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revision 548 by ph10, Fri Jun 25 14:42:00 2010 UTC revision 1320 by ph10, Wed May 1 16:39:35 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    
220    PCRE 16-BIT API STRING EXTRACTION FUNCTIONS
221    
222           int pcre16_copy_named_substring(const pcre16 *code,
223                PCRE_SPTR16 subject, int *ovector,
224                int stringcount, PCRE_SPTR16 stringname,
225                PCRE_UCHAR16 *buffer, int buffersize);
226    
227           int pcre16_copy_substring(PCRE_SPTR16 subject, int *ovector,
228                int stringcount, int stringnumber, PCRE_UCHAR16 *buffer,
229                int buffersize);
230    
231           int pcre16_get_named_substring(const pcre16 *code,
232                PCRE_SPTR16 subject, int *ovector,
233                int stringcount, PCRE_SPTR16 stringname,
234                PCRE_SPTR16 *stringptr);
235    
236           int pcre16_get_stringnumber(const pcre16 *code,
237                PCRE_SPTR16 name);
238    
239           int pcre16_get_stringtable_entries(const pcre16 *code,
240                PCRE_SPTR16 name, PCRE_UCHAR16 **first, PCRE_UCHAR16 **last);
241    
242           int pcre16_get_substring(PCRE_SPTR16 subject, int *ovector,
243                int stringcount, int stringnumber,
244                PCRE_SPTR16 *stringptr);
245    
246           int pcre16_get_substring_list(PCRE_SPTR16 subject,
247                int *ovector, int stringcount, PCRE_SPTR16 **listptr);
248    
249           void pcre16_free_substring(PCRE_SPTR16 stringptr);
250    
251           void pcre16_free_substring_list(PCRE_SPTR16 *stringptr);
252    
253    
254    PCRE 16-BIT API AUXILIARY FUNCTIONS
255    
256           pcre16_jit_stack *pcre16_jit_stack_alloc(int startsize, int maxsize);
257    
258           void pcre16_jit_stack_free(pcre16_jit_stack *stack);
259    
260           void pcre16_assign_jit_stack(pcre16_extra *extra,
261                pcre16_jit_callback callback, void *data);
262    
263           const unsigned char *pcre16_maketables(void);
264    
265           int pcre16_fullinfo(const pcre16 *code, const pcre16_extra *extra,
266                int what, void *where);
267    
268           int pcre16_refcount(pcre16 *code, int adjust);
269    
270           int pcre16_config(int what, void *where);
271    
272           const char *pcre16_version(void);
273    
274           int pcre16_pattern_to_host_byte_order(pcre16 *code,
275                pcre16_extra *extra, const unsigned char *tables);
276    
277    
278    PCRE 16-BIT API INDIRECTED FUNCTIONS
279    
280           void *(*pcre16_malloc)(size_t);
281    
282           void (*pcre16_free)(void *);
283    
284           void *(*pcre16_stack_malloc)(size_t);
285    
286           void (*pcre16_stack_free)(void *);
287    
288           int (*pcre16_callout)(pcre16_callout_block *);
289    
290    
291    PCRE 16-BIT API 16-BIT-ONLY FUNCTION
292    
293           int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *output,
294                PCRE_SPTR16 input, int length, int *byte_order,
295                int keep_boms);
296    
297    
298    THE PCRE 16-BIT LIBRARY
299    
300           Starting  with  release  8.30, it is possible to compile a PCRE library
301           that supports 16-bit character strings, including  UTF-16  strings,  as
302           well  as  or instead of the original 8-bit library. The majority of the
303           work to make  this  possible  was  done  by  Zoltan  Herczeg.  The  two
304           libraries contain identical sets of functions, used in exactly the same
305           way. Only the names of the functions and the data types of their  argu-
306           ments  and results are different. To avoid over-complication and reduce
307           the documentation maintenance load,  most  of  the  PCRE  documentation
308           describes  the  8-bit  library,  with only occasional references to the
309           16-bit library. This page describes what is different when you use  the
310           16-bit library.
311    
312           WARNING:  A  single  application can be linked with both libraries, but
313           you must take care when processing any particular pattern to use  func-
314           tions  from  just one library. For example, if you want to study a pat-
315           tern that was compiled with  pcre16_compile(),  you  must  do  so  with
316           pcre16_study(), not pcre_study(), and you must free the study data with
317           pcre16_free_study().
318    
319    
320    THE HEADER FILE
321    
322           There is only one header file, pcre.h. It contains prototypes  for  all
323           the functions in all libraries, as well as definitions of flags, struc-
324           tures, error codes, etc.
325    
326    
327    THE LIBRARY NAME
328    
329           In Unix-like systems, the 16-bit library is called libpcre16,  and  can
330           normally  be  accesss  by adding -lpcre16 to the command for linking an
331           application that uses PCRE.
332    
333    
334    STRING TYPES
335    
336           In the 8-bit library, strings are passed to PCRE library  functions  as
337           vectors  of  bytes  with  the  C  type "char *". In the 16-bit library,
338           strings are passed as vectors of unsigned 16-bit quantities. The  macro
339           PCRE_UCHAR16  specifies  an  appropriate  data type, and PCRE_SPTR16 is
340           defined as "const PCRE_UCHAR16 *". In very  many  environments,  "short
341           int" is a 16-bit data type. When PCRE is built, it defines PCRE_UCHAR16
342           as "unsigned short int", but checks that it really  is  a  16-bit  data
343           type.  If  it is not, the build fails with an error message telling the
344           maintainer to modify the definition appropriately.
345    
346    
347    STRUCTURE TYPES
348    
349           The types of the opaque structures that are used  for  compiled  16-bit
350           patterns  and  JIT stacks are pcre16 and pcre16_jit_stack respectively.
351           The  type  of  the  user-accessible  structure  that  is  returned   by
352           pcre16_study()  is  pcre16_extra, and the type of the structure that is
353           used for passing data to a callout  function  is  pcre16_callout_block.
354           These structures contain the same fields, with the same names, as their
355           8-bit counterparts. The only difference is that pointers  to  character
356           strings are 16-bit instead of 8-bit types.
357    
358    
359    16-BIT FUNCTIONS
360    
361           For  every function in the 8-bit library there is a corresponding func-
362           tion in the 16-bit library with a name that starts with pcre16_ instead
363           of  pcre_.  The  prototypes are listed above. In addition, there is one
364           extra function, pcre16_utf16_to_host_byte_order(). This  is  a  utility
365           function  that converts a UTF-16 character string to host byte order if
366           necessary. The other 16-bit  functions  expect  the  strings  they  are
367           passed to be in host byte order.
368    
369           The input and output arguments of pcre16_utf16_to_host_byte_order() may
370           point to the same address, that is, conversion in place  is  supported.
371           The output buffer must be at least as long as the input.
372    
373           The  length  argument  specifies the number of 16-bit data units in the
374           input string; a negative value specifies a zero-terminated string.
375    
376           If byte_order is NULL, it is assumed that the string starts off in host
377           byte  order. This may be changed by byte-order marks (BOMs) anywhere in
378           the string (commonly as the first character).
379    
380           If byte_order is not NULL, a non-zero value of the integer to which  it
381           points  means  that  the input starts off in host byte order, otherwise
382           the opposite order is assumed. Again, BOMs in  the  string  can  change
383           this. The final byte order is passed back at the end of processing.
384    
385           If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
386           copied into the output string. Otherwise they are discarded.
387    
388           The result of the function is the number of 16-bit  units  placed  into
389           the  output  buffer,  including  the  zero terminator if the string was
390           zero-terminated.
391    
392    
393    SUBJECT STRING OFFSETS
394    
395           The offsets within subject strings that are returned  by  the  matching
396           functions are in 16-bit units rather than bytes.
397    
398    
399    NAMED SUBPATTERNS
400    
401           The  name-to-number translation table that is maintained for named sub-
402           patterns uses 16-bit characters.  The  pcre16_get_stringtable_entries()
403           function returns the length of each entry in the table as the number of
404           16-bit data units.
405    
406    
407    OPTION NAMES
408    
409           There   are   two   new   general   option   names,   PCRE_UTF16    and
410           PCRE_NO_UTF16_CHECK,     which     correspond    to    PCRE_UTF8    and
411           PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
412           define  the  same bits in the options word. There is a discussion about
413           the validity of UTF-16 strings in the pcreunicode page.
414    
415           For the pcre16_config() function there is an  option  PCRE_CONFIG_UTF16
416           that  returns  1  if UTF-16 support is configured, otherwise 0. If this
417           option  is  given  to  pcre_config()  or  pcre32_config(),  or  if  the
418           PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF32  option is given to pcre16_con-
419           fig(), the result is the PCRE_ERROR_BADOPTION error.
420    
421    
422    CHARACTER CODES
423    
424           In 16-bit mode, when  PCRE_UTF16  is  not  set,  character  values  are
425           treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
426           that they can range from 0 to 0xffff instead of 0  to  0xff.  Character
427           types  for characters less than 0xff can therefore be influenced by the
428           locale in the same way as before.  Characters greater  than  0xff  have
429           only one case, and no "type" (such as letter or digit).
430    
431           In  UTF-16  mode,  the  character  code  is  Unicode, in the range 0 to
432           0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
433           because  those  are "surrogate" values that are used in pairs to encode
434           values greater than 0xffff.
435    
436           A UTF-16 string can indicate its endianness by special code knows as  a
437           byte-order mark (BOM). The PCRE functions do not handle this, expecting
438           strings  to  be  in  host  byte  order.  A  utility   function   called
439           pcre16_utf16_to_host_byte_order()  is  provided  to help with this (see
440           above).
441    
442    
443    ERROR NAMES
444    
445           The errors PCRE_ERROR_BADUTF16_OFFSET and PCRE_ERROR_SHORTUTF16  corre-
446           spond  to  their  8-bit  counterparts.  The error PCRE_ERROR_BADMODE is
447           given when a compiled pattern is passed to a  function  that  processes
448           patterns  in  the  other  mode, for example, if a pattern compiled with
449           pcre_compile() is passed to pcre16_exec().
450    
451           There are new error codes whose names  begin  with  PCRE_UTF16_ERR  for
452           invalid  UTF-16  strings,  corresponding to the PCRE_UTF8_ERR codes for
453           UTF-8 strings that are described in the section entitled "Reason  codes
454           for  invalid UTF-8 strings" in the main pcreapi page. The UTF-16 errors
455           are:
456    
457             PCRE_UTF16_ERR1  Missing low surrogate at end of string
458             PCRE_UTF16_ERR2  Invalid low surrogate follows high surrogate
459             PCRE_UTF16_ERR3  Isolated low surrogate
460             PCRE_UTF16_ERR4  Non-character
461    
462         9. Case-insensitive matching applies only to  characters  whose  values  
463         are  less than 128, unless PCRE is built with Unicode property support.  ERROR TEXTS
464         Even when Unicode property support is available, PCRE  still  uses  its  
465         own  character  tables when checking the case of low-valued characters,         If there is an error while compiling a pattern, the error text that  is
466         so as not to degrade performance.  The Unicode property information  is         passed  back by pcre16_compile() or pcre16_compile2() is still an 8-bit
467         used only for characters with higher values. Even when Unicode property         character string, zero-terminated.
468         support is available, PCRE supports case-insensitive matching only when  
469         there  is  a  one-to-one  mapping between a letter's cases. There are a  
470         small number of many-to-one mappings in Unicode;  these  are  not  sup-  CALLOUTS
471         ported by PCRE.  
472           The subject and mark fields in the callout block that is  passed  to  a
473           callout function point to 16-bit vectors.
474    
475    
476    TESTING
477    
478           The  pcretest  program continues to operate with 8-bit input and output
479           files, but it can be used for testing the 16-bit library. If it is  run
480           with the command line option -16, patterns and subject strings are con-
481           verted from 8-bit to 16-bit before being passed to PCRE, and the 16-bit
482           library  functions  are used instead of the 8-bit ones. Returned 16-bit
483           strings are converted to 8-bit for output. If both the  8-bit  and  the
484           32-bit libraries were not compiled, pcretest defaults to 16-bit and the
485           -16 option is ignored.
486    
487           When PCRE is being built, the RunTest script that is  called  by  "make
488           check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
489           16-bit and 32-bit libraries has been built, and runs the  tests  appro-
490           priately.
491    
492    
493    NOT SUPPORTED IN 16-BIT MODE
494    
495           Not all the features of the 8-bit library are available with the 16-bit
496           library. The C++ and POSIX wrapper functions  support  only  the  8-bit
497           library, and the pcregrep program is at present 8-bit only.
498    
499    
500  AUTHOR  AUTHOR
# Line 260  AUTHOR Line 503  AUTHOR
503         University Computing Service         University Computing Service
504         Cambridge CB2 3QH, England.         Cambridge CB2 3QH, England.
505    
        Putting  an actual email address here seems to have been a spam magnet,  
        so I've taken it away. If you want to email me, use  my  two  initials,  
        followed by the two digits 10, at the domain cam.ac.uk.  
   
506    
507  REVISION  REVISION
508    
509         Last updated: 12 May 2010         Last updated: 08 November 2012
510         Copyright (c) 1997-2010 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
511  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
512    
513    
514    PCRE(3)                    Library Functions Manual                    PCRE(3)
515    
516    
 PCREBUILD(3)                                                      PCREBUILD(3)  
   
517    
518  NAME  NAME
519         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
520    
521           #include <pcre.h>
522    
523    
524    PCRE 32-BIT API BASIC FUNCTIONS
525    
526           pcre32 *pcre32_compile(PCRE_SPTR32 pattern, int options,
527                const char **errptr, int *erroffset,
528                const unsigned char *tableptr);
529    
530           pcre32 *pcre32_compile2(PCRE_SPTR32 pattern, int options,
531                int *errorcodeptr,
532                const char **errptr, int *erroffset,
533                const unsigned char *tableptr);
534    
535           pcre32_extra *pcre32_study(const pcre32 *code, int options,
536                const char **errptr);
537    
538           void pcre32_free_study(pcre32_extra *extra);
539    
540           int pcre32_exec(const pcre32 *code, const pcre32_extra *extra,
541                PCRE_SPTR32 subject, int length, int startoffset,
542                int options, int *ovector, int ovecsize);
543    
544           int pcre32_dfa_exec(const pcre32 *code, const pcre32_extra *extra,
545                PCRE_SPTR32 subject, int length, int startoffset,
546                int options, int *ovector, int ovecsize,
547                int *workspace, int wscount);
548    
549    
550    PCRE 32-BIT API STRING EXTRACTION FUNCTIONS
551    
552           int pcre32_copy_named_substring(const pcre32 *code,
553                PCRE_SPTR32 subject, int *ovector,
554                int stringcount, PCRE_SPTR32 stringname,
555                PCRE_UCHAR32 *buffer, int buffersize);
556    
557           int pcre32_copy_substring(PCRE_SPTR32 subject, int *ovector,
558                int stringcount, int stringnumber, PCRE_UCHAR32 *buffer,
559                int buffersize);
560    
561           int pcre32_get_named_substring(const pcre32 *code,
562                PCRE_SPTR32 subject, int *ovector,
563                int stringcount, PCRE_SPTR32 stringname,
564                PCRE_SPTR32 *stringptr);
565    
566           int pcre32_get_stringnumber(const pcre32 *code,
567                PCRE_SPTR32 name);
568    
569           int pcre32_get_stringtable_entries(const pcre32 *code,
570                PCRE_SPTR32 name, PCRE_UCHAR32 **first, PCRE_UCHAR32 **last);
571    
572           int pcre32_get_substring(PCRE_SPTR32 subject, int *ovector,
573                int stringcount, int stringnumber,
574                PCRE_SPTR32 *stringptr);
575    
576           int pcre32_get_substring_list(PCRE_SPTR32 subject,
577                int *ovector, int stringcount, PCRE_SPTR32 **listptr);
578    
579           void pcre32_free_substring(PCRE_SPTR32 stringptr);
580    
581           void pcre32_free_substring_list(PCRE_SPTR32 *stringptr);
582    
583    
584    PCRE 32-BIT API AUXILIARY FUNCTIONS
585    
586           pcre32_jit_stack *pcre32_jit_stack_alloc(int startsize, int maxsize);
587    
588           void pcre32_jit_stack_free(pcre32_jit_stack *stack);
589    
590           void pcre32_assign_jit_stack(pcre32_extra *extra,
591                pcre32_jit_callback callback, void *data);
592    
593           const unsigned char *pcre32_maketables(void);
594    
595           int pcre32_fullinfo(const pcre32 *code, const pcre32_extra *extra,
596                int what, void *where);
597    
598           int pcre32_refcount(pcre32 *code, int adjust);
599    
600           int pcre32_config(int what, void *where);
601    
602           const char *pcre32_version(void);
603    
604           int pcre32_pattern_to_host_byte_order(pcre32 *code,
605                pcre32_extra *extra, const unsigned char *tables);
606    
607    
608    PCRE 32-BIT API INDIRECTED FUNCTIONS
609    
610           void *(*pcre32_malloc)(size_t);
611    
612           void (*pcre32_free)(void *);
613    
614           void *(*pcre32_stack_malloc)(size_t);
615    
616           void (*pcre32_stack_free)(void *);
617    
618           int (*pcre32_callout)(pcre32_callout_block *);
619    
620    
621    PCRE 32-BIT API 32-BIT-ONLY FUNCTION
622    
623           int pcre32_utf32_to_host_byte_order(PCRE_UCHAR32 *output,
624                PCRE_SPTR32 input, int length, int *byte_order,
625                int keep_boms);
626    
627    
628    THE PCRE 32-BIT LIBRARY
629    
630           Starting  with  release  8.32, it is possible to compile a PCRE library
631           that supports 32-bit character strings, including  UTF-32  strings,  as
632           well as or instead of the original 8-bit library. This work was done by
633           Christian Persch, based on the work done  by  Zoltan  Herczeg  for  the
634           16-bit  library.  All  three  libraries contain identical sets of func-
635           tions, used in exactly the same way.  Only the names of  the  functions
636           and  the  data  types  of their arguments and results are different. To
637           avoid over-complication and reduce the documentation maintenance  load,
638           most  of  the PCRE documentation describes the 8-bit library, with only
639           occasional references to the 16-bit and  32-bit  libraries.  This  page
640           describes what is different when you use the 32-bit library.
641    
642           WARNING:  A  single  application  can  be linked with all or any of the
643           three libraries, but you must take care when processing any  particular
644           pattern  to  use  functions  from just one library. For example, if you
645           want to study a pattern that was compiled  with  pcre32_compile(),  you
646           must do so with pcre32_study(), not pcre_study(), and you must free the
647           study data with pcre32_free_study().
648    
649    
650    THE HEADER FILE
651    
652           There is only one header file, pcre.h. It contains prototypes  for  all
653           the functions in all libraries, as well as definitions of flags, struc-
654           tures, error codes, etc.
655    
656    
657    THE LIBRARY NAME
658    
659           In Unix-like systems, the 32-bit library is called libpcre32,  and  can
660           normally  be  accesss  by adding -lpcre32 to the command for linking an
661           application that uses PCRE.
662    
663    
664    STRING TYPES
665    
666           In the 8-bit library, strings are passed to PCRE library  functions  as
667           vectors  of  bytes  with  the  C  type "char *". In the 32-bit library,
668           strings are passed as vectors of unsigned 32-bit quantities. The  macro
669           PCRE_UCHAR32  specifies  an  appropriate  data type, and PCRE_SPTR32 is
670           defined as "const PCRE_UCHAR32 *". In very many environments, "unsigned
671           int" is a 32-bit data type. When PCRE is built, it defines PCRE_UCHAR32
672           as "unsigned int", but checks that it really is a 32-bit data type.  If
673           it is not, the build fails with an error message telling the maintainer
674           to modify the definition appropriately.
675    
676    
677    STRUCTURE TYPES
678    
679           The types of the opaque structures that are used  for  compiled  32-bit
680           patterns  and  JIT stacks are pcre32 and pcre32_jit_stack respectively.
681           The  type  of  the  user-accessible  structure  that  is  returned   by
682           pcre32_study()  is  pcre32_extra, and the type of the structure that is
683           used for passing data to a callout  function  is  pcre32_callout_block.
684           These structures contain the same fields, with the same names, as their
685           8-bit counterparts. The only difference is that pointers  to  character
686           strings are 32-bit instead of 8-bit types.
687    
688    
689    32-BIT FUNCTIONS
690    
691           For  every function in the 8-bit library there is a corresponding func-
692           tion in the 32-bit library with a name that starts with pcre32_ instead
693           of  pcre_.  The  prototypes are listed above. In addition, there is one
694           extra function, pcre32_utf32_to_host_byte_order(). This  is  a  utility
695           function  that converts a UTF-32 character string to host byte order if
696           necessary. The other 32-bit  functions  expect  the  strings  they  are
697           passed to be in host byte order.
698    
699           The input and output arguments of pcre32_utf32_to_host_byte_order() may
700           point to the same address, that is, conversion in place  is  supported.
701           The output buffer must be at least as long as the input.
702    
703           The  length  argument  specifies the number of 32-bit data units in the
704           input string; a negative value specifies a zero-terminated string.
705    
706           If byte_order is NULL, it is assumed that the string starts off in host
707           byte  order. This may be changed by byte-order marks (BOMs) anywhere in
708           the string (commonly as the first character).
709    
710           If byte_order is not NULL, a non-zero value of the integer to which  it
711           points  means  that  the input starts off in host byte order, otherwise
712           the opposite order is assumed. Again, BOMs in  the  string  can  change
713           this. The final byte order is passed back at the end of processing.
714    
715           If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
716           copied into the output string. Otherwise they are discarded.
717    
718           The result of the function is the number of 32-bit  units  placed  into
719           the  output  buffer,  including  the  zero terminator if the string was
720           zero-terminated.
721    
722    
723    SUBJECT STRING OFFSETS
724    
725           The offsets within subject strings that are returned  by  the  matching
726           functions are in 32-bit units rather than bytes.
727    
728    
729    NAMED SUBPATTERNS
730    
731           The  name-to-number translation table that is maintained for named sub-
732           patterns uses 32-bit characters.  The  pcre32_get_stringtable_entries()
733           function returns the length of each entry in the table as the number of
734           32-bit data units.
735    
736    
737    OPTION NAMES
738    
739           There   are   two   new   general   option   names,   PCRE_UTF32    and
740           PCRE_NO_UTF32_CHECK,     which     correspond    to    PCRE_UTF8    and
741           PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
742           define  the  same bits in the options word. There is a discussion about
743           the validity of UTF-32 strings in the pcreunicode page.
744    
745           For the pcre32_config() function there is an  option  PCRE_CONFIG_UTF32
746           that  returns  1  if UTF-32 support is configured, otherwise 0. If this
747           option  is  given  to  pcre_config()  or  pcre16_config(),  or  if  the
748           PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF16  option is given to pcre32_con-
749           fig(), the result is the PCRE_ERROR_BADOPTION error.
750    
751    
752    CHARACTER CODES
753    
754           In 32-bit mode, when  PCRE_UTF32  is  not  set,  character  values  are
755           treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
756           that they can range from 0 to 0x7fffffff instead of 0 to 0xff.  Charac-
757           ter  types for characters less than 0xff can therefore be influenced by
758           the locale in the same way as before.   Characters  greater  than  0xff
759           have only one case, and no "type" (such as letter or digit).
760    
761           In  UTF-32  mode,  the  character  code  is  Unicode, in the range 0 to
762           0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
763           because those are "surrogate" values that are ill-formed in UTF-32.
764    
765           A  UTF-32 string can indicate its endianness by special code knows as a
766           byte-order mark (BOM). The PCRE functions do not handle this, expecting
767           strings   to   be  in  host  byte  order.  A  utility  function  called
768           pcre32_utf32_to_host_byte_order() is provided to help  with  this  (see
769           above).
770    
771    
772    ERROR NAMES
773    
774           The  error  PCRE_ERROR_BADUTF32  corresponds  to its 8-bit counterpart.
775           The error PCRE_ERROR_BADMODE is given when a compiled pattern is passed
776           to  a  function that processes patterns in the other mode, for example,
777           if a pattern compiled with pcre_compile() is passed to pcre32_exec().
778    
779           There are new error codes whose names  begin  with  PCRE_UTF32_ERR  for
780           invalid  UTF-32  strings,  corresponding to the PCRE_UTF8_ERR codes for
781           UTF-8 strings that are described in the section entitled "Reason  codes
782           for  invalid UTF-8 strings" in the main pcreapi page. The UTF-32 errors
783           are:
784    
785             PCRE_UTF32_ERR1  Surrogate character (range from 0xd800 to 0xdfff)
786             PCRE_UTF32_ERR2  Non-character
787             PCRE_UTF32_ERR3  Character > 0x10ffff
788    
789    
790    ERROR TEXTS
791    
792           If there is an error while compiling a pattern, the error text that  is
793           passed  back by pcre32_compile() or pcre32_compile2() is still an 8-bit
794           character string, zero-terminated.
795    
796    
797    CALLOUTS
798    
799           The subject and mark fields in the callout block that is  passed  to  a
800           callout function point to 32-bit vectors.
801    
802    
803    TESTING
804    
805           The  pcretest  program continues to operate with 8-bit input and output
806           files, but it can be used for testing the 32-bit library. If it is  run
807           with the command line option -32, patterns and subject strings are con-
808           verted from 8-bit to 32-bit before being passed to PCRE, and the 32-bit
809           library  functions  are used instead of the 8-bit ones. Returned 32-bit
810           strings are converted to 8-bit for output. If both the  8-bit  and  the
811           16-bit libraries were not compiled, pcretest defaults to 32-bit and the
812           -32 option is ignored.
813    
814           When PCRE is being built, the RunTest script that is  called  by  "make
815           check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
816           16-bit and 32-bit libraries has been built, and runs the  tests  appro-
817           priately.
818    
819    
820    NOT SUPPORTED IN 32-BIT MODE
821    
822           Not all the features of the 8-bit library are available with the 32-bit
823           library. The C++ and POSIX wrapper functions  support  only  the  8-bit
824           library, and the pcregrep program is at present 8-bit only.
825    
826    
827    AUTHOR
828    
829           Philip Hazel
830           University Computing Service
831           Cambridge CB2 3QH, England.
832    
833    
834    REVISION
835    
836           Last updated: 08 November 2012
837           Copyright (c) 1997-2012 University of Cambridge.
838    ------------------------------------------------------------------------------
839    
840    
841    PCREBUILD(3)               Library Functions Manual               PCREBUILD(3)
842    
843    
844    
845    NAME
846           PCRE - Perl-compatible regular expressions
847    
848  PCRE BUILD-TIME OPTIONS  PCRE BUILD-TIME OPTIONS
849    
# Line 289  PCRE BUILD-TIME OPTIONS Line 855  PCRE BUILD-TIME OPTIONS
855         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
856         instead of configure to build PCRE.         instead of configure to build PCRE.
857    
858         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-
859         environments in the file called NON_UNIX_USE, which is part of the PCRE         figure (including information about using CMake or building "by  hand")
860         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-
861         if you are building in a non-Unix-like environment.         tribution. You should consult this file as well as the README  file  if
862           you are building in a non-Unix-like environment.
863    
864         The complete list of options for configure (which includes the standard         The complete list of options for configure (which includes the standard
865         ones  such  as  the  selection  of  the  installation directory) can be         ones such as the  selection  of  the  installation  directory)  can  be
866         obtained by running         obtained by running
867    
868           ./configure --help           ./configure --help
869    
870         The following sections include  descriptions  of  options  whose  names         The  following  sections  include  descriptions  of options whose names
871         begin with --enable or --disable. These settings specify changes to the         begin with --enable or --disable. These settings specify changes to the
872         defaults for the configure command. Because of the way  that  configure         defaults  for  the configure command. Because of the way that configure
873         works,  --enable  and --disable always come in pairs, so the complemen-         works, --enable and --disable always come in pairs, so  the  complemen-
874         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
875         is not described.         is not described.
876    
877    
878    BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES
879    
880           By default, a library called libpcre  is  built,  containing  functions
881           that  take  string  arguments  contained in vectors of bytes, either as
882           single-byte characters, or interpreted as UTF-8 strings. You  can  also
883           build  a  separate library, called libpcre16, in which strings are con-
884           tained in vectors of 16-bit data units and interpreted either  as  sin-
885           gle-unit characters or UTF-16 strings, by adding
886    
887             --enable-pcre16
888    
889           to the configure command. You can also build a separate library, called
890           libpcre32, in which strings are contained in  vectors  of  32-bit  data
891           units  and  interpreted  either  as  single-unit  characters  or UTF-32
892           strings, by adding
893    
894             --enable-pcre32
895    
896           to the configure command. If you do not want the 8-bit library, add
897    
898             --disable-pcre8
899    
900           as well. At least one of the three libraries must be built.  Note  that
901           the  C++  and  POSIX  wrappers are for the 8-bit library only, and that
902           pcregrep is an 8-bit program. None of these are  built  if  you  select
903           only the 16-bit or 32-bit libraries.
904    
905    
906    BUILDING SHARED AND STATIC LIBRARIES
907    
908           The  PCRE building process uses libtool to build both shared and static
909           Unix libraries by default. You can suppress one of these by adding  one
910           of
911    
912             --disable-shared
913             --disable-static
914    
915           to the configure command, as required.
916    
917    
918  C++ SUPPORT  C++ SUPPORT
919    
920         By default, the configure script will search for a C++ compiler and C++         By  default,  if the 8-bit library is being built, the configure script
921         header files. If it finds them, it automatically builds the C++ wrapper         will search for a C++ compiler and C++ header files. If it finds  them,
922         library for PCRE. You can disable this by adding         it  automatically  builds  the C++ wrapper library (which supports only
923           8-bit strings). You can disable this by adding
924    
925           --disable-cpp           --disable-cpp
926    
927         to the configure command.         to the configure command.
928    
929    
930  UTF-8 SUPPORT  UTF-8, UTF-16 AND UTF-32 SUPPORT
931    
932         To build PCRE with support for UTF-8 Unicode character strings, add         To build PCRE with support for UTF Unicode character strings, add
933    
934           --enable-utf8           --enable-utf
935    
936         to  the  configure  command.  Of  itself, this does not make PCRE treat         to the configure command. This setting applies to all three  libraries,
937         strings as UTF-8. As well as compiling PCRE with this option, you  also         adding  support  for  UTF-8 to the 8-bit library, support for UTF-16 to
938         have  have to set the PCRE_UTF8 option when you call the pcre_compile()         the 16-bit library, and  support  for  UTF-32  to  the  to  the  32-bit
939         or pcre_compile2() functions.         library.  There  are no separate options for enabling UTF-8, UTF-16 and
940           UTF-32 independently because that would allow ridiculous settings  such
941         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
942         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-
943         option). It is not possible to support both EBCDIC and UTF-8  codes  in         out  in the same configuration. (For backwards compatibility, --enable-
944         the  same  version  of  the  library.  Consequently,  --enable-utf8 and         utf8 is a synonym of --enable-utf.)
945    
946           Of itself, this setting does not make  PCRE  treat  strings  as  UTF-8,
947           UTF-16  or UTF-32. As well as compiling PCRE with this option, you also
948           have have to set the PCRE_UTF8, PCRE_UTF16  or  PCRE_UTF32  option  (as
949           appropriate) when you call one of the pattern compiling functions.
950    
951           If  you  set --enable-utf when compiling in an EBCDIC environment, PCRE
952           expects its input to be either ASCII or UTF-8 (depending  on  the  run-
953           time option). It is not possible to support both EBCDIC and UTF-8 codes
954           in the same version of  the  library.  Consequently,  --enable-utf  and
955         --enable-ebcdic are mutually exclusive.         --enable-ebcdic are mutually exclusive.
956    
957    
958  UNICODE CHARACTER PROPERTY SUPPORT  UNICODE CHARACTER PROPERTY SUPPORT
959    
960         UTF-8 support allows PCRE to process character values greater than  255         UTF  support allows the libraries to process character codepoints up to
961         in  the  strings that it handles. On its own, however, it does not pro-         0x10ffff in the strings that they handle. On its own, however, it  does
962         vide any facilities for accessing the properties of such characters. If         not provide any facilities for accessing the properties of such charac-
963         you  want  to  be able to use the pattern escapes \P, \p, and \X, which         ters. If you want to be able to use the pattern escapes \P, \p, and \X,
964         refer to Unicode character properties, you must add         which refer to Unicode character properties, you must add
965    
966           --enable-unicode-properties           --enable-unicode-properties
967    
968         to the configure command. This implies UTF-8 support, even if you  have         to  the  configure  command. This implies UTF support, even if you have
969         not explicitly requested it.         not explicitly requested it.
970    
971         Including  Unicode  property  support  adds around 30K of tables to the         Including Unicode property support adds around 30K  of  tables  to  the
972         PCRE library. Only the general category properties such as  Lu  and  Nd         PCRE  library.  Only  the general category properties such as Lu and Nd
973         are supported. Details are given in the pcrepattern documentation.         are supported. Details are given in the pcrepattern documentation.
974    
975    
976    JUST-IN-TIME COMPILER SUPPORT
977    
978           Just-in-time compiler support is included in the build by specifying
979    
980             --enable-jit
981    
982           This support is available only for certain hardware  architectures.  If
983           this  option  is  set  for  an unsupported architecture, a compile time
984           error occurs.  See the pcrejit documentation for a  discussion  of  JIT
985           usage. When JIT support is enabled, pcregrep automatically makes use of
986           it, unless you add
987    
988             --disable-pcregrep-jit
989    
990           to the "configure" command.
991    
992    
993  CODE VALUE OF NEWLINE  CODE VALUE OF NEWLINE
994    
995         By  default,  PCRE interprets the linefeed (LF) character as indicating         By default, PCRE interprets the linefeed (LF) character  as  indicating
996         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
997         systems.  You  can compile PCRE to use carriage return (CR) instead, by         systems. You can compile PCRE to use carriage return (CR)  instead,  by
998         adding         adding
999    
1000           --enable-newline-is-cr           --enable-newline-is-cr
1001    
1002         to the  configure  command.  There  is  also  a  --enable-newline-is-lf         to  the  configure  command.  There  is  also  a --enable-newline-is-lf
1003         option, which explicitly specifies linefeed as the newline character.         option, which explicitly specifies linefeed as the newline character.
1004    
1005         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 1011  CODE VALUE OF NEWLINE
1011    
1012           --enable-newline-is-anycrlf           --enable-newline-is-anycrlf
1013    
1014         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
1015         CRLF as indicating a line ending. Finally, a fifth option, specified by         CRLF as indicating a line ending. Finally, a fifth option, specified by
1016    
1017           --enable-newline-is-any           --enable-newline-is-any
1018    
1019         causes PCRE to recognize any Unicode newline sequence.         causes PCRE to recognize any Unicode newline sequence.
1020    
1021         Whatever  line  ending convention is selected when PCRE is built can be         Whatever line ending convention is selected when PCRE is built  can  be
1022         overridden when the library functions are called. At build time  it  is         overridden  when  the library functions are called. At build time it is
1023         conventional to use the standard for your operating system.         conventional to use the standard for your operating system.
1024    
1025    
1026  WHAT \R MATCHES  WHAT \R MATCHES
1027    
1028         By  default,  the  sequence \R in a pattern matches any Unicode newline         By default, the sequence \R in a pattern matches  any  Unicode  newline
1029         sequence, whatever has been selected as the line  ending  sequence.  If         sequence,  whatever  has  been selected as the line ending sequence. If
1030         you specify         you specify
1031    
1032           --enable-bsr-anycrlf           --enable-bsr-anycrlf
1033    
1034         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-
1035         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
1036         functions are called.         functions are called.
1037    
1038    
 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.  
   
   
1039  POSIX MALLOC USAGE  POSIX MALLOC USAGE
1040    
1041         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
1042         umentation), additional working storage is  required  for  holding  the         pcreposix  documentation),  additional  working storage is required for
1043         pointers  to capturing substrings, because PCRE requires three integers         holding the pointers to capturing  substrings,  because  PCRE  requires
1044         per substring, whereas the POSIX interface provides only  two.  If  the         three integers per substring, whereas the POSIX interface provides only
1045         number of expected substrings is small, the wrapper function uses space         two. If the number of expected substrings is small, the  wrapper  func-
1046         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-
1047         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
1048         can be changed by adding a setting such as         longer used is 10; it can be changed by adding a setting such as
1049    
1050           --with-posix-malloc-threshold=20           --with-posix-malloc-threshold=20
1051    
# Line 431  POSIX MALLOC USAGE Line 1054  POSIX MALLOC USAGE
1054    
1055  HANDLING VERY LARGE PATTERNS  HANDLING VERY LARGE PATTERNS
1056    
1057         Within a compiled pattern, offset values are used  to  point  from  one         Within  a  compiled  pattern,  offset values are used to point from one
1058         part  to another (for example, from an opening parenthesis to an alter-         part to another (for example, from an opening parenthesis to an  alter-
1059         nation metacharacter). By default, two-byte values are used  for  these         nation  metacharacter).  By default, in the 8-bit and 16-bit libraries,
1060         offsets,  leading  to  a  maximum size for a compiled pattern of around         two-byte values are used for these offsets, leading to a  maximum  size
1061         64K. This is sufficient to handle all but the most  gigantic  patterns.         for  a compiled pattern of around 64K. This is sufficient to handle all
1062         Nevertheless,  some  people do want to process truyl enormous patterns,         but the most gigantic patterns.  Nevertheless, some people do  want  to
1063         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
1064         sets by adding a setting such as         use three-byte or four-byte offsets by adding a setting such as
1065    
1066           --with-link-size=3           --with-link-size=3
1067    
1068         to  the  configure  command.  The value given must be 2, 3, or 4. Using         to the configure command. The value given must be 2, 3, or 4.  For  the
1069         longer offsets slows down the operation of PCRE because it has to  load         16-bit  library,  a  value of 3 is rounded up to 4. In these libraries,
1070         additional bytes when handling them.         using longer offsets slows down the operation of PCRE because it has to
1071           load  additional  data  when  handling them. For the 32-bit library the
1072           value is always 4 and cannot be overridden; the value  of  --with-link-
1073           size is ignored.
1074    
1075    
1076  AVOIDING EXCESSIVE STACK USAGE  AVOIDING EXCESSIVE STACK USAGE
# Line 518  CREATING CHARACTER TABLES AT BUILD TIME Line 1144  CREATING CHARACTER TABLES AT BUILD TIME
1144         to  the  configure  command, the distributed tables are no longer used.         to  the  configure  command, the distributed tables are no longer used.
1145         Instead, a program called dftables is compiled and  run.  This  outputs         Instead, a program called dftables is compiled and  run.  This  outputs
1146         the source for new set of tables, created in the default locale of your         the source for new set of tables, created in the default locale of your
1147         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
1148         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.
1149         you need to create alternative tables when cross  compiling,  you  will         If you need to create alternative tables when cross compiling, you will
1150         have to do so "by hand".)         have to do so "by hand".)
1151    
1152    
# Line 536  USING EBCDIC CODE Line 1162  USING EBCDIC CODE
1162         to the configure command. This setting implies --enable-rebuild-charta-         to the configure command. This setting implies --enable-rebuild-charta-
1163         bles.  You  should  only  use  it if you know that you are in an EBCDIC         bles.  You  should  only  use  it if you know that you are in an EBCDIC
1164         environment (for example,  an  IBM  mainframe  operating  system).  The         environment (for example,  an  IBM  mainframe  operating  system).  The
1165         --enable-ebcdic option is incompatible with --enable-utf8.         --enable-ebcdic option is incompatible with --enable-utf.
1166    
1167           The EBCDIC character that corresponds to an ASCII LF is assumed to have
1168           the value 0x15 by default. However, in some EBCDIC  environments,  0x25
1169           is used. In such an environment you should use
1170    
1171             --enable-ebcdic-nl25
1172    
1173           as well as, or instead of, --enable-ebcdic. The EBCDIC character for CR
1174           has the same value as in ASCII, namely, 0x0d.  Whichever  of  0x15  and
1175           0x25 is not chosen as LF is made to correspond to the Unicode NEL char-
1176           acter (which, in Unicode, is 0x85).
1177    
1178           The options that select newline behaviour, such as --enable-newline-is-
1179           cr, and equivalent run-time options, refer to these character values in
1180           an EBCDIC environment.
1181    
1182    
1183  PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT  PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT
# Line 549  PCREGREP OPTIONS FOR COMPRESSED FILE SUP Line 1190  PCREGREP OPTIONS FOR COMPRESSED FILE SUP
1190           --enable-pcregrep-libbz2           --enable-pcregrep-libbz2
1191    
1192         to the configure command. These options naturally require that the rel-         to the configure command. These options naturally require that the rel-
1193         evant libraries are installed on your system. Configuration  will  fail         evant  libraries  are installed on your system. Configuration will fail
1194         if they are not.         if they are not.
1195    
1196    
1197    PCREGREP BUFFER SIZE
1198    
1199           pcregrep uses an internal buffer to hold a "window" on the file  it  is
1200           scanning, in order to be able to output "before" and "after" lines when
1201           it finds a match. The size of the buffer is controlled by  a  parameter
1202           whose default value is 20K. The buffer itself is three times this size,
1203           but because of the way it is used for holding "before" lines, the long-
1204           est  line  that  is guaranteed to be processable is the parameter size.
1205           You can change the default parameter value by adding, for example,
1206    
1207             --with-pcregrep-bufsize=50K
1208    
1209           to the configure command. The caller of pcregrep can, however, override
1210           this value by specifying a run-time option.
1211    
1212    
1213  PCRETEST OPTION FOR LIBREADLINE SUPPORT  PCRETEST OPTION FOR LIBREADLINE SUPPORT
1214    
1215         If you add         If you add
# Line 584  PCRETEST OPTION FOR LIBREADLINE SUPPORT Line 1241  PCRETEST OPTION FOR LIBREADLINE SUPPORT
1241         immediately before the configure command.         immediately before the configure command.
1242    
1243    
1244    DEBUGGING WITH VALGRIND SUPPORT
1245    
1246           By adding the
1247    
1248             --enable-valgrind
1249    
1250           option  to to the configure command, PCRE will use valgrind annotations
1251           to mark certain memory regions as  unaddressable.  This  allows  it  to
1252           detect invalid memory accesses, and is mostly useful for debugging PCRE
1253           itself.
1254    
1255    
1256    CODE COVERAGE REPORTING
1257    
1258           If your C compiler is gcc, you can build a version  of  PCRE  that  can
1259           generate a code coverage report for its test suite. To enable this, you
1260           must install lcov version 1.6 or above. Then specify
1261    
1262             --enable-coverage
1263    
1264           to the configure command and build PCRE in the usual way.
1265    
1266           Note that using ccache (a caching C compiler) is incompatible with code
1267           coverage  reporting. If you have configured ccache to run automatically
1268           on your system, you must set the environment variable
1269    
1270             CCACHE_DISABLE=1
1271    
1272           before running make to build PCRE, so that ccache is not used.
1273    
1274           When --enable-coverage is used,  the  following  addition  targets  are
1275           added to the Makefile:
1276    
1277             make coverage
1278    
1279           This  creates  a  fresh  coverage report for the PCRE test suite. It is
1280           equivalent to running "make coverage-reset", "make  coverage-baseline",
1281           "make check", and then "make coverage-report".
1282    
1283             make coverage-reset
1284    
1285           This zeroes the coverage counters, but does nothing else.
1286    
1287             make coverage-baseline
1288    
1289           This captures baseline coverage information.
1290    
1291             make coverage-report
1292    
1293           This creates the coverage report.
1294    
1295             make coverage-clean-report
1296    
1297           This  removes the generated coverage report without cleaning the cover-
1298           age data itself.
1299    
1300             make coverage-clean-data
1301    
1302           This removes the captured coverage data without removing  the  coverage
1303           files created at compile time (*.gcno).
1304    
1305             make coverage-clean
1306    
1307           This  cleans all coverage data including the generated coverage report.
1308           For more information about code coverage, see the gcov and  lcov  docu-
1309           mentation.
1310    
1311    
1312  SEE ALSO  SEE ALSO
1313    
1314         pcreapi(3), pcre_config(3).         pcreapi(3), pcre16, pcre32, pcre_config(3).
1315    
1316    
1317  AUTHOR  AUTHOR
# Line 598  AUTHOR Line 1323  AUTHOR
1323    
1324  REVISION  REVISION
1325    
1326         Last updated: 29 September 2009         Last updated: 30 October 2012
1327         Copyright (c) 1997-2009 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
1328  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1329    
1330    
1331    PCREMATCHING(3)            Library Functions Manual            PCREMATCHING(3)
1332    
1333    
 PCREMATCHING(3)                                                PCREMATCHING(3)  
   
1334    
1335  NAME  NAME
1336         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
1337    
   
1338  PCRE MATCHING ALGORITHMS  PCRE MATCHING ALGORITHMS
1339    
1340         This document describes the two different algorithms that are available         This document describes the two different algorithms that are available
1341         in PCRE for matching a compiled regular expression against a given sub-         in PCRE for matching a compiled regular expression against a given sub-
1342         ject  string.  The  "standard"  algorithm  is  the  one provided by the         ject  string.  The  "standard"  algorithm  is  the  one provided by the
1343         pcre_exec() function.  This works in the same was  as  Perl's  matching         pcre_exec(), pcre16_exec() and pcre32_exec() functions. These  work  in
1344         function, and provides a Perl-compatible matching operation.         the  same as as Perl's matching function, and provide a Perl-compatible
1345           matching  operation.   The  just-in-time  (JIT)  optimization  that  is
1346         An  alternative  algorithm is provided by the pcre_dfa_exec() function;         described  in  the pcrejit documentation is compatible with these func-
1347         this operates in a different way, and is not  Perl-compatible.  It  has         tions.
1348         advantages  and disadvantages compared with the standard algorithm, and  
1349         these are described below.         An  alternative  algorithm  is   provided   by   the   pcre_dfa_exec(),
1350           pcre16_dfa_exec()  and  pcre32_dfa_exec()  functions; they operate in a
1351           different way, and are not Perl-compatible. This alternative has advan-
1352           tages and disadvantages compared with the standard algorithm, and these
1353           are described below.
1354    
1355         When there is only one possible way in which a given subject string can         When there is only one possible way in which a given subject string can
1356         match  a pattern, the two algorithms give the same answer. A difference         match  a pattern, the two algorithms give the same answer. A difference
# Line 697  THE ALTERNATIVE MATCHING ALGORITHM Line 1426  THE ALTERNATIVE MATCHING ALGORITHM
1426         represent the different matching possibilities (if there are none,  the         represent the different matching possibilities (if there are none,  the
1427         match  has  failed).   Thus,  if there is more than one possible match,         match  has  failed).   Thus,  if there is more than one possible match,
1428         this algorithm finds all of them, and in particular, it finds the long-         this algorithm finds all of them, and in particular, it finds the long-
1429         est.  There  is  an  option to stop the algorithm after the first match         est.  The  matches are returned in decreasing order of length. There is
1430         (which is necessarily the shortest) is found.         an option to stop the algorithm after the first match (which is  neces-
1431           sarily the shortest) is found.
1432    
1433         Note that all the matches that are found start at the same point in the         Note that all the matches that are found start at the same point in the
1434         subject. If the pattern         subject. If the pattern
1435    
1436           cat(er(pillar)?)           cat(er(pillar)?)?
1437    
1438         is  matched  against the string "the caterpillar catchment", the result         is matched against the string "the caterpillar catchment",  the  result
1439         will be the three strings "cat", "cater", and "caterpillar" that  start         will  be the three strings "caterpillar", "cater", and "cat" that start
1440         at the fourth character of the subject. The algorithm does not automat-         at the fifth character of the subject. The algorithm does not automati-
1441         ically move on to find matches that start at later positions.         cally move on to find matches that start at later positions.
1442    
1443         There are a number of features of PCRE regular expressions that are not         There are a number of features of PCRE regular expressions that are not
1444         supported by the alternative matching algorithm. They are as follows:         supported by the alternative matching algorithm. They are as follows:
1445    
1446         1.  Because  the  algorithm  finds  all possible matches, the greedy or         1. Because the algorithm finds all  possible  matches,  the  greedy  or
1447         ungreedy nature of repetition quantifiers is not relevant.  Greedy  and         ungreedy  nature  of repetition quantifiers is not relevant. Greedy and
1448         ungreedy quantifiers are treated in exactly the same way. However, pos-         ungreedy quantifiers are treated in exactly the same way. However, pos-
1449         sessive quantifiers can make a difference when what follows could  also         sessive  quantifiers can make a difference when what follows could also
1450         match what is quantified, for example in a pattern like this:         match what is quantified, for example in a pattern like this:
1451    
1452           ^a++\w!           ^a++\w!
1453    
1454         This  pattern matches "aaab!" but not "aaa!", which would be matched by         This pattern matches "aaab!" but not "aaa!", which would be matched  by
1455         a non-possessive quantifier. Similarly, if an atomic group is  present,         a  non-possessive quantifier. Similarly, if an atomic group is present,
1456         it  is matched as if it were a standalone pattern at the current point,         it is matched as if it were a standalone pattern at the current  point,
1457         and the longest match is then "locked in" for the rest of  the  overall         and  the  longest match is then "locked in" for the rest of the overall
1458         pattern.         pattern.
1459    
1460         2. When dealing with multiple paths through the tree simultaneously, it         2. When dealing with multiple paths through the tree simultaneously, it
1461         is not straightforward to keep track of  captured  substrings  for  the         is  not  straightforward  to  keep track of captured substrings for the
1462         different  matching  possibilities,  and  PCRE's implementation of this         different matching possibilities, and  PCRE's  implementation  of  this
1463         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-
1464         strings are available.         strings are available.
1465    
1466         3.  Because no substrings are captured, back references within the pat-         3. Because no substrings are captured, back references within the  pat-
1467         tern are not supported, and cause errors if encountered.         tern are not supported, and cause errors if encountered.
1468    
1469         4. For the same reason, conditional expressions that use  a  backrefer-         4.  For  the same reason, conditional expressions that use a backrefer-
1470         ence  as  the  condition or test for a specific group recursion are not         ence as the condition or test for a specific group  recursion  are  not
1471         supported.         supported.
1472    
1473         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
1474         sequence, which resets the start of the match when encountered (but may         sequence, which resets the start of the match when encountered (but may
1475         be on some paths and not on others), is not  supported.  It  causes  an         be  on  some  paths  and not on others), is not supported. It causes an
1476         error if encountered.         error if encountered.
1477    
1478         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
1479         always 1, and the value of the capture_last field is always -1.         always 1, and the value of the capture_last field is always -1.
1480    
1481         7. The \C escape sequence, which (in the standard algorithm) matches  a         7.  The  \C  escape  sequence, which (in the standard algorithm) always
1482         single  byte, even in UTF-8 mode, is not supported because the alterna-         matches a single data unit, even in UTF-8, UTF-16 or UTF-32  modes,  is
1483         tive algorithm moves through the subject  string  one  character  at  a         not  supported  in these modes, because the alternative algorithm moves
1484         time, for all active paths through the tree.         through the subject string one character (not data unit) at a time, for
1485           all active paths through the tree.
1486    
1487         8.  Except for (*FAIL), the backtracking control verbs such as (*PRUNE)         8.  Except for (*FAIL), the backtracking control verbs such as (*PRUNE)
1488         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 1500  ADVANTAGES OF THE ALTERNATIVE ALGORITHM
1500         things with callouts.         things with callouts.
1501    
1502         2.  Because  the  alternative  algorithm  scans the subject string just         2.  Because  the  alternative  algorithm  scans the subject string just
1503         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-
1504         subject  strings  to  the matching function in several pieces, checking         sible  to  pass  very  long subject strings to the matching function in
1505         for partial matching each time.  The  pcrepartial  documentation  gives         several pieces, checking for partial matching each time. Although it is
1506         details of partial matching.         possible  to  do multi-segment matching using the standard algorithm by
1507           retaining partially matched substrings, it  is  more  complicated.  The
1508           pcrepartial  documentation  gives  details of partial matching and dis-
1509           cusses multi-segment matching.
1510    
1511    
1512  DISADVANTAGES OF THE ALTERNATIVE ALGORITHM  DISADVANTAGES OF THE ALTERNATIVE ALGORITHM
1513    
1514         The alternative algorithm suffers from a number of disadvantages:         The alternative algorithm suffers from a number of disadvantages:
1515    
1516         1.  It  is  substantially  slower  than the standard algorithm. This is         1. It is substantially slower than  the  standard  algorithm.  This  is
1517         partly because it has to search for all possible matches, but  is  also         partly  because  it has to search for all possible matches, but is also
1518         because it is less susceptible to optimization.         because it is less susceptible to optimization.
1519    
1520         2. Capturing parentheses and back references are not supported.         2. Capturing parentheses and back references are not supported.
# Line 798  AUTHOR Line 1532  AUTHOR
1532    
1533  REVISION  REVISION
1534    
1535         Last updated: 29 September 2009         Last updated: 08 January 2012
1536         Copyright (c) 1997-2009 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
1537  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1538    
1539    
1540    PCREAPI(3)                 Library Functions Manual                 PCREAPI(3)
1541    
1542    
 PCREAPI(3)                                                          PCREAPI(3)  
   
1543    
1544  NAME  NAME
1545         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
1546    
1547           #include <pcre.h>
1548    
 PCRE NATIVE API  
1549    
1550         #include <pcre.h>  PCRE NATIVE API BASIC FUNCTIONS
1551    
1552         pcre *pcre_compile(const char *pattern, int options,         pcre *pcre_compile(const char *pattern, int options,
1553              const char **errptr, int *erroffset,              const char **errptr, int *erroffset,
# Line 826  PCRE NATIVE API Line 1561  PCRE NATIVE API
1561         pcre_extra *pcre_study(const pcre *code, int options,         pcre_extra *pcre_study(const pcre *code, int options,
1562              const char **errptr);              const char **errptr);
1563    
1564           void pcre_free_study(pcre_extra *extra);
1565    
1566         int pcre_exec(const pcre *code, const pcre_extra *extra,         int pcre_exec(const pcre *code, const pcre_extra *extra,
1567              const char *subject, int length, int startoffset,              const char *subject, int length, int startoffset,
1568              int options, int *ovector, int ovecsize);              int options, int *ovector, int ovecsize);
# Line 835  PCRE NATIVE API Line 1572  PCRE NATIVE API
1572              int options, int *ovector, int ovecsize,              int options, int *ovector, int ovecsize,
1573              int *workspace, int wscount);              int *workspace, int wscount);
1574    
1575    
1576    PCRE NATIVE API STRING EXTRACTION FUNCTIONS
1577    
1578         int pcre_copy_named_substring(const pcre *code,         int pcre_copy_named_substring(const pcre *code,
1579              const char *subject, int *ovector,              const char *subject, int *ovector,
1580              int stringcount, const char *stringname,              int stringcount, const char *stringname,
# Line 866  PCRE NATIVE API Line 1606  PCRE NATIVE API
1606    
1607         void pcre_free_substring_list(const char **stringptr);         void pcre_free_substring_list(const char **stringptr);
1608    
1609    
1610    PCRE NATIVE API AUXILIARY FUNCTIONS
1611    
1612           int pcre_jit_exec(const pcre *code, const pcre_extra *extra,
1613                const char *subject, int length, int startoffset,
1614                int options, int *ovector, int ovecsize,
1615                pcre_jit_stack *jstack);
1616    
1617           pcre_jit_stack *pcre_jit_stack_alloc(int startsize, int maxsize);
1618    
1619           void pcre_jit_stack_free(pcre_jit_stack *stack);
1620    
1621           void pcre_assign_jit_stack(pcre_extra *extra,
1622                pcre_jit_callback callback, void *data);
1623    
1624         const unsigned char *pcre_maketables(void);         const unsigned char *pcre_maketables(void);
1625    
1626         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
1627              int what, void *where);              int what, void *where);
1628    
        int pcre_info(const pcre *code, int *optptr, int *firstcharptr);  
   
1629         int pcre_refcount(pcre *code, int adjust);         int pcre_refcount(pcre *code, int adjust);
1630    
1631         int pcre_config(int what, void *where);         int pcre_config(int what, void *where);
1632    
1633         char *pcre_version(void);         const char *pcre_version(void);
1634    
1635           int pcre_pattern_to_host_byte_order(pcre *code,
1636                pcre_extra *extra, const unsigned char *tables);
1637    
1638    
1639    PCRE NATIVE API INDIRECTED FUNCTIONS
1640    
1641         void *(*pcre_malloc)(size_t);         void *(*pcre_malloc)(size_t);
1642    
# Line 890  PCRE NATIVE API Line 1649  PCRE NATIVE API
1649         int (*pcre_callout)(pcre_callout_block *);         int (*pcre_callout)(pcre_callout_block *);
1650    
1651    
1652    PCRE 8-BIT, 16-BIT, AND 32-BIT LIBRARIES
1653    
1654           As  well  as  support  for  8-bit character strings, PCRE also supports
1655           16-bit strings (from release 8.30) and  32-bit  strings  (from  release
1656           8.32),  by means of two additional libraries. They can be built as well
1657           as, or instead of, the 8-bit library. To avoid too  much  complication,
1658           this  document describes the 8-bit versions of the functions, with only
1659           occasional references to the 16-bit and 32-bit libraries.
1660    
1661           The 16-bit and 32-bit functions operate in the same way as their  8-bit
1662           counterparts;  they  just  use different data types for their arguments
1663           and results, and their names start with pcre16_ or pcre32_  instead  of
1664           pcre_.  For  every  option  that  has  UTF8  in  its name (for example,
1665           PCRE_UTF8), there are corresponding 16-bit and 32-bit names  with  UTF8
1666           replaced by UTF16 or UTF32, respectively. This facility is in fact just
1667           cosmetic; the 16-bit and 32-bit option names define the same  bit  val-
1668           ues.
1669    
1670           References to bytes and UTF-8 in this document should be read as refer-
1671           ences to 16-bit data  quantities  and  UTF-16  when  using  the  16-bit
1672           library,  or  32-bit  data  quantities and UTF-32 when using the 32-bit
1673           library, unless specified otherwise. More details of the specific  dif-
1674           ferences  for  the  16-bit and 32-bit libraries are given in the pcre16
1675           and pcre32 pages.
1676    
1677    
1678  PCRE API OVERVIEW  PCRE API OVERVIEW
1679    
1680         PCRE has its own native API, which is described in this document. There         PCRE has its own native API, which is described in this document. There
1681         are also some wrapper functions that correspond to  the  POSIX  regular         are  also some wrapper functions (for the 8-bit library only) that cor-
1682         expression  API.  These  are  described in the pcreposix documentation.         respond to the POSIX regular expression  API,  but  they  do  not  give
1683         Both of these APIs define a set of C function calls. A C++  wrapper  is         access  to  all  the functionality. They are described in the pcreposix
1684         distributed with PCRE. It is documented in the pcrecpp page.         documentation. Both of these APIs define a set of C function  calls.  A
1685           C++ wrapper (again for the 8-bit library only) is also distributed with
1686         The  native  API  C  function prototypes are defined in the header file         PCRE. It is documented in the pcrecpp page.
1687         pcre.h, and on Unix systems the library itself is called  libpcre.   It  
1688         can normally be accessed by adding -lpcre to the command for linking an         The native API C function prototypes are defined  in  the  header  file
1689         application  that  uses  PCRE.  The  header  file  defines  the  macros         pcre.h,  and  on Unix-like systems the (8-bit) library itself is called
1690         PCRE_MAJOR  and  PCRE_MINOR to contain the major and minor release num-         libpcre. It can normally be accessed by adding -lpcre  to  the  command
1691         bers for the library.  Applications can use these  to  include  support         for  linking an application that uses PCRE. The header file defines the
1692           macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release
1693           numbers  for the library. Applications can use these to include support
1694         for different releases of PCRE.         for different releases of PCRE.
1695    
1696         In a Windows environment, if you want to statically link an application         In a Windows environment, if you want to statically link an application
1697         program against a non-dll pcre.a  file,  you  must  define  PCRE_STATIC         program  against  a  non-dll  pcre.a  file, you must define PCRE_STATIC
1698         before  including  pcre.h or pcrecpp.h, because otherwise the pcre_mal-         before including pcre.h or pcrecpp.h, because otherwise  the  pcre_mal-
1699         loc()   and   pcre_free()   exported   functions   will   be   declared         loc()   and   pcre_free()   exported   functions   will   be   declared
1700         __declspec(dllimport), with unwanted results.         __declspec(dllimport), with unwanted results.
1701    
1702         The   functions   pcre_compile(),  pcre_compile2(),  pcre_study(),  and         The  functions  pcre_compile(),  pcre_compile2(),   pcre_study(),   and
1703         pcre_exec() are used for compiling and matching regular expressions  in         pcre_exec()  are used for compiling and matching regular expressions in
1704         a  Perl-compatible  manner. A sample program that demonstrates the sim-         a Perl-compatible manner. A sample program that demonstrates  the  sim-
1705         plest way of using them is provided in the file  called  pcredemo.c  in         plest  way  of  using them is provided in the file called pcredemo.c in
1706         the PCRE source distribution. A listing of this program is given in the         the PCRE source distribution. A listing of this program is given in the
1707         pcredemo documentation, and the pcresample documentation describes  how         pcredemo  documentation, and the pcresample documentation describes how
1708         to compile and run it.         to compile and run it.
1709    
1710           Just-in-time compiler support is an optional feature of PCRE  that  can
1711           be built in appropriate hardware environments. It greatly speeds up the
1712           matching performance of  many  patterns.  Simple  programs  can  easily
1713           request  that  it  be  used  if available, by setting an option that is
1714           ignored when it is not relevant. More complicated programs  might  need
1715           to     make    use    of    the    functions    pcre_jit_stack_alloc(),
1716           pcre_jit_stack_free(), and pcre_assign_jit_stack() in order to  control
1717           the JIT code's memory usage.
1718    
1719           From  release  8.32 there is also a direct interface for JIT execution,
1720           which gives improved performance. The JIT-specific functions  are  dis-
1721           cussed in the pcrejit documentation.
1722    
1723         A second matching function, pcre_dfa_exec(), which is not Perl-compati-         A second matching function, pcre_dfa_exec(), which is not Perl-compati-
1724         ble, is also provided. This uses a different algorithm for  the  match-         ble, is also provided. This uses a different algorithm for  the  match-
1725         ing.  The  alternative algorithm finds all possible matches (at a given         ing.  The  alternative algorithm finds all possible matches (at a given
# Line 952  PCRE API OVERVIEW Line 1752  PCRE API OVERVIEW
1752         built are used.         built are used.
1753    
1754         The function pcre_fullinfo() is used to find out  information  about  a         The function pcre_fullinfo() is used to find out  information  about  a
1755         compiled  pattern; pcre_info() is an obsolete version that returns only         compiled  pattern.  The  function pcre_version() returns a pointer to a
1756         some of the available information, but is retained for  backwards  com-         string containing the version of PCRE and its date of release.
        patibility.   The function pcre_version() returns a pointer to a string  
        containing the version of PCRE and its date of release.  
1757    
1758         The function pcre_refcount() maintains a  reference  count  in  a  data         The function pcre_refcount() maintains a  reference  count  in  a  data
1759         block  containing  a compiled pattern. This is provided for the benefit         block  containing  a compiled pattern. This is provided for the benefit
# Line 994  NEWLINES Line 1792  NEWLINES
1792         feed) character, the two-character sequence CRLF, any of the three pre-         feed) character, the two-character sequence CRLF, any of the three pre-
1793         ceding, or any Unicode newline sequence. The Unicode newline  sequences         ceding, or any Unicode newline sequence. The Unicode newline  sequences
1794         are  the  three just mentioned, plus the single characters VT (vertical         are  the  three just mentioned, plus the single characters VT (vertical
1795         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
1796         separator, U+2028), and PS (paragraph separator, U+2029).         separator, U+2028), and PS (paragraph separator, U+2029).
1797    
1798         Each  of  the first three conventions is used by at least one operating         Each  of  the first three conventions is used by at least one operating
# Line 1032  MULTITHREADING Line 1830  MULTITHREADING
1830         ing, so the same compiled pattern can safely be used by several threads         ing, so the same compiled pattern can safely be used by several threads
1831         at once.         at once.
1832    
1833           If  the just-in-time optimization feature is being used, it needs sepa-
1834           rate memory stack areas for each thread. See the pcrejit  documentation
1835           for more details.
1836    
1837    
1838  SAVING PRECOMPILED PATTERNS FOR LATER USE  SAVING PRECOMPILED PATTERNS FOR LATER USE
1839    
1840         The compiled form of a regular expression can be saved and re-used at a         The compiled form of a regular expression can be saved and re-used at a
1841         later time, possibly by a different program, and even on a  host  other         later time, possibly by a different program, and even on a  host  other
1842         than  the  one  on  which  it  was  compiled.  Details are given in the         than  the  one  on  which  it  was  compiled.  Details are given in the
1843         pcreprecompile documentation. However, compiling a  regular  expression         pcreprecompile documentation,  which  includes  a  description  of  the
1844         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-
1845         anteed to work and may cause crashes.         lar expression with one version of PCRE for use with a  different  ver-
1846           sion is not guaranteed to work and may cause crashes.
1847    
1848    
1849  CHECKING BUILD-TIME OPTIONS  CHECKING BUILD-TIME OPTIONS
1850    
1851         int pcre_config(int what, void *where);         int pcre_config(int what, void *where);
1852    
1853         The function pcre_config() makes it possible for a PCRE client to  dis-         The  function pcre_config() makes it possible for a PCRE client to dis-
1854         cover which optional features have been compiled into the PCRE library.         cover which optional features have been compiled into the PCRE library.
1855         The pcrebuild documentation has more details about these optional  fea-         The  pcrebuild documentation has more details about these optional fea-
1856         tures.         tures.
1857    
1858         The  first  argument  for pcre_config() is an integer, specifying which         The first argument for pcre_config() is an  integer,  specifying  which
1859         information is required; the second argument is a pointer to a variable         information is required; the second argument is a pointer to a variable
1860         into  which  the  information  is  placed. The following information is         into which the information is placed. The returned  value  is  zero  on
1861           success,  or  the negative error code PCRE_ERROR_BADOPTION if the value
1862           in the first argument is not recognized. The following  information  is
1863         available:         available:
1864    
1865           PCRE_CONFIG_UTF8           PCRE_CONFIG_UTF8
1866    
1867         The output is an integer that is set to one if UTF-8 support is  avail-         The  output is an integer that is set to one if UTF-8 support is avail-
1868         able; otherwise it is set to zero.         able; otherwise it is set to zero. This value should normally be  given
1869           to the 8-bit version of this function, pcre_config(). If it is given to
1870           the  16-bit  or  32-bit  version  of  this  function,  the  result   is
1871           PCRE_ERROR_BADOPTION.
1872    
1873             PCRE_CONFIG_UTF16
1874    
1875           The output is an integer that is set to one if UTF-16 support is avail-
1876           able; otherwise it is set to zero. This value should normally be  given
1877           to the 16-bit version of this function, pcre16_config(). If it is given
1878           to the 8-bit  or  32-bit  version  of  this  function,  the  result  is
1879           PCRE_ERROR_BADOPTION.
1880    
1881             PCRE_CONFIG_UTF32
1882    
1883           The output is an integer that is set to one if UTF-32 support is avail-
1884           able; otherwise it is set to zero. This value should normally be  given
1885           to the 32-bit version of this function, pcre32_config(). If it is given
1886           to the 8-bit  or  16-bit  version  of  this  function,  the  result  is
1887           PCRE_ERROR_BADOPTION.
1888    
1889           PCRE_CONFIG_UNICODE_PROPERTIES           PCRE_CONFIG_UNICODE_PROPERTIES
1890    
1891         The  output  is  an  integer  that is set to one if support for Unicode         The  output  is  an  integer  that is set to one if support for Unicode
1892         character properties is available; otherwise it is set to zero.         character properties is available; otherwise it is set to zero.
1893    
1894             PCRE_CONFIG_JIT
1895    
1896           The output is an integer that is set to one if support for just-in-time
1897           compiling is available; otherwise it is set to zero.
1898    
1899             PCRE_CONFIG_JITTARGET
1900    
1901           The  output is a pointer to a zero-terminated "const char *" string. If
1902           JIT support is available, the string contains the name of the architec-
1903           ture  for  which the JIT compiler is configured, for example "x86 32bit
1904           (little endian + unaligned)". If JIT  support  is  not  available,  the
1905           result is NULL.
1906    
1907           PCRE_CONFIG_NEWLINE           PCRE_CONFIG_NEWLINE
1908    
1909         The output is an integer whose value specifies  the  default  character         The  output  is  an integer whose value specifies the default character
1910         sequence  that is recognized as meaning "newline". The four values that         sequence that is recognized as meaning "newline". The values  that  are
1911         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
1912         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,
1913         are returned in EBCDIC environments. The default should normally corre-         ANYCRLF,  and  ANY  yield the same values. However, the value for LF is
1914           normally 21, though some EBCDIC environments use 37. The  corresponding
1915           values  for  CRLF are 3349 and 3365. The default should normally corre-
1916         spond to the standard sequence for your operating system.         spond to the standard sequence for your operating system.
1917    
1918           PCRE_CONFIG_BSR           PCRE_CONFIG_BSR
1919    
1920         The output is an integer whose value indicates what character sequences         The output is an integer whose value indicates what character sequences
1921         the \R escape sequence matches by default. A value of 0 means  that  \R         the  \R  escape sequence matches by default. A value of 0 means that \R
1922         matches  any  Unicode  line ending sequence; a value of 1 means that \R         matches any Unicode line ending sequence; a value of 1  means  that  \R
1923         matches only CR, LF, or CRLF. The default can be overridden when a pat-         matches only CR, LF, or CRLF. The default can be overridden when a pat-
1924         tern is compiled or matched.         tern is compiled or matched.
1925    
1926           PCRE_CONFIG_LINK_SIZE           PCRE_CONFIG_LINK_SIZE
1927    
1928         The  output  is  an  integer that contains the number of bytes used for         The output is an integer that contains the number  of  bytes  used  for
1929         internal linkage in compiled regular expressions. The value is 2, 3, or         internal  linkage  in  compiled  regular  expressions.  For  the  8-bit
1930         4.  Larger  values  allow larger regular expressions to be compiled, at         library, the value can be 2, 3, or 4. For the 16-bit library, the value
1931         the expense of slower matching. The default value of  2  is  sufficient         is  either  2  or  4  and  is  still  a number of bytes. For the 32-bit
1932         for  all  but  the  most massive patterns, since it allows the compiled         library, the value is either 2 or 4 and is still a number of bytes. The
1933         pattern to be up to 64K in size.         default value of 2 is sufficient for all but the most massive patterns,
1934           since it allows the compiled pattern to be up to 64K  in  size.  Larger
1935           values  allow larger regular expressions to be compiled, at the expense
1936           of slower matching.
1937    
1938           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
1939    
# Line 1162  COMPILING A PATTERN Line 2004  COMPILING A PATTERN
2004         pcrepattern documentation). For those options that can be different  in         pcrepattern documentation). For those options that can be different  in
2005         different  parts  of  the pattern, the contents of the options argument         different  parts  of  the pattern, the contents of the options argument
2006         specifies their settings at the start of compilation and execution. The         specifies their settings at the start of compilation and execution. The
2007         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
2008         the time of matching as well as at compile time.         PCRE_NO_START_OPTIMIZE options can be set at the time  of  matching  as
2009           well as at compile time.
2010    
2011         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,
2012         if  compilation  of  a  pattern fails, pcre_compile() returns NULL, and         if compilation of a pattern fails,  pcre_compile()  returns  NULL,  and
2013         sets the variable pointed to by errptr to point to a textual error mes-         sets the variable pointed to by errptr to point to a textual error mes-
2014         sage. 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
2015         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
2016         character  that  was  being  processed when the error was discovered is         the byte that was being processed when  the  error  was  discovered  is
2017         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
2018         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
2019         until checks are carried out when the whole pattern has  been  scanned;         string, the offset is that of the first byte of the failing character.
2020         in this case the offset is set to the end of the pattern.  
2021           Some  errors are not detected until the whole pattern has been scanned;
2022         If  pcre_compile2()  is  used instead of pcre_compile(), and the error-         in these cases, the offset passed back is the length  of  the  pattern.
2023         codeptr argument is not NULL, a non-zero error code number is  returned         Note  that  the offset is in bytes, not characters, even in UTF-8 mode.
2024         via  this argument in the event of an error. This is in addition to the         It may sometimes point into the middle of a UTF-8 character.
2025    
2026           If pcre_compile2() is used instead of pcre_compile(),  and  the  error-
2027           codeptr  argument is not NULL, a non-zero error code number is returned
2028           via this argument in the event of an error. This is in addition to  the
2029         textual error message. Error codes and messages are listed below.         textual error message. Error codes and messages are listed below.
2030    
2031         If the final argument, tableptr, is NULL, PCRE uses a  default  set  of         If  the  final  argument, tableptr, is NULL, PCRE uses a default set of
2032         character  tables  that  are  built  when  PCRE  is compiled, using the         character tables that are  built  when  PCRE  is  compiled,  using  the
2033         default C locale. Otherwise, tableptr must be an address  that  is  the         default  C  locale.  Otherwise, tableptr must be an address that is the
2034         result  of  a  call to pcre_maketables(). This value is stored with the         result of a call to pcre_maketables(). This value is  stored  with  the
2035         compiled pattern, and used again by pcre_exec(), unless  another  table         compiled  pattern,  and used again by pcre_exec(), unless another table
2036         pointer is passed to it. For more discussion, see the section on locale         pointer is passed to it. For more discussion, see the section on locale
2037         support below.         support below.
2038    
2039         This code fragment shows a typical straightforward  call  to  pcre_com-         This  code  fragment  shows a typical straightforward call to pcre_com-
2040         pile():         pile():
2041    
2042           pcre *re;           pcre *re;
# Line 1202  COMPILING A PATTERN Line 2049  COMPILING A PATTERN
2049             &erroffset,       /* for error offset */             &erroffset,       /* for error offset */
2050             NULL);            /* use default character tables */             NULL);            /* use default character tables */
2051    
2052         The  following  names  for option bits are defined in the pcre.h header         The following names for option bits are defined in  the  pcre.h  header
2053         file:         file:
2054    
2055           PCRE_ANCHORED           PCRE_ANCHORED
2056    
2057         If this bit is set, the pattern is forced to be "anchored", that is, it         If this bit is set, the pattern is forced to be "anchored", that is, it
2058         is  constrained to match only at the first matching point in the string         is constrained to match only at the first matching point in the  string
2059         that is being searched (the "subject string"). This effect can also  be         that  is being searched (the "subject string"). This effect can also be
2060         achieved  by appropriate constructs in the pattern itself, which is the         achieved by appropriate constructs in the pattern itself, which is  the
2061         only way to do it in Perl.         only way to do it in Perl.
2062    
2063           PCRE_AUTO_CALLOUT           PCRE_AUTO_CALLOUT
2064    
2065         If this bit is set, pcre_compile() automatically inserts callout items,         If this bit is set, pcre_compile() automatically inserts callout items,
2066         all  with  number  255, before each pattern item. For discussion of the         all with number 255, before each pattern item. For  discussion  of  the
2067         callout facility, see the pcrecallout documentation.         callout facility, see the pcrecallout documentation.
2068    
2069           PCRE_BSR_ANYCRLF           PCRE_BSR_ANYCRLF
2070           PCRE_BSR_UNICODE           PCRE_BSR_UNICODE
2071    
2072         These options (which are mutually exclusive) control what the \R escape         These options (which are mutually exclusive) control what the \R escape
2073         sequence  matches.  The choice is either to match only CR, LF, or CRLF,         sequence matches. The choice is either to match only CR, LF,  or  CRLF,
2074         or to match any Unicode newline sequence. The default is specified when         or to match any Unicode newline sequence. The default is specified when
2075         PCRE is built. It can be overridden from within the pattern, or by set-         PCRE is built. It can be overridden from within the pattern, or by set-
2076         ting an option when a compiled pattern is matched.         ting an option when a compiled pattern is matched.
2077    
2078           PCRE_CASELESS           PCRE_CASELESS
2079    
2080         If this bit is set, letters in the pattern match both upper  and  lower         If  this  bit is set, letters in the pattern match both upper and lower
2081         case  letters.  It  is  equivalent  to  Perl's /i option, and it can be         case letters. It is equivalent to Perl's  /i  option,  and  it  can  be
2082         changed within a pattern by a (?i) option setting. In UTF-8 mode,  PCRE         changed  within a pattern by a (?i) option setting. In UTF-8 mode, PCRE
2083         always  understands the concept of case for characters whose values are         always understands the concept of case for characters whose values  are
2084         less than 128, so caseless matching is always possible. For  characters         less  than 128, so caseless matching is always possible. For characters
2085         with  higher  values,  the concept of case is supported if PCRE is com-         with higher values, the concept of case is supported if  PCRE  is  com-
2086         piled with Unicode property support, but not otherwise. If you want  to         piled  with Unicode property support, but not otherwise. If you want to
2087         use  caseless  matching  for  characters 128 and above, you must ensure         use caseless matching for characters 128 and  above,  you  must  ensure
2088         that PCRE is compiled with Unicode property support  as  well  as  with         that  PCRE  is  compiled  with Unicode property support as well as with
2089         UTF-8 support.         UTF-8 support.
2090    
2091           PCRE_DOLLAR_ENDONLY           PCRE_DOLLAR_ENDONLY
2092    
2093         If  this bit is set, a dollar metacharacter in the pattern matches only         If this bit is set, a dollar metacharacter in the pattern matches  only
2094         at the end of the subject string. Without this option,  a  dollar  also         at  the  end  of the subject string. Without this option, a dollar also
2095         matches  immediately before a newline at the end of the string (but not         matches immediately before a newline at the end of the string (but  not
2096         before any other newlines). The PCRE_DOLLAR_ENDONLY option  is  ignored         before  any  other newlines). The PCRE_DOLLAR_ENDONLY option is ignored
2097         if  PCRE_MULTILINE  is  set.   There is no equivalent to this option in         if PCRE_MULTILINE is set.  There is no equivalent  to  this  option  in
2098         Perl, and no way to set it within a pattern.         Perl, and no way to set it within a pattern.
2099    
2100           PCRE_DOTALL           PCRE_DOTALL
2101    
2102         If this bit is set, a dot metacharater in the pattern matches all char-         If  this bit is set, a dot metacharacter in the pattern matches a char-
2103         acters,  including  those that indicate newline. Without it, a dot does         acter of any value, including one that indicates a newline. However, it
2104         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.
2105         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
2106         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
2107         newline characters, independent of the setting of this option.         be changed within a pattern by a (?s) option setting. A negative  class
2108           such as [^a] always matches newline characters, independent of the set-
2109           ting of this option.
2110    
2111           PCRE_DUPNAMES           PCRE_DUPNAMES
2112    
2113         If  this  bit is set, names used to identify capturing subpatterns need         If this bit is set, names used to identify capturing  subpatterns  need
2114         not be unique. This can be helpful for certain types of pattern when it         not be unique. This can be helpful for certain types of pattern when it
2115         is  known  that  only  one instance of the named subpattern can ever be         is known that only one instance of the named  subpattern  can  ever  be
2116         matched. There are more details of named subpatterns  below;  see  also         matched.  There  are  more details of named subpatterns below; see also
2117         the pcrepattern documentation.         the pcrepattern documentation.
2118    
2119           PCRE_EXTENDED           PCRE_EXTENDED
2120    
2121         If  this  bit  is  set,  whitespace  data characters in the pattern are         If this bit is set, white space data  characters  in  the  pattern  are
2122         totally ignored except when escaped or inside a character class. White-         totally  ignored except when escaped or inside a character class. White
2123         space does not include the VT character (code 11). In addition, charac-         space does not include the VT character (code 11). In addition, charac-
2124         ters between an unescaped # outside a character class and the next new-         ters between an unescaped # outside a character class and the next new-
2125         line,  inclusive,  are  also  ignored.  This is equivalent to Perl's /x         line, inclusive, are also ignored. This  is  equivalent  to  Perl's  /x
2126         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-
2127         ting.         ting.
2128    
2129           Which characters are interpreted  as  newlines  is  controlled  by  the
2130           options  passed to pcre_compile() or by a special sequence at the start
2131           of the pattern, as described in the section entitled  "Newline  conven-
2132           tions" in the pcrepattern documentation. Note that the end of this type
2133           of comment is  a  literal  newline  sequence  in  the  pattern;  escape
2134           sequences that happen to represent a newline do not count.
2135    
2136         This  option  makes  it possible to include comments inside complicated         This  option  makes  it possible to include comments inside complicated
2137         patterns.  Note, however, that this applies only  to  data  characters.         patterns.  Note, however, that this applies only  to  data  characters.
2138         Whitespace   characters  may  never  appear  within  special  character         White  space  characters  may  never  appear  within  special character
2139         sequences in a pattern, for  example  within  the  sequence  (?(  which         sequences in a pattern, for example within the sequence (?( that intro-
2140         introduces a conditional subpattern.         duces a conditional subpattern.
2141    
2142           PCRE_EXTRA           PCRE_EXTRA
2143    
# Line 1319  COMPILING A PATTERN Line 2175  COMPILING A PATTERN
2175         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
2176         default, for Perl compatibility.         default, for Perl compatibility.
2177    
2178           (3) \U matches an upper case "U" character; by default \U causes a com-
2179           pile time error (Perl uses \U to upper case subsequent characters).
2180    
2181           (4) \u matches a lower case "u" character unless it is followed by four
2182           hexadecimal  digits,  in  which case the hexadecimal number defines the
2183           code point to match. By default, \u causes a compile time  error  (Perl
2184           uses it to upper case the following character).
2185    
2186           (5)  \x matches a lower case "x" character unless it is followed by two
2187           hexadecimal digits, in which case the hexadecimal  number  defines  the
2188           code  point  to  match. By default, as in Perl, a hexadecimal number is
2189           always expected after \x, but it may have zero, one, or two digits (so,
2190           for example, \xz matches a binary zero character followed by z).
2191    
2192           PCRE_MULTILINE           PCRE_MULTILINE
2193    
2194         By  default,  PCRE  treats the subject string as consisting of a single         By  default,  PCRE  treats the subject string as consisting of a single
# Line 1336  COMPILING A PATTERN Line 2206  COMPILING A PATTERN
2206         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,
2207         setting PCRE_MULTILINE has no effect.         setting PCRE_MULTILINE has no effect.
2208    
2209             PCRE_NEVER_UTF
2210    
2211           This option locks out interpretation of the pattern as UTF-8 (or UTF-16
2212           or  UTF-32  in the 16-bit and 32-bit libraries). In particular, it pre-
2213           vents the creator of the pattern from switching to  UTF  interpretation
2214           by starting the pattern with (*UTF). This may be useful in applications
2215           that  process  patterns  from  external  sources.  The  combination  of
2216           PCRE_UTF8 and PCRE_NEVER_UTF also causes an error.
2217    
2218           PCRE_NEWLINE_CR           PCRE_NEWLINE_CR
2219           PCRE_NEWLINE_LF           PCRE_NEWLINE_LF
2220           PCRE_NEWLINE_CRLF           PCRE_NEWLINE_CRLF
2221           PCRE_NEWLINE_ANYCRLF           PCRE_NEWLINE_ANYCRLF
2222           PCRE_NEWLINE_ANY           PCRE_NEWLINE_ANY
2223    
2224         These options override the default newline definition that  was  chosen         These  options  override the default newline definition that was chosen
2225         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
2226         newline is indicated by a single character (CR  or  LF,  respectively).         newline  is  indicated  by a single character (CR or LF, respectively).
2227         Setting  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the         Setting PCRE_NEWLINE_CRLF specifies that a newline is indicated by  the
2228         two-character CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF  specifies         two-character  CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF specifies
2229         that any of the three preceding sequences should be recognized. Setting         that any of the three preceding sequences should be recognized. Setting
2230         PCRE_NEWLINE_ANY specifies that any Unicode newline sequence should  be         PCRE_NEWLINE_ANY  specifies that any Unicode newline sequence should be
2231         recognized. The Unicode newline sequences are the three just mentioned,         recognized.
2232         plus the single characters VT (vertical  tab,  U+000B),  FF  (formfeed,  
2233         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
2234         (paragraph separator, U+2029). The last  two  are  recognized  only  in         three  just  mentioned,  plus  the  single characters VT (vertical tab,
2235         UTF-8 mode.         U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line sep-
2236           arator,  U+2028),  and  PS (paragraph separator, U+2029). For the 8-bit
2237           library, the last two are recognized only in UTF-8 mode.
2238    
2239           When PCRE is compiled to run in an EBCDIC (mainframe) environment,  the
2240           code for CR is 0x0d, the same as ASCII. However, the character code for
2241           LF is normally 0x15, though in some EBCDIC environments 0x25  is  used.
2242           Whichever  of  these  is  not LF is made to correspond to Unicode's NEL
2243           character. EBCDIC codes are all less than 256. For  more  details,  see
2244           the pcrebuild documentation.
2245    
2246         The  newline  setting  in  the  options  word  uses three bits that are         The  newline  setting  in  the  options  word  uses three bits that are
2247         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 2251  COMPILING A PATTERN
2251         PCRE_NEWLINE_CRLF, but other combinations may yield unused numbers  and         PCRE_NEWLINE_CRLF, but other combinations may yield unused numbers  and
2252         cause an error.         cause an error.
2253    
2254         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
2255         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
2256         character  class  is  encountered.  This indicates a comment that lasts         characters,  and so are ignored in this mode. Also, an unescaped # out-
2257         until after the next line break sequence. In other circumstances,  line         side a character class indicates a comment that lasts until  after  the
2258         break   sequences   are   treated  as  literal  data,  except  that  in         next  line break sequence. In other circumstances, line break sequences
2259         PCRE_EXTENDED mode, both CR and LF are treated as whitespace characters         in patterns are treated as literal data.
        and are therefore ignored.  
2260    
2261         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
2262         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 2264  COMPILING A PATTERN
2264           PCRE_NO_AUTO_CAPTURE           PCRE_NO_AUTO_CAPTURE
2265    
2266         If this option is set, it disables the use of numbered capturing paren-         If this option is set, it disables the use of numbered capturing paren-
2267         theses  in the pattern. Any opening parenthesis that is not followed by         theses in the pattern. Any opening parenthesis that is not followed  by
2268         ? behaves as if it were followed by ?: but named parentheses can  still         ?  behaves as if it were followed by ?: but named parentheses can still
2269         be  used  for  capturing  (and  they acquire numbers in the usual way).         be used for capturing (and they acquire  numbers  in  the  usual  way).
2270         There is no equivalent of this option in Perl.         There is no equivalent of this option in Perl.
2271    
2272             PCRE_NO_START_OPTIMIZE
2273    
2274           This  is an option that acts at matching time; that is, it is really an
2275           option for pcre_exec() or pcre_dfa_exec(). If  it  is  set  at  compile
2276           time,  it is remembered with the compiled pattern and assumed at match-
2277           ing time. This is necessary if you want to use JIT  execution,  because
2278           the  JIT  compiler needs to know whether or not this option is set. For
2279           details see the discussion of PCRE_NO_START_OPTIMIZE below.
2280    
2281           PCRE_UCP           PCRE_UCP
2282    
2283         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,
2284         the POSIX character classes. By default, only ASCII characters are rec-         \w,  and  some  of  the POSIX character classes. By default, only ASCII
2285         ognized, but if PCRE_UCP is set, Unicode properties are used instead to         characters are recognized, but if PCRE_UCP is set,  Unicode  properties
2286         classify  characters.  More details are given in the section on generic         are  used instead to classify characters. More details are given in the
2287         character types in the pcrepattern page. If you set PCRE_UCP,  matching         section on generic character types in the pcrepattern page. If you  set
2288         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
2289         only if PCRE has been compiled with Unicode property support.         option is available only if PCRE has been compiled with  Unicode  prop-
2290           erty support.
2291    
2292           PCRE_UNGREEDY           PCRE_UNGREEDY
2293    
2294         This option inverts the "greediness" of the quantifiers  so  that  they         This  option  inverts  the "greediness" of the quantifiers so that they
2295         are  not greedy by default, but become greedy if followed by "?". It is         are not greedy by default, but become greedy if followed by "?". It  is
2296         not compatible with Perl. It can also be set by a (?U)  option  setting         not  compatible  with Perl. It can also be set by a (?U) option setting
2297         within the pattern.         within the pattern.
2298    
2299           PCRE_UTF8           PCRE_UTF8
2300    
2301         This  option  causes PCRE to regard both the pattern and the subject as         This option causes PCRE to regard both the pattern and the  subject  as
2302         strings of UTF-8 characters instead of single-byte  character  strings.         strings of UTF-8 characters instead of single-byte strings. However, it
2303         However,  it is available only when PCRE is built to include UTF-8 sup-         is available only when PCRE is built to include UTF  support.  If  not,
2304         port. If not, the use of this option provokes an error. Details of  how         the  use  of  this option provokes an error. Details of how this option
2305         this  option  changes the behaviour of PCRE are given in the section on         changes the behaviour of PCRE are given in the pcreunicode page.
        UTF-8 support in the main pcre page.  
2306    
2307           PCRE_NO_UTF8_CHECK           PCRE_NO_UTF8_CHECK
2308    
2309         When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is         When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
2310         automatically  checked.  There  is  a  discussion about the validity of         automatically  checked.  There  is  a  discussion about the validity of
2311         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
2312         bytes  is  found,  pcre_compile() returns an error. If you already know         found,  pcre_compile()  returns an error. If you already know that your
2313         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-
2314         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
2315         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
2316         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
2317         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
2318         UTF-8 validity checking of subject strings.         checking  of  subject strings only. If the same string is being matched
2319           many times, the option can be safely set for the second and  subsequent
2320           matchings to improve performance.
2321    
2322    
2323  COMPILATION ERROR CODES  COMPILATION ERROR CODES
2324    
2325         The  following  table  lists  the  error  codes than may be returned by         The  following  table  lists  the  error  codes than may be returned by
2326         pcre_compile2(), along with the error messages that may be returned  by         pcre_compile2(), along with the error messages that may be returned  by
2327         both  compiling functions. As PCRE has developed, some error codes have         both  compiling  functions.  Note  that error messages are always 8-bit
2328         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,
2329           some  error codes have fallen out of use. To avoid confusion, they have
2330           not been re-used.
2331    
2332            0  no error            0  no error
2333            1  \ at end of pattern            1  \ at end of pattern
# Line 1461  COMPILATION ERROR CODES Line 2361  COMPILATION ERROR CODES
2361           29  (?R or (?[+-]digits must be followed by )           29  (?R or (?[+-]digits must be followed by )
2362           30  unknown POSIX class name           30  unknown POSIX class name
2363           31  POSIX collating elements are not supported           31  POSIX collating elements are not supported
2364           32  this version of PCRE is not compiled with PCRE_UTF8 support           32  this version of PCRE is compiled without UTF support
2365           33  [this code is not in use]           33  [this code is not in use]
2366           34  character value in \x{...} sequence is too large           34  character value in \x{...} sequence is too large
2367           35  invalid condition (?(0)           35  invalid condition (?(0)
2368           36  \C not allowed in lookbehind assertion           36  \C not allowed in lookbehind assertion
2369           37  PCRE does not support \L, \l, \N, \U, or \u           37  PCRE does not support \L, \l, \N{name}, \U, or \u
2370           38  number after (?C is > 255           38  number after (?C is > 255
2371           39  closing ) for (?C expected           39  closing ) for (?C expected
2372           40  recursive call could loop indefinitely           40  recursive call could loop indefinitely
2373           41  unrecognized character after (?P           41  unrecognized character after (?P
2374           42  syntax error in subpattern name (missing terminator)           42  syntax error in subpattern name (missing terminator)
2375           43  two named subpatterns have the same name           43  two named subpatterns have the same name
2376           44  invalid UTF-8 string           44  invalid UTF-8 string (specifically UTF-8)
2377           45  support for \P, \p, and \X has not been compiled           45  support for \P, \p, and \X has not been compiled
2378           46  malformed \P or \p sequence           46  malformed \P or \p sequence
2379           47  unknown property name after \P or \p           47  unknown property name after \P or \p
2380           48  subpattern name is too long (maximum 32 characters)           48  subpattern name is too long (maximum 32 characters)
2381           49  too many named subpatterns (maximum 10000)           49  too many named subpatterns (maximum 10000)
2382           50  [this code is not in use]           50  [this code is not in use]
2383           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
2384           52  internal error: overran compiling workspace           52  internal error: overran compiling workspace
2385           53  internal error: previously-checked referenced subpattern           53  internal error: previously-checked referenced subpattern
2386                 not found                 not found
# Line 1491  COMPILATION ERROR CODES Line 2391  COMPILATION ERROR CODES
2391                 name/number or by a plain number                 name/number or by a plain number
2392           58  a numbered reference must not be zero           58  a numbered reference must not be zero
2393           59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)           59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
2394           60  (*VERB) not recognized           60  (*VERB) not recognized or malformed
2395           61  number is too big           61  number is too big
2396           62  subpattern name expected           62  subpattern name expected
2397           63  digit expected after (?+           63  digit expected after (?+
# Line 1499  COMPILATION ERROR CODES Line 2399  COMPILATION ERROR CODES
2399           65  different names for subpatterns of the same number are           65  different names for subpatterns of the same number are
2400                 not allowed                 not allowed
2401           66  (*MARK) must have an argument           66  (*MARK) must have an argument
2402           67  this version of PCRE is not compiled with PCRE_UCP support           67  this version of PCRE is not compiled with Unicode property
2403                   support
2404             68  \c must be followed by an ASCII character
2405             69  \k is not followed by a braced, angle-bracketed, or quoted name
2406             70  internal error: unknown opcode in find_fixedlength()
2407             71  \N is not supported in a class
2408             72  too many forward references
2409             73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
2410             74  invalid UTF-16 string (specifically UTF-16)
2411             75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
2412             76  character value in \u.... sequence is too large
2413             77  invalid UTF-32 string (specifically UTF-32)
2414    
2415         The numbers 32 and 10000 in errors 48 and 49  are  defaults;  different         The numbers 32 and 10000 in errors 48 and 49  are  defaults;  different
2416         values may be used if the limits were changed when PCRE was built.         values may be used if the limits were changed when PCRE was built.
# Line 1524  STUDYING A PATTERN Line 2435  STUDYING A PATTERN
2435         passed; these are described below in the section on matching a pattern.         passed; these are described below in the section on matching a pattern.
2436    
2437         If studying the  pattern  does  not  produce  any  useful  information,         If studying the  pattern  does  not  produce  any  useful  information,
2438         pcre_study() returns NULL. In that circumstance, if the calling program         pcre_study()  returns  NULL  by  default.  In that circumstance, if the
2439         wants  to  pass  any  of   the   other   fields   to   pcre_exec()   or         calling program wants to pass any of the other fields to pcre_exec() or
2440         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
2441           pcre_study() is called  with  the  PCRE_STUDY_EXTRA_NEEDED  option,  it
2442         The  second  argument of pcre_study() contains option bits. At present,         returns a pcre_extra block even if studying did not find any additional
2443         no options are defined, and this argument should always be zero.         information. It may still return NULL, however, if an error  occurs  in
2444           pcre_study().
2445    
2446           The  second  argument  of  pcre_study() contains option bits. There are
2447           three further options in addition to PCRE_STUDY_EXTRA_NEEDED:
2448    
2449             PCRE_STUDY_JIT_COMPILE
2450             PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
2451             PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
2452    
2453           If any of these are set, and the just-in-time  compiler  is  available,
2454           the  pattern  is  further compiled into machine code that executes much
2455           faster than the pcre_exec()  interpretive  matching  function.  If  the
2456           just-in-time  compiler is not available, these options are ignored. All
2457           undefined bits in the options argument must be zero.
2458    
2459           JIT compilation is a heavyweight optimization. It can  take  some  time
2460           for  patterns  to  be analyzed, and for one-off matches and simple pat-
2461           terns the benefit of faster execution might be offset by a much  slower
2462           study time.  Not all patterns can be optimized by the JIT compiler. For
2463           those that cannot be handled, matching automatically falls back to  the
2464           pcre_exec()  interpreter.  For more details, see the pcrejit documenta-
2465           tion.
2466    
2467         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.
2468         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 2471  STUDYING A PATTERN
2471         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
2472         after calling pcre_study(), to be sure that it has run successfully.         after calling pcre_study(), to be sure that it has run successfully.
2473    
2474         This is a typical call to pcre_study():         When  you are finished with a pattern, you can free the memory used for
2475           the study data by calling pcre_free_study(). This function was added to
2476           the  API  for  release  8.20. For earlier versions, the memory could be
2477           freed with pcre_free(), just like the pattern itself. This  will  still
2478           work  in  cases where JIT optimization is not used, but it is advisable
2479           to change to the new function when convenient.
2480    
2481           pcre_extra *pe;         This is a typical way in which pcre_study() is used (except that  in  a
2482           pe = pcre_study(         real application there should be tests for errors):
2483    
2484             int rc;
2485             pcre *re;
2486             pcre_extra *sd;
2487             re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
2488             sd = pcre_study(
2489             re,             /* result of pcre_compile() */             re,             /* result of pcre_compile() */
2490             0,              /* no options exist */             0,              /* no options */
2491             &error);        /* set to NULL or points to a message */             &error);        /* set to NULL or points to a message */
2492             rc = pcre_exec(   /* see below for details of pcre_exec() options */
2493               re, sd, "subject", 7, 0, 0, ovector, 30);
2494             ...
2495             pcre_free_study(sd);
2496             pcre_free(re);
2497    
2498         Studying a pattern does two things: first, a lower bound for the length         Studying a pattern does two things: first, a lower bound for the length
2499         of subject string that is needed to match the pattern is computed. This         of subject string that is needed to match the pattern is computed. This
2500         does not mean that there are any strings of that length that match, but         does not mean that there are any strings of that length that match, but
2501         it does guarantee that no shorter strings match. The value is  used  by         it does guarantee that no shorter strings match. The value is  used  to
2502         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
2503         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
2504         the value in a calling program via the pcre_fullinfo() function.         pcre_fullinfo() function.
2505    
2506         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
2507         have a single fixed starting character. A bitmap of  possible  starting         have a single fixed starting character. A bitmap of  possible  starting
2508         bytes  is  created. This speeds up finding a position in the subject at         bytes  is  created. This speeds up finding a position in the subject at
2509         which to start matching.         which to start matching. (In 16-bit mode, the bitmap is used for 16-bit
2510           values  less  than  256.  In 32-bit mode, the bitmap is used for 32-bit
2511           values less than 256.)
2512    
2513           These two optimizations apply to both pcre_exec() and  pcre_dfa_exec(),
2514           and  the  information  is also used by the JIT compiler.  The optimiza-
2515           tions can be disabled by  setting  the  PCRE_NO_START_OPTIMIZE  option.
2516           You  might want to do this if your pattern contains callouts or (*MARK)
2517           and you want to make use of these facilities in  cases  where  matching
2518           fails.
2519    
2520           PCRE_NO_START_OPTIMIZE  can be specified at either compile time or exe-
2521           cution  time.  However,  if   PCRE_NO_START_OPTIMIZE   is   passed   to
2522           pcre_exec(), (that is, after any JIT compilation has happened) JIT exe-
2523           cution is disabled. For JIT execution to work with  PCRE_NO_START_OPTI-
2524           MIZE, the option must be set at compile time.
2525    
2526         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.  
2527    
2528    
2529  LOCALE SUPPORT  LOCALE SUPPORT
# Line 1631  INFORMATION ABOUT A PATTERN Line 2590  INFORMATION ABOUT A PATTERN
2590              int what, void *where);              int what, void *where);
2591    
2592         The pcre_fullinfo() function returns information about a compiled  pat-         The pcre_fullinfo() function returns information about a compiled  pat-
2593         tern. It replaces the obsolete pcre_info() function, which is neverthe-         tern.  It replaces the pcre_info() function, which was removed from the
2594         less retained for backwards compability (and is documented below).         library at version 8.30, after more than 10 years of obsolescence.
2595    
2596         The first argument for pcre_fullinfo() is a  pointer  to  the  compiled         The first argument for pcre_fullinfo() is a  pointer  to  the  compiled
2597         pattern.  The second argument is the result of pcre_study(), or NULL if         pattern.  The second argument is the result of pcre_study(), or NULL if
# Line 1641  INFORMATION ABOUT A PATTERN Line 2600  INFORMATION ABOUT A PATTERN
2600         variable to receive the data. The yield of the  function  is  zero  for         variable to receive the data. The yield of the  function  is  zero  for
2601         success, or one of the following negative numbers:         success, or one of the following negative numbers:
2602    
2603           PCRE_ERROR_NULL       the argument code was NULL           PCRE_ERROR_NULL           the argument code was NULL
2604                                 the argument where was NULL                                     the argument where was NULL
2605           PCRE_ERROR_BADMAGIC   the "magic number" was not found           PCRE_ERROR_BADMAGIC       the "magic number" was not found
2606           PCRE_ERROR_BADOPTION  the value of what was invalid           PCRE_ERROR_BADENDIANNESS  the pattern was compiled with different
2607                                       endianness
2608             PCRE_ERROR_BADOPTION      the value of what was invalid
2609             PCRE_ERROR_UNSET          the requested field is not set
2610    
2611         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
2612         an simple check against passing an arbitrary memory pointer. Here is  a         an simple check against passing an arbitrary memory pointer. The  endi-
2613         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
2614         pattern:         different host. Here is a typical call of  pcre_fullinfo(),  to  obtain
2615           the length of the compiled pattern:
2616    
2617           int rc;           int rc;
2618           size_t length;           size_t length;
2619           rc = pcre_fullinfo(           rc = pcre_fullinfo(
2620             re,               /* result of pcre_compile() */             re,               /* result of pcre_compile() */
2621             pe,               /* result of pcre_study(), or NULL */             sd,               /* result of pcre_study(), or NULL */
2622             PCRE_INFO_SIZE,   /* what is required */             PCRE_INFO_SIZE,   /* what is required */
2623             &length);         /* where to put the data */             &length);         /* where to put the data */
2624    
2625         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
2626         are as follows:         are as follows:
2627    
2628           PCRE_INFO_BACKREFMAX           PCRE_INFO_BACKREFMAX
2629    
2630         Return  the  number  of  the highest back reference in the pattern. The         Return the number of the highest back reference  in  the  pattern.  The
2631         fourth argument should point to an int variable. Zero  is  returned  if         fourth  argument  should  point to an int variable. Zero is returned if
2632         there are no back references.         there are no back references.
2633    
2634           PCRE_INFO_CAPTURECOUNT           PCRE_INFO_CAPTURECOUNT
2635    
2636         Return  the  number of capturing subpatterns in the pattern. The fourth         Return the number of capturing subpatterns in the pattern.  The  fourth
2637         argument should point to an int variable.         argument should point to an int variable.
2638    
2639           PCRE_INFO_DEFAULT_TABLES           PCRE_INFO_DEFAULT_TABLES
2640    
2641         Return a pointer to the internal default character tables within  PCRE.         Return  a pointer to the internal default character tables within PCRE.
2642         The  fourth  argument should point to an unsigned char * variable. This         The fourth argument should point to an unsigned char *  variable.  This
2643         information call is provided for internal use by the pcre_study() func-         information call is provided for internal use by the pcre_study() func-
2644         tion.  External  callers  can  cause PCRE to use its internal tables by         tion. External callers can cause PCRE to use  its  internal  tables  by
2645         passing a NULL table pointer.         passing a NULL table pointer.
2646    
2647           PCRE_INFO_FIRSTBYTE           PCRE_INFO_FIRSTBYTE
2648    
2649         Return information about the first byte of any matched  string,  for  a         Return information about the first data unit of any matched string, for
2650         non-anchored  pattern. The fourth argument should point to an int vari-         a non-anchored pattern. (The name of this option refers  to  the  8-bit
2651         able. (This option used to be called PCRE_INFO_FIRSTCHAR; the old  name         library,  where data units are bytes.) The fourth argument should point
2652         is still recognized for backwards compatibility.)         to an int variable.
2653    
2654           If there is a fixed first value, for example, the  letter  "c"  from  a
2655           pattern  such  as (cat|cow|coyote), its value is returned. In the 8-bit
2656           library, the value is always less than 256. In the 16-bit  library  the
2657           value can be up to 0xffff. In the 32-bit library the value can be up to
2658           0x10ffff.
2659    
2660         If  there  is  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  
2661    
2662         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
2663         branch starts with "^", or         branch starts with "^", or
# Line 1701  INFORMATION ABOUT A PATTERN Line 2669  INFORMATION ABOUT A PATTERN
2669         of  a  subject string or after any newline within the string. Otherwise         of  a  subject string or after any newline within the string. Otherwise
2670         -2 is returned. For anchored patterns, -2 is returned.         -2 is returned. For anchored patterns, -2 is returned.
2671    
2672           Since for the 32-bit library using the non-UTF-32 mode,  this  function
2673           is  unable to return the full 32-bit range of the character, this value
2674           is   deprecated;   instead   the   PCRE_INFO_FIRSTCHARACTERFLAGS    and
2675           PCRE_INFO_FIRSTCHARACTER values should be used.
2676    
2677           PCRE_INFO_FIRSTTABLE           PCRE_INFO_FIRSTTABLE
2678    
2679         If the pattern was studied, and this resulted in the construction of  a         If  the pattern was studied, and this resulted in the construction of a
2680         256-bit table indicating a fixed set of bytes for the first byte in any         256-bit table indicating a fixed set of values for the first data  unit
2681         matching string, a pointer to the table is returned. Otherwise NULL  is         in  any  matching string, a pointer to the table is returned. Otherwise
2682         returned.  The fourth argument should point to an unsigned char * vari-         NULL is returned. The fourth argument should point to an unsigned  char
2683         able.         * variable.
2684    
2685           PCRE_INFO_HASCRORLF           PCRE_INFO_HASCRORLF
2686    
2687         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
2688         characters,  otherwise  0.  The  fourth argument should point to an int         characters, otherwise 0. The fourth argument should  point  to  an  int
2689         variable. An explicit match is either a literal CR or LF character,  or         variable.  An explicit match is either a literal CR or LF character, or
2690         \r or \n.         \r or \n.
2691    
2692           PCRE_INFO_JCHANGED           PCRE_INFO_JCHANGED
2693    
2694         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,
2695         otherwise 0. The fourth argument should point to an int variable.  (?J)         otherwise  0. The fourth argument should point to an int variable. (?J)
2696         and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.         and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
2697    
2698             PCRE_INFO_JIT
2699    
2700           Return 1 if the pattern was studied with one of the  JIT  options,  and
2701           just-in-time compiling was successful. The fourth argument should point
2702           to an int variable. A return value of 0 means that JIT support  is  not
2703           available  in this version of PCRE, or that the pattern was not studied
2704           with a JIT option, or that the JIT compiler could not handle this  par-
2705           ticular  pattern. See the pcrejit documentation for details of what can
2706           and cannot be handled.
2707    
2708             PCRE_INFO_JITSIZE
2709    
2710           If the pattern was successfully studied with a JIT option,  return  the
2711           size  of the JIT compiled code, otherwise return zero. The fourth argu-
2712           ment should point to a size_t variable.
2713    
2714           PCRE_INFO_LASTLITERAL           PCRE_INFO_LASTLITERAL
2715    
2716         Return  the  value of the rightmost literal byte that must exist in any         Return the value of the rightmost literal data unit that must exist  in
2717         matched string, other than at its  start,  if  such  a  byte  has  been         any  matched  string, other than at its start, if such a value has been
2718         recorded. The fourth argument should point to an int variable. If there         recorded. The fourth argument should point to an int variable. If there
2719         is no such byte, -1 is returned. For anchored patterns, a last  literal         is no such value, -1 is returned. For anchored patterns, a last literal
2720         byte  is  recorded only if it follows something of variable length. For         value is recorded only if it follows something of variable length.  For
2721         example, for the pattern /^a\d+z\d+/ the returned value is "z", but for         example, for the pattern /^a\d+z\d+/ the returned value is "z", but for
2722         /^a\dz\d/ the returned value is -1.         /^a\dz\d/ the returned value is -1.
2723    
2724           Since for the 32-bit library using the non-UTF-32 mode,  this  function
2725           is  unable to return the full 32-bit range of the character, this value
2726           is   deprecated;   instead    the    PCRE_INFO_REQUIREDCHARFLAGS    and
2727           PCRE_INFO_REQUIREDCHAR values should be used.
2728    
2729             PCRE_INFO_MATCHLIMIT
2730    
2731           If  the  pattern  set  a  match  limit by including an item of the form
2732           (*LIMIT_MATCH=nnnn) at the start, the value  is  returned.  The  fourth
2733           argument  should  point to an unsigned 32-bit integer. If no such value
2734           has  been  set,  the  call  to  pcre_fullinfo()   returns   the   error
2735           PCRE_ERROR_UNSET.
2736    
2737             PCRE_INFO_MAXLOOKBEHIND
2738    
2739           Return  the  number of characters (NB not bytes) in the longest lookbe-
2740           hind assertion in the pattern. This information is  useful  when  doing
2741           multi-segment matching using the partial matching facilities. Note that
2742           the simple assertions \b and \B require a one-character lookbehind.  \A
2743           also  registers a one-character lookbehind, though it does not actually
2744           inspect the previous character. This is to ensure  that  at  least  one
2745           character  from  the old segment is retained when a new segment is pro-
2746           cessed. Otherwise, if there are no lookbehinds in the pattern, \A might
2747           match incorrectly at the start of a new segment.
2748    
2749           PCRE_INFO_MINLENGTH           PCRE_INFO_MINLENGTH
2750    
2751         If  the  pattern  was studied and a minimum length for matching subject         If  the  pattern  was studied and a minimum length for matching subject
2752         strings was computed, its value is  returned.  Otherwise  the  returned         strings was computed, its value is  returned.  Otherwise  the  returned
2753         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-8 mode
2754         be relevant in UTF-8 mode). The fourth argument should point to an  int         may be different from the number of bytes. The fourth  argument  should
2755         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
2756         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
2757         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
2758           least that long.
2759    
2760           PCRE_INFO_NAMECOUNT           PCRE_INFO_NAMECOUNT
2761           PCRE_INFO_NAMEENTRYSIZE           PCRE_INFO_NAMEENTRYSIZE
2762           PCRE_INFO_NAMETABLE           PCRE_INFO_NAMETABLE
2763    
2764         PCRE  supports the use of named as well as numbered capturing parenthe-         PCRE supports the use of named as well as numbered capturing  parenthe-
2765         ses. The names are just an additional way of identifying the  parenthe-         ses.  The names are just an additional way of identifying the parenthe-
2766         ses, which still acquire numbers. Several convenience functions such as         ses, which still acquire numbers. Several convenience functions such as
2767         pcre_get_named_substring() are provided for  extracting  captured  sub-         pcre_get_named_substring()  are  provided  for extracting captured sub-
2768         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
2769         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
2770         pointers in the output vector (described with pcre_exec() below). To do         pointers in the output vector (described with pcre_exec() below). To do
2771         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
2772         described by these three values.         described by these three values.
2773    
2774         The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT         The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT
2775         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size
2776         of  each  entry;  both  of  these  return  an int value. The entry size         of each entry; both of these  return  an  int  value.  The  entry  size
2777         depends on the length of the longest name. PCRE_INFO_NAMETABLE  returns         depends  on the length of the longest name. PCRE_INFO_NAMETABLE returns
2778         a  pointer  to  the  first  entry of the table (a pointer to char). The         a pointer to the first entry of the table. This is a pointer to char in
2779         first two bytes of each entry are the number of the capturing parenthe-         the 8-bit library, where the first two bytes of each entry are the num-
2780         sis,  most  significant byte first. The rest of the entry is the corre-         ber of the capturing parenthesis, most significant byte first.  In  the
2781         sponding name, zero terminated.         16-bit  library,  the pointer points to 16-bit data units, the first of
2782           which contains the parenthesis number.   In  the  32-bit  library,  the
2783           pointer  points  to  32-bit data units, the first of which contains the
2784           parenthesis number. The rest of the entry is  the  corresponding  name,
2785           zero terminated.
2786    
2787         The names are in alphabetical order. Duplicate names may appear if  (?|         The  names are in alphabetical order. Duplicate names may appear if (?|
2788         is used to create multiple groups with the same number, as described in         is used to create multiple groups with the same number, as described in
2789         the section on duplicate subpattern numbers in  the  pcrepattern  page.         the  section  on  duplicate subpattern numbers in the pcrepattern page.
2790         Duplicate  names  for  subpatterns with different numbers are permitted         Duplicate names for subpatterns with different  numbers  are  permitted
2791         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
2792         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-
2793         tern. In the absence of (?| this is the  order  of  increasing  number;         tern.  In  the  absence  of (?| this is the order of increasing number;
2794         when (?| is used this is not necessarily the case because later subpat-         when (?| is used this is not necessarily the case because later subpat-
2795         terns may have lower numbers.         terns may have lower numbers.
2796    
2797         As a simple example of the name/number table,  consider  the  following         As  a  simple  example of the name/number table, consider the following
2798         pattern  (assume  PCRE_EXTENDED is set, so white space - including new-         pattern after compilation by the 8-bit library (assume PCRE_EXTENDED is
2799         lines - is ignored):         set, so white space - including newlines - is ignored):
2800    
2801           (?<date> (?<year>(\d\d)?\d\d) -           (?<date> (?<year>(\d\d)?\d\d) -
2802           (?<month>\d\d) - (?<day>\d\d) )           (?<month>\d\d) - (?<day>\d\d) )
2803    
2804         There are four named subpatterns, so the table has  four  entries,  and         There  are  four  named subpatterns, so the table has four entries, and
2805         each  entry  in the table is eight bytes long. The table is as follows,         each entry in the table is eight bytes long. The table is  as  follows,
2806         with non-printing bytes shows in hexadecimal, and undefined bytes shown         with non-printing bytes shows in hexadecimal, and undefined bytes shown
2807         as ??:         as ??:
2808    
# Line 1792  INFORMATION ABOUT A PATTERN Line 2811  INFORMATION ABOUT A PATTERN
2811           00 04 m  o  n  t  h  00           00 04 m  o  n  t  h  00
2812           00 02 y  e  a  r  00 ??           00 02 y  e  a  r  00 ??
2813    
2814         When  writing  code  to  extract  data from named subpatterns using the         When writing code to extract data  from  named  subpatterns  using  the
2815         name-to-number map, remember that the length of the entries  is  likely         name-to-number  map,  remember that the length of the entries is likely
2816         to be different for each compiled pattern.         to be different for each compiled pattern.
2817    
2818           PCRE_INFO_OKPARTIAL           PCRE_INFO_OKPARTIAL
2819    
2820         Return  1  if  the  pattern  can  be  used  for  partial  matching with         Return 1  if  the  pattern  can  be  used  for  partial  matching  with
2821         pcre_exec(), otherwise 0. The fourth argument should point  to  an  int         pcre_exec(),  otherwise  0.  The fourth argument should point to an int
2822         variable.  From  release  8.00,  this  always  returns  1,  because the         variable. From  release  8.00,  this  always  returns  1,  because  the
2823         restrictions that previously applied  to  partial  matching  have  been         restrictions  that  previously  applied  to  partial matching have been
2824         lifted.  The  pcrepartial documentation gives details of partial match-         lifted. The pcrepartial documentation gives details of  partial  match-
2825         ing.         ing.
2826    
2827           PCRE_INFO_OPTIONS           PCRE_INFO_OPTIONS
2828    
2829         Return a copy of the options with which the pattern was  compiled.  The         Return  a  copy of the options with which the pattern was compiled. The
2830         fourth  argument  should  point to an unsigned long int variable. These         fourth argument should point to an unsigned long  int  variable.  These
2831         option bits are those specified in the call to pcre_compile(), modified         option bits are those specified in the call to pcre_compile(), modified
2832         by any top-level option settings at the start of the pattern itself. In         by any top-level option settings at the start of the pattern itself. In
2833         other words, they are the options that will be in force  when  matching         other  words,  they are the options that will be in force when matching
2834         starts.  For  example, if the pattern /(?im)abc(?-i)d/ is compiled with         starts. For example, if the pattern /(?im)abc(?-i)d/ is  compiled  with
2835         the PCRE_EXTENDED option, the result is PCRE_CASELESS,  PCRE_MULTILINE,         the  PCRE_EXTENDED option, the result is PCRE_CASELESS, PCRE_MULTILINE,
2836         and PCRE_EXTENDED.         and PCRE_EXTENDED.
2837    
2838         A  pattern  is  automatically  anchored by PCRE if all of its top-level         A pattern is automatically anchored by PCRE if  all  of  its  top-level
2839         alternatives begin with one of the following:         alternatives begin with one of the following:
2840    
2841           ^     unless PCRE_MULTILINE is set           ^     unless PCRE_MULTILINE is set
# Line 1828  INFORMATION ABOUT A PATTERN Line 2847  INFORMATION ABOUT A PATTERN
2847         For such patterns, the PCRE_ANCHORED bit is set in the options returned         For such patterns, the PCRE_ANCHORED bit is set in the options returned
2848         by pcre_fullinfo().         by pcre_fullinfo().
2849    
2850             PCRE_INFO_RECURSIONLIMIT
2851    
2852           If the pattern set a recursion limit by including an item of  the  form
2853           (*LIMIT_RECURSION=nnnn) at the start, the value is returned. The fourth
2854           argument should point to an unsigned 32-bit integer. If no  such  value
2855           has   been   set,   the  call  to  pcre_fullinfo()  returns  the  error
2856           PCRE_ERROR_UNSET.
2857    
2858           PCRE_INFO_SIZE           PCRE_INFO_SIZE
2859    
2860         Return  the  size  of the compiled pattern, that is, the value that was         Return the size of the compiled pattern in bytes (for both  libraries).
2861         passed as the argument to pcre_malloc() when PCRE was getting memory in         The  fourth argument should point to a size_t variable. This value does
2862         which to place the compiled data. The fourth argument should point to a         not include the  size  of  the  pcre  structure  that  is  returned  by
2863         size_t variable.         pcre_compile().  The  value that is passed as the argument to pcre_mal-
2864           loc() when pcre_compile() is getting memory in which to place the  com-
2865           piled  data  is  the value returned by this option plus the size of the
2866           pcre structure. Studying a compiled pattern, with or without JIT,  does
2867           not alter the value returned by this option.
2868    
2869           PCRE_INFO_STUDYSIZE           PCRE_INFO_STUDYSIZE
2870    
2871         Return the size of the data block pointed to by the study_data field in         Return the size in bytes of the data block pointed to by the study_data
2872         a  pcre_extra  block.  That  is,  it  is  the  value that was passed to         field in a pcre_extra block. If pcre_extra is  NULL,  or  there  is  no
2873         pcre_malloc() when PCRE was getting memory into which to place the data         study  data,  zero  is  returned. The fourth argument should point to a
2874         created  by  pcre_study().  If pcre_extra is NULL, or there is no study         size_t variable. The study_data field is set by pcre_study() to  record
2875         data, zero is returned. The fourth argument should point  to  a  size_t         information  that  will  speed  up  matching  (see the section entitled
2876           "Studying a pattern" above). The format of the study_data block is pri-
2877           vate,  but  its length is made available via this option so that it can
2878           be  saved  and  restored  (see  the  pcreprecompile  documentation  for
2879           details).
2880    
2881             PCRE_INFO_FIRSTCHARACTERFLAGS
2882    
2883           Return information about the first data unit of any matched string, for
2884           a non-anchored pattern. The fourth argument  should  point  to  an  int
2885         variable.         variable.
2886    
2887           If  there  is  a  fixed first value, for example, the letter "c" from a
2888           pattern such as (cat|cow|coyote), 1  is  returned,  and  the  character
2889           value can be retrieved using PCRE_INFO_FIRSTCHARACTER.
2890    
2891           If there is no fixed first value, and if either
2892    
2893  OBSOLETE INFO FUNCTION         (a)  the pattern was compiled with the PCRE_MULTILINE option, and every
2894           branch starts with "^", or
2895    
2896         int pcre_info(const pcre *code, int *optptr, int *firstcharptr);         (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2897           set (if it were set, the pattern would be anchored),
2898    
2899         The  pcre_info()  function is now obsolete because its interface is too         2 is returned, indicating that the pattern matches only at the start of
2900         restrictive to return all the available data about a compiled  pattern.         a subject string or after any newline within the string. Otherwise 0 is
2901         New   programs   should  use  pcre_fullinfo()  instead.  The  yield  of         returned. For anchored patterns, 0 is returned.
2902         pcre_info() is the number of capturing subpatterns, or one of the  fol-  
2903         lowing negative numbers:           PCRE_INFO_FIRSTCHARACTER
2904    
2905           PCRE_ERROR_NULL       the argument code was NULL         Return  the  fixed  first character value, if PCRE_INFO_FIRSTCHARACTER-
2906           PCRE_ERROR_BADMAGIC   the "magic number" was not found         FLAGS returned 1; otherwise returns 0. The fourth argument should point
2907           to an uint_t variable.
2908         If  the  optptr  argument is not NULL, a copy of the options with which  
2909         the pattern was compiled is placed in the integer  it  points  to  (see         In  the 8-bit library, the value is always less than 256. In the 16-bit
2910         PCRE_INFO_OPTIONS above).         library the value can be up to 0xffff. In the 32-bit library in  UTF-32
2911           mode  the  value  can  be up to 0x10ffff, and up to 0xffffffff when not
2912         If  the  pattern  is  not anchored and the firstcharptr argument is not         using UTF-32 mode.
2913         NULL, it is used to pass back information about the first character  of  
2914         any matched string (see PCRE_INFO_FIRSTBYTE above).         If there is no fixed first value, and if either
2915    
2916           (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
2917           branch starts with "^", or
2918    
2919           (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2920           set (if it were set, the pattern would be anchored),
2921    
2922           -1 is returned, indicating that the pattern matches only at  the  start
2923           of  a  subject string or after any newline within the string. Otherwise
2924           -2 is returned. For anchored patterns, -2 is returned.
2925    
2926             PCRE_INFO_REQUIREDCHARFLAGS
2927    
2928           Returns 1 if there is a rightmost literal data unit that must exist  in
2929           any matched string, other than at its start. The fourth argument should
2930           point to an int variable. If there is no such value, 0 is returned.  If
2931           returning  1,  the  character  value  itself  can  be  retrieved  using
2932           PCRE_INFO_REQUIREDCHAR.
2933    
2934           For anchored patterns, a last literal value is recorded only if it fol-
2935           lows  something  of  variable  length.  For  example,  for  the pattern
2936           /^a\d+z\d+/  the   returned   value   1   (with   "z"   returned   from
2937           PCRE_INFO_REQUIREDCHAR), but for /^a\dz\d/ the returned value is 0.
2938    
2939             PCRE_INFO_REQUIREDCHAR
2940    
2941           Return  the value of the rightmost literal data unit that must exist in
2942           any matched string, other than at its start, if such a value  has  been
2943           recorded.  The fourth argument should point to an uint32_t variable. If
2944           there is no such value, 0 is returned.
2945    
2946    
2947  REFERENCE COUNTS  REFERENCE COUNTS
2948    
2949         int pcre_refcount(pcre *code, int adjust);         int pcre_refcount(pcre *code, int adjust);
2950    
2951         The  pcre_refcount()  function is used to maintain a reference count in         The pcre_refcount() function is used to maintain a reference  count  in
2952         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
2953         benefit  of  applications  that  operate  in an object-oriented manner,         benefit of applications that  operate  in  an  object-oriented  manner,
2954         where different parts of the application may be using the same compiled         where different parts of the application may be using the same compiled
2955         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.
2956    
2957         When a pattern is compiled, the reference count field is initialized to         When a pattern is compiled, the reference count field is initialized to
2958         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
2959         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
2960         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
2961         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
2962         is outside these limits, it is forced to the appropriate limit value.         is outside these limits, it is forced to the appropriate limit value.
2963    
2964         Except when it is zero, the reference count is not correctly  preserved         Except  when it is zero, the reference count is not correctly preserved
2965         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
2966         whose byte-order is different. (This seems a highly unlikely scenario.)         whose byte-order is different. (This seems a highly unlikely scenario.)
2967    
2968    
# Line 1895  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2972  MATCHING A PATTERN: THE TRADITIONAL FUNC
2972              const char *subject, int length, int startoffset,              const char *subject, int length, int startoffset,
2973              int options, int *ovector, int ovecsize);              int options, int *ovector, int ovecsize);
2974    
2975         The function pcre_exec() is called to match a subject string against  a         The  function pcre_exec() is called to match a subject string against a
2976         compiled  pattern, which is passed in the code argument. If the pattern         compiled pattern, which is passed in the code argument. If the  pattern
2977         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
2978         argument.  This  function is the main matching facility of the library,         argument. You can call pcre_exec() with the same code and  extra  argu-
2979         and it operates in a Perl-like manner. For specialist use there is also         ments  as  many  times as you like, in order to match different subject
2980         an  alternative matching function, which is described below in the sec-         strings with the same pattern.
2981         tion about the pcre_dfa_exec() function.  
2982           This function is the main matching facility  of  the  library,  and  it
2983           operates  in  a  Perl-like  manner. For specialist use there is also an
2984           alternative matching function, which is described below in the  section
2985           about the pcre_dfa_exec() function.
2986    
2987         In most applications, the pattern will have been compiled (and  option-         In  most applications, the pattern will have been compiled (and option-
2988         ally  studied)  in the same process that calls pcre_exec(). However, it         ally studied) in the same process that calls pcre_exec().  However,  it
2989         is possible to save compiled patterns and study data, and then use them         is possible to save compiled patterns and study data, and then use them
2990         later  in  different processes, possibly even on different hosts. For a         later in different processes, possibly even on different hosts.  For  a
2991         discussion about this, see the pcreprecompile documentation.         discussion about this, see the pcreprecompile documentation.
2992    
2993         Here is an example of a simple call to pcre_exec():         Here is an example of a simple call to pcre_exec():
# Line 1925  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3006  MATCHING A PATTERN: THE TRADITIONAL FUNC
3006    
3007     Extra data for pcre_exec()     Extra data for pcre_exec()
3008    
3009         If the extra argument is not NULL, it must point to a  pcre_extra  data         If  the  extra argument is not NULL, it must point to a pcre_extra data
3010         block.  The pcre_study() function returns such a block (when it doesn't         block. The pcre_study() function returns such a block (when it  doesn't
3011         return NULL), but you can also create one for yourself, and pass  addi-         return  NULL), but you can also create one for yourself, and pass addi-
3012         tional  information  in it. The pcre_extra block contains the following         tional information in it. The pcre_extra block contains  the  following
3013         fields (not necessarily in this order):         fields (not necessarily in this order):
3014    
3015           unsigned long int flags;           unsigned long int flags;
3016           void *study_data;           void *study_data;
3017             void *executable_jit;
3018           unsigned long int match_limit;           unsigned long int match_limit;
3019           unsigned long int match_limit_recursion;           unsigned long int match_limit_recursion;
3020           void *callout_data;           void *callout_data;
3021           const unsigned char *tables;           const unsigned char *tables;
3022           unsigned char **mark;           unsigned char **mark;
3023    
3024         The flags field is a bitmap that specifies which of  the  other  fields         In  the  16-bit  version  of  this  structure,  the mark field has type
3025         are set. The flag bits are:         "PCRE_UCHAR16 **".
3026    
3027           PCRE_EXTRA_STUDY_DATA         In the 32-bit version of  this  structure,  the  mark  field  has  type
3028           "PCRE_UCHAR32 **".
3029    
3030           The  flags  field is used to specify which of the other fields are set.
3031           The flag bits are:
3032    
3033             PCRE_EXTRA_CALLOUT_DATA
3034             PCRE_EXTRA_EXECUTABLE_JIT
3035             PCRE_EXTRA_MARK
3036           PCRE_EXTRA_MATCH_LIMIT           PCRE_EXTRA_MATCH_LIMIT
3037           PCRE_EXTRA_MATCH_LIMIT_RECURSION           PCRE_EXTRA_MATCH_LIMIT_RECURSION
3038           PCRE_EXTRA_CALLOUT_DATA           PCRE_EXTRA_STUDY_DATA
3039           PCRE_EXTRA_TABLES           PCRE_EXTRA_TABLES
          PCRE_EXTRA_MARK  
3040    
3041         Other  flag  bits should be set to zero. The study_data field is set in         Other flag bits should be set to zero. The study_data field  and  some-
3042         the pcre_extra block that is returned by  pcre_study(),  together  with         times  the executable_jit field are set in the pcre_extra block that is
3043         the appropriate flag bit. You should not set this yourself, but you may         returned by pcre_study(), together with the appropriate flag bits.  You
3044         add to the block by setting the other fields  and  their  corresponding         should  not set these yourself, but you may add to the block by setting
3045         flag bits.         other fields and their corresponding flag bits.
3046    
3047         The match_limit field provides a means of preventing PCRE from using up         The match_limit field provides a means of preventing PCRE from using up
3048         a vast amount of resources when running patterns that are not going  to         a  vast amount of resources when running patterns that are not going to
3049         match,  but  which  have  a very large number of possibilities in their         match, but which have a very large number  of  possibilities  in  their
3050         search trees. The classic example is a pattern that uses nested  unlim-         search  trees. The classic example is a pattern that uses nested unlim-
3051         ited repeats.         ited repeats.
3052    
3053         Internally,  PCRE uses a function called match() which it calls repeat-         Internally, pcre_exec() uses a function called match(), which it  calls
3054         edly (sometimes recursively). The limit set by match_limit  is  imposed         repeatedly  (sometimes  recursively).  The  limit set by match_limit is
3055         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,
3056         has the effect of limiting the amount of  backtracking  that  can  take         which  has  the  effect of limiting the amount of backtracking that can
3057         place. For patterns that are not anchored, the count restarts from zero         take place. For patterns that are not anchored, the count restarts from
3058         for each position in the subject string.         zero for each position in the subject string.
3059    
3060           When pcre_exec() is called with a pattern that was successfully studied
3061           with a JIT option, the way that the matching is  executed  is  entirely
3062           different.  However, there is still the possibility of runaway matching
3063           that goes on for a very long time, and so the match_limit value is also
3064           used in this case (but in a different way) to limit how long the match-
3065           ing can continue.
3066    
3067         The default 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
3068         default  default  is 10 million, which handles all but the most extreme         default  default  is 10 million, which handles all but the most extreme
# Line 1975  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3071  MATCHING A PATTERN: THE TRADITIONAL FUNC
3071         PCRE_EXTRA_MATCH_LIMIT is set in the  flags  field.  If  the  limit  is         PCRE_EXTRA_MATCH_LIMIT is set in the  flags  field.  If  the  limit  is
3072         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
3073    
3074         The  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
3075           start of a pattern of the form
3076    
3077             (*LIMIT_MATCH=d)
3078    
3079           where d is a decimal number. However, such a setting is ignored  unless
3080           d  is  less  than  the limit set by the caller of pcre_exec() or, if no
3081           such limit is set, less than the default.
3082    
3083           The match_limit_recursion field is similar to match_limit, but  instead
3084         of limiting the total number of times that match() is called, it limits         of limiting the total number of times that match() is called, it limits
3085         the  depth  of  recursion. The recursion depth is a smaller number than         the depth of recursion. The recursion depth is a  smaller  number  than
3086         the total number of calls, because not all calls to match() are  recur-         the  total number of calls, because not all calls to match() are recur-
3087         sive.  This limit is of use only if it is set smaller than match_limit.         sive.  This limit is of use only if it is set smaller than match_limit.
3088    
3089         Limiting  the  recursion  depth  limits the amount of stack that can be         Limiting the recursion depth limits the amount of  machine  stack  that
3090         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
3091         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
3092           limit  is not relevant, and is ignored, when matching is done using JIT
3093         The  default  value  for  match_limit_recursion can be set when PCRE is         compiled code.
3094         built; the default default  is  the  same  value  as  the  default  for  
3095         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
3096         a  pcre_extra  block  in  which  match_limit_recursion  is   set,   and         built;  the  default  default  is  the  same  value  as the default for
3097         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
3098           a   pcre_extra   block  in  which  match_limit_recursion  is  set,  and
3099           PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in  the  flags  field.  If  the
3100         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.
3101    
3102           A  value for the recursion limit may also be supplied by an item at the
3103           start of a pattern of the form
3104    
3105             (*LIMIT_RECURSION=d)
3106    
3107           where d is a decimal number. However, such a setting is ignored  unless
3108           d  is  less  than  the limit set by the caller of pcre_exec() or, if no
3109           such limit is set, less than the default.
3110    
3111         The callout_data field is used in conjunction with the  "callout"  fea-         The callout_data field is used in conjunction with the  "callout"  fea-
3112         ture, and is described in the pcrecallout documentation.         ture, and is described in the pcrecallout documentation.
3113    
# Line 2007  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3123  MATCHING A PATTERN: THE TRADITIONAL FUNC
3123         tion for a discussion of saving compiled patterns for later use.         tion for a discussion of saving compiled patterns for later use.
3124    
3125         If PCRE_EXTRA_MARK is set in the flags field, the mark  field  must  be         If PCRE_EXTRA_MARK is set in the flags field, the mark  field  must  be
3126         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-
3127         tracking control verbs such as (*MARK:NAME), and the execution ends  up         tracking control verbs such as (*MARK:NAME), and the execution ends  up
3128         with  a  name  to  pass back, a pointer to the name string (zero termi-         with  a  name  to  pass back, a pointer to the name string (zero termi-
3129         nated) is placed in the variable pointed to  by  the  mark  field.  The         nated) is placed in the variable pointed to  by  the  mark  field.  The
3130         names  are  within  the  compiled pattern; if you wish to retain such a         names  are  within  the  compiled pattern; if you wish to retain such a
3131         name you must copy it before freeing the memory of a compiled  pattern.         name you must copy it before freeing the memory of a compiled  pattern.
3132         If  there  is no name to pass back, the variable pointed to by the mark         If  there  is no name to pass back, the variable pointed to by the mark
3133         field set to NULL. For details of the backtracking control  verbs,  see         field is set to NULL. For details of the  backtracking  control  verbs,
3134         the section entitled "Backtracking control" in the pcrepattern documen-         see the section entitled "Backtracking control" in the pcrepattern doc-
3135         tation.         umentation.
3136    
3137     Option bits for pcre_exec()     Option bits for pcre_exec()
3138    
3139         The unused bits of the options argument for pcre_exec() must  be  zero.         The unused bits of the options argument for pcre_exec() must  be  zero.
3140         The  only  bits  that  may  be set are PCRE_ANCHORED, PCRE_NEWLINE_xxx,         The  only  bits  that  may  be set are PCRE_ANCHORED, PCRE_NEWLINE_xxx,
3141         PCRE_NOTBOL,   PCRE_NOTEOL,    PCRE_NOTEMPTY,    PCRE_NOTEMPTY_ATSTART,         PCRE_NOTBOL,   PCRE_NOTEOL,    PCRE_NOTEMPTY,    PCRE_NOTEMPTY_ATSTART,
3142         PCRE_NO_START_OPTIMIZE,   PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_SOFT,  and         PCRE_NO_START_OPTIMIZE,   PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_HARD,  and
3143         PCRE_PARTIAL_HARD.         PCRE_PARTIAL_SOFT.
3144    
3145           If the pattern was successfully studied with one  of  the  just-in-time
3146           (JIT) compile options, the only supported options for JIT execution are
3147           PCRE_NO_UTF8_CHECK,    PCRE_NOTBOL,     PCRE_NOTEOL,     PCRE_NOTEMPTY,
3148           PCRE_NOTEMPTY_ATSTART,  PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an
3149           unsupported option is used, JIT execution is disabled  and  the  normal
3150           interpretive code in pcre_exec() is run.
3151    
3152           PCRE_ANCHORED           PCRE_ANCHORED
3153    
3154         The PCRE_ANCHORED option limits pcre_exec() to matching  at  the  first         The  PCRE_ANCHORED  option  limits pcre_exec() to matching at the first
3155         matching  position.  If  a  pattern was compiled with PCRE_ANCHORED, or         matching position. If a pattern was  compiled  with  PCRE_ANCHORED,  or
3156         turned out to be anchored by virtue of its contents, it cannot be  made         turned  out to be anchored by virtue of its contents, it cannot be made
3157         unachored at matching time.         unachored at matching time.
3158    
3159           PCRE_BSR_ANYCRLF           PCRE_BSR_ANYCRLF
3160           PCRE_BSR_UNICODE           PCRE_BSR_UNICODE
3161    
3162         These options (which are mutually exclusive) control what the \R escape         These options (which are mutually exclusive) control what the \R escape
3163         sequence matches. The choice is either to match only CR, LF,  or  CRLF,         sequence  matches.  The choice is either to match only CR, LF, or CRLF,
3164         or  to  match  any Unicode newline sequence. These options override the         or to match any Unicode newline sequence. These  options  override  the
3165         choice that was made or defaulted when the pattern was compiled.         choice that was made or defaulted when the pattern was compiled.
3166    
3167           PCRE_NEWLINE_CR           PCRE_NEWLINE_CR
# Line 2047  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3170  MATCHING A PATTERN: THE TRADITIONAL FUNC
3170           PCRE_NEWLINE_ANYCRLF           PCRE_NEWLINE_ANYCRLF
3171           PCRE_NEWLINE_ANY           PCRE_NEWLINE_ANY
3172    
3173         These options override  the  newline  definition  that  was  chosen  or         These  options  override  the  newline  definition  that  was chosen or
3174         defaulted  when the pattern was compiled. For details, see the descrip-         defaulted when the pattern was compiled. For details, see the  descrip-
3175         tion of pcre_compile()  above.  During  matching,  the  newline  choice         tion  of  pcre_compile()  above.  During  matching,  the newline choice
3176         affects  the  behaviour  of the dot, circumflex, and dollar metacharac-         affects the behaviour of the dot, circumflex,  and  dollar  metacharac-
3177         ters. It may also alter the way the match position is advanced after  a         ters.  It may also alter the way the match position is advanced after a
3178         match failure for an unanchored pattern.         match failure for an unanchored pattern.
3179    
3180         When  PCRE_NEWLINE_CRLF,  PCRE_NEWLINE_ANYCRLF,  or PCRE_NEWLINE_ANY is         When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF,  or  PCRE_NEWLINE_ANY  is
3181         set, and a match attempt for an unanchored pattern fails when the  cur-         set,  and a match attempt for an unanchored pattern fails when the cur-
3182         rent  position  is  at  a  CRLF  sequence,  and the pattern contains no         rent position is at a  CRLF  sequence,  and  the  pattern  contains  no
3183         explicit matches for  CR  or  LF  characters,  the  match  position  is         explicit  matches  for  CR  or  LF  characters,  the  match position is
3184         advanced by two characters instead of one, in other words, to after the         advanced by two characters instead of one, in other words, to after the
3185         CRLF.         CRLF.
3186    
3187         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
3188         expected.  For  example,  if  the  pattern  is .+A (and the PCRE_DOTALL         expected. For example, if the  pattern  is  .+A  (and  the  PCRE_DOTALL
3189         option is not set), it does not match the string "\r\nA" because, after         option is not set), it does not match the string "\r\nA" because, after
3190         failing  at the start, it skips both the CR and the LF before retrying.         failing at the start, it skips both the CR and the LF before  retrying.
3191         However, the pattern [\r\n]A does match that string,  because  it  con-         However,  the  pattern  [\r\n]A does match that string, because it con-
3192         tains an explicit CR or LF reference, and so advances only by one char-         tains an explicit CR or LF reference, and so advances only by one char-
3193         acter after the first failure.         acter after the first failure.
3194    
3195         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
3196         those  characters,  or  one  of the \r or \n escape sequences. Implicit         those characters, or one of the \r or  \n  escape  sequences.  Implicit
3197         matches such as [^X] do not count, nor does \s (which includes  CR  and         matches  such  as [^X] do not count, nor does \s (which includes CR and
3198         LF in the characters that it matches).         LF in the characters that it matches).
3199    
3200         Notwithstanding  the above, anomalous effects may still occur when CRLF         Notwithstanding the above, anomalous effects may still occur when  CRLF
3201         is a valid newline sequence and explicit \r or \n escapes appear in the         is a valid newline sequence and explicit \r or \n escapes appear in the
3202         pattern.         pattern.
3203    
3204           PCRE_NOTBOL           PCRE_NOTBOL
3205    
3206         This option specifies that first character of the subject string is not         This option specifies that first character of the subject string is not
3207         the beginning of a line, so the  circumflex  metacharacter  should  not         the  beginning  of  a  line, so the circumflex metacharacter should not
3208         match  before it. Setting this without PCRE_MULTILINE (at compile time)         match before it. Setting this without PCRE_MULTILINE (at compile  time)
3209         causes circumflex never to match. This option affects only  the  behav-         causes  circumflex  never to match. This option affects only the behav-
3210         iour of the circumflex metacharacter. It does not affect \A.         iour of the circumflex metacharacter. It does not affect \A.
3211    
3212           PCRE_NOTEOL           PCRE_NOTEOL
3213    
3214         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
3215         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
3216         in  multiline mode) a newline immediately before it. Setting this with-         in multiline mode) a newline immediately before it. Setting this  with-
3217         out PCRE_MULTILINE (at compile time) causes dollar never to match. This         out PCRE_MULTILINE (at compile time) causes dollar never to match. This
3218         option  affects only the behaviour of the dollar metacharacter. It does         option affects only the behaviour of the dollar metacharacter. It  does
3219         not affect \Z or \z.         not affect \Z or \z.
3220    
3221           PCRE_NOTEMPTY           PCRE_NOTEMPTY
3222    
3223         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
3224         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
3225         the alternatives match the empty string, the entire  match  fails.  For         the  alternatives  match  the empty string, the entire match fails. For
3226         example, if the pattern         example, if the pattern
3227    
3228           a?b?           a?b?
3229    
3230         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
3231         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
3232         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-
3233         rences of "a" or "b".         rences of "a" or "b".
3234    
3235           PCRE_NOTEMPTY_ATSTART           PCRE_NOTEMPTY_ATSTART
3236    
3237         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
3238         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
3239         anchored, such a match can occur only if the pattern contains \K.         anchored, such a match can occur only if the pattern contains \K.
3240    
3241         Perl    has    no    direct    equivalent    of    PCRE_NOTEMPTY     or         Perl     has    no    direct    equivalent    of    PCRE_NOTEMPTY    or
3242         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
3243         match of the empty string within its split() function, and  when  using         match  of  the empty string within its split() function, and when using
3244         the  /g  modifier.  It  is  possible  to emulate Perl's behaviour after         the /g modifier. It is  possible  to  emulate  Perl's  behaviour  after
3245         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-
3246         set  with  PCRE_NOTEMPTY_ATSTART  and  PCRE_ANCHORED,  and then if that         set with PCRE_NOTEMPTY_ATSTART and  PCRE_ANCHORED,  and  then  if  that
3247         fails, by advancing the starting offset (see below) and trying an ordi-         fails, by advancing the starting offset (see below) and trying an ordi-
3248         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
3249         in the pcredemo sample program.         in  the  pcredemo sample program. In the most general case, you have to
3250           check to see if the newline convention recognizes CRLF  as  a  newline,
3251           and  if so, and the current character is CR followed by LF, advance the
3252           starting offset by two characters instead of one.
3253    
3254           PCRE_NO_START_OPTIMIZE           PCRE_NO_START_OPTIMIZE
3255    
# Line 2134  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3260  MATCHING A PATTERN: THE TRADITIONAL FUNC
3260         cannot find it, without actually running the  main  matching  function.         cannot find it, without actually running the  main  matching  function.
3261         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-
3262         tern is not considered until after a suitable starting  point  for  the         tern is not considered until after a suitable starting  point  for  the
3263         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,
3264         "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-
3265         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
3266         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.
3267    
3268         The PCRE_NO_START_OPTIMIZE option disables the start-up  optimizations,         The PCRE_NO_START_OPTIMIZE option disables the start-up  optimizations,
3269         possibly  causing  performance  to  suffer,  but ensuring that in cases         possibly  causing  performance  to  suffer,  but ensuring that in cases
3270         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
3271         such as (*COMMIT) and (*MARK) are considered at every possible starting         such as (*COMMIT) and (*MARK) are considered at every possible starting
3272         position in the subject  string.   Setting  PCRE_NO_START_OPTIMIZE  can         position in the subject string. If  PCRE_NO_START_OPTIMIZE  is  set  at
3273         change the outcome of a matching operation.  Consider the pattern         compile  time,  it  cannot  be  unset  at  matching  time.  The  use of
3274           PCRE_NO_START_OPTIMIZE  at  matching  time  (that  is,  passing  it  to
3275           pcre_exec())  disables  JIT  execution;  in this situation, matching is
3276           always done using interpretively.
3277    
3278           Setting PCRE_NO_START_OPTIMIZE can change the  outcome  of  a  matching
3279           operation.  Consider the pattern
3280    
3281           (*COMMIT)ABC           (*COMMIT)ABC
3282    
# Line 2175  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3307  MATCHING A PATTERN: THE TRADITIONAL FUNC
3307    
3308         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
3309         UTF-8  string is automatically checked when pcre_exec() is subsequently         UTF-8  string is automatically checked when pcre_exec() is subsequently
3310         called.  The value of startoffset is also checked  to  ensure  that  it         called.  The entire string is checked before any other processing takes
3311         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
3312         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
3313         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
3314         pcre_exec() returns the error PCRE_ERROR_BADUTF8. If  startoffset  con-         sequence  of  bytes   is   found,   pcre_exec()   returns   the   error
3315         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
3316           truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
3317           both  cases, information about the precise nature of the error may also
3318           be returned (see the descriptions of these errors in the section  enti-
3319           tled  Error return values from pcre_exec() below).  If startoffset con-
3320           tains a value that does not point to the start of a UTF-8 character (or
3321           to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is returned.
3322    
3323         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
3324         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 3326  MATCHING A PATTERN: THE TRADITIONAL FUNC
3326         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
3327         making  repeated  calls  to  find  all  the matches in a single subject         making  repeated  calls  to  find  all  the matches in a single subject
3328         string. However, you should be  sure  that  the  value  of  startoffset         string. However, you should be  sure  that  the  value  of  startoffset
3329         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
3330         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
3331         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
3332         acter, is undefined. Your program may crash.         may crash.
3333    
3334           PCRE_PARTIAL_HARD           PCRE_PARTIAL_HARD
3335           PCRE_PARTIAL_SOFT           PCRE_PARTIAL_SOFT
# Line 2200  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3338  MATCHING A PATTERN: THE TRADITIONAL FUNC
3338         patibility,  PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial         patibility,  PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial
3339         match occurs if the end of the subject string is reached  successfully,         match occurs if the end of the subject string is reached  successfully,
3340         but  there  are not enough subject characters to complete the match. If         but  there  are not enough subject characters to complete the match. If
3341         this happens when PCRE_PARTIAL_HARD  is  set,  pcre_exec()  immediately         this happens when PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set,
3342         returns  PCRE_ERROR_PARTIAL.  Otherwise,  if  PCRE_PARTIAL_SOFT is set,         matching  continues  by  testing any remaining alternatives. Only if no
3343         matching continues by testing any other alternatives. Only if they  all         complete match can be found is PCRE_ERROR_PARTIAL returned  instead  of
3344         fail  is  PCRE_ERROR_PARTIAL  returned (instead of PCRE_ERROR_NOMATCH).         PCRE_ERROR_NOMATCH.  In  other  words,  PCRE_PARTIAL_SOFT says that the
3345         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
3346         found  is  set  as  the first matching string. There is a more detailed         match can be found.
3347         discussion in the pcrepartial documentation.  
3348           If  PCRE_PARTIAL_HARD  is  set, it overrides PCRE_PARTIAL_SOFT. In this
3349           case, if a partial match  is  found,  pcre_exec()  immediately  returns
3350           PCRE_ERROR_PARTIAL,  without  considering  any  other  alternatives. In
3351           other words, when PCRE_PARTIAL_HARD is set, a partial match is  consid-
3352           ered to be more important that an alternative complete match.
3353    
3354           In  both  cases,  the portion of the string that was inspected when the
3355           partial match was found is set as the first matching string. There is a
3356           more  detailed  discussion  of partial and multi-segment matching, with
3357           examples, in the pcrepartial documentation.
3358    
3359     The string to be matched by pcre_exec()     The string to be matched by pcre_exec()
3360    
3361         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
3362         length (in bytes) in length, and a starting byte offset in startoffset.         length  in  bytes in length, and a starting byte offset in startoffset.
3363         In UTF-8 mode, the byte offset must point to the start of a UTF-8 char-         If this is  negative  or  greater  than  the  length  of  the  subject,
3364         acter.  Unlike  the pattern string, the subject may contain binary zero         pcre_exec()  returns  PCRE_ERROR_BADOFFSET. When the starting offset is
3365         bytes. When the starting offset is zero, the search for a match  starts         zero, the search for a match starts at the beginning  of  the  subject,
3366         at  the  beginning  of  the subject, and this is by far the most common         and this is by far the most common case. In UTF-8 mode, the byte offset
3367         case.         must point to the start of a UTF-8 character (or the end  of  the  sub-
3368           ject).  Unlike  the pattern string, the subject may contain binary zero
3369           bytes.
3370    
3371         A non-zero starting offset is useful when searching for  another  match         A non-zero starting offset is useful when searching for  another  match
3372         in  the same subject by calling pcre_exec() again after a previous suc-         in  the same subject by calling pcre_exec() again after a previous suc-
# Line 2237  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3387  MATCHING A PATTERN: THE TRADITIONAL FUNC
3387         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
3388         discover that it is preceded by a letter.         discover that it is preceded by a letter.
3389    
3390         If  a  non-zero starting offset is passed when the pattern is anchored,         Finding  all  the  matches  in a subject is tricky when the pattern can
3391           match an empty string. It is possible to emulate Perl's /g behaviour by
3392           first   trying   the   match   again  at  the  same  offset,  with  the
3393           PCRE_NOTEMPTY_ATSTART and  PCRE_ANCHORED  options,  and  then  if  that
3394           fails,  advancing  the  starting  offset  and  trying an ordinary match
3395           again. There is some code that demonstrates how to do this in the pcre-
3396           demo sample program. In the most general case, you have to check to see
3397           if the newline convention recognizes CRLF as a newline, and if so,  and
3398           the current character is CR followed by LF, advance the starting offset
3399           by two characters instead of one.
3400    
3401           If a non-zero starting offset is passed when the pattern  is  anchored,
3402         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
3403         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
3404         subject.         subject.
3405    
3406     How pcre_exec() returns captured substrings     How pcre_exec() returns captured substrings
3407    
3408         In general, a pattern matches a certain portion of the subject, and  in         In  general, a pattern matches a certain portion of the subject, and in
3409         addition,  further  substrings  from  the  subject may be picked out by         addition, further substrings from the subject  may  be  picked  out  by
3410         parts of the pattern. Following the usage  in  Jeffrey  Friedl's  book,         parts  of  the  pattern.  Following the usage in Jeffrey Friedl's book,
3411         this  is  called "capturing" in what follows, and the phrase "capturing         this is called "capturing" in what follows, and the  phrase  "capturing
3412         subpattern" is used for a fragment of a pattern that picks out  a  sub-         subpattern"  is  used for a fragment of a pattern that picks out a sub-
3413         string.  PCRE  supports several other kinds of parenthesized subpattern         string. PCRE supports several other kinds of  parenthesized  subpattern
3414         that do not cause substrings to be captured.         that do not cause substrings to be captured.
3415    
3416         Captured substrings are returned to the caller via a vector of integers         Captured substrings are returned to the caller via a vector of integers
3417         whose  address is passed in ovector. The number of elements in the vec-         whose address is passed in ovector. The number of elements in the  vec-
3418         tor is passed in ovecsize, which must be a non-negative  number.  Note:         tor  is  passed in ovecsize, which must be a non-negative number. Note:
3419         this argument is NOT the size of ovector in bytes.         this argument is NOT the size of ovector in bytes.
3420    
3421         The  first  two-thirds of the vector is used to pass back captured sub-         The first two-thirds of the vector is used to pass back  captured  sub-
3422         strings, each substring using a pair of integers. The  remaining  third         strings,  each  substring using a pair of integers. The remaining third
3423         of  the  vector is used as workspace by pcre_exec() while matching cap-         of the vector is used as workspace by pcre_exec() while  matching  cap-
3424         turing subpatterns, and is not available for passing back  information.         turing  subpatterns, and is not available for passing back information.
3425         The  number passed in ovecsize should always be a multiple of three. If         The number passed in ovecsize should always be a multiple of three.  If
3426         it is not, it is rounded down.         it is not, it is rounded down.
3427    
3428         When a match is successful, information about  captured  substrings  is         When  a  match  is successful, information about captured substrings is
3429         returned  in  pairs  of integers, starting at the beginning of ovector,         returned in pairs of integers, starting at the  beginning  of  ovector,
3430         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
3431         element  of  each pair is set to the byte offset of the first character         element of each pair is set to the byte offset of the  first  character
3432         in a substring, and the second is set to the byte offset of  the  first         in  a  substring, and the second is set to the byte offset of the first
3433         character  after  the end of a substring. Note: these values are always         character after the end of a substring. Note: these values  are  always
3434         byte offsets, even in UTF-8 mode. They are not character counts.         byte offsets, even in UTF-8 mode. They are not character counts.
3435    
3436         The first pair of integers, ovector[0]  and  ovector[1],  identify  the         The  first  pair  of  integers, ovector[0] and ovector[1], identify the
3437         portion  of  the subject string matched by the entire pattern. The next         portion of the subject string matched by the entire pattern.  The  next
3438         pair is used for the first capturing subpattern, and so on.  The  value         pair  is  used for the first capturing subpattern, and so on. The value
3439         returned by pcre_exec() is one more than the highest numbered pair that         returned by pcre_exec() is one more than the highest numbered pair that
3440         has been set.  For example, if two substrings have been  captured,  the         has  been  set.  For example, if two substrings have been captured, the
3441         returned  value is 3. If there are no capturing subpatterns, the return         returned value is 3. If there are no capturing subpatterns, the  return
3442         value from a successful match is 1, indicating that just the first pair         value from a successful match is 1, indicating that just the first pair
3443         of offsets has been set.         of offsets has been set.
3444    
3445         If a capturing subpattern is matched repeatedly, it is the last portion         If a capturing subpattern is matched repeatedly, it is the last portion
3446         of the string that it matched that is returned.         of the string that it matched that is returned.
3447    
3448         If the vector is too small to hold all the captured substring  offsets,         If  the vector is too small to hold all the captured substring offsets,
3449         it is used as far as possible (up to two-thirds of its length), and the         it is used as far as possible (up to two-thirds of its length), and the
3450         function returns a value of zero. If the substring offsets are  not  of         function  returns a value of zero. If neither the actual string matched
3451         interest,  pcre_exec()  may  be  called with ovector passed as NULL and         nor any captured substrings are of interest, pcre_exec() may be  called
3452         ovecsize as zero. However, if the pattern contains back references  and         with  ovector passed as NULL and ovecsize as zero. However, if the pat-
3453         the  ovector is not big enough to remember the related substrings, PCRE         tern contains back references and the ovector  is  not  big  enough  to
3454         has to get additional memory for use during matching. Thus it  is  usu-         remember  the related substrings, PCRE has to get additional memory for
3455         ally advisable to supply an ovector.         use during matching. Thus it is usually advisable to supply an  ovector
3456           of reasonable size.
3457    
3458           There  are  some  cases where zero is returned (indicating vector over-
3459           flow) when in fact the vector is exactly the right size for  the  final
3460           match. For example, consider the pattern
3461    
3462             (a)(?:(b)c|bd)
3463    
3464           If  a  vector of 6 elements (allowing for only 1 captured substring) is
3465           given with subject string "abd", pcre_exec() will try to set the second
3466           captured string, thereby recording a vector overflow, before failing to
3467           match "c" and backing up  to  try  the  second  alternative.  The  zero
3468           return,  however,  does  correctly  indicate that the maximum number of
3469           slots (namely 2) have been filled. In similar cases where there is tem-
3470           porary  overflow,  but  the final number of used slots is actually less
3471           than the maximum, a non-zero value is returned.
3472    
3473         The pcre_fullinfo() function can be used to find out how many capturing         The pcre_fullinfo() function can be used to find out how many capturing
3474         subpatterns there are in a compiled  pattern.  The  smallest  size  for         subpatterns  there  are  in  a  compiled pattern. The smallest size for
3475         ovector  that  will allow for n captured substrings, in addition to the         ovector that will allow for n captured substrings, in addition  to  the
3476         offsets of the substring matched by the whole pattern, is (n+1)*3.         offsets of the substring matched by the whole pattern, is (n+1)*3.
3477    
3478         It is possible for capturing subpattern number n+1 to match  some  part         It  is  possible for capturing subpattern number n+1 to match some part
3479         of the subject when subpattern n has not been used at all. For example,         of the subject when subpattern n has not been used at all. For example,
3480         if the string "abc" is matched  against  the  pattern  (a|(z))(bc)  the         if  the  string  "abc"  is  matched against the pattern (a|(z))(bc) the
3481         return from the function is 4, and subpatterns 1 and 3 are matched, but         return from the function is 4, and subpatterns 1 and 3 are matched, but
3482         2 is not. When this happens, both values in  the  offset  pairs  corre-         2  is  not.  When  this happens, both values in the offset pairs corre-
3483         sponding to unused subpatterns are set to -1.         sponding to unused subpatterns are set to -1.
3484    
3485         Offset  values  that correspond to unused subpatterns at the end of the         Offset values that correspond to unused subpatterns at the end  of  the
3486         expression are also set to -1. For example,  if  the  string  "abc"  is         expression  are  also  set  to  -1. For example, if the string "abc" is
3487         matched  against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not         matched against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are  not
3488         matched. The return from the function is 2, because  the  highest  used         matched.  The  return  from the function is 2, because the highest used
3489         capturing subpattern number is 1. However, you can refer to the offsets         capturing subpattern number is 1, and the offsets for  for  the  second
3490         for the second and third capturing subpatterns if  you  wish  (assuming         and  third  capturing subpatterns (assuming the vector is large enough,
3491         the vector is large enough, of course).         of course) are set to -1.
3492    
3493           Note: Elements in the first two-thirds of ovector that  do  not  corre-
3494           spond  to  capturing parentheses in the pattern are never changed. That
3495           is, if a pattern contains n capturing parentheses, no more  than  ovec-
3496           tor[0]  to ovector[2n+1] are set by pcre_exec(). The other elements (in
3497           the first two-thirds) retain whatever values they previously had.
3498    
3499         Some  convenience  functions  are  provided for extracting the captured         Some convenience functions are provided  for  extracting  the  captured
3500         substrings as separate strings. These are described below.         substrings as separate strings. These are described below.
3501    
3502     Error return values from pcre_exec()     Error return values from pcre_exec()
3503    
3504         If pcre_exec() fails, it returns a negative number. The  following  are         If  pcre_exec()  fails, it returns a negative number. The following are
3505         defined in the header file:         defined in the header file:
3506    
3507           PCRE_ERROR_NOMATCH        (-1)           PCRE_ERROR_NOMATCH        (-1)
# Line 2327  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3510  MATCHING A PATTERN: THE TRADITIONAL FUNC
3510    
3511           PCRE_ERROR_NULL           (-2)           PCRE_ERROR_NULL           (-2)
3512    
3513         Either  code  or  subject  was  passed as NULL, or ovector was NULL and         Either code or subject was passed as NULL,  or  ovector  was  NULL  and
3514         ovecsize was not zero.         ovecsize was not zero.
3515    
3516           PCRE_ERROR_BADOPTION      (-3)           PCRE_ERROR_BADOPTION      (-3)
# Line 2336  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3519  MATCHING A PATTERN: THE TRADITIONAL FUNC
3519    
3520           PCRE_ERROR_BADMAGIC       (-4)           PCRE_ERROR_BADMAGIC       (-4)
3521    
3522         PCRE stores a 4-byte "magic number" at the start of the compiled  code,         PCRE  stores a 4-byte "magic number" at the start of the compiled code,
3523         to catch the case when it is passed a junk pointer and to detect when a         to catch the case when it is passed a junk pointer and to detect when