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revision 392 by ph10, Tue Mar 17 21:30:30 2009 UTC revision 531 by ph10, Tue Jun 1 13:53:26 2010 UTC
# Line 132  an application that uses PCRE. The heade Line 132  an application that uses PCRE. The heade
132  and PCRE_MINOR to contain the major and minor release numbers for the library.  and PCRE_MINOR to contain the major and minor release numbers for the library.
133  Applications can use these to include support for different releases of PCRE.  Applications can use these to include support for different releases of PCRE.
134  .P  .P
135    In a Windows environment, if you want to statically link an application program
136    against a non-dll \fBpcre.a\fP file, you must define PCRE_STATIC before
137    including \fBpcre.h\fP or \fBpcrecpp.h\fP, because otherwise the
138    \fBpcre_malloc()\fP and \fBpcre_free()\fP exported functions will be declared
139    \fB__declspec(dllimport)\fP, with unwanted results.
140    .P
141  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,
142  and \fBpcre_exec()\fP are used for compiling and matching regular expressions  and \fBpcre_exec()\fP are used for compiling and matching regular expressions
143  in a Perl-compatible manner. A sample program that demonstrates the simplest  in a Perl-compatible manner. A sample program that demonstrates the simplest
144  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
145  distribution. The  source distribution. A listing of this program is given in the
146    .\" HREF
147    \fBpcredemo\fP
148    .\"
149    documentation, and the
150  .\" HREF  .\" HREF
151  \fBpcresample\fP  \fBpcresample\fP
152  .\"  .\"
# Line 145  documentation describes how to compile a Line 155  documentation describes how to compile a
155  A second matching function, \fBpcre_dfa_exec()\fP, which is not  A second matching function, \fBpcre_dfa_exec()\fP, which is not
156  Perl-compatible, is also provided. This uses a different algorithm for the  Perl-compatible, is also provided. This uses a different algorithm for the
157  matching. The alternative algorithm finds all possible matches (at a given  matching. The alternative algorithm finds all possible matches (at a given
158  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
159  does not return captured substrings. A description of the two matching  lookbehind assertions). However, this algorithm does not return captured
160  algorithms and their advantages and disadvantages is given in the  substrings. A description of the two matching algorithms and their advantages
161    and disadvantages is given in the
162  .\" HREF  .\" HREF
163  \fBpcrematching\fP  \fBpcrematching\fP
164  .\"  .\"
# Line 390  avoiding the use of the stack. Line 401  avoiding the use of the stack.
401  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
402  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
403  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,
404  \fIerrorcodeptr\fP, via which a numerical error code can be returned.  \fIerrorcodeptr\fP, via which a numerical error code can be returned. To avoid
405    too much repetition, we refer just to \fBpcre_compile()\fP below, but the
406    information applies equally to \fBpcre_compile2()\fP.
407  .P  .P
408  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
409  \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 406  argument, which is an address (see below Line 419  argument, which is an address (see below
419  .P  .P
420  The \fIoptions\fP argument contains various bit settings that affect the  The \fIoptions\fP argument contains various bit settings that affect the
421  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
422  options are described below. Some of them, in particular, those that are  options are described below. Some of them (in particular, those that are
423  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
424  the detailed description in the  within the pattern (see the detailed description in the
425  .\" HREF  .\" HREF
426  \fBpcrepattern\fP  \fBpcrepattern\fP
427  .\"  .\"
428  documentation). For these options, the contents of the \fIoptions\fP argument  documentation). For those options that can be different in different parts of
429  specifies their initial settings at the start of compilation and execution. The  the pattern, the contents of the \fIoptions\fP argument specifies their
430  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,
431  matching as well as at compile time.  PCRE_BSR_\fIxxx\fP, and PCRE_NEWLINE_\fIxxx\fP options can be set at the time
432    of matching as well as at compile time.
433  .P  .P
434  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
435  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
436  NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual  NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual
437  error message. This is a static string that is part of the library. You must  error message. This is a static string that is part of the library. You must
438  not try to free it. The 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
439  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
440  \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,
441    an immediate error is given. Some errors are not detected until checks are
442    carried out when the whole pattern has been scanned; in this case the offset is
443    set to the end of the pattern.
444  .P  .P
445  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
446  \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 542  set, any backslash in a pattern that is Line 559  set, any backslash in a pattern that is
559  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
560  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
561  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
562  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
563  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)
564    option setting within a pattern.
565  .sp  .sp
566    PCRE_FIRSTLINE    PCRE_FIRSTLINE
567  .sp  .sp
# Line 624  were followed by ?: but named parenthese Line 642  were followed by ?: but named parenthese
642  they acquire numbers in the usual way). There is no equivalent of this option  they acquire numbers in the usual way). There is no equivalent of this option
643  in Perl.  in Perl.
644  .sp  .sp
645      PCRE_UCP
646    .sp
647    This option changes the way PCRE processes \eb, \ed, \es, \ew, and some of the
648    POSIX character classes. By default, only ASCII characters are recognized, but
649    if PCRE_UCP is set, Unicode properties are used instead to classify characters.
650    More details are given in the section on
651    .\" HTML <a href="pcre.html#genericchartypes">
652    .\" </a>
653    generic character types
654    .\"
655    in the
656    .\" HREF
657    \fBpcrepattern\fP
658    .\"
659    page. If you set PCRE_UCP, matching one of the items it affects takes much
660    longer. The option is available only if PCRE has been compiled with Unicode
661    property support.
662    .sp
663    PCRE_UNGREEDY    PCRE_UNGREEDY
664  .sp  .sp
665  This option inverts the "greediness" of the quantifiers so that they are not  This option inverts the "greediness" of the quantifiers so that they are not
# Line 736  out of use. To avoid confusion, they hav Line 772  out of use. To avoid confusion, they hav
772    57  \eg is not followed by a braced, angle-bracketed, or quoted    57  \eg is not followed by a braced, angle-bracketed, or quoted
773          name/number or by a plain number          name/number or by a plain number
774    58  a numbered reference must not be zero    58  a numbered reference must not be zero
775    59  (*VERB) with an argument is not supported    59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
776    60  (*VERB) not recognized    60  (*VERB) not recognized
777    61  number is too big    61  number is too big
778    62  subpattern name expected    62  subpattern name expected
779    63  digit expected after (?+    63  digit expected after (?+
780    64  ] is an invalid data character in JavaScript compatibility mode    64  ] is an invalid data character in JavaScript compatibility mode
781      65  different names for subpatterns of the same number are not allowed
782      66  (*MARK) must have an argument
783      67  this version of PCRE is not compiled with PCRE_UCP support
784  .sp  .sp
785  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
786  be used if the limits were changed when PCRE was built.  be used if the limits were changed when PCRE was built.
# Line 763  help speed up matching, \fBpcre_study()\ Line 802  help speed up matching, \fBpcre_study()\
802  results of the study.  results of the study.
803  .P  .P
804  The returned value from \fBpcre_study()\fP can be passed directly to  The returned value from \fBpcre_study()\fP can be passed directly to
805  \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
806  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
807  described  passed; these are described
808  .\" HTML <a href="#extradata">  .\" HTML <a href="#extradata">
809  .\" </a>  .\" </a>
810  below  below
811  .\"  .\"
812  in the section on matching a pattern.  in the section on matching a pattern.
813  .P  .P
814  If studying the pattern does not produce any additional information  If studying the pattern does not produce any useful information,
815  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program
816  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
817  own \fBpcre_extra\fP block.  \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block.
818  .P  .P
819  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
820  options are defined, and this argument should always be zero.  options are defined, and this argument should always be zero.
# Line 795  This is a typical call to \fBpcre_study\ Line 834  This is a typical call to \fBpcre_study\
834      0,              /* no options exist */      0,              /* no options exist */
835      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
836  .sp  .sp
837  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
838  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
839  bytes is created.  mean that there are any strings of that length that match, but it does
840    guarantee that no shorter strings match. The value is used by
841    \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP to avoid wasting time by trying to
842    match strings that are shorter than the lower bound. You can find out the value
843    in a calling program via the \fBpcre_fullinfo()\fP function.
844    .P
845    Studying a pattern is also useful for non-anchored patterns that do not have a
846    single fixed starting character. A bitmap of possible starting bytes is
847    created. This speeds up finding a position in the subject at which to start
848    matching.
849  .  .
850  .  .
851  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
# Line 807  bytes is created. Line 855  bytes is created.
855  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters,
856  digits, or whatever, by reference to a set of tables, indexed by character  digits, or whatever, by reference to a set of tables, indexed by character
857  value. When running in UTF-8 mode, this applies only to characters with codes  value. When running in UTF-8 mode, this applies only to characters with codes
858  less than 128. Higher-valued codes never match escapes such as \ew or \ed, but  less than 128. By default, higher-valued codes never match escapes such as \ew
859  can be tested with \ep if PCRE is built with Unicode character property  or \ed, but they can be tested with \ep if PCRE is built with Unicode character
860  support. The use of locales with Unicode is discouraged. If you are handling  property support. Alternatively, the PCRE_UCP option can be set at compile
861  characters with codes greater than 128, you should either use UTF-8 and  time; this causes \ew and friends to use Unicode property support instead of
862  Unicode, or use locales, but not try to mix the two.  built-in tables. The use of locales with Unicode is discouraged. If you are
863    handling characters with codes greater than 128, you should either use UTF-8
864    and Unicode, or use locales, but not try to mix the two.
865  .P  .P
866  PCRE contains an internal set of tables that are used when the final argument  PCRE contains an internal set of tables that are used when the final argument
867  of \fBpcre_compile()\fP is NULL. These are sufficient for many applications.  of \fBpcre_compile()\fP is NULL. These are sufficient for many applications.
# Line 962  follows something of variable length. Fo Line 1012  follows something of variable length. Fo
1012  /^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
1013  is -1.  is -1.
1014  .sp  .sp
1015      PCRE_INFO_MINLENGTH
1016    .sp
1017    If the pattern was studied and a minimum length for matching subject strings
1018    was computed, its value is returned. Otherwise the returned value is -1. The
1019    value is a number of characters, not bytes (this may be relevant in UTF-8
1020    mode). The fourth argument should point to an \fBint\fP variable. A
1021    non-negative value is a lower bound to the length of any matching string. There
1022    may not be any strings of that length that do actually match, but every string
1023    that does match is at least that long.
1024    .sp
1025    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
1026    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
1027    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
# Line 982  entry; both of these return an \fBint\fP Line 1042  entry; both of these return an \fBint\fP
1042  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
1043  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
1044  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
1045  rest of the entry is the corresponding name, zero terminated. The names are in  rest of the entry is the corresponding name, zero terminated.
1046  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of  .P
1047  their parentheses numbers. For example, consider the following pattern (assume  The names are in alphabetical order. Duplicate names may appear if (?| is used
1048  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  to create multiple groups with the same number, as described in the
1049    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1050    .\" </a>
1051    section on duplicate subpattern numbers
1052    .\"
1053    in the
1054    .\" HREF
1055    \fBpcrepattern\fP
1056    .\"
1057    page. Duplicate names for subpatterns with different numbers are permitted only
1058    if PCRE_DUPNAMES is set. In all cases of duplicate names, they appear in the
1059    table in the order in which they were found in the pattern. In the absence of
1060    (?| this is the order of increasing number; when (?| is used this is not
1061    necessarily the case because later subpatterns may have lower numbers.
1062    .P
1063    As a simple example of the name/number table, consider the following pattern
1064    (assume PCRE_EXTENDED is set, so white space - including newlines - is
1065    ignored):
1066  .sp  .sp
1067  .\" JOIN  .\" JOIN
1068    (?<date> (?<year>(\ed\ed)?\ed\ed) -    (?<date> (?<year>(\ed\ed)?\ed\ed) -
# Line 1006  different for each compiled pattern. Line 1083  different for each compiled pattern.
1083  .sp  .sp
1084    PCRE_INFO_OKPARTIAL    PCRE_INFO_OKPARTIAL
1085  .sp  .sp
1086  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
1087  fourth argument should point to an \fBint\fP variable. The  \fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
1088    \fBint\fP variable. From release 8.00, this always returns 1, because the
1089    restrictions that previously applied to partial matching have been lifted. The
1090  .\" HREF  .\" HREF
1091  \fBpcrepartial\fP  \fBpcrepartial\fP
1092  .\"  .\"
1093  documentation lists the restrictions that apply to patterns when partial  documentation gives details of partial matching.
 matching is used.  
1094  .sp  .sp
1095    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1096  .sp  .sp
# Line 1049  variable. Line 1127  variable.
1127  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
1128  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
1129  \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
1130  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
1131    study data, zero is returned. The fourth argument should point to a
1132  \fBsize_t\fP variable.  \fBsize_t\fP variable.
1133  .  .
1134  .  .
# Line 1111  is different. (This seems a highly unlik Line 1190  is different. (This seems a highly unlik
1190  .P  .P
1191  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
1192  compiled pattern, which is passed in the \fIcode\fP argument. If the  compiled pattern, which is passed in the \fIcode\fP argument. If the
1193  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
1194  \fIextra\fP argument. This function is the main matching facility of the  \fIextra\fP argument. This function is the main matching facility of the
1195  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
1196  also an alternative matching function, which is described  also an alternative matching function, which is described
# Line 1161  fields (not necessarily in this order): Line 1240  fields (not necessarily in this order):
1240    unsigned long int \fImatch_limit_recursion\fP;    unsigned long int \fImatch_limit_recursion\fP;
1241    void *\fIcallout_data\fP;    void *\fIcallout_data\fP;
1242    const unsigned char *\fItables\fP;    const unsigned char *\fItables\fP;
1243      unsigned char **\fImark\fP;
1244  .sp  .sp
1245  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
1246  are set. The flag bits are:  are set. The flag bits are:
# Line 1170  are set. The flag bits are: Line 1250  are set. The flag bits are:
1250    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1251    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1252    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1253      PCRE_EXTRA_MARK
1254  .sp  .sp
1255  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
1256  \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 1179  the block by setting the other fields an Line 1260  the block by setting the other fields an
1260  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
1261  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,
1262  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
1263  classic example is the use of nested unlimited repeats.  classic example is a pattern that uses nested unlimited repeats.
1264  .P  .P
1265  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly
1266  (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 1212  with a \fBpcre_extra\fP block in which \ Line 1293  with a \fBpcre_extra\fP block in which \
1293  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
1294  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1295  .P  .P
1296  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,
1297  which is described in the  and is described in the
1298  .\" HREF  .\" HREF
1299  \fBpcrecallout\fP  \fBpcrecallout\fP
1300  .\"  .\"
# Line 1232  called. See the Line 1313  called. See the
1313  \fBpcreprecompile\fP  \fBpcreprecompile\fP
1314  .\"  .\"
1315  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1316    .P
1317    If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1318    be set to point to a \fBchar *\fP variable. If the pattern contains any
1319    backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1320    a name to pass back, a pointer to the name string (zero terminated) is placed
1321    in the variable pointed to by the \fImark\fP field. The names are within the
1322    compiled pattern; if you wish to retain such a name you must copy it before
1323    freeing the memory of a compiled pattern. If there is no name to pass back, the
1324    variable pointed to by the \fImark\fP field set to NULL. For details of the
1325    backtracking control verbs, see the section entitled
1326    .\" HTML <a href="pcrepattern#backtrackcontrol">
1327    .\" </a>
1328    "Backtracking control"
1329    .\"
1330    in the
1331    .\" HREF
1332    \fBpcrepattern\fP
1333    .\"
1334    documentation.
1335    .
1336  .  .
1337  .\" HTML <a name="execoptions"></a>  .\" HTML <a name="execoptions"></a>
1338  .SS "Option bits for \fBpcre_exec()\fP"  .SS "Option bits for \fBpcre_exec()\fP"
# Line 1239  documentation for a discussion of saving Line 1340  documentation for a discussion of saving
1340  .sp  .sp
1341  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
1342  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,
1343  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_START_OPTIMIZE,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1344  PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
1345    PCRE_PARTIAL_HARD.
1346  .sp  .sp
1347    PCRE_ANCHORED    PCRE_ANCHORED
1348  .sp  .sp
# Line 1315  match the empty string, the entire match Line 1417  match the empty string, the entire match
1417  .sp  .sp
1418    a?b?    a?b?
1419  .sp  .sp
1420  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
1421  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
1422  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".
1423  .P  .sp
1424  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case    PCRE_NOTEMPTY_ATSTART
1425  of a pattern match of the empty string within its \fBsplit()\fP function, and  .sp
1426  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
1427  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
1428  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the  can occur only if the pattern contains \eK.
1429  starting offset (see below) and trying an ordinary match again. There is some  .P
1430  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
1431    does make a special case of a pattern match of the empty string within its
1432    \fBsplit()\fP function, and when using the /g modifier. It is possible to
1433    emulate Perl's behaviour after matching a null string by first trying the match
1434    again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
1435    if that fails, by advancing the starting offset (see below) and trying an
1436    ordinary match again. There is some code that demonstrates how to do this in
1437    the
1438    .\" HREF
1439    \fBpcredemo\fP
1440    .\"
1441    sample program.
1442  .sp  .sp
1443    PCRE_NO_START_OPTIMIZE    PCRE_NO_START_OPTIMIZE
1444  .sp  .sp
# Line 1366  PCRE_NO_UTF8_CHECK is set, the effect of Line 1479  PCRE_NO_UTF8_CHECK is set, the effect of
1479  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
1480  UTF-8 character, is undefined. Your program may crash.  UTF-8 character, is undefined. Your program may crash.
1481  .sp  .sp
1482    PCRE_PARTIAL    PCRE_PARTIAL_HARD
1483      PCRE_PARTIAL_SOFT
1484  .sp  .sp
1485  This option turns on the partial matching feature. If the subject string fails  These options turn on the partial matching feature. For backwards
1486  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
1487  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
1488  the failure to match occurred only because there were not enough subject  not enough subject characters to complete the match. If this happens when
1489  characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of  PCRE_PARTIAL_HARD is set, \fBpcre_exec()\fP immediately returns
1490  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
1491  may appear in the pattern. These are discussed in the  by testing any other alternatives. Only if they all fail is PCRE_ERROR_PARTIAL
1492    returned (instead of PCRE_ERROR_NOMATCH). The portion of the string that
1493    was inspected when the partial match was found is set as the first matching
1494    string. There is a more detailed discussion in the
1495  .\" HREF  .\" HREF
1496  \fBpcrepartial\fP  \fBpcrepartial\fP
1497  .\"  .\"
# Line 1462  the \fIovector\fP is not big enough to r Line 1579  the \fIovector\fP is not big enough to r
1579  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
1580  advisable to supply an \fIovector\fP.  advisable to supply an \fIovector\fP.
1581  .P  .P
1582  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
1583  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1584  \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
1585  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 1526  If a pattern contains back references, b Line 1643  If a pattern contains back references, b
1643  gets a block of memory at the start of matching to use for this purpose. If the  gets a block of memory at the start of matching to use for this purpose. If the
1644  call via \fBpcre_malloc()\fP fails, this error is given. The memory is  call via \fBpcre_malloc()\fP fails, this error is given. The memory is
1645  automatically freed at the end of matching.  automatically freed at the end of matching.
1646    .P
1647    This error is also given if \fBpcre_stack_malloc()\fP fails in
1648    \fBpcre_exec()\fP. This can happen only when PCRE has been compiled with
1649    \fB--disable-stack-for-recursion\fP.
1650  .sp  .sp
1651    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1652  .sp  .sp
# Line 1567  documentation for details of partial mat Line 1688  documentation for details of partial mat
1688  .sp  .sp
1689    PCRE_ERROR_BADPARTIAL     (-13)    PCRE_ERROR_BADPARTIAL     (-13)
1690  .sp  .sp
1691  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
1692  are not supported for partial matching. See the  option was used with a compiled pattern containing items that were not
1693  .\" HREF  supported for partial matching. From release 8.00 onwards, there are no
1694  \fBpcrepartial\fP  restrictions on partial matching.
 .\"  
 documentation for details of partial matching.  
1695  .sp  .sp
1696    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
1697  .sp  .sp
# Line 1743  then call \fBpcre_copy_substring()\fP or Line 1862  then call \fBpcre_copy_substring()\fP or
1862  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,
1863  the behaviour may not be what you want (see the next section).  the behaviour may not be what you want (see the next section).
1864  .P  .P
1865  \fBWarning:\fP If the pattern uses the "(?|" feature to set up multiple  \fBWarning:\fP If the pattern uses the (?| feature to set up multiple
1866  subpatterns with the same number, you cannot use names to distinguish them,  subpatterns with the same number, as described in the
1867  because names are not included in the compiled code. The matching process uses  .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1868  only numbers.  .\" </a>
1869    section on duplicate subpattern numbers
1870    .\"
1871    in the
1872    .\" HREF
1873    \fBpcrepattern\fP
1874    .\"
1875    page, you cannot use names to distinguish the different subpatterns, because
1876    names are not included in the compiled code. The matching process uses only
1877    numbers. For this reason, the use of different names for subpatterns of the
1878    same number causes an error at compile time.
1879  .  .
1880  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
1881  .rs  .rs
# Line 1756  only numbers. Line 1885  only numbers.
1885  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
1886  .PP  .PP
1887  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
1888  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
1889  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
1890  example is shown in the  such subpatterns are named, they are required to use the same names.)
1891    .P
1892    Normally, patterns with duplicate names are such that in any one match, only
1893    one of the named subpatterns participates. An example is shown in the
1894  .\" HREF  .\" HREF
1895  \fBpcrepattern\fP  \fBpcrepattern\fP
1896  .\"  .\"
# Line 1822  a compiled pattern, using a matching alg Line 1954  a compiled pattern, using a matching alg
1954  just once, and does not backtrack. This has different characteristics to the  just once, and does not backtrack. This has different characteristics to the
1955  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
1956  patterns are not supported. Nevertheless, there are times when this kind of  patterns are not supported. Nevertheless, there are times when this kind of
1957  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
1958  the  list of features that \fBpcre_dfa_exec()\fP does not support, see the
1959  .\" HREF  .\" HREF
1960  \fBpcrematching\fP  \fBpcrematching\fP
1961  .\"  .\"
# Line 1862  Here is an example of a simple call to \ Line 1994  Here is an example of a simple call to \
1994  .sp  .sp
1995  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
1996  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,
1997  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1998  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,
1999  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
2000  .sp  for \fBpcre_exec()\fP, so their description is not repeated here.
2001    PCRE_PARTIAL  .sp
2002  .sp    PCRE_PARTIAL_HARD
2003  This has the same general effect as it does for \fBpcre_exec()\fP, but the    PCRE_PARTIAL_SOFT
2004  details are slightly different. When PCRE_PARTIAL is set for  .sp
2005  \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
2006  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
2007  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
2008  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
2009  matching string.  additional characters. This happens even if some complete matches have also
2010    been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
2011    is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
2012    there have been no complete matches, but there is still at least one matching
2013    possibility. The portion of the string that was inspected when the longest
2014    partial match was found is set as the first matching string in both cases.
2015  .sp  .sp
2016    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
2017  .sp  .sp
# Line 1885  matching point in the subject string. Line 2022  matching point in the subject string.
2022  .sp  .sp
2023    PCRE_DFA_RESTART    PCRE_DFA_RESTART
2024  .sp  .sp
2025  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
2026  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
2027  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
2028  option requests this action; when it is set, the \fIworkspace\fP and  \fIworkspace\fP and \fIwscount\fP options must reference the same vector as
2029  \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
2030  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  
2031  .\" HREF  .\" HREF
2032  \fBpcrepartial\fP  \fBpcrepartial\fP
2033  .\"  .\"
# Line 1995  Cambridge CB2 3QH, England. Line 2131  Cambridge CB2 3QH, England.
2131  .rs  .rs
2132  .sp  .sp
2133  .nf  .nf
2134  Last updated: 17 March 2009  Last updated: 01 June 2010
2135  Copyright (c) 1997-2009 University of Cambridge.  Copyright (c) 1997-2010 University of Cambridge.
2136  .fi  .fi

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