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revision 243 by ph10, Thu Sep 13 09:28:14 2007 UTC revision 456 by ph10, Fri Oct 2 08:53:31 2009 UTC
# Line 135  Applications can use these to include su Line 135  Applications can use these to include su
135  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,
136  and \fBpcre_exec()\fP are used for compiling and matching regular expressions  and \fBpcre_exec()\fP are used for compiling and matching regular expressions
137  in a Perl-compatible manner. A sample program that demonstrates the simplest  in a Perl-compatible manner. A sample program that demonstrates the simplest
138  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
139  distribution. The  source distribution. A listing of this program is given in the
140    .\" HREF
141    \fBpcredemo\fP
142    .\"
143    documentation, and the
144  .\" HREF  .\" HREF
145  \fBpcresample\fP  \fBpcresample\fP
146  .\"  .\"
147  documentation describes how to run it.  documentation describes how to compile and run it.
148  .P  .P
149  A second matching function, \fBpcre_dfa_exec()\fP, which is not  A second matching function, \fBpcre_dfa_exec()\fP, which is not
150  Perl-compatible, is also provided. This uses a different algorithm for the  Perl-compatible, is also provided. This uses a different algorithm for the
151  matching. The alternative algorithm finds all possible matches (at a given  matching. The alternative algorithm finds all possible matches (at a given
152  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
153  does not return captured substrings. A description of the two matching  lookbehind assertions). However, this algorithm does not return captured
154  algorithms and their advantages and disadvantages is given in the  substrings. A description of the two matching algorithms and their advantages
155    and disadvantages is given in the
156  .\" HREF  .\" HREF
157  \fBpcrematching\fP  \fBpcrematching\fP
158  .\"  .\"
# Line 317  properties is available; otherwise it is Line 322  properties is available; otherwise it is
322  .sp  .sp
323  The output is an integer whose value specifies the default character sequence  The output is an integer whose value specifies the default character sequence
324  that is recognized as meaning "newline". The four values that are supported  that is recognized as meaning "newline". The four values that are supported
325  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.
326  default should normally be the standard sequence for your operating system.  Though they are derived from ASCII, the same values are returned in EBCDIC
327    environments. The default should normally correspond to the standard sequence
328    for your operating system.
329  .sp  .sp
330    PCRE_CONFIG_BSR    PCRE_CONFIG_BSR
331  .sp  .sp
# Line 347  documentation. Line 354  documentation.
354  .sp  .sp
355    PCRE_CONFIG_MATCH_LIMIT    PCRE_CONFIG_MATCH_LIMIT
356  .sp  .sp
357  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
358  internal matching function calls in a \fBpcre_exec()\fP execution. Further  internal matching function calls in a \fBpcre_exec()\fP execution. Further
359  details are given with \fBpcre_exec()\fP below.  details are given with \fBpcre_exec()\fP below.
360  .sp  .sp
361    PCRE_CONFIG_MATCH_LIMIT_RECURSION    PCRE_CONFIG_MATCH_LIMIT_RECURSION
362  .sp  .sp
363  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
364  recursion when calling the internal matching function in a \fBpcre_exec()\fP  recursion when calling the internal matching function in a \fBpcre_exec()\fP
365  execution. Further details are given with \fBpcre_exec()\fP below.  execution. Further details are given with \fBpcre_exec()\fP below.
366  .sp  .sp
# Line 388  avoiding the use of the stack. Line 395  avoiding the use of the stack.
395  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
396  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
397  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,
398  \fIerrorcodeptr\fP, via which a numerical error code can be returned.  \fIerrorcodeptr\fP, via which a numerical error code can be returned. To avoid
399    too much repetition, we refer just to \fBpcre_compile()\fP below, but the
400    information applies equally to \fBpcre_compile2()\fP.
401  .P  .P
402  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
403  \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 404  argument, which is an address (see below Line 413  argument, which is an address (see below
413  .P  .P
414  The \fIoptions\fP argument contains various bit settings that affect the  The \fIoptions\fP argument contains various bit settings that affect the
415  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
416  options are described below. Some of them, in particular, those that are  options are described below. Some of them (in particular, those that are
417  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
418  the detailed description in the  within the pattern (see the detailed description in the
419  .\" HREF  .\" HREF
420  \fBpcrepattern\fP  \fBpcrepattern\fP
421  .\"  .\"
422  documentation). For these options, the contents of the \fIoptions\fP argument  documentation). For those options that can be different in different parts of
423  specifies their initial settings at the start of compilation and execution. The  the pattern, the contents of the \fIoptions\fP argument specifies their
424  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,
425  matching as well as at compile time.  PCRE_BSR_\fIxxx\fP, and PCRE_NEWLINE_\fIxxx\fP options can be set at the time
426    of matching as well as at compile time.
427  .P  .P
428  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
429  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
430  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
431  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
432  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
433  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
434  \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,
435    an immediate error is given. Some errors are not detected until checks are
436    carried out when the whole pattern has been scanned; in this case the offset is
437    set to the end of the pattern.
438  .P  .P
439  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
440  \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 549  If this option is set, an unanchored pat Line 562  If this option is set, an unanchored pat
562  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
563  over the newline.  over the newline.
564  .sp  .sp
565      PCRE_JAVASCRIPT_COMPAT
566    .sp
567    If this option is set, PCRE's behaviour is changed in some ways so that it is
568    compatible with JavaScript rather than Perl. The changes are as follows:
569    .P
570    (1) A lone closing square bracket in a pattern causes a compile-time error,
571    because this is illegal in JavaScript (by default it is treated as a data
572    character). Thus, the pattern AB]CD becomes illegal when this option is set.
573    .P
574    (2) At run time, a back reference to an unset subpattern group matches an empty
575    string (by default this causes the current matching alternative to fail). A
576    pattern such as (\e1)(a) succeeds when this option is set (assuming it can find
577    an "a" in the subject), whereas it fails by default, for Perl compatibility.
578    .sp
579    PCRE_MULTILINE    PCRE_MULTILINE
580  .sp  .sp
581  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 672  out of use. To avoid confusion, they hav Line 699  out of use. To avoid confusion, they hav
699     9  nothing to repeat     9  nothing to repeat
700    10  [this code is not in use]    10  [this code is not in use]
701    11  internal error: unexpected repeat    11  internal error: unexpected repeat
702    12  unrecognized character after (?    12  unrecognized character after (? or (?-
703    13  POSIX named classes are supported only within a class    13  POSIX named classes are supported only within a class
704    14  missing )    14  missing )
705    15  reference to non-existent subpattern    15  reference to non-existent subpattern
# Line 680  out of use. To avoid confusion, they hav Line 707  out of use. To avoid confusion, they hav
707    17  unknown option bit(s) set    17  unknown option bit(s) set
708    18  missing ) after comment    18  missing ) after comment
709    19  [this code is not in use]    19  [this code is not in use]
710    20  regular expression too large    20  regular expression is too large
711    21  failed to get memory    21  failed to get memory
712    22  unmatched parentheses    22  unmatched parentheses
713    23  internal error: code overflow    23  internal error: code overflow
# Line 709  out of use. To avoid confusion, they hav Line 736  out of use. To avoid confusion, they hav
736    46  malformed \eP or \ep sequence    46  malformed \eP or \ep sequence
737    47  unknown property name after \eP or \ep    47  unknown property name after \eP or \ep
738    48  subpattern name is too long (maximum 32 characters)    48  subpattern name is too long (maximum 32 characters)
739    49  too many named subpatterns (maximum 10,000)    49  too many named subpatterns (maximum 10000)
740    50  [this code is not in use]    50  [this code is not in use]
741    51  octal value is greater than \e377 (not in UTF-8 mode)    51  octal value is greater than \e377 (not in UTF-8 mode)
742    52  internal error: overran compiling workspace    52  internal error: overran compiling workspace
# Line 717  out of use. To avoid confusion, they hav Line 744  out of use. To avoid confusion, they hav
744    54  DEFINE group contains more than one branch    54  DEFINE group contains more than one branch
745    55  repeating a DEFINE group is not allowed    55  repeating a DEFINE group is not allowed
746    56  inconsistent NEWLINE options    56  inconsistent NEWLINE options
747    57  \eg is not followed by a braced name or an optionally braced    57  \eg is not followed by a braced, angle-bracketed, or quoted
748          non-zero number          name/number or by a plain number
749    58  (?+ or (?- or (?(+ or (?(- must be followed by a non-zero number    58  a numbered reference must not be zero
750      59  (*VERB) with an argument is not supported
751      60  (*VERB) not recognized
752      61  number is too big
753      62  subpattern name expected
754      63  digit expected after (?+
755      64  ] is an invalid data character in JavaScript compatibility mode
756    .sp
757    The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
758    be used if the limits were changed when PCRE was built.
759  .  .
760  .  .
761  .SH "STUDYING A PATTERN"  .SH "STUDYING A PATTERN"
# Line 738  help speed up matching, \fBpcre_study()\ Line 774  help speed up matching, \fBpcre_study()\
774  results of the study.  results of the study.
775  .P  .P
776  The returned value from \fBpcre_study()\fP can be passed directly to  The returned value from \fBpcre_study()\fP can be passed directly to
777  \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
778  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
779  described  passed; these are described
780  .\" HTML <a href="#extradata">  .\" HTML <a href="#extradata">
781  .\" </a>  .\" </a>
782  below  below
783  .\"  .\"
784  in the section on matching a pattern.  in the section on matching a pattern.
785  .P  .P
786  If studying the pattern does not produce any additional information  If studying the pattern does not produce any useful information,
787  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program
788  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
789  own \fBpcre_extra\fP block.  \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block.
790  .P  .P
791  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
792  options are defined, and this argument should always be zero.  options are defined, and this argument should always be zero.
# Line 770  This is a typical call to \fBpcre_study\ Line 806  This is a typical call to \fBpcre_study\
806      0,              /* no options exist */      0,              /* no options exist */
807      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
808  .sp  .sp
809  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
810  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
811  bytes is created.  mean that there are any strings of that length that match, but it does
812    guarantee that no shorter strings match. The value is used by
813    \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP to avoid wasting time by trying to
814    match strings that are shorter than the lower bound. You can find out the value
815    in a calling program via the \fBpcre_fullinfo()\fP function.
816    .P
817    Studying a pattern is also useful for non-anchored patterns that do not have a
818    single fixed starting character. A bitmap of possible starting bytes is
819    created. This speeds up finding a position in the subject at which to start
820    matching.
821  .  .
822  .  .
823  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
# Line 923  explicit match is either a literal CR or Line 968  explicit match is either a literal CR or
968  .sp  .sp
969    PCRE_INFO_JCHANGED    PCRE_INFO_JCHANGED
970  .sp  .sp
971  Return 1 if the (?J) option setting is used in the pattern, otherwise 0. The  Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise
972  fourth argument should point to an \fBint\fP variable. The (?J) internal option  0. The fourth argument should point to an \fBint\fP variable. (?J) and
973  setting changes the local PCRE_DUPNAMES option.  (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
974  .sp  .sp
975    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
976  .sp  .sp
# Line 937  follows something of variable length. Fo Line 982  follows something of variable length. Fo
982  /^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
983  is -1.  is -1.
984  .sp  .sp
985      PCRE_INFO_MINLENGTH
986    .sp
987    If the pattern was studied and a minimum length for matching subject strings
988    was computed, its value is returned. Otherwise the returned value is -1. The
989    value is a number of characters, not bytes (this may be relevant in UTF-8
990    mode). The fourth argument should point to an \fBint\fP variable. A
991    non-negative value is a lower bound to the length of any matching string. There
992    may not be any strings of that length that do actually match, but every string
993    that does match is at least that long.
994    .sp
995    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
996    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
997    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
# Line 981  different for each compiled pattern. Line 1036  different for each compiled pattern.
1036  .sp  .sp
1037    PCRE_INFO_OKPARTIAL    PCRE_INFO_OKPARTIAL
1038  .sp  .sp
1039  Return 1 if the pattern can be used for partial matching, otherwise 0. The  Return 1 if the pattern can be used for partial matching with
1040  fourth argument should point to an \fBint\fP variable. The  \fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
1041    \fBint\fP variable. From release 8.00, this always returns 1, because the
1042    restrictions that previously applied to partial matching have been lifted. The
1043  .\" HREF  .\" HREF
1044  \fBpcrepartial\fP  \fBpcrepartial\fP
1045  .\"  .\"
1046  documentation lists the restrictions that apply to patterns when partial  documentation gives details of partial matching.
 matching is used.  
1047  .sp  .sp
1048    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1049  .sp  .sp
# Line 1024  variable. Line 1080  variable.
1080  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
1081  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
1082  \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
1083  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
1084    study data, zero is returned. The fourth argument should point to a
1085  \fBsize_t\fP variable.  \fBsize_t\fP variable.
1086  .  .
1087  .  .
# Line 1086  is different. (This seems a highly unlik Line 1143  is different. (This seems a highly unlik
1143  .P  .P
1144  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
1145  compiled pattern, which is passed in the \fIcode\fP argument. If the  compiled pattern, which is passed in the \fIcode\fP argument. If the
1146  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
1147  \fIextra\fP argument. This function is the main matching facility of the  \fIextra\fP argument. This function is the main matching facility of the
1148  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
1149  also an alternative matching function, which is described  also an alternative matching function, which is described
# Line 1154  the block by setting the other fields an Line 1211  the block by setting the other fields an
1211  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
1212  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,
1213  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
1214  classic example is the use of nested unlimited repeats.  classic example is a pattern that uses nested unlimited repeats.
1215  .P  .P
1216  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly
1217  (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 1187  with a \fBpcre_extra\fP block in which \ Line 1244  with a \fBpcre_extra\fP block in which \
1244  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
1245  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1246  .P  .P
1247  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,
1248  which is described in the  and is described in the
1249  .\" HREF  .\" HREF
1250  \fBpcrecallout\fP  \fBpcrecallout\fP
1251  .\"  .\"
# Line 1214  documentation for a discussion of saving Line 1271  documentation for a discussion of saving
1271  .sp  .sp
1272  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
1273  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,
1274  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1275    PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
1276    PCRE_PARTIAL_HARD.
1277  .sp  .sp
1278    PCRE_ANCHORED    PCRE_ANCHORED
1279  .sp  .sp
# Line 1289  match the empty string, the entire match Line 1348  match the empty string, the entire match
1348  .sp  .sp
1349    a?b?    a?b?
1350  .sp  .sp
1351  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
1352  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
1353  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".
1354  .P  .sp
1355  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case    PCRE_NOTEMPTY_ATSTART
1356  of a pattern match of the empty string within its \fBsplit()\fP function, and  .sp
1357  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
1358  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
1359  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the  can occur only if the pattern contains \eK.
1360  starting offset (see below) and trying an ordinary match again. There is some  .P
1361  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
1362    does make a special case of a pattern match of the empty string within its
1363    \fBsplit()\fP function, and when using the /g modifier. It is possible to
1364    emulate Perl's behaviour after matching a null string by first trying the match
1365    again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
1366    if that fails, by advancing the starting offset (see below) and trying an
1367    ordinary match again. There is some code that demonstrates how to do this in
1368    the
1369    .\" HREF
1370    \fBpcredemo\fP
1371    .\"
1372    sample program.
1373    .sp
1374      PCRE_NO_START_OPTIMIZE
1375    .sp
1376    There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1377    a match, in order to speed up the process. For example, if it is known that a
1378    match must start with a specific character, it searches the subject for that
1379    character, and fails immediately if it cannot find it, without actually running
1380    the main matching function. When callouts are in use, these optimizations can
1381    cause them to be skipped. This option disables the "start-up" optimizations,
1382    causing performance to suffer, but ensuring that the callouts do occur.
1383  .sp  .sp
1384    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1385  .sp  .sp
# Line 1330  PCRE_NO_UTF8_CHECK is set, the effect of Line 1410  PCRE_NO_UTF8_CHECK is set, the effect of
1410  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
1411  UTF-8 character, is undefined. Your program may crash.  UTF-8 character, is undefined. Your program may crash.
1412  .sp  .sp
1413    PCRE_PARTIAL    PCRE_PARTIAL_HARD
1414      PCRE_PARTIAL_SOFT
1415  .sp  .sp
1416  This option turns on the partial matching feature. If the subject string fails  These options turn on the partial matching feature. For backwards
1417  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
1418  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
1419  the failure to match occurred only because there were not enough subject  not enough subject characters to complete the match. If this happens when
1420  characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of  PCRE_PARTIAL_HARD is set, \fBpcre_exec()\fP immediately returns
1421  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
1422  may appear in the pattern. These are discussed in the  by testing any other alternatives. Only if they all fail is PCRE_ERROR_PARTIAL
1423    returned (instead of PCRE_ERROR_NOMATCH). The portion of the string that
1424    was inspected when the partial match was found is set as the first matching
1425    string. There is a more detailed discussion in the
1426  .\" HREF  .\" HREF
1427  \fBpcrepartial\fP  \fBpcrepartial\fP
1428  .\"  .\"
# Line 1348  documentation. Line 1432  documentation.
1432  .rs  .rs
1433  .sp  .sp
1434  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
1435  \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
1436  \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
1437  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
1438  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
1439  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.
1440  .P  .P
1441  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
1442  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 1386  pattern. Following the usage in Jeffrey Line 1470  pattern. Following the usage in Jeffrey
1470  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
1471  kinds of parenthesized subpattern that do not cause substrings to be captured.  kinds of parenthesized subpattern that do not cause substrings to be captured.
1472  .P  .P
1473  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
1474  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
1475  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
1476  this argument is NOT the size of \fIovector\fP in bytes.  argument is NOT the size of \fIovector\fP in bytes.
1477  .P  .P
1478  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,
1479  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
1480  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
1481  and is not available for passing back information. The length passed in  and is not available for passing back information. The number passed in
1482  \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
1483  rounded down.  rounded down.
1484  .P  .P
1485  When a match is successful, information about captured substrings is returned  When a match is successful, information about captured substrings is returned
1486  in pairs of integers, starting at the beginning of \fIovector\fP, and  in pairs of integers, starting at the beginning of \fIovector\fP, and
1487  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
1488  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
1489  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
1490  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
1491  subject string matched by the entire pattern. The next pair is used for the  mode. They are not character counts.
1492  first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fP  .P
1493  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
1494  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
1495  capturing subpatterns, the return value from a successful match is 1,  used for the first capturing subpattern, and so on. The value returned by
1496  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.
1497    For example, if two substrings have been captured, the returned value is 3. If
1498    there are no capturing subpatterns, the return value from a successful match is
1499    1, indicating that just the first pair of offsets has been set.
1500  .P  .P
1501  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
1502  string that it matched that is returned.  string that it matched that is returned.
1503  .P  .P
1504  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
1505  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
1506  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,
1507  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
1508  \fIovecsize\fP as zero. However, if the pattern contains back references and  \fIovecsize\fP as zero. However, if the pattern contains back references and
1509  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
1510  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
1511  advisable to supply an \fIovector\fP.  advisable to supply an \fIovector\fP.
1512  .P  .P
1513  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
1514  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1515  \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
1516  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 1528  documentation for details of partial mat Line 1615  documentation for details of partial mat
1615  .sp  .sp
1616    PCRE_ERROR_BADPARTIAL     (-13)    PCRE_ERROR_BADPARTIAL     (-13)
1617  .sp  .sp
1618  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
1619  are not supported for partial matching. See the  option was used with a compiled pattern containing items that were not
1620  .\" HREF  supported for partial matching. From release 8.00 onwards, there are no
1621  \fBpcrepartial\fP  restrictions on partial matching.
 .\"  
 documentation for details of partial matching.  
1622  .sp  .sp
1623    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
1624  .sp  .sp
# Line 1703  These functions call \fBpcre_get_stringn Line 1788  These functions call \fBpcre_get_stringn
1788  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
1789  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,
1790  the behaviour may not be what you want (see the next section).  the behaviour may not be what you want (see the next section).
1791  .  .P
1792    \fBWarning:\fP If the pattern uses the "(?|" feature to set up multiple
1793    subpatterns with the same number, you cannot use names to distinguish them,
1794    because names are not included in the compiled code. The matching process uses
1795    only numbers.
1796  .  .
1797  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
1798  .rs  .rs
# Line 1779  a compiled pattern, using a matching alg Line 1868  a compiled pattern, using a matching alg
1868  just once, and does not backtrack. This has different characteristics to the  just once, and does not backtrack. This has different characteristics to the
1869  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
1870  patterns are not supported. Nevertheless, there are times when this kind of  patterns are not supported. Nevertheless, there are times when this kind of
1871  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
1872  the  list of features that \fBpcre_dfa_exec()\fP does not support, see the
1873  .\" HREF  .\" HREF
1874  \fBpcrematching\fP  \fBpcrematching\fP
1875  .\"  .\"
# Line 1819  Here is an example of a simple call to \ Line 1908  Here is an example of a simple call to \
1908  .sp  .sp
1909  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
1910  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,
1911  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1912  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,
1913  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
1914  .sp  for \fBpcre_exec()\fP, so their description is not repeated here.
1915    PCRE_PARTIAL  .sp
1916  .sp    PCRE_PARTIAL_HARD
1917  This has the same general effect as it does for \fBpcre_exec()\fP, but the    PCRE_PARTIAL_SOFT
1918  details are slightly different. When PCRE_PARTIAL is set for  .sp
1919  \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
1920  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
1921  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
1922  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
1923  matching string.  additional characters. This happens even if some complete matches have also
1924    been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
1925    is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
1926    there have been no complete matches, but there is still at least one matching
1927    possibility. The portion of the string that was inspected when the longest
1928    partial match was found is set as the first matching string in both cases.
1929  .sp  .sp
1930    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
1931  .sp  .sp
# Line 1842  matching point in the subject string. Line 1936  matching point in the subject string.
1936  .sp  .sp
1937    PCRE_DFA_RESTART    PCRE_DFA_RESTART
1938  .sp  .sp
1939  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
1940  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
1941  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
1942  option requests this action; when it is set, the \fIworkspace\fP and  \fIworkspace\fP and \fIwscount\fP options must reference the same vector as
1943  \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
1944  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  
1945  .\" HREF  .\" HREF
1946  \fBpcrepartial\fP  \fBpcrepartial\fP
1947  .\"  .\"
# Line 1952  Cambridge CB2 3QH, England. Line 2045  Cambridge CB2 3QH, England.
2045  .rs  .rs
2046  .sp  .sp
2047  .nf  .nf
2048  Last updated: 11 September 2007  Last updated: 29 September 2009
2049  Copyright (c) 1997-2007 University of Cambridge.  Copyright (c) 1997-2009 University of Cambridge.
2050  .fi  .fi

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