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revision 371 by ph10, Mon Aug 25 18:28:05 2008 UTC revision 659 by ph10, Tue Aug 16 09:48:29 2011 UTC
# Line 161  and PCRE_MINOR to contain the major and Line 161  and PCRE_MINOR to contain the major and
161  Applications can use these to include support for different releases of PCRE.  Applications can use these to include support for different releases of PCRE.
162  </P>  </P>
163  <P>  <P>
164    In a Windows environment, if you want to statically link an application program
165    against a non-dll <b>pcre.a</b> file, you must define PCRE_STATIC before
166    including <b>pcre.h</b> or <b>pcrecpp.h</b>, because otherwise the
167    <b>pcre_malloc()</b> and <b>pcre_free()</b> exported functions will be declared
168    <b>__declspec(dllimport)</b>, with unwanted results.
169    </P>
170    <P>
171  The functions <b>pcre_compile()</b>, <b>pcre_compile2()</b>, <b>pcre_study()</b>,  The functions <b>pcre_compile()</b>, <b>pcre_compile2()</b>, <b>pcre_study()</b>,
172  and <b>pcre_exec()</b> are used for compiling and matching regular expressions  and <b>pcre_exec()</b> are used for compiling and matching regular expressions
173  in a Perl-compatible manner. A sample program that demonstrates the simplest  in a Perl-compatible manner. A sample program that demonstrates the simplest
174  way of using them is provided in the file called <i>pcredemo.c</i> in the source  way of using them is provided in the file called <i>pcredemo.c</i> in the PCRE
175  distribution. The  source distribution. A listing of this program is given in the
176    <a href="pcredemo.html"><b>pcredemo</b></a>
177    documentation, and the
178  <a href="pcresample.html"><b>pcresample</b></a>  <a href="pcresample.html"><b>pcresample</b></a>
179  documentation describes how to compile and run it.  documentation describes how to compile and run it.
180  </P>  </P>
# Line 173  documentation describes how to compile a Line 182  documentation describes how to compile a
182  A second matching function, <b>pcre_dfa_exec()</b>, which is not  A second matching function, <b>pcre_dfa_exec()</b>, which is not
183  Perl-compatible, is also provided. This uses a different algorithm for the  Perl-compatible, is also provided. This uses a different algorithm for the
184  matching. The alternative algorithm finds all possible matches (at a given  matching. The alternative algorithm finds all possible matches (at a given
185  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
186  does not return captured substrings. A description of the two matching  lookbehind assertions). However, this algorithm does not return captured
187  algorithms and their advantages and disadvantages is given in the  substrings. A description of the two matching algorithms and their advantages
188    and disadvantages is given in the
189  <a href="pcrematching.html"><b>pcrematching</b></a>  <a href="pcrematching.html"><b>pcrematching</b></a>
190  documentation.  documentation.
191  </P>  </P>
# Line 333  properties is available; otherwise it is Line 343  properties is available; otherwise it is
343  </pre>  </pre>
344  The output is an integer whose value specifies the default character sequence  The output is an integer whose value specifies the default character sequence
345  that is recognized as meaning "newline". The four values that are supported  that is recognized as meaning "newline". The four values that are supported
346  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.
347  default should normally be the standard sequence for your operating system.  Though they are derived from ASCII, the same values are returned in EBCDIC
348    environments. The default should normally correspond to the standard sequence
349    for your operating system.
350  <pre>  <pre>
351    PCRE_CONFIG_BSR    PCRE_CONFIG_BSR
352  </pre>  </pre>
# Line 361  documentation. Line 373  documentation.
373  <pre>  <pre>
374    PCRE_CONFIG_MATCH_LIMIT    PCRE_CONFIG_MATCH_LIMIT
375  </pre>  </pre>
376  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
377  internal matching function calls in a <b>pcre_exec()</b> execution. Further  internal matching function calls in a <b>pcre_exec()</b> execution. Further
378  details are given with <b>pcre_exec()</b> below.  details are given with <b>pcre_exec()</b> below.
379  <pre>  <pre>
380    PCRE_CONFIG_MATCH_LIMIT_RECURSION    PCRE_CONFIG_MATCH_LIMIT_RECURSION
381  </pre>  </pre>
382  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
383  recursion when calling the internal matching function in a <b>pcre_exec()</b>  recursion when calling the internal matching function in a <b>pcre_exec()</b>
384  execution. Further details are given with <b>pcre_exec()</b> below.  execution. Further details are given with <b>pcre_exec()</b> below.
385  <pre>  <pre>
# Line 395  avoiding the use of the stack. Line 407  avoiding the use of the stack.
407  Either of the functions <b>pcre_compile()</b> or <b>pcre_compile2()</b> can be  Either of the functions <b>pcre_compile()</b> or <b>pcre_compile2()</b> can be
408  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
409  the two interfaces is that <b>pcre_compile2()</b> has an additional argument,  the two interfaces is that <b>pcre_compile2()</b> has an additional argument,
410  <i>errorcodeptr</i>, via which a numerical error code can be returned.  <i>errorcodeptr</i>, via which a numerical error code can be returned. To avoid
411    too much repetition, we refer just to <b>pcre_compile()</b> below, but the
412    information applies equally to <b>pcre_compile2()</b>.
413  </P>  </P>
414  <P>  <P>
415  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
# Line 414  argument, which is an address (see below Line 428  argument, which is an address (see below
428  <P>  <P>
429  The <i>options</i> argument contains various bit settings that affect the  The <i>options</i> argument contains various bit settings that affect the
430  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
431  options are described below. Some of them, in particular, those that are  options are described below. Some of them (in particular, those that are
432  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
433  the detailed description in the  within the pattern (see the detailed description in the
434  <a href="pcrepattern.html"><b>pcrepattern</b></a>  <a href="pcrepattern.html"><b>pcrepattern</b></a>
435  documentation). For these options, the contents of the <i>options</i> argument  documentation). For those options that can be different in different parts of
436  specifies their initial settings at the start of compilation and execution. The  the pattern, the contents of the <i>options</i> argument specifies their
437  PCRE_ANCHORED and PCRE_NEWLINE_<i>xxx</i> options can be set at the time of  settings at the start of compilation and execution. The PCRE_ANCHORED,
438  matching as well as at compile time.  PCRE_BSR_<i>xxx</i>, PCRE_NEWLINE_<i>xxx</i>, PCRE_NO_UTF8_CHECK, and
439    PCRE_NO_START_OPT options can be set at the time of matching as well as at
440    compile time.
441  </P>  </P>
442  <P>  <P>
443  If <i>errptr</i> is NULL, <b>pcre_compile()</b> returns NULL immediately.  If <i>errptr</i> is NULL, <b>pcre_compile()</b> returns NULL immediately.
444  Otherwise, if compilation of a pattern fails, <b>pcre_compile()</b> returns  Otherwise, if compilation of a pattern fails, <b>pcre_compile()</b> returns
445  NULL, and sets the variable pointed to by <i>errptr</i> to point to a textual  NULL, and sets the variable pointed to by <i>errptr</i> to point to a textual
446  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
447  not try to free it. The offset from the start of the pattern to the character  not try to free it. Normally, the offset from the start of the pattern to the
448  where the error was discovered is placed in the variable pointed to by  byte that was being processed when the error was discovered is placed in the
449  <i>erroffset</i>, which must not be NULL. If it is, an immediate error is given.  variable pointed to by <i>erroffset</i>, which must not be NULL (if it is, an
450    immediate error is given). However, for an invalid UTF-8 string, the offset is
451    that of the first byte of the failing character. Also, some errors are not
452    detected until checks are carried out when the whole pattern has been scanned;
453    in these cases the offset passed back is the length of the pattern.
454    </P>
455    <P>
456    Note that the offset is in bytes, not characters, even in UTF-8 mode. It may
457    sometimes point into the middle of a UTF-8 character.
458  </P>  </P>
459  <P>  <P>
460  If <b>pcre_compile2()</b> is used instead of <b>pcre_compile()</b>, and the  If <b>pcre_compile2()</b> is used instead of <b>pcre_compile()</b>, and the
# Line 510  pattern. Line 534  pattern.
534  <pre>  <pre>
535    PCRE_DOTALL    PCRE_DOTALL
536  </pre>  </pre>
537  If this bit is set, a dot metacharater in the pattern matches all characters,  If this bit is set, a dot metacharacter in the pattern matches a character of
538  including those that indicate newline. Without it, a dot does not match when  any value, including one that indicates a newline. However, it only ever
539  the current position is at a newline. This option is equivalent to Perl's /s  matches one character, even if newlines are coded as CRLF. Without this option,
540  option, and it can be changed within a pattern by a (?s) option setting. A  a dot does not match when the current position is at a newline. This option is
541  negative class such as [^a] always matches newline characters, independent of  equivalent to Perl's /s option, and it can be changed within a pattern by a
542  the setting of this option.  (?s) option setting. A negative class such as [^a] always matches newline
543    characters, independent of the setting of this option.
544  <pre>  <pre>
545    PCRE_DUPNAMES    PCRE_DUPNAMES
546  </pre>  </pre>
# Line 536  ignored. This is equivalent to Perl's /x Line 561  ignored. This is equivalent to Perl's /x
561  pattern by a (?x) option setting.  pattern by a (?x) option setting.
562  </P>  </P>
563  <P>  <P>
564    Which characters are interpreted as newlines is controlled by the options
565    passed to <b>pcre_compile()</b> or by a special sequence at the start of the
566    pattern, as described in the section entitled
567    <a href="pcrepattern.html#newlines">"Newline conventions"</a>
568    in the <b>pcrepattern</b> documentation. Note that the end of this type of
569    comment is a literal newline sequence in the pattern; escape sequences that
570    happen to represent a newline do not count.
571    </P>
572    <P>
573  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
574  Note, however, that this applies only to data characters. Whitespace characters  Note, however, that this applies only to data characters. Whitespace characters
575  may never appear within special character sequences in a pattern, for example  may never appear within special character sequences in a pattern, for example
576  within the sequence (?( which introduces a conditional subpattern.  within the sequence (?( that introduces a conditional subpattern.
577  <pre>  <pre>
578    PCRE_EXTRA    PCRE_EXTRA
579  </pre>  </pre>
# Line 549  set, any backslash in a pattern that is Line 583  set, any backslash in a pattern that is
583  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
584  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
585  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
586  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
587  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)
588    option setting within a pattern.
589  <pre>  <pre>
590    PCRE_FIRSTLINE    PCRE_FIRSTLINE
591  </pre>  </pre>
# Line 618  PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is Line 653  PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is
653  other combinations may yield unused numbers and cause an error.  other combinations may yield unused numbers and cause an error.
654  </P>  </P>
655  <P>  <P>
656  The only time that a line break is specially recognized when compiling a  The only time that a line break in a pattern is specially recognized when
657  pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character  compiling is when PCRE_EXTENDED is set. CR and LF are whitespace characters,
658  class is encountered. This indicates a comment that lasts until after the next  and so are ignored in this mode. Also, an unescaped # outside a character class
659  line break sequence. In other circumstances, line break sequences are treated  indicates a comment that lasts until after the next line break sequence. In
660  as literal data, except that in PCRE_EXTENDED mode, both CR and LF are treated  other circumstances, line break sequences in patterns are treated as literal
661  as whitespace characters and are therefore ignored.  data.
662  </P>  </P>
663  <P>  <P>
664  The newline option that is set at compile time becomes the default that is used  The newline option that is set at compile time becomes the default that is used
# Line 637  were followed by ?: but named parenthese Line 672  were followed by ?: but named parenthese
672  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
673  in Perl.  in Perl.
674  <pre>  <pre>
675      NO_START_OPTIMIZE
676    </pre>
677    This is an option that acts at matching time; that is, it is really an option
678    for <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>. If it is set at compile time,
679    it is remembered with the compiled pattern and assumed at matching time. For
680    details see the discussion of PCRE_NO_START_OPTIMIZE
681    <a href="#execoptions">below.</a>
682    <pre>
683      PCRE_UCP
684    </pre>
685    This option changes the way PCRE processes \B, \b, \D, \d, \S, \s, \W,
686    \w, and some of the POSIX character classes. By default, only ASCII characters
687    are recognized, but if PCRE_UCP is set, Unicode properties are used instead to
688    classify characters. More details are given in the section on
689    <a href="pcre.html#genericchartypes">generic character types</a>
690    in the
691    <a href="pcrepattern.html"><b>pcrepattern</b></a>
692    page. If you set PCRE_UCP, matching one of the items it affects takes much
693    longer. The option is available only if PCRE has been compiled with Unicode
694    property support.
695    <pre>
696    PCRE_UNGREEDY    PCRE_UNGREEDY
697  </pre>  </pre>
698  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 714  out of use. To avoid confusion, they hav Line 770  out of use. To avoid confusion, they hav
770    34  character value in \x{...} sequence is too large    34  character value in \x{...} sequence is too large
771    35  invalid condition (?(0)    35  invalid condition (?(0)
772    36  \C not allowed in lookbehind assertion    36  \C not allowed in lookbehind assertion
773    37  PCRE does not support \L, \l, \N, \U, or \u    37  PCRE does not support \L, \l, \N{name}, \U, or \u
774    38  number after (?C is &#62; 255    38  number after (?C is &#62; 255
775    39  closing ) for (?C expected    39  closing ) for (?C expected
776    40  recursive call could loop indefinitely    40  recursive call could loop indefinitely
# Line 730  out of use. To avoid confusion, they hav Line 786  out of use. To avoid confusion, they hav
786    50  [this code is not in use]    50  [this code is not in use]
787    51  octal value is greater than \377 (not in UTF-8 mode)    51  octal value is greater than \377 (not in UTF-8 mode)
788    52  internal error: overran compiling workspace    52  internal error: overran compiling workspace
789    53  internal error: previously-checked referenced subpattern not found    53  internal error: previously-checked referenced subpattern
790            not found
791    54  DEFINE group contains more than one branch    54  DEFINE group contains more than one branch
792    55  repeating a DEFINE group is not allowed    55  repeating a DEFINE group is not allowed
793    56  inconsistent NEWLINE options    56  inconsistent NEWLINE options
794    57  \g is not followed by a braced, angle-bracketed, or quoted    57  \g is not followed by a braced, angle-bracketed, or quoted
795          name/number or by a plain number          name/number or by a plain number
796    58  a numbered reference must not be zero    58  a numbered reference must not be zero
797    59  (*VERB) with an argument is not supported    59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
798    60  (*VERB) not recognized    60  (*VERB) not recognized
799    61  number is too big    61  number is too big
800    62  subpattern name expected    62  subpattern name expected
801    63  digit expected after (?+    63  digit expected after (?+
802    64  ] is an invalid data character in JavaScript compatibility mode    64  ] is an invalid data character in JavaScript compatibility mode
803      65  different names for subpatterns of the same number are
804            not allowed
805      66  (*MARK) must have an argument
806      67  this version of PCRE is not compiled with PCRE_UCP support
807      68  \c must be followed by an ASCII character
808      69  \k is not followed by a braced, angle-bracketed, or quoted name
809  </pre>  </pre>
810  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
811  be used if the limits were changed when PCRE was built.  be used if the limits were changed when PCRE was built.
812  </P>  <a name="studyingapattern"></a></P>
813  <br><a name="SEC9" href="#TOC1">STUDYING A PATTERN</a><br>  <br><a name="SEC9" href="#TOC1">STUDYING A PATTERN</a><br>
814  <P>  <P>
815  <b>pcre_extra *pcre_study(const pcre *<i>code</i>, int <i>options</i></b>  <b>pcre_extra *pcre_study(const pcre *<i>code</i>, int <i>options</i></b>
# Line 763  results of the study. Line 826  results of the study.
826  </P>  </P>
827  <P>  <P>
828  The returned value from <b>pcre_study()</b> can be passed directly to  The returned value from <b>pcre_study()</b> can be passed directly to
829  <b>pcre_exec()</b>. However, a <b>pcre_extra</b> block also contains other  <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>. However, a <b>pcre_extra</b> block
830  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
831  described  passed; these are described
832  <a href="#extradata">below</a>  <a href="#extradata">below</a>
833  in the section on matching a pattern.  in the section on matching a pattern.
834  </P>  </P>
835  <P>  <P>
836  If studying the pattern does not produce any additional information  If studying the pattern does not produce any useful information,
837  <b>pcre_study()</b> returns NULL. In that circumstance, if the calling program  <b>pcre_study()</b> returns NULL. In that circumstance, if the calling program
838  wants to pass any of the other fields to <b>pcre_exec()</b>, it must set up its  wants to pass any of the other fields to <b>pcre_exec()</b> or
839  own <b>pcre_extra</b> block.  <b>pcre_dfa_exec()</b>, it must set up its own <b>pcre_extra</b> block.
840  </P>  </P>
841  <P>  <P>
842  The second argument of <b>pcre_study()</b> contains option bits. At present, no  The second argument of <b>pcre_study()</b> contains option bits. At present, no
# Line 796  This is a typical call to pcre_study< Line 859  This is a typical call to pcre_study<
859      0,              /* no options exist */      0,              /* no options exist */
860      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
861  </pre>  </pre>
862  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
863  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
864  bytes is created.  mean that there are any strings of that length that match, but it does
865    guarantee that no shorter strings match. The value is used by
866    <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b> to avoid wasting time by trying to
867    match strings that are shorter than the lower bound. You can find out the value
868    in a calling program via the <b>pcre_fullinfo()</b> function.
869    </P>
870    <P>
871    Studying a pattern is also useful for non-anchored patterns that do not have a
872    single fixed starting character. A bitmap of possible starting bytes is
873    created. This speeds up finding a position in the subject at which to start
874    matching.
875    </P>
876    <P>
877    The two optimizations just described can be disabled by setting the
878    PCRE_NO_START_OPTIMIZE option when calling <b>pcre_exec()</b> or
879    <b>pcre_dfa_exec()</b>. You might want to do this if your pattern contains
880    callouts or (*MARK), and you want to make use of these facilities in cases
881    where matching fails. See the discussion of PCRE_NO_START_OPTIMIZE
882    <a href="#execoptions">below.</a>
883  <a name="localesupport"></a></P>  <a name="localesupport"></a></P>
884  <br><a name="SEC10" href="#TOC1">LOCALE SUPPORT</a><br>  <br><a name="SEC10" href="#TOC1">LOCALE SUPPORT</a><br>
885  <P>  <P>
886  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters,
887  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
888  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
889  less than 128. Higher-valued codes never match escapes such as \w or \d, but  less than 128. By default, higher-valued codes never match escapes such as \w
890  can be tested with \p if PCRE is built with Unicode character property  or \d, but they can be tested with \p if PCRE is built with Unicode character
891  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
892  characters with codes greater than 128, you should either use UTF-8 and  time; this causes \w and friends to use Unicode property support instead of
893  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
894    handling characters with codes greater than 128, you should either use UTF-8
895    and Unicode, or use locales, but not try to mix the two.
896  </P>  </P>
897  <P>  <P>
898  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
# Line 858  internal tables) to pcre_exec(). Line 941  internal tables) to pcre_exec().
941  this facility could be used to match a pattern in a different locale from the  this facility could be used to match a pattern in a different locale from the
942  one in which it was compiled. Passing table pointers at run time is discussed  one in which it was compiled. Passing table pointers at run time is discussed
943  below in the section on matching a pattern.  below in the section on matching a pattern.
944  </P>  <a name="infoaboutpattern"></a></P>
945  <br><a name="SEC11" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br>  <br><a name="SEC11" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br>
946  <P>  <P>
947  <b>int pcre_fullinfo(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>  <b>int pcre_fullinfo(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
# Line 969  follows something of variable length. Fo Line 1052  follows something of variable length. Fo
1052  /^a\d+z\d+/ the returned value is "z", but for /^a\dz\d/ the returned value  /^a\d+z\d+/ the returned value is "z", but for /^a\dz\d/ the returned value
1053  is -1.  is -1.
1054  <pre>  <pre>
1055      PCRE_INFO_MINLENGTH
1056    </pre>
1057    If the pattern was studied and a minimum length for matching subject strings
1058    was computed, its value is returned. Otherwise the returned value is -1. The
1059    value is a number of characters, not bytes (this may be relevant in UTF-8
1060    mode). The fourth argument should point to an <b>int</b> variable. A
1061    non-negative value is a lower bound to the length of any matching string. There
1062    may not be any strings of that length that do actually match, but every string
1063    that does match is at least that long.
1064    <pre>
1065    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
1066    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
1067    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
# Line 990  entry; both of these return an int Line 1083  entry; both of these return an int
1083  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
1084  entry of the table (a pointer to <b>char</b>). The first two bytes of each entry  entry of the table (a pointer to <b>char</b>). The first two bytes of each entry
1085  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
1086  rest of the entry is the corresponding name, zero terminated. The names are in  rest of the entry is the corresponding name, zero terminated.
1087  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of  </P>
1088  their parentheses numbers. For example, consider the following pattern (assume  <P>
1089  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  The names are in alphabetical order. Duplicate names may appear if (?| is used
1090    to create multiple groups with the same number, as described in the
1091    <a href="pcrepattern.html#dupsubpatternnumber">section on duplicate subpattern numbers</a>
1092    in the
1093    <a href="pcrepattern.html"><b>pcrepattern</b></a>
1094    page. Duplicate names for subpatterns with different numbers are permitted only
1095    if PCRE_DUPNAMES is set. In all cases of duplicate names, they appear in the
1096    table in the order in which they were found in the pattern. In the absence of
1097    (?| this is the order of increasing number; when (?| is used this is not
1098    necessarily the case because later subpatterns may have lower numbers.
1099    </P>
1100    <P>
1101    As a simple example of the name/number table, consider the following pattern
1102    (assume PCRE_EXTENDED is set, so white space - including newlines - is
1103    ignored):
1104  <pre>  <pre>
1105    (?&#60;date&#62; (?&#60;year&#62;(\d\d)?\d\d) - (?&#60;month&#62;\d\d) - (?&#60;day&#62;\d\d) )    (?&#60;date&#62; (?&#60;year&#62;(\d\d)?\d\d) - (?&#60;month&#62;\d\d) - (?&#60;day&#62;\d\d) )
1106  </pre>  </pre>
# Line 1012  different for each compiled pattern. Line 1119  different for each compiled pattern.
1119  <pre>  <pre>
1120    PCRE_INFO_OKPARTIAL    PCRE_INFO_OKPARTIAL
1121  </pre>  </pre>
1122  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
1123  fourth argument should point to an <b>int</b> variable. The  <b>pcre_exec()</b>, otherwise 0. The fourth argument should point to an
1124    <b>int</b> variable. From release 8.00, this always returns 1, because the
1125    restrictions that previously applied to partial matching have been lifted. The
1126  <a href="pcrepartial.html"><b>pcrepartial</b></a>  <a href="pcrepartial.html"><b>pcrepartial</b></a>
1127  documentation lists the restrictions that apply to patterns when partial  documentation gives details of partial matching.
 matching is used.  
1128  <pre>  <pre>
1129    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1130  </pre>  </pre>
# Line 1049  variable. Line 1157  variable.
1157  <pre>  <pre>
1158    PCRE_INFO_STUDYSIZE    PCRE_INFO_STUDYSIZE
1159  </pre>  </pre>
1160  Return the size of the data block pointed to by the <i>study_data</i> field in  Return the size of the data block pointed to by the <i>study_data</i> field in a
1161  a <b>pcre_extra</b> block. That is, it is the value that was passed to  <b>pcre_extra</b> block. If <b>pcre_extra</b> is NULL, or there is no study data,
1162  <b>pcre_malloc()</b> when PCRE was getting memory into which to place the data  zero is returned. The fourth argument should point to a <b>size_t</b> variable.
1163  created by <b>pcre_study()</b>. The fourth argument should point to a  The <i>study_data</i> field is set by <b>pcre_study()</b> to record information
1164  <b>size_t</b> variable.  that will speed up matching (see the section entitled
1165    <a href="#studyingapattern">"Studying a pattern"</a>
1166    above). The format of the <i>study_data</i> block is private, but its length
1167    is made available via this option so that it can be saved and restored (see the
1168    <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
1169    documentation for details).
1170  </P>  </P>
1171  <br><a name="SEC12" href="#TOC1">OBSOLETE INFO FUNCTION</a><br>  <br><a name="SEC12" href="#TOC1">OBSOLETE INFO FUNCTION</a><br>
1172  <P>  <P>
# Line 1112  is different. (This seems a highly unlik Line 1225  is different. (This seems a highly unlik
1225  <P>  <P>
1226  The function <b>pcre_exec()</b> is called to match a subject string against a  The function <b>pcre_exec()</b> is called to match a subject string against a
1227  compiled pattern, which is passed in the <i>code</i> argument. If the  compiled pattern, which is passed in the <i>code</i> argument. If the
1228  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
1229  <i>extra</i> argument. This function is the main matching facility of the  <i>extra</i> argument. This function is the main matching facility of the
1230  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
1231  also an alternative matching function, which is described  also an alternative matching function, which is described
# Line 1160  fields (not necessarily in this order): Line 1273  fields (not necessarily in this order):
1273    unsigned long int <i>match_limit_recursion</i>;    unsigned long int <i>match_limit_recursion</i>;
1274    void *<i>callout_data</i>;    void *<i>callout_data</i>;
1275    const unsigned char *<i>tables</i>;    const unsigned char *<i>tables</i>;
1276      unsigned char **<i>mark</i>;
1277  </pre>  </pre>
1278  The <i>flags</i> field is a bitmap that specifies which of the other fields  The <i>flags</i> field is a bitmap that specifies which of the other fields
1279  are set. The flag bits are:  are set. The flag bits are:
# Line 1169  are set. The flag bits are: Line 1283  are set. The flag bits are:
1283    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1284    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1285    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1286      PCRE_EXTRA_MARK
1287  </pre>  </pre>
1288  Other flag bits should be set to zero. The <i>study_data</i> field is set in the  Other flag bits should be set to zero. The <i>study_data</i> field is set in the
1289  <b>pcre_extra</b> block that is returned by <b>pcre_study()</b>, together with  <b>pcre_extra</b> block that is returned by <b>pcre_study()</b>, together with
# Line 1179  the block by setting the other fields an Line 1294  the block by setting the other fields an
1294  The <i>match_limit</i> field provides a means of preventing PCRE from using up a  The <i>match_limit</i> field provides a means of preventing PCRE from using up a
1295  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,
1296  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
1297  classic example is the use of nested unlimited repeats.  classic example is a pattern that uses nested unlimited repeats.
1298  </P>  </P>
1299  <P>  <P>
1300  Internally, PCRE uses a function called <b>match()</b> which it calls repeatedly  Internally, PCRE uses a function called <b>match()</b> which it calls repeatedly
# Line 1218  PCRE_EXTRA_MATCH_LIMIT_RECURSION is set Line 1333  PCRE_EXTRA_MATCH_LIMIT_RECURSION is set
1333  is exceeded, <b>pcre_exec()</b> returns PCRE_ERROR_RECURSIONLIMIT.  is exceeded, <b>pcre_exec()</b> returns PCRE_ERROR_RECURSIONLIMIT.
1334  </P>  </P>
1335  <P>  <P>
1336  The <i>pcre_callout</i> field is used in conjunction with the "callout" feature,  The <i>callout_data</i> field is used in conjunction with the "callout" feature,
1337  which is described in the  and is described in the
1338  <a href="pcrecallout.html"><b>pcrecallout</b></a>  <a href="pcrecallout.html"><b>pcrecallout</b></a>
1339  documentation.  documentation.
1340  </P>  </P>
# Line 1235  the external tables might be at a differ Line 1350  the external tables might be at a differ
1350  called. See the  called. See the
1351  <a href="pcreprecompile.html"><b>pcreprecompile</b></a>  <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
1352  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1353    </P>
1354    <P>
1355    If PCRE_EXTRA_MARK is set in the <i>flags</i> field, the <i>mark</i> field must
1356    be set to point to a <b>char *</b> variable. If the pattern contains any
1357    backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1358    a name to pass back, a pointer to the name string (zero terminated) is placed
1359    in the variable pointed to by the <i>mark</i> field. The names are within the
1360    compiled pattern; if you wish to retain such a name you must copy it before
1361    freeing the memory of a compiled pattern. If there is no name to pass back, the
1362    variable pointed to by the <i>mark</i> field set to NULL. For details of the
1363    backtracking control verbs, see the section entitled
1364    <a href="pcrepattern#backtrackcontrol">"Backtracking control"</a>
1365    in the
1366    <a href="pcrepattern.html"><b>pcrepattern</b></a>
1367    documentation.
1368  <a name="execoptions"></a></P>  <a name="execoptions"></a></P>
1369  <br><b>  <br><b>
1370  Option bits for <b>pcre_exec()</b>  Option bits for <b>pcre_exec()</b>
# Line 1242  Option bits for pcre_exec() Line 1372  Option bits for pcre_exec()
1372  <P>  <P>
1373  The unused bits of the <i>options</i> argument for <b>pcre_exec()</b> must be  The unused bits of the <i>options</i> argument for <b>pcre_exec()</b> must be
1374  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_<i>xxx</i>,  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_<i>xxx</i>,
1375  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1376    PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
1377    PCRE_PARTIAL_HARD.
1378  <pre>  <pre>
1379    PCRE_ANCHORED    PCRE_ANCHORED
1380  </pre>  </pre>
# Line 1321  match the empty string, the entire match Line 1453  match the empty string, the entire match
1453  <pre>  <pre>
1454    a?b?    a?b?
1455  </pre>  </pre>
1456  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
1457  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
1458  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".
1459    <pre>
1460      PCRE_NOTEMPTY_ATSTART
1461    </pre>
1462    This is like PCRE_NOTEMPTY, except that an empty string match that is not at
1463    the start of the subject is permitted. If the pattern is anchored, such a match
1464    can occur only if the pattern contains \K.
1465  </P>  </P>
1466  <P>  <P>
1467  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case  Perl has no direct equivalent of PCRE_NOTEMPTY or PCRE_NOTEMPTY_ATSTART, but it
1468  of a pattern match of the empty string within its <b>split()</b> function, and  does make a special case of a pattern match of the empty string within its
1469  when using the /g modifier. It is possible to emulate Perl's behaviour after  <b>split()</b> function, and when using the /g modifier. It is possible to
1470  matching a null string by first trying the match again at the same offset with  emulate Perl's behaviour after matching a null string by first trying the match
1471  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the  again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
1472  starting offset (see below) and trying an ordinary match again. There is some  if that fails, by advancing the starting offset (see below) and trying an
1473  code that demonstrates how to do this in the <i>pcredemo.c</i> sample program.  ordinary match again. There is some code that demonstrates how to do this in
1474    the
1475    <a href="pcredemo.html"><b>pcredemo</b></a>
1476    sample program. In the most general case, you have to check to see if the
1477    newline convention recognizes CRLF as a newline, and if so, and the current
1478    character is CR followed by LF, advance the starting offset by two characters
1479    instead of one.
1480    <pre>
1481      PCRE_NO_START_OPTIMIZE
1482    </pre>
1483    There are a number of optimizations that <b>pcre_exec()</b> uses at the start of
1484    a match, in order to speed up the process. For example, if it is known that an
1485    unanchored match must start with a specific character, it searches the subject
1486    for that character, and fails immediately if it cannot find it, without
1487    actually running the main matching function. This means that a special item
1488    such as (*COMMIT) at the start of a pattern is not considered until after a
1489    suitable starting point for the match has been found. When callouts or (*MARK)
1490    items are in use, these "start-up" optimizations can cause them to be skipped
1491    if the pattern is never actually used. The start-up optimizations are in effect
1492    a pre-scan of the subject that takes place before the pattern is run.
1493    </P>
1494    <P>
1495    The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
1496    causing performance to suffer, but ensuring that in cases where the result is
1497    "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
1498    are considered at every possible starting position in the subject string. If
1499    PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
1500    time.
1501    </P>
1502    <P>
1503    Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
1504    Consider the pattern
1505    <pre>
1506      (*COMMIT)ABC
1507    </pre>
1508    When this is compiled, PCRE records the fact that a match must start with the
1509    character "A". Suppose the subject string is "DEFABC". The start-up
1510    optimization scans along the subject, finds "A" and runs the first match
1511    attempt from there. The (*COMMIT) item means that the pattern must match the
1512    current starting position, which in this case, it does. However, if the same
1513    match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
1514    subject string does not happen. The first match attempt is run starting from
1515    "D" and when this fails, (*COMMIT) prevents any further matches being tried, so
1516    the overall result is "no match". If the pattern is studied, more start-up
1517    optimizations may be used. For example, a minimum length for the subject may be
1518    recorded. Consider the pattern
1519    <pre>
1520      (*MARK:A)(X|Y)
1521    </pre>
1522    The minimum length for a match is one character. If the subject is "ABC", there
1523    will be attempts to match "ABC", "BC", "C", and then finally an empty string.
1524    If the pattern is studied, the final attempt does not take place, because PCRE
1525    knows that the subject is too short, and so the (*MARK) is never encountered.
1526    In this case, studying the pattern does not affect the overall match result,
1527    which is still "no match", but it does affect the auxiliary information that is
1528    returned.
1529  <pre>  <pre>
1530    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1531  </pre>  </pre>
# Line 1345  strings in the Line 1538  strings in the
1538  in the main  in the main
1539  <a href="pcre.html"><b>pcre</b></a>  <a href="pcre.html"><b>pcre</b></a>
1540  page. If an invalid UTF-8 sequence of bytes is found, <b>pcre_exec()</b> returns  page. If an invalid UTF-8 sequence of bytes is found, <b>pcre_exec()</b> returns
1541  the error PCRE_ERROR_BADUTF8. If <i>startoffset</i> contains an invalid value,  the error PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is
1542  PCRE_ERROR_BADUTF8_OFFSET is returned.  a truncated UTF-8 character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
1543    both cases, information about the precise nature of the error may also be
1544    returned (see the descriptions of these errors in the section entitled \fIError
1545    return values from\fP <b>pcre_exec()</b>
1546    <a href="#errorlist">below).</a>
1547    If <i>startoffset</i> contains a value that does not point to the start of a
1548    UTF-8 character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
1549    returned.
1550  </P>  </P>
1551  <P>  <P>
1552  If you already know that your subject is valid, and you want to skip these  If you already know that your subject is valid, and you want to skip these
# Line 1354  checks for performance reasons, you can Line 1554  checks for performance reasons, you can
1554  calling <b>pcre_exec()</b>. You might want to do this for the second and  calling <b>pcre_exec()</b>. You might want to do this for the second and
1555  subsequent calls to <b>pcre_exec()</b> if you are making repeated calls to find  subsequent calls to <b>pcre_exec()</b> if you are making repeated calls to find
1556  all the matches in a single subject string. However, you should be sure that  all the matches in a single subject string. However, you should be sure that
1557  the value of <i>startoffset</i> points to the start of a UTF-8 character. When  the value of <i>startoffset</i> points to the start of a UTF-8 character (or the
1558  PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid UTF-8 string as a  end of the subject). When PCRE_NO_UTF8_CHECK is set, the effect of passing an
1559  subject, or a value of <i>startoffset</i> that does not point to the start of a  invalid UTF-8 string as a subject or an invalid value of <i>startoffset</i> is
1560  UTF-8 character, is undefined. Your program may crash.  undefined. Your program may crash.
1561  <pre>  <pre>
1562    PCRE_PARTIAL    PCRE_PARTIAL_HARD
1563  </pre>    PCRE_PARTIAL_SOFT
1564  This option turns on the partial matching feature. If the subject string fails  </pre>
1565  to match the pattern, but at some point during the matching process the end of  These options turn on the partial matching feature. For backwards
1566  the subject was reached (that is, the subject partially matches the pattern and  compatibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial match
1567  the failure to match occurred only because there were not enough subject  occurs if the end of the subject string is reached successfully, but there are
1568  characters), <b>pcre_exec()</b> returns PCRE_ERROR_PARTIAL instead of  not enough subject characters to complete the match. If this happens when
1569  PCRE_ERROR_NOMATCH. When PCRE_PARTIAL is used, there are restrictions on what  PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set, matching continues by
1570  may appear in the pattern. These are discussed in the  testing any remaining alternatives. Only if no complete match can be found is
1571    PCRE_ERROR_PARTIAL returned instead of PCRE_ERROR_NOMATCH. In other words,
1572    PCRE_PARTIAL_SOFT says that the caller is prepared to handle a partial match,
1573    but only if no complete match can be found.
1574    </P>
1575    <P>
1576    If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
1577    partial match is found, <b>pcre_exec()</b> immediately returns
1578    PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
1579    when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
1580    important that an alternative complete match.
1581    </P>
1582    <P>
1583    In both cases, the portion of the string that was inspected when the partial
1584    match was found is set as the first matching string. There is a more detailed
1585    discussion of partial and multi-segment matching, with examples, in the
1586  <a href="pcrepartial.html"><b>pcrepartial</b></a>  <a href="pcrepartial.html"><b>pcrepartial</b></a>
1587  documentation.  documentation.
1588  </P>  </P>
# Line 1377  The string to be matched by pcre_exec Line 1592  The string to be matched by pcre_exec
1592  <P>  <P>
1593  The subject string is passed to <b>pcre_exec()</b> as a pointer in  The subject string is passed to <b>pcre_exec()</b> as a pointer in
1594  <i>subject</i>, a length (in bytes) in <i>length</i>, and a starting byte offset  <i>subject</i>, a length (in bytes) in <i>length</i>, and a starting byte offset
1595  in <i>startoffset</i>. In UTF-8 mode, the byte offset must point to the start of  in <i>startoffset</i>. If this is negative or greater than the length of the
1596  a UTF-8 character. Unlike the pattern string, the subject may contain binary  subject, <b>pcre_exec()</b> returns PCRE_ERROR_BADOFFSET. When the starting
1597  zero bytes. When the starting offset is zero, the search for a match starts at  offset is zero, the search for a match starts at the beginning of the subject,
1598  the beginning of the subject, and this is by far the most common case.  and this is by far the most common case. In UTF-8 mode, the byte offset must
1599    point to the start of a UTF-8 character (or the end of the subject). Unlike the
1600    pattern string, the subject may contain binary zero bytes.
1601  </P>  </P>
1602  <P>  <P>
1603  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
# Line 1402  set to 4, it finds the second occurrence Line 1619  set to 4, it finds the second occurrence
1619  behind the starting point to discover that it is preceded by a letter.  behind the starting point to discover that it is preceded by a letter.
1620  </P>  </P>
1621  <P>  <P>
1622    Finding all the matches in a subject is tricky when the pattern can match an
1623    empty string. It is possible to emulate Perl's /g behaviour by first trying the
1624    match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
1625    PCRE_ANCHORED options, and then if that fails, advancing the starting offset
1626    and trying an ordinary match again. There is some code that demonstrates how to
1627    do this in the
1628    <a href="pcredemo.html"><b>pcredemo</b></a>
1629    sample program. In the most general case, you have to check to see if the
1630    newline convention recognizes CRLF as a newline, and if so, and the current
1631    character is CR followed by LF, advance the starting offset by two characters
1632    instead of one.
1633    </P>
1634    <P>
1635  If a non-zero starting offset is passed when the pattern is anchored, one  If a non-zero starting offset is passed when the pattern is anchored, one
1636  attempt to match at the given offset is made. This can only succeed if the  attempt to match at the given offset is made. This can only succeed if the
1637  pattern does not require the match to be at the start of the subject.  pattern does not require the match to be at the start of the subject.
# Line 1464  has to get additional memory for use dur Line 1694  has to get additional memory for use dur
1694  advisable to supply an <i>ovector</i>.  advisable to supply an <i>ovector</i>.
1695  </P>  </P>
1696  <P>  <P>
1697  The <b>pcre_info()</b> function can be used to find out how many capturing  The <b>pcre_fullinfo()</b> function can be used to find out how many capturing
1698  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1699  <i>ovector</i> that will allow for <i>n</i> captured substrings, in addition to  <i>ovector</i> that will allow for <i>n</i> captured substrings, in addition to
1700  the offsets of the substring matched by the whole pattern, is (<i>n</i>+1)*3.  the offsets of the substring matched by the whole pattern, is (<i>n</i>+1)*3.
# Line 1482  Offset values that correspond to unused Line 1712  Offset values that correspond to unused
1712  expression are also set to -1. For example, if the string "abc" is matched  expression are also set to -1. For example, if the string "abc" is matched
1713  against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The  against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
1714  return from the function is 2, because the highest used capturing subpattern  return from the function is 2, because the highest used capturing subpattern
1715  number is 1. However, you can refer to the offsets for the second and third  number is 1, and the offsets for for the second and third capturing subpatterns
1716  capturing subpatterns if you wish (assuming the vector is large enough, of  (assuming the vector is large enough, of course) are set to -1.
1717  course).  </P>
1718    <P>
1719    <b>Note</b>: Elements of <i>ovector</i> that do not correspond to capturing
1720    parentheses in the pattern are never changed. That is, if a pattern contains
1721    <i>n</i> capturing parentheses, no more than <i>ovector[0]</i> to
1722    <i>ovector[2n+1]</i> are set by <b>pcre_exec()</b>. The other elements retain
1723    whatever values they previously had.
1724  </P>  </P>
1725  <P>  <P>
1726  Some convenience functions are provided for extracting the captured substrings  Some convenience functions are provided for extracting the captured substrings
# Line 1531  If a pattern contains back references, b Line 1767  If a pattern contains back references, b
1767  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
1768  call via <b>pcre_malloc()</b> fails, this error is given. The memory is  call via <b>pcre_malloc()</b> fails, this error is given. The memory is
1769  automatically freed at the end of matching.  automatically freed at the end of matching.
1770    </P>
1771    <P>
1772    This error is also given if <b>pcre_stack_malloc()</b> fails in
1773    <b>pcre_exec()</b>. This can happen only when PCRE has been compiled with
1774    <b>--disable-stack-for-recursion</b>.
1775  <pre>  <pre>
1776    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1777  </pre>  </pre>
# Line 1553  documentation for details. Line 1794  documentation for details.
1794  <pre>  <pre>
1795    PCRE_ERROR_BADUTF8        (-10)    PCRE_ERROR_BADUTF8        (-10)
1796  </pre>  </pre>
1797  A string that contains an invalid UTF-8 byte sequence was passed as a subject.  A string that contains an invalid UTF-8 byte sequence was passed as a subject,
1798    and the PCRE_NO_UTF8_CHECK option was not set. If the size of the output vector
1799    (<i>ovecsize</i>) is at least 2, the byte offset to the start of the the invalid
1800    UTF-8 character is placed in the first element, and a reason code is placed in
1801    the second element. The reason codes are listed in the
1802    <a href="#badutf8reasons">following section.</a>
1803    For backward compatibility, if PCRE_PARTIAL_HARD is set and the problem is a
1804    truncated UTF-8 character at the end of the subject (reason codes 1 to 5),
1805    PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
1806  <pre>  <pre>
1807    PCRE_ERROR_BADUTF8_OFFSET (-11)    PCRE_ERROR_BADUTF8_OFFSET (-11)
1808  </pre>  </pre>
1809  The UTF-8 byte sequence that was passed as a subject was valid, but the value  The UTF-8 byte sequence that was passed as a subject was checked and found to
1810  of <i>startoffset</i> did not point to the beginning of a UTF-8 character.  be valid (the PCRE_NO_UTF8_CHECK option was not set), but the value of
1811    <i>startoffset</i> did not point to the beginning of a UTF-8 character or the
1812    end of the subject.
1813  <pre>  <pre>
1814    PCRE_ERROR_PARTIAL        (-12)    PCRE_ERROR_PARTIAL        (-12)
1815  </pre>  </pre>
# Line 1568  documentation for details of partial mat Line 1819  documentation for details of partial mat
1819  <pre>  <pre>
1820    PCRE_ERROR_BADPARTIAL     (-13)    PCRE_ERROR_BADPARTIAL     (-13)
1821  </pre>  </pre>
1822  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
1823  are not supported for partial matching. See the  option was used with a compiled pattern containing items that were not
1824  <a href="pcrepartial.html"><b>pcrepartial</b></a>  supported for partial matching. From release 8.00 onwards, there are no
1825  documentation for details of partial matching.  restrictions on partial matching.
1826  <pre>  <pre>
1827    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
1828  </pre>  </pre>
# Line 1591  description above. Line 1842  description above.
1842    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
1843  </pre>  </pre>
1844  An invalid combination of PCRE_NEWLINE_<i>xxx</i> options was given.  An invalid combination of PCRE_NEWLINE_<i>xxx</i> options was given.
1845    <pre>
1846      PCRE_ERROR_BADOFFSET      (-24)
1847    </pre>
1848    The value of <i>startoffset</i> was negative or greater than the length of the
1849    subject, that is, the value in <i>length</i>.
1850    <pre>
1851      PCRE_ERROR_SHORTUTF8      (-25)
1852    </pre>
1853    This error is returned instead of PCRE_ERROR_BADUTF8 when the subject string
1854    ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD option is set.
1855    Information about the failure is returned as for PCRE_ERROR_BADUTF8. It is in
1856    fact sufficient to detect this case, but this special error code for
1857    PCRE_PARTIAL_HARD precedes the implementation of returned information; it is
1858    retained for backwards compatibility.
1859    <pre>
1860      PCRE_ERROR_RECURSELOOP    (-26)
1861    </pre>
1862    This error is returned when <b>pcre_exec()</b> detects a recursion loop within
1863    the pattern. Specifically, it means that either the whole pattern or a
1864    subpattern has been called recursively for the second time at the same position
1865    in the subject string. Some simple patterns that might do this are detected and
1866    faulted at compile time, but more complicated cases, in particular mutual
1867    recursions between two different subpatterns, cannot be detected until run
1868    time.
1869  </P>  </P>
1870  <P>  <P>
1871  Error numbers -16 to -20 and -22 are not used by <b>pcre_exec()</b>.  Error numbers -16 to -20 and -22 are not used by <b>pcre_exec()</b>.
1872    <a name="badutf8reasons"></a></P>
1873    <br><b>
1874    Reason codes for invalid UTF-8 strings
1875    </b><br>
1876    <P>
1877    When <b>pcre_exec()</b> returns either PCRE_ERROR_BADUTF8 or
1878    PCRE_ERROR_SHORTUTF8, and the size of the output vector (<i>ovecsize</i>) is at
1879    least 2, the offset of the start of the invalid UTF-8 character is placed in
1880    the first output vector element (<i>ovector[0]</i>) and a reason code is placed
1881    in the second element (<i>ovector[1]</i>). The reason codes are given names in
1882    the <b>pcre.h</b> header file:
1883    <pre>
1884      PCRE_UTF8_ERR1
1885      PCRE_UTF8_ERR2
1886      PCRE_UTF8_ERR3
1887      PCRE_UTF8_ERR4
1888      PCRE_UTF8_ERR5
1889    </pre>
1890    The string ends with a truncated UTF-8 character; the code specifies how many
1891    bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8 characters to be
1892    no longer than 4 bytes, the encoding scheme (originally defined by RFC 2279)
1893    allows for up to 6 bytes, and this is checked first; hence the possibility of
1894    4 or 5 missing bytes.
1895    <pre>
1896      PCRE_UTF8_ERR6
1897      PCRE_UTF8_ERR7
1898      PCRE_UTF8_ERR8
1899      PCRE_UTF8_ERR9
1900      PCRE_UTF8_ERR10
1901    </pre>
1902    The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of the
1903    character do not have the binary value 0b10 (that is, either the most
1904    significant bit is 0, or the next bit is 1).
1905    <pre>
1906      PCRE_UTF8_ERR11
1907      PCRE_UTF8_ERR12
1908    </pre>
1909    A character that is valid by the RFC 2279 rules is either 5 or 6 bytes long;
1910    these code points are excluded by RFC 3629.
1911    <pre>
1912      PCRE_UTF8_ERR13
1913    </pre>
1914    A 4-byte character has a value greater than 0x10fff; these code points are
1915    excluded by RFC 3629.
1916    <pre>
1917      PCRE_UTF8_ERR14
1918    </pre>
1919    A 3-byte character has a value in the range 0xd800 to 0xdfff; this range of
1920    code points are reserved by RFC 3629 for use with UTF-16, and so are excluded
1921    from UTF-8.
1922    <pre>
1923      PCRE_UTF8_ERR15
1924      PCRE_UTF8_ERR16
1925      PCRE_UTF8_ERR17
1926      PCRE_UTF8_ERR18
1927      PCRE_UTF8_ERR19
1928    </pre>
1929    A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes for a
1930    value that can be represented by fewer bytes, which is invalid. For example,
1931    the two bytes 0xc0, 0xae give the value 0x2e, whose correct coding uses just
1932    one byte.
1933    <pre>
1934      PCRE_UTF8_ERR20
1935    </pre>
1936    The two most significant bits of the first byte of a character have the binary
1937    value 0b10 (that is, the most significant bit is 1 and the second is 0). Such a
1938    byte can only validly occur as the second or subsequent byte of a multi-byte
1939    character.
1940    <pre>
1941      PCRE_UTF8_ERR21
1942    </pre>
1943    The first byte of a character has the value 0xfe or 0xff. These values can
1944    never occur in a valid UTF-8 string.
1945  </P>  </P>
1946  <br><a name="SEC15" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>  <br><a name="SEC15" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>
1947  <P>  <P>
# Line 1743  then call pcre_copy_substring() o Line 2091  then call pcre_copy_substring() o
2091  appropriate. <b>NOTE:</b> If PCRE_DUPNAMES is set and there are duplicate names,  appropriate. <b>NOTE:</b> If PCRE_DUPNAMES is set and there are duplicate names,
2092  the behaviour may not be what you want (see the next section).  the behaviour may not be what you want (see the next section).
2093  </P>  </P>
2094    <P>
2095    <b>Warning:</b> If the pattern uses the (?| feature to set up multiple
2096    subpatterns with the same number, as described in the
2097    <a href="pcrepattern.html#dupsubpatternnumber">section on duplicate subpattern numbers</a>
2098    in the
2099    <a href="pcrepattern.html"><b>pcrepattern</b></a>
2100    page, you cannot use names to distinguish the different subpatterns, because
2101    names are not included in the compiled code. The matching process uses only
2102    numbers. For this reason, the use of different names for subpatterns of the
2103    same number causes an error at compile time.
2104    </P>
2105  <br><a name="SEC17" href="#TOC1">DUPLICATE SUBPATTERN NAMES</a><br>  <br><a name="SEC17" href="#TOC1">DUPLICATE SUBPATTERN NAMES</a><br>
2106  <P>  <P>
2107  <b>int pcre_get_stringtable_entries(const pcre *<i>code</i>,</b>  <b>int pcre_get_stringtable_entries(const pcre *<i>code</i>,</b>
# Line 1750  the behaviour may not be what you want ( Line 2109  the behaviour may not be what you want (
2109  </P>  </P>
2110  <P>  <P>
2111  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
2112  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
2113  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
2114  example is shown in the  such subpatterns are named, they are required to use the same names.)
2115    </P>
2116    <P>
2117    Normally, patterns with duplicate names are such that in any one match, only
2118    one of the named subpatterns participates. An example is shown in the
2119  <a href="pcrepattern.html"><b>pcrepattern</b></a>  <a href="pcrepattern.html"><b>pcrepattern</b></a>
2120  documentation.  documentation.
2121  </P>  </P>
# Line 1772  fourth are pointers to variables which a Line 2135  fourth are pointers to variables which a
2135  has run, they point to the first and last entries in the name-to-number table  has run, they point to the first and last entries in the name-to-number table
2136  for the given name. The function itself returns the length of each entry, or  for the given name. The function itself returns the length of each entry, or
2137  PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is  PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
2138  described above in the section entitled <i>Information about a pattern</i>.  described above in the section entitled <i>Information about a pattern</i>
2139    <a href="#infoaboutpattern">above.</a>
2140  Given all the relevant entries for the name, you can extract each of their  Given all the relevant entries for the name, you can extract each of their
2141  numbers, and hence the captured data, if any.  numbers, and hence the captured data, if any.
2142  </P>  </P>
# Line 1808  a compiled pattern, using a matching alg Line 2172  a compiled pattern, using a matching alg
2172  just once, and does not backtrack. This has different characteristics to the  just once, and does not backtrack. This has different characteristics to the
2173  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
2174  patterns are not supported. Nevertheless, there are times when this kind of  patterns are not supported. Nevertheless, there are times when this kind of
2175  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
2176  the  list of features that <b>pcre_dfa_exec()</b> does not support, see the
2177  <a href="pcrematching.html"><b>pcrematching</b></a>  <a href="pcrematching.html"><b>pcrematching</b></a>
2178  documentation.  documentation.
2179  </P>  </P>
# Line 1851  Option bits for pcre_dfa_exec() Line 2215  Option bits for pcre_dfa_exec()
2215  <P>  <P>
2216  The unused bits of the <i>options</i> argument for <b>pcre_dfa_exec()</b> must be  The unused bits of the <i>options</i> argument for <b>pcre_dfa_exec()</b> must be
2217  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_<i>xxx</i>,  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_<i>xxx</i>,
2218  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
2219  PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last three of these are  PCRE_NO_UTF8_CHECK, PCRE_BSR_ANYCRLF, PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE,
2220  the same as for <b>pcre_exec()</b>, so their description is not repeated here.  PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART.
2221  <pre>  All but the last four of these are exactly the same as for <b>pcre_exec()</b>,
2222    PCRE_PARTIAL  so their description is not repeated here.
2223  </pre>  <pre>
2224  This has the same general effect as it does for <b>pcre_exec()</b>, but the    PCRE_PARTIAL_HARD
2225  details are slightly different. When PCRE_PARTIAL is set for    PCRE_PARTIAL_SOFT
2226  <b>pcre_dfa_exec()</b>, the return code PCRE_ERROR_NOMATCH is converted into  </pre>
2227  PCRE_ERROR_PARTIAL if the end of the subject is reached, there have been no  These have the same general effect as they do for <b>pcre_exec()</b>, but the
2228  complete matches, but there is still at least one matching possibility. The  details are slightly different. When PCRE_PARTIAL_HARD is set for
2229  portion of the string that provided the partial match is set as the first  <b>pcre_dfa_exec()</b>, it returns PCRE_ERROR_PARTIAL if the end of the subject
2230  matching string.  is reached and there is still at least one matching possibility that requires
2231    additional characters. This happens even if some complete matches have also
2232    been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
2233    is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
2234    there have been no complete matches, but there is still at least one matching
2235    possibility. The portion of the string that was inspected when the longest
2236    partial match was found is set as the first matching string in both cases.
2237    There is a more detailed discussion of partial and multi-segment matching, with
2238    examples, in the
2239    <a href="pcrepartial.html"><b>pcrepartial</b></a>
2240    documentation.
2241  <pre>  <pre>
2242    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
2243  </pre>  </pre>
# Line 1874  matching point in the subject string. Line 2248  matching point in the subject string.
2248  <pre>  <pre>
2249    PCRE_DFA_RESTART    PCRE_DFA_RESTART
2250  </pre>  </pre>
2251  When <b>pcre_dfa_exec()</b> is called with the PCRE_PARTIAL option, and returns  When <b>pcre_dfa_exec()</b> returns a partial match, it is possible to call it
2252  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
2253  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
2254  option requests this action; when it is set, the <i>workspace</i> and  <i>workspace</i> and <i>wscount</i> options must reference the same vector as
2255  <i>wscount</i> 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
2256  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  
2257  <a href="pcrepartial.html"><b>pcrepartial</b></a>  <a href="pcrepartial.html"><b>pcrepartial</b></a>
2258  documentation.  documentation.
2259  </P>  </P>
# Line 1976  Cambridge CB2 3QH, England. Line 2349  Cambridge CB2 3QH, England.
2349  </P>  </P>
2350  <br><a name="SEC22" href="#TOC1">REVISION</a><br>  <br><a name="SEC22" href="#TOC1">REVISION</a><br>
2351  <P>  <P>
2352  Last updated: 24 August 2008  Last updated: 13 August 2011
2353  <br>  <br>
2354  Copyright &copy; 1997-2008 University of Cambridge.  Copyright &copy; 1997-2011 University of Cambridge.
2355  <br>  <br>
2356  <p>  <p>
2357  Return to the <a href="index.html">PCRE index page</a>.  Return to the <a href="index.html">PCRE index page</a>.

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