/[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 150 by ph10, Tue Apr 17 08:22:40 2007 UTC revision 568 by ph10, Sat Nov 6 17:36:26 2010 UTC
# Line 132  an application that uses PCRE. The heade Line 132  an application that uses PCRE. The heade
132  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.
133  Applications can use these to include support for different releases of PCRE.  Applications can use these to include support for different releases of PCRE.
134  .P  .P
135    In a Windows environment, if you want to statically link an application program
136    against a non-dll \fBpcre.a\fP file, you must define PCRE_STATIC before
137    including \fBpcre.h\fP or \fBpcrecpp.h\fP, because otherwise the
138    \fBpcre_malloc()\fP and \fBpcre_free()\fP exported functions will be declared
139    \fB__declspec(dllimport)\fP, with unwanted results.
140    .P
141  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,
142  and \fBpcre_exec()\fP are used for compiling and matching regular expressions  and \fBpcre_exec()\fP are used for compiling and matching regular expressions
143  in a Perl-compatible manner. A sample program that demonstrates the simplest  in a Perl-compatible manner. A sample program that demonstrates the simplest
144  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
145  distribution. The  source distribution. A listing of this program is given in the
146    .\" HREF
147    \fBpcredemo\fP
148    .\"
149    documentation, and the
150  .\" HREF  .\" HREF
151  \fBpcresample\fP  \fBpcresample\fP
152  .\"  .\"
153  documentation describes how to run it.  documentation describes how to compile and run it.
154  .P  .P
155  A second matching function, \fBpcre_dfa_exec()\fP, which is not  A second matching function, \fBpcre_dfa_exec()\fP, which is not
156  Perl-compatible, is also provided. This uses a different algorithm for the  Perl-compatible, is also provided. This uses a different algorithm for the
157  matching. The alternative algorithm finds all possible matches (at a given  matching. The alternative algorithm finds all possible matches (at a given
158  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
159  does not return captured substrings. A description of the two matching  lookbehind assertions). However, this algorithm does not return captured
160  algorithms and their advantages and disadvantages is given in the  substrings. A description of the two matching algorithms and their advantages
161    and disadvantages is given in the
162  .\" HREF  .\" HREF
163  \fBpcrematching\fP  \fBpcrematching\fP
164  .\"  .\"
# Line 218  points during a matching operation. Deta Line 229  points during a matching operation. Deta
229  documentation.  documentation.
230  .  .
231  .  .
232    .\" HTML <a name="newlines"></a>
233  .SH NEWLINES  .SH NEWLINES
234  .rs  .rs
235  .sp  .sp
# Line 235  The default default is LF, which is the Line 247  The default default is LF, which is the
247  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
248  matched.  matched.
249  .P  .P
250    At compile time, the newline convention can be specified by the \fIoptions\fP
251    argument of \fBpcre_compile()\fP, or it can be specified by special text at the
252    start of the pattern itself; this overrides any other settings. See the
253    .\" HREF
254    \fBpcrepattern\fP
255    .\"
256    page for details of the special character sequences.
257    .P
258  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
259  pair of characters that indicate a line break". The choice of newline  pair of characters that indicate a line break". The choice of newline
260  convention affects the handling of the dot, circumflex, and dollar  convention affects the handling of the dot, circumflex, and dollar
261  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
262  recognized line ending sequence, the match position advancement for a  recognized line ending sequence, the match position advancement for a
263  non-anchored pattern. The choice of newline convention does not affect the  non-anchored pattern. There is more detail about this in the
264  interpretation of the \en or \er escape sequences.  .\" HTML <a href="#execoptions">
265    .\" </a>
266    section on \fBpcre_exec()\fP options
267    .\"
268    below.
269    .P
270    The choice of newline convention does not affect the interpretation of
271    the \en or \er escape sequences, nor does it affect what \eR matches, which is
272    controlled in a similar way, but by separate options.
273  .  .
274  .  .
275  .SH MULTITHREADING  .SH MULTITHREADING
# Line 265  which it was compiled. Details are given Line 293  which it was compiled. Details are given
293  .\" HREF  .\" HREF
294  \fBpcreprecompile\fP  \fBpcreprecompile\fP
295  .\"  .\"
296  documentation.  documentation. However, compiling a regular expression with one version of PCRE
297    for use with a different version is not guaranteed to work and may cause
298    crashes.
299  .  .
300  .  .
301  .SH "CHECKING BUILD-TIME OPTIONS"  .SH "CHECKING BUILD-TIME OPTIONS"
# Line 298  properties is available; otherwise it is Line 328  properties is available; otherwise it is
328  .sp  .sp
329  The output is an integer whose value specifies the default character sequence  The output is an integer whose value specifies the default character sequence
330  that is recognized as meaning "newline". The four values that are supported  that is recognized as meaning "newline". The four values that are supported
331  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.
332  default should normally be the standard sequence for your operating system.  Though they are derived from ASCII, the same values are returned in EBCDIC
333    environments. The default should normally correspond to the standard sequence
334    for your operating system.
335    .sp
336      PCRE_CONFIG_BSR
337    .sp
338    The output is an integer whose value indicates what character sequences the \eR
339    escape sequence matches by default. A value of 0 means that \eR matches any
340    Unicode line ending sequence; a value of 1 means that \eR matches only CR, LF,
341    or CRLF. The default can be overridden when a pattern is compiled or matched.
342  .sp  .sp
343    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
344  .sp  .sp
# Line 321  documentation. Line 360  documentation.
360  .sp  .sp
361    PCRE_CONFIG_MATCH_LIMIT    PCRE_CONFIG_MATCH_LIMIT
362  .sp  .sp
363  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
364  internal matching function calls in a \fBpcre_exec()\fP execution. Further  internal matching function calls in a \fBpcre_exec()\fP execution. Further
365  details are given with \fBpcre_exec()\fP below.  details are given with \fBpcre_exec()\fP below.
366  .sp  .sp
367    PCRE_CONFIG_MATCH_LIMIT_RECURSION    PCRE_CONFIG_MATCH_LIMIT_RECURSION
368  .sp  .sp
369  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
370  recursion when calling the internal matching function in a \fBpcre_exec()\fP  recursion when calling the internal matching function in a \fBpcre_exec()\fP
371  execution. Further details are given with \fBpcre_exec()\fP below.  execution. Further details are given with \fBpcre_exec()\fP below.
372  .sp  .sp
# Line 362  avoiding the use of the stack. Line 401  avoiding the use of the stack.
401  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
402  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
403  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,
404  \fIerrorcodeptr\fP, via which a numerical error code can be returned.  \fIerrorcodeptr\fP, via which a numerical error code can be returned. To avoid
405    too much repetition, we refer just to \fBpcre_compile()\fP below, but the
406    information applies equally to \fBpcre_compile2()\fP.
407  .P  .P
408  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
409  \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 378  argument, which is an address (see below Line 419  argument, which is an address (see below
419  .P  .P
420  The \fIoptions\fP argument contains various bit settings that affect the  The \fIoptions\fP argument contains various bit settings that affect the
421  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
422  options are described below. Some of them, in particular, those that are  options are described below. Some of them (in particular, those that are
423  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
424  the detailed description in the  within the pattern (see the detailed description in the
425  .\" HREF  .\" HREF
426  \fBpcrepattern\fP  \fBpcrepattern\fP
427  .\"  .\"
428  documentation). For these options, the contents of the \fIoptions\fP argument  documentation). For those options that can be different in different parts of
429  specifies their initial settings at the start of compilation and execution. The  the pattern, the contents of the \fIoptions\fP argument specifies their
430  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,
431  matching as well as at compile time.  PCRE_BSR_\fIxxx\fP, and PCRE_NEWLINE_\fIxxx\fP options can be set at the time
432    of matching as well as at compile time.
433  .P  .P
434  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
435  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
436  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
437  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
438  not try to free it. The offset from the start of the pattern to the character  not try to free it. The byte offset from the start of the pattern to the
439  where the error was discovered is placed in the variable pointed to by  character that was being processed when the error was discovered is placed in
440  \fIerroffset\fP, which must not be NULL. If it is, an immediate error is given.  the variable pointed to by \fIerroffset\fP, which must not be NULL. If it is,
441    an immediate error is given. Some errors are not detected until checks are
442    carried out when the whole pattern has been scanned; in this case the offset is
443    set to the end of the pattern.
444  .P  .P
445  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
446  \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 442  facility, see the Line 487  facility, see the
487  .\"  .\"
488  documentation.  documentation.
489  .sp  .sp
490      PCRE_BSR_ANYCRLF
491      PCRE_BSR_UNICODE
492    .sp
493    These options (which are mutually exclusive) control what the \eR escape
494    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
495    match any Unicode newline sequence. The default is specified when PCRE is
496    built. It can be overridden from within the pattern, or by setting an option
497    when a compiled pattern is matched.
498    .sp
499    PCRE_CASELESS    PCRE_CASELESS
500  .sp  .sp
501  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 505  set, any backslash in a pattern that is Line 559  set, any backslash in a pattern that is
559  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
560  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
561  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
562  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
563  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)
564    option setting within a pattern.
565  .sp  .sp
566    PCRE_FIRSTLINE    PCRE_FIRSTLINE
567  .sp  .sp
# Line 514  If this option is set, an unanchored pat Line 569  If this option is set, an unanchored pat
569  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
570  over the newline.  over the newline.
571  .sp  .sp
572      PCRE_JAVASCRIPT_COMPAT
573    .sp
574    If this option is set, PCRE's behaviour is changed in some ways so that it is
575    compatible with JavaScript rather than Perl. The changes are as follows:
576    .P
577    (1) A lone closing square bracket in a pattern causes a compile-time error,
578    because this is illegal in JavaScript (by default it is treated as a data
579    character). Thus, the pattern AB]CD becomes illegal when this option is set.
580    .P
581    (2) At run time, a back reference to an unset subpattern group matches an empty
582    string (by default this causes the current matching alternative to fail). A
583    pattern such as (\e1)(a) succeeds when this option is set (assuming it can find
584    an "a" in the subject), whereas it fails by default, for Perl compatibility.
585    .sp
586    PCRE_MULTILINE    PCRE_MULTILINE
587  .sp  .sp
588  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 573  were followed by ?: but named parenthese Line 642  were followed by ?: but named parenthese
642  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
643  in Perl.  in Perl.
644  .sp  .sp
645      PCRE_UCP
646    .sp
647    This option changes the way PCRE processes \eb, \ed, \es, \ew, and some of the
648    POSIX character classes. By default, only ASCII characters are recognized, but
649    if PCRE_UCP is set, Unicode properties are used instead to classify characters.
650    More details are given in the section on
651    .\" HTML <a href="pcre.html#genericchartypes">
652    .\" </a>
653    generic character types
654    .\"
655    in the
656    .\" HREF
657    \fBpcrepattern\fP
658    .\"
659    page. If you set PCRE_UCP, matching one of the items it affects takes much
660    longer. The option is available only if PCRE has been compiled with Unicode
661    property support.
662    .sp
663    PCRE_UNGREEDY    PCRE_UNGREEDY
664  .sp  .sp
665  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 599  page. Line 686  page.
686    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
687  .sp  .sp
688  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
689  automatically checked. If an invalid UTF-8 sequence of bytes is found,  automatically checked. There is a discussion about the
690  \fBpcre_compile()\fP returns an error. If you already know that your pattern is  .\" HTML <a href="pcre.html#utf8strings">
691  valid, and you want to skip this check for performance reasons, you can set the  .\" </a>
692  PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid  validity of UTF-8 strings
693  UTF-8 string as a pattern is undefined. It may cause your program to crash.  .\"
694  Note that this option can also be passed to \fBpcre_exec()\fP and  in the main
695  \fBpcre_dfa_exec()\fP, to suppress the UTF-8 validity checking of subject  .\" HREF
696  strings.  \fBpcre\fP
697    .\"
698    page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_compile()\fP
699    returns an error. If you already know that your pattern is valid, and you want
700    to skip this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK
701    option. When it is set, the effect of passing an invalid UTF-8 string as a
702    pattern is undefined. It may cause your program to crash. Note that this option
703    can also be passed to \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, to suppress
704    the UTF-8 validity checking of subject strings.
705  .  .
706  .  .
707  .SH "COMPILATION ERROR CODES"  .SH "COMPILATION ERROR CODES"
# Line 629  out of use. To avoid confusion, they hav Line 724  out of use. To avoid confusion, they hav
724     9  nothing to repeat     9  nothing to repeat
725    10  [this code is not in use]    10  [this code is not in use]
726    11  internal error: unexpected repeat    11  internal error: unexpected repeat
727    12  unrecognized character after (?    12  unrecognized character after (? or (?-
728    13  POSIX named classes are supported only within a class    13  POSIX named classes are supported only within a class
729    14  missing )    14  missing )
730    15  reference to non-existent subpattern    15  reference to non-existent subpattern
# Line 637  out of use. To avoid confusion, they hav Line 732  out of use. To avoid confusion, they hav
732    17  unknown option bit(s) set    17  unknown option bit(s) set
733    18  missing ) after comment    18  missing ) after comment
734    19  [this code is not in use]    19  [this code is not in use]
735    20  regular expression too large    20  regular expression is too large
736    21  failed to get memory    21  failed to get memory
737    22  unmatched parentheses    22  unmatched parentheses
738    23  internal error: code overflow    23  internal error: code overflow
# Line 646  out of use. To avoid confusion, they hav Line 741  out of use. To avoid confusion, they hav
741    26  malformed number or name after (?(    26  malformed number or name after (?(
742    27  conditional group contains more than two branches    27  conditional group contains more than two branches
743    28  assertion expected after (?(    28  assertion expected after (?(
744    29  (?R or (?digits must be followed by )    29  (?R or (?[+-]digits must be followed by )
745    30  unknown POSIX class name    30  unknown POSIX class name
746    31  POSIX collating elements are not supported    31  POSIX collating elements are not supported
747    32  this version of PCRE is not compiled with PCRE_UTF8 support    32  this version of PCRE is not compiled with PCRE_UTF8 support
# Line 666  out of use. To avoid confusion, they hav Line 761  out of use. To avoid confusion, they hav
761    46  malformed \eP or \ep sequence    46  malformed \eP or \ep sequence
762    47  unknown property name after \eP or \ep    47  unknown property name after \eP or \ep
763    48  subpattern name is too long (maximum 32 characters)    48  subpattern name is too long (maximum 32 characters)
764    49  too many named subpatterns (maximum 10,000)    49  too many named subpatterns (maximum 10000)
765    50  repeated subpattern is too long    50  [this code is not in use]
766    51  octal value is greater than \e377 (not in UTF-8 mode)    51  octal value is greater than \e377 (not in UTF-8 mode)
767    52  internal error: overran compiling workspace    52  internal error: overran compiling workspace
768    53  internal error: previously-checked referenced subpattern not found    53  internal error: previously-checked referenced subpattern
769            not found
770    54  DEFINE group contains more than one branch    54  DEFINE group contains more than one branch
771    55  repeating a DEFINE group is not allowed    55  repeating a DEFINE group is not allowed
772    56  inconsistent NEWLINE options"    56  inconsistent NEWLINE options
773      57  \eg is not followed by a braced, angle-bracketed, or quoted
774            name/number or by a plain number
775      58  a numbered reference must not be zero
776      59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
777      60  (*VERB) not recognized
778      61  number is too big
779      62  subpattern name expected
780      63  digit expected after (?+
781      64  ] is an invalid data character in JavaScript compatibility mode
782      65  different names for subpatterns of the same number are
783            not allowed
784      66  (*MARK) must have an argument
785      67  this version of PCRE is not compiled with PCRE_UCP support
786    .sp
787    The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
788    be used if the limits were changed when PCRE was built.
789  .  .
790  .  .
791  .SH "STUDYING A PATTERN"  .SH "STUDYING A PATTERN"
# Line 692  help speed up matching, \fBpcre_study()\ Line 804  help speed up matching, \fBpcre_study()\
804  results of the study.  results of the study.
805  .P  .P
806  The returned value from \fBpcre_study()\fP can be passed directly to  The returned value from \fBpcre_study()\fP can be passed directly to
807  \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
808  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
809  described  passed; these are described
810  .\" HTML <a href="#extradata">  .\" HTML <a href="#extradata">
811  .\" </a>  .\" </a>
812  below  below
813  .\"  .\"
814  in the section on matching a pattern.  in the section on matching a pattern.
815  .P  .P
816  If studying the pattern does not produce any additional information  If studying the pattern does not produce any useful information,
817  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program
818  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
819  own \fBpcre_extra\fP block.  \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block.
820  .P  .P
821  The second argument of \fBpcre_study()\fP contains option bits. At present, no  The second argument of \fBpcre_study()\fP contains option bits. At present, no
822  options are defined, and this argument should always be zero.  options are defined, and this argument should always be zero.
# Line 724  This is a typical call to \fBpcre_study\ Line 836  This is a typical call to \fBpcre_study\
836      0,              /* no options exist */      0,              /* no options exist */
837      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
838  .sp  .sp
839  At present, studying a pattern is useful only for non-anchored patterns that do  Studying a pattern does two things: first, a lower bound for the length of
840  not have a single fixed starting character. A bitmap of possible starting  subject string that is needed to match the pattern is computed. This does not
841  bytes is created.  mean that there are any strings of that length that match, but it does
842    guarantee that no shorter strings match. The value is used by
843    \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP to avoid wasting time by trying to
844    match strings that are shorter than the lower bound. You can find out the value
845    in a calling program via the \fBpcre_fullinfo()\fP function.
846    .P
847    Studying a pattern is also useful for non-anchored patterns that do not have a
848    single fixed starting character. A bitmap of possible starting bytes is
849    created. This speeds up finding a position in the subject at which to start
850    matching.
851    .P
852    The two optimizations just described can be disabled by setting the
853    PCRE_NO_START_OPTIMIZE option when calling \fBpcre_exec()\fP or
854    \fBpcre_dfa_exec()\fP. You might want to do this if your pattern contains
855    callouts, or make use of (*MARK), and you make use of these in cases where
856    matching fails. See the discussion of PCRE_NO_START_OPTIMIZE
857    .\" HTML <a href="#execoptions">
858    .\" </a>
859    below.
860    .\"
861  .  .
862  .  .
863  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
# Line 736  bytes is created. Line 867  bytes is created.
867  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters,
868  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
869  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
870  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
871  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
872  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
873  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
874  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
875    handling characters with codes greater than 128, you should either use UTF-8
876    and Unicode, or use locales, but not try to mix the two.
877  .P  .P
878  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
879  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 869  table indicating a fixed set of bytes fo Line 1002  table indicating a fixed set of bytes fo
1002  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
1003  fourth argument should point to an \fBunsigned char *\fP variable.  fourth argument should point to an \fBunsigned char *\fP variable.
1004  .sp  .sp
1005      PCRE_INFO_HASCRORLF
1006    .sp
1007    Return 1 if the pattern contains any explicit matches for CR or LF characters,
1008    otherwise 0. The fourth argument should point to an \fBint\fP variable. An
1009    explicit match is either a literal CR or LF character, or \er or \en.
1010    .sp
1011      PCRE_INFO_JCHANGED
1012    .sp
1013    Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise
1014    0. The fourth argument should point to an \fBint\fP variable. (?J) and
1015    (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
1016    .sp
1017    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
1018  .sp  .sp
1019  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 879  follows something of variable length. Fo Line 1024  follows something of variable length. Fo
1024  /^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
1025  is -1.  is -1.
1026  .sp  .sp
1027      PCRE_INFO_MINLENGTH
1028    .sp
1029    If the pattern was studied and a minimum length for matching subject strings
1030    was computed, its value is returned. Otherwise the returned value is -1. The
1031    value is a number of characters, not bytes (this may be relevant in UTF-8
1032    mode). The fourth argument should point to an \fBint\fP variable. A
1033    non-negative value is a lower bound to the length of any matching string. There
1034    may not be any strings of that length that do actually match, but every string
1035    that does match is at least that long.
1036    .sp
1037    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
1038    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
1039    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
# Line 899  entry; both of these return an \fBint\fP Line 1054  entry; both of these return an \fBint\fP
1054  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
1055  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
1056  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
1057  rest of the entry is the corresponding name, zero terminated. The names are in  rest of the entry is the corresponding name, zero terminated.
1058  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of  .P
1059  their parentheses numbers. For example, consider the following pattern (assume  The names are in alphabetical order. Duplicate names may appear if (?| is used
1060  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  to create multiple groups with the same number, as described in the
1061    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1062    .\" </a>
1063    section on duplicate subpattern numbers
1064    .\"
1065    in the
1066    .\" HREF
1067    \fBpcrepattern\fP
1068    .\"
1069    page. Duplicate names for subpatterns with different numbers are permitted only
1070    if PCRE_DUPNAMES is set. In all cases of duplicate names, they appear in the
1071    table in the order in which they were found in the pattern. In the absence of
1072    (?| this is the order of increasing number; when (?| is used this is not
1073    necessarily the case because later subpatterns may have lower numbers.
1074    .P
1075    As a simple example of the name/number table, consider the following pattern
1076    (assume PCRE_EXTENDED is set, so white space - including newlines - is
1077    ignored):
1078  .sp  .sp
1079  .\" JOIN  .\" JOIN
1080    (?<date> (?<year>(\ed\ed)?\ed\ed) -    (?<date> (?<year>(\ed\ed)?\ed\ed) -
# Line 921  When writing code to extract data from n Line 1093  When writing code to extract data from n
1093  name-to-number map, remember that the length of the entries is likely to be  name-to-number map, remember that the length of the entries is likely to be
1094  different for each compiled pattern.  different for each compiled pattern.
1095  .sp  .sp
1096      PCRE_INFO_OKPARTIAL
1097    .sp
1098    Return 1 if the pattern can be used for partial matching with
1099    \fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
1100    \fBint\fP variable. From release 8.00, this always returns 1, because the
1101    restrictions that previously applied to partial matching have been lifted. The
1102    .\" HREF
1103    \fBpcrepartial\fP
1104    .\"
1105    documentation gives details of partial matching.
1106    .sp
1107    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1108  .sp  .sp
1109  Return a copy of the options with which the pattern was compiled. The fourth  Return a copy of the options with which the pattern was compiled. The fourth
1110  argument should point to an \fBunsigned long int\fP variable. These option bits  argument should point to an \fBunsigned long int\fP variable. These option bits
1111  are those specified in the call to \fBpcre_compile()\fP, modified by any  are those specified in the call to \fBpcre_compile()\fP, modified by any
1112  top-level option settings within the pattern itself.  top-level option settings at the start of the pattern itself. In other words,
1113    they are the options that will be in force when matching starts. For example,
1114    if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED option, the
1115    result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED.
1116  .P  .P
1117  A pattern is automatically anchored by PCRE if all of its top-level  A pattern is automatically anchored by PCRE if all of its top-level
1118  alternatives begin with one of the following:  alternatives begin with one of the following:
# Line 953  variable. Line 1139  variable.
1139  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
1140  a \fBpcre_extra\fP block. That is, it is the value that was passed to  a \fBpcre_extra\fP block. That is, it is the value that was passed to
1141  \fBpcre_malloc()\fP when PCRE was getting memory into which to place the data  \fBpcre_malloc()\fP when PCRE was getting memory into which to place the data
1142  created by \fBpcre_study()\fP. The fourth argument should point to a  created by \fBpcre_study()\fP. If \fBpcre_extra\fP is NULL, or there is no
1143    study data, zero is returned. The fourth argument should point to a
1144  \fBsize_t\fP variable.  \fBsize_t\fP variable.
1145  .  .
1146  .  .
# Line 1015  is different. (This seems a highly unlik Line 1202  is different. (This seems a highly unlik
1202  .P  .P
1203  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
1204  compiled pattern, which is passed in the \fIcode\fP argument. If the  compiled pattern, which is passed in the \fIcode\fP argument. If the
1205  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
1206  \fIextra\fP argument. This function is the main matching facility of the  \fIextra\fP argument. This function is the main matching facility of the
1207  library, and it operates in a Perl-like manner. For specialist use there is  library, and it operates in a Perl-like manner. For specialist use there is
1208  also an alternative matching function, which is described  also an alternative matching function, which is described
# Line 1065  fields (not necessarily in this order): Line 1252  fields (not necessarily in this order):
1252    unsigned long int \fImatch_limit_recursion\fP;    unsigned long int \fImatch_limit_recursion\fP;
1253    void *\fIcallout_data\fP;    void *\fIcallout_data\fP;
1254    const unsigned char *\fItables\fP;    const unsigned char *\fItables\fP;
1255      unsigned char **\fImark\fP;
1256  .sp  .sp
1257  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
1258  are set. The flag bits are:  are set. The flag bits are:
# Line 1074  are set. The flag bits are: Line 1262  are set. The flag bits are:
1262    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1263    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1264    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1265      PCRE_EXTRA_MARK
1266  .sp  .sp
1267  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 is set in the
1268  \fBpcre_extra\fP block that is returned by \fBpcre_study()\fP, together with  \fBpcre_extra\fP block that is returned by \fBpcre_study()\fP, together with
# Line 1083  the block by setting the other fields an Line 1272  the block by setting the other fields an
1272  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
1273  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,
1274  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
1275  classic example is the use of nested unlimited repeats.  classic example is a pattern that uses nested unlimited repeats.
1276  .P  .P
1277  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly
1278  (sometimes recursively). The limit set by \fImatch_limit\fP is imposed on the  (sometimes recursively). The limit set by \fImatch_limit\fP is imposed on the
# Line 1116  with a \fBpcre_extra\fP block in which \ Line 1305  with a \fBpcre_extra\fP block in which \
1305  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
1306  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1307  .P  .P
1308  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,
1309  which is described in the  and is described in the
1310  .\" HREF  .\" HREF
1311  \fBpcrecallout\fP  \fBpcrecallout\fP
1312  .\"  .\"
# Line 1136  called. See the Line 1325  called. See the
1325  \fBpcreprecompile\fP  \fBpcreprecompile\fP
1326  .\"  .\"
1327  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1328    .P
1329    If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1330    be set to point to a \fBchar *\fP variable. If the pattern contains any
1331    backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1332    a name to pass back, a pointer to the name string (zero terminated) is placed
1333    in the variable pointed to by the \fImark\fP field. The names are within the
1334    compiled pattern; if you wish to retain such a name you must copy it before
1335    freeing the memory of a compiled pattern. If there is no name to pass back, the
1336    variable pointed to by the \fImark\fP field set to NULL. For details of the
1337    backtracking control verbs, see the section entitled
1338    .\" HTML <a href="pcrepattern#backtrackcontrol">
1339    .\" </a>
1340    "Backtracking control"
1341    .\"
1342    in the
1343    .\" HREF
1344    \fBpcrepattern\fP
1345    .\"
1346    documentation.
1347  .  .
1348    .
1349    .\" HTML <a name="execoptions"></a>
1350  .SS "Option bits for \fBpcre_exec()\fP"  .SS "Option bits for \fBpcre_exec()\fP"
1351  .rs  .rs
1352  .sp  .sp
1353  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
1354  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,
1355  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1356    PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
1357    PCRE_PARTIAL_HARD.
1358  .sp  .sp
1359    PCRE_ANCHORED    PCRE_ANCHORED
1360  .sp  .sp
# Line 1151  matching position. If a pattern was comp Line 1363  matching position. If a pattern was comp
1363  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
1364  matching time.  matching time.
1365  .sp  .sp
1366      PCRE_BSR_ANYCRLF
1367      PCRE_BSR_UNICODE
1368    .sp
1369    These options (which are mutually exclusive) control what the \eR escape
1370    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
1371    match any Unicode newline sequence. These options override the choice that was
1372    made or defaulted when the pattern was compiled.
1373    .sp
1374    PCRE_NEWLINE_CR    PCRE_NEWLINE_CR
1375    PCRE_NEWLINE_LF    PCRE_NEWLINE_LF
1376    PCRE_NEWLINE_CRLF    PCRE_NEWLINE_CRLF
# Line 1162  the pattern was compiled. For details, s Line 1382  the pattern was compiled. For details, s
1382  \fBpcre_compile()\fP above. During matching, the newline choice affects the  \fBpcre_compile()\fP above. During matching, the newline choice affects the
1383  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1384  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
1385  pattern. When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is  pattern.
1386  set, and a match attempt fails when the current position is at a CRLF sequence,  .P
1387  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
1388  words, to after the CRLF.  match attempt for an unanchored pattern fails when the current position is at a
1389    CRLF sequence, and the pattern contains no explicit matches for CR or LF
1390    characters, the match position is advanced by two characters instead of one, in
1391    other words, to after the CRLF.
1392    .P
1393    The above rule is a compromise that makes the most common cases work as
1394    expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
1395    set), it does not match the string "\er\enA" because, after failing at the
1396    start, it skips both the CR and the LF before retrying. However, the pattern
1397    [\er\en]A does match that string, because it contains an explicit CR or LF
1398    reference, and so advances only by one character after the first failure.
1399    .P
1400    An explicit match for CR of LF is either a literal appearance of one of those
1401    characters, or one of the \er or \en escape sequences. Implicit matches such as
1402    [^X] do not count, nor does \es (which includes CR and LF in the characters
1403    that it matches).
1404    .P
1405    Notwithstanding the above, anomalous effects may still occur when CRLF is a
1406    valid newline sequence and explicit \er or \en escapes appear in the pattern.
1407  .sp  .sp
1408    PCRE_NOTBOL    PCRE_NOTBOL
1409  .sp  .sp
# Line 1191  match the empty string, the entire match Line 1429  match the empty string, the entire match
1429  .sp  .sp
1430    a?b?    a?b?
1431  .sp  .sp
1432  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
1433  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
1434  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".
1435  .P  .sp
1436  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case    PCRE_NOTEMPTY_ATSTART
1437  of a pattern match of the empty string within its \fBsplit()\fP function, and  .sp
1438  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
1439  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
1440  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the  can occur only if the pattern contains \eK.
1441  starting offset (see below) and trying an ordinary match again. There is some  .P
1442  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
1443    does make a special case of a pattern match of the empty string within its
1444    \fBsplit()\fP function, and when using the /g modifier. It is possible to
1445    emulate Perl's behaviour after matching a null string by first trying the match
1446    again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
1447    if that fails, by advancing the starting offset (see below) and trying an
1448    ordinary match again. There is some code that demonstrates how to do this in
1449    the
1450    .\" HREF
1451    \fBpcredemo\fP
1452    .\"
1453    sample program. In the most general case, you have to check to see if the
1454    newline convention recognizes CRLF as a newline, and if so, and the current
1455    character is CR followed by LF, advance the starting offset by two characters
1456    instead of one.
1457    .sp
1458      PCRE_NO_START_OPTIMIZE
1459    .sp
1460    There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1461    a match, in order to speed up the process. For example, if it is known that an
1462    unanchored match must start with a specific character, it searches the subject
1463    for that character, and fails immediately if it cannot find it, without
1464    actually running the main matching function. This means that a special item
1465    such as (*COMMIT) at the start of a pattern is not considered until after a
1466    suitable starting point for the match has been found. When callouts or (*MARK)
1467    items are in use, these "start-up" optimizations can cause them to be skipped
1468    if the pattern is never actually used. The start-up optimizations are in effect
1469    a pre-scan of the subject that takes place before the pattern is run.
1470    .P
1471    The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
1472    causing performance to suffer, but ensuring that in cases where the result is
1473    "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
1474    are considered at every possible starting position in the subject string.
1475    Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
1476    Consider the pattern
1477    .sp
1478      (*COMMIT)ABC
1479    .sp
1480    When this is compiled, PCRE records the fact that a match must start with the
1481    character "A". Suppose the subject string is "DEFABC". The start-up
1482    optimization scans along the subject, finds "A" and runs the first match
1483    attempt from there. The (*COMMIT) item means that the pattern must match the
1484    current starting position, which in this case, it does. However, if the same
1485    match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
1486    subject string does not happen. The first match attempt is run starting from
1487    "D" and when this fails, (*COMMIT) prevents any further matches being tried, so
1488    the overall result is "no match". If the pattern is studied, more start-up
1489    optimizations may be used. For example, a minimum length for the subject may be
1490    recorded. Consider the pattern
1491    .sp
1492      (*MARK:A)(X|Y)
1493    .sp
1494    The minimum length for a match is one character. If the subject is "ABC", there
1495    will be attempts to match "ABC", "BC", "C", and then finally an empty string.
1496    If the pattern is studied, the final attempt does not take place, because PCRE
1497    knows that the subject is too short, and so the (*MARK) is never encountered.
1498    In this case, studying the pattern does not affect the overall match result,
1499    which is still "no match", but it does affect the auxiliary information that is
1500    returned.
1501  .sp  .sp
1502    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1503  .sp  .sp
1504  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
1505  string is automatically checked when \fBpcre_exec()\fP is subsequently called.  string is automatically checked when \fBpcre_exec()\fP is subsequently called.
1506  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
1507  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
1508  \fBpcre_exec()\fP returns the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP  strings in the
1509  contains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.  .\" HTML <a href="pcre.html#utf8strings">
1510    .\" </a>
1511    section on UTF-8 support
1512    .\"
1513    in the main
1514    .\" HREF
1515    \fBpcre\fP
1516    .\"
1517    page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns
1518    the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP contains a value that does
1519    not point to the start of a UTF-8 character (or to the end of the subject),
1520    PCRE_ERROR_BADUTF8_OFFSET is returned.
1521  .P  .P
1522  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
1523  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
1524  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
1525  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
1526  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
1527  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
1528  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
1529  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
1530  UTF-8 character, is undefined. Your program may crash.  undefined. Your program may crash.
1531  .sp  .sp
1532    PCRE_PARTIAL    PCRE_PARTIAL_HARD
1533  .sp    PCRE_PARTIAL_SOFT
1534  This option turns on the partial matching feature. If the subject string fails  .sp
1535  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
1536  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
1537  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
1538  characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of  not enough subject characters to complete the match. If this happens when
1539  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
1540  may appear in the pattern. These are discussed in the  testing any remaining alternatives. Only if no complete match can be found is
1541    PCRE_ERROR_PARTIAL returned instead of PCRE_ERROR_NOMATCH. In other words,
1542    PCRE_PARTIAL_SOFT says that the caller is prepared to handle a partial match,
1543    but only if no complete match can be found.
1544    .P
1545    If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
1546    partial match is found, \fBpcre_exec()\fP immediately returns
1547    PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
1548    when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
1549    important that an alternative complete match.
1550    .P
1551    In both cases, the portion of the string that was inspected when the partial
1552    match was found is set as the first matching string. There is a more detailed
1553    discussion of partial and multi-segment matching, with examples, in the
1554  .\" HREF  .\" HREF
1555  \fBpcrepartial\fP  \fBpcrepartial\fP
1556  .\"  .\"
1557  documentation.  documentation.
1558  .  .
1559    .
1560  .SS "The string to be matched by \fBpcre_exec()\fP"  .SS "The string to be matched by \fBpcre_exec()\fP"
1561  .rs  .rs
1562  .sp  .sp
1563  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
1564  \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
1565  \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
1566  UTF-8 character. Unlike the pattern string, the subject may contain binary zero  subject, \fBpcre_exec()\fP returns PCRE_ERROR_BADOFFSET.
1567  bytes. When the starting offset is zero, the search for a match starts at the  .P
1568  beginning of the subject, and this is by far the most common case.  In UTF-8 mode, the byte offset must point to the start of a UTF-8 character (or
1569    the end of the subject). Unlike the pattern string, the subject may contain
1570    binary zero bytes. When the starting offset is zero, the search for a match
1571    starts at the beginning of the subject, and this is by far the most common
1572    case.
1573  .P  .P
1574  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
1575  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 1264  start of the subject, which is deemed to Line 1589  start of the subject, which is deemed to
1589  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
1590  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.
1591  .P  .P
1592    Finding all the matches in a subject is tricky when the pattern can match an
1593    empty string. It is possible to emulate Perl's /g behaviour by first trying the
1594    match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
1595    PCRE_ANCHORED options, and then if that fails, advancing the starting offset
1596    and trying an ordinary match again. There is some code that demonstrates how to
1597    do this in the
1598    .\" HREF
1599    \fBpcredemo\fP
1600    .\"
1601    sample program. In the most general case, you have to check to see if the
1602    newline convention recognizes CRLF as a newline, and if so, and the current
1603    character is CR followed by LF, advance the starting offset by two characters
1604    instead of one.
1605    .P
1606  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
1607  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
1608  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.
1609  .  .
1610    .
1611  .SS "How \fBpcre_exec()\fP returns captured substrings"  .SS "How \fBpcre_exec()\fP returns captured substrings"
1612  .rs  .rs
1613  .sp  .sp
# Line 1278  pattern. Following the usage in Jeffrey Line 1618  pattern. Following the usage in Jeffrey
1618  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
1619  kinds of parenthesized subpattern that do not cause substrings to be captured.  kinds of parenthesized subpattern that do not cause substrings to be captured.
1620  .P  .P
1621  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
1622  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
1623  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
1624  this argument is NOT the size of \fIovector\fP in bytes.  argument is NOT the size of \fIovector\fP in bytes.
1625  .P  .P
1626  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,
1627  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
1628  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
1629  and is not available for passing back information. The length passed in  and is not available for passing back information. The number passed in
1630  \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
1631  rounded down.  rounded down.
1632  .P  .P
1633  When a match is successful, information about captured substrings is returned  When a match is successful, information about captured substrings is returned
1634  in pairs of integers, starting at the beginning of \fIovector\fP, and  in pairs of integers, starting at the beginning of \fIovector\fP, and
1635  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
1636  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
1637  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
1638  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
1639  subject string matched by the entire pattern. The next pair is used for the  mode. They are not character counts.
1640  first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fP  .P
1641  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
1642  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
1643  capturing subpatterns, the return value from a successful match is 1,  used for the first capturing subpattern, and so on. The value returned by
1644  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.
1645    For example, if two substrings have been captured, the returned value is 3. If
1646    there are no capturing subpatterns, the return value from a successful match is
1647    1, indicating that just the first pair of offsets has been set.
1648  .P  .P
1649  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
1650  string that it matched that is returned.  string that it matched that is returned.
1651  .P  .P
1652  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
1653  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
1654  returns a value of zero. In particular, if the substring offsets are not of  returns a value of zero. If the substring offsets are not of interest,
1655  interest, \fBpcre_exec()\fP may be called with \fIovector\fP passed as NULL and  \fBpcre_exec()\fP may be called with \fIovector\fP passed as NULL and
1656  \fIovecsize\fP as zero. However, if the pattern contains back references and  \fIovecsize\fP as zero. However, if the pattern contains back references and
1657  the \fIovector\fP is not big enough to remember the related substrings, PCRE  the \fIovector\fP is not big enough to remember the related substrings, PCRE
1658  has to get additional memory for use during matching. Thus it is usually  has to get additional memory for use during matching. Thus it is usually
1659  advisable to supply an \fIovector\fP.  advisable to supply an \fIovector\fP.
1660  .P  .P
1661  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
1662  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1663  \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
1664  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 1331  Offset values that correspond to unused Line 1674  Offset values that correspond to unused
1674  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
1675  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
1676  return from the function is 2, because the highest used capturing subpattern  return from the function is 2, because the highest used capturing subpattern
1677  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
1678  capturing subpatterns if you wish (assuming the vector is large enough, of  (assuming the vector is large enough, of course) are set to -1.
1679  course).  .P
1680    \fBNote\fP: Elements of \fIovector\fP that do not correspond to capturing
1681    parentheses in the pattern are never changed. That is, if a pattern contains
1682    \fIn\fP capturing parentheses, no more than \fIovector[0]\fP to
1683    \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other elements retain
1684    whatever values they previously had.
1685  .P  .P
1686  Some convenience functions are provided for extracting the captured substrings  Some convenience functions are provided for extracting the captured substrings
1687  as separate strings. These are described below.  as separate strings. These are described below.
# Line 1379  If a pattern contains back references, b Line 1727  If a pattern contains back references, b
1727  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
1728  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
1729  automatically freed at the end of matching.  automatically freed at the end of matching.
1730    .P
1731    This error is also given if \fBpcre_stack_malloc()\fP fails in
1732    \fBpcre_exec()\fP. This can happen only when PCRE has been compiled with
1733    \fB--disable-stack-for-recursion\fP.
1734  .sp  .sp
1735    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1736  .sp  .sp
# Line 1420  documentation for details of partial mat Line 1772  documentation for details of partial mat
1772  .sp  .sp
1773    PCRE_ERROR_BADPARTIAL     (-13)    PCRE_ERROR_BADPARTIAL     (-13)
1774  .sp  .sp
1775  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
1776  are not supported for partial matching. See the  option was used with a compiled pattern containing items that were not
1777  .\" HREF  supported for partial matching. From release 8.00 onwards, there are no
1778  \fBpcrepartial\fP  restrictions on partial matching.
 .\"  
 documentation for details of partial matching.  
1779  .sp  .sp
1780    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
1781  .sp  .sp
# Line 1442  The internal recursion limit, as specifi Line 1792  The internal recursion limit, as specifi
1792  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
1793  description above.  description above.
1794  .sp  .sp
   PCRE_ERROR_NULLWSLIMIT    (-22)  
 .sp  
 When a group 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. Some workspace is required for this; if it runs out, this error is  
 given.  
 .sp  
1795    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
1796  .sp  .sp
1797  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
1798    .sp
1799      PCRE_ERROR_BADOFFSET      (-24)
1800    .sp
1801    The value of \fIstartoffset\fP was negative or greater than the length of the
1802    subject, that is, the value in \fIlength\fP.
1803  .P  .P
1804  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.
1805  .  .
1806  .  .
1807  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
# Line 1603  These functions call \fBpcre_get_stringn Line 1950  These functions call \fBpcre_get_stringn
1950  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
1951  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,
1952  the behaviour may not be what you want (see the next section).  the behaviour may not be what you want (see the next section).
1953  .  .P
1954    \fBWarning:\fP If the pattern uses the (?| feature to set up multiple
1955    subpatterns with the same number, as described in the
1956    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1957    .\" </a>
1958    section on duplicate subpattern numbers
1959    .\"
1960    in the
1961    .\" HREF
1962    \fBpcrepattern\fP
1963    .\"
1964    page, you cannot use names to distinguish the different subpatterns, because
1965    names are not included in the compiled code. The matching process uses only
1966    numbers. For this reason, the use of different names for subpatterns of the
1967    same number causes an error at compile time.
1968  .  .
1969  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
1970  .rs  .rs
# Line 1613  the behaviour may not be what you want ( Line 1974  the behaviour may not be what you want (
1974  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
1975  .PP  .PP
1976  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
1977  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
1978  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
1979  example is shown in the  such subpatterns are named, they are required to use the same names.)
1980    .P
1981    Normally, patterns with duplicate names are such that in any one match, only
1982    one of the named subpatterns participates. An example is shown in the
1983  .\" HREF  .\" HREF
1984  \fBpcrepattern\fP  \fBpcrepattern\fP
1985  .\"  .\"
1986  documentation. When duplicates are present, \fBpcre_copy_named_substring()\fP  documentation.
1987  and \fBpcre_get_named_substring()\fP return the first substring corresponding  .P
1988  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
1989  The \fBpcre_get_stringnumber()\fP function returns one of the numbers that are  \fBpcre_get_named_substring()\fP return the first substring corresponding to
1990  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
1991  .sp  returned; no data is returned. The \fBpcre_get_stringnumber()\fP function
1992    returns one of the numbers that are associated with the name, but it is not
1993    defined which it is.
1994    .P
1995  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,
1996  you must use the \fBpcre_get_stringtable_entries()\fP function. The first  you must use the \fBpcre_get_stringtable_entries()\fP function. The first
1997  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 1676  a compiled pattern, using a matching alg Line 2043  a compiled pattern, using a matching alg
2043  just once, and does not backtrack. This has different characteristics to the  just once, and does not backtrack. This has different characteristics to the
2044  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
2045  patterns are not supported. Nevertheless, there are times when this kind of  patterns are not supported. Nevertheless, there are times when this kind of
2046  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
2047  the  list of features that \fBpcre_dfa_exec()\fP does not support, see the
2048  .\" HREF  .\" HREF
2049  \fBpcrematching\fP  \fBpcrematching\fP
2050  .\"  .\"
# Line 1716  Here is an example of a simple call to \ Line 2083  Here is an example of a simple call to \
2083  .sp  .sp
2084  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
2085  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,
2086  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
2087  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,
2088  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.
2089  .sp  All but the last four of these are exactly the same as for \fBpcre_exec()\fP,
2090    PCRE_PARTIAL  so their description is not repeated here.
2091  .sp  .sp
2092  This has the same general effect as it does for \fBpcre_exec()\fP, but the    PCRE_PARTIAL_HARD
2093  details are slightly different. When PCRE_PARTIAL is set for    PCRE_PARTIAL_SOFT
2094  \fBpcre_dfa_exec()\fP, the return code PCRE_ERROR_NOMATCH is converted into  .sp
2095  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
2096  complete matches, but there is still at least one matching possibility. The  details are slightly different. When PCRE_PARTIAL_HARD is set for
2097  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
2098  matching string.  is reached and there is still at least one matching possibility that requires
2099    additional characters. This happens even if some complete matches have also
2100    been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
2101    is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
2102    there have been no complete matches, but there is still at least one matching
2103    possibility. The portion of the string that was inspected when the longest
2104    partial match was found is set as the first matching string in both cases.
2105    There is a more detailed discussion of partial and multi-segment matching, with
2106    examples, in the
2107    .\" HREF
2108    \fBpcrepartial\fP
2109    .\"
2110    documentation.
2111  .sp  .sp
2112    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
2113  .sp  .sp
# Line 1739  matching point in the subject string. Line 2118  matching point in the subject string.
2118  .sp  .sp
2119    PCRE_DFA_RESTART    PCRE_DFA_RESTART
2120  .sp  .sp
2121  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
2122  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
2123  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
2124  option requests this action; when it is set, the \fIworkspace\fP and  \fIworkspace\fP and \fIwscount\fP options must reference the same vector as
2125  \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
2126  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  
2127  .\" HREF  .\" HREF
2128  \fBpcrepartial\fP  \fBpcrepartial\fP
2129  .\"  .\"
# Line 1849  Cambridge CB2 3QH, England. Line 2227  Cambridge CB2 3QH, England.
2227  .rs  .rs
2228  .sp  .sp
2229  .nf  .nf
2230  Last updated: 16 April 2007  Last updated: 06 November 2010
2231  Copyright (c) 1997-2007 University of Cambridge.  Copyright (c) 1997-2010 University of Cambridge.
2232  .fi  .fi

Legend:
Removed from v.150  
changed lines
  Added in v.568

  ViewVC Help
Powered by ViewVC 1.1.5