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revision 510 by ph10, Sat Mar 27 17:45:29 2010 UTC revision 553 by ph10, Fri Oct 22 15:57:50 2010 UTC
# Line 132  an application that uses PCRE. The heade Line 132  an application that uses PCRE. The heade
132  and PCRE_MINOR to contain the major and minor release numbers for the library.  and PCRE_MINOR to contain the major and minor release numbers for the library.
133  Applications can use these to include support for different releases of PCRE.  Applications can use these to include support for different releases of PCRE.
134  .P  .P
135    In a Windows environment, if you want to statically link an application program
136    against a non-dll \fBpcre.a\fP file, you must define PCRE_STATIC before
137    including \fBpcre.h\fP or \fBpcrecpp.h\fP, because otherwise the
138    \fBpcre_malloc()\fP and \fBpcre_free()\fP exported functions will be declared
139    \fB__declspec(dllimport)\fP, with unwanted results.
140    .P
141  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,
142  and \fBpcre_exec()\fP are used for compiling and matching regular expressions  and \fBpcre_exec()\fP are used for compiling and matching regular expressions
143  in a Perl-compatible manner. A sample program that demonstrates the simplest  in a Perl-compatible manner. A sample program that demonstrates the simplest
# Line 553  set, any backslash in a pattern that is Line 559  set, any backslash in a pattern that is
559  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
560  expansion. By default, as in Perl, a backslash followed by a letter with no  expansion. By default, as in Perl, a backslash followed by a letter with no
561  special meaning is treated as a literal. (Perl can, however, be persuaded to  special meaning is treated as a literal. (Perl can, however, be persuaded to
562  give a warning for this.) There are at present no other features controlled by  give an error for this, by running it with the -w option.) There are at present
563  this option. It can also be set by a (?X) option setting within a pattern.  no other features controlled by this option. It can also be set by a (?X)
564    option setting within a pattern.
565  .sp  .sp
566    PCRE_FIRSTLINE    PCRE_FIRSTLINE
567  .sp  .sp
# Line 635  were followed by ?: but named parenthese Line 642  were followed by ?: but named parenthese
642  they acquire numbers in the usual way). There is no equivalent of this option  they acquire numbers in the usual way). There is no equivalent of this option
643  in Perl.  in Perl.
644  .sp  .sp
645      PCRE_UCP
646    .sp
647    This option changes the way PCRE processes \eb, \ed, \es, \ew, and some of the
648    POSIX character classes. By default, only ASCII characters are recognized, but
649    if PCRE_UCP is set, Unicode properties are used instead to classify characters.
650    More details are given in the section on
651    .\" HTML <a href="pcre.html#genericchartypes">
652    .\" </a>
653    generic character types
654    .\"
655    in the
656    .\" HREF
657    \fBpcrepattern\fP
658    .\"
659    page. If you set PCRE_UCP, matching one of the items it affects takes much
660    longer. The option is available only if PCRE has been compiled with Unicode
661    property support.
662    .sp
663    PCRE_UNGREEDY    PCRE_UNGREEDY
664  .sp  .sp
665  This option inverts the "greediness" of the quantifiers so that they are not  This option inverts the "greediness" of the quantifiers so that they are not
# Line 740  out of use. To avoid confusion, they hav Line 765  out of use. To avoid confusion, they hav
765    50  [this code is not in use]    50  [this code is not in use]
766    51  octal value is greater than \e377 (not in UTF-8 mode)    51  octal value is greater than \e377 (not in UTF-8 mode)
767    52  internal error: overran compiling workspace    52  internal error: overran compiling workspace
768    53  internal error: previously-checked referenced subpattern not found    53  internal error: previously-checked referenced subpattern
769            not found
770    54  DEFINE group contains more than one branch    54  DEFINE group contains more than one branch
771    55  repeating a DEFINE group is not allowed    55  repeating a DEFINE group is not allowed
772    56  inconsistent NEWLINE options    56  inconsistent NEWLINE options
# Line 753  out of use. To avoid confusion, they hav Line 779  out of use. To avoid confusion, they hav
779    62  subpattern name expected    62  subpattern name expected
780    63  digit expected after (?+    63  digit expected after (?+
781    64  ] is an invalid data character in JavaScript compatibility mode    64  ] is an invalid data character in JavaScript compatibility mode
782    65  different names for subpatterns of the same number are not allowed    65  different names for subpatterns of the same number are
783            not allowed
784    66  (*MARK) must have an argument    66  (*MARK) must have an argument
785      67  this version of PCRE is not compiled with PCRE_UCP support
786  .sp  .sp
787  The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may  The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
788  be used if the limits were changed when PCRE was built.  be used if the limits were changed when PCRE was built.
# Line 820  Studying a pattern is also useful for no Line 848  Studying a pattern is also useful for no
848  single fixed starting character. A bitmap of possible starting bytes is  single fixed starting character. A bitmap of possible starting bytes is
849  created. This speeds up finding a position in the subject at which to start  created. This speeds up finding a position in the subject at which to start
850  matching.  matching.
851    .P
852    The two optimizations just described can be disabled by setting the
853    PCRE_NO_START_OPTIMIZE option when calling \fBpcre_exec()\fP or
854    \fBpcre_dfa_exec()\fP. You might want to do this if your pattern contains
855    callouts, or make use of (*MARK), and you make use of these in cases where
856    matching fails. See the discussion of PCRE_NO_START_OPTIMIZE
857    .\" HTML <a href="#execoptions">
858    .\" </a>
859    below.
860    .\"
861  .  .
862  .  .
863  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
# Line 829  matching. Line 867  matching.
867  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters,
868  digits, or whatever, by reference to a set of tables, indexed by character  digits, or whatever, by reference to a set of tables, indexed by character
869  value. When running in UTF-8 mode, this applies only to characters with codes  value. When running in UTF-8 mode, this applies only to characters with codes
870  less than 128. Higher-valued codes never match escapes such as \ew or \ed, but  less than 128. By default, higher-valued codes never match escapes such as \ew
871  can be tested with \ep if PCRE is built with Unicode character property  or \ed, but they can be tested with \ep if PCRE is built with Unicode character
872  support. The use of locales with Unicode is discouraged. If you are handling  property support. Alternatively, the PCRE_UCP option can be set at compile
873  characters with codes greater than 128, you should either use UTF-8 and  time; this causes \ew and friends to use Unicode property support instead of
874  Unicode, or use locales, but not try to mix the two.  built-in tables. The use of locales with Unicode is discouraged. If you are
875    handling characters with codes greater than 128, you should either use UTF-8
876    and Unicode, or use locales, but not try to mix the two.
877  .P  .P
878  PCRE contains an internal set of tables that are used when the final argument  PCRE contains an internal set of tables that are used when the final argument
879  of \fBpcre_compile()\fP is NULL. These are sufficient for many applications.  of \fBpcre_compile()\fP is NULL. These are sufficient for many applications.
# Line 1212  fields (not necessarily in this order): Line 1252  fields (not necessarily in this order):
1252    unsigned long int \fImatch_limit_recursion\fP;    unsigned long int \fImatch_limit_recursion\fP;
1253    void *\fIcallout_data\fP;    void *\fIcallout_data\fP;
1254    const unsigned char *\fItables\fP;    const unsigned char *\fItables\fP;
1255    unsigned char **\fImark\fP;    unsigned char **\fImark\fP;
1256  .sp  .sp
1257  The \fIflags\fP field is a bitmap that specifies which of the other fields  The \fIflags\fP field is a bitmap that specifies which of the other fields
1258  are set. The flag bits are:  are set. The flag bits are:
# Line 1222  are set. The flag bits are: Line 1262  are set. The flag bits are:
1262    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1263    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1264    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1265    PCRE_EXTRA_MARK    PCRE_EXTRA_MARK
1266  .sp  .sp
1267  Other flag bits should be set to zero. The \fIstudy_data\fP field is set in the  Other flag bits should be set to zero. The \fIstudy_data\fP field is set in the
1268  \fBpcre_extra\fP block that is returned by \fBpcre_study()\fP, together with  \fBpcre_extra\fP block that is returned by \fBpcre_study()\fP, together with
# Line 1287  called. See the Line 1327  called. See the
1327  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1328  .P  .P
1329  If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must  If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1330  be set to point to a \fBchar *\fP variable. If the pattern contains any  be set to point to a \fBchar *\fP variable. If the pattern contains any
1331  backtracking control verbs such as (*MARK:NAME), and the execution ends up with  backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1332  a name to pass back, a pointer to the name string (zero terminated) is placed  a name to pass back, a pointer to the name string (zero terminated) is placed
1333  in the variable pointed to by the \fImark\fP field. The names are within the  in the variable pointed to by the \fImark\fP field. The names are within the
# Line 1415  sample program. Line 1455  sample program.
1455    PCRE_NO_START_OPTIMIZE    PCRE_NO_START_OPTIMIZE
1456  .sp  .sp
1457  There are a number of optimizations that \fBpcre_exec()\fP uses at the start of  There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1458  a match, in order to speed up the process. For example, if it is known that a  a match, in order to speed up the process. For example, if it is known that an
1459  match must start with a specific character, it searches the subject for that  unanchored match must start with a specific character, it searches the subject
1460  character, and fails immediately if it cannot find it, without actually running  for that character, and fails immediately if it cannot find it, without
1461  the main matching function. When callouts are in use, these optimizations can  actually running the main matching function. This means that a special item
1462  cause them to be skipped. This option disables the "start-up" optimizations,  such as (*COMMIT) at the start of a pattern is not considered until after a
1463  causing performance to suffer, but ensuring that the callouts do occur.  suitable starting point for the match has been found. When callouts or (*MARK)
1464    items are in use, these "start-up" optimizations can cause them to be skipped
1465    if the pattern is never actually used. The start-up optimizations are in effect
1466    a pre-scan of the subject that takes place before the pattern is run.
1467    .P
1468    The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
1469    causing performance to suffer, but ensuring that in cases where the result is
1470    "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
1471    are considered at every possible starting position in the subject string.
1472    Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
1473    Consider the pattern
1474    .sp
1475      (*COMMIT)ABC
1476    .sp
1477    When this is compiled, PCRE records the fact that a match must start with the
1478    character "A". Suppose the subject string is "DEFABC". The start-up
1479    optimization scans along the subject, finds "A" and runs the first match
1480    attempt from there. The (*COMMIT) item means that the pattern must match the
1481    current starting position, which in this case, it does. However, if the same
1482    match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
1483    subject string does not happen. The first match attempt is run starting from
1484    "D" and when this fails, (*COMMIT) prevents any further matches being tried, so
1485    the overall result is "no match". If the pattern is studied, more start-up
1486    optimizations may be used. For example, a minimum length for the subject may be
1487    recorded. Consider the pattern
1488    .sp
1489      (*MARK:A)(X|Y)
1490    .sp
1491    The minimum length for a match is one character. If the subject is "ABC", there
1492    will be attempts to match "ABC", "BC", "C", and then finally an empty string.
1493    If the pattern is studied, the final attempt does not take place, because PCRE
1494    knows that the subject is too short, and so the (*MARK) is never encountered.
1495    In this case, studying the pattern does not affect the overall match result,
1496    which is still "no match", but it does affect the auxiliary information that is
1497    returned.
1498  .sp  .sp
1499    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1500  .sp  .sp
# Line 1458  These options turn on the partial matchi Line 1532  These options turn on the partial matchi
1532  compatibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial match  compatibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial match
1533  occurs if the end of the subject string is reached successfully, but there are  occurs if the end of the subject string is reached successfully, but there are
1534  not enough subject characters to complete the match. If this happens when  not enough subject characters to complete the match. If this happens when
1535  PCRE_PARTIAL_HARD is set, \fBpcre_exec()\fP immediately returns  PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set, matching continues by
1536  PCRE_ERROR_PARTIAL. Otherwise, if PCRE_PARTIAL_SOFT is set, matching continues  testing any remaining alternatives. Only if no complete match can be found is
1537  by testing any other alternatives. Only if they all fail is PCRE_ERROR_PARTIAL  PCRE_ERROR_PARTIAL returned instead of PCRE_ERROR_NOMATCH. In other words,
1538  returned (instead of PCRE_ERROR_NOMATCH). The portion of the string that  PCRE_PARTIAL_SOFT says that the caller is prepared to handle a partial match,
1539  was inspected when the partial match was found is set as the first matching  but only if no complete match can be found.
1540  string. There is a more detailed discussion in the  .P
1541    If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
1542    partial match is found, \fBpcre_exec()\fP immediately returns
1543    PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
1544    when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
1545    important that an alternative complete match.
1546    .P
1547    In both cases, the portion of the string that was inspected when the partial
1548    match was found is set as the first matching string. There is a more detailed
1549    discussion of partial and multi-segment matching, with examples, in the
1550  .\" HREF  .\" HREF
1551  \fBpcrepartial\fP  \fBpcrepartial\fP
1552  .\"  .\"
# Line 1615  If a pattern contains back references, b Line 1698  If a pattern contains back references, b
1698  gets a block of memory at the start of matching to use for this purpose. If the  gets a block of memory at the start of matching to use for this purpose. If the
1699  call via \fBpcre_malloc()\fP fails, this error is given. The memory is  call via \fBpcre_malloc()\fP fails, this error is given. The memory is
1700  automatically freed at the end of matching.  automatically freed at the end of matching.
1701    .P
1702    This error is also given if \fBpcre_stack_malloc()\fP fails in
1703    \fBpcre_exec()\fP. This can happen only when PCRE has been compiled with
1704    \fB--disable-stack-for-recursion\fP.
1705  .sp  .sp
1706    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1707  .sp  .sp
# Line 1963  Here is an example of a simple call to \ Line 2050  Here is an example of a simple call to \
2050  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
2051  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,
2052  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
2053  PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST,  PCRE_NO_UTF8_CHECK, PCRE_BSR_ANYCRLF, PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE,
2054  and PCRE_DFA_RESTART. All but the last four of these are exactly the same as  PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART.
2055  for \fBpcre_exec()\fP, so their description is not repeated here.  All but the last four of these are exactly the same as for \fBpcre_exec()\fP,
2056    so their description is not repeated here.
2057  .sp  .sp
2058    PCRE_PARTIAL_HARD    PCRE_PARTIAL_HARD
2059    PCRE_PARTIAL_SOFT    PCRE_PARTIAL_SOFT
# Line 1980  is converted into PCRE_ERROR_PARTIAL if Line 2068  is converted into PCRE_ERROR_PARTIAL if
2068  there have been no complete matches, but there is still at least one matching  there have been no complete matches, but there is still at least one matching
2069  possibility. The portion of the string that was inspected when the longest  possibility. The portion of the string that was inspected when the longest
2070  partial match was found is set as the first matching string in both cases.  partial match was found is set as the first matching string in both cases.
2071    There is a more detailed discussion of partial and multi-segment matching, with
2072    examples, in the
2073    .\" HREF
2074    \fBpcrepartial\fP
2075    .\"
2076    documentation.
2077  .sp  .sp
2078    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
2079  .sp  .sp
# Line 2099  Cambridge CB2 3QH, England. Line 2193  Cambridge CB2 3QH, England.
2193  .rs  .rs
2194  .sp  .sp
2195  .nf  .nf
2196  Last updated: 26 March 2010  Last updated: 22 October 2010
2197  Copyright (c) 1997-2010 University of Cambridge.  Copyright (c) 1997-2010 University of Cambridge.
2198  .fi  .fi

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