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1  .TH PCREAPI 3  .TH PCREAPI 3
2  .SH NAME  .SH NAME
3  PCRE - Perl-compatible regular expressions  PCRE - Perl-compatible regular expressions
4  .SH "PCRE NATIVE API"  .SH "PCRE NATIVE API BASIC FUNCTIONS"
5  .rs  .rs
6  .sp  .sp
7  .B #include <pcre.h>  .B #include <pcre.h>
# Line 25  PCRE - Perl-compatible regular expressio Line 25  PCRE - Perl-compatible regular expressio
25  .ti +5n  .ti +5n
26  .B const char **\fIerrptr\fP);  .B const char **\fIerrptr\fP);
27  .PP  .PP
28    .B void pcre_free_study(pcre_extra *\fIextra\fP);
29    .PP
30  .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"  .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
31  .ti +5n  .ti +5n
32  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
33  .ti +5n  .ti +5n
34  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
35    .
36    .
37    .SH "PCRE NATIVE API AUXILIARY FUNCTIONS"
38    .rs
39    .sp
40    .B pcre_jit_stack *pcre_jit_stack_alloc(int \fIstartsize\fP, int \fImaxsize\fP);
41    .PP
42    .B void pcre_jit_stack_free(pcre_jit_stack *\fIstack\fP);
43    .PP
44    .B void pcre_assign_jit_stack(pcre_extra *\fIextra\fP,
45    .ti +5n
46    .B pcre_jit_callback \fIcallback\fP, void *\fIdata\fP);
47  .PP  .PP
48  .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"  .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
49  .ti +5n  .ti +5n
# Line 114  PCRE - Perl-compatible regular expressio Line 128  PCRE - Perl-compatible regular expressio
128  .sp  .sp
129  PCRE has its own native API, which is described in this document. There are  PCRE has its own native API, which is described in this document. There are
130  also some wrapper functions that correspond to the POSIX regular expression  also some wrapper functions that correspond to the POSIX regular expression
131  API. These are described in the  API, but they do not give access to all the functionality. They are described
132    in the
133  .\" HREF  .\" HREF
134  \fBpcreposix\fP  \fBpcreposix\fP
135  .\"  .\"
136  documentation. Both of these APIs define a set of C function calls. A C++  documentation. Both of these APIs define a set of C function calls. A C++
137  wrapper is distributed with PCRE. It is documented in the  wrapper is also distributed with PCRE. It is documented in the
138  .\" HREF  .\" HREF
139  \fBpcrecpp\fP  \fBpcrecpp\fP
140  .\"  .\"
# Line 132  an application that uses PCRE. The heade Line 147  an application that uses PCRE. The heade
147  and PCRE_MINOR to contain the major and minor release numbers for the library.  and PCRE_MINOR to contain the major and minor release numbers for the library.
148  Applications can use these to include support for different releases of PCRE.  Applications can use these to include support for different releases of PCRE.
149  .P  .P
150    In a Windows environment, if you want to statically link an application program
151    against a non-dll \fBpcre.a\fP file, you must define PCRE_STATIC before
152    including \fBpcre.h\fP or \fBpcrecpp.h\fP, because otherwise the
153    \fBpcre_malloc()\fP and \fBpcre_free()\fP exported functions will be declared
154    \fB__declspec(dllimport)\fP, with unwanted results.
155    .P
156  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,
157  and \fBpcre_exec()\fP are used for compiling and matching regular expressions  and \fBpcre_exec()\fP are used for compiling and matching regular expressions
158  in a Perl-compatible manner. A sample program that demonstrates the simplest  in a Perl-compatible manner. A sample program that demonstrates the simplest
159  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
160  distribution. The  source distribution. A listing of this program is given in the
161    .\" HREF
162    \fBpcredemo\fP
163    .\"
164    documentation, and the
165  .\" HREF  .\" HREF
166  \fBpcresample\fP  \fBpcresample\fP
167  .\"  .\"
168  documentation describes how to compile and run it.  documentation describes how to compile and run it.
169  .P  .P
170    Just-in-time compiler support is an optional feature of PCRE that can be built
171    in appropriate hardware environments. It greatly speeds up the matching
172    performance of many patterns. Simple programs can request its use if available.
173    More complicated programs might need to make use of the
174    \fBpcre_jit_stack_alloc()\fP, \fBpcre_jit_stack_free()\fP, and
175    \fBpcre_assign_jit_stack()\fP functions in order to control its memory usage.
176    These functions are discussed in the
177    .\" HREF
178    \fBpcrejit\fP
179    .\"
180    documentation.
181    .P
182  A second matching function, \fBpcre_dfa_exec()\fP, which is not  A second matching function, \fBpcre_dfa_exec()\fP, 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  .\" HREF  .\" HREF
190  \fBpcrematching\fP  \fBpcrematching\fP
191  .\"  .\"
# Line 271  callout function pointed to by \fBpcre_c Line 309  callout function pointed to by \fBpcre_c
309  .P  .P
310  The compiled form of a regular expression is not altered during matching, so  The compiled form of a regular expression is not altered during matching, so
311  the same compiled pattern can safely be used by several threads at once.  the same compiled pattern can safely be used by several threads at once.
312    .P
313    If the just-in-time optimization feature is being used, it needs separate
314    memory stack areas for each thread. See the
315    .\" HREF
316    \fBpcrejit\fP
317    .\"
318    documentation for more details.
319  .  .
320  .  .
321  .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"  .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"
# Line 313  otherwise it is set to zero. Line 358  otherwise it is set to zero.
358  The output is an integer that is set to one if support for Unicode character  The output is an integer that is set to one if support for Unicode character
359  properties is available; otherwise it is set to zero.  properties is available; otherwise it is set to zero.
360  .sp  .sp
361      PCRE_CONFIG_JIT
362    .sp
363    The output is an integer that is set to one if support for just-in-time
364    compiling is available; otherwise it is set to zero.
365    .sp
366    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
367  .sp  .sp
368  The output is an integer whose value specifies the default character sequence  The output is an integer whose value specifies the default character sequence
# Line 390  avoiding the use of the stack. Line 440  avoiding the use of the stack.
440  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
441  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
442  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,
443  \fIerrorcodeptr\fP, via which a numerical error code can be returned.  \fIerrorcodeptr\fP, via which a numerical error code can be returned. To avoid
444    too much repetition, we refer just to \fBpcre_compile()\fP below, but the
445    information applies equally to \fBpcre_compile2()\fP.
446  .P  .P
447  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
448  \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 407  argument, which is an address (see below Line 459  argument, which is an address (see below
459  The \fIoptions\fP argument contains various bit settings that affect the  The \fIoptions\fP argument contains various bit settings that affect the
460  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
461  options are described below. Some of them (in particular, those that are  options are described below. Some of them (in particular, those that are
462  compatible with Perl, but also some others) can also be set and unset from  compatible with Perl, but some others as well) can also be set and unset from
463  within the pattern (see the detailed description in the  within the pattern (see the detailed description in the
464  .\" HREF  .\" HREF
465  \fBpcrepattern\fP  \fBpcrepattern\fP
466  .\"  .\"
467  documentation). For those options that can be different in different parts of  documentation). For those options that can be different in different parts of
468  the pattern, the contents of the \fIoptions\fP argument specifies their initial  the pattern, the contents of the \fIoptions\fP argument specifies their
469  settings at the start of compilation and execution. The PCRE_ANCHORED and  settings at the start of compilation and execution. The PCRE_ANCHORED,
470  PCRE_NEWLINE_\fIxxx\fP options can be set at the time of matching as well as at  PCRE_BSR_\fIxxx\fP, PCRE_NEWLINE_\fIxxx\fP, PCRE_NO_UTF8_CHECK, and
471    PCRE_NO_START_OPT options can be set at the time of matching as well as at
472  compile time.  compile time.
473  .P  .P
474  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
475  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
476  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
477  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
478  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
479  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
480  \fIerroffset\fP, which must not be NULL. If it is, an immediate error is given.  variable pointed to by \fIerroffset\fP, which must not be NULL (if it is, an
481    immediate error is given). However, for an invalid UTF-8 string, the offset is
482    that of the first byte of the failing character. Also, some errors are not
483    detected until checks are carried out when the whole pattern has been scanned;
484    in these cases the offset passed back is the length of the pattern.
485    .P
486    Note that the offset is in bytes, not characters, even in UTF-8 mode. It may
487    sometimes point into the middle of a UTF-8 character.
488  .P  .P
489  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
490  \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 503  pattern. Line 563  pattern.
563  .sp  .sp
564    PCRE_DOTALL    PCRE_DOTALL
565  .sp  .sp
566  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
567  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
568  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,
569  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
570  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
571  the setting of this option.  (?s) option setting. A negative class such as [^a] always matches newline
572    characters, independent of the setting of this option.
573  .sp  .sp
574    PCRE_DUPNAMES    PCRE_DUPNAMES
575  .sp  .sp
# Line 530  unescaped # outside a character class an Line 591  unescaped # outside a character class an
591  ignored. This is equivalent to Perl's /x option, and it can be changed within a  ignored. This is equivalent to Perl's /x option, and it can be changed within a
592  pattern by a (?x) option setting.  pattern by a (?x) option setting.
593  .P  .P
594    Which characters are interpreted as newlines is controlled by the options
595    passed to \fBpcre_compile()\fP or by a special sequence at the start of the
596    pattern, as described in the section entitled
597    .\" HTML <a href="pcrepattern.html#newlines">
598    .\" </a>
599    "Newline conventions"
600    .\"
601    in the \fBpcrepattern\fP documentation. Note that the end of this type of
602    comment is a literal newline sequence in the pattern; escape sequences that
603    happen to represent a newline do not count.
604    .P
605  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
606  Note, however, that this applies only to data characters. Whitespace characters  Note, however, that this applies only to data characters. Whitespace characters
607  may never appear within special character sequences in a pattern, for example  may never appear within special character sequences in a pattern, for example
608  within the sequence (?( which introduces a conditional subpattern.  within the sequence (?( that introduces a conditional subpattern.
609  .sp  .sp
610    PCRE_EXTRA    PCRE_EXTRA
611  .sp  .sp
# Line 543  set, any backslash in a pattern that is Line 615  set, any backslash in a pattern that is
615  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
616  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
617  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
618  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
619  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)
620    option setting within a pattern.
621  .sp  .sp
622    PCRE_FIRSTLINE    PCRE_FIRSTLINE
623  .sp  .sp
# Line 607  option, the combination may or may not b Line 680  option, the combination may or may not b
680  PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but  PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
681  other combinations may yield unused numbers and cause an error.  other combinations may yield unused numbers and cause an error.
682  .P  .P
683  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
684  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,
685  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
686  line break sequence. In other circumstances, line break sequences are treated  indicates a comment that lasts until after the next line break sequence. In
687  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
688  as whitespace characters and are therefore ignored.  data.
689  .P  .P
690  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
691  for \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, but it can be overridden.  for \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, but it can be overridden.
# Line 625  were followed by ?: but named parenthese Line 698  were followed by ?: but named parenthese
698  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
699  in Perl.  in Perl.
700  .sp  .sp
701      NO_START_OPTIMIZE
702    .sp
703    This is an option that acts at matching time; that is, it is really an option
704    for \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. If it is set at compile time,
705    it is remembered with the compiled pattern and assumed at matching time. For
706    details see the discussion of PCRE_NO_START_OPTIMIZE
707    .\" HTML <a href="#execoptions">
708    .\" </a>
709    below.
710    .\"
711    .sp
712      PCRE_UCP
713    .sp
714    This option changes the way PCRE processes \eB, \eb, \eD, \ed, \eS, \es, \eW,
715    \ew, and some of the POSIX character classes. By default, only ASCII characters
716    are recognized, but if PCRE_UCP is set, Unicode properties are used instead to
717    classify characters. More details are given in the section on
718    .\" HTML <a href="pcre.html#genericchartypes">
719    .\" </a>
720    generic character types
721    .\"
722    in the
723    .\" HREF
724    \fBpcrepattern\fP
725    .\"
726    page. If you set PCRE_UCP, matching one of the items it affects takes much
727    longer. The option is available only if PCRE has been compiled with Unicode
728    property support.
729    .sp
730    PCRE_UNGREEDY    PCRE_UNGREEDY
731  .sp  .sp
732  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 638  of UTF-8 characters instead of single-by Line 740  of UTF-8 characters instead of single-by
740  available only when PCRE is built to include UTF-8 support. If not, the use  available only when PCRE is built to include UTF-8 support. If not, the use
741  of this option provokes an error. Details of how this option changes the  of this option provokes an error. Details of how this option changes the
742  behaviour of PCRE are given in the  behaviour of PCRE are given in the
 .\" HTML <a href="pcre.html#utf8support">  
 .\" </a>  
 section on UTF-8 support  
 .\"  
 in the main  
743  .\" HREF  .\" HREF
744  \fBpcre\fP  \fBpcreunicode\fP
745  .\"  .\"
746  page.  page.
747  .sp  .sp
# Line 714  out of use. To avoid confusion, they hav Line 811  out of use. To avoid confusion, they hav
811    34  character value in \ex{...} sequence is too large    34  character value in \ex{...} sequence is too large
812    35  invalid condition (?(0)    35  invalid condition (?(0)
813    36  \eC not allowed in lookbehind assertion    36  \eC not allowed in lookbehind assertion
814    37  PCRE does not support \eL, \el, \eN, \eU, or \eu    37  PCRE does not support \eL, \el, \eN{name}, \eU, or \eu
815    38  number after (?C is > 255    38  number after (?C is > 255
816    39  closing ) for (?C expected    39  closing ) for (?C expected
817    40  recursive call could loop indefinitely    40  recursive call could loop indefinitely
# Line 730  out of use. To avoid confusion, they hav Line 827  out of use. To avoid confusion, they hav
827    50  [this code is not in use]    50  [this code is not in use]
828    51  octal value is greater than \e377 (not in UTF-8 mode)    51  octal value is greater than \e377 (not in UTF-8 mode)
829    52  internal error: overran compiling workspace    52  internal error: overran compiling workspace
830    53  internal error: previously-checked referenced subpattern not found    53  internal error: previously-checked referenced subpattern
831            not found
832    54  DEFINE group contains more than one branch    54  DEFINE group contains more than one branch
833    55  repeating a DEFINE group is not allowed    55  repeating a DEFINE group is not allowed
834    56  inconsistent NEWLINE options    56  inconsistent NEWLINE options
835    57  \eg is not followed by a braced, angle-bracketed, or quoted    57  \eg is not followed by a braced, angle-bracketed, or quoted
836          name/number or by a plain number          name/number or by a plain number
837    58  a numbered reference must not be zero    58  a numbered reference must not be zero
838    59  (*VERB) with an argument is not supported    59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
839    60  (*VERB) not recognized    60  (*VERB) not recognized
840    61  number is too big    61  number is too big
841    62  subpattern name expected    62  subpattern name expected
842    63  digit expected after (?+    63  digit expected after (?+
843    64  ] is an invalid data character in JavaScript compatibility mode    64  ] is an invalid data character in JavaScript compatibility mode
844      65  different names for subpatterns of the same number are
845            not allowed
846      66  (*MARK) must have an argument
847      67  this version of PCRE is not compiled with PCRE_UCP support
848      68  \ec must be followed by an ASCII character
849      69  \ek is not followed by a braced, angle-bracketed, or quoted name
850  .sp  .sp
851  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
852  be used if the limits were changed when PCRE was built.  be used if the limits were changed when PCRE was built.
853  .  .
854  .  .
855    .\" HTML <a name="studyingapattern"></a>
856  .SH "STUDYING A PATTERN"  .SH "STUDYING A PATTERN"
857  .rs  .rs
858  .sp  .sp
# Line 764  help speed up matching, \fBpcre_study()\ Line 869  help speed up matching, \fBpcre_study()\
869  results of the study.  results of the study.
870  .P  .P
871  The returned value from \fBpcre_study()\fP can be passed directly to  The returned value from \fBpcre_study()\fP can be passed directly to
872  \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
873  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
874  described  passed; these are described
875  .\" HTML <a href="#extradata">  .\" HTML <a href="#extradata">
876  .\" </a>  .\" </a>
877  below  below
878  .\"  .\"
879  in the section on matching a pattern.  in the section on matching a pattern.
880  .P  .P
881  If studying the pattern does not produce any additional information  If studying the pattern does not produce any useful information,
882  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program
883  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
884  own \fBpcre_extra\fP block.  \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block.
885  .P  .P
886  The second argument of \fBpcre_study()\fP contains option bits. At present, no  The second argument of \fBpcre_study()\fP contains option bits. There is only
887  options are defined, and this argument should always be zero.  one option: PCRE_STUDY_JIT_COMPILE. If this is set, and the just-in-time
888    compiler is available, the pattern is further compiled into machine code that
889    executes much faster than the \fBpcre_exec()\fP matching function. If
890    the just-in-time compiler is not available, this option is ignored. All other
891    bits in the \fIoptions\fP argument must be zero.
892    .P
893    JIT compilation is a heavyweight optimization. It can take some time for
894    patterns to be analyzed, and for one-off matches and simple patterns the
895    benefit of faster execution might be offset by a much slower study time.
896    Not all patterns can be optimized by the JIT compiler. For those that cannot be
897    handled, matching automatically falls back to the \fBpcre_exec()\fP
898    interpreter. For more details, see the
899    .\" HREF
900    \fBpcrejit\fP
901    .\"
902    documentation.
903  .P  .P
904  The third argument for \fBpcre_study()\fP is a pointer for an error message. If  The third argument for \fBpcre_study()\fP is a pointer for an error message. If
905  studying succeeds (even if no data is returned), the variable it points to is  studying succeeds (even if no data is returned), the variable it points to is
# Line 788  static string that is part of the librar Line 908  static string that is part of the librar
908  should test the error pointer for NULL after calling \fBpcre_study()\fP, to be  should test the error pointer for NULL after calling \fBpcre_study()\fP, to be
909  sure that it has run successfully.  sure that it has run successfully.
910  .P  .P
911  This is a typical call to \fBpcre_study\fP():  When you are finished with a pattern, you can free the memory used for the
912    study data by calling \fBpcre_free_study()\fP. This function was added to the
913    API for release 8.20. For earlier versions, the memory could be freed with
914    \fBpcre_free()\fP, just like the pattern itself. This will still work in cases
915    where PCRE_STUDY_JIT_COMPILE is not used, but it is advisable to change to the
916    new function when convenient.
917    .P
918    This is a typical way in which \fBpcre_study\fP() is used (except that in a
919    real application there should be tests for errors):
920  .sp  .sp
921    pcre_extra *pe;    int rc;
922    pe = pcre_study(    pcre *re;
923      pcre_extra *sd;
924      re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
925      sd = pcre_study(
926      re,             /* result of pcre_compile() */      re,             /* result of pcre_compile() */
927      0,              /* no options exist */      0,              /* no options */
928      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
929  .sp    rc = pcre_exec(   /* see below for details of pcre_exec() options */
930  At present, studying a pattern is useful only for non-anchored patterns that do      re, sd, "subject", 7, 0, 0, ovector, 30);
931  not have a single fixed starting character. A bitmap of possible starting    ...
932  bytes is created.    pcre_free_study(sd);
933      pcre_free(re);
934    .sp
935    Studying a pattern does two things: first, a lower bound for the length of
936    subject string that is needed to match the pattern is computed. This does not
937    mean that there are any strings of that length that match, but it does
938    guarantee that no shorter strings match. The value is used by
939    \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP to avoid wasting time by trying to
940    match strings that are shorter than the lower bound. You can find out the value
941    in a calling program via the \fBpcre_fullinfo()\fP function.
942    .P
943    Studying a pattern is also useful for non-anchored patterns that do not have a
944    single fixed starting character. A bitmap of possible starting bytes is
945    created. This speeds up finding a position in the subject at which to start
946    matching.
947    .P
948    These two optimizations apply to both \fBpcre_exec()\fP and
949    \fBpcre_dfa_exec()\fP. However, they are not used by \fBpcre_exec()\fP if
950    \fBpcre_study()\fP is called with the PCRE_STUDY_JIT_COMPILE option, and
951    just-in-time compiling is successful. The optimizations can be disabled by
952    setting the PCRE_NO_START_OPTIMIZE option when calling \fBpcre_exec()\fP or
953    \fBpcre_dfa_exec()\fP. You might want to do this if your pattern contains
954    callouts or (*MARK) (which cannot be handled by the JIT compiler), and you want
955    to make use of these facilities in cases where matching fails. See the
956    discussion of PCRE_NO_START_OPTIMIZE
957    .\" HTML <a href="#execoptions">
958    .\" </a>
959    below.
960    .\"
961  .  .
962  .  .
963  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
# Line 808  bytes is created. Line 967  bytes is created.
967  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters,
968  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
969  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
970  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
971  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
972  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
973  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
974  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
975    handling characters with codes greater than 128, you should either use UTF-8
976    and Unicode, or use locales, but not try to mix the two.
977  .P  .P
978  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
979  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 857  one in which it was compiled. Passing ta Line 1018  one in which it was compiled. Passing ta
1018  below in the section on matching a pattern.  below in the section on matching a pattern.
1019  .  .
1020  .  .
1021    .\" HTML <a name="infoaboutpattern"></a>
1022  .SH "INFORMATION ABOUT A PATTERN"  .SH "INFORMATION ABOUT A PATTERN"
1023  .rs  .rs
1024  .sp  .sp
# Line 888  check against passing an arbitrary memor Line 1050  check against passing an arbitrary memor
1050    size_t length;    size_t length;
1051    rc = pcre_fullinfo(    rc = pcre_fullinfo(
1052      re,               /* result of pcre_compile() */      re,               /* result of pcre_compile() */
1053      pe,               /* result of pcre_study(), or NULL */      sd,               /* result of pcre_study(), or NULL */
1054      PCRE_INFO_SIZE,   /* what is required */      PCRE_INFO_SIZE,   /* what is required */
1055      &length);         /* where to put the data */      &length);         /* where to put the data */
1056  .sp  .sp
# Line 953  Return 1 if the (?J) or (?-J) option set Line 1115  Return 1 if the (?J) or (?-J) option set
1115  0. The fourth argument should point to an \fBint\fP variable. (?J) and  0. The fourth argument should point to an \fBint\fP variable. (?J) and
1116  (?-J) set and unset the local PCRE_DUPNAMES option, respectively.  (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
1117  .sp  .sp
1118      PCRE_INFO_JIT
1119    .sp
1120    Return 1 if the pattern was studied with the PCRE_STUDY_JIT_COMPILE option, and
1121    just-in-time compiling was successful. The fourth argument should point to an
1122    \fBint\fP variable. A return value of 0 means that JIT support is not available
1123    in this version of PCRE, or that the pattern was not studied with the
1124    PCRE_STUDY_JIT_COMPILE option, or that the JIT compiler could not handle this
1125    particular pattern. See the
1126    .\" HREF
1127    \fBpcrejit\fP
1128    .\"
1129    documentation for details of what can and cannot be handled.
1130    .sp
1131    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
1132  .sp  .sp
1133  Return the value of the rightmost literal byte that must exist in any matched  Return the value of the rightmost literal byte that must exist in any matched
# Line 963  follows something of variable length. Fo Line 1138  follows something of variable length. Fo
1138  /^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
1139  is -1.  is -1.
1140  .sp  .sp
1141      PCRE_INFO_MINLENGTH
1142    .sp
1143    If the pattern was studied and a minimum length for matching subject strings
1144    was computed, its value is returned. Otherwise the returned value is -1. The
1145    value is a number of characters, not bytes (this may be relevant in UTF-8
1146    mode). The fourth argument should point to an \fBint\fP variable. A
1147    non-negative value is a lower bound to the length of any matching string. There
1148    may not be any strings of that length that do actually match, but every string
1149    that does match is at least that long.
1150    .sp
1151    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
1152    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
1153    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
# Line 983  entry; both of these return an \fBint\fP Line 1168  entry; both of these return an \fBint\fP
1168  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
1169  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
1170  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
1171  rest of the entry is the corresponding name, zero terminated. The names are in  rest of the entry is the corresponding name, zero terminated.
1172  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of  .P
1173  their parentheses numbers. For example, consider the following pattern (assume  The names are in alphabetical order. Duplicate names may appear if (?| is used
1174  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  to create multiple groups with the same number, as described in the
1175    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1176    .\" </a>
1177    section on duplicate subpattern numbers
1178    .\"
1179    in the
1180    .\" HREF
1181    \fBpcrepattern\fP
1182    .\"
1183    page. Duplicate names for subpatterns with different numbers are permitted only
1184    if PCRE_DUPNAMES is set. In all cases of duplicate names, they appear in the
1185    table in the order in which they were found in the pattern. In the absence of
1186    (?| this is the order of increasing number; when (?| is used this is not
1187    necessarily the case because later subpatterns may have lower numbers.
1188    .P
1189    As a simple example of the name/number table, consider the following pattern
1190    (assume PCRE_EXTENDED is set, so white space - including newlines - is
1191    ignored):
1192  .sp  .sp
1193  .\" JOIN  .\" JOIN
1194    (?<date> (?<year>(\ed\ed)?\ed\ed) -    (?<date> (?<year>(\ed\ed)?\ed\ed) -
# Line 1007  different for each compiled pattern. Line 1209  different for each compiled pattern.
1209  .sp  .sp
1210    PCRE_INFO_OKPARTIAL    PCRE_INFO_OKPARTIAL
1211  .sp  .sp
1212  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
1213  fourth argument should point to an \fBint\fP variable. The  \fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
1214    \fBint\fP variable. From release 8.00, this always returns 1, because the
1215    restrictions that previously applied to partial matching have been lifted. The
1216  .\" HREF  .\" HREF
1217  \fBpcrepartial\fP  \fBpcrepartial\fP
1218  .\"  .\"
1219  documentation lists the restrictions that apply to patterns when partial  documentation gives details of partial matching.
 matching is used.  
1220  .sp  .sp
1221    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1222  .sp  .sp
# Line 1047  variable. Line 1250  variable.
1250  .sp  .sp
1251    PCRE_INFO_STUDYSIZE    PCRE_INFO_STUDYSIZE
1252  .sp  .sp
1253  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 a
1254  a \fBpcre_extra\fP block. That is, it is the value that was passed to  \fBpcre_extra\fP block. If \fBpcre_extra\fP is NULL, or there is no study data,
1255  \fBpcre_malloc()\fP when PCRE was getting memory into which to place the data  zero is returned. The fourth argument should point to a \fBsize_t\fP variable.
1256  created by \fBpcre_study()\fP. The fourth argument should point to a  The \fIstudy_data\fP field is set by \fBpcre_study()\fP to record information
1257  \fBsize_t\fP variable.  that will speed up matching (see the section entitled
1258    .\" HTML <a href="#studyingapattern">
1259    .\" </a>
1260    "Studying a pattern"
1261    .\"
1262    above). The format of the \fIstudy_data\fP block is private, but its length
1263    is made available via this option so that it can be saved and restored (see the
1264    .\" HREF
1265    \fBpcreprecompile\fP
1266    .\"
1267    documentation for details).
1268  .  .
1269  .  .
1270  .SH "OBSOLETE INFO FUNCTION"  .SH "OBSOLETE INFO FUNCTION"
# Line 1112  is different. (This seems a highly unlik Line 1325  is different. (This seems a highly unlik
1325  .P  .P
1326  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
1327  compiled pattern, which is passed in the \fIcode\fP argument. If the  compiled pattern, which is passed in the \fIcode\fP argument. If the
1328  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
1329  \fIextra\fP argument. This function is the main matching facility of the  \fIextra\fP argument. This function is the main matching facility of the
1330  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
1331  also an alternative matching function, which is described  also an alternative matching function, which is described
# Line 1146  Here is an example of a simple call to \ Line 1359  Here is an example of a simple call to \
1359      ovector,        /* vector of integers for substring information */      ovector,        /* vector of integers for substring information */
1360      30);            /* number of elements (NOT size in bytes) */      30);            /* number of elements (NOT size in bytes) */
1361  .  .
1362    .
1363  .\" HTML <a name="extradata"></a>  .\" HTML <a name="extradata"></a>
1364  .SS "Extra data for \fBpcre_exec()\fR"  .SS "Extra data for \fBpcre_exec()\fR"
1365  .rs  .rs
# Line 1158  fields (not necessarily in this order): Line 1372  fields (not necessarily in this order):
1372  .sp  .sp
1373    unsigned long int \fIflags\fP;    unsigned long int \fIflags\fP;
1374    void *\fIstudy_data\fP;    void *\fIstudy_data\fP;
1375      void *\fIexecutable_jit\fP;
1376    unsigned long int \fImatch_limit\fP;    unsigned long int \fImatch_limit\fP;
1377    unsigned long int \fImatch_limit_recursion\fP;    unsigned long int \fImatch_limit_recursion\fP;
1378    void *\fIcallout_data\fP;    void *\fIcallout_data\fP;
1379    const unsigned char *\fItables\fP;    const unsigned char *\fItables\fP;
1380      unsigned char **\fImark\fP;
1381  .sp  .sp
1382  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
1383  are set. The flag bits are:  are set. The flag bits are:
1384  .sp  .sp
1385    PCRE_EXTRA_STUDY_DATA    PCRE_EXTRA_STUDY_DATA
1386      PCRE_EXTRA_EXECUTABLE_JIT
1387    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1388    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1389    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1390    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1391      PCRE_EXTRA_MARK
1392  .sp  .sp
1393  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 and sometimes
1394  \fBpcre_extra\fP block that is returned by \fBpcre_study()\fP, together with  the \fIexecutable_jit\fP field are set in the \fBpcre_extra\fP block that is
1395  the appropriate flag bit. You should not set this yourself, but you may add to  returned by \fBpcre_study()\fP, together with the appropriate flag bits. You
1396  the block by setting the other fields and their corresponding flag bits.  should not set these yourself, but you may add to the block by setting the
1397    other fields and their corresponding flag bits.
1398  .P  .P
1399  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
1400  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,
1401  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
1402  classic example is the use of nested unlimited repeats.  classic example is a pattern that uses nested unlimited repeats.
1403  .P  .P
1404  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly  Internally, \fBpcre_exec()\fP uses a function called \fBmatch()\fP, which it
1405  (sometimes recursively). The limit set by \fImatch_limit\fP is imposed on the  calls repeatedly (sometimes recursively). The limit set by \fImatch_limit\fP is
1406  number of times this function is called during a match, which has the effect of  imposed on the number of times this function is called during a match, which
1407  limiting the amount of backtracking that can take place. For patterns that are  has the effect of limiting the amount of backtracking that can take place. For
1408  not anchored, the count restarts from zero for each position in the subject  patterns that are not anchored, the count restarts from zero for each position
1409  string.  in the subject string.
1410    .P
1411    When \fBpcre_exec()\fP is called with a pattern that was successfully studied
1412    with the PCRE_STUDY_JIT_COMPILE option, the way that the matching is executed
1413    is entirely different. However, there is still the possibility of runaway
1414    matching that goes on for a very long time, and so the \fImatch_limit\fP value
1415    is also used in this case (but in a different way) to limit how long the
1416    matching can continue.
1417  .P  .P
1418  The default value for the limit can be set when PCRE is built; the default  The default value for the limit can be set when PCRE is built; the default
1419  default is 10 million, which handles all but the most extreme cases. You can  default is 10 million, which handles all but the most extreme cases. You can
# Line 1200  The \fImatch_limit_recursion\fP field is Line 1426  The \fImatch_limit_recursion\fP field is
1426  instead of limiting the total number of times that \fBmatch()\fP is called, it  instead of limiting the total number of times that \fBmatch()\fP is called, it
1427  limits the depth of recursion. The recursion depth is a smaller number than the  limits the depth of recursion. The recursion depth is a smaller number than the
1428  total number of calls, because not all calls to \fBmatch()\fP are recursive.  total number of calls, because not all calls to \fBmatch()\fP are recursive.
1429  This limit is of use only if it is set smaller than \fImatch_limit\fP.  This limit is of use only if it is set smaller than \fImatch_limit\fP.
1430  .P  .P
1431  Limiting the recursion depth limits the amount of stack that can be used, or,  Limiting the recursion depth limits the amount of machine stack that can be
1432  when PCRE has been compiled to use memory on the heap instead of the stack, the  used, or, when PCRE has been compiled to use memory on the heap instead of the
1433  amount of heap memory that can be used.  stack, the amount of heap memory that can be used. This limit is relevant, and
1434    is ignored, when the pattern was successfully studied with
1435    PCRE_STUDY_JIT_COMPILE.
1436  .P  .P
1437  The default value for \fImatch_limit_recursion\fP can be set when PCRE is  The default value for \fImatch_limit_recursion\fP can be set when PCRE is
1438  built; the default default is the same value as the default for  built; the default default is the same value as the default for
# Line 1213  with a \fBpcre_extra\fP block in which \ Line 1441  with a \fBpcre_extra\fP block in which \
1441  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
1442  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1443  .P  .P
1444  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,
1445  which is described in the  and is described in the
1446  .\" HREF  .\" HREF
1447  \fBpcrecallout\fP  \fBpcrecallout\fP
1448  .\"  .\"
# Line 1233  called. See the Line 1461  called. See the
1461  \fBpcreprecompile\fP  \fBpcreprecompile\fP
1462  .\"  .\"
1463  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1464    .P
1465    If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1466    be set to point to a \fBchar *\fP variable. If the pattern contains any
1467    backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1468    a name to pass back, a pointer to the name string (zero terminated) is placed
1469    in the variable pointed to by the \fImark\fP field. The names are within the
1470    compiled pattern; if you wish to retain such a name you must copy it before
1471    freeing the memory of a compiled pattern. If there is no name to pass back, the
1472    variable pointed to by the \fImark\fP field set to NULL. For details of the
1473    backtracking control verbs, see the section entitled
1474    .\" HTML <a href="pcrepattern#backtrackcontrol">
1475    .\" </a>
1476    "Backtracking control"
1477    .\"
1478    in the
1479    .\" HREF
1480    \fBpcrepattern\fP
1481    .\"
1482    documentation.
1483    .
1484  .  .
1485  .\" HTML <a name="execoptions"></a>  .\" HTML <a name="execoptions"></a>
1486  .SS "Option bits for \fBpcre_exec()\fP"  .SS "Option bits for \fBpcre_exec()\fP"
# Line 1240  documentation for a discussion of saving Line 1488  documentation for a discussion of saving
1488  .sp  .sp
1489  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
1490  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,
1491  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_START_OPTIMIZE,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1492  PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
1493    PCRE_PARTIAL_HARD.
1494  .sp  .sp
1495    PCRE_ANCHORED    PCRE_ANCHORED
1496  .sp  .sp
# Line 1316  match the empty string, the entire match Line 1565  match the empty string, the entire match
1565  .sp  .sp
1566    a?b?    a?b?
1567  .sp  .sp
1568  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
1569  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
1570  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".
1571  .P  .sp
1572  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case    PCRE_NOTEMPTY_ATSTART
1573  of a pattern match of the empty string within its \fBsplit()\fP function, and  .sp
1574  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
1575  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
1576  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the  can occur only if the pattern contains \eK.
1577  starting offset (see below) and trying an ordinary match again. There is some  .P
1578  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
1579    does make a special case of a pattern match of the empty string within its
1580    \fBsplit()\fP function, and when using the /g modifier. It is possible to
1581    emulate Perl's behaviour after matching a null string by first trying the match
1582    again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
1583    if that fails, by advancing the starting offset (see below) and trying an
1584    ordinary match again. There is some code that demonstrates how to do this in
1585    the
1586    .\" HREF
1587    \fBpcredemo\fP
1588    .\"
1589    sample program. In the most general case, you have to check to see if the
1590    newline convention recognizes CRLF as a newline, and if so, and the current
1591    character is CR followed by LF, advance the starting offset by two characters
1592    instead of one.
1593  .sp  .sp
1594    PCRE_NO_START_OPTIMIZE    PCRE_NO_START_OPTIMIZE
1595  .sp  .sp
1596  There are a number of optimizations that \fBpcre_exec()\fP uses at the start of  There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1597  a match, in order to speed up the process. For example, if it is known that a  a match, in order to speed up the process. For example, if it is known that an
1598  match must start with a specific character, it searches the subject for that  unanchored match must start with a specific character, it searches the subject
1599  character, and fails immediately if it cannot find it, without actually running  for that character, and fails immediately if it cannot find it, without
1600  the main matching function. When callouts are in use, these optimizations can  actually running the main matching function. This means that a special item
1601  cause them to be skipped. This option disables the "start-up" optimizations,  such as (*COMMIT) at the start of a pattern is not considered until after a
1602  causing performance to suffer, but ensuring that the callouts do occur.  suitable starting point for the match has been found. When callouts or (*MARK)
1603    items are in use, these "start-up" optimizations can cause them to be skipped
1604    if the pattern is never actually used. The start-up optimizations are in effect
1605    a pre-scan of the subject that takes place before the pattern is run.
1606    .P
1607    The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
1608    causing performance to suffer, but ensuring that in cases where the result is
1609    "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
1610    are considered at every possible starting position in the subject string. If
1611    PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
1612    time.
1613    .P
1614    Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
1615    Consider the pattern
1616    .sp
1617      (*COMMIT)ABC
1618    .sp
1619    When this is compiled, PCRE records the fact that a match must start with the
1620    character "A". Suppose the subject string is "DEFABC". The start-up
1621    optimization scans along the subject, finds "A" and runs the first match
1622    attempt from there. The (*COMMIT) item means that the pattern must match the
1623    current starting position, which in this case, it does. However, if the same
1624    match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
1625    subject string does not happen. The first match attempt is run starting from
1626    "D" and when this fails, (*COMMIT) prevents any further matches being tried, so
1627    the overall result is "no match". If the pattern is studied, more start-up
1628    optimizations may be used. For example, a minimum length for the subject may be
1629    recorded. Consider the pattern
1630    .sp
1631      (*MARK:A)(X|Y)
1632    .sp
1633    The minimum length for a match is one character. If the subject is "ABC", there
1634    will be attempts to match "ABC", "BC", "C", and then finally an empty string.
1635    If the pattern is studied, the final attempt does not take place, because PCRE
1636    knows that the subject is too short, and so the (*MARK) is never encountered.
1637    In this case, studying the pattern does not affect the overall match result,
1638    which is still "no match", but it does affect the auxiliary information that is
1639    returned.
1640  .sp  .sp
1641    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1642  .sp  .sp
# Line 1354  in the main Line 1654  in the main
1654  \fBpcre\fP  \fBpcre\fP
1655  .\"  .\"
1656  page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns  page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns
1657  the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP contains an invalid value,  the error PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is
1658  PCRE_ERROR_BADUTF8_OFFSET is returned.  a truncated UTF-8 character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
1659    both cases, information about the precise nature of the error may also be
1660    returned (see the descriptions of these errors in the section entitled \fIError
1661    return values from\fP \fBpcre_exec()\fP
1662    .\" HTML <a href="#errorlist">
1663    .\" </a>
1664    below).
1665    .\"
1666    If \fIstartoffset\fP contains a value that does not point to the start of a
1667    UTF-8 character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
1668    returned.
1669  .P  .P
1670  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
1671  checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when  checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when
1672  calling \fBpcre_exec()\fP. You might want to do this for the second and  calling \fBpcre_exec()\fP. You might want to do this for the second and
1673  subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find  subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find
1674  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
1675  the value of \fIstartoffset\fP points to the start of a UTF-8 character. When  the value of \fIstartoffset\fP points to the start of a UTF-8 character (or the
1676  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
1677  subject, or a value of \fIstartoffset\fP that does not point to the start of a  invalid UTF-8 string as a subject or an invalid value of \fIstartoffset\fP is
1678  UTF-8 character, is undefined. Your program may crash.  undefined. Your program may crash.
1679  .sp  .sp
1680    PCRE_PARTIAL    PCRE_PARTIAL_HARD
1681  .sp    PCRE_PARTIAL_SOFT
1682  This option turns on the partial matching feature. If the subject string fails  .sp
1683  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
1684  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
1685  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
1686  characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of  not enough subject characters to complete the match. If this happens when
1687  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
1688  may appear in the pattern. These are discussed in the  testing any remaining alternatives. Only if no complete match can be found is
1689    PCRE_ERROR_PARTIAL returned instead of PCRE_ERROR_NOMATCH. In other words,
1690    PCRE_PARTIAL_SOFT says that the caller is prepared to handle a partial match,
1691    but only if no complete match can be found.
1692    .P
1693    If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
1694    partial match is found, \fBpcre_exec()\fP immediately returns
1695    PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
1696    when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
1697    important that an alternative complete match.
1698    .P
1699    In both cases, the portion of the string that was inspected when the partial
1700    match was found is set as the first matching string. There is a more detailed
1701    discussion of partial and multi-segment matching, with examples, in the
1702  .\" HREF  .\" HREF
1703  \fBpcrepartial\fP  \fBpcrepartial\fP
1704  .\"  .\"
1705  documentation.  documentation.
1706  .  .
1707    .
1708  .SS "The string to be matched by \fBpcre_exec()\fP"  .SS "The string to be matched by \fBpcre_exec()\fP"
1709  .rs  .rs
1710  .sp  .sp
1711  The subject string is passed to \fBpcre_exec()\fP as a pointer in  The subject string is passed to \fBpcre_exec()\fP as a pointer in
1712  \fIsubject\fP, a length (in bytes) in \fIlength\fP, and a starting byte offset  \fIsubject\fP, a length (in bytes) in \fIlength\fP, and a starting byte offset
1713  in \fIstartoffset\fP. In UTF-8 mode, the byte offset must point to the start of  in \fIstartoffset\fP. If this is negative or greater than the length of the
1714  a UTF-8 character. Unlike the pattern string, the subject may contain binary  subject, \fBpcre_exec()\fP returns PCRE_ERROR_BADOFFSET. When the starting
1715  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,
1716  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
1717    point to the start of a UTF-8 character (or the end of the subject). Unlike the
1718    pattern string, the subject may contain binary zero bytes.
1719  .P  .P
1720  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
1721  same subject by calling \fBpcre_exec()\fP again after a previous success.  same subject by calling \fBpcre_exec()\fP again after a previous success.
# Line 1409  start of the subject, which is deemed to Line 1735  start of the subject, which is deemed to
1735  set to 4, it finds the second occurrence of "iss" because it is able to look  set to 4, it finds the second occurrence of "iss" because it is able to look
1736  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.
1737  .P  .P
1738    Finding all the matches in a subject is tricky when the pattern can match an
1739    empty string. It is possible to emulate Perl's /g behaviour by first trying the
1740    match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
1741    PCRE_ANCHORED options, and then if that fails, advancing the starting offset
1742    and trying an ordinary match again. There is some code that demonstrates how to
1743    do this in the
1744    .\" HREF
1745    \fBpcredemo\fP
1746    .\"
1747    sample program. In the most general case, you have to check to see if the
1748    newline convention recognizes CRLF as a newline, and if so, and the current
1749    character is CR followed by LF, advance the starting offset by two characters
1750    instead of one.
1751    .P
1752  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
1753  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
1754  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.
1755  .  .
1756    .
1757  .SS "How \fBpcre_exec()\fP returns captured substrings"  .SS "How \fBpcre_exec()\fP returns captured substrings"
1758  .rs  .rs
1759  .sp  .sp
# Line 1463  the \fIovector\fP is not big enough to r Line 1804  the \fIovector\fP is not big enough to r
1804  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
1805  advisable to supply an \fIovector\fP.  advisable to supply an \fIovector\fP.
1806  .P  .P
1807  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
1808  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1809  \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
1810  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 1479  Offset values that correspond to unused Line 1820  Offset values that correspond to unused
1820  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
1821  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
1822  return from the function is 2, because the highest used capturing subpattern  return from the function is 2, because the highest used capturing subpattern
1823  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
1824  capturing subpatterns if you wish (assuming the vector is large enough, of  (assuming the vector is large enough, of course) are set to -1.
1825  course).  .P
1826    \fBNote\fP: Elements in the first two-thids of \fIovector\fP that do not
1827    correspond to capturing parentheses in the pattern are never changed. That is,
1828    if a pattern contains \fIn\fP capturing parentheses, no more than
1829    \fIovector[0]\fP to \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other
1830    elements (in the first two-thirds) retain whatever values they previously had.
1831  .P  .P
1832  Some convenience functions are provided for extracting the captured substrings  Some convenience functions are provided for extracting the captured substrings
1833  as separate strings. These are described below.  as separate strings. These are described below.
1834  .  .
1835    .
1836  .\" HTML <a name="errorlist"></a>  .\" HTML <a name="errorlist"></a>
1837  .SS "Error return values from \fBpcre_exec()\fP"  .SS "Error return values from \fBpcre_exec()\fP"
1838  .rs  .rs
# Line 1527  If a pattern contains back references, b Line 1874  If a pattern contains back references, b
1874  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
1875  call via \fBpcre_malloc()\fP fails, this error is given. The memory is  call via \fBpcre_malloc()\fP fails, this error is given. The memory is
1876  automatically freed at the end of matching.  automatically freed at the end of matching.
1877    .P
1878    This error is also given if \fBpcre_stack_malloc()\fP fails in
1879    \fBpcre_exec()\fP. This can happen only when PCRE has been compiled with
1880    \fB--disable-stack-for-recursion\fP.
1881  .sp  .sp
1882    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1883  .sp  .sp
# Line 1551  documentation for details. Line 1902  documentation for details.
1902  .sp  .sp
1903    PCRE_ERROR_BADUTF8        (-10)    PCRE_ERROR_BADUTF8        (-10)
1904  .sp  .sp
1905  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,
1906    and the PCRE_NO_UTF8_CHECK option was not set. If the size of the output vector
1907    (\fIovecsize\fP) is at least 2, the byte offset to the start of the the invalid
1908    UTF-8 character is placed in the first element, and a reason code is placed in
1909    the second element. The reason codes are listed in the
1910    .\" HTML <a href="#badutf8reasons">
1911    .\" </a>
1912    following section.
1913    .\"
1914    For backward compatibility, if PCRE_PARTIAL_HARD is set and the problem is a
1915    truncated UTF-8 character at the end of the subject (reason codes 1 to 5),
1916    PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
1917  .sp  .sp
1918    PCRE_ERROR_BADUTF8_OFFSET (-11)    PCRE_ERROR_BADUTF8_OFFSET (-11)
1919  .sp  .sp
1920  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
1921  of \fIstartoffset\fP 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
1922    \fIstartoffset\fP did not point to the beginning of a UTF-8 character or the
1923    end of the subject.
1924  .sp  .sp
1925    PCRE_ERROR_PARTIAL        (-12)    PCRE_ERROR_PARTIAL        (-12)
1926  .sp  .sp
# Line 1568  documentation for details of partial mat Line 1932  documentation for details of partial mat
1932  .sp  .sp
1933    PCRE_ERROR_BADPARTIAL     (-13)    PCRE_ERROR_BADPARTIAL     (-13)
1934  .sp  .sp
1935  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
1936  are not supported for partial matching. See the  option was used with a compiled pattern containing items that were not
1937  .\" HREF  supported for partial matching. From release 8.00 onwards, there are no
1938  \fBpcrepartial\fP  restrictions on partial matching.
 .\"  
 documentation for details of partial matching.  
1939  .sp  .sp
1940    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
1941  .sp  .sp
# Line 1593  description above. Line 1955  description above.
1955    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
1956  .sp  .sp
1957  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
1958    .sp
1959      PCRE_ERROR_BADOFFSET      (-24)
1960    .sp
1961    The value of \fIstartoffset\fP was negative or greater than the length of the
1962    subject, that is, the value in \fIlength\fP.
1963    .sp
1964      PCRE_ERROR_SHORTUTF8      (-25)
1965    .sp
1966    This error is returned instead of PCRE_ERROR_BADUTF8 when the subject string
1967    ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD option is set.
1968    Information about the failure is returned as for PCRE_ERROR_BADUTF8. It is in
1969    fact sufficient to detect this case, but this special error code for
1970    PCRE_PARTIAL_HARD precedes the implementation of returned information; it is
1971    retained for backwards compatibility.
1972    .sp
1973      PCRE_ERROR_RECURSELOOP    (-26)
1974    .sp
1975    This error is returned when \fBpcre_exec()\fP detects a recursion loop within
1976    the pattern. Specifically, it means that either the whole pattern or a
1977    subpattern has been called recursively for the second time at the same position
1978    in the subject string. Some simple patterns that might do this are detected and
1979    faulted at compile time, but more complicated cases, in particular mutual
1980    recursions between two different subpatterns, cannot be detected until run
1981    time.
1982    .sp
1983      PCRE_ERROR_JIT_STACKLIMIT (-27)
1984    .sp
1985    This error is returned when a pattern that was successfully studied using the
1986    PCRE_STUDY_JIT_COMPILE option is matched, but the memory available for the
1987    just-in-time processing stack is not large enough. See the
1988    .\" HREF
1989    \fBpcrejit\fP
1990    .\"
1991    documentation for more details.
1992  .P  .P
1993  Error numbers -16 to -20 and -22 are not used by \fBpcre_exec()\fP.  Error numbers -16 to -20 and -22 are not used by \fBpcre_exec()\fP.
1994  .  .
1995  .  .
1996    .\" HTML <a name="badutf8reasons"></a>
1997    .SS "Reason codes for invalid UTF-8 strings"
1998    .rs
1999    .sp
2000    When \fBpcre_exec()\fP returns either PCRE_ERROR_BADUTF8 or
2001    PCRE_ERROR_SHORTUTF8, and the size of the output vector (\fIovecsize\fP) is at
2002    least 2, the offset of the start of the invalid UTF-8 character is placed in
2003    the first output vector element (\fIovector[0]\fP) and a reason code is placed
2004    in the second element (\fIovector[1]\fP). The reason codes are given names in
2005    the \fBpcre.h\fP header file:
2006    .sp
2007      PCRE_UTF8_ERR1
2008      PCRE_UTF8_ERR2
2009      PCRE_UTF8_ERR3
2010      PCRE_UTF8_ERR4
2011      PCRE_UTF8_ERR5
2012    .sp
2013    The string ends with a truncated UTF-8 character; the code specifies how many
2014    bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8 characters to be
2015    no longer than 4 bytes, the encoding scheme (originally defined by RFC 2279)
2016    allows for up to 6 bytes, and this is checked first; hence the possibility of
2017    4 or 5 missing bytes.
2018    .sp
2019      PCRE_UTF8_ERR6
2020      PCRE_UTF8_ERR7
2021      PCRE_UTF8_ERR8
2022      PCRE_UTF8_ERR9
2023      PCRE_UTF8_ERR10
2024    .sp
2025    The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of the
2026    character do not have the binary value 0b10 (that is, either the most
2027    significant bit is 0, or the next bit is 1).
2028    .sp
2029      PCRE_UTF8_ERR11
2030      PCRE_UTF8_ERR12
2031    .sp
2032    A character that is valid by the RFC 2279 rules is either 5 or 6 bytes long;
2033    these code points are excluded by RFC 3629.
2034    .sp
2035      PCRE_UTF8_ERR13
2036    .sp
2037    A 4-byte character has a value greater than 0x10fff; these code points are
2038    excluded by RFC 3629.
2039    .sp
2040      PCRE_UTF8_ERR14
2041    .sp
2042    A 3-byte character has a value in the range 0xd800 to 0xdfff; this range of
2043    code points are reserved by RFC 3629 for use with UTF-16, and so are excluded
2044    from UTF-8.
2045    .sp
2046      PCRE_UTF8_ERR15
2047      PCRE_UTF8_ERR16
2048      PCRE_UTF8_ERR17
2049      PCRE_UTF8_ERR18
2050      PCRE_UTF8_ERR19
2051    .sp
2052    A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes for a
2053    value that can be represented by fewer bytes, which is invalid. For example,
2054    the two bytes 0xc0, 0xae give the value 0x2e, whose correct coding uses just
2055    one byte.
2056    .sp
2057      PCRE_UTF8_ERR20
2058    .sp
2059    The two most significant bits of the first byte of a character have the binary
2060    value 0b10 (that is, the most significant bit is 1 and the second is 0). Such a
2061    byte can only validly occur as the second or subsequent byte of a multi-byte
2062    character.
2063    .sp
2064      PCRE_UTF8_ERR21
2065    .sp
2066    The first byte of a character has the value 0xfe or 0xff. These values can
2067    never occur in a valid UTF-8 string.
2068    .
2069    .
2070  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
2071  .rs  .rs
2072  .sp  .sp
# Line 1744  then call \fBpcre_copy_substring()\fP or Line 2214  then call \fBpcre_copy_substring()\fP or
2214  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,
2215  the behaviour may not be what you want (see the next section).  the behaviour may not be what you want (see the next section).
2216  .P  .P
2217  \fBWarning:\fP If the pattern uses the "(?|" feature to set up multiple  \fBWarning:\fP If the pattern uses the (?| feature to set up multiple
2218  subpatterns with the same number, you cannot use names to distinguish them,  subpatterns with the same number, as described in the
2219  because names are not included in the compiled code. The matching process uses  .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
2220  only numbers.  .\" </a>
2221    section on duplicate subpattern numbers
2222    .\"
2223    in the
2224    .\" HREF
2225    \fBpcrepattern\fP
2226    .\"
2227    page, you cannot use names to distinguish the different subpatterns, because
2228    names are not included in the compiled code. The matching process uses only
2229    numbers. For this reason, the use of different names for subpatterns of the
2230    same number causes an error at compile time.
2231  .  .
2232  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
2233  .rs  .rs
# Line 1757  only numbers. Line 2237  only numbers.
2237  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
2238  .PP  .PP
2239  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
2240  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
2241  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
2242  example is shown in the  such subpatterns are named, they are required to use the same names.)
2243    .P
2244    Normally, patterns with duplicate names are such that in any one match, only
2245    one of the named subpatterns participates. An example is shown in the
2246  .\" HREF  .\" HREF
2247  \fBpcrepattern\fP  \fBpcrepattern\fP
2248  .\"  .\"
# Line 1779  fourth are pointers to variables which a Line 2262  fourth are pointers to variables which a
2262  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
2263  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
2264  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
2265  described above in the section entitled \fIInformation about a pattern\fP.  described above in the section entitled \fIInformation about a pattern\fP
2266    .\" HTML <a href="#infoaboutpattern">
2267    .\" </a>
2268    above.
2269    .\"
2270  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
2271  numbers, and hence the captured data, if any.  numbers, and hence the captured data, if any.
2272  .  .
# Line 1823  a compiled pattern, using a matching alg Line 2310  a compiled pattern, using a matching alg
2310  just once, and does not backtrack. This has different characteristics to the  just once, and does not backtrack. This has different characteristics to the
2311  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
2312  patterns are not supported. Nevertheless, there are times when this kind of  patterns are not supported. Nevertheless, there are times when this kind of
2313  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
2314  the  list of features that \fBpcre_dfa_exec()\fP does not support, see the
2315  .\" HREF  .\" HREF
2316  \fBpcrematching\fP  \fBpcrematching\fP
2317  .\"  .\"
# Line 1863  Here is an example of a simple call to \ Line 2350  Here is an example of a simple call to \
2350  .sp  .sp
2351  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
2352  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,
2353  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
2354  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,
2355  the same as for \fBpcre_exec()\fP, so their description is not repeated here.  PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART.
2356  .sp  All but the last four of these are exactly the same as for \fBpcre_exec()\fP,
2357    PCRE_PARTIAL  so their description is not repeated here.
2358  .sp  .sp
2359  This has the same general effect as it does for \fBpcre_exec()\fP, but the    PCRE_PARTIAL_HARD
2360  details are slightly different. When PCRE_PARTIAL is set for    PCRE_PARTIAL_SOFT
2361  \fBpcre_dfa_exec()\fP, the return code PCRE_ERROR_NOMATCH is converted into  .sp
2362  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 \fBpcre_exec()\fP, but the
2363  complete matches, but there is still at least one matching possibility. The  details are slightly different. When PCRE_PARTIAL_HARD is set for
2364  portion of the string that provided the partial match is set as the first  \fBpcre_dfa_exec()\fP, it returns PCRE_ERROR_PARTIAL if the end of the subject
2365  matching string.  is reached and there is still at least one matching possibility that requires
2366    additional characters. This happens even if some complete matches have also
2367    been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
2368    is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
2369    there have been no complete matches, but there is still at least one matching
2370    possibility. The portion of the string that was inspected when the longest
2371    partial match was found is set as the first matching string in both cases.
2372    There is a more detailed discussion of partial and multi-segment matching, with
2373    examples, in the
2374    .\" HREF
2375    \fBpcrepartial\fP
2376    .\"
2377    documentation.
2378  .sp  .sp
2379    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
2380  .sp  .sp
# Line 1886  matching point in the subject string. Line 2385  matching point in the subject string.
2385  .sp  .sp
2386    PCRE_DFA_RESTART    PCRE_DFA_RESTART
2387  .sp  .sp
2388  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
2389  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
2390  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
2391  option requests this action; when it is set, the \fIworkspace\fP and  \fIworkspace\fP and \fIwscount\fP options must reference the same vector as
2392  \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
2393  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  
2394  .\" HREF  .\" HREF
2395  \fBpcrepartial\fP  \fBpcrepartial\fP
2396  .\"  .\"
2397  documentation.  documentation.
2398  .  .
2399    .
2400  .SS "Successful returns from \fBpcre_dfa_exec()\fP"  .SS "Successful returns from \fBpcre_dfa_exec()\fP"
2401  .rs  .rs
2402  .sp  .sp
# Line 1929  returns data, even though the meaning of Line 2428  returns data, even though the meaning of
2428  The strings are returned in reverse order of length; that is, the longest  The strings are returned in reverse order of length; that is, the longest
2429  matching string is given first. If there were too many matches to fit into  matching string is given first. If there were too many matches to fit into
2430  \fIovector\fP, the yield of the function is zero, and the vector is filled with  \fIovector\fP, the yield of the function is zero, and the vector is filled with
2431  the longest matches.  the longest matches. Unlike \fBpcre_exec()\fP, \fBpcre_dfa_exec()\fP can use
2432    the entire \fIovector\fP for returning matched strings.
2433    .
2434  .  .
2435  .SS "Error returns from \fBpcre_dfa_exec()\fP"  .SS "Error returns from \fBpcre_dfa_exec()\fP"
2436  .rs  .rs
# Line 1958  group. These are not supported. Line 2459  group. These are not supported.
2459    PCRE_ERROR_DFA_UMLIMIT    (-18)    PCRE_ERROR_DFA_UMLIMIT    (-18)
2460  .sp  .sp
2461  This return is given if \fBpcre_dfa_exec()\fP is called with an \fIextra\fP  This return is given if \fBpcre_dfa_exec()\fP is called with an \fIextra\fP
2462  block that contains a setting of the \fImatch_limit\fP field. This is not  block that contains a setting of the \fImatch_limit\fP or
2463  supported (it is meaningless).  \fImatch_limit_recursion\fP fields. This is not supported (these fields are
2464    meaningless for DFA matching).
2465  .sp  .sp
2466    PCRE_ERROR_DFA_WSSIZE     (-19)    PCRE_ERROR_DFA_WSSIZE     (-19)
2467  .sp  .sp
# Line 1996  Cambridge CB2 3QH, England. Line 2498  Cambridge CB2 3QH, England.
2498  .rs  .rs
2499  .sp  .sp
2500  .nf  .nf
2501  Last updated: 11 April 2009  Last updated: 29 August 2011
2502  Copyright (c) 1997-2009 University of Cambridge.  Copyright (c) 1997-2011 University of Cambridge.
2503  .fi  .fi

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