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revision 440 by ph10, Wed Sep 9 10:14:40 2009 UTC revision 513 by ph10, Mon May 3 11:13:37 2010 UTC
# Line 395  avoiding the use of the stack. Line 395  avoiding the use of the stack.
395  Either of the functions \fBpcre_compile()\fP or \fBpcre_compile2()\fP can be  Either of the functions \fBpcre_compile()\fP or \fBpcre_compile2()\fP can be
396  called to compile a pattern into an internal form. The only difference between  called to compile a pattern into an internal form. The only difference between
397  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,
398  \fIerrorcodeptr\fP, via which a numerical error code can be returned.  \fIerrorcodeptr\fP, via which a numerical error code can be returned. To avoid
399    too much repetition, we refer just to \fBpcre_compile()\fP below, but the
400    information applies equally to \fBpcre_compile2()\fP.
401  .P  .P
402  The pattern is a C string terminated by a binary zero, and is passed in the  The pattern is a C string terminated by a binary zero, and is passed in the
403  \fIpattern\fP argument. A pointer to a single block of memory that is obtained  \fIpattern\fP argument. A pointer to a single block of memory that is obtained
# Line 412  argument, which is an address (see below Line 414  argument, which is an address (see below
414  The \fIoptions\fP argument contains various bit settings that affect the  The \fIoptions\fP argument contains various bit settings that affect the
415  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
416  options are described below. Some of them (in particular, those that are  options are described below. Some of them (in particular, those that are
417  compatible with Perl, but also some others) can also be set and unset from  compatible with Perl, but some others as well) can also be set and unset from
418  within the pattern (see the detailed description in the  within the pattern (see the detailed description in the
419  .\" HREF  .\" HREF
420  \fBpcrepattern\fP  \fBpcrepattern\fP
421  .\"  .\"
422  documentation). For those options that can be different in different parts of  documentation). For those options that can be different in different parts of
423  the pattern, the contents of the \fIoptions\fP argument specifies their initial  the pattern, the contents of the \fIoptions\fP argument specifies their
424  settings at the start of compilation and execution. The PCRE_ANCHORED and  settings at the start of compilation and execution. The PCRE_ANCHORED,
425  PCRE_NEWLINE_\fIxxx\fP options can be set at the time of matching as well as at  PCRE_BSR_\fIxxx\fP, and PCRE_NEWLINE_\fIxxx\fP options can be set at the time
426  compile time.  of matching as well as at compile time.
427  .P  .P
428  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
429  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
430  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
431  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
432  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
433  where the error was discovered is placed in the variable pointed to by  character that was being processed when the error was discovered is placed in
434  \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,
435    an immediate error is given. Some errors are not detected until checks are
436    carried out when the whole pattern has been scanned; in this case the offset is
437    set to the end of the pattern.
438  .P  .P
439  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
440  \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 548  set, any backslash in a pattern that is Line 553  set, any backslash in a pattern that is
553  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
554  expansion. By default, as in Perl, a backslash followed by a letter with no  expansion. By default, as in Perl, a backslash followed by a letter with no
555  special meaning is treated as a literal. (Perl can, however, be persuaded to  special meaning is treated as a literal. (Perl can, however, be persuaded to
556  give a warning for this.) There are at present no other features controlled by  give an error for this, by running it with the -w option.) There are at present
557  this option. It can also be set by a (?X) option setting within a pattern.  no other features controlled by this option. It can also be set by a (?X)
558    option setting within a pattern.
559  .sp  .sp
560    PCRE_FIRSTLINE    PCRE_FIRSTLINE
561  .sp  .sp
# Line 742  out of use. To avoid confusion, they hav Line 748  out of use. To avoid confusion, they hav
748    57  \eg is not followed by a braced, angle-bracketed, or quoted    57  \eg is not followed by a braced, angle-bracketed, or quoted
749          name/number or by a plain number          name/number or by a plain number
750    58  a numbered reference must not be zero    58  a numbered reference must not be zero
751    59  (*VERB) with an argument is not supported    59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
752    60  (*VERB) not recognized    60  (*VERB) not recognized
753    61  number is too big    61  number is too big
754    62  subpattern name expected    62  subpattern name expected
755    63  digit expected after (?+    63  digit expected after (?+
756    64  ] is an invalid data character in JavaScript compatibility mode    64  ] is an invalid data character in JavaScript compatibility mode
757      65  different names for subpatterns of the same number are not allowed
758      66  (*MARK) must have an argument
759  .sp  .sp
760  The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may  The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
761  be used if the limits were changed when PCRE was built.  be used if the limits were changed when PCRE was built.
# Line 769  help speed up matching, \fBpcre_study()\ Line 777  help speed up matching, \fBpcre_study()\
777  results of the study.  results of the study.
778  .P  .P
779  The returned value from \fBpcre_study()\fP can be passed directly to  The returned value from \fBpcre_study()\fP can be passed directly to
780  \fBpcre_exec()\fP. However, a \fBpcre_extra\fP block also contains other  \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. However, a \fBpcre_extra\fP block
781  fields that can be set by the caller before the block is passed; these are  also contains other fields that can be set by the caller before the block is
782  described  passed; these are described
783  .\" HTML <a href="#extradata">  .\" HTML <a href="#extradata">
784  .\" </a>  .\" </a>
785  below  below
786  .\"  .\"
787  in the section on matching a pattern.  in the section on matching a pattern.
788  .P  .P
789  If studying the pattern does not produce any additional information  If studying the pattern does not produce any useful information,
790  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program
791  wants to pass any of the other fields to \fBpcre_exec()\fP, it must set up its  wants to pass any of the other fields to \fBpcre_exec()\fP or
792  own \fBpcre_extra\fP block.  \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block.
793  .P  .P
794  The second argument of \fBpcre_study()\fP contains option bits. At present, no  The second argument of \fBpcre_study()\fP contains option bits. At present, no
795  options are defined, and this argument should always be zero.  options are defined, and this argument should always be zero.
# Line 801  This is a typical call to \fBpcre_study\ Line 809  This is a typical call to \fBpcre_study\
809      0,              /* no options exist */      0,              /* no options exist */
810      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
811  .sp  .sp
812  At present, studying a pattern is useful only for non-anchored patterns that do  Studying a pattern does two things: first, a lower bound for the length of
813  not have a single fixed starting character. A bitmap of possible starting  subject string that is needed to match the pattern is computed. This does not
814  bytes is created.  mean that there are any strings of that length that match, but it does
815    guarantee that no shorter strings match. The value is used by
816    \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP to avoid wasting time by trying to
817    match strings that are shorter than the lower bound. You can find out the value
818    in a calling program via the \fBpcre_fullinfo()\fP function.
819    .P
820    Studying a pattern is also useful for non-anchored patterns that do not have a
821    single fixed starting character. A bitmap of possible starting bytes is
822    created. This speeds up finding a position in the subject at which to start
823    matching.
824  .  .
825  .  .
826  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
# Line 968  follows something of variable length. Fo Line 985  follows something of variable length. Fo
985  /^a\ed+z\ed+/ the returned value is "z", but for /^a\edz\ed/ the returned value  /^a\ed+z\ed+/ the returned value is "z", but for /^a\edz\ed/ the returned value
986  is -1.  is -1.
987  .sp  .sp
988      PCRE_INFO_MINLENGTH
989    .sp
990    If the pattern was studied and a minimum length for matching subject strings
991    was computed, its value is returned. Otherwise the returned value is -1. The
992    value is a number of characters, not bytes (this may be relevant in UTF-8
993    mode). The fourth argument should point to an \fBint\fP variable. A
994    non-negative value is a lower bound to the length of any matching string. There
995    may not be any strings of that length that do actually match, but every string
996    that does match is at least that long.
997    .sp
998    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
999    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
1000    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
# Line 988  entry; both of these return an \fBint\fP Line 1015  entry; both of these return an \fBint\fP
1015  length of the longest name. PCRE_INFO_NAMETABLE returns a pointer to the first  length of the longest name. PCRE_INFO_NAMETABLE returns a pointer to the first
1016  entry of the table (a pointer to \fBchar\fP). The first two bytes of each entry  entry of the table (a pointer to \fBchar\fP). The first two bytes of each entry
1017  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
1018  rest of the entry is the corresponding name, zero terminated. The names are in  rest of the entry is the corresponding name, zero terminated.
1019  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of  .P
1020  their parentheses numbers. For example, consider the following pattern (assume  The names are in alphabetical order. Duplicate names may appear if (?| is used
1021  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  to create multiple groups with the same number, as described in the
1022    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1023    .\" </a>
1024    section on duplicate subpattern numbers
1025    .\"
1026    in the
1027    .\" HREF
1028    \fBpcrepattern\fP
1029    .\"
1030    page. Duplicate names for subpatterns with different numbers are permitted only
1031    if PCRE_DUPNAMES is set. In all cases of duplicate names, they appear in the
1032    table in the order in which they were found in the pattern. In the absence of
1033    (?| this is the order of increasing number; when (?| is used this is not
1034    necessarily the case because later subpatterns may have lower numbers.
1035    .P
1036    As a simple example of the name/number table, consider the following pattern
1037    (assume PCRE_EXTENDED is set, so white space - including newlines - is
1038    ignored):
1039  .sp  .sp
1040  .\" JOIN  .\" JOIN
1041    (?<date> (?<year>(\ed\ed)?\ed\ed) -    (?<date> (?<year>(\ed\ed)?\ed\ed) -
# Line 1056  variable. Line 1100  variable.
1100  Return the size of the data block pointed to by the \fIstudy_data\fP field in  Return the size of the data block pointed to by the \fIstudy_data\fP field in
1101  a \fBpcre_extra\fP block. That is, it is the value that was passed to  a \fBpcre_extra\fP block. That is, it is the value that was passed to
1102  \fBpcre_malloc()\fP when PCRE was getting memory into which to place the data  \fBpcre_malloc()\fP when PCRE was getting memory into which to place the data
1103  created by \fBpcre_study()\fP. The fourth argument should point to a  created by \fBpcre_study()\fP. If \fBpcre_extra\fP is NULL, or there is no
1104    study data, zero is returned. The fourth argument should point to a
1105  \fBsize_t\fP variable.  \fBsize_t\fP variable.
1106  .  .
1107  .  .
# Line 1118  is different. (This seems a highly unlik Line 1163  is different. (This seems a highly unlik
1163  .P  .P
1164  The function \fBpcre_exec()\fP is called to match a subject string against a  The function \fBpcre_exec()\fP is called to match a subject string against a
1165  compiled pattern, which is passed in the \fIcode\fP argument. If the  compiled pattern, which is passed in the \fIcode\fP argument. If the
1166  pattern has been studied, the result of the study should be passed in the  pattern was studied, the result of the study should be passed in the
1167  \fIextra\fP argument. This function is the main matching facility of the  \fIextra\fP argument. This function is the main matching facility of the
1168  library, and it operates in a Perl-like manner. For specialist use there is  library, and it operates in a Perl-like manner. For specialist use there is
1169  also an alternative matching function, which is described  also an alternative matching function, which is described
# Line 1168  fields (not necessarily in this order): Line 1213  fields (not necessarily in this order):
1213    unsigned long int \fImatch_limit_recursion\fP;    unsigned long int \fImatch_limit_recursion\fP;
1214    void *\fIcallout_data\fP;    void *\fIcallout_data\fP;
1215    const unsigned char *\fItables\fP;    const unsigned char *\fItables\fP;
1216      unsigned char **\fImark\fP;
1217  .sp  .sp
1218  The \fIflags\fP field is a bitmap that specifies which of the other fields  The \fIflags\fP field is a bitmap that specifies which of the other fields
1219  are set. The flag bits are:  are set. The flag bits are:
# Line 1177  are set. The flag bits are: Line 1223  are set. The flag bits are:
1223    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1224    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1225    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1226      PCRE_EXTRA_MARK
1227  .sp  .sp
1228  Other flag bits should be set to zero. The \fIstudy_data\fP field is set in the  Other flag bits should be set to zero. The \fIstudy_data\fP field is set in the
1229  \fBpcre_extra\fP block that is returned by \fBpcre_study()\fP, together with  \fBpcre_extra\fP block that is returned by \fBpcre_study()\fP, together with
# Line 1186  the block by setting the other fields an Line 1233  the block by setting the other fields an
1233  The \fImatch_limit\fP field provides a means of preventing PCRE from using up a  The \fImatch_limit\fP field provides a means of preventing PCRE from using up a
1234  vast amount of resources when running patterns that are not going to match,  vast amount of resources when running patterns that are not going to match,
1235  but which have a very large number of possibilities in their search trees. The  but which have a very large number of possibilities in their search trees. The
1236  classic example is the use of nested unlimited repeats.  classic example is a pattern that uses nested unlimited repeats.
1237  .P  .P
1238  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly
1239  (sometimes recursively). The limit set by \fImatch_limit\fP is imposed on the  (sometimes recursively). The limit set by \fImatch_limit\fP is imposed on the
# Line 1239  called. See the Line 1286  called. See the
1286  \fBpcreprecompile\fP  \fBpcreprecompile\fP
1287  .\"  .\"
1288  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1289    .P
1290    If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1291    be set to point to a \fBchar *\fP variable. If the pattern contains any
1292    backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1293    a name to pass back, a pointer to the name string (zero terminated) is placed
1294    in the variable pointed to by the \fImark\fP field. The names are within the
1295    compiled pattern; if you wish to retain such a name you must copy it before
1296    freeing the memory of a compiled pattern. If there is no name to pass back, the
1297    variable pointed to by the \fImark\fP field set to NULL. For details of the
1298    backtracking control verbs, see the section entitled
1299    .\" HTML <a href="pcrepattern#backtrackcontrol">
1300    .\" </a>
1301    "Backtracking control"
1302    .\"
1303    in the
1304    .\" HREF
1305    \fBpcrepattern\fP
1306    .\"
1307    documentation.
1308    .
1309  .  .
1310  .\" HTML <a name="execoptions"></a>  .\" HTML <a name="execoptions"></a>
1311  .SS "Option bits for \fBpcre_exec()\fP"  .SS "Option bits for \fBpcre_exec()\fP"
# Line 1246  documentation for a discussion of saving Line 1313  documentation for a discussion of saving
1313  .sp  .sp
1314  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
1315  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,
1316  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_START_OPTIMIZE,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1317  PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and PCRE_PARTIAL_HARD.  PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
1318    PCRE_PARTIAL_HARD.
1319  .sp  .sp
1320    PCRE_ANCHORED    PCRE_ANCHORED
1321  .sp  .sp
# Line 1322  match the empty string, the entire match Line 1390  match the empty string, the entire match
1390  .sp  .sp
1391    a?b?    a?b?
1392  .sp  .sp
1393  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
1394  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
1395  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".
1396  .P  .sp
1397  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case    PCRE_NOTEMPTY_ATSTART
1398  of a pattern match of the empty string within its \fBsplit()\fP function, and  .sp
1399  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
1400  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
1401  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the  can occur only if the pattern contains \eK.
1402  starting offset (see below) and trying an ordinary match again. There is some  .P
1403  code that demonstrates how to do this in the  Perl has no direct equivalent of PCRE_NOTEMPTY or PCRE_NOTEMPTY_ATSTART, but it
1404    does make a special case of a pattern match of the empty string within its
1405    \fBsplit()\fP function, and when using the /g modifier. It is possible to
1406    emulate Perl's behaviour after matching a null string by first trying the match
1407    again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
1408    if that fails, by advancing the starting offset (see below) and trying an
1409    ordinary match again. There is some code that demonstrates how to do this in
1410    the
1411  .\" HREF  .\" HREF
1412  \fBpcredemo\fP  \fBpcredemo\fP
1413  .\"  .\"
# Line 1377  PCRE_NO_UTF8_CHECK is set, the effect of Line 1452  PCRE_NO_UTF8_CHECK is set, the effect of
1452  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
1453  UTF-8 character, is undefined. Your program may crash.  UTF-8 character, is undefined. Your program may crash.
1454  .sp  .sp
1455    PCRE_PARTIAL_HARD    PCRE_PARTIAL_HARD
1456    PCRE_PARTIAL_SOFT    PCRE_PARTIAL_SOFT
1457  .sp  .sp
1458  These options turn on the partial matching feature. For backwards  These options turn on the partial matching feature. For backwards
# Line 1477  the \fIovector\fP is not big enough to r Line 1552  the \fIovector\fP is not big enough to r
1552  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
1553  advisable to supply an \fIovector\fP.  advisable to supply an \fIovector\fP.
1554  .P  .P
1555  The \fBpcre_info()\fP function can be used to find out how many capturing  The \fBpcre_fullinfo()\fP function can be used to find out how many capturing
1556  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1557  \fIovector\fP that will allow for \fIn\fP captured substrings, in addition to  \fIovector\fP that will allow for \fIn\fP captured substrings, in addition to
1558  the offsets of the substring matched by the whole pattern, is (\fIn\fP+1)*3.  the offsets of the substring matched by the whole pattern, is (\fIn\fP+1)*3.
# Line 1584  documentation for details of partial mat Line 1659  documentation for details of partial mat
1659  .sp  .sp
1660  This code is no longer in use. It was formerly returned when the PCRE_PARTIAL  This code is no longer in use. It was formerly returned when the PCRE_PARTIAL
1661  option was used with a compiled pattern containing items that were not  option was used with a compiled pattern containing items that were not
1662  supported for partial matching. From release 8.00 onwards, there are no  supported for partial matching. From release 8.00 onwards, there are no
1663  restrictions on partial matching.  restrictions on partial matching.
1664  .sp  .sp
1665    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
# Line 1756  then call \fBpcre_copy_substring()\fP or Line 1831  then call \fBpcre_copy_substring()\fP or
1831  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,
1832  the behaviour may not be what you want (see the next section).  the behaviour may not be what you want (see the next section).
1833  .P  .P
1834  \fBWarning:\fP If the pattern uses the "(?|" feature to set up multiple  \fBWarning:\fP If the pattern uses the (?| feature to set up multiple
1835  subpatterns with the same number, you cannot use names to distinguish them,  subpatterns with the same number, as described in the
1836  because names are not included in the compiled code. The matching process uses  .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1837  only numbers.  .\" </a>
1838    section on duplicate subpattern numbers
1839    .\"
1840    in the
1841    .\" HREF
1842    \fBpcrepattern\fP
1843    .\"
1844    page, you cannot use names to distinguish the different subpatterns, because
1845    names are not included in the compiled code. The matching process uses only
1846    numbers. For this reason, the use of different names for subpatterns of the
1847    same number causes an error at compile time.
1848  .  .
1849  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
1850  .rs  .rs
# Line 1769  only numbers. Line 1854  only numbers.
1854  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
1855  .PP  .PP
1856  When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns  When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
1857  are not required to be unique. Normally, patterns with duplicate names are such  are not required to be unique. (Duplicate names are always allowed for
1858  that in any one match, only one of the named subpatterns participates. An  subpatterns with the same number, created by using the (?| feature. Indeed, if
1859  example is shown in the  such subpatterns are named, they are required to use the same names.)
1860    .P
1861    Normally, patterns with duplicate names are such that in any one match, only
1862    one of the named subpatterns participates. An example is shown in the
1863  .\" HREF  .\" HREF
1864  \fBpcrepattern\fP  \fBpcrepattern\fP
1865  .\"  .\"
# Line 1835  a compiled pattern, using a matching alg Line 1923  a compiled pattern, using a matching alg
1923  just once, and does not backtrack. This has different characteristics to the  just once, and does not backtrack. This has different characteristics to the
1924  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
1925  patterns are not supported. Nevertheless, there are times when this kind of  patterns are not supported. Nevertheless, there are times when this kind of
1926  matching can be useful. For a discussion of the two matching algorithms, and a  matching can be useful. For a discussion of the two matching algorithms, and a
1927  list of features that \fBpcre_dfa_exec()\fP does not support, see the  list of features that \fBpcre_dfa_exec()\fP does not support, see the
1928  .\" HREF  .\" HREF
1929  \fBpcrematching\fP  \fBpcrematching\fP
# Line 1875  Here is an example of a simple call to \ Line 1963  Here is an example of a simple call to \
1963  .sp  .sp
1964  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
1965  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,
1966  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1967  PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last  PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST,
1968  four of these are exactly the same as for \fBpcre_exec()\fP, so their  and PCRE_DFA_RESTART. All but the last four of these are exactly the same as
1969  description is not repeated here.  for \fBpcre_exec()\fP, so their description is not repeated here.
1970  .sp  .sp
1971    PCRE_PARTIAL_HARD    PCRE_PARTIAL_HARD
1972    PCRE_PARTIAL_SOFT    PCRE_PARTIAL_SOFT
1973  .sp  .sp
1974  These have the same general effect as they do for \fBpcre_exec()\fP, but the  These have the same general effect as they do for \fBpcre_exec()\fP, but the
1975  details are slightly different. When PCRE_PARTIAL_HARD is set for  details are slightly different. When PCRE_PARTIAL_HARD is set for
# Line 2012  Cambridge CB2 3QH, England. Line 2100  Cambridge CB2 3QH, England.
2100  .rs  .rs
2101  .sp  .sp
2102  .nf  .nf
2103  Last updated: 09 September 2009  Last updated: 03 May 2010
2104  Copyright (c) 1997-2009 University of Cambridge.  Copyright (c) 1997-2010 University of Cambridge.
2105  .fi  .fi

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