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revision 566 by ph10, Wed Nov 3 18:32:55 2010 UTC revision 572 by ph10, Wed Nov 17 17:55:57 2010 UTC
# Line 435  If \fIerrptr\fP is NULL, \fBpcre_compile Line 435  If \fIerrptr\fP is NULL, \fBpcre_compile
435  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
436  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
437  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
438  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
439  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
440  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
441  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
442  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
443  set to the end of the pattern.  of the pattern.
444    .P
445    Note that the offset is in bytes, not characters, even in UTF-8 mode. It may
446    point into the middle of a UTF-8 character (for example, when
447    PCRE_ERROR_BADUTF8 is returned for an invalid UTF-8 string).
448  .P  .P
449  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
450  \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 519  pattern. Line 523  pattern.
523  .sp  .sp
524    PCRE_DOTALL    PCRE_DOTALL
525  .sp  .sp
526  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
527  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
528  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,
529  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
530  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
531  the setting of this option.  (?s) option setting. A negative class such as [^a] always matches newline
532    characters, independent of the setting of this option.
533  .sp  .sp
534    PCRE_DUPNAMES    PCRE_DUPNAMES
535  .sp  .sp
# Line 546  unescaped # outside a character class an Line 551  unescaped # outside a character class an
551  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
552  pattern by a (?x) option setting.  pattern by a (?x) option setting.
553  .P  .P
554    Which characters are interpreted as newlines
555    is controlled by the options passed to \fBpcre_compile()\fP or by a special
556    sequence at the start of the pattern, as described in the section entitled
557    .\" HTML <a href="pcrepattern.html#newlines">
558    .\" </a>
559    "Newline conventions"
560    .\"
561    in the \fBpcrepattern\fP documentation. Note that the end of this type of
562    comment is a literal newline sequence in the pattern; escape sequences that
563    happen to represent a newline do not count.
564    .P
565  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
566  Note, however, that this applies only to data characters. Whitespace characters  Note, however, that this applies only to data characters. Whitespace characters
567  may never appear within special character sequences in a pattern, for example  may never appear within special character sequences in a pattern, for example
568  within the sequence (?( which introduces a conditional subpattern.  within the sequence (?( that introduces a conditional subpattern.
569  .sp  .sp
570    PCRE_EXTRA    PCRE_EXTRA
571  .sp  .sp
# Line 624  option, the combination may or may not b Line 640  option, the combination may or may not b
640  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
641  other combinations may yield unused numbers and cause an error.  other combinations may yield unused numbers and cause an error.
642  .P  .P
643  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
644  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,
645  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
646  line break sequence. In other circumstances, line break sequences are treated  indicates a comment that lasts until after the next line break sequence. In
647  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
648  as whitespace characters and are therefore ignored.  data.
649  .P  .P
650  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
651  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 644  in Perl. Line 660  in Perl.
660  .sp  .sp
661    PCRE_UCP    PCRE_UCP
662  .sp  .sp
663  This option changes the way PCRE processes \eb, \ed, \es, \ew, and some of the  This option changes the way PCRE processes \eB, \eb, \eD, \ed, \eS, \es, \eW,
664  POSIX character classes. By default, only ASCII characters are recognized, but  \ew, and some of the POSIX character classes. By default, only ASCII characters
665  if PCRE_UCP is set, Unicode properties are used instead to classify characters.  are recognized, but if PCRE_UCP is set, Unicode properties are used instead to
666  More details are given in the section on  classify characters. More details are given in the section on
667  .\" HTML <a href="pcre.html#genericchartypes">  .\" HTML <a href="pcre.html#genericchartypes">
668  .\" </a>  .\" </a>
669  generic character types  generic character types
# Line 852  matching. Line 868  matching.
868  The two optimizations just described can be disabled by setting the  The two optimizations just described can be disabled by setting the
869  PCRE_NO_START_OPTIMIZE option when calling \fBpcre_exec()\fP or  PCRE_NO_START_OPTIMIZE option when calling \fBpcre_exec()\fP or
870  \fBpcre_dfa_exec()\fP. You might want to do this if your pattern contains  \fBpcre_dfa_exec()\fP. You might want to do this if your pattern contains
871  callouts, or make use of (*MARK), and you make use of these in cases where  callouts or (*MARK), and you want to make use of these facilities in cases
872  matching fails. See the discussion of PCRE_NO_START_OPTIMIZE  where matching fails. See the discussion of PCRE_NO_START_OPTIMIZE
873  .\" HTML <a href="#execoptions">  .\" HTML <a href="#execoptions">
874  .\" </a>  .\" </a>
875  below.  below.
# Line 1450  the Line 1466  the
1466  .\" HREF  .\" HREF
1467  \fBpcredemo\fP  \fBpcredemo\fP
1468  .\"  .\"
1469  sample program. In the most general case, you have to check to see if the  sample program. In the most general case, you have to check to see if the
1470  newline convention recognizes CRLF as a newline, and if so, and the current  newline convention recognizes CRLF as a newline, and if so, and the current
1471  character is CR followed by LF, advance the starting offset by two characters  character is CR followed by LF, advance the starting offset by two characters
1472  instead of one.  instead of one.
1473  .sp  .sp
# Line 1515  in the main Line 1531  in the main
1531  \fBpcre\fP  \fBpcre\fP
1532  .\"  .\"
1533  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
1534  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
1535  PCRE_ERROR_BADUTF8_OFFSET is returned.  a truncated UTF-8 character at the end of the subject, PCRE_ERROR_SHORTUTF8. If
1536    \fIstartoffset\fP contains a value that does not point to the start of a UTF-8
1537    character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
1538    returned.
1539  .P  .P
1540  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
1541  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
1542  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
1543  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
1544  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
1545  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
1546  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
1547  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
1548  UTF-8 character, is undefined. Your program may crash.  undefined. Your program may crash.
1549  .sp  .sp
1550    PCRE_PARTIAL_HARD    PCRE_PARTIAL_HARD
1551    PCRE_PARTIAL_SOFT    PCRE_PARTIAL_SOFT
# Line 1544  but only if no complete match can be fou Line 1563  but only if no complete match can be fou
1563  If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a  If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
1564  partial match is found, \fBpcre_exec()\fP immediately returns  partial match is found, \fBpcre_exec()\fP immediately returns
1565  PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,  PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
1566  when PCRE_PARTIAL_HARD is set, a partial match is considered to be more  when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
1567  important that an alternative complete match.  important that an alternative complete match.
1568  .P  .P
1569  In both cases, the portion of the string that was inspected when the partial  In both cases, the portion of the string that was inspected when the partial
# Line 1555  discussion of partial and multi-segment Line 1574  discussion of partial and multi-segment
1574  .\"  .\"
1575  documentation.  documentation.
1576  .  .
1577    .
1578  .SS "The string to be matched by \fBpcre_exec()\fP"  .SS "The string to be matched by \fBpcre_exec()\fP"
1579  .rs  .rs
1580  .sp  .sp
1581  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
1582  \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
1583  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
1584  a UTF-8 character. Unlike the pattern string, the subject may contain binary  subject, \fBpcre_exec()\fP returns PCRE_ERROR_BADOFFSET. When the starting
1585  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,
1586  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
1587    point to the start of a UTF-8 character (or the end of the subject). Unlike the
1588    pattern string, the subject may contain binary zero bytes.
1589  .P  .P
1590  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
1591  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 1583  start of the subject, which is deemed to Line 1605  start of the subject, which is deemed to
1605  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
1606  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.
1607  .P  .P
1608    Finding all the matches in a subject is tricky when the pattern can match an
1609    empty string. It is possible to emulate Perl's /g behaviour by first trying the
1610    match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
1611    PCRE_ANCHORED options, and then if that fails, advancing the starting offset
1612    and trying an ordinary match again. There is some code that demonstrates how to
1613    do this in the
1614    .\" HREF
1615    \fBpcredemo\fP
1616    .\"
1617    sample program. In the most general case, you have to check to see if the
1618    newline convention recognizes CRLF as a newline, and if so, and the current
1619    character is CR followed by LF, advance the starting offset by two characters
1620    instead of one.
1621    .P
1622  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
1623  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
1624  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.
1625  .  .
1626    .
1627  .SS "How \fBpcre_exec()\fP returns captured substrings"  .SS "How \fBpcre_exec()\fP returns captured substrings"
1628  .rs  .rs
1629  .sp  .sp
# Line 1653  Offset values that correspond to unused Line 1690  Offset values that correspond to unused
1690  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
1691  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
1692  return from the function is 2, because the highest used capturing subpattern  return from the function is 2, because the highest used capturing subpattern
1693  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
1694  capturing subpatterns if you wish (assuming the vector is large enough, of  (assuming the vector is large enough, of course) are set to -1.
1695  course).  .P
1696    \fBNote\fP: Elements of \fIovector\fP that do not correspond to capturing
1697    parentheses in the pattern are never changed. That is, if a pattern contains
1698    \fIn\fP capturing parentheses, no more than \fIovector[0]\fP to
1699    \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other elements retain
1700    whatever values they previously had.
1701  .P  .P
1702  Some convenience functions are provided for extracting the captured substrings  Some convenience functions are provided for extracting the captured substrings
1703  as separate strings. These are described below.  as separate strings. These are described below.
# Line 1730  documentation for details. Line 1772  documentation for details.
1772    PCRE_ERROR_BADUTF8        (-10)    PCRE_ERROR_BADUTF8        (-10)
1773  .sp  .sp
1774  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.
1775    However, if PCRE_PARTIAL_HARD is set and the problem is a truncated UTF-8
1776    character at the end of the subject, PCRE_ERROR_SHORTUTF8 is used instead.
1777  .sp  .sp
1778    PCRE_ERROR_BADUTF8_OFFSET (-11)    PCRE_ERROR_BADUTF8_OFFSET (-11)
1779  .sp  .sp
1780  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
1781  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
1782    end of the subject.
1783  .sp  .sp
1784    PCRE_ERROR_PARTIAL        (-12)    PCRE_ERROR_PARTIAL        (-12)
1785  .sp  .sp
# Line 1769  description above. Line 1814  description above.
1814    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
1815  .sp  .sp
1816  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
1817    .sp
1818      PCRE_ERROR_BADOFFSET      (-24)
1819    .sp
1820    The value of \fIstartoffset\fP was negative or greater than the length of the
1821    subject, that is, the value in \fIlength\fP.
1822    .sp
1823      PCRE_ERROR_SHORTUTF8      (-25)
1824    .sp
1825    The subject string ended with an incomplete (truncated) UTF-8 character, and
1826    the PCRE_PARTIAL_HARD option was set. Without this option, PCRE_ERROR_BADUTF8
1827    is returned in this situation.
1828  .P  .P
1829  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.
1830  .  .
# Line 2196  Cambridge CB2 3QH, England. Line 2252  Cambridge CB2 3QH, England.
2252  .rs  .rs
2253  .sp  .sp
2254  .nf  .nf
2255  Last updated: 01 November 2010  Last updated: 13 November 2010
2256  Copyright (c) 1997-2010 University of Cambridge.  Copyright (c) 1997-2010 University of Cambridge.
2257  .fi  .fi

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