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revision 196 by ph10, Mon Jul 30 13:44:50 2007 UTC revision 788 by ph10, Tue Dec 6 15:38:01 2011 UTC
# Line 1  Line 1 
1  .TH PCREAPI 3  .TH PCREAPI 3
2  .SH NAME  .SH NAME
3  PCRE - Perl-compatible regular expressions  PCRE - Perl-compatible regular expressions
4  .SH "PCRE NATIVE API"  .SH "PCRE NATIVE API BASIC FUNCTIONS"
5  .rs  .rs
6  .sp  .sp
7  .B #include <pcre.h>  .B #include <pcre.h>
# Line 25  PCRE - Perl-compatible regular expressio Line 25  PCRE - Perl-compatible regular expressio
25  .ti +5n  .ti +5n
26  .B const char **\fIerrptr\fP);  .B const char **\fIerrptr\fP);
27  .PP  .PP
28    .B void pcre_free_study(pcre_extra *\fIextra\fP);
29    .PP
30  .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"  .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
31  .ti +5n  .ti +5n
32  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
33  .ti +5n  .ti +5n
34  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
35    .
36    .
37    .SH "PCRE NATIVE API AUXILIARY FUNCTIONS"
38    .rs
39    .sp
40    .B pcre_jit_stack *pcre_jit_stack_alloc(int \fIstartsize\fP, int \fImaxsize\fP);
41    .PP
42    .B void pcre_jit_stack_free(pcre_jit_stack *\fIstack\fP);
43    .PP
44    .B void pcre_assign_jit_stack(pcre_extra *\fIextra\fP,
45    .ti +5n
46    .B pcre_jit_callback \fIcallback\fP, void *\fIdata\fP);
47  .PP  .PP
48  .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"  .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
49  .ti +5n  .ti +5n
# Line 97  PCRE - Perl-compatible regular expressio Line 111  PCRE - Perl-compatible regular expressio
111  .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);  .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
112  .PP  .PP
113  .B char *pcre_version(void);  .B char *pcre_version(void);
114  .PP  .
115    .
116    .SH "PCRE NATIVE API INDIRECTED FUNCTIONS"
117    .rs
118    .sp
119  .B void *(*pcre_malloc)(size_t);  .B void *(*pcre_malloc)(size_t);
120  .PP  .PP
121  .B void (*pcre_free)(void *);  .B void (*pcre_free)(void *);
# Line 114  PCRE - Perl-compatible regular expressio Line 132  PCRE - Perl-compatible regular expressio
132  .sp  .sp
133  PCRE has its own native API, which is described in this document. There are  PCRE has its own native API, which is described in this document. There are
134  also some wrapper functions that correspond to the POSIX regular expression  also some wrapper functions that correspond to the POSIX regular expression
135  API. These are described in the  API, but they do not give access to all the functionality. They are described
136    in the
137  .\" HREF  .\" HREF
138  \fBpcreposix\fP  \fBpcreposix\fP
139  .\"  .\"
140  documentation. Both of these APIs define a set of C function calls. A C++  documentation. Both of these APIs define a set of C function calls. A C++
141  wrapper is distributed with PCRE. It is documented in the  wrapper is also distributed with PCRE. It is documented in the
142  .\" HREF  .\" HREF
143  \fBpcrecpp\fP  \fBpcrecpp\fP
144  .\"  .\"
# Line 132  an application that uses PCRE. The heade Line 151  an application that uses PCRE. The heade
151  and PCRE_MINOR to contain the major and minor release numbers for the library.  and PCRE_MINOR to contain the major and minor release numbers for the library.
152  Applications can use these to include support for different releases of PCRE.  Applications can use these to include support for different releases of PCRE.
153  .P  .P
154    In a Windows environment, if you want to statically link an application program
155    against a non-dll \fBpcre.a\fP file, you must define PCRE_STATIC before
156    including \fBpcre.h\fP or \fBpcrecpp.h\fP, because otherwise the
157    \fBpcre_malloc()\fP and \fBpcre_free()\fP exported functions will be declared
158    \fB__declspec(dllimport)\fP, with unwanted results.
159    .P
160  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,
161  and \fBpcre_exec()\fP are used for compiling and matching regular expressions  and \fBpcre_exec()\fP are used for compiling and matching regular expressions
162  in a Perl-compatible manner. A sample program that demonstrates the simplest  in a Perl-compatible manner. A sample program that demonstrates the simplest
163  way of using them is provided in the file called \fIpcredemo.c\fP in the source  way of using them is provided in the file called \fIpcredemo.c\fP in the PCRE
164  distribution. The  source distribution. A listing of this program is given in the
165    .\" HREF
166    \fBpcredemo\fP
167    .\"
168    documentation, and the
169  .\" HREF  .\" HREF
170  \fBpcresample\fP  \fBpcresample\fP
171  .\"  .\"
172  documentation describes how to run it.  documentation describes how to compile and run it.
173    .P
174    Just-in-time compiler support is an optional feature of PCRE that can be built
175    in appropriate hardware environments. It greatly speeds up the matching
176    performance of many patterns. Simple programs can easily request that it be
177    used if available, by setting an option that is ignored when it is not
178    relevant. More complicated programs might need to make use of the functions
179    \fBpcre_jit_stack_alloc()\fP, \fBpcre_jit_stack_free()\fP, and
180    \fBpcre_assign_jit_stack()\fP in order to control the JIT code's memory usage.
181    These functions are discussed in the
182    .\" HREF
183    \fBpcrejit\fP
184    .\"
185    documentation.
186  .P  .P
187  A second matching function, \fBpcre_dfa_exec()\fP, which is not  A second matching function, \fBpcre_dfa_exec()\fP, which is not
188  Perl-compatible, is also provided. This uses a different algorithm for the  Perl-compatible, is also provided. This uses a different algorithm for the
189  matching. The alternative algorithm finds all possible matches (at a given  matching. The alternative algorithm finds all possible matches (at a given
190  point in the subject), and scans the subject just once. However, this algorithm  point in the subject), and scans the subject just once (unless there are
191  does not return captured substrings. A description of the two matching  lookbehind assertions). However, this algorithm does not return captured
192  algorithms and their advantages and disadvantages is given in the  substrings. A description of the two matching algorithms and their advantages
193    and disadvantages is given in the
194  .\" HREF  .\" HREF
195  \fBpcrematching\fP  \fBpcrematching\fP
196  .\"  .\"
# Line 218  points during a matching operation. Deta Line 261  points during a matching operation. Deta
261  documentation.  documentation.
262  .  .
263  .  .
264    .\" HTML <a name="newlines"></a>
265  .SH NEWLINES  .SH NEWLINES
266  .rs  .rs
267  .sp  .sp
# Line 235  The default default is LF, which is the Line 279  The default default is LF, which is the
279  default can be overridden, either when a pattern is compiled, or when it is  default can be overridden, either when a pattern is compiled, or when it is
280  matched.  matched.
281  .P  .P
282    At compile time, the newline convention can be specified by the \fIoptions\fP
283    argument of \fBpcre_compile()\fP, or it can be specified by special text at the
284    start of the pattern itself; this overrides any other settings. See the
285    .\" HREF
286    \fBpcrepattern\fP
287    .\"
288    page for details of the special character sequences.
289    .P
290  In the PCRE documentation the word "newline" is used to mean "the character or  In the PCRE documentation the word "newline" is used to mean "the character or
291  pair of characters that indicate a line break". The choice of newline  pair of characters that indicate a line break". The choice of newline
292  convention affects the handling of the dot, circumflex, and dollar  convention affects the handling of the dot, circumflex, and dollar
293  metacharacters, the handling of #-comments in /x mode, and, when CRLF is a  metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
294  recognized line ending sequence, the match position advancement for a  recognized line ending sequence, the match position advancement for a
295  non-anchored pattern. The choice of newline convention does not affect the  non-anchored pattern. There is more detail about this in the
296  interpretation of the \en or \er escape sequences.  .\" HTML <a href="#execoptions">
297    .\" </a>
298    section on \fBpcre_exec()\fP options
299    .\"
300    below.
301    .P
302    The choice of newline convention does not affect the interpretation of
303    the \en or \er escape sequences, nor does it affect what \eR matches, which is
304    controlled in a similar way, but by separate options.
305  .  .
306  .  .
307  .SH MULTITHREADING  .SH MULTITHREADING
# Line 254  callout function pointed to by \fBpcre_c Line 314  callout function pointed to by \fBpcre_c
314  .P  .P
315  The compiled form of a regular expression is not altered during matching, so  The compiled form of a regular expression is not altered during matching, so
316  the same compiled pattern can safely be used by several threads at once.  the same compiled pattern can safely be used by several threads at once.
317    .P
318    If the just-in-time optimization feature is being used, it needs separate
319    memory stack areas for each thread. See the
320    .\" HREF
321    \fBpcrejit\fP
322    .\"
323    documentation for more details.
324  .  .
325  .  .
326  .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"  .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"
# Line 296  otherwise it is set to zero. Line 363  otherwise it is set to zero.
363  The output is an integer that is set to one if support for Unicode character  The output is an integer that is set to one if support for Unicode character
364  properties is available; otherwise it is set to zero.  properties is available; otherwise it is set to zero.
365  .sp  .sp
366      PCRE_CONFIG_JIT
367    .sp
368    The output is an integer that is set to one if support for just-in-time
369    compiling is available; otherwise it is set to zero.
370    .sp
371    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
372  .sp  .sp
373  The output is an integer whose value specifies the default character sequence  The output is an integer whose value specifies the default character sequence
374  that is recognized as meaning "newline". The four values that are supported  that is recognized as meaning "newline". The four values that are supported
375  are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF, and -1 for ANY. The  are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF, and -1 for ANY.
376  default should normally be the standard sequence for your operating system.  Though they are derived from ASCII, the same values are returned in EBCDIC
377    environments. The default should normally correspond to the standard sequence
378    for your operating system.
379    .sp
380      PCRE_CONFIG_BSR
381    .sp
382    The output is an integer whose value indicates what character sequences the \eR
383    escape sequence matches by default. A value of 0 means that \eR matches any
384    Unicode line ending sequence; a value of 1 means that \eR matches only CR, LF,
385    or CRLF. The default can be overridden when a pattern is compiled or matched.
386  .sp  .sp
387    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
388  .sp  .sp
# Line 323  documentation. Line 404  documentation.
404  .sp  .sp
405    PCRE_CONFIG_MATCH_LIMIT    PCRE_CONFIG_MATCH_LIMIT
406  .sp  .sp
407  The output is an integer that gives the default limit for the number of  The output is a long integer that gives the default limit for the number of
408  internal matching function calls in a \fBpcre_exec()\fP execution. Further  internal matching function calls in a \fBpcre_exec()\fP execution. Further
409  details are given with \fBpcre_exec()\fP below.  details are given with \fBpcre_exec()\fP below.
410  .sp  .sp
411    PCRE_CONFIG_MATCH_LIMIT_RECURSION    PCRE_CONFIG_MATCH_LIMIT_RECURSION
412  .sp  .sp
413  The output is an integer that gives the default limit for the depth of  The output is a long integer that gives the default limit for the depth of
414  recursion when calling the internal matching function in a \fBpcre_exec()\fP  recursion when calling the internal matching function in a \fBpcre_exec()\fP
415  execution. Further details are given with \fBpcre_exec()\fP below.  execution. Further details are given with \fBpcre_exec()\fP below.
416  .sp  .sp
# Line 364  avoiding the use of the stack. Line 445  avoiding the use of the stack.
445  Either of the functions \fBpcre_compile()\fP or \fBpcre_compile2()\fP can be  Either of the functions \fBpcre_compile()\fP or \fBpcre_compile2()\fP can be
446  called to compile a pattern into an internal form. The only difference between  called to compile a pattern into an internal form. The only difference between
447  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,
448  \fIerrorcodeptr\fP, via which a numerical error code can be returned.  \fIerrorcodeptr\fP, via which a numerical error code can be returned. To avoid
449    too much repetition, we refer just to \fBpcre_compile()\fP below, but the
450    information applies equally to \fBpcre_compile2()\fP.
451  .P  .P
452  The pattern is a C string terminated by a binary zero, and is passed in the  The pattern is a C string terminated by a binary zero, and is passed in the
453  \fIpattern\fP argument. A pointer to a single block of memory that is obtained  \fIpattern\fP argument. A pointer to a single block of memory that is obtained
# Line 380  argument, which is an address (see below Line 463  argument, which is an address (see below
463  .P  .P
464  The \fIoptions\fP argument contains various bit settings that affect the  The \fIoptions\fP argument contains various bit settings that affect the
465  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
466  options are described below. Some of them, in particular, those that are  options are described below. Some of them (in particular, those that are
467  compatible with Perl, can also be set and unset from within the pattern (see  compatible with Perl, but some others as well) can also be set and unset from
468  the detailed description in the  within the pattern (see the detailed description in the
469  .\" HREF  .\" HREF
470  \fBpcrepattern\fP  \fBpcrepattern\fP
471  .\"  .\"
472  documentation). For these options, the contents of the \fIoptions\fP argument  documentation). For those options that can be different in different parts of
473  specifies their initial settings at the start of compilation and execution. The  the pattern, the contents of the \fIoptions\fP argument specifies their
474  PCRE_ANCHORED and PCRE_NEWLINE_\fIxxx\fP options can be set at the time of  settings at the start of compilation and execution. The PCRE_ANCHORED,
475  matching as well as at compile time.  PCRE_BSR_\fIxxx\fP, PCRE_NEWLINE_\fIxxx\fP, PCRE_NO_UTF8_CHECK, and
476    PCRE_NO_START_OPT options can be set at the time of matching as well as at
477    compile time.
478  .P  .P
479  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
480  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
481  NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual  NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual
482  error message. This is a static string that is part of the library. You must  error message. This is a static string that is part of the library. You must
483  not try to free it. The offset from the start of the pattern to the character  not try to free it. Normally, the offset from the start of the pattern to the
484  where the error was discovered is placed in the variable pointed to by  byte that was being processed when the error was discovered is placed in the
485  \fIerroffset\fP, which must not be NULL. If it is, an immediate error is given.  variable pointed to by \fIerroffset\fP, which must not be NULL (if it is, an
486    immediate error is given). However, for an invalid UTF-8 string, the offset is
487    that of the first byte of the failing character. Also, some errors are not
488    detected until checks are carried out when the whole pattern has been scanned;
489    in these cases the offset passed back is the length of the pattern.
490    .P
491    Note that the offset is in bytes, not characters, even in UTF-8 mode. It may
492    sometimes point into the middle of a UTF-8 character.
493  .P  .P
494  If \fBpcre_compile2()\fP is used instead of \fBpcre_compile()\fP, and the  If \fBpcre_compile2()\fP is used instead of \fBpcre_compile()\fP, and the
495  \fIerrorcodeptr\fP argument is not NULL, a non-zero error code number is  \fIerrorcodeptr\fP argument is not NULL, a non-zero error code number is
# Line 444  facility, see the Line 536  facility, see the
536  .\"  .\"
537  documentation.  documentation.
538  .sp  .sp
539      PCRE_BSR_ANYCRLF
540      PCRE_BSR_UNICODE
541    .sp
542    These options (which are mutually exclusive) control what the \eR escape
543    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
544    match any Unicode newline sequence. The default is specified when PCRE is
545    built. It can be overridden from within the pattern, or by setting an option
546    when a compiled pattern is matched.
547    .sp
548    PCRE_CASELESS    PCRE_CASELESS
549  .sp  .sp
550  If this bit is set, letters in the pattern match both upper and lower case  If this bit is set, letters in the pattern match both upper and lower case
# Line 467  pattern. Line 568  pattern.
568  .sp  .sp
569    PCRE_DOTALL    PCRE_DOTALL
570  .sp  .sp
571  If this bit is set, a dot metacharater in the pattern matches all characters,  If this bit is set, a dot metacharacter in the pattern matches a character of
572  including those that indicate newline. Without it, a dot does not match when  any value, including one that indicates a newline. However, it only ever
573  the current position is at a newline. This option is equivalent to Perl's /s  matches one character, even if newlines are coded as CRLF. Without this option,
574  option, and it can be changed within a pattern by a (?s) option setting. A  a dot does not match when the current position is at a newline. This option is
575  negative class such as [^a] always matches newline characters, independent of  equivalent to Perl's /s option, and it can be changed within a pattern by a
576  the setting of this option.  (?s) option setting. A negative class such as [^a] always matches newline
577    characters, independent of the setting of this option.
578  .sp  .sp
579    PCRE_DUPNAMES    PCRE_DUPNAMES
580  .sp  .sp
# Line 494  unescaped # outside a character class an Line 596  unescaped # outside a character class an
596  ignored. This is equivalent to Perl's /x option, and it can be changed within a  ignored. This is equivalent to Perl's /x option, and it can be changed within a
597  pattern by a (?x) option setting.  pattern by a (?x) option setting.
598  .P  .P
599    Which characters are interpreted as newlines is controlled by the options
600    passed to \fBpcre_compile()\fP or by a special sequence at the start of the
601    pattern, as described in the section entitled
602    .\" HTML <a href="pcrepattern.html#newlines">
603    .\" </a>
604    "Newline conventions"
605    .\"
606    in the \fBpcrepattern\fP documentation. Note that the end of this type of
607    comment is a literal newline sequence in the pattern; escape sequences that
608    happen to represent a newline do not count.
609    .P
610  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
611  Note, however, that this applies only to data characters. Whitespace characters  Note, however, that this applies only to data characters. Whitespace characters
612  may never appear within special character sequences in a pattern, for example  may never appear within special character sequences in a pattern, for example
613  within the sequence (?( which introduces a conditional subpattern.  within the sequence (?( that introduces a conditional subpattern.
614  .sp  .sp
615    PCRE_EXTRA    PCRE_EXTRA
616  .sp  .sp
# Line 507  set, any backslash in a pattern that is Line 620  set, any backslash in a pattern that is
620  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
621  expansion. By default, as in Perl, a backslash followed by a letter with no  expansion. By default, as in Perl, a backslash followed by a letter with no
622  special meaning is treated as a literal. (Perl can, however, be persuaded to  special meaning is treated as a literal. (Perl can, however, be persuaded to
623  give a warning for this.) There are at present no other features controlled by  give an error for this, by running it with the -w option.) There are at present
624  this option. It can also be set by a (?X) option setting within a pattern.  no other features controlled by this option. It can also be set by a (?X)
625    option setting within a pattern.
626  .sp  .sp
627    PCRE_FIRSTLINE    PCRE_FIRSTLINE
628  .sp  .sp
# Line 516  If this option is set, an unanchored pat Line 630  If this option is set, an unanchored pat
630  the first newline in the subject string, though the matched text may continue  the first newline in the subject string, though the matched text may continue
631  over the newline.  over the newline.
632  .sp  .sp
633      PCRE_JAVASCRIPT_COMPAT
634    .sp
635    If this option is set, PCRE's behaviour is changed in some ways so that it is
636    compatible with JavaScript rather than Perl. The changes are as follows:
637    .P
638    (1) A lone closing square bracket in a pattern causes a compile-time error,
639    because this is illegal in JavaScript (by default it is treated as a data
640    character). Thus, the pattern AB]CD becomes illegal when this option is set.
641    .P
642    (2) At run time, a back reference to an unset subpattern group matches an empty
643    string (by default this causes the current matching alternative to fail). A
644    pattern such as (\e1)(a) succeeds when this option is set (assuming it can find
645    an "a" in the subject), whereas it fails by default, for Perl compatibility.
646    .P
647    (3) \eU matches an upper case "U" character; by default \eU causes a compile
648    time error (Perl uses \eU to upper case subsequent characters).
649    .P
650    (4) \eu matches a lower case "u" character unless it is followed by four
651    hexadecimal digits, in which case the hexadecimal number defines the code point
652    to match. By default, \eu causes a compile time error (Perl uses it to upper
653    case the following character).
654    .P
655    (5) \ex matches a lower case "x" character unless it is followed by two
656    hexadecimal digits, in which case the hexadecimal number defines the code point
657    to match. By default, as in Perl, a hexadecimal number is always expected after
658    \ex, but it may have zero, one, or two digits (so, for example, \exz matches a
659    binary zero character followed by z).
660    .sp
661    PCRE_MULTILINE    PCRE_MULTILINE
662  .sp  .sp
663  By default, PCRE treats the subject string as consisting of a single line of  By default, PCRE treats the subject string as consisting of a single line of
# Line 557  option, the combination may or may not b Line 699  option, the combination may or may not b
699  PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but  PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
700  other combinations may yield unused numbers and cause an error.  other combinations may yield unused numbers and cause an error.
701  .P  .P
702  The only time that a line break is specially recognized when compiling a  The only time that a line break in a pattern is specially recognized when
703  pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character  compiling is when PCRE_EXTENDED is set. CR and LF are whitespace characters,
704  class is encountered. This indicates a comment that lasts until after the next  and so are ignored in this mode. Also, an unescaped # outside a character class
705  line break sequence. In other circumstances, line break sequences are treated  indicates a comment that lasts until after the next line break sequence. In
706  as literal data, except that in PCRE_EXTENDED mode, both CR and LF are treated  other circumstances, line break sequences in patterns are treated as literal
707  as whitespace characters and are therefore ignored.  data.
708  .P  .P
709  The newline option that is set at compile time becomes the default that is used  The newline option that is set at compile time becomes the default that is used
710  for \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, but it can be overridden.  for \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, but it can be overridden.
# Line 575  were followed by ?: but named parenthese Line 717  were followed by ?: but named parenthese
717  they acquire numbers in the usual way). There is no equivalent of this option  they acquire numbers in the usual way). There is no equivalent of this option
718  in Perl.  in Perl.
719  .sp  .sp
720      NO_START_OPTIMIZE
721    .sp
722    This is an option that acts at matching time; that is, it is really an option
723    for \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. If it is set at compile time,
724    it is remembered with the compiled pattern and assumed at matching time. For
725    details see the discussion of PCRE_NO_START_OPTIMIZE
726    .\" HTML <a href="#execoptions">
727    .\" </a>
728    below.
729    .\"
730    .sp
731      PCRE_UCP
732    .sp
733    This option changes the way PCRE processes \eB, \eb, \eD, \ed, \eS, \es, \eW,
734    \ew, and some of the POSIX character classes. By default, only ASCII characters
735    are recognized, but if PCRE_UCP is set, Unicode properties are used instead to
736    classify characters. More details are given in the section on
737    .\" HTML <a href="pcre.html#genericchartypes">
738    .\" </a>
739    generic character types
740    .\"
741    in the
742    .\" HREF
743    \fBpcrepattern\fP
744    .\"
745    page. If you set PCRE_UCP, matching one of the items it affects takes much
746    longer. The option is available only if PCRE has been compiled with Unicode
747    property support.
748    .sp
749    PCRE_UNGREEDY    PCRE_UNGREEDY
750  .sp  .sp
751  This option inverts the "greediness" of the quantifiers so that they are not  This option inverts the "greediness" of the quantifiers so that they are not
# Line 588  of UTF-8 characters instead of single-by Line 759  of UTF-8 characters instead of single-by
759  available only when PCRE is built to include UTF-8 support. If not, the use  available only when PCRE is built to include UTF-8 support. If not, the use
760  of this option provokes an error. Details of how this option changes the  of this option provokes an error. Details of how this option changes the
761  behaviour of PCRE are given in the  behaviour of PCRE are given in the
 .\" HTML <a href="pcre.html#utf8support">  
 .\" </a>  
 section on UTF-8 support  
 .\"  
 in the main  
762  .\" HREF  .\" HREF
763  \fBpcre\fP  \fBpcreunicode\fP
764  .\"  .\"
765  page.  page.
766  .sp  .sp
767    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
768  .sp  .sp
769  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
770  automatically checked. If an invalid UTF-8 sequence of bytes is found,  automatically checked. There is a discussion about the
771  \fBpcre_compile()\fP returns an error. If you already know that your pattern is  .\" HTML <a href="pcre.html#utf8strings">
772  valid, and you want to skip this check for performance reasons, you can set the  .\" </a>
773  PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid  validity of UTF-8 strings
774  UTF-8 string as a pattern is undefined. It may cause your program to crash.  .\"
775  Note that this option can also be passed to \fBpcre_exec()\fP and  in the main
776  \fBpcre_dfa_exec()\fP, to suppress the UTF-8 validity checking of subject  .\" HREF
777  strings.  \fBpcre\fP
778    .\"
779    page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_compile()\fP
780    returns an error. If you already know that your pattern is valid, and you want
781    to skip this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK
782    option. When it is set, the effect of passing an invalid UTF-8 string as a
783    pattern is undefined. It may cause your program to crash. Note that this option
784    can also be passed to \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, to suppress
785    the UTF-8 validity checking of subject strings.
786  .  .
787  .  .
788  .SH "COMPILATION ERROR CODES"  .SH "COMPILATION ERROR CODES"
# Line 631  out of use. To avoid confusion, they hav Line 805  out of use. To avoid confusion, they hav
805     9  nothing to repeat     9  nothing to repeat
806    10  [this code is not in use]    10  [this code is not in use]
807    11  internal error: unexpected repeat    11  internal error: unexpected repeat
808    12  unrecognized character after (?    12  unrecognized character after (? or (?-
809    13  POSIX named classes are supported only within a class    13  POSIX named classes are supported only within a class
810    14  missing )    14  missing )
811    15  reference to non-existent subpattern    15  reference to non-existent subpattern
# Line 639  out of use. To avoid confusion, they hav Line 813  out of use. To avoid confusion, they hav
813    17  unknown option bit(s) set    17  unknown option bit(s) set
814    18  missing ) after comment    18  missing ) after comment
815    19  [this code is not in use]    19  [this code is not in use]
816    20  regular expression too large    20  regular expression is too large
817    21  failed to get memory    21  failed to get memory
818    22  unmatched parentheses    22  unmatched parentheses
819    23  internal error: code overflow    23  internal error: code overflow
# Line 656  out of use. To avoid confusion, they hav Line 830  out of use. To avoid confusion, they hav
830    34  character value in \ex{...} sequence is too large    34  character value in \ex{...} sequence is too large
831    35  invalid condition (?(0)    35  invalid condition (?(0)
832    36  \eC not allowed in lookbehind assertion    36  \eC not allowed in lookbehind assertion
833    37  PCRE does not support \eL, \el, \eN, \eU, or \eu    37  PCRE does not support \eL, \el, \eN{name}, \eU, or \eu
834    38  number after (?C is > 255    38  number after (?C is > 255
835    39  closing ) for (?C expected    39  closing ) for (?C expected
836    40  recursive call could loop indefinitely    40  recursive call could loop indefinitely
# Line 668  out of use. To avoid confusion, they hav Line 842  out of use. To avoid confusion, they hav
842    46  malformed \eP or \ep sequence    46  malformed \eP or \ep sequence
843    47  unknown property name after \eP or \ep    47  unknown property name after \eP or \ep
844    48  subpattern name is too long (maximum 32 characters)    48  subpattern name is too long (maximum 32 characters)
845    49  too many named subpatterns (maximum 10,000)    49  too many named subpatterns (maximum 10000)
846    50  repeated subpattern is too long    50  [this code is not in use]
847    51  octal value is greater than \e377 (not in UTF-8 mode)    51  octal value is greater than \e377 (not in UTF-8 mode)
848    52  internal error: overran compiling workspace    52  internal error: overran compiling workspace
849    53  internal error: previously-checked referenced subpattern not found    53  internal error: previously-checked referenced subpattern
850            not found
851    54  DEFINE group contains more than one branch    54  DEFINE group contains more than one branch
852    55  repeating a DEFINE group is not allowed    55  repeating a DEFINE group is not allowed
853    56  inconsistent NEWLINE options"    56  inconsistent NEWLINE options
854    57  \eg is not followed by a braced name or an optionally braced    57  \eg is not followed by a braced, angle-bracketed, or quoted
855          non-zero number          name/number or by a plain number
856    58  (?+ or (?- or (?(+ or (?(- must be followed by a non-zero number    58  a numbered reference must not be zero
857      59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
858      60  (*VERB) not recognized
859      61  number is too big
860      62  subpattern name expected
861      63  digit expected after (?+
862      64  ] is an invalid data character in JavaScript compatibility mode
863      65  different names for subpatterns of the same number are
864            not allowed
865      66  (*MARK) must have an argument
866      67  this version of PCRE is not compiled with PCRE_UCP support
867      68  \ec must be followed by an ASCII character
868      69  \ek is not followed by a braced, angle-bracketed, or quoted name
869    .sp
870    The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
871    be used if the limits were changed when PCRE was built.
872  .  .
873  .  .
874    .\" HTML <a name="studyingapattern"></a>
875  .SH "STUDYING A PATTERN"  .SH "STUDYING A PATTERN"
876  .rs  .rs
877  .sp  .sp
# Line 697  help speed up matching, \fBpcre_study()\ Line 888  help speed up matching, \fBpcre_study()\
888  results of the study.  results of the study.
889  .P  .P
890  The returned value from \fBpcre_study()\fP can be passed directly to  The returned value from \fBpcre_study()\fP can be passed directly to
891  \fBpcre_exec()\fP. However, a \fBpcre_extra\fP block also contains other  \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. However, a \fBpcre_extra\fP block
892  fields that can be set by the caller before the block is passed; these are  also contains other fields that can be set by the caller before the block is
893  described  passed; these are described
894  .\" HTML <a href="#extradata">  .\" HTML <a href="#extradata">
895  .\" </a>  .\" </a>
896  below  below
897  .\"  .\"
898  in the section on matching a pattern.  in the section on matching a pattern.
899  .P  .P
900  If studying the pattern does not produce any additional information  If studying the pattern does not produce any useful information,
901  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program
902  wants to pass any of the other fields to \fBpcre_exec()\fP, it must set up its  wants to pass any of the other fields to \fBpcre_exec()\fP or
903  own \fBpcre_extra\fP block.  \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block.
904  .P  .P
905  The second argument of \fBpcre_study()\fP contains option bits. At present, no  The second argument of \fBpcre_study()\fP contains option bits. There is only
906  options are defined, and this argument should always be zero.  one option: PCRE_STUDY_JIT_COMPILE. If this is set, and the just-in-time
907    compiler is available, the pattern is further compiled into machine code that
908    executes much faster than the \fBpcre_exec()\fP matching function. If
909    the just-in-time compiler is not available, this option is ignored. All other
910    bits in the \fIoptions\fP argument must be zero.
911    .P
912    JIT compilation is a heavyweight optimization. It can take some time for
913    patterns to be analyzed, and for one-off matches and simple patterns the
914    benefit of faster execution might be offset by a much slower study time.
915    Not all patterns can be optimized by the JIT compiler. For those that cannot be
916    handled, matching automatically falls back to the \fBpcre_exec()\fP
917    interpreter. For more details, see the
918    .\" HREF
919    \fBpcrejit\fP
920    .\"
921    documentation.
922  .P  .P
923  The third argument for \fBpcre_study()\fP is a pointer for an error message. If  The third argument for \fBpcre_study()\fP is a pointer for an error message. If
924  studying succeeds (even if no data is returned), the variable it points to is  studying succeeds (even if no data is returned), the variable it points to is
# Line 721  static string that is part of the librar Line 927  static string that is part of the librar
927  should test the error pointer for NULL after calling \fBpcre_study()\fP, to be  should test the error pointer for NULL after calling \fBpcre_study()\fP, to be
928  sure that it has run successfully.  sure that it has run successfully.
929  .P  .P
930  This is a typical call to \fBpcre_study\fP():  When you are finished with a pattern, you can free the memory used for the
931    study data by calling \fBpcre_free_study()\fP. This function was added to the
932    API for release 8.20. For earlier versions, the memory could be freed with
933    \fBpcre_free()\fP, just like the pattern itself. This will still work in cases
934    where PCRE_STUDY_JIT_COMPILE is not used, but it is advisable to change to the
935    new function when convenient.
936    .P
937    This is a typical way in which \fBpcre_study\fP() is used (except that in a
938    real application there should be tests for errors):
939  .sp  .sp
940    pcre_extra *pe;    int rc;
941    pe = pcre_study(    pcre *re;
942      pcre_extra *sd;
943      re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
944      sd = pcre_study(
945      re,             /* result of pcre_compile() */      re,             /* result of pcre_compile() */
946      0,              /* no options exist */      0,              /* no options */
947      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
948  .sp    rc = pcre_exec(   /* see below for details of pcre_exec() options */
949  At present, studying a pattern is useful only for non-anchored patterns that do      re, sd, "subject", 7, 0, 0, ovector, 30);
950  not have a single fixed starting character. A bitmap of possible starting    ...
951  bytes is created.    pcre_free_study(sd);
952      pcre_free(re);
953    .sp
954    Studying a pattern does two things: first, a lower bound for the length of
955    subject string that is needed to match the pattern is computed. This does not
956    mean that there are any strings of that length that match, but it does
957    guarantee that no shorter strings match. The value is used by
958    \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP to avoid wasting time by trying to
959    match strings that are shorter than the lower bound. You can find out the value
960    in a calling program via the \fBpcre_fullinfo()\fP function.
961    .P
962    Studying a pattern is also useful for non-anchored patterns that do not have a
963    single fixed starting character. A bitmap of possible starting bytes is
964    created. This speeds up finding a position in the subject at which to start
965    matching.
966    .P
967    These two optimizations apply to both \fBpcre_exec()\fP and
968    \fBpcre_dfa_exec()\fP. However, they are not used by \fBpcre_exec()\fP if
969    \fBpcre_study()\fP is called with the PCRE_STUDY_JIT_COMPILE option, and
970    just-in-time compiling is successful. The optimizations can be disabled by
971    setting the PCRE_NO_START_OPTIMIZE option when calling \fBpcre_exec()\fP or
972    \fBpcre_dfa_exec()\fP. You might want to do this if your pattern contains
973    callouts or (*MARK) (which cannot be handled by the JIT compiler), and you want
974    to make use of these facilities in cases where matching fails. See the
975    discussion of PCRE_NO_START_OPTIMIZE
976    .\" HTML <a href="#execoptions">
977    .\" </a>
978    below.
979    .\"
980  .  .
981  .  .
982  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
# Line 741  bytes is created. Line 986  bytes is created.
986  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters,
987  digits, or whatever, by reference to a set of tables, indexed by character  digits, or whatever, by reference to a set of tables, indexed by character
988  value. When running in UTF-8 mode, this applies only to characters with codes  value. When running in UTF-8 mode, this applies only to characters with codes
989  less than 128. Higher-valued codes never match escapes such as \ew or \ed, but  less than 128. By default, higher-valued codes never match escapes such as \ew
990  can be tested with \ep if PCRE is built with Unicode character property  or \ed, but they can be tested with \ep if PCRE is built with Unicode character
991  support. The use of locales with Unicode is discouraged. If you are handling  property support. Alternatively, the PCRE_UCP option can be set at compile
992  characters with codes greater than 128, you should either use UTF-8 and  time; this causes \ew and friends to use Unicode property support instead of
993  Unicode, or use locales, but not try to mix the two.  built-in tables. The use of locales with Unicode is discouraged. If you are
994    handling characters with codes greater than 128, you should either use UTF-8
995    and Unicode, or use locales, but not try to mix the two.
996  .P  .P
997  PCRE contains an internal set of tables that are used when the final argument  PCRE contains an internal set of tables that are used when the final argument
998  of \fBpcre_compile()\fP is NULL. These are sufficient for many applications.  of \fBpcre_compile()\fP is NULL. These are sufficient for many applications.
# Line 790  one in which it was compiled. Passing ta Line 1037  one in which it was compiled. Passing ta
1037  below in the section on matching a pattern.  below in the section on matching a pattern.
1038  .  .
1039  .  .
1040    .\" HTML <a name="infoaboutpattern"></a>
1041  .SH "INFORMATION ABOUT A PATTERN"  .SH "INFORMATION ABOUT A PATTERN"
1042  .rs  .rs
1043  .sp  .sp
# Line 821  check against passing an arbitrary memor Line 1069  check against passing an arbitrary memor
1069    size_t length;    size_t length;
1070    rc = pcre_fullinfo(    rc = pcre_fullinfo(
1071      re,               /* result of pcre_compile() */      re,               /* result of pcre_compile() */
1072      pe,               /* result of pcre_study(), or NULL */      sd,               /* result of pcre_study(), or NULL */
1073      PCRE_INFO_SIZE,   /* what is required */      PCRE_INFO_SIZE,   /* what is required */
1074      &length);         /* where to put the data */      &length);         /* where to put the data */
1075  .sp  .sp
# Line 874  table indicating a fixed set of bytes fo Line 1122  table indicating a fixed set of bytes fo
1122  string, a pointer to the table is returned. Otherwise NULL is returned. The  string, a pointer to the table is returned. Otherwise NULL is returned. The
1123  fourth argument should point to an \fBunsigned char *\fP variable.  fourth argument should point to an \fBunsigned char *\fP variable.
1124  .sp  .sp
1125      PCRE_INFO_HASCRORLF
1126    .sp
1127    Return 1 if the pattern contains any explicit matches for CR or LF characters,
1128    otherwise 0. The fourth argument should point to an \fBint\fP variable. An
1129    explicit match is either a literal CR or LF character, or \er or \en.
1130    .sp
1131    PCRE_INFO_JCHANGED    PCRE_INFO_JCHANGED
1132  .sp  .sp
1133  Return 1 if the (?J) option setting is used in the pattern, otherwise 0. The  Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise
1134  fourth argument should point to an \fBint\fP variable. The (?J) internal option  0. The fourth argument should point to an \fBint\fP variable. (?J) and
1135  setting changes the local PCRE_DUPNAMES option.  (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
1136    .sp
1137      PCRE_INFO_JIT
1138    .sp
1139    Return 1 if the pattern was studied with the PCRE_STUDY_JIT_COMPILE option, and
1140    just-in-time compiling was successful. The fourth argument should point to an
1141    \fBint\fP variable. A return value of 0 means that JIT support is not available
1142    in this version of PCRE, or that the pattern was not studied with the
1143    PCRE_STUDY_JIT_COMPILE option, or that the JIT compiler could not handle this
1144    particular pattern. See the
1145    .\" HREF
1146    \fBpcrejit\fP
1147    .\"
1148    documentation for details of what can and cannot be handled.
1149    .sp
1150      PCRE_INFO_JITSIZE
1151    .sp
1152    If the pattern was successfully studied with the PCRE_STUDY_JIT_COMPILE option,
1153    return the size of the JIT compiled code, otherwise return zero. The fourth
1154    argument should point to a \fBsize_t\fP variable.
1155  .sp  .sp
1156    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
1157  .sp  .sp
# Line 890  follows something of variable length. Fo Line 1163  follows something of variable length. Fo
1163  /^a\ed+z\ed+/ the returned value is "z", but for /^a\edz\ed/ the returned value  /^a\ed+z\ed+/ the returned value is "z", but for /^a\edz\ed/ the returned value
1164  is -1.  is -1.
1165  .sp  .sp
1166      PCRE_INFO_MINLENGTH
1167    .sp
1168    If the pattern was studied and a minimum length for matching subject strings
1169    was computed, its value is returned. Otherwise the returned value is -1. The
1170    value is a number of characters, not bytes (this may be relevant in UTF-8
1171    mode). The fourth argument should point to an \fBint\fP variable. A
1172    non-negative value is a lower bound to the length of any matching string. There
1173    may not be any strings of that length that do actually match, but every string
1174    that does match is at least that long.
1175    .sp
1176    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
1177    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
1178    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
# Line 910  entry; both of these return an \fBint\fP Line 1193  entry; both of these return an \fBint\fP
1193  length of the longest name. PCRE_INFO_NAMETABLE returns a pointer to the first  length of the longest name. PCRE_INFO_NAMETABLE returns a pointer to the first
1194  entry of the table (a pointer to \fBchar\fP). The first two bytes of each entry  entry of the table (a pointer to \fBchar\fP). The first two bytes of each entry
1195  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
1196  rest of the entry is the corresponding name, zero terminated. The names are in  rest of the entry is the corresponding name, zero terminated.
1197  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of  .P
1198  their parentheses numbers. For example, consider the following pattern (assume  The names are in alphabetical order. Duplicate names may appear if (?| is used
1199  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  to create multiple groups with the same number, as described in the
1200    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1201    .\" </a>
1202    section on duplicate subpattern numbers
1203    .\"
1204    in the
1205    .\" HREF
1206    \fBpcrepattern\fP
1207    .\"
1208    page. Duplicate names for subpatterns with different numbers are permitted only
1209    if PCRE_DUPNAMES is set. In all cases of duplicate names, they appear in the
1210    table in the order in which they were found in the pattern. In the absence of
1211    (?| this is the order of increasing number; when (?| is used this is not
1212    necessarily the case because later subpatterns may have lower numbers.
1213    .P
1214    As a simple example of the name/number table, consider the following pattern
1215    (assume PCRE_EXTENDED is set, so white space - including newlines - is
1216    ignored):
1217  .sp  .sp
1218  .\" JOIN  .\" JOIN
1219    (?<date> (?<year>(\ed\ed)?\ed\ed) -    (?<date> (?<year>(\ed\ed)?\ed\ed) -
# Line 934  different for each compiled pattern. Line 1234  different for each compiled pattern.
1234  .sp  .sp
1235    PCRE_INFO_OKPARTIAL    PCRE_INFO_OKPARTIAL
1236  .sp  .sp
1237  Return 1 if the pattern can be used for partial matching, otherwise 0. The  Return 1 if the pattern can be used for partial matching with
1238  fourth argument should point to an \fBint\fP variable. The  \fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
1239    \fBint\fP variable. From release 8.00, this always returns 1, because the
1240    restrictions that previously applied to partial matching have been lifted. The
1241  .\" HREF  .\" HREF
1242  \fBpcrepartial\fP  \fBpcrepartial\fP
1243  .\"  .\"
1244  documentation lists the restrictions that apply to patterns when partial  documentation gives details of partial matching.
 matching is used.  
1245  .sp  .sp
1246    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1247  .sp  .sp
# Line 967  For such patterns, the PCRE_ANCHORED bit Line 1268  For such patterns, the PCRE_ANCHORED bit
1268  .sp  .sp
1269    PCRE_INFO_SIZE    PCRE_INFO_SIZE
1270  .sp  .sp
1271  Return the size of the compiled pattern, that is, the value that was passed as  Return the size of the compiled pattern. The fourth argument should point to a
1272  the argument to \fBpcre_malloc()\fP when PCRE was getting memory in which to  \fBsize_t\fP variable. This value does not include the size of the \fBpcre\fP
1273  place the compiled data. The fourth argument should point to a \fBsize_t\fP  structure that is returned by \fBpcre_compile()\fP. The value that is passed as
1274  variable.  the argument to \fBpcre_malloc()\fP when \fBpcre_compile()\fP is getting memory
1275    in which to place the compiled data is the value returned by this option plus
1276    the size of the \fBpcre\fP structure. Studying a compiled pattern, with or
1277    without JIT, does not alter the value returned by this option.
1278  .sp  .sp
1279    PCRE_INFO_STUDYSIZE    PCRE_INFO_STUDYSIZE
1280  .sp  .sp
1281  Return the size of the data block pointed to by the \fIstudy_data\fP field in  Return the size of the data block pointed to by the \fIstudy_data\fP field in a
1282  a \fBpcre_extra\fP block. That is, it is the value that was passed to  \fBpcre_extra\fP block. If \fBpcre_extra\fP is NULL, or there is no study data,
1283  \fBpcre_malloc()\fP when PCRE was getting memory into which to place the data  zero is returned. The fourth argument should point to a \fBsize_t\fP variable.
1284  created by \fBpcre_study()\fP. The fourth argument should point to a  The \fIstudy_data\fP field is set by \fBpcre_study()\fP to record information
1285  \fBsize_t\fP variable.  that will speed up matching (see the section entitled
1286    .\" HTML <a href="#studyingapattern">
1287    .\" </a>
1288    "Studying a pattern"
1289    .\"
1290    above). The format of the \fIstudy_data\fP block is private, but its length
1291    is made available via this option so that it can be saved and restored (see the
1292    .\" HREF
1293    \fBpcreprecompile\fP
1294    .\"
1295    documentation for details).
1296  .  .
1297  .  .
1298  .SH "OBSOLETE INFO FUNCTION"  .SH "OBSOLETE INFO FUNCTION"
# Line 1039  is different. (This seems a highly unlik Line 1353  is different. (This seems a highly unlik
1353  .P  .P
1354  The function \fBpcre_exec()\fP is called to match a subject string against a  The function \fBpcre_exec()\fP is called to match a subject string against a
1355  compiled pattern, which is passed in the \fIcode\fP argument. If the  compiled pattern, which is passed in the \fIcode\fP argument. If the
1356  pattern has been studied, the result of the study should be passed in the  pattern was studied, the result of the study should be passed in the
1357  \fIextra\fP argument. This function is the main matching facility of the  \fIextra\fP argument. You can call \fBpcre_exec()\fP with the same \fIcode\fP
1358  library, and it operates in a Perl-like manner. For specialist use there is  and \fIextra\fP arguments as many times as you like, in order to match
1359  also an alternative matching function, which is described  different subject strings with the same pattern.
1360    .P
1361    This function is the main matching facility of the library, and it operates in
1362    a Perl-like manner. For specialist use there is also an alternative matching
1363    function, which is described
1364  .\" HTML <a href="#dfamatch">  .\" HTML <a href="#dfamatch">
1365  .\" </a>  .\" </a>
1366  below  below
# Line 1073  Here is an example of a simple call to \ Line 1391  Here is an example of a simple call to \
1391      ovector,        /* vector of integers for substring information */      ovector,        /* vector of integers for substring information */
1392      30);            /* number of elements (NOT size in bytes) */      30);            /* number of elements (NOT size in bytes) */
1393  .  .
1394    .
1395  .\" HTML <a name="extradata"></a>  .\" HTML <a name="extradata"></a>
1396  .SS "Extra data for \fBpcre_exec()\fR"  .SS "Extra data for \fBpcre_exec()\fR"
1397  .rs  .rs
# Line 1085  fields (not necessarily in this order): Line 1404  fields (not necessarily in this order):
1404  .sp  .sp
1405    unsigned long int \fIflags\fP;    unsigned long int \fIflags\fP;
1406    void *\fIstudy_data\fP;    void *\fIstudy_data\fP;
1407      void *\fIexecutable_jit\fP;
1408    unsigned long int \fImatch_limit\fP;    unsigned long int \fImatch_limit\fP;
1409    unsigned long int \fImatch_limit_recursion\fP;    unsigned long int \fImatch_limit_recursion\fP;
1410    void *\fIcallout_data\fP;    void *\fIcallout_data\fP;
1411    const unsigned char *\fItables\fP;    const unsigned char *\fItables\fP;
1412      unsigned char **\fImark\fP;
1413  .sp  .sp
1414  The \fIflags\fP field is a bitmap that specifies which of the other fields  The \fIflags\fP field is a bitmap that specifies which of the other fields
1415  are set. The flag bits are:  are set. The flag bits are:
1416  .sp  .sp
1417    PCRE_EXTRA_STUDY_DATA    PCRE_EXTRA_STUDY_DATA
1418      PCRE_EXTRA_EXECUTABLE_JIT
1419    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1420    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1421    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1422    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1423      PCRE_EXTRA_MARK
1424  .sp  .sp
1425  Other flag bits should be set to zero. The \fIstudy_data\fP field is set in the  Other flag bits should be set to zero. The \fIstudy_data\fP field and sometimes
1426  \fBpcre_extra\fP block that is returned by \fBpcre_study()\fP, together with  the \fIexecutable_jit\fP field are set in the \fBpcre_extra\fP block that is
1427  the appropriate flag bit. You should not set this yourself, but you may add to  returned by \fBpcre_study()\fP, together with the appropriate flag bits. You
1428  the block by setting the other fields and their corresponding flag bits.  should not set these yourself, but you may add to the block by setting the
1429    other fields and their corresponding flag bits.
1430  .P  .P
1431  The \fImatch_limit\fP field provides a means of preventing PCRE from using up a  The \fImatch_limit\fP field provides a means of preventing PCRE from using up a
1432  vast amount of resources when running patterns that are not going to match,  vast amount of resources when running patterns that are not going to match,
1433  but which have a very large number of possibilities in their search trees. The  but which have a very large number of possibilities in their search trees. The
1434  classic example is the use of nested unlimited repeats.  classic example is a pattern that uses nested unlimited repeats.
1435  .P  .P
1436  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly  Internally, \fBpcre_exec()\fP uses a function called \fBmatch()\fP, which it
1437  (sometimes recursively). The limit set by \fImatch_limit\fP is imposed on the  calls repeatedly (sometimes recursively). The limit set by \fImatch_limit\fP is
1438  number of times this function is called during a match, which has the effect of  imposed on the number of times this function is called during a match, which
1439  limiting the amount of backtracking that can take place. For patterns that are  has the effect of limiting the amount of backtracking that can take place. For
1440  not anchored, the count restarts from zero for each position in the subject  patterns that are not anchored, the count restarts from zero for each position
1441  string.  in the subject string.
1442    .P
1443    When \fBpcre_exec()\fP is called with a pattern that was successfully studied
1444    with the PCRE_STUDY_JIT_COMPILE option, the way that the matching is executed
1445    is entirely different. However, there is still the possibility of runaway
1446    matching that goes on for a very long time, and so the \fImatch_limit\fP value
1447    is also used in this case (but in a different way) to limit how long the
1448    matching can continue.
1449  .P  .P
1450  The default value for the limit can be set when PCRE is built; the default  The default value for the limit can be set when PCRE is built; the default
1451  default is 10 million, which handles all but the most extreme cases. You can  default is 10 million, which handles all but the most extreme cases. You can
# Line 1129  limits the depth of recursion. The recur Line 1460  limits the depth of recursion. The recur
1460  total number of calls, because not all calls to \fBmatch()\fP are recursive.  total number of calls, because not all calls to \fBmatch()\fP are recursive.
1461  This limit is of use only if it is set smaller than \fImatch_limit\fP.  This limit is of use only if it is set smaller than \fImatch_limit\fP.
1462  .P  .P
1463  Limiting the recursion depth limits the amount of stack that can be used, or,  Limiting the recursion depth limits the amount of machine stack that can be
1464  when PCRE has been compiled to use memory on the heap instead of the stack, the  used, or, when PCRE has been compiled to use memory on the heap instead of the
1465  amount of heap memory that can be used.  stack, the amount of heap memory that can be used. This limit is not relevant,
1466    and is ignored, if the pattern was successfully studied with
1467    PCRE_STUDY_JIT_COMPILE.
1468  .P  .P
1469  The default value for \fImatch_limit_recursion\fP can be set when PCRE is  The default value for \fImatch_limit_recursion\fP can be set when PCRE is
1470  built; the default default is the same value as the default for  built; the default default is the same value as the default for
# Line 1140  with a \fBpcre_extra\fP block in which \ Line 1473  with a \fBpcre_extra\fP block in which \
1473  PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the \fIflags\fP field. If the limit  PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the \fIflags\fP field. If the limit
1474  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1475  .P  .P
1476  The \fIpcre_callout\fP field is used in conjunction with the "callout" feature,  The \fIcallout_data\fP field is used in conjunction with the "callout" feature,
1477  which is described in the  and is described in the
1478  .\" HREF  .\" HREF
1479  \fBpcrecallout\fP  \fBpcrecallout\fP
1480  .\"  .\"
# Line 1160  called. See the Line 1493  called. See the
1493  \fBpcreprecompile\fP  \fBpcreprecompile\fP
1494  .\"  .\"
1495  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1496    .P
1497    If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1498    be set to point to a \fBchar *\fP variable. If the pattern contains any
1499    backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1500    a name to pass back, a pointer to the name string (zero terminated) is placed
1501    in the variable pointed to by the \fImark\fP field. The names are within the
1502    compiled pattern; if you wish to retain such a name you must copy it before
1503    freeing the memory of a compiled pattern. If there is no name to pass back, the
1504    variable pointed to by the \fImark\fP field set to NULL. For details of the
1505    backtracking control verbs, see the section entitled
1506    .\" HTML <a href="pcrepattern#backtrackcontrol">
1507    .\" </a>
1508    "Backtracking control"
1509    .\"
1510    in the
1511    .\" HREF
1512    \fBpcrepattern\fP
1513    .\"
1514    documentation.
1515    .
1516  .  .
1517    .\" HTML <a name="execoptions"></a>
1518  .SS "Option bits for \fBpcre_exec()\fP"  .SS "Option bits for \fBpcre_exec()\fP"
1519  .rs  .rs
1520  .sp  .sp
1521  The unused bits of the \fIoptions\fP argument for \fBpcre_exec()\fP must be  The unused bits of the \fIoptions\fP argument for \fBpcre_exec()\fP must be
1522  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
1523  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1524    PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
1525    PCRE_PARTIAL_HARD.
1526    .P
1527    If the pattern was successfully studied with the PCRE_STUDY_JIT_COMPILE option,
1528    the only supported options for JIT execution are PCRE_NO_UTF8_CHECK,
1529    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and PCRE_NOTEMPTY_ATSTART. Note in
1530    particular that partial matching is not supported. If an unsupported option is
1531    used, JIT execution is disabled and the normal interpretive code in
1532    \fBpcre_exec()\fP is run.
1533  .sp  .sp
1534    PCRE_ANCHORED    PCRE_ANCHORED
1535  .sp  .sp
# Line 1175  matching position. If a pattern was comp Line 1538  matching position. If a pattern was comp
1538  to be anchored by virtue of its contents, it cannot be made unachored at  to be anchored by virtue of its contents, it cannot be made unachored at
1539  matching time.  matching time.
1540  .sp  .sp
1541      PCRE_BSR_ANYCRLF
1542      PCRE_BSR_UNICODE
1543    .sp
1544    These options (which are mutually exclusive) control what the \eR escape
1545    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
1546    match any Unicode newline sequence. These options override the choice that was
1547    made or defaulted when the pattern was compiled.
1548    .sp
1549    PCRE_NEWLINE_CR    PCRE_NEWLINE_CR
1550    PCRE_NEWLINE_LF    PCRE_NEWLINE_LF
1551    PCRE_NEWLINE_CRLF    PCRE_NEWLINE_CRLF
# Line 1186  the pattern was compiled. For details, s Line 1557  the pattern was compiled. For details, s
1557  \fBpcre_compile()\fP above. During matching, the newline choice affects the  \fBpcre_compile()\fP above. During matching, the newline choice affects the
1558  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1559  the way the match position is advanced after a match failure for an unanchored  the way the match position is advanced after a match failure for an unanchored
1560  pattern. When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is  pattern.
1561  set, and a match attempt fails when the current position is at a CRLF sequence,  .P
1562  the match position is advanced by two characters instead of one, in other  When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a
1563  words, to after the CRLF.  match attempt for an unanchored pattern fails when the current position is at a
1564    CRLF sequence, and the pattern contains no explicit matches for CR or LF
1565    characters, the match position is advanced by two characters instead of one, in
1566    other words, to after the CRLF.
1567    .P
1568    The above rule is a compromise that makes the most common cases work as
1569    expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
1570    set), it does not match the string "\er\enA" because, after failing at the
1571    start, it skips both the CR and the LF before retrying. However, the pattern
1572    [\er\en]A does match that string, because it contains an explicit CR or LF
1573    reference, and so advances only by one character after the first failure.
1574    .P
1575    An explicit match for CR of LF is either a literal appearance of one of those
1576    characters, or one of the \er or \en escape sequences. Implicit matches such as
1577    [^X] do not count, nor does \es (which includes CR and LF in the characters
1578    that it matches).
1579    .P
1580    Notwithstanding the above, anomalous effects may still occur when CRLF is a
1581    valid newline sequence and explicit \er or \en escapes appear in the pattern.
1582  .sp  .sp
1583    PCRE_NOTBOL    PCRE_NOTBOL
1584  .sp  .sp
# Line 1215  match the empty string, the entire match Line 1604  match the empty string, the entire match
1604  .sp  .sp
1605    a?b?    a?b?
1606  .sp  .sp
1607  is applied to a string not beginning with "a" or "b", it matches the empty  is applied to a string not beginning with "a" or "b", it matches an empty
1608  string at the start of the subject. With PCRE_NOTEMPTY set, this match is not  string at the start of the subject. With PCRE_NOTEMPTY set, this match is not
1609  valid, so PCRE searches further into the string for occurrences of "a" or "b".  valid, so PCRE searches further into the string for occurrences of "a" or "b".
1610  .P  .sp
1611  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case    PCRE_NOTEMPTY_ATSTART
1612  of a pattern match of the empty string within its \fBsplit()\fP function, and  .sp
1613  when using the /g modifier. It is possible to emulate Perl's behaviour after  This is like PCRE_NOTEMPTY, except that an empty string match that is not at
1614  matching a null string by first trying the match again at the same offset with  the start of the subject is permitted. If the pattern is anchored, such a match
1615  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the  can occur only if the pattern contains \eK.
1616  starting offset (see below) and trying an ordinary match again. There is some  .P
1617  code that demonstrates how to do this in the \fIpcredemo.c\fP sample program.  Perl has no direct equivalent of PCRE_NOTEMPTY or PCRE_NOTEMPTY_ATSTART, but it
1618    does make a special case of a pattern match of the empty string within its
1619    \fBsplit()\fP function, and when using the /g modifier. It is possible to
1620    emulate Perl's behaviour after matching a null string by first trying the match
1621    again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
1622    if that fails, by advancing the starting offset (see below) and trying an
1623    ordinary match again. There is some code that demonstrates how to do this in
1624    the
1625    .\" HREF
1626    \fBpcredemo\fP
1627    .\"
1628    sample program. In the most general case, you have to check to see if the
1629    newline convention recognizes CRLF as a newline, and if so, and the current
1630    character is CR followed by LF, advance the starting offset by two characters
1631    instead of one.
1632    .sp
1633      PCRE_NO_START_OPTIMIZE
1634    .sp
1635    There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1636    a match, in order to speed up the process. For example, if it is known that an
1637    unanchored match must start with a specific character, it searches the subject
1638    for that character, and fails immediately if it cannot find it, without
1639    actually running the main matching function. This means that a special item
1640    such as (*COMMIT) at the start of a pattern is not considered until after a
1641    suitable starting point for the match has been found. When callouts or (*MARK)
1642    items are in use, these "start-up" optimizations can cause them to be skipped
1643    if the pattern is never actually used. The start-up optimizations are in effect
1644    a pre-scan of the subject that takes place before the pattern is run.
1645    .P
1646    The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
1647    causing performance to suffer, but ensuring that in cases where the result is
1648    "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
1649    are considered at every possible starting position in the subject string. If
1650    PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
1651    time.
1652    .P
1653    Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
1654    Consider the pattern
1655    .sp
1656      (*COMMIT)ABC
1657    .sp
1658    When this is compiled, PCRE records the fact that a match must start with the
1659    character "A". Suppose the subject string is "DEFABC". The start-up
1660    optimization scans along the subject, finds "A" and runs the first match
1661    attempt from there. The (*COMMIT) item means that the pattern must match the
1662    current starting position, which in this case, it does. However, if the same
1663    match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
1664    subject string does not happen. The first match attempt is run starting from
1665    "D" and when this fails, (*COMMIT) prevents any further matches being tried, so
1666    the overall result is "no match". If the pattern is studied, more start-up
1667    optimizations may be used. For example, a minimum length for the subject may be
1668    recorded. Consider the pattern
1669    .sp
1670      (*MARK:A)(X|Y)
1671    .sp
1672    The minimum length for a match is one character. If the subject is "ABC", there
1673    will be attempts to match "ABC", "BC", "C", and then finally an empty string.
1674    If the pattern is studied, the final attempt does not take place, because PCRE
1675    knows that the subject is too short, and so the (*MARK) is never encountered.
1676    In this case, studying the pattern does not affect the overall match result,
1677    which is still "no match", but it does affect the auxiliary information that is
1678    returned.
1679  .sp  .sp
1680    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1681  .sp  .sp
1682  When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8  When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8
1683  string is automatically checked when \fBpcre_exec()\fP is subsequently called.  string is automatically checked when \fBpcre_exec()\fP is subsequently called.
1684  The value of \fIstartoffset\fP is also checked to ensure that it points to the  The value of \fIstartoffset\fP is also checked to ensure that it points to the
1685  start of a UTF-8 character. If an invalid UTF-8 sequence of bytes is found,  start of a UTF-8 character. There is a discussion about the validity of UTF-8
1686  \fBpcre_exec()\fP returns the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP  strings in the
1687  contains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.  .\" HTML <a href="pcre.html#utf8strings">
1688    .\" </a>
1689    section on UTF-8 support
1690    .\"
1691    in the main
1692    .\" HREF
1693    \fBpcre\fP
1694    .\"
1695    page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns
1696    the error PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is
1697    a truncated UTF-8 character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
1698    both cases, information about the precise nature of the error may also be
1699    returned (see the descriptions of these errors in the section entitled \fIError
1700    return values from\fP \fBpcre_exec()\fP
1701    .\" HTML <a href="#errorlist">
1702    .\" </a>
1703    below).
1704    .\"
1705    If \fIstartoffset\fP contains a value that does not point to the start of a
1706    UTF-8 character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
1707    returned.
1708  .P  .P
1709  If you already know that your subject is valid, and you want to skip these  If you already know that your subject is valid, and you want to skip these
1710  checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when  checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when
1711  calling \fBpcre_exec()\fP. You might want to do this for the second and  calling \fBpcre_exec()\fP. You might want to do this for the second and
1712  subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find  subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find
1713  all the matches in a single subject string. However, you should be sure that  all the matches in a single subject string. However, you should be sure that
1714  the value of \fIstartoffset\fP points to the start of a UTF-8 character. When  the value of \fIstartoffset\fP points to the start of a UTF-8 character (or the
1715  PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid UTF-8 string as a  end of the subject). When PCRE_NO_UTF8_CHECK is set, the effect of passing an
1716  subject, or a value of \fIstartoffset\fP that does not point to the start of a  invalid UTF-8 string as a subject or an invalid value of \fIstartoffset\fP is
1717  UTF-8 character, is undefined. Your program may crash.  undefined. Your program may crash.
1718  .sp  .sp
1719    PCRE_PARTIAL    PCRE_PARTIAL_HARD
1720  .sp    PCRE_PARTIAL_SOFT
1721  This option turns on the partial matching feature. If the subject string fails  .sp
1722  to match the pattern, but at some point during the matching process the end of  These options turn on the partial matching feature. For backwards
1723  the subject was reached (that is, the subject partially matches the pattern and  compatibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial match
1724  the failure to match occurred only because there were not enough subject  occurs if the end of the subject string is reached successfully, but there are
1725  characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of  not enough subject characters to complete the match. If this happens when
1726  PCRE_ERROR_NOMATCH. When PCRE_PARTIAL is used, there are restrictions on what  PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set, matching continues by
1727  may appear in the pattern. These are discussed in the  testing any remaining alternatives. Only if no complete match can be found is
1728    PCRE_ERROR_PARTIAL returned instead of PCRE_ERROR_NOMATCH. In other words,
1729    PCRE_PARTIAL_SOFT says that the caller is prepared to handle a partial match,
1730    but only if no complete match can be found.
1731    .P
1732    If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
1733    partial match is found, \fBpcre_exec()\fP immediately returns
1734    PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
1735    when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
1736    important that an alternative complete match.
1737    .P
1738    In both cases, the portion of the string that was inspected when the partial
1739    match was found is set as the first matching string. There is a more detailed
1740    discussion of partial and multi-segment matching, with examples, in the
1741  .\" HREF  .\" HREF
1742  \fBpcrepartial\fP  \fBpcrepartial\fP
1743  .\"  .\"
1744  documentation.  documentation.
1745  .  .
1746    .
1747  .SS "The string to be matched by \fBpcre_exec()\fP"  .SS "The string to be matched by \fBpcre_exec()\fP"
1748  .rs  .rs
1749  .sp  .sp
1750  The subject string is passed to \fBpcre_exec()\fP as a pointer in  The subject string is passed to \fBpcre_exec()\fP as a pointer in
1751  \fIsubject\fP, a length in \fIlength\fP, and a starting byte offset in  \fIsubject\fP, a length (in bytes) in \fIlength\fP, and a starting byte offset
1752  \fIstartoffset\fP. In UTF-8 mode, the byte offset must point to the start of a  in \fIstartoffset\fP. If this is negative or greater than the length of the
1753  UTF-8 character. Unlike the pattern string, the subject may contain binary zero  subject, \fBpcre_exec()\fP returns PCRE_ERROR_BADOFFSET. When the starting
1754  bytes. When the starting offset is zero, the search for a match starts at the  offset is zero, the search for a match starts at the beginning of the subject,
1755  beginning of the subject, and this is by far the most common case.  and this is by far the most common case. In UTF-8 mode, the byte offset must
1756    point to the start of a UTF-8 character (or the end of the subject). Unlike the
1757    pattern string, the subject may contain binary zero bytes.
1758  .P  .P
1759  A non-zero starting offset is useful when searching for another match in the  A non-zero starting offset is useful when searching for another match in the
1760  same subject by calling \fBpcre_exec()\fP again after a previous success.  same subject by calling \fBpcre_exec()\fP again after a previous success.
# Line 1288  start of the subject, which is deemed to Line 1774  start of the subject, which is deemed to
1774  set to 4, it finds the second occurrence of "iss" because it is able to look  set to 4, it finds the second occurrence of "iss" because it is able to look
1775  behind the starting point to discover that it is preceded by a letter.  behind the starting point to discover that it is preceded by a letter.
1776  .P  .P
1777    Finding all the matches in a subject is tricky when the pattern can match an
1778    empty string. It is possible to emulate Perl's /g behaviour by first trying the
1779    match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
1780    PCRE_ANCHORED options, and then if that fails, advancing the starting offset
1781    and trying an ordinary match again. There is some code that demonstrates how to
1782    do this in the
1783    .\" HREF
1784    \fBpcredemo\fP
1785    .\"
1786    sample program. In the most general case, you have to check to see if the
1787    newline convention recognizes CRLF as a newline, and if so, and the current
1788    character is CR followed by LF, advance the starting offset by two characters
1789    instead of one.
1790    .P
1791  If a non-zero starting offset is passed when the pattern is anchored, one  If a non-zero starting offset is passed when the pattern is anchored, one
1792  attempt to match at the given offset is made. This can only succeed if the  attempt to match at the given offset is made. This can only succeed if the
1793  pattern does not require the match to be at the start of the subject.  pattern does not require the match to be at the start of the subject.
1794  .  .
1795    .
1796  .SS "How \fBpcre_exec()\fP returns captured substrings"  .SS "How \fBpcre_exec()\fP returns captured substrings"
1797  .rs  .rs
1798  .sp  .sp
# Line 1302  pattern. Following the usage in Jeffrey Line 1803  pattern. Following the usage in Jeffrey
1803  a fragment of a pattern that picks out a substring. PCRE supports several other  a fragment of a pattern that picks out a substring. PCRE supports several other
1804  kinds of parenthesized subpattern that do not cause substrings to be captured.  kinds of parenthesized subpattern that do not cause substrings to be captured.
1805  .P  .P
1806  Captured substrings are returned to the caller via a vector of integer offsets  Captured substrings are returned to the caller via a vector of integers whose
1807  whose address is passed in \fIovector\fP. The number of elements in the vector  address is passed in \fIovector\fP. The number of elements in the vector is
1808  is passed in \fIovecsize\fP, which must be a non-negative number. \fBNote\fP:  passed in \fIovecsize\fP, which must be a non-negative number. \fBNote\fP: this
1809  this argument is NOT the size of \fIovector\fP in bytes.  argument is NOT the size of \fIovector\fP in bytes.
1810  .P  .P
1811  The first two-thirds of the vector is used to pass back captured substrings,  The first two-thirds of the vector is used to pass back captured substrings,
1812  each substring using a pair of integers. The remaining third of the vector is  each substring using a pair of integers. The remaining third of the vector is
1813  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
1814  and is not available for passing back information. The length passed in  and is not available for passing back information. The number passed in
1815  \fIovecsize\fP should always be a multiple of three. If it is not, it is  \fIovecsize\fP should always be a multiple of three. If it is not, it is
1816  rounded down.  rounded down.
1817  .P  .P
1818  When a match is successful, information about captured substrings is returned  When a match is successful, information about captured substrings is returned
1819  in pairs of integers, starting at the beginning of \fIovector\fP, and  in pairs of integers, starting at the beginning of \fIovector\fP, and
1820  continuing up to two-thirds of its length at the most. The first element of a  continuing up to two-thirds of its length at the most. The first element of
1821  pair is set to the offset of the first character in a substring, and the second  each pair is set to the byte offset of the first character in a substring, and
1822  is set to the offset of the first character after the end of a substring. The  the second is set to the byte offset of the first character after the end of a
1823  first pair, \fIovector[0]\fP and \fIovector[1]\fP, identify the portion of the  substring. \fBNote\fP: these values are always byte offsets, even in UTF-8
1824  subject string matched by the entire pattern. The next pair is used for the  mode. They are not character counts.
1825  first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fP  .P
1826  is one more than the highest numbered pair that has been set. For example, if  The first pair of integers, \fIovector[0]\fP and \fIovector[1]\fP, identify the
1827  two substrings have been captured, the returned value is 3. If there are no  portion of the subject string matched by the entire pattern. The next pair is
1828  capturing subpatterns, the return value from a successful match is 1,  used for the first capturing subpattern, and so on. The value returned by
1829  indicating that just the first pair of offsets has been set.  \fBpcre_exec()\fP is one more than the highest numbered pair that has been set.
1830    For example, if two substrings have been captured, the returned value is 3. If
1831    there are no capturing subpatterns, the return value from a successful match is
1832    1, indicating that just the first pair of offsets has been set.
1833  .P  .P
1834  If a capturing subpattern is matched repeatedly, it is the last portion of the  If a capturing subpattern is matched repeatedly, it is the last portion of the
1835  string that it matched that is returned.  string that it matched that is returned.
1836  .P  .P
1837  If the vector is too small to hold all the captured substring offsets, it is  If the vector is too small to hold all the captured substring offsets, it is
1838  used as far as possible (up to two-thirds of its length), and the function  used as far as possible (up to two-thirds of its length), and the function
1839  returns a value of zero. In particular, if the substring offsets are not of  returns a value of zero. If neither the actual string matched not any captured
1840  interest, \fBpcre_exec()\fP may be called with \fIovector\fP passed as NULL and  substrings are of interest, \fBpcre_exec()\fP may be called with \fIovector\fP
1841  \fIovecsize\fP as zero. However, if the pattern contains back references and  passed as NULL and \fIovecsize\fP as zero. However, if the pattern contains
1842  the \fIovector\fP is not big enough to remember the related substrings, PCRE  back references and the \fIovector\fP is not big enough to remember the related
1843  has to get additional memory for use during matching. Thus it is usually  substrings, PCRE has to get additional memory for use during matching. Thus it
1844  advisable to supply an \fIovector\fP.  is usually advisable to supply an \fIovector\fP of reasonable size.
1845    .P
1846    There are some cases where zero is returned (indicating vector overflow) when
1847    in fact the vector is exactly the right size for the final match. For example,
1848    consider the pattern
1849    .sp
1850      (a)(?:(b)c|bd)
1851    .sp
1852    If a vector of 6 elements (allowing for only 1 captured substring) is given
1853    with subject string "abd", \fBpcre_exec()\fP will try to set the second
1854    captured string, thereby recording a vector overflow, before failing to match
1855    "c" and backing up to try the second alternative. The zero return, however,
1856    does correctly indicate that the maximum number of slots (namely 2) have been
1857    filled. In similar cases where there is temporary overflow, but the final
1858    number of used slots is actually less than the maximum, a non-zero value is
1859    returned.
1860  .P  .P
1861  The \fBpcre_info()\fP function can be used to find out how many capturing  The \fBpcre_fullinfo()\fP function can be used to find out how many capturing
1862  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1863  \fIovector\fP that will allow for \fIn\fP captured substrings, in addition to  \fIovector\fP that will allow for \fIn\fP captured substrings, in addition to
1864  the offsets of the substring matched by the whole pattern, is (\fIn\fP+1)*3.  the offsets of the substring matched by the whole pattern, is (\fIn\fP+1)*3.
# Line 1355  Offset values that correspond to unused Line 1874  Offset values that correspond to unused
1874  expression are also set to -1. For example, if the string "abc" is matched  expression are also set to -1. For example, if the string "abc" is matched
1875  against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The  against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
1876  return from the function is 2, because the highest used capturing subpattern  return from the function is 2, because the highest used capturing subpattern
1877  number is 1. However, you can refer to the offsets for the second and third  number is 1, and the offsets for for the second and third capturing subpatterns
1878  capturing subpatterns if you wish (assuming the vector is large enough, of  (assuming the vector is large enough, of course) are set to -1.
1879  course).  .P
1880    \fBNote\fP: Elements in the first two-thirds of \fIovector\fP that do not
1881    correspond to capturing parentheses in the pattern are never changed. That is,
1882    if a pattern contains \fIn\fP capturing parentheses, no more than
1883    \fIovector[0]\fP to \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other
1884    elements (in the first two-thirds) retain whatever values they previously had.
1885  .P  .P
1886  Some convenience functions are provided for extracting the captured substrings  Some convenience functions are provided for extracting the captured substrings
1887  as separate strings. These are described below.  as separate strings. These are described below.
1888  .  .
1889    .
1890  .\" HTML <a name="errorlist"></a>  .\" HTML <a name="errorlist"></a>
1891  .SS "Error return values from \fBpcre_exec()\fP"  .SS "Error return values from \fBpcre_exec()\fP"
1892  .rs  .rs
# Line 1403  If a pattern contains back references, b Line 1928  If a pattern contains back references, b
1928  gets a block of memory at the start of matching to use for this purpose. If the  gets a block of memory at the start of matching to use for this purpose. If the
1929  call via \fBpcre_malloc()\fP fails, this error is given. The memory is  call via \fBpcre_malloc()\fP fails, this error is given. The memory is
1930  automatically freed at the end of matching.  automatically freed at the end of matching.
1931    .P
1932    This error is also given if \fBpcre_stack_malloc()\fP fails in
1933    \fBpcre_exec()\fP. This can happen only when PCRE has been compiled with
1934    \fB--disable-stack-for-recursion\fP.
1935  .sp  .sp
1936    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1937  .sp  .sp
# Line 1427  documentation for details. Line 1956  documentation for details.
1956  .sp  .sp
1957    PCRE_ERROR_BADUTF8        (-10)    PCRE_ERROR_BADUTF8        (-10)
1958  .sp  .sp
1959  A string that contains an invalid UTF-8 byte sequence was passed as a subject.  A string that contains an invalid UTF-8 byte sequence was passed as a subject,
1960    and the PCRE_NO_UTF8_CHECK option was not set. If the size of the output vector
1961    (\fIovecsize\fP) is at least 2, the byte offset to the start of the the invalid
1962    UTF-8 character is placed in the first element, and a reason code is placed in
1963    the second element. The reason codes are listed in the
1964    .\" HTML <a href="#badutf8reasons">
1965    .\" </a>
1966    following section.
1967    .\"
1968    For backward compatibility, if PCRE_PARTIAL_HARD is set and the problem is a
1969    truncated UTF-8 character at the end of the subject (reason codes 1 to 5),
1970    PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
1971  .sp  .sp
1972    PCRE_ERROR_BADUTF8_OFFSET (-11)    PCRE_ERROR_BADUTF8_OFFSET (-11)
1973  .sp  .sp
1974  The UTF-8 byte sequence that was passed as a subject was valid, but the value  The UTF-8 byte sequence that was passed as a subject was checked and found to
1975  of \fIstartoffset\fP did not point to the beginning of a UTF-8 character.  be valid (the PCRE_NO_UTF8_CHECK option was not set), but the value of
1976    \fIstartoffset\fP did not point to the beginning of a UTF-8 character or the
1977    end of the subject.
1978  .sp  .sp
1979    PCRE_ERROR_PARTIAL        (-12)    PCRE_ERROR_PARTIAL        (-12)
1980  .sp  .sp
# Line 1444  documentation for details of partial mat Line 1986  documentation for details of partial mat
1986  .sp  .sp
1987    PCRE_ERROR_BADPARTIAL     (-13)    PCRE_ERROR_BADPARTIAL     (-13)
1988  .sp  .sp
1989  The PCRE_PARTIAL option was used with a compiled pattern containing items that  This code is no longer in use. It was formerly returned when the PCRE_PARTIAL
1990  are not supported for partial matching. See the  option was used with a compiled pattern containing items that were not
1991  .\" HREF  supported for partial matching. From release 8.00 onwards, there are no
1992  \fBpcrepartial\fP  restrictions on partial matching.
 .\"  
 documentation for details of partial matching.  
1993  .sp  .sp
1994    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
1995  .sp  .sp
# Line 1466  The internal recursion limit, as specifi Line 2006  The internal recursion limit, as specifi
2006  field in a \fBpcre_extra\fP structure (or defaulted) was reached. See the  field in a \fBpcre_extra\fP structure (or defaulted) was reached. See the
2007  description above.  description above.
2008  .sp  .sp
   PCRE_ERROR_NULLWSLIMIT    (-22)  
 .sp  
 When a parenthesized subpattern that can match an empty substring is repeated  
 with an unbounded upper limit, the subject position at the start of the group  
 must be remembered, so that a test for an empty string can be made when the end  
 of the group is reached. The repetition loop is automatically terminated when  
 an empty string is matched.  
 .P  
 Some workspace is required for remembering the starting position. For most  
 capturing subpatterns, an internal recursive call of the match() function is  
 used, and in this case, the workspace is taken from the runtime stack. However,  
 for non-capturing subpatterns, this is not available. Instead, some fixed  
 workspace (taken from the top-level stack) is used. If it runs out, the  
 PCRE_ERROR_NULLWSLIMIT error is given. The size of the fixed workspace allows  
 for up to 1000 repetitions of a non-capturing subpattern that might match an  
 empty string. If this limit is a problem for you, you can sometimes get round  
 it by changing a non-capturing subpattern into a capturing one, but that will  
 increase the amount of runtime stack that is used.  
 .sp  
2009    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
2010  .sp  .sp
2011  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
2012    .sp
2013      PCRE_ERROR_BADOFFSET      (-24)
2014    .sp
2015    The value of \fIstartoffset\fP was negative or greater than the length of the
2016    subject, that is, the value in \fIlength\fP.
2017    .sp
2018      PCRE_ERROR_SHORTUTF8      (-25)
2019    .sp
2020    This error is returned instead of PCRE_ERROR_BADUTF8 when the subject string
2021    ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD option is set.
2022    Information about the failure is returned as for PCRE_ERROR_BADUTF8. It is in
2023    fact sufficient to detect this case, but this special error code for
2024    PCRE_PARTIAL_HARD precedes the implementation of returned information; it is
2025    retained for backwards compatibility.
2026    .sp
2027      PCRE_ERROR_RECURSELOOP    (-26)
2028    .sp
2029    This error is returned when \fBpcre_exec()\fP detects a recursion loop within
2030    the pattern. Specifically, it means that either the whole pattern or a
2031    subpattern has been called recursively for the second time at the same position
2032    in the subject string. Some simple patterns that might do this are detected and
2033    faulted at compile time, but more complicated cases, in particular mutual
2034    recursions between two different subpatterns, cannot be detected until run
2035    time.
2036    .sp
2037      PCRE_ERROR_JIT_STACKLIMIT (-27)
2038    .sp
2039    This error is returned when a pattern that was successfully studied using the
2040    PCRE_STUDY_JIT_COMPILE option is being matched, but the memory available for
2041    the just-in-time processing stack is not large enough. See the
2042    .\" HREF
2043    \fBpcrejit\fP
2044    .\"
2045    documentation for more details.
2046  .P  .P
2047  Error numbers -16 to -20 are not used by \fBpcre_exec()\fP.  Error numbers -16 to -20 and -22 are not used by \fBpcre_exec()\fP.
2048    .
2049    .
2050    .\" HTML <a name="badutf8reasons"></a>
2051    .SS "Reason codes for invalid UTF-8 strings"
2052    .rs
2053    .sp
2054    When \fBpcre_exec()\fP returns either PCRE_ERROR_BADUTF8 or
2055    PCRE_ERROR_SHORTUTF8, and the size of the output vector (\fIovecsize\fP) is at
2056    least 2, the offset of the start of the invalid UTF-8 character is placed in
2057    the first output vector element (\fIovector[0]\fP) and a reason code is placed
2058    in the second element (\fIovector[1]\fP). The reason codes are given names in
2059    the \fBpcre.h\fP header file:
2060    .sp
2061      PCRE_UTF8_ERR1
2062      PCRE_UTF8_ERR2
2063      PCRE_UTF8_ERR3
2064      PCRE_UTF8_ERR4
2065      PCRE_UTF8_ERR5
2066    .sp
2067    The string ends with a truncated UTF-8 character; the code specifies how many
2068    bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8 characters to be
2069    no longer than 4 bytes, the encoding scheme (originally defined by RFC 2279)
2070    allows for up to 6 bytes, and this is checked first; hence the possibility of
2071    4 or 5 missing bytes.
2072    .sp
2073      PCRE_UTF8_ERR6
2074      PCRE_UTF8_ERR7
2075      PCRE_UTF8_ERR8
2076      PCRE_UTF8_ERR9
2077      PCRE_UTF8_ERR10
2078    .sp
2079    The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of the
2080    character do not have the binary value 0b10 (that is, either the most
2081    significant bit is 0, or the next bit is 1).
2082    .sp
2083      PCRE_UTF8_ERR11
2084      PCRE_UTF8_ERR12
2085    .sp
2086    A character that is valid by the RFC 2279 rules is either 5 or 6 bytes long;
2087    these code points are excluded by RFC 3629.
2088    .sp
2089      PCRE_UTF8_ERR13
2090    .sp
2091    A 4-byte character has a value greater than 0x10fff; these code points are
2092    excluded by RFC 3629.
2093    .sp
2094      PCRE_UTF8_ERR14
2095    .sp
2096    A 3-byte character has a value in the range 0xd800 to 0xdfff; this range of
2097    code points are reserved by RFC 3629 for use with UTF-16, and so are excluded
2098    from UTF-8.
2099    .sp
2100      PCRE_UTF8_ERR15
2101      PCRE_UTF8_ERR16
2102      PCRE_UTF8_ERR17
2103      PCRE_UTF8_ERR18
2104      PCRE_UTF8_ERR19
2105    .sp
2106    A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes for a
2107    value that can be represented by fewer bytes, which is invalid. For example,
2108    the two bytes 0xc0, 0xae give the value 0x2e, whose correct coding uses just
2109    one byte.
2110    .sp
2111      PCRE_UTF8_ERR20
2112    .sp
2113    The two most significant bits of the first byte of a character have the binary
2114    value 0b10 (that is, the most significant bit is 1 and the second is 0). Such a
2115    byte can only validly occur as the second or subsequent byte of a multi-byte
2116    character.
2117    .sp
2118      PCRE_UTF8_ERR21
2119    .sp
2120    The first byte of a character has the value 0xfe or 0xff. These values can
2121    never occur in a valid UTF-8 string.
2122  .  .
2123  .  .
2124  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
# Line 1638  These functions call \fBpcre_get_stringn Line 2267  These functions call \fBpcre_get_stringn
2267  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
2268  appropriate. \fBNOTE:\fP If PCRE_DUPNAMES is set and there are duplicate names,  appropriate. \fBNOTE:\fP If PCRE_DUPNAMES is set and there are duplicate names,
2269  the behaviour may not be what you want (see the next section).  the behaviour may not be what you want (see the next section).
2270    .P
2271    \fBWarning:\fP If the pattern uses the (?| feature to set up multiple
2272    subpatterns with the same number, as described in the
2273    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
2274    .\" </a>
2275    section on duplicate subpattern numbers
2276    .\"
2277    in the
2278    .\" HREF
2279    \fBpcrepattern\fP
2280    .\"
2281    page, you cannot use names to distinguish the different subpatterns, because
2282    names are not included in the compiled code. The matching process uses only
2283    numbers. For this reason, the use of different names for subpatterns of the
2284    same number causes an error at compile time.
2285  .  .
2286  .  .
2287  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
# Line 1648  the behaviour may not be what you want ( Line 2292  the behaviour may not be what you want (
2292  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
2293  .PP  .PP
2294  When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns  When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
2295  are not required to be unique. Normally, patterns with duplicate names are such  are not required to be unique. (Duplicate names are always allowed for
2296  that in any one match, only one of the named subpatterns participates. An  subpatterns with the same number, created by using the (?| feature. Indeed, if
2297  example is shown in the  such subpatterns are named, they are required to use the same names.)
2298    .P
2299    Normally, patterns with duplicate names are such that in any one match, only
2300    one of the named subpatterns participates. An example is shown in the
2301  .\" HREF  .\" HREF
2302  \fBpcrepattern\fP  \fBpcrepattern\fP
2303  .\"  .\"
2304  documentation. When duplicates are present, \fBpcre_copy_named_substring()\fP  documentation.
2305  and \fBpcre_get_named_substring()\fP return the first substring corresponding  .P
2306  to the given name that is set. If none are set, an empty string is returned.  When duplicates are present, \fBpcre_copy_named_substring()\fP and
2307  The \fBpcre_get_stringnumber()\fP function returns one of the numbers that are  \fBpcre_get_named_substring()\fP return the first substring corresponding to
2308  associated with the name, but it is not defined which it is.  the given name that is set. If none are set, PCRE_ERROR_NOSUBSTRING (-7) is
2309  .sp  returned; no data is returned. The \fBpcre_get_stringnumber()\fP function
2310    returns one of the numbers that are associated with the name, but it is not
2311    defined which it is.
2312    .P
2313  If you want to get full details of all captured substrings for a given name,  If you want to get full details of all captured substrings for a given name,
2314  you must use the \fBpcre_get_stringtable_entries()\fP function. The first  you must use the \fBpcre_get_stringtable_entries()\fP function. The first
2315  argument is the compiled pattern, and the second is the name. The third and  argument is the compiled pattern, and the second is the name. The third and
# Line 1667  fourth are pointers to variables which a Line 2317  fourth are pointers to variables which a
2317  has run, they point to the first and last entries in the name-to-number table  has run, they point to the first and last entries in the name-to-number table
2318  for the given name. The function itself returns the length of each entry, or  for the given name. The function itself returns the length of each entry, or
2319  PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is  PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
2320  described above in the section entitled \fIInformation about a pattern\fP.  described above in the section entitled \fIInformation about a pattern\fP
2321    .\" HTML <a href="#infoaboutpattern">
2322    .\" </a>
2323    above.
2324    .\"
2325  Given all the relevant entries for the name, you can extract each of their  Given all the relevant entries for the name, you can extract each of their
2326  numbers, and hence the captured data, if any.  numbers, and hence the captured data, if any.
2327  .  .
# Line 1711  a compiled pattern, using a matching alg Line 2365  a compiled pattern, using a matching alg
2365  just once, and does not backtrack. This has different characteristics to the  just once, and does not backtrack. This has different characteristics to the
2366  normal algorithm, and is not compatible with Perl. Some of the features of PCRE  normal algorithm, and is not compatible with Perl. Some of the features of PCRE
2367  patterns are not supported. Nevertheless, there are times when this kind of  patterns are not supported. Nevertheless, there are times when this kind of
2368  matching can be useful. For a discussion of the two matching algorithms, see  matching can be useful. For a discussion of the two matching algorithms, and a
2369  the  list of features that \fBpcre_dfa_exec()\fP does not support, see the
2370  .\" HREF  .\" HREF
2371  \fBpcrematching\fP  \fBpcrematching\fP
2372  .\"  .\"
# Line 1751  Here is an example of a simple call to \ Line 2405  Here is an example of a simple call to \
2405  .sp  .sp
2406  The unused bits of the \fIoptions\fP argument for \fBpcre_dfa_exec()\fP must be  The unused bits of the \fIoptions\fP argument for \fBpcre_dfa_exec()\fP must be
2407  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
2408  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
2409  PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last three of these are  PCRE_NO_UTF8_CHECK, PCRE_BSR_ANYCRLF, PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE,
2410  the same as for \fBpcre_exec()\fP, so their description is not repeated here.  PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART.
2411  .sp  All but the last four of these are exactly the same as for \fBpcre_exec()\fP,
2412    PCRE_PARTIAL  so their description is not repeated here.
2413  .sp  .sp
2414  This has the same general effect as it does for \fBpcre_exec()\fP, but the    PCRE_PARTIAL_HARD
2415  details are slightly different. When PCRE_PARTIAL is set for    PCRE_PARTIAL_SOFT
2416  \fBpcre_dfa_exec()\fP, the return code PCRE_ERROR_NOMATCH is converted into  .sp
2417  PCRE_ERROR_PARTIAL if the end of the subject is reached, there have been no  These have the same general effect as they do for \fBpcre_exec()\fP, but the
2418  complete matches, but there is still at least one matching possibility. The  details are slightly different. When PCRE_PARTIAL_HARD is set for
2419  portion of the string that provided the partial match is set as the first  \fBpcre_dfa_exec()\fP, it returns PCRE_ERROR_PARTIAL if the end of the subject
2420  matching string.  is reached and there is still at least one matching possibility that requires
2421    additional characters. This happens even if some complete matches have also
2422    been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
2423    is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
2424    there have been no complete matches, but there is still at least one matching
2425    possibility. The portion of the string that was inspected when the longest
2426    partial match was found is set as the first matching string in both cases.
2427    There is a more detailed discussion of partial and multi-segment matching, with
2428    examples, in the
2429    .\" HREF
2430    \fBpcrepartial\fP
2431    .\"
2432    documentation.
2433  .sp  .sp
2434    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
2435  .sp  .sp
# Line 1774  matching point in the subject string. Line 2440  matching point in the subject string.
2440  .sp  .sp
2441    PCRE_DFA_RESTART    PCRE_DFA_RESTART
2442  .sp  .sp
2443  When \fBpcre_dfa_exec()\fP is called with the PCRE_PARTIAL option, and returns  When \fBpcre_dfa_exec()\fP returns a partial match, it is possible to call it
2444  a partial match, it is possible to call it again, with additional subject  again, with additional subject characters, and have it continue with the same
2445  characters, and have it continue with the same match. The PCRE_DFA_RESTART  match. The PCRE_DFA_RESTART option requests this action; when it is set, the
2446  option requests this action; when it is set, the \fIworkspace\fP and  \fIworkspace\fP and \fIwscount\fP options must reference the same vector as
2447  \fIwscount\fP options must reference the same vector as before because data  before because data about the match so far is left in them after a partial
2448  about the match so far is left in them after a partial match. There is more  match. There is more discussion of this facility in the
 discussion of this facility in the  
2449  .\" HREF  .\" HREF
2450  \fBpcrepartial\fP  \fBpcrepartial\fP
2451  .\"  .\"
2452  documentation.  documentation.
2453  .  .
2454    .
2455  .SS "Successful returns from \fBpcre_dfa_exec()\fP"  .SS "Successful returns from \fBpcre_dfa_exec()\fP"
2456  .rs  .rs
2457  .sp  .sp
# Line 1817  returns data, even though the meaning of Line 2483  returns data, even though the meaning of
2483  The strings are returned in reverse order of length; that is, the longest  The strings are returned in reverse order of length; that is, the longest
2484  matching string is given first. If there were too many matches to fit into  matching string is given first. If there were too many matches to fit into
2485  \fIovector\fP, the yield of the function is zero, and the vector is filled with  \fIovector\fP, the yield of the function is zero, and the vector is filled with
2486  the longest matches.  the longest matches. Unlike \fBpcre_exec()\fP, \fBpcre_dfa_exec()\fP can use
2487    the entire \fIovector\fP for returning matched strings.
2488    .
2489  .  .
2490  .SS "Error returns from \fBpcre_dfa_exec()\fP"  .SS "Error returns from \fBpcre_dfa_exec()\fP"
2491  .rs  .rs
# Line 1846  group. These are not supported. Line 2514  group. These are not supported.
2514    PCRE_ERROR_DFA_UMLIMIT    (-18)    PCRE_ERROR_DFA_UMLIMIT    (-18)
2515  .sp  .sp
2516  This return is given if \fBpcre_dfa_exec()\fP is called with an \fIextra\fP  This return is given if \fBpcre_dfa_exec()\fP is called with an \fIextra\fP
2517  block that contains a setting of the \fImatch_limit\fP field. This is not  block that contains a setting of the \fImatch_limit\fP or
2518  supported (it is meaningless).  \fImatch_limit_recursion\fP fields. This is not supported (these fields are
2519    meaningless for DFA matching).
2520  .sp  .sp
2521    PCRE_ERROR_DFA_WSSIZE     (-19)    PCRE_ERROR_DFA_WSSIZE     (-19)
2522  .sp  .sp
# Line 1884  Cambridge CB2 3QH, England. Line 2553  Cambridge CB2 3QH, England.
2553  .rs  .rs
2554  .sp  .sp
2555  .nf  .nf
2556  Last updated: 30 July 2007  Last updated: 02 December 2011
2557  Copyright (c) 1997-2007 University of Cambridge.  Copyright (c) 1997-2011 University of Cambridge.
2558  .fi  .fi

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