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revision 518 by ph10, Tue May 18 15:47:01 2010 UTC revision 598 by ph10, Sat May 7 15:37:31 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 618  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 636  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    PCRE_UCP
674  .sp  .sp
675  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,
676  POSIX character classes. By default, only ASCII characters are recognized, but  \ew, and some of the POSIX character classes. By default, only ASCII characters
677  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
678  More details are given in the section on  classify characters. More details are given in the section on
679  .\" HTML <a href="pcre.html#genericchartypes">  .\" HTML <a href="pcre.html#genericchartypes">
680  .\" </a>  .\" </a>
681  generic character types  generic character types
# Line 759  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 772  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    67  this version of PCRE is not compiled with PCRE_UCP support
814  .sp  .sp
# Line 840  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 900  one in which it was compiled. Passing ta Line 946  one in which it was compiled. Passing ta
946  below in the section on matching a pattern.  below in the section on matching a pattern.
947  .  .
948  .  .
949    .\" HTML <a name="infoaboutpattern"></a>
950  .SH "INFORMATION ABOUT A PATTERN"  .SH "INFORMATION ABOUT A PATTERN"
951  .rs  .rs
952  .sp  .sp
# Line 1432  the Line 1479  the
1479  .\" HREF  .\" HREF
1480  \fBpcredemo\fP  \fBpcredemo\fP
1481  .\"  .\"
1482  sample program.  sample program. In the most general case, you have to check to see if the
1483    newline convention recognizes CRLF as a newline, and if so, and the current
1484    character is CR followed by LF, advance the starting offset by two characters
1485    instead of one.
1486  .sp  .sp
1487    PCRE_NO_START_OPTIMIZE    PCRE_NO_START_OPTIMIZE
1488  .sp  .sp
1489  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
1490  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
1491  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
1492  character, and fails immediately if it cannot find it, without actually running  for that character, and fails immediately if it cannot find it, without
1493  the main matching function. When callouts are in use, these optimizations can  actually running the main matching function. This means that a special item
1494  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
1495  causing performance to suffer, but ensuring that the callouts do occur.  suitable starting point for the match has been found. When callouts or (*MARK)
1496    items are in use, these "start-up" optimizations can cause them to be skipped
1497    if the pattern is never actually used. The start-up optimizations are in effect
1498    a pre-scan of the subject that takes place before the pattern is run.
1499    .P
1500    The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
1501    causing performance to suffer, but ensuring that in cases where the result is
1502    "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
1503    are considered at every possible starting position in the subject string. If
1504    PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
1505    time.
1506    .P
1507    Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
1508    Consider the pattern
1509    .sp
1510      (*COMMIT)ABC
1511    .sp
1512    When this is compiled, PCRE records the fact that a match must start with the
1513    character "A". Suppose the subject string is "DEFABC". The start-up
1514    optimization scans along the subject, finds "A" and runs the first match
1515    attempt from there. The (*COMMIT) item means that the pattern must match the
1516    current starting position, which in this case, it does. However, if the same
1517    match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
1518    subject string does not happen. The first match attempt is run starting from
1519    "D" and when this fails, (*COMMIT) prevents any further matches being tried, so
1520    the overall result is "no match". If the pattern is studied, more start-up
1521    optimizations may be used. For example, a minimum length for the subject may be
1522    recorded. Consider the pattern
1523    .sp
1524      (*MARK:A)(X|Y)
1525    .sp
1526    The minimum length for a match is one character. If the subject is "ABC", there
1527    will be attempts to match "ABC", "BC", "C", and then finally an empty string.
1528    If the pattern is studied, the final attempt does not take place, because PCRE
1529    knows that the subject is too short, and so the (*MARK) is never encountered.
1530    In this case, studying the pattern does not affect the overall match result,
1531    which is still "no match", but it does affect the auxiliary information that is
1532    returned.
1533  .sp  .sp
1534    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1535  .sp  .sp
# Line 1460  in the main Line 1547  in the main
1547  \fBpcre\fP  \fBpcre\fP
1548  .\"  .\"
1549  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
1550  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
1551  PCRE_ERROR_BADUTF8_OFFSET is returned.  a truncated UTF-8 character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
1552    both cases, information about the precise nature of the error may also be
1553    returned (see the descriptions of these errors in the section entitled \fIError
1554    return values from\fP \fBpcre_exec()\fP
1555    .\" HTML <a href="#errorlist">
1556    .\" </a>
1557    below).
1558    .\"
1559    If \fIstartoffset\fP contains a value that does not point to the start of a
1560    UTF-8 character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
1561    returned.
1562  .P  .P
1563  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
1564  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
1565  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
1566  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
1567  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
1568  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
1569  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
1570  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
1571  UTF-8 character, is undefined. Your program may crash.  undefined. Your program may crash.
1572  .sp  .sp
1573    PCRE_PARTIAL_HARD    PCRE_PARTIAL_HARD
1574    PCRE_PARTIAL_SOFT    PCRE_PARTIAL_SOFT
# Line 1480  These options turn on the partial matchi Line 1577  These options turn on the partial matchi
1577  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
1578  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
1579  not enough subject characters to complete the match. If this happens when  not enough subject characters to complete the match. If this happens when
1580  PCRE_PARTIAL_HARD is set, \fBpcre_exec()\fP immediately returns  PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set, matching continues by
1581  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
1582  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,
1583  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,
1584  was inspected when the partial match was found is set as the first matching  but only if no complete match can be found.
1585  string. There is a more detailed discussion in the  .P
1586    If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
1587    partial match is found, \fBpcre_exec()\fP immediately returns
1588    PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
1589    when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
1590    important that an alternative complete match.
1591    .P
1592    In both cases, the portion of the string that was inspected when the partial
1593    match was found is set as the first matching string. There is a more detailed
1594    discussion of partial and multi-segment matching, with examples, in the
1595  .\" HREF  .\" HREF
1596  \fBpcrepartial\fP  \fBpcrepartial\fP
1597  .\"  .\"
1598  documentation.  documentation.
1599  .  .
1600    .
1601  .SS "The string to be matched by \fBpcre_exec()\fP"  .SS "The string to be matched by \fBpcre_exec()\fP"
1602  .rs  .rs
1603  .sp  .sp
1604  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
1605  \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
1606  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
1607  a UTF-8 character. Unlike the pattern string, the subject may contain binary  subject, \fBpcre_exec()\fP returns PCRE_ERROR_BADOFFSET. When the starting
1608  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,
1609  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
1610    point to the start of a UTF-8 character (or the end of the subject). Unlike the
1611    pattern string, the subject may contain binary zero bytes.
1612  .P  .P
1613  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
1614  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 1519  start of the subject, which is deemed to Line 1628  start of the subject, which is deemed to
1628  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
1629  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.
1630  .P  .P
1631    Finding all the matches in a subject is tricky when the pattern can match an
1632    empty string. It is possible to emulate Perl's /g behaviour by first trying the
1633    match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
1634    PCRE_ANCHORED options, and then if that fails, advancing the starting offset
1635    and trying an ordinary match again. There is some code that demonstrates how to
1636    do this in the
1637    .\" HREF
1638    \fBpcredemo\fP
1639    .\"
1640    sample program. In the most general case, you have to check to see if the
1641    newline convention recognizes CRLF as a newline, and if so, and the current
1642    character is CR followed by LF, advance the starting offset by two characters
1643    instead of one.
1644    .P
1645  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
1646  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
1647  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.
1648  .  .
1649    .
1650  .SS "How \fBpcre_exec()\fP returns captured substrings"  .SS "How \fBpcre_exec()\fP returns captured substrings"
1651  .rs  .rs
1652  .sp  .sp
# Line 1589  Offset values that correspond to unused Line 1713  Offset values that correspond to unused
1713  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
1714  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
1715  return from the function is 2, because the highest used capturing subpattern  return from the function is 2, because the highest used capturing subpattern
1716  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
1717  capturing subpatterns if you wish (assuming the vector is large enough, of  (assuming the vector is large enough, of course) are set to -1.
1718  course).  .P
1719    \fBNote\fP: Elements of \fIovector\fP that do not correspond to capturing
1720    parentheses in the pattern are never changed. That is, if a pattern contains
1721    \fIn\fP capturing parentheses, no more than \fIovector[0]\fP to
1722    \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other elements retain
1723    whatever values they previously had.
1724  .P  .P
1725  Some convenience functions are provided for extracting the captured substrings  Some convenience functions are provided for extracting the captured substrings
1726  as separate strings. These are described below.  as separate strings. These are described below.
1727  .  .
1728    .
1729  .\" HTML <a name="errorlist"></a>  .\" HTML <a name="errorlist"></a>
1730  .SS "Error return values from \fBpcre_exec()\fP"  .SS "Error return values from \fBpcre_exec()\fP"
1731  .rs  .rs
# Line 1637  If a pattern contains back references, b Line 1767  If a pattern contains back references, b
1767  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
1768  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
1769  automatically freed at the end of matching.  automatically freed at the end of matching.
1770    .P
1771    This error is also given if \fBpcre_stack_malloc()\fP fails in
1772    \fBpcre_exec()\fP. This can happen only when PCRE has been compiled with
1773    \fB--disable-stack-for-recursion\fP.
1774  .sp  .sp
1775    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1776  .sp  .sp
# Line 1661  documentation for details. Line 1795  documentation for details.
1795  .sp  .sp
1796    PCRE_ERROR_BADUTF8        (-10)    PCRE_ERROR_BADUTF8        (-10)
1797  .sp  .sp
1798  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,
1799    and the PCRE_NO_UTF8_CHECK option was not set. If the size of the output vector
1800    (\fIovecsize\fP) is at least 2, the byte offset to the start of the the invalid
1801    UTF-8 character is placed in the first element, and a reason code is placed in
1802    the second element. The reason codes are listed in the
1803    .\" HTML <a href="#badutf8reasons">
1804    .\" </a>
1805    following section.
1806    .\"
1807    For backward compatibility, if PCRE_PARTIAL_HARD is set and the problem is a
1808    truncated UTF-8 character at the end of the subject (reason codes 1 to 5),
1809    PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
1810  .sp  .sp
1811    PCRE_ERROR_BADUTF8_OFFSET (-11)    PCRE_ERROR_BADUTF8_OFFSET (-11)
1812  .sp  .sp
1813  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
1814  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
1815    \fIstartoffset\fP did not point to the beginning of a UTF-8 character or the
1816    end of the subject.
1817  .sp  .sp
1818    PCRE_ERROR_PARTIAL        (-12)    PCRE_ERROR_PARTIAL        (-12)
1819  .sp  .sp
# Line 1701  description above. Line 1848  description above.
1848    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
1849  .sp  .sp
1850  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
1851    .sp
1852      PCRE_ERROR_BADOFFSET      (-24)
1853    .sp
1854    The value of \fIstartoffset\fP was negative or greater than the length of the
1855    subject, that is, the value in \fIlength\fP.
1856    .sp
1857      PCRE_ERROR_SHORTUTF8      (-25)
1858    .sp
1859    This error is returned instead of PCRE_ERROR_BADUTF8 when the subject string
1860    ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD option is set.
1861    Information about the failure is returned as for PCRE_ERROR_BADUTF8. It is in
1862    fact sufficient to detect this case, but this special error code for
1863    PCRE_PARTIAL_HARD precedes the implementation of returned information; it is
1864    retained for backwards compatibility.
1865  .P  .P
1866  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.
1867  .  .
1868  .  .
1869    .\" HTML <a name="badutf8reasons"></a>
1870    .SS "Reason codes for invalid UTF-8 strings"
1871    .rs
1872    .sp
1873    When \fBpcre_exec()\fP returns either PCRE_ERROR_BADUTF8 or
1874    PCRE_ERROR_SHORTUTF8, and the size of the output vector (\fIovecsize\fP) is at
1875    least 2, the offset of the start of the invalid UTF-8 character is placed in
1876    the first output vector element (\fIovector[0]\fP) and a reason code is placed
1877    in the second element (\fIovector[1]\fP). The reason codes are given names in
1878    the \fBpcre.h\fP header file:
1879    .sp
1880      PCRE_UTF8_ERR1
1881      PCRE_UTF8_ERR2
1882      PCRE_UTF8_ERR3
1883      PCRE_UTF8_ERR4
1884      PCRE_UTF8_ERR5
1885    .sp
1886    The string ends with a truncated UTF-8 character; the code specifies how many
1887    bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8 characters to be
1888    no longer than 4 bytes, the encoding scheme (originally defined by RFC 2279)
1889    allows for up to 6 bytes, and this is checked first; hence the possibility of
1890    4 or 5 missing bytes.
1891    .sp
1892      PCRE_UTF8_ERR6
1893      PCRE_UTF8_ERR7
1894      PCRE_UTF8_ERR8
1895      PCRE_UTF8_ERR9
1896      PCRE_UTF8_ERR10
1897    .sp
1898    The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of the
1899    character do not have the binary value 0b10 (that is, either the most
1900    significant bit is 0, or the next bit is 1).
1901    .sp
1902      PCRE_UTF8_ERR11
1903      PCRE_UTF8_ERR12
1904    .sp
1905    A character that is valid by the RFC 2279 rules is either 5 or 6 bytes long;
1906    these code points are excluded by RFC 3629.
1907    .sp
1908      PCRE_UTF8_ERR13
1909    .sp
1910    A 4-byte character has a value greater than 0x10fff; these code points are
1911    excluded by RFC 3629.
1912    .sp
1913      PCRE_UTF8_ERR14
1914    .sp
1915    A 3-byte character has a value in the range 0xd800 to 0xdfff; this range of
1916    code points are reserved by RFC 3629 for use with UTF-16, and so are excluded
1917    from UTF-8.
1918    .sp
1919      PCRE_UTF8_ERR15
1920      PCRE_UTF8_ERR16
1921      PCRE_UTF8_ERR17
1922      PCRE_UTF8_ERR18
1923      PCRE_UTF8_ERR19
1924    .sp
1925    A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes for a
1926    value that can be represented by fewer bytes, which is invalid. For example,
1927    the two bytes 0xc0, 0xae give the value 0x2e, whose correct coding uses just
1928    one byte.
1929    .sp
1930      PCRE_UTF8_ERR20
1931    .sp
1932    The two most significant bits of the first byte of a character have the binary
1933    value 0b10 (that is, the most significant bit is 1 and the second is 0). Such a
1934    byte can only validly occur as the second or subsequent byte of a multi-byte
1935    character.
1936    .sp
1937      PCRE_UTF8_ERR21
1938    .sp
1939    The first byte of a character has the value 0xfe or 0xff. These values can
1940    never occur in a valid UTF-8 string.
1941    .
1942    .
1943  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
1944  .rs  .rs
1945  .sp  .sp
# Line 1900  fourth are pointers to variables which a Line 2135  fourth are pointers to variables which a
2135  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
2136  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
2137  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
2138  described above in the section entitled \fIInformation about a pattern\fP.  described above in the section entitled \fIInformation about a pattern\fP
2139    .\" HTML <a href="#infoaboutpattern">
2140    .\" </a>
2141    above.
2142    .\"
2143  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
2144  numbers, and hence the captured data, if any.  numbers, and hence the captured data, if any.
2145  .  .
# Line 1985  Here is an example of a simple call to \ Line 2224  Here is an example of a simple call to \
2224  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
2225  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,
2226  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
2227  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,
2228  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.
2229  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,
2230    so their description is not repeated here.
2231  .sp  .sp
2232    PCRE_PARTIAL_HARD    PCRE_PARTIAL_HARD
2233    PCRE_PARTIAL_SOFT    PCRE_PARTIAL_SOFT
# Line 2002  is converted into PCRE_ERROR_PARTIAL if Line 2242  is converted into PCRE_ERROR_PARTIAL if
2242  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
2243  possibility. The portion of the string that was inspected when the longest  possibility. The portion of the string that was inspected when the longest
2244  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.
2245    There is a more detailed discussion of partial and multi-segment matching, with
2246    examples, in the
2247    .\" HREF
2248    \fBpcrepartial\fP
2249    .\"
2250    documentation.
2251  .sp  .sp
2252    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
2253  .sp  .sp
# Line 2023  match. There is more discussion of this Line 2269  match. There is more discussion of this
2269  .\"  .\"
2270  documentation.  documentation.
2271  .  .
2272    .
2273  .SS "Successful returns from \fBpcre_dfa_exec()\fP"  .SS "Successful returns from \fBpcre_dfa_exec()\fP"
2274  .rs  .rs
2275  .sp  .sp
# Line 2056  matching string is given first. If there Line 2303  matching string is given first. If there
2303  \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
2304  the longest matches.  the longest matches.
2305  .  .
2306    .
2307  .SS "Error returns from \fBpcre_dfa_exec()\fP"  .SS "Error returns from \fBpcre_dfa_exec()\fP"
2308  .rs  .rs
2309  .sp  .sp
# Line 2121  Cambridge CB2 3QH, England. Line 2369  Cambridge CB2 3QH, England.
2369  .rs  .rs
2370  .sp  .sp
2371  .nf  .nf
2372  Last updated: 16 May 2010  Last updated: 07 May 2011
2373  Copyright (c) 1997-2010 University of Cambridge.  Copyright (c) 1997-2011 University of Cambridge.
2374  .fi  .fi

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