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revision 336 by ph10, Sat Apr 12 15:59:03 2008 UTC revision 454 by ph10, Tue Sep 22 09:42:11 2009 UTC
# Line 135  Applications can use these to include su Line 135  Applications can use these to include su
135  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,
136  and \fBpcre_exec()\fP are used for compiling and matching regular expressions  and \fBpcre_exec()\fP are used for compiling and matching regular expressions
137  in a Perl-compatible manner. A sample program that demonstrates the simplest  in a Perl-compatible manner. A sample program that demonstrates the simplest
138  way of using them is provided in the file called \fIpcredemo.c\fP in the source  way of using them is provided in the file called \fIpcredemo.c\fP in the PCRE
139  distribution. The  source distribution. A listing of this program is given in the
140    .\" HREF
141    \fBpcredemo\fP
142    .\"
143    documentation, and the
144  .\" HREF  .\" HREF
145  \fBpcresample\fP  \fBpcresample\fP
146  .\"  .\"
# Line 145  documentation describes how to compile a Line 149  documentation describes how to compile a
149  A second matching function, \fBpcre_dfa_exec()\fP, which is not  A second matching function, \fBpcre_dfa_exec()\fP, which is not
150  Perl-compatible, is also provided. This uses a different algorithm for the  Perl-compatible, is also provided. This uses a different algorithm for the
151  matching. The alternative algorithm finds all possible matches (at a given  matching. The alternative algorithm finds all possible matches (at a given
152  point in the subject), and scans the subject just once. However, this algorithm  point in the subject), and scans the subject just once (unless there are
153  does not return captured substrings. A description of the two matching  lookbehind assertions). However, this algorithm does not return captured
154  algorithms and their advantages and disadvantages is given in the  substrings. A description of the two matching algorithms and their advantages
155    and disadvantages is given in the
156  .\" HREF  .\" HREF
157  \fBpcrematching\fP  \fBpcrematching\fP
158  .\"  .\"
# Line 317  properties is available; otherwise it is Line 322  properties is available; otherwise it is
322  .sp  .sp
323  The output is an integer whose value specifies the default character sequence  The output is an integer whose value specifies the default character sequence
324  that is recognized as meaning "newline". The four values that are supported  that is recognized as meaning "newline". The four values that are supported
325  are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF, and -1 for ANY. The  are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF, and -1 for ANY.
326  default should normally be the standard sequence for your operating system.  Though they are derived from ASCII, the same values are returned in EBCDIC
327    environments. The default should normally correspond to the standard sequence
328    for your operating system.
329  .sp  .sp
330    PCRE_CONFIG_BSR    PCRE_CONFIG_BSR
331  .sp  .sp
# Line 347  documentation. Line 354  documentation.
354  .sp  .sp
355    PCRE_CONFIG_MATCH_LIMIT    PCRE_CONFIG_MATCH_LIMIT
356  .sp  .sp
357  The output is an integer that gives the default limit for the number of  The output is a long integer that gives the default limit for the number of
358  internal matching function calls in a \fBpcre_exec()\fP execution. Further  internal matching function calls in a \fBpcre_exec()\fP execution. Further
359  details are given with \fBpcre_exec()\fP below.  details are given with \fBpcre_exec()\fP below.
360  .sp  .sp
361    PCRE_CONFIG_MATCH_LIMIT_RECURSION    PCRE_CONFIG_MATCH_LIMIT_RECURSION
362  .sp  .sp
363  The output is an integer that gives the default limit for the depth of  The output is a long integer that gives the default limit for the depth of
364  recursion when calling the internal matching function in a \fBpcre_exec()\fP  recursion when calling the internal matching function in a \fBpcre_exec()\fP
365  execution. Further details are given with \fBpcre_exec()\fP below.  execution. Further details are given with \fBpcre_exec()\fP below.
366  .sp  .sp
# Line 404  argument, which is an address (see below Line 411  argument, which is an address (see below
411  .P  .P
412  The \fIoptions\fP argument contains various bit settings that affect the  The \fIoptions\fP argument contains various bit settings that affect the
413  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
414  options are described below. Some of them, in particular, those that are  options are described below. Some of them (in particular, those that are
415  compatible with Perl, can also be set and unset from within the pattern (see  compatible with Perl, but also some others) can also be set and unset from
416  the detailed description in the  within the pattern (see the detailed description in the
417  .\" HREF  .\" HREF
418  \fBpcrepattern\fP  \fBpcrepattern\fP
419  .\"  .\"
420  documentation). For these options, the contents of the \fIoptions\fP argument  documentation). For those options that can be different in different parts of
421  specifies their initial settings at the start of compilation and execution. The  the pattern, the contents of the \fIoptions\fP argument specifies their initial
422  PCRE_ANCHORED and PCRE_NEWLINE_\fIxxx\fP options can be set at the time of  settings at the start of compilation and execution. The PCRE_ANCHORED and
423  matching as well as at compile time.  PCRE_NEWLINE_\fIxxx\fP options can be set at the time of matching as well as at
424    compile time.
425  .P  .P
426  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
427  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
428  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
429  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
430  not try to free it. The offset from the start of the pattern to the character  not try to free it. The byte offset from the start of the pattern to the
431  where the error was discovered is placed in the variable pointed to by  character that was being processes when the error was discovered is placed in
432  \fIerroffset\fP, which must not be NULL. If it is, an immediate error is given.  the variable pointed to by \fIerroffset\fP, which must not be NULL. If it is,
433    an immediate error is given. Some errors are not detected until checks are
434    carried out when the whole pattern has been scanned; in this case the offset is
435    set to the end of the pattern.
436  .P  .P
437  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
438  \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 551  over the newline. Line 562  over the newline.
562  .sp  .sp
563    PCRE_JAVASCRIPT_COMPAT    PCRE_JAVASCRIPT_COMPAT
564  .sp  .sp
565  If this option is set, PCRE's behaviour is changed in some ways so that it is  If this option is set, PCRE's behaviour is changed in some ways so that it is
566  compatible with JavaScript rather than Perl. The changes are as follows:  compatible with JavaScript rather than Perl. The changes are as follows:
567  .P  .P
568  (1) A lone closing square bracket in a pattern causes a compile-time error,  (1) A lone closing square bracket in a pattern causes a compile-time error,
# Line 559  because this is illegal in JavaScript (b Line 570  because this is illegal in JavaScript (b
570  character). Thus, the pattern AB]CD becomes illegal when this option is set.  character). Thus, the pattern AB]CD becomes illegal when this option is set.
571  .P  .P
572  (2) At run time, a back reference to an unset subpattern group matches an empty  (2) At run time, a back reference to an unset subpattern group matches an empty
573  string (by default this causes the current matching path to fail). A pattern  string (by default this causes the current matching alternative to fail). A
574  such as (\1)(a) succeeds when this option is set (assuming it can find an "a"  pattern such as (\e1)(a) succeeds when this option is set (assuming it can find
575  in the subject), whereas it fails by default, for Perl compatibility.  an "a" in the subject), whereas it fails by default, for Perl compatibility.
576  .sp  .sp
577    PCRE_MULTILINE    PCRE_MULTILINE
578  .sp  .sp
# Line 731  out of use. To avoid confusion, they hav Line 742  out of use. To avoid confusion, they hav
742    54  DEFINE group contains more than one branch    54  DEFINE group contains more than one branch
743    55  repeating a DEFINE group is not allowed    55  repeating a DEFINE group is not allowed
744    56  inconsistent NEWLINE options    56  inconsistent NEWLINE options
745    57  \eg is not followed by a braced, angle-bracketed, or quoted    57  \eg is not followed by a braced, angle-bracketed, or quoted
746          name/number or by a plain number          name/number or by a plain number
747    58  a numbered reference must not be zero    58  a numbered reference must not be zero
748    59  (*VERB) with an argument is not supported    59  (*VERB) with an argument is not supported
749    60  (*VERB) not recognized    60  (*VERB) not recognized
# Line 1004  different for each compiled pattern. Line 1015  different for each compiled pattern.
1015  .sp  .sp
1016    PCRE_INFO_OKPARTIAL    PCRE_INFO_OKPARTIAL
1017  .sp  .sp
1018  Return 1 if the pattern can be used for partial matching, otherwise 0. The  Return 1 if the pattern can be used for partial matching with
1019  fourth argument should point to an \fBint\fP variable. The  \fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
1020    \fBint\fP variable. From release 8.00, this always returns 1, because the
1021    restrictions that previously applied to partial matching have been lifted. The
1022  .\" HREF  .\" HREF
1023  \fBpcrepartial\fP  \fBpcrepartial\fP
1024  .\"  .\"
1025  documentation lists the restrictions that apply to patterns when partial  documentation gives details of partial matching.
 matching is used.  
1026  .sp  .sp
1027    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1028  .sp  .sp
# Line 1210  with a \fBpcre_extra\fP block in which \ Line 1222  with a \fBpcre_extra\fP block in which \
1222  PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the \fIflags\fP field. If the limit  PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the \fIflags\fP field. If the limit
1223  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1224  .P  .P
1225  The \fIpcre_callout\fP field is used in conjunction with the "callout" feature,  The \fIcallout_data\fP field is used in conjunction with the "callout" feature,
1226  which is described in the  and is described in the
1227  .\" HREF  .\" HREF
1228  \fBpcrecallout\fP  \fBpcrecallout\fP
1229  .\"  .\"
# Line 1237  documentation for a discussion of saving Line 1249  documentation for a discussion of saving
1249  .sp  .sp
1250  The unused bits of the \fIoptions\fP argument for \fBpcre_exec()\fP must be  The unused bits of the \fIoptions\fP argument for \fBpcre_exec()\fP must be
1251  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,
1252  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1253    PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
1254    PCRE_PARTIAL_HARD.
1255  .sp  .sp
1256    PCRE_ANCHORED    PCRE_ANCHORED
1257  .sp  .sp
# Line 1312  match the empty string, the entire match Line 1326  match the empty string, the entire match
1326  .sp  .sp
1327    a?b?    a?b?
1328  .sp  .sp
1329  is applied to a string not beginning with "a" or "b", it matches the empty  is applied to a string not beginning with "a" or "b", it matches an empty
1330  string at the start of the subject. With PCRE_NOTEMPTY set, this match is not  string at the start of the subject. With PCRE_NOTEMPTY set, this match is not
1331  valid, so PCRE searches further into the string for occurrences of "a" or "b".  valid, so PCRE searches further into the string for occurrences of "a" or "b".
1332  .P  .sp
1333  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case    PCRE_NOTEMPTY_ATSTART
1334  of a pattern match of the empty string within its \fBsplit()\fP function, and  .sp
1335  when using the /g modifier. It is possible to emulate Perl's behaviour after  This is like PCRE_NOTEMPTY, except that an empty string match that is not at
1336  matching a null string by first trying the match again at the same offset with  the start of the subject is permitted. If the pattern is anchored, such a match
1337  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the  can occur only if the pattern contains \eK.
1338  starting offset (see below) and trying an ordinary match again. There is some  .P
1339  code that demonstrates how to do this in the \fIpcredemo.c\fP sample program.  Perl has no direct equivalent of PCRE_NOTEMPTY or PCRE_NOTEMPTY_ATSTART, but it
1340    does make a special case of a pattern match of the empty string within its
1341    \fBsplit()\fP function, and when using the /g modifier. It is possible to
1342    emulate Perl's behaviour after matching a null string by first trying the match
1343    again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
1344    if that fails, by advancing the starting offset (see below) and trying an
1345    ordinary match again. There is some code that demonstrates how to do this in
1346    the
1347    .\" HREF
1348    \fBpcredemo\fP
1349    .\"
1350    sample program.
1351    .sp
1352      PCRE_NO_START_OPTIMIZE
1353    .sp
1354    There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1355    a match, in order to speed up the process. For example, if it is known that a
1356    match must start with a specific character, it searches the subject for that
1357    character, and fails immediately if it cannot find it, without actually running
1358    the main matching function. When callouts are in use, these optimizations can
1359    cause them to be skipped. This option disables the "start-up" optimizations,
1360    causing performance to suffer, but ensuring that the callouts do occur.
1361  .sp  .sp
1362    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1363  .sp  .sp
# Line 1353  PCRE_NO_UTF8_CHECK is set, the effect of Line 1388  PCRE_NO_UTF8_CHECK is set, the effect of
1388  subject, or a value of \fIstartoffset\fP that does not point to the start of a  subject, or a value of \fIstartoffset\fP that does not point to the start of a
1389  UTF-8 character, is undefined. Your program may crash.  UTF-8 character, is undefined. Your program may crash.
1390  .sp  .sp
1391    PCRE_PARTIAL    PCRE_PARTIAL_HARD
1392      PCRE_PARTIAL_SOFT
1393  .sp  .sp
1394  This option turns on the partial matching feature. If the subject string fails  These options turn on the partial matching feature. For backwards
1395  to match the pattern, but at some point during the matching process the end of  compatibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial match
1396  the subject was reached (that is, the subject partially matches the pattern and  occurs if the end of the subject string is reached successfully, but there are
1397  the failure to match occurred only because there were not enough subject  not enough subject characters to complete the match. If this happens when
1398  characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of  PCRE_PARTIAL_HARD is set, \fBpcre_exec()\fP immediately returns
1399  PCRE_ERROR_NOMATCH. When PCRE_PARTIAL is used, there are restrictions on what  PCRE_ERROR_PARTIAL. Otherwise, if PCRE_PARTIAL_SOFT is set, matching continues
1400  may appear in the pattern. These are discussed in the  by testing any other alternatives. Only if they all fail is PCRE_ERROR_PARTIAL
1401    returned (instead of PCRE_ERROR_NOMATCH). The portion of the string that
1402    was inspected when the partial match was found is set as the first matching
1403    string. There is a more detailed discussion in the
1404  .\" HREF  .\" HREF
1405  \fBpcrepartial\fP  \fBpcrepartial\fP
1406  .\"  .\"
# Line 1371  documentation. Line 1410  documentation.
1410  .rs  .rs
1411  .sp  .sp
1412  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
1413  \fIsubject\fP, a length in \fIlength\fP, and a starting byte offset in  \fIsubject\fP, a length (in bytes) in \fIlength\fP, and a starting byte offset
1414  \fIstartoffset\fP. In UTF-8 mode, the byte offset must point to the start of a  in \fIstartoffset\fP. In UTF-8 mode, the byte offset must point to the start of
1415  UTF-8 character. Unlike the pattern string, the subject may contain binary zero  a UTF-8 character. Unlike the pattern string, the subject may contain binary
1416  bytes. When the starting offset is zero, the search for a match starts at the  zero bytes. When the starting offset is zero, the search for a match starts at
1417  beginning of the subject, and this is by far the most common case.  the beginning of the subject, and this is by far the most common case.
1418  .P  .P
1419  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
1420  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 1409  pattern. Following the usage in Jeffrey Line 1448  pattern. Following the usage in Jeffrey
1448  a fragment of a pattern that picks out a substring. PCRE supports several other  a fragment of a pattern that picks out a substring. PCRE supports several other
1449  kinds of parenthesized subpattern that do not cause substrings to be captured.  kinds of parenthesized subpattern that do not cause substrings to be captured.
1450  .P  .P
1451  Captured substrings are returned to the caller via a vector of integer offsets  Captured substrings are returned to the caller via a vector of integers whose
1452  whose address is passed in \fIovector\fP. The number of elements in the vector  address is passed in \fIovector\fP. The number of elements in the vector is
1453  is passed in \fIovecsize\fP, which must be a non-negative number. \fBNote\fP:  passed in \fIovecsize\fP, which must be a non-negative number. \fBNote\fP: this
1454  this argument is NOT the size of \fIovector\fP in bytes.  argument is NOT the size of \fIovector\fP in bytes.
1455  .P  .P
1456  The first two-thirds of the vector is used to pass back captured substrings,  The first two-thirds of the vector is used to pass back captured substrings,
1457  each substring using a pair of integers. The remaining third of the vector is  each substring using a pair of integers. The remaining third of the vector is
1458  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
1459  and is not available for passing back information. The length passed in  and is not available for passing back information. The number passed in
1460  \fIovecsize\fP should always be a multiple of three. If it is not, it is  \fIovecsize\fP should always be a multiple of three. If it is not, it is
1461  rounded down.  rounded down.
1462  .P  .P
1463  When a match is successful, information about captured substrings is returned  When a match is successful, information about captured substrings is returned
1464  in pairs of integers, starting at the beginning of \fIovector\fP, and  in pairs of integers, starting at the beginning of \fIovector\fP, and
1465  continuing up to two-thirds of its length at the most. The first element of a  continuing up to two-thirds of its length at the most. The first element of
1466  pair is set to the offset of the first character in a substring, and the second  each pair is set to the byte offset of the first character in a substring, and
1467  is set to the offset of the first character after the end of a substring. The  the second is set to the byte offset of the first character after the end of a
1468  first pair, \fIovector[0]\fP and \fIovector[1]\fP, identify the portion of the  substring. \fBNote\fP: these values are always byte offsets, even in UTF-8
1469  subject string matched by the entire pattern. The next pair is used for the  mode. They are not character counts.
1470  first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fP  .P
1471  is one more than the highest numbered pair that has been set. For example, if  The first pair of integers, \fIovector[0]\fP and \fIovector[1]\fP, identify the
1472  two substrings have been captured, the returned value is 3. If there are no  portion of the subject string matched by the entire pattern. The next pair is
1473  capturing subpatterns, the return value from a successful match is 1,  used for the first capturing subpattern, and so on. The value returned by
1474  indicating that just the first pair of offsets has been set.  \fBpcre_exec()\fP is one more than the highest numbered pair that has been set.
1475    For example, if two substrings have been captured, the returned value is 3. If
1476    there are no capturing subpatterns, the return value from a successful match is
1477    1, indicating that just the first pair of offsets has been set.
1478  .P  .P
1479  If a capturing subpattern is matched repeatedly, it is the last portion of the  If a capturing subpattern is matched repeatedly, it is the last portion of the
1480  string that it matched that is returned.  string that it matched that is returned.
1481  .P  .P
1482  If the vector is too small to hold all the captured substring offsets, it is  If the vector is too small to hold all the captured substring offsets, it is
1483  used as far as possible (up to two-thirds of its length), and the function  used as far as possible (up to two-thirds of its length), and the function
1484  returns a value of zero. In particular, if the substring offsets are not of  returns a value of zero. If the substring offsets are not of interest,
1485  interest, \fBpcre_exec()\fP may be called with \fIovector\fP passed as NULL and  \fBpcre_exec()\fP may be called with \fIovector\fP passed as NULL and
1486  \fIovecsize\fP as zero. However, if the pattern contains back references and  \fIovecsize\fP as zero. However, if the pattern contains back references and
1487  the \fIovector\fP is not big enough to remember the related substrings, PCRE  the \fIovector\fP is not big enough to remember the related substrings, PCRE
1488  has to get additional memory for use during matching. Thus it is usually  has to get additional memory for use during matching. Thus it is usually
# Line 1551  documentation for details of partial mat Line 1593  documentation for details of partial mat
1593  .sp  .sp
1594    PCRE_ERROR_BADPARTIAL     (-13)    PCRE_ERROR_BADPARTIAL     (-13)
1595  .sp  .sp
1596  The PCRE_PARTIAL option was used with a compiled pattern containing items that  This code is no longer in use. It was formerly returned when the PCRE_PARTIAL
1597  are not supported for partial matching. See the  option was used with a compiled pattern containing items that were not
1598  .\" HREF  supported for partial matching. From release 8.00 onwards, there are no
1599  \fBpcrepartial\fP  restrictions on partial matching.
 .\"  
 documentation for details of partial matching.  
1600  .sp  .sp
1601    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
1602  .sp  .sp
# Line 1726  These functions call \fBpcre_get_stringn Line 1766  These functions call \fBpcre_get_stringn
1766  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
1767  appropriate. \fBNOTE:\fP If PCRE_DUPNAMES is set and there are duplicate names,  appropriate. \fBNOTE:\fP If PCRE_DUPNAMES is set and there are duplicate names,
1768  the behaviour may not be what you want (see the next section).  the behaviour may not be what you want (see the next section).
1769  .  .P
1770    \fBWarning:\fP If the pattern uses the "(?|" feature to set up multiple
1771    subpatterns with the same number, you cannot use names to distinguish them,
1772    because names are not included in the compiled code. The matching process uses
1773    only numbers.
1774  .  .
1775  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
1776  .rs  .rs
# Line 1802  a compiled pattern, using a matching alg Line 1846  a compiled pattern, using a matching alg
1846  just once, and does not backtrack. This has different characteristics to the  just once, and does not backtrack. This has different characteristics to the
1847  normal algorithm, and is not compatible with Perl. Some of the features of PCRE  normal algorithm, and is not compatible with Perl. Some of the features of PCRE
1848  patterns are not supported. Nevertheless, there are times when this kind of  patterns are not supported. Nevertheless, there are times when this kind of
1849  matching can be useful. For a discussion of the two matching algorithms, see  matching can be useful. For a discussion of the two matching algorithms, and a
1850  the  list of features that \fBpcre_dfa_exec()\fP does not support, see the
1851  .\" HREF  .\" HREF
1852  \fBpcrematching\fP  \fBpcrematching\fP
1853  .\"  .\"
# Line 1842  Here is an example of a simple call to \ Line 1886  Here is an example of a simple call to \
1886  .sp  .sp
1887  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
1888  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,
1889  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1890  PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last three of these are  PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST,
1891  the same as for \fBpcre_exec()\fP, so their description is not repeated here.  and PCRE_DFA_RESTART. All but the last four of these are exactly the same as
1892  .sp  for \fBpcre_exec()\fP, so their description is not repeated here.
1893    PCRE_PARTIAL  .sp
1894  .sp    PCRE_PARTIAL_HARD
1895  This has the same general effect as it does for \fBpcre_exec()\fP, but the    PCRE_PARTIAL_SOFT
1896  details are slightly different. When PCRE_PARTIAL is set for  .sp
1897  \fBpcre_dfa_exec()\fP, the return code PCRE_ERROR_NOMATCH is converted into  These have the same general effect as they do for \fBpcre_exec()\fP, but the
1898  PCRE_ERROR_PARTIAL if the end of the subject is reached, there have been no  details are slightly different. When PCRE_PARTIAL_HARD is set for
1899  complete matches, but there is still at least one matching possibility. The  \fBpcre_dfa_exec()\fP, it returns PCRE_ERROR_PARTIAL if the end of the subject
1900  portion of the string that provided the partial match is set as the first  is reached and there is still at least one matching possibility that requires
1901  matching string.  additional characters. This happens even if some complete matches have also
1902    been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
1903    is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
1904    there have been no complete matches, but there is still at least one matching
1905    possibility. The portion of the string that was inspected when the longest
1906    partial match was found is set as the first matching string in both cases.
1907  .sp  .sp
1908    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
1909  .sp  .sp
# Line 1865  matching point in the subject string. Line 1914  matching point in the subject string.
1914  .sp  .sp
1915    PCRE_DFA_RESTART    PCRE_DFA_RESTART
1916  .sp  .sp
1917  When \fBpcre_dfa_exec()\fP is called with the PCRE_PARTIAL option, and returns  When \fBpcre_dfa_exec()\fP returns a partial match, it is possible to call it
1918  a partial match, it is possible to call it again, with additional subject  again, with additional subject characters, and have it continue with the same
1919  characters, and have it continue with the same match. The PCRE_DFA_RESTART  match. The PCRE_DFA_RESTART option requests this action; when it is set, the
1920  option requests this action; when it is set, the \fIworkspace\fP and  \fIworkspace\fP and \fIwscount\fP options must reference the same vector as
1921  \fIwscount\fP options must reference the same vector as before because data  before because data about the match so far is left in them after a partial
1922  about the match so far is left in them after a partial match. There is more  match. There is more discussion of this facility in the
 discussion of this facility in the  
1923  .\" HREF  .\" HREF
1924  \fBpcrepartial\fP  \fBpcrepartial\fP
1925  .\"  .\"
# Line 1975  Cambridge CB2 3QH, England. Line 2023  Cambridge CB2 3QH, England.
2023  .rs  .rs
2024  .sp  .sp
2025  .nf  .nf
2026  Last updated: 12 April 2008  Last updated: 22 September 2009
2027  Copyright (c) 1997-2008 University of Cambridge.  Copyright (c) 1997-2009 University of Cambridge.
2028  .fi  .fi

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