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revision 139 by ph10, Fri Mar 30 13:41:47 2007 UTC revision 525 by ph10, Wed May 26 10:50:24 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, because otherwise the \fBpcre_malloc()\fP and
138    \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
236  PCRE supports four different conventions for indicating line breaks in  PCRE supports five different conventions for indicating line breaks in
237  strings: a single CR (carriage return) character, a single LF (linefeed)  strings: a single CR (carriage return) character, a single LF (linefeed)
238  character, the two-character sequence CRLF, or any Unicode newline sequence.  character, the two-character sequence CRLF, any of the three preceding, or any
239  The Unicode newline sequences are the three just mentioned, plus the single  Unicode newline sequence. The Unicode newline sequences are the three just
240  characters VT (vertical tab, U+000B), FF (formfeed, U+000C), NEL (next line,  mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed,
241  U+0085), LS (line separator, U+2028), and PS (paragraph separator, U+2029).  U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
242    (paragraph separator, U+2029).
243  .P  .P
244  Each of the first three conventions is used by at least one operating system as  Each of the first three conventions is used by at least one operating system as
245  its standard newline sequence. When PCRE is built, a default can be specified.  its standard newline sequence. When PCRE is built, a default can be specified.
# Line 234  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 264  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 297  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, and -1 for ANY. The default should  are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF, and -1 for ANY.
332  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 320  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 361  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 377  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 441  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 504  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 513  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 532  occurrences of ^ or $ in a pattern, sett Line 602  occurrences of ^ or $ in a pattern, sett
602    PCRE_NEWLINE_CR    PCRE_NEWLINE_CR
603    PCRE_NEWLINE_LF    PCRE_NEWLINE_LF
604    PCRE_NEWLINE_CRLF    PCRE_NEWLINE_CRLF
605      PCRE_NEWLINE_ANYCRLF
606    PCRE_NEWLINE_ANY    PCRE_NEWLINE_ANY
607  .sp  .sp
608  These options override the default newline definition that was chosen when PCRE  These options override the default newline definition that was chosen when PCRE
609  was built. Setting the first or the second specifies that a newline is  was built. Setting the first or the second specifies that a newline is
610  indicated by a single character (CR or LF, respectively). Setting  indicated by a single character (CR or LF, respectively). Setting
611  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
612  CRLF sequence. Setting PCRE_NEWLINE_ANY specifies that any Unicode newline  CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three
613  sequence should be recognized. The Unicode newline sequences are the three just  preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies
614  mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed,  that any Unicode newline sequence should be recognized. The Unicode newline
615  U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS  sequences are the three just mentioned, plus the single characters VT (vertical
616  (paragraph separator, U+2029). The last two are recognized only in UTF-8 mode.  tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS (line
617    separator, U+2028), and PS (paragraph separator, U+2029). The last two are
618    recognized only in UTF-8 mode.
619  .P  .P
620  The newline setting in the options word uses three bits that are treated  The newline setting in the options word uses three bits that are treated
621  as a number, giving eight possibilities. Currently only five are used (default  as a number, giving eight possibilities. Currently only six are used (default
622  plus the four values above). This means that if you set more than one newline  plus the five values above). This means that if you set more than one newline
623  option, the combination may or may not be sensible. For example,  option, the combination may or may not be sensible. For example,
624  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
625  other combinations yield unused numbers and cause an error.  other combinations may yield unused numbers and cause an error.
626  .P  .P
627  The only time that a line break is specially recognized when compiling a  The only time that a line break is specially recognized when compiling a
628  pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character  pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character
# Line 569  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 595  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 625  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 633  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 642  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 662  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 not found
769    54  DEFINE group contains more than one branch    54  DEFINE group contains more than one branch
770    55  repeating a DEFINE group is not allowed    55  repeating a DEFINE group is not allowed
771    56  inconsistent NEWLINE options"    56  inconsistent NEWLINE options
772      57  \eg is not followed by a braced, angle-bracketed, or quoted
773            name/number or by a plain number
774      58  a numbered reference must not be zero
775      59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
776      60  (*VERB) not recognized
777      61  number is too big
778      62  subpattern name expected
779      63  digit expected after (?+
780      64  ] is an invalid data character in JavaScript compatibility mode
781      65  different names for subpatterns of the same number are not allowed
782      66  (*MARK) must have an argument
783      67  this version of PCRE is not compiled with PCRE_UCP support
784    .sp
785    The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
786    be used if the limits were changed when PCRE was built.
787  .  .
788  .  .
789  .SH "STUDYING A PATTERN"  .SH "STUDYING A PATTERN"
# Line 688  help speed up matching, \fBpcre_study()\ Line 802  help speed up matching, \fBpcre_study()\
802  results of the study.  results of the study.
803  .P  .P
804  The returned value from \fBpcre_study()\fP can be passed directly to  The returned value from \fBpcre_study()\fP can be passed directly to
805  \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
806  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
807  described  passed; these are described
808  .\" HTML <a href="#extradata">  .\" HTML <a href="#extradata">
809  .\" </a>  .\" </a>
810  below  below
811  .\"  .\"
812  in the section on matching a pattern.  in the section on matching a pattern.
813  .P  .P
814  If studying the pattern does not produce any additional information  If studying the pattern does not produce any useful information,
815  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program
816  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
817  own \fBpcre_extra\fP block.  \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block.
818  .P  .P
819  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
820  options are defined, and this argument should always be zero.  options are defined, and this argument should always be zero.
# Line 720  This is a typical call to \fBpcre_study\ Line 834  This is a typical call to \fBpcre_study\
834      0,              /* no options exist */      0,              /* no options exist */
835      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
836  .sp  .sp
837  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
838  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
839  bytes is created.  mean that there are any strings of that length that match, but it does
840    guarantee that no shorter strings match. The value is used by
841    \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP to avoid wasting time by trying to
842    match strings that are shorter than the lower bound. You can find out the value
843    in a calling program via the \fBpcre_fullinfo()\fP function.
844    .P
845    Studying a pattern is also useful for non-anchored patterns that do not have a
846    single fixed starting character. A bitmap of possible starting bytes is
847    created. This speeds up finding a position in the subject at which to start
848    matching.
849  .  .
850  .  .
851  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
# Line 732  bytes is created. Line 855  bytes is created.
855  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters,
856  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
857  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
858  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
859  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
860  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
861  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
862  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
863    handling characters with codes greater than 128, you should either use UTF-8
864    and Unicode, or use locales, but not try to mix the two.
865  .P  .P
866  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
867  of \fBpcre_compile()\fP is NULL. These are sufficient for many applications.  of \fBpcre_compile()\fP is NULL. These are sufficient for many applications.
868  Normally, the internal tables recognize only ASCII characters. However, when  Normally, the internal tables recognize only ASCII characters. However, when
869  PCRE is built, it is possible to cause the internal tables to be rebuilt in the  PCRE is built, it is possible to cause the internal tables to be rebuilt in the
870  default "C" locale of the local system, which may cause them to be different.  default "C" locale of the local system, which may cause them to be different.
871  .P  .P
# Line 760  the following code could be used: Line 885  the following code could be used:
885    tables = pcre_maketables();    tables = pcre_maketables();
886    re = pcre_compile(..., tables);    re = pcre_compile(..., tables);
887  .sp  .sp
888  The locale name "fr_FR" is used on Linux and other Unix-like systems; if you  The locale name "fr_FR" is used on Linux and other Unix-like systems; if you
889  are using Windows, the name for the French locale is "french".  are using Windows, the name for the French locale is "french".
890  .P  .P
891  When \fBpcre_maketables()\fP runs, the tables are built in memory that is  When \fBpcre_maketables()\fP runs, the tables are built in memory that is
# Line 865  table indicating a fixed set of bytes fo Line 990  table indicating a fixed set of bytes fo
990  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
991  fourth argument should point to an \fBunsigned char *\fP variable.  fourth argument should point to an \fBunsigned char *\fP variable.
992  .sp  .sp
993      PCRE_INFO_HASCRORLF
994    .sp
995    Return 1 if the pattern contains any explicit matches for CR or LF characters,
996    otherwise 0. The fourth argument should point to an \fBint\fP variable. An
997    explicit match is either a literal CR or LF character, or \er or \en.
998    .sp
999      PCRE_INFO_JCHANGED
1000    .sp
1001    Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise
1002    0. The fourth argument should point to an \fBint\fP variable. (?J) and
1003    (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
1004    .sp
1005    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
1006  .sp  .sp
1007  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 875  follows something of variable length. Fo Line 1012  follows something of variable length. Fo
1012  /^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
1013  is -1.  is -1.
1014  .sp  .sp
1015      PCRE_INFO_MINLENGTH
1016    .sp
1017    If the pattern was studied and a minimum length for matching subject strings
1018    was computed, its value is returned. Otherwise the returned value is -1. The
1019    value is a number of characters, not bytes (this may be relevant in UTF-8
1020    mode). The fourth argument should point to an \fBint\fP variable. A
1021    non-negative value is a lower bound to the length of any matching string. There
1022    may not be any strings of that length that do actually match, but every string
1023    that does match is at least that long.
1024    .sp
1025    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
1026    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
1027    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
# Line 895  entry; both of these return an \fBint\fP Line 1042  entry; both of these return an \fBint\fP
1042  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
1043  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
1044  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
1045  rest of the entry is the corresponding name, zero terminated. The names are in  rest of the entry is the corresponding name, zero terminated.
1046  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of  .P
1047  their parentheses numbers. For example, consider the following pattern (assume  The names are in alphabetical order. Duplicate names may appear if (?| is used
1048  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  to create multiple groups with the same number, as described in the
1049    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1050    .\" </a>
1051    section on duplicate subpattern numbers
1052    .\"
1053    in the
1054    .\" HREF
1055    \fBpcrepattern\fP
1056    .\"
1057    page. Duplicate names for subpatterns with different numbers are permitted only
1058    if PCRE_DUPNAMES is set. In all cases of duplicate names, they appear in the
1059    table in the order in which they were found in the pattern. In the absence of
1060    (?| this is the order of increasing number; when (?| is used this is not
1061    necessarily the case because later subpatterns may have lower numbers.
1062    .P
1063    As a simple example of the name/number table, consider the following pattern
1064    (assume PCRE_EXTENDED is set, so white space - including newlines - is
1065    ignored):
1066  .sp  .sp
1067  .\" JOIN  .\" JOIN
1068    (?<date> (?<year>(\ed\ed)?\ed\ed) -    (?<date> (?<year>(\ed\ed)?\ed\ed) -
# Line 917  When writing code to extract data from n Line 1081  When writing code to extract data from n
1081  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
1082  different for each compiled pattern.  different for each compiled pattern.
1083  .sp  .sp
1084      PCRE_INFO_OKPARTIAL
1085    .sp
1086    Return 1 if the pattern can be used for partial matching with
1087    \fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
1088    \fBint\fP variable. From release 8.00, this always returns 1, because the
1089    restrictions that previously applied to partial matching have been lifted. The
1090    .\" HREF
1091    \fBpcrepartial\fP
1092    .\"
1093    documentation gives details of partial matching.
1094    .sp
1095    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1096  .sp  .sp
1097  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
1098  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
1099  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
1100  top-level option settings within the pattern itself.  top-level option settings at the start of the pattern itself. In other words,
1101    they are the options that will be in force when matching starts. For example,
1102    if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED option, the
1103    result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED.
1104  .P  .P
1105  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
1106  alternatives begin with one of the following:  alternatives begin with one of the following:
# Line 949  variable. Line 1127  variable.
1127  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
1128  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
1129  \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
1130  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
1131    study data, zero is returned. The fourth argument should point to a
1132  \fBsize_t\fP variable.  \fBsize_t\fP variable.
1133  .  .
1134  .  .
# Line 1011  is different. (This seems a highly unlik Line 1190  is different. (This seems a highly unlik
1190  .P  .P
1191  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
1192  compiled pattern, which is passed in the \fIcode\fP argument. If the  compiled pattern, which is passed in the \fIcode\fP argument. If the
1193  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
1194  \fIextra\fP argument. This function is the main matching facility of the  \fIextra\fP argument. This function is the main matching facility of the
1195  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
1196  also an alternative matching function, which is described  also an alternative matching function, which is described
# Line 1061  fields (not necessarily in this order): Line 1240  fields (not necessarily in this order):
1240    unsigned long int \fImatch_limit_recursion\fP;    unsigned long int \fImatch_limit_recursion\fP;
1241    void *\fIcallout_data\fP;    void *\fIcallout_data\fP;
1242    const unsigned char *\fItables\fP;    const unsigned char *\fItables\fP;
1243      unsigned char **\fImark\fP;
1244  .sp  .sp
1245  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
1246  are set. The flag bits are:  are set. The flag bits are:
# Line 1070  are set. The flag bits are: Line 1250  are set. The flag bits are:
1250    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1251    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1252    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1253      PCRE_EXTRA_MARK
1254  .sp  .sp
1255  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
1256  \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 1079  the block by setting the other fields an Line 1260  the block by setting the other fields an
1260  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
1261  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,
1262  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
1263  classic example is the use of nested unlimited repeats.  classic example is a pattern that uses nested unlimited repeats.
1264  .P  .P
1265  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly
1266  (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 1112  with a \fBpcre_extra\fP block in which \ Line 1293  with a \fBpcre_extra\fP block in which \
1293  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
1294  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1295  .P  .P
1296  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,
1297  which is described in the  and is described in the
1298  .\" HREF  .\" HREF
1299  \fBpcrecallout\fP  \fBpcrecallout\fP
1300  .\"  .\"
# Line 1132  called. See the Line 1313  called. See the
1313  \fBpcreprecompile\fP  \fBpcreprecompile\fP
1314  .\"  .\"
1315  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1316    .P
1317    If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1318    be set to point to a \fBchar *\fP variable. If the pattern contains any
1319    backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1320    a name to pass back, a pointer to the name string (zero terminated) is placed
1321    in the variable pointed to by the \fImark\fP field. The names are within the
1322    compiled pattern; if you wish to retain such a name you must copy it before
1323    freeing the memory of a compiled pattern. If there is no name to pass back, the
1324    variable pointed to by the \fImark\fP field set to NULL. For details of the
1325    backtracking control verbs, see the section entitled
1326    .\" HTML <a href="pcrepattern#backtrackcontrol">
1327    .\" </a>
1328    "Backtracking control"
1329    .\"
1330    in the
1331    .\" HREF
1332    \fBpcrepattern\fP
1333    .\"
1334    documentation.
1335    .
1336  .  .
1337    .\" HTML <a name="execoptions"></a>
1338  .SS "Option bits for \fBpcre_exec()\fP"  .SS "Option bits for \fBpcre_exec()\fP"
1339  .rs  .rs
1340  .sp  .sp
1341  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
1342  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,
1343  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1344    PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
1345    PCRE_PARTIAL_HARD.
1346  .sp  .sp
1347    PCRE_ANCHORED    PCRE_ANCHORED
1348  .sp  .sp
# Line 1147  matching position. If a pattern was comp Line 1351  matching position. If a pattern was comp
1351  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
1352  matching time.  matching time.
1353  .sp  .sp
1354      PCRE_BSR_ANYCRLF
1355      PCRE_BSR_UNICODE
1356    .sp
1357    These options (which are mutually exclusive) control what the \eR escape
1358    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
1359    match any Unicode newline sequence. These options override the choice that was
1360    made or defaulted when the pattern was compiled.
1361    .sp
1362    PCRE_NEWLINE_CR    PCRE_NEWLINE_CR
1363    PCRE_NEWLINE_LF    PCRE_NEWLINE_LF
1364    PCRE_NEWLINE_CRLF    PCRE_NEWLINE_CRLF
1365      PCRE_NEWLINE_ANYCRLF
1366    PCRE_NEWLINE_ANY    PCRE_NEWLINE_ANY
1367  .sp  .sp
1368  These options override the newline definition that was chosen or defaulted when  These options override the newline definition that was chosen or defaulted when
# Line 1157  the pattern was compiled. For details, s Line 1370  the pattern was compiled. For details, s
1370  \fBpcre_compile()\fP above. During matching, the newline choice affects the  \fBpcre_compile()\fP above. During matching, the newline choice affects the
1371  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1372  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
1373  pattern. When PCRE_NEWLINE_CRLF or PCRE_NEWLINE_ANY is set, and a match attempt  pattern.
1374  fails when the current position is at a CRLF sequence, the match position is  .P
1375  advanced by two characters instead of one, in other words, to after the CRLF.  When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a
1376    match attempt for an unanchored pattern fails when the current position is at a
1377    CRLF sequence, and the pattern contains no explicit matches for CR or LF
1378    characters, the match position is advanced by two characters instead of one, in
1379    other words, to after the CRLF.
1380    .P
1381    The above rule is a compromise that makes the most common cases work as
1382    expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
1383    set), it does not match the string "\er\enA" because, after failing at the
1384    start, it skips both the CR and the LF before retrying. However, the pattern
1385    [\er\en]A does match that string, because it contains an explicit CR or LF
1386    reference, and so advances only by one character after the first failure.
1387    .P
1388    An explicit match for CR of LF is either a literal appearance of one of those
1389    characters, or one of the \er or \en escape sequences. Implicit matches such as
1390    [^X] do not count, nor does \es (which includes CR and LF in the characters
1391    that it matches).
1392    .P
1393    Notwithstanding the above, anomalous effects may still occur when CRLF is a
1394    valid newline sequence and explicit \er or \en escapes appear in the pattern.
1395  .sp  .sp
1396    PCRE_NOTBOL    PCRE_NOTBOL
1397  .sp  .sp
# Line 1185  match the empty string, the entire match Line 1417  match the empty string, the entire match
1417  .sp  .sp
1418    a?b?    a?b?
1419  .sp  .sp
1420  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
1421  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
1422  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".
1423  .P  .sp
1424  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case    PCRE_NOTEMPTY_ATSTART
1425  of a pattern match of the empty string within its \fBsplit()\fP function, and  .sp
1426  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
1427  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
1428  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the  can occur only if the pattern contains \eK.
1429  starting offset (see below) and trying an ordinary match again. There is some  .P
1430  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
1431    does make a special case of a pattern match of the empty string within its
1432    \fBsplit()\fP function, and when using the /g modifier. It is possible to
1433    emulate Perl's behaviour after matching a null string by first trying the match
1434    again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
1435    if that fails, by advancing the starting offset (see below) and trying an
1436    ordinary match again. There is some code that demonstrates how to do this in
1437    the
1438    .\" HREF
1439    \fBpcredemo\fP
1440    .\"
1441    sample program.
1442    .sp
1443      PCRE_NO_START_OPTIMIZE
1444    .sp
1445    There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1446    a match, in order to speed up the process. For example, if it is known that a
1447    match must start with a specific character, it searches the subject for that
1448    character, and fails immediately if it cannot find it, without actually running
1449    the main matching function. When callouts are in use, these optimizations can
1450    cause them to be skipped. This option disables the "start-up" optimizations,
1451    causing performance to suffer, but ensuring that the callouts do occur.
1452  .sp  .sp
1453    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1454  .sp  .sp
1455  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
1456  string is automatically checked when \fBpcre_exec()\fP is subsequently called.  string is automatically checked when \fBpcre_exec()\fP is subsequently called.
1457  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
1458  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
1459  \fBpcre_exec()\fP returns the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP  strings in the
1460  contains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.  .\" HTML <a href="pcre.html#utf8strings">
1461    .\" </a>
1462    section on UTF-8 support
1463    .\"
1464    in the main
1465    .\" HREF
1466    \fBpcre\fP
1467    .\"
1468    page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns
1469    the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP contains an invalid value,
1470    PCRE_ERROR_BADUTF8_OFFSET is returned.
1471  .P  .P
1472  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
1473  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
# Line 1216  PCRE_NO_UTF8_CHECK is set, the effect of Line 1479  PCRE_NO_UTF8_CHECK is set, the effect of
1479  subject, or a value of \fIstartoffset\fP that does not point to the start of a  subject, or a value of \fIstartoffset\fP that does not point to the start of a
1480  UTF-8 character, is undefined. Your program may crash.  UTF-8 character, is undefined. Your program may crash.
1481  .sp  .sp
1482    PCRE_PARTIAL    PCRE_PARTIAL_HARD
1483      PCRE_PARTIAL_SOFT
1484  .sp  .sp
1485  This option turns on the partial matching feature. If the subject string fails  These options turn on the partial matching feature. For backwards
1486  to match the pattern, but at some point during the matching process the end of  compatibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial match
1487  the subject was reached (that is, the subject partially matches the pattern and  occurs if the end of the subject string is reached successfully, but there are
1488  the failure to match occurred only because there were not enough subject  not enough subject characters to complete the match. If this happens when
1489  characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of  PCRE_PARTIAL_HARD is set, \fBpcre_exec()\fP immediately returns
1490  PCRE_ERROR_NOMATCH. When PCRE_PARTIAL is used, there are restrictions on what  PCRE_ERROR_PARTIAL. Otherwise, if PCRE_PARTIAL_SOFT is set, matching continues
1491  may appear in the pattern. These are discussed in the  by testing any other alternatives. Only if they all fail is PCRE_ERROR_PARTIAL
1492    returned (instead of PCRE_ERROR_NOMATCH). The portion of the string that
1493    was inspected when the partial match was found is set as the first matching
1494    string. There is a more detailed discussion in the
1495  .\" HREF  .\" HREF
1496  \fBpcrepartial\fP  \fBpcrepartial\fP
1497  .\"  .\"
# Line 1234  documentation. Line 1501  documentation.
1501  .rs  .rs
1502  .sp  .sp
1503  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
1504  \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
1505  \fIstartoffset\fP. In UTF-8 mode, the byte offset must point to the start of a  in \fIstartoffset\fP. In UTF-8 mode, the byte offset must point to the start of
1506  UTF-8 character. Unlike the pattern string, the subject may contain binary zero  a UTF-8 character. Unlike the pattern string, the subject may contain binary
1507  bytes. When the starting offset is zero, the search for a match starts at the  zero bytes. When the starting offset is zero, the search for a match starts at
1508  beginning of the subject, and this is by far the most common case.  the beginning of the subject, and this is by far the most common case.
1509  .P  .P
1510  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
1511  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 1272  pattern. Following the usage in Jeffrey Line 1539  pattern. Following the usage in Jeffrey
1539  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
1540  kinds of parenthesized subpattern that do not cause substrings to be captured.  kinds of parenthesized subpattern that do not cause substrings to be captured.
1541  .P  .P
1542  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
1543  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
1544  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
1545  this argument is NOT the size of \fIovector\fP in bytes.  argument is NOT the size of \fIovector\fP in bytes.
1546  .P  .P
1547  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,
1548  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
1549  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
1550  and is not available for passing back information. The length passed in  and is not available for passing back information. The number passed in
1551  \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
1552  rounded down.  rounded down.
1553  .P  .P
1554  When a match is successful, information about captured substrings is returned  When a match is successful, information about captured substrings is returned
1555  in pairs of integers, starting at the beginning of \fIovector\fP, and  in pairs of integers, starting at the beginning of \fIovector\fP, and
1556  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
1557  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
1558  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
1559  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
1560  subject string matched by the entire pattern. The next pair is used for the  mode. They are not character counts.
1561  first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fP  .P
1562  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
1563  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
1564  capturing subpatterns, the return value from a successful match is 1,  used for the first capturing subpattern, and so on. The value returned by
1565  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.
1566    For example, if two substrings have been captured, the returned value is 3. If
1567    there are no capturing subpatterns, the return value from a successful match is
1568    1, indicating that just the first pair of offsets has been set.
1569  .P  .P
1570  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
1571  string that it matched that is returned.  string that it matched that is returned.
1572  .P  .P
1573  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
1574  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
1575  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,
1576  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
1577  \fIovecsize\fP as zero. However, if the pattern contains back references and  \fIovecsize\fP as zero. However, if the pattern contains back references and
1578  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
1579  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
1580  advisable to supply an \fIovector\fP.  advisable to supply an \fIovector\fP.
1581  .P  .P
1582  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
1583  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1584  \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
1585  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 1414  documentation for details of partial mat Line 1684  documentation for details of partial mat
1684  .sp  .sp
1685    PCRE_ERROR_BADPARTIAL     (-13)    PCRE_ERROR_BADPARTIAL     (-13)
1686  .sp  .sp
1687  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
1688  are not supported for partial matching. See the  option was used with a compiled pattern containing items that were not
1689  .\" HREF  supported for partial matching. From release 8.00 onwards, there are no
1690  \fBpcrepartial\fP  restrictions on partial matching.
 .\"  
 documentation for details of partial matching.  
1691  .sp  .sp
1692    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
1693  .sp  .sp
# Line 1436  The internal recursion limit, as specifi Line 1704  The internal recursion limit, as specifi
1704  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
1705  description above.  description above.
1706  .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  
1707    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
1708  .sp  .sp
1709  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
1710  .P  .P
1711  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.
1712  .  .
1713  .  .
1714  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
# Line 1597  These functions call \fBpcre_get_stringn Line 1857  These functions call \fBpcre_get_stringn
1857  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
1858  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,
1859  the behaviour may not be what you want (see the next section).  the behaviour may not be what you want (see the next section).
1860  .  .P
1861    \fBWarning:\fP If the pattern uses the (?| feature to set up multiple
1862    subpatterns with the same number, as described in the
1863    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1864    .\" </a>
1865    section on duplicate subpattern numbers
1866    .\"
1867    in the
1868    .\" HREF
1869    \fBpcrepattern\fP
1870    .\"
1871    page, you cannot use names to distinguish the different subpatterns, because
1872    names are not included in the compiled code. The matching process uses only
1873    numbers. For this reason, the use of different names for subpatterns of the
1874    same number causes an error at compile time.
1875  .  .
1876  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
1877  .rs  .rs
# Line 1607  the behaviour may not be what you want ( Line 1881  the behaviour may not be what you want (
1881  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
1882  .PP  .PP
1883  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
1884  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
1885  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
1886  example is shown in the  such subpatterns are named, they are required to use the same names.)
1887    .P
1888    Normally, patterns with duplicate names are such that in any one match, only
1889    one of the named subpatterns participates. An example is shown in the
1890  .\" HREF  .\" HREF
1891  \fBpcrepattern\fP  \fBpcrepattern\fP
1892  .\"  .\"
1893  documentation. When duplicates are present, \fBpcre_copy_named_substring()\fP  documentation.
1894  and \fBpcre_get_named_substring()\fP return the first substring corresponding  .P
1895  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
1896  The \fBpcre_get_stringnumber()\fP function returns one of the numbers that are  \fBpcre_get_named_substring()\fP return the first substring corresponding to
1897  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
1898  .sp  returned; no data is returned. The \fBpcre_get_stringnumber()\fP function
1899    returns one of the numbers that are associated with the name, but it is not
1900    defined which it is.
1901    .P
1902  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,
1903  you must use the \fBpcre_get_stringtable_entries()\fP function. The first  you must use the \fBpcre_get_stringtable_entries()\fP function. The first
1904  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 1670  a compiled pattern, using a matching alg Line 1950  a compiled pattern, using a matching alg
1950  just once, and does not backtrack. This has different characteristics to the  just once, and does not backtrack. This has different characteristics to the
1951  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
1952  patterns are not supported. Nevertheless, there are times when this kind of  patterns are not supported. Nevertheless, there are times when this kind of
1953  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
1954  the  list of features that \fBpcre_dfa_exec()\fP does not support, see the
1955  .\" HREF  .\" HREF
1956  \fBpcrematching\fP  \fBpcrematching\fP
1957  .\"  .\"
# Line 1710  Here is an example of a simple call to \ Line 1990  Here is an example of a simple call to \
1990  .sp  .sp
1991  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
1992  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,
1993  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1994  PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last three of these are  PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST,
1995  the same as for \fBpcre_exec()\fP, so their description is not repeated here.  and PCRE_DFA_RESTART. All but the last four of these are exactly the same as
1996  .sp  for \fBpcre_exec()\fP, so their description is not repeated here.
1997    PCRE_PARTIAL  .sp
1998  .sp    PCRE_PARTIAL_HARD
1999  This has the same general effect as it does for \fBpcre_exec()\fP, but the    PCRE_PARTIAL_SOFT
2000  details are slightly different. When PCRE_PARTIAL is set for  .sp
2001  \fBpcre_dfa_exec()\fP, the return code PCRE_ERROR_NOMATCH is converted into  These have the same general effect as they do for \fBpcre_exec()\fP, but the
2002  PCRE_ERROR_PARTIAL if the end of the subject is reached, there have been no  details are slightly different. When PCRE_PARTIAL_HARD is set for
2003  complete matches, but there is still at least one matching possibility. The  \fBpcre_dfa_exec()\fP, it returns PCRE_ERROR_PARTIAL if the end of the subject
2004  portion of the string that provided the partial match is set as the first  is reached and there is still at least one matching possibility that requires
2005  matching string.  additional characters. This happens even if some complete matches have also
2006    been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
2007    is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
2008    there have been no complete matches, but there is still at least one matching
2009    possibility. The portion of the string that was inspected when the longest
2010    partial match was found is set as the first matching string in both cases.
2011  .sp  .sp
2012    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
2013  .sp  .sp
# Line 1733  matching point in the subject string. Line 2018  matching point in the subject string.
2018  .sp  .sp
2019    PCRE_DFA_RESTART    PCRE_DFA_RESTART
2020  .sp  .sp
2021  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
2022  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
2023  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
2024  option requests this action; when it is set, the \fIworkspace\fP and  \fIworkspace\fP and \fIwscount\fP options must reference the same vector as
2025  \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
2026  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  
2027  .\" HREF  .\" HREF
2028  \fBpcrepartial\fP  \fBpcrepartial\fP
2029  .\"  .\"
# Line 1843  Cambridge CB2 3QH, England. Line 2127  Cambridge CB2 3QH, England.
2127  .rs  .rs
2128  .sp  .sp
2129  .nf  .nf
2130  Last updated: 06 March 2007  Last updated: 26 May 2010
2131  Copyright (c) 1997-2007 University of Cambridge.  Copyright (c) 1997-2010 University of Cambridge.
2132  .fi  .fi

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