indirections  to  memory  management functions. These special functions         indirections to memory management functions.  These  special  functions
1795         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
1796         data, instead of recursive function calls, when running the pcre_exec()         data, instead of recursive function calls, when running the pcre_exec()
1797         function. See the pcrebuild documentation for  details  of  how  to  do         function.  See  the  pcrebuild  documentation  for details of how to do
1798         this.  It  is  a non-standard way of building PCRE, for use in environ-         this. It is a non-standard way of building PCRE, for  use  in  environ-
1799         ments that have limited stacks. Because of the greater  use  of  memory         ments  that  have  limited stacks. Because of the greater use of memory
1800         management,  it  runs  more  slowly. Separate functions are provided so         management, it runs more slowly. Separate  functions  are  provided  so
1801         that special-purpose external code can be  used  for  this  case.  When         that  special-purpose  external  code  can  be used for this case. When
1802         used,  these  functions  are always called in a stack-like manner (last         used, these functions are always called in a  stack-like  manner  (last
1803         obtained, first freed), and always for memory blocks of the same  size.         obtained,  first freed), and always for memory blocks of the same size.
1804         There  is  a discussion about PCRE's stack usage in the pcrestack docu-         There is a discussion about PCRE's stack usage in the  pcrestack  docu-
1805         mentation.         mentation.
1806    
1807         The global variable pcre_callout initially contains NULL. It can be set         The global variable pcre_callout initially contains NULL. It can be set
1808         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
1809         specified points during a matching operation. Details are given in  the         specified  points during a matching operation. Details are given in the
1810         pcrecallout documentation.         pcrecallout documentation.
1811    
1812    
1813  NEWLINES  NEWLINES
1814    
1815         PCRE  supports five different conventions for indicating line breaks in         PCRE supports five different conventions for indicating line breaks  in
1816         strings: a single CR (carriage return) character, a  single  LF  (line-         strings:  a  single  CR (carriage return) character, a single LF (line-
1817         feed) character, the two-character sequence CRLF, any of the three pre-         feed) character, the two-character sequence CRLF, any of the three pre-
1818         ceding, or any Unicode newline sequence. The Unicode newline  sequences         ceding,  or any Unicode newline sequence. The Unicode newline sequences
1819         are  the  three just mentioned, plus the single characters VT (vertical         are the three just mentioned, plus the single characters  VT  (vertical
1820         tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS  (line         tab, U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line
1821         separator, U+2028), and PS (paragraph separator, U+2029).         separator, U+2028), and PS (paragraph separator, U+2029).
1822    
1823         Each  of  the first three conventions is used by at least one operating         Each of the first three conventions is used by at least  one  operating
1824         system as its standard newline sequence. When PCRE is built, a  default         system  as its standard newline sequence. When PCRE is built, a default
1825         can  be  specified.  The default default is LF, which is the Unix stan-         can be specified.  The default default is LF, which is the  Unix  stan-
1826         dard. When PCRE is run, the default can be overridden,  either  when  a         dard.  When  PCRE  is run, the default can be overridden, either when a
1827         pattern is compiled, or when it is matched.         pattern is compiled, or when it is matched.
1828    
1829           At compile time, the newline convention can be specified by the options
1830           argument  of  pcre_compile(), or it can be specified by special text at
1831           the start of the pattern itself; this overrides any other settings. See
1832           the pcrepattern page for details of the special character sequences.
1833    
1834         In the PCRE documentation the word "newline" is used to mean "the char-         In the PCRE documentation the word "newline" is used to mean "the char-
1835         acter or pair of characters that indicate a line break". The choice  of         acter or pair of characters that indicate a line break". The choice  of
1836         newline  convention  affects  the  handling of the dot, circumflex, and         newline  convention  affects  the  handling of the dot, circumflex, and
1837         dollar metacharacters, the handling of #-comments in /x mode, and, when         dollar metacharacters, the handling of #-comments in /x mode, and, when
1838         CRLF  is a recognized line ending sequence, the match position advance-         CRLF  is a recognized line ending sequence, the match position advance-
1839         ment for a non-anchored pattern. The choice of newline convention  does         ment for a non-anchored pattern. There is more detail about this in the
1840         not affect the interpretation of the \n or \r escape sequences.         section on pcre_exec() options below.
1841    
1842           The  choice of newline convention does not affect the interpretation of
1843           the \n or \r escape sequences, nor does  it  affect  what  \R  matches,
1844           which is controlled in a similar way, but by separate options.
1845    
1846    
1847  MULTITHREADING  MULTITHREADING
# Line 882  MULTITHREADING Line 1851  MULTITHREADING
1851         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
1852         callout function pointed to by pcre_callout, are shared by all threads.         callout function pointed to by pcre_callout, are shared by all threads.
1853    
1854         The  compiled form of a regular expression is not altered during match-         The compiled form of a regular expression is not altered during  match-
1855         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
1856         at once.         at once.
1857    
1858           If the just-in-time optimization feature is being used, it needs  sepa-
1859           rate  memory stack areas for each thread. See the pcrejit documentation
1860           for more details.
1861    
1862    
1863  SAVING PRECOMPILED PATTERNS FOR LATER USE  SAVING PRECOMPILED PATTERNS FOR LATER USE
1864    
1865         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
1866         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
1867         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
1868         pcreprecompile documentation. However, compiling a  regular  expression         pcreprecompile  documentation,  which  includes  a  description  of the
1869         with  one version of PCRE for use with a different version is not guar-         pcre_pattern_to_host_byte_order() function. However, compiling a  regu-
1870         anteed to work and may cause crashes.         lar  expression  with one version of PCRE for use with a different ver-
1871           sion is not guaranteed to work and may cause crashes.
1872    
1873    
1874  CHECKING BUILD-TIME OPTIONS  CHECKING BUILD-TIME OPTIONS
# Line 908  CHECKING BUILD-TIME OPTIONS Line 1882  CHECKING BUILD-TIME OPTIONS
1882    
1883         The  first  argument  for pcre_config() is an integer, specifying which         The  first  argument  for pcre_config() is an integer, specifying which
1884         information is required; the second argument is a pointer to a variable         information is required; the second argument is a pointer to a variable
1885         into  which  the  information  is  placed. The following information is         into  which  the  information  is placed. The returned value is zero on
1886           success, or the negative error code PCRE_ERROR_BADOPTION if  the  value
1887           in  the  first argument is not recognized. The following information is
1888         available:         available:
1889    
1890           PCRE_CONFIG_UTF8           PCRE_CONFIG_UTF8
1891    
1892         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-
1893         able; otherwise it is set to zero.         able;  otherwise it is set to zero. This value should normally be given
1894           to the 8-bit version of this function, pcre_config(). If it is given to
1895           the   16-bit  or  32-bit  version  of  this  function,  the  result  is
1896           PCRE_ERROR_BADOPTION.
1897    
1898             PCRE_CONFIG_UTF16
1899    
1900           The output is an integer that is set to one if UTF-16 support is avail-
1901           able;  otherwise it is set to zero. This value should normally be given
1902           to the 16-bit version of this function, pcre16_config(). If it is given
1903           to  the  8-bit  or  32-bit  version  of  this  function,  the result is
1904           PCRE_ERROR_BADOPTION.
1905    
1906             PCRE_CONFIG_UTF32
1907    
1908           The output is an integer that is set to one if UTF-32 support is avail-
1909           able;  otherwise it is set to zero. This value should normally be given
1910           to the 32-bit version of this function, pcre32_config(). If it is given
1911           to  the  8-bit  or  16-bit  version  of  this  function,  the result is
1912           PCRE_ERROR_BADOPTION.
1913    
1914           PCRE_CONFIG_UNICODE_PROPERTIES           PCRE_CONFIG_UNICODE_PROPERTIES
1915    
1916         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
1917         character properties is available; otherwise it is set to zero.         character properties is available; otherwise it is set to zero.
1918    
1919             PCRE_CONFIG_JIT
1920    
1921           The output is an integer that is set to one if support for just-in-time
1922           compiling is available; otherwise it is set to zero.
1923    
1924             PCRE_CONFIG_JITTARGET
1925    
1926           The output is a pointer to a zero-terminated "const char *" string.  If
1927           JIT support is available, the string contains the name of the architec-
1928           ture for which the JIT compiler is configured, for example  "x86  32bit
1929           (little  endian  +  unaligned)".  If  JIT support is not available, the
1930           result is NULL.
1931    
1932           PCRE_CONFIG_NEWLINE           PCRE_CONFIG_NEWLINE
1933    
1934         The output is an integer whose value specifies  the  default  character         The output is an integer whose value specifies  the  default  character
1935         sequence  that is recognized as meaning "newline". The four values that         sequence  that  is recognized as meaning "newline". The values that are
1936         are supported are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF,         supported in ASCII/Unicode environments are: 10 for LF, 13 for CR, 3338
1937         and  -1  for  ANY. The default should normally be the standard sequence         for  CRLF,  -2 for ANYCRLF, and -1 for ANY. In EBCDIC environments, CR,
1938         for your operating system.         ANYCRLF, and ANY yield the same values. However, the value  for  LF  is
1939           normally  21, though some EBCDIC environments use 37. The corresponding
1940           values for CRLF are 3349 and 3365. The default should  normally  corre-
1941           spond to the standard sequence for your operating system.
1942    
1943             PCRE_CONFIG_BSR
1944    
1945           The output is an integer whose value indicates what character sequences
1946           the \R escape sequence matches by default. A value of 0 means  that  \R
1947           matches  any  Unicode  line ending sequence; a value of 1 means that \R
1948           matches only CR, LF, or CRLF. The default can be overridden when a pat-
1949           tern is compiled or matched.
1950    
1951           PCRE_CONFIG_LINK_SIZE           PCRE_CONFIG_LINK_SIZE
1952    
1953         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
1954         internal linkage in compiled regular expressions. The value is 2, 3, or         internal  linkage  in  compiled  regular  expressions.  For  the  8-bit
1955         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
1956         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
1957         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
1958         pattern to be up to 64K in size.         default value of 2 is sufficient for all but the most massive patterns,
1959           since  it  allows  the compiled pattern to be up to 64K in size. Larger
1960           values allow larger regular expressions to be compiled, at the  expense
1961           of slower matching.
1962    
1963           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
1964    
# Line 944  CHECKING BUILD-TIME OPTIONS Line 1966  CHECKING BUILD-TIME OPTIONS
1966         POSIX interface uses malloc() for output vectors. Further  details  are         POSIX interface uses malloc() for output vectors. Further  details  are
1967         given in the pcreposix documentation.         given in the pcreposix documentation.
1968    
1969             PCRE_CONFIG_PARENS_LIMIT
1970    
1971           The output is a long integer that gives the maximum depth of nesting of
1972           parentheses (of any kind) in a pattern. This limit is  imposed  to  cap
1973           the amount of system stack used when a pattern is compiled. It is spec-
1974           ified when PCRE is built; the default is 250.
1975    
1976           PCRE_CONFIG_MATCH_LIMIT           PCRE_CONFIG_MATCH_LIMIT
1977    
1978         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-
1979         internal matching function calls in a  pcre_exec()  execution.  Further         ber  of  internal  matching  function calls in a pcre_exec() execution.
1980         details are given with pcre_exec() below.         Further details are given with pcre_exec() below.
1981    
1982           PCRE_CONFIG_MATCH_LIMIT_RECURSION           PCRE_CONFIG_MATCH_LIMIT_RECURSION
1983    
1984         The  output is an integer that gives the default limit for the depth of         The output is a long integer that gives the default limit for the depth
1985         recursion when calling the internal matching function in a  pcre_exec()         of   recursion  when  calling  the  internal  matching  function  in  a
1986         execution. Further details are given with pcre_exec() below.         pcre_exec() execution.  Further  details  are  given  with  pcre_exec()
1987           below.
1988    
1989           PCRE_CONFIG_STACKRECURSE           PCRE_CONFIG_STACKRECURSE
1990    
# Line 981  COMPILING A PATTERN Line 2011  COMPILING A PATTERN
2011         Either of the functions pcre_compile() or pcre_compile2() can be called         Either of the functions pcre_compile() or pcre_compile2() can be called
2012         to compile a pattern into an internal form. The only difference between         to compile a pattern into an internal form. The only difference between
2013         the  two interfaces is that pcre_compile2() has an additional argument,         the  two interfaces is that pcre_compile2() has an additional argument,
2014         errorcodeptr, via which a numerical error code can be returned.         errorcodeptr, via which a numerical error  code  can  be  returned.  To
2015           avoid  too  much repetition, we refer just to pcre_compile() below, but
2016           the information applies equally to pcre_compile2().
2017    
2018         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
2019         the  pattern  argument.  A  pointer to a single block of memory that is         the  pattern  argument.  A  pointer to a single block of memory that is
# Line 998  COMPILING A PATTERN Line 2030  COMPILING A PATTERN
2030    
2031         The options argument contains various bit settings that affect the com-         The options argument contains various bit settings that affect the com-
2032         pilation. It should be zero if no options are required.  The  available         pilation. It should be zero if no options are required.  The  available
2033         options  are  described  below. Some of them, in particular, those that         options  are  described  below. Some of them (in particular, those that
2034         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
2035         pattern  (see  the  detailed  description in the pcrepattern documenta-         unset  from  within  the  pattern  (see the detailed description in the
2036         tion). For these options, the contents of the options  argument  speci-         pcrepattern documentation). For those options that can be different  in
2037         fies  their initial settings at the start of compilation and execution.         different  parts  of  the pattern, the contents of the options argument
2038         The PCRE_ANCHORED and PCRE_NEWLINE_xxx options can be set at  the  time         specifies their settings at the start of compilation and execution. The
2039         of matching as well as at compile time.         PCRE_ANCHORED,  PCRE_BSR_xxx, PCRE_NEWLINE_xxx, PCRE_NO_UTF8_CHECK, and
2040           PCRE_NO_START_OPTIMIZE options can be set at the time  of  matching  as
2041           well as at compile time.
2042    
2043         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,
2044         if compilation of a pattern fails,  pcre_compile()  returns  NULL,  and         if compilation of a pattern fails,  pcre_compile()  returns  NULL,  and
2045         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-
2046         sage. This is a static string that is part of the library. You must not         sage. This is a static string that is part of the library. You must not
2047         try to free it. The offset from the start of the pattern to the charac-         try  to  free it. Normally, the offset from the start of the pattern to
2048         ter where the error was discovered is placed in the variable pointed to         the data unit that was being processed when the error was discovered is
2049         by  erroffset,  which must not be NULL. If it is, an immediate error is         placed  in the variable pointed to by erroffset, which must not be NULL
2050         given.         (if it is, an immediate error is given). However, for an invalid  UTF-8
2051           or  UTF-16  string,  the  offset  is that of the first data unit of the
2052           failing character.
2053    
2054           Some errors are not detected until the whole pattern has been  scanned;
2055           in  these  cases,  the offset passed back is the length of the pattern.
2056           Note that the offset is in data units, not characters, even  in  a  UTF
2057           mode. It may sometimes point into the middle of a UTF-8 or UTF-16 char-
2058           acter.
2059    
2060         If pcre_compile2() is used instead of pcre_compile(),  and  the  error-         If pcre_compile2() is used instead of pcre_compile(),  and  the  error-
2061         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 1024  COMPILING A PATTERN Line 2066  COMPILING A PATTERN
2066         character tables that are  built  when  PCRE  is  compiled,  using  the         character tables that are  built  when  PCRE  is  compiled,  using  the
2067         default  C  locale.  Otherwise, tableptr must be an address that is the         default  C  locale.  Otherwise, tableptr must be an address that is the
2068         result of a call to pcre_maketables(). This value is  stored  with  the         result of a call to pcre_maketables(). This value is  stored  with  the
2069         compiled  pattern,  and used again by pcre_exec(), unless another table         compiled  pattern,  and  used  again by pcre_exec() and pcre_dfa_exec()
2070         pointer is passed to it. For more discussion, see the section on locale         when the pattern is matched. For more discussion, see  the  section  on
2071         support below.         locale support below.
2072    
2073         This  code  fragment  shows a typical straightforward call to pcre_com-         This  code  fragment  shows a typical straightforward call to pcre_com-
2074         pile():         pile():
# Line 1058  COMPILING A PATTERN Line 2100  COMPILING A PATTERN
2100         all with number 255, before each pattern item. For  discussion  of  the         all with number 255, before each pattern item. For  discussion  of  the
2101         callout facility, see the pcrecallout documentation.         callout facility, see the pcrecallout documentation.
2102    
2103             PCRE_BSR_ANYCRLF
2104             PCRE_BSR_UNICODE
2105    
2106           These options (which are mutually exclusive) control what the \R escape
2107           sequence matches. The choice is either to match only CR, LF,  or  CRLF,
2108           or to match any Unicode newline sequence. The default is specified when
2109           PCRE is built. It can be overridden from within the pattern, or by set-
2110           ting an option when a compiled pattern is matched.
2111    
2112           PCRE_CASELESS           PCRE_CASELESS
2113    
2114         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 1082  COMPILING A PATTERN Line 2133  COMPILING A PATTERN
2133    
2134           PCRE_DOTALL           PCRE_DOTALL
2135    
2136         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-
2137         acters, including those that indicate newline. Without it, a  dot  does         acter of any value, including one that indicates a newline. However, it
2138         not  match  when  the  current position is at a newline. This option is         only  ever  matches  one character, even if newlines are coded as CRLF.
2139         equivalent to Perl's /s option, and it can be changed within a  pattern         Without this option, a dot does not match when the current position  is
2140         by  a (?s) option setting. A negative class such as [^a] always matches         at a newline. This option is equivalent to Perl's /s option, and it can
2141         newline characters, independent of the setting of this option.         be changed within a pattern by a (?s) option setting. A negative  class
2142           such as [^a] always matches newline characters, independent of the set-
2143           ting of this option.
2144    
2145           PCRE_DUPNAMES           PCRE_DUPNAMES
2146    
# Line 1099  COMPILING A PATTERN Line 2152  COMPILING A PATTERN
2152    
2153           PCRE_EXTENDED           PCRE_EXTENDED
2154    
2155         If this bit is set, whitespace  data  characters  in  the  pattern  are         If this bit is set, most white space  characters  in  the  pattern  are
2156         totally ignored except when escaped or inside a character class. White-         totally  ignored  except when escaped or inside a character class. How-
2157         space does not include the VT character (code 11). In addition, charac-         ever, white space is not allowed within  sequences  such  as  (?>  that
2158         ters between an unescaped # outside a character class and the next new-         introduce  various  parenthesized  subpatterns,  nor within a numerical
2159         line, inclusive, are also ignored. This  is  equivalent  to  Perl's  /x         quantifier such as {1,3}.  However, ignorable white space is  permitted
2160         option,  and  it  can be changed within a pattern by a (?x) option set-         between an item and a following quantifier and between a quantifier and
2161         ting.         a following + that indicates possessiveness.
2162    
2163         This option makes it possible to include  comments  inside  complicated         White space did not used to include the VT character (code 11), because
2164         patterns.   Note,  however,  that this applies only to data characters.         Perl did not treat this character as white space. However, Perl changed
2165         Whitespace  characters  may  never  appear  within  special   character         at release 5.18, so PCRE followed  at  release  8.34,  and  VT  is  now
2166         sequences  in  a  pattern,  for  example  within the sequence (?( which         treated as white space.
2167         introduces a conditional subpattern.  
2168           PCRE_EXTENDED  also  causes characters between an unescaped # outside a
2169           character class  and  the  next  newline,  inclusive,  to  be  ignored.
2170           PCRE_EXTENDED  is equivalent to Perl's /x option, and it can be changed
2171           within a pattern by a (?x) option setting.
2172    
2173           Which characters are interpreted  as  newlines  is  controlled  by  the
2174           options  passed to pcre_compile() or by a special sequence at the start
2175           of the pattern, as described in the section entitled  "Newline  conven-
2176           tions" in the pcrepattern documentation. Note that the end of this type
2177           of comment is  a  literal  newline  sequence  in  the  pattern;  escape
2178           sequences that happen to represent a newline do not count.
2179    
2180           This  option  makes  it possible to include comments inside complicated
2181           patterns.  Note, however, that this applies only  to  data  characters.
2182           White  space  characters  may  never  appear  within  special character
2183           sequences in a pattern, for example within the sequence (?( that intro-
2184           duces a conditional subpattern.
2185    
2186           PCRE_EXTRA           PCRE_EXTRA
2187    
2188         This option was invented in order to turn on  additional  functionality         This  option  was invented in order to turn on additional functionality
2189         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
2190         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
2191         letter  that  has  no  special  meaning causes an error, thus reserving         letter that has no special meaning  causes  an  error,  thus  reserving
2192         these combinations for future expansion. By  default,  as  in  Perl,  a         these  combinations  for  future  expansion.  By default, as in Perl, a
2193         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
2194         literal. (Perl can, however, be persuaded to give a warning for  this.)         literal. (Perl can, however, be persuaded to give an error for this, by
2195         There  are  at  present no other features controlled by this option. It         running it with the -w option.) There are at present no other  features
2196         can also be set by a (?X) option setting within a pattern.         controlled  by this option. It can also be set by a (?X) option setting
2197           within a pattern.
2198    
2199           PCRE_FIRSTLINE           PCRE_FIRSTLINE
2200    
# Line 1131  COMPILING A PATTERN Line 2202  COMPILING A PATTERN
2202         before  or  at  the  first  newline  in  the subject string, though the         before  or  at  the  first  newline  in  the subject string, though the
2203         matched text may continue over the newline.         matched text may continue over the newline.
2204    
2205             PCRE_JAVASCRIPT_COMPAT
2206    
2207           If this option is set, PCRE's behaviour is changed in some ways so that
2208           it  is  compatible with JavaScript rather than Perl. The changes are as
2209           follows:
2210    
2211           (1) A lone closing square bracket in a pattern  causes  a  compile-time
2212           error,  because this is illegal in JavaScript (by default it is treated
2213           as a data character). Thus, the pattern AB]CD becomes illegal when this
2214           option is set.
2215    
2216           (2)  At run time, a back reference to an unset subpattern group matches
2217           an empty string (by default this causes the current  matching  alterna-
2218           tive  to  fail). A pattern such as (\1)(a) succeeds when this option is
2219           set (assuming it can find an "a" in the subject), whereas it  fails  by
2220           default, for Perl compatibility.
2221    
2222           (3) \U matches an upper case "U" character; by default \U causes a com-
2223           pile time error (Perl uses \U to upper case subsequent characters).
2224    
2225           (4) \u matches a lower case "u" character unless it is followed by four
2226           hexadecimal  digits,  in  which case the hexadecimal number defines the
2227           code point to match. By default, \u causes a compile time  error  (Perl
2228           uses it to upper case the following character).
2229    
2230           (5)  \x matches a lower case "x" character unless it is followed by two
2231           hexadecimal digits, in which case the hexadecimal  number  defines  the
2232           code  point  to  match. By default, as in Perl, a hexadecimal number is
2233           always expected after \x, but it may have zero, one, or two digits (so,
2234           for example, \xz matches a binary zero character followed by z).
2235    
2236           PCRE_MULTILINE           PCRE_MULTILINE
2237    
2238         By default, PCRE treats the subject string as consisting  of  a  single         By  default,  for  the purposes of matching "start of line" and "end of
2239         line  of characters (even if it actually contains newlines). The "start         line", PCRE treats the subject string as consisting of a single line of
2240         of line" metacharacter (^) matches only at the  start  of  the  string,         characters,  even if it actually contains newlines. The "start of line"
2241         while  the  "end  of line" metacharacter ($) matches only at the end of         metacharacter (^) matches only at the start of the string, and the "end
2242         the string, or before a terminating newline (unless PCRE_DOLLAR_ENDONLY         of  line"  metacharacter  ($) matches only at the end of the string, or
2243         is set). This is the same as Perl.         before a terminating newline (except when PCRE_DOLLAR_ENDONLY is  set).
2244           Note,  however,  that  unless  PCRE_DOTALL  is set, the "any character"
2245           metacharacter (.) does not match at a newline. This behaviour  (for  ^,
2246           $, and dot) is the same as Perl.
2247    
2248         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"
2249         constructs match immediately following or immediately  before  internal         constructs match immediately following or immediately  before  internal
# Line 1148  COMPILING A PATTERN Line 2253  COMPILING A PATTERN
2253         lines in a subject string, or no occurrences of ^ or $  in  a  pattern,         lines in a subject string, or no occurrences of ^ or $  in  a  pattern,
2254         setting PCRE_MULTILINE has no effect.         setting PCRE_MULTILINE has no effect.
2255    
2256             PCRE_NEVER_UTF
2257    
2258           This option locks out interpretation of the pattern as UTF-8 (or UTF-16
2259           or UTF-32 in the 16-bit and 32-bit libraries). In particular,  it  pre-
2260           vents  the  creator of the pattern from switching to UTF interpretation
2261           by starting the pattern with (*UTF). This may be useful in applications
2262           that  process  patterns  from  external  sources.  The  combination  of
2263           PCRE_UTF8 and PCRE_NEVER_UTF also causes an error.
2264    
2265           PCRE_NEWLINE_CR           PCRE_NEWLINE_CR
2266           PCRE_NEWLINE_LF           PCRE_NEWLINE_LF
2267           PCRE_NEWLINE_CRLF           PCRE_NEWLINE_CRLF
2268           PCRE_NEWLINE_ANYCRLF           PCRE_NEWLINE_ANYCRLF
2269           PCRE_NEWLINE_ANY           PCRE_NEWLINE_ANY
2270    
2271         These  options  override the default newline definition that was chosen         These options override the default newline definition that  was  chosen
2272         when PCRE was built. Setting the first or the second specifies  that  a         when  PCRE  was built. Setting the first or the second specifies that a
2273         newline  is  indicated  by a single character (CR or LF, respectively).         newline is indicated by a single character (CR  or  LF,  respectively).
2274         Setting PCRE_NEWLINE_CRLF specifies that a newline is indicated by  the         Setting  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the
2275         two-character  CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF specifies         two-character CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF  specifies
2276         that any of the three preceding sequences should be recognized. Setting         that any of the three preceding sequences should be recognized. Setting
2277         PCRE_NEWLINE_ANY  specifies that any Unicode newline sequence should be         PCRE_NEWLINE_ANY specifies that any Unicode newline sequence should  be
2278         recognized. The Unicode newline sequences are the three just mentioned,         recognized.
2279         plus  the  single  characters  VT (vertical tab, U+000B), FF (formfeed,  
2280         U+000C), NEL (next line, U+0085), LS (line separator, U+2028),  and  PS         In  an ASCII/Unicode environment, the Unicode newline sequences are the
2281         (paragraph  separator,  U+2029).  The  last  two are recognized only in         three just mentioned, plus the  single  characters  VT  (vertical  tab,
2282         UTF-8 mode.         U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line sep-
2283           arator, U+2028), and PS (paragraph separator, U+2029).  For  the  8-bit
2284           library, the last two are recognized only in UTF-8 mode.
2285    
2286           When  PCRE is compiled to run in an EBCDIC (mainframe) environment, the
2287           code for CR is 0x0d, the same as ASCII. However, the character code for
2288           LF  is  normally 0x15, though in some EBCDIC environments 0x25 is used.
2289           Whichever of these is not LF is made to  correspond  to  Unicode's  NEL
2290           character.  EBCDIC  codes  are all less than 256. For more details, see
2291           the pcrebuild documentation.
2292    
2293         The newline setting in the  options  word  uses  three  bits  that  are         The newline setting in the  options  word  uses  three  bits  that  are
2294         treated as a number, giving eight possibilities. Currently only six are         treated as a number, giving eight possibilities. Currently only six are
# Line 1175  COMPILING A PATTERN Line 2298  COMPILING A PATTERN
2298         PCRE_NEWLINE_CRLF,  but other combinations may yield unused numbers and         PCRE_NEWLINE_CRLF,  but other combinations may yield unused numbers and
2299         cause an error.         cause an error.
2300    
2301         The only time that a line break is specially recognized when  compiling         The only time that a line break in a pattern  is  specially  recognized
2302         a  pattern  is  if  PCRE_EXTENDED  is set, and an unescaped # outside a         when  compiling is when PCRE_EXTENDED is set. CR and LF are white space
2303         character class is encountered. This indicates  a  comment  that  lasts         characters, and so are ignored in this mode. Also, an unescaped #  out-
2304         until  after the next line break sequence. In other circumstances, line         side  a  character class indicates a comment that lasts until after the
2305         break  sequences  are  treated  as  literal  data,   except   that   in         next line break sequence. In other circumstances, line break  sequences
2306         PCRE_EXTENDED mode, both CR and LF are treated as whitespace characters         in patterns are treated as literal data.
        and are therefore ignored.  
2307    
2308         The newline option that is set at compile time becomes the default that         The newline option that is set at compile time becomes the default that
2309         is  used for pcre_exec() and pcre_dfa_exec(), but it can be overridden.         is used for pcre_exec() and pcre_dfa_exec(), but it can be overridden.
2310    
2311           PCRE_NO_AUTO_CAPTURE           PCRE_NO_AUTO_CAPTURE
2312    
# Line 1194  COMPILING A PATTERN Line 2316  COMPILING A PATTERN
2316         be  used  for  capturing  (and  they acquire numbers in the usual way).         be  used  for  capturing  (and  they acquire numbers in the usual way).
2317         There is no equivalent of this option in Perl.         There is no equivalent of this option in Perl.
2318    
2319             PCRE_NO_AUTO_POSSESS
2320    
2321           If this option is set, it disables "auto-possessification". This is  an
2322           optimization  that,  for example, turns a+b into a++b in order to avoid
2323           backtracks into a+ that can never be successful. However,  if  callouts
2324           are  in  use,  auto-possessification  means that some of them are never
2325           taken. You can set this option if you want the matching functions to do
2326           a  full  unoptimized  search and run all the callouts, but it is mainly
2327           provided for testing purposes.
2328    
2329             PCRE_NO_START_OPTIMIZE
2330    
2331           This is an option that acts at matching time; that is, it is really  an
2332           option  for  pcre_exec()  or  pcre_dfa_exec().  If it is set at compile
2333           time, it is remembered with the compiled pattern and assumed at  match-
2334           ing  time.  This is necessary if you want to use JIT execution, because
2335           the JIT compiler needs to know whether or not this option is  set.  For
2336           details see the discussion of PCRE_NO_START_OPTIMIZE below.
2337    
2338             PCRE_UCP
2339    
2340           This  option changes the way PCRE processes \B, \b, \D, \d, \S, \s, \W,
2341           \w, and some of the POSIX character classes.  By  default,  only  ASCII
2342           characters  are  recognized, but if PCRE_UCP is set, Unicode properties
2343           are used instead to classify characters. More details are given in  the
2344           section  on generic character types in the pcrepattern page. If you set
2345           PCRE_UCP, matching one of the items it affects takes much  longer.  The
2346           option  is  available only if PCRE has been compiled with Unicode prop-
2347           erty support.
2348    
2349           PCRE_UNGREEDY           PCRE_UNGREEDY
2350    
2351         This option inverts the "greediness" of the quantifiers  so  that  they         This option inverts the "greediness" of the quantifiers  so  that  they
# Line 1204  COMPILING A PATTERN Line 2356  COMPILING A PATTERN
2356           PCRE_UTF8           PCRE_UTF8
2357    
2358         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
2359         strings of UTF-8 characters instead of single-byte  character  strings.         strings of UTF-8 characters instead of single-byte strings. However, it
2360         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,
2361         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
2362         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.  
2363    
2364           PCRE_NO_UTF8_CHECK           PCRE_NO_UTF8_CHECK
2365    
2366         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
2367         automatically  checked. If an invalid UTF-8 sequence of bytes is found,         automatically checked. There is a  discussion  about  the  validity  of
2368         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
2369         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
2370         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-
2371         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
2372         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
2373         pcre_exec()  and pcre_dfa_exec(), to suppress the UTF-8 validity check-         may cause your program to crash or loop. Note that this option can also
2374         ing of subject strings.         be  passed to pcre_exec() and pcre_dfa_exec(), to suppress the validity
2375           checking of subject strings only. If the same string is  being  matched
2376           many  times, the option can be safely set for the second and subsequent
2377           matchings to improve performance.
2378    
2379    
2380  COMPILATION ERROR CODES  COMPILATION ERROR CODES
2381    
2382         The following table lists the error  codes  than  may  be  returned  by         The following table lists the error  codes  than  may  be  returned  by
2383         pcre_compile2(),  along with the error messages that may be returned by         pcre_compile2(),  along with the error messages that may be returned by
2384         both compiling functions. As PCRE has developed, some error codes  have         both compiling functions. Note that error  messages  are  always  8-bit
2385         fallen out of use. To avoid confusion, they have not been re-used.         ASCII  strings,  even  in 16-bit or 32-bit mode. As PCRE has developed,
2386           some error codes have fallen out of use. To avoid confusion, they  have
2387           not been re-used.
2388    
2389            0  no error            0  no error
2390            1  \ at end of pattern            1  \ at end of pattern
# Line 1242  COMPILATION ERROR CODES Line 2398  COMPILATION ERROR CODES
2398            9  nothing to repeat            9  nothing to repeat
2399           10  [this code is not in use]           10  [this code is not in use]
2400           11  internal error: unexpected repeat           11  internal error: unexpected repeat
2401           12  unrecognized character after (?           12  unrecognized character after (? or (?-
2402           13  POSIX named classes are supported only within a class           13  POSIX named classes are supported only within a class
2403           14  missing )           14  missing )
2404           15  reference to non-existent subpattern           15  reference to non-existent subpattern
# Line 1250  COMPILATION ERROR CODES Line 2406  COMPILATION ERROR CODES
2406           17  unknown option bit(s) set           17  unknown option bit(s) set
2407           18  missing ) after comment           18  missing ) after comment
2408           19  [this code is not in use]           19  [this code is not in use]
2409           20  regular expression too large           20  regular expression is too large
2410           21  failed to get memory           21  failed to get memory
2411           22  unmatched parentheses           22  unmatched parentheses
2412           23  internal error: code overflow           23  internal error: code overflow
# Line 1259  COMPILATION ERROR CODES Line 2415  COMPILATION ERROR CODES
2415           26  malformed number or name after (?(           26  malformed number or name after (?(
2416           27  conditional group contains more than two branches           27  conditional group contains more than two branches
2417           28  assertion expected after (?(           28  assertion expected after (?(
2418           29  (?R or (?digits must be followed by )           29  (?R or (?[+-]digits must be followed by )
2419           30  unknown POSIX class name           30  unknown POSIX class name
2420           31  POSIX collating elements are not supported           31  POSIX collating elements are not supported
2421           32  this version of PCRE is not compiled with PCRE_UTF8 support           32  this version of PCRE is compiled without UTF support
2422           33  [this code is not in use]           33  [this code is not in use]
2423           34  character value in \x{...} sequence is too large           34  character value in \x{} or \o{} is too large
2424           35  invalid condition (?(0)           35  invalid condition (?(0)
2425           36  \C not allowed in lookbehind assertion           36  \C not allowed in lookbehind assertion
2426           37  PCRE does not support \L, \l, \N, \U, or \u           37  PCRE does not support \L, \l, \N{name}, \U, or \u
2427           38  number after (?C is > 255           38  number after (?C is > 255
2428           39  closing ) for (?C expected           39  closing ) for (?C expected
2429           40  recursive call could loop indefinitely           40  recursive call could loop indefinitely
2430           41  unrecognized character after (?P           41  unrecognized character after (?P
2431           42  syntax error in subpattern name (missing terminator)           42  syntax error in subpattern name (missing terminator)
2432           43  two named subpatterns have the same name           43  two named subpatterns have the same name
2433           44  invalid UTF-8 string           44  invalid UTF-8 string (specifically UTF-8)
2434           45  support for \P, \p, and \X has not been compiled           45  support for \P, \p, and \X has not been compiled
2435           46  malformed \P or \p sequence           46  malformed \P or \p sequence
2436           47  unknown property name after \P or \p           47  unknown property name after \P or \p
2437           48  subpattern name is too long (maximum 32 characters)           48  subpattern name is too long (maximum 32 characters)
2438           49  too many named subpatterns (maximum 10,000)           49  too many named subpatterns (maximum 10000)
2439           50  repeated subpattern is too long           50  [this code is not in use]
2440           51  octal value is greater than \377 (not in UTF-8 mode)           51  octal value is greater than \377 in 8-bit non-UTF-8 mode
2441           52  internal error: overran compiling workspace           52  internal error: overran compiling workspace
2442           53   internal  error:  previously-checked  referenced  subpattern not           53  internal error: previously-checked referenced subpattern
2443         found                 not found
2444           54  DEFINE group contains more than one branch           54  DEFINE group contains more than one branch
2445           55  repeating a DEFINE group is not allowed           55  repeating a DEFINE group is not allowed
2446           56  inconsistent NEWLINE options"           56  inconsistent NEWLINE options
2447             57  \g is not followed by a braced, angle-bracketed, or quoted
2448                   name/number or by a plain number
2449             58  a numbered reference must not be zero
2450             59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
2451             60  (*VERB) not recognized or malformed
2452             61  number is too big
2453             62  subpattern name expected
2454             63  digit expected after (?+
2455             64  ] is an invalid data character in JavaScript compatibility mode
2456             65  different names for subpatterns of the same number are
2457                   not allowed
2458             66  (*MARK) must have an argument
2459             67  this version of PCRE is not compiled with Unicode property
2460                   support
2461             68  \c must be followed by an ASCII character
2462             69  \k is not followed by a braced, angle-bracketed, or quoted name
2463             70  internal error: unknown opcode in find_fixedlength()
2464             71  \N is not supported in a class
2465             72  too many forward references
2466             73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
2467             74  invalid UTF-16 string (specifically UTF-16)
2468             75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
2469             76  character value in \u.... sequence is too large
2470             77  invalid UTF-32 string (specifically UTF-32)
2471             78  setting UTF is disabled by the application
2472             79  non-hex character in \x{} (closing brace missing?)
2473             80  non-octal character in \o{} (closing brace missing?)
2474             81  missing opening brace after \o
2475             82  parentheses are too deeply nested
2476             83  invalid range in character class
2477    
2478           The  numbers  32  and 10000 in errors 48 and 49 are defaults; different
2479           values may be used if the limits were changed when PCRE was built.
2480    
2481    
2482  STUDYING A PATTERN  STUDYING A PATTERN
2483    
2484         pcre_extra *pcre_study(const pcre *code, int options         pcre_extra *pcre_study(const pcre *code, int options,
2485              const char **errptr);              const char **errptr);
2486    
2487         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
# Line 1304  STUDYING A PATTERN Line 2493  STUDYING A PATTERN
2493         the results of the study.         the results of the study.
2494    
2495         The  returned  value  from  pcre_study()  can  be  passed  directly  to         The  returned  value  from  pcre_study()  can  be  passed  directly  to
2496         pcre_exec().  However,  a  pcre_extra  block also contains other fields         pcre_exec()  or  pcre_dfa_exec(). However, a pcre_extra block also con-
2497         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
2498         described below in the section on matching a pattern.         passed; these are described below in the section on matching a pattern.
2499    
2500         If  studying  the  pattern  does not produce any additional information         If  studying  the  pattern  does  not  produce  any useful information,
2501         pcre_study() returns NULL. In that circumstance, if the calling program         pcre_study() returns NULL by default.  In  that  circumstance,  if  the
2502         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
2503         its own pcre_extra block.         pcre_dfa_exec(), it must set up its own pcre_extra block.  However,  if
2504           pcre_study()  is  called  with  the  PCRE_STUDY_EXTRA_NEEDED option, it
2505         The second argument of pcre_study() contains option bits.  At  present,         returns a pcre_extra block even if studying did not find any additional
2506         no options are defined, and this argument should always be zero.         information.  It  may still return NULL, however, if an error occurs in
2507           pcre_study().
2508    
2509           The second argument of pcre_study() contains  option  bits.  There  are
2510           three further options in addition to PCRE_STUDY_EXTRA_NEEDED:
2511    
2512             PCRE_STUDY_JIT_COMPILE
2513             PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
2514             PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
2515    
2516           If  any  of  these are set, and the just-in-time compiler is available,
2517           the pattern is further compiled into machine code  that  executes  much
2518           faster  than  the  pcre_exec()  interpretive  matching function. If the
2519           just-in-time compiler is not available, these options are ignored.  All
2520           undefined bits in the options argument must be zero.
2521    
2522           JIT  compilation  is  a heavyweight optimization. It can take some time
2523           for patterns to be analyzed, and for one-off matches  and  simple  pat-
2524           terns  the benefit of faster execution might be offset by a much slower
2525           study time.  Not all patterns can be optimized by the JIT compiler. For
2526           those  that cannot be handled, matching automatically falls back to the
2527           pcre_exec() interpreter. For more details, see the  pcrejit  documenta-
2528           tion.
2529    
2530         The  third argument for pcre_study() is a pointer for an error message.         The  third argument for pcre_study() is a pointer for an error message.
2531         If studying succeeds (even if no data is  returned),  the  variable  it         If studying succeeds (even if no data is  returned),  the  variable  it
# Line 1323  STUDYING A PATTERN Line 2534  STUDYING A PATTERN
2534         must  not  try  to  free it. You should test the error pointer for NULL         must  not  try  to  free it. You should test the error pointer for NULL
2535         after calling pcre_study(), to be sure that it has run successfully.         after calling pcre_study(), to be sure that it has run successfully.
2536    
2537         This is a typical call to pcre_study():         When you are finished with a pattern, you can free the memory used  for
2538           the study data by calling pcre_free_study(). This function was added to
2539           the API for release 8.20. For earlier versions,  the  memory  could  be
2540           freed  with  pcre_free(), just like the pattern itself. This will still
2541           work in cases where JIT optimization is not used, but it  is  advisable
2542           to change to the new function when convenient.
2543    
2544           This  is  a typical way in which pcre_study() is used (except that in a
2545           real application there should be tests for errors):
2546    
2547           pcre_extra *pe;           int rc;
2548           pe = pcre_study(           pcre *re;
2549             pcre_extra *sd;
2550             re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
2551             sd = pcre_study(
2552             re,             /* result of pcre_compile() */             re,             /* result of pcre_compile() */
2553             0,              /* no options exist */             0,              /* no options */
2554             &error);        /* set to NULL or points to a message */             &error);        /* set to NULL or points to a message */
2555             rc = pcre_exec(   /* see below for details of pcre_exec() options */
2556               re, sd, "subject", 7, 0, 0, ovector, 30);
2557             ...
2558             pcre_free_study(sd);
2559             pcre_free(re);
2560    
2561           Studying a pattern does two things: first, a lower bound for the length
2562           of subject string that is needed to match the pattern is computed. This
2563           does not mean that there are any strings of that length that match, but
2564           it  does  guarantee that no shorter strings match. The value is used to
2565           avoid wasting time by trying to match strings that are shorter than the
2566           lower  bound.  You  can find out the value in a calling program via the
2567           pcre_fullinfo() function.
2568    
2569           Studying a pattern is also useful for non-anchored patterns that do not
2570           have  a  single fixed starting character. A bitmap of possible starting
2571           bytes is created. This speeds up finding a position in the  subject  at
2572           which to start matching. (In 16-bit mode, the bitmap is used for 16-bit
2573           values less than 256.  In 32-bit mode, the bitmap is  used  for  32-bit
2574           values less than 256.)
2575    
2576           These  two optimizations apply to both pcre_exec() and pcre_dfa_exec(),
2577           and the information is also used by the JIT  compiler.   The  optimiza-
2578           tions  can  be  disabled  by setting the PCRE_NO_START_OPTIMIZE option.
2579           You might want to do this if your pattern contains callouts or  (*MARK)
2580           and  you  want  to make use of these facilities in cases where matching
2581           fails.
2582    
2583           PCRE_NO_START_OPTIMIZE can be specified at either compile time or  exe-
2584           cution   time.   However,   if   PCRE_NO_START_OPTIMIZE  is  passed  to
2585           pcre_exec(), (that is, after any JIT compilation has happened) JIT exe-
2586           cution  is disabled. For JIT execution to work with PCRE_NO_START_OPTI-
2587           MIZE, the option must be set at compile time.
2588    
2589         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.  
2590    
2591    
2592  LOCALE SUPPORT  LOCALE SUPPORT
2593    
2594         PCRE handles caseless matching, and determines whether  characters  are         PCRE handles caseless matching, and determines whether  characters  are
2595         letters,  digits, or whatever, by reference to a set of tables, indexed         letters,  digits, or whatever, by reference to a set of tables, indexed
2596         by character value. When running in UTF-8 mode, this  applies  only  to         by character code point. When running in UTF-8 mode, or in the  16-  or
2597         characters  with  codes  less than 128. Higher-valued codes never match         32-bit libraries, this applies only to characters with code points less
2598         escapes such as \w or \d, but can be tested with \p if  PCRE  is  built         than 256. By default, higher-valued code  points  never  match  escapes
2599         with  Unicode  character property support. The use of locales with Uni-         such  as \w or \d. However, if PCRE is built with Unicode property sup-
2600         code is discouraged. If you are handling characters with codes  greater         port, all characters can be tested with \p and \P,  or,  alternatively,
2601         than  128, you should either use UTF-8 and Unicode, or use locales, but         the  PCRE_UCP option can be set when a pattern is compiled; this causes
2602         not try to mix the two.         \w and friends to use Unicode property support instead of the  built-in
2603           tables.
2604    
2605           The  use  of  locales  with Unicode is discouraged. If you are handling
2606           characters with code points greater than 128,  you  should  either  use
2607           Unicode support, or use locales, but not try to mix the two.
2608    
2609         PCRE contains an internal set of tables that are used  when  the  final         PCRE  contains  an  internal set of tables that are used when the final
2610         argument  of  pcre_compile()  is  NULL.  These  are sufficient for many         argument of pcre_compile() is  NULL.  These  are  sufficient  for  many
2611         applications.  Normally, the internal tables recognize only ASCII char-         applications.  Normally, the internal tables recognize only ASCII char-
2612         acters. However, when PCRE is built, it is possible to cause the inter-         acters. However, when PCRE is built, it is possible to cause the inter-
2613         nal tables to be rebuilt in the default "C" locale of the local system,         nal tables to be rebuilt in the default "C" locale of the local system,
2614         which may cause them to be different.         which may cause them to be different.
2615    
2616         The  internal tables can always be overridden by tables supplied by the         The internal tables can always be overridden by tables supplied by  the
2617         application that calls PCRE. These may be created in a different locale         application that calls PCRE. These may be created in a different locale
2618         from  the  default.  As more and more applications change to using Uni-         from the default. As more and more applications change  to  using  Uni-
2619         code, the need for this locale support is expected to die away.         code, the need for this locale support is expected to die away.
2620    
2621         External tables are built by calling  the  pcre_maketables()  function,         External  tables  are  built by calling the pcre_maketables() function,
2622         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
2623         passed to pcre_compile() or pcre_exec()  as  often  as  necessary.  For         passed  to  pcre_compile() as often as necessary. For example, to build
2624         example,  to  build  and use tables that are appropriate for the French         and use tables that  are  appropriate  for  the  French  locale  (where
2625         locale (where accented characters with  values  greater  than  128  are         accented  characters  with  values greater than 128 are treated as let-
2626         treated as letters), the following code could be used:         ters), the following code could be used:
2627    
2628           setlocale(LC_CTYPE, "fr_FR");           setlocale(LC_CTYPE, "fr_FR");
2629           tables = pcre_maketables();           tables = pcre_maketables();
2630           re = pcre_compile(..., tables);           re = pcre_compile(..., tables);
2631    
2632         The  locale  name "fr_FR" is used on Linux and other Unix-like systems;         The locale name "fr_FR" is used on Linux and other  Unix-like  systems;
2633         if you are using Windows, the name for the French locale is "french".         if you are using Windows, the name for the French locale is "french".
2634    
2635         When pcre_maketables() runs, the tables are built  in  memory  that  is         When  pcre_maketables()  runs,  the  tables are built in memory that is
2636         obtained  via  pcre_malloc. It is the caller's responsibility to ensure         obtained via pcre_malloc. It is the caller's responsibility  to  ensure
2637         that the memory containing the tables remains available for as long  as         that  the memory containing the tables remains available for as long as
2638         it is needed.         it is needed.
2639    
2640         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
2641         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()
2642         and normally also by pcre_exec(). Thus, by default, for any single pat-         and also by pcre_exec() and pcre_dfa_exec(). Thus, for any single  pat-
2643         tern, compilation, studying and matching all happen in the same locale,         tern, compilation, studying and matching all happen in the same locale,
2644         but different patterns can be compiled in different locales.         but different patterns can be processed in different locales.
2645    
2646         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
2647         the internal tables) to pcre_exec(). Although  not  intended  for  this         the internal tables) to pcre_exec() or pcre_dfa_exec() (see the discus-
2648         purpose,  this facility could be used to match a pattern in a different         sion below in the section on matching a pattern). This facility is pro-
2649         locale from the one in which it was compiled. Passing table pointers at         vided  for  use  with  pre-compiled  patterns  that have been saved and
2650         run time is discussed below in the section on matching a pattern.         reloaded.  Character tables are not saved with patterns, so if  a  non-
2651           standard table was used at compile time, it must be provided again when
2652           the reloaded pattern is matched. Attempting to  use  this  facility  to
2653           match a pattern in a different locale from the one in which it was com-
2654           piled is likely to lead to anomalous (usually incorrect) results.
2655    
2656    
2657  INFORMATION ABOUT A PATTERN  INFORMATION ABOUT A PATTERN
# Line 1397  INFORMATION ABOUT A PATTERN Line 2659  INFORMATION ABOUT A PATTERN
2659         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
2660              int what, void *where);              int what, void *where);
2661    
2662         The  pcre_fullinfo() function returns information about a compiled pat-         The pcre_fullinfo() function returns information about a compiled  pat-
2663         tern. It replaces the obsolete pcre_info() function, which is neverthe-         tern.  It replaces the pcre_info() function, which was removed from the
2664         less retained for backwards compability (and is documented below).         library at version 8.30, after more than 10 years of obsolescence.
2665    
2666         The  first  argument  for  pcre_fullinfo() is a pointer to the compiled         The first argument for pcre_fullinfo() is a  pointer  to  the  compiled
2667         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
2668         the  pattern  was not studied. The third argument specifies which piece         the pattern was not studied. The third argument specifies  which  piece
2669         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
2670         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
2671         success, or one of the following negative numbers:         success, or one of the following negative numbers:
2672    
2673           PCRE_ERROR_NULL       the argument code was NULL           PCRE_ERROR_NULL           the argument code was NULL
2674                                 the argument where was NULL                                     the argument where was NULL
2675           PCRE_ERROR_BADMAGIC   the "magic number" was not found           PCRE_ERROR_BADMAGIC       the "magic number" was not found
2676           PCRE_ERROR_BADOPTION  the value of what was invalid           PCRE_ERROR_BADENDIANNESS  the pattern was compiled with different
2677                                       endianness
2678         The "magic number" is placed at the start of each compiled  pattern  as           PCRE_ERROR_BADOPTION      the value of what was invalid
2679         an  simple check against passing an arbitrary memory pointer. Here is a           PCRE_ERROR_UNSET          the requested field is not set
2680         typical call of pcre_fullinfo(), to obtain the length of  the  compiled  
2681         pattern:         The  "magic  number" is placed at the start of each compiled pattern as
2682           an simple check against passing an arbitrary memory pointer. The  endi-
2683           anness error can occur if a compiled pattern is saved and reloaded on a
2684           different host. Here is a typical call of  pcre_fullinfo(),  to  obtain
2685           the length of the compiled pattern:
2686    
2687           int rc;           int rc;
2688           size_t length;           size_t length;
2689           rc = pcre_fullinfo(           rc = pcre_fullinfo(
2690             re,               /* result of pcre_compile() */             re,               /* result of pcre_compile() */
2691             pe,               /* result of pcre_study(), or NULL */             sd,               /* result of pcre_study(), or NULL */
2692             PCRE_INFO_SIZE,   /* what is required */             PCRE_INFO_SIZE,   /* what is required */
2693             &length);         /* where to put the data */             &length);         /* where to put the data */
2694    
# Line 1450  INFORMATION ABOUT A PATTERN Line 2716  INFORMATION ABOUT A PATTERN
2716    
2717           PCRE_INFO_FIRSTBYTE           PCRE_INFO_FIRSTBYTE
2718    
2719         Return  information  about  the first byte of any matched string, for a         Return information about the first data unit of any matched string, for
2720         non-anchored pattern. The fourth argument should point to an int  vari-         a non-anchored pattern. (The name of this option refers  to  the  8-bit
2721         able.  (This option used to be called PCRE_INFO_FIRSTCHAR; the old name         library,  where data units are bytes.) The fourth argument should point
2722         is still recognized for backwards compatibility.)         to an int variable.
2723    
2724           If there is a fixed first value, for example, the  letter  "c"  from  a
2725           pattern  such  as (cat|cow|coyote), its value is returned. In the 8-bit
2726           library, the value is always less than 256. In the 16-bit  library  the
2727           value can be up to 0xffff. In the 32-bit library the value can be up to
2728           0x10ffff.
2729    
2730         If there is a fixed first byte, for example, from  a  pattern  such  as         If there is no fixed first value, and if either
        (cat|cow|coyote), its value is returned. Otherwise, if either  
2731    
2732         (a)  the pattern was compiled with the PCRE_MULTILINE option, and every         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
2733         branch starts with "^", or         branch starts with "^", or
2734    
2735         (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not         (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2736         set (if it were set, the pattern would be anchored),         set (if it were set, the pattern would be anchored),
2737    
2738         -1  is  returned, indicating that the pattern matches only at the start         -1 is returned, indicating that the pattern matches only at  the  start
2739         of a subject string or after any newline within the  string.  Otherwise         of  a  subject string or after any newline within the string. Otherwise
2740         -2 is returned. For anchored patterns, -2 is returned.         -2 is returned. For anchored patterns, -2 is returned.
2741    
2742           Since for the 32-bit library using the non-UTF-32 mode,  this  function
2743           is  unable to return the full 32-bit range of the character, this value
2744           is   deprecated;   instead   the   PCRE_INFO_FIRSTCHARACTERFLAGS    and
2745           PCRE_INFO_FIRSTCHARACTER values should be used.
2746    
2747           PCRE_INFO_FIRSTTABLE           PCRE_INFO_FIRSTTABLE
2748    
2749         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
2750         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
2751         matching  string, a pointer to the table is returned. Otherwise NULL is         in  any  matching string, a pointer to the table is returned. Otherwise
2752         returned. The fourth argument should point to an unsigned char *  vari-         NULL is returned. The fourth argument should point to an unsigned  char
2753         able.         * variable.
2754    
2755             PCRE_INFO_HASCRORLF
2756    
2757           Return  1  if  the  pattern  contains any explicit matches for CR or LF
2758           characters, otherwise 0. The fourth argument should  point  to  an  int
2759           variable.  An explicit match is either a literal CR or LF character, or
2760           \r or \n.
2761    
2762           PCRE_INFO_JCHANGED           PCRE_INFO_JCHANGED
2763    
2764         Return  1  if the (?J) option setting is used in the pattern, otherwise         Return 1 if the (?J) or (?-J) option setting is used  in  the  pattern,
2765         0. The fourth argument should point to an int variable. The (?J) inter-         otherwise  0. The fourth argument should point to an int variable. (?J)
2766         nal option setting changes the local PCRE_DUPNAMES value.         and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
2767    
2768             PCRE_INFO_JIT
2769    
2770           Return 1 if the pattern was studied with one of the  JIT  options,  and
2771           just-in-time compiling was successful. The fourth argument should point
2772           to an int variable. A return value of 0 means that JIT support  is  not
2773           available  in this version of PCRE, or that the pattern was not studied
2774           with a JIT option, or that the JIT compiler could not handle this  par-
2775           ticular  pattern. See the pcrejit documentation for details of what can
2776           and cannot be handled.
2777    
2778             PCRE_INFO_JITSIZE
2779    
2780           If the pattern was successfully studied with a JIT option,  return  the
2781           size  of the JIT compiled code, otherwise return zero. The fourth argu-
2782           ment should point to a size_t variable.
2783    
2784           PCRE_INFO_LASTLITERAL           PCRE_INFO_LASTLITERAL
2785    
2786         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
2787         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
2788         recorded. The fourth argument should point to an int variable. If there         recorded. The fourth argument should point to an int variable. If there
2789         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
2790         byte  is  recorded only if it follows something of variable length. For         value is recorded only if it follows something of variable length.  For
2791         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
2792         /^a\dz\d/ the returned value is -1.         /^a\dz\d/ the returned value is -1.
2793    
2794           Since for the 32-bit library using the non-UTF-32 mode,  this  function
2795           is  unable to return the full 32-bit range of characters, this value is
2796           deprecated;     instead     the     PCRE_INFO_REQUIREDCHARFLAGS     and
2797           PCRE_INFO_REQUIREDCHAR values should be used.
2798    
2799             PCRE_INFO_MATCH_EMPTY
2800    
2801           Return  1  if  the  pattern can match an empty string, otherwise 0. The
2802           fourth argument should point to an int variable.
2803    
2804             PCRE_INFO_MATCHLIMIT
2805    
2806           If the pattern set a match limit by  including  an  item  of  the  form
2807           (*LIMIT_MATCH=nnnn)  at  the  start,  the value is returned. The fourth
2808           argument should point to an unsigned 32-bit integer. If no  such  value
2809           has   been   set,   the  call  to  pcre_fullinfo()  returns  the  error
2810           PCRE_ERROR_UNSET.
2811    
2812             PCRE_INFO_MAXLOOKBEHIND
2813    
2814           Return the number of characters (NB not  data  units)  in  the  longest
2815           lookbehind  assertion  in  the pattern. This information is useful when
2816           doing multi-segment matching using  the  partial  matching  facilities.
2817           Note that the simple assertions \b and \B require a one-character look-
2818           behind. \A also registers a one-character lookbehind,  though  it  does
2819           not  actually inspect the previous character. This is to ensure that at
2820           least one character from the old segment is retained when a new segment
2821           is processed. Otherwise, if there are no lookbehinds in the pattern, \A
2822           might match incorrectly at the start of a new segment.
2823    
2824             PCRE_INFO_MINLENGTH
2825    
2826           If the pattern was studied and a minimum length  for  matching  subject
2827           strings  was  computed,  its  value is returned. Otherwise the returned
2828           value is -1. The value is a number of characters, which in UTF mode may
2829           be  different from the number of data units. The fourth argument should
2830           point to an int variable. A non-negative value is a lower bound to  the
2831           length  of  any  matching  string. There may not be any strings of that
2832           length that do actually match, but every string that does match  is  at
2833           least that long.
2834    
2835           PCRE_INFO_NAMECOUNT           PCRE_INFO_NAMECOUNT
2836           PCRE_INFO_NAMEENTRYSIZE           PCRE_INFO_NAMEENTRYSIZE
2837           PCRE_INFO_NAMETABLE           PCRE_INFO_NAMETABLE
# Line 1510  INFORMATION ABOUT A PATTERN Line 2850  INFORMATION ABOUT A PATTERN
2850         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size
2851         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
2852         depends on the length of the longest name. PCRE_INFO_NAMETABLE  returns         depends on the length of the longest name. PCRE_INFO_NAMETABLE  returns
2853         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
2854         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-
2855         sis,  most  significant byte first. The rest of the entry is the corre-         ber  of  the capturing parenthesis, most significant byte first. In the
2856         sponding name, zero terminated. The names are  in  alphabetical  order.         16-bit library, the pointer points to 16-bit data units, the  first  of
2857         When PCRE_DUPNAMES is set, duplicate names are in order of their paren-         which  contains  the  parenthesis  number.  In  the 32-bit library, the
2858         theses numbers. For example, consider  the  following  pattern  (assume         pointer points to 32-bit data units, the first of  which  contains  the
2859         PCRE_EXTENDED  is  set,  so  white  space  -  including  newlines  - is         parenthesis  number.  The  rest of the entry is the corresponding name,
2860         ignored):         zero terminated.
2861    
2862           The names are in alphabetical order. If (?| is used to create  multiple
2863           groups  with  the same number, as described in the section on duplicate
2864           subpattern numbers in the pcrepattern page, the groups may be given the
2865           same  name,  but  there is only one entry in the table. Different names
2866           for groups of the same number are not permitted.  Duplicate  names  for
2867           subpatterns with different numbers are permitted, but only if PCRE_DUP-
2868           NAMES is set. They appear in the table in the order in which they  were
2869           found  in  the  pattern.  In  the  absence  of (?| this is the order of
2870           increasing number; when (?| is used this is not  necessarily  the  case
2871           because later subpatterns may have lower numbers.
2872    
2873           As  a  simple  example of the name/number table, consider the following
2874           pattern after compilation by the 8-bit library (assume PCRE_EXTENDED is
2875           set, so white space - including newlines - is ignored):
2876    
2877           (?<date> (?<year>(\d\d)?\d\d) -           (?<date> (?<year>(\d\d)?\d\d) -
2878           (?<month>\d\d) - (?<day>\d\d) )           (?<month>\d\d) - (?<day>\d\d) )
2879    
2880         There are four named subpatterns, so the table has  four  entries,  and         There  are  four  named subpatterns, so the table has four entries, and
2881         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,
2882         with non-printing bytes shows in hexadecimal, and undefined bytes shown         with non-printing bytes shows in hexadecimal, and undefined bytes shown
2883         as ??:         as ??:
2884    
# Line 1532  INFORMATION ABOUT A PATTERN Line 2887  INFORMATION ABOUT A PATTERN
2887           00 04 m  o  n  t  h  00           00 04 m  o  n  t  h  00
2888           00 02 y  e  a  r  00 ??           00 02 y  e  a  r  00 ??
2889    
2890         When  writing  code  to  extract  data from named subpatterns using the         When writing code to extract data  from  named  subpatterns  using  the
2891         name-to-number map, remember that the length of the entries  is  likely         name-to-number  map,  remember that the length of the entries is likely
2892         to be different for each compiled pattern.         to be different for each compiled pattern.
2893    
2894           PCRE_INFO_OKPARTIAL           PCRE_INFO_OKPARTIAL
2895    
2896         Return  1 if the pattern can be used for partial matching, otherwise 0.         Return 1  if  the  pattern  can  be  used  for  partial  matching  with
2897         The fourth argument should point to an int  variable.  The  pcrepartial         pcre_exec(),  otherwise  0.  The fourth argument should point to an int
2898         documentation  lists  the restrictions that apply to patterns when par-         variable. From  release  8.00,  this  always  returns  1,  because  the
2899         tial matching is used.         restrictions  that  previously  applied  to  partial matching have been
2900           lifted. The pcrepartial documentation gives details of  partial  match-
2901           ing.
2902    
2903           PCRE_INFO_OPTIONS           PCRE_INFO_OPTIONS
2904    
2905         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
2906         fourth  argument  should  point to an unsigned long int variable. These         fourth argument should point to an unsigned long  int  variable.  These
2907         option bits are those specified in the call to pcre_compile(), modified         option bits are those specified in the call to pcre_compile(), modified
2908         by any top-level option settings within the pattern itself.         by any top-level option settings at the start of the pattern itself. In
2909           other  words,  they are the options that will be in force when matching
2910           starts. For example, if the pattern /(?im)abc(?-i)d/ is  compiled  with
2911           the  PCRE_EXTENDED option, the result is PCRE_CASELESS, PCRE_MULTILINE,
2912           and PCRE_EXTENDED.
2913    
2914         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
2915         alternatives begin with one of the following:         alternatives begin with one of the following:
2916    
2917           ^     unless PCRE_MULTILINE is set           ^     unless PCRE_MULTILINE is set
# Line 1562  INFORMATION ABOUT A PATTERN Line 2923  INFORMATION ABOUT A PATTERN
2923         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
2924         by pcre_fullinfo().         by pcre_fullinfo().
2925    
2926             PCRE_INFO_RECURSIONLIMIT
2927    
2928           If the pattern set a recursion limit by including an item of  the  form
2929           (*LIMIT_RECURSION=nnnn) at the start, the value is returned. The fourth
2930           argument should point to an unsigned 32-bit integer. If no  such  value
2931           has   been   set,   the  call  to  pcre_fullinfo()  returns  the  error
2932           PCRE_ERROR_UNSET.
2933    
2934           PCRE_INFO_SIZE           PCRE_INFO_SIZE
2935    
2936         Return  the  size  of the compiled pattern, that is, the value that was         Return the size of  the  compiled  pattern  in  bytes  (for  all  three
2937         passed as the argument to pcre_malloc() when PCRE was getting memory in         libraries). The fourth argument should point to a size_t variable. This
2938         which to place the compiled data. The fourth argument should point to a         value does not include the size of the pcre structure that is  returned
2939         size_t variable.         by  pcre_compile().  The  value  that  is  passed  as  the  argument to
2940           pcre_malloc() when pcre_compile() is getting memory in which  to  place
2941           the compiled data is the value returned by this option plus the size of
2942           the pcre structure. Studying a compiled pattern, with or  without  JIT,
2943           does not alter the value returned by this option.
2944    
2945           PCRE_INFO_STUDYSIZE           PCRE_INFO_STUDYSIZE
2946    
2947         Return the size of the data block pointed to by the study_data field in         Return  the  size  in bytes (for all three libraries) of the data block
2948         a  pcre_extra  block.  That  is,  it  is  the  value that was passed to         pointed to by the study_data field in a pcre_extra block. If pcre_extra
2949         pcre_malloc() when PCRE was getting memory into which to place the data         is  NULL, or there is no study data, zero is returned. The fourth argu-
2950         created  by  pcre_study(). The fourth argument should point to a size_t         ment should point to a size_t variable. The study_data field is set  by
2951           pcre_study() to record information that will speed up matching (see the
2952           section entitled  "Studying  a  pattern"  above).  The  format  of  the
2953           study_data  block is private, but its length is made available via this
2954           option so that it can be saved and  restored  (see  the  pcreprecompile
2955           documentation for details).
2956    
2957             PCRE_INFO_FIRSTCHARACTERFLAGS
2958    
2959           Return information about the first data unit of any matched string, for
2960           a non-anchored pattern. The fourth argument  should  point  to  an  int
2961         variable.         variable.
2962    
2963           If  there  is  a  fixed first value, for example, the letter "c" from a
2964           pattern such as (cat|cow|coyote), 1  is  returned,  and  the  character
2965           value can be retrieved using PCRE_INFO_FIRSTCHARACTER.
2966    
2967  OBSOLETE INFO FUNCTION         If there is no fixed first value, and if either
2968    
2969         int pcre_info(const pcre *code, int *optptr, int *firstcharptr);         (a)  the pattern was compiled with the PCRE_MULTILINE option, and every
2970           branch starts with "^", or
2971    
2972           (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2973           set (if it were set, the pattern would be anchored),
2974    
2975         The pcre_info() function is now obsolete because its interface  is  too         2 is returned, indicating that the pattern matches only at the start of
2976         restrictive  to return all the available data about a compiled pattern.         a subject string or after any newline within the string. Otherwise 0 is
2977         New  programs  should  use  pcre_fullinfo()  instead.  The   yield   of         returned. For anchored patterns, 0 is returned.
2978         pcre_info()  is the number of capturing subpatterns, or one of the fol-  
2979         lowing negative numbers:           PCRE_INFO_FIRSTCHARACTER
2980    
2981           PCRE_ERROR_NULL       the argument code was NULL         Return   the  fixed  first  character  value  in  the  situation  where
2982           PCRE_ERROR_BADMAGIC   the "magic number" was not found         PCRE_INFO_FIRSTCHARACTERFLAGS returns 1; otherwise return 0. The fourth
2983           argument should point to an uint_t variable.
2984         If the optptr argument is not NULL, a copy of the  options  with  which  
2985         the  pattern  was  compiled  is placed in the integer it points to (see         In  the 8-bit library, the value is always less than 256. In the 16-bit
2986         PCRE_INFO_OPTIONS above).         library the value can be up to 0xffff. In the 32-bit library in  UTF-32
2987           mode  the  value  can  be up to 0x10ffff, and up to 0xffffffff when not
2988         If the pattern is not anchored and the  firstcharptr  argument  is  not         using UTF-32 mode.
2989         NULL,  it is used to pass back information about the first character of  
2990         any matched string (see PCRE_INFO_FIRSTBYTE above).           PCRE_INFO_REQUIREDCHARFLAGS
2991    
2992           Returns 1 if there is a rightmost literal data unit that must exist  in
2993           any matched string, other than at its start. The fourth argument should
2994           point to an int variable. If there is no such value, 0 is returned.  If
2995           returning  1,  the  character  value  itself  can  be  retrieved  using
2996           PCRE_INFO_REQUIREDCHAR.
2997    
2998           For anchored patterns, a last literal value is recorded only if it fol-
2999           lows  something  of  variable  length.  For  example,  for  the pattern
3000           /^a\d+z\d+/  the   returned   value   1   (with   "z"   returned   from
3001           PCRE_INFO_REQUIREDCHAR), but for /^a\dz\d/ the returned value is 0.
3002    
3003             PCRE_INFO_REQUIREDCHAR
3004    
3005           Return  the value of the rightmost literal data unit that must exist in
3006           any matched string, other than at its start, if such a value  has  been
3007           recorded.  The fourth argument should point to an uint32_t variable. If
3008           there is no such value, 0 is returned.
3009    
3010    
3011  REFERENCE COUNTS  REFERENCE COUNTS
# Line 1628  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3036  MATCHING A PATTERN: THE TRADITIONAL FUNC
3036              const char *subject, int length, int startoffset,              const char *subject, int length, int startoffset,
3037              int options, int *ovector, int ovecsize);              int options, int *ovector, int ovecsize);
3038    
3039         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
3040         compiled  pattern, which is passed in the code argument. If the pattern         compiled pattern, which is passed in the code argument. If the  pattern
3041         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
3042         argument.  This  function is the main matching facility of the library,         argument. You can call pcre_exec() with the same code and  extra  argu-
3043         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
3044         an  alternative matching function, which is described below in the sec-         strings with the same pattern.
3045         tion about the pcre_dfa_exec() function.  
3046           This function is the main matching facility  of  the  library,  and  it
3047           operates  in  a  Perl-like  manner. For specialist use there is also an
3048           alternative matching function, which is described below in the  section
3049           about the pcre_dfa_exec() function.
3050    
3051         In most applications, the pattern will have been compiled (and  option-         In  most applications, the pattern will have been compiled (and option-
3052         ally  studied)  in the same process that calls pcre_exec(). However, it         ally studied) in the same process that calls pcre_exec().  However,  it
3053         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
3054         later  in  different processes, possibly even on different hosts. For a         later in different processes, possibly even on different hosts.  For  a
3055         discussion about this, see the pcreprecompile documentation.         discussion about this, see the pcreprecompile documentation.
3056    
3057         Here is an example of a simple call to pcre_exec():         Here is an example of a simple call to pcre_exec():
# Line 1658  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3070  MATCHING A PATTERN: THE TRADITIONAL FUNC
3070    
3071     Extra data for pcre_exec()     Extra data for pcre_exec()
3072    
3073         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
3074         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
3075         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-
3076         tional  information  in it. The pcre_extra block contains the following         tional information in it. The pcre_extra block contains  the  following
3077         fields (not necessarily in this order):         fields (not necessarily in this order):
3078    
3079           unsigned long int flags;           unsigned long int flags;
3080           void *study_data;           void *study_data;
3081             void *executable_jit;
3082           unsigned long int match_limit;           unsigned long int match_limit;
3083           unsigned long int match_limit_recursion;           unsigned long int match_limit_recursion;
3084           void *callout_data;           void *callout_data;
3085           const unsigned char *tables;           const unsigned char *tables;
3086             unsigned char **mark;
3087    
3088         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
3089         are set. The flag bits are:         "PCRE_UCHAR16 **".
3090    
3091           PCRE_EXTRA_STUDY_DATA         In the 32-bit version of  this  structure,  the  mark  field  has  type
3092           "PCRE_UCHAR32 **".
3093    
3094           The  flags  field is used to specify which of the other fields are set.
3095           The flag bits are:
3096    
3097             PCRE_EXTRA_CALLOUT_DATA
3098             PCRE_EXTRA_EXECUTABLE_JIT
3099             PCRE_EXTRA_MARK
3100           PCRE_EXTRA_MATCH_LIMIT           PCRE_EXTRA_MATCH_LIMIT
3101           PCRE_EXTRA_MATCH_LIMIT_RECURSION           PCRE_EXTRA_MATCH_LIMIT_RECURSION
3102           PCRE_EXTRA_CALLOUT_DATA           PCRE_EXTRA_STUDY_DATA
3103           PCRE_EXTRA_TABLES           PCRE_EXTRA_TABLES
3104    
3105         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-
3106         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
3107         the appropriate flag bit. You should not set this yourself, but you may         returned by pcre_study(), together with the appropriate flag bits.  You
3108         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
3109         flag bits.         other fields and their corresponding flag bits.
3110    
3111         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
3112         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
3113         match,  but  which  have  a very large number of possibilities in their         match, but which have a very large number  of  possibilities  in  their
3114         search trees. The classic  example  is  the  use  of  nested  unlimited         search  trees. The classic example is a pattern that uses nested unlim-
3115         repeats.         ited repeats.
3116    
3117         Internally,  PCRE uses a function called match() which it calls repeat-         Internally, pcre_exec() uses a function called match(), which it  calls
3118         edly (sometimes recursively). The limit set by match_limit  is  imposed         repeatedly  (sometimes  recursively).  The  limit set by match_limit is
3119         on  the  number  of times this function is called during a match, which         imposed on the number of times this function is called during a  match,
3120         has the effect of limiting the amount of  backtracking  that  can  take         which  has  the  effect of limiting the amount of backtracking that can
3121         place. For patterns that are not anchored, the count restarts from zero         take place. For patterns that are not anchored, the count restarts from
3122         for each position in the subject string.         zero for each position in the subject string.
3123    
3124           When pcre_exec() is called with a pattern that was successfully studied
3125           with a JIT option, the way that the matching is  executed  is  entirely
3126           different.  However, there is still the possibility of runaway matching
3127           that goes on for a very long time, and so the match_limit value is also
3128           used in this case (but in a different way) to limit how long the match-
3129           ing can continue.
3130    
3131         The default value for the limit can be set  when  PCRE  is  built;  the         The default value for the limit can be set  when  PCRE  is  built;  the
3132         default  default  is 10 million, which handles all but the most extreme         default  default  is 10 million, which handles all but the most extreme
# Line 1706  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3135  MATCHING A PATTERN: THE TRADITIONAL FUNC
3135         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
3136         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
3137    
3138         The  match_limit_recursion field is similar to match_limit, but instead         A  value  for  the  match  limit may also be supplied by an item at the
3139           start of a pattern of the form
3140    
3141             (*LIMIT_MATCH=d)
3142    
3143           where d is a decimal number. However, such a setting is ignored  unless
3144           d  is  less  than  the limit set by the caller of pcre_exec() or, if no
3145           such limit is set, less than the default.
3146    
3147           The match_limit_recursion field is similar to match_limit, but  instead
3148         of limiting the total number of times that match() is called, it limits         of limiting the total number of times that match() is called, it limits
3149         the  depth  of  recursion. The recursion depth is a smaller number than         the depth of recursion. The recursion depth is a  smaller  number  than
3150         the total number of calls, because not all calls to match() are  recur-         the  total number of calls, because not all calls to match() are recur-
3151         sive.  This limit is of use only if it is set smaller than match_limit.         sive.  This limit is of use only if it is set smaller than match_limit.
3152    
3153         Limiting the recursion depth limits the amount of  stack  that  can  be         Limiting the recursion depth limits the amount of  machine  stack  that
3154         used, or, when PCRE has been compiled to use memory on the heap instead         can  be used, or, when PCRE has been compiled to use memory on the heap
3155         of the stack, the amount of heap memory that can be used.         instead of the stack, the amount of heap memory that can be used.  This
3156           limit  is not relevant, and is ignored, when matching is done using JIT
3157           compiled code.
3158    
3159         The default value for match_limit_recursion can be  set  when  PCRE  is         The default value for match_limit_recursion can be  set  when  PCRE  is
3160         built;  the  default  default  is  the  same  value  as the default for         built;  the  default  default  is  the  same  value  as the default for
# Line 1723  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3163  MATCHING A PATTERN: THE TRADITIONAL FUNC
3163         PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in  the  flags  field.  If  the         PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in  the  flags  field.  If  the
3164         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.
3165    
3166         The  pcre_callout  field is used in conjunction with the "callout" fea-         A  value for the recursion limit may also be supplied by an item at the
3167         ture, which is described in the pcrecallout documentation.         start of a pattern of the form
3168    
3169         The tables field  is  used  to  pass  a  character  tables  pointer  to           (*LIMIT_RECURSION=d)
3170         pcre_exec();  this overrides the value that is stored with the compiled  
3171         pattern. A non-NULL value is stored with the compiled pattern  only  if         where d is a decimal number. However, such a setting is ignored  unless
3172         custom  tables  were  supplied to pcre_compile() via its tableptr argu-         d  is  less  than  the limit set by the caller of pcre_exec() or, if no
3173         ment.  If NULL is passed to pcre_exec() using this mechanism, it forces         such limit is set, less than the default.
3174         PCRE's  internal  tables  to be used. This facility is helpful when re-  
3175         using patterns that have been saved after compiling  with  an  external         The callout_data field is used in conjunction with the  "callout"  fea-
3176         set  of  tables,  because  the  external tables might be at a different         ture, and is described in the pcrecallout documentation.
3177         address when pcre_exec() is called. See the  pcreprecompile  documenta-  
3178         tion for a discussion of saving compiled patterns for later use.         The  tables field is provided for use with patterns that have been pre-
3179           compiled using custom character tables, saved to disc or elsewhere, and
3180           then  reloaded,  because the tables that were used to compile a pattern
3181           are not saved with it. See the pcreprecompile documentation for a  dis-
3182           cussion  of  saving  compiled patterns for later use. If NULL is passed
3183           using this mechanism, it forces PCRE's internal tables to be used.
3184    
3185           Warning: The tables that pcre_exec() uses must be  the  same  as  those
3186           that  were used when the pattern was compiled. If this is not the case,
3187           the behaviour of pcre_exec() is undefined. Therefore, when a pattern is
3188           compiled  and  matched  in the same process, this field should never be
3189           set. In this (the most common) case, the correct table pointer is auto-
3190           matically  passed  with  the  compiled  pattern  from pcre_compile() to
3191           pcre_exec().
3192    
3193           If PCRE_EXTRA_MARK is set in the flags field, the mark  field  must  be
3194           set  to point to a suitable variable. If the pattern contains any back-
3195           tracking control verbs such as (*MARK:NAME), and the execution ends  up
3196           with  a  name  to  pass back, a pointer to the name string (zero termi-
3197           nated) is placed in the variable pointed to  by  the  mark  field.  The
3198           names  are  within  the  compiled pattern; if you wish to retain such a
3199           name you must copy it before freeing the memory of a compiled  pattern.
3200           If  there  is no name to pass back, the variable pointed to by the mark
3201           field is set to NULL. For details of the  backtracking  control  verbs,
3202           see the section entitled "Backtracking control" in the pcrepattern doc-
3203           umentation.
3204    
3205     Option bits for pcre_exec()     Option bits for pcre_exec()
3206    
3207         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.
3208         The only bits that may  be  set  are  PCRE_ANCHORED,  PCRE_NEWLINE_xxx,         The  only  bits  that  may  be set are PCRE_ANCHORED, PCRE_NEWLINE_xxx,
3209         PCRE_NOTBOL,   PCRE_NOTEOL,   PCRE_NOTEMPTY,   PCRE_NO_UTF8_CHECK   and         PCRE_NOTBOL,   PCRE_NOTEOL,    PCRE_NOTEMPTY,    PCRE_NOTEMPTY_ATSTART,
3210         PCRE_PARTIAL.         PCRE_NO_START_OPTIMIZE,   PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_HARD,  and
3211           PCRE_PARTIAL_SOFT.
3212    
3213           If the pattern was successfully studied with one  of  the  just-in-time
3214           (JIT) compile options, the only supported options for JIT execution are
3215           PCRE_NO_UTF8_CHECK,    PCRE_NOTBOL,     PCRE_NOTEOL,     PCRE_NOTEMPTY,
3216           PCRE_NOTEMPTY_ATSTART,  PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an
3217           unsupported option is used, JIT execution is disabled  and  the  normal
3218           interpretive code in pcre_exec() is run.
3219    
3220           PCRE_ANCHORED           PCRE_ANCHORED
3221    
3222         The PCRE_ANCHORED option limits pcre_exec() to matching  at  the  first         The  PCRE_ANCHORED  option  limits pcre_exec() to matching at the first
3223         matching  position.  If  a  pattern was compiled with PCRE_ANCHORED, or         matching position. If a pattern was  compiled  with  PCRE_ANCHORED,  or
3224         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
3225         unachored at matching time.         unachored at matching time.
3226    
3227             PCRE_BSR_ANYCRLF
3228             PCRE_BSR_UNICODE
3229    
3230           These options (which are mutually exclusive) control what the \R escape
3231           sequence  matches.  The choice is either to match only CR, LF, or CRLF,
3232           or to match any Unicode newline sequence. These  options  override  the
3233           choice that was made or defaulted when the pattern was compiled.
3234    
3235           PCRE_NEWLINE_CR           PCRE_NEWLINE_CR
3236           PCRE_NEWLINE_LF           PCRE_NEWLINE_LF
3237           PCRE_NEWLINE_CRLF           PCRE_NEWLINE_CRLF
# Line 1762  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3243  MATCHING A PATTERN: THE TRADITIONAL FUNC
3243         tion  of  pcre_compile()  above.  During  matching,  the newline choice         tion  of  pcre_compile()  above.  During  matching,  the newline choice
3244         affects the behaviour of the dot, circumflex,  and  dollar  metacharac-         affects the behaviour of the dot, circumflex,  and  dollar  metacharac-
3245         ters.  It may also alter the way the match position is advanced after a         ters.  It may also alter the way the match position is advanced after a
3246         match  failure  for  an  unanchored  pattern.  When  PCRE_NEWLINE_CRLF,         match failure for an unanchored pattern.
3247         PCRE_NEWLINE_ANYCRLF,  or  PCRE_NEWLINE_ANY is set, and a match attempt  
3248         fails when the current position is at a CRLF sequence, the match  posi-         When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF,  or  PCRE_NEWLINE_ANY  is
3249         tion  is  advanced by two characters instead of one, in other words, to         set,  and a match attempt for an unanchored pattern fails when the cur-
3250         after the CRLF.         rent position is at a  CRLF  sequence,  and  the  pattern  contains  no
3251           explicit  matches  for  CR  or  LF  characters,  the  match position is
3252           advanced by two characters instead of one, in other words, to after the
3253           CRLF.
3254    
3255           The above rule is a compromise that makes the most common cases work as
3256           expected. For example, if the  pattern  is  .+A  (and  the  PCRE_DOTALL
3257           option is not set), it does not match the string "\r\nA" because, after
3258           failing at the start, it skips both the CR and the LF before  retrying.
3259           However,  the  pattern  [\r\n]A does match that string, because it con-
3260           tains an explicit CR or LF reference, and so advances only by one char-
3261           acter after the first failure.
3262    
3263           An explicit match for CR of LF is either a literal appearance of one of
3264           those characters, or one of the \r or  \n  escape  sequences.  Implicit
3265           matches  such  as [^X] do not count, nor does \s (which includes CR and
3266           LF in the characters that it matches).
3267    
3268           Notwithstanding the above, anomalous effects may still occur when  CRLF
3269           is a valid newline sequence and explicit \r or \n escapes appear in the
3270           pattern.
3271    
3272           PCRE_NOTBOL           PCRE_NOTBOL
3273    
# Line 1794  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3295  MATCHING A PATTERN: THE TRADITIONAL FUNC
3295    
3296           a?b?           a?b?
3297    
3298         is applied to a string not beginning with "a" or "b",  it  matches  the         is applied to a string not beginning with "a" or  "b",  it  matches  an
3299         empty  string at the start of the subject. With PCRE_NOTEMPTY set, this         empty  string at the start of the subject. With PCRE_NOTEMPTY set, this
3300         match is not valid, so PCRE searches further into the string for occur-         match is not valid, so PCRE searches further into the string for occur-
3301         rences of "a" or "b".         rences of "a" or "b".
3302    
3303         Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a spe-           PCRE_NOTEMPTY_ATSTART
3304         cial case of a pattern match of the empty  string  within  its  split()  
3305         function,  and  when  using  the /g modifier. It is possible to emulate         This  is  like PCRE_NOTEMPTY, except that an empty string match that is
3306         Perl's behaviour after matching a null string by first trying the match         not at the start of  the  subject  is  permitted.  If  the  pattern  is
3307         again at the same offset with PCRE_NOTEMPTY and PCRE_ANCHORED, and then         anchored, such a match can occur only if the pattern contains \K.
3308         if that fails by advancing the starting offset (see below)  and  trying  
3309         an ordinary match again. There is some code that demonstrates how to do         Perl     has    no    direct    equivalent    of    PCRE_NOTEMPTY    or
3310         this in the pcredemo.c sample program.