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revision 548 by ph10, Fri Jun 25 14:42:00 2010 UTC revision 1332 by ph10, Tue May 14 14:26:37 2013 UTC
# Line 8  pcretest commands. Line 8  pcretest commands.
8  -----------------------------------------------------------------------------  -----------------------------------------------------------------------------
9    
10    
11  PCRE(3)                                                                PCRE(3)  PCRE(3)                    Library Functions Manual                    PCRE(3)
12    
13    
14    
15  NAME  NAME
16         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
17    
   
18  INTRODUCTION  INTRODUCTION
19    
20         The  PCRE  library is a set of functions that implement regular expres-         The  PCRE  library is a set of functions that implement regular expres-
# Line 25  INTRODUCTION Line 25  INTRODUCTION
25         items, and there is an option for requesting some  minor  changes  that         items, and there is an option for requesting some  minor  changes  that
26         give better JavaScript compatibility.         give better JavaScript compatibility.
27    
28           Starting with release 8.30, it is possible to compile two separate PCRE
29           libraries:  the  original,  which  supports  8-bit  character   strings
30           (including  UTF-8  strings),  and a second library that supports 16-bit
31           character strings (including UTF-16 strings). The build process  allows
32           either  one  or both to be built. The majority of the work to make this
33           possible was done by Zoltan Herczeg.
34    
35           Starting with release 8.32 it is possible to compile a  third  separate
36           PCRE  library  that supports 32-bit character strings (including UTF-32
37           strings). The build process allows any combination of the 8-,  16-  and
38           32-bit  libraries. The work to make this possible was done by Christian
39           Persch.
40    
41           The three libraries contain identical sets of  functions,  except  that
42           the  names  in  the 16-bit library start with pcre16_ instead of pcre_,
43           and the names in the 32-bit  library  start  with  pcre32_  instead  of
44           pcre_.  To avoid over-complication and reduce the documentation mainte-
45           nance load, most of the documentation describes the 8-bit library, with
46           the  differences  for  the  16-bit and 32-bit libraries described sepa-
47           rately in the pcre16 and  pcre32  pages.  References  to  functions  or
48           structures  of  the  form  pcre[16|32]_xxx  should  be  read as meaning
49           "pcre_xxx when using the  8-bit  library,  pcre16_xxx  when  using  the
50           16-bit library, or pcre32_xxx when using the 32-bit library".
51    
52         The  current implementation of PCRE corresponds approximately with Perl         The  current implementation of PCRE corresponds approximately with Perl
53         5.10/5.11, including support for UTF-8 encoded strings and Unicode gen-         5.12, including support for UTF-8/16/32  encoded  strings  and  Unicode
54         eral  category properties. However, UTF-8 and Unicode support has to be         general  category  properties. However, UTF-8/16/32 and Unicode support
55         explicitly enabled; it is not the default. The  Unicode  tables  corre-         has to be explicitly enabled; it is not the default. The Unicode tables
56         spond to Unicode release 5.2.0.         correspond to Unicode release 6.2.0.
57    
58         In  addition to the Perl-compatible matching function, PCRE contains an         In  addition to the Perl-compatible matching function, PCRE contains an
59         alternative 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 63  INTRODUCTION
63    
64         PCRE  is  written  in C and released as a C library. A number of people         PCRE  is  written  in C and released as a C library. A number of people
65         have written wrappers and interfaces of various kinds.  In  particular,         have written wrappers and interfaces of various kinds.  In  particular,
66         Google  Inc.   have  provided  a comprehensive C++ wrapper. This is now         Google  Inc.   have  provided a comprehensive C++ wrapper for the 8-bit
67         included as part of the PCRE distribution. The pcrecpp page has details         library. This is now included as part of  the  PCRE  distribution.  The
68         of  this  interface.  Other  people's contributions can be found in the         pcrecpp  page  has  details of this interface. Other people's contribu-
69         Contrib directory at the primary FTP site, which is:         tions can be found in the Contrib directory at the  primary  FTP  site,
70           which is:
71    
72         ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre         ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre
73    
74         Details of exactly which Perl regular expression features are  and  are         Details  of  exactly which Perl regular expression features are and are
75         not supported by PCRE are given in separate documents. See the pcrepat-         not supported by PCRE are given in separate documents. See the pcrepat-
76         tern and pcrecompat pages. There is a syntax summary in the  pcresyntax         tern  and pcrecompat pages. There is a syntax summary in the pcresyntax
77         page.         page.
78    
79         Some  features  of  PCRE can be included, excluded, or changed when the         Some features of PCRE can be included, excluded, or  changed  when  the
80         library is built. The pcre_config() function makes it  possible  for  a         library  is  built.  The pcre_config() function makes it possible for a
81         client  to  discover  which  features are available. The features them-         client to discover which features are  available.  The  features  them-
82         selves are described in the pcrebuild page. Documentation about  build-         selves  are described in the pcrebuild page. Documentation about build-
83         ing  PCRE  for various operating systems can be found in the README and         ing PCRE for various operating systems can be found in the  README  and
84         NON-UNIX-USE files in the source distribution.         NON-AUTOTOOLS_BUILD files in the source distribution.
85    
86         The library contains a number of undocumented  internal  functions  and         The  libraries contains a number of undocumented internal functions and
87         data  tables  that  are  used by more than one of the exported external         data tables that are used by more than one  of  the  exported  external
88         functions, but which are not intended  for  use  by  external  callers.         functions,  but  which  are  not  intended for use by external callers.
89         Their  names  all begin with "_pcre_", which hopefully will not provoke         Their names all begin with "_pcre_" or "_pcre16_" or "_pcre32_",  which
90         any name clashes. In some environments, it is possible to control which         hopefully  will  not provoke any name clashes. In some environments, it
91         external  symbols  are  exported when a shared library is built, and in         is possible to control which  external  symbols  are  exported  when  a
92         these cases the undocumented symbols are not exported.         shared  library  is  built, and in these cases the undocumented symbols
93           are not exported.
94    
95    
96    SECURITY CONSIDERATIONS
97    
98           If you are using PCRE in a non-UTF application that  permits  users  to
99           supply  arbitrary  patterns  for  compilation, you should be aware of a
100           feature that allows users to turn on UTF support from within a pattern,
101           provided  that  PCRE  was built with UTF support. For example, an 8-bit
102           pattern that begins with "(*UTF8)" or "(*UTF)"  turns  on  UTF-8  mode,
103           which  interprets  patterns and subjects as strings of UTF-8 characters
104           instead of individual 8-bit characters.  This causes both  the  pattern
105           and any data against which it is matched to be checked for UTF-8 valid-
106           ity. If the data string is very long, such a  check  might  use  suffi-
107           ciently  many  resources  as  to cause your application to lose perfor-
108           mance.
109    
110           One  way  of  guarding  against  this  possibility  is   to   use   the
111           pcre_fullinfo()  function  to  check the compiled pattern's options for
112           UTF.  Alternatively, from release 8.33, you can set the  PCRE_NEVER_UTF
113           option  at compile time. This causes an compile time error if a pattern
114           contains a UTF-setting sequence.
115    
116           If your application is one that supports UTF, be  aware  that  validity
117           checking  can  take time. If the same data string is to be matched many
118           times, you can use the PCRE_NO_UTF[8|16|32]_CHECK option for the second
119           and subsequent matches to save redundant checks.
120    
121           Another  way  that  performance can be hit is by running a pattern that
122           has a very large search tree against a string that  will  never  match.
123           Nested  unlimited  repeats in a pattern are a common example. PCRE pro-
124           vides some protection against this: see the PCRE_EXTRA_MATCH_LIMIT fea-
125           ture in the pcreapi page.
126    
127    
128  USER DOCUMENTATION  USER DOCUMENTATION
129    
130         The user documentation for PCRE comprises a number  of  different  sec-         The  user  documentation  for PCRE comprises a number of different sec-
131         tions.  In the "man" format, each of these is a separate "man page". In         tions. In the "man" format, each of these is a separate "man page".  In
132         the HTML format, each is a separate page, linked from the  index  page.         the  HTML  format, each is a separate page, linked from the index page.
133         In  the  plain  text format, all the sections, except the pcredemo sec-         In the plain text format, all the sections, except  the  pcredemo  sec-
134         tion, are concatenated, for ease of searching. The sections are as fol-         tion, are concatenated, for ease of searching. The sections are as fol-
135         lows:         lows:
136    
137           pcre              this document           pcre              this document
138           pcre-config       show PCRE installation configuration information           pcre-config       show PCRE installation configuration information
139             pcre16            details of the 16-bit library
140             pcre32            details of the 32-bit library
141           pcreapi           details of PCRE's native C API           pcreapi           details of PCRE's native C API
142           pcrebuild         options for building PCRE           pcrebuild         building PCRE
143           pcrecallout       details of the callout feature           pcrecallout       details of the callout feature
144           pcrecompat        discussion of Perl compatibility           pcrecompat        discussion of Perl compatibility
145           pcrecpp           details of the C++ wrapper           pcrecpp           details of the C++ wrapper for the 8-bit library
146           pcredemo          a demonstration C program that uses PCRE           pcredemo          a demonstration C program that uses PCRE
147           pcregrep          description of the pcregrep command           pcregrep          description of the pcregrep command (8-bit only)
148             pcrejit           discussion of the just-in-time optimization support
149             pcrelimits        details of size and other limits
150           pcrematching      discussion of the two matching algorithms           pcrematching      discussion of the two matching algorithms
151           pcrepartial       details of the partial matching facility           pcrepartial       details of the partial matching facility
152           pcrepattern       syntax and semantics of supported           pcrepattern       syntax and semantics of supported
153                               regular expressions                               regular expressions
154           pcreperform       discussion of performance issues           pcreperform       discussion of performance issues
155           pcreposix         the POSIX-compatible C API           pcreposix         the POSIX-compatible C API for the 8-bit library
156           pcreprecompile    details of saving and re-using precompiled patterns           pcreprecompile    details of saving and re-using precompiled patterns
157           pcresample        discussion of the pcredemo program           pcresample        discussion of the pcredemo program
158           pcrestack         discussion of stack usage           pcrestack         discussion of stack usage
159           pcresyntax        quick syntax reference           pcresyntax        quick syntax reference
160           pcretest          description of the pcretest testing command           pcretest          description of the pcretest testing command
161             pcreunicode       discussion of Unicode and UTF-8/16/32 support
162    
163         In  addition,  in the "man" and HTML formats, there is a short page for         In addition, in the "man" and HTML formats, there is a short  page  for
164         each C library function, listing its arguments and results.         each C library function, listing its arguments and results.
165    
166    
167  LIMITATIONS  AUTHOR
168    
169         There are some size limitations in PCRE but it is hoped that they  will         Philip Hazel
170         never in practice be relevant.         University Computing Service
171           Cambridge CB2 3QH, England.
172    
173         The  maximum  length of a compiled pattern is 65539 (sic) bytes if PCRE         Putting  an actual email address here seems to have been a spam magnet,
174         is compiled with the default internal linkage size of 2. If you want to         so I've taken it away. If you want to email me, use  my  two  initials,
175         process  regular  expressions  that are truly enormous, you can compile         followed by the two digits 10, at the domain cam.ac.uk.
        PCRE with an internal linkage size of 3 or 4 (see the  README  file  in  
        the  source  distribution and the pcrebuild documentation for details).  
        In these cases the limit is substantially larger.  However,  the  speed  
        of execution is slower.  
176    
        All values in repeating quantifiers must be less than 65536.  
177    
178         There is no limit to the number of parenthesized subpatterns, but there  REVISION
        can be no more than 65535 capturing subpatterns.  
179    
180         The maximum length of name for a named subpattern is 32 characters, and         Last updated: 13 May 2013
181         the maximum number of named subpatterns is 10000.         Copyright (c) 1997-2013 University of Cambridge.
182    ------------------------------------------------------------------------------
183    
184    
185    PCRE(3)                    Library Functions Manual                    PCRE(3)
186    
        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.  
187    
188    
189  UTF-8 AND UNICODE PROPERTY SUPPORT  NAME
190           PCRE - Perl-compatible regular expressions
191    
192         From release 3.3, PCRE has  had  some  support  for  character  strings         #include <pcre.h>
        encoded  in the UTF-8 format. For release 4.0 this was greatly extended  
        to cover most common requirements, and in release 5.0  additional  sup-  
        port for Unicode general category properties was added.  
   
        In  order  process  UTF-8 strings, you must build PCRE to include UTF-8  
        support in the code, and, in addition,  you  must  call  pcre_compile()  
        with  the  PCRE_UTF8  option  flag,  or the pattern must start with the  
        sequence (*UTF8). When either of these is the case,  both  the  pattern  
        and  any  subject  strings  that  are matched against it are treated as  
        UTF-8 strings instead of strings of 1-byte characters.  
193    
        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.  
194    
195         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.  
196    
197     Validity of UTF-8 strings         pcre16 *pcre16_compile(PCRE_SPTR16 pattern, int options,
198                const char **errptr, int *erroffset,
199                const unsigned char *tableptr);
200    
201         When  you  set  the  PCRE_UTF8 flag, the strings passed as patterns and         pcre16 *pcre16_compile2(PCRE_SPTR16 pattern, int options,
202         subjects are (by default) checked for validity on entry to the relevant              int *errorcodeptr,
203         functions.  From  release 7.3 of PCRE, the check is according the rules              const char **errptr, int *erroffset,
204         of RFC 3629, which are themselves derived from the  Unicode  specifica-              const unsigned char *tableptr);
        tion.  Earlier  releases  of PCRE followed the rules of RFC 2279, which  
        allows the full range of 31-bit values (0 to 0x7FFFFFFF).  The  current  
        check allows only values in the range U+0 to U+10FFFF, excluding U+D800  
        to U+DFFF.  
   
        The excluded code points are the "Low Surrogate Area"  of  Unicode,  of  
        which  the Unicode Standard says this: "The Low Surrogate Area does not  
        contain any  character  assignments,  consequently  no  character  code  
        charts or namelists are provided for this area. Surrogates are reserved  
        for use with UTF-16 and then must be used in pairs."  The  code  points  
        that  are  encoded  by  UTF-16  pairs are available as independent code  
        points in the UTF-8 encoding. (In  other  words,  the  whole  surrogate  
        thing is a fudge for UTF-16 which unfortunately messes up UTF-8.)  
   
        If  an  invalid  UTF-8  string  is  passed  to  PCRE,  an  error return  
        (PCRE_ERROR_BADUTF8) is given. In some situations, you may already know  
        that your strings are valid, and therefore want to skip these checks in  
        order to improve performance. If you set the PCRE_NO_UTF8_CHECK flag at  
        compile  time  or at run time, PCRE assumes that the pattern or subject  
        it is given (respectively) contains only valid  UTF-8  codes.  In  this  
        case, it does not diagnose an invalid UTF-8 string.  
   
        If  you  pass  an  invalid UTF-8 string when PCRE_NO_UTF8_CHECK is set,  
        what happens depends on why the string is invalid. If the  string  con-  
        forms to the "old" definition of UTF-8 (RFC 2279), it is processed as a  
        string of characters in the range 0  to  0x7FFFFFFF.  In  other  words,  
        apart from the initial validity test, PCRE (when in UTF-8 mode) handles  
        strings according to the more liberal rules of RFC  2279.  However,  if  
        the  string does not even conform to RFC 2279, the result is undefined.  
        Your program may crash.  
   
        If you want to process strings  of  values  in  the  full  range  0  to  
        0x7FFFFFFF,  encoded in a UTF-8-like manner as per the old RFC, you can  
        set PCRE_NO_UTF8_CHECK to bypass the more restrictive test. However, in  
        this situation, you will have to apply your own validity check.  
   
    General comments about UTF-8 mode  
   
        1.  An  unbraced  hexadecimal  escape sequence (such as \xb3) matches a  
        two-byte UTF-8 character if the value is greater than 127.  
   
        2. Octal numbers up to \777 are recognized, and  match  two-byte  UTF-8  
        characters for values greater than \177.  
   
        3.  Repeat quantifiers apply to complete UTF-8 characters, not to indi-  
        vidual bytes, for example: \x{100}{3}.  
   
        4. The dot metacharacter matches one UTF-8 character instead of a  sin-  
        gle byte.  
   
        5.  The  escape sequence \C can be used to match a single byte in UTF-8  
        mode, but its use can lead to some strange effects.  This  facility  is  
        not available in the alternative matching function, pcre_dfa_exec().  
205    
206         6.  The  character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly         pcre16_extra *pcre16_study(const pcre16 *code, int options,
207         test characters of any code value, but, by default, the characters that              const char **errptr);
        PCRE  recognizes  as digits, spaces, or word characters remain the same  
        set as before, all with values less than 256. This  remains  true  even  
        when  PCRE  is built to include Unicode property support, because to do  
        otherwise would slow down PCRE in many common  cases.  Note  that  this  
        also applies to \b, because it is defined in terms of \w and \W. If you  
        really want to test for a wider sense of, say,  "digit",  you  can  use  
        explicit  Unicode property tests such as \p{Nd}.  Alternatively, if you  
        set the PCRE_UCP option, the way that the  character  escapes  work  is  
        changed  so that Unicode properties are used to determine which charac-  
        ters match. There are more details in the section on generic  character  
        types in the pcrepattern documentation.  
208    
209         7.  Similarly,  characters that match the POSIX named character classes         void pcre16_free_study(pcre16_extra *extra);
        are all low-valued characters, unless the PCRE_UCP option is set.  
210    
211         8. However, the Perl 5.10 horizontal and vertical  whitespace  matching         int pcre16_exec(const pcre16 *code, const pcre16_extra *extra,
212         escapes (\h, \H, \v, and \V) do match all the appropriate Unicode char-              PCRE_SPTR16 subject, int length, int startoffset,
213         acters, whether or not PCRE_UCP is set.              int options, int *ovector, int ovecsize);
214    
215         9. Case-insensitive matching applies only to  characters  whose  values         int pcre16_dfa_exec(const pcre16 *code, const pcre16_extra *extra,
216         are  less than 128, unless PCRE is built with Unicode property support.              PCRE_SPTR16 subject, int length, int startoffset,
217         Even when Unicode property support is available, PCRE  still  uses  its              int options, int *ovector, int ovecsize,
218         own  character  tables when checking the case of low-valued characters,              int *workspace, int wscount);
219         so as not to degrade performance.  The Unicode property information  is  
220         used only for characters with higher values. Even when Unicode property  
221         support is available, PCRE supports case-insensitive matching only when  PCRE 16-BIT API STRING EXTRACTION FUNCTIONS
222         there  is  a  one-to-one  mapping between a letter's cases. There are a  
223         small number of many-to-one mappings in Unicode;  these  are  not  sup-         int pcre16_copy_named_substring(const pcre16 *code,
224         ported by PCRE.              PCRE_SPTR16 subject, int *ovector,
225                int stringcount, PCRE_SPTR16 stringname,
226                PCRE_UCHAR16 *buffer, int buffersize);
227    
228           int pcre16_copy_substring(PCRE_SPTR16 subject, int *ovector,
229                int stringcount, int stringnumber, PCRE_UCHAR16 *buffer,
230                int buffersize);
231    
232           int pcre16_get_named_substring(const pcre16 *code,
233                PCRE_SPTR16 subject, int *ovector,
234                int stringcount, PCRE_SPTR16 stringname,
235                PCRE_SPTR16 *stringptr);
236    
237           int pcre16_get_stringnumber(const pcre16 *code,
238                PCRE_SPTR16 name);
239    
240           int pcre16_get_stringtable_entries(const pcre16 *code,
241                PCRE_SPTR16 name, PCRE_UCHAR16 **first, PCRE_UCHAR16 **last);
242    
243           int pcre16_get_substring(PCRE_SPTR16 subject, int *ovector,
244                int stringcount, int stringnumber,
245                PCRE_SPTR16 *stringptr);
246    
247           int pcre16_get_substring_list(PCRE_SPTR16 subject,
248                int *ovector, int stringcount, PCRE_SPTR16 **listptr);
249    
250           void pcre16_free_substring(PCRE_SPTR16 stringptr);
251    
252           void pcre16_free_substring_list(PCRE_SPTR16 *stringptr);
253    
254    
255    PCRE 16-BIT API AUXILIARY FUNCTIONS
256    
257           pcre16_jit_stack *pcre16_jit_stack_alloc(int startsize, int maxsize);
258    
259           void pcre16_jit_stack_free(pcre16_jit_stack *stack);
260    
261           void pcre16_assign_jit_stack(pcre16_extra *extra,
262                pcre16_jit_callback callback, void *data);
263    
264           const unsigned char *pcre16_maketables(void);
265    
266           int pcre16_fullinfo(const pcre16 *code, const pcre16_extra *extra,
267                int what, void *where);
268    
269           int pcre16_refcount(pcre16 *code, int adjust);
270    
271           int pcre16_config(int what, void *where);
272    
273           const char *pcre16_version(void);
274    
275           int pcre16_pattern_to_host_byte_order(pcre16 *code,
276                pcre16_extra *extra, const unsigned char *tables);
277    
278    
279    PCRE 16-BIT API INDIRECTED FUNCTIONS
280    
281           void *(*pcre16_malloc)(size_t);
282    
283           void (*pcre16_free)(void *);
284    
285           void *(*pcre16_stack_malloc)(size_t);
286    
287           void (*pcre16_stack_free)(void *);
288    
289           int (*pcre16_callout)(pcre16_callout_block *);
290    
291    
292    PCRE 16-BIT API 16-BIT-ONLY FUNCTION
293    
294           int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *output,
295                PCRE_SPTR16 input, int length, int *byte_order,
296                int keep_boms);
297    
298    
299    THE PCRE 16-BIT LIBRARY
300    
301           Starting  with  release  8.30, it is possible to compile a PCRE library
302           that supports 16-bit character strings, including  UTF-16  strings,  as
303           well  as  or instead of the original 8-bit library. The majority of the
304           work to make  this  possible  was  done  by  Zoltan  Herczeg.  The  two
305           libraries contain identical sets of functions, used in exactly the same
306           way. Only the names of the functions and the data types of their  argu-
307           ments  and results are different. To avoid over-complication and reduce
308           the documentation maintenance load,  most  of  the  PCRE  documentation
309           describes  the  8-bit  library,  with only occasional references to the
310           16-bit library. This page describes what is different when you use  the
311           16-bit library.
312    
313           WARNING:  A  single  application can be linked with both libraries, but
314           you must take care when processing any particular pattern to use  func-
315           tions  from  just one library. For example, if you want to study a pat-
316           tern that was compiled with  pcre16_compile(),  you  must  do  so  with
317           pcre16_study(), not pcre_study(), and you must free the study data with
318           pcre16_free_study().
319    
320    
321    THE HEADER FILE
322    
323           There is only one header file, pcre.h. It contains prototypes  for  all
324           the functions in all libraries, as well as definitions of flags, struc-
325           tures, error codes, etc.
326    
327    
328    THE LIBRARY NAME
329    
330           In Unix-like systems, the 16-bit library is called libpcre16,  and  can
331           normally  be  accesss  by adding -lpcre16 to the command for linking an
332           application that uses PCRE.
333    
334    
335    STRING TYPES
336    
337           In the 8-bit library, strings are passed to PCRE library  functions  as
338           vectors  of  bytes  with  the  C  type "char *". In the 16-bit library,
339           strings are passed as vectors of unsigned 16-bit quantities. The  macro
340           PCRE_UCHAR16  specifies  an  appropriate  data type, and PCRE_SPTR16 is
341           defined as "const PCRE_UCHAR16 *". In very  many  environments,  "short
342           int" is a 16-bit data type. When PCRE is built, it defines PCRE_UCHAR16
343           as "unsigned short int", but checks that it really  is  a  16-bit  data
344           type.  If  it is not, the build fails with an error message telling the
345           maintainer to modify the definition appropriately.
346    
347    
348    STRUCTURE TYPES
349    
350           The types of the opaque structures that are used  for  compiled  16-bit
351           patterns  and  JIT stacks are pcre16 and pcre16_jit_stack respectively.
352           The  type  of  the  user-accessible  structure  that  is  returned   by
353           pcre16_study()  is  pcre16_extra, and the type of the structure that is
354           used for passing data to a callout  function  is  pcre16_callout_block.
355           These structures contain the same fields, with the same names, as their
356           8-bit counterparts. The only difference is that pointers  to  character
357           strings are 16-bit instead of 8-bit types.
358    
359    
360    16-BIT FUNCTIONS
361    
362           For  every function in the 8-bit library there is a corresponding func-
363           tion in the 16-bit library with a name that starts with pcre16_ instead
364           of  pcre_.  The  prototypes are listed above. In addition, there is one
365           extra function, pcre16_utf16_to_host_byte_order(). This  is  a  utility
366           function  that converts a UTF-16 character string to host byte order if
367           necessary. The other 16-bit  functions  expect  the  strings  they  are
368           passed to be in host byte order.
369    
370           The input and output arguments of pcre16_utf16_to_host_byte_order() may
371           point to the same address, that is, conversion in place  is  supported.
372           The output buffer must be at least as long as the input.
373    
374           The  length  argument  specifies the number of 16-bit data units in the
375           input string; a negative value specifies a zero-terminated string.
376    
377           If byte_order is NULL, it is assumed that the string starts off in host
378           byte  order. This may be changed by byte-order marks (BOMs) anywhere in
379           the string (commonly as the first character).
380    
381           If byte_order is not NULL, a non-zero value of the integer to which  it
382           points  means  that  the input starts off in host byte order, otherwise
383           the opposite order is assumed. Again, BOMs in  the  string  can  change
384           this. The final byte order is passed back at the end of processing.
385    
386           If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
387           copied into the output string. Otherwise they are discarded.
388    
389           The result of the function is the number of 16-bit  units  placed  into
390           the  output  buffer,  including  the  zero terminator if the string was
391           zero-terminated.
392    
393    
394    SUBJECT STRING OFFSETS
395    
396           The lengths and starting offsets of subject strings must  be  specified
397           in  16-bit  data units, and the offsets within subject strings that are
398           returned by the matching functions are in also 16-bit units rather than
399           bytes.
400    
401    
402    NAMED SUBPATTERNS
403    
404           The  name-to-number translation table that is maintained for named sub-
405           patterns uses 16-bit characters.  The  pcre16_get_stringtable_entries()
406           function returns the length of each entry in the table as the number of
407           16-bit data units.
408    
409    
410    OPTION NAMES
411    
412           There   are   two   new   general   option   names,   PCRE_UTF16    and
413           PCRE_NO_UTF16_CHECK,     which     correspond    to    PCRE_UTF8    and
414           PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
415           define  the  same bits in the options word. There is a discussion about
416           the validity of UTF-16 strings in the pcreunicode page.
417    
418           For the pcre16_config() function there is an  option  PCRE_CONFIG_UTF16
419           that  returns  1  if UTF-16 support is configured, otherwise 0. If this
420           option  is  given  to  pcre_config()  or  pcre32_config(),  or  if  the
421           PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF32  option is given to pcre16_con-
422           fig(), the result is the PCRE_ERROR_BADOPTION error.
423    
424    
425    CHARACTER CODES
426    
427           In 16-bit mode, when  PCRE_UTF16  is  not  set,  character  values  are
428           treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
429           that they can range from 0 to 0xffff instead of 0  to  0xff.  Character
430           types  for characters less than 0xff can therefore be influenced by the
431           locale in the same way as before.  Characters greater  than  0xff  have
432           only one case, and no "type" (such as letter or digit).
433    
434           In  UTF-16  mode,  the  character  code  is  Unicode, in the range 0 to
435           0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
436           because  those  are "surrogate" values that are used in pairs to encode
437           values greater than 0xffff.
438    
439           A UTF-16 string can indicate its endianness by special code knows as  a
440           byte-order mark (BOM). The PCRE functions do not handle this, expecting
441           strings  to  be  in  host  byte  order.  A  utility   function   called
442           pcre16_utf16_to_host_byte_order()  is  provided  to help with this (see
443           above).
444    
445    
446    ERROR NAMES
447    
448           The errors PCRE_ERROR_BADUTF16_OFFSET and PCRE_ERROR_SHORTUTF16  corre-
449           spond  to  their  8-bit  counterparts.  The error PCRE_ERROR_BADMODE is
450           given when a compiled pattern is passed to a  function  that  processes
451           patterns  in  the  other  mode, for example, if a pattern compiled with
452           pcre_compile() is passed to pcre16_exec().
453    
454           There are new error codes whose names  begin  with  PCRE_UTF16_ERR  for
455           invalid  UTF-16  strings,  corresponding to the PCRE_UTF8_ERR codes for
456           UTF-8 strings that are described in the section entitled "Reason  codes
457           for  invalid UTF-8 strings" in the main pcreapi page. The UTF-16 errors
458           are:
459    
460             PCRE_UTF16_ERR1  Missing low surrogate at end of string
461             PCRE_UTF16_ERR2  Invalid low surrogate follows high surrogate
462             PCRE_UTF16_ERR3  Isolated low surrogate
463             PCRE_UTF16_ERR4  Non-character
464    
465    
466    ERROR TEXTS
467    
468           If there is an error while compiling a pattern, the error text that  is
469           passed  back by pcre16_compile() or pcre16_compile2() is still an 8-bit
470           character string, zero-terminated.
471    
472    
473    CALLOUTS
474    
475           The subject and mark fields in the callout block that is  passed  to  a
476           callout function point to 16-bit vectors.
477    
478    
479    TESTING
480    
481           The  pcretest  program continues to operate with 8-bit input and output
482           files, but it can be used for testing the 16-bit library. If it is  run
483           with the command line option -16, patterns and subject strings are con-
484           verted from 8-bit to 16-bit before being passed to PCRE, and the 16-bit
485           library  functions  are used instead of the 8-bit ones. Returned 16-bit
486           strings are converted to 8-bit for output. If both the  8-bit  and  the
487           32-bit libraries were not compiled, pcretest defaults to 16-bit and the
488           -16 option is ignored.
489    
490           When PCRE is being built, the RunTest script that is  called  by  "make
491           check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
492           16-bit and 32-bit libraries has been built, and runs the  tests  appro-
493           priately.
494    
495    
496    NOT SUPPORTED IN 16-BIT MODE
497    
498           Not all the features of the 8-bit library are available with the 16-bit
499           library. The C++ and POSIX wrapper functions  support  only  the  8-bit
500           library, and the pcregrep program is at present 8-bit only.
501    
502    
503  AUTHOR  AUTHOR
# Line 260  AUTHOR Line 506  AUTHOR
506         University Computing Service         University Computing Service
507         Cambridge CB2 3QH, England.         Cambridge CB2 3QH, England.
508    
        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.  
   
509    
510  REVISION  REVISION
511    
512         Last updated: 12 May 2010         Last updated: 12 May 2013
513         Copyright (c) 1997-2010 University of Cambridge.         Copyright (c) 1997-2013 University of Cambridge.
514  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
515    
516    
517    PCRE(3)                    Library Functions Manual                    PCRE(3)
518    
519    
520    
521    NAME
522           PCRE - Perl-compatible regular expressions
523    
524           #include <pcre.h>
525    
526    
527    PCRE 32-BIT API BASIC FUNCTIONS
528    
529           pcre32 *pcre32_compile(PCRE_SPTR32 pattern, int options,
530                const char **errptr, int *erroffset,
531                const unsigned char *tableptr);
532    
533           pcre32 *pcre32_compile2(PCRE_SPTR32 pattern, int options,
534                int *errorcodeptr,
535                const char **errptr, int *erroffset,
536                const unsigned char *tableptr);
537    
538           pcre32_extra *pcre32_study(const pcre32 *code, int options,
539                const char **errptr);
540    
541           void pcre32_free_study(pcre32_extra *extra);
542    
543           int pcre32_exec(const pcre32 *code, const pcre32_extra *extra,
544                PCRE_SPTR32 subject, int length, int startoffset,
545                int options, int *ovector, int ovecsize);
546    
547           int pcre32_dfa_exec(const pcre32 *code, const pcre32_extra *extra,
548                PCRE_SPTR32 subject, int length, int startoffset,
549                int options, int *ovector, int ovecsize,
550                int *workspace, int wscount);
551    
552    
553    PCRE 32-BIT API STRING EXTRACTION FUNCTIONS
554    
555           int pcre32_copy_named_substring(const pcre32 *code,
556                PCRE_SPTR32 subject, int *ovector,
557                int stringcount, PCRE_SPTR32 stringname,
558                PCRE_UCHAR32 *buffer, int buffersize);
559    
560           int pcre32_copy_substring(PCRE_SPTR32 subject, int *ovector,
561                int stringcount, int stringnumber, PCRE_UCHAR32 *buffer,
562                int buffersize);
563    
564           int pcre32_get_named_substring(const pcre32 *code,
565                PCRE_SPTR32 subject, int *ovector,
566                int stringcount, PCRE_SPTR32 stringname,
567                PCRE_SPTR32 *stringptr);
568    
569           int pcre32_get_stringnumber(const pcre32 *code,
570                PCRE_SPTR32 name);
571    
572           int pcre32_get_stringtable_entries(const pcre32 *code,
573                PCRE_SPTR32 name, PCRE_UCHAR32 **first, PCRE_UCHAR32 **last);
574    
575           int pcre32_get_substring(PCRE_SPTR32 subject, int *ovector,
576                int stringcount, int stringnumber,
577                PCRE_SPTR32 *stringptr);
578    
579           int pcre32_get_substring_list(PCRE_SPTR32 subject,
580                int *ovector, int stringcount, PCRE_SPTR32 **listptr);
581    
582           void pcre32_free_substring(PCRE_SPTR32 stringptr);
583    
584           void pcre32_free_substring_list(PCRE_SPTR32 *stringptr);
585    
586    
587    PCRE 32-BIT API AUXILIARY FUNCTIONS
588    
589           pcre32_jit_stack *pcre32_jit_stack_alloc(int startsize, int maxsize);
590    
591           void pcre32_jit_stack_free(pcre32_jit_stack *stack);
592    
593           void pcre32_assign_jit_stack(pcre32_extra *extra,
594                pcre32_jit_callback callback, void *data);
595    
596           const unsigned char *pcre32_maketables(void);
597    
598           int pcre32_fullinfo(const pcre32 *code, const pcre32_extra *extra,
599                int what, void *where);
600    
601           int pcre32_refcount(pcre32 *code, int adjust);
602    
603           int pcre32_config(int what, void *where);
604    
605           const char *pcre32_version(void);
606    
607           int pcre32_pattern_to_host_byte_order(pcre32 *code,
608                pcre32_extra *extra, const unsigned char *tables);
609    
610    
611    PCRE 32-BIT API INDIRECTED FUNCTIONS
612    
613           void *(*pcre32_malloc)(size_t);
614    
615           void (*pcre32_free)(void *);
616    
617           void *(*pcre32_stack_malloc)(size_t);
618    
619           void (*pcre32_stack_free)(void *);
620    
621           int (*pcre32_callout)(pcre32_callout_block *);
622    
623    
624    PCRE 32-BIT API 32-BIT-ONLY FUNCTION
625    
626           int pcre32_utf32_to_host_byte_order(PCRE_UCHAR32 *output,
627                PCRE_SPTR32 input, int length, int *byte_order,
628                int keep_boms);
629    
630    
631    THE PCRE 32-BIT LIBRARY
632    
633           Starting  with  release  8.32, it is possible to compile a PCRE library
634           that supports 32-bit character strings, including  UTF-32  strings,  as
635           well as or instead of the original 8-bit library. This work was done by
636           Christian Persch, based on the work done  by  Zoltan  Herczeg  for  the
637           16-bit  library.  All  three  libraries contain identical sets of func-
638           tions, used in exactly the same way.  Only the names of  the  functions
639           and  the  data  types  of their arguments and results are different. To
640           avoid over-complication and reduce the documentation maintenance  load,
641           most  of  the PCRE documentation describes the 8-bit library, with only
642           occasional references to the 16-bit and  32-bit  libraries.  This  page
643           describes what is different when you use the 32-bit library.
644    
645           WARNING:  A  single  application  can  be linked with all or any of the
646           three libraries, but you must take care when processing any  particular
647           pattern  to  use  functions  from just one library. For example, if you
648           want to study a pattern that was compiled  with  pcre32_compile(),  you
649           must do so with pcre32_study(), not pcre_study(), and you must free the
650           study data with pcre32_free_study().
651    
652    
653    THE HEADER FILE
654    
655           There is only one header file, pcre.h. It contains prototypes  for  all
656           the functions in all libraries, as well as definitions of flags, struc-
657           tures, error codes, etc.
658    
659    
660    THE LIBRARY NAME
661    
662           In Unix-like systems, the 32-bit library is called libpcre32,  and  can
663           normally  be  accesss  by adding -lpcre32 to the command for linking an
664           application that uses PCRE.
665    
666    
667    STRING TYPES
668    
669           In the 8-bit library, strings are passed to PCRE library  functions  as
670           vectors  of  bytes  with  the  C  type "char *". In the 32-bit library,
671           strings are passed as vectors of unsigned 32-bit quantities. The  macro
672           PCRE_UCHAR32  specifies  an  appropriate  data type, and PCRE_SPTR32 is
673           defined as "const PCRE_UCHAR32 *". In very many environments, "unsigned
674           int" is a 32-bit data type. When PCRE is built, it defines PCRE_UCHAR32
675           as "unsigned int", but checks that it really is a 32-bit data type.  If
676           it is not, the build fails with an error message telling the maintainer
677           to modify the definition appropriately.
678    
679    
680    STRUCTURE TYPES
681    
682           The types of the opaque structures that are used  for  compiled  32-bit
683           patterns  and  JIT stacks are pcre32 and pcre32_jit_stack respectively.
684           The  type  of  the  user-accessible  structure  that  is  returned   by
685           pcre32_study()  is  pcre32_extra, and the type of the structure that is
686           used for passing data to a callout  function  is  pcre32_callout_block.
687           These structures contain the same fields, with the same names, as their
688           8-bit counterparts. The only difference is that pointers  to  character
689           strings are 32-bit instead of 8-bit types.
690    
691    
692    32-BIT FUNCTIONS
693    
694           For  every function in the 8-bit library there is a corresponding func-
695           tion in the 32-bit library with a name that starts with pcre32_ instead
696           of  pcre_.  The  prototypes are listed above. In addition, there is one
697           extra function, pcre32_utf32_to_host_byte_order(). This  is  a  utility
698           function  that converts a UTF-32 character string to host byte order if
699           necessary. The other 32-bit  functions  expect  the  strings  they  are
700           passed to be in host byte order.
701    
702           The input and output arguments of pcre32_utf32_to_host_byte_order() may
703           point to the same address, that is, conversion in place  is  supported.
704           The output buffer must be at least as long as the input.
705    
706           The  length  argument  specifies the number of 32-bit data units in the
707           input string; a negative value specifies a zero-terminated string.
708    
709           If byte_order is NULL, it is assumed that the string starts off in host
710           byte  order. This may be changed by byte-order marks (BOMs) anywhere in
711           the string (commonly as the first character).
712    
713           If byte_order is not NULL, a non-zero value of the integer to which  it
714           points  means  that  the input starts off in host byte order, otherwise
715           the opposite order is assumed. Again, BOMs in  the  string  can  change
716           this. The final byte order is passed back at the end of processing.
717    
718           If  keep_boms  is  not  zero,  byte-order  mark characters (0xfeff) are
719           copied into the output string. Otherwise they are discarded.
720    
721           The result of the function is the number of 32-bit  units  placed  into
722           the  output  buffer,  including  the  zero terminator if the string was
723           zero-terminated.
724    
725    
726    SUBJECT STRING OFFSETS
727    
728           The lengths and starting offsets of subject strings must  be  specified
729           in  32-bit  data units, and the offsets within subject strings that are
730           returned by the matching functions are in also 32-bit units rather than
731           bytes.
732    
733    
734    NAMED SUBPATTERNS
735    
736           The  name-to-number translation table that is maintained for named sub-
737           patterns uses 32-bit characters.  The  pcre32_get_stringtable_entries()
738           function returns the length of each entry in the table as the number of
739           32-bit data units.
740    
741    
742    OPTION NAMES
743    
744           There   are   two   new   general   option   names,   PCRE_UTF32    and
745           PCRE_NO_UTF32_CHECK,     which     correspond    to    PCRE_UTF8    and
746           PCRE_NO_UTF8_CHECK in the 8-bit library. In  fact,  these  new  options
747           define  the  same bits in the options word. There is a discussion about
748           the validity of UTF-32 strings in the pcreunicode page.
749    
750           For the pcre32_config() function there is an  option  PCRE_CONFIG_UTF32
751           that  returns  1  if UTF-32 support is configured, otherwise 0. If this
752           option  is  given  to  pcre_config()  or  pcre16_config(),  or  if  the
753           PCRE_CONFIG_UTF8  or  PCRE_CONFIG_UTF16  option is given to pcre32_con-
754           fig(), the result is the PCRE_ERROR_BADOPTION error.
755    
756    
757    CHARACTER CODES
758    
759           In 32-bit mode, when  PCRE_UTF32  is  not  set,  character  values  are
760           treated in the same way as in 8-bit, non UTF-8 mode, except, of course,
761           that they can range from 0 to 0x7fffffff instead of 0 to 0xff.  Charac-
762           ter  types for characters less than 0xff can therefore be influenced by
763           the locale in the same way as before.   Characters  greater  than  0xff
764           have only one case, and no "type" (such as letter or digit).
765    
766           In  UTF-32  mode,  the  character  code  is  Unicode, in the range 0 to
767           0x10ffff, with the exception of values in the range  0xd800  to  0xdfff
768           because those are "surrogate" values that are ill-formed in UTF-32.
769    
770           A  UTF-32 string can indicate its endianness by special code knows as a
771           byte-order mark (BOM). The PCRE functions do not handle this, expecting
772           strings   to   be  in  host  byte  order.  A  utility  function  called
773           pcre32_utf32_to_host_byte_order() is provided to help  with  this  (see
774           above).
775    
776    
777    ERROR NAMES
778    
779           The  error  PCRE_ERROR_BADUTF32  corresponds  to its 8-bit counterpart.
780           The error PCRE_ERROR_BADMODE is given when a compiled pattern is passed
781           to  a  function that processes patterns in the other mode, for example,
782           if a pattern compiled with pcre_compile() is passed to pcre32_exec().
783    
784           There are new error codes whose names  begin  with  PCRE_UTF32_ERR  for
785           invalid  UTF-32  strings,  corresponding to the PCRE_UTF8_ERR codes for
786           UTF-8 strings that are described in the section entitled "Reason  codes
787           for  invalid UTF-8 strings" in the main pcreapi page. The UTF-32 errors
788           are:
789    
790             PCRE_UTF32_ERR1  Surrogate character (range from 0xd800 to 0xdfff)
791             PCRE_UTF32_ERR2  Non-character
792             PCRE_UTF32_ERR3  Character > 0x10ffff
793    
794    
795    ERROR TEXTS
796    
797           If there is an error while compiling a pattern, the error text that  is
798           passed  back by pcre32_compile() or pcre32_compile2() is still an 8-bit
799           character string, zero-terminated.
800    
801    
802    CALLOUTS
803    
804           The subject and mark fields in the callout block that is  passed  to  a
805           callout function point to 32-bit vectors.
806    
807    
808    TESTING
809    
810           The  pcretest  program continues to operate with 8-bit input and output
811           files, but it can be used for testing the 32-bit library. If it is  run
812           with the command line option -32, patterns and subject strings are con-
813           verted from 8-bit to 32-bit before being passed to PCRE, and the 32-bit
814           library  functions  are used instead of the 8-bit ones. Returned 32-bit
815           strings are converted to 8-bit for output. If both the  8-bit  and  the
816           16-bit libraries were not compiled, pcretest defaults to 32-bit and the
817           -32 option is ignored.
818    
819           When PCRE is being built, the RunTest script that is  called  by  "make
820           check"  uses  the  pcretest  -C  option to discover which of the 8-bit,
821           16-bit and 32-bit libraries has been built, and runs the  tests  appro-
822           priately.
823    
824    
825    NOT SUPPORTED IN 32-BIT MODE
826    
827           Not all the features of the 8-bit library are available with the 32-bit
828           library. The C++ and POSIX wrapper functions  support  only  the  8-bit
829           library, and the pcregrep program is at present 8-bit only.
830    
831    
832    AUTHOR
833    
834           Philip Hazel
835           University Computing Service
836           Cambridge CB2 3QH, England.
837    
838    
839    REVISION
840    
841           Last updated: 12 May 2013
842           Copyright (c) 1997-2013 University of Cambridge.
843    ------------------------------------------------------------------------------
844    
845    
846    PCREBUILD(3)               Library Functions Manual               PCREBUILD(3)
847    
 PCREBUILD(3)                                                      PCREBUILD(3)  
848    
849    
850  NAME  NAME
851         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
852    
853    BUILDING PCRE
854    
855           PCRE  is  distributed with a configure script that can be used to build
856           the library in Unix-like environments using the applications  known  as
857           Autotools.   Also  in  the  distribution  are files to support building
858           using CMake instead of configure. The text file README contains general
859           information  about  building  with Autotools (some of which is repeated
860           below), and also has some comments about building on various  operating
861           systems.  There  is  a lot more information about building PCRE without
862           using Autotools (including information about using CMake  and  building
863           "by  hand")  in  the  text file called NON-AUTOTOOLS-BUILD.  You should
864           consult this file as well as the README file if you are building  in  a
865           non-Unix-like environment.
866    
867    
868  PCRE BUILD-TIME OPTIONS  PCRE BUILD-TIME OPTIONS
869    
870         This  document  describes  the  optional  features  of PCRE that can be         The  rest of this document describes the optional features of PCRE that
871         selected when the library is compiled. It assumes use of the  configure         can be selected when the library is compiled. It  assumes  use  of  the
872         script,  where the optional features are selected or deselected by pro-         configure  script,  where  the  optional features are selected or dese-
873         viding options to configure before running the make  command.  However,         lected by providing options to configure before running the  make  com-
874         the  same  options  can be selected in both Unix-like and non-Unix-like         mand.  However,  the same options can be selected in both Unix-like and
875         environments using the GUI facility of cmake-gui if you are using CMake         non-Unix-like environments using the GUI facility of cmake-gui  if  you
876         instead of configure to build PCRE.         are using CMake instead of configure to build PCRE.
877    
878         There  is  a  lot more information about building PCRE in non-Unix-like         If  you  are not using Autotools or CMake, option selection can be done
879         environments in the file called NON_UNIX_USE, which is part of the PCRE         by editing the config.h file, or by passing parameter settings  to  the
880         distribution.  You  should consult this file as well as the README file         compiler, as described in NON-AUTOTOOLS-BUILD.
        if you are building in a non-Unix-like environment.  
881    
882         The complete list of options for configure (which includes the standard         The complete list of options for configure (which includes the standard
883         ones  such  as  the  selection  of  the  installation directory) can be         ones such as the  selection  of  the  installation  directory)  can  be
884         obtained by running         obtained by running
885    
886           ./configure --help           ./configure --help
887    
888         The following sections include  descriptions  of  options  whose  names         The  following  sections  include  descriptions  of options whose names
889         begin with --enable or --disable. These settings specify changes to the         begin with --enable or --disable. These settings specify changes to the
890         defaults for the configure command. Because of the way  that  configure         defaults  for  the configure command. Because of the way that configure
891         works,  --enable  and --disable always come in pairs, so the complemen-         works, --enable and --disable always come in pairs, so  the  complemen-
892         tary option always exists as well, but as it specifies the default,  it         tary  option always exists as well, but as it specifies the default, it
893         is not described.         is not described.
894    
895    
896    BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES
897    
898           By default, a library called libpcre  is  built,  containing  functions
899           that  take  string  arguments  contained in vectors of bytes, either as
900           single-byte characters, or interpreted as UTF-8 strings. You  can  also
901           build  a  separate library, called libpcre16, in which strings are con-
902           tained in vectors of 16-bit data units and interpreted either  as  sin-
903           gle-unit characters or UTF-16 strings, by adding
904    
905             --enable-pcre16
906    
907           to  the  configure  command.  You  can  also build yet another separate
908           library, called libpcre32, in which strings are contained in vectors of
909           32-bit  data  units and interpreted either as single-unit characters or
910           UTF-32 strings, by adding
911    
912             --enable-pcre32
913    
914           to the configure command. If you do not want the 8-bit library, add
915    
916             --disable-pcre8
917    
918           as well. At least one of the three libraries must be built.  Note  that
919           the  C++  and  POSIX  wrappers are for the 8-bit library only, and that
920           pcregrep is an 8-bit program. None of these are  built  if  you  select
921           only the 16-bit or 32-bit libraries.
922    
923    
924    BUILDING SHARED AND STATIC LIBRARIES
925    
926           The  Autotools  PCRE building process uses libtool to build both shared
927           and static libraries by default. You  can  suppress  one  of  these  by
928           adding one of
929    
930             --disable-shared
931             --disable-static
932    
933           to the configure command, as required.
934    
935    
936  C++ SUPPORT  C++ SUPPORT
937    
938         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
939         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,
940         library for PCRE. You can disable this by adding         it  automatically  builds  the C++ wrapper library (which supports only
941           8-bit strings). You can disable this by adding
942    
943           --disable-cpp           --disable-cpp
944    
945         to the configure command.         to the configure command.
946    
947    
948  UTF-8 SUPPORT  UTF-8, UTF-16 AND UTF-32 SUPPORT
949    
950         To build PCRE with support for UTF-8 Unicode character strings, add         To build PCRE with support for UTF Unicode character strings, add
951    
952           --enable-utf8           --enable-utf
953    
954         to  the  configure  command.  Of  itself, this does not make PCRE treat         to the configure command. This setting applies to all three  libraries,
955         strings as UTF-8. As well as compiling PCRE with this option, you  also         adding  support  for  UTF-8 to the 8-bit library, support for UTF-16 to
956         have  have to set the PCRE_UTF8 option when you call the pcre_compile()         the 16-bit library, and  support  for  UTF-32  to  the  to  the  32-bit
957         or pcre_compile2() functions.         library.  There  are no separate options for enabling UTF-8, UTF-16 and
958           UTF-32 independently because that would allow ridiculous settings  such
959         If you set --enable-utf8 when compiling in an EBCDIC environment,  PCRE         as  requesting UTF-16 support while building only the 8-bit library. It
960         expects its input to be either ASCII or UTF-8 (depending on the runtime         is not possible to build one library with UTF support and another with-
961         option). It is not possible to support both EBCDIC and UTF-8  codes  in         out  in the same configuration. (For backwards compatibility, --enable-
962         the  same  version  of  the  library.  Consequently,  --enable-utf8 and         utf8 is a synonym of --enable-utf.)
963    
964           Of itself, this setting does not make  PCRE  treat  strings  as  UTF-8,
965           UTF-16  or UTF-32. As well as compiling PCRE with this option, you also
966           have have to set the PCRE_UTF8, PCRE_UTF16  or  PCRE_UTF32  option  (as
967           appropriate) when you call one of the pattern compiling functions.
968    
969           If  you  set --enable-utf when compiling in an EBCDIC environment, PCRE
970           expects its input to be either ASCII or UTF-8 (depending  on  the  run-
971           time option). It is not possible to support both EBCDIC and UTF-8 codes
972           in the same version of  the  library.  Consequently,  --enable-utf  and
973         --enable-ebcdic are mutually exclusive.         --enable-ebcdic are mutually exclusive.
974    
975    
976  UNICODE CHARACTER PROPERTY SUPPORT  UNICODE CHARACTER PROPERTY SUPPORT
977    
978         UTF-8 support allows PCRE to process character values greater than  255         UTF  support allows the libraries to process character codepoints up to
979         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
980         vide any facilities for accessing the properties of such characters. If         not provide any facilities for accessing the properties of such charac-
981         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,
982         refer to Unicode character properties, you must add         which refer to Unicode character properties, you must add
983    
984           --enable-unicode-properties           --enable-unicode-properties
985    
986         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
987         not explicitly requested it.         not explicitly requested it.
988    
989         Including  Unicode  property  support  adds around 30K of tables to the         Including Unicode property support adds around 30K  of  tables  to  the
990         PCRE library. Only the general category properties such as  Lu  and  Nd         PCRE  library.  Only  the general category properties such as Lu and Nd
991         are supported. Details are given in the pcrepattern documentation.         are supported. Details are given in the pcrepattern documentation.
992    
993    
994    JUST-IN-TIME COMPILER SUPPORT
995    
996           Just-in-time compiler support is included in the build by specifying
997    
998             --enable-jit
999    
1000           This support is available only for certain hardware  architectures.  If
1001           this  option  is  set  for  an unsupported architecture, a compile time
1002           error occurs.  See the pcrejit documentation for a  discussion  of  JIT
1003           usage. When JIT support is enabled, pcregrep automatically makes use of
1004           it, unless you add
1005    
1006             --disable-pcregrep-jit
1007    
1008           to the "configure" command.
1009    
1010    
1011  CODE VALUE OF NEWLINE  CODE VALUE OF NEWLINE
1012    
1013         By  default,  PCRE interprets the linefeed (LF) character as indicating         By default, PCRE interprets the linefeed (LF) character  as  indicating
1014         the end of a line. This is the normal newline  character  on  Unix-like         the  end  of  a line. This is the normal newline character on Unix-like
1015         systems.  You  can compile PCRE to use carriage return (CR) instead, by         systems. You can compile PCRE to use carriage return (CR)  instead,  by
1016         adding         adding
1017    
1018           --enable-newline-is-cr           --enable-newline-is-cr
1019    
1020         to the  configure  command.  There  is  also  a  --enable-newline-is-lf         to  the  configure  command.  There  is  also  a --enable-newline-is-lf
1021         option, which explicitly specifies linefeed as the newline character.         option, which explicitly specifies linefeed as the newline character.
1022    
1023         Alternatively, you can specify that line endings are to be indicated by         Alternatively, you can specify that line endings are to be indicated by
# Line 376  CODE VALUE OF NEWLINE Line 1029  CODE VALUE OF NEWLINE
1029    
1030           --enable-newline-is-anycrlf           --enable-newline-is-anycrlf
1031    
1032         which causes PCRE to recognize any of the three sequences  CR,  LF,  or         which  causes  PCRE  to recognize any of the three sequences CR, LF, or
1033         CRLF as indicating a line ending. Finally, a fifth option, specified by         CRLF as indicating a line ending. Finally, a fifth option, specified by
1034    
1035           --enable-newline-is-any           --enable-newline-is-any
1036    
1037         causes PCRE to recognize any Unicode newline sequence.         causes PCRE to recognize any Unicode newline sequence.
1038    
1039         Whatever  line  ending convention is selected when PCRE is built can be         Whatever line ending convention is selected when PCRE is built  can  be
1040         overridden when the library functions are called. At build time  it  is         overridden  when  the library functions are called. At build time it is
1041         conventional to use the standard for your operating system.         conventional to use the standard for your operating system.
1042    
1043    
1044  WHAT \R MATCHES  WHAT \R MATCHES
1045    
1046         By  default,  the  sequence \R in a pattern matches any Unicode newline         By default, the sequence \R in a pattern matches  any  Unicode  newline
1047         sequence, whatever has been selected as the line  ending  sequence.  If         sequence,  whatever  has  been selected as the line ending sequence. If
1048         you specify         you specify
1049    
1050           --enable-bsr-anycrlf           --enable-bsr-anycrlf
1051    
1052         the  default  is changed so that \R matches only CR, LF, or CRLF. What-         the default is changed so that \R matches only CR, LF, or  CRLF.  What-
1053         ever is selected when PCRE is built can be overridden when the  library         ever  is selected when PCRE is built can be overridden when the library
1054         functions are called.         functions are called.
1055    
1056    
 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.  
   
   
1057  POSIX MALLOC USAGE  POSIX MALLOC USAGE
1058    
1059         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
1060         umentation), additional working storage is  required  for  holding  the         pcreposix  documentation),  additional  working storage is required for
1061         pointers  to capturing substrings, because PCRE requires three integers         holding the pointers to capturing  substrings,  because  PCRE  requires
1062         per substring, whereas the POSIX interface provides only  two.  If  the         three integers per substring, whereas the POSIX interface provides only
1063         number of expected substrings is small, the wrapper function uses space         two. If the number of expected substrings is small, the  wrapper  func-
1064         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-
1065         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
1066         can be changed by adding a setting such as         longer used is 10; it can be changed by adding a setting such as
1067    
1068           --with-posix-malloc-threshold=20           --with-posix-malloc-threshold=20
1069    
# Line 431  POSIX MALLOC USAGE Line 1072  POSIX MALLOC USAGE
1072    
1073  HANDLING VERY LARGE PATTERNS  HANDLING VERY LARGE PATTERNS
1074    
1075         Within a compiled pattern, offset values are used  to  point  from  one         Within  a  compiled  pattern,  offset values are used to point from one
1076         part  to another (for example, from an opening parenthesis to an alter-         part to another (for example, from an opening parenthesis to an  alter-
1077         nation metacharacter). By default, two-byte values are used  for  these         nation  metacharacter).  By default, in the 8-bit and 16-bit libraries,
1078         offsets,  leading  to  a  maximum size for a compiled pattern of around         two-byte values are used for these offsets, leading to a  maximum  size
1079         64K. This is sufficient to handle all but the most  gigantic  patterns.         for  a compiled pattern of around 64K. This is sufficient to handle all
1080         Nevertheless,  some  people do want to process truyl enormous patterns,         but the most gigantic patterns.  Nevertheless, some people do  want  to
1081         so it is possible to compile PCRE to use three-byte or  four-byte  off-         process  truly  enormous patterns, so it is possible to compile PCRE to
1082         sets by adding a setting such as         use three-byte or four-byte offsets by adding a setting such as
1083    
1084           --with-link-size=3           --with-link-size=3
1085    
1086         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
1087         longer offsets slows down the operation of PCRE because it has to  load         16-bit  library,  a  value of 3 is rounded up to 4. In these libraries,
1088         additional bytes when handling them.         using longer offsets slows down the operation of PCRE because it has to
1089           load  additional  data  when  handling them. For the 32-bit library the
1090           value is always 4 and cannot be overridden; the value  of  --with-link-
1091           size is ignored.
1092    
1093    
1094  AVOIDING EXCESSIVE STACK USAGE  AVOIDING EXCESSIVE STACK USAGE
# Line 518  CREATING CHARACTER TABLES AT BUILD TIME Line 1162  CREATING CHARACTER TABLES AT BUILD TIME
1162         to  the  configure  command, the distributed tables are no longer used.         to  the  configure  command, the distributed tables are no longer used.
1163         Instead, a program called dftables is compiled and  run.  This  outputs         Instead, a program called dftables is compiled and  run.  This  outputs
1164         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
1165         C runtime system. (This method of replacing the tables does not work if         C run-time system. (This method of replacing the tables does  not  work
1166         you  are cross compiling, because dftables is run on the local host. If         if  you are cross compiling, because dftables is run on the local host.
1167         you need to create alternative tables when cross  compiling,  you  will         If you need to create alternative tables when cross compiling, you will
1168         have to do so "by hand".)         have to do so "by hand".)
1169    
1170    
# Line 536  USING EBCDIC CODE Line 1180  USING EBCDIC CODE
1180         to the configure command. This setting implies --enable-rebuild-charta-         to the configure command. This setting implies --enable-rebuild-charta-
1181         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
1182         environment (for example,  an  IBM  mainframe  operating  system).  The         environment (for example,  an  IBM  mainframe  operating  system).  The
1183         --enable-ebcdic option is incompatible with --enable-utf8.         --enable-ebcdic option is incompatible with --enable-utf.
1184    
1185           The EBCDIC character that corresponds to an ASCII LF is assumed to have
1186           the value 0x15 by default. However, in some EBCDIC  environments,  0x25
1187           is used. In such an environment you should use
1188    
1189             --enable-ebcdic-nl25
1190    
1191           as well as, or instead of, --enable-ebcdic. The EBCDIC character for CR
1192           has the same value as in ASCII, namely, 0x0d.  Whichever  of  0x15  and
1193           0x25 is not chosen as LF is made to correspond to the Unicode NEL char-
1194           acter (which, in Unicode, is 0x85).
1195    
1196           The options that select newline behaviour, such as --enable-newline-is-
1197           cr, and equivalent run-time options, refer to these character values in
1198           an EBCDIC environment.
1199    
1200    
1201  PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT  PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT
# Line 549  PCREGREP OPTIONS FOR COMPRESSED FILE SUP Line 1208  PCREGREP OPTIONS FOR COMPRESSED FILE SUP
1208           --enable-pcregrep-libbz2           --enable-pcregrep-libbz2
1209    
1210         to the configure command. These options naturally require that the rel-         to the configure command. These options naturally require that the rel-
1211         evant libraries are installed on your system. Configuration  will  fail         evant  libraries  are installed on your system. Configuration will fail
1212         if they are not.         if they are not.
1213    
1214    
1215    PCREGREP BUFFER SIZE
1216    
1217           pcregrep uses an internal buffer to hold a "window" on the file  it  is
1218           scanning, in order to be able to output "before" and "after" lines when
1219           it finds a match. The size of the buffer is controlled by  a  parameter
1220           whose default value is 20K. The buffer itself is three times this size,
1221           but because of the way it is used for holding "before" lines, the long-
1222           est  line  that  is guaranteed to be processable is the parameter size.
1223           You can change the default parameter value by adding, for example,
1224    
1225             --with-pcregrep-bufsize=50K
1226    
1227           to the configure command. The caller of pcregrep can, however, override
1228           this value by specifying a run-time option.
1229    
1230    
1231  PCRETEST OPTION FOR LIBREADLINE SUPPORT  PCRETEST OPTION FOR LIBREADLINE SUPPORT
1232    
1233         If you add         If you add
# Line 584  PCRETEST OPTION FOR LIBREADLINE SUPPORT Line 1259  PCRETEST OPTION FOR LIBREADLINE SUPPORT
1259         immediately before the configure command.         immediately before the configure command.
1260    
1261    
1262    DEBUGGING WITH VALGRIND SUPPORT
1263    
1264           By adding the
1265    
1266             --enable-valgrind
1267    
1268           option  to to the configure command, PCRE will use valgrind annotations
1269           to mark certain memory regions as  unaddressable.  This  allows  it  to
1270           detect invalid memory accesses, and is mostly useful for debugging PCRE
1271           itself.
1272    
1273    
1274    CODE COVERAGE REPORTING
1275    
1276           If your C compiler is gcc, you can build a version  of  PCRE  that  can
1277           generate a code coverage report for its test suite. To enable this, you
1278           must install lcov version 1.6 or above. Then specify
1279    
1280             --enable-coverage
1281    
1282           to the configure command and build PCRE in the usual way.
1283    
1284           Note that using ccache (a caching C compiler) is incompatible with code
1285           coverage  reporting. If you have configured ccache to run automatically
1286           on your system, you must set the environment variable
1287    
1288             CCACHE_DISABLE=1
1289    
1290           before running make to build PCRE, so that ccache is not used.
1291    
1292           When --enable-coverage is used,  the  following  addition  targets  are
1293           added to the Makefile:
1294    
1295             make coverage
1296    
1297           This  creates  a  fresh  coverage report for the PCRE test suite. It is
1298           equivalent to running "make coverage-reset", "make  coverage-baseline",
1299           "make check", and then "make coverage-report".
1300    
1301             make coverage-reset
1302    
1303           This zeroes the coverage counters, but does nothing else.
1304    
1305             make coverage-baseline
1306    
1307           This captures baseline coverage information.
1308    
1309             make coverage-report
1310    
1311           This creates the coverage report.
1312    
1313             make coverage-clean-report
1314    
1315           This  removes the generated coverage report without cleaning the cover-
1316           age data itself.
1317    
1318             make coverage-clean-data
1319    
1320           This removes the captured coverage data without removing  the  coverage
1321           files created at compile time (*.gcno).
1322    
1323             make coverage-clean
1324    
1325           This  cleans all coverage data including the generated coverage report.
1326           For more information about code coverage, see the gcov and  lcov  docu-
1327           mentation.
1328    
1329    
1330  SEE ALSO  SEE ALSO
1331    
1332         pcreapi(3), pcre_config(3).         pcreapi(3), pcre16, pcre32, pcre_config(3).
1333    
1334    
1335  AUTHOR  AUTHOR
# Line 598  AUTHOR Line 1341  AUTHOR
1341    
1342  REVISION  REVISION
1343    
1344         Last updated: 29 September 2009         Last updated: 12 May 2013
1345         Copyright (c) 1997-2009 University of Cambridge.         Copyright (c) 1997-2013 University of Cambridge.
1346  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1347    
1348    
1349    PCREMATCHING(3)            Library Functions Manual            PCREMATCHING(3)
1350    
1351    
 PCREMATCHING(3)                                                PCREMATCHING(3)  
   
1352    
1353  NAME  NAME
1354         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
1355    
   
1356  PCRE MATCHING ALGORITHMS  PCRE MATCHING ALGORITHMS
1357    
1358         This document describes the two different algorithms that are available         This document describes the two different algorithms that are available
1359         in PCRE for matching a compiled regular expression against a given sub-         in PCRE for matching a compiled regular expression against a given sub-
1360         ject  string.  The  "standard"  algorithm  is  the  one provided by the         ject  string.  The  "standard"  algorithm  is  the  one provided by the
1361         pcre_exec() function.  This works in the same was  as  Perl's  matching         pcre_exec(), pcre16_exec() and pcre32_exec() functions. These  work  in
1362         function, and provides a Perl-compatible matching operation.         the  same as as Perl's matching function, and provide a Perl-compatible
1363           matching  operation.   The  just-in-time  (JIT)  optimization  that  is
1364         An  alternative  algorithm is provided by the pcre_dfa_exec() function;         described  in  the pcrejit documentation is compatible with these func-
1365         this operates in a different way, and is not  Perl-compatible.  It  has         tions.
1366         advantages  and disadvantages compared with the standard algorithm, and  
1367         these are described below.         An  alternative  algorithm  is   provided   by   the   pcre_dfa_exec(),
1368           pcre16_dfa_exec()  and  pcre32_dfa_exec()  functions; they operate in a
1369           different way, and are not Perl-compatible. This alternative has advan-
1370           tages and disadvantages compared with the standard algorithm, and these
1371           are described below.
1372    
1373         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
1374         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 1444  THE ALTERNATIVE MATCHING ALGORITHM
1444         represent the different matching possibilities (if there are none,  the         represent the different matching possibilities (if there are none,  the
1445         match  has  failed).   Thus,  if there is more than one possible match,         match  has  failed).   Thus,  if there is more than one possible match,
1446         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-
1447         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
1448         (which is necessarily the shortest) is found.         an option to stop the algorithm after the first match (which is  neces-
1449           sarily the shortest) is found.
1450    
1451         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
1452         subject. If the pattern         subject. If the pattern
1453    
1454           cat(er(pillar)?)           cat(er(pillar)?)?
1455    
1456         is  matched  against the string "the caterpillar catchment", the result         is matched against the string "the caterpillar catchment",  the  result
1457         will be the three strings "cat", "cater", and "caterpillar" that  start         will  be the three strings "caterpillar", "cater", and "cat" that start
1458         at the fourth character of the subject. The algorithm does not automat-         at the fifth character of the subject. The algorithm does not automati-
1459         ically move on to find matches that start at later positions.         cally move on to find matches that start at later positions.
1460    
1461         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
1462         supported by the alternative matching algorithm. They are as follows:         supported by the alternative matching algorithm. They are as follows:
1463    
1464         1.  Because  the  algorithm  finds  all possible matches, the greedy or         1. Because the algorithm finds all  possible  matches,  the  greedy  or
1465         ungreedy nature of repetition quantifiers is not relevant.  Greedy  and         ungreedy  nature  of repetition quantifiers is not relevant. Greedy and
1466         ungreedy quantifiers are treated in exactly the same way. However, pos-         ungreedy quantifiers are treated in exactly the same way. However, pos-
1467         sessive quantifiers can make a difference when what follows could  also         sessive  quantifiers can make a difference when what follows could also
1468         match what is quantified, for example in a pattern like this:         match what is quantified, for example in a pattern like this:
1469    
1470           ^a++\w!           ^a++\w!
1471    
1472         This  pattern matches "aaab!" but not "aaa!", which would be matched by         This pattern matches "aaab!" but not "aaa!", which would be matched  by
1473         a non-possessive quantifier. Similarly, if an atomic group is  present,         a  non-possessive quantifier. Similarly, if an atomic group is present,
1474         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,
1475         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
1476         pattern.         pattern.
1477    
1478         2. When dealing with multiple paths through the tree simultaneously, it         2. When dealing with multiple paths through the tree simultaneously, it
1479         is not straightforward to keep track of  captured  substrings  for  the         is  not  straightforward  to  keep track of captured substrings for the
1480         different  matching  possibilities,  and  PCRE's implementation of this         different matching possibilities, and  PCRE's  implementation  of  this
1481         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-
1482         strings are available.         strings are available.
1483    
1484         3.  Because no substrings are captured, back references within the pat-         3. Because no substrings are captured, back references within the  pat-
1485         tern are not supported, and cause errors if encountered.         tern are not supported, and cause errors if encountered.
1486    
1487         4. For the same reason, conditional expressions that use  a  backrefer-         4.  For  the same reason, conditional expressions that use a backrefer-
1488         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
1489         supported.         supported.
1490    
1491         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
1492         sequence, which resets the start of the match when encountered (but may         sequence, which resets the start of the match when encountered (but may
1493         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
1494         error if encountered.         error if encountered.
1495    
1496         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
1497         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.
1498    
1499         7. The \C escape sequence, which (in the standard algorithm) matches  a         7.  The  \C  escape  sequence, which (in the standard algorithm) always
1500         single  byte, even in UTF-8 mode, is not supported because the alterna-         matches a single data unit, even in UTF-8, UTF-16 or UTF-32  modes,  is
1501         tive algorithm moves through the subject  string  one  character  at  a         not  supported  in these modes, because the alternative algorithm moves
1502         time, for all active paths through the tree.         through the subject string one character (not data unit) at a time, for
1503           all active paths through the tree.
1504    
1505         8.  Except for (*FAIL), the backtracking control verbs such as (*PRUNE)         8.  Except for (*FAIL), the backtracking control verbs such as (*PRUNE)
1506         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 1518  ADVANTAGES OF THE ALTERNATIVE ALGORITHM
1518         things with callouts.         things with callouts.
1519    
1520         2.  Because  the  alternative  algorithm  scans the subject string just         2.  Because  the  alternative  algorithm  scans the subject string just
1521         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-
1522         subject  strings  to  the matching function in several pieces, checking         sible  to  pass  very  long subject strings to the matching function in
1523         for partial matching each time.  The  pcrepartial  documentation  gives         several pieces, checking for partial matching each time. Although it is
1524         details of partial matching.         possible  to  do multi-segment matching using the standard algorithm by
1525           retaining partially matched substrings, it  is  more  complicated.  The
1526           pcrepartial  documentation  gives  details of partial matching and dis-
1527           cusses multi-segment matching.
1528    
1529    
1530  DISADVANTAGES OF THE ALTERNATIVE ALGORITHM  DISADVANTAGES OF THE ALTERNATIVE ALGORITHM
1531    
1532         The alternative algorithm suffers from a number of disadvantages:         The alternative algorithm suffers from a number of disadvantages:
1533    
1534         1.  It  is  substantially  slower  than the standard algorithm. This is         1. It is substantially slower than  the  standard  algorithm.  This  is
1535         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
1536         because it is less susceptible to optimization.         because it is less susceptible to optimization.
1537    
1538         2. Capturing parentheses and back references are not supported.         2. Capturing parentheses and back references are not supported.
# Line 798  AUTHOR Line 1550  AUTHOR
1550    
1551  REVISION  REVISION
1552    
1553         Last updated: 29 September 2009         Last updated: 08 January 2012
1554         Copyright (c) 1997-2009 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
1555  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1556    
1557    
1558    PCREAPI(3)                 Library Functions Manual                 PCREAPI(3)
1559    
1560    
 PCREAPI(3)                                                          PCREAPI(3)  
   
1561    
1562  NAME  NAME
1563         PCRE - Perl-compatible regular expressions         PCRE - Perl-compatible regular expressions
1564    
1565           #include <pcre.h>
1566    
 PCRE NATIVE API  
1567    
1568         #include <pcre.h>  PCRE NATIVE API BASIC FUNCTIONS
1569    
1570         pcre *pcre_compile(const char *pattern, int options,         pcre *pcre_compile(const char *pattern, int options,
1571              const char **errptr, int *erroffset,              const char **errptr, int *erroffset,
# Line 826  PCRE NATIVE API Line 1579  PCRE NATIVE API
1579         pcre_extra *pcre_study(const pcre *code, int options,         pcre_extra *pcre_study(const pcre *code, int options,
1580              const char **errptr);              const char **errptr);
1581    
1582           void pcre_free_study(pcre_extra *extra);
1583    
1584         int pcre_exec(const pcre *code, const pcre_extra *extra,         int pcre_exec(const pcre *code, const pcre_extra *extra,
1585              const char *subject, int length, int startoffset,              const char *subject, int length, int startoffset,
1586              int options, int *ovector, int ovecsize);              int options, int *ovector, int ovecsize);
# Line 835  PCRE NATIVE API Line 1590  PCRE NATIVE API
1590              int options, int *ovector, int ovecsize,              int options, int *ovector, int ovecsize,
1591              int *workspace, int wscount);              int *workspace, int wscount);
1592    
1593    
1594    PCRE NATIVE API STRING EXTRACTION FUNCTIONS
1595    
1596         int pcre_copy_named_substring(const pcre *code,         int pcre_copy_named_substring(const pcre *code,
1597              const char *subject, int *ovector,              const char *subject, int *ovector,
1598              int stringcount, const char *stringname,              int stringcount, const char *stringname,
# Line 866  PCRE NATIVE API Line 1624  PCRE NATIVE API
1624    
1625         void pcre_free_substring_list(const char **stringptr);         void pcre_free_substring_list(const char **stringptr);
1626    
1627    
1628    PCRE NATIVE API AUXILIARY FUNCTIONS
1629    
1630           int pcre_jit_exec(const pcre *code, const pcre_extra *extra,
1631                const char *subject, int length, int startoffset,
1632                int options, int *ovector, int ovecsize,
1633                pcre_jit_stack *jstack);
1634    
1635           pcre_jit_stack *pcre_jit_stack_alloc(int startsize, int maxsize);
1636    
1637           void pcre_jit_stack_free(pcre_jit_stack *stack);
1638    
1639           void pcre_assign_jit_stack(pcre_extra *extra,
1640                pcre_jit_callback callback, void *data);
1641    
1642         const unsigned char *pcre_maketables(void);         const unsigned char *pcre_maketables(void);
1643    
1644         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
1645              int what, void *where);              int what, void *where);
1646    
        int pcre_info(const pcre *code, int *optptr, int *firstcharptr);  
   
1647         int pcre_refcount(pcre *code, int adjust);         int pcre_refcount(pcre *code, int adjust);
1648    
1649         int pcre_config(int what, void *where);         int pcre_config(int what, void *where);
1650    
1651         char *pcre_version(void);         const char *pcre_version(void);
1652    
1653           int pcre_pattern_to_host_byte_order(pcre *code,
1654                pcre_extra *extra, const unsigned char *tables);
1655    
1656    
1657    PCRE NATIVE API INDIRECTED FUNCTIONS
1658    
1659         void *(*pcre_malloc)(size_t);         void *(*pcre_malloc)(size_t);
1660    
# Line 890  PCRE NATIVE API Line 1667  PCRE NATIVE API
1667         int (*pcre_callout)(pcre_callout_block *);         int (*pcre_callout)(pcre_callout_block *);
1668    
1669    
1670    PCRE 8-BIT, 16-BIT, AND 32-BIT LIBRARIES
1671    
1672           As  well  as  support  for  8-bit character strings, PCRE also supports
1673           16-bit strings (from release 8.30) and  32-bit  strings  (from  release
1674           8.32),  by means of two additional libraries. They can be built as well
1675           as, or instead of, the 8-bit library. To avoid too  much  complication,
1676           this  document describes the 8-bit versions of the functions, with only
1677           occasional references to the 16-bit and 32-bit libraries.
1678    
1679           The 16-bit and 32-bit functions operate in the same way as their  8-bit
1680           counterparts;  they  just  use different data types for their arguments
1681           and results, and their names start with pcre16_ or pcre32_  instead  of
1682           pcre_.  For  every  option  that  has  UTF8  in  its name (for example,
1683           PCRE_UTF8), there are corresponding 16-bit and 32-bit names  with  UTF8
1684           replaced by UTF16 or UTF32, respectively. This facility is in fact just
1685           cosmetic; the 16-bit and 32-bit option names define the same  bit  val-
1686           ues.
1687    
1688           References to bytes and UTF-8 in this document should be read as refer-
1689           ences to 16-bit data units and UTF-16 when using the 16-bit library, or
1690           32-bit  data  units  and  UTF-32  when using the 32-bit library, unless
1691           specified otherwise.  More details of the specific differences for  the
1692           16-bit and 32-bit libraries are given in the pcre16 and pcre32 pages.
1693    
1694    
1695  PCRE API OVERVIEW  PCRE API OVERVIEW
1696    
1697         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
1698         are also some wrapper functions that correspond to  the  POSIX  regular         are also some wrapper functions (for the 8-bit library only) that  cor-
1699         expression  API.  These  are  described in the pcreposix documentation.         respond  to  the  POSIX  regular  expression  API, but they do not give
1700         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
1701         distributed with PCRE. It is documented in the pcrecpp page.         documentation.  Both  of these APIs define a set of C function calls. A
1702           C++ wrapper (again for the 8-bit library only) is also distributed with
1703           PCRE. It is documented in the pcrecpp page.
1704    
1705         The  native  API  C  function prototypes are defined in the header file         The  native  API  C  function prototypes are defined in the header file
1706         pcre.h, and on Unix systems the library itself is called  libpcre.   It         pcre.h, and on Unix-like systems the (8-bit) library itself  is  called
1707         can normally be accessed by adding -lpcre to the command for linking an         libpcre.  It  can  normally be accessed by adding -lpcre to the command
1708         application  that  uses  PCRE.  The  header  file  defines  the  macros         for linking an application that uses PCRE. The header file defines  the
1709         PCRE_MAJOR  and  PCRE_MINOR to contain the major and minor release num-         macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release
1710         bers for the library.  Applications can use these  to  include  support         numbers for the library. Applications can use these to include  support
1711         for different releases of PCRE.         for different releases of PCRE.
1712    
1713         In a Windows environment, if you want to statically link an application         In a Windows environment, if you want to statically link an application
# Line 920  PCRE API OVERVIEW Line 1724  PCRE API OVERVIEW
1724         pcredemo documentation, and the pcresample documentation describes  how         pcredemo documentation, and the pcresample documentation describes  how
1725         to compile and run it.         to compile and run it.
1726    
1727           Just-in-time  compiler  support is an optional feature of PCRE that can
1728           be built in appropriate hardware environments. It greatly speeds up the
1729           matching  performance  of  many  patterns.  Simple  programs can easily
1730           request that it be used if available, by  setting  an  option  that  is
1731           ignored  when  it is not relevant. More complicated programs might need
1732           to    make    use    of    the    functions     pcre_jit_stack_alloc(),
1733           pcre_jit_stack_free(),  and pcre_assign_jit_stack() in order to control
1734           the JIT code's memory usage.
1735    
1736           From release 8.32 there is also a direct interface for  JIT  execution,
1737           which  gives  improved performance. The JIT-specific functions are dis-
1738           cussed in the pcrejit documentation.
1739    
1740         A second matching function, pcre_dfa_exec(), which is not Perl-compati-         A second matching function, pcre_dfa_exec(), which is not Perl-compati-
1741         ble, is also provided. This uses a different algorithm for  the  match-         ble,  is  also provided. This uses a different algorithm for the match-
1742         ing.  The  alternative algorithm finds all possible matches (at a given         ing. The alternative algorithm finds all possible matches (at  a  given
1743         point in the subject), and scans the subject just  once  (unless  there         point  in  the  subject), and scans the subject just once (unless there
1744         are  lookbehind  assertions).  However,  this algorithm does not return         are lookbehind assertions). However, this  algorithm  does  not  return
1745         captured substrings. A description of the two matching  algorithms  and         captured  substrings.  A description of the two matching algorithms and
1746         their  advantages  and disadvantages is given in the pcrematching docu-         their advantages and disadvantages is given in the  pcrematching  docu-
1747         mentation.         mentation.
1748    
1749         In addition to the main compiling and  matching  functions,  there  are         In  addition  to  the  main compiling and matching functions, there are
1750         convenience functions for extracting captured substrings from a subject         convenience functions for extracting captured substrings from a subject
1751         string that is matched by pcre_exec(). They are:         string that is matched by pcre_exec(). They are:
1752    
# Line 944  PCRE API OVERVIEW Line 1761  PCRE API OVERVIEW
1761         pcre_free_substring() and pcre_free_substring_list() are also provided,         pcre_free_substring() and pcre_free_substring_list() are also provided,
1762         to free the memory used for extracted strings.         to free the memory used for extracted strings.
1763    
1764         The  function  pcre_maketables()  is  used  to build a set of character         The function pcre_maketables() is used to  build  a  set  of  character
1765         tables  in  the  current  locale   for   passing   to   pcre_compile(),         tables   in   the   current   locale  for  passing  to  pcre_compile(),
1766         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
1767         provided for specialist use.  Most  commonly,  no  special  tables  are         provided  for  specialist  use.  Most  commonly,  no special tables are
1768         passed,  in  which case internal tables that are generated when PCRE is         passed, in which case internal tables that are generated when  PCRE  is
1769         built are used.         built are used.
1770    
1771         The function pcre_fullinfo() is used to find out  information  about  a         The  function  pcre_fullinfo()  is used to find out information about a
1772         compiled  pattern; pcre_info() is an obsolete version that returns only         compiled pattern. The function pcre_version() returns a  pointer  to  a
1773         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.  
1774    
1775         The function pcre_refcount() maintains a  reference  count  in  a  data         The  function  pcre_refcount()  maintains  a  reference count in a data
1776         block  containing  a compiled pattern. This is provided for the benefit         block containing a compiled pattern. This is provided for  the  benefit
1777         of object-oriented applications.         of object-oriented applications.
1778    
1779         The global variables pcre_malloc and pcre_free  initially  contain  the         The  global  variables  pcre_malloc and pcre_free initially contain the
1780         entry  points  of  the  standard malloc() and free() functions, respec-         entry points of the standard malloc()  and  free()  functions,  respec-
1781         tively. PCRE calls the memory management functions via these variables,         tively. PCRE calls the memory management functions via these variables,
1782         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
1783         calls. This should be done before calling any PCRE functions.         calls. This should be done before calling any PCRE functions.
1784    
1785         The global variables pcre_stack_malloc  and  pcre_stack_free  are  also         The  global  variables  pcre_stack_malloc  and pcre_stack_free are also
1786         indirections  to  memory  management functions. These special functions         indirections to memory management functions.  These  special  functions
1787         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
1788         data, instead of recursive function calls, when running the pcre_exec()         data, instead of recursive function calls, when running the pcre_exec()
1789         function. See the pcrebuild documentation for  details  of  how  to  do         function.  See  the  pcrebuild  documentation  for details of how to do
1790         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-
1791         ments that have limited stacks. Because of the greater  use  of  memory         ments  that  have  limited stacks. Because of the greater use of memory
1792         management,  it  runs  more  slowly. Separate functions are provided so         management, it runs more slowly. Separate  functions  are  provided  so
1793         that special-purpose external code can be  used  for  this  case.  When         that  special-purpose  external  code  can  be used for this case. When
1794         used,  these  functions  are always called in a stack-like manner (last         used, these functions are always called in a  stack-like  manner  (last
1795         obtained, first freed), and always for memory blocks of the same  size.         obtained,  first freed), and always for memory blocks of the same size.
1796         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-
1797         mentation.         mentation.
1798    
1799         The global variable pcre_callout initially contains NULL. It can be set         The global variable pcre_callout initially contains NULL. It can be set
1800         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
1801         specified points during a matching operation. Details are given in  the         specified  points during a matching operation. Details are given in the
1802         pcrecallout documentation.         pcrecallout documentation.
1803    
1804    
1805  NEWLINES  NEWLINES
1806    
1807         PCRE  supports five different conventions for indicating line breaks in         PCRE supports five different conventions for indicating line breaks  in
1808         strings: a single CR (carriage return) character, a  single  LF  (line-         strings:  a  single  CR (carriage return) character, a single LF (line-
1809         feed) character, the two-character sequence CRLF, any of the three pre-         feed) character, the two-character sequence CRLF, any of the three pre-
1810         ceding, or any Unicode newline sequence. The Unicode newline  sequences         ceding,  or any Unicode newline sequence. The Unicode newline sequences
1811         are  the  three just mentioned, plus the single characters VT (vertical         are the three just mentioned, plus the single characters  VT  (vertical
1812         tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS  (line         tab, U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line
1813         separator, U+2028), and PS (paragraph separator, U+2029).         separator, U+2028), and PS (paragraph separator, U+2029).
1814    
1815         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
1816         system as its standard newline sequence. When PCRE is built, a  default         system  as its standard newline sequence. When PCRE is built, a default
1817         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-
1818         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
1819         pattern is compiled, or when it is matched.         pattern is compiled, or when it is matched.
1820    
1821         At compile time, the newline convention can be specified by the options         At compile time, the newline convention can be specified by the options
1822         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
1823         the start of the pattern itself; this overrides any other settings. See         the start of the pattern itself; this overrides any other settings. See
1824         the pcrepattern page for details of the special character sequences.         the pcrepattern page for details of the special character sequences.
1825    
1826         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-
1827         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
1828         newline convention affects the handling of  the  dot,  circumflex,  and         newline  convention  affects  the  handling of the dot, circumflex, and
1829         dollar metacharacters, the handling of #-comments in /x mode, and, when         dollar metacharacters, the handling of #-comments in /x mode, and, when
1830         CRLF is a recognized line ending sequence, the match position  advance-         CRLF  is a recognized line ending sequence, the match position advance-
1831         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
1832         section on pcre_exec() options below.         section on pcre_exec() options below.
1833    
1834         The choice of newline convention does not affect the interpretation  of         The  choice of newline convention does not affect the interpretation of
1835         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,
1836         which is controlled in a similar way, but by separate options.         which is controlled in a similar way, but by separate options.
1837    
1838    
1839  MULTITHREADING  MULTITHREADING
1840    
1841         The PCRE functions can be used in  multi-threading  applications,  with         The  PCRE  functions  can be used in multi-threading applications, with
1842         the  proviso  that  the  memory  management  functions  pointed  to  by         the  proviso  that  the  memory  management  functions  pointed  to  by
1843         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
1844         callout function pointed to by pcre_callout, are shared by all threads.         callout function pointed to by pcre_callout, are shared by all threads.
1845    
1846         The  compiled form of a regular expression is not altered during match-         The compiled form of a regular expression is not altered during  match-
1847         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
1848         at once.         at once.
1849    
1850           If the just-in-time optimization feature is being used, it needs  sepa-
1851           rate  memory stack areas for each thread. See the pcrejit documentation
1852           for more details.
1853    
1854    
1855  SAVING PRECOMPILED PATTERNS FOR LATER USE  SAVING PRECOMPILED PATTERNS FOR LATER USE
1856    
1857         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
1858         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
1859         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
1860         pcreprecompile documentation. However, compiling a  regular  expression         pcreprecompile  documentation,  which  includes  a  description  of the
1861         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-
1862         anteed to work and may cause crashes.         lar  expression  with one version of PCRE for use with a different ver-
1863           sion is not guaranteed to work and may cause crashes.
1864    
1865    
1866  CHECKING BUILD-TIME OPTIONS  CHECKING BUILD-TIME OPTIONS
# Line 1054  CHECKING BUILD-TIME OPTIONS Line 1874  CHECKING BUILD-TIME OPTIONS
1874    
1875         The  first  argument  for pcre_config() is an integer, specifying which         The  first  argument  for pcre_config() is an integer, specifying which
1876         information is required; the second argument is a pointer to a variable         information is required; the second argument is a pointer to a variable
1877         into  which  the  information  is  placed. The following information is         into  which  the  information  is placed. The returned value is zero on
1878           success, or the negative error code PCRE_ERROR_BADOPTION if  the  value
1879           in  the  first argument is not recognized. The following information is
1880         available:         available:
1881    
1882           PCRE_CONFIG_UTF8           PCRE_CONFIG_UTF8
1883    
1884         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-
1885         able; otherwise it is set to zero.         able;  otherwise it is set to zero. This value should normally be given
1886           to the 8-bit version of this function, pcre_config(). If it is given to
1887           the   16-bit  or  32-bit  version  of  this  function,  the  result  is
1888           PCRE_ERROR_BADOPTION.
1889    
1890             PCRE_CONFIG_UTF16
1891    
1892           The output is an integer that is set to one if UTF-16 support is avail-
1893           able;  otherwise it is set to zero. This value should normally be given
1894           to the 16-bit version of this function, pcre16_config(). If it is given
1895           to  the  8-bit  or  32-bit  version  of  this  function,  the result is
1896           PCRE_ERROR_BADOPTION.
1897    
1898             PCRE_CONFIG_UTF32
1899    
1900           The output is an integer that is set to one if UTF-32 support is avail-
1901           able;  otherwise it is set to zero. This value should normally be given
1902           to the 32-bit version of this function, pcre32_config(). If it is given
1903           to  the  8-bit  or  16-bit  version  of  this  function,  the result is
1904           PCRE_ERROR_BADOPTION.
1905    
1906           PCRE_CONFIG_UNICODE_PROPERTIES           PCRE_CONFIG_UNICODE_PROPERTIES
1907    
1908         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
1909         character properties is available; otherwise it is set to zero.         character properties is available; otherwise it is set to zero.
1910    
1911             PCRE_CONFIG_JIT
1912    
1913           The output is an integer that is set to one if support for just-in-time
1914           compiling is available; otherwise it is set to zero.
1915    
1916             PCRE_CONFIG_JITTARGET
1917    
1918           The output is a pointer to a zero-terminated "const char *" string.  If
1919           JIT support is available, the string contains the name of the architec-
1920           ture for which the JIT compiler is configured, for example  "x86  32bit
1921           (little  endian  +  unaligned)".  If  JIT support is not available, the
1922           result is NULL.
1923    
1924           PCRE_CONFIG_NEWLINE           PCRE_CONFIG_NEWLINE
1925    
1926         The output is an integer whose value specifies  the  default  character         The output is an integer whose value specifies  the  default  character
1927         sequence  that is recognized as meaning "newline". The four values that         sequence  that  is recognized as meaning "newline". The values that are
1928         are supported are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF,         supported in ASCII/Unicode environments are: 10 for LF, 13 for CR, 3338
1929         and  -1  for  ANY.  Though they are derived from ASCII, the same values         for  CRLF,  -2 for ANYCRLF, and -1 for ANY. In EBCDIC environments, CR,
1930         are returned in EBCDIC environments. The default should normally corre-         ANYCRLF, and ANY yield the same values. However, the value  for  LF  is
1931           normally  21, though some EBCDIC environments use 37. The corresponding
1932           values for CRLF are 3349 and 3365. The default should  normally  corre-
1933         spond to the standard sequence for your operating system.         spond to the standard sequence for your operating system.
1934    
1935           PCRE_CONFIG_BSR           PCRE_CONFIG_BSR
# Line 1087  CHECKING BUILD-TIME OPTIONS Line 1943  CHECKING BUILD-TIME OPTIONS
1943           PCRE_CONFIG_LINK_SIZE           PCRE_CONFIG_LINK_SIZE
1944    
1945         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
1946         internal linkage in compiled regular expressions. The value is 2, 3, or         internal  linkage  in  compiled  regular  expressions.  For  the  8-bit
1947         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
1948         the expense of slower matching. The default value of  2  is  sufficient         is either 2 or 4 and is  still  a  number  of  bytes.  For  the  32-bit
1949         for  all  but  the  most massive patterns, since it allows the compiled         library, the value is either 2 or 4 and is still a number of bytes. The
1950         pattern to be up to 64K in size.         default value of 2 is sufficient for all but the most massive patterns,
1951           since  it  allows  the compiled pattern to be up to 64K in size. Larger
1952           values allow larger regular expressions to be compiled, at the  expense
1953           of slower matching.
1954    
1955           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
1956    
1957         The output is an integer that contains the threshold  above  which  the         The  output  is  an integer that contains the threshold above which the
1958         POSIX  interface  uses malloc() for output vectors. Further details are         POSIX interface uses malloc() for output vectors. Further  details  are
1959         given in the pcreposix documentation.         given in the pcreposix documentation.
1960    
1961           PCRE_CONFIG_MATCH_LIMIT           PCRE_CONFIG_MATCH_LIMIT
1962    
1963         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-
1964         ber  of  internal  matching  function calls in a pcre_exec() execution.         ber of internal matching function calls  in  a  pcre_exec()  execution.
1965         Further details are given with pcre_exec() below.         Further details are given with pcre_exec() below.
1966    
1967           PCRE_CONFIG_MATCH_LIMIT_RECURSION           PCRE_CONFIG_MATCH_LIMIT_RECURSION
1968    
1969         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
1970         of   recursion  when  calling  the  internal  matching  function  in  a         of  recursion  when  calling  the  internal  matching  function  in   a
1971         pcre_exec() execution.  Further  details  are  given  with  pcre_exec()         pcre_exec()  execution.  Further  details  are  given  with pcre_exec()
1972         below.         below.
1973    
1974           PCRE_CONFIG_STACKRECURSE           PCRE_CONFIG_STACKRECURSE
1975    
1976         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
1977         running pcre_exec() is implemented by recursive function calls that use         running pcre_exec() is implemented by recursive function calls that use
1978         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
1979         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
1980         on  the  heap  instead  of  recursive  function  calls.  In  this case,         on the  heap  instead  of  recursive  function  calls.  In  this  case,
1981         pcre_stack_malloc and  pcre_stack_free  are  called  to  manage  memory         pcre_stack_malloc  and  pcre_stack_free  are  called  to  manage memory
1982         blocks on the heap, thus avoiding the use of the stack.         blocks on the heap, thus avoiding the use of the stack.
1983    
1984    
# Line 1136  COMPILING A PATTERN Line 1995  COMPILING A PATTERN
1995    
1996         Either of the functions pcre_compile() or pcre_compile2() can be called         Either of the functions pcre_compile() or pcre_compile2() can be called
1997         to compile a pattern into an internal form. The only difference between         to compile a pattern into an internal form. The only difference between
1998         the  two interfaces is that pcre_compile2() has an additional argument,         the two interfaces is that pcre_compile2() has an additional  argument,
1999         errorcodeptr, via which a numerical error  code  can  be  returned.  To         errorcodeptr,  via  which  a  numerical  error code can be returned. To
2000         avoid  too  much repetition, we refer just to pcre_compile() below, but         avoid too much repetition, we refer just to pcre_compile()  below,  but
2001         the information applies equally to pcre_compile2().         the information applies equally to pcre_compile2().
2002    
2003         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
2004         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
2005         obtained via pcre_malloc is returned. This contains the  compiled  code         obtained  via  pcre_malloc is returned. This contains the compiled code
2006         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
2007         is a typedef for a structure whose contents are not externally defined.         is a typedef for a structure whose contents are not externally defined.
2008         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
2009         longer required.         longer required.
2010    
2011         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
2012         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
2013         fully relocatable, because it may contain a copy of the tableptr  argu-         fully  relocatable, because it may contain a copy of the tableptr argu-
2014         ment, which is an address (see below).         ment, which is an address (see below).
2015    
2016         The options argument contains various bit settings that affect the com-         The options argument contains various bit settings that affect the com-
2017         pilation. It should be zero if no options are required.  The  available         pilation.  It  should be zero if no options are required. The available
2018         options  are  described  below. Some of them (in particular, those that         options are described below. Some of them (in  particular,  those  that
2019         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
2020         unset  from  within  the  pattern  (see the detailed description in the         unset from within the pattern (see  the  detailed  description  in  the
2021         pcrepattern documentation). For those options that can be different  in         pcrepattern  documentation). For those options that can be different in
2022         different  parts  of  the pattern, the contents of the options argument         different parts of the pattern, the contents of  the  options  argument
2023         specifies their settings at the start of compilation and execution. The         specifies their settings at the start of compilation and execution. The
2024         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
2025         the time of matching as well as at compile time.         PCRE_NO_START_OPTIMIZE  options  can  be set at the time of matching as
2026           well as at compile time.
2027    
2028         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,
2029         if  compilation  of  a  pattern fails, pcre_compile() returns NULL, and         if  compilation  of  a  pattern fails, pcre_compile() returns NULL, and
2030         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-
2031         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
2032         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
2033         character  that  was  being  processed when the error was discovered is         the data unit that was being processed when the error was discovered is
2034         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
2035         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
2036         until checks are carried out when the whole pattern has  been  scanned;         or UTF-16 string, the offset is that of the  first  data  unit  of  the
2037         in this case the offset is set to the end of the pattern.         failing character.
2038    
2039           Some  errors are not detected until the whole pattern has been scanned;
2040           in these cases, the offset passed back is the length  of  the  pattern.
2041           Note  that  the  offset is in data units, not characters, even in a UTF
2042           mode. It may sometimes point into the middle of a UTF-8 or UTF-16 char-
2043           acter.
2044    
2045         If  pcre_compile2()  is  used instead of pcre_compile(), and the error-         If  pcre_compile2()  is  used instead of pcre_compile(), and the error-
2046         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 2118  COMPILING A PATTERN
2118    
2119           PCRE_DOTALL           PCRE_DOTALL
2120    
2121         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-
2122         acters,  including  those that indicate newline. Without it, a dot does         acter of any value, including one that indicates a newline. However, it
2123         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.
2124         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
2125         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
2126         newline characters, independent of the setting of this option.         be  changed within a pattern by a (?s) option setting. A negative class
2127           such as [^a] always matches newline characters, independent of the set-
2128           ting of this option.
2129    
2130           PCRE_DUPNAMES           PCRE_DUPNAMES
2131    
# Line 1269  COMPILING A PATTERN Line 2137  COMPILING A PATTERN
2137    
2138           PCRE_EXTENDED           PCRE_EXTENDED
2139    
2140         If  this  bit  is  set,  whitespace  data characters in the pattern are         If  this  bit  is  set,  white space data characters in the pattern are
2141         totally ignored except when escaped or inside a character class. White-         totally ignored except when escaped or inside a character class.  White
2142         space does not include the VT character (code 11). In addition, charac-         space does not include the VT character (code 11). In addition, charac-
2143         ters between an unescaped # outside a character class and the next new-         ters between an unescaped # outside a character class and the next new-
2144         line,  inclusive,  are  also  ignored.  This is equivalent to Perl's /x         line,  inclusive,  are  also  ignored.  This is equivalent to Perl's /x
2145         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-
2146         ting.         ting.
2147    
2148         This  option  makes  it possible to include comments inside complicated         Which  characters  are  interpreted  as  newlines  is controlled by the
2149         patterns.  Note, however, that this applies only  to  data  characters.         options passed to pcre_compile() or by a special sequence at the  start
2150         Whitespace   characters  may  never  appear  within  special  character         of  the  pattern, as described in the section entitled "Newline conven-
2151         sequences in a pattern, for  example  within  the  sequence  (?(  which         tions" in the pcrepattern documentation. Note that the end of this type
2152         introduces a conditional subpattern.         of  comment  is  a  literal  newline  sequence  in  the pattern; escape
2153           sequences that happen to represent a newline do not count.
2154    
2155           This option makes it possible to include  comments  inside  complicated
2156           patterns.   Note,  however,  that this applies only to data characters.
2157           White space  characters  may  never  appear  within  special  character
2158           sequences in a pattern, for example within the sequence (?( that intro-
2159           duces a conditional subpattern.
2160    
2161           PCRE_EXTRA           PCRE_EXTRA
2162    
2163         This  option  was invented in order to turn on additional functionality         This option was invented in order to turn on  additional  functionality
2164         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
2165         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
2166         letter that has no special meaning  causes  an  error,  thus  reserving         letter  that  has  no  special  meaning causes an error, thus reserving
2167         these  combinations  for  future  expansion.  By default, as in Perl, a         these combinations for future expansion. By  default,  as  in  Perl,  a
2168         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
2169         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
2170         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
2171         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
2172         within a pattern.         within a pattern.
2173    
2174           PCRE_FIRSTLINE           PCRE_FIRSTLINE
2175    
2176         If this option is set, an  unanchored  pattern  is  required  to  match         If  this  option  is  set,  an  unanchored pattern is required to match
2177         before  or  at  the  first  newline  in  the subject string, though the         before or at the first  newline  in  the  subject  string,  though  the
2178         matched text may continue over the newline.         matched text may continue over the newline.
2179    
2180           PCRE_JAVASCRIPT_COMPAT           PCRE_JAVASCRIPT_COMPAT
2181    
2182         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
2183         it  is  compatible with JavaScript rather than Perl. The changes are as         it is compatible with JavaScript rather than Perl. The changes  are  as
2184         follows:         follows:
2185    
2186         (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
2187         error,  because this is illegal in JavaScript (by default it is treated         error, because this is illegal in JavaScript (by default it is  treated
2188         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
2189         option is set.         option is set.
2190    
2191         (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
2192         an empty string (by default this causes the current  matching  alterna-         an  empty  string (by default this causes the current matching alterna-
2193         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
2194         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
2195         default, for Perl compatibility.         default, for Perl compatibility.
2196    
2197           (3) \U matches an upper case "U" character; by default \U causes a com-
2198           pile time error (Perl uses \U to upper case subsequent characters).
2199    
2200           (4) \u matches a lower case "u" character unless it is followed by four
2201           hexadecimal digits, in which case the hexadecimal  number  defines  the
2202           code  point  to match. By default, \u causes a compile time error (Perl
2203           uses it to upper case the following character).
2204    
2205           (5) \x matches a lower case "x" character unless it is followed by  two
2206           hexadecimal  digits,  in  which case the hexadecimal number defines the
2207           code point to match. By default, as in Perl, a  hexadecimal  number  is
2208           always expected after \x, but it may have zero, one, or two digits (so,
2209           for example, \xz matches a binary zero character followed by z).
2210    
2211           PCRE_MULTILINE           PCRE_MULTILINE
2212    
2213         By  default,  PCRE  treats the subject string as consisting of a single         By default, for the purposes of matching "start of line"  and  "end  of
2214         line of characters (even if it actually contains newlines). The  "start         line", PCRE treats the subject string as consisting of a single line of
2215         of  line"  metacharacter  (^)  matches only at the start of the string,         characters, even if it actually contains newlines. The "start of  line"
2216         while the "end of line" metacharacter ($) matches only at  the  end  of         metacharacter (^) matches only at the start of the string, and the "end
2217         the string, or before a terminating newline (unless PCRE_DOLLAR_ENDONLY         of line" metacharacter ($) matches only at the end of  the  string,  or
2218         is set). This is the same as Perl.         before  a terminating newline (except when PCRE_DOLLAR_ENDONLY is set).
2219           Note, however, that unless PCRE_DOTALL  is  set,  the  "any  character"
2220           metacharacter  (.)  does not match at a newline. This behaviour (for ^,
2221           $, and dot) is the same as Perl.
2222    
2223         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"
2224         constructs  match  immediately following or immediately before internal         constructs  match  immediately following or immediately before internal
# Line 1336  COMPILING A PATTERN Line 2228  COMPILING A PATTERN
2228         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,
2229         setting PCRE_MULTILINE has no effect.         setting PCRE_MULTILINE has no effect.
2230    
2231             PCRE_NEVER_UTF
2232    
2233           This option locks out interpretation of the pattern as UTF-8 (or UTF-16
2234           or  UTF-32  in the 16-bit and 32-bit libraries). In particular, it pre-
2235           vents the creator of the pattern from switching to  UTF  interpretation
2236           by starting the pattern with (*UTF). This may be useful in applications
2237           that  process  patterns  from  external  sources.  The  combination  of
2238           PCRE_UTF8 and PCRE_NEVER_UTF also causes an error.
2239    
2240           PCRE_NEWLINE_CR           PCRE_NEWLINE_CR
2241           PCRE_NEWLINE_LF           PCRE_NEWLINE_LF
2242           PCRE_NEWLINE_CRLF           PCRE_NEWLINE_CRLF
2243           PCRE_NEWLINE_ANYCRLF           PCRE_NEWLINE_ANYCRLF
2244           PCRE_NEWLINE_ANY           PCRE_NEWLINE_ANY
2245    
2246         These options override the default newline definition that  was  chosen         These  options  override the default newline definition that was chosen
2247         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
2248         newline is indicated by a single character (CR  or  LF,  respectively).         newline  is  indicated  by a single character (CR or LF, respectively).
2249         Setting  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the         Setting PCRE_NEWLINE_CRLF specifies that a newline is indicated by  the
2250         two-character CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF  specifies         two-character  CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF specifies
2251         that any of the three preceding sequences should be recognized. Setting         that any of the three preceding sequences should be recognized. Setting
2252         PCRE_NEWLINE_ANY specifies that any Unicode newline sequence should  be         PCRE_NEWLINE_ANY  specifies that any Unicode newline sequence should be
2253         recognized. The Unicode newline sequences are the three just mentioned,         recognized.
2254         plus the single characters VT (vertical  tab,  U+000B),  FF  (formfeed,  
2255         U+000C),  NEL  (next line, U+0085), LS (line separator, U+2028), and PS         In an ASCII/Unicode environment, the Unicode newline sequences are  the
2256         (paragraph separator, U+2029). The last  two  are  recognized  only  in         three  just  mentioned,  plus  the  single characters VT (vertical tab,
2257         UTF-8 mode.         U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line sep-
2258           arator,  U+2028),  and  PS (paragraph separator, U+2029). For the 8-bit
2259           library, the last two are recognized only in UTF-8 mode.
2260    
2261           When PCRE is compiled to run in an EBCDIC (mainframe) environment,  the
2262           code for CR is 0x0d, the same as ASCII. However, the character code for
2263           LF is normally 0x15, though in some EBCDIC environments 0x25  is  used.
2264           Whichever  of  these  is  not LF is made to correspond to Unicode's NEL
2265           character. EBCDIC codes are all less than 256. For  more  details,  see
2266           the pcrebuild documentation.
2267    
2268         The  newline  setting  in  the  options  word  uses three bits that are         The  newline  setting  in  the  options  word  uses three bits that are
2269         treated as a number, giving eight possibilities. Currently only six are         treated as a number, giving eight possibilities. Currently only six are
# Line 1363  COMPILING A PATTERN Line 2273  COMPILING A PATTERN
2273         PCRE_NEWLINE_CRLF, but other combinations may yield unused numbers  and         PCRE_NEWLINE_CRLF, but other combinations may yield unused numbers  and
2274         cause an error.         cause an error.
2275    
2276         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
2277         a pattern is if PCRE_EXTENDED is set, and  an  unescaped  #  outside  a         when compiling is when PCRE_EXTENDED is set. CR and LF are white  space
2278         character  class  is  encountered.  This indicates a comment that lasts         characters,  and so are ignored in this mode. Also, an unescaped # out-
2279         until after the next line break sequence. In other circumstances,  line         side a character class indicates a comment that lasts until  after  the
2280         break   sequences   are   treated  as  literal  data,  except  that  in         next  line break sequence. In other circumstances, line break sequences
2281         PCRE_EXTENDED mode, both CR and LF are treated as whitespace characters         in patterns are treated as literal data.
        and are therefore ignored.  
2282    
2283         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
2284         is used for pcre_exec() and pcre_dfa_exec(), but it can be overridden.         is used for pcre_exec() and pcre_dfa_exec(), but it can be overridden.
# Line 1377  COMPILING A PATTERN Line 2286  COMPILING A PATTERN
2286           PCRE_NO_AUTO_CAPTURE           PCRE_NO_AUTO_CAPTURE
2287    
2288         If this option is set, it disables the use of numbered capturing paren-         If this option is set, it disables the use of numbered capturing paren-
2289         theses  in the pattern. Any opening parenthesis that is not followed by         theses in the pattern. Any opening parenthesis that is not followed  by
2290         ? behaves as if it were followed by ?: but named parentheses can  still         ?  behaves as if it were followed by ?: but named parentheses can still
2291         be  used  for  capturing  (and  they acquire numbers in the usual way).         be used for capturing (and they acquire  numbers  in  the  usual  way).
2292         There is no equivalent of this option in Perl.         There is no equivalent of this option in Perl.
2293    
2294             PCRE_NO_START_OPTIMIZE
2295    
2296           This  is an option that acts at matching time; that is, it is really an
2297           option for pcre_exec() or pcre_dfa_exec(). If  it  is  set  at  compile
2298           time,  it is remembered with the compiled pattern and assumed at match-
2299           ing time. This is necessary if you want to use JIT  execution,  because
2300           the  JIT  compiler needs to know whether or not this option is set. For
2301           details see the discussion of PCRE_NO_START_OPTIMIZE below.
2302    
2303           PCRE_UCP           PCRE_UCP
2304    
2305         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,
2306         the POSIX character classes. By default, only ASCII characters are rec-         \w,  and  some  of  the POSIX character classes. By default, only ASCII
2307         ognized, but if PCRE_UCP is set, Unicode properties are used instead to         characters are recognized, but if PCRE_UCP is set,  Unicode  properties
2308         classify  characters.  More details are given in the section on generic         are  used instead to classify characters. More details are given in the
2309         character types in the pcrepattern page. If you set PCRE_UCP,  matching         section on generic character types in the pcrepattern page. If you  set
2310         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
2311         only if PCRE has been compiled with Unicode property support.         option is available only if PCRE has been compiled with  Unicode  prop-
2312           erty support.
2313    
2314           PCRE_UNGREEDY           PCRE_UNGREEDY
2315    
2316         This option inverts the "greediness" of the quantifiers  so  that  they         This  option  inverts  the "greediness" of the quantifiers so that they
2317         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
2318         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
2319         within the pattern.         within the pattern.
2320    
2321           PCRE_UTF8           PCRE_UTF8
2322    
2323         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
2324         strings of UTF-8 characters instead of single-byte  character  strings.         strings of UTF-8 characters instead of single-byte strings. However, it
2325         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,
2326         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
2327         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.  
2328    
2329           PCRE_NO_UTF8_CHECK           PCRE_NO_UTF8_CHECK
2330    
2331         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
2332         automatically  checked.  There  is  a  discussion about the validity of         automatically  checked.  There  is  a  discussion about the validity of
2333         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
2334         bytes  is  found,  pcre_compile() returns an error. If you already know         found,  pcre_compile()  returns an error. If you already know that your
2335         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-
2336         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
2337         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
2338         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
2339         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
2340         UTF-8 validity checking of subject strings.         checking  of  subject strings only. If the same string is being matched
2341           many times, the option can be safely set for the second and  subsequent
2342           matchings to improve performance.
2343    
2344    
2345  COMPILATION ERROR CODES  COMPILATION ERROR CODES
2346    
2347         The  following  table  lists  the  error  codes than may be returned by         The  following  table  lists  the  error  codes than may be returned by
2348         pcre_compile2(), along with the error messages that may be returned  by         pcre_compile2(), along with the error messages that may be returned  by
2349         both  compiling functions. As PCRE has developed, some error codes have         both  compiling  functions.  Note  that error messages are always 8-bit
2350         fallen out of use. To avoid confusion, they have not been re-used.         ASCII strings, even in 16-bit or 32-bit mode. As  PCRE  has  developed,
2351           some  error codes have fallen out of use. To avoid confusion, they have
2352           not been re-used.
2353    
2354            0  no error            0  no error
2355            1  \ at end of pattern            1  \ at end of pattern
# Line 1461  COMPILATION ERROR CODES Line 2383  COMPILATION ERROR CODES
2383           29  (?R or (?[+-]digits must be followed by )           29  (?R or (?[+-]digits must be followed by )
2384           30  unknown POSIX class name           30  unknown POSIX class name
2385           31  POSIX collating elements are not supported           31  POSIX collating elements are not supported
2386           32  this version of PCRE is not compiled with PCRE_UTF8 support           32  this version of PCRE is compiled without UTF support
2387           33  [this code is not in use]           33  [this code is not in use]
2388           34  character value in \x{...} sequence is too large           34  character value in \x{...} sequence is too large
2389           35  invalid condition (?(0)           35  invalid condition (?(0)
2390           36  \C not allowed in lookbehind assertion           36  \C not allowed in lookbehind assertion
2391           37  PCRE does not support \L, \l, \N, \U, or \u           37  PCRE does not support \L, \l, \N{name}, \U, or \u
2392           38  number after (?C is > 255           38  number after (?C is > 255
2393           39  closing ) for (?C expected           39  closing ) for (?C expected
2394           40  recursive call could loop indefinitely           40  recursive call could loop indefinitely
2395           41  unrecognized character after (?P           41  unrecognized character after (?P
2396           42  syntax error in subpattern name (missing terminator)           42  syntax error in subpattern name (missing terminator)
2397           43  two named subpatterns have the same name           43  two named subpatterns have the same name
2398           44  invalid UTF-8 string           44  invalid UTF-8 string (specifically UTF-8)
2399           45  support for \P, \p, and \X has not been compiled           45  support for \P, \p, and \X has not been compiled
2400           46  malformed \P or \p sequence           46  malformed \P or \p sequence
2401           47  unknown property name after \P or \p           47  unknown property name after \P or \p
2402           48  subpattern name is too long (maximum 32 characters)           48  subpattern name is too long (maximum 32 characters)
2403           49  too many named subpatterns (maximum 10000)           49  too many named subpatterns (maximum 10000)
2404           50  [this code is not in use]           50  [this code is not in use]
2405           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
2406           52  internal error: overran compiling workspace           52  internal error: overran compiling workspace
2407           53  internal error: previously-checked referenced subpattern           53  internal error: previously-checked referenced subpattern
2408                 not found                 not found
# Line 1491  COMPILATION ERROR CODES Line 2413  COMPILATION ERROR CODES
2413                 name/number or by a plain number                 name/number or by a plain number
2414           58  a numbered reference must not be zero           58  a numbered reference must not be zero
2415           59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)           59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
2416           60  (*VERB) not recognized           60  (*VERB) not recognized or malformed
2417           61  number is too big           61  number is too big
2418           62  subpattern name expected           62  subpattern name expected
2419           63  digit expected after (?+           63  digit expected after (?+
# Line 1499  COMPILATION ERROR CODES Line 2421  COMPILATION ERROR CODES
2421           65  different names for subpatterns of the same number are           65  different names for subpatterns of the same number are
2422                 not allowed                 not allowed
2423           66  (*MARK) must have an argument           66  (*MARK) must have an argument
2424           67  this version of PCRE is not compiled with PCRE_UCP support           67  this version of PCRE is not compiled with Unicode property
2425                   support
2426             68  \c must be followed by an ASCII character
2427             69  \k is not followed by a braced, angle-bracketed, or quoted name
2428             70  internal error: unknown opcode in find_fixedlength()
2429             71  \N is not supported in a class
2430             72  too many forward references
2431             73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
2432             74  invalid UTF-16 string (specifically UTF-16)
2433             75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
2434             76  character value in \u.... sequence is too large
2435             77  invalid UTF-32 string (specifically UTF-32)
2436    
2437         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
2438         values may be used if the limits were changed when PCRE was built.         values may be used if the limits were changed when PCRE was built.
# Line 1524  STUDYING A PATTERN Line 2457  STUDYING A PATTERN
2457         passed; these are described below in the section on matching a pattern.         passed; these are described below in the section on matching a pattern.
2458    
2459         If studying the  pattern  does  not  produce  any  useful  information,         If studying the  pattern  does  not  produce  any  useful  information,
2460         pcre_study() returns NULL. In that circumstance, if the calling program         pcre_study()  returns  NULL  by  default.  In that circumstance, if the
2461         wants  to  pass  any  of   the   other   fields   to   pcre_exec()   or         calling program wants to pass any of the other fields to pcre_exec() or
2462         pcre_dfa_exec(), it must set up its own pcre_extra block.         pcre_dfa_exec(),  it  must set up its own pcre_extra block. However, if
2463           pcre_study() is called  with  the  PCRE_STUDY_EXTRA_NEEDED  option,  it
2464         The  second  argument of pcre_study() contains option bits. At present,         returns a pcre_extra block even if studying did not find any additional
2465         no options are defined, and this argument should always be zero.         information. It may still return NULL, however, if an error  occurs  in
2466           pcre_study().
2467    
2468           The  second  argument  of  pcre_study() contains option bits. There are
2469           three further options in addition to PCRE_STUDY_EXTRA_NEEDED:
2470    
2471             PCRE_STUDY_JIT_COMPILE
2472             PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
2473             PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
2474    
2475           If any of these are set, and the just-in-time  compiler  is  available,
2476           the  pattern  is  further compiled into machine code that executes much
2477           faster than the pcre_exec()  interpretive  matching  function.  If  the
2478           just-in-time  compiler is not available, these options are ignored. All
2479           undefined bits in the options argument must be zero.
2480    
2481           JIT compilation is a heavyweight optimization. It can  take  some  time
2482           for  patterns  to  be analyzed, and for one-off matches and simple pat-
2483           terns the benefit of faster execution might be offset by a much  slower
2484           study time.  Not all patterns can be optimized by the JIT compiler. For
2485           those that cannot be handled, matching automatically falls back to  the
2486           pcre_exec()  interpreter.  For more details, see the pcrejit documenta-
2487           tion.
2488    
2489         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.
2490         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 2493  STUDYING A PATTERN
2493         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
2494         after calling pcre_study(), to be sure that it has run successfully.         after calling pcre_study(), to be sure that it has run successfully.
2495    
2496         This is a typical call to pcre_study():         When  you are finished with a pattern, you can free the memory used for
2497           the study data by calling pcre_free_study(). This function was added to
2498           the  API  for  release  8.20. For earlier versions, the memory could be
2499           freed with pcre_free(), just like the pattern itself. This  will  still
2500           work  in  cases where JIT optimization is not used, but it is advisable
2501           to change to the new function when convenient.
2502    
2503           pcre_extra *pe;         This is a typical way in which pcre_study() is used (except that  in  a
2504           pe = pcre_study(         real application there should be tests for errors):
2505    
2506             int rc;
2507             pcre *re;
2508             pcre_extra *sd;
2509             re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
2510             sd = pcre_study(
2511             re,             /* result of pcre_compile() */             re,             /* result of pcre_compile() */
2512             0,              /* no options exist */             0,              /* no options */
2513             &error);        /* set to NULL or points to a message */             &error);        /* set to NULL or points to a message */
2514             rc = pcre_exec(   /* see below for details of pcre_exec() options */
2515               re, sd, "subject", 7, 0, 0, ovector, 30);
2516             ...
2517             pcre_free_study(sd);
2518             pcre_free(re);
2519    
2520         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
2521         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
2522         does not mean that there are any strings of that length that match, but         does not mean that there are any strings of that length that match, but
2523         it does guarantee that no shorter strings match. The value is  used  by         it does guarantee that no shorter strings match. The value is  used  to
2524         pcre_exec()  and  pcre_dfa_exec()  to  avoid  wasting time by trying to         avoid wasting time by trying to match strings that are shorter than the
2525         match strings that are shorter than the lower bound. You can  find  out         lower bound. You can find out the value in a calling  program  via  the
2526         the value in a calling program via the pcre_fullinfo() function.         pcre_fullinfo() function.
2527    
2528         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
2529         have a single fixed starting character. A bitmap of  possible  starting         have a single fixed starting character. A bitmap of  possible  starting
2530         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
2531         which to start matching.         which to start matching. (In 16-bit mode, the bitmap is used for 16-bit
2532           values  less  than  256.  In 32-bit mode, the bitmap is used for 32-bit
2533           values less than 256.)
2534    
2535           These two optimizations apply to both pcre_exec() and  pcre_dfa_exec(),
2536           and  the  information  is also used by the JIT compiler.  The optimiza-
2537           tions can be disabled by  setting  the  PCRE_NO_START_OPTIMIZE  option.
2538           You  might want to do this if your pattern contains callouts or (*MARK)
2539           and you want to make use of these facilities in  cases  where  matching
2540           fails.
2541    
2542           PCRE_NO_START_OPTIMIZE  can be specified at either compile time or exe-
2543           cution  time.  However,  if   PCRE_NO_START_OPTIMIZE   is   passed   to
2544           pcre_exec(), (that is, after any JIT compilation has happened) JIT exe-
2545           cution is disabled. For JIT execution to work with  PCRE_NO_START_OPTI-
2546           MIZE, the option must be set at compile time.
2547    
2548         The two optimizations just described can be  disabled  by  setting  the         There is a longer discussion of PCRE_NO_START_OPTIMIZE below.
        PCRE_NO_START_OPTIMIZE    option    when    calling    pcre_exec()   or  
        pcre_dfa_exec(). You might want to do this  if  your  pattern  contains  
        callouts,  or  make  use of (*MARK), and you make use of these in cases  
        where matching fails.  See  the  discussion  of  PCRE_NO_START_OPTIMIZE  
        below.  
2549    
2550    
2551  LOCALE SUPPORT  LOCALE SUPPORT
# Line 1631  INFORMATION ABOUT A PATTERN Line 2612  INFORMATION ABOUT A PATTERN
2612              int what, void *where);              int what, void *where);
2613    
2614         The pcre_fullinfo() function returns information about a compiled  pat-         The pcre_fullinfo() function returns information about a compiled  pat-
2615         tern. It replaces the obsolete pcre_info() function, which is neverthe-         tern.  It replaces the pcre_info() function, which was removed from the
2616         less retained for backwards compability (and is documented below).         library at version 8.30, after more than 10 years of obsolescence.
2617    
2618         The first argument for pcre_fullinfo() is a  pointer  to  the  compiled         The first argument for pcre_fullinfo() is a  pointer  to  the  compiled
2619         pattern.  The second argument is the result of pcre_study(), or NULL if         pattern.  The second argument is the result of pcre_study(), or NULL if
# Line 1641  INFORMATION ABOUT A PATTERN Line 2622  INFORMATION ABOUT A PATTERN
2622         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
2623         success, or one of the following negative numbers:         success, or one of the following negative numbers:
2624    
2625           PCRE_ERROR_NULL       the argument code was NULL           PCRE_ERROR_NULL           the argument code was NULL
2626                                 the argument where was NULL                                     the argument where was NULL
2627           PCRE_ERROR_BADMAGIC   the "magic number" was not found           PCRE_ERROR_BADMAGIC       the "magic number" was not found
2628           PCRE_ERROR_BADOPTION  the value of what was invalid           PCRE_ERROR_BADENDIANNESS  the pattern was compiled with different
2629                                       endianness
2630             PCRE_ERROR_BADOPTION      the value of what was invalid
2631             PCRE_ERROR_UNSET          the requested field is not set
2632    
2633         The  "magic  number" is placed at the start of each compiled pattern as         The  "magic  number" is placed at the start of each compiled pattern as
2634         an simple check against passing an arbitrary memory pointer. Here is  a         an simple check against passing an arbitrary memory pointer. The  endi-
2635         typical  call  of pcre_fullinfo(), to obtain the length of the compiled         anness error can occur if a compiled pattern is saved and reloaded on a
2636         pattern:         different host. Here is a typical call of  pcre_fullinfo(),  to  obtain
2637           the length of the compiled pattern:
2638    
2639           int rc;           int rc;
2640           size_t length;           size_t length;
2641           rc = pcre_fullinfo(           rc = pcre_fullinfo(
2642             re,               /* result of pcre_compile() */             re,               /* result of pcre_compile() */
2643             pe,               /* result of pcre_study(), or NULL */             sd,               /* result of pcre_study(), or NULL */
2644             PCRE_INFO_SIZE,   /* what is required */             PCRE_INFO_SIZE,   /* what is required */
2645             &length);         /* where to put the data */             &length);         /* where to put the data */
2646    
2647         The possible values for the third argument are defined in  pcre.h,  and         The  possible  values for the third argument are defined in pcre.h, and
2648         are as follows:         are as follows:
2649    
2650           PCRE_INFO_BACKREFMAX           PCRE_INFO_BACKREFMAX
2651    
2652         Return  the  number  of  the highest back reference in the pattern. The         Return the number of the highest back reference  in  the  pattern.  The
2653         fourth argument should point to an int variable. Zero  is  returned  if         fourth  argument  should  point to an int variable. Zero is returned if
2654         there are no back references.         there are no back references.
2655    
2656           PCRE_INFO_CAPTURECOUNT           PCRE_INFO_CAPTURECOUNT
2657    
2658         Return  the  number of capturing subpatterns in the pattern. The fourth         Return the number of capturing subpatterns in the pattern.  The  fourth
2659         argument should point to an int variable.         argument should point to an int variable.
2660    
2661           PCRE_INFO_DEFAULT_TABLES           PCRE_INFO_DEFAULT_TABLES
2662    
2663         Return a pointer to the internal default character tables within  PCRE.         Return  a pointer to the internal default character tables within PCRE.
2664         The  fourth  argument should point to an unsigned char * variable. This         The fourth argument should point to an unsigned char *  variable.  This
2665         information call is provided for internal use by the pcre_study() func-         information call is provided for internal use by the pcre_study() func-
2666         tion.  External  callers  can  cause PCRE to use its internal tables by         tion. External callers can cause PCRE to use  its  internal  tables  by
2667         passing a NULL table pointer.         passing a NULL table pointer.
2668    
2669           PCRE_INFO_FIRSTBYTE           PCRE_INFO_FIRSTBYTE
2670    
2671         Return information about the first byte of any matched  string,  for  a         Return information about the first data unit of any matched string, for
2672         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
2673         able. (This option used to be called PCRE_INFO_FIRSTCHAR; the old  name         library,  where data units are bytes.) The fourth argument should point
2674         is still recognized for backwards compatibility.)         to an int variable.
2675    
2676           If there is a fixed first value, for example, the  letter  "c"  from  a
2677           pattern  such  as (cat|cow|coyote), its value is returned. In the 8-bit
2678           library, the value is always less than 256. In the 16-bit  library  the
2679           value can be up to 0xffff. In the 32-bit library the value can be up to
2680           0x10ffff.
2681    
2682         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  
2683    
2684         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
2685         branch starts with "^", or         branch starts with "^", or
# Line 1701  INFORMATION ABOUT A PATTERN Line 2691  INFORMATION ABOUT A PATTERN
2691         of  a  subject string or after any newline within the string. Otherwise         of  a  subject string or after any newline within the string. Otherwise
2692         -2 is returned. For anchored patterns, -2 is returned.         -2 is returned. For anchored patterns, -2 is returned.
2693    
2694           Since for the 32-bit library using the non-UTF-32 mode,  this  function
2695           is  unable to return the full 32-bit range of the character, this value
2696           is   deprecated;   instead   the   PCRE_INFO_FIRSTCHARACTERFLAGS    and
2697           PCRE_INFO_FIRSTCHARACTER values should be used.
2698    
2699           PCRE_INFO_FIRSTTABLE           PCRE_INFO_FIRSTTABLE
2700    
2701         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
2702         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
2703         matching string, a pointer to the table is returned. Otherwise NULL  is         in  any  matching string, a pointer to the table is returned. Otherwise
2704         returned.  The fourth argument should point to an unsigned char * vari-         NULL is returned. The fourth argument should point to an unsigned  char
2705         able.         * variable.
2706    
2707           PCRE_INFO_HASCRORLF           PCRE_INFO_HASCRORLF
2708    
2709         Return 1 if the pattern contains any explicit  matches  for  CR  or  LF         Return  1  if  the  pattern  contains any explicit matches for CR or LF
2710         characters,  otherwise  0.  The  fourth argument should point to an int         characters, otherwise 0. The fourth argument should  point  to  an  int
2711         variable. An explicit match is either a literal CR or LF character,  or         variable.  An explicit match is either a literal CR or LF character, or
2712         \r or \n.         \r or \n.
2713    
2714           PCRE_INFO_JCHANGED           PCRE_INFO_JCHANGED
2715    
2716         Return  1  if  the (?J) or (?-J) option setting is used in the pattern,         Return 1 if the (?J) or (?-J) option setting is used  in  the  pattern,
2717         otherwise 0. The fourth argument should point to an int variable.  (?J)         otherwise  0. The fourth argument should point to an int variable. (?J)
2718         and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.         and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
2719    
2720             PCRE_INFO_JIT
2721    
2722           Return 1 if the pattern was studied with one of the  JIT  options,  and
2723           just-in-time compiling was successful. The fourth argument should point
2724           to an int variable. A return value of 0 means that JIT support  is  not
2725           available  in this version of PCRE, or that the pattern was not studied
2726           with a JIT option, or that the JIT compiler could not handle this  par-
2727           ticular  pattern. See the pcrejit documentation for details of what can
2728           and cannot be handled.
2729    
2730             PCRE_INFO_JITSIZE
2731    
2732           If the pattern was successfully studied with a JIT option,  return  the
2733           size  of the JIT compiled code, otherwise return zero. The fourth argu-
2734           ment should point to a size_t variable.
2735    
2736           PCRE_INFO_LASTLITERAL           PCRE_INFO_LASTLITERAL
2737    
2738         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
2739         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
2740         recorded. The fourth argument should point to an int variable. If there         recorded. The fourth argument should point to an int variable. If there
2741         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
2742         byte  is  recorded only if it follows something of variable length. For         value is recorded only if it follows something of variable length.  For
2743         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
2744         /^a\dz\d/ the returned value is -1.         /^a\dz\d/ the returned value is -1.
2745    
2746           Since for the 32-bit library using the non-UTF-32 mode,  this  function
2747           is  unable to return the full 32-bit range of the character, this value
2748           is   deprecated;   instead    the    PCRE_INFO_REQUIREDCHARFLAGS    and
2749           PCRE_INFO_REQUIREDCHAR values should be used.
2750    
2751             PCRE_INFO_MATCHLIMIT
2752    
2753           If  the  pattern  set  a  match  limit by including an item of the form
2754           (*LIMIT_MATCH=nnnn) at the start, the value  is  returned.  The  fourth
2755           argument  should  point to an unsigned 32-bit integer. If no such value
2756           has  been  set,  the  call  to  pcre_fullinfo()   returns   the   error
2757           PCRE_ERROR_UNSET.
2758    
2759             PCRE_INFO_MAXLOOKBEHIND
2760    
2761           Return  the  number  of  characters  (NB not data units) in the longest
2762           lookbehind assertion in the pattern. This information  is  useful  when
2763           doing  multi-segment  matching  using  the partial matching facilities.
2764           Note that the simple assertions \b and \B require a one-character look-
2765           behind.  \A  also  registers a one-character lookbehind, though it does
2766           not actually inspect the previous character. This is to ensure that  at
2767           least one character from the old segment is retained when a new segment
2768           is processed. Otherwise, if there are no lookbehinds in the pattern, \A
2769           might match incorrectly at the start of a new segment.
2770    
2771           PCRE_INFO_MINLENGTH           PCRE_INFO_MINLENGTH
2772    
2773         If  the  pattern  was studied and a minimum length for matching subject         If  the  pattern  was studied and a minimum length for matching subject
2774         strings was computed, its value is  returned.  Otherwise  the  returned         strings was computed, its value is  returned.  Otherwise  the  returned
2775         value  is  -1. The value is a number of characters, not bytes (this may         value is -1. The value is a number of characters, which in UTF mode may
2776         be relevant in UTF-8 mode). The fourth argument should point to an  int         be different from the number of data units. The fourth argument  should
2777         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
2778         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
2779         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
2780           least that long.
2781    
2782           PCRE_INFO_NAMECOUNT           PCRE_INFO_NAMECOUNT
2783           PCRE_INFO_NAMEENTRYSIZE           PCRE_INFO_NAMEENTRYSIZE
2784           PCRE_INFO_NAMETABLE           PCRE_INFO_NAMETABLE
2785    
2786         PCRE  supports the use of named as well as numbered capturing parenthe-         PCRE supports the use of named as well as numbered capturing  parenthe-
2787         ses. The names are just an additional way of identifying the  parenthe-         ses.  The names are just an additional way of identifying the parenthe-
2788         ses, which still acquire numbers. Several convenience functions such as         ses, which still acquire numbers. Several convenience functions such as
2789         pcre_get_named_substring() are provided for  extracting  captured  sub-         pcre_get_named_substring()  are  provided  for extracting captured sub-
2790         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
2791         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
2792         pointers in the output vector (described with pcre_exec() below). To do         pointers in the output vector (described with pcre_exec() below). To do
2793         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
2794         described by these three values.         described by these three values.
2795    
2796         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
2797         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size
2798         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
2799         depends on the length of the longest name. PCRE_INFO_NAMETABLE  returns         depends  on the length of the longest name. PCRE_INFO_NAMETABLE returns
2800         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
2801         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-
2802         sis,  most  significant byte first. The rest of the entry is the corre-         ber of the capturing parenthesis, most significant byte first.  In  the
2803         sponding name, zero terminated.         16-bit  library,  the pointer points to 16-bit data units, the first of
2804           which contains the parenthesis  number.  In  the  32-bit  library,  the
2805           pointer  points  to  32-bit data units, the first of which contains the
2806           parenthesis number. The rest of the entry is  the  corresponding  name,
2807           zero terminated.
2808    
2809         The names are in alphabetical order. Duplicate names may appear if  (?|         The  names are in alphabetical order. Duplicate names may appear if (?|
2810         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
2811         the section on duplicate subpattern numbers in  the  pcrepattern  page.         the  section  on  duplicate subpattern numbers in the pcrepattern page.
2812         Duplicate  names  for  subpatterns with different numbers are permitted         Duplicate names for subpatterns with different  numbers  are  permitted
2813         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
2814         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-
2815         tern. In the absence of (?| this is the  order  of  increasing  number;         tern.  In  the  absence  of (?| this is the order of increasing number;
2816         when (?| is used this is not necessarily the case because later subpat-         when (?| is used this is not necessarily the case because later subpat-
2817         terns may have lower numbers.         terns may have lower numbers.
2818    
2819         As a simple example of the name/number table,  consider  the  following         As  a  simple  example of the name/number table, consider the following
2820         pattern  (assume  PCRE_EXTENDED is set, so white space - including new-         pattern after compilation by the 8-bit library (assume PCRE_EXTENDED is
2821         lines - is ignored):         set, so white space - including newlines - is ignored):
2822    
2823           (?<date> (?<year>(\d\d)?\d\d) -           (?<date> (?<year>(\d\d)?\d\d) -
2824           (?<month>\d\d) - (?<day>\d\d) )           (?<month>\d\d) - (?<day>\d\d) )
2825    
2826         There are four named subpatterns, so the table has  four  entries,  and         There  are  four  named subpatterns, so the table has four entries, and
2827         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,
2828         with non-printing bytes shows in hexadecimal, and undefined bytes shown         with non-printing bytes shows in hexadecimal, and undefined bytes shown
2829         as ??:         as ??:
2830    
# Line 1792  INFORMATION ABOUT A PATTERN Line 2833  INFORMATION ABOUT A PATTERN
2833           00 04 m  o  n  t  h  00           00 04 m  o  n  t  h  00
2834           00 02 y  e  a  r  00 ??           00 02 y  e  a  r  00 ??
2835    
2836         When  writing  code  to  extract  data from named subpatterns using the         When writing code to extract data  from  named  subpatterns  using  the
2837         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
2838         to be different for each compiled pattern.         to be different for each compiled pattern.
2839    
2840           PCRE_INFO_OKPARTIAL           PCRE_INFO_OKPARTIAL
2841    
2842         Return  1  if  the  pattern  can  be  used  for  partial  matching with         Return 1  if  the  pattern  can  be  used  for  partial  matching  with
2843         pcre_exec(), otherwise 0. The fourth argument should point  to  an  int         pcre_exec(),  otherwise  0.  The fourth argument should point to an int
2844         variable.  From  release  8.00,  this  always  returns  1,  because the         variable. From  release  8.00,  this  always  returns  1,  because  the
2845         restrictions that previously applied  to  partial  matching  have  been         restrictions  that  previously  applied  to  partial matching have been
2846         lifted.  The  pcrepartial documentation gives details of partial match-         lifted. The pcrepartial documentation gives details of  partial  match-
2847         ing.         ing.
2848    
2849           PCRE_INFO_OPTIONS           PCRE_INFO_OPTIONS
2850    
2851         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
2852         fourth  argument  should  point to an unsigned long int variable. These         fourth argument should point to an unsigned long  int  variable.  These
2853         option bits are those specified in the call to pcre_compile(), modified         option bits are those specified in the call to pcre_compile(), modified
2854         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
2855         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
2856         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
2857         the PCRE_EXTENDED option, the result is PCRE_CASELESS,  PCRE_MULTILINE,         the  PCRE_EXTENDED option, the result is PCRE_CASELESS, PCRE_MULTILINE,
2858         and PCRE_EXTENDED.         and PCRE_EXTENDED.
2859    
2860         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
2861         alternatives begin with one of the following:         alternatives begin with one of the following:
2862    
2863           ^     unless PCRE_MULTILINE is set           ^     unless PCRE_MULTILINE is set
# Line 1828  INFORMATION ABOUT A PATTERN Line 2869  INFORMATION ABOUT A PATTERN
2869         For such patterns, the PCRE_ANCHORED bit is set in the options returned         For such patterns, the PCRE_ANCHORED bit is set in the options returned
2870         by pcre_fullinfo().         by pcre_fullinfo().
2871    
2872             PCRE_INFO_RECURSIONLIMIT
2873    
2874           If the pattern set a recursion limit by including an item of  the  form
2875           (*LIMIT_RECURSION=nnnn) at the start, the value is returned. The fourth
2876           argument should point to an unsigned 32-bit integer. If no  such  value
2877           has   been   set,   the  call  to  pcre_fullinfo()  returns  the  error
2878           PCRE_ERROR_UNSET.
2879    
2880           PCRE_INFO_SIZE           PCRE_INFO_SIZE
2881    
2882         Return  the  size  of the compiled pattern, that is, the value that was         Return the size of  the  compiled  pattern  in  bytes  (for  all  three
2883         passed as the argument to pcre_malloc() when PCRE was getting memory in         libraries). The fourth argument should point to a size_t variable. This
2884         which to place the compiled data. The fourth argument should point to a         value does not include the size of the pcre structure that is  returned
2885         size_t variable.         by  pcre_compile().  The  value  that  is  passed  as  the  argument to
2886           pcre_malloc() when pcre_compile() is getting memory in which  to  place
2887           the compiled data is the value returned by this option plus the size of
2888           the pcre structure. Studying a compiled pattern, with or  without  JIT,
2889           does not alter the value returned by this option.
2890    
2891           PCRE_INFO_STUDYSIZE           PCRE_INFO_STUDYSIZE
2892    
2893         Return the size of the data block pointed to by the study_data field in         Return  the  size  in bytes (for all three libraries) of the data block
2894         a  pcre_extra  block.  That  is,  it  is  the  value that was passed to         pointed to by the study_data field in a pcre_extra block. If pcre_extra
2895         pcre_malloc() when PCRE was getting memory into which to place the data         is  NULL, or there is no study data, zero is returned. The fourth argu-
2896         created  by  pcre_study().  If pcre_extra is NULL, or there is no study         ment should point to a size_t variable. The study_data field is set  by
2897         data, zero is returned. The fourth argument should point  to  a  size_t         pcre_study() to record information that will speed up matching (see the
2898           section entitled  "Studying  a  pattern"  above).  The  format  of  the
2899           study_data  block is private, but its length is made available via this
2900           option so that it can be saved and  restored  (see  the  pcreprecompile
2901           documentation for details).
2902    
2903             PCRE_INFO_FIRSTCHARACTERFLAGS
2904    
2905           Return information about the first data unit of any matched string, for
2906           a non-anchored pattern. The fourth argument  should  point  to  an  int
2907         variable.         variable.
2908    
2909           If  there  is  a  fixed first value, for example, the letter "c" from a
2910           pattern such as (cat|cow|coyote), 1  is  returned,  and  the  character
2911           value can be retrieved using PCRE_INFO_FIRSTCHARACTER.
2912    
2913           If there is no fixed first value, and if either
2914    
2915           (a)  the pattern was compiled with the PCRE_MULTILINE option, and every
2916           branch starts with "^", or
2917    
2918           (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2919           set (if it were set, the pattern would be anchored),
2920    
2921           2 is returned, indicating that the pattern matches only at the start of
2922           a subject string or after any newline within the string. Otherwise 0 is
2923           returned. For anchored patterns, 0 is returned.
2924    
2925             PCRE_INFO_FIRSTCHARACTER
2926    
2927           Return  the  fixed  first character value, if PCRE_INFO_FIRSTCHARACTER-
2928           FLAGS returned 1; otherwise returns 0. The fourth argument should point
2929           to an uint_t variable.
2930    
2931           In  the 8-bit library, the value is always less than 256. In the 16-bit
2932           library the value can be up to 0xffff. In the 32-bit library in  UTF-32
2933           mode  the  value  can  be up to 0x10ffff, and up to 0xffffffff when not
2934           using UTF-32 mode.
2935    
2936           If there is no fixed first value, and if either
2937    
2938           (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
2939           branch starts with "^", or
2940    
2941           (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2942           set (if it were set, the pattern would be anchored),
2943    
2944  OBSOLETE INFO FUNCTION         -1 is returned, indicating that the pattern matches only at  the  start
2945           of  a  subject string or after any newline within the string. Otherwise
2946           -2 is returned. For anchored patterns, -2 is returned.
2947    
2948         int pcre_info(const pcre *code, int *optptr, int *firstcharptr);           PCRE_INFO_REQUIREDCHARFLAGS
2949    
2950         The  pcre_info()  function is now obsolete because its interface is too         Returns 1 if there is a rightmost literal data unit that must exist  in
2951         restrictive to return all the available data about a compiled  pattern.         any matched string, other than at its start. The fourth argument should
2952         New   programs   should  use  pcre_fullinfo()  instead.  The  yield  of         point to an int variable. If there is no such value, 0 is returned.  If
2953         pcre_info() is the number of capturing subpatterns, or one of the  fol-         returning  1,  the  character  value  itself  can  be  retrieved  using
2954         lowing negative numbers:         PCRE_INFO_REQUIREDCHAR.
2955    
2956           PCRE_ERROR_NULL       the argument code was NULL         For anchored patterns, a last literal value is recorded only if it fol-
2957           PCRE_ERROR_BADMAGIC   the "magic number" was not found         lows  something  of  variable  length.  For  example,  for  the pattern
2958           /^a\d+z\d+/  the   returned   value   1   (with   "z"   returned   from
2959         If  the  optptr  argument is not NULL, a copy of the options with which         PCRE_INFO_REQUIREDCHAR), but for /^a\dz\d/ the returned value is 0.
2960         the pattern was compiled is placed in the integer  it  points  to  (see  
2961         PCRE_INFO_OPTIONS above).           PCRE_INFO_REQUIREDCHAR
2962    
2963         If  the  pattern  is  not anchored and the firstcharptr argument is not         Return  the value of the rightmost literal data unit that must exist in
2964         NULL, it is used to pass back information about the first character  of         any matched string, other than at its start, if such a value  has  been
2965         any matched string (see PCRE_INFO_FIRSTBYTE above).         recorded.  The fourth argument should point to an uint32_t variable. If
2966           there is no such value, 0 is returned.
2967    
2968    
2969  REFERENCE COUNTS  REFERENCE COUNTS
2970    
2971         int pcre_refcount(pcre *code, int adjust);         int pcre_refcount(pcre *code, int adjust);
2972    
2973         The  pcre_refcount()  function is used to maintain a reference count in         The pcre_refcount() function is used to maintain a reference  count  in
2974         the data block that contains a compiled pattern. It is provided for the         the data block that contains a compiled pattern. It is provided for the
2975         benefit  of  applications  that  operate  in an object-oriented manner,         benefit of applications that  operate  in  an  object-oriented  manner,
2976         where different parts of the application may be using the same compiled         where different parts of the application may be using the same compiled
2977         pattern, but you want to free the block when they are all done.         pattern, but you want to free the block when they are all done.
2978    
2979         When a pattern is compiled, the reference count field is initialized to         When a pattern is compiled, the reference count field is initialized to
2980         zero.  It is changed only by calling this function, whose action is  to         zero.   It is changed only by calling this function, whose action is to
2981         add  the  adjust  value  (which may be positive or negative) to it. The         add the adjust value (which may be positive or  negative)  to  it.  The
2982         yield of the function is the new value. However, the value of the count         yield of the function is the new value. However, the value of the count
2983         is  constrained to lie between 0 and 65535, inclusive. If the new value         is constrained to lie between 0 and 65535, inclusive. If the new  value
2984         is outside these limits, it is forced to the appropriate limit value.         is outside these limits, it is forced to the appropriate limit value.
2985    
2986         Except when it is zero, the reference count is not correctly  preserved         Except  when it is zero, the reference count is not correctly preserved
2987         if  a  pattern  is  compiled on one host and then transferred to a host         if a pattern is compiled on one host and then  transferred  to  a  host
2988         whose byte-order is different. (This seems a highly unlikely scenario.)         whose byte-order is different. (This seems a highly unlikely scenario.)
2989    
2990    
# Line 1895  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2994  MATCHING A PATTERN: THE TRADITIONAL FUNC
2994              const char *subject, int length, int startoffset,              const char *subject, int length, int startoffset,
2995              int options, int *ovector, int ovecsize);              int options, int *ovector, int ovecsize);
2996    
2997         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
2998         compiled  pattern, which is passed in the code argument. If the pattern         compiled pattern, which is passed in the code argument. If the  pattern
2999         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
3000         argument.  This  function is the main matching facility of the library,         argument. You can call pcre_exec() with the same code and  extra  argu-
3001         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
3002         an  alternative matching function, which is described below in the sec-         strings with the same pattern.
3003         tion about the pcre_dfa_exec() function.  
3004           This function is the main matching facility  of  the  library,  and  it
3005           operates  in  a  Perl-like  manner. For specialist use there is also an
3006           alternative matching function, which is described below in the  section
3007           about the pcre_dfa_exec() function.
3008    
3009         In most applications, the pattern will have been compiled (and  option-         In  most applications, the pattern will have been compiled (and option-
3010         ally  studied)  in the same process that calls pcre_exec(). However, it         ally studied) in the same process that calls pcre_exec().  However,  it
3011         is possible to save compiled patterns and study data, and then use them         is possible to save compiled patterns and study data, and then use them
3012         later  in  different processes, possibly even on different hosts. For a         later in different processes, possibly even on different hosts.  For  a
3013         discussion about this, see the pcreprecompile documentation.         discussion about this, see the pcreprecompile documentation.
3014    
3015         Here is an example of a simple call to pcre_exec():         Here is an example of a simple call to pcre_exec():
# Line 1925  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3028  MATCHING A PATTERN: THE TRADITIONAL FUNC
3028    
3029     Extra data for pcre_exec()     Extra data for pcre_exec()
3030    
3031         If the extra argument is not NULL, it must point to a  pcre_extra  data         If  the  extra argument is not NULL, it must point to a pcre_extra data
3032         block.  The pcre_study() function returns such a block (when it doesn't         block. The pcre_study() function returns such a block (when it  doesn't
3033         return NULL), but you can also create one for yourself, and pass  addi-         return  NULL), but you can also create one for yourself, and pass addi-
3034         tional  information  in it. The pcre_extra block contains the following         tional information in it. The pcre_extra block contains  the  following
3035         fields (not necessarily in this order):         fields (not necessarily in this order):
3036    
3037           unsigned long int flags;           unsigned long int flags;
3038           void *study_data;           void *study_data;
3039             void *executable_jit;
3040           unsigned long int match_limit;           unsigned long int match_limit;
3041           unsigned long int match_limit_recursion;           unsigned long int match_limit_recursion;
3042           void *callout_data;           void *callout_data;
3043           const unsigned char *tables;           const unsigned char *tables;
3044           unsigned char **mark;           unsigned char **mark;
3045    
3046         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
3047         are set. The flag bits are:         "PCRE_UCHAR16 **".
3048    
3049           PCRE_EXTRA_STUDY_DATA         In the 32-bit version of  this  structure,  the  mark  field  has  type
3050           "PCRE_UCHAR32 **".
3051    
3052           The  flags  field is used to specify which of the other fields are set.
3053           The flag bits are:
3054    
3055             PCRE_EXTRA_CALLOUT_DATA
3056             PCRE_EXTRA_EXECUTABLE_JIT
3057             PCRE_EXTRA_MARK
3058           PCRE_EXTRA_MATCH_LIMIT           PCRE_EXTRA_MATCH_LIMIT
3059           PCRE_EXTRA_MATCH_LIMIT_RECURSION           PCRE_EXTRA_MATCH_LIMIT_RECURSION
3060           PCRE_EXTRA_CALLOUT_DATA           PCRE_EXTRA_STUDY_DATA
3061           PCRE_EXTRA_TABLES           PCRE_EXTRA_TABLES
          PCRE_EXTRA_MARK  
3062    
3063         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-
3064         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
3065         the appropriate flag bit. You should not set this yourself, but you may         returned by pcre_study(), together with the appropriate flag bits.  You
3066         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
3067         flag bits.         other fields and their corresponding flag bits.
3068    
3069         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
3070         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
3071         match,  but  which  have  a very large number of possibilities in their         match, but which have a very large number  of  possibilities  in  their
3072         search trees. The classic example is a pattern that uses nested  unlim-         search  trees. The classic example is a pattern that uses nested unlim-
3073         ited repeats.         ited repeats.
3074    
3075         Internally,  PCRE uses a function called match() which it calls repeat-         Internally, pcre_exec() uses a function called match(), which it  calls
3076         edly (sometimes recursively). The limit set by match_limit  is  imposed         repeatedly  (sometimes  recursively).  The  limit set by match_limit is
3077         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,
3078         has the effect of limiting the amount of  backtracking  that  can  take         which  has  the  effect of limiting the amount of backtracking that can
3079         place. For patterns that are not anchored, the count restarts from zero         take place. For patterns that are not anchored, the count restarts from
3080         for each position in the subject string.         zero for each position in the subject string.
3081    
3082           When pcre_exec() is called with a pattern that was successfully studied
3083           with a JIT option, the way that the matching is  executed  is  entirely
3084           different.  However, there is still the possibility of runaway matching
3085           that goes on for a very long time, and so the match_limit value is also
3086           used in this case (but in a different way) to limit how long the match-
3087           ing can continue.
3088    
3089         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
3090         default  default  is 10 million, which handles all but the most extreme         default  default  is 10 million, which handles all but the most extreme
# Line 1975  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3093  MATCHING A PATTERN: THE TRADITIONAL FUNC
3093         PCRE_EXTRA_MATCH_LIMIT is set in the  flags  field.  If  the  limit  is         PCRE_EXTRA_MATCH_LIMIT is set in the  flags  field.  If  the  limit  is
3094         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
3095    
3096         The  match_limit_recursion field is similar to match_limit, but instead         A  value  for  the  match  limit may also be supplied by an item at the
3097           start of a pattern of the form
3098    
3099             (*LIMIT_MATCH=d)
3100    
3101           where d is a decimal number. However, such a setting is ignored  unless
3102           d  is  less  than  the limit set by the caller of pcre_exec() or, if no
3103           such limit is set, less than the default.
3104    
3105           The match_limit_recursion field is similar to match_limit, but  instead
3106         of limiting the total number of times that match() is called, it limits         of limiting the total number of times that match() is called, it limits
3107         the  depth  of  recursion. The recursion depth is a smaller number than         the depth of recursion. The recursion depth is a  smaller  number  than
3108         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-
3109         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.
3110    
3111         Limiting  the  recursion  depth  limits the amount of stack that can be         Limiting the recursion depth limits the amount of  machine  stack  that
3112         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
3113         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
3114           limit  is not relevant, and is ignored, when matching is done using JIT
3115         The  default  value  for  match_limit_recursion can be set when PCRE is         compiled code.
3116         built; the default default  is  the  same  value  as  the  default  for  
3117         match_limit.  You can override the default by suppling pcre_exec() with         The default value for match_limit_recursion can be  set  when  PCRE  is
3118         a  pcre_extra  block  in  which  match_limit_recursion  is   set,   and         built;  the  default  default  is  the  same  value  as the default for
3119         PCRE_EXTRA_MATCH_LIMIT_RECURSION  is  set  in  the  flags field. If the         match_limit. You can override the default by suppling pcre_exec()  with
3120           a   pcre_extra   block  in  which  match_limit_recursion  is  set,  and
3121           PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in  the  flags  field.  If  the
3122         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.
3123    
3124           A  value for the recursion limit may also be supplied by an item at the
3125           start of a pattern of the form
3126    
3127             (*LIMIT_RECURSION=d)
3128    
3129           where d is a decimal number. However, such a setting is ignored  unless
3130           d  is  less  than  the limit set by the caller of pcre_exec() or, if no
3131           such limit is set, less than the default.
3132    
3133         The callout_data field is used in conjunction with the  "callout"  fea-         The callout_data field is used in conjunction with the  "callout"  fea-
3134         ture, and is described in the pcrecallout documentation.         ture, and is described in the pcrecallout documentation.
3135    
# Line 2007  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3145  MATCHING A PATTERN: THE TRADITIONAL FUNC
3145         tion for a discussion of saving compiled patterns for later use.         tion for a discussion of saving compiled patterns for later use.
3146    
3147         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
3148         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-
3149         tracking control verbs such as (*MARK:NAME), and the execution ends  up         tracking control verbs such as (*MARK:NAME), and the execution ends  up
3150         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-
3151         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
3152         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
3153         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.
3154         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
3155         field set to NULL. For details of the backtracking control  verbs,  see         field is set to NULL. For details of the  backtracking  control  verbs,
3156         the section entitled "Backtracking control" in the pcrepattern documen-         see the section entitled "Backtracking control" in the pcrepattern doc-
3157         tation.         umentation.
3158    
3159     Option bits for pcre_exec()     Option bits for pcre_exec()
3160    
3161         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.
3162         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,
3163         PCRE_NOTBOL,   PCRE_NOTEOL,    PCRE_NOTEMPTY,    PCRE_NOTEMPTY_ATSTART,         PCRE_NOTBOL,   PCRE_NOTEOL,    PCRE_NOTEMPTY,    PCRE_NOTEMPTY_ATSTART,
3164         PCRE_NO_START_OPTIMIZE,   PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_SOFT,  and         PCRE_NO_START_OPTIMIZE,   PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_HARD,  and
3165         PCRE_PARTIAL_HARD.         PCRE_PARTIAL_SOFT.
3166    
3167           If the pattern was successfully studied with one  of  the  just-in-time
3168           (JIT) compile options, the only supported options for JIT execution are
3169           PCRE_NO_UTF8_CHECK,    PCRE_NOTBOL,     PCRE_NOTEOL,     PCRE_NOTEMPTY,
3170           PCRE_NOTEMPTY_ATSTART,  PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an
3171           unsupported option is used, JIT execution is disabled  and  the  normal
3172           interpretive code in pcre_exec() is run.
3173    
3174           PCRE_ANCHORED           PCRE_ANCHORED
3175    
3176         The PCRE_ANCHORED option limits pcre_exec() to matching  at  the  first         The  PCRE_ANCHORED  option  limits pcre_exec() to matching at the first
3177         matching  position.  If  a  pattern was compiled with PCRE_ANCHORED, or         matching position. If a pattern was  compiled  with  PCRE_ANCHORED,  or
3178         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
3179         unachored at matching time.         unachored at matching time.
3180    
3181           PCRE_BSR_ANYCRLF           PCRE_BSR_ANYCRLF
3182           PCRE_BSR_UNICODE           PCRE_BSR_UNICODE
3183    
3184         These options (which are mutually exclusive) control what the \R escape         These options (which are mutually exclusive) control what the \R escape
3185         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,
3186         or  to  match  any Unicode newline sequence. These options override the         or to match any Unicode newline sequence. These  options  override  the
3187         choice that was made or defaulted when the pattern was compiled.         choice that was made or defaulted when the pattern was compiled.
3188    
3189           PCRE_NEWLINE_CR           PCRE_NEWLINE_CR
# Line 2047  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3192  MATCHING A PATTERN: THE TRADITIONAL FUNC
3192           PCRE_NEWLINE_ANYCRLF           PCRE_NEWLINE_ANYCRLF
3193           PCRE_NEWLINE_ANY           PCRE_NEWLINE_ANY
3194    
3195         These options override  the  newline  definition  that  was  chosen  or         These  options  override  the  newline  definition  that  was chosen or
3196         defaulted  when the pattern was compiled. For details, see the descrip-         defaulted when the pattern was compiled. For details, see the  descrip-
3197         tion of pcre_compile()  above.  During  matching,  the  newline  choice         tion  of  pcre_compile()  above.  During  matching,  the newline choice
3198         affects  the  behaviour  of the dot, circumflex, and dollar metacharac-         affects the behaviour of the dot, circumflex,  and  dollar  metacharac-
3199         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
3200         match failure for an unanchored pattern.         match failure for an unanchored pattern.
3201    
3202         When  PCRE_NEWLINE_CRLF,  PCRE_NEWLINE_ANYCRLF,  or PCRE_NEWLINE_ANY is         When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF,  or  PCRE_NEWLINE_ANY  is
3203         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-
3204         rent  position  is  at  a  CRLF  sequence,  and the pattern contains no         rent position is at a  CRLF  sequence,  and  the  pattern  contains  no
3205         explicit matches for  CR  or  LF  characters,  the  match  position  is         explicit  matches  for  CR  or  LF  characters,  the  match position is
3206         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
3207         CRLF.         CRLF.
3208    
3209         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
3210         expected.  For  example,  if  the  pattern  is .+A (and the PCRE_DOTALL         expected. For example, if the  pattern  is  .+A  (and  the  PCRE_DOTALL
3211         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
3212         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.
3213         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-
3214         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-
3215         acter after the first failure.         acter after the first failure.
3216    
3217         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
3218         those  characters,  or  one  of the \r or \n escape sequences. Implicit         those characters, or one of the \r or  \n  escape  sequences.  Implicit
3219         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
3220         LF in the characters that it matches).         LF in the characters that it matches).
3221    
3222         Notwithstanding  the above, anomalous effects may still occur when CRLF         Notwithstanding the above, anomalous effects may still occur when  CRLF
3223         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
3224         pattern.         pattern.
3225    
3226           PCRE_NOTBOL           PCRE_NOTBOL
3227    
3228         This option specifies that first character of the subject string is not         This option specifies that first character of the subject string is not
3229         the beginning of a line, so the  circumflex  metacharacter  should  not         the  beginning  of  a  line, so the circumflex metacharacter should not
3230         match  before it. Setting this without PCRE_MULTILINE (at compile time)         match before it. Setting this without PCRE_MULTILINE (at compile  time)
3231         causes circumflex never to match. This option affects only  the  behav-         causes  circumflex  never to match. This option affects only the behav-
3232         iour of the circumflex metacharacter. It does not affect \A.         iour of the circumflex metacharacter. It does not affect \A.
3233    
3234           PCRE_NOTEOL           PCRE_NOTEOL
3235    
3236         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
3237         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
3238         in  multiline mode) a newline immediately before it. Setting this with-         in multiline mode) a newline immediately before it. Setting this  with-
3239         out PCRE_MULTILINE (at compile time) causes dollar never to match. This         out PCRE_MULTILINE (at compile time) causes dollar never to match. This
3240         option  affects only the behaviour of the dollar metacharacter. It does         option affects only the behaviour of the dollar metacharacter. It  does
3241         not affect \Z or \z.         not affect \Z or \z.
3242    
3243           PCRE_NOTEMPTY           PCRE_NOTEMPTY
3244    
3245         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
3246         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
3247         the alternatives match the empty string, the entire  match  fails.  For         the  alternatives  match  the empty string, the entire match fails. For
3248         example, if the pattern         example, if the pattern
3249    
3250           a?b?           a?b?
3251    
3252         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
3253         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
3254         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-
3255         rences of "a" or "b".         rences of "a" or "b".
3256    
3257           PCRE_NOTEMPTY_ATSTART           PCRE_NOTEMPTY_ATSTART
3258    
3259         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
3260         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
3261         anchored, such a match can occur only if the pattern contains \K.         anchored, such a match can occur only if the pattern contains \K.
3262    
3263         Perl    has    no    direct    equivalent    of    PCRE_NOTEMPTY     or         Perl     has    no    direct    equivalent    of    PCRE_NOTEMPTY    or
3264         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
3265         match of the empty string within its split() function, and  when  using         match  of  the empty string within its split() function, and when using
3266         the  /g  modifier.  It  is  possible  to emulate Perl's behaviour after         the /g modifier. It is  possible  to  emulate  Perl's  behaviour  after
3267         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-
3268         set  with  PCRE_NOTEMPTY_ATSTART  and  PCRE_ANCHORED,  and then if that         set with PCRE_NOTEMPTY_ATSTART and  PCRE_ANCHORED,  and  then  if  that
3269         fails, by advancing the starting offset (see below) and trying an ordi-         fails, by advancing the starting offset (see below) and trying an ordi-
3270         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
3271         in the pcredemo sample program.         in  the  pcredemo sample program. In the most general case, you have to
3272           check to see if the newline convention recognizes CRLF  as  a  newline,
3273           and  if so, and the current character is CR followed by LF, advance the
3274           starting offset by two characters instead of one.
3275    
3276           PCRE_NO_START_OPTIMIZE           PCRE_NO_START_OPTIMIZE
3277    
# Line 2134  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3282  MATCHING A PATTERN: THE TRADITIONAL FUNC
3282         cannot find it, without actually running the  main  matching  function.         cannot find it, without actually running the  main  matching  function.
3283         This means that a special item such as (*COMMIT) at the start of a pat-         This means that a special item such as (*COMMIT) at the start of a pat-
3284         tern is not considered until after a suitable starting  point  for  the         tern is not considered until after a suitable starting  point  for  the
3285         match  has been found. When callouts or (*MARK) items are in use, these         match  has been found. Also, when callouts or (*MARK) items are in use,
3286         "start-up" optimizations can cause them to be skipped if the pattern is         these "start-up" optimizations can cause them to be skipped if the pat-
3287         never  actually  used.  The start-up optimizations are in effect a pre-         tern is never actually used. The start-up optimizations are in effect a
3288         scan of the subject that takes place before the pattern is run.         pre-scan of the subject that takes place before the pattern is run.
3289    
3290         The PCRE_NO_START_OPTIMIZE option disables the start-up  optimizations,         The PCRE_NO_START_OPTIMIZE option disables the start-up  optimizations,
3291         possibly  causing  performance  to  suffer,  but ensuring that in cases         possibly  causing  performance  to  suffer,  but ensuring that in cases
3292         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
3293         such as (*COMMIT) and (*MARK) are considered at every possible starting         such as (*COMMIT) and (*MARK) are considered at every possible starting
3294         position in the subject  string.   Setting  PCRE_NO_START_OPTIMIZE  can         position in the subject string. If  PCRE_NO_START_OPTIMIZE  is  set  at
3295         change the outcome of a matching operation.  Consider the pattern         compile  time,  it  cannot  be  unset  at  matching  time.  The  use of
3296           PCRE_NO_START_OPTIMIZE  at  matching  time  (that  is,  passing  it  to
3297           pcre_exec())  disables  JIT  execution;  in this situation, matching is
3298           always done using interpretively.
3299    
3300           Setting PCRE_NO_START_OPTIMIZE can change the  outcome  of  a  matching
3301           operation.  Consider the pattern
3302    
3303           (*COMMIT)ABC           (*COMMIT)ABC
3304    
# Line 2175  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3329  MATCHING A PATTERN: THE TRADITIONAL FUNC
3329    
3330         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
3331         UTF-8  string is automatically checked when pcre_exec() is subsequently         UTF-8  string is automatically checked when pcre_exec() is subsequently
3332         called.  The value of startoffset is also checked  to  ensure  that  it         called.  The entire string is checked before any other processing takes
3333         points  to  the start of a UTF-8 character. There is a discussion about         place.  The  value  of  startoffset  is  also checked to ensure that it
3334         the validity of UTF-8 strings in the section on UTF-8  support  in  the         points to the start of a UTF-8 character. There is a  discussion  about
3335         main  pcre  page.  If  an  invalid  UTF-8  sequence  of bytes is found,         the  validity  of  UTF-8 strings in the pcreunicode page. If an invalid
3336         pcre_exec() returns the error PCRE_ERROR_BADUTF8. If  startoffset  con-         sequence  of  bytes   is   found,   pcre_exec()   returns   the   error
3337         tains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.         PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a
3338           truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
3339           both  cases, information about the precise nature of the error may also
3340           be returned (see the descriptions of these errors in the section  enti-
3341           tled  Error return values from pcre_exec() below).  If startoffset con-
3342           tains a value that does not point to the start of a UTF-8 character (or
3343           to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is returned.
3344    
3345         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
3346         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 3348  MATCHING A PATTERN: THE TRADITIONAL FUNC
3348         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
3349         making  repeated  calls  to  find  all  the matches in a single subject         making  repeated  calls  to  find  all  the matches in a single subject
3350         string. However, you should be  sure  that  the  value  of  startoffset         string. However, you should be  sure  that  the  value  of  startoffset
3351         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
3352         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
3353         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
3354         acter, is undefined. Your program may crash.         may crash.
3355    
3356           PCRE_PARTIAL_HARD           PCRE_PARTIAL_HARD
3357           PCRE_PARTIAL_SOFT           PCRE_PARTIAL_SOFT
# Line 2200  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3360  MATCHING A PATTERN: THE TRADITIONAL FUNC
3360         patibility,  PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial         patibility,  PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial
3361         match occurs if the end of the subject string is reached  successfully,         match occurs if the end of the subject string is reached  successfully,
3362         but  there  are not enough subject characters to complete the match. If         but  there  are not enough subject characters to complete the match. If
3363         this happens when PCRE_PARTIAL_HARD  is  set,  pcre_exec()  immediately         this happens when PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set,
3364         returns  PCRE_ERROR_PARTIAL.  Otherwise,  if  PCRE_PARTIAL_SOFT is set,         matching  continues  by  testing any remaining alternatives. Only if no
3365         matching continues by testing any other alternatives. Only if they  all         complete match can be found is PCRE_ERROR_PARTIAL returned  instead  of
3366         fail  is  PCRE_ERROR_PARTIAL  returned (instead of PCRE_ERROR_NOMATCH).         PCRE_ERROR_NOMATCH.  In  other  words,  PCRE_PARTIAL_SOFT says that the
3367         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
3368         found  is  set  as  the first matching string. There is a more detailed         match can be found.
3369         discussion in the pcrepartial documentation.  
3370           If  PCRE_PARTIAL_HARD  is  set, it overrides PCRE_PARTIAL_SOFT. In this
3371           case, if a partial match  is  found,  pcre_exec()  immediately  returns
3372           PCRE_ERROR_PARTIAL,  without  considering  any  other  alternatives. In
3373           other words, when PCRE_PARTIAL_HARD is set, a partial match is  consid-
3374           ered to be more important that an alternative complete match.
3375    
3376           In  both  cases,  the portion of the string that was inspected when the
3377           partial match was found is set as the first matching string. There is a
3378           more  detailed  discussion  of partial and multi-segment matching, with
3379           examples, in the pcrepartial documentation.
3380    
3381     The string to be matched by pcre_exec()     The string to be matched by pcre_exec()
3382    
3383         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
3384         length (in bytes) in length, and a starting byte offset in startoffset.         length  in  length, and a starting offset in startoffset. The units for
3385         In UTF-8 mode, the byte offset must point to the start of a UTF-8 char-         length and startoffset are bytes for the  8-bit  library,  16-bit  data
3386         acter.  Unlike  the pattern string, the subject may contain binary zero         items  for  the  16-bit  library,  and 32-bit data items for the 32-bit
3387         bytes. When the starting offset is zero, the search for a match  starts         library.
3388         at  the  beginning  of  the subject, and this is by far the most common  
3389         case.         If startoffset is negative or greater than the length of  the  subject,
3390           pcre_exec()  returns  PCRE_ERROR_BADOFFSET. When the starting offset is
3391         A non-zero starting offset is useful when searching for  another  match         zero, the search for a match starts at the beginning  of  the  subject,
3392         in  the same subject by calling pcre_exec() again after a previous suc-         and  this  is by far the most common case. In UTF-8 or UTF-16 mode, the
3393         cess.  Setting startoffset differs from just passing over  a  shortened         offset must point to the start of a character, or the end of  the  sub-
3394         string  and  setting  PCRE_NOTBOL  in the case of a pattern that begins         ject  (in  UTF-32 mode, one data unit equals one character, so all off-
3395           sets are valid). Unlike the pattern string,  the  subject  may  contain
3396           binary zeroes.
3397    
3398           A  non-zero  starting offset is useful when searching for another match
3399           in the same subject by calling pcre_exec() again after a previous  suc-
3400           cess.   Setting  startoffset differs from just passing over a shortened
3401           string and setting PCRE_NOTBOL in the case of  a  pattern  that  begins
3402         with any kind of lookbehind. For example, consider the pattern         with any kind of lookbehind. For example, consider the pattern
3403    
3404           \Biss\B           \Biss\B
3405    
3406         which finds occurrences of "iss" in the middle of  words.  (\B  matches         which  finds  occurrences  of "iss" in the middle of words. (\B matches
3407         only  if  the  current position in the subject is not a word boundary.)         only if the current position in the subject is not  a  word  boundary.)
3408         When applied to the string "Mississipi" the first call  to  pcre_exec()         When  applied  to the string "Mississipi" the first call to pcre_exec()
3409         finds  the  first  occurrence. If pcre_exec() is called again with just         finds the first occurrence. If pcre_exec() is called  again  with  just
3410         the remainder of the subject,  namely  "issipi",  it  does  not  match,         the  remainder  of  the  subject,  namely  "issipi", it does not match,
3411         because \B is always false at the start of the subject, which is deemed         because \B is always false at the start of the subject, which is deemed
3412         to be a word boundary. However, if pcre_exec()  is  passed  the