/[pcre]/code/trunk/doc/pcreapi.3
ViewVC logotype

Diff of /code/trunk/doc/pcreapi.3

Parent Directory Parent Directory | Revision Log Revision Log | View Patch Patch

revision 428 by ph10, Mon Aug 31 17:10:26 2009 UTC revision 776 by ph10, Thu Dec 1 11:02:56 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 compile and run it.  documentation describes how to compile and run it.
173  .P  .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
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 271  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 313  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
# Line 390  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 407  argument, which is an address (see below Line 464  argument, which is an address (see below
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, but also some others) can also be set and unset from  compatible with Perl, but some others as well) can also be set and unset from
468  within the pattern (see 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 those options that can be different in different parts of  documentation). For those options that can be different in different parts of
473  the pattern, the contents of the \fIoptions\fP argument specifies their initial  the pattern, the contents of the \fIoptions\fP argument specifies their
474  settings at the start of compilation and execution. The PCRE_ANCHORED and  settings at the start of compilation and execution. The PCRE_ANCHORED,
475  PCRE_NEWLINE_\fIxxx\fP options can be set at the time of matching as well as at  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.  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 503  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 530  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 543  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 565  character). Thus, the pattern AB]CD beco Line 643  character). Thus, the pattern AB]CD beco
643  string (by default this causes the current matching alternative to fail). A  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  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.  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  .sp
661    PCRE_MULTILINE    PCRE_MULTILINE
662  .sp  .sp
# Line 607  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 625  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 638  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
# Line 714  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 730  out of use. To avoid confusion, they hav Line 846  out of use. To avoid confusion, they hav
846    50  [this code is not in use]    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, angle-bracketed, or quoted    57  \eg is not followed by a braced, angle-bracketed, or quoted
855          name/number or by a plain number          name/number or by a plain number
856    58  a numbered reference must not be zero    58  a numbered reference must not be zero
857    59  (*VERB) with an argument is not supported    59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
858    60  (*VERB) not recognized    60  (*VERB) not recognized
859    61  number is too big    61  number is too big
860    62  subpattern name expected    62  subpattern name expected
861    63  digit expected after (?+    63  digit expected after (?+
862    64  ] is an invalid data character in JavaScript compatibility mode    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  .sp
870  The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may  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.  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 764  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 788  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 808  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 857  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 888  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 953  Return 1 if the (?J) or (?-J) option set Line 1134  Return 1 if the (?J) or (?-J) option set
1134  0. The fourth argument should point to an \fBint\fP variable. (?J) and  0. The fourth argument should point to an \fBint\fP variable. (?J) and
1135  (?-J) set and unset the local PCRE_DUPNAMES option, respectively.  (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
1136  .sp  .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_LASTLITERAL    PCRE_INFO_LASTLITERAL
1151  .sp  .sp
1152  Return the value of the rightmost literal byte that must exist in any matched  Return the value of the rightmost literal byte that must exist in any matched
# Line 963  follows something of variable length. Fo Line 1157  follows something of variable length. Fo
1157  /^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
1158  is -1.  is -1.
1159  .sp  .sp
1160      PCRE_INFO_MINLENGTH
1161    .sp
1162    If the pattern was studied and a minimum length for matching subject strings
1163    was computed, its value is returned. Otherwise the returned value is -1. The
1164    value is a number of characters, not bytes (this may be relevant in UTF-8
1165    mode). The fourth argument should point to an \fBint\fP variable. A
1166    non-negative value is a lower bound to the length of any matching string. There
1167    may not be any strings of that length that do actually match, but every string
1168    that does match is at least that long.
1169    .sp
1170    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
1171    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
1172    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
# Line 983  entry; both of these return an \fBint\fP Line 1187  entry; both of these return an \fBint\fP
1187  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
1188  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
1189  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
1190  rest of the entry is the corresponding name, zero terminated. The names are in  rest of the entry is the corresponding name, zero terminated.
1191  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of  .P
1192  their parentheses numbers. For example, consider the following pattern (assume  The names are in alphabetical order. Duplicate names may appear if (?| is used
1193  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  to create multiple groups with the same number, as described in the
1194    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1195    .\" </a>
1196    section on duplicate subpattern numbers
1197    .\"
1198    in the
1199    .\" HREF
1200    \fBpcrepattern\fP
1201    .\"
1202    page. Duplicate names for subpatterns with different numbers are permitted only
1203    if PCRE_DUPNAMES is set. In all cases of duplicate names, they appear in the
1204    table in the order in which they were found in the pattern. In the absence of
1205    (?| this is the order of increasing number; when (?| is used this is not
1206    necessarily the case because later subpatterns may have lower numbers.
1207    .P
1208    As a simple example of the name/number table, consider the following pattern
1209    (assume PCRE_EXTENDED is set, so white space - including newlines - is
1210    ignored):
1211  .sp  .sp
1212  .\" JOIN  .\" JOIN
1213    (?<date> (?<year>(\ed\ed)?\ed\ed) -    (?<date> (?<year>(\ed\ed)?\ed\ed) -
# Line 1007  different for each compiled pattern. Line 1228  different for each compiled pattern.
1228  .sp  .sp
1229    PCRE_INFO_OKPARTIAL    PCRE_INFO_OKPARTIAL
1230  .sp  .sp
1231  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
1232  fourth argument should point to an \fBint\fP variable. From release 8.00, this  \fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
1233  always returns 1, because the restrictions that previously applied to partial  \fBint\fP variable. From release 8.00, this always returns 1, because the
1234  matching have been lifted. The  restrictions that previously applied to partial matching have been lifted. The
1235  .\" HREF  .\" HREF
1236  \fBpcrepartial\fP  \fBpcrepartial\fP
1237  .\"  .\"
# Line 1041  For such patterns, the PCRE_ANCHORED bit Line 1262  For such patterns, the PCRE_ANCHORED bit
1262  .sp  .sp
1263    PCRE_INFO_SIZE    PCRE_INFO_SIZE
1264  .sp  .sp
1265  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
1266  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
1267  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
1268  variable.  the argument to \fBpcre_malloc()\fP when \fBpcre_compile()\fP is getting memory
1269    in which to place the compiled data is the value returned by this option plus
1270    the size of the \fBpcre\fP structure. Studying a compiled pattern, with or
1271    without JIT, does not alter the value returned by this option.
1272  .sp  .sp
1273    PCRE_INFO_STUDYSIZE    PCRE_INFO_STUDYSIZE
1274  .sp  .sp
1275  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
1276  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,
1277  \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.
1278  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
1279  \fBsize_t\fP variable.  that will speed up matching (see the section entitled
1280    .\" HTML <a href="#studyingapattern">
1281    .\" </a>
1282    "Studying a pattern"
1283    .\"
1284    above). The format of the \fIstudy_data\fP block is private, but its length
1285    is made available via this option so that it can be saved and restored (see the
1286    .\" HREF
1287    \fBpcreprecompile\fP
1288    .\"
1289    documentation for details).
1290  .  .
1291  .  .
1292  .SH "OBSOLETE INFO FUNCTION"  .SH "OBSOLETE INFO FUNCTION"
# Line 1113  is different. (This seems a highly unlik Line 1347  is different. (This seems a highly unlik
1347  .P  .P
1348  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
1349  compiled pattern, which is passed in the \fIcode\fP argument. If the  compiled pattern, which is passed in the \fIcode\fP argument. If the
1350  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
1351  \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
1352  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
1353  also an alternative matching function, which is described  different subject strings with the same pattern.
1354    .P
1355    This function is the main matching facility of the library, and it operates in
1356    a Perl-like manner. For specialist use there is also an alternative matching
1357    function, which is described
1358  .\" HTML <a href="#dfamatch">  .\" HTML <a href="#dfamatch">
1359  .\" </a>  .\" </a>
1360  below  below
# Line 1147  Here is an example of a simple call to \ Line 1385  Here is an example of a simple call to \
1385      ovector,        /* vector of integers for substring information */      ovector,        /* vector of integers for substring information */
1386      30);            /* number of elements (NOT size in bytes) */      30);            /* number of elements (NOT size in bytes) */
1387  .  .
1388    .
1389  .\" HTML <a name="extradata"></a>  .\" HTML <a name="extradata"></a>
1390  .SS "Extra data for \fBpcre_exec()\fR"  .SS "Extra data for \fBpcre_exec()\fR"
1391  .rs  .rs
# Line 1159  fields (not necessarily in this order): Line 1398  fields (not necessarily in this order):
1398  .sp  .sp
1399    unsigned long int \fIflags\fP;    unsigned long int \fIflags\fP;
1400    void *\fIstudy_data\fP;    void *\fIstudy_data\fP;
1401      void *\fIexecutable_jit\fP;
1402    unsigned long int \fImatch_limit\fP;    unsigned long int \fImatch_limit\fP;
1403    unsigned long int \fImatch_limit_recursion\fP;    unsigned long int \fImatch_limit_recursion\fP;
1404    void *\fIcallout_data\fP;    void *\fIcallout_data\fP;
1405    const unsigned char *\fItables\fP;    const unsigned char *\fItables\fP;
1406      unsigned char **\fImark\fP;
1407  .sp  .sp
1408  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
1409  are set. The flag bits are:  are set. The flag bits are:
1410  .sp  .sp
1411    PCRE_EXTRA_STUDY_DATA    PCRE_EXTRA_STUDY_DATA
1412      PCRE_EXTRA_EXECUTABLE_JIT
1413    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1414    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1415    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1416    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1417      PCRE_EXTRA_MARK
1418  .sp  .sp
1419  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
1420  \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
1421  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
1422  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
1423    other fields and their corresponding flag bits.
1424  .P  .P
1425  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
1426  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,
1427  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
1428  classic example is the use of nested unlimited repeats.  classic example is a pattern that uses nested unlimited repeats.
1429  .P  .P
1430  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly  Internally, \fBpcre_exec()\fP uses a function called \fBmatch()\fP, which it
1431  (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
1432  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
1433  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
1434  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
1435  string.  in the subject string.
1436    .P
1437    When \fBpcre_exec()\fP is called with a pattern that was successfully studied
1438    with the PCRE_STUDY_JIT_COMPILE option, the way that the matching is executed
1439    is entirely different. However, there is still the possibility of runaway
1440    matching that goes on for a very long time, and so the \fImatch_limit\fP value
1441    is also used in this case (but in a different way) to limit how long the
1442    matching can continue.
1443  .P  .P
1444  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
1445  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 1203  limits the depth of recursion. The recur Line 1454  limits the depth of recursion. The recur
1454  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.
1455  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.
1456  .P  .P
1457  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
1458  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
1459  amount of heap memory that can be used.  stack, the amount of heap memory that can be used. This limit is not relevant,
1460    and is ignored, if the pattern was successfully studied with
1461    PCRE_STUDY_JIT_COMPILE.
1462  .P  .P
1463  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
1464  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 1214  with a \fBpcre_extra\fP block in which \ Line 1467  with a \fBpcre_extra\fP block in which \
1467  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
1468  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1469  .P  .P
1470  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,
1471  which is described in the  and is described in the
1472  .\" HREF  .\" HREF
1473  \fBpcrecallout\fP  \fBpcrecallout\fP
1474  .\"  .\"
# Line 1234  called. See the Line 1487  called. See the
1487  \fBpcreprecompile\fP  \fBpcreprecompile\fP
1488  .\"  .\"
1489  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1490    .P
1491    If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1492    be set to point to a \fBchar *\fP variable. If the pattern contains any
1493    backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1494    a name to pass back, a pointer to the name string (zero terminated) is placed
1495    in the variable pointed to by the \fImark\fP field. The names are within the
1496    compiled pattern; if you wish to retain such a name you must copy it before
1497    freeing the memory of a compiled pattern. If there is no name to pass back, the
1498    variable pointed to by the \fImark\fP field set to NULL. For details of the
1499    backtracking control verbs, see the section entitled
1500    .\" HTML <a href="pcrepattern#backtrackcontrol">
1501    .\" </a>
1502    "Backtracking control"
1503    .\"
1504    in the
1505    .\" HREF
1506    \fBpcrepattern\fP
1507    .\"
1508    documentation.
1509    .
1510  .  .
1511  .\" HTML <a name="execoptions"></a>  .\" HTML <a name="execoptions"></a>
1512  .SS "Option bits for \fBpcre_exec()\fP"  .SS "Option bits for \fBpcre_exec()\fP"
# Line 1241  documentation for a discussion of saving Line 1514  documentation for a discussion of saving
1514  .sp  .sp
1515  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
1516  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,
1517  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_START_OPTIMIZE,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1518  PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and PCRE_PARTIAL_HARD.  PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
1519    PCRE_PARTIAL_HARD.
1520    .P
1521    If the pattern was successfully studied with the PCRE_STUDY_JIT_COMPILE option,
1522    the only supported options for JIT execution are PCRE_NO_UTF8_CHECK,
1523    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and PCRE_NOTEMPTY_ATSTART. Note in
1524    particular that partial matching is not supported. If an unsupported option is
1525    used, JIT execution is disabled and the normal interpretive code in
1526    \fBpcre_exec()\fP is run.
1527  .sp  .sp
1528    PCRE_ANCHORED    PCRE_ANCHORED
1529  .sp  .sp
# Line 1317  match the empty string, the entire match Line 1598  match the empty string, the entire match
1598  .sp  .sp
1599    a?b?    a?b?
1600  .sp  .sp
1601  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
1602  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
1603  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".
1604  .P  .sp
1605  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case    PCRE_NOTEMPTY_ATSTART
1606  of a pattern match of the empty string within its \fBsplit()\fP function, and  .sp
1607  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
1608  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
1609  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the  can occur only if the pattern contains \eK.
1610  starting offset (see below) and trying an ordinary match again. There is some  .P
1611  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
1612    does make a special case of a pattern match of the empty string within its
1613    \fBsplit()\fP function, and when using the /g modifier. It is possible to
1614    emulate Perl's behaviour after matching a null string by first trying the match
1615    again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
1616    if that fails, by advancing the starting offset (see below) and trying an
1617    ordinary match again. There is some code that demonstrates how to do this in
1618    the
1619    .\" HREF
1620    \fBpcredemo\fP
1621    .\"
1622    sample program. In the most general case, you have to check to see if the
1623    newline convention recognizes CRLF as a newline, and if so, and the current
1624    character is CR followed by LF, advance the starting offset by two characters
1625    instead of one.
1626  .sp  .sp
1627    PCRE_NO_START_OPTIMIZE    PCRE_NO_START_OPTIMIZE
1628  .sp  .sp
1629  There are a number of optimizations that \fBpcre_exec()\fP uses at the start of  There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1630  a match, in order to speed up the process. For example, if it is known that a  a match, in order to speed up the process. For example, if it is known that an
1631  match must start with a specific character, it searches the subject for that  unanchored match must start with a specific character, it searches the subject
1632  character, and fails immediately if it cannot find it, without actually running  for that character, and fails immediately if it cannot find it, without
1633  the main matching function. When callouts are in use, these optimizations can  actually running the main matching function. This means that a special item
1634  cause them to be skipped. This option disables the "start-up" optimizations,  such as (*COMMIT) at the start of a pattern is not considered until after a
1635  causing performance to suffer, but ensuring that the callouts do occur.  suitable starting point for the match has been found. When callouts or (*MARK)
1636    items are in use, these "start-up" optimizations can cause them to be skipped
1637    if the pattern is never actually used. The start-up optimizations are in effect
1638    a pre-scan of the subject that takes place before the pattern is run.
1639    .P
1640    The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
1641    causing performance to suffer, but ensuring that in cases where the result is
1642    "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
1643    are considered at every possible starting position in the subject string. If
1644    PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
1645    time.
1646    .P
1647    Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
1648    Consider the pattern
1649    .sp
1650      (*COMMIT)ABC
1651    .sp
1652    When this is compiled, PCRE records the fact that a match must start with the
1653    character "A". Suppose the subject string is "DEFABC". The start-up
1654    optimization scans along the subject, finds "A" and runs the first match
1655    attempt from there. The (*COMMIT) item means that the pattern must match the
1656    current starting position, which in this case, it does. However, if the same
1657    match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
1658    subject string does not happen. The first match attempt is run starting from
1659    "D" and when this fails, (*COMMIT) prevents any further matches being tried, so
1660    the overall result is "no match". If the pattern is studied, more start-up
1661    optimizations may be used. For example, a minimum length for the subject may be
1662    recorded. Consider the pattern
1663    .sp
1664      (*MARK:A)(X|Y)
1665    .sp
1666    The minimum length for a match is one character. If the subject is "ABC", there
1667    will be attempts to match "ABC", "BC", "C", and then finally an empty string.
1668    If the pattern is studied, the final attempt does not take place, because PCRE
1669    knows that the subject is too short, and so the (*MARK) is never encountered.
1670    In this case, studying the pattern does not affect the overall match result,
1671    which is still "no match", but it does affect the auxiliary information that is
1672    returned.
1673  .sp  .sp
1674    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1675  .sp  .sp
# Line 1355  in the main Line 1687  in the main
1687  \fBpcre\fP  \fBpcre\fP
1688  .\"  .\"
1689  page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns  page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns
1690  the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP contains an invalid value,  the error PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is
1691  PCRE_ERROR_BADUTF8_OFFSET is returned.  a truncated UTF-8 character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
1692    both cases, information about the precise nature of the error may also be
1693    returned (see the descriptions of these errors in the section entitled \fIError
1694    return values from\fP \fBpcre_exec()\fP
1695    .\" HTML <a href="#errorlist">
1696    .\" </a>
1697    below).
1698    .\"
1699    If \fIstartoffset\fP contains a value that does not point to the start of a
1700    UTF-8 character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
1701    returned.
1702  .P  .P
1703  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
1704  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
1705  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
1706  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
1707  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
1708  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
1709  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
1710  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
1711  UTF-8 character, is undefined. Your program may crash.  undefined. Your program may crash.
1712  .sp  .sp
1713    PCRE_PARTIAL_HARD    PCRE_PARTIAL_HARD
1714    PCRE_PARTIAL_SOFT    PCRE_PARTIAL_SOFT
1715  .sp  .sp
1716  These options turn on the partial matching feature. For backwards  These options turn on the partial matching feature. For backwards
1717  compatibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial match  compatibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial match
1718  occurs if the end of the subject string is reached successfully, but there are  occurs if the end of the subject string is reached successfully, but there are
1719  not enough subject characters to complete the match. If this happens when  not enough subject characters to complete the match. If this happens when
1720  PCRE_PARTIAL_HARD is set, \fBpcre_exec()\fP immediately returns  PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set, matching continues by
1721  PCRE_ERROR_PARTIAL. Otherwise, if PCRE_PARTIAL_SOFT is set, matching continues  testing any remaining alternatives. Only if no complete match can be found is
1722  by testing any other alternatives. Only if they all fail is PCRE_ERROR_PARTIAL  PCRE_ERROR_PARTIAL returned instead of PCRE_ERROR_NOMATCH. In other words,
1723  returned (instead of PCRE_ERROR_NOMATCH). The portion of the string that  PCRE_PARTIAL_SOFT says that the caller is prepared to handle a partial match,
1724  provided the partial match is set as the first matching string. There is a more  but only if no complete match can be found.
1725  detailed discussion in the  .P
1726    If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
1727    partial match is found, \fBpcre_exec()\fP immediately returns
1728    PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
1729    when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
1730    important that an alternative complete match.
1731    .P
1732    In both cases, the portion of the string that was inspected when the partial
1733    match was found is set as the first matching string. There is a more detailed
1734    discussion of partial and multi-segment matching, with examples, in the
1735  .\" HREF  .\" HREF
1736  \fBpcrepartial\fP  \fBpcrepartial\fP
1737  .\"  .\"
1738  documentation.  documentation.
1739  .  .
1740    .
1741  .SS "The string to be matched by \fBpcre_exec()\fP"  .SS "The string to be matched by \fBpcre_exec()\fP"
1742  .rs  .rs
1743  .sp  .sp
1744  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
1745  \fIsubject\fP, a length (in bytes) in \fIlength\fP, and a starting byte offset  \fIsubject\fP, a length (in bytes) in \fIlength\fP, and a starting byte offset
1746  in \fIstartoffset\fP. In UTF-8 mode, the byte offset must point to the start of  in \fIstartoffset\fP. If this is negative or greater than the length of the
1747  a UTF-8 character. Unlike the pattern string, the subject may contain binary  subject, \fBpcre_exec()\fP returns PCRE_ERROR_BADOFFSET. When the starting
1748  zero bytes. When the starting offset is zero, the search for a match starts at  offset is zero, the search for a match starts at the beginning of the subject,
1749  the 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
1750    point to the start of a UTF-8 character (or the end of the subject). Unlike the
1751    pattern string, the subject may contain binary zero bytes.
1752  .P  .P
1753  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
1754  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 1414  start of the subject, which is deemed to Line 1768  start of the subject, which is deemed to
1768  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
1769  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.
1770  .P  .P
1771    Finding all the matches in a subject is tricky when the pattern can match an
1772    empty string. It is possible to emulate Perl's /g behaviour by first trying the
1773    match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
1774    PCRE_ANCHORED options, and then if that fails, advancing the starting offset
1775    and trying an ordinary match again. There is some code that demonstrates how to
1776    do this in the
1777    .\" HREF
1778    \fBpcredemo\fP
1779    .\"
1780    sample program. In the most general case, you have to check to see if the
1781    newline convention recognizes CRLF as a newline, and if so, and the current
1782    character is CR followed by LF, advance the starting offset by two characters
1783    instead of one.
1784    .P
1785  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
1786  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
1787  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.
1788  .  .
1789    .
1790  .SS "How \fBpcre_exec()\fP returns captured substrings"  .SS "How \fBpcre_exec()\fP returns captured substrings"
1791  .rs  .rs
1792  .sp  .sp
# Line 1461  string that it matched that is returned. Line 1830  string that it matched that is returned.
1830  .P  .P
1831  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
1832  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
1833  returns a value of zero. If the substring offsets are not of interest,  returns a value of zero. If neither the actual string matched not any captured
1834  \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
1835  \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
1836  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
1837  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
1838  advisable to supply an \fIovector\fP.  is usually advisable to supply an \fIovector\fP of reasonable size.
1839    .P
1840    There are some cases where zero is returned (indicating vector overflow) when
1841    in fact the vector is exactly the right size for the final match. For example,
1842    consider the pattern
1843    .sp
1844      (a)(?:(b)c|bd)
1845    .sp
1846    If a vector of 6 elements (allowing for only 1 captured substring) is given
1847    with subject string "abd", \fBpcre_exec()\fP will try to set the second
1848    captured string, thereby recording a vector overflow, before failing to match
1849    "c" and backing up to try the second alternative. The zero return, however,
1850    does correctly indicate that the maximum number of slots (namely 2) have been
1851    filled. In similar cases where there is temporary overflow, but the final
1852    number of used slots is actually less than the maximum, a non-zero value is
1853    returned.
1854  .P  .P
1855  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
1856  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1857  \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
1858  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 1484  Offset values that correspond to unused Line 1868  Offset values that correspond to unused
1868  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
1869  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
1870  return from the function is 2, because the highest used capturing subpattern  return from the function is 2, because the highest used capturing subpattern
1871  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
1872  capturing subpatterns if you wish (assuming the vector is large enough, of  (assuming the vector is large enough, of course) are set to -1.
1873  course).  .P
1874    \fBNote\fP: Elements in the first two-thirds of \fIovector\fP that do not
1875    correspond to capturing parentheses in the pattern are never changed. That is,
1876    if a pattern contains \fIn\fP capturing parentheses, no more than
1877    \fIovector[0]\fP to \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other
1878    elements (in the first two-thirds) retain whatever values they previously had.
1879  .P  .P
1880  Some convenience functions are provided for extracting the captured substrings  Some convenience functions are provided for extracting the captured substrings
1881  as separate strings. These are described below.  as separate strings. These are described below.
1882  .  .
1883    .
1884  .\" HTML <a name="errorlist"></a>  .\" HTML <a name="errorlist"></a>
1885  .SS "Error return values from \fBpcre_exec()\fP"  .SS "Error return values from \fBpcre_exec()\fP"
1886  .rs  .rs
# Line 1532  If a pattern contains back references, b Line 1922  If a pattern contains back references, b
1922  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
1923  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
1924  automatically freed at the end of matching.  automatically freed at the end of matching.
1925    .P
1926    This error is also given if \fBpcre_stack_malloc()\fP fails in
1927    \fBpcre_exec()\fP. This can happen only when PCRE has been compiled with
1928    \fB--disable-stack-for-recursion\fP.
1929  .sp  .sp
1930    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1931  .sp  .sp
# Line 1556  documentation for details. Line 1950  documentation for details.
1950  .sp  .sp
1951    PCRE_ERROR_BADUTF8        (-10)    PCRE_ERROR_BADUTF8        (-10)
1952  .sp  .sp
1953  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,
1954    and the PCRE_NO_UTF8_CHECK option was not set. If the size of the output vector
1955    (\fIovecsize\fP) is at least 2, the byte offset to the start of the the invalid
1956    UTF-8 character is placed in the first element, and a reason code is placed in
1957    the second element. The reason codes are listed in the
1958    .\" HTML <a href="#badutf8reasons">
1959    .\" </a>
1960    following section.
1961    .\"
1962    For backward compatibility, if PCRE_PARTIAL_HARD is set and the problem is a
1963    truncated UTF-8 character at the end of the subject (reason codes 1 to 5),
1964    PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
1965  .sp  .sp
1966    PCRE_ERROR_BADUTF8_OFFSET (-11)    PCRE_ERROR_BADUTF8_OFFSET (-11)
1967  .sp  .sp
1968  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
1969  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
1970    \fIstartoffset\fP did not point to the beginning of a UTF-8 character or the
1971    end of the subject.
1972  .sp  .sp
1973    PCRE_ERROR_PARTIAL        (-12)    PCRE_ERROR_PARTIAL        (-12)
1974  .sp  .sp
# Line 1575  documentation for details of partial mat Line 1982  documentation for details of partial mat
1982  .sp  .sp
1983  This code is no longer in use. It was formerly returned when the PCRE_PARTIAL  This code is no longer in use. It was formerly returned when the PCRE_PARTIAL
1984  option was used with a compiled pattern containing items that were not  option was used with a compiled pattern containing items that were not
1985  supported for partial matching. From release 8.00 onwards, there are no  supported for partial matching. From release 8.00 onwards, there are no
1986  restrictions on partial matching.  restrictions on partial matching.
1987  .sp  .sp
1988    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
# Line 1596  description above. Line 2003  description above.
2003    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
2004  .sp  .sp
2005  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
2006    .sp
2007      PCRE_ERROR_BADOFFSET      (-24)
2008    .sp
2009    The value of \fIstartoffset\fP was negative or greater than the length of the
2010    subject, that is, the value in \fIlength\fP.
2011    .sp
2012      PCRE_ERROR_SHORTUTF8      (-25)
2013    .sp
2014    This error is returned instead of PCRE_ERROR_BADUTF8 when the subject string
2015    ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD option is set.
2016    Information about the failure is returned as for PCRE_ERROR_BADUTF8. It is in
2017    fact sufficient to detect this case, but this special error code for
2018    PCRE_PARTIAL_HARD precedes the implementation of returned information; it is
2019    retained for backwards compatibility.
2020    .sp
2021      PCRE_ERROR_RECURSELOOP    (-26)
2022    .sp
2023    This error is returned when \fBpcre_exec()\fP detects a recursion loop within
2024    the pattern. Specifically, it means that either the whole pattern or a
2025    subpattern has been called recursively for the second time at the same position
2026    in the subject string. Some simple patterns that might do this are detected and
2027    faulted at compile time, but more complicated cases, in particular mutual
2028    recursions between two different subpatterns, cannot be detected until run
2029    time.
2030    .sp
2031      PCRE_ERROR_JIT_STACKLIMIT (-27)
2032    .sp
2033    This error is returned when a pattern that was successfully studied using the
2034    PCRE_STUDY_JIT_COMPILE option is being matched, but the memory available for
2035    the just-in-time processing stack is not large enough. See the
2036    .\" HREF
2037    \fBpcrejit\fP
2038    .\"
2039    documentation for more details.
2040  .P  .P
2041  Error numbers -16 to -20 and -22 are not used by \fBpcre_exec()\fP.  Error numbers -16 to -20 and -22 are not used by \fBpcre_exec()\fP.
2042  .  .
2043  .  .
2044    .\" HTML <a name="badutf8reasons"></a>
2045    .SS "Reason codes for invalid UTF-8 strings"
2046    .rs
2047    .sp
2048    When \fBpcre_exec()\fP returns either PCRE_ERROR_BADUTF8 or
2049    PCRE_ERROR_SHORTUTF8, and the size of the output vector (\fIovecsize\fP) is at
2050    least 2, the offset of the start of the invalid UTF-8 character is placed in
2051    the first output vector element (\fIovector[0]\fP) and a reason code is placed
2052    in the second element (\fIovector[1]\fP). The reason codes are given names in
2053    the \fBpcre.h\fP header file:
2054    .sp
2055      PCRE_UTF8_ERR1
2056      PCRE_UTF8_ERR2
2057      PCRE_UTF8_ERR3
2058      PCRE_UTF8_ERR4
2059      PCRE_UTF8_ERR5
2060    .sp
2061    The string ends with a truncated UTF-8 character; the code specifies how many
2062    bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8 characters to be
2063    no longer than 4 bytes, the encoding scheme (originally defined by RFC 2279)
2064    allows for up to 6 bytes, and this is checked first; hence the possibility of
2065    4 or 5 missing bytes.
2066    .sp
2067      PCRE_UTF8_ERR6
2068      PCRE_UTF8_ERR7
2069      PCRE_UTF8_ERR8
2070      PCRE_UTF8_ERR9
2071      PCRE_UTF8_ERR10
2072    .sp
2073    The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of the
2074    character do not have the binary value 0b10 (that is, either the most
2075    significant bit is 0, or the next bit is 1).
2076    .sp
2077      PCRE_UTF8_ERR11
2078      PCRE_UTF8_ERR12
2079    .sp
2080    A character that is valid by the RFC 2279 rules is either 5 or 6 bytes long;
2081    these code points are excluded by RFC 3629.
2082    .sp
2083      PCRE_UTF8_ERR13
2084    .sp
2085    A 4-byte character has a value greater than 0x10fff; these code points are
2086    excluded by RFC 3629.
2087    .sp
2088      PCRE_UTF8_ERR14
2089    .sp
2090    A 3-byte character has a value in the range 0xd800 to 0xdfff; this range of
2091    code points are reserved by RFC 3629 for use with UTF-16, and so are excluded
2092    from UTF-8.
2093    .sp
2094      PCRE_UTF8_ERR15
2095      PCRE_UTF8_ERR16
2096      PCRE_UTF8_ERR17
2097      PCRE_UTF8_ERR18
2098      PCRE_UTF8_ERR19
2099    .sp
2100    A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes for a
2101    value that can be represented by fewer bytes, which is invalid. For example,
2102    the two bytes 0xc0, 0xae give the value 0x2e, whose correct coding uses just
2103    one byte.
2104    .sp
2105      PCRE_UTF8_ERR20
2106    .sp
2107    The two most significant bits of the first byte of a character have the binary
2108    value 0b10 (that is, the most significant bit is 1 and the second is 0). Such a
2109    byte can only validly occur as the second or subsequent byte of a multi-byte
2110    character.
2111    .sp
2112      PCRE_UTF8_ERR21
2113    .sp
2114    The first byte of a character has the value 0xfe or 0xff. These values can
2115    never occur in a valid UTF-8 string.
2116    .
2117    .
2118  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
2119  .rs  .rs
2120  .sp  .sp
# Line 1747  then call \fBpcre_copy_substring()\fP or Line 2262  then call \fBpcre_copy_substring()\fP or
2262  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,
2263  the behaviour may not be what you want (see the next section).  the behaviour may not be what you want (see the next section).
2264  .P  .P
2265  \fBWarning:\fP If the pattern uses the "(?|" feature to set up multiple  \fBWarning:\fP If the pattern uses the (?| feature to set up multiple
2266  subpatterns with the same number, you cannot use names to distinguish them,  subpatterns with the same number, as described in the
2267  because names are not included in the compiled code. The matching process uses  .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
2268  only numbers.  .\" </a>
2269    section on duplicate subpattern numbers
2270    .\"
2271    in the
2272    .\" HREF
2273    \fBpcrepattern\fP
2274    .\"
2275    page, you cannot use names to distinguish the different subpatterns, because
2276    names are not included in the compiled code. The matching process uses only
2277    numbers. For this reason, the use of different names for subpatterns of the
2278    same number causes an error at compile time.
2279    .
2280  .  .
2281  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
2282  .rs  .rs
# Line 1760  only numbers. Line 2286  only numbers.
2286  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
2287  .PP  .PP
2288  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
2289  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
2290  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
2291  example is shown in the  such subpatterns are named, they are required to use the same names.)
2292    .P
2293    Normally, patterns with duplicate names are such that in any one match, only
2294    one of the named subpatterns participates. An example is shown in the
2295  .\" HREF  .\" HREF
2296  \fBpcrepattern\fP  \fBpcrepattern\fP
2297  .\"  .\"
# Line 1782  fourth are pointers to variables which a Line 2311  fourth are pointers to variables which a
2311  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
2312  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
2313  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
2314  described above in the section entitled \fIInformation about a pattern\fP.  described above in the section entitled \fIInformation about a pattern\fP
2315    .\" HTML <a href="#infoaboutpattern">
2316    .\" </a>
2317    above.
2318    .\"
2319  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
2320  numbers, and hence the captured data, if any.  numbers, and hence the captured data, if any.
2321  .  .
# Line 1826  a compiled pattern, using a matching alg Line 2359  a compiled pattern, using a matching alg
2359  just once, and does not backtrack. This has different characteristics to the  just once, and does not backtrack. This has different characteristics to the
2360  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
2361  patterns are not supported. Nevertheless, there are times when this kind of  patterns are not supported. Nevertheless, there are times when this kind of
2362  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
2363  the  list of features that \fBpcre_dfa_exec()\fP does not support, see the
2364  .\" HREF  .\" HREF
2365  \fBpcrematching\fP  \fBpcrematching\fP
2366  .\"  .\"
# Line 1866  Here is an example of a simple call to \ Line 2399  Here is an example of a simple call to \
2399  .sp  .sp
2400  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
2401  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,
2402  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
2403  PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last  PCRE_NO_UTF8_CHECK, PCRE_BSR_ANYCRLF, PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE,
2404  four of these are exactly the same as for \fBpcre_exec()\fP, so their  PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART.
2405  description is not repeated here.  All but the last four of these are exactly the same as for \fBpcre_exec()\fP,
2406    so their description is not repeated here.
2407  .sp  .sp
2408    PCRE_PARTIAL_HARD    PCRE_PARTIAL_HARD
2409    PCRE_PARTIAL_SOFT    PCRE_PARTIAL_SOFT
2410  .sp  .sp
2411  These have the same general effect as they do for \fBpcre_exec()\fP, but the  These have the same general effect as they do for \fBpcre_exec()\fP, but the
2412  details are slightly different. When PCRE_PARTIAL_HARD is set for  details are slightly different. When PCRE_PARTIAL_HARD is set for
# Line 1882  additional characters. This happens even Line 2416  additional characters. This happens even
2416  been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH  been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
2417  is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,  is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
2418  there have been no complete matches, but there is still at least one matching  there have been no complete matches, but there is still at least one matching
2419  possibility. The portion of the string that provided the longest partial match  possibility. The portion of the string that was inspected when the longest
2420  is set as the first matching string in both cases.  partial match was found is set as the first matching string in both cases.
2421    There is a more detailed discussion of partial and multi-segment matching, with
2422    examples, in the
2423    .\" HREF
2424    \fBpcrepartial\fP
2425    .\"
2426    documentation.
2427  .sp  .sp
2428    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
2429  .sp  .sp
# Line 1905  match. There is more discussion of this Line 2445  match. There is more discussion of this
2445  .\"  .\"
2446  documentation.  documentation.
2447  .  .
2448    .
2449  .SS "Successful returns from \fBpcre_dfa_exec()\fP"  .SS "Successful returns from \fBpcre_dfa_exec()\fP"
2450  .rs  .rs
2451  .sp  .sp
# Line 1936  returns data, even though the meaning of Line 2477  returns data, even though the meaning of
2477  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
2478  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
2479  \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
2480  the longest matches.  the longest matches. Unlike \fBpcre_exec()\fP, \fBpcre_dfa_exec()\fP can use
2481    the entire \fIovector\fP for returning matched strings.
2482    .
2483  .  .
2484  .SS "Error returns from \fBpcre_dfa_exec()\fP"  .SS "Error returns from \fBpcre_dfa_exec()\fP"
2485  .rs  .rs
# Line 1965  group. These are not supported. Line 2508  group. These are not supported.
2508    PCRE_ERROR_DFA_UMLIMIT    (-18)    PCRE_ERROR_DFA_UMLIMIT    (-18)
2509  .sp  .sp
2510  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
2511  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
2512  supported (it is meaningless).  \fImatch_limit_recursion\fP fields. This is not supported (these fields are
2513    meaningless for DFA matching).
2514  .sp  .sp
2515    PCRE_ERROR_DFA_WSSIZE     (-19)    PCRE_ERROR_DFA_WSSIZE     (-19)
2516  .sp  .sp
# Line 2003  Cambridge CB2 3QH, England. Line 2547  Cambridge CB2 3QH, England.
2547  .rs  .rs
2548  .sp  .sp
2549  .nf  .nf
2550  Last updated: 29 August 2009  Last updated: 01 December 2011
2551  Copyright (c) 1997-2009 University of Cambridge.  Copyright (c) 1997-2011 University of Cambridge.
2552  .fi  .fi

Legend:
Removed from v.428  
changed lines
  Added in v.776

webmaster@exim.org
ViewVC Help
Powered by ViewVC 1.1.12