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revision 336 by ph10, Sat Apr 12 15:59:03 2008 UTC revision 512 by ph10, Tue Mar 30 11:11:52 2010 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 388  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 404  argument, which is an address (see below Line 413  argument, which is an address (see below
413  .P  .P
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, can also be set and unset from within the pattern (see  compatible with Perl, but some others as well) can also be set and unset from
418  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 these options, the contents of the \fIoptions\fP argument  documentation). For those options that can be different in different parts of
423  specifies their initial settings at the start of compilation and execution. The  the pattern, the contents of the \fIoptions\fP argument specifies their
424  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,
425  matching as well as at compile time.  PCRE_BSR_\fIxxx\fP, and PCRE_NEWLINE_\fIxxx\fP options can be set at the time
426    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 551  over the newline. Line 564  over the newline.
564  .sp  .sp
565    PCRE_JAVASCRIPT_COMPAT    PCRE_JAVASCRIPT_COMPAT
566  .sp  .sp
567  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
568  compatible with JavaScript rather than Perl. The changes are as follows:  compatible with JavaScript rather than Perl. The changes are as follows:
569  .P  .P
570  (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 572  because this is illegal in JavaScript (b
572  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.
573  .P  .P
574  (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
575  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
576  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
577  in the subject), whereas it fails by default, for Perl compatibility.  an "a" in the subject), whereas it fails by default, for Perl compatibility.
578  .sp  .sp
579    PCRE_MULTILINE    PCRE_MULTILINE
580  .sp  .sp
# Line 731  out of use. To avoid confusion, they hav Line 744  out of use. To avoid confusion, they hav
744    54  DEFINE group contains more than one branch    54  DEFINE group contains more than one branch
745    55  repeating a DEFINE group is not allowed    55  repeating a DEFINE group is not allowed
746    56  inconsistent NEWLINE options    56  inconsistent NEWLINE options
747    57  \eg is not followed by a braced, angle-bracketed, or quoted    57  \eg is not followed by a braced, angle-bracketed, or quoted
748          name/number or by a plain number          name/number or by a plain number
749    58  a numbered reference must not be zero    58  a numbered reference must not be zero
750    59  (*VERB) with an argument is not supported    59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
751    60  (*VERB) not recognized    60  (*VERB) not recognized
752    61  number is too big    61  number is too big
753    62  subpattern name expected    62  subpattern name expected
754    63  digit expected after (?+    63  digit expected after (?+
755    64  ] is an invalid data character in JavaScript compatibility mode    64  ] is an invalid data character in JavaScript compatibility mode
756      65  different names for subpatterns of the same number are not allowed
757      66  (*MARK) must have an argument
758  .sp  .sp
759  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
760  be used if the limits were changed when PCRE was built.  be used if the limits were changed when PCRE was built.
# Line 761  help speed up matching, \fBpcre_study()\ Line 776  help speed up matching, \fBpcre_study()\
776  results of the study.  results of the study.
777  .P  .P
778  The returned value from \fBpcre_study()\fP can be passed directly to  The returned value from \fBpcre_study()\fP can be passed directly to
779  \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
780  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
781  described  passed; these are described
782  .\" HTML <a href="#extradata">  .\" HTML <a href="#extradata">
783  .\" </a>  .\" </a>
784  below  below
785  .\"  .\"
786  in the section on matching a pattern.  in the section on matching a pattern.
787  .P  .P
788  If studying the pattern does not produce any additional information  If studying the pattern does not produce any useful information,
789  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program
790  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
791  own \fBpcre_extra\fP block.  \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block.
792  .P  .P
793  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
794  options are defined, and this argument should always be zero.  options are defined, and this argument should always be zero.
# Line 793  This is a typical call to \fBpcre_study\ Line 808  This is a typical call to \fBpcre_study\
808      0,              /* no options exist */      0,              /* no options exist */
809      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
810  .sp  .sp
811  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
812  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
813  bytes is created.  mean that there are any strings of that length that match, but it does
814    guarantee that no shorter strings match. The value is used by
815    \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP to avoid wasting time by trying to
816    match strings that are shorter than the lower bound. You can find out the value
817    in a calling program via the \fBpcre_fullinfo()\fP function.
818    .P
819    Studying a pattern is also useful for non-anchored patterns that do not have a
820    single fixed starting character. A bitmap of possible starting bytes is
821    created. This speeds up finding a position in the subject at which to start
822    matching.
823  .  .
824  .  .
825  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
# Line 960  follows something of variable length. Fo Line 984  follows something of variable length. Fo
984  /^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
985  is -1.  is -1.
986  .sp  .sp
987      PCRE_INFO_MINLENGTH
988    .sp
989    If the pattern was studied and a minimum length for matching subject strings
990    was computed, its value is returned. Otherwise the returned value is -1. The
991    value is a number of characters, not bytes (this may be relevant in UTF-8
992    mode). The fourth argument should point to an \fBint\fP variable. A
993    non-negative value is a lower bound to the length of any matching string. There
994    may not be any strings of that length that do actually match, but every string
995    that does match is at least that long.
996    .sp
997    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
998    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
999    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
# Line 980  entry; both of these return an \fBint\fP Line 1014  entry; both of these return an \fBint\fP
1014  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
1015  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
1016  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
1017  rest of the entry is the corresponding name, zero terminated. The names are in  rest of the entry is the corresponding name, zero terminated.
1018  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of  .P
1019  their parentheses numbers. For example, consider the following pattern (assume  The names are in alphabetical order. Duplicate names may appear if (?| is used
1020  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  to create multiple groups with the same number, as described in the
1021    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1022    .\" </a>
1023    section on duplicate subpattern numbers
1024    .\"
1025    in the
1026    .\" HREF
1027    \fBpcrepattern\fP
1028    .\"
1029    page. Duplicate names for subpatterns with different numbers are permitted only
1030    if PCRE_DUPNAMES is set. In all cases of duplicate names, they appear in the
1031    table in the order in which they were found in the pattern. In the absence of
1032    (?| this is the order of increasing number; when (?| is used this is not
1033    necessarily the case because later subpatterns may have lower numbers.
1034    .P
1035    As a simple example of the name/number table, consider the following pattern
1036    (assume PCRE_EXTENDED is set, so white space - including newlines - is
1037    ignored):
1038  .sp  .sp
1039  .\" JOIN  .\" JOIN
1040    (?<date> (?<year>(\ed\ed)?\ed\ed) -    (?<date> (?<year>(\ed\ed)?\ed\ed) -
# Line 1004  different for each compiled pattern. Line 1055  different for each compiled pattern.
1055  .sp  .sp
1056    PCRE_INFO_OKPARTIAL    PCRE_INFO_OKPARTIAL
1057  .sp  .sp
1058  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
1059  fourth argument should point to an \fBint\fP variable. The  \fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
1060    \fBint\fP variable. From release 8.00, this always returns 1, because the
1061    restrictions that previously applied to partial matching have been lifted. The
1062  .\" HREF  .\" HREF
1063  \fBpcrepartial\fP  \fBpcrepartial\fP
1064  .\"  .\"
1065  documentation lists the restrictions that apply to patterns when partial  documentation gives details of partial matching.
 matching is used.  
1066  .sp  .sp
1067    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1068  .sp  .sp
# Line 1047  variable. Line 1099  variable.
1099  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
1100  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
1101  \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
1102  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
1103    study data, zero is returned. The fourth argument should point to a
1104  \fBsize_t\fP variable.  \fBsize_t\fP variable.
1105  .  .
1106  .  .
# Line 1109  is different. (This seems a highly unlik Line 1162  is different. (This seems a highly unlik
1162  .P  .P
1163  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
1164  compiled pattern, which is passed in the \fIcode\fP argument. If the  compiled pattern, which is passed in the \fIcode\fP argument. If the
1165  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
1166  \fIextra\fP argument. This function is the main matching facility of the  \fIextra\fP argument. This function is the main matching facility of the
1167  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
1168  also an alternative matching function, which is described  also an alternative matching function, which is described
# Line 1159  fields (not necessarily in this order): Line 1212  fields (not necessarily in this order):
1212    unsigned long int \fImatch_limit_recursion\fP;    unsigned long int \fImatch_limit_recursion\fP;
1213    void *\fIcallout_data\fP;    void *\fIcallout_data\fP;
1214    const unsigned char *\fItables\fP;    const unsigned char *\fItables\fP;
1215      unsigned char **\fImark\fP;
1216  .sp  .sp
1217  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
1218  are set. The flag bits are:  are set. The flag bits are:
# Line 1168  are set. The flag bits are: Line 1222  are set. The flag bits are:
1222    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1223    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1224    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1225      PCRE_EXTRA_MARK
1226  .sp  .sp
1227  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
1228  \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 1177  the block by setting the other fields an Line 1232  the block by setting the other fields an
1232  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
1233  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,
1234  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
1235  classic example is the use of nested unlimited repeats.  classic example is a pattern that uses nested unlimited repeats.
1236  .P  .P
1237  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly
1238  (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 1210  with a \fBpcre_extra\fP block in which \ Line 1265  with a \fBpcre_extra\fP block in which \
1265  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
1266  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1267  .P  .P
1268  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,
1269  which is described in the  and is described in the
1270  .\" HREF  .\" HREF
1271  \fBpcrecallout\fP  \fBpcrecallout\fP
1272  .\"  .\"
# Line 1230  called. See the Line 1285  called. See the
1285  \fBpcreprecompile\fP  \fBpcreprecompile\fP
1286  .\"  .\"
1287  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1288    .P
1289    If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1290    be set to point to a \fBchar *\fP variable. If the pattern contains any
1291    backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1292    a name to pass back, a pointer to the name string (zero terminated) is placed
1293    in the variable pointed to by the \fImark\fP field. The names are within the
1294    compiled pattern; if you wish to retain such a name you must copy it before
1295    freeing the memory of a compiled pattern. If there is no name to pass back, the
1296    variable pointed to by the \fImark\fP field set to NULL. For details of the
1297    backtracking control verbs, see the section entitled
1298    .\" HTML <a href="pcrepattern#backtrackcontrol">
1299    .\" </a>
1300    "Backtracking control"
1301    .\"
1302    in the
1303    .\" HREF
1304    \fBpcrepattern\fP
1305    .\"
1306    documentation.
1307    .
1308  .  .
1309  .\" HTML <a name="execoptions"></a>  .\" HTML <a name="execoptions"></a>
1310  .SS "Option bits for \fBpcre_exec()\fP"  .SS "Option bits for \fBpcre_exec()\fP"
# Line 1237  documentation for a discussion of saving Line 1312  documentation for a discussion of saving
1312  .sp  .sp
1313  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
1314  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,
1315  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1316    PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
1317    PCRE_PARTIAL_HARD.
1318  .sp  .sp
1319    PCRE_ANCHORED    PCRE_ANCHORED
1320  .sp  .sp
# Line 1312  match the empty string, the entire match Line 1389  match the empty string, the entire match
1389  .sp  .sp
1390    a?b?    a?b?
1391  .sp  .sp
1392  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
1393  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
1394  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".
1395  .P  .sp
1396  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case    PCRE_NOTEMPTY_ATSTART
1397  of a pattern match of the empty string within its \fBsplit()\fP function, and  .sp
1398  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
1399  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
1400  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the  can occur only if the pattern contains \eK.
1401  starting offset (see below) and trying an ordinary match again. There is some  .P
1402  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
1403    does make a special case of a pattern match of the empty string within its
1404    \fBsplit()\fP function, and when using the /g modifier. It is possible to
1405    emulate Perl's behaviour after matching a null string by first trying the match
1406    again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
1407    if that fails, by advancing the starting offset (see below) and trying an
1408    ordinary match again. There is some code that demonstrates how to do this in
1409    the
1410    .\" HREF
1411    \fBpcredemo\fP
1412    .\"
1413    sample program.
1414    .sp
1415      PCRE_NO_START_OPTIMIZE
1416    .sp
1417    There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1418    a match, in order to speed up the process. For example, if it is known that a
1419    match must start with a specific character, it searches the subject for that
1420    character, and fails immediately if it cannot find it, without actually running
1421    the main matching function. When callouts are in use, these optimizations can
1422    cause them to be skipped. This option disables the "start-up" optimizations,
1423    causing performance to suffer, but ensuring that the callouts do occur.
1424  .sp  .sp
1425    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1426  .sp  .sp
# Line 1353  PCRE_NO_UTF8_CHECK is set, the effect of Line 1451  PCRE_NO_UTF8_CHECK is set, the effect of
1451  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
1452  UTF-8 character, is undefined. Your program may crash.  UTF-8 character, is undefined. Your program may crash.
1453  .sp  .sp
1454    PCRE_PARTIAL    PCRE_PARTIAL_HARD
1455      PCRE_PARTIAL_SOFT
1456  .sp  .sp
1457  This option turns on the partial matching feature. If the subject string fails  These options turn on the partial matching feature. For backwards
1458  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
1459  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
1460  the failure to match occurred only because there were not enough subject  not enough subject characters to complete the match. If this happens when
1461  characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of  PCRE_PARTIAL_HARD is set, \fBpcre_exec()\fP immediately returns
1462  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
1463  may appear in the pattern. These are discussed in the  by testing any other alternatives. Only if they all fail is PCRE_ERROR_PARTIAL
1464    returned (instead of PCRE_ERROR_NOMATCH). The portion of the string that
1465    was inspected when the partial match was found is set as the first matching
1466    string. There is a more detailed discussion in the
1467  .\" HREF  .\" HREF
1468  \fBpcrepartial\fP  \fBpcrepartial\fP
1469  .\"  .\"
# Line 1371  documentation. Line 1473  documentation.
1473  .rs  .rs
1474  .sp  .sp
1475  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
1476  \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
1477  \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
1478  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
1479  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
1480  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.
1481  .P  .P
1482  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
1483  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 1511  pattern. Following the usage in Jeffrey
1511  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
1512  kinds of parenthesized subpattern that do not cause substrings to be captured.  kinds of parenthesized subpattern that do not cause substrings to be captured.
1513  .P  .P
1514  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
1515  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
1516  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
1517  this argument is NOT the size of \fIovector\fP in bytes.  argument is NOT the size of \fIovector\fP in bytes.
1518  .P  .P
1519  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,
1520  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
1521  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
1522  and is not available for passing back information. The length passed in  and is not available for passing back information. The number passed in
1523  \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
1524  rounded down.  rounded down.
1525  .P  .P
1526  When a match is successful, information about captured substrings is returned  When a match is successful, information about captured substrings is returned
1527  in pairs of integers, starting at the beginning of \fIovector\fP, and  in pairs of integers, starting at the beginning of \fIovector\fP, and
1528  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
1529  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
1530  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
1531  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
1532  subject string matched by the entire pattern. The next pair is used for the  mode. They are not character counts.
1533  first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fP  .P
1534  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
1535  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
1536  capturing subpatterns, the return value from a successful match is 1,  used for the first capturing subpattern, and so on. The value returned by
1537  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.
1538    For example, if two substrings have been captured, the returned value is 3. If
1539    there are no capturing subpatterns, the return value from a successful match is
1540    1, indicating that just the first pair of offsets has been set.
1541  .P  .P
1542  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
1543  string that it matched that is returned.  string that it matched that is returned.
1544  .P  .P
1545  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
1546  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
1547  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,
1548  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
1549  \fIovecsize\fP as zero. However, if the pattern contains back references and  \fIovecsize\fP as zero. However, if the pattern contains back references and
1550  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
1551  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
1552  advisable to supply an \fIovector\fP.  advisable to supply an \fIovector\fP.
1553  .P  .P
1554  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
1555  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1556  \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
1557  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 1551  documentation for details of partial mat Line 1656  documentation for details of partial mat
1656  .sp  .sp
1657    PCRE_ERROR_BADPARTIAL     (-13)    PCRE_ERROR_BADPARTIAL     (-13)
1658  .sp  .sp
1659  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
1660  are not supported for partial matching. See the  option was used with a compiled pattern containing items that were not
1661  .\" HREF  supported for partial matching. From release 8.00 onwards, there are no
1662  \fBpcrepartial\fP  restrictions on partial matching.
 .\"  
 documentation for details of partial matching.  
1663  .sp  .sp
1664    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
1665  .sp  .sp
# Line 1726  These functions call \fBpcre_get_stringn Line 1829  These functions call \fBpcre_get_stringn
1829  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
1830  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,
1831  the behaviour may not be what you want (see the next section).  the behaviour may not be what you want (see the next section).
1832  .  .P
1833    \fBWarning:\fP If the pattern uses the (?| feature to set up multiple
1834    subpatterns with the same number, as described in the
1835    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1836    .\" </a>
1837    section on duplicate subpattern numbers
1838    .\"
1839    in the
1840    .\" HREF
1841    \fBpcrepattern\fP
1842    .\"
1843    page, you cannot use names to distinguish the different subpatterns, because
1844    names are not included in the compiled code. The matching process uses only
1845    numbers. For this reason, the use of different names for subpatterns of the
1846    same number causes an error at compile time.
1847  .  .
1848  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
1849  .rs  .rs
# Line 1736  the behaviour may not be what you want ( Line 1853  the behaviour may not be what you want (
1853  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
1854  .PP  .PP
1855  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
1856  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
1857  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
1858  example is shown in the  such subpatterns are named, they are required to use the same names.)
1859    .P
1860    Normally, patterns with duplicate names are such that in any one match, only
1861    one of the named subpatterns participates. An example is shown in the
1862  .\" HREF  .\" HREF
1863  \fBpcrepattern\fP  \fBpcrepattern\fP
1864  .\"  .\"
# Line 1802  a compiled pattern, using a matching alg Line 1922  a compiled pattern, using a matching alg
1922  just once, and does not backtrack. This has different characteristics to the  just once, and does not backtrack. This has different characteristics to the
1923  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
1924  patterns are not supported. Nevertheless, there are times when this kind of  patterns are not supported. Nevertheless, there are times when this kind of
1925  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
1926  the  list of features that \fBpcre_dfa_exec()\fP does not support, see the
1927  .\" HREF  .\" HREF
1928  \fBpcrematching\fP  \fBpcrematching\fP
1929  .\"  .\"
# Line 1842  Here is an example of a simple call to \ Line 1962  Here is an example of a simple call to \
1962  .sp  .sp
1963  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
1964  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,
1965  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1966  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,
1967  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
1968  .sp  for \fBpcre_exec()\fP, so their description is not repeated here.
1969    PCRE_PARTIAL  .sp
1970  .sp    PCRE_PARTIAL_HARD
1971  This has the same general effect as it does for \fBpcre_exec()\fP, but the    PCRE_PARTIAL_SOFT
1972  details are slightly different. When PCRE_PARTIAL is set for  .sp
1973  \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
1974  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
1975  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
1976  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
1977  matching string.  additional characters. This happens even if some complete matches have also
1978    been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
1979    is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
1980    there have been no complete matches, but there is still at least one matching
1981    possibility. The portion of the string that was inspected when the longest
1982    partial match was found is set as the first matching string in both cases.
1983  .sp  .sp
1984    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
1985  .sp  .sp
# Line 1865  matching point in the subject string. Line 1990  matching point in the subject string.
1990  .sp  .sp
1991    PCRE_DFA_RESTART    PCRE_DFA_RESTART
1992  .sp  .sp
1993  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
1994  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
1995  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
1996  option requests this action; when it is set, the \fIworkspace\fP and  \fIworkspace\fP and \fIwscount\fP options must reference the same vector as
1997  \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
1998  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  
1999  .\" HREF  .\" HREF
2000  \fBpcrepartial\fP  \fBpcrepartial\fP
2001  .\"  .\"
# Line 1975  Cambridge CB2 3QH, England. Line 2099  Cambridge CB2 3QH, England.
2099  .rs  .rs
2100  .sp  .sp
2101  .nf  .nf
2102  Last updated: 12 April 2008  Last updated: 26 March 2010
2103  Copyright (c) 1997-2008 University of Cambridge.  Copyright (c) 1997-2010 University of Cambridge.
2104  .fi  .fi

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