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revision 211 by ph10, Thu Aug 9 09:52:43 2007 UTC revision 975 by ph10, Sat Jun 2 11:03:06 2012 UTC
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1  .TH PCREAPI 3  .TH PCREAPI 3 "04 May 2012" "PCRE 8.31"
2  .SH NAME  .SH NAME
3  PCRE - Perl-compatible regular expressions  PCRE - Perl-compatible regular expressions
 .SH "PCRE NATIVE API"  
 .rs  
4  .sp  .sp
5  .B #include <pcre.h>  .B #include <pcre.h>
6  .PP  .
7    .
8    .SH "PCRE NATIVE API BASIC FUNCTIONS"
9    .rs
10    .sp
11  .SM  .SM
12  .B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,  .B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,
13  .ti +5n  .ti +5n
# Line 25  PCRE - Perl-compatible regular expressio Line 27  PCRE - Perl-compatible regular expressio
27  .ti +5n  .ti +5n
28  .B const char **\fIerrptr\fP);  .B const char **\fIerrptr\fP);
29  .PP  .PP
30    .B void pcre_free_study(pcre_extra *\fIextra\fP);
31    .PP
32  .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,"
33  .ti +5n  .ti +5n
34  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
# Line 38  PCRE - Perl-compatible regular expressio Line 42  PCRE - Perl-compatible regular expressio
42  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,
43  .ti +5n  .ti +5n
44  .B int *\fIworkspace\fP, int \fIwscount\fP);  .B int *\fIworkspace\fP, int \fIwscount\fP);
45  .PP  .
46    .
47    .SH "PCRE NATIVE API STRING EXTRACTION FUNCTIONS"
48    .rs
49    .sp
50  .B int pcre_copy_named_substring(const pcre *\fIcode\fP,  .B int pcre_copy_named_substring(const pcre *\fIcode\fP,
51  .ti +5n  .ti +5n
52  .B const char *\fIsubject\fP, int *\fIovector\fP,  .B const char *\fIsubject\fP, int *\fIovector\fP,
# Line 82  PCRE - Perl-compatible regular expressio Line 90  PCRE - Perl-compatible regular expressio
90  .B void pcre_free_substring(const char *\fIstringptr\fP);  .B void pcre_free_substring(const char *\fIstringptr\fP);
91  .PP  .PP
92  .B void pcre_free_substring_list(const char **\fIstringptr\fP);  .B void pcre_free_substring_list(const char **\fIstringptr\fP);
93    .
94    .
95    .SH "PCRE NATIVE API AUXILIARY FUNCTIONS"
96    .rs
97    .sp
98    .B pcre_jit_stack *pcre_jit_stack_alloc(int \fIstartsize\fP, int \fImaxsize\fP);
99    .PP
100    .B void pcre_jit_stack_free(pcre_jit_stack *\fIstack\fP);
101    .PP
102    .B void pcre_assign_jit_stack(pcre_extra *\fIextra\fP,
103    .ti +5n
104    .B pcre_jit_callback \fIcallback\fP, void *\fIdata\fP);
105  .PP  .PP
106  .B const unsigned char *pcre_maketables(void);  .B const unsigned char *pcre_maketables(void);
107  .PP  .PP
# Line 89  PCRE - Perl-compatible regular expressio Line 109  PCRE - Perl-compatible regular expressio
109  .ti +5n  .ti +5n
110  .B int \fIwhat\fP, void *\fIwhere\fP);  .B int \fIwhat\fP, void *\fIwhere\fP);
111  .PP  .PP
 .B int pcre_info(const pcre *\fIcode\fP, int *\fIoptptr\fP, int  
 .B *\fIfirstcharptr\fP);  
 .PP  
112  .B int pcre_refcount(pcre *\fIcode\fP, int \fIadjust\fP);  .B int pcre_refcount(pcre *\fIcode\fP, int \fIadjust\fP);
113  .PP  .PP
114  .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);  .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
115  .PP  .PP
116  .B char *pcre_version(void);  .B const char *pcre_version(void);
117  .PP  .PP
118    .B int pcre_pattern_to_host_byte_order(pcre *\fIcode\fP,
119    .ti +5n
120    .B pcre_extra *\fIextra\fP, const unsigned char *\fItables\fP);
121    .
122    .
123    .SH "PCRE NATIVE API INDIRECTED FUNCTIONS"
124    .rs
125    .sp
126  .B void *(*pcre_malloc)(size_t);  .B void *(*pcre_malloc)(size_t);
127  .PP  .PP
128  .B void (*pcre_free)(void *);  .B void (*pcre_free)(void *);
# Line 109  PCRE - Perl-compatible regular expressio Line 134  PCRE - Perl-compatible regular expressio
134  .B int (*pcre_callout)(pcre_callout_block *);  .B int (*pcre_callout)(pcre_callout_block *);
135  .  .
136  .  .
137    .SH "PCRE 8-BIT AND 16-BIT LIBRARIES"
138    .rs
139    .sp
140    From release 8.30, PCRE can be compiled as a library for handling 16-bit
141    character strings as well as, or instead of, the original library that handles
142    8-bit character strings. To avoid too much complication, this document
143    describes the 8-bit versions of the functions, with only occasional references
144    to the 16-bit library.
145    .P
146    The 16-bit functions operate in the same way as their 8-bit counterparts; they
147    just use different data types for their arguments and results, and their names
148    start with \fBpcre16_\fP instead of \fBpcre_\fP. For every option that has UTF8
149    in its name (for example, PCRE_UTF8), there is a corresponding 16-bit name with
150    UTF8 replaced by UTF16. This facility is in fact just cosmetic; the 16-bit
151    option names define the same bit values.
152    .P
153    References to bytes and UTF-8 in this document should be read as references to
154    16-bit data quantities and UTF-16 when using the 16-bit library, unless
155    specified otherwise. More details of the specific differences for the 16-bit
156    library are given in the
157    .\" HREF
158    \fBpcre16\fP
159    .\"
160    page.
161    .
162    .
163  .SH "PCRE API OVERVIEW"  .SH "PCRE API OVERVIEW"
164  .rs  .rs
165  .sp  .sp
166  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
167  also some wrapper functions that correspond to the POSIX regular expression  also some wrapper functions (for the 8-bit library only) that correspond to the
168  API. These are described in the  POSIX regular expression API, but they do not give access to all the
169    functionality. They are described in the
170  .\" HREF  .\" HREF
171  \fBpcreposix\fP  \fBpcreposix\fP
172  .\"  .\"
173  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++
174  wrapper is distributed with PCRE. It is documented in the  wrapper (again for the 8-bit library only) is also distributed with PCRE. It is
175    documented in the
176  .\" HREF  .\" HREF
177  \fBpcrecpp\fP  \fBpcrecpp\fP
178  .\"  .\"
179  page.  page.
180  .P  .P
181  The native API C function prototypes are defined in the header file  The native API C function prototypes are defined in the header file
182  \fBpcre.h\fP, and on Unix systems the library itself is called \fBlibpcre\fP.  \fBpcre.h\fP, and on Unix-like systems the (8-bit) library itself is called
183  It can normally be accessed by adding \fB-lpcre\fP to the command for linking  \fBlibpcre\fP. It can normally be accessed by adding \fB-lpcre\fP to the
184  an application that uses PCRE. The header file defines the macros PCRE_MAJOR  command for linking an application that uses PCRE. The header file defines the
185  and PCRE_MINOR to contain the major and minor release numbers for the library.  macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release numbers
186  Applications can use these to include support for different releases of PCRE.  for the library. Applications can use these to include support for different
187    releases of PCRE.
188    .P
189    In a Windows environment, if you want to statically link an application program
190    against a non-dll \fBpcre.a\fP file, you must define PCRE_STATIC before
191    including \fBpcre.h\fP or \fBpcrecpp.h\fP, because otherwise the
192    \fBpcre_malloc()\fP and \fBpcre_free()\fP exported functions will be declared
193    \fB__declspec(dllimport)\fP, with unwanted results.
194  .P  .P
195  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,
196  and \fBpcre_exec()\fP are used for compiling and matching regular expressions  and \fBpcre_exec()\fP are used for compiling and matching regular expressions
197  in a Perl-compatible manner. A sample program that demonstrates the simplest  in a Perl-compatible manner. A sample program that demonstrates the simplest
198  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
199  distribution. The  source distribution. A listing of this program is given in the
200    .\" HREF
201    \fBpcredemo\fP
202    .\"
203    documentation, and the
204  .\" HREF  .\" HREF
205  \fBpcresample\fP  \fBpcresample\fP
206  .\"  .\"
207  documentation describes how to run it.  documentation describes how to compile and run it.
208    .P
209    Just-in-time compiler support is an optional feature of PCRE that can be built
210    in appropriate hardware environments. It greatly speeds up the matching
211    performance of many patterns. Simple programs can easily request that it be
212    used if available, by setting an option that is ignored when it is not
213    relevant. More complicated programs might need to make use of the functions
214    \fBpcre_jit_stack_alloc()\fP, \fBpcre_jit_stack_free()\fP, and
215    \fBpcre_assign_jit_stack()\fP in order to control the JIT code's memory usage.
216    These functions are discussed in the
217    .\" HREF
218    \fBpcrejit\fP
219    .\"
220    documentation.
221  .P  .P
222  A second matching function, \fBpcre_dfa_exec()\fP, which is not  A second matching function, \fBpcre_dfa_exec()\fP, which is not
223  Perl-compatible, is also provided. This uses a different algorithm for the  Perl-compatible, is also provided. This uses a different algorithm for the
224  matching. The alternative algorithm finds all possible matches (at a given  matching. The alternative algorithm finds all possible matches (at a given
225  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
226  does not return captured substrings. A description of the two matching  lookbehind assertions). However, this algorithm does not return captured
227  algorithms and their advantages and disadvantages is given in the  substrings. A description of the two matching algorithms and their advantages
228    and disadvantages is given in the
229  .\" HREF  .\" HREF
230  \fBpcrematching\fP  \fBpcrematching\fP
231  .\"  .\"
# Line 175  specialist use. Most commonly, no specia Line 253  specialist use. Most commonly, no specia
253  internal tables that are generated when PCRE is built are used.  internal tables that are generated when PCRE is built are used.
254  .P  .P
255  The function \fBpcre_fullinfo()\fP is used to find out information about a  The function \fBpcre_fullinfo()\fP is used to find out information about a
256  compiled pattern; \fBpcre_info()\fP is an obsolete version that returns only  compiled pattern. The function \fBpcre_version()\fP returns a pointer to a
257  some of the available information, but is retained for backwards compatibility.  string containing the version of PCRE and its date of release.
 The function \fBpcre_version()\fP returns a pointer to a string containing the  
 version of PCRE and its date of release.  
258  .P  .P
259  The function \fBpcre_refcount()\fP maintains a reference count in a data block  The function \fBpcre_refcount()\fP maintains a reference count in a data block
260  containing a compiled pattern. This is provided for the benefit of  containing a compiled pattern. This is provided for the benefit of
# Line 218  points during a matching operation. Deta Line 294  points during a matching operation. Deta
294  documentation.  documentation.
295  .  .
296  .  .
297    .\" HTML <a name="newlines"></a>
298  .SH NEWLINES  .SH NEWLINES
299  .rs  .rs
300  .sp  .sp
# Line 225  PCRE supports five different conventions Line 302  PCRE supports five different conventions
302  strings: a single CR (carriage return) character, a single LF (linefeed)  strings: a single CR (carriage return) character, a single LF (linefeed)
303  character, the two-character sequence CRLF, any of the three preceding, or any  character, the two-character sequence CRLF, any of the three preceding, or any
304  Unicode newline sequence. The Unicode newline sequences are the three just  Unicode newline sequence. The Unicode newline sequences are the three just
305  mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed,  mentioned, plus the single characters VT (vertical tab, U+000B), FF (form feed,
306  U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS  U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
307  (paragraph separator, U+2029).  (paragraph separator, U+2029).
308  .P  .P
# Line 235  The default default is LF, which is the Line 312  The default default is LF, which is the
312  default can be overridden, either when a pattern is compiled, or when it is  default can be overridden, either when a pattern is compiled, or when it is
313  matched.  matched.
314  .P  .P
315    At compile time, the newline convention can be specified by the \fIoptions\fP
316    argument of \fBpcre_compile()\fP, or it can be specified by special text at the
317    start of the pattern itself; this overrides any other settings. See the
318    .\" HREF
319    \fBpcrepattern\fP
320    .\"
321    page for details of the special character sequences.
322    .P
323  In the PCRE documentation the word "newline" is used to mean "the character or  In the PCRE documentation the word "newline" is used to mean "the character or
324  pair of characters that indicate a line break". The choice of newline  pair of characters that indicate a line break". The choice of newline
325  convention affects the handling of the dot, circumflex, and dollar  convention affects the handling of the dot, circumflex, and dollar
326  metacharacters, the handling of #-comments in /x mode, and, when CRLF is a  metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
327  recognized line ending sequence, the match position advancement for a  recognized line ending sequence, the match position advancement for a
328  non-anchored pattern. The choice of newline convention does not affect the  non-anchored pattern. There is more detail about this in the
329  interpretation of the \en or \er escape sequences.  .\" HTML <a href="#execoptions">
330    .\" </a>
331    section on \fBpcre_exec()\fP options
332    .\"
333    below.
334    .P
335    The choice of newline convention does not affect the interpretation of
336    the \en or \er escape sequences, nor does it affect what \eR matches, which is
337    controlled in a similar way, but by separate options.
338  .  .
339  .  .
340  .SH MULTITHREADING  .SH MULTITHREADING
# Line 254  callout function pointed to by \fBpcre_c Line 347  callout function pointed to by \fBpcre_c
347  .P  .P
348  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
349  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.
350    .P
351    If the just-in-time optimization feature is being used, it needs separate
352    memory stack areas for each thread. See the
353    .\" HREF
354    \fBpcrejit\fP
355    .\"
356    documentation for more details.
357  .  .
358  .  .
359  .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"  .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"
# Line 265  which it was compiled. Details are given Line 365  which it was compiled. Details are given
365  .\" HREF  .\" HREF
366  \fBpcreprecompile\fP  \fBpcreprecompile\fP
367  .\"  .\"
368  documentation. However, compiling a regular expression with one version of PCRE  documentation, which includes a description of the
369  for use with a different version is not guaranteed to work and may cause  \fBpcre_pattern_to_host_byte_order()\fP function. However, compiling a regular
370  crashes.  expression with one version of PCRE for use with a different version is not
371    guaranteed to work and may cause crashes.
372  .  .
373  .  .
374  .SH "CHECKING BUILD-TIME OPTIONS"  .SH "CHECKING BUILD-TIME OPTIONS"
# Line 284  documentation has more details about the Line 385  documentation has more details about the
385  .P  .P
386  The first argument for \fBpcre_config()\fP is an integer, specifying which  The first argument for \fBpcre_config()\fP is an integer, specifying which
387  information is required; the second argument is a pointer to a variable into  information is required; the second argument is a pointer to a variable into
388  which the information is placed. The following information is available:  which the information is placed. The returned value is zero on success, or the
389    negative error code PCRE_ERROR_BADOPTION if the value in the first argument is
390    not recognized. The following information is available:
391  .sp  .sp
392    PCRE_CONFIG_UTF8    PCRE_CONFIG_UTF8
393  .sp  .sp
394  The output is an integer that is set to one if UTF-8 support is available;  The output is an integer that is set to one if UTF-8 support is available;
395  otherwise it is set to zero.  otherwise it is set to zero. If this option is given to the 16-bit version of
396    this function, \fBpcre16_config()\fP, the result is PCRE_ERROR_BADOPTION.
397    .sp
398      PCRE_CONFIG_UTF16
399    .sp
400    The output is an integer that is set to one if UTF-16 support is available;
401    otherwise it is set to zero. This value should normally be given to the 16-bit
402    version of this function, \fBpcre16_config()\fP. If it is given to the 8-bit
403    version of this function, the result is PCRE_ERROR_BADOPTION.
404  .sp  .sp
405    PCRE_CONFIG_UNICODE_PROPERTIES    PCRE_CONFIG_UNICODE_PROPERTIES
406  .sp  .sp
407  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
408  properties is available; otherwise it is set to zero.  properties is available; otherwise it is set to zero.
409  .sp  .sp
410      PCRE_CONFIG_JIT
411    .sp
412    The output is an integer that is set to one if support for just-in-time
413    compiling is available; otherwise it is set to zero.
414    .sp
415      PCRE_CONFIG_JITTARGET
416    .sp
417    The output is a pointer to a zero-terminated "const char *" string. If JIT
418    support is available, the string contains the name of the architecture for
419    which the JIT compiler is configured, for example "x86 32bit (little endian +
420    unaligned)". If JIT support is not available, the result is NULL.
421    .sp
422    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
423  .sp  .sp
424  The output is an integer whose value specifies the default character sequence  The output is an integer whose value specifies the default character sequence
425  that is recognized as meaning "newline". The four values that are supported  that is recognized as meaning "newline". The four values that are supported
426  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.
427  default should normally be the standard sequence for your operating system.  Though they are derived from ASCII, the same values are returned in EBCDIC
428    environments. The default should normally correspond to the standard sequence
429    for your operating system.
430    .sp
431      PCRE_CONFIG_BSR
432    .sp
433    The output is an integer whose value indicates what character sequences the \eR
434    escape sequence matches by default. A value of 0 means that \eR matches any
435    Unicode line ending sequence; a value of 1 means that \eR matches only CR, LF,
436    or CRLF. The default can be overridden when a pattern is compiled or matched.
437  .sp  .sp
438    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
439  .sp  .sp
440  The output is an integer that contains the number of bytes used for internal  The output is an integer that contains the number of bytes used for internal
441  linkage in compiled regular expressions. The value is 2, 3, or 4. Larger values  linkage in compiled regular expressions. For the 8-bit library, the value can
442  allow larger regular expressions to be compiled, at the expense of slower  be 2, 3, or 4. For the 16-bit library, the value is either 2 or 4 and is still
443  matching. The default value of 2 is sufficient for all but the most massive  a number of bytes. The default value of 2 is sufficient for all but the most
444  patterns, since it allows the compiled pattern to be up to 64K in size.  massive patterns, since it allows the compiled pattern to be up to 64K in size.
445    Larger values allow larger regular expressions to be compiled, at the expense
446    of slower matching.
447  .sp  .sp
448    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
449  .sp  .sp
# Line 323  documentation. Line 457  documentation.
457  .sp  .sp
458    PCRE_CONFIG_MATCH_LIMIT    PCRE_CONFIG_MATCH_LIMIT
459  .sp  .sp
460  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
461  internal matching function calls in a \fBpcre_exec()\fP execution. Further  internal matching function calls in a \fBpcre_exec()\fP execution. Further
462  details are given with \fBpcre_exec()\fP below.  details are given with \fBpcre_exec()\fP below.
463  .sp  .sp
464    PCRE_CONFIG_MATCH_LIMIT_RECURSION    PCRE_CONFIG_MATCH_LIMIT_RECURSION
465  .sp  .sp
466  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
467  recursion when calling the internal matching function in a \fBpcre_exec()\fP  recursion when calling the internal matching function in a \fBpcre_exec()\fP
468  execution. Further details are given with \fBpcre_exec()\fP below.  execution. Further details are given with \fBpcre_exec()\fP below.
469  .sp  .sp
# Line 364  avoiding the use of the stack. Line 498  avoiding the use of the stack.
498  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
499  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
500  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,
501  \fIerrorcodeptr\fP, via which a numerical error code can be returned.  \fIerrorcodeptr\fP, via which a numerical error code can be returned. To avoid
502    too much repetition, we refer just to \fBpcre_compile()\fP below, but the
503    information applies equally to \fBpcre_compile2()\fP.
504  .P  .P
505  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
506  \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 380  argument, which is an address (see below Line 516  argument, which is an address (see below
516  .P  .P
517  The \fIoptions\fP argument contains various bit settings that affect the  The \fIoptions\fP argument contains various bit settings that affect the
518  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
519  options are described below. Some of them, in particular, those that are  options are described below. Some of them (in particular, those that are
520  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
521  the detailed description in the  within the pattern (see the detailed description in the
522  .\" HREF  .\" HREF
523  \fBpcrepattern\fP  \fBpcrepattern\fP
524  .\"  .\"
525  documentation). For these options, the contents of the \fIoptions\fP argument  documentation). For those options that can be different in different parts of
526  specifies their initial settings at the start of compilation and execution. The  the pattern, the contents of the \fIoptions\fP argument specifies their
527  PCRE_ANCHORED and PCRE_NEWLINE_\fIxxx\fP options can be set at the time of  settings at the start of compilation and execution. The PCRE_ANCHORED,
528  matching as well as at compile time.  PCRE_BSR_\fIxxx\fP, PCRE_NEWLINE_\fIxxx\fP, PCRE_NO_UTF8_CHECK, and
529    PCRE_NO_START_OPTIMIZE options can be set at the time of matching as well as at
530    compile time.
531  .P  .P
532  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
533  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
534  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
535  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
536  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
537  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
538  \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
539    immediate error is given). However, for an invalid UTF-8 string, the offset is
540    that of the first byte of the failing character.
541    .P
542    Some errors are not detected until the whole pattern has been scanned; in these
543    cases, the offset passed back is the length of the pattern. Note that the
544    offset is in bytes, not characters, even in UTF-8 mode. It may sometimes point
545    into the middle of a UTF-8 character.
546  .P  .P
547  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
548  \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 444  facility, see the Line 589  facility, see the
589  .\"  .\"
590  documentation.  documentation.
591  .sp  .sp
592      PCRE_BSR_ANYCRLF
593      PCRE_BSR_UNICODE
594    .sp
595    These options (which are mutually exclusive) control what the \eR escape
596    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
597    match any Unicode newline sequence. The default is specified when PCRE is
598    built. It can be overridden from within the pattern, or by setting an option
599    when a compiled pattern is matched.
600    .sp
601    PCRE_CASELESS    PCRE_CASELESS
602  .sp  .sp
603  If this bit is set, letters in the pattern match both upper and lower case  If this bit is set, letters in the pattern match both upper and lower case
# Line 467  pattern. Line 621  pattern.
621  .sp  .sp
622    PCRE_DOTALL    PCRE_DOTALL
623  .sp  .sp
624  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
625  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
626  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,
627  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
628  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
629  the setting of this option.  (?s) option setting. A negative class such as [^a] always matches newline
630    characters, independent of the setting of this option.
631  .sp  .sp
632    PCRE_DUPNAMES    PCRE_DUPNAMES
633  .sp  .sp
# Line 487  documentation. Line 642  documentation.
642  .sp  .sp
643    PCRE_EXTENDED    PCRE_EXTENDED
644  .sp  .sp
645  If this bit is set, whitespace data characters in the pattern are totally  If this bit is set, white space data characters in the pattern are totally
646  ignored except when escaped or inside a character class. Whitespace does not  ignored except when escaped or inside a character class. White space does not
647  include the VT character (code 11). In addition, characters between an  include the VT character (code 11). In addition, characters between an
648  unescaped # outside a character class and the next newline, inclusive, are also  unescaped # outside a character class and the next newline, inclusive, are also
649  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
650  pattern by a (?x) option setting.  pattern by a (?x) option setting.
651  .P  .P
652    Which characters are interpreted as newlines is controlled by the options
653    passed to \fBpcre_compile()\fP or by a special sequence at the start of the
654    pattern, as described in the section entitled
655    .\" HTML <a href="pcrepattern.html#newlines">
656    .\" </a>
657    "Newline conventions"
658    .\"
659    in the \fBpcrepattern\fP documentation. Note that the end of this type of
660    comment is a literal newline sequence in the pattern; escape sequences that
661    happen to represent a newline do not count.
662    .P
663  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
664  Note, however, that this applies only to data characters. Whitespace characters  Note, however, that this applies only to data characters. White space characters
665  may never appear within special character sequences in a pattern, for example  may never appear within special character sequences in a pattern, for example
666  within the sequence (?( which introduces a conditional subpattern.  within the sequence (?( that introduces a conditional subpattern.
667  .sp  .sp
668    PCRE_EXTRA    PCRE_EXTRA
669  .sp  .sp
# Line 507  set, any backslash in a pattern that is Line 673  set, any backslash in a pattern that is
673  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
674  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
675  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
676  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
677  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)
678    option setting within a pattern.
679  .sp  .sp
680    PCRE_FIRSTLINE    PCRE_FIRSTLINE
681  .sp  .sp
# Line 516  If this option is set, an unanchored pat Line 683  If this option is set, an unanchored pat
683  the first newline in the subject string, though the matched text may continue  the first newline in the subject string, though the matched text may continue
684  over the newline.  over the newline.
685  .sp  .sp
686      PCRE_JAVASCRIPT_COMPAT
687    .sp
688    If this option is set, PCRE's behaviour is changed in some ways so that it is
689    compatible with JavaScript rather than Perl. The changes are as follows:
690    .P
691    (1) A lone closing square bracket in a pattern causes a compile-time error,
692    because this is illegal in JavaScript (by default it is treated as a data
693    character). Thus, the pattern AB]CD becomes illegal when this option is set.
694    .P
695    (2) At run time, a back reference to an unset subpattern group matches an empty
696    string (by default this causes the current matching alternative to fail). A
697    pattern such as (\e1)(a) succeeds when this option is set (assuming it can find
698    an "a" in the subject), whereas it fails by default, for Perl compatibility.
699    .P
700    (3) \eU matches an upper case "U" character; by default \eU causes a compile
701    time error (Perl uses \eU to upper case subsequent characters).
702    .P
703    (4) \eu matches a lower case "u" character unless it is followed by four
704    hexadecimal digits, in which case the hexadecimal number defines the code point
705    to match. By default, \eu causes a compile time error (Perl uses it to upper
706    case the following character).
707    .P
708    (5) \ex matches a lower case "x" character unless it is followed by two
709    hexadecimal digits, in which case the hexadecimal number defines the code point
710    to match. By default, as in Perl, a hexadecimal number is always expected after
711    \ex, but it may have zero, one, or two digits (so, for example, \exz matches a
712    binary zero character followed by z).
713    .sp
714    PCRE_MULTILINE    PCRE_MULTILINE
715  .sp  .sp
716  By default, PCRE treats the subject string as consisting of a single line of  By default, PCRE treats the subject string as consisting of a single line of
# Line 546  CRLF sequence. Setting PCRE_NEWLINE_ANYC Line 741  CRLF sequence. Setting PCRE_NEWLINE_ANYC
741  preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies  preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies
742  that any Unicode newline sequence should be recognized. The Unicode newline  that any Unicode newline sequence should be recognized. The Unicode newline
743  sequences are the three just mentioned, plus the single characters VT (vertical  sequences are the three just mentioned, plus the single characters VT (vertical
744  tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS (line  tab, U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line
745  separator, U+2028), and PS (paragraph separator, U+2029). The last two are  separator, U+2028), and PS (paragraph separator, U+2029). For the 8-bit
746  recognized only in UTF-8 mode.  library, the last two are recognized only in UTF-8 mode.
747  .P  .P
748  The newline setting in the options word uses three bits that are treated  The newline setting in the options word uses three bits that are treated
749  as a number, giving eight possibilities. Currently only six are used (default  as a number, giving eight possibilities. Currently only six are used (default
# Line 557  option, the combination may or may not b Line 752  option, the combination may or may not b
752  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
753  other combinations may yield unused numbers and cause an error.  other combinations may yield unused numbers and cause an error.
754  .P  .P
755  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
756  pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character  compiling is when PCRE_EXTENDED is set. CR and LF are white space characters,
757  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
758  line break sequence. In other circumstances, line break sequences are treated  indicates a comment that lasts until after the next line break sequence. In
759  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
760  as whitespace characters and are therefore ignored.  data.
761  .P  .P
762  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
763  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 575  were followed by ?: but named parenthese Line 770  were followed by ?: but named parenthese
770  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
771  in Perl.  in Perl.
772  .sp  .sp
773      NO_START_OPTIMIZE
774    .sp
775    This is an option that acts at matching time; that is, it is really an option
776    for \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. If it is set at compile time,
777    it is remembered with the compiled pattern and assumed at matching time. For
778    details see the discussion of PCRE_NO_START_OPTIMIZE
779    .\" HTML <a href="#execoptions">
780    .\" </a>
781    below.
782    .\"
783    .sp
784      PCRE_UCP
785    .sp
786    This option changes the way PCRE processes \eB, \eb, \eD, \ed, \eS, \es, \eW,
787    \ew, and some of the POSIX character classes. By default, only ASCII characters
788    are recognized, but if PCRE_UCP is set, Unicode properties are used instead to
789    classify characters. More details are given in the section on
790    .\" HTML <a href="pcre.html#genericchartypes">
791    .\" </a>
792    generic character types
793    .\"
794    in the
795    .\" HREF
796    \fBpcrepattern\fP
797    .\"
798    page. If you set PCRE_UCP, matching one of the items it affects takes much
799    longer. The option is available only if PCRE has been compiled with Unicode
800    property support.
801    .sp
802    PCRE_UNGREEDY    PCRE_UNGREEDY
803  .sp  .sp
804  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 584  with Perl. It can also be set by a (?U) Line 808  with Perl. It can also be set by a (?U)
808    PCRE_UTF8    PCRE_UTF8
809  .sp  .sp
810  This option causes PCRE to regard both the pattern and the subject as strings  This option causes PCRE to regard both the pattern and the subject as strings
811  of UTF-8 characters instead of single-byte character strings. However, it is  of UTF-8 characters instead of single-byte strings. However, it is available
812  available only when PCRE is built to include UTF-8 support. If not, the use  only when PCRE is built to include UTF support. If not, the use of this option
813  of this option provokes an error. Details of how this option changes the  provokes an error. Details of how this option changes the behaviour of PCRE are
814  behaviour of PCRE are given in the  given in the
 .\" HTML <a href="pcre.html#utf8support">  
 .\" </a>  
 section on UTF-8 support  
 .\"  
 in the main  
815  .\" HREF  .\" HREF
816  \fBpcre\fP  \fBpcreunicode\fP
817  .\"  .\"
818  page.  page.
819  .sp  .sp
820    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
821  .sp  .sp
822  When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is  When PCRE_UTF8 is set, the validity of the pattern as a UTF-8
823  automatically checked. There is a discussion about the  string is automatically checked. There is a discussion about the
824  .\" HTML <a href="pcre.html#utf8strings">  .\" HTML <a href="pcreunicode.html#utf8strings">
825  .\" </a>  .\" </a>
826  validity of UTF-8 strings  validity of UTF-8 strings
827  .\"  .\"
828  in the main  in the
829  .\" HREF  .\" HREF
830  \fBpcre\fP  \fBpcreunicode\fP
831  .\"  .\"
832  page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_compile()\fP  page. If an invalid UTF-8 sequence is found, \fBpcre_compile()\fP returns an
833  returns an error. If you already know that your pattern is valid, and you want  error. If you already know that your pattern is valid, and you want to skip
834  to skip this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK  this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK option.
835  option. When it is set, the effect of passing an invalid UTF-8 string as a  When it is set, the effect of passing an invalid UTF-8 string as a pattern is
836  pattern is undefined. It may cause your program to crash. Note that this option  undefined. It may cause your program to crash. Note that this option can also
837  can also be passed to \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, to suppress  be passed to \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, to suppress the
838  the UTF-8 validity checking of subject strings.  validity checking of subject strings.
839  .  .
840  .  .
841  .SH "COMPILATION ERROR CODES"  .SH "COMPILATION ERROR CODES"
# Line 624  the UTF-8 validity checking of subject s Line 843  the UTF-8 validity checking of subject s
843  .sp  .sp
844  The following table lists the error codes than may be returned by  The following table lists the error codes than may be returned by
845  \fBpcre_compile2()\fP, along with the error messages that may be returned by  \fBpcre_compile2()\fP, along with the error messages that may be returned by
846  both compiling functions. As PCRE has developed, some error codes have fallen  both compiling functions. Note that error messages are always 8-bit ASCII
847  out of use. To avoid confusion, they have not been re-used.  strings, even in 16-bit mode. As PCRE has developed, some error codes have
848    fallen out of use. To avoid confusion, they have not been re-used.
849  .sp  .sp
850     0  no error     0  no error
851     1  \e at end of pattern     1  \e at end of pattern
# Line 639  out of use. To avoid confusion, they hav Line 859  out of use. To avoid confusion, they hav
859     9  nothing to repeat     9  nothing to repeat
860    10  [this code is not in use]    10  [this code is not in use]
861    11  internal error: unexpected repeat    11  internal error: unexpected repeat
862    12  unrecognized character after (?    12  unrecognized character after (? or (?-
863    13  POSIX named classes are supported only within a class    13  POSIX named classes are supported only within a class
864    14  missing )    14  missing )
865    15  reference to non-existent subpattern    15  reference to non-existent subpattern
# Line 647  out of use. To avoid confusion, they hav Line 867  out of use. To avoid confusion, they hav
867    17  unknown option bit(s) set    17  unknown option bit(s) set
868    18  missing ) after comment    18  missing ) after comment
869    19  [this code is not in use]    19  [this code is not in use]
870    20  regular expression too large    20  regular expression is too large
871    21  failed to get memory    21  failed to get memory
872    22  unmatched parentheses    22  unmatched parentheses
873    23  internal error: code overflow    23  internal error: code overflow
# Line 659  out of use. To avoid confusion, they hav Line 879  out of use. To avoid confusion, they hav
879    29  (?R or (?[+-]digits must be followed by )    29  (?R or (?[+-]digits must be followed by )
880    30  unknown POSIX class name    30  unknown POSIX class name
881    31  POSIX collating elements are not supported    31  POSIX collating elements are not supported
882    32  this version of PCRE is not compiled with PCRE_UTF8 support    32  this version of PCRE is compiled without UTF support
883    33  [this code is not in use]    33  [this code is not in use]
884    34  character value in \ex{...} sequence is too large    34  character value in \ex{...} sequence is too large
885    35  invalid condition (?(0)    35  invalid condition (?(0)
886    36  \eC not allowed in lookbehind assertion    36  \eC not allowed in lookbehind assertion
887    37  PCRE does not support \eL, \el, \eN, \eU, or \eu    37  PCRE does not support \eL, \el, \eN{name}, \eU, or \eu
888    38  number after (?C is > 255    38  number after (?C is > 255
889    39  closing ) for (?C expected    39  closing ) for (?C expected
890    40  recursive call could loop indefinitely    40  recursive call could loop indefinitely
891    41  unrecognized character after (?P    41  unrecognized character after (?P
892    42  syntax error in subpattern name (missing terminator)    42  syntax error in subpattern name (missing terminator)
893    43  two named subpatterns have the same name    43  two named subpatterns have the same name
894    44  invalid UTF-8 string    44  invalid UTF-8 string (specifically UTF-8)
895    45  support for \eP, \ep, and \eX has not been compiled    45  support for \eP, \ep, and \eX has not been compiled
896    46  malformed \eP or \ep sequence    46  malformed \eP or \ep sequence
897    47  unknown property name after \eP or \ep    47  unknown property name after \eP or \ep
898    48  subpattern name is too long (maximum 32 characters)    48  subpattern name is too long (maximum 32 characters)
899    49  too many named subpatterns (maximum 10,000)    49  too many named subpatterns (maximum 10000)
900    50  [this code is not in use]    50  [this code is not in use]
901    51  octal value is greater than \e377 (not in UTF-8 mode)    51  octal value is greater than \e377 in 8-bit non-UTF-8 mode
902    52  internal error: overran compiling workspace    52  internal error: overran compiling workspace
903    53  internal error: previously-checked referenced subpattern not found    53  internal error: previously-checked referenced subpattern
904            not found
905    54  DEFINE group contains more than one branch    54  DEFINE group contains more than one branch
906    55  repeating a DEFINE group is not allowed    55  repeating a DEFINE group is not allowed
907    56  inconsistent NEWLINE options"    56  inconsistent NEWLINE options
908    57  \eg is not followed by a braced name or an optionally braced    57  \eg is not followed by a braced, angle-bracketed, or quoted
909          non-zero number          name/number or by a plain number
910    58  (?+ or (?- or (?(+ or (?(- must be followed by a non-zero number    58  a numbered reference must not be zero
911      59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
912      60  (*VERB) not recognized
913      61  number is too big
914      62  subpattern name expected
915      63  digit expected after (?+
916      64  ] is an invalid data character in JavaScript compatibility mode
917      65  different names for subpatterns of the same number are
918            not allowed
919      66  (*MARK) must have an argument
920      67  this version of PCRE is not compiled with Unicode property
921            support
922      68  \ec must be followed by an ASCII character
923      69  \ek is not followed by a braced, angle-bracketed, or quoted name
924      70  internal error: unknown opcode in find_fixedlength()
925      71  \eN is not supported in a class
926      72  too many forward references
927      73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
928      74  invalid UTF-16 string (specifically UTF-16)
929      75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
930    .sp
931    The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
932    be used if the limits were changed when PCRE was built.
933  .  .
934  .  .
935    .\" HTML <a name="studyingapattern"></a>
936  .SH "STUDYING A PATTERN"  .SH "STUDYING A PATTERN"
937  .rs  .rs
938  .sp  .sp
# Line 705  help speed up matching, \fBpcre_study()\ Line 949  help speed up matching, \fBpcre_study()\
949  results of the study.  results of the study.
950  .P  .P
951  The returned value from \fBpcre_study()\fP can be passed directly to  The returned value from \fBpcre_study()\fP can be passed directly to
952  \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
953  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
954  described  passed; these are described
955  .\" HTML <a href="#extradata">  .\" HTML <a href="#extradata">
956  .\" </a>  .\" </a>
957  below  below
958  .\"  .\"
959  in the section on matching a pattern.  in the section on matching a pattern.
960  .P  .P
961  If studying the pattern does not produce any additional information  If studying the pattern does not produce any useful information,
962  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program
963  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
964  own \fBpcre_extra\fP block.  \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block.
965  .P  .P
966  The second argument of \fBpcre_study()\fP contains option bits. At present, no  The second argument of \fBpcre_study()\fP contains option bits. There are three
967  options are defined, and this argument should always be zero.  options:
968    .sp
969      PCRE_STUDY_JIT_COMPILE
970      PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
971      PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
972    .sp
973    If any of these are set, and the just-in-time compiler is available, the
974    pattern is further compiled into machine code that executes much faster than
975    the \fBpcre_exec()\fP interpretive matching function. If the just-in-time
976    compiler is not available, these options are ignored. All other bits in the
977    \fIoptions\fP argument must be zero.
978    .P
979    JIT compilation is a heavyweight optimization. It can take some time for
980    patterns to be analyzed, and for one-off matches and simple patterns the
981    benefit of faster execution might be offset by a much slower study time.
982    Not all patterns can be optimized by the JIT compiler. For those that cannot be
983    handled, matching automatically falls back to the \fBpcre_exec()\fP
984    interpreter. For more details, see the
985    .\" HREF
986    \fBpcrejit\fP
987    .\"
988    documentation.
989  .P  .P
990  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
991  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 729  static string that is part of the librar Line 994  static string that is part of the librar
994  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
995  sure that it has run successfully.  sure that it has run successfully.
996  .P  .P
997  This is a typical call to \fBpcre_study\fP():  When you are finished with a pattern, you can free the memory used for the
998    study data by calling \fBpcre_free_study()\fP. This function was added to the
999    API for release 8.20. For earlier versions, the memory could be freed with
1000    \fBpcre_free()\fP, just like the pattern itself. This will still work in cases
1001    where JIT optimization is not used, but it is advisable to change to the new
1002    function when convenient.
1003    .P
1004    This is a typical way in which \fBpcre_study\fP() is used (except that in a
1005    real application there should be tests for errors):
1006  .sp  .sp
1007    pcre_extra *pe;    int rc;
1008    pe = pcre_study(    pcre *re;
1009      pcre_extra *sd;
1010      re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
1011      sd = pcre_study(
1012      re,             /* result of pcre_compile() */      re,             /* result of pcre_compile() */
1013      0,              /* no options exist */      0,              /* no options */
1014      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
1015  .sp    rc = pcre_exec(   /* see below for details of pcre_exec() options */
1016  At present, studying a pattern is useful only for non-anchored patterns that do      re, sd, "subject", 7, 0, 0, ovector, 30);
1017  not have a single fixed starting character. A bitmap of possible starting    ...
1018  bytes is created.    pcre_free_study(sd);
1019      pcre_free(re);
1020    .sp
1021    Studying a pattern does two things: first, a lower bound for the length of
1022    subject string that is needed to match the pattern is computed. This does not
1023    mean that there are any strings of that length that match, but it does
1024    guarantee that no shorter strings match. The value is used by
1025    \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP to avoid wasting time by trying to
1026    match strings that are shorter than the lower bound. You can find out the value
1027    in a calling program via the \fBpcre_fullinfo()\fP function.
1028    .P
1029    Studying a pattern is also useful for non-anchored patterns that do not have a
1030    single fixed starting character. A bitmap of possible starting bytes is
1031    created. This speeds up finding a position in the subject at which to start
1032    matching. (In 16-bit mode, the bitmap is used for 16-bit values less than 256.)
1033    .P
1034    These two optimizations apply to both \fBpcre_exec()\fP and
1035    \fBpcre_dfa_exec()\fP, and the information is also used by the JIT compiler.
1036    The optimizations can be disabled by setting the PCRE_NO_START_OPTIMIZE option
1037    when calling \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP, but if this is done,
1038    JIT execution is also disabled. You might want to do this if your pattern
1039    contains callouts or (*MARK) and you want to make use of these facilities in
1040    cases where matching fails. See the discussion of PCRE_NO_START_OPTIMIZE
1041    .\" HTML <a href="#execoptions">
1042    .\" </a>
1043    below.
1044    .\"
1045  .  .
1046  .  .
1047  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
# Line 748  bytes is created. Line 1050  bytes is created.
1050  .sp  .sp
1051  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters,
1052  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
1053  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
1054  less than 128. Higher-valued codes never match escapes such as \ew or \ed, but  with codes less than 128. By default, higher-valued codes never match escapes
1055  can be tested with \ep if PCRE is built with Unicode character property  such as \ew or \ed, but they can be tested with \ep if PCRE is built with
1056  support. The use of locales with Unicode is discouraged. If you are handling  Unicode character property support. Alternatively, the PCRE_UCP option can be
1057  characters with codes greater than 128, you should either use UTF-8 and  set at compile time; this causes \ew and friends to use Unicode property
1058  Unicode, or use locales, but not try to mix the two.  support instead of built-in tables. The use of locales with Unicode is
1059    discouraged. If you are handling characters with codes greater than 128, you
1060    should either use UTF-8 and Unicode, or use locales, but not try to mix the
1061    two.
1062  .P  .P
1063  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
1064  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 798  one in which it was compiled. Passing ta Line 1103  one in which it was compiled. Passing ta
1103  below in the section on matching a pattern.  below in the section on matching a pattern.
1104  .  .
1105  .  .
1106    .\" HTML <a name="infoaboutpattern"></a>
1107  .SH "INFORMATION ABOUT A PATTERN"  .SH "INFORMATION ABOUT A PATTERN"
1108  .rs  .rs
1109  .sp  .sp
# Line 806  below in the section on matching a patte Line 1112  below in the section on matching a patte
1112  .B int \fIwhat\fP, void *\fIwhere\fP);  .B int \fIwhat\fP, void *\fIwhere\fP);
1113  .PP  .PP
1114  The \fBpcre_fullinfo()\fP function returns information about a compiled  The \fBpcre_fullinfo()\fP function returns information about a compiled
1115  pattern. It replaces the obsolete \fBpcre_info()\fP function, which is  pattern. It replaces the \fBpcre_info()\fP function, which was removed from the
1116  nevertheless retained for backwards compability (and is documented below).  library at version 8.30, after more than 10 years of obsolescence.
1117  .P  .P
1118  The first argument for \fBpcre_fullinfo()\fP is a pointer to the compiled  The first argument for \fBpcre_fullinfo()\fP is a pointer to the compiled
1119  pattern. The second argument is the result of \fBpcre_study()\fP, or NULL if  pattern. The second argument is the result of \fBpcre_study()\fP, or NULL if
# Line 816  information is required, and the fourth Line 1122  information is required, and the fourth
1122  to receive the data. The yield of the function is zero for success, or one of  to receive the data. The yield of the function is zero for success, or one of
1123  the following negative numbers:  the following negative numbers:
1124  .sp  .sp
1125    PCRE_ERROR_NULL       the argument \fIcode\fP was NULL    PCRE_ERROR_NULL           the argument \fIcode\fP was NULL
1126                          the argument \fIwhere\fP was NULL                              the argument \fIwhere\fP was NULL
1127    PCRE_ERROR_BADMAGIC   the "magic number" was not found    PCRE_ERROR_BADMAGIC       the "magic number" was not found
1128    PCRE_ERROR_BADOPTION  the value of \fIwhat\fP was invalid    PCRE_ERROR_BADENDIANNESS  the pattern was compiled with different
1129                                endianness
1130      PCRE_ERROR_BADOPTION      the value of \fIwhat\fP was invalid
1131  .sp  .sp
1132  The "magic number" is placed at the start of each compiled pattern as an simple  The "magic number" is placed at the start of each compiled pattern as an simple
1133  check against passing an arbitrary memory pointer. Here is a typical call of  check against passing an arbitrary memory pointer. The endianness error can
1134  \fBpcre_fullinfo()\fP, to obtain the length of the compiled pattern:  occur if a compiled pattern is saved and reloaded on a different host. Here is
1135    a typical call of \fBpcre_fullinfo()\fP, to obtain the length of the compiled
1136    pattern:
1137  .sp  .sp
1138    int rc;    int rc;
1139    size_t length;    size_t length;
1140    rc = pcre_fullinfo(    rc = pcre_fullinfo(
1141      re,               /* result of pcre_compile() */      re,               /* result of pcre_compile() */
1142      pe,               /* result of pcre_study(), or NULL */      sd,               /* result of pcre_study(), or NULL */
1143      PCRE_INFO_SIZE,   /* what is required */      PCRE_INFO_SIZE,   /* what is required */
1144      &length);         /* where to put the data */      &length);         /* where to put the data */
1145  .sp  .sp
# Line 857  a NULL table pointer. Line 1167  a NULL table pointer.
1167  .sp  .sp
1168    PCRE_INFO_FIRSTBYTE    PCRE_INFO_FIRSTBYTE
1169  .sp  .sp
1170  Return information about the first byte of any matched string, for a  Return information about the first data unit of any matched string, for a
1171  non-anchored pattern. The fourth argument should point to an \fBint\fP  non-anchored pattern. (The name of this option refers to the 8-bit library,
1172  variable. (This option used to be called PCRE_INFO_FIRSTCHAR; the old name is  where data units are bytes.) The fourth argument should point to an \fBint\fP
1173  still recognized for backwards compatibility.)  variable.
1174    .P
1175    If there is a fixed first value, for example, the letter "c" from a pattern
1176    such as (cat|cow|coyote), its value is returned. In the 8-bit library, the
1177    value is always less than 256; in the 16-bit library the value can be up to
1178    0xffff.
1179  .P  .P
1180  If there is a fixed first byte, for example, from a pattern such as  If there is no fixed first value, and if either
 (cat|cow|coyote), its value is returned. Otherwise, if either  
1181  .sp  .sp
1182  (a) the pattern was compiled with the PCRE_MULTILINE option, and every branch  (a) the pattern was compiled with the PCRE_MULTILINE option, and every branch
1183  starts with "^", or  starts with "^", or
# Line 878  returned. For anchored patterns, -2 is r Line 1192  returned. For anchored patterns, -2 is r
1192    PCRE_INFO_FIRSTTABLE    PCRE_INFO_FIRSTTABLE
1193  .sp  .sp
1194  If the pattern was studied, and this resulted in the construction of a 256-bit  If the pattern was studied, and this resulted in the construction of a 256-bit
1195  table indicating a fixed set of bytes for the first byte in any matching  table indicating a fixed set of values for the first data unit in any matching
1196  string, a pointer to the table is returned. Otherwise NULL is returned. The  string, a pointer to the table is returned. Otherwise NULL is returned. The
1197  fourth argument should point to an \fBunsigned char *\fP variable.  fourth argument should point to an \fBunsigned char *\fP variable.
1198  .sp  .sp
1199      PCRE_INFO_HASCRORLF
1200    .sp
1201    Return 1 if the pattern contains any explicit matches for CR or LF characters,
1202    otherwise 0. The fourth argument should point to an \fBint\fP variable. An
1203    explicit match is either a literal CR or LF character, or \er or \en.
1204    .sp
1205    PCRE_INFO_JCHANGED    PCRE_INFO_JCHANGED
1206  .sp  .sp
1207  Return 1 if the (?J) option setting is used in the pattern, otherwise 0. The  Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise
1208  fourth argument should point to an \fBint\fP variable. The (?J) internal option  0. The fourth argument should point to an \fBint\fP variable. (?J) and
1209  setting changes the local PCRE_DUPNAMES option.  (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
1210    .sp
1211      PCRE_INFO_JIT
1212    .sp
1213    Return 1 if the pattern was studied with one of the JIT options, and
1214    just-in-time compiling was successful. The fourth argument should point to an
1215    \fBint\fP variable. A return value of 0 means that JIT support is not available
1216    in this version of PCRE, or that the pattern was not studied with a JIT option,
1217    or that the JIT compiler could not handle this particular pattern. See the
1218    .\" HREF
1219    \fBpcrejit\fP
1220    .\"
1221    documentation for details of what can and cannot be handled.
1222    .sp
1223      PCRE_INFO_JITSIZE
1224    .sp
1225    If the pattern was successfully studied with a JIT option, return the size of
1226    the JIT compiled code, otherwise return zero. The fourth argument should point
1227    to a \fBsize_t\fP variable.
1228  .sp  .sp
1229    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
1230  .sp  .sp
1231  Return the value of the rightmost literal byte that must exist in any matched  Return the value of the rightmost literal data unit that must exist in any
1232  string, other than at its start, if such a byte has been recorded. The fourth  matched string, other than at its start, if such a value has been recorded. The
1233  argument should point to an \fBint\fP variable. If there is no such byte, -1 is  fourth argument should point to an \fBint\fP variable. If there is no such
1234  returned. For anchored patterns, a last literal byte is recorded only if it  value, -1 is returned. For anchored patterns, a last literal value is recorded
1235  follows something of variable length. For example, for the pattern  only if it follows something of variable length. For example, for the pattern
1236  /^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
1237  is -1.  is -1.
1238  .sp  .sp
1239      PCRE_INFO_MAXLOOKBEHIND
1240    .sp
1241    Return the number of characters (NB not bytes) in the longest lookbehind
1242    assertion in the pattern. Note that the simple assertions \eb and \eB require a
1243    one-character lookbehind. This information is useful when doing multi-segment
1244    matching using the partial matching facilities.
1245    .sp
1246      PCRE_INFO_MINLENGTH
1247    .sp
1248    If the pattern was studied and a minimum length for matching subject strings
1249    was computed, its value is returned. Otherwise the returned value is -1. The
1250    value is a number of characters, which in UTF-8 mode may be different from the
1251    number of bytes. The fourth argument should point to an \fBint\fP variable. A
1252    non-negative value is a lower bound to the length of any matching string. There
1253    may not be any strings of that length that do actually match, but every string
1254    that does match is at least that long.
1255    .sp
1256    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
1257    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
1258    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
# Line 916  The map consists of a number of fixed-si Line 1271  The map consists of a number of fixed-si
1271  the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size of each  the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size of each
1272  entry; both of these return an \fBint\fP value. The entry size depends on the  entry; both of these return an \fBint\fP value. The entry size depends on the
1273  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
1274  entry of the table (a pointer to \fBchar\fP). The first two bytes of each entry  entry of the table. This is a pointer to \fBchar\fP in the 8-bit library, where
1275  are the number of the capturing parenthesis, most significant byte first. The  the first two bytes of each entry are the number of the capturing parenthesis,
1276  rest of the entry is the corresponding name, zero terminated. The names are in  most significant byte first. In the 16-bit library, the pointer points to
1277  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of  16-bit data units, the first of which contains the parenthesis number. The rest
1278  their parentheses numbers. For example, consider the following pattern (assume  of the entry is the corresponding name, zero terminated.
1279  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  .P
1280    The names are in alphabetical order. Duplicate names may appear if (?| is used
1281    to create multiple groups with the same number, as described in the
1282    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1283    .\" </a>
1284    section on duplicate subpattern numbers
1285    .\"
1286    in the
1287    .\" HREF
1288    \fBpcrepattern\fP
1289    .\"
1290    page. Duplicate names for subpatterns with different numbers are permitted only
1291    if PCRE_DUPNAMES is set. In all cases of duplicate names, they appear in the
1292    table in the order in which they were found in the pattern. In the absence of
1293    (?| this is the order of increasing number; when (?| is used this is not
1294    necessarily the case because later subpatterns may have lower numbers.
1295    .P
1296    As a simple example of the name/number table, consider the following pattern
1297    after compilation by the 8-bit library (assume PCRE_EXTENDED is set, so white
1298    space - including newlines - is ignored):
1299  .sp  .sp
1300  .\" JOIN  .\" JOIN
1301    (?<date> (?<year>(\ed\ed)?\ed\ed) -    (?<date> (?<year>(\ed\ed)?\ed\ed) -
# Line 942  different for each compiled pattern. Line 1316  different for each compiled pattern.
1316  .sp  .sp
1317    PCRE_INFO_OKPARTIAL    PCRE_INFO_OKPARTIAL
1318  .sp  .sp
1319  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
1320  fourth argument should point to an \fBint\fP variable. The  \fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
1321    \fBint\fP variable. From release 8.00, this always returns 1, because the
1322    restrictions that previously applied to partial matching have been lifted. The
1323  .\" HREF  .\" HREF
1324  \fBpcrepartial\fP  \fBpcrepartial\fP
1325  .\"  .\"
1326  documentation lists the restrictions that apply to patterns when partial  documentation gives details of partial matching.
 matching is used.  
1327  .sp  .sp
1328    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1329  .sp  .sp
# Line 975  For such patterns, the PCRE_ANCHORED bit Line 1350  For such patterns, the PCRE_ANCHORED bit
1350  .sp  .sp
1351    PCRE_INFO_SIZE    PCRE_INFO_SIZE
1352  .sp  .sp
1353  Return the size of the compiled pattern, that is, the value that was passed as  Return the size of the compiled pattern in bytes (for both libraries). The
1354  the argument to \fBpcre_malloc()\fP when PCRE was getting memory in which to  fourth argument should point to a \fBsize_t\fP variable. This value does not
1355  place the compiled data. The fourth argument should point to a \fBsize_t\fP  include the size of the \fBpcre\fP structure that is returned by
1356  variable.  \fBpcre_compile()\fP. The value that is passed as the argument to
1357    \fBpcre_malloc()\fP when \fBpcre_compile()\fP is getting memory in which to
1358    place the compiled data is the value returned by this option plus the size of
1359    the \fBpcre\fP structure. Studying a compiled pattern, with or without JIT,
1360    does not alter the value returned by this option.
1361  .sp  .sp
1362    PCRE_INFO_STUDYSIZE    PCRE_INFO_STUDYSIZE
1363  .sp  .sp
1364  Return the size of the data block pointed to by the \fIstudy_data\fP field in  Return the size in bytes of the data block pointed to by the \fIstudy_data\fP
1365  a \fBpcre_extra\fP block. That is, it is the value that was passed to  field in a \fBpcre_extra\fP block. If \fBpcre_extra\fP is NULL, or there is no
1366  \fBpcre_malloc()\fP when PCRE was getting memory into which to place the data  study data, zero is returned. The fourth argument should point to a
1367  created by \fBpcre_study()\fP. The fourth argument should point to a  \fBsize_t\fP variable. The \fIstudy_data\fP field is set by \fBpcre_study()\fP
1368  \fBsize_t\fP variable.  to record information that will speed up matching (see the section entitled
1369  .  .\" HTML <a href="#studyingapattern">
1370  .  .\" </a>
1371  .SH "OBSOLETE INFO FUNCTION"  "Studying a pattern"
1372  .rs  .\"
1373  .sp  above). The format of the \fIstudy_data\fP block is private, but its length
1374  .B int pcre_info(const pcre *\fIcode\fP, int *\fIoptptr\fP, int  is made available via this option so that it can be saved and restored (see the
1375  .B *\fIfirstcharptr\fP);  .\" HREF
1376  .PP  \fBpcreprecompile\fP
1377  The \fBpcre_info()\fP function is now obsolete because its interface is too  .\"
1378  restrictive to return all the available data about a compiled pattern. New  documentation for details).
 programs should use \fBpcre_fullinfo()\fP instead. The yield of  
 \fBpcre_info()\fP is the number of capturing subpatterns, or one of the  
 following negative numbers:  
 .sp  
   PCRE_ERROR_NULL       the argument \fIcode\fP was NULL  
   PCRE_ERROR_BADMAGIC   the "magic number" was not found  
 .sp  
 If the \fIoptptr\fP argument is not NULL, a copy of the options with which the  
 pattern was compiled is placed in the integer it points to (see  
 PCRE_INFO_OPTIONS above).  
 .P  
 If the pattern is not anchored and the \fIfirstcharptr\fP argument is not NULL,  
 it is used to pass back information about the first character of any matched  
 string (see PCRE_INFO_FIRSTBYTE above).  
1379  .  .
1380  .  .
1381  .SH "REFERENCE COUNTS"  .SH "REFERENCE COUNTS"
# Line 1047  is different. (This seems a highly unlik Line 1412  is different. (This seems a highly unlik
1412  .P  .P
1413  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
1414  compiled pattern, which is passed in the \fIcode\fP argument. If the  compiled pattern, which is passed in the \fIcode\fP argument. If the
1415  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
1416  \fIextra\fP argument. This function is the main matching facility of the  \fIextra\fP argument. You can call \fBpcre_exec()\fP with the same \fIcode\fP
1417  library, and it operates in a Perl-like manner. For specialist use there is  and \fIextra\fP arguments as many times as you like, in order to match
1418  also an alternative matching function, which is described  different subject strings with the same pattern.
1419    .P
1420    This function is the main matching facility of the library, and it operates in
1421    a Perl-like manner. For specialist use there is also an alternative matching
1422    function, which is described
1423  .\" HTML <a href="#dfamatch">  .\" HTML <a href="#dfamatch">
1424  .\" </a>  .\" </a>
1425  below  below
# Line 1081  Here is an example of a simple call to \ Line 1450  Here is an example of a simple call to \
1450      ovector,        /* vector of integers for substring information */      ovector,        /* vector of integers for substring information */
1451      30);            /* number of elements (NOT size in bytes) */      30);            /* number of elements (NOT size in bytes) */
1452  .  .
1453    .
1454  .\" HTML <a name="extradata"></a>  .\" HTML <a name="extradata"></a>
1455  .SS "Extra data for \fBpcre_exec()\fR"  .SS "Extra data for \fBpcre_exec()\fR"
1456  .rs  .rs
# Line 1093  fields (not necessarily in this order): Line 1463  fields (not necessarily in this order):
1463  .sp  .sp
1464    unsigned long int \fIflags\fP;    unsigned long int \fIflags\fP;
1465    void *\fIstudy_data\fP;    void *\fIstudy_data\fP;
1466      void *\fIexecutable_jit\fP;
1467    unsigned long int \fImatch_limit\fP;    unsigned long int \fImatch_limit\fP;
1468    unsigned long int \fImatch_limit_recursion\fP;    unsigned long int \fImatch_limit_recursion\fP;
1469    void *\fIcallout_data\fP;    void *\fIcallout_data\fP;
1470    const unsigned char *\fItables\fP;    const unsigned char *\fItables\fP;
1471      unsigned char **\fImark\fP;
1472  .sp  .sp
1473  The \fIflags\fP field is a bitmap that specifies which of the other fields  In the 16-bit version of this structure, the \fImark\fP field has type
1474  are set. The flag bits are:  "PCRE_UCHAR16 **".
1475    .P
1476    The \fIflags\fP field is used to specify which of the other fields are set. The
1477    flag bits are:
1478  .sp  .sp
1479    PCRE_EXTRA_STUDY_DATA    PCRE_EXTRA_CALLOUT_DATA
1480      PCRE_EXTRA_EXECUTABLE_JIT
1481      PCRE_EXTRA_MARK
1482    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1483    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1484    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_STUDY_DATA
1485    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1486  .sp  .sp
1487  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
1488  \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
1489  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
1490  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 other
1491    fields and their corresponding flag bits.
1492  .P  .P
1493  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
1494  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,
1495  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
1496  classic example is the use of nested unlimited repeats.  classic example is a pattern that uses nested unlimited repeats.
1497  .P  .P
1498  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly  Internally, \fBpcre_exec()\fP uses a function called \fBmatch()\fP, which it
1499  (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
1500  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
1501  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
1502  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
1503  string.  in the subject string.
1504    .P
1505    When \fBpcre_exec()\fP is called with a pattern that was successfully studied
1506    with a JIT option, the way that the matching is executed is entirely different.
1507    However, there is still the possibility of runaway matching that goes on for a
1508    very long time, and so the \fImatch_limit\fP value is also used in this case
1509    (but in a different way) to limit how long the matching can continue.
1510  .P  .P
1511  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
1512  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 1137  limits the depth of recursion. The recur Line 1521  limits the depth of recursion. The recur
1521  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.
1522  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.
1523  .P  .P
1524  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
1525  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
1526  amount of heap memory that can be used.  stack, the amount of heap memory that can be used. This limit is not relevant,
1527    and is ignored, when matching is done using JIT compiled code.
1528  .P  .P
1529  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
1530  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 1148  with a \fBpcre_extra\fP block in which \ Line 1533  with a \fBpcre_extra\fP block in which \
1533  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
1534  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1535  .P  .P
1536  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,
1537  which is described in the  and is described in the
1538  .\" HREF  .\" HREF
1539  \fBpcrecallout\fP  \fBpcrecallout\fP
1540  .\"  .\"
# Line 1168  called. See the Line 1553  called. See the
1553  \fBpcreprecompile\fP  \fBpcreprecompile\fP
1554  .\"  .\"
1555  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1556    .P
1557    If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1558    be set to point to a suitable variable. If the pattern contains any
1559    backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1560    a name to pass back, a pointer to the name string (zero terminated) is placed
1561    in the variable pointed to by the \fImark\fP field. The names are within the
1562    compiled pattern; if you wish to retain such a name you must copy it before
1563    freeing the memory of a compiled pattern. If there is no name to pass back, the
1564    variable pointed to by the \fImark\fP field is set to NULL. For details of the
1565    backtracking control verbs, see the section entitled
1566    .\" HTML <a href="pcrepattern#backtrackcontrol">
1567    .\" </a>
1568    "Backtracking control"
1569    .\"
1570    in the
1571    .\" HREF
1572    \fBpcrepattern\fP
1573    .\"
1574    documentation.
1575    .
1576  .  .
1577    .\" HTML <a name="execoptions"></a>
1578  .SS "Option bits for \fBpcre_exec()\fP"  .SS "Option bits for \fBpcre_exec()\fP"
1579  .rs  .rs
1580  .sp  .sp
1581  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
1582  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,
1583  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1584    PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD, and
1585    PCRE_PARTIAL_SOFT.
1586    .P
1587    If the pattern was successfully studied with one of the just-in-time (JIT)
1588    compile options, the only supported options for JIT execution are
1589    PCRE_NO_UTF8_CHECK, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY,
1590    PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an
1591    unsupported option is used, JIT execution is disabled and the normal
1592    interpretive code in \fBpcre_exec()\fP is run.
1593  .sp  .sp
1594    PCRE_ANCHORED    PCRE_ANCHORED
1595  .sp  .sp
# Line 1183  matching position. If a pattern was comp Line 1598  matching position. If a pattern was comp
1598  to be anchored by virtue of its contents, it cannot be made unachored at  to be anchored by virtue of its contents, it cannot be made unachored at
1599  matching time.  matching time.
1600  .sp  .sp
1601      PCRE_BSR_ANYCRLF
1602      PCRE_BSR_UNICODE
1603    .sp
1604    These options (which are mutually exclusive) control what the \eR escape
1605    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
1606    match any Unicode newline sequence. These options override the choice that was
1607    made or defaulted when the pattern was compiled.
1608    .sp
1609    PCRE_NEWLINE_CR    PCRE_NEWLINE_CR
1610    PCRE_NEWLINE_LF    PCRE_NEWLINE_LF
1611    PCRE_NEWLINE_CRLF    PCRE_NEWLINE_CRLF
# Line 1194  the pattern was compiled. For details, s Line 1617  the pattern was compiled. For details, s
1617  \fBpcre_compile()\fP above. During matching, the newline choice affects the  \fBpcre_compile()\fP above. During matching, the newline choice affects the
1618  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1619  the way the match position is advanced after a match failure for an unanchored  the way the match position is advanced after a match failure for an unanchored
1620  pattern. When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is  pattern.
1621  set, and a match attempt fails when the current position is at a CRLF sequence,  .P
1622  the match position is advanced by two characters instead of one, in other  When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a
1623  words, to after the CRLF.  match attempt for an unanchored pattern fails when the current position is at a
1624    CRLF sequence, and the pattern contains no explicit matches for CR or LF
1625    characters, the match position is advanced by two characters instead of one, in
1626    other words, to after the CRLF.
1627    .P
1628    The above rule is a compromise that makes the most common cases work as
1629    expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
1630    set), it does not match the string "\er\enA" because, after failing at the
1631    start, it skips both the CR and the LF before retrying. However, the pattern
1632    [\er\en]A does match that string, because it contains an explicit CR or LF
1633    reference, and so advances only by one character after the first failure.
1634    .P
1635    An explicit match for CR of LF is either a literal appearance of one of those
1636    characters, or one of the \er or \en escape sequences. Implicit matches such as
1637    [^X] do not count, nor does \es (which includes CR and LF in the characters
1638    that it matches).
1639    .P
1640    Notwithstanding the above, anomalous effects may still occur when CRLF is a
1641    valid newline sequence and explicit \er or \en escapes appear in the pattern.
1642  .sp  .sp
1643    PCRE_NOTBOL    PCRE_NOTBOL
1644  .sp  .sp
# Line 1223  match the empty string, the entire match Line 1664  match the empty string, the entire match
1664  .sp  .sp
1665    a?b?    a?b?
1666  .sp  .sp
1667  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
1668  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
1669  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".
1670  .P  .sp
1671  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case    PCRE_NOTEMPTY_ATSTART
1672  of a pattern match of the empty string within its \fBsplit()\fP function, and  .sp
1673  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
1674  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
1675  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the  can occur only if the pattern contains \eK.
1676  starting offset (see below) and trying an ordinary match again. There is some  .P
1677  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
1678    does make a special case of a pattern match of the empty string within its
1679    \fBsplit()\fP function, and when using the /g modifier. It is possible to
1680    emulate Perl's behaviour after matching a null string by first trying the match
1681    again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
1682    if that fails, by advancing the starting offset (see below) and trying an
1683    ordinary match again. There is some code that demonstrates how to do this in
1684    the
1685    .\" HREF
1686    \fBpcredemo\fP
1687    .\"
1688    sample program. In the most general case, you have to check to see if the
1689    newline convention recognizes CRLF as a newline, and if so, and the current
1690    character is CR followed by LF, advance the starting offset by two characters
1691    instead of one.
1692    .sp
1693      PCRE_NO_START_OPTIMIZE
1694    .sp
1695    There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1696    a match, in order to speed up the process. For example, if it is known that an
1697    unanchored match must start with a specific character, it searches the subject
1698    for that character, and fails immediately if it cannot find it, without
1699    actually running the main matching function. This means that a special item
1700    such as (*COMMIT) at the start of a pattern is not considered until after a
1701    suitable starting point for the match has been found. When callouts or (*MARK)
1702    items are in use, these "start-up" optimizations can cause them to be skipped
1703    if the pattern is never actually used. The start-up optimizations are in effect
1704    a pre-scan of the subject that takes place before the pattern is run.
1705    .P
1706    The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
1707    causing performance to suffer, but ensuring that in cases where the result is
1708    "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
1709    are considered at every possible starting position in the subject string. If
1710    PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
1711    time. The use of PCRE_NO_START_OPTIMIZE disables JIT execution; when it is set,
1712    matching is always done using interpretively.
1713    .P
1714    Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
1715    Consider the pattern
1716    .sp
1717      (*COMMIT)ABC
1718    .sp
1719    When this is compiled, PCRE records the fact that a match must start with the
1720    character "A". Suppose the subject string is "DEFABC". The start-up
1721    optimization scans along the subject, finds "A" and runs the first match
1722    attempt from there. The (*COMMIT) item means that the pattern must match the
1723    current starting position, which in this case, it does. However, if the same
1724    match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
1725    subject string does not happen. The first match attempt is run starting from
1726    "D" and when this fails, (*COMMIT) prevents any further matches being tried, so
1727    the overall result is "no match". If the pattern is studied, more start-up
1728    optimizations may be used. For example, a minimum length for the subject may be
1729    recorded. Consider the pattern
1730    .sp
1731      (*MARK:A)(X|Y)
1732    .sp
1733    The minimum length for a match is one character. If the subject is "ABC", there
1734    will be attempts to match "ABC", "BC", "C", and then finally an empty string.
1735    If the pattern is studied, the final attempt does not take place, because PCRE
1736    knows that the subject is too short, and so the (*MARK) is never encountered.
1737    In this case, studying the pattern does not affect the overall match result,
1738    which is still "no match", but it does affect the auxiliary information that is
1739    returned.
1740  .sp  .sp
1741    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1742  .sp  .sp
1743  When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8  When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8
1744  string is automatically checked when \fBpcre_exec()\fP is subsequently called.  string is automatically checked when \fBpcre_exec()\fP is subsequently called.
1745  The value of \fIstartoffset\fP is also checked to ensure that it points to the  The entire string is checked before any other processing takes place. The value
1746  start of a UTF-8 character. There is a discussion about the validity of UTF-8  of \fIstartoffset\fP is also checked to ensure that it points to the start of a
1747  strings in the  UTF-8 character. There is a discussion about the
1748  .\" HTML <a href="pcre.html#utf8strings">  .\" HTML <a href="pcreunicode.html#utf8strings">
1749  .\" </a>  .\" </a>
1750  section on UTF-8 support  validity of UTF-8 strings
1751  .\"  .\"
1752  in the main  in the
1753  .\" HREF  .\" HREF
1754  \fBpcre\fP  \fBpcreunicode\fP
1755    .\"
1756    page. If an invalid sequence of bytes is found, \fBpcre_exec()\fP returns the
1757    error PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a
1758    truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In both
1759    cases, information about the precise nature of the error may also be returned
1760    (see the descriptions of these errors in the section entitled \fIError return
1761    values from\fP \fBpcre_exec()\fP
1762    .\" HTML <a href="#errorlist">
1763    .\" </a>
1764    below).
1765  .\"  .\"
1766  page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns  If \fIstartoffset\fP contains a value that does not point to the start of a
1767  the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP contains an invalid value,  UTF-8 character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
1768  PCRE_ERROR_BADUTF8_OFFSET is returned.  returned.
1769  .P  .P
1770  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
1771  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
1772  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
1773  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
1774  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
1775  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 character (or the end
1776  PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid UTF-8 string as a  of the subject). When PCRE_NO_UTF8_CHECK is set, the effect of passing an
1777  subject, or a value of \fIstartoffset\fP that does not point to the start of a  invalid string as a subject or an invalid value of \fIstartoffset\fP is
1778  UTF-8 character, is undefined. Your program may crash.  undefined. Your program may crash.
1779  .sp  .sp
1780    PCRE_PARTIAL    PCRE_PARTIAL_HARD
1781  .sp    PCRE_PARTIAL_SOFT
1782  This option turns on the partial matching feature. If the subject string fails  .sp
1783  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
1784  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
1785  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
1786  characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of  not enough subject characters to complete the match. If this happens when
1787  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
1788  may appear in the pattern. These are discussed in the  testing any remaining alternatives. Only if no complete match can be found is
1789    PCRE_ERROR_PARTIAL returned instead of PCRE_ERROR_NOMATCH. In other words,
1790    PCRE_PARTIAL_SOFT says that the caller is prepared to handle a partial match,
1791    but only if no complete match can be found.
1792    .P
1793    If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
1794    partial match is found, \fBpcre_exec()\fP immediately returns
1795    PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
1796    when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
1797    important that an alternative complete match.
1798    .P
1799    In both cases, the portion of the string that was inspected when the partial
1800    match was found is set as the first matching string. There is a more detailed
1801    discussion of partial and multi-segment matching, with examples, in the
1802  .\" HREF  .\" HREF
1803  \fBpcrepartial\fP  \fBpcrepartial\fP
1804  .\"  .\"
1805  documentation.  documentation.
1806  .  .
1807    .
1808  .SS "The string to be matched by \fBpcre_exec()\fP"  .SS "The string to be matched by \fBpcre_exec()\fP"
1809  .rs  .rs
1810  .sp  .sp
1811  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
1812  \fIsubject\fP, a length in \fIlength\fP, and a starting byte offset in  \fIsubject\fP, a length in bytes in \fIlength\fP, and a starting byte offset
1813  \fIstartoffset\fP. In UTF-8 mode, the byte offset must point to the start of a  in \fIstartoffset\fP. If this is negative or greater than the length of the
1814  UTF-8 character. Unlike the pattern string, the subject may contain binary zero  subject, \fBpcre_exec()\fP returns PCRE_ERROR_BADOFFSET. When the starting
1815  bytes. When the starting offset is zero, the search for a match starts at the  offset is zero, the search for a match starts at the beginning of the subject,
1816  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
1817    point to the start of a UTF-8 character (or the end of the subject). Unlike the
1818    pattern string, the subject may contain binary zero bytes.
1819  .P  .P
1820  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
1821  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 1306  start of the subject, which is deemed to Line 1835  start of the subject, which is deemed to
1835  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
1836  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.
1837  .P  .P
1838    Finding all the matches in a subject is tricky when the pattern can match an
1839    empty string. It is possible to emulate Perl's /g behaviour by first trying the
1840    match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
1841    PCRE_ANCHORED options, and then if that fails, advancing the starting offset
1842    and trying an ordinary match again. There is some code that demonstrates how to
1843    do this in the
1844    .\" HREF
1845    \fBpcredemo\fP
1846    .\"
1847    sample program. In the most general case, you have to check to see if the
1848    newline convention recognizes CRLF as a newline, and if so, and the current
1849    character is CR followed by LF, advance the starting offset by two characters
1850    instead of one.
1851    .P
1852  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
1853  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
1854  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.
1855  .  .
1856    .
1857  .SS "How \fBpcre_exec()\fP returns captured substrings"  .SS "How \fBpcre_exec()\fP returns captured substrings"
1858  .rs  .rs
1859  .sp  .sp
# Line 1320  pattern. Following the usage in Jeffrey Line 1864  pattern. Following the usage in Jeffrey
1864  a fragment of a pattern that picks out a substring. PCRE supports several other  a fragment of a pattern that picks out a substring. PCRE supports several other
1865  kinds of parenthesized subpattern that do not cause substrings to be captured.  kinds of parenthesized subpattern that do not cause substrings to be captured.
1866  .P  .P
1867  Captured substrings are returned to the caller via a vector of integer offsets  Captured substrings are returned to the caller via a vector of integers whose
1868  whose address is passed in \fIovector\fP. The number of elements in the vector  address is passed in \fIovector\fP. The number of elements in the vector is
1869  is passed in \fIovecsize\fP, which must be a non-negative number. \fBNote\fP:  passed in \fIovecsize\fP, which must be a non-negative number. \fBNote\fP: this
1870  this argument is NOT the size of \fIovector\fP in bytes.  argument is NOT the size of \fIovector\fP in bytes.
1871  .P  .P
1872  The first two-thirds of the vector is used to pass back captured substrings,  The first two-thirds of the vector is used to pass back captured substrings,
1873  each substring using a pair of integers. The remaining third of the vector is  each substring using a pair of integers. The remaining third of the vector is
1874  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
1875  and is not available for passing back information. The length passed in  and is not available for passing back information. The number passed in
1876  \fIovecsize\fP should always be a multiple of three. If it is not, it is  \fIovecsize\fP should always be a multiple of three. If it is not, it is
1877  rounded down.  rounded down.
1878  .P  .P
1879  When a match is successful, information about captured substrings is returned  When a match is successful, information about captured substrings is returned
1880  in pairs of integers, starting at the beginning of \fIovector\fP, and  in pairs of integers, starting at the beginning of \fIovector\fP, and
1881  continuing up to two-thirds of its length at the most. The first element of a  continuing up to two-thirds of its length at the most. The first element of
1882  pair is set to the offset of the first character in a substring, and the second  each pair is set to the byte offset of the first character in a substring, and
1883  is set to the offset of the first character after the end of a substring. The  the second is set to the byte offset of the first character after the end of a
1884  first pair, \fIovector[0]\fP and \fIovector[1]\fP, identify the portion of the  substring. \fBNote\fP: these values are always byte offsets, even in UTF-8
1885  subject string matched by the entire pattern. The next pair is used for the  mode. They are not character counts.
1886  first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fP  .P
1887  is one more than the highest numbered pair that has been set. For example, if  The first pair of integers, \fIovector[0]\fP and \fIovector[1]\fP, identify the
1888  two substrings have been captured, the returned value is 3. If there are no  portion of the subject string matched by the entire pattern. The next pair is
1889  capturing subpatterns, the return value from a successful match is 1,  used for the first capturing subpattern, and so on. The value returned by
1890  indicating that just the first pair of offsets has been set.  \fBpcre_exec()\fP is one more than the highest numbered pair that has been set.
1891    For example, if two substrings have been captured, the returned value is 3. If
1892    there are no capturing subpatterns, the return value from a successful match is
1893    1, indicating that just the first pair of offsets has been set.
1894  .P  .P
1895  If a capturing subpattern is matched repeatedly, it is the last portion of the  If a capturing subpattern is matched repeatedly, it is the last portion of the
1896  string that it matched that is returned.  string that it matched that is returned.
1897  .P  .P
1898  If the vector is too small to hold all the captured substring offsets, it is  If the vector is too small to hold all the captured substring offsets, it is
1899  used as far as possible (up to two-thirds of its length), and the function  used as far as possible (up to two-thirds of its length), and the function
1900  returns a value of zero. In particular, if the substring offsets are not of  returns a value of zero. If neither the actual string matched nor any captured
1901  interest, \fBpcre_exec()\fP may be called with \fIovector\fP passed as NULL and  substrings are of interest, \fBpcre_exec()\fP may be called with \fIovector\fP
1902  \fIovecsize\fP as zero. However, if the pattern contains back references and  passed as NULL and \fIovecsize\fP as zero. However, if the pattern contains
1903  the \fIovector\fP is not big enough to remember the related substrings, PCRE  back references and the \fIovector\fP is not big enough to remember the related
1904  has to get additional memory for use during matching. Thus it is usually  substrings, PCRE has to get additional memory for use during matching. Thus it
1905  advisable to supply an \fIovector\fP.  is usually advisable to supply an \fIovector\fP of reasonable size.
1906    .P
1907    There are some cases where zero is returned (indicating vector overflow) when
1908    in fact the vector is exactly the right size for the final match. For example,
1909    consider the pattern
1910    .sp
1911      (a)(?:(b)c|bd)
1912    .sp
1913    If a vector of 6 elements (allowing for only 1 captured substring) is given
1914    with subject string "abd", \fBpcre_exec()\fP will try to set the second
1915    captured string, thereby recording a vector overflow, before failing to match
1916    "c" and backing up to try the second alternative. The zero return, however,
1917    does correctly indicate that the maximum number of slots (namely 2) have been
1918    filled. In similar cases where there is temporary overflow, but the final
1919    number of used slots is actually less than the maximum, a non-zero value is
1920    returned.
1921  .P  .P
1922  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
1923  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1924  \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
1925  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 1373  Offset values that correspond to unused Line 1935  Offset values that correspond to unused
1935  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
1936  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
1937  return from the function is 2, because the highest used capturing subpattern  return from the function is 2, because the highest used capturing subpattern
1938  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
1939  capturing subpatterns if you wish (assuming the vector is large enough, of  (assuming the vector is large enough, of course) are set to -1.
1940  course).  .P
1941    \fBNote\fP: Elements in the first two-thirds of \fIovector\fP that do not
1942    correspond to capturing parentheses in the pattern are never changed. That is,
1943    if a pattern contains \fIn\fP capturing parentheses, no more than
1944    \fIovector[0]\fP to \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other
1945    elements (in the first two-thirds) retain whatever values they previously had.
1946  .P  .P
1947  Some convenience functions are provided for extracting the captured substrings  Some convenience functions are provided for extracting the captured substrings
1948  as separate strings. These are described below.  as separate strings. These are described below.
1949  .  .
1950    .
1951  .\" HTML <a name="errorlist"></a>  .\" HTML <a name="errorlist"></a>
1952  .SS "Error return values from \fBpcre_exec()\fP"  .SS "Error return values from \fBpcre_exec()\fP"
1953  .rs  .rs
# Line 1421  If a pattern contains back references, b Line 1989  If a pattern contains back references, b
1989  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
1990  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
1991  automatically freed at the end of matching.  automatically freed at the end of matching.
1992    .P
1993    This error is also given if \fBpcre_stack_malloc()\fP fails in
1994    \fBpcre_exec()\fP. This can happen only when PCRE has been compiled with
1995    \fB--disable-stack-for-recursion\fP.
1996  .sp  .sp
1997    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1998  .sp  .sp
# Line 1445  documentation for details. Line 2017  documentation for details.
2017  .sp  .sp
2018    PCRE_ERROR_BADUTF8        (-10)    PCRE_ERROR_BADUTF8        (-10)
2019  .sp  .sp
2020  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,
2021    and the PCRE_NO_UTF8_CHECK option was not set. If the size of the output vector
2022    (\fIovecsize\fP) is at least 2, the byte offset to the start of the the invalid
2023    UTF-8 character is placed in the first element, and a reason code is placed in
2024    the second element. The reason codes are listed in the
2025    .\" HTML <a href="#badutf8reasons">
2026    .\" </a>
2027    following section.
2028    .\"
2029    For backward compatibility, if PCRE_PARTIAL_HARD is set and the problem is a
2030    truncated UTF-8 character at the end of the subject (reason codes 1 to 5),
2031    PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
2032  .sp  .sp
2033    PCRE_ERROR_BADUTF8_OFFSET (-11)    PCRE_ERROR_BADUTF8_OFFSET (-11)
2034  .sp  .sp
2035  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
2036  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
2037    \fIstartoffset\fP did not point to the beginning of a UTF-8 character or the
2038    end of the subject.
2039  .sp  .sp
2040    PCRE_ERROR_PARTIAL        (-12)    PCRE_ERROR_PARTIAL        (-12)
2041  .sp  .sp
# Line 1462  documentation for details of partial mat Line 2047  documentation for details of partial mat
2047  .sp  .sp
2048    PCRE_ERROR_BADPARTIAL     (-13)    PCRE_ERROR_BADPARTIAL     (-13)
2049  .sp  .sp
2050  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
2051  are not supported for partial matching. See the  option was used with a compiled pattern containing items that were not
2052  .\" HREF  supported for partial matching. From release 8.00 onwards, there are no
2053  \fBpcrepartial\fP  restrictions on partial matching.
 .\"  
 documentation for details of partial matching.  
2054  .sp  .sp
2055    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
2056  .sp  .sp
# Line 1487  description above. Line 2070  description above.
2070    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
2071  .sp  .sp
2072  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
2073    .sp
2074      PCRE_ERROR_BADOFFSET      (-24)
2075    .sp
2076    The value of \fIstartoffset\fP was negative or greater than the length of the
2077    subject, that is, the value in \fIlength\fP.
2078    .sp
2079      PCRE_ERROR_SHORTUTF8      (-25)
2080    .sp
2081    This error is returned instead of PCRE_ERROR_BADUTF8 when the subject string
2082    ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD option is set.
2083    Information about the failure is returned as for PCRE_ERROR_BADUTF8. It is in
2084    fact sufficient to detect this case, but this special error code for
2085    PCRE_PARTIAL_HARD precedes the implementation of returned information; it is
2086    retained for backwards compatibility.
2087    .sp
2088      PCRE_ERROR_RECURSELOOP    (-26)
2089    .sp
2090    This error is returned when \fBpcre_exec()\fP detects a recursion loop within
2091    the pattern. Specifically, it means that either the whole pattern or a
2092    subpattern has been called recursively for the second time at the same position
2093    in the subject string. Some simple patterns that might do this are detected and
2094    faulted at compile time, but more complicated cases, in particular mutual
2095    recursions between two different subpatterns, cannot be detected until run
2096    time.
2097    .sp
2098      PCRE_ERROR_JIT_STACKLIMIT (-27)
2099    .sp
2100    This error is returned when a pattern that was successfully studied using a
2101    JIT compile option is being matched, but the memory available for the
2102    just-in-time processing stack is not large enough. See the
2103    .\" HREF
2104    \fBpcrejit\fP
2105    .\"
2106    documentation for more details.
2107    .sp
2108      PCRE_ERROR_BADMODE        (-28)
2109    .sp
2110    This error is given if a pattern that was compiled by the 8-bit library is
2111    passed to a 16-bit library function, or vice versa.
2112    .sp
2113      PCRE_ERROR_BADENDIANNESS  (-29)
2114    .sp
2115    This error is given if a pattern that was compiled and saved is reloaded on a
2116    host with different endianness. The utility function
2117    \fBpcre_pattern_to_host_byte_order()\fP can be used to convert such a pattern
2118    so that it runs on the new host.
2119  .P  .P
2120  Error numbers -16 to -20 and -22 are not used by \fBpcre_exec()\fP.  Error numbers -16 to -20, -22, and -30 are not used by \fBpcre_exec()\fP.
2121    .
2122    .
2123    .\" HTML <a name="badutf8reasons"></a>
2124    .SS "Reason codes for invalid UTF-8 strings"
2125    .rs
2126    .sp
2127    This section applies only to the 8-bit library. The corresponding information
2128    for the 16-bit library is given in the
2129    .\" HREF
2130    \fBpcre16\fP
2131    .\"
2132    page.
2133    .P
2134    When \fBpcre_exec()\fP returns either PCRE_ERROR_BADUTF8 or
2135    PCRE_ERROR_SHORTUTF8, and the size of the output vector (\fIovecsize\fP) is at
2136    least 2, the offset of the start of the invalid UTF-8 character is placed in
2137    the first output vector element (\fIovector[0]\fP) and a reason code is placed
2138    in the second element (\fIovector[1]\fP). The reason codes are given names in
2139    the \fBpcre.h\fP header file:
2140    .sp
2141      PCRE_UTF8_ERR1
2142      PCRE_UTF8_ERR2
2143      PCRE_UTF8_ERR3
2144      PCRE_UTF8_ERR4
2145      PCRE_UTF8_ERR5
2146    .sp
2147    The string ends with a truncated UTF-8 character; the code specifies how many
2148    bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8 characters to be
2149    no longer than 4 bytes, the encoding scheme (originally defined by RFC 2279)
2150    allows for up to 6 bytes, and this is checked first; hence the possibility of
2151    4 or 5 missing bytes.
2152    .sp
2153      PCRE_UTF8_ERR6
2154      PCRE_UTF8_ERR7
2155      PCRE_UTF8_ERR8
2156      PCRE_UTF8_ERR9
2157      PCRE_UTF8_ERR10
2158    .sp
2159    The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of the
2160    character do not have the binary value 0b10 (that is, either the most
2161    significant bit is 0, or the next bit is 1).
2162    .sp
2163      PCRE_UTF8_ERR11
2164      PCRE_UTF8_ERR12
2165    .sp
2166    A character that is valid by the RFC 2279 rules is either 5 or 6 bytes long;
2167    these code points are excluded by RFC 3629.
2168    .sp
2169      PCRE_UTF8_ERR13
2170    .sp
2171    A 4-byte character has a value greater than 0x10fff; these code points are
2172    excluded by RFC 3629.
2173    .sp
2174      PCRE_UTF8_ERR14
2175    .sp
2176    A 3-byte character has a value in the range 0xd800 to 0xdfff; this range of
2177    code points are reserved by RFC 3629 for use with UTF-16, and so are excluded
2178    from UTF-8.
2179    .sp
2180      PCRE_UTF8_ERR15
2181      PCRE_UTF8_ERR16
2182      PCRE_UTF8_ERR17
2183      PCRE_UTF8_ERR18
2184      PCRE_UTF8_ERR19
2185    .sp
2186    A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes for a
2187    value that can be represented by fewer bytes, which is invalid. For example,
2188    the two bytes 0xc0, 0xae give the value 0x2e, whose correct coding uses just
2189    one byte.
2190    .sp
2191      PCRE_UTF8_ERR20
2192    .sp
2193    The two most significant bits of the first byte of a character have the binary
2194    value 0b10 (that is, the most significant bit is 1 and the second is 0). Such a
2195    byte can only validly occur as the second or subsequent byte of a multi-byte
2196    character.
2197    .sp
2198      PCRE_UTF8_ERR21
2199    .sp
2200    The first byte of a character has the value 0xfe or 0xff. These values can
2201    never occur in a valid UTF-8 string.
2202  .  .
2203  .  .
2204  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
# Line 1637  These functions call \fBpcre_get_stringn Line 2347  These functions call \fBpcre_get_stringn
2347  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
2348  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,
2349  the behaviour may not be what you want (see the next section).  the behaviour may not be what you want (see the next section).
2350    .P
2351    \fBWarning:\fP If the pattern uses the (?| feature to set up multiple
2352    subpatterns with the same number, as described in the
2353    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
2354    .\" </a>
2355    section on duplicate subpattern numbers
2356    .\"
2357    in the
2358    .\" HREF
2359    \fBpcrepattern\fP
2360    .\"
2361    page, you cannot use names to distinguish the different subpatterns, because
2362    names are not included in the compiled code. The matching process uses only
2363    numbers. For this reason, the use of different names for subpatterns of the
2364    same number causes an error at compile time.
2365  .  .
2366  .  .
2367  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
# Line 1647  the behaviour may not be what you want ( Line 2372  the behaviour may not be what you want (
2372  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
2373  .PP  .PP
2374  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
2375  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
2376  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
2377  example is shown in the  such subpatterns are named, they are required to use the same names.)
2378    .P
2379    Normally, patterns with duplicate names are such that in any one match, only
2380    one of the named subpatterns participates. An example is shown in the
2381  .\" HREF  .\" HREF
2382  \fBpcrepattern\fP  \fBpcrepattern\fP
2383  .\"  .\"
# Line 1669  fourth are pointers to variables which a Line 2397  fourth are pointers to variables which a
2397  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
2398  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
2399  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
2400  described above in the section entitled \fIInformation about a pattern\fP.  described above in the section entitled \fIInformation about a pattern\fP
2401    .\" HTML <a href="#infoaboutpattern">
2402    .\" </a>
2403    above.
2404    .\"
2405  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
2406  numbers, and hence the captured data, if any.  numbers, and hence the captured data, if any.
2407  .  .
# Line 1696  other alternatives. Ultimately, when it Line 2428  other alternatives. Ultimately, when it
2428  will yield PCRE_ERROR_NOMATCH.  will yield PCRE_ERROR_NOMATCH.
2429  .  .
2430  .  .
2431    .SH "OBTAINING AN ESTIMATE OF STACK USAGE"
2432    .rs
2433    .sp
2434    Matching certain patterns using \fBpcre_exec()\fP can use a lot of process
2435    stack, which in certain environments can be rather limited in size. Some users
2436    find it helpful to have an estimate of the amount of stack that is used by
2437    \fBpcre_exec()\fP, to help them set recursion limits, as described in the
2438    .\" HREF
2439    \fBpcrestack\fP
2440    .\"
2441    documentation. The estimate that is output by \fBpcretest\fP when called with
2442    the \fB-m\fP and \fB-C\fP options is obtained by calling \fBpcre_exec\fP with
2443    the values NULL, NULL, NULL, -999, and -999 for its first five arguments.
2444    .P
2445    Normally, if its first argument is NULL, \fBpcre_exec()\fP immediately returns
2446    the negative error code PCRE_ERROR_NULL, but with this special combination of
2447    arguments, it returns instead a negative number whose absolute value is the
2448    approximate stack frame size in bytes. (A negative number is used so that it is
2449    clear that no match has happened.) The value is approximate because in some
2450    cases, recursive calls to \fBpcre_exec()\fP occur when there are one or two
2451    additional variables on the stack.
2452    .P
2453    If PCRE has been compiled to use the heap instead of the stack for recursion,
2454    the value returned is the size of each block that is obtained from the heap.
2455    .
2456    .
2457  .\" HTML <a name="dfamatch"></a>  .\" HTML <a name="dfamatch"></a>
2458  .SH "MATCHING A PATTERN: THE ALTERNATIVE FUNCTION"  .SH "MATCHING A PATTERN: THE ALTERNATIVE FUNCTION"
2459  .rs  .rs
# Line 1713  a compiled pattern, using a matching alg Line 2471  a compiled pattern, using a matching alg
2471  just once, and does not backtrack. This has different characteristics to the  just once, and does not backtrack. This has different characteristics to the
2472  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
2473  patterns are not supported. Nevertheless, there are times when this kind of  patterns are not supported. Nevertheless, there are times when this kind of
2474  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
2475  the  list of features that \fBpcre_dfa_exec()\fP does not support, see the
2476  .\" HREF  .\" HREF
2477  \fBpcrematching\fP  \fBpcrematching\fP
2478  .\"  .\"
# Line 1753  Here is an example of a simple call to \ Line 2511  Here is an example of a simple call to \
2511  .sp  .sp
2512  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
2513  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,
2514  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
2515  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,
2516  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.
2517  .sp  All but the last four of these are exactly the same as for \fBpcre_exec()\fP,
2518    PCRE_PARTIAL  so their description is not repeated here.
2519  .sp  .sp
2520  This has the same general effect as it does for \fBpcre_exec()\fP, but the    PCRE_PARTIAL_HARD
2521  details are slightly different. When PCRE_PARTIAL is set for    PCRE_PARTIAL_SOFT
2522  \fBpcre_dfa_exec()\fP, the return code PCRE_ERROR_NOMATCH is converted into  .sp
2523  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
2524  complete matches, but there is still at least one matching possibility. The  details are slightly different. When PCRE_PARTIAL_HARD is set for
2525  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
2526  matching string.  is reached and there is still at least one matching possibility that requires
2527    additional characters. This happens even if some complete matches have also
2528    been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
2529    is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
2530    there have been no complete matches, but there is still at least one matching
2531    possibility. The portion of the string that was inspected when the longest
2532    partial match was found is set as the first matching string in both cases.
2533    There is a more detailed discussion of partial and multi-segment matching, with
2534    examples, in the
2535    .\" HREF
2536    \fBpcrepartial\fP
2537    .\"
2538    documentation.
2539  .sp  .sp
2540    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
2541  .sp  .sp
# Line 1776  matching point in the subject string. Line 2546  matching point in the subject string.
2546  .sp  .sp
2547    PCRE_DFA_RESTART    PCRE_DFA_RESTART
2548  .sp  .sp
2549  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
2550  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
2551  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
2552  option requests this action; when it is set, the \fIworkspace\fP and  \fIworkspace\fP and \fIwscount\fP options must reference the same vector as
2553  \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
2554  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  
2555  .\" HREF  .\" HREF
2556  \fBpcrepartial\fP  \fBpcrepartial\fP
2557  .\"  .\"
2558  documentation.  documentation.
2559  .  .
2560    .
2561  .SS "Successful returns from \fBpcre_dfa_exec()\fP"  .SS "Successful returns from \fBpcre_dfa_exec()\fP"
2562  .rs  .rs
2563  .sp  .sp
# Line 1819  returns data, even though the meaning of Line 2589  returns data, even though the meaning of
2589  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
2590  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
2591  \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
2592  the longest matches.  the longest matches. Unlike \fBpcre_exec()\fP, \fBpcre_dfa_exec()\fP can use
2593    the entire \fIovector\fP for returning matched strings.
2594    .
2595  .  .
2596  .SS "Error returns from \fBpcre_dfa_exec()\fP"  .SS "Error returns from \fBpcre_dfa_exec()\fP"
2597  .rs  .rs
# Line 1848  group. These are not supported. Line 2620  group. These are not supported.
2620    PCRE_ERROR_DFA_UMLIMIT    (-18)    PCRE_ERROR_DFA_UMLIMIT    (-18)
2621  .sp  .sp
2622  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
2623  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
2624  supported (it is meaningless).  \fImatch_limit_recursion\fP fields. This is not supported (these fields are
2625    meaningless for DFA matching).
2626  .sp  .sp
2627    PCRE_ERROR_DFA_WSSIZE     (-19)    PCRE_ERROR_DFA_WSSIZE     (-19)
2628  .sp  .sp
# Line 1862  When a recursive subpattern is processed Line 2635  When a recursive subpattern is processed
2635  recursively, using private vectors for \fIovector\fP and \fIworkspace\fP. This  recursively, using private vectors for \fIovector\fP and \fIworkspace\fP. This
2636  error is given if the output vector is not large enough. This should be  error is given if the output vector is not large enough. This should be
2637  extremely rare, as a vector of size 1000 is used.  extremely rare, as a vector of size 1000 is used.
2638    .sp
2639      PCRE_ERROR_DFA_BADRESTART (-30)
2640    .sp
2641    When \fBpcre_dfa_exec()\fP is called with the \fBPCRE_DFA_RESTART\fP option,
2642    some plausibility checks are made on the contents of the workspace, which
2643    should contain data about the previous partial match. If any of these checks
2644    fail, this error is given.
2645  .  .
2646  .  .
2647  .SH "SEE ALSO"  .SH "SEE ALSO"
2648  .rs  .rs
2649  .sp  .sp
2650  \fBpcrebuild\fP(3), \fBpcrecallout\fP(3), \fBpcrecpp(3)\fP(3),  \fBpcre16\fP(3), \fBpcrebuild\fP(3), \fBpcrecallout\fP(3), \fBpcrecpp(3)\fP(3),
2651  \fBpcrematching\fP(3), \fBpcrepartial\fP(3), \fBpcreposix\fP(3),  \fBpcrematching\fP(3), \fBpcrepartial\fP(3), \fBpcreposix\fP(3),
2652  \fBpcreprecompile\fP(3), \fBpcresample\fP(3), \fBpcrestack\fP(3).  \fBpcreprecompile\fP(3), \fBpcresample\fP(3), \fBpcrestack\fP(3).
2653  .  .
# Line 1886  Cambridge CB2 3QH, England. Line 2666  Cambridge CB2 3QH, England.
2666  .rs  .rs
2667  .sp  .sp
2668  .nf  .nf
2669  Last updated: 09 August 2007  Last updated: 04 May 2012
2670  Copyright (c) 1997-2007 University of Cambridge.  Copyright (c) 1997-2012 University of Cambridge.
2671  .fi  .fi

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