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revision 226 by ph10, Tue Aug 21 11:46:08 2007 UTC revision 454 by ph10, Tue Sep 22 09:42:11 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 218  points during a matching operation. Deta Line 223  points during a matching operation. Deta
223  documentation.  documentation.
224  .  .
225  .  .
226    .\" HTML <a name="newlines"></a>
227  .SH NEWLINES  .SH NEWLINES
228  .rs  .rs
229  .sp  .sp
# Line 235  The default default is LF, which is the Line 241  The default default is LF, which is the
241  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
242  matched.  matched.
243  .P  .P
244    At compile time, the newline convention can be specified by the \fIoptions\fP
245    argument of \fBpcre_compile()\fP, or it can be specified by special text at the
246    start of the pattern itself; this overrides any other settings. See the
247    .\" HREF
248    \fBpcrepattern\fP
249    .\"
250    page for details of the special character sequences.
251    .P
252  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
253  pair of characters that indicate a line break". The choice of newline  pair of characters that indicate a line break". The choice of newline
254  convention affects the handling of the dot, circumflex, and dollar  convention affects the handling of the dot, circumflex, and dollar
# Line 245  non-anchored pattern. There is more deta Line 259  non-anchored pattern. There is more deta
259  .\" </a>  .\" </a>
260  section on \fBpcre_exec()\fP options  section on \fBpcre_exec()\fP options
261  .\"  .\"
262  below. The choice of newline convention does not affect the interpretation of  below.
263  the \en or \er escape sequences.  .P
264    The choice of newline convention does not affect the interpretation of
265    the \en or \er escape sequences, nor does it affect what \eR matches, which is
266    controlled in a similar way, but by separate options.
267  .  .
268  .  .
269  .SH MULTITHREADING  .SH MULTITHREADING
# Line 305  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
330      PCRE_CONFIG_BSR
331    .sp
332    The output is an integer whose value indicates what character sequences the \eR
333    escape sequence matches by default. A value of 0 means that \eR matches any
334    Unicode line ending sequence; a value of 1 means that \eR matches only CR, LF,
335    or CRLF. The default can be overridden when a pattern is compiled or matched.
336  .sp  .sp
337    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
338  .sp  .sp
# Line 328  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 385  argument, which is an address (see below Line 411  argument, which is an address (see below
411  .P  .P
412  The \fIoptions\fP argument contains various bit settings that affect the  The \fIoptions\fP argument contains various bit settings that affect the
413  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
414  options are described below. Some of them, in particular, those that are  options are described below. Some of them (in particular, those that are
415  compatible with Perl, can also be set and unset from within the pattern (see  compatible with Perl, but also some others) can also be set and unset from
416  the detailed description in the  within the pattern (see the detailed description in the
417  .\" HREF  .\" HREF
418  \fBpcrepattern\fP  \fBpcrepattern\fP
419  .\"  .\"
420  documentation). For these options, the contents of the \fIoptions\fP argument  documentation). For those options that can be different in different parts of
421  specifies their initial settings at the start of compilation and execution. The  the pattern, the contents of the \fIoptions\fP argument specifies their initial
422  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 and
423  matching as well as at compile time.  PCRE_NEWLINE_\fIxxx\fP options can be set at the time of matching as well as at
424    compile time.
425  .P  .P
426  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
427  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
428  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
429  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
430  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
431  where the error was discovered is placed in the variable pointed to by  character that was being processes when the error was discovered is placed in
432  \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,
433    an immediate error is given. Some errors are not detected until checks are
434    carried out when the whole pattern has been scanned; in this case the offset is
435    set to the end of the pattern.
436  .P  .P
437  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
438  \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 449  facility, see the Line 479  facility, see the
479  .\"  .\"
480  documentation.  documentation.
481  .sp  .sp
482      PCRE_BSR_ANYCRLF
483      PCRE_BSR_UNICODE
484    .sp
485    These options (which are mutually exclusive) control what the \eR escape
486    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
487    match any Unicode newline sequence. The default is specified when PCRE is
488    built. It can be overridden from within the pattern, or by setting an option
489    when a compiled pattern is matched.
490    .sp
491    PCRE_CASELESS    PCRE_CASELESS
492  .sp  .sp
493  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 521  If this option is set, an unanchored pat Line 560  If this option is set, an unanchored pat
560  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
561  over the newline.  over the newline.
562  .sp  .sp
563      PCRE_JAVASCRIPT_COMPAT
564    .sp
565    If this option is set, PCRE's behaviour is changed in some ways so that it is
566    compatible with JavaScript rather than Perl. The changes are as follows:
567    .P
568    (1) A lone closing square bracket in a pattern causes a compile-time error,
569    because this is illegal in JavaScript (by default it is treated as a data
570    character). Thus, the pattern AB]CD becomes illegal when this option is set.
571    .P
572    (2) At run time, a back reference to an unset subpattern group matches an empty
573    string (by default this causes the current matching alternative to fail). A
574    pattern such as (\e1)(a) succeeds when this option is set (assuming it can find
575    an "a" in the subject), whereas it fails by default, for Perl compatibility.
576    .sp
577    PCRE_MULTILINE    PCRE_MULTILINE
578  .sp  .sp
579  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 644  out of use. To avoid confusion, they hav Line 697  out of use. To avoid confusion, they hav
697     9  nothing to repeat     9  nothing to repeat
698    10  [this code is not in use]    10  [this code is not in use]
699    11  internal error: unexpected repeat    11  internal error: unexpected repeat
700    12  unrecognized character after (?    12  unrecognized character after (? or (?-
701    13  POSIX named classes are supported only within a class    13  POSIX named classes are supported only within a class
702    14  missing )    14  missing )
703    15  reference to non-existent subpattern    15  reference to non-existent subpattern
# Line 652  out of use. To avoid confusion, they hav Line 705  out of use. To avoid confusion, they hav
705    17  unknown option bit(s) set    17  unknown option bit(s) set
706    18  missing ) after comment    18  missing ) after comment
707    19  [this code is not in use]    19  [this code is not in use]
708    20  regular expression too large    20  regular expression is too large
709    21  failed to get memory    21  failed to get memory
710    22  unmatched parentheses    22  unmatched parentheses
711    23  internal error: code overflow    23  internal error: code overflow
# Line 681  out of use. To avoid confusion, they hav Line 734  out of use. To avoid confusion, they hav
734    46  malformed \eP or \ep sequence    46  malformed \eP or \ep sequence
735    47  unknown property name after \eP or \ep    47  unknown property name after \eP or \ep
736    48  subpattern name is too long (maximum 32 characters)    48  subpattern name is too long (maximum 32 characters)
737    49  too many named subpatterns (maximum 10,000)    49  too many named subpatterns (maximum 10000)
738    50  [this code is not in use]    50  [this code is not in use]
739    51  octal value is greater than \e377 (not in UTF-8 mode)    51  octal value is greater than \e377 (not in UTF-8 mode)
740    52  internal error: overran compiling workspace    52  internal error: overran compiling workspace
741    53  internal error: previously-checked referenced subpattern not found    53  internal error: previously-checked referenced subpattern not found
742    54  DEFINE group contains more than one branch    54  DEFINE group contains more than one branch
743    55  repeating a DEFINE group is not allowed    55  repeating a DEFINE group is not allowed
744    56  inconsistent NEWLINE options"    56  inconsistent NEWLINE options
745    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
746          non-zero number          name/number or by a plain number
747    58  (?+ or (?- or (?(+ or (?(- must be followed by a non-zero number    58  a numbered reference must not be zero
748      59  (*VERB) with an argument is not supported
749      60  (*VERB) not recognized
750      61  number is too big
751      62  subpattern name expected
752      63  digit expected after (?+
753      64  ] is an invalid data character in JavaScript compatibility mode
754    .sp
755    The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
756    be used if the limits were changed when PCRE was built.
757  .  .
758  .  .
759  .SH "STUDYING A PATTERN"  .SH "STUDYING A PATTERN"
# Line 889  fourth argument should point to an \fBun Line 951  fourth argument should point to an \fBun
951  .sp  .sp
952    PCRE_INFO_HASCRORLF    PCRE_INFO_HASCRORLF
953  .sp  .sp
954  Return 1 if the pattern contains any explicit matches for CR or LF characters,  Return 1 if the pattern contains any explicit matches for CR or LF characters,
955  otherwise 0. The fourth argument should point to an \fBint\fP variable.  otherwise 0. The fourth argument should point to an \fBint\fP variable. An
956    explicit match is either a literal CR or LF character, or \er or \en.
957  .sp  .sp
958    PCRE_INFO_JCHANGED    PCRE_INFO_JCHANGED
959  .sp  .sp
960  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
961  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
962  setting changes the local PCRE_DUPNAMES option.  (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
963  .sp  .sp
964    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
965  .sp  .sp
# Line 952  different for each compiled pattern. Line 1015  different for each compiled pattern.
1015  .sp  .sp
1016    PCRE_INFO_OKPARTIAL    PCRE_INFO_OKPARTIAL
1017  .sp  .sp
1018  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
1019  fourth argument should point to an \fBint\fP variable. The  \fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
1020    \fBint\fP variable. From release 8.00, this always returns 1, because the
1021    restrictions that previously applied to partial matching have been lifted. The
1022  .\" HREF  .\" HREF
1023  \fBpcrepartial\fP  \fBpcrepartial\fP
1024  .\"  .\"
1025  documentation lists the restrictions that apply to patterns when partial  documentation gives details of partial matching.
 matching is used.  
1026  .sp  .sp
1027    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1028  .sp  .sp
# Line 1158  with a \fBpcre_extra\fP block in which \ Line 1222  with a \fBpcre_extra\fP block in which \
1222  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
1223  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1224  .P  .P
1225  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,
1226  which is described in the  and is described in the
1227  .\" HREF  .\" HREF
1228  \fBpcrecallout\fP  \fBpcrecallout\fP
1229  .\"  .\"
# Line 1185  documentation for a discussion of saving Line 1249  documentation for a discussion of saving
1249  .sp  .sp
1250  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
1251  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,
1252  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1253    PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
1254    PCRE_PARTIAL_HARD.
1255  .sp  .sp
1256    PCRE_ANCHORED    PCRE_ANCHORED
1257  .sp  .sp
# Line 1194  matching position. If a pattern was comp Line 1260  matching position. If a pattern was comp
1260  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
1261  matching time.  matching time.
1262  .sp  .sp
1263      PCRE_BSR_ANYCRLF
1264      PCRE_BSR_UNICODE
1265    .sp
1266    These options (which are mutually exclusive) control what the \eR escape
1267    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
1268    match any Unicode newline sequence. These options override the choice that was
1269    made or defaulted when the pattern was compiled.
1270    .sp
1271    PCRE_NEWLINE_CR    PCRE_NEWLINE_CR
1272    PCRE_NEWLINE_LF    PCRE_NEWLINE_LF
1273    PCRE_NEWLINE_CRLF    PCRE_NEWLINE_CRLF
# Line 1205  the pattern was compiled. For details, s Line 1279  the pattern was compiled. For details, s
1279  \fBpcre_compile()\fP above. During matching, the newline choice affects the  \fBpcre_compile()\fP above. During matching, the newline choice affects the
1280  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1281  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
1282  pattern.  pattern.
1283  .P  .P
1284  When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a  When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a
1285  match attempt for an unanchored pattern fails when the current position is at a  match attempt for an unanchored pattern fails when the current position is at a
1286  CRLF sequence, and the pattern contains no explicit matches for CR or NL  CRLF sequence, and the pattern contains no explicit matches for CR or LF
1287  characters, the match position is advanced by two characters instead of one, in  characters, the match position is advanced by two characters instead of one, in
1288  other words, to after the CRLF.  other words, to after the CRLF.
1289  .P  .P
1290  The above rule is a compromise that makes the most common cases work as  The above rule is a compromise that makes the most common cases work as
1291  expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not  expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
1292  set), it does not match the string "\er\enA" because, after failing at the  set), it does not match the string "\er\enA" because, after failing at the
1293  start, it skips both the CR and the LF before retrying. However, the pattern  start, it skips both the CR and the LF before retrying. However, the pattern
1294  [\er\en]A does match that string, because it contains an explicit CR or LF  [\er\en]A does match that string, because it contains an explicit CR or LF
1295  reference, and so advances only by one character after the first failure.  reference, and so advances only by one character after the first failure.
1296  Note than an explicit CR or LF reference occurs for negated character classes  .P
1297  such as [^X] because they can match CR or LF characters.  An explicit match for CR of LF is either a literal appearance of one of those
1298    characters, or one of the \er or \en escape sequences. Implicit matches such as
1299    [^X] do not count, nor does \es (which includes CR and LF in the characters
1300    that it matches).
1301  .P  .P
1302  Notwithstanding the above, anomalous effects may still occur when CRLF is a  Notwithstanding the above, anomalous effects may still occur when CRLF is a
1303  valid newline sequence and explicit \er or \en escapes appear in the pattern.  valid newline sequence and explicit \er or \en escapes appear in the pattern.
# Line 1249  match the empty string, the entire match Line 1326  match the empty string, the entire match
1326  .sp  .sp
1327    a?b?    a?b?
1328  .sp  .sp
1329  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
1330  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
1331  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".
1332  .P  .sp
1333  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case    PCRE_NOTEMPTY_ATSTART
1334  of a pattern match of the empty string within its \fBsplit()\fP function, and  .sp
1335  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
1336  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
1337  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the  can occur only if the pattern contains \eK.
1338  starting offset (see below) and trying an ordinary match again. There is some  .P
1339  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
1340    does make a special case of a pattern match of the empty string within its
1341    \fBsplit()\fP function, and when using the /g modifier. It is possible to
1342    emulate Perl's behaviour after matching a null string by first trying the match
1343    again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
1344    if that fails, by advancing the starting offset (see below) and trying an
1345    ordinary match again. There is some code that demonstrates how to do this in
1346    the
1347    .\" HREF
1348    \fBpcredemo\fP
1349    .\"
1350    sample program.
1351    .sp
1352      PCRE_NO_START_OPTIMIZE
1353    .sp
1354    There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1355    a match, in order to speed up the process. For example, if it is known that a
1356    match must start with a specific character, it searches the subject for that
1357    character, and fails immediately if it cannot find it, without actually running
1358    the main matching function. When callouts are in use, these optimizations can
1359    cause them to be skipped. This option disables the "start-up" optimizations,
1360    causing performance to suffer, but ensuring that the callouts do occur.
1361  .sp  .sp
1362    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1363  .sp  .sp
# Line 1290  PCRE_NO_UTF8_CHECK is set, the effect of Line 1388  PCRE_NO_UTF8_CHECK is set, the effect of
1388  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
1389  UTF-8 character, is undefined. Your program may crash.  UTF-8 character, is undefined. Your program may crash.
1390  .sp  .sp
1391    PCRE_PARTIAL    PCRE_PARTIAL_HARD
1392      PCRE_PARTIAL_SOFT
1393  .sp  .sp
1394  This option turns on the partial matching feature. If the subject string fails  These options turn on the partial matching feature. For backwards
1395  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
1396  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
1397  the failure to match occurred only because there were not enough subject  not enough subject characters to complete the match. If this happens when
1398  characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of  PCRE_PARTIAL_HARD is set, \fBpcre_exec()\fP immediately returns
1399  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
1400  may appear in the pattern. These are discussed in the  by testing any other alternatives. Only if they all fail is PCRE_ERROR_PARTIAL
1401    returned (instead of PCRE_ERROR_NOMATCH). The portion of the string that
1402    was inspected when the partial match was found is set as the first matching
1403    string. There is a more detailed discussion in the
1404  .\" HREF  .\" HREF
1405  \fBpcrepartial\fP  \fBpcrepartial\fP
1406  .\"  .\"
# Line 1308  documentation. Line 1410  documentation.
1410  .rs  .rs
1411  .sp  .sp
1412  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
1413  \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
1414  \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
1415  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
1416  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
1417  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.
1418  .P  .P
1419  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
1420  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 1346  pattern. Following the usage in Jeffrey Line 1448  pattern. Following the usage in Jeffrey
1448  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
1449  kinds of parenthesized subpattern that do not cause substrings to be captured.  kinds of parenthesized subpattern that do not cause substrings to be captured.
1450  .P  .P
1451  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
1452  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
1453  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
1454  this argument is NOT the size of \fIovector\fP in bytes.  argument is NOT the size of \fIovector\fP in bytes.
1455  .P  .P
1456  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,
1457  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
1458  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
1459  and is not available for passing back information. The length passed in  and is not available for passing back information. The number passed in
1460  \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
1461  rounded down.  rounded down.
1462  .P  .P
1463  When a match is successful, information about captured substrings is returned  When a match is successful, information about captured substrings is returned
1464  in pairs of integers, starting at the beginning of \fIovector\fP, and  in pairs of integers, starting at the beginning of \fIovector\fP, and
1465  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
1466  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
1467  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
1468  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
1469  subject string matched by the entire pattern. The next pair is used for the  mode. They are not character counts.
1470  first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fP  .P
1471  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
1472  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
1473  capturing subpatterns, the return value from a successful match is 1,  used for the first capturing subpattern, and so on. The value returned by
1474  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.
1475    For example, if two substrings have been captured, the returned value is 3. If
1476    there are no capturing subpatterns, the return value from a successful match is
1477    1, indicating that just the first pair of offsets has been set.
1478  .P  .P
1479  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
1480  string that it matched that is returned.  string that it matched that is returned.
1481  .P  .P
1482  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
1483  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
1484  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,
1485  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
1486  \fIovecsize\fP as zero. However, if the pattern contains back references and  \fIovecsize\fP as zero. However, if the pattern contains back references and
1487  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
1488  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
# Line 1488  documentation for details of partial mat Line 1593  documentation for details of partial mat
1593  .sp  .sp
1594    PCRE_ERROR_BADPARTIAL     (-13)    PCRE_ERROR_BADPARTIAL     (-13)
1595  .sp  .sp
1596  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
1597  are not supported for partial matching. See the  option was used with a compiled pattern containing items that were not
1598  .\" HREF  supported for partial matching. From release 8.00 onwards, there are no
1599  \fBpcrepartial\fP  restrictions on partial matching.
 .\"  
 documentation for details of partial matching.  
1600  .sp  .sp
1601    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
1602  .sp  .sp
# Line 1663  These functions call \fBpcre_get_stringn Line 1766  These functions call \fBpcre_get_stringn
1766  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
1767  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,
1768  the behaviour may not be what you want (see the next section).  the behaviour may not be what you want (see the next section).
1769  .  .P
1770    \fBWarning:\fP If the pattern uses the "(?|" feature to set up multiple
1771    subpatterns with the same number, you cannot use names to distinguish them,
1772    because names are not included in the compiled code. The matching process uses
1773    only numbers.
1774  .  .
1775  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
1776  .rs  .rs
# Line 1739  a compiled pattern, using a matching alg Line 1846  a compiled pattern, using a matching alg
1846  just once, and does not backtrack. This has different characteristics to the  just once, and does not backtrack. This has different characteristics to the
1847  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
1848  patterns are not supported. Nevertheless, there are times when this kind of  patterns are not supported. Nevertheless, there are times when this kind of
1849  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
1850  the  list of features that \fBpcre_dfa_exec()\fP does not support, see the
1851  .\" HREF  .\" HREF
1852  \fBpcrematching\fP  \fBpcrematching\fP
1853  .\"  .\"
# Line 1779  Here is an example of a simple call to \ Line 1886  Here is an example of a simple call to \
1886  .sp  .sp
1887  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
1888  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,
1889  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1890  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,
1891  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
1892  .sp  for \fBpcre_exec()\fP, so their description is not repeated here.
1893    PCRE_PARTIAL  .sp
1894  .sp    PCRE_PARTIAL_HARD
1895  This has the same general effect as it does for \fBpcre_exec()\fP, but the    PCRE_PARTIAL_SOFT
1896  details are slightly different. When PCRE_PARTIAL is set for  .sp
1897  \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
1898  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
1899  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
1900  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
1901  matching string.  additional characters. This happens even if some complete matches have also
1902    been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
1903    is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
1904    there have been no complete matches, but there is still at least one matching
1905    possibility. The portion of the string that was inspected when the longest
1906    partial match was found is set as the first matching string in both cases.
1907  .sp  .sp
1908    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
1909  .sp  .sp
# Line 1802  matching point in the subject string. Line 1914  matching point in the subject string.
1914  .sp  .sp
1915    PCRE_DFA_RESTART    PCRE_DFA_RESTART
1916  .sp  .sp
1917  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
1918  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
1919  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
1920  option requests this action; when it is set, the \fIworkspace\fP and  \fIworkspace\fP and \fIwscount\fP options must reference the same vector as
1921  \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
1922  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  
1923  .\" HREF  .\" HREF
1924  \fBpcrepartial\fP  \fBpcrepartial\fP
1925  .\"  .\"
# Line 1912  Cambridge CB2 3QH, England. Line 2023  Cambridge CB2 3QH, England.
2023  .rs  .rs
2024  .sp  .sp
2025  .nf  .nf
2026  Last updated: 21 August 2007  Last updated: 22 September 2009
2027  Copyright (c) 1997-2007 University of Cambridge.  Copyright (c) 1997-2009 University of Cambridge.
2028  .fi  .fi

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