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revision 371 by ph10, Mon Aug 25 18:28:05 2008 UTC revision 518 by ph10, Tue May 18 15:47:01 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 540  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 622  were followed by ?: but named parenthese Line 636  were followed by ?: but named parenthese
636  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
637  in Perl.  in Perl.
638  .sp  .sp
639      PCRE_UCP
640    .sp
641    This option changes the way PCRE processes \eb, \ed, \es, \ew, and some of the
642    POSIX character classes. By default, only ASCII characters are recognized, but
643    if PCRE_UCP is set, Unicode properties are used instead to classify characters.
644    More details are given in the section on
645    .\" HTML <a href="pcre.html#genericchartypes">
646    .\" </a>
647    generic character types
648    .\"
649    in the
650    .\" HREF
651    \fBpcrepattern\fP
652    .\"
653    page. If you set PCRE_UCP, matching one of the items it affects takes much
654    longer. The option is available only if PCRE has been compiled with Unicode
655    property support.
656    .sp
657    PCRE_UNGREEDY    PCRE_UNGREEDY
658  .sp  .sp
659  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 734  out of use. To avoid confusion, they hav Line 766  out of use. To avoid confusion, they hav
766    57  \eg is not followed by a braced, angle-bracketed, or quoted    57  \eg is not followed by a braced, angle-bracketed, or quoted
767          name/number or by a plain number          name/number or by a plain number
768    58  a numbered reference must not be zero    58  a numbered reference must not be zero
769    59  (*VERB) with an argument is not supported    59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
770    60  (*VERB) not recognized    60  (*VERB) not recognized
771    61  number is too big    61  number is too big
772    62  subpattern name expected    62  subpattern name expected
773    63  digit expected after (?+    63  digit expected after (?+
774    64  ] is an invalid data character in JavaScript compatibility mode    64  ] is an invalid data character in JavaScript compatibility mode
775      65  different names for subpatterns of the same number are not allowed
776      66  (*MARK) must have an argument
777      67  this version of PCRE is not compiled with PCRE_UCP support
778  .sp  .sp
779  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
780  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 796  help speed up matching, \fBpcre_study()\
796  results of the study.  results of the study.
797  .P  .P
798  The returned value from \fBpcre_study()\fP can be passed directly to  The returned value from \fBpcre_study()\fP can be passed directly to
799  \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
800  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
801  described  passed; these are described
802  .\" HTML <a href="#extradata">  .\" HTML <a href="#extradata">
803  .\" </a>  .\" </a>
804  below  below
805  .\"  .\"
806  in the section on matching a pattern.  in the section on matching a pattern.
807  .P  .P
808  If studying the pattern does not produce any additional information  If studying the pattern does not produce any useful information,
809  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program
810  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
811  own \fBpcre_extra\fP block.  \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block.
812  .P  .P
813  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
814  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 828  This is a typical call to \fBpcre_study\
828      0,              /* no options exist */      0,              /* no options exist */
829      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
830  .sp  .sp
831  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
832  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
833  bytes is created.  mean that there are any strings of that length that match, but it does
834    guarantee that no shorter strings match. The value is used by
835    \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP to avoid wasting time by trying to
836    match strings that are shorter than the lower bound. You can find out the value
837    in a calling program via the \fBpcre_fullinfo()\fP function.
838    .P
839    Studying a pattern is also useful for non-anchored patterns that do not have a
840    single fixed starting character. A bitmap of possible starting bytes is
841    created. This speeds up finding a position in the subject at which to start
842    matching.
843  .  .
844  .  .
845  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
# Line 805  bytes is created. Line 849  bytes is created.
849  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters,
850  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
851  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
852  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
853  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
854  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
855  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
856  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
857    handling characters with codes greater than 128, you should either use UTF-8
858    and Unicode, or use locales, but not try to mix the two.
859  .P  .P
860  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
861  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 960  follows something of variable length. Fo Line 1006  follows something of variable length. Fo
1006  /^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
1007  is -1.  is -1.
1008  .sp  .sp
1009      PCRE_INFO_MINLENGTH
1010    .sp
1011    If the pattern was studied and a minimum length for matching subject strings
1012    was computed, its value is returned. Otherwise the returned value is -1. The
1013    value is a number of characters, not bytes (this may be relevant in UTF-8
1014    mode). The fourth argument should point to an \fBint\fP variable. A
1015    non-negative value is a lower bound to the length of any matching string. There
1016    may not be any strings of that length that do actually match, but every string
1017    that does match is at least that long.
1018    .sp
1019    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
1020    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
1021    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
# Line 980  entry; both of these return an \fBint\fP Line 1036  entry; both of these return an \fBint\fP
1036  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
1037  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
1038  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
1039  rest of the entry is the corresponding name, zero terminated. The names are in  rest of the entry is the corresponding name, zero terminated.
1040  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of  .P
1041  their parentheses numbers. For example, consider the following pattern (assume  The names are in alphabetical order. Duplicate names may appear if (?| is used
1042  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  to create multiple groups with the same number, as described in the
1043    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1044    .\" </a>
1045    section on duplicate subpattern numbers
1046    .\"
1047    in the
1048    .\" HREF
1049    \fBpcrepattern\fP
1050    .\"
1051    page. Duplicate names for subpatterns with different numbers are permitted only
1052    if PCRE_DUPNAMES is set. In all cases of duplicate names, they appear in the
1053    table in the order in which they were found in the pattern. In the absence of
1054    (?| this is the order of increasing number; when (?| is used this is not
1055    necessarily the case because later subpatterns may have lower numbers.
1056    .P
1057    As a simple example of the name/number table, consider the following pattern
1058    (assume PCRE_EXTENDED is set, so white space - including newlines - is
1059    ignored):
1060  .sp  .sp
1061  .\" JOIN  .\" JOIN
1062    (?<date> (?<year>(\ed\ed)?\ed\ed) -    (?<date> (?<year>(\ed\ed)?\ed\ed) -
# Line 1004  different for each compiled pattern. Line 1077  different for each compiled pattern.
1077  .sp  .sp
1078    PCRE_INFO_OKPARTIAL    PCRE_INFO_OKPARTIAL
1079  .sp  .sp
1080  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
1081  fourth argument should point to an \fBint\fP variable. The  \fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
1082    \fBint\fP variable. From release 8.00, this always returns 1, because the
1083    restrictions that previously applied to partial matching have been lifted. The
1084  .\" HREF  .\" HREF
1085  \fBpcrepartial\fP  \fBpcrepartial\fP
1086  .\"  .\"
1087  documentation lists the restrictions that apply to patterns when partial  documentation gives details of partial matching.
 matching is used.  
1088  .sp  .sp
1089    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1090  .sp  .sp
# Line 1047  variable. Line 1121  variable.
1121  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
1122  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
1123  \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
1124  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
1125    study data, zero is returned. The fourth argument should point to a
1126  \fBsize_t\fP variable.  \fBsize_t\fP variable.
1127  .  .
1128  .  .
# Line 1109  is different. (This seems a highly unlik Line 1184  is different. (This seems a highly unlik
1184  .P  .P
1185  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
1186  compiled pattern, which is passed in the \fIcode\fP argument. If the  compiled pattern, which is passed in the \fIcode\fP argument. If the
1187  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
1188  \fIextra\fP argument. This function is the main matching facility of the  \fIextra\fP argument. This function is the main matching facility of the
1189  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
1190  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 1234  fields (not necessarily in this order):
1234    unsigned long int \fImatch_limit_recursion\fP;    unsigned long int \fImatch_limit_recursion\fP;
1235    void *\fIcallout_data\fP;    void *\fIcallout_data\fP;
1236    const unsigned char *\fItables\fP;    const unsigned char *\fItables\fP;
1237      unsigned char **\fImark\fP;
1238  .sp  .sp
1239  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
1240  are set. The flag bits are:  are set. The flag bits are:
# Line 1168  are set. The flag bits are: Line 1244  are set. The flag bits are:
1244    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1245    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1246    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1247      PCRE_EXTRA_MARK
1248  .sp  .sp
1249  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
1250  \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 1254  the block by setting the other fields an
1254  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
1255  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,
1256  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
1257  classic example is the use of nested unlimited repeats.  classic example is a pattern that uses nested unlimited repeats.
1258  .P  .P
1259  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly
1260  (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 1287  with a \fBpcre_extra\fP block in which \
1287  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
1288  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1289  .P  .P
1290  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,
1291  which is described in the  and is described in the
1292  .\" HREF  .\" HREF
1293  \fBpcrecallout\fP  \fBpcrecallout\fP
1294  .\"  .\"
# Line 1230  called. See the Line 1307  called. See the
1307  \fBpcreprecompile\fP  \fBpcreprecompile\fP
1308  .\"  .\"
1309  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1310    .P
1311    If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1312    be set to point to a \fBchar *\fP variable. If the pattern contains any
1313    backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1314    a name to pass back, a pointer to the name string (zero terminated) is placed
1315    in the variable pointed to by the \fImark\fP field. The names are within the
1316    compiled pattern; if you wish to retain such a name you must copy it before
1317    freeing the memory of a compiled pattern. If there is no name to pass back, the
1318    variable pointed to by the \fImark\fP field set to NULL. For details of the
1319    backtracking control verbs, see the section entitled
1320    .\" HTML <a href="pcrepattern#backtrackcontrol">
1321    .\" </a>
1322    "Backtracking control"
1323    .\"
1324    in the
1325    .\" HREF
1326    \fBpcrepattern\fP
1327    .\"
1328    documentation.
1329    .
1330  .  .
1331  .\" HTML <a name="execoptions"></a>  .\" HTML <a name="execoptions"></a>
1332  .SS "Option bits for \fBpcre_exec()\fP"  .SS "Option bits for \fBpcre_exec()\fP"
# Line 1237  documentation for a discussion of saving Line 1334  documentation for a discussion of saving
1334  .sp  .sp
1335  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
1336  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,
1337  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1338    PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
1339    PCRE_PARTIAL_HARD.
1340  .sp  .sp
1341    PCRE_ANCHORED    PCRE_ANCHORED
1342  .sp  .sp
# Line 1312  match the empty string, the entire match Line 1411  match the empty string, the entire match
1411  .sp  .sp
1412    a?b?    a?b?
1413  .sp  .sp
1414  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
1415  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
1416  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".
1417  .P  .sp
1418  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case    PCRE_NOTEMPTY_ATSTART
1419  of a pattern match of the empty string within its \fBsplit()\fP function, and  .sp
1420  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
1421  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
1422  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the  can occur only if the pattern contains \eK.
1423  starting offset (see below) and trying an ordinary match again. There is some  .P
1424  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
1425    does make a special case of a pattern match of the empty string within its
1426    \fBsplit()\fP function, and when using the /g modifier. It is possible to
1427    emulate Perl's behaviour after matching a null string by first trying the match
1428    again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
1429    if that fails, by advancing the starting offset (see below) and trying an
1430    ordinary match again. There is some code that demonstrates how to do this in
1431    the
1432    .\" HREF
1433    \fBpcredemo\fP
1434    .\"
1435    sample program.
1436    .sp
1437      PCRE_NO_START_OPTIMIZE
1438    .sp
1439    There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1440    a match, in order to speed up the process. For example, if it is known that a
1441    match must start with a specific character, it searches the subject for that
1442    character, and fails immediately if it cannot find it, without actually running
1443    the main matching function. When callouts are in use, these optimizations can
1444    cause them to be skipped. This option disables the "start-up" optimizations,
1445    causing performance to suffer, but ensuring that the callouts do occur.
1446  .sp  .sp
1447    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1448  .sp  .sp
# Line 1353  PCRE_NO_UTF8_CHECK is set, the effect of Line 1473  PCRE_NO_UTF8_CHECK is set, the effect of
1473  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
1474  UTF-8 character, is undefined. Your program may crash.  UTF-8 character, is undefined. Your program may crash.
1475  .sp  .sp
1476    PCRE_PARTIAL    PCRE_PARTIAL_HARD
1477      PCRE_PARTIAL_SOFT
1478  .sp  .sp
1479  This option turns on the partial matching feature. If the subject string fails  These options turn on the partial matching feature. For backwards
1480  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
1481  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
1482  the failure to match occurred only because there were not enough subject  not enough subject characters to complete the match. If this happens when
1483  characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of  PCRE_PARTIAL_HARD is set, \fBpcre_exec()\fP immediately returns
1484  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
1485  may appear in the pattern. These are discussed in the  by testing any other alternatives. Only if they all fail is PCRE_ERROR_PARTIAL
1486    returned (instead of PCRE_ERROR_NOMATCH). The portion of the string that
1487    was inspected when the partial match was found is set as the first matching
1488    string. There is a more detailed discussion in the
1489  .\" HREF  .\" HREF
1490  \fBpcrepartial\fP  \fBpcrepartial\fP
1491  .\"  .\"
# Line 1449  the \fIovector\fP is not big enough to r Line 1573  the \fIovector\fP is not big enough to r
1573  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
1574  advisable to supply an \fIovector\fP.  advisable to supply an \fIovector\fP.
1575  .P  .P
1576  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
1577  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1578  \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
1579  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 1554  documentation for details of partial mat Line 1678  documentation for details of partial mat
1678  .sp  .sp
1679    PCRE_ERROR_BADPARTIAL     (-13)    PCRE_ERROR_BADPARTIAL     (-13)
1680  .sp  .sp
1681  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
1682  are not supported for partial matching. See the  option was used with a compiled pattern containing items that were not
1683  .\" HREF  supported for partial matching. From release 8.00 onwards, there are no
1684  \fBpcrepartial\fP  restrictions on partial matching.
 .\"  
 documentation for details of partial matching.  
1685  .sp  .sp
1686    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
1687  .sp  .sp
# Line 1729  These functions call \fBpcre_get_stringn Line 1851  These functions call \fBpcre_get_stringn
1851  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
1852  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,
1853  the behaviour may not be what you want (see the next section).  the behaviour may not be what you want (see the next section).
1854  .  .P
1855    \fBWarning:\fP If the pattern uses the (?| feature to set up multiple
1856    subpatterns with the same number, as described in the
1857    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1858    .\" </a>
1859    section on duplicate subpattern numbers
1860    .\"
1861    in the
1862    .\" HREF
1863    \fBpcrepattern\fP
1864    .\"
1865    page, you cannot use names to distinguish the different subpatterns, because
1866    names are not included in the compiled code. The matching process uses only
1867    numbers. For this reason, the use of different names for subpatterns of the
1868    same number causes an error at compile time.
1869  .  .
1870  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
1871  .rs  .rs
# Line 1739  the behaviour may not be what you want ( Line 1875  the behaviour may not be what you want (
1875  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
1876  .PP  .PP
1877  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
1878  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
1879  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
1880  example is shown in the  such subpatterns are named, they are required to use the same names.)
1881    .P
1882    Normally, patterns with duplicate names are such that in any one match, only
1883    one of the named subpatterns participates. An example is shown in the
1884  .\" HREF  .\" HREF
1885  \fBpcrepattern\fP  \fBpcrepattern\fP
1886  .\"  .\"
# Line 1805  a compiled pattern, using a matching alg Line 1944  a compiled pattern, using a matching alg
1944  just once, and does not backtrack. This has different characteristics to the  just once, and does not backtrack. This has different characteristics to the
1945  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
1946  patterns are not supported. Nevertheless, there are times when this kind of  patterns are not supported. Nevertheless, there are times when this kind of
1947  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
1948  the  list of features that \fBpcre_dfa_exec()\fP does not support, see the
1949  .\" HREF  .\" HREF
1950  \fBpcrematching\fP  \fBpcrematching\fP
1951  .\"  .\"
# Line 1845  Here is an example of a simple call to \ Line 1984  Here is an example of a simple call to \
1984  .sp  .sp
1985  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
1986  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,
1987  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1988  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,
1989  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
1990  .sp  for \fBpcre_exec()\fP, so their description is not repeated here.
1991    PCRE_PARTIAL  .sp
1992  .sp    PCRE_PARTIAL_HARD
1993  This has the same general effect as it does for \fBpcre_exec()\fP, but the    PCRE_PARTIAL_SOFT
1994  details are slightly different. When PCRE_PARTIAL is set for  .sp
1995  \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
1996  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
1997  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
1998  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
1999  matching string.  additional characters. This happens even if some complete matches have also
2000    been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
2001    is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
2002    there have been no complete matches, but there is still at least one matching
2003    possibility. The portion of the string that was inspected when the longest
2004    partial match was found is set as the first matching string in both cases.
2005  .sp  .sp
2006    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
2007  .sp  .sp
# Line 1868  matching point in the subject string. Line 2012  matching point in the subject string.
2012  .sp  .sp
2013    PCRE_DFA_RESTART    PCRE_DFA_RESTART
2014  .sp  .sp
2015  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
2016  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
2017  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
2018  option requests this action; when it is set, the \fIworkspace\fP and  \fIworkspace\fP and \fIwscount\fP options must reference the same vector as
2019  \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
2020  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  
2021  .\" HREF  .\" HREF
2022  \fBpcrepartial\fP  \fBpcrepartial\fP
2023  .\"  .\"
# Line 1978  Cambridge CB2 3QH, England. Line 2121  Cambridge CB2 3QH, England.
2121  .rs  .rs
2122  .sp  .sp
2123  .nf  .nf
2124  Last updated: 24 August 2008  Last updated: 16 May 2010
2125  Copyright (c) 1997-2008 University of Cambridge.  Copyright (c) 1997-2010 University of Cambridge.
2126  .fi  .fi

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