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revision 461 by ph10, Mon Oct 5 10:59:35 2009 UTC revision 576 by ph10, Sun Nov 21 18:45:10 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 422  within the pattern (see the detailed des Line 428  within the pattern (see the detailed des
428  documentation). For those options that can be different in different parts of  documentation). For those options that can be different in different parts of
429  the pattern, the contents of the \fIoptions\fP argument specifies their  the pattern, the contents of the \fIoptions\fP argument specifies their
430  settings at the start of compilation and execution. The PCRE_ANCHORED,  settings at the start of compilation and execution. The PCRE_ANCHORED,
431  PCRE_BSR_\fIxxx\fP, and PCRE_NEWLINE_\fIxxx\fP options can be set at the time  PCRE_BSR_\fIxxx\fP, PCRE_NEWLINE_\fIxxx\fP, PCRE_NO_UTF8_CHECK, and
432  of matching as well as at compile time.  PCRE_NO_START_OPT options can be set at the time of matching as well as at
433    compile time.
434  .P  .P
435  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
436  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
437  NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual  NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual
438  error message. This is a static string that is part of the library. You must  error message. This is a static string that is part of the library. You must
439  not try to free it. The byte offset from the start of the pattern to the  not try to free it. The offset from the start of the pattern to the byte that
440  character that was being processed when the error was discovered is placed in  was being processed when the error was discovered is placed in the variable
441  the variable pointed to by \fIerroffset\fP, which must not be NULL. If it is,  pointed to by \fIerroffset\fP, which must not be NULL. If it is, an immediate
442  an immediate error is given. Some errors are not detected until checks are  error is given. Some errors are not detected until checks are carried out when
443  carried out when the whole pattern has been scanned; in this case the offset is  the whole pattern has been scanned; in this case the offset is set to the end
444  set to the end of the pattern.  of the pattern.
445    .P
446    Note that the offset is in bytes, not characters, even in UTF-8 mode. It may
447    point into the middle of a UTF-8 character (for example, when
448    PCRE_ERROR_BADUTF8 is returned for an invalid UTF-8 string).
449  .P  .P
450  If \fBpcre_compile2()\fP is used instead of \fBpcre_compile()\fP, and the  If \fBpcre_compile2()\fP is used instead of \fBpcre_compile()\fP, and the
451  \fIerrorcodeptr\fP argument is not NULL, a non-zero error code number is  \fIerrorcodeptr\fP argument is not NULL, a non-zero error code number is
# Line 513  pattern. Line 524  pattern.
524  .sp  .sp
525    PCRE_DOTALL    PCRE_DOTALL
526  .sp  .sp
527  If this bit is set, a dot metacharater in the pattern matches all characters,  If this bit is set, a dot metacharacter in the pattern matches a character of
528  including those that indicate newline. Without it, a dot does not match when  any value, including one that indicates a newline. However, it only ever
529  the current position is at a newline. This option is equivalent to Perl's /s  matches one character, even if newlines are coded as CRLF. Without this option,
530  option, and it can be changed within a pattern by a (?s) option setting. A  a dot does not match when the current position is at a newline. This option is
531  negative class such as [^a] always matches newline characters, independent of  equivalent to Perl's /s option, and it can be changed within a pattern by a
532  the setting of this option.  (?s) option setting. A negative class such as [^a] always matches newline
533    characters, independent of the setting of this option.
534  .sp  .sp
535    PCRE_DUPNAMES    PCRE_DUPNAMES
536  .sp  .sp
# Line 540  unescaped # outside a character class an Line 552  unescaped # outside a character class an
552  ignored. This is equivalent to Perl's /x option, and it can be changed within a  ignored. This is equivalent to Perl's /x option, and it can be changed within a
553  pattern by a (?x) option setting.  pattern by a (?x) option setting.
554  .P  .P
555    Which characters are interpreted as newlines
556    is controlled by the options passed to \fBpcre_compile()\fP or by a special
557    sequence at the start of the pattern, as described in the section entitled
558    .\" HTML <a href="pcrepattern.html#newlines">
559    .\" </a>
560    "Newline conventions"
561    .\"
562    in the \fBpcrepattern\fP documentation. Note that the end of this type of
563    comment is a literal newline sequence in the pattern; escape sequences that
564    happen to represent a newline do not count.
565    .P
566  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
567  Note, however, that this applies only to data characters. Whitespace characters  Note, however, that this applies only to data characters. Whitespace characters
568  may never appear within special character sequences in a pattern, for example  may never appear within special character sequences in a pattern, for example
569  within the sequence (?( which introduces a conditional subpattern.  within the sequence (?( that introduces a conditional subpattern.
570  .sp  .sp
571    PCRE_EXTRA    PCRE_EXTRA
572  .sp  .sp
# Line 553  set, any backslash in a pattern that is Line 576  set, any backslash in a pattern that is
576  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
577  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
578  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
579  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
580  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)
581    option setting within a pattern.
582  .sp  .sp
583    PCRE_FIRSTLINE    PCRE_FIRSTLINE
584  .sp  .sp
# Line 617  option, the combination may or may not b Line 641  option, the combination may or may not b
641  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
642  other combinations may yield unused numbers and cause an error.  other combinations may yield unused numbers and cause an error.
643  .P  .P
644  The only time that a line break is specially recognized when compiling a  The only time that a line break in a pattern is specially recognized when
645  pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character  compiling is when PCRE_EXTENDED is set. CR and LF are whitespace characters,
646  class is encountered. This indicates a comment that lasts until after the next  and so are ignored in this mode. Also, an unescaped # outside a character class
647  line break sequence. In other circumstances, line break sequences are treated  indicates a comment that lasts until after the next line break sequence. In
648  as literal data, except that in PCRE_EXTENDED mode, both CR and LF are treated  other circumstances, line break sequences in patterns are treated as literal
649  as whitespace characters and are therefore ignored.  data.
650  .P  .P
651  The newline option that is set at compile time becomes the default that is used  The newline option that is set at compile time becomes the default that is used
652  for \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, but it can be overridden.  for \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, but it can be overridden.
# Line 635  were followed by ?: but named parenthese Line 659  were followed by ?: but named parenthese
659  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
660  in Perl.  in Perl.
661  .sp  .sp
662      NO_START_OPTIMIZE
663    .sp
664    This is an option that acts at matching time; that is, it is really an option
665    for \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. If it is set at compile time,
666    it is remembered with the compiled pattern and assumed at matching time. For
667    details see the discussion of PCRE_NO_START_OPTIMIZE
668    .\" HTML <a href="#execoptions">
669    .\" </a>
670    below.
671    .\"
672    .sp
673      PCRE_UCP
674    .sp
675    This option changes the way PCRE processes \eB, \eb, \eD, \ed, \eS, \es, \eW,
676    \ew, and some of the POSIX character classes. By default, only ASCII characters
677    are recognized, but if PCRE_UCP is set, Unicode properties are used instead to
678    classify characters. More details are given in the section on
679    .\" HTML <a href="pcre.html#genericchartypes">
680    .\" </a>
681    generic character types
682    .\"
683    in the
684    .\" HREF
685    \fBpcrepattern\fP
686    .\"
687    page. If you set PCRE_UCP, matching one of the items it affects takes much
688    longer. The option is available only if PCRE has been compiled with Unicode
689    property support.
690    .sp
691    PCRE_UNGREEDY    PCRE_UNGREEDY
692  .sp  .sp
693  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 793  out of use. To avoid confusion, they hav
793    50  [this code is not in use]    50  [this code is not in use]
794    51  octal value is greater than \e377 (not in UTF-8 mode)    51  octal value is greater than \e377 (not in UTF-8 mode)
795    52  internal error: overran compiling workspace    52  internal error: overran compiling workspace
796    53  internal error: previously-checked referenced subpattern not found    53  internal error: previously-checked referenced subpattern
797            not found
798    54  DEFINE group contains more than one branch    54  DEFINE group contains more than one branch
799    55  repeating a DEFINE group is not allowed    55  repeating a DEFINE group is not allowed
800    56  inconsistent NEWLINE options    56  inconsistent NEWLINE options
801    57  \eg is not followed by a braced, angle-bracketed, or quoted    57  \eg is not followed by a braced, angle-bracketed, or quoted
802          name/number or by a plain number          name/number or by a plain number
803    58  a numbered reference must not be zero    58  a numbered reference must not be zero
804    59  (*VERB) with an argument is not supported    59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
805    60  (*VERB) not recognized    60  (*VERB) not recognized
806    61  number is too big    61  number is too big
807    62  subpattern name expected    62  subpattern name expected
808    63  digit expected after (?+    63  digit expected after (?+
809    64  ] is an invalid data character in JavaScript compatibility mode    64  ] is an invalid data character in JavaScript compatibility mode
810      65  different names for subpatterns of the same number are
811            not allowed
812      66  (*MARK) must have an argument
813      67  this version of PCRE is not compiled with PCRE_UCP support
814  .sp  .sp
815  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
816  be used if the limits were changed when PCRE was built.  be used if the limits were changed when PCRE was built.
# Line 818  Studying a pattern is also useful for no Line 876  Studying a pattern is also useful for no
876  single fixed starting character. A bitmap of possible starting bytes is  single fixed starting character. A bitmap of possible starting bytes is
877  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
878  matching.  matching.
879    .P
880    The two optimizations just described can be disabled by setting the
881    PCRE_NO_START_OPTIMIZE option when calling \fBpcre_exec()\fP or
882    \fBpcre_dfa_exec()\fP. You might want to do this if your pattern contains
883    callouts or (*MARK), and you want to make use of these facilities in cases
884    where matching fails. See the discussion of PCRE_NO_START_OPTIMIZE
885    .\" HTML <a href="#execoptions">
886    .\" </a>
887    below.
888    .\"
889  .  .
890  .  .
891  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
# Line 827  matching. Line 895  matching.
895  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters,
896  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
897  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
898  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
899  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
900  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
901  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
902  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
903    handling characters with codes greater than 128, you should either use UTF-8
904    and Unicode, or use locales, but not try to mix the two.
905  .P  .P
906  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
907  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 1210  fields (not necessarily in this order): Line 1280  fields (not necessarily in this order):
1280    unsigned long int \fImatch_limit_recursion\fP;    unsigned long int \fImatch_limit_recursion\fP;
1281    void *\fIcallout_data\fP;    void *\fIcallout_data\fP;
1282    const unsigned char *\fItables\fP;    const unsigned char *\fItables\fP;
1283      unsigned char **\fImark\fP;
1284  .sp  .sp
1285  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
1286  are set. The flag bits are:  are set. The flag bits are:
# Line 1219  are set. The flag bits are: Line 1290  are set. The flag bits are:
1290    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1291    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1292    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1293      PCRE_EXTRA_MARK
1294  .sp  .sp
1295  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
1296  \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 1281  called. See the Line 1353  called. See the
1353  \fBpcreprecompile\fP  \fBpcreprecompile\fP
1354  .\"  .\"
1355  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1356    .P
1357    If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1358    be set to point to a \fBchar *\fP variable. If the pattern contains any
1359    backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1360    a name to pass back, a pointer to the name string (zero terminated) is placed
1361    in the variable pointed to by the \fImark\fP field. The names are within the
1362    compiled pattern; if you wish to retain such a name you must copy it before
1363    freeing the memory of a compiled pattern. If there is no name to pass back, the
1364    variable pointed to by the \fImark\fP field set to NULL. For details of the
1365    backtracking control verbs, see the section entitled
1366    .\" HTML <a href="pcrepattern#backtrackcontrol">
1367    .\" </a>
1368    "Backtracking control"
1369    .\"
1370    in the
1371    .\" HREF
1372    \fBpcrepattern\fP
1373    .\"
1374    documentation.
1375    .
1376  .  .
1377  .\" HTML <a name="execoptions"></a>  .\" HTML <a name="execoptions"></a>
1378  .SS "Option bits for \fBpcre_exec()\fP"  .SS "Option bits for \fBpcre_exec()\fP"
# Line 1386  the Line 1478  the
1478  .\" HREF  .\" HREF
1479  \fBpcredemo\fP  \fBpcredemo\fP
1480  .\"  .\"
1481  sample program.  sample program. In the most general case, you have to check to see if the
1482    newline convention recognizes CRLF as a newline, and if so, and the current
1483    character is CR followed by LF, advance the starting offset by two characters
1484    instead of one.
1485  .sp  .sp
1486    PCRE_NO_START_OPTIMIZE    PCRE_NO_START_OPTIMIZE
1487  .sp  .sp
1488  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
1489  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
1490  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
1491  character, and fails immediately if it cannot find it, without actually running  for that character, and fails immediately if it cannot find it, without
1492  the main matching function. When callouts are in use, these optimizations can  actually running the main matching function. This means that a special item
1493  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
1494  causing performance to suffer, but ensuring that the callouts do occur.  suitable starting point for the match has been found. When callouts or (*MARK)
1495    items are in use, these "start-up" optimizations can cause them to be skipped
1496    if the pattern is never actually used. The start-up optimizations are in effect
1497    a pre-scan of the subject that takes place before the pattern is run.
1498    .P
1499    The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
1500    causing performance to suffer, but ensuring that in cases where the result is
1501    "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
1502    are considered at every possible starting position in the subject string. If
1503    PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
1504    time.
1505    .P
1506    Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
1507    Consider the pattern
1508    .sp
1509      (*COMMIT)ABC
1510    .sp
1511    When this is compiled, PCRE records the fact that a match must start with the
1512    character "A". Suppose the subject string is "DEFABC". The start-up
1513    optimization scans along the subject, finds "A" and runs the first match
1514    attempt from there. The (*COMMIT) item means that the pattern must match the
1515    current starting position, which in this case, it does. However, if the same
1516    match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
1517    subject string does not happen. The first match attempt is run starting from
1518    "D" and when this fails, (*COMMIT) prevents any further matches being tried, so
1519    the overall result is "no match". If the pattern is studied, more start-up
1520    optimizations may be used. For example, a minimum length for the subject may be
1521    recorded. Consider the pattern
1522    .sp
1523      (*MARK:A)(X|Y)
1524    .sp
1525    The minimum length for a match is one character. If the subject is "ABC", there
1526    will be attempts to match "ABC", "BC", "C", and then finally an empty string.
1527    If the pattern is studied, the final attempt does not take place, because PCRE
1528    knows that the subject is too short, and so the (*MARK) is never encountered.
1529    In this case, studying the pattern does not affect the overall match result,
1530    which is still "no match", but it does affect the auxiliary information that is
1531    returned.
1532  .sp  .sp
1533    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1534  .sp  .sp
# Line 1414  in the main Line 1546  in the main
1546  \fBpcre\fP  \fBpcre\fP
1547  .\"  .\"
1548  page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns  page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns
1549  the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP contains an invalid value,  the error PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is
1550  PCRE_ERROR_BADUTF8_OFFSET is returned.  a truncated UTF-8 character at the end of the subject, PCRE_ERROR_SHORTUTF8. If
1551    \fIstartoffset\fP contains a value that does not point to the start of a UTF-8
1552    character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
1553    returned.
1554  .P  .P
1555  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
1556  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
1557  calling \fBpcre_exec()\fP. You might want to do this for the second and  calling \fBpcre_exec()\fP. You might want to do this for the second and
1558  subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find  subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find
1559  all the matches in a single subject string. However, you should be sure that  all the matches in a single subject string. However, you should be sure that
1560  the value of \fIstartoffset\fP points to the start of a UTF-8 character. When  the value of \fIstartoffset\fP points to the start of a UTF-8 character (or the
1561  PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid UTF-8 string as a  end of the subject). When PCRE_NO_UTF8_CHECK is set, the effect of passing an
1562  subject, or a value of \fIstartoffset\fP that does not point to the start of a  invalid UTF-8 string as a subject or an invalid value of \fIstartoffset\fP is
1563  UTF-8 character, is undefined. Your program may crash.  undefined. Your program may crash.
1564  .sp  .sp
1565    PCRE_PARTIAL_HARD    PCRE_PARTIAL_HARD
1566    PCRE_PARTIAL_SOFT    PCRE_PARTIAL_SOFT
# Line 1434  These options turn on the partial matchi Line 1569  These options turn on the partial matchi
1569  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
1570  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
1571  not enough subject characters to complete the match. If this happens when  not enough subject characters to complete the match. If this happens when
1572  PCRE_PARTIAL_HARD is set, \fBpcre_exec()\fP immediately returns  PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set, matching continues by
1573  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
1574  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,
1575  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,
1576  was inspected when the partial match was found is set as the first matching  but only if no complete match can be found.
1577  string. There is a more detailed discussion in the  .P
1578    If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
1579    partial match is found, \fBpcre_exec()\fP immediately returns
1580    PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
1581    when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
1582    important that an alternative complete match.
1583    .P
1584    In both cases, the portion of the string that was inspected when the partial
1585    match was found is set as the first matching string. There is a more detailed
1586    discussion of partial and multi-segment matching, with examples, in the
1587  .\" HREF  .\" HREF
1588  \fBpcrepartial\fP  \fBpcrepartial\fP
1589  .\"  .\"
1590  documentation.  documentation.
1591  .  .
1592    .
1593  .SS "The string to be matched by \fBpcre_exec()\fP"  .SS "The string to be matched by \fBpcre_exec()\fP"
1594  .rs  .rs
1595  .sp  .sp
1596  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
1597  \fIsubject\fP, a length (in bytes) in \fIlength\fP, and a starting byte offset  \fIsubject\fP, a length (in bytes) in \fIlength\fP, and a starting byte offset
1598  in \fIstartoffset\fP. In UTF-8 mode, the byte offset must point to the start of  in \fIstartoffset\fP. If this is negative or greater than the length of the
1599  a UTF-8 character. Unlike the pattern string, the subject may contain binary  subject, \fBpcre_exec()\fP returns PCRE_ERROR_BADOFFSET. When the starting
1600  zero bytes. When the starting offset is zero, the search for a match starts at  offset is zero, the search for a match starts at the beginning of the subject,
1601  the beginning of the subject, and this is by far the most common case.  and this is by far the most common case. In UTF-8 mode, the byte offset must
1602    point to the start of a UTF-8 character (or the end of the subject). Unlike the
1603    pattern string, the subject may contain binary zero bytes.
1604  .P  .P
1605  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
1606  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 1473  start of the subject, which is deemed to Line 1620  start of the subject, which is deemed to
1620  set to 4, it finds the second occurrence of "iss" because it is able to look  set to 4, it finds the second occurrence of "iss" because it is able to look
1621  behind the starting point to discover that it is preceded by a letter.  behind the starting point to discover that it is preceded by a letter.
1622  .P  .P
1623    Finding all the matches in a subject is tricky when the pattern can match an
1624    empty string. It is possible to emulate Perl's /g behaviour by first trying the
1625    match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
1626    PCRE_ANCHORED options, and then if that fails, advancing the starting offset
1627    and trying an ordinary match again. There is some code that demonstrates how to
1628    do this in the
1629    .\" HREF
1630    \fBpcredemo\fP
1631    .\"
1632    sample program. In the most general case, you have to check to see if the
1633    newline convention recognizes CRLF as a newline, and if so, and the current
1634    character is CR followed by LF, advance the starting offset by two characters
1635    instead of one.
1636    .P
1637  If a non-zero starting offset is passed when the pattern is anchored, one  If a non-zero starting offset is passed when the pattern is anchored, one
1638  attempt to match at the given offset is made. This can only succeed if the  attempt to match at the given offset is made. This can only succeed if the
1639  pattern does not require the match to be at the start of the subject.  pattern does not require the match to be at the start of the subject.
1640  .  .
1641    .
1642  .SS "How \fBpcre_exec()\fP returns captured substrings"  .SS "How \fBpcre_exec()\fP returns captured substrings"
1643  .rs  .rs
1644  .sp  .sp
# Line 1543  Offset values that correspond to unused Line 1705  Offset values that correspond to unused
1705  expression are also set to -1. For example, if the string "abc" is matched  expression are also set to -1. For example, if the string "abc" is matched
1706  against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The  against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
1707  return from the function is 2, because the highest used capturing subpattern  return from the function is 2, because the highest used capturing subpattern
1708  number is 1. However, you can refer to the offsets for the second and third  number is 1, and the offsets for for the second and third capturing subpatterns
1709  capturing subpatterns if you wish (assuming the vector is large enough, of  (assuming the vector is large enough, of course) are set to -1.
1710  course).  .P
1711    \fBNote\fP: Elements of \fIovector\fP that do not correspond to capturing
1712    parentheses in the pattern are never changed. That is, if a pattern contains
1713    \fIn\fP capturing parentheses, no more than \fIovector[0]\fP to
1714    \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other elements retain
1715    whatever values they previously had.
1716  .P  .P
1717  Some convenience functions are provided for extracting the captured substrings  Some convenience functions are provided for extracting the captured substrings
1718  as separate strings. These are described below.  as separate strings. These are described below.
# Line 1591  If a pattern contains back references, b Line 1758  If a pattern contains back references, b
1758  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
1759  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
1760  automatically freed at the end of matching.  automatically freed at the end of matching.
1761    .P
1762    This error is also given if \fBpcre_stack_malloc()\fP fails in
1763    \fBpcre_exec()\fP. This can happen only when PCRE has been compiled with
1764    \fB--disable-stack-for-recursion\fP.
1765  .sp  .sp
1766    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1767  .sp  .sp
# Line 1616  documentation for details. Line 1787  documentation for details.
1787    PCRE_ERROR_BADUTF8        (-10)    PCRE_ERROR_BADUTF8        (-10)
1788  .sp  .sp
1789  A string that contains an invalid UTF-8 byte sequence was passed as a subject.  A string that contains an invalid UTF-8 byte sequence was passed as a subject.
1790    However, if PCRE_PARTIAL_HARD is set and the problem is a truncated UTF-8
1791    character at the end of the subject, PCRE_ERROR_SHORTUTF8 is used instead.
1792  .sp  .sp
1793    PCRE_ERROR_BADUTF8_OFFSET (-11)    PCRE_ERROR_BADUTF8_OFFSET (-11)
1794  .sp  .sp
1795  The UTF-8 byte sequence that was passed as a subject was valid, but the value  The UTF-8 byte sequence that was passed as a subject was valid, but the value
1796  of \fIstartoffset\fP did not point to the beginning of a UTF-8 character.  of \fIstartoffset\fP did not point to the beginning of a UTF-8 character or the
1797    end of the subject.
1798  .sp  .sp
1799    PCRE_ERROR_PARTIAL        (-12)    PCRE_ERROR_PARTIAL        (-12)
1800  .sp  .sp
# Line 1655  description above. Line 1829  description above.
1829    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
1830  .sp  .sp
1831  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
1832    .sp
1833      PCRE_ERROR_BADOFFSET      (-24)
1834    .sp
1835    The value of \fIstartoffset\fP was negative or greater than the length of the
1836    subject, that is, the value in \fIlength\fP.
1837    .sp
1838      PCRE_ERROR_SHORTUTF8      (-25)
1839    .sp
1840    The subject string ended with an incomplete (truncated) UTF-8 character, and
1841    the PCRE_PARTIAL_HARD option was set. Without this option, PCRE_ERROR_BADUTF8
1842    is returned in this situation.
1843  .P  .P
1844  Error numbers -16 to -20 and -22 are not used by \fBpcre_exec()\fP.  Error numbers -16 to -20 and -22 are not used by \fBpcre_exec()\fP.
1845  .  .
# Line 1939  Here is an example of a simple call to \ Line 2124  Here is an example of a simple call to \
2124  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
2125  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,
2126  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
2127  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,
2128  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.
2129  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,
2130    so their description is not repeated here.
2131  .sp  .sp
2132    PCRE_PARTIAL_HARD    PCRE_PARTIAL_HARD
2133    PCRE_PARTIAL_SOFT    PCRE_PARTIAL_SOFT
# Line 1956  is converted into PCRE_ERROR_PARTIAL if Line 2142  is converted into PCRE_ERROR_PARTIAL if
2142  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
2143  possibility. The portion of the string that was inspected when the longest  possibility. The portion of the string that was inspected when the longest
2144  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.
2145    There is a more detailed discussion of partial and multi-segment matching, with
2146    examples, in the
2147    .\" HREF
2148    \fBpcrepartial\fP
2149    .\"
2150    documentation.
2151  .sp  .sp
2152    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
2153  .sp  .sp
# Line 2075  Cambridge CB2 3QH, England. Line 2267  Cambridge CB2 3QH, England.
2267  .rs  .rs
2268  .sp  .sp
2269  .nf  .nf
2270  Last updated: 03 October 2009  Last updated: 21 November 2010
2271  Copyright (c) 1997-2009 University of Cambridge.  Copyright (c) 1997-2010 University of Cambridge.
2272  .fi  .fi

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