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revision 525 by ph10, Wed May 26 10:50:24 2010 UTC revision 569 by ph10, Sun Nov 7 16:14:50 2010 UTC
# Line 134  Applications can use these to include su Line 134  Applications can use these to include su
134  .P  .P
135  In a Windows environment, if you want to statically link an application program  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  against a non-dll \fBpcre.a\fP file, you must define PCRE_STATIC before
137  including \fBpcre.h\fP, because otherwise the \fBpcre_malloc()\fP and  including \fBpcre.h\fP or \fBpcrecpp.h\fP, because otherwise the
138  \fBpcre_free()\fP exported functions will be declared  \fBpcre_malloc()\fP and \fBpcre_free()\fP exported functions will be declared
139  \fB__declspec(dllimport)\fP, with unwanted results.  \fB__declspec(dllimport)\fP, with unwanted results.
140  .P  .P
141  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,
# 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 765  out of use. To avoid confusion, they hav Line 769  out of use. To avoid confusion, they hav
769    50  [this code is not in use]    50  [this code is not in use]
770    51  octal value is greater than \e377 (not in UTF-8 mode)    51  octal value is greater than \e377 (not in UTF-8 mode)
771    52  internal error: overran compiling workspace    52  internal error: overran compiling workspace
772    53  internal error: previously-checked referenced subpattern not found    53  internal error: previously-checked referenced subpattern
773            not found
774    54  DEFINE group contains more than one branch    54  DEFINE group contains more than one branch
775    55  repeating a DEFINE group is not allowed    55  repeating a DEFINE group is not allowed
776    56  inconsistent NEWLINE options    56  inconsistent NEWLINE options
# Line 778  out of use. To avoid confusion, they hav Line 783  out of use. To avoid confusion, they hav
783    62  subpattern name expected    62  subpattern name expected
784    63  digit expected after (?+    63  digit expected after (?+
785    64  ] is an invalid data character in JavaScript compatibility mode    64  ] is an invalid data character in JavaScript compatibility mode
786    65  different names for subpatterns of the same number are not allowed    65  different names for subpatterns of the same number are
787            not allowed
788    66  (*MARK) must have an argument    66  (*MARK) must have an argument
789    67  this version of PCRE is not compiled with PCRE_UCP support    67  this version of PCRE is not compiled with PCRE_UCP support
790  .sp  .sp
# Line 846  Studying a pattern is also useful for no Line 852  Studying a pattern is also useful for no
852  single fixed starting character. A bitmap of possible starting bytes is  single fixed starting character. A bitmap of possible starting bytes is
853  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
854  matching.  matching.
855    .P
856    The two optimizations just described can be disabled by setting the
857    PCRE_NO_START_OPTIMIZE option when calling \fBpcre_exec()\fP or
858    \fBpcre_dfa_exec()\fP. You might want to do this if your pattern contains
859    callouts, or make use of (*MARK), and you make use of these in cases where
860    matching fails. See the discussion of PCRE_NO_START_OPTIMIZE
861    .\" HTML <a href="#execoptions">
862    .\" </a>
863    below.
864    .\"
865  .  .
866  .  .
867  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
# Line 1438  the Line 1454  the
1454  .\" HREF  .\" HREF
1455  \fBpcredemo\fP  \fBpcredemo\fP
1456  .\"  .\"
1457  sample program.  sample program. In the most general case, you have to check to see if the
1458    newline convention recognizes CRLF as a newline, and if so, and the current
1459    character is CR followed by LF, advance the starting offset by two characters
1460    instead of one.
1461  .sp  .sp
1462    PCRE_NO_START_OPTIMIZE    PCRE_NO_START_OPTIMIZE
1463  .sp  .sp
1464  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
1465  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
1466  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
1467  character, and fails immediately if it cannot find it, without actually running  for that character, and fails immediately if it cannot find it, without
1468  the main matching function. When callouts are in use, these optimizations can  actually running the main matching function. This means that a special item
1469  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
1470  causing performance to suffer, but ensuring that the callouts do occur.  suitable starting point for the match has been found. When callouts or (*MARK)
1471    items are in use, these "start-up" optimizations can cause them to be skipped
1472    if the pattern is never actually used. The start-up optimizations are in effect
1473    a pre-scan of the subject that takes place before the pattern is run.
1474    .P
1475    The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
1476    causing performance to suffer, but ensuring that in cases where the result is
1477    "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
1478    are considered at every possible starting position in the subject string.
1479    Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
1480    Consider the pattern
1481    .sp
1482      (*COMMIT)ABC
1483    .sp
1484    When this is compiled, PCRE records the fact that a match must start with the
1485    character "A". Suppose the subject string is "DEFABC". The start-up
1486    optimization scans along the subject, finds "A" and runs the first match
1487    attempt from there. The (*COMMIT) item means that the pattern must match the
1488    current starting position, which in this case, it does. However, if the same
1489    match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
1490    subject string does not happen. The first match attempt is run starting from
1491    "D" and when this fails, (*COMMIT) prevents any further matches being tried, so
1492    the overall result is "no match". If the pattern is studied, more start-up
1493    optimizations may be used. For example, a minimum length for the subject may be
1494    recorded. Consider the pattern
1495    .sp
1496      (*MARK:A)(X|Y)
1497    .sp
1498    The minimum length for a match is one character. If the subject is "ABC", there
1499    will be attempts to match "ABC", "BC", "C", and then finally an empty string.
1500    If the pattern is studied, the final attempt does not take place, because PCRE
1501    knows that the subject is too short, and so the (*MARK) is never encountered.
1502    In this case, studying the pattern does not affect the overall match result,
1503    which is still "no match", but it does affect the auxiliary information that is
1504    returned.
1505  .sp  .sp
1506    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1507  .sp  .sp
# Line 1466  in the main Line 1519  in the main
1519  \fBpcre\fP  \fBpcre\fP
1520  .\"  .\"
1521  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
1522  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
1523  PCRE_ERROR_BADUTF8_OFFSET is returned.  a truncated UTF-8 character at the end of the subject, PCRE_ERROR_SHORTUTF8. If
1524    \fIstartoffset\fP contains a value that does not point to the start of a UTF-8
1525    character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
1526    returned.
1527  .P  .P
1528  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
1529  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
1530  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
1531  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
1532  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
1533  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
1534  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
1535  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
1536  UTF-8 character, is undefined. Your program may crash.  undefined. Your program may crash.
1537  .sp  .sp
1538    PCRE_PARTIAL_HARD    PCRE_PARTIAL_HARD
1539    PCRE_PARTIAL_SOFT    PCRE_PARTIAL_SOFT
# Line 1486  These options turn on the partial matchi Line 1542  These options turn on the partial matchi
1542  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
1543  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
1544  not enough subject characters to complete the match. If this happens when  not enough subject characters to complete the match. If this happens when
1545  PCRE_PARTIAL_HARD is set, \fBpcre_exec()\fP immediately returns  PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set, matching continues by
1546  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
1547  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,
1548  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,
1549  was inspected when the partial match was found is set as the first matching  but only if no complete match can be found.
1550  string. There is a more detailed discussion in the  .P
1551    If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
1552    partial match is found, \fBpcre_exec()\fP immediately returns
1553    PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
1554    when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
1555    important that an alternative complete match.
1556    .P
1557    In both cases, the portion of the string that was inspected when the partial
1558    match was found is set as the first matching string. There is a more detailed
1559    discussion of partial and multi-segment matching, with examples, in the
1560  .\" HREF  .\" HREF
1561  \fBpcrepartial\fP  \fBpcrepartial\fP
1562  .\"  .\"
1563  documentation.  documentation.
1564  .  .
1565    .
1566  .SS "The string to be matched by \fBpcre_exec()\fP"  .SS "The string to be matched by \fBpcre_exec()\fP"
1567  .rs  .rs
1568  .sp  .sp
1569  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
1570  \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
1571  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
1572  a UTF-8 character. Unlike the pattern string, the subject may contain binary  subject, \fBpcre_exec()\fP returns PCRE_ERROR_BADOFFSET.
1573  zero bytes. When the starting offset is zero, the search for a match starts at  .P
1574  the beginning of the subject, and this is by far the most common case.  In UTF-8 mode, the byte offset must point to the start of a UTF-8 character (or
1575    the end of the subject). Unlike the pattern string, the subject may contain
1576    binary zero bytes. When the starting offset is zero, the search for a match
1577    starts at the beginning of the subject, and this is by far the most common
1578    case.
1579  .P  .P
1580  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
1581  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 1525  start of the subject, which is deemed to Line 1595  start of the subject, which is deemed to
1595  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
1596  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.
1597  .P  .P
1598    Finding all the matches in a subject is tricky when the pattern can match an
1599    empty string. It is possible to emulate Perl's /g behaviour by first trying the
1600    match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
1601    PCRE_ANCHORED options, and then if that fails, advancing the starting offset
1602    and trying an ordinary match again. There is some code that demonstrates how to
1603    do this in the
1604    .\" HREF
1605    \fBpcredemo\fP
1606    .\"
1607    sample program. In the most general case, you have to check to see if the
1608    newline convention recognizes CRLF as a newline, and if so, and the current
1609    character is CR followed by LF, advance the starting offset by two characters
1610    instead of one.
1611    .P
1612  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
1613  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
1614  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.
1615  .  .
1616    .
1617  .SS "How \fBpcre_exec()\fP returns captured substrings"  .SS "How \fBpcre_exec()\fP returns captured substrings"
1618  .rs  .rs
1619  .sp  .sp
# Line 1595  Offset values that correspond to unused Line 1680  Offset values that correspond to unused
1680  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
1681  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
1682  return from the function is 2, because the highest used capturing subpattern  return from the function is 2, because the highest used capturing subpattern
1683  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
1684  capturing subpatterns if you wish (assuming the vector is large enough, of  (assuming the vector is large enough, of course) are set to -1.
1685  course).  .P
1686    \fBNote\fP: Elements of \fIovector\fP that do not correspond to capturing
1687    parentheses in the pattern are never changed. That is, if a pattern contains
1688    \fIn\fP capturing parentheses, no more than \fIovector[0]\fP to
1689    \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other elements retain
1690    whatever values they previously had.
1691  .P  .P
1692  Some convenience functions are provided for extracting the captured substrings  Some convenience functions are provided for extracting the captured substrings
1693  as separate strings. These are described below.  as separate strings. These are described below.
# Line 1643  If a pattern contains back references, b Line 1733  If a pattern contains back references, b
1733  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
1734  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
1735  automatically freed at the end of matching.  automatically freed at the end of matching.
1736    .P
1737    This error is also given if \fBpcre_stack_malloc()\fP fails in
1738    \fBpcre_exec()\fP. This can happen only when PCRE has been compiled with
1739    \fB--disable-stack-for-recursion\fP.
1740  .sp  .sp
1741    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1742  .sp  .sp
# Line 1668  documentation for details. Line 1762  documentation for details.
1762    PCRE_ERROR_BADUTF8        (-10)    PCRE_ERROR_BADUTF8        (-10)
1763  .sp  .sp
1764  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.
1765    However, if PCRE_PARTIAL_HARD is set and the problem is a truncated UTF-8
1766    character at the end of the subject, PCRE_ERROR_SHORTUTF8 is used instead.
1767  .sp  .sp
1768    PCRE_ERROR_BADUTF8_OFFSET (-11)    PCRE_ERROR_BADUTF8_OFFSET (-11)
1769  .sp  .sp
1770  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
1771  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
1772    end of the subject.
1773  .sp  .sp
1774    PCRE_ERROR_PARTIAL        (-12)    PCRE_ERROR_PARTIAL        (-12)
1775  .sp  .sp
# Line 1707  description above. Line 1804  description above.
1804    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
1805  .sp  .sp
1806  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
1807    .sp
1808      PCRE_ERROR_BADOFFSET      (-24)
1809    .sp
1810    The value of \fIstartoffset\fP was negative or greater than the length of the
1811    subject, that is, the value in \fIlength\fP.
1812    .sp
1813      PCRE_ERROR_SHORTUTF8      (-25)
1814    .sp
1815    The subject string ended with an incomplete (truncated) UTF-8 character, and
1816    the PCRE_PARTIAL_HARD option was set. Without this option, PCRE_ERROR_BADUTF8
1817    is returned in this situation.
1818  .P  .P
1819  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.
1820  .  .
# Line 1991  Here is an example of a simple call to \ Line 2099  Here is an example of a simple call to \
2099  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
2100  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,
2101  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
2102  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,
2103  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.
2104  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,
2105    so their description is not repeated here.
2106  .sp  .sp
2107    PCRE_PARTIAL_HARD    PCRE_PARTIAL_HARD
2108    PCRE_PARTIAL_SOFT    PCRE_PARTIAL_SOFT
# Line 2008  is converted into PCRE_ERROR_PARTIAL if Line 2117  is converted into PCRE_ERROR_PARTIAL if
2117  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
2118  possibility. The portion of the string that was inspected when the longest  possibility. The portion of the string that was inspected when the longest
2119  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.
2120    There is a more detailed discussion of partial and multi-segment matching, with
2121    examples, in the
2122    .\" HREF
2123    \fBpcrepartial\fP
2124    .\"
2125    documentation.
2126  .sp  .sp
2127    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
2128  .sp  .sp
# Line 2127  Cambridge CB2 3QH, England. Line 2242  Cambridge CB2 3QH, England.
2242  .rs  .rs
2243  .sp  .sp
2244  .nf  .nf
2245  Last updated: 26 May 2010  Last updated: 06 November 2010
2246  Copyright (c) 1997-2010 University of Cambridge.  Copyright (c) 1997-2010 University of Cambridge.
2247  .fi  .fi

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