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revision 512 by ph10, Tue Mar 30 11:11:52 2010 UTC revision 659 by ph10, Tue Aug 16 09:48:29 2011 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. Normally, the offset from the start of the pattern to the
440  character that was being processed when the error was discovered is placed in  byte that was being processed when the error was discovered is placed in the
441  the variable pointed to by \fIerroffset\fP, which must not be NULL. If it is,  variable pointed to by \fIerroffset\fP, which must not be NULL (if it is, an
442  an immediate error is given. Some errors are not detected until checks are  immediate error is given). However, for an invalid UTF-8 string, the offset is
443  carried out when the whole pattern has been scanned; in this case the offset is  that of the first byte of the failing character. Also, some errors are not
444  set to the end of the pattern.  detected until checks are carried out when the whole pattern has been scanned;
445    in these cases the offset passed back is the length of the pattern.
446    .P
447    Note that the offset is in bytes, not characters, even in UTF-8 mode. It may
448    sometimes point into the middle of a UTF-8 character.
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 is controlled by the options
556    passed to \fBpcre_compile()\fP or by a special sequence at the start of the
557    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 724  out of use. To avoid confusion, they hav Line 777  out of use. To avoid confusion, they hav
777    34  character value in \ex{...} sequence is too large    34  character value in \ex{...} sequence is too large
778    35  invalid condition (?(0)    35  invalid condition (?(0)
779    36  \eC not allowed in lookbehind assertion    36  \eC not allowed in lookbehind assertion
780    37  PCRE does not support \eL, \el, \eN, \eU, or \eu    37  PCRE does not support \eL, \el, \eN{name}, \eU, or \eu
781    38  number after (?C is > 255    38  number after (?C is > 255
782    39  closing ) for (?C expected    39  closing ) for (?C expected
783    40  recursive call could loop indefinitely    40  recursive call could loop indefinitely
# 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
# Line 753  out of use. To avoid confusion, they hav Line 807  out of use. To avoid confusion, they hav
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 not allowed    65  different names for subpatterns of the same number are
811            not allowed
812    66  (*MARK) must have an argument    66  (*MARK) must have an argument
813      67  this version of PCRE is not compiled with PCRE_UCP support
814      68  \ec must be followed by an ASCII character
815      69  \ek is not followed by a braced, angle-bracketed, or quoted name
816  .sp  .sp
817  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
818  be used if the limits were changed when PCRE was built.  be used if the limits were changed when PCRE was built.
819  .  .
820  .  .
821    .\" HTML <a name="studyingapattern"></a>
822  .SH "STUDYING A PATTERN"  .SH "STUDYING A PATTERN"
823  .rs  .rs
824  .sp  .sp
# Line 820  Studying a pattern is also useful for no Line 879  Studying a pattern is also useful for no
879  single fixed starting character. A bitmap of possible starting bytes is  single fixed starting character. A bitmap of possible starting bytes is
880  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
881  matching.  matching.
882    .P
883    The two optimizations just described can be disabled by setting the
884    PCRE_NO_START_OPTIMIZE option when calling \fBpcre_exec()\fP or
885    \fBpcre_dfa_exec()\fP. You might want to do this if your pattern contains
886    callouts or (*MARK), and you want to make use of these facilities in cases
887    where matching fails. See the discussion of PCRE_NO_START_OPTIMIZE
888    .\" HTML <a href="#execoptions">
889    .\" </a>
890    below.
891    .\"
892  .  .
893  .  .
894  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
# Line 829  matching. Line 898  matching.
898  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters,
899  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
900  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
901  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
902  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
903  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
904  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
905  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
906    handling characters with codes greater than 128, you should either use UTF-8
907    and Unicode, or use locales, but not try to mix the two.
908  .P  .P
909  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
910  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 878  one in which it was compiled. Passing ta Line 949  one in which it was compiled. Passing ta
949  below in the section on matching a pattern.  below in the section on matching a pattern.
950  .  .
951  .  .
952    .\" HTML <a name="infoaboutpattern"></a>
953  .SH "INFORMATION ABOUT A PATTERN"  .SH "INFORMATION ABOUT A PATTERN"
954  .rs  .rs
955  .sp  .sp
# Line 1096  variable. Line 1168  variable.
1168  .sp  .sp
1169    PCRE_INFO_STUDYSIZE    PCRE_INFO_STUDYSIZE
1170  .sp  .sp
1171  Return the size of the data block pointed to by the \fIstudy_data\fP field in  Return the size of the data block pointed to by the \fIstudy_data\fP field in a
1172  a \fBpcre_extra\fP block. That is, it is the value that was passed to  \fBpcre_extra\fP block. If \fBpcre_extra\fP is NULL, or there is no study data,
1173  \fBpcre_malloc()\fP when PCRE was getting memory into which to place the data  zero is returned. The fourth argument should point to a \fBsize_t\fP variable.
1174  created by \fBpcre_study()\fP. If \fBpcre_extra\fP is NULL, or there is no  The \fIstudy_data\fP field is set by \fBpcre_study()\fP to record information
1175  study data, zero is returned. The fourth argument should point to a  that will speed up matching (see the section entitled
1176  \fBsize_t\fP variable.  .\" HTML <a href="#studyingapattern">
1177    .\" </a>
1178    "Studying a pattern"
1179    .\"
1180    above). The format of the \fIstudy_data\fP block is private, but its length
1181    is made available via this option so that it can be saved and restored (see the
1182    .\" HREF
1183    \fBpcreprecompile\fP
1184    .\"
1185    documentation for details).
1186  .  .
1187  .  .
1188  .SH "OBSOLETE INFO FUNCTION"  .SH "OBSOLETE INFO FUNCTION"
# Line 1196  Here is an example of a simple call to \ Line 1277  Here is an example of a simple call to \
1277      ovector,        /* vector of integers for substring information */      ovector,        /* vector of integers for substring information */
1278      30);            /* number of elements (NOT size in bytes) */      30);            /* number of elements (NOT size in bytes) */
1279  .  .
1280    .
1281  .\" HTML <a name="extradata"></a>  .\" HTML <a name="extradata"></a>
1282  .SS "Extra data for \fBpcre_exec()\fR"  .SS "Extra data for \fBpcre_exec()\fR"
1283  .rs  .rs
# Line 1410  the Line 1492  the
1492  .\" HREF  .\" HREF
1493  \fBpcredemo\fP  \fBpcredemo\fP
1494  .\"  .\"
1495  sample program.  sample program. In the most general case, you have to check to see if the
1496    newline convention recognizes CRLF as a newline, and if so, and the current
1497    character is CR followed by LF, advance the starting offset by two characters
1498    instead of one.
1499  .sp  .sp
1500    PCRE_NO_START_OPTIMIZE    PCRE_NO_START_OPTIMIZE
1501  .sp  .sp
1502  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
1503  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
1504  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
1505  character, and fails immediately if it cannot find it, without actually running  for that character, and fails immediately if it cannot find it, without
1506  the main matching function. When callouts are in use, these optimizations can  actually running the main matching function. This means that a special item
1507  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
1508  causing performance to suffer, but ensuring that the callouts do occur.  suitable starting point for the match has been found. When callouts or (*MARK)
1509    items are in use, these "start-up" optimizations can cause them to be skipped
1510    if the pattern is never actually used. The start-up optimizations are in effect
1511    a pre-scan of the subject that takes place before the pattern is run.
1512    .P
1513    The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
1514    causing performance to suffer, but ensuring that in cases where the result is
1515    "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
1516    are considered at every possible starting position in the subject string. If
1517    PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
1518    time.
1519    .P
1520    Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
1521    Consider the pattern
1522    .sp
1523      (*COMMIT)ABC
1524    .sp
1525    When this is compiled, PCRE records the fact that a match must start with the
1526    character "A". Suppose the subject string is "DEFABC". The start-up
1527    optimization scans along the subject, finds "A" and runs the first match
1528    attempt from there. The (*COMMIT) item means that the pattern must match the
1529    current starting position, which in this case, it does. However, if the same
1530    match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
1531    subject string does not happen. The first match attempt is run starting from
1532    "D" and when this fails, (*COMMIT) prevents any further matches being tried, so
1533    the overall result is "no match". If the pattern is studied, more start-up
1534    optimizations may be used. For example, a minimum length for the subject may be
1535    recorded. Consider the pattern
1536    .sp
1537      (*MARK:A)(X|Y)
1538    .sp
1539    The minimum length for a match is one character. If the subject is "ABC", there
1540    will be attempts to match "ABC", "BC", "C", and then finally an empty string.
1541    If the pattern is studied, the final attempt does not take place, because PCRE
1542    knows that the subject is too short, and so the (*MARK) is never encountered.
1543    In this case, studying the pattern does not affect the overall match result,
1544    which is still "no match", but it does affect the auxiliary information that is
1545    returned.
1546  .sp  .sp
1547    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1548  .sp  .sp
# Line 1438  in the main Line 1560  in the main
1560  \fBpcre\fP  \fBpcre\fP
1561  .\"  .\"
1562  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
1563  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
1564  PCRE_ERROR_BADUTF8_OFFSET is returned.  a truncated UTF-8 character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
1565    both cases, information about the precise nature of the error may also be
1566    returned (see the descriptions of these errors in the section entitled \fIError
1567    return values from\fP \fBpcre_exec()\fP
1568    .\" HTML <a href="#errorlist">
1569    .\" </a>
1570    below).
1571    .\"
1572    If \fIstartoffset\fP contains a value that does not point to the start of a
1573    UTF-8 character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
1574    returned.
1575  .P  .P
1576  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
1577  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
1578  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
1579  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
1580  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
1581  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
1582  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
1583  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
1584  UTF-8 character, is undefined. Your program may crash.  undefined. Your program may crash.
1585  .sp  .sp
1586    PCRE_PARTIAL_HARD    PCRE_PARTIAL_HARD
1587    PCRE_PARTIAL_SOFT    PCRE_PARTIAL_SOFT
# Line 1458  These options turn on the partial matchi Line 1590  These options turn on the partial matchi
1590  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
1591  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
1592  not enough subject characters to complete the match. If this happens when  not enough subject characters to complete the match. If this happens when
1593  PCRE_PARTIAL_HARD is set, \fBpcre_exec()\fP immediately returns  PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set, matching continues by
1594  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
1595  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,
1596  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,
1597  was inspected when the partial match was found is set as the first matching  but only if no complete match can be found.
1598  string. There is a more detailed discussion in the  .P
1599    If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
1600    partial match is found, \fBpcre_exec()\fP immediately returns
1601    PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
1602    when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
1603    important that an alternative complete match.
1604    .P
1605    In both cases, the portion of the string that was inspected when the partial
1606    match was found is set as the first matching string. There is a more detailed
1607    discussion of partial and multi-segment matching, with examples, in the
1608  .\" HREF  .\" HREF
1609  \fBpcrepartial\fP  \fBpcrepartial\fP
1610  .\"  .\"
1611  documentation.  documentation.
1612  .  .
1613    .
1614  .SS "The string to be matched by \fBpcre_exec()\fP"  .SS "The string to be matched by \fBpcre_exec()\fP"
1615  .rs  .rs
1616  .sp  .sp
1617  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
1618  \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
1619  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
1620  a UTF-8 character. Unlike the pattern string, the subject may contain binary  subject, \fBpcre_exec()\fP returns PCRE_ERROR_BADOFFSET. When the starting
1621  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,
1622  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
1623    point to the start of a UTF-8 character (or the end of the subject). Unlike the
1624    pattern string, the subject may contain binary zero bytes.
1625  .P  .P
1626  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
1627  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 1497  start of the subject, which is deemed to Line 1641  start of the subject, which is deemed to
1641  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
1642  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.
1643  .P  .P
1644    Finding all the matches in a subject is tricky when the pattern can match an
1645    empty string. It is possible to emulate Perl's /g behaviour by first trying the
1646    match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
1647    PCRE_ANCHORED options, and then if that fails, advancing the starting offset
1648    and trying an ordinary match again. There is some code that demonstrates how to
1649    do this in the
1650    .\" HREF
1651    \fBpcredemo\fP
1652    .\"
1653    sample program. In the most general case, you have to check to see if the
1654    newline convention recognizes CRLF as a newline, and if so, and the current
1655    character is CR followed by LF, advance the starting offset by two characters
1656    instead of one.
1657    .P
1658  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
1659  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
1660  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.
1661  .  .
1662    .
1663  .SS "How \fBpcre_exec()\fP returns captured substrings"  .SS "How \fBpcre_exec()\fP returns captured substrings"
1664  .rs  .rs
1665  .sp  .sp
# Line 1567  Offset values that correspond to unused Line 1726  Offset values that correspond to unused
1726  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
1727  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
1728  return from the function is 2, because the highest used capturing subpattern  return from the function is 2, because the highest used capturing subpattern
1729  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
1730  capturing subpatterns if you wish (assuming the vector is large enough, of  (assuming the vector is large enough, of course) are set to -1.
1731  course).  .P
1732    \fBNote\fP: Elements of \fIovector\fP that do not correspond to capturing
1733    parentheses in the pattern are never changed. That is, if a pattern contains
1734    \fIn\fP capturing parentheses, no more than \fIovector[0]\fP to
1735    \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other elements retain
1736    whatever values they previously had.
1737  .P  .P
1738  Some convenience functions are provided for extracting the captured substrings  Some convenience functions are provided for extracting the captured substrings
1739  as separate strings. These are described below.  as separate strings. These are described below.
1740  .  .
1741    .
1742  .\" HTML <a name="errorlist"></a>  .\" HTML <a name="errorlist"></a>
1743  .SS "Error return values from \fBpcre_exec()\fP"  .SS "Error return values from \fBpcre_exec()\fP"
1744  .rs  .rs
# Line 1615  If a pattern contains back references, b Line 1780  If a pattern contains back references, b
1780  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
1781  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
1782  automatically freed at the end of matching.  automatically freed at the end of matching.
1783    .P
1784    This error is also given if \fBpcre_stack_malloc()\fP fails in
1785    \fBpcre_exec()\fP. This can happen only when PCRE has been compiled with
1786    \fB--disable-stack-for-recursion\fP.
1787  .sp  .sp
1788    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1789  .sp  .sp
# Line 1639  documentation for details. Line 1808  documentation for details.
1808  .sp  .sp
1809    PCRE_ERROR_BADUTF8        (-10)    PCRE_ERROR_BADUTF8        (-10)
1810  .sp  .sp
1811  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,
1812    and the PCRE_NO_UTF8_CHECK option was not set. If the size of the output vector
1813    (\fIovecsize\fP) is at least 2, the byte offset to the start of the the invalid
1814    UTF-8 character is placed in the first element, and a reason code is placed in
1815    the second element. The reason codes are listed in the
1816    .\" HTML <a href="#badutf8reasons">
1817    .\" </a>
1818    following section.
1819    .\"
1820    For backward compatibility, if PCRE_PARTIAL_HARD is set and the problem is a
1821    truncated UTF-8 character at the end of the subject (reason codes 1 to 5),
1822    PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
1823  .sp  .sp
1824    PCRE_ERROR_BADUTF8_OFFSET (-11)    PCRE_ERROR_BADUTF8_OFFSET (-11)
1825  .sp  .sp
1826  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 checked and found to
1827  of \fIstartoffset\fP did not point to the beginning of a UTF-8 character.  be valid (the PCRE_NO_UTF8_CHECK option was not set), but the value of
1828    \fIstartoffset\fP did not point to the beginning of a UTF-8 character or the
1829    end of the subject.
1830  .sp  .sp
1831    PCRE_ERROR_PARTIAL        (-12)    PCRE_ERROR_PARTIAL        (-12)
1832  .sp  .sp
# Line 1679  description above. Line 1861  description above.
1861    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
1862  .sp  .sp
1863  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
1864    .sp
1865      PCRE_ERROR_BADOFFSET      (-24)
1866    .sp
1867    The value of \fIstartoffset\fP was negative or greater than the length of the
1868    subject, that is, the value in \fIlength\fP.
1869    .sp
1870      PCRE_ERROR_SHORTUTF8      (-25)
1871    .sp
1872    This error is returned instead of PCRE_ERROR_BADUTF8 when the subject string
1873    ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD option is set.
1874    Information about the failure is returned as for PCRE_ERROR_BADUTF8. It is in
1875    fact sufficient to detect this case, but this special error code for
1876    PCRE_PARTIAL_HARD precedes the implementation of returned information; it is
1877    retained for backwards compatibility.
1878    .sp
1879      PCRE_ERROR_RECURSELOOP    (-26)
1880    .sp
1881    This error is returned when \fBpcre_exec()\fP detects a recursion loop within
1882    the pattern. Specifically, it means that either the whole pattern or a
1883    subpattern has been called recursively for the second time at the same position
1884    in the subject string. Some simple patterns that might do this are detected and
1885    faulted at compile time, but more complicated cases, in particular mutual
1886    recursions between two different subpatterns, cannot be detected until run
1887    time.
1888  .P  .P
1889  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.
1890  .  .
1891  .  .
1892    .\" HTML <a name="badutf8reasons"></a>
1893    .SS "Reason codes for invalid UTF-8 strings"
1894    .rs
1895    .sp
1896    When \fBpcre_exec()\fP returns either PCRE_ERROR_BADUTF8 or
1897    PCRE_ERROR_SHORTUTF8, and the size of the output vector (\fIovecsize\fP) is at
1898    least 2, the offset of the start of the invalid UTF-8 character is placed in
1899    the first output vector element (\fIovector[0]\fP) and a reason code is placed
1900    in the second element (\fIovector[1]\fP). The reason codes are given names in
1901    the \fBpcre.h\fP header file:
1902    .sp
1903      PCRE_UTF8_ERR1
1904      PCRE_UTF8_ERR2
1905      PCRE_UTF8_ERR3
1906      PCRE_UTF8_ERR4
1907      PCRE_UTF8_ERR5
1908    .sp
1909    The string ends with a truncated UTF-8 character; the code specifies how many
1910    bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8 characters to be
1911    no longer than 4 bytes, the encoding scheme (originally defined by RFC 2279)
1912    allows for up to 6 bytes, and this is checked first; hence the possibility of
1913    4 or 5 missing bytes.
1914    .sp
1915      PCRE_UTF8_ERR6
1916      PCRE_UTF8_ERR7
1917      PCRE_UTF8_ERR8
1918      PCRE_UTF8_ERR9
1919      PCRE_UTF8_ERR10
1920    .sp
1921    The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of the
1922    character do not have the binary value 0b10 (that is, either the most
1923    significant bit is 0, or the next bit is 1).
1924    .sp
1925      PCRE_UTF8_ERR11
1926      PCRE_UTF8_ERR12
1927    .sp
1928    A character that is valid by the RFC 2279 rules is either 5 or 6 bytes long;
1929    these code points are excluded by RFC 3629.
1930    .sp
1931      PCRE_UTF8_ERR13
1932    .sp
1933    A 4-byte character has a value greater than 0x10fff; these code points are
1934    excluded by RFC 3629.
1935    .sp
1936      PCRE_UTF8_ERR14
1937    .sp
1938    A 3-byte character has a value in the range 0xd800 to 0xdfff; this range of
1939    code points are reserved by RFC 3629 for use with UTF-16, and so are excluded
1940    from UTF-8.
1941    .sp
1942      PCRE_UTF8_ERR15
1943      PCRE_UTF8_ERR16
1944      PCRE_UTF8_ERR17
1945      PCRE_UTF8_ERR18
1946      PCRE_UTF8_ERR19
1947    .sp
1948    A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes for a
1949    value that can be represented by fewer bytes, which is invalid. For example,
1950    the two bytes 0xc0, 0xae give the value 0x2e, whose correct coding uses just
1951    one byte.
1952    .sp
1953      PCRE_UTF8_ERR20
1954    .sp
1955    The two most significant bits of the first byte of a character have the binary
1956    value 0b10 (that is, the most significant bit is 1 and the second is 0). Such a
1957    byte can only validly occur as the second or subsequent byte of a multi-byte
1958    character.
1959    .sp
1960      PCRE_UTF8_ERR21
1961    .sp
1962    The first byte of a character has the value 0xfe or 0xff. These values can
1963    never occur in a valid UTF-8 string.
1964    .
1965    .
1966  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
1967  .rs  .rs
1968  .sp  .sp
# Line 1878  fourth are pointers to variables which a Line 2158  fourth are pointers to variables which a
2158  has run, they point to the first and last entries in the name-to-number table  has run, they point to the first and last entries in the name-to-number table
2159  for the given name. The function itself returns the length of each entry, or  for the given name. The function itself returns the length of each entry, or
2160  PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is  PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
2161  described above in the section entitled \fIInformation about a pattern\fP.  described above in the section entitled \fIInformation about a pattern\fP
2162    .\" HTML <a href="#infoaboutpattern">
2163    .\" </a>
2164    above.
2165    .\"
2166  Given all the relevant entries for the name, you can extract each of their  Given all the relevant entries for the name, you can extract each of their
2167  numbers, and hence the captured data, if any.  numbers, and hence the captured data, if any.
2168  .  .
# Line 1963  Here is an example of a simple call to \ Line 2247  Here is an example of a simple call to \
2247  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
2248  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,
2249  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
2250  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,
2251  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.
2252  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,
2253    so their description is not repeated here.
2254  .sp  .sp
2255    PCRE_PARTIAL_HARD    PCRE_PARTIAL_HARD
2256    PCRE_PARTIAL_SOFT    PCRE_PARTIAL_SOFT
# Line 1980  is converted into PCRE_ERROR_PARTIAL if Line 2265  is converted into PCRE_ERROR_PARTIAL if
2265  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
2266  possibility. The portion of the string that was inspected when the longest  possibility. The portion of the string that was inspected when the longest
2267  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.
2268    There is a more detailed discussion of partial and multi-segment matching, with
2269    examples, in the
2270    .\" HREF
2271    \fBpcrepartial\fP
2272    .\"
2273    documentation.
2274  .sp  .sp
2275    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
2276  .sp  .sp
# Line 2001  match. There is more discussion of this Line 2292  match. There is more discussion of this
2292  .\"  .\"
2293  documentation.  documentation.
2294  .  .
2295    .
2296  .SS "Successful returns from \fBpcre_dfa_exec()\fP"  .SS "Successful returns from \fBpcre_dfa_exec()\fP"
2297  .rs  .rs
2298  .sp  .sp
# Line 2034  matching string is given first. If there Line 2326  matching string is given first. If there
2326  \fIovector\fP, the yield of the function is zero, and the vector is filled with  \fIovector\fP, the yield of the function is zero, and the vector is filled with
2327  the longest matches.  the longest matches.
2328  .  .
2329    .
2330  .SS "Error returns from \fBpcre_dfa_exec()\fP"  .SS "Error returns from \fBpcre_dfa_exec()\fP"
2331  .rs  .rs
2332  .sp  .sp
# Line 2099  Cambridge CB2 3QH, England. Line 2392  Cambridge CB2 3QH, England.
2392  .rs  .rs
2393  .sp  .sp
2394  .nf  .nf
2395  Last updated: 26 March 2010  Last updated: 13 August 2011
2396  Copyright (c) 1997-2010 University of Cambridge.  Copyright (c) 1997-2011 University of Cambridge.
2397  .fi  .fi

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