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# 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           Starting with release 8.30, it is possible to compile two separate PCRE
29           libraries:  the  original,  which  supports  8-bit  character   strings
30           (including  UTF-8  strings),  and a second library that supports 16-bit
31           character strings (including UTF-16 strings). The build process  allows
32           either  one  or both to be built. The majority of the work to make this
33           possible was done by Zoltan Herczeg.
34    
35           The two libraries contain identical sets of functions, except that  the
36           names  in  the  16-bit  library start with pcre16_ instead of pcre_. To
37           avoid over-complication and reduce the documentation maintenance  load,
38           most of the documentation describes the 8-bit library, with the differ-
39           ences for the 16-bit library described separately in the  pcre16  page.
40           References  to  functions or structures of the form pcre[16]_xxx should
41           be  read  as  meaning  "pcre_xxx  when  using  the  8-bit  library  and
42           pcre16_xxx when using the 16-bit library".
43    
44         The  current implementation of PCRE corresponds approximately with Perl         The  current implementation of PCRE corresponds approximately with Perl
45         5.10/5.11, including support for UTF-8 encoded strings and Unicode gen-         5.12, including support for UTF-8/16 encoded strings and  Unicode  gen-
46         eral  category properties. However, UTF-8 and Unicode support has to be         eral  category properties. However, UTF-8/16 and Unicode support has to
47         explicitly enabled; it is not the default. The  Unicode  tables  corre-         be explicitly enabled; it is not the default. The Unicode tables corre-
48         spond to Unicode release 5.2.0.         spond to Unicode release 6.0.0.
49    
50         In  addition to the Perl-compatible matching function, PCRE contains an         In  addition to the Perl-compatible matching function, PCRE contains an
51         alternative function that matches the same compiled patterns in a  dif-         alternative function that matches the same compiled patterns in a  dif-
# Line 39  INTRODUCTION Line 55  INTRODUCTION
55    
56         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
57         have written wrappers and interfaces of various kinds.  In  particular,         have written wrappers and interfaces of various kinds.  In  particular,
58         Google  Inc.   have  provided  a comprehensive C++ wrapper. This is now         Google  Inc.   have  provided a comprehensive C++ wrapper for the 8-bit
59         included as part of the PCRE distribution. The pcrecpp page has details         library. This is now included as part of  the  PCRE  distribution.  The
60         of  this  interface.  Other  people's contributions can be found in the         pcrecpp  page  has  details of this interface. Other people's contribu-
61         Contrib directory at the primary FTP site, which is:         tions can be found in the Contrib directory at the  primary  FTP  site,
62           which is:
63    
64         ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre         ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre
65    
66         Details of exactly which Perl regular expression features are  and  are         Details  of  exactly which Perl regular expression features are and are
67         not supported by PCRE are given in separate documents. See the pcrepat-         not supported by PCRE are given in separate documents. See the pcrepat-
68         tern and pcrecompat pages. There is a syntax summary in the  pcresyntax         tern  and pcrecompat pages. There is a syntax summary in the pcresyntax
69         page.         page.
70    
71         Some  features  of  PCRE can be included, excluded, or changed when the         Some features of PCRE can be included, excluded, or  changed  when  the
72         library is built. The pcre_config() function makes it  possible  for  a         library  is  built.  The pcre_config() function makes it possible for a
73         client  to  discover  which  features are available. The features them-         client to discover which features are  available.  The  features  them-
74         selves are described in the pcrebuild page. Documentation about  build-         selves  are described in the pcrebuild page. Documentation about build-
75         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
76         NON-UNIX-USE files in the source distribution.         NON-UNIX-USE files in the source distribution.
77    
78         The library contains a number of undocumented  internal  functions  and         The  libraries contains a number of undocumented internal functions and
79         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
80         functions, but which are not intended  for  use  by  external  callers.         functions,  but  which  are  not  intended for use by external callers.
81         Their  names  all begin with "_pcre_", which hopefully will not provoke         Their names all begin with "_pcre_" or "_pcre16_", which hopefully will
82         any name clashes. In some environments, it is possible to control which         not  provoke  any name clashes. In some environments, it is possible to
83         external  symbols  are  exported when a shared library is built, and in         control which external symbols are exported when a  shared  library  is
84         these cases the undocumented symbols are not exported.         built, and in these cases the undocumented symbols are not exported.
85    
86    
87  USER DOCUMENTATION  USER DOCUMENTATION
88    
89         The user documentation for PCRE comprises a number  of  different  sec-         The  user  documentation  for PCRE comprises a number of different sec-
90         tions.  In the "man" format, each of these is a separate "man page". In         tions. In the "man" format, each of these is a separate "man page".  In
91         the HTML format, each is a separate page, linked from the  index  page.         the  HTML  format, each is a separate page, linked from the index page.
92         In  the  plain  text format, all the sections, except the pcredemo sec-         In the plain text format, all the sections, except  the  pcredemo  sec-
93         tion, are concatenated, for ease of searching. The sections are as fol-         tion, are concatenated, for ease of searching. The sections are as fol-
94         lows:         lows:
95    
96           pcre              this document           pcre              this document
97             pcre16            details of the 16-bit library
98           pcre-config       show PCRE installation configuration information           pcre-config       show PCRE installation configuration information
99           pcreapi           details of PCRE's native C API           pcreapi           details of PCRE's native C API
100           pcrebuild         options for building PCRE           pcrebuild         options for building PCRE
101           pcrecallout       details of the callout feature           pcrecallout       details of the callout feature
102           pcrecompat        discussion of Perl compatibility           pcrecompat        discussion of Perl compatibility
103           pcrecpp           details of the C++ wrapper           pcrecpp           details of the C++ wrapper for the 8-bit library
104           pcredemo          a demonstration C program that uses PCRE           pcredemo          a demonstration C program that uses PCRE
105           pcregrep          description of the pcregrep command           pcregrep          description of the pcregrep command (8-bit only)
106             pcrejit           discussion of the just-in-time optimization support
107             pcrelimits        details of size and other limits
108           pcrematching      discussion of the two matching algorithms           pcrematching      discussion of the two matching algorithms
109           pcrepartial       details of the partial matching facility           pcrepartial       details of the partial matching facility
110           pcrepattern       syntax and semantics of supported           pcrepattern       syntax and semantics of supported
111                               regular expressions                               regular expressions
112           pcreperform       discussion of performance issues           pcreperform       discussion of performance issues
113           pcreposix         the POSIX-compatible C API           pcreposix         the POSIX-compatible C API for the 8-bit library
114           pcreprecompile    details of saving and re-using precompiled patterns           pcreprecompile    details of saving and re-using precompiled patterns
115           pcresample        discussion of the pcredemo program           pcresample        discussion of the pcredemo program
116           pcrestack         discussion of stack usage           pcrestack         discussion of stack usage
117           pcresyntax        quick syntax reference           pcresyntax        quick syntax reference
118           pcretest          description of the pcretest testing command           pcretest          description of the pcretest testing command
119             pcreunicode       discussion of Unicode and UTF-8/16 support
120    
121         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
122         each C library function, listing its arguments and results.         each 8-bit C library function, listing its arguments and results.
123    
124    
125  LIMITATIONS  AUTHOR
126    
127         There are some size limitations in PCRE but it is hoped that they  will         Philip Hazel
128         never in practice be relevant.         University Computing Service
129           Cambridge CB2 3QH, England.
130    
131         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,
132         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,
133         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.  
134    
        All values in repeating quantifiers must be less than 65536.  
135    
136         There is no limit to the number of parenthesized subpatterns, but there  REVISION
        can be no more than 65535 capturing subpatterns.  
137    
138         The maximum length of name for a named subpattern is 32 characters, and         Last updated: 10 January 2012
139         the maximum number of named subpatterns is 10000.         Copyright (c) 1997-2012 University of Cambridge.
140    ------------------------------------------------------------------------------
141    
142    
143    PCRE(3)                                                                PCRE(3)
144    
        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.  
145    
146    NAME
147           PCRE - Perl-compatible regular expressions
148    
149  UTF-8 AND UNICODE PROPERTY SUPPORT         #include <pcre.h>
150    
        From release 3.3, PCRE has  had  some  support  for  character  strings  
        encoded  in the UTF-8 format. For release 4.0 this was greatly extended  
        to cover most common requirements, and in release 5.0  additional  sup-  
        port for Unicode general category properties was added.  
   
        In  order  process  UTF-8 strings, you must build PCRE to include UTF-8  
        support in the code, and, in addition,  you  must  call  pcre_compile()  
        with  the  PCRE_UTF8  option  flag,  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.  
   
        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.  
151    
152         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.  
153    
154     Validity of UTF-8 strings         pcre16 *pcre16_compile(PCRE_SPTR16 pattern, int options,
155                const char **errptr, int *erroffset,
156                const unsigned char *tableptr);
157    
158         When  you  set  the  PCRE_UTF8 flag, the strings passed as patterns and         pcre16 *pcre16_compile2(PCRE_SPTR16 pattern, int options,
159         subjects are (by default) checked for validity on entry to the relevant              int *errorcodeptr,
160         functions.  From  release 7.3 of PCRE, the check is according the rules              const char **errptr, int *erroffset,
161         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.  
162    
163         If  you  pass  an  invalid UTF-8 string when PCRE_NO_UTF8_CHECK is set,         pcre16_extra *pcre16_study(const pcre16 *code, int options,
164         what happens depends on why the string is invalid. If the  string  con-              const char **errptr);
        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.  
165    
166         If you want to process strings  of  values  in  the  full  range  0  to         void pcre16_free_study(pcre16_extra *extra);
        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.  
167    
168     General comments about UTF-8 mode         int pcre16_exec(const pcre16 *code, const pcre16_extra *extra,
169                PCRE_SPTR16 subject, int length, int startoffset,
170                int options, int *ovector, int ovecsize);
171    
172         1.  An  unbraced  hexadecimal  escape sequence (such as \xb3) matches a         int pcre16_dfa_exec(const pcre16 *code, const pcre16_extra *extra,
173         two-byte UTF-8 character if the value is greater than 127.              PCRE_SPTR16 subject, int length, int startoffset,
174                int options, int *ovector, int ovecsize,
175                int *workspace, int wscount);
176    
        2. Octal numbers up to \777 are recognized, and  match  two-byte  UTF-8  
        characters for values greater than \177.  
177    
178         3.  Repeat quantifiers apply to complete UTF-8 characters, not to indi-  PCRE 16-BIT API STRING EXTRACTION FUNCTIONS
        vidual bytes, for example: \x{100}{3}.  
179    
180         4. The dot metacharacter matches one UTF-8 character instead of a  sin-         int pcre16_copy_named_substring(const pcre16 *code,
181         gle byte.              PCRE_SPTR16 subject, int *ovector,
182                int stringcount, PCRE_SPTR16 stringname,
183                PCRE_UCHAR16 *buffer, int buffersize);
184    
185         5.  The  escape sequence \C can be used to match a single byte in UTF-8         int pcre16_copy_substring(PCRE_SPTR16 subject, int *ovector,
186         mode, but its use can lead to some strange effects.  This  facility  is              int stringcount, int stringnumber, PCRE_UCHAR16 *buffer,
187         not available in the alternative matching function, pcre_dfa_exec().              int buffersize);
188    
189         6.  The  character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly         int pcre16_get_named_substring(const pcre16 *code,
190         test characters of any code value, but, by default, the characters that              PCRE_SPTR16 subject, int *ovector,
191         PCRE  recognizes  as digits, spaces, or word characters remain the same              int stringcount, PCRE_SPTR16 stringname,
192         set as before, all with values less than 256. This  remains  true  even              PCRE_SPTR16 *stringptr);
        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.  
193    
194         7.  Similarly,  characters that match the POSIX named character classes         int pcre16_get_stringnumber(const pcre16 *code,
195         are all low-valued characters, unless the PCRE_UCP option is set.              PCRE_SPTR16 name);
196    
197           int pcre16_get_stringtable_entries(const pcre16 *code,
198                PCRE_SPTR16 name, PCRE_UCHAR16 **first, PCRE_UCHAR16 **last);
199    
200           int pcre16_get_substring(PCRE_SPTR16 subject, int *ovector,
201                int stringcount, int stringnumber,
202                PCRE_SPTR16 *stringptr);
203    
204           int pcre16_get_substring_list(PCRE_SPTR16 subject,
205                int *ovector, int stringcount, PCRE_SPTR16 **listptr);
206    
207           void pcre16_free_substring(PCRE_SPTR16 stringptr);
208    
209           void pcre16_free_substring_list(PCRE_SPTR16 *stringptr);
210    
211    
212    PCRE 16-BIT API AUXILIARY FUNCTIONS
213    
214           pcre16_jit_stack *pcre16_jit_stack_alloc(int startsize, int maxsize);
215    
216           void pcre16_jit_stack_free(pcre16_jit_stack *stack);
217    
218           void pcre16_assign_jit_stack(pcre16_extra *extra,
219                pcre16_jit_callback callback, void *data);
220    
221           const unsigned char *pcre16_maketables(void);
222    
223           int pcre16_fullinfo(const pcre16 *code, const pcre16_extra *extra,
224                int what, void *where);
225    
226           int pcre16_refcount(pcre16 *code, int adjust);
227    
228           int pcre16_config(int what, void *where);
229    
230           const char *pcre16_version(void);
231    
232           int pcre16_pattern_to_host_byte_order(pcre16 *code,
233                pcre16_extra *extra, const unsigned char *tables);
234    
235    
236    PCRE 16-BIT API INDIRECTED FUNCTIONS
237    
238           void *(*pcre16_malloc)(size_t);
239    
240           void (*pcre16_free)(void *);
241    
242           void *(*pcre16_stack_malloc)(size_t);
243    
244           void (*pcre16_stack_free)(void *);
245    
246           int (*pcre16_callout)(pcre16_callout_block *);
247    
248    
249    PCRE 16-BIT API 16-BIT-ONLY FUNCTION
250    
251           int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *output,
252                PCRE_SPTR16 input, int length, int *byte_order,
253                int keep_boms);
254    
255    
256    THE PCRE 16-BIT LIBRARY
257    
258           Starting  with  release  8.30, it is possible to compile a PCRE library
259           that supports 16-bit character strings, including  UTF-16  strings,  as
260           well  as  or instead of the original 8-bit library. The majority of the
261           work to make  this  possible  was  done  by  Zoltan  Herczeg.  The  two
262           libraries contain identical sets of functions, used in exactly the same
263           way. Only the names of the functions and the data types of their  argu-
264           ments  and results are different. To avoid over-complication and reduce
265           the documentation maintenance load,  most  of  the  PCRE  documentation
266           describes  the  8-bit  library,  with only occasional references to the
267           16-bit library. This page describes what is different when you use  the
268           16-bit library.
269    
270           WARNING:  A  single  application can be linked with both libraries, but
271           you must take care when processing any particular pattern to use  func-
272           tions  from  just one library. For example, if you want to study a pat-
273           tern that was compiled with  pcre16_compile(),  you  must  do  so  with
274           pcre16_study(), not pcre_study(), and you must free the study data with
275           pcre16_free_study().
276    
277    
278    THE HEADER FILE
279    
280           There is only one header file, pcre.h. It contains prototypes  for  all
281           the  functions  in  both  libraries,  as  well as definitions of flags,
282           structures, error codes, etc.
283    
284    
285    THE LIBRARY NAME
286    
287           In Unix-like systems, the 16-bit library is called libpcre16,  and  can
288           normally  be  accesss  by adding -lpcre16 to the command for linking an
289           application that uses PCRE.
290    
291    
292    STRING TYPES
293    
294           In the 8-bit library, strings are passed to PCRE library  functions  as
295           vectors  of  bytes  with  the  C  type "char *". In the 16-bit library,
296           strings are passed as vectors of unsigned 16-bit quantities. The  macro
297           PCRE_UCHAR16  specifies  an  appropriate  data type, and PCRE_SPTR16 is
298           defined as "const PCRE_UCHAR16 *". In very  many  environments,  "short
299           int" is a 16-bit data type. When PCRE is built, it defines PCRE_UCHAR16
300           as "short int", but checks that it really is a 16-bit data type. If  it
301           is not, the build fails with an error message telling the maintainer to
302           modify the definition appropriately.
303    
304    
305    STRUCTURE TYPES
306    
307           The types of the opaque structures that are used  for  compiled  16-bit
308           patterns  and  JIT stacks are pcre16 and pcre16_jit_stack respectively.
309           The  type  of  the  user-accessible  structure  that  is  returned   by
310           pcre16_study()  is  pcre16_extra, and the type of the structure that is
311           used for passing data to a callout  function  is  pcre16_callout_block.
312           These structures contain the same fields, with the same names, as their
313           8-bit counterparts. The only difference is that pointers  to  character
314           strings are 16-bit instead of 8-bit types.
315    
316    
317    16-BIT FUNCTIONS
318    
319           For  every function in the 8-bit library there is a corresponding func-
320           tion in the 16-bit library with a name that starts with pcre16_ instead
321           of  pcre_.  The  prototypes are listed above. In addition, there is one
322           extra function, pcre16_utf16_to_host_byte_order(). This  is  a  utility
323           function  that converts a UTF-16 character string to host byte order if
324           necessary. The other 16-bit  functions  expect  the  strings  they  are
325           passed to be in host byte order.
326    
327           The input and output arguments of pcre16_utf16_to_host_byte_order() may
328           point to the same address, that is, conversion in place  is  supported.
329           The output buffer must be at least as long as the input.
330    
331           The  length  argument  specifies the number of 16-bit data units in the
332           input string; a negative value specifies a zero-terminated string.
333    
334           If byte_order is NULL, it is assumed that the string starts off in host
335           byte  order. This may be changed by byte-order marks (BOMs) anywhere in
336           the string (commonly as the first character).
337    
338           If byte_order is not NULL, a non-zero value of the integer to which  it
339           points  means  that  the input starts off in host byte order, otherwise
340           the opposite order is assumed. Again, BOMs in  the  string  can  change
341           this. The final byte order is passed back at the end of processing.
342    
343           If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
344           copied into the output string. Otherwise they are discarded.
345    
346           The result of the function is the number of 16-bit  units  placed  into
347           the  output  buffer,  including  the  zero terminator if the string was
348           zero-terminated.
349    
350    
351    SUBJECT STRING OFFSETS
352    
353           The offsets within subject strings that are returned  by  the  matching
354           functions are in 16-bit units rather than bytes.
355    
356    
357    NAMED SUBPATTERNS
358    
359           The  name-to-number translation table that is maintained for named sub-
360           patterns uses 16-bit characters.  The  pcre16_get_stringtable_entries()
361           function returns the length of each entry in the table as the number of
362           16-bit data units.
363    
364    
365    OPTION NAMES
366    
367           There   are   two   new   general   option   names,   PCRE_UTF16    and
368           PCRE_NO_UTF16_CHECK,     which     correspond    to    PCRE_UTF8    and
369           PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
370           define the same bits in the options word.
371    
372           For  the  pcre16_config() function there is an option PCRE_CONFIG_UTF16
373           that returns 1 if UTF-16 support is configured, otherwise  0.  If  this
374           option  is given to pcre_config(), or if the PCRE_CONFIG_UTF8 option is
375           given to pcre16_config(), the result is the PCRE_ERROR_BADOPTION error.
376    
377    
378    CHARACTER CODES
379    
380           In 16-bit mode, when  PCRE_UTF16  is  not  set,  character  values  are
381           treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
382           that they can range from 0 to 0xffff instead of 0  to  0xff.  Character
383           types  for characters less than 0xff can therefore be influenced by the
384           locale in the same way as before.  Characters greater  than  0xff  have
385           only one case, and no "type" (such as letter or digit).
386    
387           In  UTF-16  mode,  the  character  code  is  Unicode, in the range 0 to
388           0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
389           because  those  are "surrogate" values that are used in pairs to encode
390           values greater than 0xffff.
391    
392           A UTF-16 string can indicate its endianness by special code knows as  a
393           byte-order mark (BOM). The PCRE functions do not handle this, expecting
394           strings  to  be  in  host  byte  order.  A  utility   function   called
395           pcre16_utf16_to_host_byte_order()  is  provided  to help with this (see
396           above).
397    
398    
399    ERROR NAMES
400    
401           The errors PCRE_ERROR_BADUTF16_OFFSET and PCRE_ERROR_SHORTUTF16  corre-
402           spond  to  their  8-bit  counterparts.  The error PCRE_ERROR_BADMODE is
403           given when a compiled pattern is passed to a  function  that  processes
404           patterns  in  the  other  mode, for example, if a pattern compiled with
405           pcre_compile() is passed to pcre16_exec().
406    
407           There are new error codes whose names  begin  with  PCRE_UTF16_ERR  for
408           invalid  UTF-16  strings,  corresponding to the PCRE_UTF8_ERR codes for
409           UTF-8 strings that are described in the section entitled "Reason  codes
410           for  invalid UTF-8 strings" in the main pcreapi page. The UTF-16 errors
411           are:
412    
413             PCRE_UTF16_ERR1  Missing low surrogate at end of string
414             PCRE_UTF16_ERR2  Invalid low surrogate follows high surrogate
415             PCRE_UTF16_ERR3  Isolated low surrogate
416             PCRE_UTF16_ERR4  Invalid character 0xfffe
417    
418    
419    ERROR TEXTS
420    
421           If there is an error while compiling a pattern, the error text that  is
422           passed  back by pcre16_compile() or pcre16_compile2() is still an 8-bit
423           character string, zero-terminated.
424    
425    
426    CALLOUTS
427    
428         8. However, the Perl 5.10 horizontal and vertical  whitespace  matching         The subject and mark fields in the callout block that is  passed  to  a
429         escapes (\h, \H, \v, and \V) do match all the appropriate Unicode char-         callout function point to 16-bit vectors.
430         acters, whether or not PCRE_UCP is set.  
431    
432         9. Case-insensitive matching applies only to  characters  whose  values  TESTING
433         are  less than 128, unless PCRE is built with Unicode property support.  
434         Even when Unicode property support is available, PCRE  still  uses  its         The  pcretest  program continues to operate with 8-bit input and output
435         own  character  tables when checking the case of low-valued characters,         files, but it can be used for testing the 16-bit library. If it is  run
436         so as not to degrade performance.  The Unicode property information  is         with the command line option -16, patterns and subject strings are con-
437         used only for characters with higher values. Even when Unicode property         verted from 8-bit to 16-bit before being passed to PCRE, and the 16-bit
438         support is available, PCRE supports case-insensitive matching only when         library  functions  are used instead of the 8-bit ones. Returned 16-bit
439         there  is  a  one-to-one  mapping between a letter's cases. There are a         strings are converted to 8-bit for output. If the 8-bit library was not
440         small number of many-to-one mappings in Unicode;  these  are  not  sup-         compiled, pcretest defaults to 16-bit and the -16 option is ignored.
441         ported by PCRE.  
442           When  PCRE  is  being built, the RunTest script that is called by "make
443           check" uses the pcretest -C option to discover which of the  8-bit  and
444           16-bit libraries has been built, and runs the tests appropriately.
445    
446    
447    NOT SUPPORTED IN 16-BIT MODE
448    
449           Not all the features of the 8-bit library are available with the 16-bit
450           library. The C++ and POSIX wrapper functions  support  only  the  8-bit
451           library, and the pcregrep program is at present 8-bit only.
452    
453    
454  AUTHOR  AUTHOR
# Line 260  AUTHOR Line 457  AUTHOR
457         University Computing Service         University Computing Service
458         Cambridge CB2 3QH, England.         Cambridge CB2 3QH, England.
459    
        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.  
   
460    
461  REVISION  REVISION
462    
463         Last updated: 12 May 2010         Last updated: 08 January 2012
464         Copyright (c) 1997-2010 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
465  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
466    
467    
468  PCREBUILD(3)                                                      PCREBUILD(3)  PCREBUILD(3)                                                      PCREBUILD(3)
469    
470    
# Line 308  PCRE BUILD-TIME OPTIONS Line 501  PCRE BUILD-TIME OPTIONS
501         is not described.         is not described.
502    
503    
504    BUILDING 8-BIT and 16-BIT LIBRARIES
505    
506           By  default,  a  library  called libpcre is built, containing functions
507           that take string arguments contained in vectors  of  bytes,  either  as
508           single-byte  characters,  or interpreted as UTF-8 strings. You can also
509           build a separate library, called libpcre16, in which strings  are  con-
510           tained  in  vectors of 16-bit data units and interpreted either as sin-
511           gle-unit characters or UTF-16 strings, by adding
512    
513             --enable-pcre16
514    
515           to the configure command. If you do not want the 8-bit library, add
516    
517             --disable-pcre8
518    
519           as well. At least one of the two libraries must be built. Note that the
520           C++  and  POSIX wrappers are for the 8-bit library only, and that pcre-
521           grep is an 8-bit program. None of these are built if  you  select  only
522           the 16-bit library.
523    
524    
525    BUILDING SHARED AND STATIC LIBRARIES
526    
527           The  PCRE building process uses libtool to build both shared and static
528           Unix libraries by default. You can suppress one of these by adding  one
529           of
530    
531             --disable-shared
532             --disable-static
533    
534           to the configure command, as required.
535    
536    
537  C++ SUPPORT  C++ SUPPORT
538    
539         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
540         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,
541         library for PCRE. You can disable this by adding         it  automatically  builds  the C++ wrapper library (which supports only
542           8-bit strings). You can disable this by adding
543    
544           --disable-cpp           --disable-cpp
545    
546         to the configure command.         to the configure command.
547    
548    
549  UTF-8 SUPPORT  UTF-8 and UTF-16 SUPPORT
550    
551         To build PCRE with support for UTF-8 Unicode character strings, add         To build PCRE with support for UTF Unicode character strings, add
552    
553           --enable-utf8           --enable-utf
554    
555         to  the  configure  command.  Of  itself, this does not make PCRE treat         to the configure command.  This  setting  applies  to  both  libraries,
556         strings as UTF-8. As well as compiling PCRE with this option, you  also         adding support for UTF-8 to the 8-bit library and support for UTF-16 to
557         have  have to set the PCRE_UTF8 option when you call the pcre_compile()         the 16-bit library. There are no separate options  for  enabling  UTF-8
558         or pcre_compile2() functions.         and  UTF-16  independently because that would allow ridiculous settings
559           such as  requesting  UTF-16  support  while  building  only  the  8-bit
560           library.  It  is not possible to build one library with UTF support and
561           the other without in the same configuration. (For backwards compatibil-
562           ity, --enable-utf8 is a synonym of --enable-utf.)
563    
564           Of  itself,  this  setting does not make PCRE treat strings as UTF-8 or
565           UTF-16. As well as compiling PCRE with this option, you also have  have
566           to set the PCRE_UTF8 or PCRE_UTF16 option when you call one of the pat-
567           tern compiling functions.
568    
569         If you set --enable-utf8 when compiling in an EBCDIC environment,  PCRE         If you set --enable-utf when compiling in an EBCDIC  environment,  PCRE
570         expects its input to be either ASCII or UTF-8 (depending on the runtime         expects its input to be either ASCII or UTF-8 (depending on the runtime
571         option). It is not possible to support both EBCDIC and UTF-8  codes  in         option). It is not possible to support both EBCDIC and UTF-8  codes  in
572         the  same  version  of  the  library.  Consequently,  --enable-utf8 and         the  same  version  of  the  library.  Consequently,  --enable-utf  and
573         --enable-ebcdic are mutually exclusive.         --enable-ebcdic are mutually exclusive.
574    
575    
576  UNICODE CHARACTER PROPERTY SUPPORT  UNICODE CHARACTER PROPERTY SUPPORT
577    
578         UTF-8 support allows PCRE to process character values greater than  255         UTF support allows the libraries to process character codepoints up  to
579         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
580         vide any facilities for accessing the properties of such characters. If         not provide any facilities for accessing the properties of such charac-
581         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,
582         refer to Unicode character properties, you must add         which refer to Unicode character properties, you must add
583    
584           --enable-unicode-properties           --enable-unicode-properties
585    
586         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
587         not explicitly requested it.         not explicitly requested it.
588    
589         Including  Unicode  property  support  adds around 30K of tables to the         Including  Unicode  property  support  adds around 30K of tables to the
# Line 355  UNICODE CHARACTER PROPERTY SUPPORT Line 591  UNICODE CHARACTER PROPERTY SUPPORT
591         are supported. Details are given in the pcrepattern documentation.         are supported. Details are given in the pcrepattern documentation.
592    
593    
594    JUST-IN-TIME COMPILER SUPPORT
595    
596           Just-in-time compiler support is included in the build by specifying
597    
598             --enable-jit
599    
600           This  support  is available only for certain hardware architectures. If
601           this option is set for an  unsupported  architecture,  a  compile  time
602           error  occurs.   See  the pcrejit documentation for a discussion of JIT
603           usage. When JIT support is enabled, pcregrep automatically makes use of
604           it, unless you add
605    
606             --disable-pcregrep-jit
607    
608           to the "configure" command.
609    
610    
611  CODE VALUE OF NEWLINE  CODE VALUE OF NEWLINE
612    
613         By  default,  PCRE interprets the linefeed (LF) character as indicating         By  default,  PCRE interprets the linefeed (LF) character as indicating
# Line 401  WHAT \R MATCHES Line 654  WHAT \R MATCHES
654         functions are called.         functions are called.
655    
656    
 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.  
   
   
657  POSIX MALLOC USAGE  POSIX MALLOC USAGE
658    
659         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
660         umentation), additional working storage is  required  for  holding  the         pcreposix documentation), additional working storage  is  required  for
661         pointers  to capturing substrings, because PCRE requires three integers         holding  the  pointers  to  capturing substrings, because PCRE requires
662         per substring, whereas the POSIX interface provides only  two.  If  the         three integers per substring, whereas the POSIX interface provides only
663         number of expected substrings is small, the wrapper function uses space         two.  If  the number of expected substrings is small, the wrapper func-
664         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-
665         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
666         can be changed by adding a setting such as         longer used is 10; it can be changed by adding a setting such as
667    
668           --with-posix-malloc-threshold=20           --with-posix-malloc-threshold=20
669    
# Line 436  HANDLING VERY LARGE PATTERNS Line 677  HANDLING VERY LARGE PATTERNS
677         nation metacharacter). By default, two-byte values are used  for  these         nation metacharacter). By default, two-byte values are used  for  these
678         offsets,  leading  to  a  maximum size for a compiled pattern of around         offsets,  leading  to  a  maximum size for a compiled pattern of around
679         64K. This is sufficient to handle all but the most  gigantic  patterns.         64K. This is sufficient to handle all but the most  gigantic  patterns.
680         Nevertheless,  some  people do want to process truyl enormous patterns,         Nevertheless,  some  people do want to process truly enormous patterns,
681         so it is possible to compile PCRE to use three-byte or  four-byte  off-         so it is possible to compile PCRE to use three-byte or  four-byte  off-
682         sets by adding a setting such as         sets by adding a setting such as
683    
684           --with-link-size=3           --with-link-size=3
685    
686         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
687         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. Using  longer  offsets
688         additional bytes when handling them.         slows down the operation of PCRE because it has to load additional data
689           when handling them.
690    
691    
692  AVOIDING EXCESSIVE STACK USAGE  AVOIDING EXCESSIVE STACK USAGE
693    
694         When matching with the pcre_exec() function, PCRE implements backtrack-         When matching with the pcre_exec() function, PCRE implements backtrack-
695         ing by making recursive calls to an internal function  called  match().         ing  by  making recursive calls to an internal function called match().
696         In  environments  where  the size of the stack is limited, this can se-         In environments where the size of the stack is limited,  this  can  se-
697         verely limit PCRE's operation. (The Unix environment does  not  usually         verely  limit  PCRE's operation. (The Unix environment does not usually
698         suffer from this problem, but it may sometimes be necessary to increase         suffer from this problem, but it may sometimes be necessary to increase
699         the maximum stack size.  There is a discussion in the  pcrestack  docu-         the  maximum  stack size.  There is a discussion in the pcrestack docu-
700         mentation.)  An alternative approach to recursion that uses memory from         mentation.) An alternative approach to recursion that uses memory  from
701         the heap to remember data, instead of using recursive  function  calls,         the  heap  to remember data, instead of using recursive function calls,
702         has  been  implemented to work round the problem of limited stack size.         has been implemented to work round the problem of limited  stack  size.
703         If you want to build a version of PCRE that works this way, add         If you want to build a version of PCRE that works this way, add
704    
705           --disable-stack-for-recursion           --disable-stack-for-recursion
706    
707         to the configure command. With this configuration, PCRE  will  use  the         to  the  configure  command. With this configuration, PCRE will use the
708         pcre_stack_malloc  and pcre_stack_free variables to call memory manage-         pcre_stack_malloc and pcre_stack_free variables to call memory  manage-
709         ment functions. By default these point to malloc() and free(), but  you         ment  functions. By default these point to malloc() and free(), but you
710         can replace the pointers so that your own functions are used instead.         can replace the pointers so that your own functions are used instead.
711    
712         Separate  functions  are  provided  rather  than  using pcre_malloc and         Separate functions are  provided  rather  than  using  pcre_malloc  and
713         pcre_free because the  usage  is  very  predictable:  the  block  sizes         pcre_free  because  the  usage  is  very  predictable:  the block sizes
714         requested  are  always  the  same,  and  the blocks are always freed in         requested are always the same, and  the  blocks  are  always  freed  in
715         reverse order. A calling program might be able to  implement  optimized         reverse  order.  A calling program might be able to implement optimized
716         functions  that  perform  better  than  malloc()  and free(). PCRE runs         functions that perform better  than  malloc()  and  free().  PCRE  runs
717         noticeably more slowly when built in this way. This option affects only         noticeably more slowly when built in this way. This option affects only
718         the pcre_exec() function; it is not relevant for pcre_dfa_exec().         the pcre_exec() function; it is not relevant for pcre_dfa_exec().
719    
720    
721  LIMITING PCRE RESOURCE USAGE  LIMITING PCRE RESOURCE USAGE
722    
723         Internally,  PCRE has a function called match(), which it calls repeat-         Internally, PCRE has a function called match(), which it calls  repeat-
724         edly  (sometimes  recursively)  when  matching  a  pattern   with   the         edly   (sometimes   recursively)  when  matching  a  pattern  with  the
725         pcre_exec()  function.  By controlling the maximum number of times this         pcre_exec() function. By controlling the maximum number of  times  this
726         function may be called during a single matching operation, a limit  can         function  may be called during a single matching operation, a limit can
727         be  placed  on  the resources used by a single call to pcre_exec(). The         be placed on the resources used by a single call  to  pcre_exec().  The
728         limit can be changed at run time, as described in the pcreapi  documen-         limit  can be changed at run time, as described in the pcreapi documen-
729         tation.  The default is 10 million, but this can be changed by adding a         tation. The default is 10 million, but this can be changed by adding  a
730         setting such as         setting such as
731    
732           --with-match-limit=500000           --with-match-limit=500000
733    
734         to  the  configure  command.  This  setting  has  no  effect   on   the         to   the   configure  command.  This  setting  has  no  effect  on  the
735         pcre_dfa_exec() matching function.         pcre_dfa_exec() matching function.
736    
737         In  some  environments  it is desirable to limit the depth of recursive         In some environments it is desirable to limit the  depth  of  recursive
738         calls of match() more strictly than the total number of calls, in order         calls of match() more strictly than the total number of calls, in order
739         to  restrict  the maximum amount of stack (or heap, if --disable-stack-         to restrict the maximum amount of stack (or heap,  if  --disable-stack-
740         for-recursion is specified) that is used. A second limit controls this;         for-recursion is specified) that is used. A second limit controls this;
741         it  defaults  to  the  value  that is set for --with-match-limit, which         it defaults to the value that  is  set  for  --with-match-limit,  which
742         imposes no additional constraints. However, you can set a  lower  limit         imposes  no  additional constraints. However, you can set a lower limit
743         by adding, for example,         by adding, for example,
744    
745           --with-match-limit-recursion=10000           --with-match-limit-recursion=10000
746    
747         to  the  configure  command.  This  value can also be overridden at run         to the configure command. This value can  also  be  overridden  at  run
748         time.         time.
749    
750    
751  CREATING CHARACTER TABLES AT BUILD TIME  CREATING CHARACTER TABLES AT BUILD TIME
752    
753         PCRE uses fixed tables for processing characters whose code values  are         PCRE  uses fixed tables for processing characters whose code values are
754         less  than 256. By default, PCRE is built with a set of tables that are         less than 256. By default, PCRE is built with a set of tables that  are
755         distributed in the file pcre_chartables.c.dist. These  tables  are  for         distributed  in  the  file pcre_chartables.c.dist. These tables are for
756         ASCII codes only. If you add         ASCII codes only. If you add
757    
758           --enable-rebuild-chartables           --enable-rebuild-chartables
759    
760         to  the  configure  command, the distributed tables are no longer used.         to the configure command, the distributed tables are  no  longer  used.
761         Instead, a program called dftables is compiled and  run.  This  outputs         Instead,  a  program  called dftables is compiled and run. This outputs
762         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
763         C runtime system. (This method of replacing the tables does not work if         C runtime system. (This method of replacing the tables does not work if
764         you  are cross compiling, because dftables is run on the local host. If         you are cross compiling, because dftables is run on the local host.  If
765         you need to create alternative tables when cross  compiling,  you  will         you  need  to  create alternative tables when cross compiling, you will
766         have to do so "by hand".)         have to do so "by hand".)
767    
768    
769  USING EBCDIC CODE  USING EBCDIC CODE
770    
771         PCRE  assumes  by  default that it will run in an environment where the         PCRE assumes by default that it will run in an  environment  where  the
772         character code is ASCII (or Unicode, which is  a  superset  of  ASCII).         character  code  is  ASCII  (or Unicode, which is a superset of ASCII).
773         This  is  the  case for most computer operating systems. PCRE can, how-         This is the case for most computer operating systems.  PCRE  can,  how-
774         ever, be compiled to run in an EBCDIC environment by adding         ever, be compiled to run in an EBCDIC environment by adding
775    
776           --enable-ebcdic           --enable-ebcdic
777    
778         to the configure command. This setting implies --enable-rebuild-charta-         to the configure command. This setting implies --enable-rebuild-charta-
779         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
780         environment (for example,  an  IBM  mainframe  operating  system).  The         environment  (for  example,  an  IBM  mainframe  operating system). The
781         --enable-ebcdic option is incompatible with --enable-utf8.         --enable-ebcdic option is incompatible with --enable-utf.
782    
783    
784  PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT  PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT
# Line 549  PCREGREP OPTIONS FOR COMPRESSED FILE SUP Line 791  PCREGREP OPTIONS FOR COMPRESSED FILE SUP
791           --enable-pcregrep-libbz2           --enable-pcregrep-libbz2
792    
793         to the configure command. These options naturally require that the rel-         to the configure command. These options naturally require that the rel-
794         evant libraries are installed on your system. Configuration  will  fail         evant  libraries  are installed on your system. Configuration will fail
795         if they are not.         if they are not.
796    
797    
798    PCREGREP BUFFER SIZE
799    
800           pcregrep uses an internal buffer to hold a "window" on the file  it  is
801           scanning, in order to be able to output "before" and "after" lines when
802           it finds a match. The size of the buffer is controlled by  a  parameter
803           whose default value is 20K. The buffer itself is three times this size,
804           but because of the way it is used for holding "before" lines, the long-
805           est  line  that  is guaranteed to be processable is the parameter size.
806           You can change the default parameter value by adding, for example,
807    
808             --with-pcregrep-bufsize=50K
809    
810           to the configure command. The caller of pcregrep can, however, override
811           this value by specifying a run-time option.
812    
813    
814  PCRETEST OPTION FOR LIBREADLINE SUPPORT  PCRETEST OPTION FOR LIBREADLINE SUPPORT
815    
816         If you add         If you add
# Line 586  PCRETEST OPTION FOR LIBREADLINE SUPPORT Line 844  PCRETEST OPTION FOR LIBREADLINE SUPPORT
844    
845  SEE ALSO  SEE ALSO
846    
847         pcreapi(3), pcre_config(3).         pcreapi(3), pcre16, pcre_config(3).
848    
849    
850  AUTHOR  AUTHOR
# Line 598  AUTHOR Line 856  AUTHOR
856    
857  REVISION  REVISION
858    
859         Last updated: 29 September 2009         Last updated: 07 January 2012
860         Copyright (c) 1997-2009 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
861  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
862    
863    
864  PCREMATCHING(3)                                                PCREMATCHING(3)  PCREMATCHING(3)                                                PCREMATCHING(3)
865    
866    
# Line 615  PCRE MATCHING ALGORITHMS Line 873  PCRE MATCHING ALGORITHMS
873         This document describes the two different algorithms that are available         This document describes the two different algorithms that are available
874         in PCRE for matching a compiled regular expression against a given sub-         in PCRE for matching a compiled regular expression against a given sub-
875         ject  string.  The  "standard"  algorithm  is  the  one provided by the         ject  string.  The  "standard"  algorithm  is  the  one provided by the
876         pcre_exec() function.  This works in the same was  as  Perl's  matching         pcre_exec() and pcre16_exec() functions. These work in the same was  as
877         function, and provides a Perl-compatible matching operation.         Perl's matching function, and provide a Perl-compatible matching opera-
878           tion. The just-in-time (JIT) optimization  that  is  described  in  the
879         An  alternative  algorithm is provided by the pcre_dfa_exec() function;         pcrejit documentation is compatible with these functions.
880         this operates in a different way, and is not  Perl-compatible.  It  has  
881         advantages  and disadvantages compared with the standard algorithm, and         An  alternative  algorithm  is  provided  by  the  pcre_dfa_exec()  and
882         these are described below.         pcre16_dfa_exec() functions; they operate in a different way,  and  are
883           not  Perl-compatible. This alternative has advantages and disadvantages
884           compared with the standard algorithm, and these are described below.
885    
886         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
887         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 957  THE ALTERNATIVE MATCHING ALGORITHM
957         represent the different matching possibilities (if there are none,  the         represent the different matching possibilities (if there are none,  the
958         match  has  failed).   Thus,  if there is more than one possible match,         match  has  failed).   Thus,  if there is more than one possible match,
959         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-
960         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
961         (which is necessarily the shortest) is found.         an option to stop the algorithm after the first match (which is  neces-
962           sarily the shortest) is found.
963    
964         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
965         subject. If the pattern         subject. If the pattern
966    
967           cat(er(pillar)?)           cat(er(pillar)?)?
968    
969         is  matched  against the string "the caterpillar catchment", the result         is matched against the string "the caterpillar catchment",  the  result
970         will be the three strings "cat", "cater", and "caterpillar" that  start         will  be the three strings "caterpillar", "cater", and "cat" that start
971         at the fourth character of the subject. The algorithm does not automat-         at the fifth character of the subject. The algorithm does not automati-
972         ically move on to find matches that start at later positions.         cally move on to find matches that start at later positions.
973    
974         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
975         supported by the alternative matching algorithm. They are as follows:         supported by the alternative matching algorithm. They are as follows:
976    
977         1.  Because  the  algorithm  finds  all possible matches, the greedy or         1. Because the algorithm finds all  possible  matches,  the  greedy  or
978         ungreedy nature of repetition quantifiers is not relevant.  Greedy  and         ungreedy  nature  of repetition quantifiers is not relevant. Greedy and
979         ungreedy quantifiers are treated in exactly the same way. However, pos-         ungreedy quantifiers are treated in exactly the same way. However, pos-
980         sessive quantifiers can make a difference when what follows could  also         sessive  quantifiers can make a difference when what follows could also
981         match what is quantified, for example in a pattern like this:         match what is quantified, for example in a pattern like this:
982    
983           ^a++\w!           ^a++\w!
984    
985         This  pattern matches "aaab!" but not "aaa!", which would be matched by         This pattern matches "aaab!" but not "aaa!", which would be matched  by
986         a non-possessive quantifier. Similarly, if an atomic group is  present,         a  non-possessive quantifier. Similarly, if an atomic group is present,
987         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,
988         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
989         pattern.         pattern.
990    
991         2. When dealing with multiple paths through the tree simultaneously, it         2. When dealing with multiple paths through the tree simultaneously, it
992         is not straightforward to keep track of  captured  substrings  for  the         is  not  straightforward  to  keep track of captured substrings for the
993         different  matching  possibilities,  and  PCRE's implementation of this         different matching possibilities, and  PCRE's  implementation  of  this
994         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-
995         strings are available.         strings are available.
996    
997         3.  Because no substrings are captured, back references within the pat-         3. Because no substrings are captured, back references within the  pat-
998         tern are not supported, and cause errors if encountered.         tern are not supported, and cause errors if encountered.
999    
1000         4. For the same reason, conditional expressions that use  a  backrefer-         4.  For  the same reason, conditional expressions that use a backrefer-
1001         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
1002         supported.         supported.
1003    
1004         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
1005         sequence, which resets the start of the match when encountered (but may         sequence, which resets the start of the match when encountered (but may
1006         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
1007         error if encountered.         error if encountered.
1008    
1009         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
1010         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.
1011    
1012         7. The \C escape sequence, which (in the standard algorithm) matches  a         7.  The  \C  escape  sequence, which (in the standard algorithm) always
1013         single  byte, even in UTF-8 mode, is not supported because the alterna-         matches a single data unit, even in UTF-8 or UTF-16 modes, is not  sup-
1014         tive algorithm moves through the subject  string  one  character  at  a         ported  in these modes, because the alternative algorithm moves through
1015         time, for all active paths through the tree.         the subject string one character (not data unit) at  a  time,  for  all
1016           active paths through the tree.
1017    
1018         8.  Except for (*FAIL), the backtracking control verbs such as (*PRUNE)         8.  Except for (*FAIL), the backtracking control verbs such as (*PRUNE)
1019         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 1031  ADVANTAGES OF THE ALTERNATIVE ALGORITHM
1031         things with callouts.         things with callouts.
1032    
1033         2.  Because  the  alternative  algorithm  scans the subject string just         2.  Because  the  alternative  algorithm  scans the subject string just
1034         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-
1035         subject  strings  to  the matching function in several pieces, checking         sible  to  pass  very  long subject strings to the matching function in
1036         for partial matching each time.  The  pcrepartial  documentation  gives         several pieces, checking for partial matching each time. Although it is
1037         details of partial matching.         possible  to  do multi-segment matching using the standard algorithm by
1038           retaining partially matched substrings, it  is  more  complicated.  The
1039           pcrepartial  documentation  gives  details of partial matching and dis-
1040           cusses multi-segment matching.
1041    
1042    
1043  DISADVANTAGES OF THE ALTERNATIVE ALGORITHM  DISADVANTAGES OF THE ALTERNATIVE ALGORITHM
1044    
1045         The alternative algorithm suffers from a number of disadvantages:         The alternative algorithm suffers from a number of disadvantages:
1046    
1047         1.  It  is  substantially  slower  than the standard algorithm. This is         1. It is substantially slower than  the  standard  algorithm.  This  is
1048         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
1049         because it is less susceptible to optimization.         because it is less susceptible to optimization.
1050    
1051         2. Capturing parentheses and back references are not supported.         2. Capturing parentheses and back references are not supported.
# Line 798  AUTHOR Line 1063  AUTHOR
1063    
1064  REVISION  REVISION
1065    
1066         Last updated: 29 September 2009         Last updated: 08 January 2012
1067         Copyright (c) 1997-2009 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
1068  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1069    
1070    
1071  PCREAPI(3)                                                          PCREAPI(3)  PCREAPI(3)                                                          PCREAPI(3)
1072    
1073    
1074  NAME  NAME
1075         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
1076    
1077           #include <pcre.h>
1078    
 PCRE NATIVE API  
1079    
1080         #include <pcre.h>  PCRE NATIVE API BASIC FUNCTIONS
1081    
1082         pcre *pcre_compile(const char *pattern, int options,         pcre *pcre_compile(const char *pattern, int options,
1083              const char **errptr, int *erroffset,              const char **errptr, int *erroffset,
# Line 826  PCRE NATIVE API Line 1091  PCRE NATIVE API
1091         pcre_extra *pcre_study(const pcre *code, int options,         pcre_extra *pcre_study(const pcre *code, int options,
1092              const char **errptr);              const char **errptr);
1093    
1094           void pcre_free_study(pcre_extra *extra);
1095    
1096         int pcre_exec(const pcre *code, const pcre_extra *extra,         int pcre_exec(const pcre *code, const pcre_extra *extra,
1097              const char *subject, int length, int startoffset,              const char *subject, int length, int startoffset,
1098              int options, int *ovector, int ovecsize);              int options, int *ovector, int ovecsize);
# Line 835  PCRE NATIVE API Line 1102  PCRE NATIVE API
1102              int options, int *ovector, int ovecsize,              int options, int *ovector, int ovecsize,
1103              int *workspace, int wscount);              int *workspace, int wscount);
1104    
1105    
1106    PCRE NATIVE API STRING EXTRACTION FUNCTIONS
1107    
1108         int pcre_copy_named_substring(const pcre *code,         int pcre_copy_named_substring(const pcre *code,
1109              const char *subject, int *ovector,              const char *subject, int *ovector,
1110              int stringcount, const char *stringname,              int stringcount, const char *stringname,
# Line 866  PCRE NATIVE API Line 1136  PCRE NATIVE API
1136    
1137         void pcre_free_substring_list(const char **stringptr);         void pcre_free_substring_list(const char **stringptr);
1138    
1139    
1140    PCRE NATIVE API AUXILIARY FUNCTIONS
1141    
1142           pcre_jit_stack *pcre_jit_stack_alloc(int startsize, int maxsize);
1143    
1144           void pcre_jit_stack_free(pcre_jit_stack *stack);
1145    
1146           void pcre_assign_jit_stack(pcre_extra *extra,
1147                pcre_jit_callback callback, void *data);
1148    
1149         const unsigned char *pcre_maketables(void);         const unsigned char *pcre_maketables(void);
1150    
1151         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
1152              int what, void *where);              int what, void *where);
1153    
        int pcre_info(const pcre *code, int *optptr, int *firstcharptr);  
   
1154         int pcre_refcount(pcre *code, int adjust);         int pcre_refcount(pcre *code, int adjust);
1155    
1156         int pcre_config(int what, void *where);         int pcre_config(int what, void *where);
1157    
1158         char *pcre_version(void);         const char *pcre_version(void);
1159    
1160           int pcre_pattern_to_host_byte_order(pcre *code,
1161                pcre_extra *extra, const unsigned char *tables);
1162    
1163    
1164    PCRE NATIVE API INDIRECTED FUNCTIONS
1165    
1166         void *(*pcre_malloc)(size_t);         void *(*pcre_malloc)(size_t);
1167    
# Line 890  PCRE NATIVE API Line 1174  PCRE NATIVE API
1174         int (*pcre_callout)(pcre_callout_block *);         int (*pcre_callout)(pcre_callout_block *);
1175    
1176    
1177    PCRE 8-BIT AND 16-BIT LIBRARIES
1178    
1179           From  release  8.30,  PCRE  can  be  compiled as a library for handling
1180           16-bit character strings as  well  as,  or  instead  of,  the  original
1181           library that handles 8-bit character strings. To avoid too much compli-
1182           cation, this document describes the 8-bit versions  of  the  functions,
1183           with only occasional references to the 16-bit library.
1184    
1185           The  16-bit  functions  operate in the same way as their 8-bit counter-
1186           parts; they just use different  data  types  for  their  arguments  and
1187           results, and their names start with pcre16_ instead of pcre_. For every
1188           option that has UTF8 in its name (for example, PCRE_UTF8), there  is  a
1189           corresponding 16-bit name with UTF8 replaced by UTF16. This facility is
1190           in fact just cosmetic; the 16-bit option names define the same bit val-
1191           ues.
1192    
1193           References to bytes and UTF-8 in this document should be read as refer-
1194           ences to 16-bit data  quantities  and  UTF-16  when  using  the  16-bit
1195           library,  unless specified otherwise. More details of the specific dif-
1196           ferences for the 16-bit library are given in the pcre16 page.
1197    
1198    
1199  PCRE API OVERVIEW  PCRE API OVERVIEW
1200    
1201         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
1202         are also some wrapper functions that correspond to  the  POSIX  regular         are  also some wrapper functions (for the 8-bit library only) that cor-
1203         expression  API.  These  are  described in the pcreposix documentation.         respond to the POSIX regular expression  API,  but  they  do  not  give
1204         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
1205         distributed with PCRE. It is documented in the pcrecpp page.         documentation. Both of these APIs define a set of C function  calls.  A
1206           C++ wrapper (again for the 8-bit library only) is also distributed with
1207         The  native  API  C  function prototypes are defined in the header file         PCRE. It is documented in the pcrecpp page.
1208         pcre.h, and on Unix systems the library itself is called  libpcre.   It  
1209         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
1210         application  that  uses  PCRE.  The  header  file  defines  the  macros         pcre.h,  and  on Unix-like systems the (8-bit) library itself is called
1211         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
1212         bers for the library.  Applications can use these  to  include  support         for  linking an application that uses PCRE. The header file defines the
1213           macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release
1214           numbers  for the library. Applications can use these to include support
1215         for different releases of PCRE.         for different releases of PCRE.
1216    
1217         In a Windows environment, if you want to statically link an application         In a Windows environment, if you want to statically link an application
1218         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
1219         before  including  pcre.h or pcrecpp.h, because otherwise the pcre_mal-         before including pcre.h or pcrecpp.h, because otherwise  the  pcre_mal-
1220         loc()   and   pcre_free()   exported   functions   will   be   declared         loc()   and   pcre_free()   exported   functions   will   be   declared
1221         __declspec(dllimport), with unwanted results.         __declspec(dllimport), with unwanted results.
1222    
1223         The   functions   pcre_compile(),  pcre_compile2(),  pcre_study(),  and         The  functions  pcre_compile(),  pcre_compile2(),   pcre_study(),   and
1224         pcre_exec() are used for compiling and matching regular expressions  in         pcre_exec()  are used for compiling and matching regular expressions in
1225         a  Perl-compatible  manner. A sample program that demonstrates the sim-         a Perl-compatible manner. A sample program that demonstrates  the  sim-
1226         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
1227         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
1228         pcredemo documentation, and the pcresample documentation describes  how         pcredemo  documentation, and the pcresample documentation describes how
1229         to compile and run it.         to compile and run it.
1230    
1231           Just-in-time compiler support is an optional feature of PCRE  that  can
1232           be built in appropriate hardware environments. It greatly speeds up the
1233           matching performance of  many  patterns.  Simple  programs  can  easily
1234           request  that  it  be  used  if available, by setting an option that is
1235           ignored when it is not relevant. More complicated programs  might  need
1236           to     make    use    of    the    functions    pcre_jit_stack_alloc(),
1237           pcre_jit_stack_free(), and pcre_assign_jit_stack() in order to  control
1238           the  JIT  code's  memory  usage.   These functions are discussed in the
1239           pcrejit documentation.
1240    
1241         A second matching function, pcre_dfa_exec(), which is not Perl-compati-         A second matching function, pcre_dfa_exec(), which is not Perl-compati-
1242         ble, is also provided. This uses a different algorithm for  the  match-         ble,  is  also provided. This uses a different algorithm for the match-
1243         ing.  The  alternative algorithm finds all possible matches (at a given         ing. The alternative algorithm finds all possible matches (at  a  given
1244         point in the subject), and scans the subject just  once  (unless  there         point  in  the  subject), and scans the subject just once (unless there
1245         are  lookbehind  assertions).  However,  this algorithm does not return         are lookbehind assertions). However, this  algorithm  does  not  return
1246         captured substrings. A description of the two matching  algorithms  and         captured  substrings.  A description of the two matching algorithms and
1247         their  advantages  and disadvantages is given in the pcrematching docu-         their advantages and disadvantages is given in the  pcrematching  docu-
1248         mentation.         mentation.
1249    
1250         In addition to the main compiling and  matching  functions,  there  are         In  addition  to  the  main compiling and matching functions, there are
1251         convenience functions for extracting captured substrings from a subject         convenience functions for extracting captured substrings from a subject
1252         string that is matched by pcre_exec(). They are:         string that is matched by pcre_exec(). They are:
1253    
# Line 944  PCRE API OVERVIEW Line 1262  PCRE API OVERVIEW
1262         pcre_free_substring() and pcre_free_substring_list() are also provided,         pcre_free_substring() and pcre_free_substring_list() are also provided,
1263         to free the memory used for extracted strings.         to free the memory used for extracted strings.
1264    
1265         The  function  pcre_maketables()  is  used  to build a set of character         The function pcre_maketables() is used to  build  a  set  of  character
1266         tables  in  the  current  locale   for   passing   to   pcre_compile(),         tables   in   the   current   locale  for  passing  to  pcre_compile(),
1267         pcre_exec(),  or  pcre_dfa_exec(). This is an optional facility that is         pcre_exec(), or pcre_dfa_exec(). This is an optional facility  that  is
1268         provided for specialist use.  Most  commonly,  no  special  tables  are         provided  for  specialist  use.  Most  commonly,  no special tables are
1269         passed,  in  which case internal tables that are generated when PCRE is         passed, in which case internal tables that are generated when  PCRE  is
1270         built are used.         built are used.
1271    
1272         The function pcre_fullinfo() is used to find out  information  about  a         The  function  pcre_fullinfo()  is used to find out information about a
1273         compiled  pattern; pcre_info() is an obsolete version that returns only         compiled pattern. The function pcre_version() returns a  pointer  to  a
1274         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.  
1275    
1276         The function pcre_refcount() maintains a  reference  count  in  a  data         The  function  pcre_refcount()  maintains  a  reference count in a data
1277         block  containing  a compiled pattern. This is provided for the benefit         block containing a compiled pattern. This is provided for  the  benefit
1278         of object-oriented applications.         of object-oriented applications.
1279    
1280         The global variables pcre_malloc and pcre_free  initially  contain  the         The  global  variables  pcre_malloc and pcre_free initially contain the
1281         entry  points  of  the  standard malloc() and free() functions, respec-         entry points of the standard malloc()  and  free()  functions,  respec-
1282         tively. PCRE calls the memory management functions via these variables,         tively. PCRE calls the memory management functions via these variables,
1283         so  a  calling  program  can replace them if it wishes to intercept the         so a calling program can replace them if it  wishes  to  intercept  the
1284         calls. This should be done before calling any PCRE functions.         calls. This should be done before calling any PCRE functions.
1285    
1286         The global variables pcre_stack_malloc  and  pcre_stack_free  are  also         The  global  variables  pcre_stack_malloc  and pcre_stack_free are also
1287         indirections  to  memory  management functions. These special functions         indirections to memory management functions.  These  special  functions
1288         are used only when PCRE is compiled to use  the  heap  for  remembering         are  used  only  when  PCRE is compiled to use the heap for remembering
1289         data, instead of recursive function calls, when running the pcre_exec()         data, instead of recursive function calls, when running the pcre_exec()
1290         function. See the pcrebuild documentation for  details  of  how  to  do         function.  See  the  pcrebuild  documentation  for details of how to do
1291         this.  It  is  a non-standard way of building PCRE, for use in environ-         this. It is a non-standard way of building PCRE, for  use  in  environ-
1292         ments that have limited stacks. Because of the greater  use  of  memory         ments  that  have  limited stacks. Because of the greater use of memory
1293         management,  it  runs  more  slowly. Separate functions are provided so         management, it runs more slowly. Separate  functions  are  provided  so
1294         that special-purpose external code can be  used  for  this  case.  When         that  special-purpose  external  code  can  be used for this case. When
1295         used,  these  functions  are always called in a stack-like manner (last         used, these functions are always called in a  stack-like  manner  (last
1296         obtained, first freed), and always for memory blocks of the same  size.         obtained,  first freed), and always for memory blocks of the same size.
1297         There  is  a discussion about PCRE's stack usage in the pcrestack docu-         There is a discussion about PCRE's stack usage in the  pcrestack  docu-
1298         mentation.         mentation.
1299    
1300         The global variable pcre_callout initially contains NULL. It can be set         The global variable pcre_callout initially contains NULL. It can be set
1301         by  the  caller  to  a "callout" function, which PCRE will then call at         by the caller to a "callout" function, which PCRE  will  then  call  at
1302         specified points during a matching operation. Details are given in  the         specified  points during a matching operation. Details are given in the
1303         pcrecallout documentation.         pcrecallout documentation.
1304    
1305    
1306  NEWLINES  NEWLINES
1307    
1308         PCRE  supports five different conventions for indicating line breaks in         PCRE supports five different conventions for indicating line breaks  in
1309         strings: a single CR (carriage return) character, a  single  LF  (line-         strings:  a  single  CR (carriage return) character, a single LF (line-
1310         feed) character, the two-character sequence CRLF, any of the three pre-         feed) character, the two-character sequence CRLF, any of the three pre-
1311         ceding, or any Unicode newline sequence. The Unicode newline  sequences         ceding,  or any Unicode newline sequence. The Unicode newline sequences
1312         are  the  three just mentioned, plus the single characters VT (vertical         are the three just mentioned, plus the single characters  VT  (vertical
1313         tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS  (line         tab,  U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS (line
1314         separator, U+2028), and PS (paragraph separator, U+2029).         separator, U+2028), and PS (paragraph separator, U+2029).
1315    
1316         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
1317         system as its standard newline sequence. When PCRE is built, a  default         system  as its standard newline sequence. When PCRE is built, a default
1318         can  be  specified.  The default default is LF, which is the Unix stan-         can be specified.  The default default is LF, which is the  Unix  stan-
1319         dard. When PCRE is run, the default can be overridden,  either  when  a         dard.  When  PCRE  is run, the default can be overridden, either when a
1320         pattern is compiled, or when it is matched.         pattern is compiled, or when it is matched.
1321    
1322         At compile time, the newline convention can be specified by the options         At compile time, the newline convention can be specified by the options
1323         argument of pcre_compile(), or it can be specified by special  text  at         argument  of  pcre_compile(), or it can be specified by special text at
1324         the start of the pattern itself; this overrides any other settings. See         the start of the pattern itself; this overrides any other settings. See
1325         the pcrepattern page for details of the special character sequences.         the pcrepattern page for details of the special character sequences.
1326    
1327         In the PCRE documentation the word "newline" is used to mean "the char-         In the PCRE documentation the word "newline" is used to mean "the char-
1328         acter  or pair of characters that indicate a line break". The choice of         acter or pair of characters that indicate a line break". The choice  of
1329         newline convention affects the handling of  the  dot,  circumflex,  and         newline  convention  affects  the  handling of the dot, circumflex, and
1330         dollar metacharacters, the handling of #-comments in /x mode, and, when         dollar metacharacters, the handling of #-comments in /x mode, and, when
1331         CRLF is a recognized line ending sequence, the match position  advance-         CRLF  is a recognized line ending sequence, the match position advance-
1332         ment for a non-anchored pattern. There is more detail about this in the         ment for a non-anchored pattern. There is more detail about this in the
1333         section on pcre_exec() options below.         section on pcre_exec() options below.
1334    
1335         The choice of newline convention does not affect the interpretation  of         The  choice of newline convention does not affect the interpretation of
1336         the  \n  or  \r  escape  sequences, nor does it affect what \R matches,         the \n or \r escape sequences, nor does  it  affect  what  \R  matches,
1337         which is controlled in a similar way, but by separate options.         which is controlled in a similar way, but by separate options.
1338    
1339    
1340  MULTITHREADING  MULTITHREADING
1341    
1342         The PCRE functions can be used in  multi-threading  applications,  with         The  PCRE  functions  can be used in multi-threading applications, with
1343         the  proviso  that  the  memory  management  functions  pointed  to  by         the  proviso  that  the  memory  management  functions  pointed  to  by
1344         pcre_malloc, pcre_free, pcre_stack_malloc, and pcre_stack_free, and the         pcre_malloc, pcre_free, pcre_stack_malloc, and pcre_stack_free, and the
1345         callout function pointed to by pcre_callout, are shared by all threads.         callout function pointed to by pcre_callout, are shared by all threads.
1346    
1347         The  compiled form of a regular expression is not altered during match-         The compiled form of a regular expression is not altered during  match-
1348         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
1349         at once.         at once.
1350    
1351           If the just-in-time optimization feature is being used, it needs  sepa-
1352           rate  memory stack areas for each thread. See the pcrejit documentation
1353           for more details.
1354    
1355    
1356  SAVING PRECOMPILED PATTERNS FOR LATER USE  SAVING PRECOMPILED PATTERNS FOR LATER USE
1357    
1358         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
1359         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
1360         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
1361         pcreprecompile documentation. However, compiling a  regular  expression         pcreprecompile  documentation,  which  includes  a  description  of the
1362         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-
1363         anteed to work and may cause crashes.         lar  expression  with one version of PCRE for use with a different ver-
1364           sion is not guaranteed to work and may cause crashes.
1365    
1366    
1367  CHECKING BUILD-TIME OPTIONS  CHECKING BUILD-TIME OPTIONS
# Line 1054  CHECKING BUILD-TIME OPTIONS Line 1375  CHECKING BUILD-TIME OPTIONS
1375    
1376         The  first  argument  for pcre_config() is an integer, specifying which         The  first  argument  for pcre_config() is an integer, specifying which
1377         information is required; the second argument is a pointer to a variable         information is required; the second argument is a pointer to a variable
1378         into  which  the  information  is  placed. The following information is         into  which  the  information  is placed. The returned value is zero on
1379           success, or the negative error code PCRE_ERROR_BADOPTION if  the  value
1380           in  the  first argument is not recognized. The following information is
1381         available:         available:
1382    
1383           PCRE_CONFIG_UTF8           PCRE_CONFIG_UTF8
1384    
1385         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-
1386         able; otherwise it is set to zero.         able;  otherwise  it  is  set  to  zero. If this option is given to the
1387           16-bit  version  of  this  function,  pcre16_config(),  the  result  is
1388           PCRE_ERROR_BADOPTION.
1389    
1390             PCRE_CONFIG_UTF16
1391    
1392           The output is an integer that is set to one if UTF-16 support is avail-
1393           able; otherwise it is set to zero. This value should normally be  given
1394           to the 16-bit version of this function, pcre16_config(). If it is given
1395           to the 8-bit version of this function, the result is  PCRE_ERROR_BADOP-
1396           TION.
1397    
1398           PCRE_CONFIG_UNICODE_PROPERTIES           PCRE_CONFIG_UNICODE_PROPERTIES
1399    
1400         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
1401         character properties is available; otherwise it is set to zero.         character properties is available; otherwise it is set to zero.
1402    
1403             PCRE_CONFIG_JIT
1404    
1405           The output is an integer that is set to one if support for just-in-time
1406           compiling is available; otherwise it is set to zero.
1407    
1408             PCRE_CONFIG_JITTARGET
1409    
1410           The  output is a pointer to a zero-terminated "const char *" string. If
1411           JIT support is available, the string contains the name of the architec-
1412           ture  for  which the JIT compiler is configured, for example "x86 32bit
1413           (little endian + unaligned)". If JIT  support  is  not  available,  the
1414           result is NULL.
1415    
1416           PCRE_CONFIG_NEWLINE           PCRE_CONFIG_NEWLINE
1417    
1418         The output is an integer whose value specifies  the  default  character         The  output  is  an integer whose value specifies the default character
1419         sequence  that is recognized as meaning "newline". The four values that         sequence that is recognized as meaning "newline". The four values  that
1420         are supported are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF,         are supported are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF,
1421         and  -1  for  ANY.  Though they are derived from ASCII, the same values         and -1 for ANY.  Though they are derived from ASCII,  the  same  values
1422         are returned in EBCDIC environments. The default should normally corre-         are returned in EBCDIC environments. The default should normally corre-
1423         spond to the standard sequence for your operating system.         spond to the standard sequence for your operating system.
1424    
1425           PCRE_CONFIG_BSR           PCRE_CONFIG_BSR
1426    
1427         The output is an integer whose value indicates what character sequences         The output is an integer whose value indicates what character sequences
1428         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
1429         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
1430         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-
1431         tern is compiled or matched.         tern is compiled or matched.
1432    
1433           PCRE_CONFIG_LINK_SIZE           PCRE_CONFIG_LINK_SIZE
1434    
1435         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
1436         internal linkage in compiled regular expressions. The value is 2, 3, or         internal  linkage  in  compiled  regular  expressions.  For  the  8-bit
1437         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
1438         the expense of slower matching. The default value of  2  is  sufficient         is either 2 or 4 and is still a number of bytes. The default value of 2
1439         for  all  but  the  most massive patterns, since it allows the compiled         is sufficient for all but the most massive patterns,  since  it  allows
1440         pattern to be up to 64K in size.         the  compiled  pattern  to  be  up to 64K in size.  Larger values allow
1441           larger regular expressions to be compiled, at  the  expense  of  slower
1442           matching.
1443    
1444           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
1445    
1446         The output is an integer that contains the threshold  above  which  the         The  output  is  an integer that contains the threshold above which the
1447         POSIX  interface  uses malloc() for output vectors. Further details are         POSIX interface uses malloc() for output vectors. Further  details  are
1448         given in the pcreposix documentation.         given in the pcreposix documentation.
1449    
1450           PCRE_CONFIG_MATCH_LIMIT           PCRE_CONFIG_MATCH_LIMIT
1451    
1452         The output is a long integer that gives the default limit for the  num-         The  output is a long integer that gives the default limit for the num-
1453         ber  of  internal  matching  function calls in a pcre_exec() execution.         ber of internal matching function calls  in  a  pcre_exec()  execution.
1454         Further details are given with pcre_exec() below.         Further details are given with pcre_exec() below.
1455    
1456           PCRE_CONFIG_MATCH_LIMIT_RECURSION           PCRE_CONFIG_MATCH_LIMIT_RECURSION
1457    
1458         The output is a long integer that gives the default limit for the depth         The output is a long integer that gives the default limit for the depth
1459         of   recursion  when  calling  the  internal  matching  function  in  a         of  recursion  when  calling  the  internal  matching  function  in   a
1460         pcre_exec() execution.  Further  details  are  given  with  pcre_exec()         pcre_exec()  execution.  Further  details  are  given  with pcre_exec()
1461         below.         below.
1462    
1463           PCRE_CONFIG_STACKRECURSE           PCRE_CONFIG_STACKRECURSE
1464    
1465         The  output is an integer that is set to one if internal recursion when         The output is an integer that is set to one if internal recursion  when
1466         running pcre_exec() is implemented by recursive function calls that use         running pcre_exec() is implemented by recursive function calls that use
1467         the  stack  to remember their state. This is the usual way that PCRE is         the stack to remember their state. This is the usual way that  PCRE  is
1468         compiled. The output is zero if PCRE was compiled to use blocks of data         compiled. The output is zero if PCRE was compiled to use blocks of data
1469         on  the  heap  instead  of  recursive  function  calls.  In  this case,         on the  heap  instead  of  recursive  function  calls.  In  this  case,
1470         pcre_stack_malloc and  pcre_stack_free  are  called  to  manage  memory         pcre_stack_malloc  and  pcre_stack_free  are  called  to  manage memory
1471         blocks on the heap, thus avoiding the use of the stack.         blocks on the heap, thus avoiding the use of the stack.
1472    
1473    
# Line 1136  COMPILING A PATTERN Line 1484  COMPILING A PATTERN
1484    
1485         Either of the functions pcre_compile() or pcre_compile2() can be called         Either of the functions pcre_compile() or pcre_compile2() can be called
1486         to compile a pattern into an internal form. The only difference between         to compile a pattern into an internal form. The only difference between
1487         the  two interfaces is that pcre_compile2() has an additional argument,         the two interfaces is that pcre_compile2() has an additional  argument,
1488         errorcodeptr, via which a numerical error  code  can  be  returned.  To         errorcodeptr,  via  which  a  numerical  error code can be returned. To
1489         avoid  too  much repetition, we refer just to pcre_compile() below, but         avoid too much repetition, we refer just to pcre_compile()  below,  but
1490         the information applies equally to pcre_compile2().         the information applies equally to pcre_compile2().
1491    
1492         The pattern is a C string terminated by a binary zero, and is passed in         The pattern is a C string terminated by a binary zero, and is passed in
1493         the  pattern  argument.  A  pointer to a single block of memory that is         the pattern argument. A pointer to a single block  of  memory  that  is
1494         obtained via pcre_malloc is returned. This contains the  compiled  code         obtained  via  pcre_malloc is returned. This contains the compiled code
1495         and related data. The pcre type is defined for the returned block; this         and related data. The pcre type is defined for the returned block; this
1496         is a typedef for a structure whose contents are not externally defined.         is a typedef for a structure whose contents are not externally defined.
1497         It is up to the caller to free the memory (via pcre_free) when it is no         It is up to the caller to free the memory (via pcre_free) when it is no
1498         longer required.         longer required.
1499    
1500         Although the compiled code of a PCRE regex is relocatable, that is,  it         Although  the compiled code of a PCRE regex is relocatable, that is, it
1501         does not depend on memory location, the complete pcre data block is not         does not depend on memory location, the complete pcre data block is not
1502         fully relocatable, because it may contain a copy of the tableptr  argu-         fully  relocatable, because it may contain a copy of the tableptr argu-
1503         ment, which is an address (see below).         ment, which is an address (see below).
1504    
1505         The options argument contains various bit settings that affect the com-         The options argument contains various bit settings that affect the com-
1506         pilation. It should be zero if no options are required.  The  available         pilation.  It  should be zero if no options are required. The available
1507         options  are  described  below. Some of them (in particular, those that         options are described below. Some of them (in  particular,  those  that
1508         are compatible with Perl, but some others as well) can also be set  and         are  compatible with Perl, but some others as well) can also be set and
1509         unset  from  within  the  pattern  (see the detailed description in the         unset from within the pattern (see  the  detailed  description  in  the
1510         pcrepattern documentation). For those options that can be different  in         pcrepattern  documentation). For those options that can be different in
1511         different  parts  of  the pattern, the contents of the options argument         different parts of the pattern, the contents of  the  options  argument
1512         specifies their settings at the start of compilation and execution. The         specifies their settings at the start of compilation and execution. The
1513         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
1514         the time of matching as well as at compile time.         PCRE_NO_START_OPTIMIZE  options  can  be set at the time of matching as
1515           well as at compile time.
1516    
1517         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,
1518         if  compilation  of  a  pattern fails, pcre_compile() returns NULL, and         if  compilation  of  a  pattern fails, pcre_compile() returns NULL, and
1519         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-
1520         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
1521         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
1522         character  that  was  being  processed when the error was discovered is         the  byte  that  was  being  processed when the error was discovered is
1523         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
1524         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
1525         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.
1526         in this case the offset is set to the end of the pattern.  
1527           Some errors are not detected until the whole pattern has been  scanned;
1528           in  these  cases,  the offset passed back is the length of the pattern.
1529           Note that the offset is in bytes, not characters, even in  UTF-8  mode.
1530           It may sometimes point into the middle of a UTF-8 character.
1531    
1532         If  pcre_compile2()  is  used instead of pcre_compile(), and the error-         If  pcre_compile2()  is  used instead of pcre_compile(), and the error-
1533         codeptr argument is not NULL, a non-zero error code number is  returned         codeptr argument is not NULL, a non-zero error code number is  returned
# Line 1252  COMPILING A PATTERN Line 1605  COMPILING A PATTERN
1605    
1606           PCRE_DOTALL           PCRE_DOTALL
1607    
1608         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-
1609         acters,  including  those that indicate newline. Without it, a dot does         acter of any value, including one that indicates a newline. However, it
1610         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.
1611         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
1612         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
1613         newline characters, independent of the setting of this option.         be  changed within a pattern by a (?s) option setting. A negative class
1614           such as [^a] always matches newline characters, independent of the set-
1615           ting of this option.
1616    
1617           PCRE_DUPNAMES           PCRE_DUPNAMES
1618    
# Line 1277  COMPILING A PATTERN Line 1632  COMPILING A PATTERN
1632         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-
1633         ting.         ting.
1634    
1635         This  option  makes  it possible to include comments inside complicated         Which  characters  are  interpreted  as  newlines  is controlled by the
1636         patterns.  Note, however, that this applies only  to  data  characters.         options passed to pcre_compile() or by a special sequence at the  start
1637         Whitespace   characters  may  never  appear  within  special  character         of  the  pattern, as described in the section entitled "Newline conven-
1638         sequences in a pattern, for  example  within  the  sequence  (?(  which         tions" in the pcrepattern documentation. Note that the end of this type
1639         introduces a conditional subpattern.         of  comment  is  a  literal  newline  sequence  in  the pattern; escape
1640           sequences that happen to represent a newline do not count.
1641    
1642           This option makes it possible to include  comments  inside  complicated
1643           patterns.   Note,  however,  that this applies only to data characters.
1644           Whitespace  characters  may  never  appear  within  special   character
1645           sequences in a pattern, for example within the sequence (?( that intro-
1646           duces a conditional subpattern.
1647    
1648           PCRE_EXTRA           PCRE_EXTRA
1649    
1650         This  option  was invented in order to turn on additional functionality         This option was invented in order to turn on  additional  functionality
1651         of PCRE that is incompatible with Perl, but it  is  currently  of  very         of  PCRE  that  is  incompatible with Perl, but it is currently of very
1652         little  use. When set, any backslash in a pattern that is followed by a         little use. When set, any backslash in a pattern that is followed by  a
1653         letter that has no special meaning  causes  an  error,  thus  reserving         letter  that  has  no  special  meaning causes an error, thus reserving
1654         these  combinations  for  future  expansion.  By default, as in Perl, a         these combinations for future expansion. By  default,  as  in  Perl,  a
1655         backslash followed by a letter with no special meaning is treated as  a         backslash  followed by a letter with no special meaning is treated as a
1656         literal. (Perl can, however, be persuaded to give an error for this, by         literal. (Perl can, however, be persuaded to give an error for this, by
1657         running it with the -w option.) There are at present no other  features         running  it with the -w option.) There are at present no other features
1658         controlled  by this option. It can also be set by a (?X) option setting         controlled by this option. It can also be set by a (?X) option  setting
1659         within a pattern.         within a pattern.
1660    
1661           PCRE_FIRSTLINE           PCRE_FIRSTLINE
1662    
1663         If this option is set, an  unanchored  pattern  is  required  to  match         If  this  option  is  set,  an  unanchored pattern is required to match
1664         before  or  at  the  first  newline  in  the subject string, though the         before or at the first  newline  in  the  subject  string,  though  the
1665         matched text may continue over the newline.         matched text may continue over the newline.
1666    
1667           PCRE_JAVASCRIPT_COMPAT           PCRE_JAVASCRIPT_COMPAT
1668    
1669         If this option is set, PCRE's behaviour is changed in some ways so that         If this option is set, PCRE's behaviour is changed in some ways so that
1670         it  is  compatible with JavaScript rather than Perl. The changes are as         it is compatible with JavaScript rather than Perl. The changes  are  as
1671         follows:         follows:
1672    
1673         (1) A lone closing square bracket in a pattern  causes  a  compile-time         (1)  A  lone  closing square bracket in a pattern causes a compile-time
1674         error,  because this is illegal in JavaScript (by default it is treated         error, because this is illegal in JavaScript (by default it is  treated
1675         as a data character). Thus, the pattern AB]CD becomes illegal when this         as a data character). Thus, the pattern AB]CD becomes illegal when this
1676         option is set.         option is set.
1677    
1678         (2)  At run time, a back reference to an unset subpattern group matches         (2) At run time, a back reference to an unset subpattern group  matches
1679         an empty string (by default this causes the current  matching  alterna-         an  empty  string (by default this causes the current matching alterna-
1680         tive  to  fail). A pattern such as (\1)(a) succeeds when this option is         tive to fail). A pattern such as (\1)(a) succeeds when this  option  is
1681         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
1682         default, for Perl compatibility.         default, for Perl compatibility.
1683    
1684           (3) \U matches an upper case "U" character; by default \U causes a com-
1685           pile time error (Perl uses \U to upper case subsequent characters).
1686    
1687           (4) \u matches a lower case "u" character unless it is followed by four
1688           hexadecimal digits, in which case the hexadecimal  number  defines  the
1689           code  point  to match. By default, \u causes a compile time error (Perl
1690           uses it to upper case the following character).
1691    
1692           (5) \x matches a lower case "x" character unless it is followed by  two
1693           hexadecimal  digits,  in  which case the hexadecimal number defines the
1694           code point to match. By default, as in Perl, a  hexadecimal  number  is
1695           always expected after \x, but it may have zero, one, or two digits (so,
1696           for example, \xz matches a binary zero character followed by z).
1697    
1698           PCRE_MULTILINE           PCRE_MULTILINE
1699    
1700         By  default,  PCRE  treats the subject string as consisting of a single         By default, PCRE treats the subject string as consisting  of  a  single
1701         line of characters (even if it actually contains newlines). The  "start         line  of characters (even if it actually contains newlines). The "start
1702         of  line"  metacharacter  (^)  matches only at the start of the string,         of line" metacharacter (^) matches only at the  start  of  the  string,
1703         while the "end of line" metacharacter ($) matches only at  the  end  of         while  the  "end  of line" metacharacter ($) matches only at the end of
1704         the string, or before a terminating newline (unless PCRE_DOLLAR_ENDONLY         the string, or before a terminating newline (unless PCRE_DOLLAR_ENDONLY
1705         is set). This is the same as Perl.         is set). This is the same as Perl.
1706    
1707         When PCRE_MULTILINE it is set, the "start of line" and  "end  of  line"         When  PCRE_MULTILINE  it  is set, the "start of line" and "end of line"
1708         constructs  match  immediately following or immediately before internal         constructs match immediately following or immediately  before  internal
1709         newlines in the subject string, respectively, as well as  at  the  very         newlines  in  the  subject string, respectively, as well as at the very
1710         start  and  end.  This is equivalent to Perl's /m option, and it can be         start and end. This is equivalent to Perl's /m option, and  it  can  be
1711         changed within a pattern by a (?m) option setting. If there are no new-         changed within a pattern by a (?m) option setting. If there are no new-
1712         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,
1713         setting PCRE_MULTILINE has no effect.         setting PCRE_MULTILINE has no effect.
1714    
1715           PCRE_NEWLINE_CR           PCRE_NEWLINE_CR
# Line 1342  COMPILING A PATTERN Line 1718  COMPILING A PATTERN
1718           PCRE_NEWLINE_ANYCRLF           PCRE_NEWLINE_ANYCRLF
1719           PCRE_NEWLINE_ANY           PCRE_NEWLINE_ANY
1720    
1721         These options override the default newline definition that  was  chosen         These  options  override the default newline definition that was chosen
1722         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
1723         newline is indicated by a single character (CR  or  LF,  respectively).         newline  is  indicated  by a single character (CR or LF, respectively).
1724         Setting  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the         Setting PCRE_NEWLINE_CRLF specifies that a newline is indicated by  the
1725         two-character CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF  specifies         two-character  CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF specifies
1726         that any of the three preceding sequences should be recognized. Setting         that any of the three preceding sequences should be recognized. Setting
1727         PCRE_NEWLINE_ANY specifies that any Unicode newline sequence should  be         PCRE_NEWLINE_ANY  specifies that any Unicode newline sequence should be
1728         recognized. The Unicode newline sequences are the three just mentioned,         recognized. The Unicode newline sequences are the three just mentioned,
1729         plus the single characters VT (vertical  tab,  U+000B),  FF  (formfeed,         plus  the  single  characters  VT (vertical tab, U+000B), FF (formfeed,
1730         U+000C),  NEL  (next line, U+0085), LS (line separator, U+2028), and PS         U+000C), NEL (next line, U+0085), LS (line separator, U+2028),  and  PS
1731         (paragraph separator, U+2029). The last  two  are  recognized  only  in         (paragraph  separator, U+2029). For the 8-bit library, the last two are
1732         UTF-8 mode.         recognized only in UTF-8 mode.
1733    
1734         The  newline  setting  in  the  options  word  uses three bits that are         The newline setting in the  options  word  uses  three  bits  that  are
1735         treated as a number, giving eight possibilities. Currently only six are         treated as a number, giving eight possibilities. Currently only six are
1736         used  (default  plus the five values above). This means that if you set         used (default plus the five values above). This means that if  you  set
1737         more than one newline option, the combination may or may not be  sensi-         more  than one newline option, the combination may or may not be sensi-
1738         ble. For example, PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to         ble. For example, PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to
1739         PCRE_NEWLINE_CRLF, but other combinations may yield unused numbers  and         PCRE_NEWLINE_CRLF,  but other combinations may yield unused numbers and
1740         cause an error.         cause an error.
1741    
1742         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
1743         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 whitespace
1744         character  class  is  encountered.  This indicates a comment that lasts         characters, and so are ignored in this mode. Also, an unescaped #  out-
1745         until after the next line break sequence. In other circumstances,  line         side  a  character class indicates a comment that lasts until after the
1746         break   sequences   are   treated  as  literal  data,  except  that  in         next line break sequence. In other circumstances, line break  sequences
1747         PCRE_EXTENDED mode, both CR and LF are treated as whitespace characters         in patterns are treated as literal data.
        and are therefore ignored.  
1748    
1749         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
1750         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 1382  COMPILING A PATTERN Line 1757  COMPILING A PATTERN
1757         be  used  for  capturing  (and  they acquire numbers in the usual way).         be  used  for  capturing  (and  they acquire numbers in the usual way).
1758         There is no equivalent of this option in Perl.         There is no equivalent of this option in Perl.
1759    
1760             NO_START_OPTIMIZE
1761    
1762           This is an option that acts at matching time; that is, it is really  an
1763           option  for  pcre_exec()  or  pcre_dfa_exec().  If it is set at compile
1764           time, it is remembered with the compiled pattern and assumed at  match-
1765           ing  time.  For  details  see  the discussion of PCRE_NO_START_OPTIMIZE
1766           below.
1767    
1768           PCRE_UCP           PCRE_UCP
1769    
1770         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,
1771         the POSIX character classes. By default, only ASCII characters are rec-         \w,  and  some  of  the POSIX character classes. By default, only ASCII
1772         ognized, but if PCRE_UCP is set, Unicode properties are used instead to         characters are recognized, but if PCRE_UCP is set,  Unicode  properties
1773         classify  characters.  More details are given in the section on generic         are  used instead to classify characters. More details are given in the
1774         character types in the pcrepattern page. If you set PCRE_UCP,  matching         section on generic character types in the pcrepattern page. If you  set
1775         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
1776         only if PCRE has been compiled with Unicode property support.         option is available only if PCRE has been compiled with  Unicode  prop-
1777           erty support.
1778    
1779           PCRE_UNGREEDY           PCRE_UNGREEDY
1780    
1781         This option inverts the "greediness" of the quantifiers  so  that  they         This  option  inverts  the "greediness" of the quantifiers so that they
1782         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
1783         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
1784         within the pattern.         within the pattern.
1785    
1786           PCRE_UTF8           PCRE_UTF8
1787    
1788         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
1789         strings of UTF-8 characters instead of single-byte  character  strings.         strings of UTF-8 characters instead of single-byte strings. However, it
1790         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,
1791         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
1792         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.  
1793    
1794           PCRE_NO_UTF8_CHECK           PCRE_NO_UTF8_CHECK
1795    
1796         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
1797         automatically  checked.  There  is  a  discussion about the validity of         automatically  checked.  There  is  a  discussion about the validity of
1798         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
1799         bytes  is  found,  pcre_compile() returns an error. If you already know         found,  pcre_compile()  returns an error. If you already know that your
1800         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-
1801         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
1802         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
1803         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
1804         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
1805         UTF-8 validity checking of subject strings.         checking of subject strings.
1806    
1807    
1808  COMPILATION ERROR CODES  COMPILATION ERROR CODES
1809    
1810         The  following  table  lists  the  error  codes than may be returned by         The  following  table  lists  the  error  codes than may be returned by
1811         pcre_compile2(), along with the error messages that may be returned  by         pcre_compile2(), along with the error messages that may be returned  by
1812         both  compiling functions. As PCRE has developed, some error codes have         both  compiling  functions.  Note  that error messages are always 8-bit
1813         fallen out of use. To avoid confusion, they have not been re-used.         ASCII strings, even in 16-bit mode. As PCRE has developed,  some  error
1814           codes  have  fallen  out of use. To avoid confusion, they have not been
1815           re-used.
1816    
1817            0  no error            0  no error
1818            1  \ at end of pattern            1  \ at end of pattern
# Line 1461  COMPILATION ERROR CODES Line 1846  COMPILATION ERROR CODES
1846           29  (?R or (?[+-]digits must be followed by )           29  (?R or (?[+-]digits must be followed by )
1847           30  unknown POSIX class name           30  unknown POSIX class name
1848           31  POSIX collating elements are not supported           31  POSIX collating elements are not supported
1849           32  this version of PCRE is not compiled with PCRE_UTF8 support           32  this version of PCRE is compiled without UTF support
1850           33  [this code is not in use]           33  [this code is not in use]
1851           34  character value in \x{...} sequence is too large           34  character value in \x{...} sequence is too large
1852           35  invalid condition (?(0)           35  invalid condition (?(0)
1853           36  \C not allowed in lookbehind assertion           36  \C not allowed in lookbehind assertion
1854           37  PCRE does not support \L, \l, \N, \U, or \u           37  PCRE does not support \L, \l, \N{name}, \U, or \u
1855           38  number after (?C is > 255           38  number after (?C is > 255
1856           39  closing ) for (?C expected           39  closing ) for (?C expected
1857           40  recursive call could loop indefinitely           40  recursive call could loop indefinitely
1858           41  unrecognized character after (?P           41  unrecognized character after (?P
1859           42  syntax error in subpattern name (missing terminator)           42  syntax error in subpattern name (missing terminator)
1860           43  two named subpatterns have the same name           43  two named subpatterns have the same name
1861           44  invalid UTF-8 string           44  invalid UTF-8 string (specifically UTF-8)
1862           45  support for \P, \p, and \X has not been compiled           45  support for \P, \p, and \X has not been compiled
1863           46  malformed \P or \p sequence           46  malformed \P or \p sequence
1864           47  unknown property name after \P or \p           47  unknown property name after \P or \p
1865           48  subpattern name is too long (maximum 32 characters)           48  subpattern name is too long (maximum 32 characters)
1866           49  too many named subpatterns (maximum 10000)           49  too many named subpatterns (maximum 10000)
1867           50  [this code is not in use]           50  [this code is not in use]
1868           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
1869           52  internal error: overran compiling workspace           52  internal error: overran compiling workspace
1870           53  internal error: previously-checked referenced subpattern           53  internal error: previously-checked referenced subpattern
1871                 not found                 not found
# Line 1499  COMPILATION ERROR CODES Line 1884  COMPILATION ERROR CODES
1884           65  different names for subpatterns of the same number are           65  different names for subpatterns of the same number are
1885                 not allowed                 not allowed
1886           66  (*MARK) must have an argument           66  (*MARK) must have an argument
1887           67  this version of PCRE is not compiled with PCRE_UCP support           67  this version of PCRE is not compiled with Unicode property
1888                   support
1889             68  \c must be followed by an ASCII character
1890             69  \k is not followed by a braced, angle-bracketed, or quoted name
1891             70  internal error: unknown opcode in find_fixedlength()
1892             71  \N is not supported in a class
1893             72  too many forward references
1894             73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
1895             74  invalid UTF-16 string (specifically UTF-16)
1896    
1897         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
1898         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 1528  STUDYING A PATTERN Line 1921  STUDYING A PATTERN
1921         wants  to  pass  any  of   the   other   fields   to   pcre_exec()   or         wants  to  pass  any  of   the   other   fields   to   pcre_exec()   or
1922         pcre_dfa_exec(), it must set up its own pcre_extra block.         pcre_dfa_exec(), it must set up its own pcre_extra block.
1923    
1924         The  second  argument of pcre_study() contains option bits. At present,         The  second  argument  of  pcre_study() contains option bits. There are
1925         no options are defined, and this argument should always be zero.         three options:
1926    
1927             PCRE_STUDY_JIT_COMPILE
1928             PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
1929             PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
1930    
1931           If any of these are set, and the just-in-time  compiler  is  available,
1932           the  pattern  is  further compiled into machine code that executes much
1933           faster than the pcre_exec()  interpretive  matching  function.  If  the
1934           just-in-time  compiler is not available, these options are ignored. All
1935           other bits in the options argument must be zero.
1936    
1937           JIT compilation is a heavyweight optimization. It can  take  some  time
1938           for  patterns  to  be analyzed, and for one-off matches and simple pat-
1939           terns the benefit of faster execution might be offset by a much  slower
1940           study time.  Not all patterns can be optimized by the JIT compiler. For
1941           those that cannot be handled, matching automatically falls back to  the
1942           pcre_exec()  interpreter.  For more details, see the pcrejit documenta-
1943           tion.
1944    
1945         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.
1946         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 1949  STUDYING A PATTERN
1949         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
1950         after calling pcre_study(), to be sure that it has run successfully.         after calling pcre_study(), to be sure that it has run successfully.
1951    
1952         This is a typical call to pcre_study():         When  you are finished with a pattern, you can free the memory used for
1953           the study data by calling pcre_free_study(). This function was added to
1954           the  API  for  release  8.20. For earlier versions, the memory could be
1955           freed with pcre_free(), just like the pattern itself. This  will  still
1956           work  in  cases where JIT optimization is not used, but it is advisable
1957           to change to the new function when convenient.
1958    
1959           pcre_extra *pe;         This is a typical way in which pcre_study() is used (except that  in  a
1960           pe = pcre_study(         real application there should be tests for errors):
1961    
1962             int rc;
1963             pcre *re;
1964             pcre_extra *sd;
1965             re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
1966             sd = pcre_study(
1967             re,             /* result of pcre_compile() */             re,             /* result of pcre_compile() */
1968             0,              /* no options exist */             0,              /* no options */
1969             &error);        /* set to NULL or points to a message */             &error);        /* set to NULL or points to a message */
1970             rc = pcre_exec(   /* see below for details of pcre_exec() options */
1971               re, sd, "subject", 7, 0, 0, ovector, 30);
1972             ...
1973             pcre_free_study(sd);
1974             pcre_free(re);
1975    
1976         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
1977         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
# Line 1557  STUDYING A PATTERN Line 1984  STUDYING A PATTERN
1984         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
1985         have a single fixed starting character. A bitmap of  possible  starting         have a single fixed starting character. A bitmap of  possible  starting
1986         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
1987         which to start matching.         which to start matching. (In 16-bit mode, the bitmap is used for 16-bit
1988           values less than 256.)
1989    
1990         The two optimizations just described can be  disabled  by  setting  the         These  two optimizations apply to both pcre_exec() and pcre_dfa_exec(),
1991         PCRE_NO_START_OPTIMIZE    option    when    calling    pcre_exec()   or         and the information is also used by the JIT  compiler.   The  optimiza-
1992         pcre_dfa_exec(). You might want to do this  if  your  pattern  contains         tions can be disabled by setting the PCRE_NO_START_OPTIMIZE option when
1993         callouts,  or  make  use of (*MARK), and you make use of these in cases         calling pcre_exec() or pcre_dfa_exec(), but if this is done, JIT execu-
1994         where matching fails.  See  the  discussion  of  PCRE_NO_START_OPTIMIZE         tion  is  also disabled. You might want to do this if your pattern con-
1995         below.         tains callouts or (*MARK) and you want to make use of these  facilities
1996           in    cases    where    matching   fails.   See   the   discussion   of
1997           PCRE_NO_START_OPTIMIZE below.
1998    
1999    
2000  LOCALE SUPPORT  LOCALE SUPPORT
2001    
2002         PCRE  handles  caseless matching, and determines whether characters are         PCRE handles caseless matching, and determines whether  characters  are
2003         letters, digits, or whatever, by reference to a set of tables,  indexed         letters,  digits, or whatever, by reference to a set of tables, indexed
2004         by  character  value.  When running in UTF-8 mode, this applies only to         by character value. When running in UTF-8 mode, this  applies  only  to
2005         characters with codes less than 128. By  default,  higher-valued  codes         characters  with  codes  less than 128. By default, higher-valued codes
2006         never match escapes such as \w or \d, but they can be tested with \p if         never match escapes such as \w or \d, but they can be tested with \p if
2007         PCRE is built with Unicode character property  support.  Alternatively,         PCRE  is  built with Unicode character property support. Alternatively,
2008         the  PCRE_UCP  option  can  be  set at compile time; this causes \w and         the PCRE_UCP option can be set at compile  time;  this  causes  \w  and
2009         friends to use Unicode property support instead of built-in tables. The         friends to use Unicode property support instead of built-in tables. The
2010         use of locales with Unicode is discouraged. If you are handling charac-         use of locales with Unicode is discouraged. If you are handling charac-
2011         ters with codes greater than 128, you should either use UTF-8 and  Uni-         ters  with codes greater than 128, you should either use UTF-8 and Uni-
2012         code, or use locales, but not try to mix the two.         code, or use locales, but not try to mix the two.
2013    
2014         PCRE  contains  an  internal set of tables that are used when the final         PCRE contains an internal set of tables that are used  when  the  final
2015         argument of pcre_compile() is  NULL.  These  are  sufficient  for  many         argument  of  pcre_compile()  is  NULL.  These  are sufficient for many
2016         applications.  Normally, the internal tables recognize only ASCII char-         applications.  Normally, the internal tables recognize only ASCII char-
2017         acters. However, when PCRE is built, it is possible to cause the inter-         acters. However, when PCRE is built, it is possible to cause the inter-
2018         nal tables to be rebuilt in the default "C" locale of the local system,         nal tables to be rebuilt in the default "C" locale of the local system,
2019         which may cause them to be different.         which may cause them to be different.
2020    
2021         The internal tables can always be overridden by tables supplied by  the         The  internal tables can always be overridden by tables supplied by the
2022         application that calls PCRE. These may be created in a different locale         application that calls PCRE. These may be created in a different locale
2023         from the default. As more and more applications change  to  using  Uni-         from  the  default.  As more and more applications change to using Uni-
2024         code, the need for this locale support is expected to die away.         code, the need for this locale support is expected to die away.
2025    
2026         External  tables  are  built by calling the pcre_maketables() function,         External tables are built by calling  the  pcre_maketables()  function,
2027         which has no arguments, in the relevant locale. The result can then  be         which  has no arguments, in the relevant locale. The result can then be
2028         passed  to  pcre_compile()  or  pcre_exec()  as often as necessary. For         passed to pcre_compile() or pcre_exec()  as  often  as  necessary.  For
2029         example, to build and use tables that are appropriate  for  the  French         example,  to  build  and use tables that are appropriate for the French
2030         locale  (where  accented  characters  with  values greater than 128 are         locale (where accented characters with  values  greater  than  128  are
2031         treated as letters), the following code could be used:         treated as letters), the following code could be used:
2032    
2033           setlocale(LC_CTYPE, "fr_FR");           setlocale(LC_CTYPE, "fr_FR");
2034           tables = pcre_maketables();           tables = pcre_maketables();
2035           re = pcre_compile(..., tables);           re = pcre_compile(..., tables);
2036    
2037         The locale name "fr_FR" is used on Linux and other  Unix-like  systems;         The  locale  name "fr_FR" is used on Linux and other Unix-like systems;
2038         if you are using Windows, the name for the French locale is "french".         if you are using Windows, the name for the French locale is "french".
2039    
2040         When  pcre_maketables()  runs,  the  tables are built in memory that is         When pcre_maketables() runs, the tables are built  in  memory  that  is
2041         obtained via pcre_malloc. It is the caller's responsibility  to  ensure         obtained  via  pcre_malloc. It is the caller's responsibility to ensure
2042         that  the memory containing the tables remains available for as long as         that the memory containing the tables remains available for as long  as
2043         it is needed.         it is needed.
2044    
2045         The pointer that is passed to pcre_compile() is saved with the compiled         The pointer that is passed to pcre_compile() is saved with the compiled
2046         pattern,  and the same tables are used via this pointer by pcre_study()         pattern, and the same tables are used via this pointer by  pcre_study()
2047         and normally also by pcre_exec(). Thus, by default, for any single pat-         and normally also by pcre_exec(). Thus, by default, for any single pat-
2048         tern, compilation, studying and matching all happen in the same locale,         tern, compilation, studying and matching all happen in the same locale,
2049         but different patterns can be compiled in different locales.         but different patterns can be compiled in different locales.
2050    
2051         It is possible to pass a table pointer or NULL (indicating the  use  of         It  is  possible to pass a table pointer or NULL (indicating the use of
2052         the  internal  tables)  to  pcre_exec(). Although not intended for this         the internal tables) to pcre_exec(). Although  not  intended  for  this
2053         purpose, this facility could be used to match a pattern in a  different         purpose,  this facility could be used to match a pattern in a different
2054         locale from the one in which it was compiled. Passing table pointers at         locale from the one in which it was compiled. Passing table pointers at
2055         run time is discussed below in the section on matching a pattern.         run time is discussed below in the section on matching a pattern.
2056    
# Line 1630  INFORMATION ABOUT A PATTERN Line 2060  INFORMATION ABOUT A PATTERN
2060         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
2061              int what, void *where);              int what, void *where);
2062    
2063         The pcre_fullinfo() function returns information about a compiled  pat-         The  pcre_fullinfo() function returns information about a compiled pat-
2064         tern. It replaces the obsolete pcre_info() function, which is neverthe-         tern. It replaces the pcre_info() function, which was removed from  the
2065         less retained for backwards compability (and is documented below).         library at version 8.30, after more than 10 years of obsolescence.
2066    
2067         The first argument for pcre_fullinfo() is a  pointer  to  the  compiled         The  first  argument  for  pcre_fullinfo() is a pointer to the compiled
2068         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
2069         the pattern was not studied. The third argument specifies  which  piece         the  pattern  was not studied. The third argument specifies which piece
2070         of  information  is required, and the fourth argument is a pointer to a         of information is required, and the fourth argument is a pointer  to  a
2071         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
2072         success, or one of the following negative numbers:         success, or one of the following negative numbers:
2073    
2074           PCRE_ERROR_NULL       the argument code was NULL           PCRE_ERROR_NULL           the argument code was NULL
2075                                 the argument where was NULL                                     the argument where was NULL
2076           PCRE_ERROR_BADMAGIC   the "magic number" was not found           PCRE_ERROR_BADMAGIC       the "magic number" was not found
2077           PCRE_ERROR_BADOPTION  the value of what was invalid           PCRE_ERROR_BADENDIANNESS  the pattern was compiled with different
2078                                       endianness
2079         The  "magic  number" is placed at the start of each compiled pattern as           PCRE_ERROR_BADOPTION      the value of what was invalid
2080         an simple check against passing an arbitrary memory pointer. Here is  a  
2081         typical  call  of pcre_fullinfo(), to obtain the length of the compiled         The "magic number" is placed at the start of each compiled  pattern  as
2082         pattern:         an  simple check against passing an arbitrary memory pointer. The endi-
2083           anness error can occur if a compiled pattern is saved and reloaded on a
2084           different  host.  Here  is a typical call of pcre_fullinfo(), to obtain
2085           the length of the compiled pattern:
2086    
2087           int rc;           int rc;
2088           size_t length;           size_t length;
2089           rc = pcre_fullinfo(           rc = pcre_fullinfo(
2090             re,               /* result of pcre_compile() */             re,               /* result of pcre_compile() */
2091             pe,               /* result of pcre_study(), or NULL */             sd,               /* result of pcre_study(), or NULL */
2092             PCRE_INFO_SIZE,   /* what is required */             PCRE_INFO_SIZE,   /* what is required */
2093             &length);         /* where to put the data */             &length);         /* where to put the data */
2094    
# Line 1683  INFORMATION ABOUT A PATTERN Line 2116  INFORMATION ABOUT A PATTERN
2116    
2117           PCRE_INFO_FIRSTBYTE           PCRE_INFO_FIRSTBYTE
2118    
2119         Return information about the first byte of any matched  string,  for  a         Return information about the first data unit of any matched string, for
2120         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
2121         able. (This option used to be called PCRE_INFO_FIRSTCHAR; the old  name         library, where data units are bytes.) The fourth argument should  point
2122         is still recognized for backwards compatibility.)         to an int variable.
2123    
2124           If  there  is  a  fixed first value, for example, the letter "c" from a
2125           pattern such as (cat|cow|coyote), its value is returned. In  the  8-bit
2126           library,  the  value is always less than 256; in the 16-bit library the
2127           value can be up to 0xffff.
2128    
2129         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  
2130    
2131         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
2132         branch starts with "^", or         branch starts with "^", or
# Line 1704  INFORMATION ABOUT A PATTERN Line 2141  INFORMATION ABOUT A PATTERN
2141           PCRE_INFO_FIRSTTABLE           PCRE_INFO_FIRSTTABLE
2142    
2143         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
2144         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
2145         matching string, a pointer to the table is returned. Otherwise NULL  is         in any matching string, a pointer to the table is  returned.  Otherwise
2146         returned.  The fourth argument should point to an unsigned char * vari-         NULL  is returned. The fourth argument should point to an unsigned char
2147         able.         * variable.
2148    
2149           PCRE_INFO_HASCRORLF           PCRE_INFO_HASCRORLF
2150    
# Line 1722  INFORMATION ABOUT A PATTERN Line 2159  INFORMATION ABOUT A PATTERN
2159         otherwise 0. The fourth argument should point to an int variable.  (?J)         otherwise 0. The fourth argument should point to an int variable.  (?J)
2160         and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.         and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
2161    
2162             PCRE_INFO_JIT
2163    
2164           Return  1  if  the pattern was studied with one of the JIT options, and
2165           just-in-time compiling was successful. The fourth argument should point
2166           to  an  int variable. A return value of 0 means that JIT support is not
2167           available in this version of PCRE, or that the pattern was not  studied
2168           with  a JIT option, or that the JIT compiler could not handle this par-
2169           ticular pattern. See the pcrejit documentation for details of what  can
2170           and cannot be handled.
2171    
2172             PCRE_INFO_JITSIZE
2173    
2174           If  the  pattern was successfully studied with a JIT option, return the
2175           size of the JIT compiled code, otherwise return zero. The fourth  argu-
2176           ment should point to a size_t variable.
2177    
2178           PCRE_INFO_LASTLITERAL           PCRE_INFO_LASTLITERAL
2179    
2180         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
2181         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
2182         recorded. The fourth argument should point to an int variable. If there         recorded. The fourth argument should point to an int variable. If there
2183         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
2184         byte  is  recorded only if it follows something of variable length. For         value  is recorded only if it follows something of variable length. For
2185         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
2186         /^a\dz\d/ the returned value is -1.         /^a\dz\d/ the returned value is -1.
2187    
# Line 1736  INFORMATION ABOUT A PATTERN Line 2189  INFORMATION ABOUT A PATTERN
2189    
2190         If  the  pattern  was studied and a minimum length for matching subject         If  the  pattern  was studied and a minimum length for matching subject
2191         strings was computed, its value is  returned.  Otherwise  the  returned         strings was computed, its value is  returned.  Otherwise  the  returned
2192         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
2193         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
2194         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
2195         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
2196         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
2197           least that long.
2198    
2199           PCRE_INFO_NAMECOUNT           PCRE_INFO_NAMECOUNT
2200           PCRE_INFO_NAMEENTRYSIZE           PCRE_INFO_NAMEENTRYSIZE
2201           PCRE_INFO_NAMETABLE           PCRE_INFO_NAMETABLE
2202    
2203         PCRE  supports the use of named as well as numbered capturing parenthe-         PCRE supports the use of named as well as numbered capturing  parenthe-
2204         ses. The names are just an additional way of identifying the  parenthe-         ses.  The names are just an additional way of identifying the parenthe-
2205         ses, which still acquire numbers. Several convenience functions such as         ses, which still acquire numbers. Several convenience functions such as
2206         pcre_get_named_substring() are provided for  extracting  captured  sub-         pcre_get_named_substring()  are  provided  for extracting captured sub-
2207         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
2208         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
2209         pointers in the output vector (described with pcre_exec() below). To do         pointers in the output vector (described with pcre_exec() below). To do
2210         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
2211         described by these three values.         described by these three values.
2212    
2213         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
2214         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size
2215         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
2216         depends on the length of the longest name. PCRE_INFO_NAMETABLE  returns         depends  on the length of the longest name. PCRE_INFO_NAMETABLE returns
2217         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
2218         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-
2219         sis,  most  significant byte first. The rest of the entry is the corre-         ber of the capturing parenthesis, most significant byte first.  In  the
2220         sponding name, zero terminated.         16-bit  library,  the pointer points to 16-bit data units, the first of
2221           which contains the parenthesis number. The rest of  the  entry  is  the
2222           corresponding name, zero terminated.
2223    
2224         The names are in alphabetical order. Duplicate names may appear if  (?|         The  names are in alphabetical order. Duplicate names may appear if (?|
2225         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
2226         the section on duplicate subpattern numbers in  the  pcrepattern  page.         the  section  on  duplicate subpattern numbers in the pcrepattern page.
2227         Duplicate  names  for  subpatterns with different numbers are permitted         Duplicate names for subpatterns with different  numbers  are  permitted
2228         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
2229         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-
2230         tern. In the absence of (?| this is the  order  of  increasing  number;         tern.  In  the  absence  of (?| this is the order of increasing number;
2231         when (?| is used this is not necessarily the case because later subpat-         when (?| is used this is not necessarily the case because later subpat-
2232         terns may have lower numbers.         terns may have lower numbers.
2233    
2234         As a simple example of the name/number table,  consider  the  following         As  a  simple  example of the name/number table, consider the following
2235         pattern  (assume  PCRE_EXTENDED is set, so white space - including new-         pattern after compilation by the 8-bit library (assume PCRE_EXTENDED is
2236         lines - is ignored):         set, so white space - including newlines - is ignored):
2237    
2238           (?<date> (?<year>(\d\d)?\d\d) -           (?<date> (?<year>(\d\d)?\d\d) -
2239           (?<month>\d\d) - (?<day>\d\d) )           (?<month>\d\d) - (?<day>\d\d) )
2240    
2241         There are four named subpatterns, so the table has  four  entries,  and         There  are  four  named subpatterns, so the table has four entries, and
2242         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,
2243         with non-printing bytes shows in hexadecimal, and undefined bytes shown         with non-printing bytes shows in hexadecimal, and undefined bytes shown
2244         as ??:         as ??:
2245    
# Line 1792  INFORMATION ABOUT A PATTERN Line 2248  INFORMATION ABOUT A PATTERN
2248           00 04 m  o  n  t  h  00           00 04 m  o  n  t  h  00
2249           00 02 y  e  a  r  00 ??           00 02 y  e  a  r  00 ??
2250    
2251         When  writing  code  to  extract  data from named subpatterns using the         When writing code to extract data  from  named  subpatterns  using  the
2252         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
2253         to be different for each compiled pattern.         to be different for each compiled pattern.
2254    
2255           PCRE_INFO_OKPARTIAL           PCRE_INFO_OKPARTIAL
2256    
2257         Return  1  if  the  pattern  can  be  used  for  partial  matching with         Return 1  if  the  pattern  can  be  used  for  partial  matching  with
2258         pcre_exec(), otherwise 0. The fourth argument should point  to  an  int         pcre_exec(),  otherwise  0.  The fourth argument should point to an int
2259         variable.  From  release  8.00,  this  always  returns  1,  because the         variable. From  release  8.00,  this  always  returns  1,  because  the
2260         restrictions that previously applied  to  partial  matching  have  been         restrictions  that  previously  applied  to  partial matching have been
2261         lifted.  The  pcrepartial documentation gives details of partial match-         lifted. The pcrepartial documentation gives details of  partial  match-
2262         ing.         ing.
2263    
2264           PCRE_INFO_OPTIONS           PCRE_INFO_OPTIONS
2265    
2266         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
2267         fourth  argument  should  point to an unsigned long int variable. These         fourth argument should point to an unsigned long  int  variable.  These
2268         option bits are those specified in the call to pcre_compile(), modified         option bits are those specified in the call to pcre_compile(), modified
2269         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
2270         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
2271         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
2272         the PCRE_EXTENDED option, the result is PCRE_CASELESS,  PCRE_MULTILINE,         the  PCRE_EXTENDED option, the result is PCRE_CASELESS, PCRE_MULTILINE,
2273         and PCRE_EXTENDED.         and PCRE_EXTENDED.
2274    
2275         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
2276         alternatives begin with one of the following:         alternatives begin with one of the following:
2277    
2278           ^     unless PCRE_MULTILINE is set           ^     unless PCRE_MULTILINE is set
# Line 1830  INFORMATION ABOUT A PATTERN Line 2286  INFORMATION ABOUT A PATTERN
2286    
2287           PCRE_INFO_SIZE           PCRE_INFO_SIZE
2288    
2289         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).
2290         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
2291         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
2292         size_t variable.         pcre_compile().  The  value that is passed as the argument to pcre_mal-
2293           loc() when pcre_compile() is getting memory in which to place the  com-
2294           piled  data  is  the value returned by this option plus the size of the
2295           pcre structure. Studying a compiled pattern, with or without JIT,  does
2296           not alter the value returned by this option.
2297    
2298           PCRE_INFO_STUDYSIZE           PCRE_INFO_STUDYSIZE
2299    
2300         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
2301         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
2302         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
2303         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
2304         data, zero is returned. The fourth argument should point  to  a  size_t         information  that  will  speed  up  matching  (see the section entitled
2305         variable.         "Studying a pattern" above). The format of the study_data block is pri-
2306           vate,  but  its length is made available via this option so that it can
2307           be  saved  and  restored  (see  the  pcreprecompile  documentation  for
2308  OBSOLETE INFO FUNCTION         details).
   
        int pcre_info(const pcre *code, int *optptr, int *firstcharptr);  
   
        The  pcre_info()  function is now obsolete because its interface is too  
        restrictive to return all the available data about a compiled  pattern.  
        New   programs   should  use  pcre_fullinfo()  instead.  The  yield  of  
        pcre_info() is the number of capturing subpatterns, or one of the  fol-  
        lowing negative numbers:  
   
          PCRE_ERROR_NULL       the argument code was NULL  
          PCRE_ERROR_BADMAGIC   the "magic number" was not found  
   
        If  the  optptr  argument is not NULL, a copy of the options with which  
        the pattern was compiled is placed in the integer  it  points  to  (see  
        PCRE_INFO_OPTIONS above).  
   
        If  the  pattern  is  not anchored and the firstcharptr argument is not  
        NULL, it is used to pass back information about the first character  of  
        any matched string (see PCRE_INFO_FIRSTBYTE above).  
2309    
2310    
2311  REFERENCE COUNTS  REFERENCE COUNTS
# Line 1898  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2339  MATCHING A PATTERN: THE TRADITIONAL FUNC
2339         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
2340         compiled  pattern, which is passed in the code argument. If the pattern         compiled  pattern, which is passed in the code argument. If the pattern
2341         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
2342         argument.  This  function is the main matching facility of the library,         argument.  You  can call pcre_exec() with the same code and extra argu-
2343         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
2344         an  alternative matching function, which is described below in the sec-         strings with the same pattern.
2345         tion about the pcre_dfa_exec() function.  
2346           This  function  is  the  main  matching facility of the library, and it
2347           operates in a Perl-like manner. For specialist use  there  is  also  an
2348           alternative  matching function, which is described below in the section
2349           about the pcre_dfa_exec() function.
2350    
2351         In most applications, the pattern will have been compiled (and  option-         In most applications, the pattern will have been compiled (and  option-
2352         ally  studied)  in the same process that calls pcre_exec(). However, it         ally  studied)  in the same process that calls pcre_exec(). However, it
# Line 1933  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2378  MATCHING A PATTERN: THE TRADITIONAL FUNC
2378    
2379           unsigned long int flags;           unsigned long int flags;
2380           void *study_data;           void *study_data;
2381             void *executable_jit;
2382           unsigned long int match_limit;           unsigned long int match_limit;
2383           unsigned long int match_limit_recursion;           unsigned long int match_limit_recursion;
2384           void *callout_data;           void *callout_data;
2385           const unsigned char *tables;           const unsigned char *tables;
2386           unsigned char **mark;           unsigned char **mark;
2387    
2388         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
2389         are set. The flag bits are:         "PCRE_UCHAR16 **".
2390    
2391           PCRE_EXTRA_STUDY_DATA         The  flags  field is used to specify which of the other fields are set.
2392           The flag bits are:
2393    
2394             PCRE_EXTRA_CALLOUT_DATA
2395             PCRE_EXTRA_EXECUTABLE_JIT
2396             PCRE_EXTRA_MARK
2397           PCRE_EXTRA_MATCH_LIMIT           PCRE_EXTRA_MATCH_LIMIT
2398           PCRE_EXTRA_MATCH_LIMIT_RECURSION           PCRE_EXTRA_MATCH_LIMIT_RECURSION
2399           PCRE_EXTRA_CALLOUT_DATA           PCRE_EXTRA_STUDY_DATA
2400           PCRE_EXTRA_TABLES           PCRE_EXTRA_TABLES
          PCRE_EXTRA_MARK  
2401    
2402         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-
2403         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
2404         the appropriate flag bit. You should not set this yourself, but you may         returned by pcre_study(), together with the appropriate flag bits.  You
2405         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
2406         flag bits.         other fields and their corresponding flag bits.
2407    
2408         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
2409         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
2410         match,  but  which  have  a very large number of possibilities in their         match, but which have a very large number  of  possibilities  in  their
2411         search trees. The classic example is a pattern that uses nested  unlim-         search  trees. The classic example is a pattern that uses nested unlim-
2412         ited repeats.         ited repeats.
2413    
2414         Internally,  PCRE uses a function called match() which it calls repeat-         Internally, pcre_exec() uses a function called match(), which it  calls
2415         edly (sometimes recursively). The limit set by match_limit  is  imposed         repeatedly  (sometimes  recursively).  The  limit set by match_limit is
2416         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,
2417         has the effect of limiting the amount of  backtracking  that  can  take         which  has  the  effect of limiting the amount of backtracking that can
2418         place. For patterns that are not anchored, the count restarts from zero         take place. For patterns that are not anchored, the count restarts from
2419         for each position in the subject string.         zero for each position in the subject string.
2420    
2421           When pcre_exec() is called with a pattern that was successfully studied
2422           with a JIT option, the way that the matching is  executed  is  entirely
2423           different.  However, there is still the possibility of runaway matching
2424           that goes on for a very long time, and so the match_limit value is also
2425           used in this case (but in a different way) to limit how long the match-
2426           ing can continue.
2427    
2428         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
2429         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 1981  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2438  MATCHING A PATTERN: THE TRADITIONAL FUNC
2438         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-
2439         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.
2440    
2441         Limiting  the  recursion  depth  limits the amount of stack that can be         Limiting  the  recursion  depth limits the amount of machine stack that
2442         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
2443         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
2444           limit is not relevant, and is ignored, when matching is done using  JIT
2445           compiled code.
2446    
2447         The  default  value  for  match_limit_recursion can be set when PCRE is         The  default  value  for  match_limit_recursion can be set when PCRE is
2448         built; the default default  is  the  same  value  as  the  default  for         built; the default default  is  the  same  value  as  the  default  for
# Line 2007  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2466  MATCHING A PATTERN: THE TRADITIONAL FUNC
2466         tion for a discussion of saving compiled patterns for later use.         tion for a discussion of saving compiled patterns for later use.
2467    
2468         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
2469         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-
2470         tracking control verbs such as (*MARK:NAME), and the execution ends  up         tracking control verbs such as (*MARK:NAME), and the execution ends  up
2471         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-
2472         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
2473         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
2474         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.
2475         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
2476         field set to NULL. For details of the backtracking control  verbs,  see         field is set to NULL. For details of the  backtracking  control  verbs,
2477         the section entitled "Backtracking control" in the pcrepattern documen-         see the section entitled "Backtracking control" in the pcrepattern doc-
2478         tation.         umentation.
2479    
2480     Option bits for pcre_exec()     Option bits for pcre_exec()
2481    
2482         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.
2483         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,
2484         PCRE_NOTBOL,   PCRE_NOTEOL,    PCRE_NOTEMPTY,    PCRE_NOTEMPTY_ATSTART,         PCRE_NOTBOL,   PCRE_NOTEOL,    PCRE_NOTEMPTY,    PCRE_NOTEMPTY_ATSTART,
2485         PCRE_NO_START_OPTIMIZE,   PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_SOFT,  and         PCRE_NO_START_OPTIMIZE,   PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_HARD,  and
2486         PCRE_PARTIAL_HARD.         PCRE_PARTIAL_SOFT.
2487    
2488           If the pattern was successfully studied with one  of  the  just-in-time
2489           (JIT) compile options, the only supported options for JIT execution are
2490           PCRE_NO_UTF8_CHECK,    PCRE_NOTBOL,     PCRE_NOTEOL,     PCRE_NOTEMPTY,
2491           PCRE_NOTEMPTY_ATSTART,  PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an
2492           unsupported option is used, JIT execution is disabled  and  the  normal
2493           interpretive code in pcre_exec() is run.
2494    
2495           PCRE_ANCHORED           PCRE_ANCHORED
2496    
2497         The PCRE_ANCHORED option limits pcre_exec() to matching  at  the  first         The  PCRE_ANCHORED  option  limits pcre_exec() to matching at the first
2498         matching  position.  If  a  pattern was compiled with PCRE_ANCHORED, or         matching position. If a pattern was  compiled  with  PCRE_ANCHORED,  or
2499         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
2500         unachored at matching time.         unachored at matching time.
2501    
2502           PCRE_BSR_ANYCRLF           PCRE_BSR_ANYCRLF
2503           PCRE_BSR_UNICODE           PCRE_BSR_UNICODE
2504    
2505         These options (which are mutually exclusive) control what the \R escape         These options (which are mutually exclusive) control what the \R escape
2506         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,
2507         or  to  match  any Unicode newline sequence. These options override the         or to match any Unicode newline sequence. These  options  override  the
2508         choice that was made or defaulted when the pattern was compiled.         choice that was made or defaulted when the pattern was compiled.
2509    
2510           PCRE_NEWLINE_CR           PCRE_NEWLINE_CR
# Line 2047  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2513  MATCHING A PATTERN: THE TRADITIONAL FUNC
2513           PCRE_NEWLINE_ANYCRLF           PCRE_NEWLINE_ANYCRLF
2514           PCRE_NEWLINE_ANY           PCRE_NEWLINE_ANY
2515    
2516         These options override  the  newline  definition  that  was  chosen  or         These  options  override  the  newline  definition  that  was chosen or
2517         defaulted  when the pattern was compiled. For details, see the descrip-         defaulted when the pattern was compiled. For details, see the  descrip-
2518         tion of pcre_compile()  above.  During  matching,  the  newline  choice         tion  of  pcre_compile()  above.  During  matching,  the newline choice
2519         affects  the  behaviour  of the dot, circumflex, and dollar metacharac-         affects the behaviour of the dot, circumflex,  and  dollar  metacharac-
2520         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
2521         match failure for an unanchored pattern.         match failure for an unanchored pattern.
2522    
2523         When  PCRE_NEWLINE_CRLF,  PCRE_NEWLINE_ANYCRLF,  or PCRE_NEWLINE_ANY is         When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF,  or  PCRE_NEWLINE_ANY  is
2524         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-
2525         rent  position  is  at  a  CRLF  sequence,  and the pattern contains no         rent position is at a  CRLF  sequence,  and  the  pattern  contains  no
2526         explicit matches for  CR  or  LF  characters,  the  match  position  is         explicit  matches  for  CR  or  LF  characters,  the  match position is
2527         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
2528         CRLF.         CRLF.
2529    
2530         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
2531         expected.  For  example,  if  the  pattern  is .+A (and the PCRE_DOTALL         expected. For example, if the  pattern  is  .+A  (and  the  PCRE_DOTALL
2532         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
2533         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.
2534         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-
2535         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-
2536         acter after the first failure.         acter after the first failure.
2537    
2538         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
2539         those  characters,  or  one  of the \r or \n escape sequences. Implicit         those characters, or one of the \r or  \n  escape  sequences.  Implicit
2540         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
2541         LF in the characters that it matches).         LF in the characters that it matches).
2542    
2543         Notwithstanding  the above, anomalous effects may still occur when CRLF         Notwithstanding the above, anomalous effects may still occur when  CRLF
2544         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
2545         pattern.         pattern.
2546    
2547           PCRE_NOTBOL           PCRE_NOTBOL
2548    
2549         This option specifies that first character of the subject string is not         This option specifies that first character of the subject string is not
2550         the beginning of a line, so the  circumflex  metacharacter  should  not         the  beginning  of  a  line, so the circumflex metacharacter should not
2551         match  before it. Setting this without PCRE_MULTILINE (at compile time)         match before it. Setting this without PCRE_MULTILINE (at compile  time)
2552         causes circumflex never to match. This option affects only  the  behav-         causes  circumflex  never to match. This option affects only the behav-
2553         iour of the circumflex metacharacter. It does not affect \A.         iour of the circumflex metacharacter. It does not affect \A.
2554    
2555           PCRE_NOTEOL           PCRE_NOTEOL
2556    
2557         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
2558         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
2559         in  multiline mode) a newline immediately before it. Setting this with-         in multiline mode) a newline immediately before it. Setting this  with-
2560         out PCRE_MULTILINE (at compile time) causes dollar never to match. This         out PCRE_MULTILINE (at compile time) causes dollar never to match. This
2561         option  affects only the behaviour of the dollar metacharacter. It does         option affects only the behaviour of the dollar metacharacter. It  does
2562         not affect \Z or \z.         not affect \Z or \z.
2563    
2564           PCRE_NOTEMPTY           PCRE_NOTEMPTY
2565    
2566         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
2567         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
2568         the alternatives match the empty string, the entire  match  fails.  For         the  alternatives  match  the empty string, the entire match fails. For
2569         example, if the pattern         example, if the pattern
2570    
2571           a?b?           a?b?
2572    
2573         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
2574         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
2575         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-
2576         rences of "a" or "b".         rences of "a" or "b".
2577    
2578           PCRE_NOTEMPTY_ATSTART           PCRE_NOTEMPTY_ATSTART
2579    
2580         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
2581         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
2582         anchored, such a match can occur only if the pattern contains \K.         anchored, such a match can occur only if the pattern contains \K.
2583    
2584         Perl    has    no    direct    equivalent    of    PCRE_NOTEMPTY     or         Perl     has    no    direct    equivalent    of    PCRE_NOTEMPTY    or
2585         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
2586         match of the empty string within its split() function, and  when  using         match  of  the empty string within its split() function, and when using
2587         the  /g  modifier.  It  is  possible  to emulate Perl's behaviour after         the /g modifier. It is  possible  to  emulate  Perl's  behaviour  after
2588         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-
2589         set  with  PCRE_NOTEMPTY_ATSTART  and  PCRE_ANCHORED,  and then if that         set with PCRE_NOTEMPTY_ATSTART and  PCRE_ANCHORED,  and  then  if  that
2590         fails, by advancing the starting offset (see below) and trying an ordi-         fails, by advancing the starting offset (see below) and trying an ordi-
2591         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
2592         in the pcredemo sample program.         in  the  pcredemo sample program. In the most general case, you have to
2593           check to see if the newline convention recognizes CRLF  as  a  newline,
2594           and  if so, and the current character is CR followed by LF, advance the
2595           starting offset by two characters instead of one.
2596    
2597           PCRE_NO_START_OPTIMIZE           PCRE_NO_START_OPTIMIZE
2598    
# Line 2143  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2612  MATCHING A PATTERN: THE TRADITIONAL FUNC
2612         possibly  causing  performance  to  suffer,  but ensuring that in cases         possibly  causing  performance  to  suffer,  but ensuring that in cases
2613         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
2614         such as (*COMMIT) and (*MARK) are considered at every possible starting         such as (*COMMIT) and (*MARK) are considered at every possible starting
2615         position in the subject  string.   Setting  PCRE_NO_START_OPTIMIZE  can         position in the subject string. If  PCRE_NO_START_OPTIMIZE  is  set  at
2616         change the outcome of a matching operation.  Consider the pattern         compile  time,  it  cannot  be  unset  at  matching  time.  The  use of
2617           PCRE_NO_START_OPTIMIZE disables JIT execution; when it is set, matching
2618           is always done using interpretively.
2619    
2620           Setting  PCRE_NO_START_OPTIMIZE  can  change  the outcome of a matching
2621           operation.  Consider the pattern
2622    
2623           (*COMMIT)ABC           (*COMMIT)ABC
2624    
2625         When  this  is  compiled, PCRE records the fact that a match must start         When this is compiled, PCRE records the fact that a  match  must  start
2626         with the character "A". Suppose the subject  string  is  "DEFABC".  The         with  the  character  "A".  Suppose the subject string is "DEFABC". The
2627         start-up  optimization  scans along the subject, finds "A" and runs the         start-up optimization scans along the subject, finds "A" and  runs  the
2628         first match attempt from there. The (*COMMIT) item means that the  pat-         first  match attempt from there. The (*COMMIT) item means that the pat-
2629         tern  must  match the current starting position, which in this case, it         tern must match the current starting position, which in this  case,  it
2630         does. However, if the same match  is  run  with  PCRE_NO_START_OPTIMIZE         does.  However,  if  the  same match is run with PCRE_NO_START_OPTIMIZE
2631         set,  the  initial  scan  along the subject string does not happen. The         set, the initial scan along the subject string  does  not  happen.  The
2632         first match attempt is run starting  from  "D"  and  when  this  fails,         first  match  attempt  is  run  starting  from "D" and when this fails,
2633         (*COMMIT)  prevents  any  further  matches  being tried, so the overall         (*COMMIT) prevents any further matches  being  tried,  so  the  overall
2634         result is "no match". If the pattern is studied,  more  start-up  opti-         result  is  "no  match". If the pattern is studied, more start-up opti-
2635         mizations  may  be  used. For example, a minimum length for the subject         mizations may be used. For example, a minimum length  for  the  subject
2636         may be recorded. Consider the pattern         may be recorded. Consider the pattern
2637    
2638           (*MARK:A)(X|Y)           (*MARK:A)(X|Y)
2639    
2640         The minimum length for a match is one  character.  If  the  subject  is         The  minimum  length  for  a  match is one character. If the subject is
2641         "ABC",  there  will  be  attempts  to  match "ABC", "BC", "C", and then         "ABC", there will be attempts to  match  "ABC",  "BC",  "C",  and  then
2642         finally an empty string.  If the pattern is studied, the final  attempt         finally  an empty string.  If the pattern is studied, the final attempt
2643         does  not take place, because PCRE knows that the subject is too short,         does not take place, because PCRE knows that the subject is too  short,
2644         and so the (*MARK) is never encountered.  In this  case,  studying  the         and  so  the  (*MARK) is never encountered.  In this case, studying the
2645         pattern  does  not  affect the overall match result, which is still "no         pattern does not affect the overall match result, which  is  still  "no
2646         match", but it does affect the auxiliary information that is returned.         match", but it does affect the auxiliary information that is returned.
2647    
2648           PCRE_NO_UTF8_CHECK           PCRE_NO_UTF8_CHECK
2649    
2650         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
2651         UTF-8  string is automatically checked when pcre_exec() is subsequently         UTF-8 string is automatically checked when pcre_exec() is  subsequently
2652         called.  The value of startoffset is also checked  to  ensure  that  it         called.   The  value  of  startoffset is also checked to ensure that it
2653         points  to  the start of a UTF-8 character. There is a discussion about         points to the start of a UTF-8 character. There is a  discussion  about
2654         the validity of UTF-8 strings in the section on UTF-8  support  in  the         the  validity  of  UTF-8 strings in the pcreunicode page. If an invalid
2655         main  pcre  page.  If  an  invalid  UTF-8  sequence  of bytes is found,         sequence  of  bytes   is   found,   pcre_exec()   returns   the   error
2656         pcre_exec() returns the error PCRE_ERROR_BADUTF8. If  startoffset  con-         PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a
2657         tains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.         truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
2658           both  cases, information about the precise nature of the error may also
2659           be returned (see the descriptions of these errors in the section  enti-
2660           tled  Error return values from pcre_exec() below).  If startoffset con-
2661           tains a value that does not point to the start of a UTF-8 character (or
2662           to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is returned.
2663    
2664         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
2665         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 2667  MATCHING A PATTERN: THE TRADITIONAL FUNC
2667         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
2668         making  repeated  calls  to  find  all  the matches in a single subject         making  repeated  calls  to  find  all  the matches in a single subject
2669         string. However, you should be  sure  that  the  value  of  startoffset         string. However, you should be  sure  that  the  value  of  startoffset
2670         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
2671         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
2672         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
2673         acter, is undefined. Your program may crash.         may crash.
2674    
2675           PCRE_PARTIAL_HARD           PCRE_PARTIAL_HARD
2676           PCRE_PARTIAL_SOFT           PCRE_PARTIAL_SOFT
# Line 2200  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2679  MATCHING A PATTERN: THE TRADITIONAL FUNC
2679         patibility,  PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial         patibility,  PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial
2680         match occurs if the end of the subject string is reached  successfully,         match occurs if the end of the subject string is reached  successfully,
2681         but  there  are not enough subject characters to complete the match. If         but  there  are not enough subject characters to complete the match. If
2682         this happens when PCRE_PARTIAL_HARD  is  set,  pcre_exec()  immediately         this happens when PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set,
2683         returns  PCRE_ERROR_PARTIAL.  Otherwise,  if  PCRE_PARTIAL_SOFT is set,         matching  continues  by  testing any remaining alternatives. Only if no
2684         matching continues by testing any other alternatives. Only if they  all         complete match can be found is PCRE_ERROR_PARTIAL returned  instead  of
2685         fail  is  PCRE_ERROR_PARTIAL  returned (instead of PCRE_ERROR_NOMATCH).         PCRE_ERROR_NOMATCH.  In  other  words,  PCRE_PARTIAL_SOFT says that the
2686         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
2687         found  is  set  as  the first matching string. There is a more detailed         match can be found.
2688         discussion in the pcrepartial documentation.  
2689           If  PCRE_PARTIAL_HARD  is  set, it overrides PCRE_PARTIAL_SOFT. In this
2690           case, if a partial match  is  found,  pcre_exec()  immediately  returns
2691           PCRE_ERROR_PARTIAL,  without  considering  any  other  alternatives. In
2692           other words, when PCRE_PARTIAL_HARD is set, a partial match is  consid-
2693           ered to be more important that an alternative complete match.
2694    
2695           In  both  cases,  the portion of the string that was inspected when the
2696           partial match was found is set as the first matching string. There is a
2697           more  detailed  discussion  of partial and multi-segment matching, with
2698           examples, in the pcrepartial documentation.
2699    
2700     The string to be matched by pcre_exec()     The string to be matched by pcre_exec()
2701    
2702         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
2703         length (in bytes) in length, and a starting byte offset in startoffset.         length  in  bytes in length, and a starting byte offset in startoffset.
2704         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,
2705         acter.  Unlike  the pattern string, the subject may contain binary zero         pcre_exec()  returns  PCRE_ERROR_BADOFFSET. When the starting offset is
2706         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,
2707         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
2708         case.         must point to the start of a UTF-8 character (or the end  of  the  sub-
2709           ject).  Unlike  the pattern string, the subject may contain binary zero
2710           bytes.
2711    
2712         A non-zero starting offset is useful when searching for  another  match         A non-zero starting offset is useful when searching for  another  match
2713         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 2728  MATCHING A PATTERN: THE TRADITIONAL FUNC
2728         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
2729         discover that it is preceded by a letter.         discover that it is preceded by a letter.
2730    
2731         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
2732           match an empty string. It is possible to emulate Perl's /g behaviour by
2733           first   trying   the   match   again  at  the  same  offset,  with  the
2734           PCRE_NOTEMPTY_ATSTART and  PCRE_ANCHORED  options,  and  then  if  that
2735           fails,  advancing  the  starting  offset  and  trying an ordinary match
2736           again. There is some code that demonstrates how to do this in the pcre-
2737           demo sample program. In the most general case, you have to check to see
2738           if the newline convention recognizes CRLF as a newline, and if so,  and
2739           the current character is CR followed by LF, advance the starting offset
2740           by two characters instead of one.
2741    
2742           If a non-zero starting offset is passed when the pattern  is  anchored,
2743         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
2744         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
2745         subject.         subject.
2746    
2747     How pcre_exec() returns captured substrings     How pcre_exec() returns captured substrings
2748    
2749         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
2750         addition,  further  substrings  from  the  subject may be picked out by         addition, further substrings from the subject  may  be  picked  out  by
2751         parts of the pattern. Following the usage  in  Jeffrey  Friedl's  book,         parts  of  the  pattern.  Following the usage in Jeffrey Friedl's book,
2752         this  is  called "capturing" in what follows, and the phrase "capturing         this is called "capturing" in what follows, and the  phrase  "capturing
2753         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-
2754         string.  PCRE  supports several other kinds of parenthesized subpattern         string. PCRE supports several other kinds of  parenthesized  subpattern
2755         that do not cause substrings to be captured.         that do not cause substrings to be captured.
2756    
2757         Captured substrings are returned to the caller via a vector of integers         Captured substrings are returned to the caller via a vector of integers
2758         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-
2759         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:
2760         this argument is NOT the size of ovector in bytes.         this argument is NOT the size of ovector in bytes.
2761    
2762         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-
2763         strings, each substring using a pair of integers. The  remaining  third         strings,  each  substring using a pair of integers. The remaining third
2764         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-
2765         turing subpatterns, and is not available for passing back  information.         turing  subpatterns, and is not available for passing back information.
2766         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
2767         it is not, it is rounded down.         it is not, it is rounded down.
2768    
2769         When a match is successful, information about  captured  substrings  is         When  a  match  is successful, information about captured substrings is
2770         returned  in  pairs  of integers, starting at the beginning of ovector,         returned in pairs of integers, starting at the  beginning  of  ovector,
2771         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
2772         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
2773         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
2774         character  after  the end of a substring. Note: these values are always         character after the end of a substring. Note: these values  are  always
2775         byte offsets, even in UTF-8 mode. They are not character counts.         byte offsets, even in UTF-8 mode. They are not character counts.
2776    
2777         The first pair of integers, ovector[0]  and  ovector[1],  identify  the         The  first  pair  of  integers, ovector[0] and ovector[1], identify the
2778         portion  of  the subject string matched by the entire pattern. The next         portion of the subject string matched by the entire pattern.  The  next
2779         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
2780         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
2781         has been set.  For example, if two substrings have been  captured,  the         has  been  set.  For example, if two substrings have been captured, the
2782         returned  value is 3. If there are no capturing subpatterns, the return         returned value is 3. If there are no capturing subpatterns, the  return
2783         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
2784         of offsets has been set.         of offsets has been set.
2785    
2786         If a capturing subpattern is matched repeatedly, it is the last portion         If a capturing subpattern is matched repeatedly, it is the last portion
2787         of the string that it matched that is returned.         of the string that it matched that is returned.
2788    
2789         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,
2790         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
2791         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
2792         interest,  pcre_exec()  may  be  called with ovector passed as NULL and         not any captured substrings are of interest, pcre_exec() may be  called
2793         ovecsize as zero. However, if the pattern contains back references  and         with  ovector passed as NULL and ovecsize as zero. However, if the pat-
2794         the  ovector is not big enough to remember the related substrings, PCRE         tern contains back references and the ovector  is  not  big  enough  to
2795         has to get additional memory for use during matching. Thus it  is  usu-         remember  the related substrings, PCRE has to get additional memory for
2796         ally advisable to supply an ovector.         use during matching. Thus it is usually advisable to supply an  ovector
2797           of reasonable size.
2798    
2799           There  are  some  cases where zero is returned (indicating vector over-
2800           flow) when in fact the vector is exactly the right size for  the  final
2801           match. For example, consider the pattern
2802    
2803             (a)(?:(b)c|bd)
2804    
2805           If  a  vector of 6 elements (allowing for only 1 captured substring) is
2806           given with subject string "abd", pcre_exec() will try to set the second
2807           captured string, thereby recording a vector overflow, before failing to
2808           match "c" and backing up  to  try  the  second  alternative.  The  zero
2809           return,  however,  does  correctly  indicate that the maximum number of
2810           slots (namely 2) have been filled. In similar cases where there is tem-
2811           porary  overflow,  but  the final number of used slots is actually less
2812           than the maximum, a non-zero value is returned.
2813    
2814         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
2815         subpatterns there are in a compiled  pattern.  The  smallest  size  for         subpatterns  there  are  in  a  compiled pattern. The smallest size for
2816         ovector  that  will allow for n captured substrings, in addition to the         ovector that will allow for n captured substrings, in addition  to  the
2817         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.
2818    
2819         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
2820         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,
2821         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
2822         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
2823         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-
2824         sponding to unused subpatterns are set to -1.         sponding to unused subpatterns are set to -1.
2825    
2826         Offset  values  that correspond to unused subpatterns at the end of the         Offset values that correspond to unused subpatterns at the end  of  the
2827         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
2828         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
2829         matched. The return from the function is 2, because  the  highest  used         matched.  The  return  from the function is 2, because the highest used
2830         capturing subpattern number is 1. However, you can refer to the offsets         capturing subpattern number is 1, and the offsets for  for  the  second
2831         for the second and third capturing subpatterns if  you  wish  (assuming         and  third  capturing subpatterns (assuming the vector is large enough,
2832         the vector is large enough, of course).         of course) are set to -1.
2833    
2834           Note: Elements in the first two-thirds of ovector that  do  not  corre-
2835           spond  to  capturing parentheses in the pattern are never changed. That
2836           is, if a pattern contains n capturing parentheses, no more  than  ovec-
2837           tor[0]  to ovector[2n+1] are set by pcre_exec(). The other elements (in
2838           the first two-thirds) retain whatever values they previously had.
2839    
2840         Some  convenience  functions  are  provided for extracting the captured         Some convenience functions are provided  for  extracting  the  captured
2841         substrings as separate strings. These are described below.         substrings as separate strings. These are described below.
2842    
2843     Error return values from pcre_exec()     Error return values from pcre_exec()
2844    
2845         If pcre_exec() fails, it returns a negative number. The  following  are         If  pcre_exec()  fails, it returns a negative number. The following are
2846         defined in the header file:         defined in the header file:
2847    
2848           PCRE_ERROR_NOMATCH        (-1)           PCRE_ERROR_NOMATCH        (-1)
# Line 2327  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2851  MATCHING A PATTERN: THE TRADITIONAL FUNC
2851    
2852           PCRE_ERROR_NULL           (-2)           PCRE_ERROR_NULL           (-2)
2853    
2854         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
2855         ovecsize was not zero.         ovecsize was not zero.
2856    
2857           PCRE_ERROR_BADOPTION      (-3)           PCRE_ERROR_BADOPTION      (-3)
# Line 2336  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2860  MATCHING A PATTERN: THE TRADITIONAL FUNC
2860    
2861           PCRE_ERROR_BADMAGIC       (-4)           PCRE_ERROR_BADMAGIC       (-4)
2862    
2863         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,
2864         to catch the case when it is passed a junk pointer and to detect when a         to catch the case when it is passed a junk pointer and to detect when a
2865         pattern that was compiled in an environment of one endianness is run in         pattern that was compiled in an environment of one endianness is run in
2866         an  environment  with the other endianness. This is the error that PCRE         an environment with the other endianness. This is the error  that  PCRE
2867         gives when the magic number is not present.         gives when the magic number is not present.
2868    
2869           PCRE_ERROR_UNKNOWN_OPCODE (-5)           PCRE_ERROR_UNKNOWN_OPCODE (-5)
2870    
2871         While running the pattern match, an unknown item was encountered in the         While running the pattern match, an unknown item was encountered in the
2872         compiled  pattern.  This  error  could be caused by a bug in PCRE or by         compiled pattern. This error could be caused by a bug  in  PCRE  or  by
2873         overwriting of the compiled pattern.         overwriting of the compiled pattern.
2874    
2875           PCRE_ERROR_NOMEMORY       (-6)           PCRE_ERROR_NOMEMORY       (-6)
2876    
2877         If a pattern contains back references, but the ovector that  is  passed         If  a  pattern contains back references, but the ovector that is passed
2878         to pcre_exec() is not big enough to remember the referenced substrings,         to pcre_exec() is not big enough to remember the referenced substrings,
2879         PCRE gets a block of memory at the start of matching to  use  for  this         PCRE  gets  a  block of memory at the start of matching to use for this
2880         purpose.  If the call via pcre_malloc() fails, this error is given. The         purpose. If the call via pcre_malloc() fails, this error is given.  The
2881         memory is automatically freed at the end of matching.         memory is automatically freed at the end of matching.
2882    
2883         This error is also given if pcre_stack_malloc() fails  in  pcre_exec().         This  error  is also given if pcre_stack_malloc() fails in pcre_exec().
2884         This  can happen only when PCRE has been compiled with --disable-stack-         This can happen only when PCRE has been compiled with  --disable-stack-
2885         for-recursion.         for-recursion.
2886    
2887           PCRE_ERROR_NOSUBSTRING    (-7)           PCRE_ERROR_NOSUBSTRING    (-7)
2888    
2889         This error is used by the pcre_copy_substring(),  pcre_get_substring(),         This  error is used by the pcre_copy_substring(), pcre_get_substring(),
2890         and  pcre_get_substring_list()  functions  (see  below).  It  is  never         and  pcre_get_substring_list()  functions  (see  below).  It  is  never
2891         returned by pcre_exec().         returned by pcre_exec().
2892    
2893           PCRE_ERROR_MATCHLIMIT     (-8)           PCRE_ERROR_MATCHLIMIT     (-8)
2894    
2895         The backtracking limit, as specified by  the  match_limit  field  in  a         The  backtracking  limit,  as  specified  by the match_limit field in a
2896         pcre_extra  structure  (or  defaulted) was reached. See the description         pcre_extra structure (or defaulted) was reached.  See  the  description
2897         above.         above.
2898    
2899           PCRE_ERROR_CALLOUT        (-9)           PCRE_ERROR_CALLOUT        (-9)
2900    
2901         This error is never generated by pcre_exec() itself. It is provided for         This error is never generated by pcre_exec() itself. It is provided for
2902         use  by  callout functions that want to yield a distinctive error code.         use by callout functions that want to yield a distinctive  error  code.
2903         See the pcrecallout documentation for details.         See the pcrecallout documentation for details.
2904    
2905           PCRE_ERROR_BADUTF8        (-10)           PCRE_ERROR_BADUTF8        (-10)
2906    
2907         A string that contains an invalid UTF-8 byte sequence was passed  as  a         A  string  that contains an invalid UTF-8 byte sequence was passed as a
2908         subject.         subject, and the PCRE_NO_UTF8_CHECK option was not set. If the size  of
2909           the  output  vector  (ovecsize)  is  at least 2, the byte offset to the
2910           start of the the invalid UTF-8 character is placed in  the  first  ele-
2911           ment,  and  a  reason  code is placed in the second element. The reason
2912           codes are listed in the following section.  For backward compatibility,
2913           if  PCRE_PARTIAL_HARD is set and the problem is a truncated UTF-8 char-
2914           acter  at  the  end  of  the   subject   (reason   codes   1   to   5),
2915           PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
2916    
2917           PCRE_ERROR_BADUTF8_OFFSET (-11)           PCRE_ERROR_BADUTF8_OFFSET (-11)
2918    
2919         The UTF-8 byte sequence that was passed as a subject was valid, but the         The  UTF-8  byte  sequence that was passed as a subject was checked and
2920         value of startoffset did not point to the beginning of a UTF-8  charac-         found to be valid (the PCRE_NO_UTF8_CHECK option was not set), but  the
2921         ter.         value  of startoffset did not point to the beginning of a UTF-8 charac-
2922           ter or the end of the subject.
2923    
2924           PCRE_ERROR_PARTIAL        (-12)           PCRE_ERROR_PARTIAL        (-12)
2925    
2926         The  subject  string did not match, but it did match partially. See the         The subject string did not match, but it did match partially.  See  the
2927         pcrepartial documentation for details of partial matching.         pcrepartial documentation for details of partial matching.
2928    
2929           PCRE_ERROR_BADPARTIAL     (-13)           PCRE_ERROR_BADPARTIAL     (-13)
2930    
2931         This code is no longer in  use.  It  was  formerly  returned  when  the         This  code  is  no  longer  in  use.  It was formerly returned when the
2932         PCRE_PARTIAL  option  was used with a compiled pattern containing items         PCRE_PARTIAL option was used with a compiled pattern  containing  items
2933         that were  not  supported  for  partial  matching.  From  release  8.00         that  were  not  supported  for  partial  matching.  From  release 8.00
2934         onwards, there are no restrictions on partial matching.         onwards, there are no restrictions on partial matching.
2935    
2936           PCRE_ERROR_INTERNAL       (-14)           PCRE_ERROR_INTERNAL       (-14)
2937    
2938         An  unexpected  internal error has occurred. This error could be caused         An unexpected internal error has occurred. This error could  be  caused
2939         by a bug in PCRE or by overwriting of the compiled pattern.         by a bug in PCRE or by overwriting of the compiled pattern.
2940    
2941           PCRE_ERROR_BADCOUNT       (-15)           PCRE_ERROR_BADCOUNT       (-15)
# Line 2413  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2945  MATCHING A PATTERN: THE TRADITIONAL FUNC
2945           PCRE_ERROR_RECURSIONLIMIT (-21)           PCRE_ERROR_RECURSIONLIMIT (-21)
2946    
2947         The internal recursion limit, as specified by the match_limit_recursion         The internal recursion limit, as specified by the match_limit_recursion
2948         field  in  a  pcre_extra  structure (or defaulted) was reached. See the         field in a pcre_extra structure (or defaulted)  was  reached.  See  the
2949         description above.         description above.
2950    
2951           PCRE_ERROR_BADNEWLINE     (-23)           PCRE_ERROR_BADNEWLINE     (-23)
2952    
2953         An invalid combination of PCRE_NEWLINE_xxx options was given.         An invalid combination of PCRE_NEWLINE_xxx options was given.
2954    
2955             PCRE_ERROR_BADOFFSET      (-24)
2956    
2957           The value of startoffset was negative or greater than the length of the
2958           subject, that is, the value in length.
2959    
2960             PCRE_ERROR_SHORTUTF8      (-25)
2961    
2962           This error is returned instead of PCRE_ERROR_BADUTF8 when  the  subject
2963           string  ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD
2964           option is set.  Information  about  the  failure  is  returned  as  for
2965           PCRE_ERROR_BADUTF8.  It  is in fact sufficient to detect this case, but
2966           this special error code for PCRE_PARTIAL_HARD precedes the  implementa-
2967           tion  of returned information; it is retained for backwards compatibil-
2968           ity.
2969    
2970             PCRE_ERROR_RECURSELOOP    (-26)
2971    
2972           This error is returned when pcre_exec() detects a recursion loop within
2973           the  pattern. Specifically, it means that either the whole pattern or a
2974           subpattern has been called recursively for the second time at the  same
2975           position in the subject string. Some simple patterns that might do this
2976           are detected and faulted at compile time, but more  complicated  cases,
2977           in particular mutual recursions between two different subpatterns, can-
2978           not be detected until run time.
2979    
2980             PCRE_ERROR_JIT_STACKLIMIT (-27)
2981    
2982           This error is returned when a pattern  that  was  successfully  studied
2983           using  a  JIT compile option is being matched, but the memory available
2984           for the just-in-time processing stack is  not  large  enough.  See  the
2985           pcrejit documentation for more details.
2986    
2987             PCRE_ERROR_BADMODE (-28)
2988    
2989           This error is given if a pattern that was compiled by the 8-bit library
2990           is passed to a 16-bit library function, or vice versa.
2991    
2992             PCRE_ERROR_BADENDIANNESS (-29)
2993    
2994           This error is given if  a  pattern  that  was  compiled  and  saved  is
2995           reloaded  on  a  host  with  different endianness. The utility function
2996           pcre_pattern_to_host_byte_order() can be used to convert such a pattern
2997           so that it runs on the new host.
2998    
2999         Error numbers -16 to -20 and -22 are not used by pcre_exec().         Error numbers -16 to -20 and -22 are not used by pcre_exec().
3000    
3001       Reason codes for invalid UTF-8 strings
3002    
3003           This  section  applies  only  to  the  8-bit library. The corresponding
3004           information for the 16-bit library is given in the pcre16 page.
3005    
3006           When pcre_exec() returns either PCRE_ERROR_BADUTF8 or PCRE_ERROR_SHORT-
3007           UTF8,  and  the size of the output vector (ovecsize) is at least 2, the
3008           offset of the start of the invalid UTF-8 character  is  placed  in  the
3009           first output vector element (ovector[0]) and a reason code is placed in
3010           the second element (ovector[1]). The reason codes are  given  names  in
3011           the pcre.h header file:
3012    
3013             PCRE_UTF8_ERR1
3014             PCRE_UTF8_ERR2
3015             PCRE_UTF8_ERR3
3016             PCRE_UTF8_ERR4
3017             PCRE_UTF8_ERR5
3018    
3019           The  string  ends  with a truncated UTF-8 character; the code specifies
3020           how many bytes are missing (1 to 5). Although RFC 3629 restricts  UTF-8
3021           characters  to  be  no longer than 4 bytes, the encoding scheme (origi-
3022           nally defined by RFC 2279) allows for  up  to  6  bytes,  and  this  is
3023           checked first; hence the possibility of 4 or 5 missing bytes.
3024    
3025             PCRE_UTF8_ERR6
3026             PCRE_UTF8_ERR7
3027             PCRE_UTF8_ERR8
3028             PCRE_UTF8_ERR9
3029             PCRE_UTF8_ERR10
3030    
3031           The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of
3032           the character do not have the binary value 0b10 (that  is,  either  the
3033           most significant bit is 0, or the next bit is 1).
3034    
3035             PCRE_UTF8_ERR11
3036             PCRE_UTF8_ERR12
3037    
3038           A  character that is valid by the RFC 2279 rules is either 5 or 6 bytes
3039           long; these code points are excluded by RFC 3629.
3040    
3041             PCRE_UTF8_ERR13
3042    
3043           A 4-byte character has a value greater than 0x10fff; these code  points
3044           are excluded by RFC 3629.
3045    
3046             PCRE_UTF8_ERR14
3047    
3048           A  3-byte  character  has  a  value in the range 0xd800 to 0xdfff; this
3049           range of code points are reserved by RFC 3629 for use with UTF-16,  and
3050           so are excluded from UTF-8.
3051    
3052             PCRE_UTF8_ERR15
3053             PCRE_UTF8_ERR16
3054             PCRE_UTF8_ERR17
3055             PCRE_UTF8_ERR18
3056             PCRE_UTF8_ERR19
3057    
3058           A  2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes
3059           for a value that can be represented by fewer bytes, which  is  invalid.
3060           For  example,  the two bytes 0xc0, 0xae give the value 0x2e, whose cor-
3061           rect coding uses just one byte.
3062    
3063             PCRE_UTF8_ERR20
3064    
3065           The two most significant bits of the first byte of a character have the
3066           binary  value 0b10 (that is, the most significant bit is 1 and the sec-
3067           ond is 0). Such a byte can only validly occur as the second  or  subse-
3068           quent byte of a multi-byte character.
3069    
3070             PCRE_UTF8_ERR21
3071    
3072           The  first byte of a character has the value 0xfe or 0xff. These values
3073           can never occur in a valid UTF-8 string.
3074    
3075    
3076  EXTRACTING CAPTURED SUBSTRINGS BY NUMBER  EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
3077    
# Line 2597  DUPLICATE SUBPATTERN NAMES Line 3247  DUPLICATE SUBPATTERN NAMES
3247         the name-to-number table  for  the  given  name.  The  function  itself         the name-to-number table  for  the  given  name.  The  function  itself
3248         returns  the  length  of  each entry, or PCRE_ERROR_NOSUBSTRING (-7) if         returns  the  length  of  each entry, or PCRE_ERROR_NOSUBSTRING (-7) if
3249         there are none. The format of the table is described above in the  sec-         there are none. The format of the table is described above in the  sec-
3250         tion  entitled  Information  about  a  pattern.  Given all the relevant         tion  entitled  Information about a pattern above.  Given all the rele-
3251         entries for the name, you can extract each of their numbers, and  hence         vant entries for the name, you can extract each of their  numbers,  and
3252         the captured data, if any.         hence the captured data, if any.
3253    
3254    
3255  FINDING ALL POSSIBLE MATCHES  FINDING ALL POSSIBLE MATCHES
# Line 2620  FINDING ALL POSSIBLE MATCHES Line 3270  FINDING ALL POSSIBLE MATCHES
3270         matches, pcre_exec() will yield PCRE_ERROR_NOMATCH.         matches, pcre_exec() will yield PCRE_ERROR_NOMATCH.
3271    
3272    
3273    OBTAINING AN ESTIMATE OF STACK USAGE
3274    
3275           Matching certain patterns using pcre_exec() can use a  lot  of  process
3276           stack,  which  in  certain  environments can be rather limited in size.
3277           Some users find it helpful to have an estimate of the amount  of  stack
3278           that  is  used  by  pcre_exec(),  to help them set recursion limits, as
3279           described in the pcrestack documentation. The estimate that  is  output
3280           by pcretest when called with the -m and -C options is obtained by call-
3281           ing pcre_exec with the values NULL, NULL, NULL, -999, and -999 for  its
3282           first five arguments.
3283    
3284           Normally,  if  its  first  argument  is  NULL,  pcre_exec() immediately
3285           returns the negative error code PCRE_ERROR_NULL, but with this  special
3286           combination  of  arguments,  it returns instead a negative number whose
3287           absolute value is the approximate stack frame size in bytes.  (A  nega-
3288           tive  number  is  used so that it is clear that no match has happened.)
3289           The value is approximate because in  some  cases,  recursive  calls  to
3290           pcre_exec() occur when there are one or two additional variables on the
3291           stack.
3292    
3293           If PCRE has been compiled to use the heap  instead  of  the  stack  for
3294           recursion,  the  value  returned  is  the  size  of  each block that is
3295           obtained from the heap.
3296    
3297    
3298  MATCHING A PATTERN: THE ALTERNATIVE FUNCTION  MATCHING A PATTERN: THE ALTERNATIVE FUNCTION
3299    
3300         int pcre_dfa_exec(const pcre *code, const pcre_extra *extra,         int pcre_dfa_exec(const pcre *code, const pcre_extra *extra,
# Line 2690  MATCHING A PATTERN: THE ALTERNATIVE FUNC Line 3365  MATCHING A PATTERN: THE ALTERNATIVE FUNC
3365         of the subject is reached, there have been  no  complete  matches,  but         of the subject is reached, there have been  no  complete  matches,  but
3366         there  is  still  at least one matching possibility. The portion of the         there  is  still  at least one matching possibility. The portion of the
3367         string that was inspected when the longest partial match was  found  is         string that was inspected when the longest partial match was  found  is
3368         set as the first matching string in both cases.         set  as  the  first  matching  string  in  both cases.  There is a more
3369           detailed discussion of partial and multi-segment matching,  with  exam-
3370           ples, in the pcrepartial documentation.
3371    
3372           PCRE_DFA_SHORTEST           PCRE_DFA_SHORTEST
3373    
# Line 2741  MATCHING A PATTERN: THE ALTERNATIVE FUNC Line 3418  MATCHING A PATTERN: THE ALTERNATIVE FUNC
3418         The strings are returned in reverse order of length; that is, the long-         The strings are returned in reverse order of length; that is, the long-
3419         est matching string is given first. If there were too many  matches  to         est matching string is given first. If there were too many  matches  to
3420         fit  into ovector, the yield of the function is zero, and the vector is         fit  into ovector, the yield of the function is zero, and the vector is
3421         filled with the longest matches.         filled with the longest matches.  Unlike  pcre_exec(),  pcre_dfa_exec()
3422           can use the entire ovector for returning matched strings.
3423    
3424     Error returns from pcre_dfa_exec()     Error returns from pcre_dfa_exec()
3425    
3426         The pcre_dfa_exec() function returns a negative number when  it  fails.         The  pcre_dfa_exec()  function returns a negative number when it fails.
3427         Many  of  the  errors  are  the  same as for pcre_exec(), and these are         Many of the errors are the same  as  for  pcre_exec(),  and  these  are
3428         described above.  There are in addition the following errors  that  are         described  above.   There are in addition the following errors that are
3429         specific to pcre_dfa_exec():         specific to pcre_dfa_exec():
3430    
3431           PCRE_ERROR_DFA_UITEM      (-16)           PCRE_ERROR_DFA_UITEM      (-16)
3432    
3433         This  return is given if pcre_dfa_exec() encounters an item in the pat-         This return is given if pcre_dfa_exec() encounters an item in the  pat-
3434         tern that it does not support, for instance, the use of \C  or  a  back         tern  that  it  does not support, for instance, the use of \C or a back
3435         reference.         reference.
3436    
3437           PCRE_ERROR_DFA_UCOND      (-17)           PCRE_ERROR_DFA_UCOND      (-17)
3438    
3439         This  return  is  given  if pcre_dfa_exec() encounters a condition item         This return is given if pcre_dfa_exec()  encounters  a  condition  item
3440         that uses a back reference for the condition, or a test  for  recursion         that  uses  a back reference for the condition, or a test for recursion
3441         in a specific group. These are not supported.         in a specific group. These are not supported.
3442    
3443           PCRE_ERROR_DFA_UMLIMIT    (-18)           PCRE_ERROR_DFA_UMLIMIT    (-18)
3444    
3445         This  return  is given if pcre_dfa_exec() is called with an extra block         This return is given if pcre_dfa_exec() is called with an  extra  block
3446         that contains a setting of the match_limit field. This is not supported         that  contains  a  setting  of the match_limit or match_limit_recursion
3447         (it is meaningless).         fields. This is not supported (these fields  are  meaningless  for  DFA
3448           matching).
3449    
3450           PCRE_ERROR_DFA_WSSIZE     (-19)           PCRE_ERROR_DFA_WSSIZE     (-19)
3451    
# Line 2783  MATCHING A PATTERN: THE ALTERNATIVE FUNC Line 3462  MATCHING A PATTERN: THE ALTERNATIVE FUNC
3462    
3463  SEE ALSO  SEE ALSO
3464    
3465         pcrebuild(3),  pcrecallout(3), pcrecpp(3)(3), pcrematching(3), pcrepar-         pcre16(3),   pcrebuild(3),  pcrecallout(3),  pcrecpp(3)(3),  pcrematch-
3466         tial(3), pcreposix(3), pcreprecompile(3), pcresample(3), pcrestack(3).         ing(3), pcrepartial(3), pcreposix(3), pcreprecompile(3), pcresample(3),
3467           pcrestack(3).
3468    
3469    
3470  AUTHOR  AUTHOR
# Line 2796  AUTHOR Line 3476  AUTHOR
3476    
3477  REVISION  REVISION
3478    
3479         Last updated: 21 June 2010         Last updated: 22 February 2012
3480         Copyright (c) 1997-2010 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
3481  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
3482    
3483    
3484  PCRECALLOUT(3)                                                  PCRECALLOUT(3)  PCRECALLOUT(3)                                                  PCRECALLOUT(3)
3485    
3486    
# Line 2812  PCRE CALLOUTS Line 3492  PCRE CALLOUTS
3492    
3493         int (*pcre_callout)(pcre_callout_block *);         int (*pcre_callout)(pcre_callout_block *);
3494    
3495           int (*pcre16_callout)(pcre16_callout_block *);
3496    
3497         PCRE provides a feature called "callout", which is a means of temporar-         PCRE provides a feature called "callout", which is a means of temporar-
3498         ily passing control to the caller of PCRE  in  the  middle  of  pattern         ily passing control to the caller of PCRE  in  the  middle  of  pattern
3499         matching.  The  caller of PCRE provides an external function by putting         matching.  The  caller of PCRE provides an external function by putting
3500         its entry point in the global variable pcre_callout. By  default,  this         its entry point in the global variable pcre_callout (pcre16_callout for
3501         variable contains NULL, which disables all calling out.         the  16-bit  library).  By  default, this variable contains NULL, which
3502           disables all calling out.
3503    
3504         Within  a  regular  expression,  (?C) indicates the points at which the         Within a regular expression, (?C) indicates the  points  at  which  the
3505         external function is to be called.  Different  callout  points  can  be         external  function  is  to  be  called. Different callout points can be
3506         identified  by  putting  a number less than 256 after the letter C. The         identified by putting a number less than 256 after the  letter  C.  The
3507         default value is zero.  For  example,  this  pattern  has  two  callout         default  value  is  zero.   For  example,  this pattern has two callout
3508         points:         points:
3509    
3510           (?C1)abc(?C2)def           (?C1)abc(?C2)def
3511    
3512         If  the  PCRE_AUTO_CALLOUT  option  bit  is  set when pcre_compile() or         If the PCRE_AUTO_CALLOUT option bit is set when a pattern is  compiled,
3513         pcre_compile2() is called, PCRE  automatically  inserts  callouts,  all         PCRE  automatically  inserts callouts, all with number 255, before each
3514         with  number  255,  before  each  item  in the pattern. For example, if         item in the pattern. For example, if PCRE_AUTO_CALLOUT is used with the
3515         PCRE_AUTO_CALLOUT is used with the pattern         pattern
3516    
3517           A(\d{2}|--)           A(\d{2}|--)
3518    
# Line 2837  PCRE CALLOUTS Line 3520  PCRE CALLOUTS
3520    
3521         (?C255)A(?C255)((?C255)\d{2}(?C255)|(?C255)-(?C255)-(?C255))(?C255)         (?C255)A(?C255)((?C255)\d{2}(?C255)|(?C255)-(?C255)-(?C255))(?C255)
3522    
3523         Notice that there is a callout before and after  each  parenthesis  and         Notice  that  there  is a callout before and after each parenthesis and
3524         alternation  bar.  Automatic  callouts  can  be  used  for tracking the         alternation bar. Automatic  callouts  can  be  used  for  tracking  the
3525         progress of pattern matching. The pcretest command has an  option  that         progress  of  pattern matching. The pcretest command has an option that
3526         sets  automatic callouts; when it is used, the output indicates how the         sets automatic callouts; when it is used, the output indicates how  the
3527         pattern is matched. This is useful information when you are  trying  to         pattern  is  matched. This is useful information when you are trying to
3528         optimize the performance of a particular pattern.         optimize the performance of a particular pattern.
3529    
3530           The use of callouts in a pattern makes it ineligible  for  optimization
3531           by  the  just-in-time  compiler.  Studying  such  a  pattern  with  the
3532           PCRE_STUDY_JIT_COMPILE option always fails.
3533    
3534    
3535  MISSING CALLOUTS  MISSING CALLOUTS
3536    
3537         You  should  be  aware  that,  because of optimizations in the way PCRE         You should be aware that, because of  optimizations  in  the  way  PCRE
3538         matches patterns by default, callouts  sometimes  do  not  happen.  For         matches  patterns  by  default,  callouts  sometimes do not happen. For
3539         example, if the pattern is         example, if the pattern is
3540    
3541           ab(?C4)cd           ab(?C4)cd
3542    
3543         PCRE knows that any matching string must contain the letter "d". If the         PCRE knows that any matching string must contain the letter "d". If the
3544         subject string is "abyz", the lack of "d" means that  matching  doesn't         subject  string  is "abyz", the lack of "d" means that matching doesn't
3545         ever  start,  and  the  callout is never reached. However, with "abyd",         ever start, and the callout is never  reached.  However,  with  "abyd",
3546         though the result is still no match, the callout is obeyed.         though the result is still no match, the callout is obeyed.
3547    
3548         If the pattern is studied, PCRE knows the minimum length of a  matching         If  the pattern is studied, PCRE knows the minimum length of a matching
3549         string,  and will immediately give a "no match" return without actually         string, and will immediately give a "no match" return without  actually
3550         running a match if the subject is not long enough, or,  for  unanchored         running  a  match if the subject is not long enough, or, for unanchored
3551         patterns, if it has been scanned far enough.         patterns, if it has been scanned far enough.
3552    
3553         You  can disable these optimizations by passing the PCRE_NO_START_OPTI-         You can disable these optimizations by passing the  PCRE_NO_START_OPTI-
3554         MIZE option to pcre_exec() or  pcre_dfa_exec().  This  slows  down  the         MIZE  option  to the matching function, or by starting the pattern with
3555         matching  process,  but  does  ensure that callouts such as the example         (*NO_START_OPT). This slows down the matching process, but does  ensure
3556         above are obeyed.         that callouts such as the example above are obeyed.
3557    
3558    
3559  THE CALLOUT INTERFACE  THE CALLOUT INTERFACE
3560    
3561         During matching, when PCRE reaches a callout point, the external  func-         During  matching, when PCRE reaches a callout point, the external func-
3562         tion  defined by pcre_callout is called (if it is set). This applies to         tion defined by pcre_callout or pcre16_callout  is  called  (if  it  is
3563         both the pcre_exec() and the pcre_dfa_exec()  matching  functions.  The         set).   This applies to both normal and DFA matching. The only argument
3564         only  argument  to  the callout function is a pointer to a pcre_callout         to the callout function is a pointer to a pcre_callout or  pcre16_call-
3565         block. This structure contains the following fields:         out block.  These structures contains the following fields:
3566    
3567           int          version;           int           version;
3568           int          callout_number;           int           callout_number;
3569           int         *offset_vector;           int          *offset_vector;
3570           const char  *subject;           const char   *subject;           (8-bit version)
3571           int          subject_length;           PCRE_SPTR16   subject;           (16-bit version)
3572           int          start_match;           int           subject_length;
3573           int          current_position;           int           start_match;
3574           int          capture_top;           int           current_position;
3575           int          capture_last;           int           capture_top;
3576           void        *callout_data;           int           capture_last;
3577           int          pattern_position;           void         *callout_data;
3578           int          next_item_length;           int           pattern_position;
3579             int           next_item_length;
3580         The version field is an integer containing the version  number  of  the           const unsigned char *mark;       (8-bit version)
3581         block  format. The initial version was 0; the current version is 1. The           const PCRE_UCHAR16  *mark;       (16-bit version)
3582         version number will change again in future  if  additional  fields  are  
3583           The  version  field  is an integer containing the version number of the
3584           block format. The initial version was 0; the current version is 2.  The
3585           version  number  will  change  again in future if additional fields are
3586         added, but the intention is never to remove any of the existing fields.         added, but the intention is never to remove any of the existing fields.
3587    
3588         The  callout_number  field  contains the number of the callout, as com-         The callout_number field contains the number of the  callout,  as  com-
3589         piled into the pattern (that is, the number after ?C for  manual  call-         piled  into  the pattern (that is, the number after ?C for manual call-
3590         outs, and 255 for automatically generated callouts).         outs, and 255 for automatically generated callouts).
3591    
3592         The  offset_vector field is a pointer to the vector of offsets that was         The offset_vector field is a pointer to the vector of offsets that  was
3593         passed  by  the  caller  to  pcre_exec()   or   pcre_dfa_exec().   When         passed  by  the  caller  to  the matching function. When pcre_exec() or
3594         pcre_exec()  is used, the contents can be inspected in order to extract         pcre16_exec() is used, the contents  can  be  inspected,  in  order  to
3595         substrings that have been matched so  far,  in  the  same  way  as  for         extract  substrings  that  have been matched so far, in the same way as
3596         extracting  substrings after a match has completed. For pcre_dfa_exec()         for extracting substrings after a match  has  completed.  For  the  DFA
3597         this field is not useful.         matching functions, this field is not useful.
3598    
3599         The subject and subject_length fields contain copies of the values that         The subject and subject_length fields contain copies of the values that
3600         were passed to pcre_exec().         were passed to the matching function.
3601    
3602         The  start_match  field normally contains the offset within the subject         The start_match field normally contains the offset within  the  subject
3603         at which the current match attempt  started.  However,  if  the  escape         at  which  the  current  match  attempt started. However, if the escape
3604         sequence  \K has been encountered, this value is changed to reflect the         sequence \K has been encountered, this value is changed to reflect  the
3605         modified starting point. If the pattern is not  anchored,  the  callout         modified  starting  point.  If the pattern is not anchored, the callout
3606         function may be called several times from the same point in the pattern         function may be called several times from the same point in the pattern
3607         for different starting points in the subject.         for different starting points in the subject.
3608    
3609         The current_position field contains the offset within  the  subject  of         The  current_position  field  contains the offset within the subject of
3610         the current match pointer.         the current match pointer.
3611    
3612         When  the  pcre_exec() function is used, the capture_top field contains         When the pcre_exec() or pcre16_exec() is used,  the  capture_top  field
3613         one more than the number of the highest numbered captured substring  so         contains one more than the number of the highest numbered captured sub-
3614         far.  If  no substrings have been captured, the value of capture_top is         string so far. If no substrings have been captured, the value  of  cap-
3615         one. This is always the case when pcre_dfa_exec() is used,  because  it         ture_top  is  one.  This  is always the case when the DFA functions are
3616         does not support captured substrings.         used, because they do not support captured substrings.
3617    
3618         The  capture_last  field  contains the number of the most recently cap-         The capture_last field contains the number of the  most  recently  cap-
3619         tured substring. If no substrings have been captured, its value is  -1.         tured  substring. If no substrings have been captured, its value is -1.
3620         This is always the case when pcre_dfa_exec() is used.         This is always the case for the DFA matching functions.
3621    
3622         The  callout_data  field contains a value that is passed to pcre_exec()         The callout_data field contains a value that is passed  to  a  matching
3623         or pcre_dfa_exec() specifically so that it can be passed back in  call-         function  specifically so that it can be passed back in callouts. It is
3624         outs.  It  is  passed  in the pcre_callout field of the pcre_extra data         passed in the callout_data field of a pcre_extra or  pcre16_extra  data
3625         structure. If no such data was passed, the value of callout_data  in  a         structure.  If  no such data was passed, the value of callout_data in a
3626         pcre_callout  block  is  NULL. There is a description of the pcre_extra         callout block is NULL. There is a description of the pcre_extra  struc-
3627         structure in the pcreapi documentation.         ture in the pcreapi documentation.
3628    
3629         The pattern_position field is present from version 1 of the  pcre_call-         The  pattern_position  field  is  present from version 1 of the callout
3630         out structure. It contains the offset to the next item to be matched in         structure. It contains the offset to the next item to be matched in the
3631         the pattern string.         pattern string.
3632    
3633         The next_item_length field is present from version 1 of the  pcre_call-         The  next_item_length  field  is  present from version 1 of the callout
3634         out structure. It contains the length of the next item to be matched in         structure. It contains the length of the next item to be matched in the
3635         the pattern string. When the callout immediately precedes  an  alterna-         pattern  string.  When  the callout immediately precedes an alternation
3636         tion  bar, a closing parenthesis, or the end of the pattern, the length         bar, a closing parenthesis, or the end of the pattern,  the  length  is
3637         is zero. When the callout precedes an opening parenthesis,  the  length         zero.  When  the callout precedes an opening parenthesis, the length is
3638         is that of the entire subpattern.         that of the entire subpattern.
3639    
3640         The  pattern_position  and next_item_length fields are intended to help         The pattern_position and next_item_length fields are intended  to  help
3641         in distinguishing between different automatic callouts, which all  have         in  distinguishing between different automatic callouts, which all have
3642         the same callout number. However, they are set for all callouts.         the same callout number. However, they are set for all callouts.
3643    
3644           The mark field is present from version 2 of the callout  structure.  In
3645           callouts from pcre_exec() or pcre16_exec() it contains a pointer to the
3646           zero-terminated name of the most recently passed (*MARK), (*PRUNE),  or
3647           (*THEN)  item  in the match, or NULL if no such items have been passed.
3648           Instances of (*PRUNE) or (*THEN) without a name  do  not  obliterate  a
3649           previous  (*MARK).  In  callouts  from  the DFA matching functions this
3650           field always contains NULL.
3651    
3652    
3653  RETURN VALUES  RETURN VALUES
3654    
3655         The  external callout function returns an integer to PCRE. If the value         The external callout function returns an integer to PCRE. If the  value
3656         is zero, matching proceeds as normal. If  the  value  is  greater  than         is  zero,  matching  proceeds  as  normal. If the value is greater than
3657         zero,  matching  fails  at  the current point, but the testing of other         zero, matching fails at the current point, but  the  testing  of  other
3658         matching possibilities goes ahead, just as if a lookahead assertion had         matching possibilities goes ahead, just as if a lookahead assertion had
3659         failed.  If  the  value  is less than zero, the match is abandoned, and         failed. If the value is less than zero, the  match  is  abandoned,  the
3660         pcre_exec() or pcre_dfa_exec() returns the negative value.         matching function returns the negative value.
3661    
3662         Negative  values  should  normally  be   chosen   from   the   set   of         Negative   values   should   normally   be   chosen  from  the  set  of
3663         PCRE_ERROR_xxx values. In particular, PCRE_ERROR_NOMATCH forces a stan-         PCRE_ERROR_xxx values. In particular, PCRE_ERROR_NOMATCH forces a stan-
3664         dard "no  match"  failure.   The  error  number  PCRE_ERROR_CALLOUT  is         dard  "no  match"  failure.   The  error  number  PCRE_ERROR_CALLOUT is