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revision 142 by ph10, Fri Mar 30 15:55:18 2007 UTC revision 426 by ph10, Wed Aug 26 15:38:32 2009 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
225  PCRE supports four different conventions for indicating line breaks in  PCRE supports five different conventions for indicating line breaks in
226  strings: a single CR (carriage return) character, a single LF (linefeed)  strings: a single CR (carriage return) character, a single LF (linefeed)
227  character, the two-character sequence CRLF, or any Unicode newline sequence.  character, the two-character sequence CRLF, any of the three preceding, or any
228  The Unicode newline sequences are the three just mentioned, plus the single  Unicode newline sequence. The Unicode newline sequences are the three just
229  characters VT (vertical tab, U+000B), FF (formfeed, U+000C), NEL (next line,  mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed,
230  U+0085), LS (line separator, U+2028), and PS (paragraph separator, U+2029).  U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
231    (paragraph separator, U+2029).
232  .P  .P
233  Each of the first three conventions is used by at least one operating system as  Each of the first three conventions is used by at least one operating system as
234  its standard newline sequence. When PCRE is built, a default can be specified.  its standard newline sequence. When PCRE is built, a default can be specified.
# Line 234  The default default is LF, which is the Line 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 264  which it was compiled. Details are given Line 282  which it was compiled. Details are given
282  .\" HREF  .\" HREF
283  \fBpcreprecompile\fP  \fBpcreprecompile\fP
284  .\"  .\"
285  documentation.  documentation. However, compiling a regular expression with one version of PCRE
286    for use with a different version is not guaranteed to work and may cause
287    crashes.
288  .  .
289  .  .
290  .SH "CHECKING BUILD-TIME OPTIONS"  .SH "CHECKING BUILD-TIME OPTIONS"
# Line 297  properties is available; otherwise it is Line 317  properties is available; otherwise it is
317  .sp  .sp
318  The output is an integer whose value specifies the default character sequence  The output is an integer whose value specifies the default character sequence
319  that is recognized as meaning "newline". The four values that are supported  that is recognized as meaning "newline". The four values that are supported
320  are: 10 for LF, 13 for CR, 3338 for CRLF, and -1 for ANY. The default should  are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF, and -1 for ANY.
321  normally be the standard sequence for your operating system.  Though they are derived from ASCII, the same values are returned in EBCDIC
322    environments. The default should normally correspond to the standard sequence
323    for your operating system.
324    .sp
325      PCRE_CONFIG_BSR
326    .sp
327    The output is an integer whose value indicates what character sequences the \eR
328    escape sequence matches by default. A value of 0 means that \eR matches any
329    Unicode line ending sequence; a value of 1 means that \eR matches only CR, LF,
330    or CRLF. The default can be overridden when a pattern is compiled or matched.
331  .sp  .sp
332    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
333  .sp  .sp
# Line 320  documentation. Line 349  documentation.
349  .sp  .sp
350    PCRE_CONFIG_MATCH_LIMIT    PCRE_CONFIG_MATCH_LIMIT
351  .sp  .sp
352  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
353  internal matching function calls in a \fBpcre_exec()\fP execution. Further  internal matching function calls in a \fBpcre_exec()\fP execution. Further
354  details are given with \fBpcre_exec()\fP below.  details are given with \fBpcre_exec()\fP below.
355  .sp  .sp
356    PCRE_CONFIG_MATCH_LIMIT_RECURSION    PCRE_CONFIG_MATCH_LIMIT_RECURSION
357  .sp  .sp
358  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
359  recursion when calling the internal matching function in a \fBpcre_exec()\fP  recursion when calling the internal matching function in a \fBpcre_exec()\fP
360  execution. Further details are given with \fBpcre_exec()\fP below.  execution. Further details are given with \fBpcre_exec()\fP below.
361  .sp  .sp
# Line 377  argument, which is an address (see below Line 406  argument, which is an address (see below
406  .P  .P
407  The \fIoptions\fP argument contains various bit settings that affect the  The \fIoptions\fP argument contains various bit settings that affect the
408  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
409  options are described below. Some of them, in particular, those that are  options are described below. Some of them (in particular, those that are
410  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
411  the detailed description in the  within the pattern (see the detailed description in the
412  .\" HREF  .\" HREF
413  \fBpcrepattern\fP  \fBpcrepattern\fP
414  .\"  .\"
415  documentation). For these options, the contents of the \fIoptions\fP argument  documentation). For those options that can be different in different parts of
416  specifies their initial settings at the start of compilation and execution. The  the pattern, the contents of the \fIoptions\fP argument specifies their initial
417  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
418  matching as well as at compile time.  PCRE_NEWLINE_\fIxxx\fP options can be set at the time of matching as well as at
419    compile time.
420  .P  .P
421  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
422  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
# Line 441  facility, see the Line 471  facility, see the
471  .\"  .\"
472  documentation.  documentation.
473  .sp  .sp
474      PCRE_BSR_ANYCRLF
475      PCRE_BSR_UNICODE
476    .sp
477    These options (which are mutually exclusive) control what the \eR escape
478    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
479    match any Unicode newline sequence. The default is specified when PCRE is
480    built. It can be overridden from within the pattern, or by setting an option
481    when a compiled pattern is matched.
482    .sp
483    PCRE_CASELESS    PCRE_CASELESS
484  .sp  .sp
485  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 513  If this option is set, an unanchored pat Line 552  If this option is set, an unanchored pat
552  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
553  over the newline.  over the newline.
554  .sp  .sp
555      PCRE_JAVASCRIPT_COMPAT
556    .sp
557    If this option is set, PCRE's behaviour is changed in some ways so that it is
558    compatible with JavaScript rather than Perl. The changes are as follows:
559    .P
560    (1) A lone closing square bracket in a pattern causes a compile-time error,
561    because this is illegal in JavaScript (by default it is treated as a data
562    character). Thus, the pattern AB]CD becomes illegal when this option is set.
563    .P
564    (2) At run time, a back reference to an unset subpattern group matches an empty
565    string (by default this causes the current matching alternative to fail). A
566    pattern such as (\e1)(a) succeeds when this option is set (assuming it can find
567    an "a" in the subject), whereas it fails by default, for Perl compatibility.
568    .sp
569    PCRE_MULTILINE    PCRE_MULTILINE
570  .sp  .sp
571  By default, PCRE treats the subject string as consisting of a single line of  By default, PCRE treats the subject string as consisting of a single line of
# Line 532  occurrences of ^ or $ in a pattern, sett Line 585  occurrences of ^ or $ in a pattern, sett
585    PCRE_NEWLINE_CR    PCRE_NEWLINE_CR
586    PCRE_NEWLINE_LF    PCRE_NEWLINE_LF
587    PCRE_NEWLINE_CRLF    PCRE_NEWLINE_CRLF
588      PCRE_NEWLINE_ANYCRLF
589    PCRE_NEWLINE_ANY    PCRE_NEWLINE_ANY
590  .sp  .sp
591  These options override the default newline definition that was chosen when PCRE  These options override the default newline definition that was chosen when PCRE
592  was built. Setting the first or the second specifies that a newline is  was built. Setting the first or the second specifies that a newline is
593  indicated by a single character (CR or LF, respectively). Setting  indicated by a single character (CR or LF, respectively). Setting
594  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
595  CRLF sequence. Setting PCRE_NEWLINE_ANY specifies that any Unicode newline  CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three
596  sequence should be recognized. The Unicode newline sequences are the three just  preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies
597  mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed,  that any Unicode newline sequence should be recognized. The Unicode newline
598  U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS  sequences are the three just mentioned, plus the single characters VT (vertical
599  (paragraph separator, U+2029). The last two are recognized only in UTF-8 mode.  tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS (line
600    separator, U+2028), and PS (paragraph separator, U+2029). The last two are
601    recognized only in UTF-8 mode.
602  .P  .P
603  The newline setting in the options word uses three bits that are treated  The newline setting in the options word uses three bits that are treated
604  as a number, giving eight possibilities. Currently only five are used (default  as a number, giving eight possibilities. Currently only six are used (default
605  plus the four values above). This means that if you set more than one newline  plus the five values above). This means that if you set more than one newline
606  option, the combination may or may not be sensible. For example,  option, the combination may or may not be sensible. For example,
607  PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but  PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
608  other combinations yield unused numbers and cause an error.  other combinations may yield unused numbers and cause an error.
609  .P  .P
610  The only time that a line break is specially recognized when compiling a  The only time that a line break is specially recognized when compiling a
611  pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character  pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character
# Line 595  page. Line 651  page.
651    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
652  .sp  .sp
653  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
654  automatically checked. If an invalid UTF-8 sequence of bytes is found,  automatically checked. There is a discussion about the
655  \fBpcre_compile()\fP returns an error. If you already know that your pattern is  .\" HTML <a href="pcre.html#utf8strings">
656  valid, and you want to skip this check for performance reasons, you can set the  .\" </a>
657  PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid  validity of UTF-8 strings
658  UTF-8 string as a pattern is undefined. It may cause your program to crash.  .\"
659  Note that this option can also be passed to \fBpcre_exec()\fP and  in the main
660  \fBpcre_dfa_exec()\fP, to suppress the UTF-8 validity checking of subject  .\" HREF
661  strings.  \fBpcre\fP
662    .\"
663    page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_compile()\fP
664    returns an error. If you already know that your pattern is valid, and you want
665    to skip this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK
666    option. When it is set, the effect of passing an invalid UTF-8 string as a
667    pattern is undefined. It may cause your program to crash. Note that this option
668    can also be passed to \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, to suppress
669    the UTF-8 validity checking of subject strings.
670  .  .
671  .  .
672  .SH "COMPILATION ERROR CODES"  .SH "COMPILATION ERROR CODES"
# Line 625  out of use. To avoid confusion, they hav Line 689  out of use. To avoid confusion, they hav
689     9  nothing to repeat     9  nothing to repeat
690    10  [this code is not in use]    10  [this code is not in use]
691    11  internal error: unexpected repeat    11  internal error: unexpected repeat
692    12  unrecognized character after (?    12  unrecognized character after (? or (?-
693    13  POSIX named classes are supported only within a class    13  POSIX named classes are supported only within a class
694    14  missing )    14  missing )
695    15  reference to non-existent subpattern    15  reference to non-existent subpattern
# Line 633  out of use. To avoid confusion, they hav Line 697  out of use. To avoid confusion, they hav
697    17  unknown option bit(s) set    17  unknown option bit(s) set
698    18  missing ) after comment    18  missing ) after comment
699    19  [this code is not in use]    19  [this code is not in use]
700    20  regular expression too large    20  regular expression is too large
701    21  failed to get memory    21  failed to get memory
702    22  unmatched parentheses    22  unmatched parentheses
703    23  internal error: code overflow    23  internal error: code overflow
# Line 642  out of use. To avoid confusion, they hav Line 706  out of use. To avoid confusion, they hav
706    26  malformed number or name after (?(    26  malformed number or name after (?(
707    27  conditional group contains more than two branches    27  conditional group contains more than two branches
708    28  assertion expected after (?(    28  assertion expected after (?(
709    29  (?R or (?digits must be followed by )    29  (?R or (?[+-]digits must be followed by )
710    30  unknown POSIX class name    30  unknown POSIX class name
711    31  POSIX collating elements are not supported    31  POSIX collating elements are not supported
712    32  this version of PCRE is not compiled with PCRE_UTF8 support    32  this version of PCRE is not compiled with PCRE_UTF8 support
# Line 662  out of use. To avoid confusion, they hav Line 726  out of use. To avoid confusion, they hav
726    46  malformed \eP or \ep sequence    46  malformed \eP or \ep sequence
727    47  unknown property name after \eP or \ep    47  unknown property name after \eP or \ep
728    48  subpattern name is too long (maximum 32 characters)    48  subpattern name is too long (maximum 32 characters)
729    49  too many named subpatterns (maximum 10,000)    49  too many named subpatterns (maximum 10000)
730    50  repeated subpattern is too long    50  [this code is not in use]
731    51  octal value is greater than \e377 (not in UTF-8 mode)    51  octal value is greater than \e377 (not in UTF-8 mode)
732    52  internal error: overran compiling workspace    52  internal error: overran compiling workspace
733    53  internal error: previously-checked referenced subpattern not found    53  internal error: previously-checked referenced subpattern not found
734    54  DEFINE group contains more than one branch    54  DEFINE group contains more than one branch
735    55  repeating a DEFINE group is not allowed    55  repeating a DEFINE group is not allowed
736    56  inconsistent NEWLINE options"    56  inconsistent NEWLINE options
737      57  \eg is not followed by a braced, angle-bracketed, or quoted
738            name/number or by a plain number
739      58  a numbered reference must not be zero
740      59  (*VERB) with an argument is not supported
741      60  (*VERB) not recognized
742      61  number is too big
743      62  subpattern name expected
744      63  digit expected after (?+
745      64  ] is an invalid data character in JavaScript compatibility mode
746    .sp
747    The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
748    be used if the limits were changed when PCRE was built.
749  .  .
750  .  .
751  .SH "STUDYING A PATTERN"  .SH "STUDYING A PATTERN"
# Line 865  table indicating a fixed set of bytes fo Line 941  table indicating a fixed set of bytes fo
941  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
942  fourth argument should point to an \fBunsigned char *\fP variable.  fourth argument should point to an \fBunsigned char *\fP variable.
943  .sp  .sp
944      PCRE_INFO_HASCRORLF
945    .sp
946    Return 1 if the pattern contains any explicit matches for CR or LF characters,
947    otherwise 0. The fourth argument should point to an \fBint\fP variable. An
948    explicit match is either a literal CR or LF character, or \er or \en.
949    .sp
950      PCRE_INFO_JCHANGED
951    .sp
952    Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise
953    0. The fourth argument should point to an \fBint\fP variable. (?J) and
954    (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
955    .sp
956    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
957  .sp  .sp
958  Return the value of the rightmost literal byte that must exist in any matched  Return the value of the rightmost literal byte that must exist in any matched
# Line 917  When writing code to extract data from n Line 1005  When writing code to extract data from n
1005  name-to-number map, remember that the length of the entries is likely to be  name-to-number map, remember that the length of the entries is likely to be
1006  different for each compiled pattern.  different for each compiled pattern.
1007  .sp  .sp
1008      PCRE_INFO_OKPARTIAL
1009    .sp
1010    Return 1 if the pattern can be used for partial matching, otherwise 0. The
1011    fourth argument should point to an \fBint\fP variable. From release 8.00, this
1012    always returns 1, because the restrictions that previously applied to partial
1013    matching have been lifted. The
1014    .\" HREF
1015    \fBpcrepartial\fP
1016    .\"
1017    documentation gives details of partial matching.
1018    .sp
1019    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1020  .sp  .sp
1021  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
1022  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
1023  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
1024  top-level option settings within the pattern itself.  top-level option settings at the start of the pattern itself. In other words,
1025    they are the options that will be in force when matching starts. For example,
1026    if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED option, the
1027    result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED.
1028  .P  .P
1029  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
1030  alternatives begin with one of the following:  alternatives begin with one of the following:
# Line 1133  called. See the Line 1235  called. See the
1235  .\"  .\"
1236  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1237  .  .
1238    .\" HTML <a name="execoptions"></a>
1239  .SS "Option bits for \fBpcre_exec()\fP"  .SS "Option bits for \fBpcre_exec()\fP"
1240  .rs  .rs
1241  .sp  .sp
1242  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
1243  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,
1244  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_START_OPTIMIZE,
1245    PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.
1246  .sp  .sp
1247    PCRE_ANCHORED    PCRE_ANCHORED
1248  .sp  .sp
# Line 1147  matching position. If a pattern was comp Line 1251  matching position. If a pattern was comp
1251  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
1252  matching time.  matching time.
1253  .sp  .sp
1254      PCRE_BSR_ANYCRLF
1255      PCRE_BSR_UNICODE
1256    .sp
1257    These options (which are mutually exclusive) control what the \eR escape
1258    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
1259    match any Unicode newline sequence. These options override the choice that was
1260    made or defaulted when the pattern was compiled.
1261    .sp
1262    PCRE_NEWLINE_CR    PCRE_NEWLINE_CR
1263    PCRE_NEWLINE_LF    PCRE_NEWLINE_LF
1264    PCRE_NEWLINE_CRLF    PCRE_NEWLINE_CRLF
1265      PCRE_NEWLINE_ANYCRLF
1266    PCRE_NEWLINE_ANY    PCRE_NEWLINE_ANY
1267  .sp  .sp
1268  These options override the newline definition that was chosen or defaulted when  These options override the newline definition that was chosen or defaulted when
# Line 1157  the pattern was compiled. For details, s Line 1270  the pattern was compiled. For details, s
1270  \fBpcre_compile()\fP above. During matching, the newline choice affects the  \fBpcre_compile()\fP above. During matching, the newline choice affects the
1271  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1272  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
1273  pattern. When PCRE_NEWLINE_CRLF or PCRE_NEWLINE_ANY is set, and a match attempt  pattern.
1274  fails when the current position is at a CRLF sequence, the match position is  .P
1275  advanced by two characters instead of one, in other words, to after the CRLF.  When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a
1276    match attempt for an unanchored pattern fails when the current position is at a
1277    CRLF sequence, and the pattern contains no explicit matches for CR or LF
1278    characters, the match position is advanced by two characters instead of one, in
1279    other words, to after the CRLF.
1280    .P
1281    The above rule is a compromise that makes the most common cases work as
1282    expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
1283    set), it does not match the string "\er\enA" because, after failing at the
1284    start, it skips both the CR and the LF before retrying. However, the pattern
1285    [\er\en]A does match that string, because it contains an explicit CR or LF
1286    reference, and so advances only by one character after the first failure.
1287    .P
1288    An explicit match for CR of LF is either a literal appearance of one of those
1289    characters, or one of the \er or \en escape sequences. Implicit matches such as
1290    [^X] do not count, nor does \es (which includes CR and LF in the characters
1291    that it matches).
1292    .P
1293    Notwithstanding the above, anomalous effects may still occur when CRLF is a
1294    valid newline sequence and explicit \er or \en escapes appear in the pattern.
1295  .sp  .sp
1296    PCRE_NOTBOL    PCRE_NOTBOL
1297  .sp  .sp
# Line 1197  PCRE_NOTEMPTY and PCRE_ANCHORED, and the Line 1329  PCRE_NOTEMPTY and PCRE_ANCHORED, and the
1329  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
1330  code that demonstrates how to do this in the \fIpcredemo.c\fP sample program.  code that demonstrates how to do this in the \fIpcredemo.c\fP sample program.
1331  .sp  .sp
1332      PCRE_NO_START_OPTIMIZE
1333    .sp
1334    There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1335    a match, in order to speed up the process. For example, if it is known that a
1336    match must start with a specific character, it searches the subject for that
1337    character, and fails immediately if it cannot find it, without actually running
1338    the main matching function. When callouts are in use, these optimizations can
1339    cause them to be skipped. This option disables the "start-up" optimizations,
1340    causing performance to suffer, but ensuring that the callouts do occur.
1341    .sp
1342    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1343  .sp  .sp
1344  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
1345  string is automatically checked when \fBpcre_exec()\fP is subsequently called.  string is automatically checked when \fBpcre_exec()\fP is subsequently called.
1346  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
1347  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
1348  \fBpcre_exec()\fP returns the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP  strings in the
1349  contains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.  .\" HTML <a href="pcre.html#utf8strings">
1350    .\" </a>
1351    section on UTF-8 support
1352    .\"
1353    in the main
1354    .\" HREF
1355    \fBpcre\fP
1356    .\"
1357    page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns
1358    the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP contains an invalid value,
1359    PCRE_ERROR_BADUTF8_OFFSET is returned.
1360  .P  .P
1361  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
1362  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 1223  to match the pattern, but at some point Line 1375  to match the pattern, but at some point
1375  the subject was reached (that is, the subject partially matches the pattern and  the subject was reached (that is, the subject partially matches the pattern and
1376  the failure to match occurred only because there were not enough subject  the failure to match occurred only because there were not enough subject
1377  characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of  characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of
1378  PCRE_ERROR_NOMATCH. When PCRE_PARTIAL is used, there are restrictions on what  PCRE_ERROR_NOMATCH. The portion of the string that provided the longest partial
1379  may appear in the pattern. These are discussed in the  match is set as the first matching string. There is further discussion in the
1380  .\" HREF  .\" HREF
1381  \fBpcrepartial\fP  \fBpcrepartial\fP
1382  .\"  .\"
# Line 1234  documentation. Line 1386  documentation.
1386  .rs  .rs
1387  .sp  .sp
1388  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
1389  \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
1390  \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
1391  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
1392  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
1393  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.
1394  .P  .P
1395  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
1396  same subject by calling \fBpcre_exec()\fP again after a previous success.  same subject by calling \fBpcre_exec()\fP again after a previous success.
# Line 1272  pattern. Following the usage in Jeffrey Line 1424  pattern. Following the usage in Jeffrey
1424  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
1425  kinds of parenthesized subpattern that do not cause substrings to be captured.  kinds of parenthesized subpattern that do not cause substrings to be captured.
1426  .P  .P
1427  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
1428  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
1429  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
1430  this argument is NOT the size of \fIovector\fP in bytes.  argument is NOT the size of \fIovector\fP in bytes.
1431  .P  .P
1432  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,
1433  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
1434  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
1435  and is not available for passing back information. The length passed in  and is not available for passing back information. The number passed in
1436  \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
1437  rounded down.  rounded down.
1438  .P  .P
1439  When a match is successful, information about captured substrings is returned  When a match is successful, information about captured substrings is returned
1440  in pairs of integers, starting at the beginning of \fIovector\fP, and  in pairs of integers, starting at the beginning of \fIovector\fP, and
1441  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
1442  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
1443  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
1444  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
1445  subject string matched by the entire pattern. The next pair is used for the  mode. They are not character counts.
1446  first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fP  .P
1447  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
1448  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
1449  capturing subpatterns, the return value from a successful match is 1,  used for the first capturing subpattern, and so on. The value returned by
1450  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.
1451    For example, if two substrings have been captured, the returned value is 3. If
1452    there are no capturing subpatterns, the return value from a successful match is
1453    1, indicating that just the first pair of offsets has been set.
1454  .P  .P
1455  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
1456  string that it matched that is returned.  string that it matched that is returned.
1457  .P  .P
1458  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
1459  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
1460  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,
1461  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
1462  \fIovecsize\fP as zero. However, if the pattern contains back references and  \fIovecsize\fP as zero. However, if the pattern contains back references and
1463  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
1464  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 1414  documentation for details of partial mat Line 1569  documentation for details of partial mat
1569  .sp  .sp
1570    PCRE_ERROR_BADPARTIAL     (-13)    PCRE_ERROR_BADPARTIAL     (-13)
1571  .sp  .sp
1572  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
1573  are not supported for partial matching. See the  option was used with a compiled pattern containing items that were not
1574  .\" HREF  supported for partial matching. From release 8.00 onwards, there are no
1575  \fBpcrepartial\fP  restrictions on partial matching.
 .\"  
 documentation for details of partial matching.  
1576  .sp  .sp
1577    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
1578  .sp  .sp
# Line 1436  The internal recursion limit, as specifi Line 1589  The internal recursion limit, as specifi
1589  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
1590  description above.  description above.
1591  .sp  .sp
   PCRE_ERROR_NULLWSLIMIT    (-22)  
 .sp  
 When a group that can match an empty substring is repeated with an unbounded  
 upper limit, the subject position at the start of the group must be remembered,  
 so that a test for an empty string can be made when the end of the group is  
 reached. Some workspace is required for this; if it runs out, this error is  
 given.  
 .sp  
1592    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
1593  .sp  .sp
1594  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
1595  .P  .P
1596  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.
1597  .  .
1598  .  .
1599  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
# Line 1597  These functions call \fBpcre_get_stringn Line 1742  These functions call \fBpcre_get_stringn
1742  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
1743  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,
1744  the behaviour may not be what you want (see the next section).  the behaviour may not be what you want (see the next section).
1745  .  .P
1746    \fBWarning:\fP If the pattern uses the "(?|" feature to set up multiple
1747    subpatterns with the same number, you cannot use names to distinguish them,
1748    because names are not included in the compiled code. The matching process uses
1749    only numbers.
1750  .  .
1751  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
1752  .rs  .rs
# Line 1613  example is shown in the Line 1762  example is shown in the
1762  .\" HREF  .\" HREF
1763  \fBpcrepattern\fP  \fBpcrepattern\fP
1764  .\"  .\"
1765  documentation. When duplicates are present, \fBpcre_copy_named_substring()\fP  documentation.
1766  and \fBpcre_get_named_substring()\fP return the first substring corresponding  .P
1767  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
1768  The \fBpcre_get_stringnumber()\fP function returns one of the numbers that are  \fBpcre_get_named_substring()\fP return the first substring corresponding to
1769  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
1770  .sp  returned; no data is returned. The \fBpcre_get_stringnumber()\fP function
1771    returns one of the numbers that are associated with the name, but it is not
1772    defined which it is.
1773    .P
1774  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,
1775  you must use the \fBpcre_get_stringtable_entries()\fP function. The first  you must use the \fBpcre_get_stringtable_entries()\fP function. The first
1776  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 1712  The unused bits of the \fIoptions\fP arg Line 1864  The unused bits of the \fIoptions\fP arg
1864  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,
1865  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,
1866  PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last three of these are  PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last three of these are
1867  the same as for \fBpcre_exec()\fP, so their description is not repeated here.  exactly the same as for \fBpcre_exec()\fP, so their description is not repeated
1868    here.
1869  .sp  .sp
1870    PCRE_PARTIAL    PCRE_PARTIAL
1871  .sp  .sp
# Line 1721  details are slightly different. When PCR Line 1874  details are slightly different. When PCR
1874  \fBpcre_dfa_exec()\fP, the return code PCRE_ERROR_NOMATCH is converted into  \fBpcre_dfa_exec()\fP, the return code PCRE_ERROR_NOMATCH is converted into
1875  PCRE_ERROR_PARTIAL if the end of the subject is reached, there have been no  PCRE_ERROR_PARTIAL if the end of the subject is reached, there have been no
1876  complete matches, but there is still at least one matching possibility. The  complete matches, but there is still at least one matching possibility. The
1877  portion of the string that provided the partial match is set as the first  portion of the string that provided the longest partial match is set as the
1878  matching string.  first matching string.
1879  .sp  .sp
1880    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
1881  .sp  .sp
# Line 1843  Cambridge CB2 3QH, England. Line 1996  Cambridge CB2 3QH, England.
1996  .rs  .rs
1997  .sp  .sp
1998  .nf  .nf
1999  Last updated: 06 March 2007  Last updated: 26 August 2009
2000  Copyright (c) 1997-2007 University of Cambridge.  Copyright (c) 1997-2009 University of Cambridge.
2001  .fi  .fi

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