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revision 548 by ph10, Fri Jun 25 14:42:00 2010 UTC revision 1329 by ph10, Sun May 12 16:33:19 2013 UTC
# Line 8  pcretest commands. Line 8  pcretest commands.
8  -----------------------------------------------------------------------------  -----------------------------------------------------------------------------
9    
10    
11  PCRE(3)                                                                PCRE(3)  PCRE(3)                    Library Functions Manual                    PCRE(3)
12    
13    
14    
15  NAME  NAME
16         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
17    
   
18  INTRODUCTION  INTRODUCTION
19    
20         The  PCRE  library is a set of functions that implement regular expres-         The  PCRE  library is a set of functions that implement regular expres-
# Line 25  INTRODUCTION Line 25  INTRODUCTION
25         items, and there is an option for requesting some  minor  changes  that         items, and there is an option for requesting some  minor  changes  that
26         give better JavaScript compatibility.         give better JavaScript compatibility.
27    
28         The  current implementation of PCRE corresponds approximately with Perl         Starting with release 8.30, it is possible to compile two separate PCRE
29         5.10/5.11, including support for UTF-8 encoded strings and Unicode gen-         libraries:  the  original,  which  supports  8-bit  character   strings
30         eral  category properties. However, UTF-8 and Unicode support has to be         (including  UTF-8  strings),  and a second library that supports 16-bit
31         explicitly enabled; it is not the default. The  Unicode  tables  corre-         character strings (including UTF-16 strings). The build process  allows
32         spond to Unicode release 5.2.0.         either  one  or both to be built. The majority of the work to make this
33           possible was done by Zoltan Herczeg.
34    
35           Starting with release 8.32 it is possible to compile a  third  separate
36           PCRE library, which supports 32-bit character strings (including UTF-32
37           strings). The build process allows any set of the 8-,  16-  and  32-bit
38           libraries. The work to make this possible was done by Christian Persch.
39    
40           The  three  libraries  contain identical sets of functions, except that
41           the names in the 16-bit library start with pcre16_  instead  of  pcre_,
42           and  the  names  in  the  32-bit  library start with pcre32_ instead of
43           pcre_. To avoid over-complication and reduce the documentation  mainte-
44           nance load, most of the documentation describes the 8-bit library, with
45           the differences for the 16-bit and  32-bit  libraries  described  sepa-
46           rately  in  the  pcre16  and  pcre32  pages. References to functions or
47           structures of the  form  pcre[16|32]_xxx  should  be  read  as  meaning
48           "pcre_xxx  when  using  the  8-bit  library,  pcre16_xxx when using the
49           16-bit library, or pcre32_xxx when using the 32-bit library".
50    
51           The current implementation of PCRE corresponds approximately with  Perl
52           5.12,  including  support  for  UTF-8/16/32 encoded strings and Unicode
53           general category properties. However, UTF-8/16/32 and  Unicode  support
54           has to be explicitly enabled; it is not the default. The Unicode tables
55           correspond to Unicode release 6.2.0.
56    
57         In  addition to the Perl-compatible matching function, PCRE contains an         In addition to the Perl-compatible matching function, PCRE contains  an
58         alternative function that matches the same compiled patterns in a  dif-         alternative  function that matches the same compiled patterns in a dif-
59         ferent way. In certain circumstances, the alternative function has some         ferent way. In certain circumstances, the alternative function has some
60         advantages.  For a discussion of the two matching algorithms,  see  the         advantages.   For  a discussion of the two matching algorithms, see the
61         pcrematching page.         pcrematching page.
62    
63         PCRE  is  written  in C and released as a C library. A number of people         PCRE is written in C and released as a C library. A  number  of  people
64         have written wrappers and interfaces of various kinds.  In  particular,         have  written  wrappers and interfaces of various kinds. In particular,
65         Google  Inc.   have  provided  a comprehensive C++ wrapper. 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 56  INTRODUCTION Line 80  INTRODUCTION
80         client  to  discover  which  features are available. The features them-         client  to  discover  which  features are available. The features them-
81         selves are described in the pcrebuild page. Documentation about  build-         selves are described in the pcrebuild page. Documentation about  build-
82         ing  PCRE  for various operating systems can be found in the README and         ing  PCRE  for various operating systems can be found in the README and
83         NON-UNIX-USE files in the source distribution.         NON-AUTOTOOLS_BUILD files in the source distribution.
84    
85         The library contains a number of undocumented  internal  functions  and         The libraries contains a number of undocumented internal functions  and
86         data  tables  that  are  used by more than one of the exported external         data  tables  that  are  used by more than one of the exported external
87         functions, but which are not intended  for  use  by  external  callers.         functions, but which are not intended  for  use  by  external  callers.
88         Their  names  all begin with "_pcre_", which hopefully will not provoke         Their  names all begin with "_pcre_" or "_pcre16_" or "_pcre32_", which
89         any name clashes. In some environments, it is possible to control which         hopefully will not provoke any name clashes. In some  environments,  it
90         external  symbols  are  exported when a shared library is built, and in         is  possible  to  control  which  external  symbols are exported when a
91         these cases the undocumented symbols are not exported.         shared library is built, and in these cases  the  undocumented  symbols
92           are not exported.
93    
94    
95    SECURITY CONSIDERATIONS
96    
97           If  you  are  using PCRE in a non-UTF application that permits users to
98           supply arbitrary patterns for compilation, you should  be  aware  of  a
99           feature that allows users to turn on UTF support from within a pattern,
100           provided that PCRE was built with UTF support. For  example,  an  8-bit
101           pattern  that  begins  with  "(*UTF8)" or "(*UTF)" turns on UTF-8 mode,
102           which interprets patterns and subjects as strings of  UTF-8  characters
103           instead  of  individual 8-bit characters.  This causes both the pattern
104           and any data against which it is matched to be checked for UTF-8 valid-
105           ity.  If  the  data  string is very long, such a check might use suffi-
106           ciently many resources as to cause your  application  to  lose  perfor-
107           mance.
108    
109           One   way   of   guarding  against  this  possibility  is  to  use  the
110           pcre_fullinfo() function to check the compiled  pattern's  options  for
111           UTF.   Alternatively, from release 8.33, you can set the PCRE_NEVER_UTF
112           option at compile time. This causes an compile time error if a  pattern
113           contains a UTF-setting sequence.
114    
115           If  your  application  is one that supports UTF, be aware that validity
116           checking can take time. If the same data string is to be  matched  many
117           times, you can use the PCRE_NO_UTF[8|16|32]_CHECK option for the second
118           and subsequent matches to save redundant checks.
119    
120           Another way that performance can be hit is by running  a  pattern  that
121           has  a  very  large search tree against a string that will never match.
122           Nested unlimited repeats in a pattern are a common example.  PCRE  pro-
123           vides some protection against this: see the PCRE_EXTRA_MATCH_LIMIT fea-
124           ture in the pcreapi page.
125    
126    
127  USER DOCUMENTATION  USER DOCUMENTATION
# Line 77  USER DOCUMENTATION Line 134  USER DOCUMENTATION
134         lows:         lows:
135    
136           pcre              this document           pcre              this document
137             pcre16            details of the 16-bit library
138             pcre32            details of the 32-bit library
139           pcre-config       show PCRE installation configuration information           pcre-config       show PCRE installation configuration information
140           pcreapi           details of PCRE's native C API           pcreapi           details of PCRE's native C API
141           pcrebuild         options for building PCRE           pcrebuild         options for building PCRE
142           pcrecallout       details of the callout feature           pcrecallout       details of the callout feature
143           pcrecompat        discussion of Perl compatibility           pcrecompat        discussion of Perl compatibility
144           pcrecpp           details of the C++ wrapper           pcrecpp           details of the C++ wrapper for the 8-bit library
145           pcredemo          a demonstration C program that uses PCRE           pcredemo          a demonstration C program that uses PCRE
146           pcregrep          description of the pcregrep command           pcregrep          description of the pcregrep command (8-bit only)
147             pcrejit           discussion of the just-in-time optimization support
148             pcrelimits        details of size and other limits
149           pcrematching      discussion of the two matching algorithms           pcrematching      discussion of the two matching algorithms
150           pcrepartial       details of the partial matching facility           pcrepartial       details of the partial matching facility
151           pcrepattern       syntax and semantics of supported           pcrepattern       syntax and semantics of supported
152                               regular expressions                               regular expressions
153           pcreperform       discussion of performance issues           pcreperform       discussion of performance issues
154           pcreposix         the POSIX-compatible C API           pcreposix         the POSIX-compatible C API for the 8-bit library
155           pcreprecompile    details of saving and re-using precompiled patterns           pcreprecompile    details of saving and re-using precompiled patterns
156           pcresample        discussion of the pcredemo program           pcresample        discussion of the pcredemo program
157           pcrestack         discussion of stack usage           pcrestack         discussion of stack usage
158           pcresyntax        quick syntax reference           pcresyntax        quick syntax reference
159           pcretest          description of the pcretest testing command           pcretest          description of the pcretest testing command
160             pcreunicode       discussion of Unicode and UTF-8/16/32 support
161    
162         In  addition,  in the "man" and HTML formats, there is a short page for         In  addition,  in the "man" and HTML formats, there is a short page for
163         each C library function, listing its arguments and results.         each C library function, listing its arguments and results.
164    
165    
166  LIMITATIONS  AUTHOR
167    
168         There are some size limitations in PCRE but it is hoped that they  will         Philip Hazel
169         never in practice be relevant.         University Computing Service
170           Cambridge CB2 3QH, England.
171    
172         The  maximum  length of a compiled pattern is 65539 (sic) bytes if PCRE         Putting an actual email address here seems to have been a spam  magnet,
173         is compiled with the default internal linkage size of 2. If you want to         so  I've  taken  it away. If you want to email me, use my two initials,
174         process  regular  expressions  that are truly enormous, you can compile         followed by the two digits 10, at the domain cam.ac.uk.
        PCRE with an internal linkage size of 3 or 4 (see the  README  file  in  
        the  source  distribution and the pcrebuild documentation for details).  
        In these cases the limit is substantially larger.  However,  the  speed  
        of execution is slower.  
175    
        All values in repeating quantifiers must be less than 65536.  
176    
177         There is no limit to the number of parenthesized subpatterns, but there  REVISION
        can be no more than 65535 capturing subpatterns.  
178    
179         The maximum length of name for a named subpattern is 32 characters, and         Last updated: 26 April 2013
180         the maximum number of named subpatterns is 10000.         Copyright (c) 1997-2013 University of Cambridge.
181    ------------------------------------------------------------------------------
182    
183    
184    PCRE(3)                    Library Functions Manual                    PCRE(3)
185    
        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.  
186    
187    
188  UTF-8 AND UNICODE PROPERTY SUPPORT  NAME
189           PCRE - Perl-compatible regular expressions
190    
191         From release 3.3, PCRE has  had  some  support  for  character  strings         #include <pcre.h>
        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,  or the pattern must start with the  
        sequence (*UTF8). When either of these is the case,  both  the  pattern  
        and  any  subject  strings  that  are matched against it are treated as  
        UTF-8 strings instead of strings of 1-byte characters.  
192    
        If you compile PCRE with UTF-8 support, but do not use it at run  time,  
        the  library will be a bit bigger, but the additional run time overhead  
        is limited to testing the PCRE_UTF8 flag occasionally, so should not be  
        very big.  
193    
194         If PCRE is built with Unicode character property support (which implies  PCRE 16-BIT API BASIC FUNCTIONS
        UTF-8 support), the escape sequences \p{..}, \P{..}, and  \X  are  sup-  
        ported.  The available properties that can be tested are limited to the  
        general category properties such as Lu for an upper case letter  or  Nd  
        for  a  decimal number, 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.  
195    
196     Validity of UTF-8 strings         pcre16 *pcre16_compile(PCRE_SPTR16 pattern, int options,
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 *pcre16_compile2(PCRE_SPTR16 pattern, int options,
201         subjects are (by default) checked for validity on entry to the relevant              int *errorcodeptr,
202         functions.  From  release 7.3 of PCRE, the check is according the rules              const char **errptr, int *erroffset,
203         of RFC 3629, which are themselves derived from the  Unicode  specifica-              const unsigned char *tableptr);
        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.  
   
        If  you  pass  an  invalid UTF-8 string when PCRE_NO_UTF8_CHECK is set,  
        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.  
   
        If you want to process strings  of  values  in  the  full  range  0  to  
        0x7FFFFFFF,  encoded in a UTF-8-like manner as per the old RFC, you can  
        set PCRE_NO_UTF8_CHECK to bypass the more restrictive test. However, in  
        this situation, you will have to apply your own validity check.  
   
    General comments about UTF-8 mode  
   
        1.  An  unbraced  hexadecimal  escape sequence (such as \xb3) matches a  
        two-byte UTF-8 character if the value is greater than 127.  
   
        2. Octal numbers up to \777 are recognized, and  match  two-byte  UTF-8  
        characters for values greater than \177.  
   
        3.  Repeat quantifiers apply to complete UTF-8 characters, not to indi-  
        vidual bytes, for example: \x{100}{3}.  
   
        4. The dot metacharacter matches one UTF-8 character instead of a  sin-  
        gle byte.  
   
        5.  The  escape sequence \C can be used to match a single byte in UTF-8  
        mode, but its use can lead to some strange effects.  This  facility  is  
        not available in the alternative matching function, pcre_dfa_exec().  
204    
205         6.  The  character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly         pcre16_extra *pcre16_study(const pcre16 *code, int options,
206         test characters of any code value, but, by default, the characters that              const char **errptr);
        PCRE  recognizes  as digits, spaces, or word characters remain the same  
        set as before, all with values less than 256. This  remains  true  even  
        when  PCRE  is built to include Unicode property support, because to do  
        otherwise would slow down PCRE in many common  cases.  Note  that  this  
        also applies to \b, because it is defined in terms of \w and \W. If you  
        really want to test for a wider sense of, say,  "digit",  you  can  use  
        explicit  Unicode property tests such as \p{Nd}.  Alternatively, if you  
        set the PCRE_UCP option, the way that the  character  escapes  work  is  
        changed  so that Unicode properties are used to determine which charac-  
        ters match. There are more details in the section on generic  character  
        types in the pcrepattern documentation.  
207    
208         7.  Similarly,  characters that match the POSIX named character classes         void pcre16_free_study(pcre16_extra *extra);
209         are all low-valued characters, unless the PCRE_UCP option is set.  
210           int pcre16_exec(const pcre16 *code, const pcre16_extra *extra,
211                PCRE_SPTR16 subject, int length, int startoffset,
212                int options, int *ovector, int ovecsize);
213    
214         8. However, the Perl 5.10 horizontal and vertical  whitespace  matching         int pcre16_dfa_exec(const pcre16 *code, const pcre16_extra *extra,
215         escapes (\h, \H, \v, and \V) do match all the appropriate Unicode char-              PCRE_SPTR16 subject, int length, int startoffset,
216         acters, whether or not PCRE_UCP is set.              int options, int *ovector, int ovecsize,
217                int *workspace, int wscount);
218    
219         9. Case-insensitive matching applies only to  characters  whose  values  
220         are  less than 128, unless PCRE is built with Unicode property support.  PCRE 16-BIT API STRING EXTRACTION FUNCTIONS
221         Even when Unicode property support is available, PCRE  still  uses  its  
222         own  character  tables when checking the case of low-valued characters,         int pcre16_copy_named_substring(const pcre16 *code,
223         so as not to degrade performance.  The Unicode property information  is              PCRE_SPTR16 subject, int *ovector,
224         used only for characters with higher values. Even when Unicode property              int stringcount, PCRE_SPTR16 stringname,
225         support is available, PCRE supports case-insensitive matching only when              PCRE_UCHAR16 *buffer, int buffersize);
226         there  is  a  one-to-one  mapping between a letter's cases. There are a  
227         small number of many-to-one mappings in Unicode;  these  are  not  sup-         int pcre16_copy_substring(PCRE_SPTR16 subject, int *ovector,
228         ported by PCRE.              int stringcount, int stringnumber, PCRE_UCHAR16 *buffer,
229                int buffersize);
230    
231           int pcre16_get_named_substring(const pcre16 *code,
232                PCRE_SPTR16 subject, int *ovector,
233                int stringcount, PCRE_SPTR16 stringname,
234                PCRE_SPTR16 *stringptr);
235    
236           int pcre16_get_stringnumber(const pcre16 *code,
237                PCRE_SPTR16 name);
238    
239           int pcre16_get_stringtable_entries(const pcre16 *code,
240                PCRE_SPTR16 name, PCRE_UCHAR16 **first, PCRE_UCHAR16 **last);
241    
242           int pcre16_get_substring(PCRE_SPTR16 subject, int *ovector,
243                int stringcount, int stringnumber,
244                PCRE_SPTR16 *stringptr);
245    
246           int pcre16_get_substring_list(PCRE_SPTR16 subject,
247                int *ovector, int stringcount, PCRE_SPTR16 **listptr);
248    
249           void pcre16_free_substring(PCRE_SPTR16 stringptr);
250    
251           void pcre16_free_substring_list(PCRE_SPTR16 *stringptr);
252    
253    
254    PCRE 16-BIT API AUXILIARY FUNCTIONS
255    
256           pcre16_jit_stack *pcre16_jit_stack_alloc(int startsize, int maxsize);
257    
258           void pcre16_jit_stack_free(pcre16_jit_stack *stack);
259    
260           void pcre16_assign_jit_stack(pcre16_extra *extra,
261                pcre16_jit_callback callback, void *data);
262    
263           const unsigned char *pcre16_maketables(void);
264    
265           int pcre16_fullinfo(const pcre16 *code, const pcre16_extra *extra,
266                int what, void *where);
267    
268           int pcre16_refcount(pcre16 *code, int adjust);
269    
270           int pcre16_config(int what, void *where);
271    
272           const char *pcre16_version(void);
273    
274           int pcre16_pattern_to_host_byte_order(pcre16 *code,
275                pcre16_extra *extra, const unsigned char *tables);
276    
277    
278    PCRE 16-BIT API INDIRECTED FUNCTIONS
279    
280           void *(*pcre16_malloc)(size_t);
281    
282           void (*pcre16_free)(void *);
283    
284           void *(*pcre16_stack_malloc)(size_t);
285    
286           void (*pcre16_stack_free)(void *);
287    
288           int (*pcre16_callout)(pcre16_callout_block *);
289    
290    
291    PCRE 16-BIT API 16-BIT-ONLY FUNCTION
292    
293           int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *output,
294                PCRE_SPTR16 input, int length, int *byte_order,
295                int keep_boms);
296    
297    
298    THE PCRE 16-BIT LIBRARY
299    
300           Starting  with  release  8.30, it is possible to compile a PCRE library
301           that supports 16-bit character strings, including  UTF-16  strings,  as
302           well  as  or instead of the original 8-bit library. The majority of the
303           work to make  this  possible  was  done  by  Zoltan  Herczeg.  The  two
304           libraries contain identical sets of functions, used in exactly the same
305           way. Only the names of the functions and the data types of their  argu-
306           ments  and results are different. To avoid over-complication and reduce
307           the documentation maintenance load,  most  of  the  PCRE  documentation
308           describes  the  8-bit  library,  with only occasional references to the
309           16-bit library. This page describes what is different when you use  the
310           16-bit library.
311    
312           WARNING:  A  single  application can be linked with both libraries, but
313           you must take care when processing any particular pattern to use  func-
314           tions  from  just one library. For example, if you want to study a pat-
315           tern that was compiled with  pcre16_compile(),  you  must  do  so  with
316           pcre16_study(), not pcre_study(), and you must free the study data with
317           pcre16_free_study().
318    
319    
320    THE HEADER FILE
321    
322           There is only one header file, pcre.h. It contains prototypes  for  all
323           the functions in all libraries, as well as definitions of flags, struc-
324           tures, error codes, etc.
325    
326    
327    THE LIBRARY NAME
328    
329           In Unix-like systems, the 16-bit library is called libpcre16,  and  can
330           normally  be  accesss  by adding -lpcre16 to the command for linking an
331           application that uses PCRE.
332    
333    
334    STRING TYPES
335    
336           In the 8-bit library, strings are passed to PCRE library  functions  as
337           vectors  of  bytes  with  the  C  type "char *". In the 16-bit library,
338           strings are passed as vectors of unsigned 16-bit quantities. The  macro
339           PCRE_UCHAR16  specifies  an  appropriate  data type, and PCRE_SPTR16 is
340           defined as "const PCRE_UCHAR16 *". In very  many  environments,  "short
341           int" is a 16-bit data type. When PCRE is built, it defines PCRE_UCHAR16
342           as "unsigned short int", but checks that it really  is  a  16-bit  data
343           type.  If  it is not, the build fails with an error message telling the
344           maintainer to modify the definition appropriately.
345    
346    
347    STRUCTURE TYPES
348    
349           The types of the opaque structures that are used  for  compiled  16-bit
350           patterns  and  JIT stacks are pcre16 and pcre16_jit_stack respectively.
351           The  type  of  the  user-accessible  structure  that  is  returned   by
352           pcre16_study()  is  pcre16_extra, and the type of the structure that is
353           used for passing data to a callout  function  is  pcre16_callout_block.
354           These structures contain the same fields, with the same names, as their
355           8-bit counterparts. The only difference is that pointers  to  character
356           strings are 16-bit instead of 8-bit types.
357    
358    
359    16-BIT FUNCTIONS
360    
361           For  every function in the 8-bit library there is a corresponding func-
362           tion in the 16-bit library with a name that starts with pcre16_ instead
363           of  pcre_.  The  prototypes are listed above. In addition, there is one
364           extra function, pcre16_utf16_to_host_byte_order(). This  is  a  utility
365           function  that converts a UTF-16 character string to host byte order if
366           necessary. The other 16-bit  functions  expect  the  strings  they  are
367           passed to be in host byte order.
368    
369           The input and output arguments of pcre16_utf16_to_host_byte_order() may
370           point to the same address, that is, conversion in place  is  supported.
371           The output buffer must be at least as long as the input.
372    
373           The  length  argument  specifies the number of 16-bit data units in the
374           input string; a negative value specifies a zero-terminated string.
375    
376           If byte_order is NULL, it is assumed that the string starts off in host
377           byte  order. This may be changed by byte-order marks (BOMs) anywhere in
378           the string (commonly as the first character).
379    
380           If byte_order is not NULL, a non-zero value of the integer to which  it
381           points  means  that  the input starts off in host byte order, otherwise
382           the opposite order is assumed. Again, BOMs in  the  string  can  change
383           this. The final byte order is passed back at the end of processing.
384    
385           If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
386           copied into the output string. Otherwise they are discarded.
387    
388           The result of the function is the number of 16-bit  units  placed  into
389           the  output  buffer,  including  the  zero terminator if the string was
390           zero-terminated.
391    
392    
393    SUBJECT STRING OFFSETS
394    
395           The lengths and starting offsets of subject strings must  be  specified
396           in  16-bit  data units, and the offsets within subject strings that are
397           returned by the matching functions are in also 16-bit units rather than
398           bytes.
399    
400    
401    NAMED SUBPATTERNS
402    
403           The  name-to-number translation table that is maintained for named sub-
404           patterns uses 16-bit characters.  The  pcre16_get_stringtable_entries()
405           function returns the length of each entry in the table as the number of
406           16-bit data units.
407    
408    
409    OPTION NAMES
410    
411           There   are   two   new   general   option   names,   PCRE_UTF16    and
412           PCRE_NO_UTF16_CHECK,     which     correspond    to    PCRE_UTF8    and
413           PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
414           define  the  same bits in the options word. There is a discussion about
415           the validity of UTF-16 strings in the pcreunicode page.
416    
417           For the pcre16_config() function there is an  option  PCRE_CONFIG_UTF16
418           that  returns  1  if UTF-16 support is configured, otherwise 0. If this
419           option  is  given  to  pcre_config()  or  pcre32_config(),  or  if  the
420           PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF32  option is given to pcre16_con-
421           fig(), the result is the PCRE_ERROR_BADOPTION error.
422    
423    
424    CHARACTER CODES
425    
426           In 16-bit mode, when  PCRE_UTF16  is  not  set,  character  values  are
427           treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
428           that they can range from 0 to 0xffff instead of 0  to  0xff.  Character
429           types  for characters less than 0xff can therefore be influenced by the
430           locale in the same way as before.  Characters greater  than  0xff  have
431           only one case, and no "type" (such as letter or digit).
432    
433           In  UTF-16  mode,  the  character  code  is  Unicode, in the range 0 to
434           0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
435           because  those  are "surrogate" values that are used in pairs to encode
436           values greater than 0xffff.
437    
438           A UTF-16 string can indicate its endianness by special code knows as  a
439           byte-order mark (BOM). The PCRE functions do not handle this, expecting
440           strings  to  be  in  host  byte  order.  A  utility   function   called
441           pcre16_utf16_to_host_byte_order()  is  provided  to help with this (see
442           above).
443    
444    
445    ERROR NAMES
446    
447           The errors PCRE_ERROR_BADUTF16_OFFSET and PCRE_ERROR_SHORTUTF16  corre-
448           spond  to  their  8-bit  counterparts.  The error PCRE_ERROR_BADMODE is
449           given when a compiled pattern is passed to a  function  that  processes
450           patterns  in  the  other  mode, for example, if a pattern compiled with
451           pcre_compile() is passed to pcre16_exec().
452    
453           There are new error codes whose names  begin  with  PCRE_UTF16_ERR  for
454           invalid  UTF-16  strings,  corresponding to the PCRE_UTF8_ERR codes for
455           UTF-8 strings that are described in the section entitled "Reason  codes
456           for  invalid UTF-8 strings" in the main pcreapi page. The UTF-16 errors
457           are:
458    
459             PCRE_UTF16_ERR1  Missing low surrogate at end of string
460             PCRE_UTF16_ERR2  Invalid low surrogate follows high surrogate
461             PCRE_UTF16_ERR3  Isolated low surrogate
462             PCRE_UTF16_ERR4  Non-character
463    
464    
465    ERROR TEXTS
466    
467           If there is an error while compiling a pattern, the error text that  is
468           passed  back by pcre16_compile() or pcre16_compile2() is still an 8-bit
469           character string, zero-terminated.
470    
471    
472    CALLOUTS
473    
474           The subject and mark fields in the callout block that is  passed  to  a
475           callout function point to 16-bit vectors.
476    
477    
478    TESTING
479    
480           The  pcretest  program continues to operate with 8-bit input and output
481           files, but it can be used for testing the 16-bit library. If it is  run
482           with the command line option -16, patterns and subject strings are con-
483           verted from 8-bit to 16-bit before being passed to PCRE, and the 16-bit
484           library  functions  are used instead of the 8-bit ones. Returned 16-bit
485           strings are converted to 8-bit for output. If both the  8-bit  and  the
486           32-bit libraries were not compiled, pcretest defaults to 16-bit and the
487           -16 option is ignored.
488    
489           When PCRE is being built, the RunTest script that is  called  by  "make
490           check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
491           16-bit and 32-bit libraries has been built, and runs the  tests  appro-
492           priately.
493    
494    
495    NOT SUPPORTED IN 16-BIT MODE
496    
497           Not all the features of the 8-bit library are available with the 16-bit
498           library. The C++ and POSIX wrapper functions  support  only  the  8-bit
499           library, and the pcregrep program is at present 8-bit only.
500    
501    
502  AUTHOR  AUTHOR
# Line 260  AUTHOR Line 505  AUTHOR
505         University Computing Service         University Computing Service
506         Cambridge CB2 3QH, England.         Cambridge CB2 3QH, England.
507    
        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.  
   
508    
509  REVISION  REVISION
510    
511         Last updated: 12 May 2010         Last updated: 12 May 2013
512         Copyright (c) 1997-2010 University of Cambridge.         Copyright (c) 1997-2013 University of Cambridge.
513  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
514    
515    
516    PCRE(3)                    Library Functions Manual                    PCRE(3)
517    
518    
 PCREBUILD(3)                                                      PCREBUILD(3)  
   
519    
520  NAME  NAME
521         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
522    
523           #include <pcre.h>
524    
525    
526    PCRE 32-BIT API BASIC FUNCTIONS
527    
528           pcre32 *pcre32_compile(PCRE_SPTR32 pattern, int options,
529                const char **errptr, int *erroffset,
530                const unsigned char *tableptr);
531    
532           pcre32 *pcre32_compile2(PCRE_SPTR32 pattern, int options,
533                int *errorcodeptr,
534                const char **errptr, int *erroffset,
535                const unsigned char *tableptr);
536    
537           pcre32_extra *pcre32_study(const pcre32 *code, int options,
538                const char **errptr);
539    
540           void pcre32_free_study(pcre32_extra *extra);
541    
542           int pcre32_exec(const pcre32 *code, const pcre32_extra *extra,
543                PCRE_SPTR32 subject, int length, int startoffset,
544                int options, int *ovector, int ovecsize);
545    
546           int pcre32_dfa_exec(const pcre32 *code, const pcre32_extra *extra,
547                PCRE_SPTR32 subject, int length, int startoffset,
548                int options, int *ovector, int ovecsize,
549                int *workspace, int wscount);
550    
551    
552    PCRE 32-BIT API STRING EXTRACTION FUNCTIONS
553    
554           int pcre32_copy_named_substring(const pcre32 *code,
555                PCRE_SPTR32 subject, int *ovector,
556                int stringcount, PCRE_SPTR32 stringname,
557                PCRE_UCHAR32 *buffer, int buffersize);
558    
559           int pcre32_copy_substring(PCRE_SPTR32 subject, int *ovector,
560                int stringcount, int stringnumber, PCRE_UCHAR32 *buffer,
561                int buffersize);
562    
563           int pcre32_get_named_substring(const pcre32 *code,
564                PCRE_SPTR32 subject, int *ovector,
565                int stringcount, PCRE_SPTR32 stringname,
566                PCRE_SPTR32 *stringptr);
567    
568           int pcre32_get_stringnumber(const pcre32 *code,
569                PCRE_SPTR32 name);
570    
571           int pcre32_get_stringtable_entries(const pcre32 *code,
572                PCRE_SPTR32 name, PCRE_UCHAR32 **first, PCRE_UCHAR32 **last);
573    
574           int pcre32_get_substring(PCRE_SPTR32 subject, int *ovector,
575                int stringcount, int stringnumber,
576                PCRE_SPTR32 *stringptr);
577    
578           int pcre32_get_substring_list(PCRE_SPTR32 subject,
579                int *ovector, int stringcount, PCRE_SPTR32 **listptr);
580    
581           void pcre32_free_substring(PCRE_SPTR32 stringptr);
582    
583           void pcre32_free_substring_list(PCRE_SPTR32 *stringptr);
584    
585    
586    PCRE 32-BIT API AUXILIARY FUNCTIONS
587    
588           pcre32_jit_stack *pcre32_jit_stack_alloc(int startsize, int maxsize);
589    
590           void pcre32_jit_stack_free(pcre32_jit_stack *stack);
591    
592           void pcre32_assign_jit_stack(pcre32_extra *extra,
593                pcre32_jit_callback callback, void *data);
594    
595           const unsigned char *pcre32_maketables(void);
596    
597           int pcre32_fullinfo(const pcre32 *code, const pcre32_extra *extra,
598                int what, void *where);
599    
600           int pcre32_refcount(pcre32 *code, int adjust);
601    
602           int pcre32_config(int what, void *where);
603    
604           const char *pcre32_version(void);
605    
606           int pcre32_pattern_to_host_byte_order(pcre32 *code,
607                pcre32_extra *extra, const unsigned char *tables);
608    
609    
610    PCRE 32-BIT API INDIRECTED FUNCTIONS
611    
612           void *(*pcre32_malloc)(size_t);
613    
614           void (*pcre32_free)(void *);
615    
616           void *(*pcre32_stack_malloc)(size_t);
617    
618           void (*pcre32_stack_free)(void *);
619    
620           int (*pcre32_callout)(pcre32_callout_block *);
621    
622    
623    PCRE 32-BIT API 32-BIT-ONLY FUNCTION
624    
625           int pcre32_utf32_to_host_byte_order(PCRE_UCHAR32 *output,
626                PCRE_SPTR32 input, int length, int *byte_order,
627                int keep_boms);
628    
629    
630    THE PCRE 32-BIT LIBRARY
631    
632           Starting  with  release  8.32, it is possible to compile a PCRE library
633           that supports 32-bit character strings, including  UTF-32  strings,  as
634           well as or instead of the original 8-bit library. This work was done by
635           Christian Persch, based on the work done  by  Zoltan  Herczeg  for  the
636           16-bit  library.  All  three  libraries contain identical sets of func-
637           tions, used in exactly the same way.  Only the names of  the  functions
638           and  the  data  types  of their arguments and results are different. To
639           avoid over-complication and reduce the documentation maintenance  load,
640           most  of  the PCRE documentation describes the 8-bit library, with only
641           occasional references to the 16-bit and  32-bit  libraries.  This  page
642           describes what is different when you use the 32-bit library.
643    
644           WARNING:  A  single  application  can  be linked with all or any of the
645           three libraries, but you must take care when processing any  particular
646           pattern  to  use  functions  from just one library. For example, if you
647           want to study a pattern that was compiled  with  pcre32_compile(),  you
648           must do so with pcre32_study(), not pcre_study(), and you must free the
649           study data with pcre32_free_study().
650    
651    
652    THE HEADER FILE
653    
654           There is only one header file, pcre.h. It contains prototypes  for  all
655           the functions in all libraries, as well as definitions of flags, struc-
656           tures, error codes, etc.
657    
658    
659    THE LIBRARY NAME
660    
661           In Unix-like systems, the 32-bit library is called libpcre32,  and  can
662           normally  be  accesss  by adding -lpcre32 to the command for linking an
663           application that uses PCRE.
664    
665    
666    STRING TYPES
667    
668           In the 8-bit library, strings are passed to PCRE library  functions  as
669           vectors  of  bytes  with  the  C  type "char *". In the 32-bit library,
670           strings are passed as vectors of unsigned 32-bit quantities. The  macro
671           PCRE_UCHAR32  specifies  an  appropriate  data type, and PCRE_SPTR32 is
672           defined as "const PCRE_UCHAR32 *". In very many environments, "unsigned
673           int" is a 32-bit data type. When PCRE is built, it defines PCRE_UCHAR32
674           as "unsigned int", but checks that it really is a 32-bit data type.  If
675           it is not, the build fails with an error message telling the maintainer
676           to modify the definition appropriately.
677    
678    
679    STRUCTURE TYPES
680    
681           The types of the opaque structures that are used  for  compiled  32-bit
682           patterns  and  JIT stacks are pcre32 and pcre32_jit_stack respectively.
683           The  type  of  the  user-accessible  structure  that  is  returned   by
684           pcre32_study()  is  pcre32_extra, and the type of the structure that is
685           used for passing data to a callout  function  is  pcre32_callout_block.
686           These structures contain the same fields, with the same names, as their
687           8-bit counterparts. The only difference is that pointers  to  character
688           strings are 32-bit instead of 8-bit types.
689    
690    
691    32-BIT FUNCTIONS
692    
693           For  every function in the 8-bit library there is a corresponding func-
694           tion in the 32-bit library with a name that starts with pcre32_ instead
695           of  pcre_.  The  prototypes are listed above. In addition, there is one
696           extra function, pcre32_utf32_to_host_byte_order(). This  is  a  utility
697           function  that converts a UTF-32 character string to host byte order if
698           necessary. The other 32-bit  functions  expect  the  strings  they  are
699           passed to be in host byte order.
700    
701           The input and output arguments of pcre32_utf32_to_host_byte_order() may
702           point to the same address, that is, conversion in place  is  supported.
703           The output buffer must be at least as long as the input.
704    
705           The  length  argument  specifies the number of 32-bit data units in the
706           input string; a negative value specifies a zero-terminated string.
707    
708           If byte_order is NULL, it is assumed that the string starts off in host
709           byte  order. This may be changed by byte-order marks (BOMs) anywhere in
710           the string (commonly as the first character).
711    
712           If byte_order is not NULL, a non-zero value of the integer to which  it
713           points  means  that  the input starts off in host byte order, otherwise
714           the opposite order is assumed. Again, BOMs in  the  string  can  change
715           this. The final byte order is passed back at the end of processing.
716    
717           If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
718           copied into the output string. Otherwise they are discarded.
719    
720           The result of the function is the number of 32-bit  units  placed  into
721           the  output  buffer,  including  the  zero terminator if the string was
722           zero-terminated.
723    
724    
725    SUBJECT STRING OFFSETS
726    
727           The lengths and starting offsets of subject strings must  be  specified
728           in  32-bit  data units, and the offsets within subject strings that are
729           returned by the matching functions are in also 32-bit units rather than
730           bytes.
731    
732    
733    NAMED SUBPATTERNS
734    
735           The  name-to-number translation table that is maintained for named sub-
736           patterns uses 32-bit characters.  The  pcre32_get_stringtable_entries()
737           function returns the length of each entry in the table as the number of
738           32-bit data units.
739    
740    
741    OPTION NAMES
742    
743           There   are   two   new   general   option   names,   PCRE_UTF32    and
744           PCRE_NO_UTF32_CHECK,     which     correspond    to    PCRE_UTF8    and
745           PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
746           define  the  same bits in the options word. There is a discussion about
747           the validity of UTF-32 strings in the pcreunicode page.
748    
749           For the pcre32_config() function there is an  option  PCRE_CONFIG_UTF32
750           that  returns  1  if UTF-32 support is configured, otherwise 0. If this
751           option  is  given  to  pcre_config()  or  pcre16_config(),  or  if  the
752           PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF16  option is given to pcre32_con-
753           fig(), the result is the PCRE_ERROR_BADOPTION error.
754    
755    
756    CHARACTER CODES
757    
758           In 32-bit mode, when  PCRE_UTF32  is  not  set,  character  values  are
759           treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
760           that they can range from 0 to 0x7fffffff instead of 0 to 0xff.  Charac-
761           ter  types for characters less than 0xff can therefore be influenced by
762           the locale in the same way as before.   Characters  greater  than  0xff
763           have only one case, and no "type" (such as letter or digit).
764    
765           In  UTF-32  mode,  the  character  code  is  Unicode, in the range 0 to
766           0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
767           because those are "surrogate" values that are ill-formed in UTF-32.
768    
769           A  UTF-32 string can indicate its endianness by special code knows as a
770           byte-order mark (BOM). The PCRE functions do not handle this, expecting
771           strings   to   be  in  host  byte  order.  A  utility  function  called
772           pcre32_utf32_to_host_byte_order() is provided to help  with  this  (see
773           above).
774    
775    
776    ERROR NAMES
777    
778           The  error  PCRE_ERROR_BADUTF32  corresponds  to its 8-bit counterpart.
779           The error PCRE_ERROR_BADMODE is given when a compiled pattern is passed
780           to  a  function that processes patterns in the other mode, for example,
781           if a pattern compiled with pcre_compile() is passed to pcre32_exec().
782    
783           There are new error codes whose names  begin  with  PCRE_UTF32_ERR  for
784           invalid  UTF-32  strings,  corresponding to the PCRE_UTF8_ERR codes for
785           UTF-8 strings that are described in the section entitled "Reason  codes
786           for  invalid UTF-8 strings" in the main pcreapi page. The UTF-32 errors
787           are:
788    
789             PCRE_UTF32_ERR1  Surrogate character (range from 0xd800 to 0xdfff)
790             PCRE_UTF32_ERR2  Non-character
791             PCRE_UTF32_ERR3  Character > 0x10ffff
792    
793    
794    ERROR TEXTS
795    
796           If there is an error while compiling a pattern, the error text that  is
797           passed  back by pcre32_compile() or pcre32_compile2() is still an 8-bit
798           character string, zero-terminated.
799    
800    
801    CALLOUTS
802    
803           The subject and mark fields in the callout block that is  passed  to  a
804           callout function point to 32-bit vectors.
805    
806    
807    TESTING
808    
809           The  pcretest  program continues to operate with 8-bit input and output
810           files, but it can be used for testing the 32-bit library. If it is  run
811           with the command line option -32, patterns and subject strings are con-
812           verted from 8-bit to 32-bit before being passed to PCRE, and the 32-bit
813           library  functions  are used instead of the 8-bit ones. Returned 32-bit
814           strings are converted to 8-bit for output. If both the  8-bit  and  the
815           16-bit libraries were not compiled, pcretest defaults to 32-bit and the
816           -32 option is ignored.
817    
818           When PCRE is being built, the RunTest script that is  called  by  "make
819           check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
820           16-bit and 32-bit libraries has been built, and runs the  tests  appro-
821           priately.
822    
823    
824    NOT SUPPORTED IN 32-BIT MODE
825    
826           Not all the features of the 8-bit library are available with the 32-bit
827           library. The C++ and POSIX wrapper functions  support  only  the  8-bit
828           library, and the pcregrep program is at present 8-bit only.
829    
830    
831    AUTHOR
832    
833           Philip Hazel
834           University Computing Service
835           Cambridge CB2 3QH, England.
836    
837    
838    REVISION
839    
840           Last updated: 12 May 2013
841           Copyright (c) 1997-2013 University of Cambridge.
842    ------------------------------------------------------------------------------
843    
844    
845    PCREBUILD(3)               Library Functions Manual               PCREBUILD(3)
846    
847    
848    
849    NAME
850           PCRE - Perl-compatible regular expressions
851    
852  PCRE BUILD-TIME OPTIONS  PCRE BUILD-TIME OPTIONS
853    
# Line 289  PCRE BUILD-TIME OPTIONS Line 859  PCRE BUILD-TIME OPTIONS
859         environments using the GUI facility of cmake-gui if you are using CMake         environments using the GUI facility of cmake-gui if you are using CMake
860         instead of configure to build PCRE.         instead of configure to build PCRE.
861    
862         There  is  a  lot more information about building PCRE in non-Unix-like         There  is a lot more information about building PCRE without using con-
863         environments in the file called NON_UNIX_USE, which is part of the PCRE         figure (including information about using CMake or building "by  hand")
864         distribution.  You  should consult this file as well as the README file         in  the file called NON-AUTOTOOLS-BUILD, which is part of the PCRE dis-
865         if you are building in a non-Unix-like environment.         tribution. You should consult this file as well as the README  file  if
866           you are building in a non-Unix-like environment.
867    
868         The complete list of options for configure (which includes the standard         The complete list of options for configure (which includes the standard
869         ones  such  as  the  selection  of  the  installation directory) can be         ones such as the  selection  of  the  installation  directory)  can  be
870         obtained by running         obtained by running
871    
872           ./configure --help           ./configure --help
873    
874         The following sections include  descriptions  of  options  whose  names         The  following  sections  include  descriptions  of options whose names
875         begin with --enable or --disable. These settings specify changes to the         begin with --enable or --disable. These settings specify changes to the
876         defaults for the configure command. Because of the way  that  configure         defaults  for  the configure command. Because of the way that configure
877         works,  --enable  and --disable always come in pairs, so the complemen-         works, --enable and --disable always come in pairs, so  the  complemen-
878         tary option always exists as well, but as it specifies the default,  it         tary  option always exists as well, but as it specifies the default, it
879         is not described.         is not described.
880    
881    
882    BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES
883    
884           By default, a library called libpcre  is  built,  containing  functions
885           that  take  string  arguments  contained in vectors of bytes, either as
886           single-byte characters, or interpreted as UTF-8 strings. You  can  also
887           build  a  separate library, called libpcre16, in which strings are con-
888           tained in vectors of 16-bit data units and interpreted either  as  sin-
889           gle-unit characters or UTF-16 strings, by adding
890    
891             --enable-pcre16
892    
893           to the configure command. You can also build a separate library, called
894           libpcre32, in which strings are contained in  vectors  of  32-bit  data
895           units  and  interpreted  either  as  single-unit  characters  or UTF-32
896           strings, by adding
897    
898             --enable-pcre32
899    
900           to the configure command. If you do not want the 8-bit library, add
901    
902             --disable-pcre8
903    
904           as well. At least one of the three libraries must be built.  Note  that
905           the  C++  and  POSIX  wrappers are for the 8-bit library only, and that
906           pcregrep is an 8-bit program. None of these are  built  if  you  select
907           only the 16-bit or 32-bit libraries.
908    
909    
910    BUILDING SHARED AND STATIC LIBRARIES
911    
912           The  PCRE building process uses libtool to build both shared and static
913           Unix libraries by default. You can suppress one of these by adding  one
914           of
915    
916             --disable-shared
917             --disable-static
918    
919           to the configure command, as required.
920    
921    
922  C++ SUPPORT  C++ SUPPORT
923    
924         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
925         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,
926         library for PCRE. You can disable this by adding         it  automatically  builds  the C++ wrapper library (which supports only
927           8-bit strings). You can disable this by adding
928    
929           --disable-cpp           --disable-cpp
930    
931         to the configure command.         to the configure command.
932    
933    
934  UTF-8 SUPPORT  UTF-8, UTF-16 AND UTF-32 SUPPORT
935    
936         To build PCRE with support for UTF-8 Unicode character strings, add         To build PCRE with support for UTF Unicode character strings, add
937    
938           --enable-utf8           --enable-utf
939    
940         to  the  configure  command.  Of  itself, this does not make PCRE treat         to the configure command. This setting applies to all three  libraries,
941         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
942         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
943         or pcre_compile2() functions.         library.  There  are no separate options for enabling UTF-8, UTF-16 and
944           UTF-32 independently because that would allow ridiculous settings  such
945         If you set --enable-utf8 when compiling in an EBCDIC environment,  PCRE         as  requesting UTF-16 support while building only the 8-bit library. It
946         expects its input to be either ASCII or UTF-8 (depending on the runtime         is not possible to build one library with UTF support and another with-
947         option). It is not possible to support both EBCDIC and UTF-8  codes  in         out  in the same configuration. (For backwards compatibility, --enable-
948         the  same  version  of  the  library.  Consequently,  --enable-utf8 and         utf8 is a synonym of --enable-utf.)
949    
950           Of itself, this setting does not make  PCRE  treat  strings  as  UTF-8,
951           UTF-16  or UTF-32. As well as compiling PCRE with this option, you also
952           have have to set the PCRE_UTF8, PCRE_UTF16  or  PCRE_UTF32  option  (as
953           appropriate) when you call one of the pattern compiling functions.
954    
955           If  you  set --enable-utf when compiling in an EBCDIC environment, PCRE
956           expects its input to be either ASCII or UTF-8 (depending  on  the  run-
957           time option). It is not possible to support both EBCDIC and UTF-8 codes
958           in the same version of  the  library.  Consequently,  --enable-utf  and
959         --enable-ebcdic are mutually exclusive.         --enable-ebcdic are mutually exclusive.
960    
961    
962  UNICODE CHARACTER PROPERTY SUPPORT  UNICODE CHARACTER PROPERTY SUPPORT
963    
964         UTF-8 support allows PCRE to process character values greater than  255         UTF  support allows the libraries to process character codepoints up to
965         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
966         vide any facilities for accessing the properties of such characters. If         not provide any facilities for accessing the properties of such charac-
967         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,
968         refer to Unicode character properties, you must add         which refer to Unicode character properties, you must add
969    
970           --enable-unicode-properties           --enable-unicode-properties
971    
972         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
973         not explicitly requested it.         not explicitly requested it.
974    
975         Including  Unicode  property  support  adds around 30K of tables to the         Including Unicode property support adds around 30K  of  tables  to  the
976         PCRE library. Only the general category properties such as  Lu  and  Nd         PCRE  library.  Only  the general category properties such as Lu and Nd
977         are supported. Details are given in the pcrepattern documentation.         are supported. Details are given in the pcrepattern documentation.
978    
979    
980    JUST-IN-TIME COMPILER SUPPORT
981    
982           Just-in-time compiler support is included in the build by specifying
983    
984             --enable-jit
985    
986           This support is available only for certain hardware  architectures.  If
987           this  option  is  set  for  an unsupported architecture, a compile time
988           error occurs.  See the pcrejit documentation for a  discussion  of  JIT
989           usage. When JIT support is enabled, pcregrep automatically makes use of
990           it, unless you add
991    
992             --disable-pcregrep-jit
993    
994           to the "configure" command.
995    
996    
997  CODE VALUE OF NEWLINE  CODE VALUE OF NEWLINE
998    
999         By  default,  PCRE interprets the linefeed (LF) character as indicating         By default, PCRE interprets the linefeed (LF) character  as  indicating
1000         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
1001         systems.  You  can compile PCRE to use carriage return (CR) instead, by         systems. You can compile PCRE to use carriage return (CR)  instead,  by
1002         adding         adding
1003    
1004           --enable-newline-is-cr           --enable-newline-is-cr
1005    
1006         to the  configure  command.  There  is  also  a  --enable-newline-is-lf         to  the  configure  command.  There  is  also  a --enable-newline-is-lf
1007         option, which explicitly specifies linefeed as the newline character.         option, which explicitly specifies linefeed as the newline character.
1008    
1009         Alternatively, you can specify that line endings are to be indicated by         Alternatively, you can specify that line endings are to be indicated by
# Line 376  CODE VALUE OF NEWLINE Line 1015  CODE VALUE OF NEWLINE
1015    
1016           --enable-newline-is-anycrlf           --enable-newline-is-anycrlf
1017    
1018         which causes PCRE to recognize any of the three sequences  CR,  LF,  or         which  causes  PCRE  to recognize any of the three sequences CR, LF, or
1019         CRLF as indicating a line ending. Finally, a fifth option, specified by         CRLF as indicating a line ending. Finally, a fifth option, specified by
1020    
1021           --enable-newline-is-any           --enable-newline-is-any
1022    
1023         causes PCRE to recognize any Unicode newline sequence.         causes PCRE to recognize any Unicode newline sequence.
1024    
1025         Whatever  line  ending convention is selected when PCRE is built can be         Whatever line ending convention is selected when PCRE is built  can  be
1026         overridden when the library functions are called. At build time  it  is         overridden  when  the library functions are called. At build time it is
1027         conventional to use the standard for your operating system.         conventional to use the standard for your operating system.
1028    
1029    
1030  WHAT \R MATCHES  WHAT \R MATCHES
1031    
1032         By  default,  the  sequence \R in a pattern matches any Unicode newline         By default, the sequence \R in a pattern matches  any  Unicode  newline
1033         sequence, whatever has been selected as the line  ending  sequence.  If         sequence,  whatever  has  been selected as the line ending sequence. If
1034         you specify         you specify
1035    
1036           --enable-bsr-anycrlf           --enable-bsr-anycrlf
1037    
1038         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-
1039         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
1040         functions are called.         functions are called.
1041    
1042    
 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.  
   
   
1043  POSIX MALLOC USAGE  POSIX MALLOC USAGE
1044    
1045         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
1046         umentation), additional working storage is  required  for  holding  the         pcreposix  documentation),  additional  working storage is required for
1047         pointers  to capturing substrings, because PCRE requires three integers         holding the pointers to capturing  substrings,  because  PCRE  requires
1048         per substring, whereas the POSIX interface provides only  two.  If  the         three integers per substring, whereas the POSIX interface provides only
1049         number of expected substrings is small, the wrapper function uses space         two. If the number of expected substrings is small, the  wrapper  func-
1050         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-
1051         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
1052         can be changed by adding a setting such as         longer used is 10; it can be changed by adding a setting such as
1053    
1054           --with-posix-malloc-threshold=20           --with-posix-malloc-threshold=20
1055    
# Line 431  POSIX MALLOC USAGE Line 1058  POSIX MALLOC USAGE
1058    
1059  HANDLING VERY LARGE PATTERNS  HANDLING VERY LARGE PATTERNS
1060    
1061         Within a compiled pattern, offset values are used  to  point  from  one         Within  a  compiled  pattern,  offset values are used to point from one
1062         part  to another (for example, from an opening parenthesis to an alter-         part to another (for example, from an opening parenthesis to an  alter-
1063         nation metacharacter). By default, two-byte values are used  for  these         nation  metacharacter).  By default, in the 8-bit and 16-bit libraries,
1064         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
1065         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
1066         Nevertheless,  some  people do want to process truyl enormous patterns,         but the most gigantic patterns.  Nevertheless, some people do  want  to
1067         so it is possible to compile PCRE to use three-byte or  four-byte  off-         process  truly  enormous patterns, so it is possible to compile PCRE to
1068         sets by adding a setting such as         use three-byte or four-byte offsets by adding a setting such as
1069    
1070           --with-link-size=3           --with-link-size=3
1071    
1072         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
1073         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,
1074         additional bytes when handling them.         using longer offsets slows down the operation of PCRE because it has to
1075           load  additional  data  when  handling them. For the 32-bit library the
1076           value is always 4 and cannot be overridden; the value  of  --with-link-
1077           size is ignored.
1078    
1079    
1080  AVOIDING EXCESSIVE STACK USAGE  AVOIDING EXCESSIVE STACK USAGE
# Line 518  CREATING CHARACTER TABLES AT BUILD TIME Line 1148  CREATING CHARACTER TABLES AT BUILD TIME
1148         to  the  configure  command, the distributed tables are no longer used.         to  the  configure  command, the distributed tables are no longer used.
1149         Instead, a program called dftables is compiled and  run.  This  outputs         Instead, a program called dftables is compiled and  run.  This  outputs
1150         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
1151         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
1152         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.
1153         you need to create alternative tables when cross  compiling,  you  will         If you need to create alternative tables when cross compiling, you will
1154         have to do so "by hand".)         have to do so "by hand".)
1155    
1156    
# Line 536  USING EBCDIC CODE Line 1166  USING EBCDIC CODE
1166         to the configure command. This setting implies --enable-rebuild-charta-         to the configure command. This setting implies --enable-rebuild-charta-
1167         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
1168         environment (for example,  an  IBM  mainframe  operating  system).  The         environment (for example,  an  IBM  mainframe  operating  system).  The
1169         --enable-ebcdic option is incompatible with --enable-utf8.         --enable-ebcdic option is incompatible with --enable-utf.
1170    
1171           The EBCDIC character that corresponds to an ASCII LF is assumed to have
1172           the value 0x15 by default. However, in some EBCDIC  environments,  0x25
1173           is used. In such an environment you should use
1174    
1175             --enable-ebcdic-nl25
1176    
1177           as well as, or instead of, --enable-ebcdic. The EBCDIC character for CR
1178           has the same value as in ASCII, namely, 0x0d.  Whichever  of  0x15  and
1179           0x25 is not chosen as LF is made to correspond to the Unicode NEL char-
1180           acter (which, in Unicode, is 0x85).
1181    
1182           The options that select newline behaviour, such as --enable-newline-is-
1183           cr, and equivalent run-time options, refer to these character values in
1184           an EBCDIC environment.
1185    
1186    
1187  PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT  PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT
# Line 549  PCREGREP OPTIONS FOR COMPRESSED FILE SUP Line 1194  PCREGREP OPTIONS FOR COMPRESSED FILE SUP
1194           --enable-pcregrep-libbz2           --enable-pcregrep-libbz2
1195    
1196         to the configure command. These options naturally require that the rel-         to the configure command. These options naturally require that the rel-
1197         evant libraries are installed on your system. Configuration  will  fail         evant  libraries  are installed on your system. Configuration will fail
1198         if they are not.         if they are not.
1199    
1200    
1201    PCREGREP BUFFER SIZE
1202    
1203           pcregrep uses an internal buffer to hold a "window" on the file  it  is
1204           scanning, in order to be able to output "before" and "after" lines when
1205           it finds a match. The size of the buffer is controlled by  a  parameter
1206           whose default value is 20K. The buffer itself is three times this size,
1207           but because of the way it is used for holding "before" lines, the long-
1208           est  line  that  is guaranteed to be processable is the parameter size.
1209           You can change the default parameter value by adding, for example,
1210    
1211             --with-pcregrep-bufsize=50K
1212    
1213           to the configure command. The caller of pcregrep can, however, override
1214           this value by specifying a run-time option.
1215    
1216    
1217  PCRETEST OPTION FOR LIBREADLINE SUPPORT  PCRETEST OPTION FOR LIBREADLINE SUPPORT
1218    
1219         If you add         If you add
# Line 584  PCRETEST OPTION FOR LIBREADLINE SUPPORT Line 1245  PCRETEST OPTION FOR LIBREADLINE SUPPORT
1245         immediately before the configure command.         immediately before the configure command.
1246    
1247    
1248    DEBUGGING WITH VALGRIND SUPPORT
1249    
1250           By adding the
1251    
1252             --enable-valgrind
1253    
1254           option  to to the configure command, PCRE will use valgrind annotations
1255           to mark certain memory regions as  unaddressable.  This  allows  it  to
1256           detect invalid memory accesses, and is mostly useful for debugging PCRE
1257           itself.
1258    
1259    
1260    CODE COVERAGE REPORTING
1261    
1262           If your C compiler is gcc, you can build a version  of  PCRE  that  can
1263           generate a code coverage report for its test suite. To enable this, you
1264           must install lcov version 1.6 or above. Then specify
1265    
1266             --enable-coverage
1267    
1268           to the configure command and build PCRE in the usual way.
1269    
1270           Note that using ccache (a caching C compiler) is incompatible with code
1271           coverage  reporting. If you have configured ccache to run automatically
1272           on your system, you must set the environment variable
1273    
1274             CCACHE_DISABLE=1
1275    
1276           before running make to build PCRE, so that ccache is not used.
1277    
1278           When --enable-coverage is used,  the  following  addition  targets  are
1279           added to the Makefile:
1280    
1281             make coverage
1282    
1283           This  creates  a  fresh  coverage report for the PCRE test suite. It is
1284           equivalent to running "make coverage-reset", "make  coverage-baseline",
1285           "make check", and then "make coverage-report".
1286    
1287             make coverage-reset
1288    
1289           This zeroes the coverage counters, but does nothing else.
1290    
1291             make coverage-baseline
1292    
1293           This captures baseline coverage information.
1294    
1295             make coverage-report
1296    
1297           This creates the coverage report.
1298    
1299             make coverage-clean-report
1300    
1301           This  removes the generated coverage report without cleaning the cover-
1302           age data itself.
1303    
1304             make coverage-clean-data
1305    
1306           This removes the captured coverage data without removing  the  coverage
1307           files created at compile time (*.gcno).
1308    
1309             make coverage-clean
1310    
1311           This  cleans all coverage data including the generated coverage report.
1312           For more information about code coverage, see the gcov and  lcov  docu-
1313           mentation.
1314    
1315    
1316  SEE ALSO  SEE ALSO
1317    
1318         pcreapi(3), pcre_config(3).         pcreapi(3), pcre16, pcre32, pcre_config(3).
1319    
1320    
1321  AUTHOR  AUTHOR
# Line 598  AUTHOR Line 1327  AUTHOR
1327    
1328  REVISION  REVISION
1329    
1330         Last updated: 29 September 2009         Last updated: 30 October 2012
1331         Copyright (c) 1997-2009 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
1332  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1333    
1334    
1335    PCREMATCHING(3)            Library Functions Manual            PCREMATCHING(3)
1336    
1337    
 PCREMATCHING(3)                                                PCREMATCHING(3)  
   
1338    
1339  NAME  NAME
1340         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
1341    
   
1342  PCRE MATCHING ALGORITHMS  PCRE MATCHING ALGORITHMS
1343    
1344         This document describes the two different algorithms that are available         This document describes the two different algorithms that are available
1345         in PCRE for matching a compiled regular expression against a given sub-         in PCRE for matching a compiled regular expression against a given sub-
1346         ject  string.  The  "standard"  algorithm  is  the  one provided by the         ject  string.  The  "standard"  algorithm  is  the  one provided by the
1347         pcre_exec() function.  This works in the same was  as  Perl's  matching         pcre_exec(), pcre16_exec() and pcre32_exec() functions. These  work  in
1348         function, and provides a Perl-compatible matching operation.         the  same as as Perl's matching function, and provide a Perl-compatible
1349           matching  operation.   The  just-in-time  (JIT)  optimization  that  is
1350         An  alternative  algorithm is provided by the pcre_dfa_exec() function;         described  in  the pcrejit documentation is compatible with these func-
1351         this operates in a different way, and is not  Perl-compatible.  It  has         tions.
1352         advantages  and disadvantages compared with the standard algorithm, and  
1353         these are described below.         An  alternative  algorithm  is   provided   by   the   pcre_dfa_exec(),
1354           pcre16_dfa_exec()  and  pcre32_dfa_exec()  functions; they operate in a
1355           different way, and are not Perl-compatible. This alternative has advan-
1356           tages and disadvantages compared with the standard algorithm, and these
1357           are described below.
1358    
1359         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
1360         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 697  THE ALTERNATIVE MATCHING ALGORITHM Line 1430  THE ALTERNATIVE MATCHING ALGORITHM
1430         represent the different matching possibilities (if there are none,  the         represent the different matching possibilities (if there are none,  the
1431         match  has  failed).   Thus,  if there is more than one possible match,         match  has  failed).   Thus,  if there is more than one possible match,
1432         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-
1433         est.  There  is  an  option to stop the algorithm after the first match         est.  The  matches are returned in decreasing order of length. There is
1434         (which is necessarily the shortest) is found.         an option to stop the algorithm after the first match (which is  neces-
1435           sarily the shortest) is found.
1436    
1437         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
1438         subject. If the pattern         subject. If the pattern
1439    
1440           cat(er(pillar)?)           cat(er(pillar)?)?
1441    
1442         is  matched  against the string "the caterpillar catchment", the result         is matched against the string "the caterpillar catchment",  the  result
1443         will be the three strings "cat", "cater", and "caterpillar" that  start         will  be the three strings "caterpillar", "cater", and "cat" that start
1444         at the fourth character of the subject. The algorithm does not automat-         at the fifth character of the subject. The algorithm does not automati-
1445         ically move on to find matches that start at later positions.         cally move on to find matches that start at later positions.
1446    
1447         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
1448         supported by the alternative matching algorithm. They are as follows:         supported by the alternative matching algorithm. They are as follows:
1449    
1450         1.  Because  the  algorithm  finds  all possible matches, the greedy or         1. Because the algorithm finds all  possible  matches,  the  greedy  or
1451         ungreedy nature of repetition quantifiers is not relevant.  Greedy  and         ungreedy  nature  of repetition quantifiers is not relevant. Greedy and
1452         ungreedy quantifiers are treated in exactly the same way. However, pos-         ungreedy quantifiers are treated in exactly the same way. However, pos-
1453         sessive quantifiers can make a difference when what follows could  also         sessive  quantifiers can make a difference when what follows could also
1454         match what is quantified, for example in a pattern like this:         match what is quantified, for example in a pattern like this:
1455    
1456           ^a++\w!           ^a++\w!
1457    
1458         This  pattern matches "aaab!" but not "aaa!", which would be matched by         This pattern matches "aaab!" but not "aaa!", which would be matched  by
1459         a non-possessive quantifier. Similarly, if an atomic group is  present,         a  non-possessive quantifier. Similarly, if an atomic group is present,
1460         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,
1461         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
1462         pattern.         pattern.
1463    
1464         2. When dealing with multiple paths through the tree simultaneously, it         2. When dealing with multiple paths through the tree simultaneously, it
1465         is not straightforward to keep track of  captured  substrings  for  the         is  not  straightforward  to  keep track of captured substrings for the
1466         different  matching  possibilities,  and  PCRE's implementation of this         different matching possibilities, and  PCRE's  implementation  of  this
1467         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-
1468         strings are available.         strings are available.
1469    
1470         3.  Because no substrings are captured, back references within the pat-         3. Because no substrings are captured, back references within the  pat-
1471         tern are not supported, and cause errors if encountered.         tern are not supported, and cause errors if encountered.
1472    
1473         4. For the same reason, conditional expressions that use  a  backrefer-         4.  For  the same reason, conditional expressions that use a backrefer-
1474         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
1475         supported.         supported.
1476    
1477         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
1478         sequence, which resets the start of the match when encountered (but may         sequence, which resets the start of the match when encountered (but may
1479         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
1480         error if encountered.         error if encountered.
1481    
1482         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
1483         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.
1484    
1485         7. The \C escape sequence, which (in the standard algorithm) matches  a         7.  The  \C  escape  sequence, which (in the standard algorithm) always
1486         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
1487         tive algorithm moves through the subject  string  one  character  at  a         not  supported  in these modes, because the alternative algorithm moves
1488         time, for all active paths through the tree.         through the subject string one character (not data unit) at a time, for
1489           all active paths through the tree.
1490    
1491         8.  Except for (*FAIL), the backtracking control verbs such as (*PRUNE)         8.  Except for (*FAIL), the backtracking control verbs such as (*PRUNE)
1492         are not supported. (*FAIL) is supported, and  behaves  like  a  failing         are not supported. (*FAIL) is supported, and  behaves  like  a  failing
# Line 769  ADVANTAGES OF THE ALTERNATIVE ALGORITHM Line 1504  ADVANTAGES OF THE ALTERNATIVE ALGORITHM
1504         things with callouts.         things with callouts.
1505    
1506         2.  Because  the  alternative  algorithm  scans the subject string just         2.  Because  the  alternative  algorithm  scans the subject string just
1507         once, and never needs to backtrack, it is possible to  pass  very  long         once, and never needs to backtrack (except for lookbehinds), it is pos-
1508         subject  strings  to  the matching function in several pieces, checking         sible  to  pass  very  long subject strings to the matching function in
1509         for partial matching each time.  The  pcrepartial  documentation  gives         several pieces, checking for partial matching each time. Although it is
1510         details of partial matching.         possible  to  do multi-segment matching using the standard algorithm by
1511           retaining partially matched substrings, it  is  more  complicated.  The
1512           pcrepartial  documentation  gives  details of partial matching and dis-
1513           cusses multi-segment matching.
1514    
1515    
1516  DISADVANTAGES OF THE ALTERNATIVE ALGORITHM  DISADVANTAGES OF THE ALTERNATIVE ALGORITHM
1517    
1518         The alternative algorithm suffers from a number of disadvantages:         The alternative algorithm suffers from a number of disadvantages:
1519    
1520         1.  It  is  substantially  slower  than the standard algorithm. This is         1. It is substantially slower than  the  standard  algorithm.  This  is
1521         partly because it has to search for all possible matches, but  is  also         partly  because  it has to search for all possible matches, but is also
1522         because it is less susceptible to optimization.         because it is less susceptible to optimization.
1523    
1524         2. Capturing parentheses and back references are not supported.         2. Capturing parentheses and back references are not supported.
# Line 798  AUTHOR Line 1536  AUTHOR
1536    
1537  REVISION  REVISION
1538    
1539         Last updated: 29 September 2009         Last updated: 08 January 2012
1540         Copyright (c) 1997-2009 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
1541  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1542    
1543    
1544    PCREAPI(3)                 Library Functions Manual                 PCREAPI(3)
1545    
1546    
 PCREAPI(3)                                                          PCREAPI(3)  
   
1547    
1548  NAME  NAME
1549         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
1550    
1551           #include <pcre.h>
1552    
 PCRE NATIVE API  
1553    
1554         #include <pcre.h>  PCRE NATIVE API BASIC FUNCTIONS
1555    
1556         pcre *pcre_compile(const char *pattern, int options,         pcre *pcre_compile(const char *pattern, int options,
1557              const char **errptr, int *erroffset,              const char **errptr, int *erroffset,
# Line 826  PCRE NATIVE API Line 1565  PCRE NATIVE API
1565         pcre_extra *pcre_study(const pcre *code, int options,         pcre_extra *pcre_study(const pcre *code, int options,
1566              const char **errptr);              const char **errptr);
1567    
1568           void pcre_free_study(pcre_extra *extra);
1569    
1570         int pcre_exec(const pcre *code, const pcre_extra *extra,         int pcre_exec(const pcre *code, const pcre_extra *extra,
1571              const char *subject, int length, int startoffset,              const char *subject, int length, int startoffset,
1572              int options, int *ovector, int ovecsize);              int options, int *ovector, int ovecsize);
# Line 835  PCRE NATIVE API Line 1576  PCRE NATIVE API
1576              int options, int *ovector, int ovecsize,              int options, int *ovector, int ovecsize,
1577              int *workspace, int wscount);              int *workspace, int wscount);
1578    
1579    
1580    PCRE NATIVE API STRING EXTRACTION FUNCTIONS
1581    
1582         int pcre_copy_named_substring(const pcre *code,         int pcre_copy_named_substring(const pcre *code,
1583              const char *subject, int *ovector,              const char *subject, int *ovector,
1584              int stringcount, const char *stringname,              int stringcount, const char *stringname,
# Line 866  PCRE NATIVE API Line 1610  PCRE NATIVE API
1610    
1611         void pcre_free_substring_list(const char **stringptr);         void pcre_free_substring_list(const char **stringptr);
1612    
1613    
1614    PCRE NATIVE API AUXILIARY FUNCTIONS
1615    
1616           int pcre_jit_exec(const pcre *code, const pcre_extra *extra,
1617                const char *subject, int length, int startoffset,
1618                int options, int *ovector, int ovecsize,
1619                pcre_jit_stack *jstack);
1620    
1621           pcre_jit_stack *pcre_jit_stack_alloc(int startsize, int maxsize);
1622    
1623           void pcre_jit_stack_free(pcre_jit_stack *stack);
1624    
1625           void pcre_assign_jit_stack(pcre_extra *extra,
1626                pcre_jit_callback callback, void *data);
1627    
1628         const unsigned char *pcre_maketables(void);         const unsigned char *pcre_maketables(void);
1629    
1630         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
1631              int what, void *where);              int what, void *where);
1632    
        int pcre_info(const pcre *code, int *optptr, int *firstcharptr);  
   
1633         int pcre_refcount(pcre *code, int adjust);         int pcre_refcount(pcre *code, int adjust);
1634    
1635         int pcre_config(int what, void *where);         int pcre_config(int what, void *where);
1636    
1637         char *pcre_version(void);         const char *pcre_version(void);
1638    
1639           int pcre_pattern_to_host_byte_order(pcre *code,
1640                pcre_extra *extra, const unsigned char *tables);
1641    
1642    
1643    PCRE NATIVE API INDIRECTED FUNCTIONS
1644    
1645         void *(*pcre_malloc)(size_t);         void *(*pcre_malloc)(size_t);
1646    
# Line 890  PCRE NATIVE API Line 1653  PCRE NATIVE API
1653         int (*pcre_callout)(pcre_callout_block *);         int (*pcre_callout)(pcre_callout_block *);
1654    
1655    
1656    PCRE 8-BIT, 16-BIT, AND 32-BIT LIBRARIES
1657    
1658           As  well  as  support  for  8-bit character strings, PCRE also supports
1659           16-bit strings (from release 8.30) and  32-bit  strings  (from  release
1660           8.32),  by means of two additional libraries. They can be built as well
1661           as, or instead of, the 8-bit library. To avoid too  much  complication,
1662           this  document describes the 8-bit versions of the functions, with only
1663           occasional references to the 16-bit and 32-bit libraries.
1664    
1665           The 16-bit and 32-bit functions operate in the same way as their  8-bit
1666           counterparts;  they  just  use different data types for their arguments
1667           and results, and their names start with pcre16_ or pcre32_  instead  of
1668           pcre_.  For  every  option  that  has  UTF8  in  its name (for example,
1669           PCRE_UTF8), there are corresponding 16-bit and 32-bit names  with  UTF8
1670           replaced by UTF16 or UTF32, respectively. This facility is in fact just
1671           cosmetic; the 16-bit and 32-bit option names define the same  bit  val-
1672           ues.
1673    
1674           References to bytes and UTF-8 in this document should be read as refer-
1675           ences to 16-bit data units and UTF-16 when using the 16-bit library, or
1676           32-bit  data  units  and  UTF-32  when using the 32-bit library, unless
1677           specified otherwise.  More details of the specific differences for  the
1678           16-bit and 32-bit libraries are given in the pcre16 and pcre32 pages.
1679    
1680    
1681  PCRE API OVERVIEW  PCRE API OVERVIEW
1682    
1683         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
1684         are also some wrapper functions that correspond to  the  POSIX  regular         are also some wrapper functions (for the 8-bit library only) that  cor-
1685         expression  API.  These  are  described in the pcreposix documentation.         respond  to  the  POSIX  regular  expression  API, but they do not give
1686         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
1687         distributed with PCRE. It is documented in the pcrecpp page.         documentation.  Both  of these APIs define a set of C function calls. A
1688           C++ wrapper (again for the 8-bit library only) is also distributed with
1689           PCRE. It is documented in the pcrecpp page.
1690    
1691         The  native  API  C  function prototypes are defined in the header file         The  native  API  C  function prototypes are defined in the header file
1692         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
1693         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
1694         application  that  uses  PCRE.  The  header  file  defines  the  macros         for linking an application that uses PCRE. The header file defines  the
1695         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
1696         bers for the library.  Applications can use these  to  include  support         numbers for the library. Applications can use these to include  support
1697         for different releases of PCRE.         for different releases of PCRE.
1698    
1699         In a Windows environment, if you want to statically link an application         In a Windows environment, if you want to statically link an application
# Line 920  PCRE API OVERVIEW Line 1710  PCRE API OVERVIEW
1710         pcredemo documentation, and the pcresample documentation describes  how         pcredemo documentation, and the pcresample documentation describes  how
1711         to compile and run it.         to compile and run it.
1712    
1713           Just-in-time  compiler  support is an optional feature of PCRE that can
1714           be built in appropriate hardware environments. It greatly speeds up the
1715           matching  performance  of  many  patterns.  Simple  programs can easily
1716           request that it be used if available, by  setting  an  option  that  is
1717           ignored  when  it is not relevant. More complicated programs might need
1718           to    make    use    of    the    functions     pcre_jit_stack_alloc(),
1719           pcre_jit_stack_free(),  and pcre_assign_jit_stack() in order to control
1720           the JIT code's memory usage.
1721    
1722           From release 8.32 there is also a direct interface for  JIT  execution,
1723           which  gives  improved performance. The JIT-specific functions are dis-
1724           cussed in the pcrejit documentation.
1725    
1726         A second matching function, pcre_dfa_exec(), which is not Perl-compati-         A second matching function, pcre_dfa_exec(), which is not Perl-compati-
1727         ble, is also provided. This uses a different algorithm for  the  match-         ble,  is  also provided. This uses a different algorithm for the match-
1728         ing.  The  alternative algorithm finds all possible matches (at a given         ing. The alternative algorithm finds all possible matches (at  a  given
1729         point in the subject), and scans the subject just  once  (unless  there         point  in  the  subject), and scans the subject just once (unless there
1730         are  lookbehind  assertions).  However,  this algorithm does not return         are lookbehind assertions). However, this  algorithm  does  not  return
1731         captured substrings. A description of the two matching  algorithms  and         captured  substrings.  A description of the two matching algorithms and
1732         their  advantages  and disadvantages is given in the pcrematching docu-         their advantages and disadvantages is given in the  pcrematching  docu-
1733         mentation.         mentation.
1734    
1735         In addition to the main compiling and  matching  functions,  there  are         In  addition  to  the  main compiling and matching functions, there are
1736         convenience functions for extracting captured substrings from a subject         convenience functions for extracting captured substrings from a subject
1737         string that is matched by pcre_exec(). They are:         string that is matched by pcre_exec(). They are:
1738    
# Line 944  PCRE API OVERVIEW Line 1747  PCRE API OVERVIEW
1747         pcre_free_substring() and pcre_free_substring_list() are also provided,         pcre_free_substring() and pcre_free_substring_list() are also provided,
1748         to free the memory used for extracted strings.         to free the memory used for extracted strings.
1749    
1750         The  function  pcre_maketables()  is  used  to build a set of character         The function pcre_maketables() is used to  build  a  set  of  character
1751         tables  in  the  current  locale   for   passing   to   pcre_compile(),         tables   in   the   current   locale  for  passing  to  pcre_compile(),
1752         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
1753         provided for specialist use.  Most  commonly,  no  special  tables  are         provided  for  specialist  use.  Most  commonly,  no special tables are
1754         passed,  in  which case internal tables that are generated when PCRE is         passed, in which case internal tables that are generated when  PCRE  is
1755         built are used.         built are used.
1756    
1757         The function pcre_fullinfo() is used to find out  information  about  a         The  function  pcre_fullinfo()  is used to find out information about a
1758         compiled  pattern; pcre_info() is an obsolete version that returns only         compiled pattern. The function pcre_version() returns a  pointer  to  a
1759         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.  
1760    
1761         The function pcre_refcount() maintains a  reference  count  in  a  data         The  function  pcre_refcount()  maintains  a  reference count in a data
1762         block  containing  a compiled pattern. This is provided for the benefit         block containing a compiled pattern. This is provided for  the  benefit
1763         of object-oriented applications.         of object-oriented applications.
1764    
1765         The global variables pcre_malloc and pcre_free  initially  contain  the         The  global  variables  pcre_malloc and pcre_free initially contain the
1766         entry  points  of  the  standard malloc() and free() functions, respec-         entry points of the standard malloc()  and  free()  functions,  respec-
1767         tively. PCRE calls the memory management functions via these variables,         tively. PCRE calls the memory management functions via these variables,
1768         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
1769         calls. This should be done before calling any PCRE functions.         calls. This should be done before calling any PCRE functions.
1770    
1771         The global variables pcre_stack_malloc  and  pcre_stack_free  are  also         The  global  variables  pcre_stack_malloc  and pcre_stack_free are also
1772         indirections  to  memory  management functions. These special functions         indirections to memory management functions.  These  special  functions
1773         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
1774         data, instead of recursive function calls, when running the pcre_exec()         data, instead of recursive function calls, when running the pcre_exec()
1775         function. See the pcrebuild documentation for  details  of  how  to  do         function.  See  the  pcrebuild  documentation  for details of how to do
1776         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-
1777         ments that have limited stacks. Because of the greater  use  of  memory         ments  that  have  limited stacks. Because of the greater use of memory
1778         management,  it  runs  more  slowly. Separate functions are provided so         management, it runs more slowly. Separate  functions  are  provided  so
1779         that special-purpose external code can be  used  for  this  case.  When         that  special-purpose  external  code  can  be used for this case. When
1780         used,  these  functions  are always called in a stack-like manner (last         used, these functions are always called in a  stack-like  manner  (last
1781         obtained, first freed), and always for memory blocks of the same  size.         obtained,  first freed), and always for memory blocks of the same size.
1782         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-
1783         mentation.         mentation.
1784    
1785         The global variable pcre_callout initially contains NULL. It can be set         The global variable pcre_callout initially contains NULL. It can be set
1786         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
1787         specified points during a matching operation. Details are given in  the         specified  points during a matching operation. Details are given in the
1788         pcrecallout documentation.         pcrecallout documentation.
1789    
1790    
1791  NEWLINES  NEWLINES
1792    
1793         PCRE  supports five different conventions for indicating line breaks in         PCRE supports five different conventions for indicating line breaks  in
1794         strings: a single CR (carriage return) character, a  single  LF  (line-         strings:  a  single  CR (carriage return) character, a single LF (line-
1795         feed) character, the two-character sequence CRLF, any of the three pre-         feed) character, the two-character sequence CRLF, any of the three pre-
1796         ceding, or any Unicode newline sequence. The Unicode newline  sequences         ceding,  or any Unicode newline sequence. The Unicode newline sequences
1797         are  the  three just mentioned, plus the single characters VT (vertical         are the three just mentioned, plus the single characters  VT  (vertical
1798         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
1799         separator, U+2028), and PS (paragraph separator, U+2029).         separator, U+2028), and PS (paragraph separator, U+2029).
1800    
1801         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
1802         system as its standard newline sequence. When PCRE is built, a  default         system  as its standard newline sequence. When PCRE is built, a default
1803         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-
1804         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
1805         pattern is compiled, or when it is matched.         pattern is compiled, or when it is matched.
1806    
1807         At compile time, the newline convention can be specified by the options         At compile time, the newline convention can be specified by the options
1808         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
1809         the start of the pattern itself; this overrides any other settings. See         the start of the pattern itself; this overrides any other settings. See
1810         the pcrepattern page for details of the special character sequences.         the pcrepattern page for details of the special character sequences.
1811    
1812         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-
1813         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
1814         newline convention affects the handling of  the  dot,  circumflex,  and         newline  convention  affects  the  handling of the dot, circumflex, and
1815         dollar metacharacters, the handling of #-comments in /x mode, and, when         dollar metacharacters, the handling of #-comments in /x mode, and, when
1816         CRLF is a recognized line ending sequence, the match position  advance-         CRLF  is a recognized line ending sequence, the match position advance-
1817         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
1818         section on pcre_exec() options below.         section on pcre_exec() options below.
1819    
1820         The choice of newline convention does not affect the interpretation  of         The  choice of newline convention does not affect the interpretation of
1821         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,
1822         which is controlled in a similar way, but by separate options.         which is controlled in a similar way, but by separate options.
1823    
1824    
1825  MULTITHREADING  MULTITHREADING
1826    
1827         The PCRE functions can be used in  multi-threading  applications,  with         The  PCRE  functions  can be used in multi-threading applications, with
1828         the  proviso  that  the  memory  management  functions  pointed  to  by         the  proviso  that  the  memory  management  functions  pointed  to  by
1829         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
1830         callout function pointed to by pcre_callout, are shared by all threads.         callout function pointed to by pcre_callout, are shared by all threads.
1831    
1832         The  compiled form of a regular expression is not altered during match-         The compiled form of a regular expression is not altered during  match-
1833         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
1834         at once.         at once.
1835    
1836           If the just-in-time optimization feature is being used, it needs  sepa-
1837           rate  memory stack areas for each thread. See the pcrejit documentation
1838           for more details.
1839    
1840    
1841  SAVING PRECOMPILED PATTERNS FOR LATER USE  SAVING PRECOMPILED PATTERNS FOR LATER USE
1842    
1843         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
1844         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
1845         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
1846         pcreprecompile documentation. However, compiling a  regular  expression         pcreprecompile  documentation,  which  includes  a  description  of the
1847         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-
1848         anteed to work and may cause crashes.         lar  expression  with one version of PCRE for use with a different ver-
1849           sion is not guaranteed to work and may cause crashes.
1850    
1851    
1852  CHECKING BUILD-TIME OPTIONS  CHECKING BUILD-TIME OPTIONS
# Line 1054  CHECKING BUILD-TIME OPTIONS Line 1860  CHECKING BUILD-TIME OPTIONS
1860    
1861         The  first  argument  for pcre_config() is an integer, specifying which         The  first  argument  for pcre_config() is an integer, specifying which
1862         information is required; the second argument is a pointer to a variable         information is required; the second argument is a pointer to a variable
1863         into  which  the  information  is  placed. The following information is         into  which  the  information  is placed. The returned value is zero on
1864           success, or the negative error code PCRE_ERROR_BADOPTION if  the  value
1865           in  the  first argument is not recognized. The following information is
1866         available:         available:
1867    
1868           PCRE_CONFIG_UTF8           PCRE_CONFIG_UTF8
1869    
1870         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-
1871         able; otherwise it is set to zero.         able;  otherwise it is set to zero. This value should normally be given
1872           to the 8-bit version of this function, pcre_config(). If it is given to
1873           the   16-bit  or  32-bit  version  of  this  function,  the  result  is
1874           PCRE_ERROR_BADOPTION.
1875    
1876             PCRE_CONFIG_UTF16
1877    
1878           The output is an integer that is set to one if UTF-16 support is avail-
1879           able;  otherwise it is set to zero. This value should normally be given
1880           to the 16-bit version of this function, pcre16_config(). If it is given
1881           to  the  8-bit  or  32-bit  version  of  this  function,  the result is
1882           PCRE_ERROR_BADOPTION.
1883    
1884             PCRE_CONFIG_UTF32
1885    
1886           The output is an integer that is set to one if UTF-32 support is avail-
1887           able;  otherwise it is set to zero. This value should normally be given
1888           to the 32-bit version of this function, pcre32_config(). If it is given
1889           to  the  8-bit  or  16-bit  version  of  this  function,  the result is
1890           PCRE_ERROR_BADOPTION.
1891    
1892           PCRE_CONFIG_UNICODE_PROPERTIES           PCRE_CONFIG_UNICODE_PROPERTIES
1893    
1894         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
1895         character properties is available; otherwise it is set to zero.         character properties is available; otherwise it is set to zero.
1896    
1897             PCRE_CONFIG_JIT
1898    
1899           The output is an integer that is set to one if support for just-in-time
1900           compiling is available; otherwise it is set to zero.
1901    
1902             PCRE_CONFIG_JITTARGET
1903    
1904           The output is a pointer to a zero-terminated "const char *" string.  If
1905           JIT support is available, the string contains the name of the architec-
1906           ture for which the JIT compiler is configured, for example  "x86  32bit
1907           (little  endian  +  unaligned)".  If  JIT support is not available, the
1908           result is NULL.
1909    
1910           PCRE_CONFIG_NEWLINE           PCRE_CONFIG_NEWLINE
1911    
1912         The output is an integer whose value specifies  the  default  character         The output is an integer whose value specifies  the  default  character
1913         sequence  that is recognized as meaning "newline". The four values that         sequence  that  is recognized as meaning "newline". The values that are
1914         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
1915         and  -1  for  ANY.  Though they are derived from ASCII, the same values         for  CRLF,  -2 for ANYCRLF, and -1 for ANY. In EBCDIC environments, CR,
1916         are returned in EBCDIC environments. The default should normally corre-         ANYCRLF, and ANY yield the same values. However, the value  for  LF  is
1917           normally  21, though some EBCDIC environments use 37. The corresponding
1918           values for CRLF are 3349 and 3365. The default should  normally  corre-
1919         spond to the standard sequence for your operating system.         spond to the standard sequence for your operating system.
1920    
1921           PCRE_CONFIG_BSR           PCRE_CONFIG_BSR
# Line 1087  CHECKING BUILD-TIME OPTIONS Line 1929  CHECKING BUILD-TIME OPTIONS
1929           PCRE_CONFIG_LINK_SIZE           PCRE_CONFIG_LINK_SIZE
1930    
1931         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
1932         internal linkage in compiled regular expressions. The value is 2, 3, or         internal  linkage  in  compiled  regular  expressions.  For  the  8-bit
1933         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
1934         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
1935         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
1936         pattern to be up to 64K in size.         default value of 2 is sufficient for all but the most massive patterns,
1937           since  it  allows  the compiled pattern to be up to 64K in size. Larger
1938           values allow larger regular expressions to be compiled, at the  expense
1939           of slower matching.
1940    
1941           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
1942    
1943         The output is an integer that contains the threshold  above  which  the         The  output  is  an integer that contains the threshold above which the
1944         POSIX  interface  uses malloc() for output vectors. Further details are         POSIX interface uses malloc() for output vectors. Further  details  are
1945         given in the pcreposix documentation.         given in the pcreposix documentation.
1946    
1947           PCRE_CONFIG_MATCH_LIMIT           PCRE_CONFIG_MATCH_LIMIT
1948    
1949         The output is a long integer that gives the default limit for the  num-         The  output is a long integer that gives the default limit for the num-
1950         ber  of  internal  matching  function calls in a pcre_exec() execution.         ber of internal matching function calls  in  a  pcre_exec()  execution.
1951         Further details are given with pcre_exec() below.         Further details are given with pcre_exec() below.
1952    
1953           PCRE_CONFIG_MATCH_LIMIT_RECURSION           PCRE_CONFIG_MATCH_LIMIT_RECURSION
1954    
1955         The output is a long integer that gives the default limit for the depth         The output is a long integer that gives the default limit for the depth
1956         of   recursion  when  calling  the  internal  matching  function  in  a         of  recursion  when  calling  the  internal  matching  function  in   a
1957         pcre_exec() execution.  Further  details  are  given  with  pcre_exec()         pcre_exec()  execution.  Further  details  are  given  with pcre_exec()
1958         below.         below.
1959    
1960           PCRE_CONFIG_STACKRECURSE           PCRE_CONFIG_STACKRECURSE
1961    
1962         The  output is an integer that is set to one if internal recursion when         The output is an integer that is set to one if internal recursion  when
1963         running pcre_exec() is implemented by recursive function calls that use         running pcre_exec() is implemented by recursive function calls that use
1964         the  stack  to remember their state. This is the usual way that PCRE is         the stack to remember their state. This is the usual way that  PCRE  is
1965         compiled. The output is zero if PCRE was compiled to use blocks of data         compiled. The output is zero if PCRE was compiled to use blocks of data
1966         on  the  heap  instead  of  recursive  function  calls.  In  this case,         on the  heap  instead  of  recursive  function  calls.  In  this  case,
1967         pcre_stack_malloc and  pcre_stack_free  are  called  to  manage  memory         pcre_stack_malloc  and  pcre_stack_free  are  called  to  manage memory
1968         blocks on the heap, thus avoiding the use of the stack.         blocks on the heap, thus avoiding the use of the stack.
1969    
1970    
# Line 1136  COMPILING A PATTERN Line 1981  COMPILING A PATTERN
1981    
1982         Either of the functions pcre_compile() or pcre_compile2() can be called         Either of the functions pcre_compile() or pcre_compile2() can be called
1983         to compile a pattern into an internal form. The only difference between         to compile a pattern into an internal form. The only difference between
1984         the  two interfaces is that pcre_compile2() has an additional argument,         the two interfaces is that pcre_compile2() has an additional  argument,
1985         errorcodeptr, via which a numerical error  code  can  be  returned.  To         errorcodeptr,  via  which  a  numerical  error code can be returned. To
1986         avoid  too  much repetition, we refer just to pcre_compile() below, but         avoid too much repetition, we refer just to pcre_compile()  below,  but
1987         the information applies equally to pcre_compile2().         the information applies equally to pcre_compile2().
1988    
1989         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
1990         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
1991         obtained via pcre_malloc is returned. This contains the  compiled  code         obtained  via  pcre_malloc is returned. This contains the compiled code
1992         and related data. The pcre type is defined for the returned block; this         and related data. The pcre type is defined for the returned block; this
1993         is a typedef for a structure whose contents are not externally defined.         is a typedef for a structure whose contents are not externally defined.
1994         It is up to the caller to free the memory (via pcre_free) when it is no         It is up to the caller to free the memory (via pcre_free) when it is no
1995         longer required.         longer required.
1996    
1997         Although the compiled code of a PCRE regex is relocatable, that is,  it         Although  the compiled code of a PCRE regex is relocatable, that is, it
1998         does not depend on memory location, the complete pcre data block is not         does not depend on memory location, the complete pcre data block is not
1999         fully relocatable, because it may contain a copy of the tableptr  argu-         fully  relocatable, because it may contain a copy of the tableptr argu-
2000         ment, which is an address (see below).         ment, which is an address (see below).
2001    
2002         The options argument contains various bit settings that affect the com-         The options argument contains various bit settings that affect the com-
2003         pilation. It should be zero if no options are required.  The  available         pilation.  It  should be zero if no options are required. The available
2004         options  are  described  below. Some of them (in particular, those that         options are described below. Some of them (in  particular,  those  that
2005         are compatible with Perl, but some others as well) can also be set  and         are  compatible with Perl, but some others as well) can also be set and
2006         unset  from  within  the  pattern  (see the detailed description in the         unset from within the pattern (see  the  detailed  description  in  the
2007         pcrepattern documentation). For those options that can be different  in         pcrepattern  documentation). For those options that can be different in
2008         different  parts  of  the pattern, the contents of the options argument         different parts of the pattern, the contents of  the  options  argument
2009         specifies their settings at the start of compilation and execution. The         specifies their settings at the start of compilation and execution. The
2010         PCRE_ANCHORED, PCRE_BSR_xxx, and PCRE_NEWLINE_xxx options can be set at         PCRE_ANCHORED, PCRE_BSR_xxx, PCRE_NEWLINE_xxx, PCRE_NO_UTF8_CHECK,  and
2011         the time of matching as well as at compile time.         PCRE_NO_START_OPTIMIZE  options  can  be set at the time of matching as
2012           well as at compile time.
2013    
2014         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,
2015         if  compilation  of  a  pattern fails, pcre_compile() returns NULL, and         if  compilation  of  a  pattern fails, pcre_compile() returns NULL, and
2016         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-
2017         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
2018         try to free it. The byte offset from the start of the  pattern  to  the         try to free it. Normally, the offset from the start of the  pattern  to
2019         character  that  was  being  processed when the error was discovered is         the data unit that was being processed when the error was discovered is
2020         placed in the variable pointed to by erroffset, which must not be NULL.         placed in the variable pointed to by erroffset, which must not be  NULL
2021         If  it  is,  an  immediate error is given. Some errors are not detected         (if  it is, an immediate error is given). However, for an invalid UTF-8
2022         until checks are carried out when the whole pattern has  been  scanned;         or UTF-16 string, the offset is that of the  first  data  unit  of  the
2023         in this case the offset is set to the end of the pattern.         failing character.
2024    
2025           Some  errors are not detected until the whole pattern has been scanned;
2026           in these cases, the offset passed back is the length  of  the  pattern.
2027           Note  that  the  offset is in data units, not characters, even in a UTF
2028           mode. It may sometimes point into the middle of a UTF-8 or UTF-16 char-
2029           acter.
2030    
2031         If  pcre_compile2()  is  used instead of pcre_compile(), and the error-         If  pcre_compile2()  is  used instead of pcre_compile(), and the error-
2032         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 1252  COMPILING A PATTERN Line 2104  COMPILING A PATTERN
2104    
2105           PCRE_DOTALL           PCRE_DOTALL
2106    
2107         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-
2108         acters,  including  those that indicate newline. Without it, a dot does         acter of any value, including one that indicates a newline. However, it
2109         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.
2110         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
2111         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
2112         newline characters, independent of the setting of this option.         be  changed within a pattern by a (?s) option setting. A negative class
2113           such as [^a] always matches newline characters, independent of the set-
2114           ting of this option.
2115    
2116           PCRE_DUPNAMES           PCRE_DUPNAMES
2117    
# Line 1269  COMPILING A PATTERN Line 2123  COMPILING A PATTERN
2123    
2124           PCRE_EXTENDED           PCRE_EXTENDED
2125    
2126         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
2127         totally ignored except when escaped or inside a character class. White-         totally ignored except when escaped or inside a character class.  White
2128         space does not include the VT character (code 11). In addition, charac-         space does not include the VT character (code 11). In addition, charac-
2129         ters between an unescaped # outside a character class and the next new-         ters between an unescaped # outside a character class and the next new-
2130         line,  inclusive,  are  also  ignored.  This is equivalent to Perl's /x         line,  inclusive,  are  also  ignored.  This is equivalent to Perl's /x
2131         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-
2132         ting.         ting.
2133    
2134         This  option  makes  it possible to include comments inside complicated         Which  characters  are  interpreted  as  newlines  is controlled by the
2135         patterns.  Note, however, that this applies only  to  data  characters.         options passed to pcre_compile() or by a special sequence at the  start
2136         Whitespace   characters  may  never  appear  within  special  character         of  the  pattern, as described in the section entitled "Newline conven-
2137         sequences in a pattern, for  example  within  the  sequence  (?(  which         tions" in the pcrepattern documentation. Note that the end of this type
2138         introduces a conditional subpattern.         of  comment  is  a  literal  newline  sequence  in  the pattern; escape
2139           sequences that happen to represent a newline do not count.
2140    
2141           This option makes it possible to include  comments  inside  complicated
2142           patterns.   Note,  however,  that this applies only to data characters.
2143           White space  characters  may  never  appear  within  special  character
2144           sequences in a pattern, for example within the sequence (?( that intro-
2145           duces a conditional subpattern.
2146    
2147           PCRE_EXTRA           PCRE_EXTRA
2148    
2149         This  option  was invented in order to turn on additional functionality         This option was invented in order to turn on  additional  functionality
2150         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
2151         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
2152         letter that has no special meaning  causes  an  error,  thus  reserving         letter  that  has  no  special  meaning causes an error, thus reserving
2153         these  combinations  for  future  expansion.  By default, as in Perl, a         these combinations for future expansion. By  default,  as  in  Perl,  a
2154         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
2155         literal. (Perl can, however, be persuaded to give an error for this, by         literal. (Perl can, however, be persuaded to give an error for this, by
2156         running it with the -w option.) There are at present no other  features         running  it with the -w option.) There are at present no other features
2157         controlled  by this option. It can also be set by a (?X) option setting         controlled by this option. It can also be set by a (?X) option  setting
2158         within a pattern.         within a pattern.
2159    
2160           PCRE_FIRSTLINE           PCRE_FIRSTLINE
2161    
2162         If this option is set, an  unanchored  pattern  is  required  to  match         If  this  option  is  set,  an  unanchored pattern is required to match
2163         before  or  at  the  first  newline  in  the subject string, though the         before or at the first  newline  in  the  subject  string,  though  the
2164         matched text may continue over the newline.         matched text may continue over the newline.
2165    
2166           PCRE_JAVASCRIPT_COMPAT           PCRE_JAVASCRIPT_COMPAT
2167    
2168         If this option is set, PCRE's behaviour is changed in some ways so that         If this option is set, PCRE's behaviour is changed in some ways so that
2169         it  is  compatible with JavaScript rather than Perl. The changes are as         it is compatible with JavaScript rather than Perl. The changes  are  as
2170         follows:         follows:
2171    
2172         (1) A lone closing square bracket in a pattern  causes  a  compile-time         (1)  A  lone  closing square bracket in a pattern causes a compile-time
2173         error,  because this is illegal in JavaScript (by default it is treated         error, because this is illegal in JavaScript (by default it is  treated
2174         as a data character). Thus, the pattern AB]CD becomes illegal when this         as a data character). Thus, the pattern AB]CD becomes illegal when this
2175         option is set.         option is set.
2176    
2177         (2)  At run time, a back reference to an unset subpattern group matches         (2) At run time, a back reference to an unset subpattern group  matches
2178         an empty string (by default this causes the current  matching  alterna-         an  empty  string (by default this causes the current matching alterna-
2179         tive  to  fail). A pattern such as (\1)(a) succeeds when this option is         tive to fail). A pattern such as (\1)(a) succeeds when this  option  is
2180         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
2181         default, for Perl compatibility.         default, for Perl compatibility.
2182    
2183           (3) \U matches an upper case "U" character; by default \U causes a com-
2184           pile time error (Perl uses \U to upper case subsequent characters).
2185    
2186           (4) \u matches a lower case "u" character unless it is followed by four
2187           hexadecimal digits, in which case the hexadecimal  number  defines  the
2188           code  point  to match. By default, \u causes a compile time error (Perl
2189           uses it to upper case the following character).
2190    
2191           (5) \x matches a lower case "x" character unless it is followed by  two
2192           hexadecimal  digits,  in  which case the hexadecimal number defines the
2193           code point to match. By default, as in Perl, a  hexadecimal  number  is
2194           always expected after \x, but it may have zero, one, or two digits (so,
2195           for example, \xz matches a binary zero character followed by z).
2196    
2197           PCRE_MULTILINE           PCRE_MULTILINE
2198    
2199         By  default,  PCRE  treats the subject string as consisting of a single         By default, for the purposes of matching "start of line"  and  "end  of
2200         line of characters (even if it actually contains newlines). The  "start         line", PCRE treats the subject string as consisting of a single line of
2201         of  line"  metacharacter  (^)  matches only at the start of the string,         characters, even if it actually contains newlines. The "start of  line"
2202         while the "end of line" metacharacter ($) matches only at  the  end  of         metacharacter (^) matches only at the start of the string, and the "end
2203         the string, or before a terminating newline (unless PCRE_DOLLAR_ENDONLY         of line" metacharacter ($) matches only at the end of  the  string,  or
2204         is set). This is the same as Perl.         before  a terminating newline (except when PCRE_DOLLAR_ENDONLY is set).
2205           Note, however, that unless PCRE_DOTALL  is  set,  the  "any  character"
2206           metacharacter  (.)  does not match at a newline. This behaviour (for ^,
2207           $, and dot) is the same as Perl.
2208    
2209         When PCRE_MULTILINE it is set, the "start of line" and  "end  of  line"         When PCRE_MULTILINE it is set, the "start of line" and  "end  of  line"
2210         constructs  match  immediately following or immediately before internal         constructs  match  immediately following or immediately before internal
# Line 1336  COMPILING A PATTERN Line 2214  COMPILING A PATTERN
2214         lines  in  a  subject string, or no occurrences of ^ or $ in a pattern,         lines  in  a  subject string, or no occurrences of ^ or $ in a pattern,
2215         setting PCRE_MULTILINE has no effect.         setting PCRE_MULTILINE has no effect.
2216    
2217             PCRE_NEVER_UTF
2218    
2219           This option locks out interpretation of the pattern as UTF-8 (or UTF-16
2220           or  UTF-32  in the 16-bit and 32-bit libraries). In particular, it pre-
2221           vents the creator of the pattern from switching to  UTF  interpretation
2222           by starting the pattern with (*UTF). This may be useful in applications
2223           that  process  patterns  from  external  sources.  The  combination  of
2224           PCRE_UTF8 and PCRE_NEVER_UTF also causes an error.
2225    
2226           PCRE_NEWLINE_CR           PCRE_NEWLINE_CR
2227           PCRE_NEWLINE_LF           PCRE_NEWLINE_LF
2228           PCRE_NEWLINE_CRLF           PCRE_NEWLINE_CRLF
2229           PCRE_NEWLINE_ANYCRLF           PCRE_NEWLINE_ANYCRLF
2230           PCRE_NEWLINE_ANY           PCRE_NEWLINE_ANY
2231    
2232         These options override the default newline definition that  was  chosen         These  options  override the default newline definition that was chosen
2233         when  PCRE  was built. Setting the first or the second specifies that a         when PCRE was built. Setting the first or the second specifies  that  a
2234         newline is indicated by a single character (CR  or  LF,  respectively).         newline  is  indicated  by a single character (CR or LF, respectively).
2235         Setting  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the         Setting PCRE_NEWLINE_CRLF specifies that a newline is indicated by  the
2236         two-character CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF  specifies         two-character  CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF specifies
2237         that any of the three preceding sequences should be recognized. Setting         that any of the three preceding sequences should be recognized. Setting
2238         PCRE_NEWLINE_ANY specifies that any Unicode newline sequence should  be         PCRE_NEWLINE_ANY  specifies that any Unicode newline sequence should be
2239         recognized. The Unicode newline sequences are the three just mentioned,         recognized.
2240         plus the single characters VT (vertical  tab,  U+000B),  FF  (formfeed,  
2241         U+000C),  NEL  (next line, U+0085), LS (line separator, U+2028), and PS         In an ASCII/Unicode environment, the Unicode newline sequences are  the
2242         (paragraph separator, U+2029). The last  two  are  recognized  only  in         three  just  mentioned,  plus  the  single characters VT (vertical tab,
2243         UTF-8 mode.         U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line sep-
2244           arator,  U+2028),  and  PS (paragraph separator, U+2029). For the 8-bit
2245           library, the last two are recognized only in UTF-8 mode.
2246    
2247           When PCRE is compiled to run in an EBCDIC (mainframe) environment,  the
2248           code for CR is 0x0d, the same as ASCII. However, the character code for
2249           LF is normally 0x15, though in some EBCDIC environments 0x25  is  used.
2250           Whichever  of  these  is  not LF is made to correspond to Unicode's NEL
2251           character. EBCDIC codes are all less than 256. For  more  details,  see
2252           the pcrebuild documentation.
2253    
2254         The  newline  setting  in  the  options  word  uses three bits that are         The  newline  setting  in  the  options  word  uses three bits that are
2255         treated as a number, giving eight possibilities. Currently only six are         treated as a number, giving eight possibilities. Currently only six are
# Line 1363  COMPILING A PATTERN Line 2259  COMPILING A PATTERN
2259         PCRE_NEWLINE_CRLF, but other combinations may yield unused numbers  and         PCRE_NEWLINE_CRLF, but other combinations may yield unused numbers  and
2260         cause an error.         cause an error.
2261    
2262         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
2263         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
2264         character  class  is  encountered.  This indicates a comment that lasts         characters,  and so are ignored in this mode. Also, an unescaped # out-
2265         until after the next line break sequence. In other circumstances,  line         side a character class indicates a comment that lasts until  after  the
2266         break   sequences   are   treated  as  literal  data,  except  that  in         next  line break sequence. In other circumstances, line break sequences
2267         PCRE_EXTENDED mode, both CR and LF are treated as whitespace characters         in patterns are treated as literal data.
        and are therefore ignored.  
2268    
2269         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
2270         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.
# Line 1377  COMPILING A PATTERN Line 2272  COMPILING A PATTERN
2272           PCRE_NO_AUTO_CAPTURE           PCRE_NO_AUTO_CAPTURE
2273    
2274         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-
2275         theses  in the pattern. Any opening parenthesis that is not followed by         theses in the pattern. Any opening parenthesis that is not followed  by
2276         ? behaves as if it were followed by ?: but named parentheses can  still         ?  behaves as if it were followed by ?: but named parentheses can still
2277         be  used  for  capturing  (and  they acquire numbers in the usual way).         be used for capturing (and they acquire  numbers  in  the  usual  way).
2278         There is no equivalent of this option in Perl.         There is no equivalent of this option in Perl.
2279    
2280             PCRE_NO_START_OPTIMIZE
2281    
2282           This  is an option that acts at matching time; that is, it is really an
2283           option for pcre_exec() or pcre_dfa_exec(). If  it  is  set  at  compile
2284           time,  it is remembered with the compiled pattern and assumed at match-
2285           ing time. This is necessary if you want to use JIT  execution,  because
2286           the  JIT  compiler needs to know whether or not this option is set. For
2287           details see the discussion of PCRE_NO_START_OPTIMIZE below.
2288    
2289           PCRE_UCP           PCRE_UCP
2290    
2291         This option changes the way PCRE processes \b, \d, \s, \w, and some  of         This option changes the way PCRE processes \B, \b, \D, \d, \S, \s,  \W,
2292         the POSIX character classes. By default, only ASCII characters are rec-         \w,  and  some  of  the POSIX character classes. By default, only ASCII
2293         ognized, but if PCRE_UCP is set, Unicode properties are used instead to         characters are recognized, but if PCRE_UCP is set,  Unicode  properties
2294         classify  characters.  More details are given in the section on generic         are  used instead to classify characters. More details are given in the
2295         character types in the pcrepattern page. If you set PCRE_UCP,  matching         section on generic character types in the pcrepattern page. If you  set
2296         one  of the items it affects takes much longer. The option is available         PCRE_UCP,  matching  one of the items it affects takes much longer. The
2297         only if PCRE has been compiled with Unicode property support.         option is available only if PCRE has been compiled with  Unicode  prop-
2298           erty support.
2299    
2300           PCRE_UNGREEDY           PCRE_UNGREEDY
2301    
2302         This option inverts the "greediness" of the quantifiers  so  that  they         This  option  inverts  the "greediness" of the quantifiers so that they
2303         are  not greedy by default, but become greedy if followed by "?". It is         are not greedy by default, but become greedy if followed by "?". It  is
2304         not compatible with Perl. It can also be set by a (?U)  option  setting         not  compatible  with Perl. It can also be set by a (?U) option setting
2305         within the pattern.         within the pattern.
2306    
2307           PCRE_UTF8           PCRE_UTF8
2308    
2309         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
2310         strings of UTF-8 characters instead of single-byte  character  strings.         strings of UTF-8 characters instead of single-byte strings. However, it
2311         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,
2312         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
2313         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.  
2314    
2315           PCRE_NO_UTF8_CHECK           PCRE_NO_UTF8_CHECK
2316    
2317         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
2318         automatically  checked.  There  is  a  discussion about the validity of         automatically  checked.  There  is  a  discussion about the validity of
2319         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
2320         bytes  is  found,  pcre_compile() returns an error. If you already know         found,  pcre_compile()  returns an error. If you already know that your
2321         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-
2322         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
2323         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
2324         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
2325         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
2326         UTF-8 validity checking of subject strings.         checking  of  subject strings only. If the same string is being matched
2327           many times, the option can be safely set for the second and  subsequent
2328           matchings to improve performance.
2329    
2330    
2331  COMPILATION ERROR CODES  COMPILATION ERROR CODES
2332    
2333         The  following  table  lists  the  error  codes than may be returned by         The  following  table  lists  the  error  codes than may be returned by
2334         pcre_compile2(), along with the error messages that may be returned  by         pcre_compile2(), along with the error messages that may be returned  by
2335         both  compiling functions. As PCRE has developed, some error codes have         both  compiling  functions.  Note  that error messages are always 8-bit
2336         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,
2337           some  error codes have fallen out of use. To avoid confusion, they have
2338           not been re-used.
2339    
2340            0  no error            0  no error
2341            1  \ at end of pattern            1  \ at end of pattern
# Line 1461  COMPILATION ERROR CODES Line 2369  COMPILATION ERROR CODES
2369           29  (?R or (?[+-]digits must be followed by )           29  (?R or (?[+-]digits must be followed by )
2370           30  unknown POSIX class name           30  unknown POSIX class name
2371           31  POSIX collating elements are not supported           31  POSIX collating elements are not supported
2372           32  this version of PCRE is not compiled with PCRE_UTF8 support           32  this version of PCRE is compiled without UTF support
2373           33  [this code is not in use]           33  [this code is not in use]
2374           34  character value in \x{...} sequence is too large           34  character value in \x{...} sequence is too large
2375           35  invalid condition (?(0)           35  invalid condition (?(0)
2376           36  \C not allowed in lookbehind assertion           36  \C not allowed in lookbehind assertion
2377           37  PCRE does not support \L, \l, \N, \U, or \u           37  PCRE does not support \L, \l, \N{name}, \U, or \u
2378           38  number after (?C is > 255           38  number after (?C is > 255
2379           39  closing ) for (?C expected           39  closing ) for (?C expected
2380           40  recursive call could loop indefinitely           40  recursive call could loop indefinitely
2381           41  unrecognized character after (?P           41  unrecognized character after (?P
2382           42  syntax error in subpattern name (missing terminator)           42  syntax error in subpattern name (missing terminator)
2383           43  two named subpatterns have the same name           43  two named subpatterns have the same name
2384           44  invalid UTF-8 string           44  invalid UTF-8 string (specifically UTF-8)
2385           45  support for \P, \p, and \X has not been compiled           45  support for \P, \p, and \X has not been compiled
2386           46  malformed \P or \p sequence           46  malformed \P or \p sequence
2387           47  unknown property name after \P or \p           47  unknown property name after \P or \p
2388           48  subpattern name is too long (maximum 32 characters)           48  subpattern name is too long (maximum 32 characters)
2389           49  too many named subpatterns (maximum 10000)           49  too many named subpatterns (maximum 10000)
2390           50  [this code is not in use]           50  [this code is not in use]
2391           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
2392           52  internal error: overran compiling workspace           52  internal error: overran compiling workspace
2393           53  internal error: previously-checked referenced subpattern           53  internal error: previously-checked referenced subpattern
2394                 not found                 not found
# Line 1491  COMPILATION ERROR CODES Line 2399  COMPILATION ERROR CODES
2399                 name/number or by a plain number                 name/number or by a plain number
2400           58  a numbered reference must not be zero           58  a numbered reference must not be zero
2401           59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)           59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
2402           60  (*VERB) not recognized           60  (*VERB) not recognized or malformed
2403           61  number is too big           61  number is too big
2404           62  subpattern name expected           62  subpattern name expected
2405           63  digit expected after (?+           63  digit expected after (?+
# Line 1499  COMPILATION ERROR CODES Line 2407  COMPILATION ERROR CODES
2407           65  different names for subpatterns of the same number are           65  different names for subpatterns of the same number are
2408                 not allowed                 not allowed
2409           66  (*MARK) must have an argument           66  (*MARK) must have an argument
2410           67  this version of PCRE is not compiled with PCRE_UCP support           67  this version of PCRE is not compiled with Unicode property
2411                   support
2412             68  \c must be followed by an ASCII character
2413             69  \k is not followed by a braced, angle-bracketed, or quoted name
2414             70  internal error: unknown opcode in find_fixedlength()
2415             71  \N is not supported in a class
2416             72  too many forward references
2417             73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
2418             74  invalid UTF-16 string (specifically UTF-16)
2419             75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
2420             76  character value in \u.... sequence is too large
2421             77  invalid UTF-32 string (specifically UTF-32)
2422    
2423         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
2424         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 1524  STUDYING A PATTERN Line 2443  STUDYING A PATTERN
2443         passed; these are described below in the section on matching a pattern.         passed; these are described below in the section on matching a pattern.
2444    
2445         If studying the  pattern  does  not  produce  any  useful  information,         If studying the  pattern  does  not  produce  any  useful  information,
2446         pcre_study() returns NULL. In that circumstance, if the calling program         pcre_study()  returns  NULL  by  default.  In that circumstance, if the
2447         wants  to  pass  any  of   the   other   fields   to   pcre_exec()   or         calling program wants to pass any of the other fields to pcre_exec() or
2448         pcre_dfa_exec(), it must set up its own pcre_extra block.         pcre_dfa_exec(),  it  must set up its own pcre_extra block. However, if
2449           pcre_study() is called  with  the  PCRE_STUDY_EXTRA_NEEDED  option,  it
2450         The  second  argument of pcre_study() contains option bits. At present,         returns a pcre_extra block even if studying did not find any additional
2451         no options are defined, and this argument should always be zero.         information. It may still return NULL, however, if an error  occurs  in
2452           pcre_study().
2453    
2454           The  second  argument  of  pcre_study() contains option bits. There are
2455           three further options in addition to PCRE_STUDY_EXTRA_NEEDED:
2456    
2457             PCRE_STUDY_JIT_COMPILE
2458             PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
2459             PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
2460    
2461           If any of these are set, and the just-in-time  compiler  is  available,
2462           the  pattern  is  further compiled into machine code that executes much
2463           faster than the pcre_exec()  interpretive  matching  function.  If  the
2464           just-in-time  compiler is not available, these options are ignored. All
2465           undefined bits in the options argument must be zero.
2466    
2467           JIT compilation is a heavyweight optimization. It can  take  some  time
2468           for  patterns  to  be analyzed, and for one-off matches and simple pat-
2469           terns the benefit of faster execution might be offset by a much  slower
2470           study time.  Not all patterns can be optimized by the JIT compiler. For
2471           those that cannot be handled, matching automatically falls back to  the
2472           pcre_exec()  interpreter.  For more details, see the pcrejit documenta-
2473           tion.
2474    
2475         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.
2476         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 1538  STUDYING A PATTERN Line 2479  STUDYING A PATTERN
2479         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
2480         after calling pcre_study(), to be sure that it has run successfully.         after calling pcre_study(), to be sure that it has run successfully.
2481    
2482         This is a typical call to pcre_study():         When  you are finished with a pattern, you can free the memory used for
2483           the study data by calling pcre_free_study(). This function was added to
2484           the  API  for  release  8.20. For earlier versions, the memory could be
2485           freed with pcre_free(), just like the pattern itself. This  will  still
2486           work  in  cases where JIT optimization is not used, but it is advisable
2487           to change to the new function when convenient.
2488    
2489           pcre_extra *pe;         This is a typical way in which pcre_study() is used (except that  in  a
2490           pe = pcre_study(         real application there should be tests for errors):
2491    
2492             int rc;
2493             pcre *re;
2494             pcre_extra *sd;
2495             re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
2496             sd = pcre_study(
2497             re,             /* result of pcre_compile() */             re,             /* result of pcre_compile() */
2498             0,              /* no options exist */             0,              /* no options */
2499             &error);        /* set to NULL or points to a message */             &error);        /* set to NULL or points to a message */
2500             rc = pcre_exec(   /* see below for details of pcre_exec() options */
2501               re, sd, "subject", 7, 0, 0, ovector, 30);
2502             ...
2503             pcre_free_study(sd);
2504             pcre_free(re);
2505    
2506         Studying a pattern does two things: first, a lower bound for the length         Studying a pattern does two things: first, a lower bound for the length
2507         of subject string that is needed to match the pattern is computed. This         of subject string that is needed to match the pattern is computed. This
2508         does not mean that there are any strings of that length that match, but         does not mean that there are any strings of that length that match, but
2509         it does guarantee that no shorter strings match. The value is  used  by         it does guarantee that no shorter strings match. The value is  used  to
2510         pcre_exec()  and  pcre_dfa_exec()  to  avoid  wasting time by trying to         avoid wasting time by trying to match strings that are shorter than the
2511         match strings that are shorter than the lower bound. You can  find  out         lower bound. You can find out the value in a calling  program  via  the
2512         the value in a calling program via the pcre_fullinfo() function.         pcre_fullinfo() function.
2513    
2514         Studying a pattern is also useful for non-anchored patterns that do not         Studying a pattern is also useful for non-anchored patterns that do not
2515         have a single fixed starting character. A bitmap of  possible  starting         have a single fixed starting character. A bitmap of  possible  starting
2516         bytes  is  created. This speeds up finding a position in the subject at         bytes  is  created. This speeds up finding a position in the subject at
2517         which to start matching.         which to start matching. (In 16-bit mode, the bitmap is used for 16-bit
2518           values  less  than  256.  In 32-bit mode, the bitmap is used for 32-bit
2519           values less than 256.)
2520    
2521           These two optimizations apply to both pcre_exec() and  pcre_dfa_exec(),
2522           and  the  information  is also used by the JIT compiler.  The optimiza-
2523           tions can be disabled by  setting  the  PCRE_NO_START_OPTIMIZE  option.
2524           You  might want to do this if your pattern contains callouts or (*MARK)
2525           and you want to make use of these facilities in  cases  where  matching
2526           fails.
2527    
2528           PCRE_NO_START_OPTIMIZE  can be specified at either compile time or exe-
2529           cution  time.  However,  if   PCRE_NO_START_OPTIMIZE   is   passed   to
2530           pcre_exec(), (that is, after any JIT compilation has happened) JIT exe-
2531           cution is disabled. For JIT execution to work with  PCRE_NO_START_OPTI-
2532           MIZE, the option must be set at compile time.
2533    
2534         The two optimizations just described can be  disabled  by  setting  the         There is a longer discussion of PCRE_NO_START_OPTIMIZE below.
        PCRE_NO_START_OPTIMIZE    option    when    calling    pcre_exec()   or  
        pcre_dfa_exec(). You might want to do this  if  your  pattern  contains  
        callouts,  or  make  use of (*MARK), and you make use of these in cases  
        where matching fails.  See  the  discussion  of  PCRE_NO_START_OPTIMIZE  
        below.  
2535    
2536    
2537  LOCALE SUPPORT  LOCALE SUPPORT
# Line 1631  INFORMATION ABOUT A PATTERN Line 2598  INFORMATION ABOUT A PATTERN
2598              int what, void *where);              int what, void *where);
2599    
2600         The pcre_fullinfo() function returns information about a compiled  pat-         The pcre_fullinfo() function returns information about a compiled  pat-
2601         tern. It replaces the obsolete pcre_info() function, which is neverthe-         tern.  It replaces the pcre_info() function, which was removed from the
2602         less retained for backwards compability (and is documented below).         library at version 8.30, after more than 10 years of obsolescence.
2603    
2604         The first argument for pcre_fullinfo() is a  pointer  to  the  compiled         The first argument for pcre_fullinfo() is a  pointer  to  the  compiled
2605         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 1641  INFORMATION ABOUT A PATTERN Line 2608  INFORMATION ABOUT A PATTERN
2608         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
2609         success, or one of the following negative numbers:         success, or one of the following negative numbers:
2610    
2611           PCRE_ERROR_NULL       the argument code was NULL           PCRE_ERROR_NULL           the argument code was NULL
2612                                 the argument where was NULL                                     the argument where was NULL
2613           PCRE_ERROR_BADMAGIC   the "magic number" was not found           PCRE_ERROR_BADMAGIC       the "magic number" was not found
2614           PCRE_ERROR_BADOPTION  the value of what was invalid           PCRE_ERROR_BADENDIANNESS  the pattern was compiled with different
2615                                       endianness
2616             PCRE_ERROR_BADOPTION      the value of what was invalid
2617             PCRE_ERROR_UNSET          the requested field is not set
2618    
2619         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
2620         an simple check against passing an arbitrary memory pointer. Here is  a         an simple check against passing an arbitrary memory pointer. The  endi-
2621         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
2622         pattern:         different host. Here is a typical call of  pcre_fullinfo(),  to  obtain
2623           the length of the compiled pattern:
2624    
2625           int rc;           int rc;
2626           size_t length;           size_t length;
2627           rc = pcre_fullinfo(           rc = pcre_fullinfo(
2628             re,               /* result of pcre_compile() */             re,               /* result of pcre_compile() */
2629             pe,               /* result of pcre_study(), or NULL */             sd,               /* result of pcre_study(), or NULL */
2630             PCRE_INFO_SIZE,   /* what is required */             PCRE_INFO_SIZE,   /* what is required */
2631             &length);         /* where to put the data */             &length);         /* where to put the data */
2632    
2633         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
2634         are as follows:         are as follows:
2635    
2636           PCRE_INFO_BACKREFMAX           PCRE_INFO_BACKREFMAX
2637    
2638         Return  the  number  of  the highest back reference in the pattern. The         Return the number of the highest back reference  in  the  pattern.  The
2639         fourth argument should point to an int variable. Zero  is  returned  if         fourth  argument  should  point to an int variable. Zero is returned if
2640         there are no back references.         there are no back references.
2641    
2642           PCRE_INFO_CAPTURECOUNT           PCRE_INFO_CAPTURECOUNT
2643    
2644         Return  the  number of capturing subpatterns in the pattern. The fourth         Return the number of capturing subpatterns in the pattern.  The  fourth
2645         argument should point to an int variable.         argument should point to an int variable.
2646    
2647           PCRE_INFO_DEFAULT_TABLES           PCRE_INFO_DEFAULT_TABLES
2648    
2649         Return a pointer to the internal default character tables within  PCRE.         Return  a pointer to the internal default character tables within PCRE.
2650         The  fourth  argument should point to an unsigned char * variable. This         The fourth argument should point to an unsigned char *  variable.  This
2651         information call is provided for internal use by the pcre_study() func-         information call is provided for internal use by the pcre_study() func-
2652         tion.  External  callers  can  cause PCRE to use its internal tables by         tion. External callers can cause PCRE to use  its  internal  tables  by
2653         passing a NULL table pointer.         passing a NULL table pointer.
2654    
2655           PCRE_INFO_FIRSTBYTE           PCRE_INFO_FIRSTBYTE
2656    
2657         Return information about the first byte of any matched  string,  for  a         Return information about the first data unit of any matched string, for
2658         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
2659         able. (This option used to be called PCRE_INFO_FIRSTCHAR; the old  name         library,  where data units are bytes.) The fourth argument should point
2660         is still recognized for backwards compatibility.)         to an int variable.
2661    
2662           If there is a fixed first value, for example, the  letter  "c"  from  a
2663           pattern  such  as (cat|cow|coyote), its value is returned. In the 8-bit
2664           library, the value is always less than 256. In the 16-bit  library  the
2665           value can be up to 0xffff. In the 32-bit library the value can be up to
2666           0x10ffff.
2667    
2668         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  
2669    
2670         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
2671         branch starts with "^", or         branch starts with "^", or
# Line 1701  INFORMATION ABOUT A PATTERN Line 2677  INFORMATION ABOUT A PATTERN
2677         of  a  subject string or after any newline within the string. Otherwise         of  a  subject string or after any newline within the string. Otherwise
2678         -2 is returned. For anchored patterns, -2 is returned.         -2 is returned. For anchored patterns, -2 is returned.
2679    
2680           Since for the 32-bit library using the non-UTF-32 mode,  this  function
2681           is  unable to return the full 32-bit range of the character, this value
2682           is   deprecated;   instead   the   PCRE_INFO_FIRSTCHARACTERFLAGS    and
2683           PCRE_INFO_FIRSTCHARACTER values should be used.
2684    
2685           PCRE_INFO_FIRSTTABLE           PCRE_INFO_FIRSTTABLE
2686    
2687         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
2688         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
2689         matching string, a pointer to the table is returned. Otherwise NULL  is         in  any  matching string, a pointer to the table is returned. Otherwise
2690         returned.  The fourth argument should point to an unsigned char * vari-         NULL is returned. The fourth argument should point to an unsigned  char
2691         able.         * variable.
2692    
2693           PCRE_INFO_HASCRORLF           PCRE_INFO_HASCRORLF
2694    
2695         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
2696         characters,  otherwise  0.  The  fourth argument should point to an int         characters, otherwise 0. The fourth argument should  point  to  an  int
2697         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
2698         \r or \n.         \r or \n.
2699    
2700           PCRE_INFO_JCHANGED           PCRE_INFO_JCHANGED
2701    
2702         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,
2703         otherwise 0. The fourth argument should point to an int variable.  (?J)         otherwise  0. The fourth argument should point to an int variable. (?J)
2704         and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.         and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
2705    
2706             PCRE_INFO_JIT
2707    
2708           Return 1 if the pattern was studied with one of the  JIT  options,  and
2709           just-in-time compiling was successful. The fourth argument should point
2710           to an int variable. A return value of 0 means that JIT support  is  not
2711           available  in this version of PCRE, or that the pattern was not studied
2712           with a JIT option, or that the JIT compiler could not handle this  par-
2713           ticular  pattern. See the pcrejit documentation for details of what can
2714           and cannot be handled.
2715    
2716             PCRE_INFO_JITSIZE
2717    
2718           If the pattern was successfully studied with a JIT option,  return  the
2719           size  of the JIT compiled code, otherwise return zero. The fourth argu-
2720           ment should point to a size_t variable.
2721    
2722           PCRE_INFO_LASTLITERAL           PCRE_INFO_LASTLITERAL
2723    
2724         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
2725         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
2726         recorded. The fourth argument should point to an int variable. If there         recorded. The fourth argument should point to an int variable. If there
2727         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
2728         byte  is  recorded only if it follows something of variable length. For         value is recorded only if it follows something of variable length.  For
2729         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
2730         /^a\dz\d/ the returned value is -1.         /^a\dz\d/ the returned value is -1.
2731    
2732           Since for the 32-bit library using the non-UTF-32 mode,  this  function
2733           is  unable to return the full 32-bit range of the character, this value
2734           is   deprecated;   instead    the    PCRE_INFO_REQUIREDCHARFLAGS    and
2735           PCRE_INFO_REQUIREDCHAR values should be used.
2736    
2737             PCRE_INFO_MATCHLIMIT
2738    
2739           If  the  pattern  set  a  match  limit by including an item of the form
2740           (*LIMIT_MATCH=nnnn) at the start, the value  is  returned.  The  fourth
2741           argument  should  point to an unsigned 32-bit integer. If no such value
2742           has  been  set,  the  call  to  pcre_fullinfo()   returns   the   error
2743           PCRE_ERROR_UNSET.
2744    
2745             PCRE_INFO_MAXLOOKBEHIND
2746    
2747           Return  the  number  of  characters  (NB not data units) in the longest
2748           lookbehind assertion in the pattern. This information  is  useful  when
2749           doing  multi-segment  matching  using  the partial matching facilities.
2750           Note that the simple assertions \b and \B require a one-character look-
2751           behind.  \A  also  registers a one-character lookbehind, though it does
2752           not actually inspect the previous character. This is to ensure that  at
2753           least one character from the old segment is retained when a new segment
2754           is processed. Otherwise, if there are no lookbehinds in the pattern, \A
2755           might match incorrectly at the start of a new segment.
2756    
2757           PCRE_INFO_MINLENGTH           PCRE_INFO_MINLENGTH
2758    
2759         If  the  pattern  was studied and a minimum length for matching subject         If  the  pattern  was studied and a minimum length for matching subject
2760         strings was computed, its value is  returned.  Otherwise  the  returned         strings was computed, its value is  returned.  Otherwise  the  returned
2761         value  is  -1. The value is a number of characters, not bytes (this may         value is -1. The value is a number of characters, which in UTF mode may
2762         be relevant in UTF-8 mode). The fourth argument should point to an  int         be different from the number of data units. The fourth argument  should
2763         variable.  A  non-negative  value is a lower bound to the length of any         point  to an int variable. A non-negative value is a lower bound to the
2764         matching string. There may not be any strings of that  length  that  do         length of any matching string. There may not be  any  strings  of  that
2765         actually match, but every string that does match is at least that long.         length  that  do actually match, but every string that does match is at
2766           least that long.
2767    
2768           PCRE_INFO_NAMECOUNT           PCRE_INFO_NAMECOUNT
2769           PCRE_INFO_NAMEENTRYSIZE           PCRE_INFO_NAMEENTRYSIZE
2770           PCRE_INFO_NAMETABLE           PCRE_INFO_NAMETABLE
2771    
2772         PCRE  supports the use of named as well as numbered capturing parenthe-         PCRE supports the use of named as well as numbered capturing  parenthe-
2773         ses. The names are just an additional way of identifying the  parenthe-         ses.  The names are just an additional way of identifying the parenthe-
2774         ses, which still acquire numbers. Several convenience functions such as         ses, which still acquire numbers. Several convenience functions such as
2775         pcre_get_named_substring() are provided for  extracting  captured  sub-         pcre_get_named_substring()  are  provided  for extracting captured sub-
2776         strings  by  name. It is also possible to extract the data directly, by         strings by name. It is also possible to extract the data  directly,  by
2777         first converting the name to a number in order to  access  the  correct         first  converting  the  name to a number in order to access the correct
2778         pointers in the output vector (described with pcre_exec() below). To do         pointers in the output vector (described with pcre_exec() below). To do
2779         the conversion, you need  to  use  the  name-to-number  map,  which  is         the  conversion,  you  need  to  use  the  name-to-number map, which is
2780         described by these three values.         described by these three values.
2781    
2782         The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT         The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT
2783         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size
2784         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
2785         depends on the length of the longest name. PCRE_INFO_NAMETABLE  returns         depends  on the length of the longest name. PCRE_INFO_NAMETABLE returns
2786         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
2787         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-
2788         sis,  most  significant byte first. The rest of the entry is the corre-         ber of the capturing parenthesis, most significant byte first.  In  the
2789         sponding name, zero terminated.         16-bit  library,  the pointer points to 16-bit data units, the first of
2790           which contains the parenthesis  number.  In  the  32-bit  library,  the
2791           pointer  points  to  32-bit data units, the first of which contains the
2792           parenthesis number. The rest of the entry is  the  corresponding  name,
2793           zero terminated.
2794    
2795         The names are in alphabetical order. Duplicate names may appear if  (?|         The  names are in alphabetical order. Duplicate names may appear if (?|
2796         is used to create multiple groups with the same number, as described in         is used to create multiple groups with the same number, as described in
2797         the section on duplicate subpattern numbers in  the  pcrepattern  page.         the  section  on  duplicate subpattern numbers in the pcrepattern page.
2798         Duplicate  names  for  subpatterns with different numbers are permitted         Duplicate names for subpatterns with different  numbers  are  permitted
2799         only if PCRE_DUPNAMES is set. In all cases  of  duplicate  names,  they         only  if  PCRE_DUPNAMES  is  set. In all cases of duplicate names, they
2800         appear  in  the table in the order in which they were found in the pat-         appear in the table in the order in which they were found in  the  pat-
2801         tern. In the absence of (?| this is the  order  of  increasing  number;         tern.  In  the  absence  of (?| this is the order of increasing number;
2802         when (?| is used this is not necessarily the case because later subpat-         when (?| is used this is not necessarily the case because later subpat-
2803         terns may have lower numbers.         terns may have lower numbers.
2804    
2805         As a simple example of the name/number table,  consider  the  following         As  a  simple  example of the name/number table, consider the following
2806         pattern  (assume  PCRE_EXTENDED is set, so white space - including new-         pattern after compilation by the 8-bit library (assume PCRE_EXTENDED is
2807         lines - is ignored):         set, so white space - including newlines - is ignored):
2808    
2809           (?<date> (?<year>(\d\d)?\d\d) -           (?<date> (?<year>(\d\d)?\d\d) -
2810           (?<month>\d\d) - (?<day>\d\d) )           (?<month>\d\d) - (?<day>\d\d) )
2811    
2812         There are four named subpatterns, so the table has  four  entries,  and         There  are  four  named subpatterns, so the table has four entries, and
2813         each  entry  in the table is eight bytes long. The table is as follows,         each entry in the table is eight bytes long. The table is  as  follows,
2814         with non-printing bytes shows in hexadecimal, and undefined bytes shown         with non-printing bytes shows in hexadecimal, and undefined bytes shown
2815         as ??:         as ??:
2816    
# Line 1792  INFORMATION ABOUT A PATTERN Line 2819  INFORMATION ABOUT A PATTERN
2819           00 04 m  o  n  t  h  00           00 04 m  o  n  t  h  00
2820           00 02 y  e  a  r  00 ??           00 02 y  e  a  r  00 ??
2821    
2822         When  writing  code  to  extract  data from named subpatterns using the         When writing code to extract data  from  named  subpatterns  using  the
2823         name-to-number map, remember that the length of the entries  is  likely         name-to-number  map,  remember that the length of the entries is likely
2824         to be different for each compiled pattern.         to be different for each compiled pattern.
2825    
2826           PCRE_INFO_OKPARTIAL           PCRE_INFO_OKPARTIAL
2827    
2828         Return  1  if  the  pattern  can  be  used  for  partial  matching with         Return 1  if  the  pattern  can  be  used  for  partial  matching  with
2829         pcre_exec(), otherwise 0. The fourth argument should point  to  an  int         pcre_exec(),  otherwise  0.  The fourth argument should point to an int
2830         variable.  From  release  8.00,  this  always  returns  1,  because the         variable. From  release  8.00,  this  always  returns  1,  because  the
2831         restrictions that previously applied  to  partial  matching  have  been         restrictions  that  previously  applied  to  partial matching have been
2832         lifted.  The  pcrepartial documentation gives details of partial match-         lifted. The pcrepartial documentation gives details of  partial  match-
2833         ing.         ing.
2834    
2835           PCRE_INFO_OPTIONS           PCRE_INFO_OPTIONS
2836    
2837         Return a copy of the options with which the pattern was  compiled.  The         Return  a  copy of the options with which the pattern was compiled. The
2838         fourth  argument  should  point to an unsigned long int variable. These         fourth argument should point to an unsigned long  int  variable.  These
2839         option bits are those specified in the call to pcre_compile(), modified         option bits are those specified in the call to pcre_compile(), modified
2840         by any top-level option settings at the start of the pattern itself. In         by any top-level option settings at the start of the pattern itself. In
2841         other words, they are the options that will be in force  when  matching         other  words,  they are the options that will be in force when matching
2842         starts.  For  example, if the pattern /(?im)abc(?-i)d/ is compiled with         starts. For example, if the pattern /(?im)abc(?-i)d/ is  compiled  with
2843         the PCRE_EXTENDED option, the result is PCRE_CASELESS,  PCRE_MULTILINE,         the  PCRE_EXTENDED option, the result is PCRE_CASELESS, PCRE_MULTILINE,
2844         and PCRE_EXTENDED.         and PCRE_EXTENDED.
2845    
2846         A  pattern  is  automatically  anchored by PCRE if all of its top-level         A pattern is automatically anchored by PCRE if  all  of  its  top-level
2847         alternatives begin with one of the following:         alternatives begin with one of the following:
2848    
2849           ^     unless PCRE_MULTILINE is set           ^     unless PCRE_MULTILINE is set
# Line 1828  INFORMATION ABOUT A PATTERN Line 2855  INFORMATION ABOUT A PATTERN
2855         For such patterns, the PCRE_ANCHORED bit is set in the options returned         For such patterns, the PCRE_ANCHORED bit is set in the options returned
2856         by pcre_fullinfo().         by pcre_fullinfo().
2857    
2858             PCRE_INFO_RECURSIONLIMIT
2859    
2860           If the pattern set a recursion limit by including an item of  the  form
2861           (*LIMIT_RECURSION=nnnn) at the start, the value is returned. The fourth
2862           argument should point to an unsigned 32-bit integer. If no  such  value
2863           has   been   set,   the  call  to  pcre_fullinfo()  returns  the  error
2864           PCRE_ERROR_UNSET.
2865    
2866           PCRE_INFO_SIZE           PCRE_INFO_SIZE
2867    
2868         Return  the  size  of the compiled pattern, that is, the value that was         Return the size of  the  compiled  pattern  in  bytes  (for  all  three
2869         passed as the argument to pcre_malloc() when PCRE was getting memory in         libraries). The fourth argument should point to a size_t variable. This
2870         which to place the compiled data. The fourth argument should point to a         value does not include the size of the pcre structure that is  returned
2871         size_t variable.         by  pcre_compile().  The  value  that  is  passed  as  the  argument to
2872           pcre_malloc() when pcre_compile() is getting memory in which  to  place
2873           the compiled data is the value returned by this option plus the size of
2874           the pcre structure. Studying a compiled pattern, with or  without  JIT,
2875           does not alter the value returned by this option.
2876    
2877           PCRE_INFO_STUDYSIZE           PCRE_INFO_STUDYSIZE
2878    
2879         Return the size of the data block pointed to by the study_data field in         Return  the  size  in bytes (for all three libraries) of the data block
2880         a  pcre_extra  block.  That  is,  it  is  the  value that was passed to         pointed to by the study_data field in a pcre_extra block. If pcre_extra
2881         pcre_malloc() when PCRE was getting memory into which to place the data         is  NULL, or there is no study data, zero is returned. The fourth argu-
2882         created  by  pcre_study().  If pcre_extra is NULL, or there is no study         ment should point to a size_t variable. The study_data field is set  by
2883         data, zero is returned. The fourth argument should point  to  a  size_t         pcre_study() to record information that will speed up matching (see the
2884           section entitled  "Studying  a  pattern"  above).  The  format  of  the
2885           study_data  block is private, but its length is made available via this
2886           option so that it can be saved and  restored  (see  the  pcreprecompile
2887           documentation for details).
2888    
2889             PCRE_INFO_FIRSTCHARACTERFLAGS
2890    
2891           Return information about the first data unit of any matched string, for
2892           a non-anchored pattern. The fourth argument  should  point  to  an  int
2893         variable.         variable.
2894    
2895           If  there  is  a  fixed first value, for example, the letter "c" from a
2896           pattern such as (cat|cow|coyote), 1  is  returned,  and  the  character
2897           value can be retrieved using PCRE_INFO_FIRSTCHARACTER.
2898    
2899           If there is no fixed first value, and if either
2900    
2901           (a)  the pattern was compiled with the PCRE_MULTILINE option, and every
2902           branch starts with "^", or
2903    
2904           (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2905           set (if it were set, the pattern would be anchored),
2906    
2907           2 is returned, indicating that the pattern matches only at the start of
2908           a subject string or after any newline within the string. Otherwise 0 is
2909           returned. For anchored patterns, 0 is returned.
2910    
2911             PCRE_INFO_FIRSTCHARACTER
2912    
2913           Return  the  fixed  first character value, if PCRE_INFO_FIRSTCHARACTER-
2914           FLAGS returned 1; otherwise returns 0. The fourth argument should point
2915           to an uint_t variable.
2916    
2917           In  the 8-bit library, the value is always less than 256. In the 16-bit
2918           library the value can be up to 0xffff. In the 32-bit library in  UTF-32
2919           mode  the  value  can  be up to 0x10ffff, and up to 0xffffffff when not
2920           using UTF-32 mode.
2921    
2922           If there is no fixed first value, and if either
2923    
2924           (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
2925           branch starts with "^", or
2926    
2927           (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2928           set (if it were set, the pattern would be anchored),
2929    
2930  OBSOLETE INFO FUNCTION         -1 is returned, indicating that the pattern matches only at  the  start
2931           of  a  subject string or after any newline within the string. Otherwise
2932           -2 is returned. For anchored patterns, -2 is returned.
2933    
2934         int pcre_info(const pcre *code, int *optptr, int *firstcharptr);           PCRE_INFO_REQUIREDCHARFLAGS
2935    
2936         The  pcre_info()  function is now obsolete because its interface is too         Returns 1 if there is a rightmost literal data unit that must exist  in
2937         restrictive to return all the available data about a compiled  pattern.         any matched string, other than at its start. The fourth argument should
2938         New   programs   should  use  pcre_fullinfo()  instead.  The  yield  of         point to an int variable. If there is no such value, 0 is returned.  If
2939         pcre_info() is the number of capturing subpatterns, or one of the  fol-         returning  1,  the  character  value  itself  can  be  retrieved  using
2940         lowing negative numbers:         PCRE_INFO_REQUIREDCHAR.
2941    
2942           PCRE_ERROR_NULL       the argument code was NULL         For anchored patterns, a last literal value is recorded only if it fol-
2943           PCRE_ERROR_BADMAGIC   the "magic number" was not found         lows  something  of  variable  length.  For  example,  for  the pattern
2944           /^a\d+z\d+/  the   returned   value   1   (with   "z"   returned   from
2945         If  the  optptr  argument is not NULL, a copy of the options with which         PCRE_INFO_REQUIREDCHAR), but for /^a\dz\d/ the returned value is 0.
2946         the pattern was compiled is placed in the integer  it  points  to  (see  
2947         PCRE_INFO_OPTIONS above).           PCRE_INFO_REQUIREDCHAR
2948    
2949         If  the  pattern  is  not anchored and the firstcharptr argument is not         Return  the value of the rightmost literal data unit that must exist in
2950         NULL, it is used to pass back information about the first character  of         any matched string, other than at its start, if such a value  has  been
2951         any matched string (see PCRE_INFO_FIRSTBYTE above).         recorded.  The fourth argument should point to an uint32_t variable. If
2952           there is no such value, 0 is returned.
2953    
2954    
2955  REFERENCE COUNTS  REFERENCE COUNTS
2956    
2957         int pcre_refcount(pcre *code, int adjust);         int pcre_refcount(pcre *code, int adjust);
2958    
2959         The  pcre_refcount()  function is used to maintain a reference count in         The pcre_refcount() function is used to maintain a reference  count  in
2960         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
2961         benefit  of  applications  that  operate  in an object-oriented manner,         benefit of applications that  operate  in  an  object-oriented  manner,
2962         where different parts of the application may be using the same compiled         where different parts of the application may be using the same compiled
2963         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.
2964    
2965         When a pattern is compiled, the reference count field is initialized to         When a pattern is compiled, the reference count field is initialized to
2966         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
2967         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
2968         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
2969         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
2970         is outside these limits, it is forced to the appropriate limit value.         is outside these limits, it is forced to the appropriate limit value.
2971    
2972         Except when it is zero, the reference count is not correctly  preserved         Except  when it is zero, the reference count is not correctly preserved
2973         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
2974         whose byte-order is different. (This seems a highly unlikely scenario.)         whose byte-order is different. (This seems a highly unlikely scenario.)
2975    
2976    
# Line 1895  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2980  MATCHING A PATTERN: THE TRADITIONAL FUNC
2980              const char *subject, int length, int startoffset,              const char *subject, int length, int startoffset,
2981              int options, int *ovector, int ovecsize);              int options, int *ovector, int ovecsize);
2982    
2983         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
2984         compiled  pattern, which is passed in the code argument. If the pattern         compiled pattern, which is passed in the code argument. If the  pattern
2985         was 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
2986         argument.  This  function is the main matching facility of the library,         argument. You can call pcre_exec() with the same code and  extra  argu-
2987         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
2988         an  alternative matching function, which is described below in the sec-         strings with the same pattern.
2989         tion about the pcre_dfa_exec() function.  
2990           This function is the main matching facility  of  the  library,  and  it
2991           operates  in  a  Perl-like  manner. For specialist use there is also an
2992           alternative matching function, which is described below in the  section
2993           about the pcre_dfa_exec() function.
2994    
2995         In most applications, the pattern will have been compiled (and  option-         In  most applications, the pattern will have been compiled (and option-
2996         ally  studied)  in the same process that calls pcre_exec(). However, it         ally studied) in the same process that calls pcre_exec().  However,  it
2997         is possible to save compiled patterns and study data, and then use them         is possible to save compiled patterns and study data, and then use them
2998         later  in  different processes, possibly even on different hosts. For a         later in different processes, possibly even on different hosts.  For  a
2999         discussion about this, see the pcreprecompile documentation.         discussion about this, see the pcreprecompile documentation.
3000    
3001         Here is an example of a simple call to pcre_exec():         Here is an example of a simple call to pcre_exec():
# Line 1925  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3014  MATCHING A PATTERN: THE TRADITIONAL FUNC
3014    
3015     Extra data for pcre_exec()     Extra data for pcre_exec()
3016    
3017         If the extra argument is not NULL, it must point to a  pcre_extra  data         If  the  extra argument is not NULL, it must point to a pcre_extra data
3018         block.  The pcre_study() function returns such a block (when it doesn't         block. The pcre_study() function returns such a block (when it  doesn't
3019         return NULL), but you can also create one for yourself, and pass  addi-         return  NULL), but you can also create one for yourself, and pass addi-
3020         tional  information  in it. The pcre_extra block contains the following         tional information in it. The pcre_extra block contains  the  following
3021         fields (not necessarily in this order):         fields (not necessarily in this order):
3022    
3023           unsigned long int flags;           unsigned long int flags;
3024           void *study_data;           void *study_data;
3025             void *executable_jit;
3026           unsigned long int match_limit;           unsigned long int match_limit;
3027           unsigned long int match_limit_recursion;           unsigned long int match_limit_recursion;
3028           void *callout_data;           void *callout_data;
3029           const unsigned char *tables;           const unsigned char *tables;
3030           unsigned char **mark;           unsigned char **mark;
3031    
3032         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
3033         are set. The flag bits are:         "PCRE_UCHAR16 **".
3034    
3035           PCRE_EXTRA_STUDY_DATA         In the 32-bit version of  this  structure,  the  mark  field  has  type
3036           "PCRE_UCHAR32 **".
3037    
3038           The  flags  field is used to specify which of the other fields are set.
3039           The flag bits are:
3040    
3041             PCRE_EXTRA_CALLOUT_DATA
3042             PCRE_EXTRA_EXECUTABLE_JIT
3043             PCRE_EXTRA_MARK
3044           PCRE_EXTRA_MATCH_LIMIT           PCRE_EXTRA_MATCH_LIMIT
3045           PCRE_EXTRA_MATCH_LIMIT_RECURSION           PCRE_EXTRA_MATCH_LIMIT_RECURSION
3046           PCRE_EXTRA_CALLOUT_DATA           PCRE_EXTRA_STUDY_DATA
3047           PCRE_EXTRA_TABLES           PCRE_EXTRA_TABLES
          PCRE_EXTRA_MARK  
3048    
3049         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-
3050         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
3051         the appropriate flag bit. You should not set this yourself, but you may         returned by pcre_study(), together with the appropriate flag bits.  You
3052         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
3053         flag bits.         other fields and their corresponding flag bits.
3054    
3055         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
3056         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
3057         match,  but  which  have  a very large number of possibilities in their         match, but which have a very large number  of  possibilities  in  their
3058         search trees. The classic example is a pattern that uses nested  unlim-         search  trees. The classic example is a pattern that uses nested unlim-
3059         ited repeats.         ited repeats.
3060    
3061         Internally,  PCRE uses a function called match() which it calls repeat-         Internally, pcre_exec() uses a function called match(), which it  calls
3062         edly (sometimes recursively). The limit set by match_limit  is  imposed         repeatedly  (sometimes  recursively).  The  limit set by match_limit is
3063         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,
3064         has the effect of limiting the amount of  backtracking  that  can  take         which  has  the  effect of limiting the amount of backtracking that can
3065         place. For patterns that are not anchored, the count restarts from zero         take place. For patterns that are not anchored, the count restarts from
3066         for each position in the subject string.         zero for each position in the subject string.
3067    
3068           When pcre_exec() is called with a pattern that was successfully studied
3069           with a JIT option, the way that the matching is  executed  is  entirely
3070           different.  However, there is still the possibility of runaway matching
3071           that goes on for a very long time, and so the match_limit value is also
3072           used in this case (but in a different way) to limit how long the match-
3073           ing can continue.
3074    
3075         The default value for the limit can be set  when  PCRE  is  built;  the         The default value for the limit can be set  when  PCRE  is  built;  the
3076         default  default  is 10 million, which handles all but the most extreme         default  default  is 10 million, which handles all but the most extreme
# Line 1975  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3079  MATCHING A PATTERN: THE TRADITIONAL FUNC
3079         PCRE_EXTRA_MATCH_LIMIT is set in the  flags  field.  If  the  limit  is         PCRE_EXTRA_MATCH_LIMIT is set in the  flags  field.  If  the  limit  is
3080         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
3081    
3082         The  match_limit_recursion field is similar to match_limit, but instead         A  value  for  the  match  limit may also be supplied by an item at the
3083           start of a pattern of the form
3084    
3085             (*LIMIT_MATCH=d)
3086    
3087           where d is a decimal number. However, such a setting is ignored  unless
3088           d  is  less  than  the limit set by the caller of pcre_exec() or, if no
3089           such limit is set, less than the default.
3090    
3091           The match_limit_recursion field is similar to match_limit, but  instead
3092         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
3093         the  depth  of  recursion. The recursion depth is a smaller number than         the depth of recursion. The recursion depth is a  smaller  number  than
3094         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-
3095         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.
3096    
3097         Limiting  the  recursion  depth  limits the amount of stack that can be         Limiting the recursion depth limits the amount of  machine  stack  that
3098         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
3099         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
3100           limit  is not relevant, and is ignored, when matching is done using JIT
3101         The  default  value  for  match_limit_recursion can be set when PCRE is         compiled code.
3102         built; the default default  is  the  same  value  as  the  default  for  
3103         match_limit.  You can override the default by suppling pcre_exec() with         The default value for match_limit_recursion can be  set  when  PCRE  is
3104         a  pcre_extra  block  in  which  match_limit_recursion  is   set,   and         built;  the  default  default  is  the  same  value  as the default for
3105         PCRE_EXTRA_MATCH_LIMIT_RECURSION  is  set  in  the  flags field. If the         match_limit. You can override the default by suppling pcre_exec()  with
3106           a   pcre_extra   block  in  which  match_limit_recursion  is  set,  and
3107           PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in  the  flags  field.  If  the
3108         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.
3109    
3110           A  value for the recursion limit may also be supplied by an item at the
3111           start of a pattern of the form
3112    
3113             (*LIMIT_RECURSION=d)
3114    
3115           where d is a decimal number. However, such a setting is ignored  unless
3116           d  is  less  than  the limit set by the caller of pcre_exec() or, if no
3117           such limit is set, less than the default.
3118    
3119         The callout_data field is used in conjunction with the  "callout"  fea-         The callout_data field is used in conjunction with the  "callout"  fea-
3120         ture, and is described in the pcrecallout documentation.         ture, and is described in the pcrecallout documentation.
3121    
# Line 2007  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3131  MATCHING A PATTERN: THE TRADITIONAL FUNC
3131         tion for a discussion of saving compiled patterns for later use.         tion for a discussion of saving compiled patterns for later use.
3132    
3133         If PCRE_EXTRA_MARK is set in the flags field, the mark  field  must  be         If PCRE_EXTRA_MARK is set in the flags field, the mark  field  must  be
3134         set  to  point  to a char * variable. If the pattern contains any back-         set  to point to a suitable variable. If the pattern contains any back-
3135         tracking control verbs such as (*MARK:NAME), and the execution ends  up         tracking control verbs such as (*MARK:NAME), and the execution ends  up
3136         with  a  name  to  pass back, a pointer to the name string (zero termi-         with  a  name  to  pass back, a pointer to the name string (zero termi-
3137         nated) is placed in the variable pointed to  by  the  mark  field.  The         nated) is placed in the variable pointed to  by  the  mark  field.  The
3138         names  are  within  the  compiled pattern; if you wish to retain such a         names  are  within  the  compiled pattern; if you wish to retain such a
3139         name you must copy it before freeing the memory of a compiled  pattern.         name you must copy it before freeing the memory of a compiled  pattern.
3140         If  there  is no name to pass back, the variable pointed to by the mark         If  there  is no name to pass back, the variable pointed to by the mark
3141         field set to NULL. For details of the backtracking control  verbs,  see         field is set to NULL. For details of the  backtracking  control  verbs,
3142         the section entitled "Backtracking control" in the pcrepattern documen-         see the section entitled "Backtracking control" in the pcrepattern doc-
3143         tation.         umentation.
3144    
3145     Option bits for pcre_exec()     Option bits for pcre_exec()
3146    
3147         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.
3148         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,
3149         PCRE_NOTBOL,   PCRE_NOTEOL,    PCRE_NOTEMPTY,    PCRE_NOTEMPTY_ATSTART,         PCRE_NOTBOL,   PCRE_NOTEOL,    PCRE_NOTEMPTY,    PCRE_NOTEMPTY_ATSTART,
3150         PCRE_NO_START_OPTIMIZE,   PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_SOFT,  and         PCRE_NO_START_OPTIMIZE,   PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_HARD,  and
3151         PCRE_PARTIAL_HARD.         PCRE_PARTIAL_SOFT.
3152    
3153           If the pattern was successfully studied with one  of  the  just-in-time
3154           (JIT) compile options, the only supported options for JIT execution are
3155           PCRE_NO_UTF8_CHECK,    PCRE_NOTBOL,     PCRE_NOTEOL,     PCRE_NOTEMPTY,
3156           PCRE_NOTEMPTY_ATSTART,  PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an
3157           unsupported option is used, JIT execution is disabled  and  the  normal
3158           interpretive code in pcre_exec() is run.
3159    
3160           PCRE_ANCHORED           PCRE_ANCHORED
3161    
3162         The PCRE_ANCHORED option limits pcre_exec() to matching  at  the  first         The  PCRE_ANCHORED  option  limits pcre_exec() to matching at the first
3163         matching  position.  If  a  pattern was compiled with PCRE_ANCHORED, or         matching position. If a pattern was  compiled  with  PCRE_ANCHORED,  or
3164         turned out to be anchored by virtue of its contents, it cannot be  made         turned  out to be anchored by virtue of its contents, it cannot be made
3165         unachored at matching time.         unachored at matching time.
3166    
3167           PCRE_BSR_ANYCRLF           PCRE_BSR_ANYCRLF
3168           PCRE_BSR_UNICODE           PCRE_BSR_UNICODE
3169    
3170         These options (which are mutually exclusive) control what the \R escape         These options (which are mutually exclusive) control what the \R escape
3171         sequence matches. The choice is either to match only CR, LF,  or  CRLF,         sequence  matches.  The choice is either to match only CR, LF, or CRLF,
3172         or  to  match  any Unicode newline sequence. These options override the         or to match any Unicode newline sequence. These  options  override  the
3173         choice that was made or defaulted when the pattern was compiled.         choice that was made or defaulted when the pattern was compiled.
3174    
3175           PCRE_NEWLINE_CR           PCRE_NEWLINE_CR
# Line 2047  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3178  MATCHING A PATTERN: THE TRADITIONAL FUNC
3178           PCRE_NEWLINE_ANYCRLF           PCRE_NEWLINE_ANYCRLF
3179           PCRE_NEWLINE_ANY           PCRE_NEWLINE_ANY
3180    
3181         These options override  the  newline  definition  that  was  chosen  or         These  options  override  the  newline  definition  that  was chosen or
3182         defaulted  when the pattern was compiled. For details, see the descrip-         defaulted when the pattern was compiled. For details, see the  descrip-
3183         tion of pcre_compile()  above.  During  matching,  the  newline  choice         tion  of  pcre_compile()  above.  During  matching,  the newline choice
3184         affects  the  behaviour  of the dot, circumflex, and dollar metacharac-         affects the behaviour of the dot, circumflex,  and  dollar  metacharac-
3185         ters. It may also alter the way the match position is advanced after  a         ters.  It may also alter the way the match position is advanced after a
3186         match failure for an unanchored pattern.         match failure for an unanchored pattern.
3187    
3188         When  PCRE_NEWLINE_CRLF,  PCRE_NEWLINE_ANYCRLF,  or PCRE_NEWLINE_ANY is         When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF,  or  PCRE_NEWLINE_ANY  is
3189         set, and a match attempt for an unanchored pattern fails when the  cur-         set,  and a match attempt for an unanchored pattern fails when the cur-
3190         rent  position  is  at  a  CRLF  sequence,  and the pattern contains no         rent position is at a  CRLF  sequence,  and  the  pattern  contains  no
3191         explicit matches for  CR  or  LF  characters,  the  match  position  is         explicit  matches  for  CR  or  LF  characters,  the  match position is
3192         advanced by two characters instead of one, in other words, to after the         advanced by two characters instead of one, in other words, to after the
3193         CRLF.         CRLF.
3194    
3195         The above rule is a compromise that makes the most common cases work as         The above rule is a compromise that makes the most common cases work as
3196         expected.  For  example,  if  the  pattern  is .+A (and the PCRE_DOTALL         expected. For example, if the  pattern  is  .+A  (and  the  PCRE_DOTALL
3197         option is not set), it does not match the string "\r\nA" because, after         option is not set), it does not match the string "\r\nA" because, after
3198         failing  at the start, it skips both the CR and the LF before retrying.         failing at the start, it skips both the CR and the LF before  retrying.
3199         However, the pattern [\r\n]A does match that string,  because  it  con-         However,  the  pattern  [\r\n]A does match that string, because it con-
3200         tains an explicit CR or LF reference, and so advances only by one char-         tains an explicit CR or LF reference, and so advances only by one char-
3201         acter after the first failure.         acter after the first failure.
3202    
3203         An explicit match for CR of LF is either a literal appearance of one of         An explicit match for CR of LF is either a literal appearance of one of
3204         those  characters,  or  one  of the \r or \n escape sequences. Implicit         those characters, or one of the \r or  \n  escape  sequences.  Implicit
3205         matches such as [^X] do not count, nor does \s (which includes  CR  and         matches  such  as [^X] do not count, nor does \s (which includes CR and
3206         LF in the characters that it matches).         LF in the characters that it matches).
3207    
3208         Notwithstanding  the above, anomalous effects may still occur when CRLF         Notwithstanding the above, anomalous effects may still occur when  CRLF
3209         is a valid newline sequence and explicit \r or \n escapes appear in the         is a valid newline sequence and explicit \r or \n escapes appear in the
3210         pattern.         pattern.
3211    
3212           PCRE_NOTBOL           PCRE_NOTBOL
3213    
3214         This option specifies that first character of the subject string is not         This option specifies that first character of the subject string is not
3215         the beginning of a line, so the  circumflex  metacharacter  should  not         the  beginning  of  a  line, so the circumflex metacharacter should not
3216         match  before it. Setting this without PCRE_MULTILINE (at compile time)         match before it. Setting this without PCRE_MULTILINE (at compile  time)
3217         causes circumflex never to match. This option affects only  the  behav-         causes  circumflex  never to match. This option affects only the behav-
3218         iour of the circumflex metacharacter. It does not affect \A.         iour of the circumflex metacharacter. It does not affect \A.
3219    
3220           PCRE_NOTEOL           PCRE_NOTEOL
3221    
3222         This option specifies that the end of the subject string is not the end         This option specifies that the end of the subject string is not the end
3223         of a line, so the dollar metacharacter should not match it nor  (except         of  a line, so the dollar metacharacter should not match it nor (except
3224         in  multiline mode) a newline immediately before it. Setting this with-         in multiline mode) a newline immediately before it. Setting this  with-
3225         out PCRE_MULTILINE (at compile time) causes dollar never to match. This         out PCRE_MULTILINE (at compile time) causes dollar never to match. This
3226         option  affects only the behaviour of the dollar metacharacter. It does         option affects only the behaviour of the dollar metacharacter. It  does
3227         not affect \Z or \z.         not affect \Z or \z.
3228    
3229           PCRE_NOTEMPTY           PCRE_NOTEMPTY
3230    
3231         An empty string is not considered to be a valid match if this option is         An empty string is not considered to be a valid match if this option is
3232         set.  If  there are alternatives in the pattern, they are tried. If all         set. If there are alternatives in the pattern, they are tried.  If  all
3233         the alternatives match the empty string, the entire  match  fails.  For         the  alternatives  match  the empty string, the entire match fails. For
3234         example, if the pattern         example, if the pattern
3235    
3236           a?b?           a?b?
3237    
3238         is  applied  to  a  string not beginning with "a" or "b", it matches an         is applied to a string not beginning with "a" or  "b",  it  matches  an
3239         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
3240         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-
3241         rences of "a" or "b".         rences of "a" or "b".
3242    
3243           PCRE_NOTEMPTY_ATSTART           PCRE_NOTEMPTY_ATSTART
3244    
3245         This is like PCRE_NOTEMPTY, except that an empty string match  that  is         This  is  like PCRE_NOTEMPTY, except that an empty string match that is
3246         not  at  the  start  of  the  subject  is  permitted. If the pattern is         not at the start of  the  subject  is  permitted.  If  the  pattern  is
3247         anchored, such a match can occur only if the pattern contains \K.         anchored, such a match can occur only if the pattern contains \K.
3248    
3249         Perl    has    no    direct    equivalent    of    PCRE_NOTEMPTY     or         Perl     has    no    direct    equivalent    of    PCRE_NOTEMPTY    or
3250         PCRE_NOTEMPTY_ATSTART,  but  it  does  make a special case of a pattern         PCRE_NOTEMPTY_ATSTART, but it does make a special  case  of  a  pattern
3251         match of the empty string within its split() function, and  when  using         match  of  the empty string within its split() function, and when using
3252         the  /g  modifier.  It  is  possible  to emulate Perl's behaviour after         the /g modifier. It is  possible  to  emulate  Perl's  behaviour  after
3253         matching a null string by first trying the match again at the same off-         matching a null string by first trying the match again at the same off-
3254         set  with  PCRE_NOTEMPTY_ATSTART  and  PCRE_ANCHORED,  and then if that         set with PCRE_NOTEMPTY_ATSTART and  PCRE_ANCHORED,  and  then  if  that
3255         fails, by advancing the starting offset (see below) and trying an ordi-         fails, by advancing the starting offset (see below) and trying an ordi-
3256         nary  match  again. There is some code that demonstrates how to do this         nary match again. There is some code that demonstrates how to  do  this
3257         in the pcredemo sample program.         in  the  pcredemo sample program. In the most general case, you have to
3258           check to see if the newline convention recognizes CRLF  as  a  newline,
3259           and  if so, and the current character is CR followed by LF, advance the
3260           starting offset by two characters instead of one.
3261    
3262           PCRE_NO_START_OPTIMIZE           PCRE_NO_START_OPTIMIZE
3263    
# Line 2134  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3268  MATCHING A PATTERN: THE TRADITIONAL FUNC
3268         cannot find it, without actually running the  main  matching  function.         cannot find it, without actually running the  main  matching  function.
3269         This means that a special item such as (*COMMIT) at the start of a pat-         This means that a special item such as (*COMMIT) at the start of a pat-
3270         tern is not considered until after a suitable starting  point  for  the         tern is not considered until after a suitable starting  point  for  the
3271         match  has been found. When callouts or (*MARK) items are in use, these         match  has been found. Also, when callouts or (*MARK) items are in use,
3272         "start-up" optimizations can cause them to be skipped if the pattern is         these "start-up" optimizations can cause them to be skipped if the pat-
3273         never  actually  used.  The start-up optimizations are in effect a pre-         tern is never actually used. The start-up optimizations are in effect a
3274         scan of the subject that takes place before the pattern is run.         pre-scan of the subject that takes place before the pattern is run.
3275    
3276         The PCRE_NO_START_OPTIMIZE option disables the start-up  optimizations,         The PCRE_NO_START_OPTIMIZE option disables the start-up  optimizations,
3277         possibly  causing  performance  to  suffer,  but ensuring that in cases         possibly  causing  performance  to  suffer,  but ensuring that in cases
3278         where the result is "no match", the callouts do occur, and  that  items         where the result is "no match", the callouts do occur, and  that  items
3279         such as (*COMMIT) and (*MARK) are considered at every possible starting         such as (*COMMIT) and (*MARK) are considered at every possible starting
3280         position in the subject  string.   Setting  PCRE_NO_START_OPTIMIZE  can         position in the subject string. If  PCRE_NO_START_OPTIMIZE  is  set  at
3281         change the outcome of a matching operation.  Consider the pattern         compile  time,  it  cannot  be  unset  at  matching  time.  The  use of
3282           PCRE_NO_START_OPTIMIZE  at  matching  time  (that  is,  passing  it  to
3283           pcre_exec())  disables  JIT  execution;  in this situation, matching is
3284           always done using interpretively.
3285    
3286           Setting PCRE_NO_START_OPTIMIZE can change the  outcome  of  a  matching
3287           operation.  Consider the pattern
3288    
3289           (*COMMIT)ABC           (*COMMIT)ABC
3290    
# Line 2175  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3315  MATCHING A PATTERN: THE TRADITIONAL FUNC
3315    
3316         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
3317         UTF-8  string is automatically checked when pcre_exec() is subsequently         UTF-8  string is automatically checked when pcre_exec() is subsequently
3318         called.  The value of startoffset is also checked  to  ensure  that  it         called.  The entire string is checked before any other processing takes
3319         points  to  the start of a UTF-8 character. There is a discussion about         place.  The  value  of  startoffset  is  also checked to ensure that it
3320         the validity of UTF-8 strings in the section on UTF-8  support  in  the         points to the start of a UTF-8 character. There is a  discussion  about
3321         main  pcre  page.  If  an  invalid  UTF-8  sequence  of bytes is found,         the  validity  of  UTF-8 strings in the pcreunicode page. If an invalid
3322         pcre_exec() returns the error PCRE_ERROR_BADUTF8. If  startoffset  con-         sequence  of  bytes   is   found,   pcre_exec()   returns   the   error
3323         tains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.         PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a
3324           truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
3325           both  cases, information about the precise nature of the error may also
3326           be returned (see the descriptions of these errors in the section  enti-
3327           tled  Error return values from pcre_exec() below).  If startoffset con-
3328           tains a value that does not point to the start of a UTF-8 character (or
3329           to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is returned.
3330    
3331         If  you  already  know that your subject is valid, and you want to skip         If  you  already  know that your subject is valid, and you want to skip
3332         these   checks   for   performance   reasons,   you   can    set    the         these   checks   for   performance   reasons,   you   can    set    the
# Line 2188  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3334  MATCHING A PATTERN: THE TRADITIONAL FUNC
3334         do this for the second and subsequent calls to pcre_exec() if  you  are         do this for the second and subsequent calls to pcre_exec() if  you  are
3335         making  repeated  calls  to  find  all  the matches in a single subject         making  repeated  calls  to  find  all  the matches in a single subject
3336         string. However, you should be  sure  that  the  value  of  startoffset         string. However, you should be  sure  that  the  value  of  startoffset
3337         points  to  the  start of a UTF-8 character. When PCRE_NO_UTF8_CHECK is         points  to  the  start of a character (or the end of the subject). When
3338         set, the effect of passing an invalid UTF-8 string as a subject,  or  a         PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid string as a
3339         value  of startoffset that does not point to the start of a UTF-8 char-         subject  or  an invalid value of startoffset is undefined. Your program
3340         acter, is undefined. Your program may crash.         may crash.
3341    
3342           PCRE_PARTIAL_HARD           PCRE_PARTIAL_HARD
3343           PCRE_PARTIAL_SOFT           PCRE_PARTIAL_SOFT
# Line 2200  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3346  MATCHING A PATTERN: THE TRADITIONAL FUNC
3346         patibility,  PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial         patibility,  PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial
3347         match occurs if the end of the subject string is reached  successfully,         match occurs if the end of the subject string is reached  successfully,
3348         but  there  are not enough subject characters to complete the match. If         but  there  are not enough subject characters to complete the match. If
3349         this happens when PCRE_PARTIAL_HARD  is  set,  pcre_exec()  immediately         this happens when PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set,
3350         returns  PCRE_ERROR_PARTIAL.  Otherwise,  if  PCRE_PARTIAL_SOFT is set,         matching  continues  by  testing any remaining alternatives. Only if no
3351         matching continues by testing any other alternatives. Only if they  all         complete match can be found is PCRE_ERROR_PARTIAL returned  instead  of
3352         fail  is  PCRE_ERROR_PARTIAL  returned (instead of PCRE_ERROR_NOMATCH).         PCRE_ERROR_NOMATCH.  In  other  words,  PCRE_PARTIAL_SOFT says that the
3353         The portion of the string that was inspected when the partial match was         caller is prepared to handle a partial match, but only if  no  complete
3354         found  is  set  as  the first matching string. There is a more detailed         match can be found.
3355         discussion in the pcrepartial documentation.  
3356           If  PCRE_PARTIAL_HARD  is  set, it overrides PCRE_PARTIAL_SOFT. In this
3357           case, if a partial match  is  found,  pcre_exec()  immediately  returns
3358           PCRE_ERROR_PARTIAL,  without  considering  any  other  alternatives. In
3359           other words, when PCRE_PARTIAL_HARD is set, a partial match is  consid-
3360           ered to be more important that an alternative complete match.
3361    
3362           In  both  cases,  the portion of the string that was inspected when the
3363           partial match was found is set as the first matching string. There is a
3364           more  detailed  discussion  of partial and multi-segment matching, with
3365           examples, in the pcrepartial documentation.
3366    
3367     The string to be matched by pcre_exec()     The string to be matched by pcre_exec()
3368    
3369         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
3370         length (in bytes) in length, and a starting byte offset in startoffset.         length  in  length, and a starting offset in startoffset. The units for
3371         In UTF-8 mode, the byte offset must point to the start of a UTF-8 char-         length and startoffset are bytes for the  8-bit  library,  16-bit  data
3372         acter.  Unlike  the pattern string, the subject may contain binary zero         items  for  the  16-bit  library,  and 32-bit data items for the 32-bit
3373         bytes. When the starting offset is zero, the search for a match  starts         library.
3374         at  the  beginning  of  the subject, and this is by far the most common  
3375         case.         If startoffset is negative or greater than the length of  the  subject,
3376           pcre_exec()  returns  PCRE_ERROR_BADOFFSET. When the starting offset is
3377         A non-zero starting offset is useful when searching for  another  match         zero, the search for a match starts at the beginning  of  the  subject,
3378         in  the same subject by calling pcre_exec() again after a previous suc-         and  this  is by far the most common case. In UTF-8 or UTF-16 mode, the
3379         cess.  Setting startoffset differs from just passing over  a  shortened         offset must point to the start of a character, or the end of  the  sub-
3380         string  and  setting  PCRE_NOTBOL  in the case of a pattern that begins         ject  (in  UTF-32 mode, one data unit equals one character, so all off-
3381           sets are valid). Unlike the pattern string,  the  subject  may  contain
3382           binary zeroes.
3383    
3384           A  non-zero  starting offset is useful when searching for another match
3385           in the same subject by calling pcre_exec() again after a previous  suc-
3386           cess.   Setting  startoffset differs from just passing over a shortened
3387           string and setting PCRE_NOTBOL in the case of  a  pattern  that  begins
3388         with any kind of lookbehind. For example, consider the pattern         with any kind of lookbehind. For example, consider the pattern
3389    
3390           \Biss\B           \Biss\B
3391    
3392         which finds occurrences of "iss" in the middle of  words.  (\B  matches         which  finds  occurrences  of "iss" in the middle of words. (\B matches
3393         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.)
3394         When applied to the string "Mississipi" the first call  to  pcre_exec()         When  applied  to the string "Mississipi" the first call to pcre_exec()
3395         finds  the  first  occurrence. If pcre_exec() is called again with just         finds the first occurrence. If pcre_exec() is called  again  with  just
3396         the remainder of the subject,  namely  "issipi",  it  does  not  match,         the  remainder  of  the  subject,  namely  "issipi", it does not match,
3397         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
3398         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
3399         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-
3400         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
3401         discover that it is preceded by a letter.         discover that it is preceded by a letter.
3402    
3403           Finding all the matches in a subject is tricky  when  the  pattern  can
3404           match an empty string. It is possible to emulate Perl's /g behaviour by
3405           first  trying  the  match  again  at  the   same   offset,   with   the
3406           PCRE_NOTEMPTY_ATSTART  and  PCRE_ANCHORED  options,  and  then  if that
3407           fails, advancing the starting  offset  and  trying  an  ordinary  match
3408           again. There is some code that demonstrates how to do this in the pcre-
3409           demo sample program. In the most general case, you have to check to see
3410           if  the newline convention recognizes CRLF as a newline, and if so, and
3411           the current character is CR followed by LF, advance the starting offset
3412           by two characters instead of one.
3413    
3414         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,
3415         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
3416         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 2267  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3441  MATCHING A PATTERN: THE TRADITIONAL FUNC
3441         When a match is successful, information about  captured  substrings  is         When a match is successful, information about  captured  substrings  is
3442         returned  in  pairs  of integers, starting at the beginning of ovector,         returned  in  pairs  of integers, starting at the beginning of ovector,
3443         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
3444         element  of  each pair is set to the byte offset of the first character         element  of  each pair is set to the offset of the first character in a
3445         in a substring, and the second is set to the byte offset of  the  first         substring, and the second is set to the offset of the  first  character
3446         character  after  the end of a substring. N