/[pcre]/code/trunk/doc/html/pcreapi.html
ViewVC logotype

Diff of /code/trunk/doc/html/pcreapi.html

Parent Directory Parent Directory | Revision Log Revision Log | View Patch Patch

revision 172 by ph10, Tue Jun 5 10:40:13 2007 UTC revision 345 by ph10, Mon Apr 28 15:10:02 2008 UTC
# Line 167  in a Perl-compatible manner. A sample pr Line 167  in a Perl-compatible manner. A sample pr
167  way of using them is provided in the file called <i>pcredemo.c</i> in the source  way of using them is provided in the file called <i>pcredemo.c</i> in the source
168  distribution. The  distribution. The
169  <a href="pcresample.html"><b>pcresample</b></a>  <a href="pcresample.html"><b>pcresample</b></a>
170  documentation describes how to run it.  documentation describes how to compile and run it.
171  </P>  </P>
172  <P>  <P>
173  A second matching function, <b>pcre_dfa_exec()</b>, which is not  A second matching function, <b>pcre_dfa_exec()</b>, which is not
# Line 243  by the caller to a "callout" function, w Line 243  by the caller to a "callout" function, w
243  points during a matching operation. Details are given in the  points during a matching operation. Details are given in the
244  <a href="pcrecallout.html"><b>pcrecallout</b></a>  <a href="pcrecallout.html"><b>pcrecallout</b></a>
245  documentation.  documentation.
246  </P>  <a name="newlines"></a></P>
247  <br><a name="SEC3" href="#TOC1">NEWLINES</a><br>  <br><a name="SEC3" href="#TOC1">NEWLINES</a><br>
248  <P>  <P>
249  PCRE supports five different conventions for indicating line breaks in  PCRE supports five different conventions for indicating line breaks in
# Line 262  default can be overridden, either when a Line 262  default can be overridden, either when a
262  matched.  matched.
263  </P>  </P>
264  <P>  <P>
265    At compile time, the newline convention can be specified by the <i>options</i>
266    argument of <b>pcre_compile()</b>, or it can be specified by special text at the
267    start of the pattern itself; this overrides any other settings. See the
268    <a href="pcrepattern.html"><b>pcrepattern</b></a>
269    page for details of the special character sequences.
270    </P>
271    <P>
272  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
273  pair of characters that indicate a line break". The choice of newline  pair of characters that indicate a line break". The choice of newline
274  convention affects the handling of the dot, circumflex, and dollar  convention affects the handling of the dot, circumflex, and dollar
275  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
276  recognized line ending sequence, the match position advancement for a  recognized line ending sequence, the match position advancement for a
277  non-anchored pattern. The choice of newline convention does not affect the  non-anchored pattern. There is more detail about this in the
278  interpretation of the \n or \r escape sequences.  <a href="#execoptions">section on <b>pcre_exec()</b> options</a>
279    below.
280    </P>
281    <P>
282    The choice of newline convention does not affect the interpretation of
283    the \n or \r escape sequences, nor does it affect what \R matches, which is
284    controlled in a similar way, but by separate options.
285  </P>  </P>
286  <br><a name="SEC4" href="#TOC1">MULTITHREADING</a><br>  <br><a name="SEC4" href="#TOC1">MULTITHREADING</a><br>
287  <P>  <P>
# Line 323  that is recognized as meaning "newline". Line 336  that is recognized as meaning "newline".
336  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
337  default should normally be the standard sequence for your operating system.  default should normally be the standard sequence for your operating system.
338  <pre>  <pre>
339      PCRE_CONFIG_BSR
340    </pre>
341    The output is an integer whose value indicates what character sequences the \R
342    escape sequence matches by default. A value of 0 means that \R matches any
343    Unicode line ending sequence; a value of 1 means that \R matches only CR, LF,
344    or CRLF. The default can be overridden when a pattern is compiled or matched.
345    <pre>
346    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
347  </pre>  </pre>
348  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 458  facility, see the Line 478  facility, see the
478  <a href="pcrecallout.html"><b>pcrecallout</b></a>  <a href="pcrecallout.html"><b>pcrecallout</b></a>
479  documentation.  documentation.
480  <pre>  <pre>
481      PCRE_BSR_ANYCRLF
482      PCRE_BSR_UNICODE
483    </pre>
484    These options (which are mutually exclusive) control what the \R escape
485    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
486    match any Unicode newline sequence. The default is specified when PCRE is
487    built. It can be overridden from within the pattern, or by setting an option
488    when a compiled pattern is matched.
489    <pre>
490    PCRE_CASELESS    PCRE_CASELESS
491  </pre>  </pre>
492  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 529  If this option is set, an unanchored pat Line 558  If this option is set, an unanchored pat
558  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
559  over the newline.  over the newline.
560  <pre>  <pre>
561      PCRE_JAVASCRIPT_COMPAT
562    </pre>
563    If this option is set, PCRE's behaviour is changed in some ways so that it is
564    compatible with JavaScript rather than Perl. The changes are as follows:
565    </P>
566    <P>
567    (1) A lone closing square bracket in a pattern causes a compile-time error,
568    because this is illegal in JavaScript (by default it is treated as a data
569    character). Thus, the pattern AB]CD becomes illegal when this option is set.
570    </P>
571    <P>
572    (2) At run time, a back reference to an unset subpattern group matches an empty
573    string (by default this causes the current matching alternative to fail). A
574    pattern such as (\1)(a) succeeds when this option is set (assuming it can find
575    an "a" in the subject), whereas it fails by default, for Perl compatibility.
576    <pre>
577    PCRE_MULTILINE    PCRE_MULTILINE
578  </pre>  </pre>
579  By default, PCRE treats the subject string as consisting of a single line of  By default, PCRE treats the subject string as consisting of a single line of
# Line 613  page. Line 658  page.
658    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
659  </pre>  </pre>
660  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
661  automatically checked. If an invalid UTF-8 sequence of bytes is found,  automatically checked. There is a discussion about the
662  <b>pcre_compile()</b> returns an error. If you already know that your pattern is  <a href="pcre.html#utf8strings">validity of UTF-8 strings</a>
663  valid, and you want to skip this check for performance reasons, you can set the  in the main
664  PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid  <a href="pcre.html"><b>pcre</b></a>
665  UTF-8 string as a pattern is undefined. It may cause your program to crash.  page. If an invalid UTF-8 sequence of bytes is found, <b>pcre_compile()</b>
666  Note that this option can also be passed to <b>pcre_exec()</b> and  returns an error. If you already know that your pattern is valid, and you want
667  <b>pcre_dfa_exec()</b>, to suppress the UTF-8 validity checking of subject  to skip this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK
668  strings.  option. When it is set, the effect of passing an invalid UTF-8 string as a
669    pattern is undefined. It may cause your program to crash. Note that this option
670    can also be passed to <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>, to suppress
671    the UTF-8 validity checking of subject strings.
672  </P>  </P>
673  <br><a name="SEC8" href="#TOC1">COMPILATION ERROR CODES</a><br>  <br><a name="SEC8" href="#TOC1">COMPILATION ERROR CODES</a><br>
674  <P>  <P>
# Line 641  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 649  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 658  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 678  out of use. To avoid confusion, they hav Line 726  out of use. To avoid confusion, they hav
726    46  malformed \P or \p sequence    46  malformed \P or \p sequence
727    47  unknown property name after \P or \p    47  unknown property name after \P or \p
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 \377 (not in UTF-8 mode)    51  octal value is greater than \377 (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  </PRE>    57  \g 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    </pre>
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  </P>  </P>
750  <br><a name="SEC9" href="#TOC1">STUDYING A PATTERN</a><br>  <br><a name="SEC9" href="#TOC1">STUDYING A PATTERN</a><br>
751  <P>  <P>
# Line 888  table indicating a fixed set of bytes fo Line 947  table indicating a fixed set of bytes fo
947  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
948  fourth argument should point to an <b>unsigned char *</b> variable.  fourth argument should point to an <b>unsigned char *</b> variable.
949  <pre>  <pre>
950      PCRE_INFO_HASCRORLF
951    </pre>
952    Return 1 if the pattern contains any explicit matches for CR or LF characters,
953    otherwise 0. The fourth argument should point to an <b>int</b> variable. An
954    explicit match is either a literal CR or LF character, or \r or \n.
955    <pre>
956    PCRE_INFO_JCHANGED    PCRE_INFO_JCHANGED
957  </pre>  </pre>
958  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
959  fourth argument should point to an <b>int</b> variable. The (?J) internal option  0. The fourth argument should point to an <b>int</b> variable. (?J) and
960  setting changes the local PCRE_DUPNAMES value.  (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
961  <pre>  <pre>
962    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
963  </pre>  </pre>
# Line 958  matching is used. Line 1023  matching is used.
1023  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
1024  argument should point to an <b>unsigned long int</b> variable. These option bits  argument should point to an <b>unsigned long int</b> variable. These option bits
1025  are those specified in the call to <b>pcre_compile()</b>, modified by any  are those specified in the call to <b>pcre_compile()</b>, modified by any
1026  top-level option settings within the pattern itself.  top-level option settings at the start of the pattern itself. In other words,
1027    they are the options that will be in force when matching starts. For example,
1028    if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED option, the
1029    result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED.
1030  </P>  </P>
1031  <P>  <P>
1032  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
# Line 1167  the external tables might be at a differ Line 1235  the external tables might be at a differ
1235  called. See the  called. See the
1236  <a href="pcreprecompile.html"><b>pcreprecompile</b></a>  <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
1237  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1238  </P>  <a name="execoptions"></a></P>
1239  <br><b>  <br><b>
1240  Option bits for <b>pcre_exec()</b>  Option bits for <b>pcre_exec()</b>
1241  </b><br>  </b><br>
# Line 1183  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  <pre>  <pre>
1254      PCRE_BSR_ANYCRLF
1255      PCRE_BSR_UNICODE
1256    </pre>
1257    These options (which are mutually exclusive) control what the \R 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    <pre>
1262    PCRE_NEWLINE_CR    PCRE_NEWLINE_CR
1263    PCRE_NEWLINE_LF    PCRE_NEWLINE_LF
1264    PCRE_NEWLINE_CRLF    PCRE_NEWLINE_CRLF
# Line 1194  the pattern was compiled. For details, s Line 1270  the pattern was compiled. For details, s
1270  <b>pcre_compile()</b> above. During matching, the newline choice affects the  <b>pcre_compile()</b> 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, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is  pattern.
1274  set, and a match attempt fails when the current position is at a CRLF sequence,  </P>
1275  the match position is advanced by two characters instead of one, in other  <P>
1276  words, to after the CRLF.  When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a
1277    match attempt for an unanchored pattern fails when the current position is at a
1278    CRLF sequence, and the pattern contains no explicit matches for CR or LF
1279    characters, the match position is advanced by two characters instead of one, in
1280    other words, to after the CRLF.
1281    </P>
1282    <P>
1283    The above rule is a compromise that makes the most common cases work as
1284    expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
1285    set), it does not match the string "\r\nA" because, after failing at the
1286    start, it skips both the CR and the LF before retrying. However, the pattern
1287    [\r\n]A does match that string, because it contains an explicit CR or LF
1288    reference, and so advances only by one character after the first failure.
1289    </P>
1290    <P>
1291    An explicit match for CR of LF is either a literal appearance of one of those
1292    characters, or one of the \r or \n escape sequences. Implicit matches such as
1293    [^X] do not count, nor does \s (which includes CR and LF in the characters
1294    that it matches).
1295    </P>
1296    <P>
1297    Notwithstanding the above, anomalous effects may still occur when CRLF is a
1298    valid newline sequence and explicit \r or \n escapes appear in the pattern.
1299  <pre>  <pre>
1300    PCRE_NOTBOL    PCRE_NOTBOL
1301  </pre>  </pre>
# Line 1241  code that demonstrates how to do this in Line 1339  code that demonstrates how to do this in
1339  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
1340  string is automatically checked when <b>pcre_exec()</b> is subsequently called.  string is automatically checked when <b>pcre_exec()</b> is subsequently called.
1341  The value of <i>startoffset</i> is also checked to ensure that it points to the  The value of <i>startoffset</i> is also checked to ensure that it points to the
1342  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
1343  <b>pcre_exec()</b> returns the error PCRE_ERROR_BADUTF8. If <i>startoffset</i>  strings in the
1344  contains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.  <a href="pcre.html#utf8strings">section on UTF-8 support</a>
1345    in the main
1346    <a href="pcre.html"><b>pcre</b></a>
1347    page. If an invalid UTF-8 sequence of bytes is found, <b>pcre_exec()</b> returns
1348    the error PCRE_ERROR_BADUTF8. If <i>startoffset</i> contains an invalid value,
1349    PCRE_ERROR_BADUTF8_OFFSET is returned.
1350  </P>  </P>
1351  <P>  <P>
1352  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
# Line 1481  The internal recursion limit, as specifi Line 1584  The internal recursion limit, as specifi
1584  field in a <b>pcre_extra</b> structure (or defaulted) was reached. See the  field in a <b>pcre_extra</b> structure (or defaulted) was reached. See the
1585  description above.  description above.
1586  <pre>  <pre>
   PCRE_ERROR_NULLWSLIMIT    (-22)  
 </pre>  
 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.  
 <pre>  
1587    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
1588  </pre>  </pre>
1589  An invalid combination of PCRE_NEWLINE_<i>xxx</i> options was given.  An invalid combination of PCRE_NEWLINE_<i>xxx</i> options was given.
1590  </P>  </P>
1591  <P>  <P>
1592  Error numbers -16 to -20 are not used by <b>pcre_exec()</b>.  Error numbers -16 to -20 and -22 are not used by <b>pcre_exec()</b>.
1593  </P>  </P>
1594  <br><a name="SEC15" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>  <br><a name="SEC15" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>
1595  <P>  <P>
# Line 1655  are not required to be unique. Normally, Line 1750  are not required to be unique. Normally,
1750  that in any one match, only one of the named subpatterns participates. An  that in any one match, only one of the named subpatterns participates. An
1751  example is shown in the  example is shown in the
1752  <a href="pcrepattern.html"><b>pcrepattern</b></a>  <a href="pcrepattern.html"><b>pcrepattern</b></a>
1753  documentation. When duplicates are present, <b>pcre_copy_named_substring()</b>  documentation.
1754  and <b>pcre_get_named_substring()</b> return the first substring corresponding  </P>
1755  to the given name that is set. If none are set, an empty string is returned.  <P>
1756  The <b>pcre_get_stringnumber()</b> function returns one of the numbers that are  When duplicates are present, <b>pcre_copy_named_substring()</b> and
1757  associated with the name, but it is not defined which it is.  <b>pcre_get_named_substring()</b> return the first substring corresponding to
1758  <br>  the given name that is set. If none are set, PCRE_ERROR_NOSUBSTRING (-7) is
1759  <br>  returned; no data is returned. The <b>pcre_get_stringnumber()</b> function
1760    returns one of the numbers that are associated with the name, but it is not
1761    defined which it is.
1762    </P>
1763    <P>
1764  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,
1765  you must use the <b>pcre_get_stringtable_entries()</b> function. The first  you must use the <b>pcre_get_stringtable_entries()</b> function. The first
1766  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 1873  Cambridge CB2 3QH, England. Line 1972  Cambridge CB2 3QH, England.
1972  </P>  </P>
1973  <br><a name="SEC22" href="#TOC1">REVISION</a><br>  <br><a name="SEC22" href="#TOC1">REVISION</a><br>
1974  <P>  <P>
1975  Last updated: 04 June 2007  Last updated: 12 April 2008
1976  <br>  <br>
1977  Copyright &copy; 1997-2007 University of Cambridge.  Copyright &copy; 1997-2008 University of Cambridge.
1978  <br>  <br>
1979  <p>  <p>
1980  Return to the <a href="index.html">PCRE index page</a>.  Return to the <a href="index.html">PCRE index page</a>.

Legend:
Removed from v.172  
changed lines
  Added in v.345

  ViewVC Help
Powered by ViewVC 1.1.5