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revision 191 by ph10, Mon Jul 30 11:13:54 2007 UTC revision 336 by ph10, Sat Apr 12 15:59:03 2008 UTC
# Line 140  distribution. The Line 140  distribution. The
140  .\" HREF  .\" HREF
141  \fBpcresample\fP  \fBpcresample\fP
142  .\"  .\"
143  documentation describes how to run it.  documentation describes how to compile and run it.
144  .P  .P
145  A second matching function, \fBpcre_dfa_exec()\fP, which is not  A second matching function, \fBpcre_dfa_exec()\fP, which is not
146  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 218  points during a matching operation. Deta
218  documentation.  documentation.
219  .  .
220  .  .
221    .\" HTML <a name="newlines"></a>
222  .SH NEWLINES  .SH NEWLINES
223  .rs  .rs
224  .sp  .sp
# Line 235  The default default is LF, which is the Line 236  The default default is LF, which is the
236  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
237  matched.  matched.
238  .P  .P
239    At compile time, the newline convention can be specified by the \fIoptions\fP
240    argument of \fBpcre_compile()\fP, or it can be specified by special text at the
241    start of the pattern itself; this overrides any other settings. See the
242    .\" HREF
243    \fBpcrepattern\fP
244    .\"
245    page for details of the special character sequences.
246    .P
247  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
248  pair of characters that indicate a line break". The choice of newline  pair of characters that indicate a line break". The choice of newline
249  convention affects the handling of the dot, circumflex, and dollar  convention affects the handling of the dot, circumflex, and dollar
250  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
251  recognized line ending sequence, the match position advancement for a  recognized line ending sequence, the match position advancement for a
252  non-anchored pattern. The choice of newline convention does not affect the  non-anchored pattern. There is more detail about this in the
253  interpretation of the \en or \er escape sequences.  .\" HTML <a href="#execoptions">
254    .\" </a>
255    section on \fBpcre_exec()\fP options
256    .\"
257    below.
258    .P
259    The choice of newline convention does not affect the interpretation of
260    the \en or \er escape sequences, nor does it affect what \eR matches, which is
261    controlled in a similar way, but by separate options.
262  .  .
263  .  .
264  .SH MULTITHREADING  .SH MULTITHREADING
# Line 303  that is recognized as meaning "newline". Line 320  that is recognized as meaning "newline".
320  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. The
321  default should normally be the standard sequence for your operating system.  default should normally be the standard sequence for your operating system.
322  .sp  .sp
323      PCRE_CONFIG_BSR
324    .sp
325    The output is an integer whose value indicates what character sequences the \eR
326    escape sequence matches by default. A value of 0 means that \eR matches any
327    Unicode line ending sequence; a value of 1 means that \eR matches only CR, LF,
328    or CRLF. The default can be overridden when a pattern is compiled or matched.
329    .sp
330    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
331  .sp  .sp
332  The output is an integer that contains the number of bytes used for internal  The output is an integer that contains the number of bytes used for internal
# Line 444  facility, see the Line 468  facility, see the
468  .\"  .\"
469  documentation.  documentation.
470  .sp  .sp
471      PCRE_BSR_ANYCRLF
472      PCRE_BSR_UNICODE
473    .sp
474    These options (which are mutually exclusive) control what the \eR escape
475    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
476    match any Unicode newline sequence. The default is specified when PCRE is
477    built. It can be overridden from within the pattern, or by setting an option
478    when a compiled pattern is matched.
479    .sp
480    PCRE_CASELESS    PCRE_CASELESS
481  .sp  .sp
482  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 549  If this option is set, an unanchored pat
549  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
550  over the newline.  over the newline.
551  .sp  .sp
552      PCRE_JAVASCRIPT_COMPAT
553    .sp
554    If this option is set, PCRE's behaviour is changed in some ways so that it is
555    compatible with JavaScript rather than Perl. The changes are as follows:
556    .P
557    (1) A lone closing square bracket in a pattern causes a compile-time error,
558    because this is illegal in JavaScript (by default it is treated as a data
559    character). Thus, the pattern AB]CD becomes illegal when this option is set.
560    .P
561    (2) At run time, a back reference to an unset subpattern group matches an empty
562    string (by default this causes the current matching path to fail). A pattern
563    such as (\1)(a) succeeds when this option is set (assuming it can find an "a"
564    in the subject), whereas it fails by default, for Perl compatibility.
565    .sp
566    PCRE_MULTILINE    PCRE_MULTILINE
567  .sp  .sp
568  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 648  page.
648    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
649  .sp  .sp
650  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
651  automatically checked. If an invalid UTF-8 sequence of bytes is found,  automatically checked. There is a discussion about the
652  \fBpcre_compile()\fP returns an error. If you already know that your pattern is  .\" HTML <a href="pcre.html#utf8strings">
653  valid, and you want to skip this check for performance reasons, you can set the  .\" </a>
654  PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid  validity of UTF-8 strings
655  UTF-8 string as a pattern is undefined. It may cause your program to crash.  .\"
656  Note that this option can also be passed to \fBpcre_exec()\fP and  in the main
657  \fBpcre_dfa_exec()\fP, to suppress the UTF-8 validity checking of subject  .\" HREF
658  strings.  \fBpcre\fP
659    .\"
660    page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_compile()\fP
661    returns an error. If you already know that your pattern is valid, and you want
662    to skip this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK
663    option. When it is set, the effect of passing an invalid UTF-8 string as a
664    pattern is undefined. It may cause your program to crash. Note that this option
665    can also be passed to \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, to suppress
666    the UTF-8 validity checking of subject strings.
667  .  .
668  .  .
669  .SH "COMPILATION ERROR CODES"  .SH "COMPILATION ERROR CODES"
# Line 631  out of use. To avoid confusion, they hav Line 686  out of use. To avoid confusion, they hav
686     9  nothing to repeat     9  nothing to repeat
687    10  [this code is not in use]    10  [this code is not in use]
688    11  internal error: unexpected repeat    11  internal error: unexpected repeat
689    12  unrecognized character after (?    12  unrecognized character after (? or (?-
690    13  POSIX named classes are supported only within a class    13  POSIX named classes are supported only within a class
691    14  missing )    14  missing )
692    15  reference to non-existent subpattern    15  reference to non-existent subpattern
# Line 639  out of use. To avoid confusion, they hav Line 694  out of use. To avoid confusion, they hav
694    17  unknown option bit(s) set    17  unknown option bit(s) set
695    18  missing ) after comment    18  missing ) after comment
696    19  [this code is not in use]    19  [this code is not in use]
697    20  regular expression too large    20  regular expression is too large
698    21  failed to get memory    21  failed to get memory
699    22  unmatched parentheses    22  unmatched parentheses
700    23  internal error: code overflow    23  internal error: code overflow
# Line 668  out of use. To avoid confusion, they hav Line 723  out of use. To avoid confusion, they hav
723    46  malformed \eP or \ep sequence    46  malformed \eP or \ep sequence
724    47  unknown property name after \eP or \ep    47  unknown property name after \eP or \ep
725    48  subpattern name is too long (maximum 32 characters)    48  subpattern name is too long (maximum 32 characters)
726    49  too many named subpatterns (maximum 10,000)    49  too many named subpatterns (maximum 10000)
727    50  repeated subpattern is too long    50  [this code is not in use]
728    51  octal value is greater than \e377 (not in UTF-8 mode)    51  octal value is greater than \e377 (not in UTF-8 mode)
729    52  internal error: overran compiling workspace    52  internal error: overran compiling workspace
730    53  internal error: previously-checked referenced subpattern not found    53  internal error: previously-checked referenced subpattern not found
731    54  DEFINE group contains more than one branch    54  DEFINE group contains more than one branch
732    55  repeating a DEFINE group is not allowed    55  repeating a DEFINE group is not allowed
733    56  inconsistent NEWLINE options"    56  inconsistent NEWLINE options
734    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
735          non-zero number          name/number or by a plain number
736    58  (?+ or (?- or (?(+ or (?(- must be followed by a non-zero number    58  a numbered reference must not be zero
737      59  (*VERB) with an argument is not supported
738      60  (*VERB) not recognized
739      61  number is too big
740      62  subpattern name expected
741      63  digit expected after (?+
742      64  ] is an invalid data character in JavaScript compatibility mode
743    .sp
744    The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
745    be used if the limits were changed when PCRE was built.
746  .  .
747  .  .
748  .SH "STUDYING A PATTERN"  .SH "STUDYING A PATTERN"
# Line 874  table indicating a fixed set of bytes fo Line 938  table indicating a fixed set of bytes fo
938  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
939  fourth argument should point to an \fBunsigned char *\fP variable.  fourth argument should point to an \fBunsigned char *\fP variable.
940  .sp  .sp
941      PCRE_INFO_HASCRORLF
942    .sp
943    Return 1 if the pattern contains any explicit matches for CR or LF characters,
944    otherwise 0. The fourth argument should point to an \fBint\fP variable. An
945    explicit match is either a literal CR or LF character, or \er or \en.
946    .sp
947    PCRE_INFO_JCHANGED    PCRE_INFO_JCHANGED
948  .sp  .sp
949  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
950  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
951  setting changes the local PCRE_DUPNAMES option.  (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
952  .sp  .sp
953    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
954  .sp  .sp
# Line 947  matching is used. Line 1017  matching is used.
1017  Return a copy of the options with which the pattern was compiled. The fourth  Return a copy of the options with which the pattern was compiled. The fourth
1018  argument should point to an \fBunsigned long int\fP variable. These option bits  argument should point to an \fBunsigned long int\fP variable. These option bits
1019  are those specified in the call to \fBpcre_compile()\fP, modified by any  are those specified in the call to \fBpcre_compile()\fP, modified by any
1020  top-level option settings within the pattern itself.  top-level option settings at the start of the pattern itself. In other words,
1021    they are the options that will be in force when matching starts. For example,
1022    if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED option, the
1023    result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED.
1024  .P  .P
1025  A pattern is automatically anchored by PCRE if all of its top-level  A pattern is automatically anchored by PCRE if all of its top-level
1026  alternatives begin with one of the following:  alternatives begin with one of the following:
# Line 1158  called. See the Line 1231  called. See the
1231  .\"  .\"
1232  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1233  .  .
1234    .\" HTML <a name="execoptions"></a>
1235  .SS "Option bits for \fBpcre_exec()\fP"  .SS "Option bits for \fBpcre_exec()\fP"
1236  .rs  .rs
1237  .sp  .sp
# Line 1172  matching position. If a pattern was comp Line 1246  matching position. If a pattern was comp
1246  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
1247  matching time.  matching time.
1248  .sp  .sp
1249      PCRE_BSR_ANYCRLF
1250      PCRE_BSR_UNICODE
1251    .sp
1252    These options (which are mutually exclusive) control what the \eR escape
1253    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
1254    match any Unicode newline sequence. These options override the choice that was
1255    made or defaulted when the pattern was compiled.
1256    .sp
1257    PCRE_NEWLINE_CR    PCRE_NEWLINE_CR
1258    PCRE_NEWLINE_LF    PCRE_NEWLINE_LF
1259    PCRE_NEWLINE_CRLF    PCRE_NEWLINE_CRLF
# Line 1183  the pattern was compiled. For details, s Line 1265  the pattern was compiled. For details, s
1265  \fBpcre_compile()\fP above. During matching, the newline choice affects the  \fBpcre_compile()\fP above. During matching, the newline choice affects the
1266  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1267  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
1268  pattern. When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is  pattern.
1269  set, and a match attempt fails when the current position is at a CRLF sequence,  .P
1270  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
1271  words, to after the CRLF.  match attempt for an unanchored pattern fails when the current position is at a
1272    CRLF sequence, and the pattern contains no explicit matches for CR or LF
1273    characters, the match position is advanced by two characters instead of one, in
1274    other words, to after the CRLF.
1275    .P
1276    The above rule is a compromise that makes the most common cases work as
1277    expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
1278    set), it does not match the string "\er\enA" because, after failing at the
1279    start, it skips both the CR and the LF before retrying. However, the pattern
1280    [\er\en]A does match that string, because it contains an explicit CR or LF
1281    reference, and so advances only by one character after the first failure.
1282    .P
1283    An explicit match for CR of LF is either a literal appearance of one of those
1284    characters, or one of the \er or \en escape sequences. Implicit matches such as
1285    [^X] do not count, nor does \es (which includes CR and LF in the characters
1286    that it matches).
1287    .P
1288    Notwithstanding the above, anomalous effects may still occur when CRLF is a
1289    valid newline sequence and explicit \er or \en escapes appear in the pattern.
1290  .sp  .sp
1291    PCRE_NOTBOL    PCRE_NOTBOL
1292  .sp  .sp
# Line 1229  code that demonstrates how to do this in Line 1329  code that demonstrates how to do this in
1329  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
1330  string is automatically checked when \fBpcre_exec()\fP is subsequently called.  string is automatically checked when \fBpcre_exec()\fP is subsequently called.
1331  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
1332  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
1333  \fBpcre_exec()\fP returns the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP  strings in the
1334  contains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.  .\" HTML <a href="pcre.html#utf8strings">
1335    .\" </a>
1336    section on UTF-8 support
1337    .\"
1338    in the main
1339    .\" HREF
1340    \fBpcre\fP
1341    .\"
1342    page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns
1343    the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP contains an invalid value,
1344    PCRE_ERROR_BADUTF8_OFFSET is returned.
1345  .P  .P
1346  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
1347  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 1463  The internal recursion limit, as specifi Line 1573  The internal recursion limit, as specifi
1573  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
1574  description above.  description above.
1575  .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  
1576    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
1577  .sp  .sp
1578  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
1579  .P  .P
1580  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.
1581  .  .
1582  .  .
1583  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
# Line 1651  example is shown in the Line 1742  example is shown in the
1742  .\" HREF  .\" HREF
1743  \fBpcrepattern\fP  \fBpcrepattern\fP
1744  .\"  .\"
1745  documentation. When duplicates are present, \fBpcre_copy_named_substring()\fP  documentation.
1746  and \fBpcre_get_named_substring()\fP return the first substring corresponding  .P
1747  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
1748  The \fBpcre_get_stringnumber()\fP function returns one of the numbers that are  \fBpcre_get_named_substring()\fP return the first substring corresponding to
1749  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
1750  .sp  returned; no data is returned. The \fBpcre_get_stringnumber()\fP function
1751    returns one of the numbers that are associated with the name, but it is not
1752    defined which it is.
1753    .P
1754  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,
1755  you must use the \fBpcre_get_stringtable_entries()\fP function. The first  you must use the \fBpcre_get_stringtable_entries()\fP function. The first
1756  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 1881  Cambridge CB2 3QH, England. Line 1975  Cambridge CB2 3QH, England.
1975  .rs  .rs
1976  .sp  .sp
1977  .nf  .nf
1978  Last updated: 30 July 2007  Last updated: 12 April 2008
1979  Copyright (c) 1997-2007 University of Cambridge.  Copyright (c) 1997-2008 University of Cambridge.
1980  .fi  .fi

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