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revision 196 by ph10, Mon Jul 30 13:44:50 2007 UTC revision 429 by ph10, Tue Sep 1 16:10:16 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
# Line 218  points during a matching operation. Deta Line 222  points during a matching operation. Deta
222  documentation.  documentation.
223  .  .
224  .  .
225    .\" HTML <a name="newlines"></a>
226  .SH NEWLINES  .SH NEWLINES
227  .rs  .rs
228  .sp  .sp
# Line 235  The default default is LF, which is the Line 240  The default default is LF, which is the
240  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
241  matched.  matched.
242  .P  .P
243    At compile time, the newline convention can be specified by the \fIoptions\fP
244    argument of \fBpcre_compile()\fP, or it can be specified by special text at the
245    start of the pattern itself; this overrides any other settings. See the
246    .\" HREF
247    \fBpcrepattern\fP
248    .\"
249    page for details of the special character sequences.
250    .P
251  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
252  pair of characters that indicate a line break". The choice of newline  pair of characters that indicate a line break". The choice of newline
253  convention affects the handling of the dot, circumflex, and dollar  convention affects the handling of the dot, circumflex, and dollar
254  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
255  recognized line ending sequence, the match position advancement for a  recognized line ending sequence, the match position advancement for a
256  non-anchored pattern. The choice of newline convention does not affect the  non-anchored pattern. There is more detail about this in the
257  interpretation of the \en or \er escape sequences.  .\" HTML <a href="#execoptions">
258    .\" </a>
259    section on \fBpcre_exec()\fP options
260    .\"
261    below.
262    .P
263    The choice of newline convention does not affect the interpretation of
264    the \en or \er escape sequences, nor does it affect what \eR matches, which is
265    controlled in a similar way, but by separate options.
266  .  .
267  .  .
268  .SH MULTITHREADING  .SH MULTITHREADING
# Line 300  properties is available; otherwise it is Line 321  properties is available; otherwise it is
321  .sp  .sp
322  The output is an integer whose value specifies the default character sequence  The output is an integer whose value specifies the default character sequence
323  that is recognized as meaning "newline". The four values that are supported  that is recognized as meaning "newline". The four values that are supported
324  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.
325  default should normally be the standard sequence for your operating system.  Though they are derived from ASCII, the same values are returned in EBCDIC
326    environments. The default should normally correspond to the standard sequence
327    for your operating system.
328    .sp
329      PCRE_CONFIG_BSR
330    .sp
331    The output is an integer whose value indicates what character sequences the \eR
332    escape sequence matches by default. A value of 0 means that \eR matches any
333    Unicode line ending sequence; a value of 1 means that \eR matches only CR, LF,
334    or CRLF. The default can be overridden when a pattern is compiled or matched.
335  .sp  .sp
336    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
337  .sp  .sp
# Line 323  documentation. Line 353  documentation.
353  .sp  .sp
354    PCRE_CONFIG_MATCH_LIMIT    PCRE_CONFIG_MATCH_LIMIT
355  .sp  .sp
356  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
357  internal matching function calls in a \fBpcre_exec()\fP execution. Further  internal matching function calls in a \fBpcre_exec()\fP execution. Further
358  details are given with \fBpcre_exec()\fP below.  details are given with \fBpcre_exec()\fP below.
359  .sp  .sp
360    PCRE_CONFIG_MATCH_LIMIT_RECURSION    PCRE_CONFIG_MATCH_LIMIT_RECURSION
361  .sp  .sp
362  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
363  recursion when calling the internal matching function in a \fBpcre_exec()\fP  recursion when calling the internal matching function in a \fBpcre_exec()\fP
364  execution. Further details are given with \fBpcre_exec()\fP below.  execution. Further details are given with \fBpcre_exec()\fP below.
365  .sp  .sp
# Line 380  argument, which is an address (see below Line 410  argument, which is an address (see below
410  .P  .P
411  The \fIoptions\fP argument contains various bit settings that affect the  The \fIoptions\fP argument contains various bit settings that affect the
412  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
413  options are described below. Some of them, in particular, those that are  options are described below. Some of them (in particular, those that are
414  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
415  the detailed description in the  within the pattern (see the detailed description in the
416  .\" HREF  .\" HREF
417  \fBpcrepattern\fP  \fBpcrepattern\fP
418  .\"  .\"
419  documentation). For these options, the contents of the \fIoptions\fP argument  documentation). For those options that can be different in different parts of
420  specifies their initial settings at the start of compilation and execution. The  the pattern, the contents of the \fIoptions\fP argument specifies their initial
421  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
422  matching as well as at compile time.  PCRE_NEWLINE_\fIxxx\fP options can be set at the time of matching as well as at
423    compile time.
424  .P  .P
425  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
426  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
# Line 444  facility, see the Line 475  facility, see the
475  .\"  .\"
476  documentation.  documentation.
477  .sp  .sp
478      PCRE_BSR_ANYCRLF
479      PCRE_BSR_UNICODE
480    .sp
481    These options (which are mutually exclusive) control what the \eR escape
482    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
483    match any Unicode newline sequence. The default is specified when PCRE is
484    built. It can be overridden from within the pattern, or by setting an option
485    when a compiled pattern is matched.
486    .sp
487    PCRE_CASELESS    PCRE_CASELESS
488  .sp  .sp
489  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 516  If this option is set, an unanchored pat Line 556  If this option is set, an unanchored pat
556  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
557  over the newline.  over the newline.
558  .sp  .sp
559      PCRE_JAVASCRIPT_COMPAT
560    .sp
561    If this option is set, PCRE's behaviour is changed in some ways so that it is
562    compatible with JavaScript rather than Perl. The changes are as follows:
563    .P
564    (1) A lone closing square bracket in a pattern causes a compile-time error,
565    because this is illegal in JavaScript (by default it is treated as a data
566    character). Thus, the pattern AB]CD becomes illegal when this option is set.
567    .P
568    (2) At run time, a back reference to an unset subpattern group matches an empty
569    string (by default this causes the current matching alternative to fail). A
570    pattern such as (\e1)(a) succeeds when this option is set (assuming it can find
571    an "a" in the subject), whereas it fails by default, for Perl compatibility.
572    .sp
573    PCRE_MULTILINE    PCRE_MULTILINE
574  .sp  .sp
575  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 601  page. Line 655  page.
655    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
656  .sp  .sp
657  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
658  automatically checked. If an invalid UTF-8 sequence of bytes is found,  automatically checked. There is a discussion about the
659  \fBpcre_compile()\fP returns an error. If you already know that your pattern is  .\" HTML <a href="pcre.html#utf8strings">
660  valid, and you want to skip this check for performance reasons, you can set the  .\" </a>
661  PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid  validity of UTF-8 strings
662  UTF-8 string as a pattern is undefined. It may cause your program to crash.  .\"
663  Note that this option can also be passed to \fBpcre_exec()\fP and  in the main
664  \fBpcre_dfa_exec()\fP, to suppress the UTF-8 validity checking of subject  .\" HREF
665  strings.  \fBpcre\fP
666    .\"
667    page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_compile()\fP
668    returns an error. If you already know that your pattern is valid, and you want
669    to skip this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK
670    option. When it is set, the effect of passing an invalid UTF-8 string as a
671    pattern is undefined. It may cause your program to crash. Note that this option
672    can also be passed to \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, to suppress
673    the UTF-8 validity checking of subject strings.
674  .  .
675  .  .
676  .SH "COMPILATION ERROR CODES"  .SH "COMPILATION ERROR CODES"
# Line 631  out of use. To avoid confusion, they hav Line 693  out of use. To avoid confusion, they hav
693     9  nothing to repeat     9  nothing to repeat
694    10  [this code is not in use]    10  [this code is not in use]
695    11  internal error: unexpected repeat    11  internal error: unexpected repeat
696    12  unrecognized character after (?    12  unrecognized character after (? or (?-
697    13  POSIX named classes are supported only within a class    13  POSIX named classes are supported only within a class
698    14  missing )    14  missing )
699    15  reference to non-existent subpattern    15  reference to non-existent subpattern
# Line 639  out of use. To avoid confusion, they hav Line 701  out of use. To avoid confusion, they hav
701    17  unknown option bit(s) set    17  unknown option bit(s) set
702    18  missing ) after comment    18  missing ) after comment
703    19  [this code is not in use]    19  [this code is not in use]
704    20  regular expression too large    20  regular expression is too large
705    21  failed to get memory    21  failed to get memory
706    22  unmatched parentheses    22  unmatched parentheses
707    23  internal error: code overflow    23  internal error: code overflow
# Line 668  out of use. To avoid confusion, they hav Line 730  out of use. To avoid confusion, they hav
730    46  malformed \eP or \ep sequence    46  malformed \eP or \ep sequence
731    47  unknown property name after \eP or \ep    47  unknown property name after \eP or \ep
732    48  subpattern name is too long (maximum 32 characters)    48  subpattern name is too long (maximum 32 characters)
733    49  too many named subpatterns (maximum 10,000)    49  too many named subpatterns (maximum 10000)
734    50  repeated subpattern is too long    50  [this code is not in use]
735    51  octal value is greater than \e377 (not in UTF-8 mode)    51  octal value is greater than \e377 (not in UTF-8 mode)
736    52  internal error: overran compiling workspace    52  internal error: overran compiling workspace
737    53  internal error: previously-checked referenced subpattern not found    53  internal error: previously-checked referenced subpattern not found
738    54  DEFINE group contains more than one branch    54  DEFINE group contains more than one branch
739    55  repeating a DEFINE group is not allowed    55  repeating a DEFINE group is not allowed
740    56  inconsistent NEWLINE options"    56  inconsistent NEWLINE options
741    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
742          non-zero number          name/number or by a plain number
743    58  (?+ or (?- or (?(+ or (?(- must be followed by a non-zero number    58  a numbered reference must not be zero
744      59  (*VERB) with an argument is not supported
745      60  (*VERB) not recognized
746      61  number is too big
747      62  subpattern name expected
748      63  digit expected after (?+
749      64  ] is an invalid data character in JavaScript compatibility mode
750    .sp
751    The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
752    be used if the limits were changed when PCRE was built.
753  .  .
754  .  .
755  .SH "STUDYING A PATTERN"  .SH "STUDYING A PATTERN"
# Line 874  table indicating a fixed set of bytes fo Line 945  table indicating a fixed set of bytes fo
945  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
946  fourth argument should point to an \fBunsigned char *\fP variable.  fourth argument should point to an \fBunsigned char *\fP variable.
947  .sp  .sp
948      PCRE_INFO_HASCRORLF
949    .sp
950    Return 1 if the pattern contains any explicit matches for CR or LF characters,
951    otherwise 0. The fourth argument should point to an \fBint\fP variable. An
952    explicit match is either a literal CR or LF character, or \er or \en.
953    .sp
954    PCRE_INFO_JCHANGED    PCRE_INFO_JCHANGED
955  .sp  .sp
956  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
957  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
958  setting changes the local PCRE_DUPNAMES option.  (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
959  .sp  .sp
960    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
961  .sp  .sp
# Line 935  different for each compiled pattern. Line 1012  different for each compiled pattern.
1012    PCRE_INFO_OKPARTIAL    PCRE_INFO_OKPARTIAL
1013  .sp  .sp
1014  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, otherwise 0. The
1015  fourth argument should point to an \fBint\fP variable. The  fourth argument should point to an \fBint\fP variable. From release 8.00, this
1016    always returns 1, because the restrictions that previously applied to partial
1017    matching have been lifted. The
1018  .\" HREF  .\" HREF
1019  \fBpcrepartial\fP  \fBpcrepartial\fP
1020  .\"  .\"
1021  documentation lists the restrictions that apply to patterns when partial  documentation gives details of partial matching.
 matching is used.  
1022  .sp  .sp
1023    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1024  .sp  .sp
# Line 1161  called. See the Line 1239  called. See the
1239  .\"  .\"
1240  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1241  .  .
1242    .\" HTML <a name="execoptions"></a>
1243  .SS "Option bits for \fBpcre_exec()\fP"  .SS "Option bits for \fBpcre_exec()\fP"
1244  .rs  .rs
1245  .sp  .sp
1246  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
1247  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,
1248  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_START_OPTIMIZE,
1249    PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and PCRE_PARTIAL_HARD.
1250  .sp  .sp
1251    PCRE_ANCHORED    PCRE_ANCHORED
1252  .sp  .sp
# Line 1175  matching position. If a pattern was comp Line 1255  matching position. If a pattern was comp
1255  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
1256  matching time.  matching time.
1257  .sp  .sp
1258      PCRE_BSR_ANYCRLF
1259      PCRE_BSR_UNICODE
1260    .sp
1261    These options (which are mutually exclusive) control what the \eR escape
1262    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
1263    match any Unicode newline sequence. These options override the choice that was
1264    made or defaulted when the pattern was compiled.
1265    .sp
1266    PCRE_NEWLINE_CR    PCRE_NEWLINE_CR
1267    PCRE_NEWLINE_LF    PCRE_NEWLINE_LF
1268    PCRE_NEWLINE_CRLF    PCRE_NEWLINE_CRLF
# Line 1186  the pattern was compiled. For details, s Line 1274  the pattern was compiled. For details, s
1274  \fBpcre_compile()\fP above. During matching, the newline choice affects the  \fBpcre_compile()\fP above. During matching, the newline choice affects the
1275  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1276  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
1277  pattern. When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is  pattern.
1278  set, and a match attempt fails when the current position is at a CRLF sequence,  .P
1279  the match position is advanced by two characters instead of one, in other  When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a
1280  words, to after the CRLF.  match attempt for an unanchored pattern fails when the current position is at a
1281    CRLF sequence, and the pattern contains no explicit matches for CR or LF
1282    characters, the match position is advanced by two characters instead of one, in
1283    other words, to after the CRLF.
1284    .P
1285    The above rule is a compromise that makes the most common cases work as
1286    expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
1287    set), it does not match the string "\er\enA" because, after failing at the
1288    start, it skips both the CR and the LF before retrying. However, the pattern
1289    [\er\en]A does match that string, because it contains an explicit CR or LF
1290    reference, and so advances only by one character after the first failure.
1291    .P
1292    An explicit match for CR of LF is either a literal appearance of one of those
1293    characters, or one of the \er or \en escape sequences. Implicit matches such as
1294    [^X] do not count, nor does \es (which includes CR and LF in the characters
1295    that it matches).
1296    .P
1297    Notwithstanding the above, anomalous effects may still occur when CRLF is a
1298    valid newline sequence and explicit \er or \en escapes appear in the pattern.
1299  .sp  .sp
1300    PCRE_NOTBOL    PCRE_NOTBOL
1301  .sp  .sp
# Line 1225  when using the /g modifier. It is possib Line 1331  when using the /g modifier. It is possib
1331  matching a null string by first trying the match again at the same offset with  matching a null string by first trying the match again at the same offset with
1332  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the
1333  starting offset (see below) and trying an ordinary match again. There is some  starting offset (see below) and trying an ordinary match again. There is some
1334  code that demonstrates how to do this in the \fIpcredemo.c\fP sample program.  code that demonstrates how to do this in the
1335    .\" HREF
1336    \fBpcredemo\fP
1337    .\"
1338    sample program.
1339    .sp
1340      PCRE_NO_START_OPTIMIZE
1341    .sp
1342    There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1343    a match, in order to speed up the process. For example, if it is known that a
1344    match must start with a specific character, it searches the subject for that
1345    character, and fails immediately if it cannot find it, without actually running
1346    the main matching function. When callouts are in use, these optimizations can
1347    cause them to be skipped. This option disables the "start-up" optimizations,
1348    causing performance to suffer, but ensuring that the callouts do occur.
1349  .sp  .sp
1350    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1351  .sp  .sp
1352  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
1353  string is automatically checked when \fBpcre_exec()\fP is subsequently called.  string is automatically checked when \fBpcre_exec()\fP is subsequently called.
1354  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
1355  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
1356  \fBpcre_exec()\fP returns the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP  strings in the
1357  contains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.  .\" HTML <a href="pcre.html#utf8strings">
1358    .\" </a>
1359    section on UTF-8 support
1360    .\"
1361    in the main
1362    .\" HREF
1363    \fBpcre\fP
1364    .\"
1365    page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns
1366    the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP contains an invalid value,
1367    PCRE_ERROR_BADUTF8_OFFSET is returned.
1368  .P  .P
1369  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
1370  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 1246  PCRE_NO_UTF8_CHECK is set, the effect of Line 1376  PCRE_NO_UTF8_CHECK is set, the effect of
1376  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
1377  UTF-8 character, is undefined. Your program may crash.  UTF-8 character, is undefined. Your program may crash.
1378  .sp  .sp
1379    PCRE_PARTIAL    PCRE_PARTIAL_HARD
1380      PCRE_PARTIAL_SOFT
1381  .sp  .sp
1382  This option turns on the partial matching feature. If the subject string fails  These options turn on the partial matching feature. For backwards
1383  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
1384  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
1385  the failure to match occurred only because there were not enough subject  not enough subject characters to complete the match. If this happens when
1386  characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of  PCRE_PARTIAL_HARD is set, \fBpcre_exec()\fP immediately returns
1387  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
1388  may appear in the pattern. These are discussed in the  by testing any other alternatives. Only if they all fail is PCRE_ERROR_PARTIAL
1389    returned (instead of PCRE_ERROR_NOMATCH). The portion of the string that
1390    provided the partial match is set as the first matching string. There is a more
1391    detailed discussion in the
1392  .\" HREF  .\" HREF
1393  \fBpcrepartial\fP  \fBpcrepartial\fP
1394  .\"  .\"
# Line 1264  documentation. Line 1398  documentation.
1398  .rs  .rs
1399  .sp  .sp
1400  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
1401  \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
1402  \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
1403  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
1404  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
1405  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.
1406  .P  .P
1407  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
1408  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 1302  pattern. Following the usage in Jeffrey Line 1436  pattern. Following the usage in Jeffrey
1436  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
1437  kinds of parenthesized subpattern that do not cause substrings to be captured.  kinds of parenthesized subpattern that do not cause substrings to be captured.
1438  .P  .P
1439  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
1440  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
1441  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
1442  this argument is NOT the size of \fIovector\fP in bytes.  argument is NOT the size of \fIovector\fP in bytes.
1443  .P  .P
1444  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,
1445  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
1446  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
1447  and is not available for passing back information. The length passed in  and is not available for passing back information. The number passed in
1448  \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
1449  rounded down.  rounded down.
1450  .P  .P
1451  When a match is successful, information about captured substrings is returned  When a match is successful, information about captured substrings is returned
1452  in pairs of integers, starting at the beginning of \fIovector\fP, and  in pairs of integers, starting at the beginning of \fIovector\fP, and
1453  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
1454  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
1455  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
1456  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
1457  subject string matched by the entire pattern. The next pair is used for the  mode. They are not character counts.
1458  first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fP  .P
1459  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
1460  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
1461  capturing subpatterns, the return value from a successful match is 1,  used for the first capturing subpattern, and so on. The value returned by
1462  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.
1463    For example, if two substrings have been captured, the returned value is 3. If
1464    there are no capturing subpatterns, the return value from a successful match is
1465    1, indicating that just the first pair of offsets has been set.
1466  .P  .P
1467  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
1468  string that it matched that is returned.  string that it matched that is returned.
1469  .P  .P
1470  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
1471  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
1472  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,
1473  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
1474  \fIovecsize\fP as zero. However, if the pattern contains back references and  \fIovecsize\fP as zero. However, if the pattern contains back references and
1475  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
1476  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 1444  documentation for details of partial mat Line 1581  documentation for details of partial mat
1581  .sp  .sp
1582    PCRE_ERROR_BADPARTIAL     (-13)    PCRE_ERROR_BADPARTIAL     (-13)
1583  .sp  .sp
1584  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
1585  are not supported for partial matching. See the  option was used with a compiled pattern containing items that were not
1586  .\" HREF  supported for partial matching. From release 8.00 onwards, there are no
1587  \fBpcrepartial\fP  restrictions on partial matching.
 .\"  
 documentation for details of partial matching.  
1588  .sp  .sp
1589    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
1590  .sp  .sp
# Line 1466  The internal recursion limit, as specifi Line 1601  The internal recursion limit, as specifi
1601  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
1602  description above.  description above.
1603  .sp  .sp
   PCRE_ERROR_NULLWSLIMIT    (-22)  
 .sp  
 When a parenthesized subpattern 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. The repetition loop is automatically terminated when  
 an empty string is matched.  
 .P  
 Some workspace is required for remembering the starting position. For most  
 capturing subpatterns, an internal recursive call of the match() function is  
 used, and in this case, the workspace is taken from the runtime stack. However,  
 for non-capturing subpatterns, this is not available. Instead, some fixed  
 workspace (taken from the top-level stack) is used. If it runs out, the  
 PCRE_ERROR_NULLWSLIMIT error is given. The size of the fixed workspace allows  
 for up to 1000 repetitions of a non-capturing subpattern that might match an  
 empty string. If this limit is a problem for you, you can sometimes get round  
 it by changing a non-capturing subpattern into a capturing one, but that will  
 increase the amount of runtime stack that is used.  
 .sp  
1604    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
1605  .sp  .sp
1606  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
1607  .P  .P
1608  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.
1609  .  .
1610  .  .
1611  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
# Line 1638  These functions call \fBpcre_get_stringn Line 1754  These functions call \fBpcre_get_stringn
1754  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
1755  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,
1756  the behaviour may not be what you want (see the next section).  the behaviour may not be what you want (see the next section).
1757  .  .P
1758    \fBWarning:\fP If the pattern uses the "(?|" feature to set up multiple
1759    subpatterns with the same number, you cannot use names to distinguish them,
1760    because names are not included in the compiled code. The matching process uses
1761    only numbers.
1762  .  .
1763  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
1764  .rs  .rs
# Line 1654  example is shown in the Line 1774  example is shown in the
1774  .\" HREF  .\" HREF
1775  \fBpcrepattern\fP  \fBpcrepattern\fP
1776  .\"  .\"
1777  documentation. When duplicates are present, \fBpcre_copy_named_substring()\fP  documentation.
1778  and \fBpcre_get_named_substring()\fP return the first substring corresponding  .P
1779  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
1780  The \fBpcre_get_stringnumber()\fP function returns one of the numbers that are  \fBpcre_get_named_substring()\fP return the first substring corresponding to
1781  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
1782  .sp  returned; no data is returned. The \fBpcre_get_stringnumber()\fP function
1783    returns one of the numbers that are associated with the name, but it is not
1784    defined which it is.
1785    .P
1786  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,
1787  you must use the \fBpcre_get_stringtable_entries()\fP function. The first  you must use the \fBpcre_get_stringtable_entries()\fP function. The first
1788  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 1751  Here is an example of a simple call to \ Line 1874  Here is an example of a simple call to \
1874  .sp  .sp
1875  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
1876  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,
1877  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD,
1878  PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last three of these are  PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last
1879  the same as for \fBpcre_exec()\fP, so their description is not repeated here.  four of these are exactly the same as for \fBpcre_exec()\fP, so their
1880  .sp  description is not repeated here.
1881    PCRE_PARTIAL  .sp
1882  .sp    PCRE_PARTIAL_HARD
1883  This has the same general effect as it does for \fBpcre_exec()\fP, but the    PCRE_PARTIAL_SOFT
1884  details are slightly different. When PCRE_PARTIAL is set for  .sp
1885  \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
1886  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
1887  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
1888  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
1889  matching string.  additional characters. This happens even if some complete matches have also
1890    been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
1891    is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
1892    there have been no complete matches, but there is still at least one matching
1893    possibility. The portion of the string that provided the longest partial match
1894    is set as the first matching string in both cases.
1895  .sp  .sp
1896    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
1897  .sp  .sp
# Line 1774  matching point in the subject string. Line 1902  matching point in the subject string.
1902  .sp  .sp
1903    PCRE_DFA_RESTART    PCRE_DFA_RESTART
1904  .sp  .sp
1905  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
1906  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
1907  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
1908  option requests this action; when it is set, the \fIworkspace\fP and  \fIworkspace\fP and \fIwscount\fP options must reference the same vector as
1909  \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
1910  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  
1911  .\" HREF  .\" HREF
1912  \fBpcrepartial\fP  \fBpcrepartial\fP
1913  .\"  .\"
# Line 1884  Cambridge CB2 3QH, England. Line 2011  Cambridge CB2 3QH, England.
2011  .rs  .rs
2012  .sp  .sp
2013  .nf  .nf
2014  Last updated: 30 July 2007  Last updated: 01 September 2009
2015  Copyright (c) 1997-2007 University of Cambridge.  Copyright (c) 1997-2009 University of Cambridge.
2016  .fi  .fi

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