/[pcre]/code/trunk/doc/pcre.txt
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2  This file contains a concatenation of the PCRE man pages, converted to plain  This file contains a concatenation of the PCRE man pages, converted to plain
3  text format for ease of searching with a text editor, or for use on systems  text format for ease of searching with a text editor, or for use on systems
4  that do not have a man page processor. The small individual files that give  that do not have a man page processor. The small individual files that give
5  synopses of each function in the library have not been included. There are  synopses of each function in the library have not been included. Neither has
6  separate text files for the pcregrep and pcretest commands.  the pcredemo program. There are separate text files for the pcregrep and
7    pcretest commands.
8  -----------------------------------------------------------------------------  -----------------------------------------------------------------------------
9    
10    
# Line 18  INTRODUCTION Line 19  INTRODUCTION
19    
20         The  PCRE  library is a set of functions that implement regular expres-         The  PCRE  library is a set of functions that implement regular expres-
21         sion pattern matching using the same syntax and semantics as Perl, with         sion pattern matching using the same syntax and semantics as Perl, with
22         just  a  few  differences. Certain features that appeared in Python and         just  a few differences. Some features that appeared in Python and PCRE
23         PCRE before they appeared in Perl are also available using  the  Python         before they appeared in Perl are also available using the  Python  syn-
24         syntax.  There is also some support for certain .NET and Oniguruma syn-         tax,  there  is  some  support for one or two .NET and Oniguruma syntax
25         tax items, and there is an option for  requesting  some  minor  changes         items, and there is an option for requesting some  minor  changes  that
26         that give better JavaScript compatibility.         give better JavaScript compatibility.
27    
28         The  current  implementation of PCRE (release 7.x) corresponds approxi-         Starting with release 8.30, it is possible to compile two separate PCRE
29         mately with Perl 5.10, including support for UTF-8 encoded strings  and         libraries:  the  original,  which  supports  8-bit  character   strings
30         Unicode general category properties. However, UTF-8 and Unicode support         (including  UTF-8  strings),  and a second library that supports 16-bit
31           character strings (including UTF-16 strings). The build process  allows
32           either  one  or both to be built. The majority of the work to make this
33           possible was done by Zoltan Herczeg.
34    
35           Starting with release 8.32 it is possible to compile a  third  separate
36           PCRE library, which supports 32-bit character strings (including UTF-32
37           strings). The build process allows any set of the 8-,  16-  and  32-bit
38           libraries. The work to make this possible was done by Christian Persch.
39    
40           The  three  libraries  contain identical sets of functions, except that
41           the names in the 16-bit library start with pcre16_  instead  of  pcre_,
42           and  the  names  in  the  32-bit  library start with pcre32_ instead of
43           pcre_. To avoid over-complication and reduce the documentation  mainte-
44           nance load, most of the documentation describes the 8-bit library, with
45           the differences for the 16-bit and  32-bit  libraries  described  sepa-
46           rately  in  the  pcre16  and  pcre32  pages. References to functions or
47           structures of the  form  pcre[16|32]_xxx  should  be  read  as  meaning
48           "pcre_xxx  when  using  the  8-bit  library,  pcre16_xxx when using the
49           16-bit library, or pcre32_xxx when using the 32-bit library".
50    
51           The current implementation of PCRE corresponds approximately with  Perl
52           5.12,  including  support  for  UTF-8/16/32 encoded strings and Unicode
53           general category properties. However, UTF-8/16/32 and  Unicode  support
54         has to be explicitly enabled; it is not the default. The Unicode tables         has to be explicitly enabled; it is not the default. The Unicode tables
55         correspond to Unicode release 5.0.0.         correspond to Unicode release 6.2.0.
56    
57         In  addition to the Perl-compatible matching function, PCRE contains an         In addition to the Perl-compatible matching function, PCRE contains  an
58         alternative matching function that matches the same  compiled  patterns         alternative  function that matches the same compiled patterns in a dif-
59         in  a different way. In certain circumstances, the alternative function         ferent way. In certain circumstances, the alternative function has some
60         has some advantages. For a discussion of the two  matching  algorithms,         advantages.   For  a discussion of the two matching algorithms, see the
61         see the pcrematching page.         pcrematching page.
62    
63         PCRE  is  written  in C and released as a C library. A number of people         PCRE is written in C and released as a C library. A  number  of  people
64         have written wrappers and interfaces of various kinds.  In  particular,         have  written  wrappers and interfaces of various kinds. In particular,
65         Google  Inc.   have  provided  a comprehensive C++ wrapper. This is now         Google Inc.  have provided a comprehensive C++ wrapper  for  the  8-bit
66         included as part of the PCRE distribution. The pcrecpp page has details         library.  This  is  now  included as part of the PCRE distribution. The
67         of  this  interface.  Other  people's contributions can be found in the         pcrecpp page has details of this interface.  Other  people's  contribu-
68         Contrib directory at the primary FTP site, which is:         tions  can  be  found in the Contrib directory at the primary FTP site,
69           which is:
70    
71         ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre         ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre
72    
# Line 54  INTRODUCTION Line 79  INTRODUCTION
79         library is built. The pcre_config() function makes it  possible  for  a         library is built. The pcre_config() function makes it  possible  for  a
80         client  to  discover  which  features are available. The features them-         client  to  discover  which  features are available. The features them-
81         selves are described in the pcrebuild page. Documentation about  build-         selves are described in the pcrebuild page. Documentation about  build-
82         ing  PCRE for various operating systems can be found in the README file         ing  PCRE  for various operating systems can be found in the README and
83         in the source distribution.         NON-AUTOTOOLS_BUILD files in the source distribution.
84    
85         The library contains a number of undocumented  internal  functions  and         The libraries contains a number of undocumented internal functions  and
86         data  tables  that  are  used by more than one of the exported external         data  tables  that  are  used by more than one of the exported external
87         functions, but which are not intended  for  use  by  external  callers.         functions, but which are not intended  for  use  by  external  callers.
88         Their  names  all begin with "_pcre_", which hopefully will not provoke         Their  names all begin with "_pcre_" or "_pcre16_" or "_pcre32_", which
89         any name clashes. In some environments, it is possible to control which         hopefully will not provoke any name clashes. In some  environments,  it
90         external  symbols  are  exported when a shared library is built, and in         is  possible  to  control  which  external  symbols are exported when a
91         these cases the undocumented symbols are not exported.         shared library is built, and in these cases  the  undocumented  symbols
92           are not exported.
93    
94    
95    SECURITY CONSIDERATIONS
96    
97           If  you  are  using PCRE in a non-UTF application that permits users to
98           supply arbitrary patterns for compilation, you should  be  aware  of  a
99           feature that allows users to turn on UTF support from within a pattern,
100           provided that PCRE was built with UTF support. For  example,  an  8-bit
101           pattern  that  begins  with  "(*UTF8)" turns on UTF-8 mode. This causes
102           both the pattern and any data against which it is matched to be checked
103           for UTF-8 validity. If the data string is very long, such a check might
104           use sufficiently many resources as to cause your  application  to  lose
105           performance.
106    
107           The  best  way  of  guarding  against  this  possibility  is to use the
108           pcre_fullinfo() function to check the compiled  pattern's  options  for
109           UTF.
110    
111           If  your  application  is one that supports UTF, be aware that validity
112           checking can take time. If the same data string is to be  matched  many
113           times, you can use the PCRE_NO_UTF[8|16|32]_CHECK option for the second
114           and subsequent matches to save redundant checks.
115    
116           Another way that performance can be hit is by running  a  pattern  that
117           has  a  very  large search tree against a string that will never match.
118           Nested unlimited repeats in a pattern are a common example.  PCRE  pro-
119           vides some protection against this: see the PCRE_EXTRA_MATCH_LIMIT fea-
120           ture in the pcreapi page.
121    
122    
123  USER DOCUMENTATION  USER DOCUMENTATION
# Line 71  USER DOCUMENTATION Line 125  USER DOCUMENTATION
125         The user documentation for PCRE comprises a number  of  different  sec-         The user documentation for PCRE comprises a number  of  different  sec-
126         tions.  In the "man" format, each of these is a separate "man page". In         tions.  In the "man" format, each of these is a separate "man page". In
127         the HTML format, each is a separate page, linked from the  index  page.         the HTML format, each is a separate page, linked from the  index  page.
128         In  the  plain text format, all the sections are concatenated, for ease         In  the  plain  text format, all the sections, except the pcredemo sec-
129         of searching. The sections are as follows:         tion, are concatenated, for ease of searching. The sections are as fol-
130           lows:
131    
132           pcre              this document           pcre              this document
133             pcre16            details of the 16-bit library
134             pcre32            details of the 32-bit library
135           pcre-config       show PCRE installation configuration information           pcre-config       show PCRE installation configuration information
136           pcreapi           details of PCRE's native C API           pcreapi           details of PCRE's native C API
137           pcrebuild         options for building PCRE           pcrebuild         options for building PCRE
138           pcrecallout       details of the callout feature           pcrecallout       details of the callout feature
139           pcrecompat        discussion of Perl compatibility           pcrecompat        discussion of Perl compatibility
140           pcrecpp           details of the C++ wrapper           pcrecpp           details of the C++ wrapper for the 8-bit library
141           pcregrep          description of the pcregrep command           pcredemo          a demonstration C program that uses PCRE
142             pcregrep          description of the pcregrep command (8-bit only)
143             pcrejit           discussion of the just-in-time optimization support
144             pcrelimits        details of size and other limits
145           pcrematching      discussion of the two matching algorithms           pcrematching      discussion of the two matching algorithms
146           pcrepartial       details of the partial matching facility           pcrepartial       details of the partial matching facility
147           pcrepattern       syntax and semantics of supported           pcrepattern       syntax and semantics of supported
148                               regular expressions                               regular expressions
          pcresyntax        quick syntax reference  
149           pcreperform       discussion of performance issues           pcreperform       discussion of performance issues
150           pcreposix         the POSIX-compatible C API           pcreposix         the POSIX-compatible C API for the 8-bit library
151           pcreprecompile    details of saving and re-using precompiled patterns           pcreprecompile    details of saving and re-using precompiled patterns
152           pcresample        discussion of the sample program           pcresample        discussion of the pcredemo program
153           pcrestack         discussion of stack usage           pcrestack         discussion of stack usage
154             pcresyntax        quick syntax reference
155           pcretest          description of the pcretest testing command           pcretest          description of the pcretest testing command
156             pcreunicode       discussion of Unicode and UTF-8/16/32 support
157    
158         In  addition,  in the "man" and HTML formats, there is a short page for         In  addition,  in the "man" and HTML formats, there is a short page for
159         each C library function, listing its arguments and results.         each C library function, listing its arguments and results.
160    
161    
162  LIMITATIONS  AUTHOR
163    
164         There are some size limitations in PCRE but it is hoped that they  will         Philip Hazel
165         never in practice be relevant.         University Computing Service
166           Cambridge CB2 3QH, England.
167    
168         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,
169         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,
170         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.  
171    
        All values in repeating quantifiers must be less than 65536.  
172    
173         There is no limit to the number of parenthesized subpatterns, but there  REVISION
        can be no more than 65535 capturing subpatterns.  
174    
175         The maximum length of name for a named subpattern is 32 characters, and         Last updated: 30 October 2012
176         the maximum number of named subpatterns is 10000.         Copyright (c) 1997-2012 University of Cambridge.
177    ------------------------------------------------------------------------------
178    
179    
180    PCRE(3)                                                                PCRE(3)
181    
        The  maximum  length of a subject string is the largest positive number  
        that an integer variable can hold. However, when using the  traditional  
        matching function, PCRE uses recursion to handle subpatterns and indef-  
        inite repetition.  This means that the available stack space may  limit  
        the size of a subject string that can be processed by certain patterns.  
        For a discussion of stack issues, see the pcrestack documentation.  
182    
183    NAME
184           PCRE - Perl-compatible regular expressions
185    
186  UTF-8 AND UNICODE PROPERTY SUPPORT         #include <pcre.h>
187    
        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.  
188    
189         If  you compile PCRE with UTF-8 support, but do not use it at run time,  PCRE 16-BIT API BASIC FUNCTIONS
        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.  
190    
191         If PCRE is built with Unicode character property support (which implies         pcre16 *pcre16_compile(PCRE_SPTR16 pattern, int options,
192         UTF-8  support),  the  escape sequences \p{..}, \P{..}, and \X are sup-              const char **errptr, int *erroffset,
193         ported.  The available properties that can be tested are limited to the              const unsigned char *tableptr);
        general  category  properties such as Lu for an upper case letter or Nd  
        for a decimal number, the Unicode script names such as Arabic  or  Han,  
        and  the  derived  properties  Any  and L&. A full list is given in the  
        pcrepattern documentation. Only the short names for properties are sup-  
        ported.  For example, \p{L} matches a letter. Its Perl synonym, \p{Let-  
        ter}, is not supported.  Furthermore,  in  Perl,  many  properties  may  
        optionally  be  prefixed by "Is", for compatibility with Perl 5.6. PCRE  
        does not support this.  
194    
195     Validity of UTF-8 strings         pcre16 *pcre16_compile2(PCRE_SPTR16 pattern, int options,
196                int *errorcodeptr,
197                const char **errptr, int *erroffset,
198                const unsigned char *tableptr);
199    
200         When you set the PCRE_UTF8 flag, the strings  passed  as  patterns  and         pcre16_extra *pcre16_study(const pcre16 *code, int options,
201         subjects are (by default) checked for validity on entry to the relevant              const char **errptr);
        functions. From release 7.3 of PCRE, the check is according  the  rules  
        of  RFC  3629, which are themselves derived from the Unicode specifica-  
        tion. Earlier releases of PCRE followed the rules of  RFC  2279,  which  
        allows  the  full range of 31-bit values (0 to 0x7FFFFFFF). The current  
        check allows only values in the range U+0 to U+10FFFF, excluding U+D800  
        to U+DFFF.  
   
        The  excluded  code  points are the "Low Surrogate Area" of Unicode, of  
        which the Unicode Standard says this: "The Low Surrogate Area does  not  
        contain  any  character  assignments,  consequently  no  character code  
        charts or namelists are provided for this area. Surrogates are reserved  
        for  use  with  UTF-16 and then must be used in pairs." The code points  
        that are encoded by UTF-16 pairs  are  available  as  independent  code  
        points  in  the  UTF-8  encoding.  (In other words, the whole surrogate  
        thing is a fudge for UTF-16 which unfortunately messes up UTF-8.)  
   
        If an  invalid  UTF-8  string  is  passed  to  PCRE,  an  error  return  
        (PCRE_ERROR_BADUTF8) is given. In some situations, you may already know  
        that your strings are valid, and therefore want to skip these checks in  
        order to improve performance. If you set the PCRE_NO_UTF8_CHECK flag at  
        compile time or at run time, PCRE assumes that the pattern  or  subject  
        it  is  given  (respectively)  contains only valid UTF-8 codes. In this  
        case, it does not diagnose an invalid UTF-8 string.  
202    
203         If you pass an invalid UTF-8 string  when  PCRE_NO_UTF8_CHECK  is  set,         void pcre16_free_study(pcre16_extra *extra);
        what  happens  depends on why the string is invalid. If the string con-  
        forms to the "old" definition of UTF-8 (RFC 2279), it is processed as a  
        string  of  characters  in  the  range 0 to 0x7FFFFFFF. In other words,  
        apart from the initial validity test, PCRE (when in UTF-8 mode) handles  
        strings  according  to  the more liberal rules of RFC 2279. However, if  
        the string does not even conform to RFC 2279, the result is  undefined.  
        Your program may crash.  
204    
205         If  you  want  to  process  strings  of  values  in the full range 0 to         int pcre16_exec(const pcre16 *code, const pcre16_extra *extra,
206         0x7FFFFFFF, encoded in a UTF-8-like manner as per the old RFC, you  can              PCRE_SPTR16 subject, int length, int startoffset,
207         set PCRE_NO_UTF8_CHECK to bypass the more restrictive test. However, in              int options, int *ovector, int ovecsize);
        this situation, you will have to apply your own validity check.  
208    
209     General comments about UTF-8 mode         int pcre16_dfa_exec(const pcre16 *code, const pcre16_extra *extra,
210                PCRE_SPTR16 subject, int length, int startoffset,
211                int options, int *ovector, int ovecsize,
212                int *workspace, int wscount);
213    
        1. An unbraced hexadecimal escape sequence (such  as  \xb3)  matches  a  
        two-byte UTF-8 character if the value is greater than 127.  
214    
215         2.  Octal  numbers  up to \777 are recognized, and match two-byte UTF-8  PCRE 16-BIT API STRING EXTRACTION FUNCTIONS
        characters for values greater than \177.  
216    
217         3. Repeat quantifiers apply to complete UTF-8 characters, not to  indi-         int pcre16_copy_named_substring(const pcre16 *code,
218         vidual bytes, for example: \x{100}{3}.              PCRE_SPTR16 subject, int *ovector,
219                int stringcount, PCRE_SPTR16 stringname,
220                PCRE_UCHAR16 *buffer, int buffersize);
221    
222         4.  The dot metacharacter matches one UTF-8 character instead of a sin-         int pcre16_copy_substring(PCRE_SPTR16 subject, int *ovector,
223         gle byte.              int stringcount, int stringnumber, PCRE_UCHAR16 *buffer,
224                int buffersize);
225    
226         5. The escape sequence \C can be used to match a single byte  in  UTF-8         int pcre16_get_named_substring(const pcre16 *code,
227         mode,  but  its  use can lead to some strange effects. This facility is              PCRE_SPTR16 subject, int *ovector,
228         not available in the alternative matching function, pcre_dfa_exec().              int stringcount, PCRE_SPTR16 stringname,
229                PCRE_SPTR16 *stringptr);
230    
231         6. The character escapes \b, \B, \d, \D, \s, \S, \w, and  \W  correctly         int pcre16_get_stringnumber(const pcre16 *code,
232         test  characters of any code value, but the characters that PCRE recog-              PCRE_SPTR16 name);
        nizes as digits, spaces, or word characters  remain  the  same  set  as  
        before, all with values less than 256. This remains true even when PCRE  
        includes Unicode property support, because to do otherwise  would  slow  
        down  PCRE in many common cases. If you really want to test for a wider  
        sense of, say, "digit", you must use Unicode  property  tests  such  as  
        \p{Nd}.  
233    
234         7.  Similarly,  characters that match the POSIX named character classes         int pcre16_get_stringtable_entries(const pcre16 *code,
235         are all low-valued characters.              PCRE_SPTR16 name, PCRE_UCHAR16 **first, PCRE_UCHAR16 **last);
236    
237         8. However, the Perl 5.10 horizontal and vertical  whitespace  matching         int pcre16_get_substring(PCRE_SPTR16 subject, int *ovector,
238         escapes (\h, \H, \v, and \V) do match all the appropriate Unicode char-              int stringcount, int stringnumber,
239         acters.              PCRE_SPTR16 *stringptr);
240    
241         9. Case-insensitive matching applies only to  characters  whose  values         int pcre16_get_substring_list(PCRE_SPTR16 subject,
242         are  less than 128, unless PCRE is built with Unicode property support.              int *ovector, int stringcount, PCRE_SPTR16 **listptr);
243         Even when Unicode property support is available, PCRE  still  uses  its  
244         own  character  tables when checking the case of low-valued characters,         void pcre16_free_substring(PCRE_SPTR16 stringptr);
245         so as not to degrade performance.  The Unicode property information  is  
246         used only for characters with higher values. Even when Unicode property         void pcre16_free_substring_list(PCRE_SPTR16 *stringptr);
247         support is available, PCRE supports case-insensitive matching only when  
248         there  is  a  one-to-one  mapping between a letter's cases. There are a  
249         small number of many-to-one mappings in Unicode;  these  are  not  sup-  PCRE 16-BIT API AUXILIARY FUNCTIONS
250         ported by PCRE.  
251           pcre16_jit_stack *pcre16_jit_stack_alloc(int startsize, int maxsize);
252    
253           void pcre16_jit_stack_free(pcre16_jit_stack *stack);
254    
255           void pcre16_assign_jit_stack(pcre16_extra *extra,
256                pcre16_jit_callback callback, void *data);
257    
258           const unsigned char *pcre16_maketables(void);
259    
260           int pcre16_fullinfo(const pcre16 *code, const pcre16_extra *extra,
261                int what, void *where);
262    
263           int pcre16_refcount(pcre16 *code, int adjust);
264    
265           int pcre16_config(int what, void *where);
266    
267           const char *pcre16_version(void);
268    
269           int pcre16_pattern_to_host_byte_order(pcre16 *code,
270                pcre16_extra *extra, const unsigned char *tables);
271    
272    
273    PCRE 16-BIT API INDIRECTED FUNCTIONS
274    
275           void *(*pcre16_malloc)(size_t);
276    
277           void (*pcre16_free)(void *);
278    
279           void *(*pcre16_stack_malloc)(size_t);
280    
281           void (*pcre16_stack_free)(void *);
282    
283           int (*pcre16_callout)(pcre16_callout_block *);
284    
285    
286    PCRE 16-BIT API 16-BIT-ONLY FUNCTION
287    
288           int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *output,
289                PCRE_SPTR16 input, int length, int *byte_order,
290                int keep_boms);
291    
292    
293    THE PCRE 16-BIT LIBRARY
294    
295           Starting  with  release  8.30, it is possible to compile a PCRE library
296           that supports 16-bit character strings, including  UTF-16  strings,  as
297           well  as  or instead of the original 8-bit library. The majority of the
298           work to make  this  possible  was  done  by  Zoltan  Herczeg.  The  two
299           libraries contain identical sets of functions, used in exactly the same
300           way. Only the names of the functions and the data types of their  argu-
301           ments  and results are different. To avoid over-complication and reduce
302           the documentation maintenance load,  most  of  the  PCRE  documentation
303           describes  the  8-bit  library,  with only occasional references to the
304           16-bit library. This page describes what is different when you use  the
305           16-bit library.
306    
307           WARNING:  A  single  application can be linked with both libraries, but
308           you must take care when processing any particular pattern to use  func-
309           tions  from  just one library. For example, if you want to study a pat-
310           tern that was compiled with  pcre16_compile(),  you  must  do  so  with
311           pcre16_study(), not pcre_study(), and you must free the study data with
312           pcre16_free_study().
313    
314    
315    THE HEADER FILE
316    
317           There is only one header file, pcre.h. It contains prototypes  for  all
318           the  functions  in  both  libraries,  as  well as definitions of flags,
319           structures, error codes, etc.
320    
321    
322    THE LIBRARY NAME
323    
324           In Unix-like systems, the 16-bit library is called libpcre16,  and  can
325           normally  be  accesss  by adding -lpcre16 to the command for linking an
326           application that uses PCRE.
327    
328    
329    STRING TYPES
330    
331           In the 8-bit library, strings are passed to PCRE library  functions  as
332           vectors  of  bytes  with  the  C  type "char *". In the 16-bit library,
333           strings are passed as vectors of unsigned 16-bit quantities. The  macro
334           PCRE_UCHAR16  specifies  an  appropriate  data type, and PCRE_SPTR16 is
335           defined as "const PCRE_UCHAR16 *". In very  many  environments,  "short
336           int" is a 16-bit data type. When PCRE is built, it defines PCRE_UCHAR16
337           as "short int", but checks that it really is a 16-bit data type. If  it
338           is not, the build fails with an error message telling the maintainer to
339           modify the definition appropriately.
340    
341    
342    STRUCTURE TYPES
343    
344           The types of the opaque structures that are used  for  compiled  16-bit
345           patterns  and  JIT stacks are pcre16 and pcre16_jit_stack respectively.
346           The  type  of  the  user-accessible  structure  that  is  returned   by
347           pcre16_study()  is  pcre16_extra, and the type of the structure that is
348           used for passing data to a callout  function  is  pcre16_callout_block.
349           These structures contain the same fields, with the same names, as their
350           8-bit counterparts. The only difference is that pointers  to  character
351           strings are 16-bit instead of 8-bit types.
352    
353    
354    16-BIT FUNCTIONS
355    
356           For  every function in the 8-bit library there is a corresponding func-
357           tion in the 16-bit library with a name that starts with pcre16_ instead
358           of  pcre_.  The  prototypes are listed above. In addition, there is one
359           extra function, pcre16_utf16_to_host_byte_order(). This  is  a  utility
360           function  that converts a UTF-16 character string to host byte order if
361           necessary. The other 16-bit  functions  expect  the  strings  they  are
362           passed to be in host byte order.
363    
364           The input and output arguments of pcre16_utf16_to_host_byte_order() may
365           point to the same address, that is, conversion in place  is  supported.
366           The output buffer must be at least as long as the input.
367    
368           The  length  argument  specifies the number of 16-bit data units in the
369           input string; a negative value specifies a zero-terminated string.
370    
371           If byte_order is NULL, it is assumed that the string starts off in host
372           byte  order. This may be changed by byte-order marks (BOMs) anywhere in
373           the string (commonly as the first character).
374    
375           If byte_order is not NULL, a non-zero value of the integer to which  it
376           points  means  that  the input starts off in host byte order, otherwise
377           the opposite order is assumed. Again, BOMs in  the  string  can  change
378           this. The final byte order is passed back at the end of processing.
379    
380           If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
381           copied into the output string. Otherwise they are discarded.
382    
383           The result of the function is the number of 16-bit  units  placed  into
384           the  output  buffer,  including  the  zero terminator if the string was
385           zero-terminated.
386    
387    
388    SUBJECT STRING OFFSETS
389    
390           The offsets within subject strings that are returned  by  the  matching
391           functions are in 16-bit units rather than bytes.
392    
393    
394    NAMED SUBPATTERNS
395    
396           The  name-to-number translation table that is maintained for named sub-
397           patterns uses 16-bit characters.  The  pcre16_get_stringtable_entries()
398           function returns the length of each entry in the table as the number of
399           16-bit data units.
400    
401    
402    OPTION NAMES
403    
404           There   are   two   new   general   option   names,   PCRE_UTF16    and
405           PCRE_NO_UTF16_CHECK,     which     correspond    to    PCRE_UTF8    and
406           PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
407           define  the  same bits in the options word. There is a discussion about
408           the validity of UTF-16 strings in the pcreunicode page.
409    
410           For the pcre16_config() function there is an  option  PCRE_CONFIG_UTF16
411           that  returns  1  if UTF-16 support is configured, otherwise 0. If this
412           option  is  given  to  pcre_config()  or  pcre32_config(),  or  if  the
413           PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF32  option is given to pcre16_con-
414           fig(), the result is the PCRE_ERROR_BADOPTION error.
415    
416    
417    CHARACTER CODES
418    
419           In 16-bit mode, when  PCRE_UTF16  is  not  set,  character  values  are
420           treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
421           that they can range from 0 to 0xffff instead of 0  to  0xff.  Character
422           types  for characters less than 0xff can therefore be influenced by the
423           locale in the same way as before.  Characters greater  than  0xff  have
424           only one case, and no "type" (such as letter or digit).
425    
426           In  UTF-16  mode,  the  character  code  is  Unicode, in the range 0 to
427           0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
428           because  those  are "surrogate" values that are used in pairs to encode
429           values greater than 0xffff.
430    
431           A UTF-16 string can indicate its endianness by special code knows as  a
432           byte-order mark (BOM). The PCRE functions do not handle this, expecting
433           strings  to  be  in  host  byte  order.  A  utility   function   called
434           pcre16_utf16_to_host_byte_order()  is  provided  to help with this (see
435           above).
436    
437    
438    ERROR NAMES
439    
440           The errors PCRE_ERROR_BADUTF16_OFFSET and PCRE_ERROR_SHORTUTF16  corre-
441           spond  to  their  8-bit  counterparts.  The error PCRE_ERROR_BADMODE is
442           given when a compiled pattern is passed to a  function  that  processes
443           patterns  in  the  other  mode, for example, if a pattern compiled with
444           pcre_compile() is passed to pcre16_exec().
445    
446           There are new error codes whose names  begin  with  PCRE_UTF16_ERR  for
447           invalid  UTF-16  strings,  corresponding to the PCRE_UTF8_ERR codes for
448           UTF-8 strings that are described in the section entitled "Reason  codes
449           for  invalid UTF-8 strings" in the main pcreapi page. The UTF-16 errors
450           are:
451    
452             PCRE_UTF16_ERR1  Missing low surrogate at end of string
453             PCRE_UTF16_ERR2  Invalid low surrogate follows high surrogate
454             PCRE_UTF16_ERR3  Isolated low surrogate
455             PCRE_UTF16_ERR4  Non-character
456    
457    
458    ERROR TEXTS
459    
460           If there is an error while compiling a pattern, the error text that  is
461           passed  back by pcre16_compile() or pcre16_compile2() is still an 8-bit
462           character string, zero-terminated.
463    
464    
465    CALLOUTS
466    
467           The subject and mark fields in the callout block that is  passed  to  a
468           callout function point to 16-bit vectors.
469    
470    
471    TESTING
472    
473           The  pcretest  program continues to operate with 8-bit input and output
474           files, but it can be used for testing the 16-bit library. If it is  run
475           with the command line option -16, patterns and subject strings are con-
476           verted from 8-bit to 16-bit before being passed to PCRE, and the 16-bit
477           library  functions  are used instead of the 8-bit ones. Returned 16-bit
478           strings are converted to 8-bit for output. If both the  8-bit  and  the
479           32-bit libraries were not compiled, pcretest defaults to 16-bit and the
480           -16 option is ignored.
481    
482           When PCRE is being built, the RunTest script that is  called  by  "make
483           check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
484           16-bit and 32-bit libraries has been built, and runs the  tests  appro-
485           priately.
486    
487    
488    NOT SUPPORTED IN 16-BIT MODE
489    
490           Not all the features of the 8-bit library are available with the 16-bit
491           library. The C++ and POSIX wrapper functions  support  only  the  8-bit
492           library, and the pcregrep program is at present 8-bit only.
493    
494    
495  AUTHOR  AUTHOR
# Line 251  AUTHOR Line 498  AUTHOR
498         University Computing Service         University Computing Service
499         Cambridge CB2 3QH, England.         Cambridge CB2 3QH, England.
500    
        Putting  an actual email address here seems to have been a spam magnet,  
        so I've taken it away. If you want to email me, use  my  two  initials,  
        followed by the two digits 10, at the domain cam.ac.uk.  
   
501    
502  REVISION  REVISION
503    
504         Last updated: 12 April 2008         Last updated: 14 April 2012
505         Copyright (c) 1997-2008 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
506  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
507    
508    
509    PCRE(3)                                                                PCRE(3)
510    
511    
512    NAME
513           PCRE - Perl-compatible regular expressions
514    
515           #include <pcre.h>
516    
517    
518    PCRE 32-BIT API BASIC FUNCTIONS
519    
520           pcre32 *pcre32_compile(PCRE_SPTR32 pattern, int options,
521                const char **errptr, int *erroffset,
522                const unsigned char *tableptr);
523    
524           pcre32 *pcre32_compile2(PCRE_SPTR32 pattern, int options,
525                int *errorcodeptr,
526                const char **errptr, int *erroffset,
527                const unsigned char *tableptr);
528    
529           pcre32_extra *pcre32_study(const pcre32 *code, int options,
530                const char **errptr);
531    
532           void pcre32_free_study(pcre32_extra *extra);
533    
534           int pcre32_exec(const pcre32 *code, const pcre32_extra *extra,
535                PCRE_SPTR32 subject, int length, int startoffset,
536                int options, int *ovector, int ovecsize);
537    
538           int pcre32_dfa_exec(const pcre32 *code, const pcre32_extra *extra,
539                PCRE_SPTR32 subject, int length, int startoffset,
540                int options, int *ovector, int ovecsize,
541                int *workspace, int wscount);
542    
543    
544    PCRE 32-BIT API STRING EXTRACTION FUNCTIONS
545    
546           int pcre32_copy_named_substring(const pcre32 *code,
547                PCRE_SPTR32 subject, int *ovector,
548                int stringcount, PCRE_SPTR32 stringname,
549                PCRE_UCHAR32 *buffer, int buffersize);
550    
551           int pcre32_copy_substring(PCRE_SPTR32 subject, int *ovector,
552                int stringcount, int stringnumber, PCRE_UCHAR32 *buffer,
553                int buffersize);
554    
555           int pcre32_get_named_substring(const pcre32 *code,
556                PCRE_SPTR32 subject, int *ovector,
557                int stringcount, PCRE_SPTR32 stringname,
558                PCRE_SPTR32 *stringptr);
559    
560           int pcre32_get_stringnumber(const pcre32 *code,
561                PCRE_SPTR32 name);
562    
563           int pcre32_get_stringtable_entries(const pcre32 *code,
564                PCRE_SPTR32 name, PCRE_UCHAR32 **first, PCRE_UCHAR32 **last);
565    
566           int pcre32_get_substring(PCRE_SPTR32 subject, int *ovector,
567                int stringcount, int stringnumber,
568                PCRE_SPTR32 *stringptr);
569    
570           int pcre32_get_substring_list(PCRE_SPTR32 subject,
571                int *ovector, int stringcount, PCRE_SPTR32 **listptr);
572    
573           void pcre32_free_substring(PCRE_SPTR32 stringptr);
574    
575           void pcre32_free_substring_list(PCRE_SPTR32 *stringptr);
576    
577    
578    PCRE 32-BIT API AUXILIARY FUNCTIONS
579    
580           pcre32_jit_stack *pcre32_jit_stack_alloc(int startsize, int maxsize);
581    
582           void pcre32_jit_stack_free(pcre32_jit_stack *stack);
583    
584           void pcre32_assign_jit_stack(pcre32_extra *extra,
585                pcre32_jit_callback callback, void *data);
586    
587           const unsigned char *pcre32_maketables(void);
588    
589           int pcre32_fullinfo(const pcre32 *code, const pcre32_extra *extra,
590                int what, void *where);
591    
592           int pcre32_refcount(pcre32 *code, int adjust);
593    
594           int pcre32_config(int what, void *where);
595    
596           const char *pcre32_version(void);
597    
598           int pcre32_pattern_to_host_byte_order(pcre32 *code,
599                pcre32_extra *extra, const unsigned char *tables);
600    
601    
602    PCRE 32-BIT API INDIRECTED FUNCTIONS
603    
604           void *(*pcre32_malloc)(size_t);
605    
606           void (*pcre32_free)(void *);
607    
608           void *(*pcre32_stack_malloc)(size_t);
609    
610           void (*pcre32_stack_free)(void *);
611    
612           int (*pcre32_callout)(pcre32_callout_block *);
613    
614    
615    PCRE 32-BIT API 32-BIT-ONLY FUNCTION
616    
617           int pcre32_utf32_to_host_byte_order(PCRE_UCHAR32 *output,
618                PCRE_SPTR32 input, int length, int *byte_order,
619                int keep_boms);
620    
621    
622    THE PCRE 32-BIT LIBRARY
623    
624           Starting  with  release  8.32, it is possible to compile a PCRE library
625           that supports 32-bit character strings, including  UTF-32  strings,  as
626           well as or instead of the original 8-bit library. This work was done by
627           Christian Persch, based on the work done  by  Zoltan  Herczeg  for  the
628           16-bit  library.  All  three  libraries contain identical sets of func-
629           tions, used in exactly the same way.  Only the names of  the  functions
630           and  the  data  types  of their arguments and results are different. To
631           avoid over-complication and reduce the documentation maintenance  load,
632           most  of  the PCRE documentation describes the 8-bit library, with only
633           occasional references to the 16-bit and  32-bit  libraries.  This  page
634           describes what is different when you use the 32-bit library.
635    
636           WARNING:  A  single  application  can  be linked with all or any of the
637           three libraries, but you must take care when processing any  particular
638           pattern  to  use  functions  from just one library. For example, if you
639           want to study a pattern that was compiled  with  pcre32_compile(),  you
640           must do so with pcre32_study(), not pcre_study(), and you must free the
641           study data with pcre32_free_study().
642    
643    
644    THE HEADER FILE
645    
646           There is only one header file, pcre.h. It contains prototypes  for  all
647           the  functions  in  both  libraries,  as  well as definitions of flags,
648           structures, error codes, etc.
649    
650    
651    THE LIBRARY NAME
652    
653           In Unix-like systems, the 32-bit library is called libpcre32,  and  can
654           normally  be  accesss  by adding -lpcre32 to the command for linking an
655           application that uses PCRE.
656    
657    
658    STRING TYPES
659    
660           In the 8-bit library, strings are passed to PCRE library  functions  as
661           vectors  of  bytes  with  the  C  type "char *". In the 32-bit library,
662           strings are passed as vectors of unsigned 32-bit quantities. The  macro
663           PCRE_UCHAR32  specifies  an  appropriate  data type, and PCRE_SPTR32 is
664           defined as "const PCRE_UCHAR32 *". In very many environments, "unsigned
665           int" is a 32-bit data type. When PCRE is built, it defines PCRE_UCHAR32
666           as "unsigned int", but checks that it really is a 32-bit data type.  If
667           it is not, the build fails with an error message telling the maintainer
668           to modify the definition appropriately.
669    
670    
671    STRUCTURE TYPES
672    
673           The types of the opaque structures that are used  for  compiled  32-bit
674           patterns  and  JIT stacks are pcre32 and pcre32_jit_stack respectively.
675           The  type  of  the  user-accessible  structure  that  is  returned   by
676           pcre32_study()  is  pcre32_extra, and the type of the structure that is
677           used for passing data to a callout  function  is  pcre32_callout_block.
678           These structures contain the same fields, with the same names, as their
679           8-bit counterparts. The only difference is that pointers  to  character
680           strings are 32-bit instead of 8-bit types.
681    
682    
683    32-BIT FUNCTIONS
684    
685           For  every function in the 8-bit library there is a corresponding func-
686           tion in the 32-bit library with a name that starts with pcre32_ instead
687           of  pcre_.  The  prototypes are listed above. In addition, there is one
688           extra function, pcre32_utf32_to_host_byte_order(). This  is  a  utility
689           function  that converts a UTF-32 character string to host byte order if
690           necessary. The other 32-bit  functions  expect  the  strings  they  are
691           passed to be in host byte order.
692    
693           The input and output arguments of pcre32_utf32_to_host_byte_order() may
694           point to the same address, that is, conversion in place  is  supported.
695           The output buffer must be at least as long as the input.
696    
697           The  length  argument  specifies the number of 32-bit data units in the
698           input string; a negative value specifies a zero-terminated string.
699    
700           If byte_order is NULL, it is assumed that the string starts off in host
701           byte  order. This may be changed by byte-order marks (BOMs) anywhere in
702           the string (commonly as the first character).
703    
704           If byte_order is not NULL, a non-zero value of the integer to which  it
705           points  means  that  the input starts off in host byte order, otherwise
706           the opposite order is assumed. Again, BOMs in  the  string  can  change
707           this. The final byte order is passed back at the end of processing.
708    
709           If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
710           copied into the output string. Otherwise they are discarded.
711    
712           The result of the function is the number of 32-bit  units  placed  into
713           the  output  buffer,  including  the  zero terminator if the string was
714           zero-terminated.
715    
716    
717    SUBJECT STRING OFFSETS
718    
719           The offsets within subject strings that are returned  by  the  matching
720           functions are in 32-bit units rather than bytes.
721    
722    
723    NAMED SUBPATTERNS
724    
725           The  name-to-number translation table that is maintained for named sub-
726           patterns uses 32-bit characters.  The  pcre32_get_stringtable_entries()
727           function returns the length of each entry in the table as the number of
728           32-bit data units.
729    
730    
731    OPTION NAMES
732    
733           There   are   two   new   general   option   names,   PCRE_UTF32    and
734           PCRE_NO_UTF32_CHECK,     which     correspond    to    PCRE_UTF8    and
735           PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
736           define  the  same bits in the options word. There is a discussion about
737           the validity of UTF-32 strings in the pcreunicode page.
738    
739           For the pcre32_config() function there is an  option  PCRE_CONFIG_UTF32
740           that  returns  1  if UTF-32 support is configured, otherwise 0. If this
741           option  is  given  to  pcre_config()  or  pcre16_config(),  or  if  the
742           PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF16  option is given to pcre32_con-
743           fig(), the result is the PCRE_ERROR_BADOPTION error.
744    
745    
746    CHARACTER CODES
747    
748           In 32-bit mode, when  PCRE_UTF32  is  not  set,  character  values  are
749           treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
750           that they can range from 0 to 0x7fffffff instead of 0 to 0xff.  Charac-
751           ter  types for characters less than 0xff can therefore be influenced by
752           the locale in the same way as before.   Characters  greater  than  0xff
753           have only one case, and no "type" (such as letter or digit).
754    
755           In  UTF-32  mode,  the  character  code  is  Unicode, in the range 0 to
756           0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
757           because those are "surrogate" values that are ill-formed in UTF-32.
758    
759           A  UTF-32 string can indicate its endianness by special code knows as a
760           byte-order mark (BOM). The PCRE functions do not handle this, expecting
761           strings   to   be  in  host  byte  order.  A  utility  function  called
762           pcre32_utf32_to_host_byte_order() is provided to help  with  this  (see
763           above).
764    
765    
766    ERROR NAMES
767    
768           The  error  PCRE_ERROR_BADUTF32  corresponds  to its 8-bit counterpart.
769           The error PCRE_ERROR_BADMODE is given when a compiled pattern is passed
770           to  a  function that processes patterns in the other mode, for example,
771           if a pattern compiled with pcre_compile() is passed to pcre32_exec().
772    
773           There are new error codes whose names  begin  with  PCRE_UTF32_ERR  for
774           invalid  UTF-32  strings,  corresponding to the PCRE_UTF8_ERR codes for
775           UTF-8 strings that are described in the section entitled "Reason  codes
776           for  invalid UTF-8 strings" in the main pcreapi page. The UTF-32 errors
777           are:
778    
779             PCRE_UTF32_ERR1  Surrogate character (range from 0xd800 to 0xdfff)
780             PCRE_UTF32_ERR2  Non-character
781             PCRE_UTF32_ERR3  Character > 0x10ffff
782    
783    
784    ERROR TEXTS
785    
786           If there is an error while compiling a pattern, the error text that  is
787           passed  back by pcre32_compile() or pcre32_compile2() is still an 8-bit
788           character string, zero-terminated.
789    
790    
791    CALLOUTS
792    
793           The subject and mark fields in the callout block that is  passed  to  a
794           callout function point to 32-bit vectors.
795    
796    
797    TESTING
798    
799           The  pcretest  program continues to operate with 8-bit input and output
800           files, but it can be used for testing the 32-bit library. If it is  run
801           with the command line option -32, patterns and subject strings are con-
802           verted from 8-bit to 32-bit before being passed to PCRE, and the 32-bit
803           library  functions  are used instead of the 8-bit ones. Returned 32-bit
804           strings are converted to 8-bit for output. If both the  8-bit  and  the
805           16-bit libraries were not compiled, pcretest defaults to 32-bit and the
806           -32 option is ignored.
807    
808           When PCRE is being built, the RunTest script that is  called  by  "make
809           check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
810           16-bit and 32-bit libraries has been built, and runs the  tests  appro-
811           priately.
812    
813    
814    NOT SUPPORTED IN 32-BIT MODE
815    
816           Not all the features of the 8-bit library are available with the 32-bit
817           library. The C++ and POSIX wrapper functions  support  only  the  8-bit
818           library, and the pcregrep program is at present 8-bit only.
819    
820    
821    AUTHOR
822    
823           Philip Hazel
824           University Computing Service
825           Cambridge CB2 3QH, England.
826    
827    
828    REVISION
829    
830           Last updated: 24 June 2012
831           Copyright (c) 1997-2012 University of Cambridge.
832    ------------------------------------------------------------------------------
833    
834    
835  PCREBUILD(3)                                                      PCREBUILD(3)  PCREBUILD(3)                                                      PCREBUILD(3)
836    
837    
# Line 277  PCRE BUILD-TIME OPTIONS Line 846  PCRE BUILD-TIME OPTIONS
846         script,  where the optional features are selected or deselected by pro-         script,  where the optional features are selected or deselected by pro-
847         viding options to configure before running the make  command.  However,         viding options to configure before running the make  command.  However,
848         the  same  options  can be selected in both Unix-like and non-Unix-like         the  same  options  can be selected in both Unix-like and non-Unix-like
849         environments using the GUI facility of  CMakeSetup  if  you  are  using         environments using the GUI facility of cmake-gui if you are using CMake
850         CMake instead of configure to build PCRE.         instead of configure to build PCRE.
851    
852           There  is a lot more information about building PCRE without using con-
853           figure (including information about using CMake or building "by  hand")
854           in  the file called NON-AUTOTOOLS-BUILD, which is part of the PCRE dis-
855           tribution. You should consult this file as well as the README  file  if
856           you are building in a non-Unix-like environment.
857    
858         The complete list of options for configure (which includes the standard         The complete list of options for configure (which includes the standard
859         ones such as the  selection  of  the  installation  directory)  can  be         ones such as the  selection  of  the  installation  directory)  can  be
# Line 294  PCRE BUILD-TIME OPTIONS Line 869  PCRE BUILD-TIME OPTIONS
869         is not described.         is not described.
870    
871    
872    BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES
873    
874           By default, a library called libpcre  is  built,  containing  functions
875           that  take  string  arguments  contained in vectors of bytes, either as
876           single-byte characters, or interpreted as UTF-8 strings. You  can  also
877           build  a  separate library, called libpcre16, in which strings are con-
878           tained in vectors of 16-bit data units and interpreted either  as  sin-
879           gle-unit characters or UTF-16 strings, by adding
880    
881             --enable-pcre16
882    
883           to the configure command. You can also build a separate library, called
884           libpcre32, in which strings are contained in  vectors  of  32-bit  data
885           units  and  interpreted  either  as  single-unit  characters  or UTF-32
886           strings, by adding
887    
888             --enable-pcre32
889    
890           to the configure command. If you do not want the 8-bit library, add
891    
892             --disable-pcre8
893    
894           as well. At least one of the three libraries must be built.  Note  that
895           the  C++  and  POSIX  wrappers are for the 8-bit library only, and that
896           pcregrep is an 8-bit program. None of these are  built  if  you  select
897           only the 16-bit or 32-bit libraries.
898    
899    
900    BUILDING SHARED AND STATIC LIBRARIES
901    
902           The  PCRE building process uses libtool to build both shared and static
903           Unix libraries by default. You can suppress one of these by adding  one
904           of
905    
906             --disable-shared
907             --disable-static
908    
909           to the configure command, as required.
910    
911    
912  C++ SUPPORT  C++ SUPPORT
913    
914         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
915         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,
916         library for PCRE. You can disable this by adding         it  automatically  builds  the C++ wrapper library (which supports only
917           8-bit strings). You can disable this by adding
918    
919           --disable-cpp           --disable-cpp
920    
921         to the configure command.         to the configure command.
922    
923    
924  UTF-8 SUPPORT  UTF-8, UTF-16 AND UTF-32 SUPPORT
925    
926         To build PCRE with support for UTF-8 character strings, add         To build PCRE with support for UTF Unicode character strings, add
927    
928           --enable-utf8           --enable-utf
929    
930         to the configure command. Of itself, this  does  not  make  PCRE  treat         to the configure command. This setting applies to all three  libraries,
931         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
932         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
933         function.         library.  There  are no separate options for enabling UTF-8, UTF-16 and
934           UTF-32 independently because that would allow ridiculous settings  such
935           as  requesting UTF-16 support while building only the 8-bit library. It
936           is not possible to build one library with UTF support and another with-
937           out  in the same configuration. (For backwards compatibility, --enable-
938           utf8 is a synonym of --enable-utf.)
939    
940           Of itself, this setting does not make  PCRE  treat  strings  as  UTF-8,
941           UTF-16  or UTF-32. As well as compiling PCRE with this option, you also
942           have have to set the PCRE_UTF8, PCRE_UTF16  or  PCRE_UTF32  option  (as
943           appropriate) when you call one of the pattern compiling functions.
944    
945           If  you  set --enable-utf when compiling in an EBCDIC environment, PCRE
946           expects its input to be either ASCII or UTF-8 (depending  on  the  run-
947           time option). It is not possible to support both EBCDIC and UTF-8 codes
948           in the same version of  the  library.  Consequently,  --enable-utf  and
949           --enable-ebcdic are mutually exclusive.
950    
951    
952  UNICODE CHARACTER PROPERTY SUPPORT  UNICODE CHARACTER PROPERTY SUPPORT
953    
954         UTF-8  support allows PCRE to process character values greater than 255         UTF  support allows the libraries to process character codepoints up to
955         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
956         vide any facilities for accessing the properties of such characters. If         not provide any facilities for accessing the properties of such charac-
957         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,
958         refer to Unicode character properties, you must add         which refer to Unicode character properties, you must add
959    
960           --enable-unicode-properties           --enable-unicode-properties
961    
962         to  the configure command. This implies UTF-8 support, even if you have         to  the  configure  command. This implies UTF support, even if you have
963         not explicitly requested it.         not explicitly requested it.
964    
965         Including Unicode property support adds around 30K  of  tables  to  the         Including Unicode property support adds around 30K  of  tables  to  the
# Line 335  UNICODE CHARACTER PROPERTY SUPPORT Line 967  UNICODE CHARACTER PROPERTY SUPPORT
967         are supported. Details are given in the pcrepattern documentation.         are supported. Details are given in the pcrepattern documentation.
968    
969    
970    JUST-IN-TIME COMPILER SUPPORT
971    
972           Just-in-time compiler support is included in the build by specifying
973    
974             --enable-jit
975    
976           This support is available only for certain hardware  architectures.  If
977           this  option  is  set  for  an unsupported architecture, a compile time
978           error occurs.  See the pcrejit documentation for a  discussion  of  JIT
979           usage. When JIT support is enabled, pcregrep automatically makes use of
980           it, unless you add
981    
982             --disable-pcregrep-jit
983    
984           to the "configure" command.
985    
986    
987  CODE VALUE OF NEWLINE  CODE VALUE OF NEWLINE
988    
989         By default, PCRE interprets character 10 (linefeed, LF)  as  indicating         By default, PCRE interprets the linefeed (LF) character  as  indicating
990         the  end  of  a line. This is the normal newline character on Unix-like         the  end  of  a line. This is the normal newline character on Unix-like
991         systems. You can compile PCRE to use character 13 (carriage return, CR)         systems. You can compile PCRE to use carriage return (CR)  instead,  by
992         instead, by adding         adding
993    
994           --enable-newline-is-cr           --enable-newline-is-cr
995    
# Line 363  CODE VALUE OF NEWLINE Line 1012  CODE VALUE OF NEWLINE
1012    
1013         causes PCRE to recognize any Unicode newline sequence.         causes PCRE to recognize any Unicode newline sequence.
1014    
1015         Whatever  line  ending convention is selected when PCRE is built can be         Whatever line ending convention is selected when PCRE is built  can  be
1016         overridden when the library functions are called. At build time  it  is         overridden  when  the library functions are called. At build time it is
1017         conventional to use the standard for your operating system.         conventional to use the standard for your operating system.
1018    
1019    
1020  WHAT \R MATCHES  WHAT \R MATCHES
1021    
1022         By  default,  the  sequence \R in a pattern matches any Unicode newline         By default, the sequence \R in a pattern matches  any  Unicode  newline
1023         sequence, whatever has been selected as the line  ending  sequence.  If         sequence,  whatever  has  been selected as the line ending sequence. If
1024         you specify         you specify
1025    
1026           --enable-bsr-anycrlf           --enable-bsr-anycrlf
1027    
1028         the  default  is changed so that \R matches only CR, LF, or CRLF. What-         the default is changed so that \R matches only CR, LF, or  CRLF.  What-
1029         ever is selected when PCRE is built can be overridden when the  library         ever  is selected when PCRE is built can be overridden when the library
1030         functions are called.         functions are called.
1031    
1032    
 BUILDING SHARED AND STATIC LIBRARIES  
   
        The  PCRE building process uses libtool to build both shared and static  
        Unix libraries by default. You can suppress one of these by adding  one  
        of  
   
          --disable-shared  
          --disable-static  
   
        to the configure command, as required.  
   
   
1033  POSIX MALLOC USAGE  POSIX MALLOC USAGE
1034    
1035         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
1036         umentation), additional working storage is  required  for  holding  the         pcreposix  documentation),  additional  working storage is required for
1037         pointers  to capturing substrings, because PCRE requires three integers         holding the pointers to capturing  substrings,  because  PCRE  requires
1038         per substring, whereas the POSIX interface provides only  two.  If  the         three integers per substring, whereas the POSIX interface provides only
1039         number of expected substrings is small, the wrapper function uses space         two. If the number of expected substrings is small, the  wrapper  func-
1040         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-
1041         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
1042         can be changed by adding a setting such as         longer used is 10; it can be changed by adding a setting such as
1043    
1044           --with-posix-malloc-threshold=20           --with-posix-malloc-threshold=20
1045    
# Line 411  POSIX MALLOC USAGE Line 1048  POSIX MALLOC USAGE
1048    
1049  HANDLING VERY LARGE PATTERNS  HANDLING VERY LARGE PATTERNS
1050    
1051         Within a compiled pattern, offset values are used  to  point  from  one         Within  a  compiled  pattern,  offset values are used to point from one
1052         part  to another (for example, from an opening parenthesis to an alter-         part to another (for example, from an opening parenthesis to an  alter-
1053         nation metacharacter). By default, two-byte values are used  for  these         nation  metacharacter).  By default, in the 8-bit and 16-bit libraries,
1054         offsets,  leading  to  a  maximum size for a compiled pattern of around         two-byte values are used for these offsets, leading to a  maximum  size
1055         64K. This is sufficient to handle all but the most  gigantic  patterns.         for  a compiled pattern of around 64K. This is sufficient to handle all
1056         Nevertheless,  some  people do want to process enormous patterns, so it         but the most gigantic patterns.  Nevertheless, some people do  want  to
1057         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
1058         adding a setting such as         use three-byte or four-byte offsets by adding a setting such as
1059    
1060           --with-link-size=3           --with-link-size=3
1061    
1062         to  the  configure  command.  The value given must be 2, 3, or 4. Using         to the configure command. The value given must be 2, 3, or 4.  For  the
1063         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,
1064         additional bytes when handling them.         using longer offsets slows down the operation of PCRE because it has to
1065           load  additional  data  when  handling them. For the 32-bit library the
1066           value is always 4 and cannot be overridden; the value  of  --with-link-
1067           size is ignored.
1068    
1069    
1070  AVOIDING EXCESSIVE STACK USAGE  AVOIDING EXCESSIVE STACK USAGE
# Line 445  AVOIDING EXCESSIVE STACK USAGE Line 1085  AVOIDING EXCESSIVE STACK USAGE
1085         to the configure command. With this configuration, PCRE  will  use  the         to the configure command. With this configuration, PCRE  will  use  the
1086         pcre_stack_malloc  and pcre_stack_free variables to call memory manage-         pcre_stack_malloc  and pcre_stack_free variables to call memory manage-
1087         ment functions. By default these point to malloc() and free(), but  you         ment functions. By default these point to malloc() and free(), but  you
1088         can replace the pointers so that your own functions are used.         can replace the pointers so that your own functions are used instead.
1089    
1090         Separate  functions  are  provided  rather  than  using pcre_malloc and         Separate  functions  are  provided  rather  than  using pcre_malloc and
1091         pcre_free because the  usage  is  very  predictable:  the  block  sizes         pcre_free because the  usage  is  very  predictable:  the  block  sizes
# Line 453  AVOIDING EXCESSIVE STACK USAGE Line 1093  AVOIDING EXCESSIVE STACK USAGE
1093         reverse order. A calling program might be able to  implement  optimized         reverse order. A calling program might be able to  implement  optimized
1094         functions  that  perform  better  than  malloc()  and free(). PCRE runs         functions  that  perform  better  than  malloc()  and free(). PCRE runs
1095         noticeably more slowly when built in this way. This option affects only         noticeably more slowly when built in this way. This option affects only
1096         the   pcre_exec()   function;   it   is   not   relevant  for  the  the         the pcre_exec() function; it is not relevant for pcre_dfa_exec().
        pcre_dfa_exec() function.  
1097    
1098    
1099  LIMITING PCRE RESOURCE USAGE  LIMITING PCRE RESOURCE USAGE
1100    
1101         Internally, PCRE has a function called match(), which it calls  repeat-         Internally,  PCRE has a function called match(), which it calls repeat-
1102         edly   (sometimes   recursively)  when  matching  a  pattern  with  the         edly  (sometimes  recursively)  when  matching  a  pattern   with   the
1103         pcre_exec() function. By controlling the maximum number of  times  this         pcre_exec()  function.  By controlling the maximum number of times this
1104         function  may be called during a single matching operation, a limit can         function may be called during a single matching operation, a limit  can
1105         be placed on the resources used by a single call  to  pcre_exec().  The         be  placed  on  the resources used by a single call to pcre_exec(). The
1106         limit  can be changed at run time, as described in the pcreapi documen-         limit can be changed at run time, as described in the pcreapi  documen-
1107         tation. The default is 10 million, but this can be changed by adding  a         tation.  The default is 10 million, but this can be changed by adding a
1108         setting such as         setting such as
1109    
1110           --with-match-limit=500000           --with-match-limit=500000
1111    
1112         to   the   configure  command.  This  setting  has  no  effect  on  the         to  the  configure  command.  This  setting  has  no  effect   on   the
1113         pcre_dfa_exec() matching function.         pcre_dfa_exec() matching function.
1114    
1115         In some environments it is desirable to limit the  depth  of  recursive         In  some  environments  it is desirable to limit the depth of recursive
1116         calls of match() more strictly than the total number of calls, in order         calls of match() more strictly than the total number of calls, in order
1117         to restrict the maximum amount of stack (or heap,  if  --disable-stack-         to  restrict  the maximum amount of stack (or heap, if --disable-stack-
1118         for-recursion is specified) that is used. A second limit controls this;         for-recursion is specified) that is used. A second limit controls this;
1119         it defaults to the value that  is  set  for  --with-match-limit,  which         it  defaults  to  the  value  that is set for --with-match-limit, which
1120         imposes  no  additional constraints. However, you can set a lower limit         imposes no additional constraints. However, you can set a  lower  limit
1121         by adding, for example,         by adding, for example,
1122    
1123           --with-match-limit-recursion=10000           --with-match-limit-recursion=10000
1124    
1125         to the configure command. This value can  also  be  overridden  at  run         to  the  configure  command.  This  value can also be overridden at run
1126         time.         time.
1127    
1128    
1129  CREATING CHARACTER TABLES AT BUILD TIME  CREATING CHARACTER TABLES AT BUILD TIME
1130    
1131         PCRE  uses fixed tables for processing characters whose code values are         PCRE uses fixed tables for processing characters whose code values  are
1132         less than 256. By default, PCRE is built with a set of tables that  are         less  than 256. By default, PCRE is built with a set of tables that are
1133         distributed  in  the  file pcre_chartables.c.dist. These tables are for         distributed in the file pcre_chartables.c.dist. These  tables  are  for
1134         ASCII codes only. If you add         ASCII codes only. If you add
1135    
1136           --enable-rebuild-chartables           --enable-rebuild-chartables
1137    
1138         to the configure command, the distributed tables are  no  longer  used.         to  the  configure  command, the distributed tables are no longer used.
1139         Instead,  a  program  called dftables is compiled and run. This outputs         Instead, a program called dftables is compiled and  run.  This  outputs
1140         the source for new set of tables, created in the default locale of your         the source for new set of tables, created in the default locale of your
1141         C runtime system. (This method of replacing the tables does not work if         C run-time system. (This method of replacing the tables does  not  work
1142         you are cross compiling, because dftables is run on the local host.  If         if  you are cross compiling, because dftables is run on the local host.
1143         you  need  to  create alternative tables when cross compiling, you will         If you need to create alternative tables when cross compiling, you will
1144         have to do so "by hand".)         have to do so "by hand".)
1145    
1146    
1147  USING EBCDIC CODE  USING EBCDIC CODE
1148    
1149         PCRE assumes by default that it will run in an  environment  where  the         PCRE  assumes  by  default that it will run in an environment where the
1150         character  code  is  ASCII  (or Unicode, which is a superset of ASCII).         character code is ASCII (or Unicode, which is  a  superset  of  ASCII).
1151         This is the case for most computer operating systems.  PCRE  can,  how-         This  is  the  case for most computer operating systems. PCRE can, how-
1152         ever, be compiled to run in an EBCDIC environment by adding         ever, be compiled to run in an EBCDIC environment by adding
1153    
1154           --enable-ebcdic           --enable-ebcdic
1155    
1156         to the configure command. This setting implies --enable-rebuild-charta-         to the configure command. This setting implies --enable-rebuild-charta-
1157         bles. You should only use it if you know that  you  are  in  an  EBCDIC         bles.  You  should  only  use  it if you know that you are in an EBCDIC
1158         environment (for example, an IBM mainframe operating system).         environment (for example,  an  IBM  mainframe  operating  system).  The
1159           --enable-ebcdic option is incompatible with --enable-utf.
1160    
1161           The EBCDIC character that corresponds to an ASCII LF is assumed to have
1162           the value 0x15 by default. However, in some EBCDIC  environments,  0x25
1163           is used. In such an environment you should use
1164    
1165             --enable-ebcdic-nl25
1166    
1167           as well as, or instead of, --enable-ebcdic. The EBCDIC character for CR
1168           has the same value as in ASCII, namely, 0x0d.  Whichever  of  0x15  and
1169           0x25 is not chosen as LF is made to correspond to the Unicode NEL char-
1170           acter (which, in Unicode, is 0x85).
1171    
1172           The options that select newline behaviour, such as --enable-newline-is-
1173           cr, and equivalent run-time options, refer to these character values in
1174           an EBCDIC environment.
1175    
1176    
1177  PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT  PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT
# Line 529  PCREGREP OPTIONS FOR COMPRESSED FILE SUP Line 1184  PCREGREP OPTIONS FOR COMPRESSED FILE SUP
1184           --enable-pcregrep-libbz2           --enable-pcregrep-libbz2
1185    
1186         to the configure command. These options naturally require that the rel-         to the configure command. These options naturally require that the rel-
1187         evant libraries are installed on your system. Configuration  will  fail         evant  libraries  are installed on your system. Configuration will fail
1188         if they are not.         if they are not.
1189    
1190    
1191    PCREGREP BUFFER SIZE
1192    
1193           pcregrep uses an internal buffer to hold a "window" on the file  it  is
1194           scanning, in order to be able to output "before" and "after" lines when
1195           it finds a match. The size of the buffer is controlled by  a  parameter
1196           whose default value is 20K. The buffer itself is three times this size,
1197           but because of the way it is used for holding "before" lines, the long-
1198           est  line  that  is guaranteed to be processable is the parameter size.
1199           You can change the default parameter value by adding, for example,
1200    
1201             --with-pcregrep-bufsize=50K
1202    
1203           to the configure command. The caller of pcregrep can, however, override
1204           this value by specifying a run-time option.
1205    
1206    
1207  PCRETEST OPTION FOR LIBREADLINE SUPPORT  PCRETEST OPTION FOR LIBREADLINE SUPPORT
1208    
1209         If you add         If you add
# Line 542  PCRETEST OPTION FOR LIBREADLINE SUPPORT Line 1213  PCRETEST OPTION FOR LIBREADLINE SUPPORT
1213         to  the  configure  command,  pcretest  is  linked with the libreadline         to  the  configure  command,  pcretest  is  linked with the libreadline
1214         library, and when its input is from a terminal, it reads it  using  the         library, and when its input is from a terminal, it reads it  using  the
1215         readline() function. This provides line-editing and history facilities.         readline() function. This provides line-editing and history facilities.
1216         Note that libreadline is GPL-licenced, so if you distribute a binary of         Note that libreadline is GPL-licensed, so if you distribute a binary of
1217         pcretest linked in this way, there may be licensing issues.         pcretest linked in this way, there may be licensing issues.
1218    
1219         Setting  this  option  causes  the -lreadline option to be added to the         Setting  this  option  causes  the -lreadline option to be added to the
# Line 564  PCRETEST OPTION FOR LIBREADLINE SUPPORT Line 1235  PCRETEST OPTION FOR LIBREADLINE SUPPORT
1235         immediately before the configure command.         immediately before the configure command.
1236    
1237    
1238    DEBUGGING WITH VALGRIND SUPPORT
1239    
1240           By adding the
1241    
1242             --enable-valgrind
1243    
1244           option  to to the configure command, PCRE will use valgrind annotations
1245           to mark certain memory regions as  unaddressable.  This  allows  it  to
1246           detect invalid memory accesses, and is mostly useful for debugging PCRE
1247           itself.
1248    
1249    
1250    CODE COVERAGE REPORTING
1251    
1252           If your C compiler is gcc, you can build a version  of  PCRE  that  can
1253           generate a code coverage report for its test suite. To enable this, you
1254           must install lcov version 1.6 or above. Then specify
1255    
1256             --enable-coverage
1257    
1258           to the configure command and build PCRE in the usual way.
1259    
1260           Note that using ccache (a caching C compiler) is incompatible with code
1261           coverage  reporting. If you have configured ccache to run automatically
1262           on your system, you must set the environment variable
1263    
1264             CCACHE_DISABLE=1
1265    
1266           before running make to build PCRE, so that ccache is not used.
1267    
1268           When --enable-coverage is used,  the  following  addition  targets  are
1269           added to the Makefile:
1270    
1271             make coverage
1272    
1273           This  creates  a  fresh  coverage report for the PCRE test suite. It is
1274           equivalent to running "make coverage-reset", "make  coverage-baseline",
1275           "make check", and then "make coverage-report".
1276    
1277             make coverage-reset
1278    
1279           This zeroes the coverage counters, but does nothing else.
1280    
1281             make coverage-baseline
1282    
1283           This captures baseline coverage information.
1284    
1285             make coverage-report
1286    
1287           This creates the coverage report.
1288    
1289             make coverage-clean-report
1290    
1291           This  removes the generated coverage report without cleaning the cover-
1292           age data itself.
1293    
1294             make coverage-clean-data
1295    
1296           This removes the captured coverage data without removing  the  coverage
1297           files created at compile time (*.gcno).
1298    
1299             make coverage-clean
1300    
1301           This  cleans all coverage data including the generated coverage report.
1302           For more information about code coverage, see the gcov and  lcov  docu-
1303           mentation.
1304    
1305    
1306  SEE ALSO  SEE ALSO
1307    
1308         pcreapi(3), pcre_config(3).         pcreapi(3), pcre16, pcre32, pcre_config(3).
1309    
1310    
1311  AUTHOR  AUTHOR
# Line 578  AUTHOR Line 1317  AUTHOR
1317    
1318  REVISION  REVISION
1319    
1320         Last updated: 13 April 2008         Last updated: 30 October 2012
1321         Copyright (c) 1997-2008 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
1322  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1323    
1324    
1325  PCREMATCHING(3)                                                PCREMATCHING(3)  PCREMATCHING(3)                                                PCREMATCHING(3)
1326    
1327    
# Line 595  PCRE MATCHING ALGORITHMS Line 1334  PCRE MATCHING ALGORITHMS
1334         This document describes the two different algorithms that are available         This document describes the two different algorithms that are available
1335         in PCRE for matching a compiled regular expression against a given sub-         in PCRE for matching a compiled regular expression against a given sub-
1336         ject  string.  The  "standard"  algorithm  is  the  one provided by the         ject  string.  The  "standard"  algorithm  is  the  one provided by the
1337         pcre_exec() function.  This works in the same was  as  Perl's  matching         pcre_exec(), pcre16_exec() and pcre32_exec() functions. These  work  in
1338         function, and provides a Perl-compatible matching operation.         the  same as as Perl's matching function, and provide a Perl-compatible
1339           matching  operation.   The  just-in-time  (JIT)  optimization  that  is
1340         An  alternative  algorithm is provided by the pcre_dfa_exec() function;         described  in  the pcrejit documentation is compatible with these func-
1341         this operates in a different way, and is not  Perl-compatible.  It  has         tions.
1342         advantages  and disadvantages compared with the standard algorithm, and  
1343         these are described below.         An  alternative  algorithm  is   provided   by   the   pcre_dfa_exec(),
1344           pcre16_dfa_exec()  and  pcre32_dfa_exec()  functions; they operate in a
1345           different way, and are not Perl-compatible. This alternative has advan-
1346           tages and disadvantages compared with the standard algorithm, and these
1347           are described below.
1348    
1349         When there is only one possible way in which a given subject string can         When there is only one possible way in which a given subject string can
1350         match  a pattern, the two algorithms give the same answer. A difference         match  a pattern, the two algorithms give the same answer. A difference
# Line 666  THE ALTERNATIVE MATCHING ALGORITHM Line 1409  THE ALTERNATIVE MATCHING ALGORITHM
1409         though  it is not implemented as a traditional finite state machine (it         though  it is not implemented as a traditional finite state machine (it
1410         keeps multiple states active simultaneously).         keeps multiple states active simultaneously).
1411    
1412           Although the general principle of this matching algorithm  is  that  it
1413           scans  the subject string only once, without backtracking, there is one
1414           exception: when a lookaround assertion is encountered,  the  characters
1415           following  or  preceding  the  current  point  have to be independently
1416           inspected.
1417    
1418         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
1419         there  are  no more unterminated paths. At this point, terminated paths         there  are  no more unterminated paths. At this point, terminated paths
1420         represent the different matching possibilities (if there are none,  the         represent the different matching possibilities (if there are none,  the
1421         match  has  failed).   Thus,  if there is more than one possible match,         match  has  failed).   Thus,  if there is more than one possible match,
1422         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-
1423         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
1424         match (which is necessarily the shortest) has been found.         an option to stop the algorithm after the first match (which is  neces-
1425           sarily the shortest) is found.
1426    
1427         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
1428         subject. If the pattern         subject. If the pattern
1429    
1430           cat(er(pillar)?)           cat(er(pillar)?)?
1431    
1432         is  matched  against the string "the caterpillar catchment", the result         is matched against the string "the caterpillar catchment",  the  result
1433         will be the three strings "cat", "cater", and "caterpillar" that  start         will  be the three strings "caterpillar", "cater", and "cat" that start
1434         at the fourth character of the subject. The algorithm does not automat-         at the fifth character of the subject. The algorithm does not automati-
1435         ically move on to find matches that start at later positions.         cally move on to find matches that start at later positions.
1436    
1437         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
1438         supported by the alternative matching algorithm. They are as follows:         supported by the alternative matching algorithm. They are as follows:
1439    
1440         1.  Because  the  algorithm  finds  all possible matches, the greedy or         1. Because the algorithm finds all  possible  matches,  the  greedy  or
1441         ungreedy nature of repetition quantifiers is not relevant.  Greedy  and         ungreedy  nature  of repetition quantifiers is not relevant. Greedy and
1442         ungreedy quantifiers are treated in exactly the same way. However, pos-         ungreedy quantifiers are treated in exactly the same way. However, pos-
1443         sessive quantifiers can make a difference when what follows could  also         sessive  quantifiers can make a difference when what follows could also
1444         match what is quantified, for example in a pattern like this:         match what is quantified, for example in a pattern like this:
1445    
1446           ^a++\w!           ^a++\w!
1447    
1448         This  pattern matches "aaab!" but not "aaa!", which would be matched by         This pattern matches "aaab!" but not "aaa!", which would be matched  by
1449         a non-possessive quantifier. Similarly, if an atomic group is  present,         a  non-possessive quantifier. Similarly, if an atomic group is present,
1450         it  is matched as if it were a standalone pattern at the current point,         it is matched as if it were a standalone pattern at the current  point,
1451         and the longest match is then "locked in" for the rest of  the  overall         and  the  longest match is then "locked in" for the rest of the overall
1452         pattern.         pattern.
1453    
1454         2. When dealing with multiple paths through the tree simultaneously, it         2. When dealing with multiple paths through the tree simultaneously, it
1455         is not straightforward to keep track of  captured  substrings  for  the         is  not  straightforward  to  keep track of captured substrings for the
1456         different  matching  possibilities,  and  PCRE's implementation of this         different matching possibilities, and  PCRE's  implementation  of  this
1457         algorithm does not attempt to do this. This means that no captured sub-         algorithm does not attempt to do this. This means that no captured sub-
1458         strings are available.         strings are available.
1459    
1460         3.  Because no substrings are captured, back references within the pat-         3. Because no substrings are captured, back references within the  pat-
1461         tern are not supported, and cause errors if encountered.         tern are not supported, and cause errors if encountered.
1462    
1463         4. For the same reason, conditional expressions that use  a  backrefer-         4.  For  the same reason, conditional expressions that use a backrefer-
1464         ence  as  the  condition or test for a specific group recursion are not         ence as the condition or test for a specific group  recursion  are  not
1465         supported.         supported.
1466    
1467         5. Because many paths through the tree may be  active,  the  \K  escape         5.  Because  many  paths  through the tree may be active, the \K escape
1468         sequence, which resets the start of the match when encountered (but may         sequence, which resets the start of the match when encountered (but may
1469         be on some paths and not on others), is not  supported.  It  causes  an         be  on  some  paths  and not on others), is not supported. It causes an
1470         error if encountered.         error if encountered.
1471    
1472         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
1473         always 1, and the value of the capture_last field is always -1.         always 1, and the value of the capture_last field is always -1.
1474    
1475         7. The \C escape sequence, which (in the standard algorithm) matches  a         7.  The  \C  escape  sequence, which (in the standard algorithm) always
1476         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
1477         tive algorithm moves through the subject  string  one  character  at  a         not  supported  in these modes, because the alternative algorithm moves
1478         time, for all active paths through the tree.         through the subject string one character (not data unit) at a time, for
1479           all active paths through the tree.
1480    
1481         8.  Except for (*FAIL), the backtracking control verbs such as (*PRUNE)         8.  Except for (*FAIL), the backtracking control verbs such as (*PRUNE)
1482         are not supported. (*FAIL) is supported, and  behaves  like  a  failing         are not supported. (*FAIL) is supported, and  behaves  like  a  failing
# Line 742  ADVANTAGES OF THE ALTERNATIVE ALGORITHM Line 1493  ADVANTAGES OF THE ALTERNATIVE ALGORITHM
1493         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
1494         things with callouts.         things with callouts.
1495    
1496         2.  There is much better support for partial matching. The restrictions         2.  Because  the  alternative  algorithm  scans the subject string just
1497         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-
1498         rithm  for  partial matching do not apply to the alternative algorithm.         sible  to  pass  very  long subject strings to the matching function in
1499         For non-anchored patterns, the starting position of a partial match  is         several pieces, checking for partial matching each time. Although it is
1500         available.         possible  to  do multi-segment matching using the standard algorithm by
1501           retaining partially matched substrings, it  is  more  complicated.  The
1502         3.  Because  the  alternative  algorithm  scans the subject string just         pcrepartial  documentation  gives  details of partial matching and dis-
1503         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.  
1504    
1505    
1506  DISADVANTAGES OF THE ALTERNATIVE ALGORITHM  DISADVANTAGES OF THE ALTERNATIVE ALGORITHM
# Line 777  AUTHOR Line 1526  AUTHOR
1526    
1527  REVISION  REVISION
1528    
1529         Last updated: 19 April 2008         Last updated: 08 January 2012
1530         Copyright (c) 1997-2008 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
1531  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1532    
1533    
1534  PCREAPI(3)                                                          PCREAPI(3)  PCREAPI(3)                                                          PCREAPI(3)
1535    
1536    
1537  NAME  NAME
1538         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
1539    
1540           #include <pcre.h>
1541    
 PCRE NATIVE API  
1542    
1543         #include <pcre.h>  PCRE NATIVE API BASIC FUNCTIONS
1544    
1545         pcre *pcre_compile(const char *pattern, int options,         pcre *pcre_compile(const char *pattern, int options,
1546              const char **errptr, int *erroffset,              const char **errptr, int *erroffset,
# Line 805  PCRE NATIVE API Line 1554  PCRE NATIVE API
1554         pcre_extra *pcre_study(const pcre *code, int options,         pcre_extra *pcre_study(const pcre *code, int options,
1555              const char **errptr);              const char **errptr);
1556    
1557           void pcre_free_study(pcre_extra *extra);
1558    
1559         int pcre_exec(const pcre *code, const pcre_extra *extra,         int pcre_exec(const pcre *code, const pcre_extra *extra,
1560              const char *subject, int length, int startoffset,              const char *subject, int length, int startoffset,
1561              int options, int *ovector, int ovecsize);              int options, int *ovector, int ovecsize);
# Line 814  PCRE NATIVE API Line 1565  PCRE NATIVE API
1565              int options, int *ovector, int ovecsize,              int options, int *ovector, int ovecsize,
1566              int *workspace, int wscount);              int *workspace, int wscount);
1567    
1568    
1569    PCRE NATIVE API STRING EXTRACTION FUNCTIONS
1570    
1571         int pcre_copy_named_substring(const pcre *code,         int pcre_copy_named_substring(const pcre *code,
1572              const char *subject, int *ovector,              const char *subject, int *ovector,
1573              int stringcount, const char *stringname,              int stringcount, const char *stringname,
# Line 845  PCRE NATIVE API Line 1599  PCRE NATIVE API
1599    
1600         void pcre_free_substring_list(const char **stringptr);         void pcre_free_substring_list(const char **stringptr);
1601    
1602    
1603    PCRE NATIVE API AUXILIARY FUNCTIONS
1604    
1605           int pcre_jit_exec(const pcre *code, const pcre_extra *extra,
1606                const char *subject, int length, int startoffset,
1607                int options, int *ovector, int ovecsize,
1608                pcre_jit_stack *jstack);
1609    
1610           pcre_jit_stack *pcre_jit_stack_alloc(int startsize, int maxsize);
1611    
1612           void pcre_jit_stack_free(pcre_jit_stack *stack);
1613    
1614           void pcre_assign_jit_stack(pcre_extra *extra,
1615                pcre_jit_callback callback, void *data);
1616    
1617         const unsigned char *pcre_maketables(void);         const unsigned char *pcre_maketables(void);
1618    
1619         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
1620              int what, void *where);              int what, void *where);
1621    
        int pcre_info(const pcre *code, int *optptr, int *firstcharptr);  
   
1622         int pcre_refcount(pcre *code, int adjust);         int pcre_refcount(pcre *code, int adjust);
1623    
1624         int pcre_config(int what, void *where);         int pcre_config(int what, void *where);
1625    
1626         char *pcre_version(void);         const char *pcre_version(void);
1627    
1628           int pcre_pattern_to_host_byte_order(pcre *code,
1629                pcre_extra *extra, const unsigned char *tables);
1630    
1631    
1632    PCRE NATIVE API INDIRECTED FUNCTIONS
1633    
1634         void *(*pcre_malloc)(size_t);         void *(*pcre_malloc)(size_t);
1635    
# Line 869  PCRE NATIVE API Line 1642  PCRE NATIVE API
1642         int (*pcre_callout)(pcre_callout_block *);         int (*pcre_callout)(pcre_callout_block *);
1643    
1644    
1645    PCRE 8-BIT, 16-BIT AND 32-BIT LIBRARIES
1646    
1647           From  release  8.30,  PCRE  can  be  compiled as a library for handling
1648           16-bit character strings as  well  as,  or  instead  of,  the  original
1649           library  that  handles 8-bit character strings. From release 8.32, PCRE
1650           can also be  compiled  as  a  library  for  handling  32-bit  character
1651           strings.  To  avoid  too much complication, this document describes the
1652           8-bit versions of the functions, with only occasional references to the
1653           16-bit and 32-bit libraries.
1654    
1655           The  16-bit and 32-bit functions operate in the same way as their 8-bit
1656           counterparts; they just use different data types  for  their  arguments
1657           and  results,  and their names start with pcre16_ or pcre32_ instead of
1658           pcre_. For every option  that  has  UTF8  in  its  name  (for  example,
1659           PCRE_UTF8),  there  are corresponding 16-bit and 32-bit names with UTF8
1660           replaced by UTF16 or UTF32, respectively. This facility is in fact just
1661           cosmetic;  the  16-bit and 32-bit option names define the same bit val-
1662           ues.
1663    
1664           References to bytes and UTF-8 in this document should be read as refer-
1665           ences  to  16-bit  data  quantities  and  UTF-16  when using the 16-bit
1666           library, or 32-bit data quantities and UTF-32  when  using  the  32-bit
1667           library,  unless specified otherwise. More details of the specific dif-
1668           ferences for the 16-bit and 32-bit libraries are given  in  the  pcre16
1669           and pcre32 pages.
1670    
1671    
1672  PCRE API OVERVIEW  PCRE API OVERVIEW
1673    
1674         PCRE has its own native API, which is described in this document. There         PCRE has its own native API, which is described in this document. There
1675         are also some wrapper functions that correspond to  the  POSIX  regular         are also some wrapper functions (for the 8-bit library only) that  cor-
1676         expression  API.  These  are  described in the pcreposix documentation.         respond  to  the  POSIX  regular  expression  API, but they do not give
1677         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
1678         distributed with PCRE. It is documented in the pcrecpp page.         documentation.  Both  of these APIs define a set of C function calls. A
1679           C++ wrapper (again for the 8-bit library only) is also distributed with
1680           PCRE. It is documented in the pcrecpp page.
1681    
1682         The  native  API  C  function prototypes are defined in the header file         The  native  API  C  function prototypes are defined in the header file
1683         pcre.h, and on Unix systems the library itself is called  libpcre.   It         pcre.h, and on Unix-like systems the (8-bit) library itself  is  called
1684         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
1685         application  that  uses  PCRE.  The  header  file  defines  the  macros         for linking an application that uses PCRE. The header file defines  the
1686         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
1687         bers for the library.  Applications can use these  to  include  support         numbers for the library. Applications can use these to include  support
1688         for different releases of PCRE.         for different releases of PCRE.
1689    
1690           In a Windows environment, if you want to statically link an application
1691           program against a non-dll pcre.a  file,  you  must  define  PCRE_STATIC
1692           before  including  pcre.h or pcrecpp.h, because otherwise the pcre_mal-
1693           loc()   and   pcre_free()   exported   functions   will   be   declared
1694           __declspec(dllimport), with unwanted results.
1695    
1696         The   functions   pcre_compile(),  pcre_compile2(),  pcre_study(),  and         The   functions   pcre_compile(),  pcre_compile2(),  pcre_study(),  and
1697         pcre_exec() are used for compiling and matching regular expressions  in         pcre_exec() are used for compiling and matching regular expressions  in
1698         a  Perl-compatible  manner. A sample program that demonstrates the sim-         a  Perl-compatible  manner. A sample program that demonstrates the sim-
1699         plest way of using them is provided in the file  called  pcredemo.c  in         plest way of using them is provided in the file  called  pcredemo.c  in
1700         the  source distribution. The pcresample documentation describes how to         the PCRE source distribution. A listing of this program is given in the
1701         compile and run it.         pcredemo documentation, and the pcresample documentation describes  how
1702           to compile and run it.
1703    
1704           Just-in-time  compiler  support is an optional feature of PCRE that can
1705           be built in appropriate hardware environments. It greatly speeds up the
1706           matching  performance  of  many  patterns.  Simple  programs can easily
1707           request that it be used if available, by  setting  an  option  that  is
1708           ignored  when  it is not relevant. More complicated programs might need
1709           to    make    use    of    the    functions     pcre_jit_stack_alloc(),
1710           pcre_jit_stack_free(),  and pcre_assign_jit_stack() in order to control
1711           the JIT code's memory usage.
1712    
1713           From release 8.32 there is also a direct interface for  JIT  execution,
1714           which  gives  improved performance. The JIT-specific functions are dis-
1715           cussed in the pcrejit documentation.
1716    
1717         A second matching function, pcre_dfa_exec(), which is not Perl-compati-         A second matching function, pcre_dfa_exec(), which is not Perl-compati-
1718         ble,  is  also provided. This uses a different algorithm for the match-         ble,  is  also provided. This uses a different algorithm for the match-
1719         ing. The alternative algorithm finds all possible matches (at  a  given         ing. The alternative algorithm finds all possible matches (at  a  given
1720         point  in  the subject), and scans the subject just once. However, this         point  in  the  subject), and scans the subject just once (unless there
1721         algorithm does not return captured substrings. A description of the two         are lookbehind assertions). However, this  algorithm  does  not  return
1722         matching  algorithms and their advantages and disadvantages is given in         captured  substrings.  A description of the two matching algorithms and
1723         the pcrematching documentation.         their advantages and disadvantages is given in the  pcrematching  docu-
1724           mentation.
1725    
1726         In addition to the main compiling and  matching  functions,  there  are         In  addition  to  the  main compiling and matching functions, there are
1727         convenience functions for extracting captured substrings from a subject         convenience functions for extracting captured substrings from a subject
1728         string that is matched by pcre_exec(). They are:         string that is matched by pcre_exec(). They are:
1729    
# Line 915  PCRE API OVERVIEW Line 1738  PCRE API OVERVIEW
1738         pcre_free_substring() and pcre_free_substring_list() are also provided,         pcre_free_substring() and pcre_free_substring_list() are also provided,
1739         to free the memory used for extracted strings.         to free the memory used for extracted strings.
1740    
1741         The  function  pcre_maketables()  is  used  to build a set of character         The function pcre_maketables() is used to  build  a  set  of  character
1742         tables  in  the  current  locale   for   passing   to   pcre_compile(),         tables   in   the   current   locale  for  passing  to  pcre_compile(),
1743         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
1744         provided for specialist use.  Most  commonly,  no  special  tables  are         provided  for  specialist  use.  Most  commonly,  no special tables are
1745         passed,  in  which case internal tables that are generated when PCRE is         passed, in which case internal tables that are generated when  PCRE  is
1746         built are used.         built are used.
1747    
1748         The function pcre_fullinfo() is used to find out  information  about  a         The  function  pcre_fullinfo()  is used to find out information about a
1749         compiled  pattern; pcre_info() is an obsolete version that returns only         compiled pattern. The function pcre_version() returns a  pointer  to  a
1750         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.  
1751    
1752         The function pcre_refcount() maintains a  reference  count  in  a  data         The  function  pcre_refcount()  maintains  a  reference count in a data
1753         block  containing  a compiled pattern. This is provided for the benefit         block containing a compiled pattern. This is provided for  the  benefit
1754         of object-oriented applications.         of object-oriented applications.
1755    
1756         The global variables pcre_malloc and pcre_free  initially  contain  the         The  global  variables  pcre_malloc and pcre_free initially contain the
1757         entry  points  of  the  standard malloc() and free() functions, respec-         entry points of the standard malloc()  and  free()  functions,  respec-
1758         tively. PCRE calls the memory management functions via these variables,         tively. PCRE calls the memory management functions via these variables,
1759         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
1760         calls. This should be done before calling any PCRE functions.         calls. This should be done before calling any PCRE functions.
1761    
1762         The global variables pcre_stack_malloc  and  pcre_stack_free  are  also         The  global  variables  pcre_stack_malloc  and pcre_stack_free are also
1763         indirections  to  memory  management functions. These special functions         indirections to memory management functions.  These  special  functions
1764         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
1765         data, instead of recursive function calls, when running the pcre_exec()         data, instead of recursive function calls, when running the pcre_exec()
1766         function. See the pcrebuild documentation for  details  of  how  to  do         function.  See  the  pcrebuild  documentation  for details of how to do
1767         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-
1768         ments that have limited stacks. Because of the greater  use  of  memory         ments  that  have  limited stacks. Because of the greater use of memory
1769         management,  it  runs  more  slowly. Separate functions are provided so         management, it runs more slowly. Separate  functions  are  provided  so
1770         that special-purpose external code can be  used  for  this  case.  When         that  special-purpose  external  code  can  be used for this case. When
1771         used,  these  functions  are always called in a stack-like manner (last         used, these functions are always called in a  stack-like  manner  (last
1772         obtained, first freed), and always for memory blocks of the same  size.         obtained,  first freed), and always for memory blocks of the same size.
1773         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-
1774         mentation.         mentation.
1775    
1776         The global variable pcre_callout initially contains NULL. It can be set         The global variable pcre_callout initially contains NULL. It can be set
1777         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
1778         specified points during a matching operation. Details are given in  the         specified  points during a matching operation. Details are given in the
1779         pcrecallout documentation.         pcrecallout documentation.
1780    
1781    
1782  NEWLINES  NEWLINES
1783    
1784         PCRE  supports five different conventions for indicating line breaks in         PCRE supports five different conventions for indicating line breaks  in
1785         strings: a single CR (carriage return) character, a  single  LF  (line-         strings:  a  single  CR (carriage return) character, a single LF (line-
1786         feed) character, the two-character sequence CRLF, any of the three pre-         feed) character, the two-character sequence CRLF, any of the three pre-
1787         ceding, or any Unicode newline sequence. The Unicode newline  sequences         ceding,  or any Unicode newline sequence. The Unicode newline sequences
1788         are  the  three just mentioned, plus the single characters VT (vertical         are the three just mentioned, plus the single characters  VT  (vertical
1789         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
1790         separator, U+2028), and PS (paragraph separator, U+2029).         separator, U+2028), and PS (paragraph separator, U+2029).
1791    
1792         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
1793         system as its standard newline sequence. When PCRE is built, a  default         system  as its standard newline sequence. When PCRE is built, a default
1794         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-
1795         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
1796         pattern is compiled, or when it is matched.         pattern is compiled, or when it is matched.
1797    
1798         At compile time, the newline convention can be specified by the options         At compile time, the newline convention can be specified by the options
1799         argument of pcre_compile(), or it can be specified by special  text  at         argument  of  pcre_compile(), or it can be specified by special text at
1800         the start of the pattern itself; this overrides any other settings. See         the start of the pattern itself; this overrides any other settings. See
1801         the pcrepattern page for details of the special character sequences.         the pcrepattern page for details of the special character sequences.
1802    
1803         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-
1804         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
1805         newline convention affects the handling of  the  dot,  circumflex,  and         newline  convention  affects  the  handling of the dot, circumflex, and
1806         dollar metacharacters, the handling of #-comments in /x mode, and, when         dollar metacharacters, the handling of #-comments in /x mode, and, when
1807         CRLF is a recognized line ending sequence, the match position  advance-         CRLF  is a recognized line ending sequence, the match position advance-
1808         ment for a non-anchored pattern. There is more detail about this in the         ment for a non-anchored pattern. There is more detail about this in the
1809         section on pcre_exec() options below.         section on pcre_exec() options below.
1810    
1811         The choice of newline convention does not affect the interpretation  of         The  choice of newline convention does not affect the interpretation of
1812         the  \n  or  \r  escape  sequences, nor does it affect what \R matches,         the \n or \r escape sequences, nor does  it  affect  what  \R  matches,
1813         which is controlled in a similar way, but by separate options.         which is controlled in a similar way, but by separate options.
1814    
1815    
1816  MULTITHREADING  MULTITHREADING
1817    
1818         The PCRE functions can be used in  multi-threading  applications,  with         The  PCRE  functions  can be used in multi-threading applications, with
1819         the  proviso  that  the  memory  management  functions  pointed  to  by         the  proviso  that  the  memory  management  functions  pointed  to  by
1820         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
1821         callout function pointed to by pcre_callout, are shared by all threads.         callout function pointed to by pcre_callout, are shared by all threads.
# Line 1003  MULTITHREADING Line 1824  MULTITHREADING
1824         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
1825         at once.         at once.
1826    
1827           If the just-in-time optimization feature is being used, it needs  sepa-
1828           rate  memory stack areas for each thread. See the pcrejit documentation
1829           for more details.
1830    
1831    
1832  SAVING PRECOMPILED PATTERNS FOR LATER USE  SAVING PRECOMPILED PATTERNS FOR LATER USE
1833    
1834         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
1835         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
1836         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
1837         pcreprecompile  documentation.  However, compiling a regular expression         pcreprecompile  documentation,  which  includes  a  description  of the
1838         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-
1839         anteed to work and may cause crashes.         lar  expression  with one version of PCRE for use with a different ver-
1840           sion is not guaranteed to work and may cause crashes.
1841    
1842    
1843  CHECKING BUILD-TIME OPTIONS  CHECKING BUILD-TIME OPTIONS
1844    
1845         int pcre_config(int what, void *where);         int pcre_config(int what, void *where);
1846    
1847         The  function pcre_config() makes it possible for a PCRE client to dis-         The function pcre_config() makes it possible for a PCRE client to  dis-
1848         cover which optional features have been compiled into the PCRE library.         cover which optional features have been compiled into the PCRE library.
1849         The  pcrebuild documentation has more details about these optional fea-         The pcrebuild documentation has more details about these optional  fea-
1850         tures.         tures.
1851    
1852         The first argument for pcre_config() is an  integer,  specifying  which         The  first  argument  for pcre_config() is an integer, specifying which
1853         information is required; the second argument is a pointer to a variable         information is required; the second argument is a pointer to a variable
1854         into which the information is  placed.  The  following  information  is         into  which  the  information  is placed. The returned value is zero on
1855           success, or the negative error code PCRE_ERROR_BADOPTION if  the  value
1856           in  the  first argument is not recognized. The following information is
1857         available:         available:
1858    
1859           PCRE_CONFIG_UTF8           PCRE_CONFIG_UTF8
1860    
1861         The  output is an integer that is set to one if UTF-8 support is avail-         The output is an integer that is set to one if UTF-8 support is  avail-
1862         able; otherwise it is set to zero.         able;  otherwise it is set to zero. This value should normally be given
1863           to the 8-bit version of this function, pcre_config(). If it is given to
1864           the   16-bit  or  32-bit  version  of  this  function,  the  result  is
1865           PCRE_ERROR_BADOPTION.
1866    
1867             PCRE_CONFIG_UTF16
1868    
1869           The output is an integer that is set to one if UTF-16 support is avail-
1870           able;  otherwise it is set to zero. This value should normally be given
1871           to the 16-bit version of this function, pcre16_config(). If it is given
1872           to  the  8-bit  or  32-bit  version  of  this  function,  the result is
1873           PCRE_ERROR_BADOPTION.
1874    
1875             PCRE_CONFIG_UTF32
1876    
1877           The output is an integer that is set to one if UTF-32 support is avail-
1878           able;  otherwise it is set to zero. This value should normally be given
1879           to the 32-bit version of this function, pcre32_config(). If it is given
1880           to  the  8-bit  or  16-bit  version  of  this  function,  the result is
1881           PCRE_ERROR_BADOPTION.
1882    
1883           PCRE_CONFIG_UNICODE_PROPERTIES           PCRE_CONFIG_UNICODE_PROPERTIES
1884    
1885         The output is an integer that is set to  one  if  support  for  Unicode         The output is an integer that is set to  one  if  support  for  Unicode
1886         character properties is available; otherwise it is set to zero.         character properties is available; otherwise it is set to zero.
1887    
1888             PCRE_CONFIG_JIT
1889    
1890           The output is an integer that is set to one if support for just-in-time
1891           compiling is available; otherwise it is set to zero.
1892    
1893             PCRE_CONFIG_JITTARGET
1894    
1895           The output is a pointer to a zero-terminated "const char *" string.  If
1896           JIT support is available, the string contains the name of the architec-
1897           ture for which the JIT compiler is configured, for example  "x86  32bit
1898           (little  endian  +  unaligned)".  If  JIT support is not available, the
1899           result is NULL.
1900    
1901           PCRE_CONFIG_NEWLINE           PCRE_CONFIG_NEWLINE
1902    
1903         The  output  is  an integer whose value specifies the default character         The output is an integer whose value specifies  the  default  character
1904         sequence that is recognized as meaning "newline". The four values  that         sequence  that  is recognized as meaning "newline". The values that are
1905         are supported are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF,         supported in ASCII/Unicode environments are: 10 for LF, 13 for CR, 3338
1906         and -1 for ANY. The default should normally be  the  standard  sequence         for  CRLF,  -2 for ANYCRLF, and -1 for ANY. In EBCDIC environments, CR,
1907         for your operating system.         ANYCRLF, and ANY yield the same values. However, the value  for  LF  is
1908           normally  21, though some EBCDIC environments use 37. The corresponding
1909           values for CRLF are 3349 and 3365. The default should  normally  corre-
1910           spond to the standard sequence for your operating system.
1911    
1912           PCRE_CONFIG_BSR           PCRE_CONFIG_BSR
1913    
# Line 1057  CHECKING BUILD-TIME OPTIONS Line 1920  CHECKING BUILD-TIME OPTIONS
1920           PCRE_CONFIG_LINK_SIZE           PCRE_CONFIG_LINK_SIZE
1921    
1922         The  output  is  an  integer that contains the number of bytes used for         The  output  is  an  integer that contains the number of bytes used for
1923         internal linkage in compiled regular expressions. The value is 2, 3, or         internal  linkage  in  compiled  regular  expressions.  For  the  8-bit
1924         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
1925         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
1926         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
1927         pattern to be up to 64K in size.         default value of 2 is sufficient for all but the most massive patterns,
1928           since  it  allows  the compiled pattern to be up to 64K in size. Larger
1929           values allow larger regular expressions to be compiled, at the  expense
1930           of slower matching.
1931    
1932           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
1933    
1934         The output is an integer that contains the threshold  above  which  the         The  output  is  an integer that contains the threshold above which the
1935         POSIX  interface  uses malloc() for output vectors. Further details are         POSIX interface uses malloc() for output vectors. Further  details  are
1936         given in the pcreposix documentation.         given in the pcreposix documentation.
1937    
1938           PCRE_CONFIG_MATCH_LIMIT           PCRE_CONFIG_MATCH_LIMIT
1939    
1940         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-
1941         internal  matching  function  calls in a pcre_exec() execution. Further         ber of internal matching function calls  in  a  pcre_exec()  execution.
1942         details are given with pcre_exec() below.         Further details are given with pcre_exec() below.
1943    
1944           PCRE_CONFIG_MATCH_LIMIT_RECURSION           PCRE_CONFIG_MATCH_LIMIT_RECURSION
1945    
1946         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
1947         recursion  when calling the internal matching function in a pcre_exec()         of  recursion  when  calling  the  internal  matching  function  in   a
1948         execution. Further details are given with pcre_exec() below.         pcre_exec()  execution.  Further  details  are  given  with pcre_exec()
1949           below.
1950    
1951           PCRE_CONFIG_STACKRECURSE           PCRE_CONFIG_STACKRECURSE
1952    
# Line 1106  COMPILING A PATTERN Line 1973  COMPILING A PATTERN
1973         Either of the functions pcre_compile() or pcre_compile2() can be called         Either of the functions pcre_compile() or pcre_compile2() can be called
1974         to compile a pattern into an internal form. The only difference between         to compile a pattern into an internal form. The only difference between
1975         the two interfaces is that pcre_compile2() has an additional  argument,         the two interfaces is that pcre_compile2() has an additional  argument,
1976         errorcodeptr, via which a numerical error code can be returned.         errorcodeptr,  via  which  a  numerical  error code can be returned. To
1977           avoid too much repetition, we refer just to pcre_compile()  below,  but
1978           the information applies equally to pcre_compile2().
1979    
1980         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
1981         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 1123  COMPILING A PATTERN Line 1992  COMPILING A PATTERN
1992    
1993         The options argument contains various bit settings that affect the com-         The options argument contains various bit settings that affect the com-
1994         pilation.  It  should be zero if no options are required. The available         pilation.  It  should be zero if no options are required. The available
1995         options are described below. Some of them, in  particular,  those  that         options are described below. Some of them (in  particular,  those  that
1996         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
1997         pattern (see the detailed description  in  the  pcrepattern  documenta-         unset from within the pattern (see  the  detailed  description  in  the
1998         tion).  For  these options, the contents of the options argument speci-         pcrepattern  documentation). For those options that can be different in
1999         fies their initial settings at the start of compilation and  execution.         different parts of the pattern, the contents of  the  options  argument
2000         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
2001         of matching as well as at compile time.         PCRE_ANCHORED, PCRE_BSR_xxx, PCRE_NEWLINE_xxx, PCRE_NO_UTF8_CHECK,  and
2002           PCRE_NO_START_OPTIMIZE  options  can  be set at the time of matching as
2003           well as at compile time.
2004    
2005         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,
2006         if  compilation  of  a  pattern fails, pcre_compile() returns NULL, and         if  compilation  of  a  pattern fails, pcre_compile() returns NULL, and
2007         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-
2008         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
2009         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
2010         ter where the error was discovered is placed in the variable pointed to         the  byte  that  was  being  processed when the error was discovered is
2011         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
2012         given.         (if  it is, an immediate error is given). However, for an invalid UTF-8
2013           string, the offset is that of the first byte of the failing character.
2014    
2015           Some errors are not detected until the whole pattern has been  scanned;
2016           in  these  cases,  the offset passed back is the length of the pattern.
2017           Note that the offset is in bytes, not characters, even in  UTF-8  mode.
2018           It may sometimes point into the middle of a UTF-8 character.
2019    
2020         If  pcre_compile2()  is  used instead of pcre_compile(), and the error-         If  pcre_compile2()  is  used instead of pcre_compile(), and the error-
2021         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 1216  COMPILING A PATTERN Line 2093  COMPILING A PATTERN
2093    
2094           PCRE_DOTALL           PCRE_DOTALL
2095    
2096         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-
2097         acters,  including  those that indicate newline. Without it, a dot does         acter of any value, including one that indicates a newline. However, it
2098         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.
2099         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
2100         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
2101         newline characters, independent of the setting of this option.         be  changed within a pattern by a (?s) option setting. A negative class
2102           such as [^a] always matches newline characters, independent of the set-
2103           ting of this option.
2104    
2105           PCRE_DUPNAMES           PCRE_DUPNAMES
2106    
# Line 1233  COMPILING A PATTERN Line 2112  COMPILING A PATTERN
2112    
2113           PCRE_EXTENDED           PCRE_EXTENDED
2114    
2115         If  this  bit  is  set,  whitespace  data characters in the pattern are         If  this  bit  is  set,  white space data characters in the pattern are
2116         totally ignored except when escaped or inside a character class. White-         totally ignored except when escaped or inside a character class.  White
2117         space does not include the VT character (code 11). In addition, charac-         space does not include the VT character (code 11). In addition, charac-
2118         ters between an unescaped # outside a character class and the next new-         ters between an unescaped # outside a character class and the next new-
2119         line,  inclusive,  are  also  ignored.  This is equivalent to Perl's /x         line,  inclusive,  are  also  ignored.  This is equivalent to Perl's /x
2120         option, and it can be changed within a pattern by a  (?x)  option  set-         option, and it can be changed within a pattern by a  (?x)  option  set-
2121         ting.         ting.
2122    
2123         This  option  makes  it possible to include comments inside complicated         Which  characters  are  interpreted  as  newlines  is controlled by the
2124         patterns.  Note, however, that this applies only  to  data  characters.         options passed to pcre_compile() or by a special sequence at the  start
2125         Whitespace   characters  may  never  appear  within  special  character         of  the  pattern, as described in the section entitled "Newline conven-
2126         sequences in a pattern, for  example  within  the  sequence  (?(  which         tions" in the pcrepattern documentation. Note that the end of this type
2127         introduces a conditional subpattern.         of  comment  is  a  literal  newline  sequence  in  the pattern; escape
2128           sequences that happen to represent a newline do not count.
2129    
2130           This option makes it possible to include  comments  inside  complicated
2131           patterns.   Note,  however,  that this applies only to data characters.
2132           White space  characters  may  never  appear  within  special  character
2133           sequences in a pattern, for example within the sequence (?( that intro-
2134           duces a conditional subpattern.
2135    
2136           PCRE_EXTRA           PCRE_EXTRA
2137    
2138         This  option  was invented in order to turn on additional functionality         This option was invented in order to turn on  additional  functionality
2139         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
2140         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
2141         letter that has no special meaning  causes  an  error,  thus  reserving         letter  that  has  no  special  meaning causes an error, thus reserving
2142         these  combinations  for  future  expansion.  By default, as in Perl, a         these combinations for future expansion. By  default,  as  in  Perl,  a
2143         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
2144         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
2145         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
2146         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
2147           within a pattern.
2148    
2149           PCRE_FIRSTLINE           PCRE_FIRSTLINE
2150    
# Line 1282  COMPILING A PATTERN Line 2169  COMPILING A PATTERN
2169         set  (assuming  it can find an "a" in the subject), whereas it fails by         set  (assuming  it can find an "a" in the subject), whereas it fails by
2170         default, for Perl compatibility.         default, for Perl compatibility.
2171    
2172           (3) \U matches an upper case "U" character; by default \U causes a com-
2173           pile time error (Perl uses \U to upper case subsequent characters).
2174    
2175           (4) \u matches a lower case "u" character unless it is followed by four
2176           hexadecimal digits, in which case the hexadecimal  number  defines  the
2177           code  point  to match. By default, \u causes a compile time error (Perl
2178           uses it to upper case the following character).
2179    
2180           (5) \x matches a lower case "x" character unless it is followed by  two
2181           hexadecimal  digits,  in  which case the hexadecimal number defines the
2182           code point to match. By default, as in Perl, a  hexadecimal  number  is
2183           always expected after \x, but it may have zero, one, or two digits (so,
2184           for example, \xz matches a binary zero character followed by z).
2185    
2186           PCRE_MULTILINE           PCRE_MULTILINE
2187    
2188         By default, PCRE treats the subject string as consisting  of  a  single         By default, PCRE treats the subject string as consisting  of  a  single
# Line 1312  COMPILING A PATTERN Line 2213  COMPILING A PATTERN
2213         two-character  CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF specifies         two-character  CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF specifies
2214         that any of the three preceding sequences should be recognized. Setting         that any of the three preceding sequences should be recognized. Setting
2215         PCRE_NEWLINE_ANY  specifies that any Unicode newline sequence should be         PCRE_NEWLINE_ANY  specifies that any Unicode newline sequence should be
2216         recognized. The Unicode newline sequences are the three just mentioned,         recognized.
        plus  the  single  characters  VT (vertical tab, U+000B), FF (formfeed,  
        U+000C), NEL (next line, U+0085), LS (line separator, U+2028),  and  PS  
        (paragraph  separator,  U+2029).  The  last  two are recognized only in  
        UTF-8 mode.  
2217    
2218         The newline setting in the  options  word  uses  three  bits  that  are         In an ASCII/Unicode environment, the Unicode newline sequences are  the
2219           three  just  mentioned,  plus  the  single characters VT (vertical tab,
2220           U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line sep-
2221           arator,  U+2028),  and  PS (paragraph separator, U+2029). For the 8-bit
2222           library, the last two are recognized only in UTF-8 mode.
2223    
2224           When PCRE is compiled to run in an EBCDIC (mainframe) environment,  the
2225           code for CR is 0x0d, the same as ASCII. However, the character code for
2226           LF is normally 0x15, though in some EBCDIC environments 0x25  is  used.
2227           Whichever  of  these  is  not LF is made to correspond to Unicode's NEL
2228           character. EBCDIC codes are all less than 256. For  more  details,  see
2229           the pcrebuild documentation.
2230    
2231           The  newline  setting  in  the  options  word  uses three bits that are
2232         treated as a number, giving eight possibilities. Currently only six are         treated as a number, giving eight possibilities. Currently only six are
2233         used (default plus the five values above). This means that if  you  set         used  (default  plus the five values above). This means that if you set
2234         more  than one newline option, the combination may or may not be sensi-         more than one newline option, the combination may or may not be  sensi-
2235         ble. For example, PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to         ble. For example, PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to
2236         PCRE_NEWLINE_CRLF,  but other combinations may yield unused numbers and         PCRE_NEWLINE_CRLF, but other combinations may yield unused numbers  and
2237         cause an error.         cause an error.
2238    
2239         The only time that a line break is specially recognized when  compiling         The  only  time  that a line break in a pattern is specially recognized
2240         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
2241         character class is encountered. This indicates  a  comment  that  lasts         characters,  and so are ignored in this mode. Also, an unescaped # out-
2242         until  after the next line break sequence. In other circumstances, line         side a character class indicates a comment that lasts until  after  the
2243         break  sequences  are  treated  as  literal  data,   except   that   in         next  line break sequence. In other circumstances, line break sequences
2244         PCRE_EXTENDED mode, both CR and LF are treated as whitespace characters         in patterns are treated as literal data.
        and are therefore ignored.  
2245    
2246         The newline option that is set at compile time becomes the default that         The newline option that is set at compile time becomes the default that
2247         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.
2248    
2249           PCRE_NO_AUTO_CAPTURE           PCRE_NO_AUTO_CAPTURE
2250    
2251         If this option is set, it disables the use of numbered capturing paren-         If this option is set, it disables the use of numbered capturing paren-
2252         theses  in the pattern. Any opening parenthesis that is not followed by         theses in the pattern. Any opening parenthesis that is not followed  by
2253         ? behaves as if it were followed by ?: but named parentheses can  still         ?  behaves as if it were followed by ?: but named parentheses can still
2254         be  used  for  capturing  (and  they acquire numbers in the usual way).         be used for capturing (and they acquire  numbers  in  the  usual  way).
2255         There is no equivalent of this option in Perl.         There is no equivalent of this option in Perl.
2256    
2257             NO_START_OPTIMIZE
2258    
2259           This  is an option that acts at matching time; that is, it is really an
2260           option for pcre_exec() or pcre_dfa_exec(). If  it  is  set  at  compile
2261           time,  it is remembered with the compiled pattern and assumed at match-
2262           ing time. For details  see  the  discussion  of  PCRE_NO_START_OPTIMIZE
2263           below.
2264    
2265             PCRE_UCP
2266    
2267           This  option changes the way PCRE processes \B, \b, \D, \d, \S, \s, \W,
2268           \w, and some of the POSIX character classes.  By  default,  only  ASCII
2269           characters  are  recognized, but if PCRE_UCP is set, Unicode properties
2270           are used instead to classify characters. More details are given in  the
2271           section  on generic character types in the pcrepattern page. If you set
2272           PCRE_UCP, matching one of the items it affects takes much  longer.  The
2273           option  is  available only if PCRE has been compiled with Unicode prop-
2274           erty support.
2275    
2276           PCRE_UNGREEDY           PCRE_UNGREEDY
2277    
2278         This option inverts the "greediness" of the quantifiers  so  that  they         This option inverts the "greediness" of the quantifiers  so  that  they
# Line 1355  COMPILING A PATTERN Line 2283  COMPILING A PATTERN
2283           PCRE_UTF8           PCRE_UTF8
2284    
2285         This  option  causes PCRE to regard both the pattern and the subject as         This  option  causes PCRE to regard both the pattern and the subject as
2286         strings of UTF-8 characters instead of single-byte  character  strings.         strings of UTF-8 characters instead of single-byte strings. However, it
2287         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,
2288         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
2289         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.  
2290    
2291           PCRE_NO_UTF8_CHECK           PCRE_NO_UTF8_CHECK
2292    
2293         When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is         When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
2294         automatically  checked.  There  is  a  discussion about the validity of         automatically checked. There is a  discussion  about  the  validity  of
2295         UTF-8 strings in the main pcre page. If an invalid  UTF-8  sequence  of         UTF-8  strings in the pcreunicode page. If an invalid UTF-8 sequence is
2296         bytes  is  found,  pcre_compile() returns an error. If you already know         found, pcre_compile() returns an error. If you already know  that  your
2297         that your pattern is valid, and you want to skip this check for perfor-         pattern  is valid, and you want to skip this check for performance rea-
2298         mance  reasons,  you  can set the PCRE_NO_UTF8_CHECK option. When it is         sons, you can set the PCRE_NO_UTF8_CHECK option.  When it is  set,  the
2299         set, the effect of passing an invalid UTF-8  string  as  a  pattern  is         effect of passing an invalid UTF-8 string as a pattern is undefined. It
2300         undefined.  It  may  cause your program to crash. Note that this option         may cause your program to crash. Note that  this  option  can  also  be
2301         can also be passed to pcre_exec() and pcre_dfa_exec(), to suppress  the         passed  to  pcre_exec()  and  pcre_dfa_exec(), to suppress the validity
2302         UTF-8 validity checking of subject strings.         checking of subject strings only. If the same string is  being  matched
2303           many  times, the option can be safely set for the second and subsequent
2304           matchings to improve performance.
2305    
2306    
2307  COMPILATION ERROR CODES  COMPILATION ERROR CODES
2308    
2309         The  following  table  lists  the  error  codes than may be returned by         The following table lists the error  codes  than  may  be  returned  by
2310         pcre_compile2(), along with the error messages that may be returned  by         pcre_compile2(),  along with the error messages that may be returned by
2311         both  compiling functions. As PCRE has developed, some error codes have         both compiling functions. Note that error  messages  are  always  8-bit
2312         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,
2313           some error codes have fallen out of use. To avoid confusion, they  have
2314           not been re-used.
2315    
2316            0  no error            0  no error
2317            1  \ at end of pattern            1  \ at end of pattern
# Line 1414  COMPILATION ERROR CODES Line 2345  COMPILATION ERROR CODES
2345           29  (?R or (?[+-]digits must be followed by )           29  (?R or (?[+-]digits must be followed by )
2346           30  unknown POSIX class name           30  unknown POSIX class name
2347           31  POSIX collating elements are not supported           31  POSIX collating elements are not supported
2348           32  this version of PCRE is not compiled with PCRE_UTF8 support           32  this version of PCRE is compiled without UTF support
2349           33  [this code is not in use]           33  [this code is not in use]
2350           34  character value in \x{...} sequence is too large           34  character value in \x{...} sequence is too large
2351           35  invalid condition (?(0)           35  invalid condition (?(0)
2352           36  \C not allowed in lookbehind assertion           36  \C not allowed in lookbehind assertion
2353           37  PCRE does not support \L, \l, \N, \U, or \u           37  PCRE does not support \L, \l, \N{name}, \U, or \u
2354           38  number after (?C is > 255           38  number after (?C is > 255
2355           39  closing ) for (?C expected           39  closing ) for (?C expected
2356           40  recursive call could loop indefinitely           40  recursive call could loop indefinitely
2357           41  unrecognized character after (?P           41  unrecognized character after (?P
2358           42  syntax error in subpattern name (missing terminator)           42  syntax error in subpattern name (missing terminator)
2359           43  two named subpatterns have the same name           43  two named subpatterns have the same name
2360           44  invalid UTF-8 string           44  invalid UTF-8 string (specifically UTF-8)
2361           45  support for \P, \p, and \X has not been compiled           45  support for \P, \p, and \X has not been compiled
2362           46  malformed \P or \p sequence           46  malformed \P or \p sequence
2363           47  unknown property name after \P or \p           47  unknown property name after \P or \p
2364           48  subpattern name is too long (maximum 32 characters)           48  subpattern name is too long (maximum 32 characters)
2365           49  too many named subpatterns (maximum 10000)           49  too many named subpatterns (maximum 10000)
2366           50  [this code is not in use]           50  [this code is not in use]
2367           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
2368           52  internal error: overran compiling workspace           52  internal error: overran compiling workspace
2369           53  internal  error:  previously-checked  referenced  subpattern  not           53  internal error: previously-checked referenced subpattern
2370         found                 not found
2371           54  DEFINE group contains more than one branch           54  DEFINE group contains more than one branch
2372           55  repeating a DEFINE group is not allowed           55  repeating a DEFINE group is not allowed
2373           56  inconsistent NEWLINE options           56  inconsistent NEWLINE options
2374           57  \g is not followed by a braced, angle-bracketed, or quoted           57  \g is not followed by a braced, angle-bracketed, or quoted
2375                 name/number or by a plain number                 name/number or by a plain number
2376           58  a numbered reference must not be zero           58  a numbered reference must not be zero
2377           59  (*VERB) with an argument is not supported           59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
2378           60  (*VERB) not recognized           60  (*VERB) not recognized
2379           61  number is too big           61  number is too big
2380           62  subpattern name expected           62  subpattern name expected
2381           63  digit expected after (?+           63  digit expected after (?+
2382           64  ] is an invalid data character in JavaScript compatibility mode           64  ] is an invalid data character in JavaScript compatibility mode
2383             65  different names for subpatterns of the same number are
2384                   not allowed
2385             66  (*MARK) must have an argument
2386             67  this version of PCRE is not compiled with Unicode property
2387                   support
2388             68  \c must be followed by an ASCII character
2389             69  \k is not followed by a braced, angle-bracketed, or quoted name
2390             70  internal error: unknown opcode in find_fixedlength()
2391             71  \N is not supported in a class
2392             72  too many forward references
2393             73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
2394             74  invalid UTF-16 string (specifically UTF-16)
2395             75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
2396             76  character value in \u.... sequence is too large
2397             77  invalid UTF-32 string (specifically UTF-32)
2398    
2399         The  numbers  32  and 10000 in errors 48 and 49 are defaults; different         The  numbers  32  and 10000 in errors 48 and 49 are defaults; different
2400         values may be used if the limits were changed when PCRE was built.         values may be used if the limits were changed when PCRE was built.
# Line 1468  STUDYING A PATTERN Line 2414  STUDYING A PATTERN
2414         the results of the study.         the results of the study.
2415    
2416         The  returned  value  from  pcre_study()  can  be  passed  directly  to         The  returned  value  from  pcre_study()  can  be  passed  directly  to
2417         pcre_exec().  However,  a  pcre_extra  block also contains other fields         pcre_exec()  or  pcre_dfa_exec(). However, a pcre_extra block also con-
2418         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
2419         described below in the section on matching a pattern.         passed; these are described below in the section on matching a pattern.
2420    
2421         If  studying  the  pattern  does not produce any additional information         If  studying  the  pattern  does  not  produce  any useful information,
2422         pcre_study() returns NULL. In that circumstance, if the calling program         pcre_study() returns NULL by default.  In  that  circumstance,  if  the
2423         wants  to  pass  any of the other fields to pcre_exec(), it must set up         calling program wants to pass any of the other fields to pcre_exec() or
2424         its own pcre_extra block.         pcre_dfa_exec(), it must set up its own pcre_extra block.  However,  if
2425           pcre_study()  is  called  with  the  PCRE_STUDY_EXTRA_NEEDED option, it
2426         The second argument of pcre_study() contains option bits.  At  present,         returns a pcre_extra block even if studying did not find any additional
2427         no options are defined, and this argument should always be zero.         information.  It  may still return NULL, however, if an error occurs in
2428           pcre_study().
2429    
2430           The second argument of pcre_study() contains  option  bits.  There  are
2431           three further options in addition to PCRE_STUDY_EXTRA_NEEDED:
2432    
2433             PCRE_STUDY_JIT_COMPILE
2434             PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
2435             PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
2436    
2437           If  any  of  these are set, and the just-in-time compiler is available,
2438           the pattern is further compiled into machine code  that  executes  much
2439           faster  than  the  pcre_exec()  interpretive  matching function. If the
2440           just-in-time compiler is not available, these options are ignored.  All
2441           undefined bits in the options argument must be zero.
2442    
2443           JIT  compilation  is  a heavyweight optimization. It can take some time
2444           for patterns to be analyzed, and for one-off matches  and  simple  pat-
2445           terns  the benefit of faster execution might be offset by a much slower
2446           study time.  Not all patterns can be optimized by the JIT compiler. For
2447           those  that cannot be handled, matching automatically falls back to the
2448           pcre_exec() interpreter. For more details, see the  pcrejit  documenta-
2449           tion.
2450    
2451         The  third argument for pcre_study() is a pointer for an error message.         The  third argument for pcre_study() is a pointer for an error message.
2452         If studying succeeds (even if no data is  returned),  the  variable  it         If studying succeeds (even if no data is  returned),  the  variable  it
# Line 1487  STUDYING A PATTERN Line 2455  STUDYING A PATTERN
2455         must  not  try  to  free it. You should test the error pointer for NULL         must  not  try  to  free it. You should test the error pointer for NULL
2456         after calling pcre_study(), to be sure that it has run successfully.         after calling pcre_study(), to be sure that it has run successfully.
2457    
2458         This is a typical call to pcre_study():         When you are finished with a pattern, you can free the memory used  for
2459           the study data by calling pcre_free_study(). This function was added to
2460           the API for release 8.20. For earlier versions,  the  memory  could  be
2461           freed  with  pcre_free(), just like the pattern itself. This will still
2462           work in cases where JIT optimization is not used, but it  is  advisable
2463           to change to the new function when convenient.
2464    
2465           This  is  a typical way in which pcre_study() is used (except that in a
2466           real application there should be tests for errors):
2467    
2468           pcre_extra *pe;           int rc;
2469           pe = pcre_study(           pcre *re;
2470             pcre_extra *sd;
2471             re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
2472             sd = pcre_study(
2473             re,             /* result of pcre_compile() */             re,             /* result of pcre_compile() */
2474             0,              /* no options exist */             0,              /* no options */
2475             &error);        /* set to NULL or points to a message */             &error);        /* set to NULL or points to a message */
2476             rc = pcre_exec(   /* see below for details of pcre_exec() options */
2477         At present, studying a pattern is useful only for non-anchored patterns             re, sd, "subject", 7, 0, 0, ovector, 30);
2478         that  do not have a single fixed starting character. A bitmap of possi-           ...
2479         ble starting bytes is created.           pcre_free_study(sd);
2480             pcre_free(re);
2481    
2482           Studying a pattern does two things: first, a lower bound for the length
2483           of subject string that is needed to match the pattern is computed. This
2484           does not mean that there are any strings of that length that match, but
2485           it  does  guarantee that no shorter strings match. The value is used to
2486           avoid wasting time by trying to match strings that are shorter than the
2487           lower  bound.  You  can find out the value in a calling program via the
2488           pcre_fullinfo() function.
2489    
2490           Studying a pattern is also useful for non-anchored patterns that do not
2491           have  a  single fixed starting character. A bitmap of possible starting
2492           bytes is created. This speeds up finding a position in the  subject  at
2493           which to start matching. (In 16-bit mode, the bitmap is used for 16-bit
2494           values less than 256.  In 32-bit mode, the bitmap is  used  for  32-bit
2495           values less than 256.)
2496    
2497           These  two optimizations apply to both pcre_exec() and pcre_dfa_exec(),
2498           and the information is also used by the JIT  compiler.   The  optimiza-
2499           tions can be disabled by setting the PCRE_NO_START_OPTIMIZE option when
2500           calling pcre_exec() or pcre_dfa_exec(), but if this is done, JIT execu-
2501           tion  is  also disabled. You might want to do this if your pattern con-
2502           tains callouts or (*MARK) and you want to make use of these  facilities
2503           in    cases    where    matching   fails.   See   the   discussion   of
2504           PCRE_NO_START_OPTIMIZE below.
2505    
2506    
2507  LOCALE SUPPORT  LOCALE SUPPORT
# Line 1505  LOCALE SUPPORT Line 2509  LOCALE SUPPORT
2509         PCRE handles caseless matching, and determines whether  characters  are         PCRE handles caseless matching, and determines whether  characters  are
2510         letters,  digits, or whatever, by reference to a set of tables, indexed         letters,  digits, or whatever, by reference to a set of tables, indexed
2511         by character value. When running in UTF-8 mode, this  applies  only  to         by character value. When running in UTF-8 mode, this  applies  only  to
2512         characters  with  codes  less than 128. Higher-valued codes never match         characters  with  codes  less than 128. By default, higher-valued codes
2513         escapes such as \w or \d, but can be tested with \p if  PCRE  is  built         never match escapes such as \w or \d, but they can be tested with \p if
2514         with  Unicode  character property support. The use of locales with Uni-         PCRE  is  built with Unicode character property support. Alternatively,
2515         code is discouraged. If you are handling characters with codes  greater         the PCRE_UCP option can be set at compile  time;  this  causes  \w  and
2516         than  128, you should either use UTF-8 and Unicode, or use locales, but         friends to use Unicode property support instead of built-in tables. The
2517         not try to mix the two.         use of locales with Unicode is discouraged. If you are handling charac-
2518           ters  with codes greater than 128, you should either use UTF-8 and Uni-
2519           code, or use locales, but not try to mix the two.
2520    
2521         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
2522         argument  of  pcre_compile()  is  NULL.  These  are sufficient for many         argument  of  pcre_compile()  is  NULL.  These  are sufficient for many
# Line 1562  INFORMATION ABOUT A PATTERN Line 2568  INFORMATION ABOUT A PATTERN
2568              int what, void *where);              int what, void *where);
2569    
2570         The  pcre_fullinfo() function returns information about a compiled pat-         The  pcre_fullinfo() function returns information about a compiled pat-
2571         tern. It replaces the obsolete pcre_info() function, which is neverthe-         tern. It replaces the pcre_info() function, which was removed from  the
2572         less retained for backwards compability (and is documented below).         library at version 8.30, after more than 10 years of obsolescence.
2573    
2574         The  first  argument  for  pcre_fullinfo() is a pointer to the compiled         The  first  argument  for  pcre_fullinfo() is a pointer to the compiled
2575         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
# Line 1572  INFORMATION ABOUT A PATTERN Line 2578  INFORMATION ABOUT A PATTERN
2578         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
2579         success, or one of the following negative numbers:         success, or one of the following negative numbers:
2580    
2581           PCRE_ERROR_NULL       the argument code was NULL           PCRE_ERROR_NULL           the argument code was NULL
2582                                 the argument where was NULL                                     the argument where was NULL
2583           PCRE_ERROR_BADMAGIC   the "magic number" was not found           PCRE_ERROR_BADMAGIC       the "magic number" was not found
2584           PCRE_ERROR_BADOPTION  the value of what was invalid           PCRE_ERROR_BADENDIANNESS  the pattern was compiled with different
2585                                       endianness
2586             PCRE_ERROR_BADOPTION      the value of what was invalid
2587    
2588         The "magic number" is placed at the start of each compiled  pattern  as         The "magic number" is placed at the start of each compiled  pattern  as
2589         an  simple check against passing an arbitrary memory pointer. Here is a         an  simple check against passing an arbitrary memory pointer. The endi-
2590         typical call of pcre_fullinfo(), to obtain the length of  the  compiled         anness error can occur if a compiled pattern is saved and reloaded on a
2591         pattern:         different  host.  Here  is a typical call of pcre_fullinfo(), to obtain
2592           the length of the compiled pattern:
2593    
2594           int rc;           int rc;
2595           size_t length;           size_t length;
2596           rc = pcre_fullinfo(           rc = pcre_fullinfo(
2597             re,               /* result of pcre_compile() */             re,               /* result of pcre_compile() */
2598             pe,               /* result of pcre_study(), or NULL */             sd,               /* result of pcre_study(), or NULL */
2599             PCRE_INFO_SIZE,   /* what is required */             PCRE_INFO_SIZE,   /* what is required */
2600             &length);         /* where to put the data */             &length);         /* where to put the data */
2601    
2602         The  possible  values for the third argument are defined in pcre.h, and         The possible values for the third argument are defined in  pcre.h,  and
2603         are as follows:         are as follows:
2604    
2605           PCRE_INFO_BACKREFMAX           PCRE_INFO_BACKREFMAX
2606    
2607         Return the number of the highest back reference  in  the  pattern.  The         Return  the  number  of  the highest back reference in the pattern. The
2608         fourth  argument  should  point to an int variable. Zero is returned if         fourth argument should point to an int variable. Zero  is  returned  if
2609         there are no back references.         there are no back references.
2610    
2611           PCRE_INFO_CAPTURECOUNT           PCRE_INFO_CAPTURECOUNT
2612    
2613         Return the number of capturing subpatterns in the pattern.  The  fourth         Return  the  number of capturing subpatterns in the pattern. The fourth
2614         argument should point to an int variable.         argument should point to an int variable.
2615    
2616           PCRE_INFO_DEFAULT_TABLES           PCRE_INFO_DEFAULT_TABLES
2617    
2618         Return  a pointer to the internal default character tables within PCRE.         Return a pointer to the internal default character tables within  PCRE.
2619         The fourth argument should point to an unsigned char *  variable.  This         The  fourth  argument should point to an unsigned char * variable. This
2620         information call is provided for internal use by the pcre_study() func-         information call is provided for internal use by the pcre_study() func-
2621         tion. External callers can cause PCRE to use  its  internal  tables  by         tion.  External  callers  can  cause PCRE to use its internal tables by
2622         passing a NULL table pointer.         passing a NULL table pointer.
2623    
2624           PCRE_INFO_FIRSTBYTE           PCRE_INFO_FIRSTBYTE
2625    
2626         Return  information  about  the first byte of any matched string, for a         Return information about the first data unit of any matched string, for
2627         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
2628         able.  (This option used to be called PCRE_INFO_FIRSTCHAR; the old name         library, where data units are bytes.) The fourth argument should  point
2629         is still recognized for backwards compatibility.)         to an int variable.
2630    
2631           If  there  is  a  fixed first value, for example, the letter "c" from a
2632           pattern such as (cat|cow|coyote), its value is returned. In  the  8-bit
2633           library,  the  value is always less than 256. In the 16-bit library the
2634           value can be up to 0xffff. In the 32-bit library the value can be up to
2635           0x10ffff.
2636    
2637         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  
2638    
2639         (a)  the pattern was compiled with the PCRE_MULTILINE option, and every         (a)  the pattern was compiled with the PCRE_MULTILINE option, and every
2640         branch starts with "^", or         branch starts with "^", or
# Line 1632  INFORMATION ABOUT A PATTERN Line 2646  INFORMATION ABOUT A PATTERN
2646         of a subject string or after any newline within the  string.  Otherwise         of a subject string or after any newline within the  string.  Otherwise
2647         -2 is returned. For anchored patterns, -2 is returned.         -2 is returned. For anchored patterns, -2 is returned.
2648    
2649           Since  for  the 32-bit library using the non-UTF-32 mode, this function
2650           is unable to return the full 32-bit range of the character, this  value
2651           is    deprecated;   instead   the   PCRE_INFO_FIRSTCHARACTERFLAGS   and
2652           PCRE_INFO_FIRSTCHARACTER values should be used.
2653    
2654           PCRE_INFO_FIRSTTABLE           PCRE_INFO_FIRSTTABLE
2655    
2656         If  the pattern was studied, and this resulted in the construction of a         If the pattern was studied, and this resulted in the construction of  a
2657         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
2658         matching  string, a pointer to the table is returned. Otherwise NULL is         in any matching string, a pointer to the table is  returned.  Otherwise
2659         returned. The fourth argument should point to an unsigned char *  vari-         NULL  is returned. The fourth argument should point to an unsigned char
2660         able.         * variable.
2661    
2662           PCRE_INFO_HASCRORLF           PCRE_INFO_HASCRORLF
2663    
2664         Return  1  if  the  pattern  contains any explicit matches for CR or LF         Return 1 if the pattern contains any explicit  matches  for  CR  or  LF
2665         characters, otherwise 0. The fourth argument should  point  to  an  int         characters,  otherwise  0.  The  fourth argument should point to an int
2666         variable.  An explicit match is either a literal CR or LF character, or         variable. An explicit match is either a literal CR or LF character,  or
2667         \r or \n.         \r or \n.
2668    
2669           PCRE_INFO_JCHANGED           PCRE_INFO_JCHANGED
2670    
2671         Return 1 if the (?J) or (?-J) option setting is used  in  the  pattern,         Return  1  if  the (?J) or (?-J) option setting is used in the pattern,
2672         otherwise  0. The fourth argument should point to an int variable. (?J)         otherwise 0. The fourth argument should point to an int variable.  (?J)
2673         and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.         and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
2674    
2675             PCRE_INFO_JIT
2676    
2677           Return  1  if  the pattern was studied with one of the JIT options, and
2678           just-in-time compiling was successful. The fourth argument should point
2679           to  an  int variable. A return value of 0 means that JIT support is not
2680           available in this version of PCRE, or that the pattern was not  studied
2681           with  a JIT option, or that the JIT compiler could not handle this par-
2682           ticular pattern. See the pcrejit documentation for details of what  can
2683           and cannot be handled.
2684    
2685             PCRE_INFO_JITSIZE
2686    
2687           If  the  pattern was successfully studied with a JIT option, return the
2688           size of the JIT compiled code, otherwise return zero. The fourth  argu-
2689           ment should point to a size_t variable.
2690    
2691           PCRE_INFO_LASTLITERAL           PCRE_INFO_LASTLITERAL
2692    
2693         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
2694         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
2695         recorded. The fourth argument should point to an int variable. If there         recorded. The fourth argument should point to an int variable. If there
2696         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
2697         byte is recorded only if it follows something of variable  length.  For         value  is recorded only if it follows something of variable length. For
2698         example, for the pattern /^a\d+z\d+/ the returned value is "z", but for         example, for the pattern /^a\d+z\d+/ the returned value is "z", but for
2699         /^a\dz\d/ the returned value is -1.         /^a\dz\d/ the returned value is -1.
2700    
2701           Since  for  the 32-bit library using the non-UTF-32 mode, this function
2702           is unable to return the full 32-bit range of the character, this  value
2703           is    deprecated;    instead    the   PCRE_INFO_REQUIREDCHARFLAGS   and
2704           PCRE_INFO_REQUIREDCHAR values should be used.
2705    
2706             PCRE_INFO_MAXLOOKBEHIND
2707    
2708           Return the number of characters (NB not bytes) in the  longest  lookbe-
2709           hind  assertion  in the pattern. Note that the simple assertions \b and
2710           \B require a one-character lookbehind. This information is useful  when
2711           doing multi-segment matching using the partial matching facilities.
2712    
2713             PCRE_INFO_MINLENGTH
2714    
2715           If  the  pattern  was studied and a minimum length for matching subject
2716           strings was computed, its value is  returned.  Otherwise  the  returned
2717           value  is  -1. The value is a number of characters, which in UTF-8 mode
2718           may be different from the number of bytes. The fourth  argument  should
2719           point  to an int variable. A non-negative value is a lower bound to the
2720           length of any matching string. There may not be  any  strings  of  that
2721           length  that  do actually match, but every string that does match is at
2722           least that long.
2723    
2724           PCRE_INFO_NAMECOUNT           PCRE_INFO_NAMECOUNT
2725           PCRE_INFO_NAMEENTRYSIZE           PCRE_INFO_NAMEENTRYSIZE
2726           PCRE_INFO_NAMETABLE           PCRE_INFO_NAMETABLE
# Line 1681  INFORMATION ABOUT A PATTERN Line 2739  INFORMATION ABOUT A PATTERN
2739         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size
2740         of each entry; both of these  return  an  int  value.  The  entry  size         of each entry; both of these  return  an  int  value.  The  entry  size
2741         depends  on the length of the longest name. PCRE_INFO_NAMETABLE returns         depends  on the length of the longest name. PCRE_INFO_NAMETABLE returns
2742         a pointer to the first entry of the table  (a  pointer  to  char).  The         a pointer to the first entry of the table. This is a pointer to char in
2743         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-
2744         sis, most significant byte first. The rest of the entry is  the  corre-         ber of the capturing parenthesis, most significant byte first.  In  the
2745         sponding  name,  zero  terminated. The names are in alphabetical order.         16-bit  library,  the pointer points to 16-bit data units, the first of
2746         When PCRE_DUPNAMES is set, duplicate names are in order of their paren-         which contains the parenthesis number.   In  the  32-bit  library,  the
2747         theses  numbers.  For  example,  consider the following pattern (assume         pointer  points  to  32-bit data units, the first of which contains the
2748         PCRE_EXTENDED is  set,  so  white  space  -  including  newlines  -  is         parenthesis number. The rest of the entry is  the  corresponding  name,
2749         ignored):         zero terminated.
2750    
2751           The  names are in alphabetical order. Duplicate names may appear if (?|
2752           is used to create multiple groups with the same number, as described in
2753           the  section  on  duplicate subpattern numbers in the pcrepattern page.
2754           Duplicate names for subpatterns with different  numbers  are  permitted
2755           only  if  PCRE_DUPNAMES  is  set. In all cases of duplicate names, they
2756           appear in the table in the order in which they were found in  the  pat-
2757           tern.  In  the  absence  of (?| this is the order of increasing number;
2758           when (?| is used this is not necessarily the case because later subpat-
2759           terns may have lower numbers.
2760    
2761           As  a  simple  example of the name/number table, consider the following
2762           pattern after compilation by the 8-bit library (assume PCRE_EXTENDED is
2763           set, so white space - including newlines - is ignored):
2764    
2765           (?<date> (?<year>(\d\d)?\d\d) -           (?<date> (?<year>(\d\d)?\d\d) -
2766           (?<month>\d\d) - (?<day>\d\d) )           (?<month>\d\d) - (?<day>\d\d) )
# Line 1709  INFORMATION ABOUT A PATTERN Line 2781  INFORMATION ABOUT A PATTERN
2781    
2782           PCRE_INFO_OKPARTIAL           PCRE_INFO_OKPARTIAL
2783    
2784         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
2785         The  fourth  argument  should point to an int variable. The pcrepartial         pcre_exec(),  otherwise  0.  The fourth argument should point to an int
2786         documentation lists the restrictions that apply to patterns  when  par-         variable. From  release  8.00,  this  always  returns  1,  because  the
2787         tial matching is used.         restrictions  that  previously  applied  to  partial matching have been
2788           lifted. The pcrepartial documentation gives details of  partial  match-
2789           ing.
2790    
2791           PCRE_INFO_OPTIONS           PCRE_INFO_OPTIONS
2792    
# Line 1739  INFORMATION ABOUT A PATTERN Line 2813  INFORMATION ABOUT A PATTERN
2813    
2814           PCRE_INFO_SIZE           PCRE_INFO_SIZE
2815    
2816         Return the size of the compiled pattern, that is, the  value  that  was         Return the size of the compiled pattern in bytes (for both  libraries).
2817         passed as the argument to pcre_malloc() when PCRE was getting memory in         The  fourth argument should point to a size_t variable. This value does
2818         which to place the compiled data. The fourth argument should point to a         not include the  size  of  the  pcre  structure  that  is  returned  by
2819         size_t variable.         pcre_compile().  The  value that is passed as the argument to pcre_mal-
2820           loc() when pcre_compile() is getting memory in which to place the  com-
2821           piled  data  is  the value returned by this option plus the size of the
2822           pcre structure. Studying a compiled pattern, with or without JIT,  does
2823           not alter the value returned by this option.
2824    
2825           PCRE_INFO_STUDYSIZE           PCRE_INFO_STUDYSIZE
2826    
2827         Return the size of the data block pointed to by the study_data field in         Return the size in bytes of the data block pointed to by the study_data
2828         a pcre_extra block. That is,  it  is  the  value  that  was  passed  to         field in a pcre_extra block. If pcre_extra is  NULL,  or  there  is  no
2829         pcre_malloc() when PCRE was getting memory into which to place the data         study  data,  zero  is  returned. The fourth argument should point to a
2830         created by pcre_study(). The fourth argument should point to  a  size_t         size_t variable. The study_data field is set by pcre_study() to  record
2831           information  that  will  speed  up  matching  (see the section entitled
2832           "Studying a pattern" above). The format of the study_data block is pri-
2833           vate,  but  its length is made available via this option so that it can
2834           be  saved  and  restored  (see  the  pcreprecompile  documentation  for
2835           details).
2836    
2837             PCRE_INFO_FIRSTCHARACTERFLAGS
2838    
2839           Return information about the first data unit of any matched string, for
2840           a non-anchored pattern. The fourth argument  should  point  to  an  int
2841         variable.         variable.
2842    
2843           If  there  is  a  fixed first value, for example, the letter "c" from a
2844           pattern such as (cat|cow|coyote), 1  is  returned,  and  the  character
2845           value can be retrieved using PCRE_INFO_FIRSTCHARACTER.
2846    
2847           If there is no fixed first value, and if either
2848    
2849           (a)  the pattern was compiled with the PCRE_MULTILINE option, and every
2850           branch starts with "^", or
2851    
2852           (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2853           set (if it were set, the pattern would be anchored),
2854    
2855           2 is returned, indicating that the pattern matches only at the start of
2856           a subject string or after any newline within the string. Otherwise 0 is
2857           returned. For anchored patterns, 0 is returned.
2858    
2859  OBSOLETE INFO FUNCTION           PCRE_INFO_FIRSTCHARACTER
2860    
2861         int pcre_info(const pcre *code, int *optptr, int *firstcharptr);         Return  the  fixed  first character value, if PCRE_INFO_FIRSTCHARACTER-
2862           FLAGS returned 1; otherwise returns 0. The fourth argument should point
2863           to an uint_t variable.
2864    
2865         The  pcre_info()  function is now obsolete because its interface is too         In  the 8-bit library, the value is always less than 256. In the 16-bit
2866         restrictive to return all the available data about a compiled  pattern.         library the value can be up to 0xffff. In the 32-bit library in  UTF-32
2867         New   programs   should  use  pcre_fullinfo()  instead.  The  yield  of         mode  the  value  can  be up to 0x10ffff, and up to 0xffffffff when not
2868         pcre_info() is the number of capturing subpatterns, or one of the  fol-         using UTF-32 mode.
2869         lowing negative numbers:  
2870           If there is no fixed first value, and if either
2871           PCRE_ERROR_NULL       the argument code was NULL  
2872           PCRE_ERROR_BADMAGIC   the "magic number" was not found         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
2873           branch starts with "^", or
2874         If  the  optptr  argument is not NULL, a copy of the options with which  
2875         the pattern was compiled is placed in the integer  it  points  to  (see         (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2876         PCRE_INFO_OPTIONS above).         set (if it were set, the pattern would be anchored),
2877    
2878         If  the  pattern  is  not anchored and the firstcharptr argument is not         -1 is returned, indicating that the pattern matches only at  the  start
2879         NULL, it is used to pass back information about the first character  of         of  a  subject string or after any newline within the string. Otherwise
2880         any matched string (see PCRE_INFO_FIRSTBYTE above).         -2 is returned. For anchored patterns, -2 is returned.
2881    
2882             PCRE_INFO_REQUIREDCHARFLAGS
2883    
2884           Returns 1 if there is a rightmost literal data unit that must exist  in
2885           any matched string, other than at its start. The fourth argument should
2886           point to an int variable. If there is no such value, 0 is returned.  If
2887           returning  1,  the  character  value  itself  can  be  retrieved  using
2888           PCRE_INFO_REQUIREDCHAR.
2889    
2890           For anchored patterns, a last literal value is recorded only if it fol-
2891           lows  something  of  variable  length.  For  example,  for  the pattern
2892           /^a\d+z\d+/  the   returned   value   1   (with   "z"   returned   from
2893           PCRE_INFO_REQUIREDCHAR), but for /^a\dz\d/ the returned value is 0.
2894    
2895             PCRE_INFO_REQUIREDCHAR
2896    
2897           Return  the value of the rightmost literal data unit that must exist in
2898           any matched string, other than at its start, if such a value  has  been
2899           recorded.  The fourth argument should point to an uint32_t variable. If
2900           there is no such value, 0 is returned.
2901    
2902    
2903  REFERENCE COUNTS  REFERENCE COUNTS
2904    
2905         int pcre_refcount(pcre *code, int adjust);         int pcre_refcount(pcre *code, int adjust);
2906    
2907         The  pcre_refcount()  function is used to maintain a reference count in         The pcre_refcount() function is used to maintain a reference  count  in
2908         the data block that contains a compiled pattern. It is provided for the         the data block that contains a compiled pattern. It is provided for the
2909         benefit  of  applications  that  operate  in an object-oriented manner,         benefit of applications that  operate  in  an  object-oriented  manner,
2910         where different parts of the application may be using the same compiled         where different parts of the application may be using the same compiled
2911         pattern, but you want to free the block when they are all done.         pattern, but you want to free the block when they are all done.
2912    
2913         When a pattern is compiled, the reference count field is initialized to         When a pattern is compiled, the reference count field is initialized to
2914         zero.  It is changed only by calling this function, whose action is  to         zero.   It is changed only by calling this function, whose action is to
2915         add  the  adjust  value  (which may be positive or negative) to it. The         add the adjust value (which may be positive or  negative)  to  it.  The
2916         yield of the function is the new value. However, the value of the count         yield of the function is the new value. However, the value of the count
2917         is  constrained to lie between 0 and 65535, inclusive. If the new value         is constrained to lie between 0 and 65535, inclusive. If the new  value
2918         is outside these limits, it is forced to the appropriate limit value.         is outside these limits, it is forced to the appropriate limit value.
2919    
2920         Except when it is zero, the reference count is not correctly  preserved         Except  when it is zero, the reference count is not correctly preserved
2921         if  a  pattern  is  compiled on one host and then transferred to a host         if a pattern is compiled on one host and then  transferred  to  a  host
2922         whose byte-order is different. (This seems a highly unlikely scenario.)         whose byte-order is different. (This seems a highly unlikely scenario.)
2923    
2924    
# Line 1805  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2930  MATCHING A PATTERN: THE TRADITIONAL FUNC
2930    
2931         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
2932         compiled pattern, which is passed in the code argument. If the  pattern         compiled pattern, which is passed in the code argument. If the  pattern
2933         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
2934         argument. This function is the main matching facility of  the  library,         argument. You can call pcre_exec() with the same code and  extra  argu-
2935         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
2936         an alternative matching function, which is described below in the  sec-         strings with the same pattern.
2937         tion about the pcre_dfa_exec() function.  
2938           This function is the main matching facility  of  the  library,  and  it
2939           operates  in  a  Perl-like  manner. For specialist use there is also an
2940           alternative matching function, which is described below in the  section
2941           about the pcre_dfa_exec() function.
2942    
2943         In  most applications, the pattern will have been compiled (and option-         In  most applications, the pattern will have been compiled (and option-
2944         ally studied) in the same process that calls pcre_exec().  However,  it         ally studied) in the same process that calls pcre_exec().  However,  it
# Line 1841  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2970  MATCHING A PATTERN: THE TRADITIONAL FUNC
2970    
2971           unsigned long int flags;           unsigned long int flags;
2972           void *study_data;           void *study_data;
2973             void *executable_jit;
2974           unsigned long int match_limit;           unsigned long int match_limit;
2975           unsigned long int match_limit_recursion;           unsigned long int match_limit_recursion;
2976           void *callout_data;           void *callout_data;
2977           const unsigned char *tables;           const unsigned char *tables;
2978             unsigned char **mark;
2979    
2980         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
2981         are set. The flag bits are:         "PCRE_UCHAR16 **".
2982    
2983           PCRE_EXTRA_STUDY_DATA         In the 32-bit version of  this  structure,  the  mark  field  has  type
2984           "PCRE_UCHAR32 **".
2985    
2986           The  flags  field is used to specify which of the other fields are set.
2987           The flag bits are:
2988    
2989             PCRE_EXTRA_CALLOUT_DATA
2990             PCRE_EXTRA_EXECUTABLE_JIT
2991             PCRE_EXTRA_MARK
2992           PCRE_EXTRA_MATCH_LIMIT           PCRE_EXTRA_MATCH_LIMIT
2993           PCRE_EXTRA_MATCH_LIMIT_RECURSION           PCRE_EXTRA_MATCH_LIMIT_RECURSION
2994           PCRE_EXTRA_CALLOUT_DATA           PCRE_EXTRA_STUDY_DATA
2995           PCRE_EXTRA_TABLES           PCRE_EXTRA_TABLES
2996    
2997         Other flag bits should be set to zero. The study_data field is  set  in         Other flag bits should be set to zero. The study_data field  and  some-
2998         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
2999         the appropriate flag bit. You should not set this yourself, but you may         returned by pcre_study(), together with the appropriate flag bits.  You
3000         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
3001         flag bits.         other fields and their corresponding flag bits.
3002    
3003         The match_limit field provides a means of preventing PCRE from using up         The match_limit field provides a means of preventing PCRE from using up
3004         a  vast amount of resources when running patterns that are not going to         a  vast amount of resources when running patterns that are not going to
3005         match, but which have a very large number  of  possibilities  in  their         match, but which have a very large number  of  possibilities  in  their
3006         search  trees.  The  classic  example  is  the  use of nested unlimited         search  trees. The classic example is a pattern that uses nested unlim-
3007         repeats.         ited repeats.
3008    
3009         Internally, PCRE uses a function called match() which it calls  repeat-         Internally, pcre_exec() uses a function called match(), which it  calls
3010         edly  (sometimes  recursively). The limit set by match_limit is imposed         repeatedly  (sometimes  recursively).  The  limit set by match_limit is
3011         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,
3012         has  the  effect  of  limiting the amount of backtracking that can take         which  has  the  effect of limiting the amount of backtracking that can
3013         place. For patterns that are not anchored, the count restarts from zero         take place. For patterns that are not anchored, the count restarts from
3014         for each position in the subject string.         zero for each position in the subject string.
3015    
3016         The  default  value  for  the  limit can be set when PCRE is built; the         When pcre_exec() is called with a pattern that was successfully studied
3017         default default is 10 million, which handles all but the  most  extreme         with a JIT option, the way that the matching is  executed  is  entirely
3018         cases.  You  can  override  the  default by suppling pcre_exec() with a         different.  However, there is still the possibility of runaway matching
3019         pcre_extra    block    in    which    match_limit    is    set,     and         that goes on for a very long time, and so the match_limit value is also
3020         PCRE_EXTRA_MATCH_LIMIT  is  set  in  the  flags  field. If the limit is         used in this case (but in a different way) to limit how long the match-
3021           ing can continue.
3022    
3023           The default value for the limit can be set  when  PCRE  is  built;  the
3024           default  default  is 10 million, which handles all but the most extreme
3025           cases. You can override the default  by  suppling  pcre_exec()  with  a
3026           pcre_extra     block    in    which    match_limit    is    set,    and
3027           PCRE_EXTRA_MATCH_LIMIT is set in the  flags  field.  If  the  limit  is
3028         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
3029    
3030         The match_limit_recursion field is similar to match_limit, but  instead         The  match_limit_recursion field is similar to match_limit, but instead
3031         of limiting the total number of times that match() is called, it limits         of limiting the total number of times that match() is called, it limits
3032         the depth of recursion. The recursion depth is a  smaller  number  than         the  depth  of  recursion. The recursion depth is a smaller number than
3033         the  total number of calls, because not all calls to match() are recur-         the total number of calls, because not all calls to match() are  recur-
3034         sive.  This limit is of use only if it is set smaller than match_limit.         sive.  This limit is of use only if it is set smaller than match_limit.
3035    
3036         Limiting  the  recursion  depth  limits the amount of stack that can be         Limiting  the  recursion  depth limits the amount of machine stack that
3037         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
3038         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
3039           limit is not relevant, and is ignored, when matching is done using  JIT
3040           compiled code.
3041    
3042         The  default  value  for  match_limit_recursion can be set when PCRE is         The  default  value  for  match_limit_recursion can be set when PCRE is
3043         built; the default default  is  the  same  value  as  the  default  for         built; the default default  is  the  same  value  as  the  default  for
# Line 1898  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3046  MATCHING A PATTERN: THE TRADITIONAL FUNC
3046         PCRE_EXTRA_MATCH_LIMIT_RECURSION  is  set  in  the  flags field. If the         PCRE_EXTRA_MATCH_LIMIT_RECURSION  is  set  in  the  flags field. If the
3047         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.
3048    
3049         The pcre_callout field is used in conjunction with the  "callout"  fea-         The callout_data field is used in conjunction with the  "callout"  fea-
3050         ture, which is described in the pcrecallout documentation.         ture, and is described in the pcrecallout documentation.
3051    
3052         The  tables  field  is  used  to  pass  a  character  tables pointer to         The  tables  field  is  used  to  pass  a  character  tables pointer to
3053         pcre_exec(); this overrides the value that is stored with the  compiled         pcre_exec(); this overrides the value that is stored with the  compiled
# Line 1912  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3060  MATCHING A PATTERN: THE TRADITIONAL FUNC
3060         address  when  pcre_exec() is called. See the pcreprecompile documenta-         address  when  pcre_exec() is called. See the pcreprecompile documenta-
3061         tion for a discussion of saving compiled patterns for later use.         tion for a discussion of saving compiled patterns for later use.
3062    
3063           If PCRE_EXTRA_MARK is set in the flags field, the mark  field  must  be
3064           set  to point to a suitable variable. If the pattern contains any back-
3065           tracking control verbs such as (*MARK:NAME), and the execution ends  up
3066           with  a  name  to  pass back, a pointer to the name string (zero termi-
3067           nated) is placed in the variable pointed to  by  the  mark  field.  The
3068           names  are  within  the  compiled pattern; if you wish to retain such a
3069           name you must copy it before freeing the memory of a compiled  pattern.
3070           If  there  is no name to pass back, the variable pointed to by the mark
3071           field is set to NULL. For details of the  backtracking  control  verbs,
3072           see the section entitled "Backtracking control" in the pcrepattern doc-
3073           umentation.
3074    
3075     Option bits for pcre_exec()     Option bits for pcre_exec()
3076    
3077         The unused bits of the options argument for pcre_exec() must  be  zero.         The unused bits of the options argument for pcre_exec() must  be  zero.
3078         The  only  bits  that  may  be set are PCRE_ANCHORED, PCRE_NEWLINE_xxx,         The  only  bits  that  may  be set are PCRE_ANCHORED, PCRE_NEWLINE_xxx,
3079         PCRE_NOTBOL,   PCRE_NOTEOL,   PCRE_NOTEMPTY,   PCRE_NO_UTF8_CHECK   and         PCRE_NOTBOL,   PCRE_NOTEOL,    PCRE_NOTEMPTY,    PCRE_NOTEMPTY_ATSTART,
3080         PCRE_PARTIAL.         PCRE_NO_START_OPTIMIZE,   PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_HARD,  and
3081           PCRE_PARTIAL_SOFT.
3082    
3083           If the pattern was successfully studied with one  of  the  just-in-time
3084           (JIT) compile options, the only supported options for JIT execution are
3085           PCRE_NO_UTF8_CHECK,    PCRE_NOTBOL,     PCRE_NOTEOL,     PCRE_NOTEMPTY,
3086           PCRE_NOTEMPTY_ATSTART,  PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an
3087           unsupported option is used, JIT execution is disabled  and  the  normal
3088           interpretive code in pcre_exec() is run.
3089    
3090           PCRE_ANCHORED           PCRE_ANCHORED
3091    
# Line 1997  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3165  MATCHING A PATTERN: THE TRADITIONAL FUNC
3165    
3166           a?b?           a?b?
3167    
3168         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
3169         empty  string at the start of the subject. With PCRE_NOTEMPTY set, this         empty  string at the start of the subject. With PCRE_NOTEMPTY set, this
3170         match is not valid, so PCRE searches further into the string for occur-         match is not valid, so PCRE searches further into the string for occur-
3171         rences of "a" or "b".         rences of "a" or "b".
3172    
3173         Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a spe-           PCRE_NOTEMPTY_ATSTART
3174         cial case of a pattern match of the empty  string  within  its  split()  
3175         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
3176         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
3177         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.
3178         if that fails by advancing the starting offset (see below)  and  trying  
3179         an ordinary match again. There is some code that demonstrates how to do         Perl     has    no    direct    equivalent    of    PCRE_NOTEMPTY    or
3180         this in the pcredemo.c sample program.         PCRE_NOTEMPTY_ATSTART, but it does make a special  case  of  a  pattern
3181           match  of  the empty string within its split() function, and when using
3182           the /g modifier. It is  possible  to  emulate  Perl's  behaviour  after
3183           matching a null string by first trying the match again at the same off-
3184           set with PCRE_NOTEMPTY_ATSTART and  PCRE_ANCHORED,  and  then  if  that
3185           fails, by advancing the starting offset (see below) and trying an ordi-
3186           nary match again. There is some code that demonstrates how to  do  this
3187           in  the  pcredemo sample program. In the most general case, you have to
3188           check to see if the newline convention recognizes CRLF  as  a  newline,
3189           and  if so, and the current character is CR followed by LF, advance the
3190           starting offset by two characters instead of one.
3191    
3192             PCRE_NO_START_OPTIMIZE
3193    
3194           There are a number of optimizations that pcre_exec() uses at the  start
3195           of  a  match,  in  order to speed up the process. For example, if it is
3196           known that an unanchored match must start with a specific character, it
3197           searches  the  subject  for that character, and fails immediately if it
3198           cannot find it, without actually running the  main  matching  function.
3199           This means that a special item such as (*COMMIT) at the start of a pat-
3200           tern is not considered until after a suitable starting  point  for  the
3201           match  has been found. When callouts or (*MARK) items are in use, these
3202           "start-up" optimizations can cause them to be skipped if the pattern is
3203           never  actually  used.  The start-up optimizations are in effect a pre-
3204           scan of the subject that takes place before the pattern is run.
3205    
3206           The PCRE_NO_START_OPTIMIZE option disables the start-up  optimizations,
3207           possibly  causing  performance  to  suffer,  but ensuring that in cases
3208           where the result is "no match", the callouts do occur, and  that  items
3209           such as (*COMMIT) and (*MARK) are considered at every possible starting
3210           position in the subject string. If  PCRE_NO_START_OPTIMIZE  is  set  at
3211           compile  time,  it  cannot  be  unset  at  matching  time.  The  use of
3212           PCRE_NO_START_OPTIMIZE disables JIT execution; when it is set, matching
3213           is always done using interpretively.
3214    
3215           Setting  PCRE_NO_START_OPTIMIZE  can  change  the outcome of a matching
3216           operation.  Consider the pattern
3217    
3218             (*COMMIT)ABC
3219    
3220           When this is compiled, PCRE records the fact that a  match  must  start
3221           with  the  character  "A".  Suppose the subject string is "DEFABC". The
3222           start-up optimization scans along the subject, finds "A" and  runs  the
3223           first  match attempt from there. The (*COMMIT) item means that the pat-
3224           tern must match the current starting position, which in this  case,  it
3225           does.  However,  if  the  same match is run with PCRE_NO_START_OPTIMIZE
3226           set, the initial scan along the subject string  does  not  happen.  The
3227           first  match  attempt  is  run  starting  from "D" and when this fails,
3228           (*COMMIT) prevents any further matches  being  tried,  so  the  overall
3229           result  is  "no  match". If the pattern is studied, more start-up opti-
3230           mizations may be used. For example, a minimum length  for  the  subject
3231           may be recorded. Consider the pattern
3232    
3233             (*MARK:A)(X|Y)
3234    
3235           The  minimum  length  for  a  match is one character. If the subject is
3236           "ABC", there will be attempts to  match  "ABC",  "BC",  "C",  and  then
3237           finally  an empty string.  If the pattern is studied, the final attempt
3238           does not take place, because PCRE knows that the subject is too  short,
3239           and  so  the  (*MARK) is never encountered.  In this case, studying the
3240           pattern does not affect the overall match result, which  is  still  "no
3241           match", but it does affect the auxiliary information that is returned.
3242    
3243           PCRE_NO_UTF8_CHECK           PCRE_NO_UTF8_CHECK
3244    
3245         When PCRE_UTF8 is set at compile time, the validity of the subject as a         When PCRE_UTF8 is set at compile time, the validity of the subject as a
3246         UTF-8  string is automatically checked when pcre_exec() is subsequently         UTF-8 string is automatically checked when pcre_exec() is  subsequently
3247         called.  The value of startoffset is also checked  to  ensure  that  it         called.  The entire string is checked before any other processing takes
3248           place. The value of startoffset is  also  checked  to  ensure  that  it
3249         points  to  the start of a UTF-8 character. There is a discussion about         points  to  the start of a UTF-8 character. There is a discussion about
3250         the validity of UTF-8 strings in the section on UTF-8  support  in  the         the validity of UTF-8 strings in the pcreunicode page.  If  an  invalid
3251         main  pcre  page.  If  an  invalid  UTF-8  sequence  of bytes is found,         sequence   of   bytes   is   found,   pcre_exec()   returns  the  error
3252         pcre_exec() returns the error PCRE_ERROR_BADUTF8. If  startoffset  con-         PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a
3253         tains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.         truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
3254           both cases, information about the precise nature of the error may  also
3255         If  you  already  know that your subject is valid, and you want to skip         be  returned (see the descriptions of these errors in the section enti-
3256         these   checks   for   performance   reasons,   you   can    set    the         tled Error return values from pcre_exec() below).  If startoffset  con-
3257         PCRE_NO_UTF8_CHECK  option  when calling pcre_exec(). You might want to         tains a value that does not point to the start of a UTF-8 character (or
3258         do this for the second and subsequent calls to pcre_exec() if  you  are         to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is returned.
3259         making  repeated  calls  to  find  all  the matches in a single subject  
3260         string. However, you should be  sure  that  the  value  of  startoffset         If you already know that your subject is valid, and you  want  to  skip
3261         points  to  the  start of a UTF-8 character. When PCRE_NO_UTF8_CHECK is         these    checks    for   performance   reasons,   you   can   set   the
3262         set, the effect of passing an invalid UTF-8 string as a subject,  or  a         PCRE_NO_UTF8_CHECK option when calling pcre_exec(). You might  want  to
3263         value  of startoffset that does not point to the start of a UTF-8 char-         do  this  for the second and subsequent calls to pcre_exec() if you are
3264         acter, is undefined. Your program may crash.         making repeated calls to find all  the  matches  in  a  single  subject
3265           string.  However,  you  should  be  sure  that the value of startoffset
3266           PCRE_PARTIAL         points to the start of a character (or the end of  the  subject).  When
3267           PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid string as a
3268         This option turns on the  partial  matching  feature.  If  the  subject         subject or an invalid value of startoffset is undefined.  Your  program
3269         string  fails to match the pattern, but at some point during the match-         may crash.
3270         ing process the end of the subject was reached (that  is,  the  subject  
3271         partially  matches  the  pattern and the failure to match occurred only           PCRE_PARTIAL_HARD
3272         because there were not enough subject characters), pcre_exec()  returns           PCRE_PARTIAL_SOFT
3273         PCRE_ERROR_PARTIAL  instead of PCRE_ERROR_NOMATCH. When PCRE_PARTIAL is  
3274         used, there are restrictions on what may appear in the  pattern.  These         These  options turn on the partial matching feature. For backwards com-
3275         are discussed in the pcrepartial documentation.         patibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A  partial
3276           match  occurs if the end of the subject string is reached successfully,
3277           but there are not enough subject characters to complete the  match.  If
3278           this happens when PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set,
3279           matching continues by testing any remaining alternatives.  Only  if  no
3280           complete  match  can be found is PCRE_ERROR_PARTIAL returned instead of
3281           PCRE_ERROR_NOMATCH. In other words,  PCRE_PARTIAL_SOFT  says  that  the
3282           caller  is  prepared to handle a partial match, but only if no complete
3283           match can be found.
3284    
3285           If PCRE_PARTIAL_HARD is set, it overrides  PCRE_PARTIAL_SOFT.  In  this
3286           case,  if  a  partial  match  is found, pcre_exec() immediately returns
3287           PCRE_ERROR_PARTIAL, without  considering  any  other  alternatives.  In
3288           other  words, when PCRE_PARTIAL_HARD is set, a partial match is consid-
3289           ered to be more important that an alternative complete match.
3290    
3291           In both cases, the portion of the string that was  inspected  when  the
3292           partial match was found is set as the first matching string. There is a
3293           more detailed discussion of partial and  multi-segment  matching,  with
3294           examples, in the pcrepartial documentation.
3295    
3296     The string to be matched by pcre_exec()     The string to be matched by pcre_exec()
3297    
3298         The  subject string is passed to pcre_exec() as a pointer in subject, a         The  subject string is passed to pcre_exec() as a pointer in subject, a
3299         length in length, and a starting byte offset in startoffset.  In  UTF-8         length in bytes in length, and a starting byte offset  in  startoffset.
3300         mode,  the  byte  offset  must point to the start of a UTF-8 character.         If  this  is  negative  or  greater  than  the  length  of the subject,
3301         Unlike the pattern string, the subject may contain binary  zero  bytes.         pcre_exec() returns PCRE_ERROR_BADOFFSET. When the starting  offset  is
3302         When  the starting offset is zero, the search for a match starts at the         zero,  the  search  for a match starts at the beginning of the subject,
3303         beginning of the subject, and this is by far the most common case.         and this is by far the most common case. In UTF-8 mode, the byte offset
3304           must  point  to  the start of a UTF-8 character (or the end of the sub-
3305         A non-zero starting offset is useful when searching for  another  match         ject). Unlike the pattern string, the subject may contain  binary  zero
3306         in  the same subject by calling pcre_exec() again after a previous suc-         bytes.
3307         cess.  Setting startoffset differs from just passing over  a  shortened  
3308         string  and  setting  PCRE_NOTBOL  in the case of a pattern that begins         A  non-zero  starting offset is useful when searching for another match
3309           in the same subject by calling pcre_exec() again after a previous  suc-
3310           cess.   Setting  startoffset differs from just passing over a shortened
3311           string and setting PCRE_NOTBOL in the case of  a  pattern  that  begins
3312         with any kind of lookbehind. For example, consider the pattern         with any kind of lookbehind. For example, consider the pattern
3313    
3314           \Biss\B           \Biss\B
3315    
3316         which finds occurrences of "iss" in the middle of  words.  (\B  matches         which  finds  occurrences  of "iss" in the middle of words. (\B matches
3317         only  if  the  current position in the subject is not a word boundary.)         only if the current position in the subject is not  a  word  boundary.)
3318         When applied to the string "Mississipi" the first call  to  pcre_exec()         When  applied  to the string "Mississipi" the first call to pcre_exec()
3319         finds  the  first  occurrence. If pcre_exec() is called again with just         finds the first occurrence. If pcre_exec() is called  again  with  just
3320         the remainder of the subject,  namely  "issipi",  it  does  not  match,         the  remainder  of  the  subject,  namely  "issipi", it does not match,
3321         because \B is always false at the start of the subject, which is deemed         because \B is always false at the start of the subject, which is deemed
3322         to be a word boundary. However, if pcre_exec()  is  passed  the  entire         to  be  a  word  boundary. However, if pcre_exec() is passed the entire
3323         string again, but with startoffset set to 4, it finds the second occur-         string again, but with startoffset set to 4, it finds the second occur-
3324         rence of "iss" because it is able to look behind the starting point  to         rence  of "iss" because it is able to look behind the starting point to
3325         discover that it is preceded by a letter.         discover that it is preceded by a letter.
3326    
3327           Finding all the matches in a subject is tricky  when  the  pattern  can
3328           match an empty string. It is possible to emulate Perl's /g behaviour by
3329           first  trying  the  match  again  at  the   same   offset,   with   the
3330           PCRE_NOTEMPTY_ATSTART  and  PCRE_ANCHORED  options,  and  then  if that
3331           fails, advancing the starting  offset  and  trying  an  ordinary  match
3332           again. There is some code that demonstrates how to do this in the pcre-
3333           demo sample program. In the most general case, you have to check to see
3334           if  the newline convention recognizes CRLF as a newline, and if so, and
3335           the current character is CR followed by LF, advance the starting offset
3336           by two characters instead of one.
3337    
3338         If  a  non-zero starting offset is passed when the pattern is anchored,         If  a  non-zero starting offset is passed when the pattern is anchored,
3339         one attempt to match at the given offset is made. This can only succeed         one attempt to match at the given offset is made. This can only succeed
3340         if  the  pattern  does  not require the match to be at the start of the         if  the  pattern  does  not require the match to be at the start of the
# Line 2087  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3350  MATCHING A PATTERN: THE TRADITIONAL FUNC
3350         string.  PCRE  supports several other kinds of parenthesized subpattern         string.  PCRE  supports several other kinds of parenthesized subpattern
3351         that do not cause substrings to be captured.         that do not cause substrings to be captured.
3352    
3353         Captured substrings are returned to the caller via a vector of  integer         Captured substrings are returned to the caller via a vector of integers
3354         offsets  whose  address is passed in ovector. The number of elements in         whose  address is passed in ovector. The number of elements in the vec-
3355         the vector is passed in ovecsize, which must be a non-negative  number.         tor is passed in ovecsize, which must be a non-negative  number.  Note:
3356         Note: this argument is NOT the size of ovector in bytes.         this argument is NOT the size of ovector in bytes.
3357    
3358         The  first  two-thirds of the vector is used to pass back captured sub-         The  first  two-thirds of the vector is used to pass back captured sub-
3359         strings, each substring using a pair of integers. The  remaining  third         strings, each substring using a pair of integers. The  remaining  third
3360         of  the  vector is used as workspace by pcre_exec() while matching cap-         of  the  vector is used as workspace by pcre_exec() while matching cap-
3361         turing subpatterns, and is not available for passing back  information.         turing subpatterns, and is not available for passing back  information.
3362         The  length passed in ovecsize should always be a multiple of three. If         The  number passed in ovecsize should always be a multiple of three. If
3363         it is not, it is rounded down.         it is not, it is rounded down.
3364    
3365         When a match is successful, information about  captured  substrings  is         When a match is successful, information about  captured  substrings  is
3366         returned  in  pairs  of integers, starting at the beginning of ovector,         returned  in  pairs  of integers, starting at the beginning of ovector,
3367         and continuing up to two-thirds of its length at the  most.  The  first         and continuing up to two-thirds of its length at the  most.  The  first
3368         element of a pair is set to the offset of the first character in a sub-         element  of  each pair is set to the byte offset of the first character
3369         string, and the second is set to the  offset  of  the  first  character         in a substring, and the second is set to the byte offset of  the  first
3370         after  the  end  of  a  substring. The first pair, ovector[0] and ovec-         character  after  the end of a substring. Note: these values are always
3371         tor[1], identify the portion of  the  subject  string  matched  by  the         byte offsets, even in UTF-8 mode. They are not character counts.
3372         entire  pattern.  The next pair is used for the first capturing subpat-  
3373         tern, and so on. The value returned by pcre_exec() is one more than the         The first pair of integers, ovector[0]  and  ovector[1],  identify  the
3374         highest numbered pair that has been set. For example, if two substrings         portion  of  the subject string matched by the entire pattern. The next
3375         have been captured, the returned value is 3. If there are no  capturing         pair is used for the first capturing subpattern, and so on.  The  value
3376         subpatterns,  the return value from a successful match is 1, indicating         returned by pcre_exec() is one more than the highest numbered pair that
3377         that just the first pair of offsets has been set.         has been set.  For example, if two substrings have been  captured,  the
3378           returned  value is 3. If there are no capturing subpatterns, the return
3379           value from a successful match is 1, indicating that just the first pair
3380           of offsets has been set.
3381    
3382         If a capturing subpattern is matched repeatedly, it is the last portion         If a capturing subpattern is matched repeatedly, it is the last portion
3383         of the string that it matched that is returned.         of the string that it matched that is returned.
3384    
3385         If  the vector is too small to hold all the captured substring offsets,         If the vector is too small to hold all the captured substring  offsets,
3386         it is used as far as possible (up to two-thirds of its length), and the         it is used as far as possible (up to two-thirds of its length), and the
3387         function  returns a value of zero. In particular, if the substring off-         function returns a value of zero. If neither the actual string  matched
3388         sets are not of interest, pcre_exec() may be called with ovector passed         nor  any captured substrings are of interest, pcre_exec() may be called
3389         as  NULL  and  ovecsize  as zero. However, if the pattern contains back         with ovector passed as NULL and ovecsize as zero. However, if the  pat-
3390         references and the ovector is not big enough to  remember  the  related         tern  contains  back  references  and  the ovector is not big enough to
3391         substrings,  PCRE has to get additional memory for use during matching.         remember the related substrings, PCRE has to get additional memory  for
3392         Thus it is usually advisable to supply an ovector.         use  during matching. Thus it is usually advisable to supply an ovector
3393           of reasonable size.
3394         The pcre_info() function can be used to find  out  how  many  capturing  
3395         subpatterns  there  are  in  a  compiled pattern. The smallest size for         There are some cases where zero is returned  (indicating  vector  over-
3396         ovector that will allow for n captured substrings, in addition  to  the         flow)  when  in fact the vector is exactly the right size for the final
3397           match. For example, consider the pattern
3398    
3399             (a)(?:(b)c|bd)
3400    
3401           If a vector of 6 elements (allowing for only 1 captured  substring)  is
3402           given with subject string "abd", pcre_exec() will try to set the second
3403           captured string, thereby recording a vector overflow, before failing to
3404           match  "c"  and  backing  up  to  try  the second alternative. The zero
3405           return, however, does correctly indicate that  the  maximum  number  of
3406           slots (namely 2) have been filled. In similar cases where there is tem-
3407           porary overflow, but the final number of used slots  is  actually  less
3408           than the maximum, a non-zero value is returned.
3409    
3410           The pcre_fullinfo() function can be used to find out how many capturing
3411           subpatterns there are in a compiled  pattern.  The  smallest  size  for
3412           ovector  that  will allow for n captured substrings, in addition to the
3413         offsets of the substring matched by the whole pattern, is (n+1)*3.         offsets of the substring matched by the whole pattern, is (n+1)*3.
3414    
3415         It  is  possible for capturing subpattern number n+1 to match some part         It is possible for capturing subpattern number n+1 to match  some  part
3416         of the subject when subpattern n has not been used at all. For example,         of the subject when subpattern n has not been used at all. For example,
3417         if  the  string  "abc"  is  matched against the pattern (a|(z))(bc) the         if the string "abc" is matched  against  the  pattern  (a|(z))(bc)  the
3418         return from the function is 4, and subpatterns 1 and 3 are matched, but         return from the function is 4, and subpatterns 1 and 3 are matched, but
3419         2  is  not.  When  this happens, both values in the offset pairs corre-         2 is not. When this happens, both values in  the  offset  pairs  corre-
3420         sponding to unused subpatterns are set to -1.         sponding to unused subpatterns are set to -1.
3421    
3422         Offset values that correspond to unused subpatterns at the end  of  the         Offset  values  that correspond to unused subpatterns at the end of the
3423         expression  are  also  set  to  -1. For example, if the string "abc" is         expression are also set to -1. For example,  if  the  string  "abc"  is
3424         matched against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are  not         matched  against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not
3425         matched.  The  return  from the function is 2, because the highest used         matched. The return from the function is 2, because  the  highest  used
3426         capturing subpattern number is 1. However, you can refer to the offsets         capturing  subpattern  number  is 1, and the offsets for for the second
3427         for  the  second  and third capturing subpatterns if you wish (assuming         and third capturing subpatterns (assuming the vector is  large  enough,
3428         the vector is large enough, of course).         of course) are set to -1.
3429    
3430           Note:  Elements  in  the first two-thirds of ovector that do not corre-
3431           spond to capturing parentheses in the pattern are never  changed.  That
3432           is,  if  a pattern contains n capturing parentheses, no more than ovec-
3433           tor[0] to ovector[2n+1] are set by pcre_exec(). The other elements  (in
3434           the first two-thirds) retain whatever values they previously had.
3435    
3436         Some convenience functions are provided  for  extracting  the  captured         Some  convenience  functions  are  provided for extracting the captured
3437         substrings as separate strings. These are described below.         substrings as separate strings. These are described below.
3438    
3439     Error return values from pcre_exec()     Error return values from pcre_exec()
3440    
3441         If  pcre_exec()  fails, it returns a negative number. The following are         If pcre_exec() fails, it returns a negative number. The  following  are
3442         defined in the header file:         defined in the header file:
3443    
3444           PCRE_ERROR_NOMATCH        (-1)           PCRE_ERROR_NOMATCH        (-1)
# Line 2159  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3447  MATCHING A PATTERN: THE TRADITIONAL FUNC
3447    
3448           PCRE_ERROR_NULL           (-2)           PCRE_ERROR_NULL           (-2)
3449    
3450         Either code or subject was passed as NULL,  or  ovector  was  NULL  and         Either  code  or  subject  was  passed as NULL, or ovector was NULL and
3451         ovecsize was not zero.         ovecsize was not zero.
3452    
3453           PCRE_ERROR_BADOPTION      (-3)           PCRE_ERROR_BADOPTION      (-3)
# Line 2168  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3456  MATCHING A PATTERN: THE TRADITIONAL FUNC
3456    
3457           PCRE_ERROR_BADMAGIC       (-4)           PCRE_ERROR_BADMAGIC       (-4)
3458    
3459         PCRE  stores a 4-byte "magic number" at the start of the compiled code,         PCRE stores a 4-byte "magic number" at the start of the compiled  code,
3460         to catch the case when it is passed a junk pointer and to detect when a         to catch the case when it is passed a junk pointer and to detect when a
3461         pattern that was compiled in an environment of one endianness is run in         pattern that was compiled in an environment of one endianness is run in
3462         an environment with the other endianness. This is the error  that  PCRE         an  environment  with the other endianness. This is the error that PCRE
3463         gives when the magic number is not present.         gives when the magic number is not present.
3464    
3465           PCRE_ERROR_UNKNOWN_OPCODE (-5)           PCRE_ERROR_UNKNOWN_OPCODE (-5)
3466    
3467         While running the pattern match, an unknown item was encountered in the         While running the pattern match, an unknown item was encountered in the
3468         compiled pattern. This error could be caused by a bug  in  PCRE  or  by         compiled  pattern.  This  error  could be caused by a bug in PCRE or by
3469         overwriting of the compiled pattern.         overwriting of the compiled pattern.
3470    
3471           PCRE_ERROR_NOMEMORY       (-6)           PCRE_ERROR_NOMEMORY       (-6)
3472    
3473         If  a  pattern contains back references, but the ovector that is passed         If a pattern contains back references, but the ovector that  is  passed
3474         to pcre_exec() is not big enough to remember the referenced substrings,         to pcre_exec() is not big enough to remember the referenced substrings,
3475         PCRE  gets  a  block of memory at the start of matching to use for this         PCRE gets a block of memory at the start of matching to  use  for  this
3476         purpose. If the call via pcre_malloc() fails, this error is given.  The         purpose.  If the call via pcre_malloc() fails, this error is given. The
3477         memory is automatically freed at the end of matching.         memory is automatically freed at the end of matching.
3478    
3479           This error is also given if pcre_stack_malloc() fails  in  pcre_exec().
3480           This  can happen only when PCRE has been compiled with --disable-stack-
3481           for-recursion.
3482    
3483           PCRE_ERROR_NOSUBSTRING    (-7)           PCRE_ERROR_NOSUBSTRING    (-7)
3484    
3485         This  error is used by the pcre_copy_substring(), pcre_get_substring(),         This error is used by the pcre_copy_substring(),  pcre_get_substring(),
3486         and  pcre_get_substring_list()  functions  (see  below).  It  is  never         and  pcre_get_substring_list()  functions  (see  below).  It  is  never
3487         returned by pcre_exec().         returned by pcre_exec().
3488    
3489           PCRE_ERROR_MATCHLIMIT     (-8)           PCRE_ERROR_MATCHLIMIT     (-8)
3490    
3491         The  backtracking  limit,  as  specified  by the match_limit field in a         The backtracking limit, as specified by  the  match_limit  field  in  a
3492         pcre_extra structure (or defaulted) was reached.  See  the  description         pcre_extra  structure  (or  defaulted) was reached. See the description
3493         above.         above.
3494    
3495           PCRE_ERROR_CALLOUT        (-9)           PCRE_ERROR_CALLOUT        (-9)
3496    
3497         This error is never generated by pcre_exec() itself. It is provided for         This error is never generated by pcre_exec() itself. It is provided for
3498         use by callout functions that want to yield a distinctive  error  code.         use  by  callout functions that want to yield a distinctive error code.
3499         See the pcrecallout documentation for details.         See the pcrecallout documentation for details.
3500    
3501           PCRE_ERROR_BADUTF8        (-10)           PCRE_ERROR_BADUTF8        (-10)
3502    
3503         A  string  that contains an invalid UTF-8 byte sequence was passed as a         A string that contains an invalid UTF-8 byte sequence was passed  as  a
3504         subject.         subject,  and the PCRE_NO_UTF8_CHECK option was not set. If the size of
3505           the output vector (ovecsize) is at least 2,  the  byte  offset  to  the
3506           start  of  the  the invalid UTF-8 character is placed in the first ele-
3507           ment, and a reason code is placed in the  second  element.  The  reason
3508           codes are listed in the following section.  For backward compatibility,
3509           if PCRE_PARTIAL_HARD is set and the problem is a truncated UTF-8  char-
3510           acter   at   the   end   of   the   subject  (reason  codes  1  to  5),
3511           PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
3512    
3513           PCRE_ERROR_BADUTF8_OFFSET (-11)           PCRE_ERROR_BADUTF8_OFFSET (-11)
3514    
3515         The UTF-8 byte sequence that was passed as a subject was valid, but the         The UTF-8 byte sequence that was passed as a subject  was  checked  and
3516         value  of startoffset did not point to the beginning of a UTF-8 charac-         found  to be valid (the PCRE_NO_UTF8_CHECK option was not set), but the
3517         ter.         value of startoffset did not point to the beginning of a UTF-8  charac-