/[pcre]/code/trunk/doc/pcreapi.3
ViewVC logotype

Diff of /code/trunk/doc/pcreapi.3

Parent Directory Parent Directory | Revision Log Revision Log | View Patch Patch

revision 71 by nigel, Sat Feb 24 21:40:24 2007 UTC revision 93 by nigel, Sat Feb 24 21:41:42 2007 UTC
# Line 1  Line 1 
1  .TH PCRE 3  .TH PCREAPI 3
2  .SH NAME  .SH NAME
3  PCRE - Perl-compatible regular expressions  PCRE - Perl-compatible regular expressions
4  .SH SYNOPSIS OF PCRE API  .SH "PCRE NATIVE API"
5  .rs  .rs
6  .sp  .sp
7  .B #include <pcre.h>  .B #include <pcre.h>
8  .PP  .PP
9  .SM  .SM
10  .br  .br
11  .B pcre *pcre_compile(const char *\fIpattern\fR, int \fIoptions\fR,  .B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,
12  .ti +5n  .ti +5n
13  .B const char **\fIerrptr\fR, int *\fIerroffset\fR,  .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
14  .ti +5n  .ti +5n
15  .B const unsigned char *\fItableptr\fR);  .B const unsigned char *\fItableptr\fP);
16  .PP  .PP
17  .br  .br
18  .B pcre_extra *pcre_study(const pcre *\fIcode\fR, int \fIoptions\fR,  .B pcre *pcre_compile2(const char *\fIpattern\fP, int \fIoptions\fP,
19  .ti +5n  .ti +5n
20  .B const char **\fIerrptr\fR);  .B int *\fIerrorcodeptr\fP,
21    .ti +5n
22    .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
23    .ti +5n
24    .B const unsigned char *\fItableptr\fP);
25    .PP
26    .br
27    .B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP,
28    .ti +5n
29    .B const char **\fIerrptr\fP);
30  .PP  .PP
31  .br  .br
32  .B int pcre_exec(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"  .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
33  .ti +5n  .ti +5n
34  .B "const char *\fIsubject\fR," int \fIlength\fR, int \fIstartoffset\fR,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
35  .ti +5n  .ti +5n
36  .B int \fIoptions\fR, int *\fIovector\fR, int \fIovecsize\fR);  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
37  .PP  .PP
38  .br  .br
39  .B int pcre_copy_named_substring(const pcre *\fIcode\fR,  .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
40  .ti +5n  .ti +5n
41  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
42  .ti +5n  .ti +5n
43  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,
44  .ti +5n  .ti +5n
45  .B char *\fIbuffer\fR, int \fIbuffersize\fR);  .B int *\fIworkspace\fP, int \fIwscount\fP);
46  .PP  .PP
47  .br  .br
48  .B int pcre_copy_substring(const char *\fIsubject\fR, int *\fIovector\fR,  .B int pcre_copy_named_substring(const pcre *\fIcode\fP,
49    .ti +5n
50    .B const char *\fIsubject\fP, int *\fIovector\fP,
51  .ti +5n  .ti +5n
52  .B int \fIstringcount\fR, int \fIstringnumber\fR, char *\fIbuffer\fR,  .B int \fIstringcount\fP, const char *\fIstringname\fP,
53  .ti +5n  .ti +5n
54  .B int \fIbuffersize\fR);  .B char *\fIbuffer\fP, int \fIbuffersize\fP);
55  .PP  .PP
56  .br  .br
57  .B int pcre_get_named_substring(const pcre *\fIcode\fR,  .B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\fP,
58  .ti +5n  .ti +5n
59  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP,
60  .ti +5n  .ti +5n
61  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B int \fIbuffersize\fP);
62    .PP
63    .br
64    .B int pcre_get_named_substring(const pcre *\fIcode\fP,
65    .ti +5n
66    .B const char *\fIsubject\fP, int *\fIovector\fP,
67  .ti +5n  .ti +5n
68  .B const char **\fIstringptr\fR);  .B int \fIstringcount\fP, const char *\fIstringname\fP,
69    .ti +5n
70    .B const char **\fIstringptr\fP);
71  .PP  .PP
72  .br  .br
73  .B int pcre_get_stringnumber(const pcre *\fIcode\fR,  .B int pcre_get_stringnumber(const pcre *\fIcode\fP,
74  .ti +5n  .ti +5n
75  .B const char *\fIname\fR);  .B const char *\fIname\fP);
76  .PP  .PP
77  .br  .br
78  .B int pcre_get_substring(const char *\fIsubject\fR, int *\fIovector\fR,  .B int pcre_get_stringtable_entries(const pcre *\fIcode\fP,
79  .ti +5n  .ti +5n
80  .B int \fIstringcount\fR, int \fIstringnumber\fR,  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
81    .PP
82    .br
83    .B int pcre_get_substring(const char *\fIsubject\fP, int *\fIovector\fP,
84    .ti +5n
85    .B int \fIstringcount\fP, int \fIstringnumber\fP,
86  .ti +5n  .ti +5n
87  .B const char **\fIstringptr\fR);  .B const char **\fIstringptr\fP);
88  .PP  .PP
89  .br  .br
90  .B int pcre_get_substring_list(const char *\fIsubject\fR,  .B int pcre_get_substring_list(const char *\fIsubject\fP,
91  .ti +5n  .ti +5n
92  .B int *\fIovector\fR, int \fIstringcount\fR, "const char ***\fIlistptr\fR);"  .B int *\fIovector\fP, int \fIstringcount\fP, "const char ***\fIlistptr\fP);"
93  .PP  .PP
94  .br  .br
95  .B void pcre_free_substring(const char *\fIstringptr\fR);  .B void pcre_free_substring(const char *\fIstringptr\fP);
96  .PP  .PP
97  .br  .br
98  .B void pcre_free_substring_list(const char **\fIstringptr\fR);  .B void pcre_free_substring_list(const char **\fIstringptr\fP);
99  .PP  .PP
100  .br  .br
101  .B const unsigned char *pcre_maketables(void);  .B const unsigned char *pcre_maketables(void);
102  .PP  .PP
103  .br  .br
104  .B int pcre_fullinfo(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"  .B int pcre_fullinfo(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
105  .ti +5n  .ti +5n
106  .B int \fIwhat\fR, void *\fIwhere\fR);  .B int \fIwhat\fP, void *\fIwhere\fP);
107  .PP  .PP
108  .br  .br
109  .B int pcre_info(const pcre *\fIcode\fR, int *\fIoptptr\fR, int  .B int pcre_info(const pcre *\fIcode\fP, int *\fIoptptr\fP, int
110  .B *\fIfirstcharptr\fR);  .B *\fIfirstcharptr\fP);
111  .PP  .PP
112  .br  .br
113  .B int pcre_config(int \fIwhat\fR, void *\fIwhere\fR);  .B int pcre_refcount(pcre *\fIcode\fP, int \fIadjust\fP);
114    .PP
115    .br
116    .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
117  .PP  .PP
118  .br  .br
119  .B char *pcre_version(void);  .B char *pcre_version(void);
# Line 99  PCRE - Perl-compatible regular expressio Line 125  PCRE - Perl-compatible regular expressio
125  .B void (*pcre_free)(void *);  .B void (*pcre_free)(void *);
126  .PP  .PP
127  .br  .br
128    .B void *(*pcre_stack_malloc)(size_t);
129    .PP
130    .br
131    .B void (*pcre_stack_free)(void *);
132    .PP
133    .br
134  .B int (*pcre_callout)(pcre_callout_block *);  .B int (*pcre_callout)(pcre_callout_block *);
135    .
136  .SH PCRE API  .
137    .SH "PCRE API OVERVIEW"
138  .rs  .rs
139  .sp  .sp
140  PCRE has its own native API, which is described in this document. There is also  PCRE has its own native API, which is described in this document. There are
141  a set of wrapper functions that correspond to the POSIX regular expression API.  also some wrapper functions that correspond to the POSIX regular expression
142  These are described in the \fBpcreposix\fR documentation.  API. These are described in the
143    .\" HREF
144  The native API function prototypes are defined in the header file \fBpcre.h\fR,  \fBpcreposix\fP
145  and on Unix systems the library itself is called \fBlibpcre.a\fR, so can be  .\"
146  accessed by adding \fB-lpcre\fR to the command for linking an application which  documentation. Both of these APIs define a set of C function calls. A C++
147  calls it. The header file defines the macros PCRE_MAJOR and PCRE_MINOR to  wrapper is distributed with PCRE. It is documented in the
148  contain the major and minor release numbers for the library. Applications can  .\" HREF
149  use these to include support for different releases.  \fBpcrecpp\fP
150    .\"
151  The functions \fBpcre_compile()\fR, \fBpcre_study()\fR, and \fBpcre_exec()\fR  page.
152  are used for compiling and matching regular expressions. A sample program that  .P
153  demonstrates the simplest way of using them is given in the file  The native API C function prototypes are defined in the header file
154  \fIpcredemo.c\fR. The \fBpcresample\fR documentation describes how to run it.  \fBpcre.h\fP, and on Unix systems the library itself is called \fBlibpcre\fP.
155    It can normally be accessed by adding \fB-lpcre\fP to the command for linking
156  There are convenience functions for extracting captured substrings from a  an application that uses PCRE. The header file defines the macros PCRE_MAJOR
157  matched subject string. They are:  and PCRE_MINOR to contain the major and minor release numbers for the library.
158    Applications can use these to include support for different releases of PCRE.
159    \fBpcre_copy_substring()\fR  .P
160    \fBpcre_copy_named_substring()\fR  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,
161    \fBpcre_get_substring()\fR  and \fBpcre_exec()\fP are used for compiling and matching regular expressions
162    \fBpcre_get_named_substring()\fR  in a Perl-compatible manner. A sample program that demonstrates the simplest
163    \fBpcre_get_substring_list()\fR  way of using them is provided in the file called \fIpcredemo.c\fP in the source
164    distribution. The
165  \fBpcre_free_substring()\fR and \fBpcre_free_substring_list()\fR are also  .\" HREF
166    \fBpcresample\fP
167    .\"
168    documentation describes how to run it.
169    .P
170    A second matching function, \fBpcre_dfa_exec()\fP, which is not
171    Perl-compatible, is also provided. This uses a different algorithm for the
172    matching. The alternative algorithm finds all possible matches (at a given
173    point in the subject), and scans the subject just once. However, this algorithm
174    does not return captured substrings. A description of the two matching
175    algorithms and their advantages and disadvantages is given in the
176    .\" HREF
177    \fBpcrematching\fP
178    .\"
179    documentation.
180    .P
181    In addition to the main compiling and matching functions, there are convenience
182    functions for extracting captured substrings from a subject string that is
183    matched by \fBpcre_exec()\fP. They are:
184    .sp
185      \fBpcre_copy_substring()\fP
186      \fBpcre_copy_named_substring()\fP
187      \fBpcre_get_substring()\fP
188      \fBpcre_get_named_substring()\fP
189      \fBpcre_get_substring_list()\fP
190      \fBpcre_get_stringnumber()\fP
191      \fBpcre_get_stringtable_entries()\fP
192    .sp
193    \fBpcre_free_substring()\fP and \fBpcre_free_substring_list()\fP are also
194  provided, to free the memory used for extracted strings.  provided, to free the memory used for extracted strings.
195    .P
196  The function \fBpcre_maketables()\fR is used (optionally) to build a set of  The function \fBpcre_maketables()\fP is used to build a set of character tables
197  character tables in the current locale for passing to \fBpcre_compile()\fR.  in the current locale for passing to \fBpcre_compile()\fP, \fBpcre_exec()\fP,
198    or \fBpcre_dfa_exec()\fP. This is an optional facility that is provided for
199  The function \fBpcre_fullinfo()\fR is used to find out information about a  specialist use. Most commonly, no special tables are passed, in which case
200  compiled pattern; \fBpcre_info()\fR is an obsolete version which returns only  internal tables that are generated when PCRE is built are used.
201    .P
202    The function \fBpcre_fullinfo()\fP is used to find out information about a
203    compiled pattern; \fBpcre_info()\fP is an obsolete version that returns only
204  some of the available information, but is retained for backwards compatibility.  some of the available information, but is retained for backwards compatibility.
205  The function \fBpcre_version()\fR returns a pointer to a string containing the  The function \fBpcre_version()\fP returns a pointer to a string containing the
206  version of PCRE and its date of release.  version of PCRE and its date of release.
207    .P
208  The global variables \fBpcre_malloc\fR and \fBpcre_free\fR initially contain  The function \fBpcre_refcount()\fP maintains a reference count in a data block
209  the entry points of the standard \fBmalloc()\fR and \fBfree()\fR functions  containing a compiled pattern. This is provided for the benefit of
210    object-oriented applications.
211    .P
212    The global variables \fBpcre_malloc\fP and \fBpcre_free\fP initially contain
213    the entry points of the standard \fBmalloc()\fP and \fBfree()\fP functions,
214  respectively. PCRE calls the memory management functions via these variables,  respectively. PCRE calls the memory management functions via these variables,
215  so a calling program can replace them if it wishes to intercept the calls. This  so a calling program can replace them if it wishes to intercept the calls. This
216  should be done before calling any PCRE functions.  should be done before calling any PCRE functions.
217    .P
218  The global variable \fBpcre_callout\fR initially contains NULL. It can be set  The global variables \fBpcre_stack_malloc\fP and \fBpcre_stack_free\fP are also
219    indirections to memory management functions. These special functions are used
220    only when PCRE is compiled to use the heap for remembering data, instead of
221    recursive function calls, when running the \fBpcre_exec()\fP function. See the
222    .\" HREF
223    \fBpcrebuild\fP
224    .\"
225    documentation for details of how to do this. It is a non-standard way of
226    building PCRE, for use in environments that have limited stacks. Because of the
227    greater use of memory management, it runs more slowly. Separate functions are
228    provided so that special-purpose external code can be used for this case. When
229    used, these functions are always called in a stack-like manner (last obtained,
230    first freed), and always for memory blocks of the same size. There is a
231    discussion about PCRE's stack usage in the
232    .\" HREF
233    \fBpcrestack\fP
234    .\"
235    documentation.
236    .P
237    The global variable \fBpcre_callout\fP initially contains NULL. It can be set
238  by the caller to a "callout" function, which PCRE will then call at specified  by the caller to a "callout" function, which PCRE will then call at specified
239  points during a matching operation. Details are given in the \fBpcrecallout\fR  points during a matching operation. Details are given in the
240    .\" HREF
241    \fBpcrecallout\fP
242    .\"
243  documentation.  documentation.
244    .
245    .
246    .SH NEWLINES
247    .rs
248    .sp
249    PCRE supports four different conventions for indicating line breaks in
250    strings: a single CR (carriage return) character, a single LF (linefeed)
251    character, the two-character sequence CRLF, or any Unicode newline sequence.
252    The Unicode newline sequences are the three just mentioned, plus the single
253    characters VT (vertical tab, U+000B), FF (formfeed, U+000C), NEL (next line,
254    U+0085), LS (line separator, U+2028), and PS (paragraph separator, U+2029).
255    .P
256    Each of the first three conventions is used by at least one operating system as
257    its standard newline sequence. When PCRE is built, a default can be specified.
258    The default default is LF, which is the Unix standard. When PCRE is run, the
259    default can be overridden, either when a pattern is compiled, or when it is
260    matched.
261    .P
262    In the PCRE documentation the word "newline" is used to mean "the character or
263    pair of characters that indicate a line break". The choice of newline
264    convention affects the handling of the dot, circumflex, and dollar
265    metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
266    recognized line ending sequence, the match position advancement for a
267    non-anchored pattern. The choice of newline convention does not affect the
268    interpretation of the \en or \er escape sequences.
269    .
270    .
271  .SH MULTITHREADING  .SH MULTITHREADING
272  .rs  .rs
273  .sp  .sp
274  The PCRE functions can be used in multi-threading applications, with the  The PCRE functions can be used in multi-threading applications, with the
275  proviso that the memory management functions pointed to by \fBpcre_malloc\fR  proviso that the memory management functions pointed to by \fBpcre_malloc\fP,
276  and \fBpcre_free\fR, and the callout function pointed to by \fBpcre_callout\fR,  \fBpcre_free\fP, \fBpcre_stack_malloc\fP, and \fBpcre_stack_free\fP, and the
277  are shared by all threads.  callout function pointed to by \fBpcre_callout\fP, are shared by all threads.
278    .P
279  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
280  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.
281    .
282  .SH CHECKING BUILD-TIME OPTIONS  .
283    .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"
284    .rs
285    .sp
286    The compiled form of a regular expression can be saved and re-used at a later
287    time, possibly by a different program, and even on a host other than the one on
288    which it was compiled. Details are given in the
289    .\" HREF
290    \fBpcreprecompile\fP
291    .\"
292    documentation.
293    .
294    .
295    .SH "CHECKING BUILD-TIME OPTIONS"
296  .rs  .rs
297  .sp  .sp
298  .B int pcre_config(int \fIwhat\fR, void *\fIwhere\fR);  .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
299  .PP  .PP
300  The function \fBpcre_config()\fR makes it possible for a PCRE client to  The function \fBpcre_config()\fP makes it possible for a PCRE client to
301  discover which optional features have been compiled into the PCRE library. The  discover which optional features have been compiled into the PCRE library. The
302  .\" HREF  .\" HREF
303  \fBpcrebuild\fR  \fBpcrebuild\fP
304  .\"  .\"
305  documentation has more details about these optional features.  documentation has more details about these optional features.
306    .P
307  The first argument for \fBpcre_config()\fR is an integer, specifying which  The first argument for \fBpcre_config()\fP is an integer, specifying which
308  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
309  which the information is placed. The following information is available:  which the information is placed. The following information is available:
310    .sp
311    PCRE_CONFIG_UTF8    PCRE_CONFIG_UTF8
312    .sp
313  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;
314  otherwise it is set to zero.  otherwise it is set to zero.
315    .sp
316      PCRE_CONFIG_UNICODE_PROPERTIES
317    .sp
318    The output is an integer that is set to one if support for Unicode character
319    properties is available; otherwise it is set to zero.
320    .sp
321    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
322    .sp
323  The output is an integer that is set to the value of the code that is used for  The output is an integer whose value specifies the default character sequence
324  the newline character. It is either linefeed (10) or carriage return (13), and  that is recognized as meaning "newline". The four values that are supported
325  should normally be the standard character for your operating system.  are: 10 for LF, 13 for CR, 3338 for CRLF, and -1 for ANY. The default should
326    normally be the standard sequence for your operating system.
327    .sp
328    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
329    .sp
330  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
331  linkage in compiled regular expressions. The value is 2, 3, or 4. Larger values  linkage in compiled regular expressions. The value is 2, 3, or 4. Larger values
332  allow larger regular expressions to be compiled, at the expense of slower  allow larger regular expressions to be compiled, at the expense of slower
333  matching. The default value of 2 is sufficient for all but the most massive  matching. The default value of 2 is sufficient for all but the most massive
334  patterns, since it allows the compiled pattern to be up to 64K in size.  patterns, since it allows the compiled pattern to be up to 64K in size.
335    .sp
336    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
337    .sp
338  The output is an integer that contains the threshold above which the POSIX  The output is an integer that contains the threshold above which the POSIX
339  interface uses \fBmalloc()\fR for output vectors. Further details are given in  interface uses \fBmalloc()\fP for output vectors. Further details are given in
340  the \fBpcreposix\fR documentation.  the
341    .\" HREF
342    \fBpcreposix\fP
343    .\"
344    documentation.
345    .sp
346    PCRE_CONFIG_MATCH_LIMIT    PCRE_CONFIG_MATCH_LIMIT
347    .sp
348  The output is an integer that gives the default limit for the number of  The output is an integer that gives the default limit for the number of
349  internal matching function calls in a \fBpcre_exec()\fR execution. Further  internal matching function calls in a \fBpcre_exec()\fP execution. Further
350  details are given with \fBpcre_exec()\fR below.  details are given with \fBpcre_exec()\fP below.
351    .sp
352  .SH COMPILING A PATTERN    PCRE_CONFIG_MATCH_LIMIT_RECURSION
353  .rs  .sp
354  .sp  The output is an integer that gives the default limit for the depth of
355  .B pcre *pcre_compile(const char *\fIpattern\fR, int \fIoptions\fR,  recursion when calling the internal matching function in a \fBpcre_exec()\fP
356  .ti +5n  execution. Further details are given with \fBpcre_exec()\fP below.
357  .B const char **\fIerrptr\fR, int *\fIerroffset\fR,  .sp
358  .ti +5n    PCRE_CONFIG_STACKRECURSE
359  .B const unsigned char *\fItableptr\fR);  .sp
360  .PP  The output is an integer that is set to one if internal recursion when running
361    \fBpcre_exec()\fP is implemented by recursive function calls that use the stack
362  The function \fBpcre_compile()\fR is called to compile a pattern into an  to remember their state. This is the usual way that PCRE is compiled. The
363  internal form. The pattern is a C string terminated by a binary zero, and  output is zero if PCRE was compiled to use blocks of data on the heap instead
364  is passed in the argument \fIpattern\fR. A pointer to a single block of memory  of recursive function calls. In this case, \fBpcre_stack_malloc\fP and
365  that is obtained via \fBpcre_malloc\fR is returned. This contains the compiled  \fBpcre_stack_free\fP are called to manage memory blocks on the heap, thus
366  code and related data. The \fBpcre\fR type is defined for the returned block;  avoiding the use of the stack.
367  this is a typedef for a structure whose contents are not externally defined. It  .
368  is up to the caller to free the memory when it is no longer required.  .
369    .SH "COMPILING A PATTERN"
370    .rs
371    .sp
372    .B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,
373    .ti +5n
374    .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
375    .ti +5n
376    .B const unsigned char *\fItableptr\fP);
377    .sp
378    .B pcre *pcre_compile2(const char *\fIpattern\fP, int \fIoptions\fP,
379    .ti +5n
380    .B int *\fIerrorcodeptr\fP,
381    .ti +5n
382    .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
383    .ti +5n
384    .B const unsigned char *\fItableptr\fP);
385    .P
386    Either of the functions \fBpcre_compile()\fP or \fBpcre_compile2()\fP can be
387    called to compile a pattern into an internal form. The only difference between
388    the two interfaces is that \fBpcre_compile2()\fP has an additional argument,
389    \fIerrorcodeptr\fP, via which a numerical error code can be returned.
390    .P
391    The pattern is a C string terminated by a binary zero, and is passed in the
392    \fIpattern\fP argument. A pointer to a single block of memory that is obtained
393    via \fBpcre_malloc\fP is returned. This contains the compiled code and related
394    data. The \fBpcre\fP type is defined for the returned block; this is a typedef
395    for a structure whose contents are not externally defined. It is up to the
396    caller to free the memory (via \fBpcre_free\fP) when it is no longer required.
397    .P
398  Although the compiled code of a PCRE regex is relocatable, that is, it does not  Although the compiled code of a PCRE regex is relocatable, that is, it does not
399  depend on memory location, the complete \fBpcre\fR data block is not  depend on memory location, the complete \fBpcre\fP data block is not
400  fully relocatable, because it contains a copy of the \fItableptr\fR argument,  fully relocatable, because it may contain a copy of the \fItableptr\fP
401  which is an address (see below).  argument, which is an address (see below).
402    .P
403  The \fIoptions\fR argument contains independent bits that affect the  The \fIoptions\fP argument contains various bit settings that affect the
404  compilation. It should be zero if no options are required. Some of the options,  compilation. It should be zero if no options are required. The available
405  in particular, those that are compatible with Perl, can also be set and unset  options are described below. Some of them, in particular, those that are
406  from within the pattern (see the detailed description of regular expressions  compatible with Perl, can also be set and unset from within the pattern (see
407  in the \fBpcrepattern\fR documentation). For these options, the contents of the  the detailed description in the
408  \fIoptions\fR argument specifies their initial settings at the start of  .\" HREF
409  compilation and execution. The PCRE_ANCHORED option can be set at the time of  \fBpcrepattern\fP
410    .\"
411    documentation). For these options, the contents of the \fIoptions\fP argument
412    specifies their initial settings at the start of compilation and execution. The
413    PCRE_ANCHORED and PCRE_NEWLINE_\fIxxx\fP options can be set at the time of
414  matching as well as at compile time.  matching as well as at compile time.
415    .P
416  If \fIerrptr\fR is NULL, \fBpcre_compile()\fR returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
417  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fR returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
418  NULL, and sets the variable pointed to by \fIerrptr\fR to point to a textual  NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual
419  error message. The offset from the start of the pattern to the character where  error message. This is a static string that is part of the library. You must
420  the error was discovered is placed in the variable pointed to by  not try to free it. The offset from the start of the pattern to the character
421  \fIerroffset\fR, which must not be NULL. If it is, an immediate error is given.  where the error was discovered is placed in the variable pointed to by
422    \fIerroffset\fP, which must not be NULL. If it is, an immediate error is given.
423  If the final argument, \fItableptr\fR, is NULL, PCRE uses a default set of  .P
424  character tables which are built when it is compiled, using the default C  If \fBpcre_compile2()\fP is used instead of \fBpcre_compile()\fP, and the
425  locale. Otherwise, \fItableptr\fR must be the result of a call to  \fIerrorcodeptr\fP argument is not NULL, a non-zero error code number is
426  \fBpcre_maketables()\fR. See the section on locale support below.  returned via this argument in the event of an error. This is in addition to the
427    textual error message. Error codes and messages are listed below.
428  This code fragment shows a typical straightforward call to \fBpcre_compile()\fR:  .P
429    If the final argument, \fItableptr\fP, is NULL, PCRE uses a default set of
430    character tables that are built when PCRE is compiled, using the default C
431    locale. Otherwise, \fItableptr\fP must be an address that is the result of a
432    call to \fBpcre_maketables()\fP. This value is stored with the compiled
433    pattern, and used again by \fBpcre_exec()\fP, unless another table pointer is
434    passed to it. For more discussion, see the section on locale support below.
435    .P
436    This code fragment shows a typical straightforward call to \fBpcre_compile()\fP:
437    .sp
438    pcre *re;    pcre *re;
439    const char *error;    const char *error;
440    int erroffset;    int erroffset;
# Line 265  This code fragment shows a typical strai Line 444  This code fragment shows a typical strai
444      &error,           /* for error message */      &error,           /* for error message */
445      &erroffset,       /* for error offset */      &erroffset,       /* for error offset */
446      NULL);            /* use default character tables */      NULL);            /* use default character tables */
447    .sp
448  The following option bits are defined:  The following names for option bits are defined in the \fBpcre.h\fP header
449    file:
450    .sp
451    PCRE_ANCHORED    PCRE_ANCHORED
452    .sp
453  If this bit is set, the pattern is forced to be "anchored", that is, it is  If this bit is set, the pattern is forced to be "anchored", that is, it is
454  constrained to match only at the first matching point in the string which is  constrained to match only at the first matching point in the string that is
455  being searched (the "subject string"). This effect can also be achieved by  being searched (the "subject string"). This effect can also be achieved by
456  appropriate constructs in the pattern itself, which is the only way to do it in  appropriate constructs in the pattern itself, which is the only way to do it in
457  Perl.  Perl.
458    .sp
459      PCRE_AUTO_CALLOUT
460    .sp
461    If this bit is set, \fBpcre_compile()\fP automatically inserts callout items,
462    all with number 255, before each pattern item. For discussion of the callout
463    facility, see the
464    .\" HREF
465    \fBpcrecallout\fP
466    .\"
467    documentation.
468    .sp
469    PCRE_CASELESS    PCRE_CASELESS
470    .sp
471  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
472  letters. It is equivalent to Perl's /i option, and it can be changed within a  letters. It is equivalent to Perl's /i option, and it can be changed within a
473  pattern by a (?i) option setting.  pattern by a (?i) option setting. In UTF-8 mode, PCRE always understands the
474    concept of case for characters whose values are less than 128, so caseless
475    matching is always possible. For characters with higher values, the concept of
476    case is supported if PCRE is compiled with Unicode property support, but not
477    otherwise. If you want to use caseless matching for characters 128 and above,
478    you must ensure that PCRE is compiled with Unicode property support as well as
479    with UTF-8 support.
480    .sp
481    PCRE_DOLLAR_ENDONLY    PCRE_DOLLAR_ENDONLY
482    .sp
483  If this bit is set, a dollar metacharacter in the pattern matches only at the  If this bit is set, a dollar metacharacter in the pattern matches only at the
484  end of the subject string. Without this option, a dollar also matches  end of the subject string. Without this option, a dollar also matches
485  immediately before the final character if it is a newline (but not before any  immediately before a newline at the end of the string (but not before any other
486  other newlines). The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is  newlines). The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is set.
487  set. There is no equivalent to this option in Perl, and no way to set it within  There is no equivalent to this option in Perl, and no way to set it within a
488  a pattern.  pattern.
489    .sp
490    PCRE_DOTALL    PCRE_DOTALL
491    .sp
492  If this bit is set, a dot metacharater in the pattern matches all characters,  If this bit is set, a dot metacharater in the pattern matches all characters,
493  including newlines. Without it, newlines are excluded. This option is  including those that indicate newline. Without it, a dot does not match when
494  equivalent to Perl's /s option, and it can be changed within a pattern by a  the current position is at a newline. This option is equivalent to Perl's /s
495  (?s) option setting. A negative class such as [^a] always matches a newline  option, and it can be changed within a pattern by a (?s) option setting. A
496  character, independent of the setting of this option.  negative class such as [^a] always matches newline characters, independent of
497    the setting of this option.
498    .sp
499      PCRE_DUPNAMES
500    .sp
501    If this bit is set, names used to identify capturing subpatterns need not be
502    unique. This can be helpful for certain types of pattern when it is known that
503    only one instance of the named subpattern can ever be matched. There are more
504    details of named subpatterns below; see also the
505    .\" HREF
506    \fBpcrepattern\fP
507    .\"
508    documentation.
509    .sp
510    PCRE_EXTENDED    PCRE_EXTENDED
511    .sp
512  If this bit is set, whitespace data characters in the pattern are totally  If this bit is set, whitespace data characters in the pattern are totally
513  ignored except when escaped or inside a character class. Whitespace does not  ignored except when escaped or inside a character class. Whitespace does not
514  include the VT character (code 11). In addition, characters between an  include the VT character (code 11). In addition, characters between an
515  unescaped # outside a character class and the next newline character,  unescaped # outside a character class and the next newline, inclusive, are also
516  inclusive, are also ignored. This is equivalent to Perl's /x option, and it can  ignored. This is equivalent to Perl's /x option, and it can be changed within a
517  be changed within a pattern by a (?x) option setting.  pattern by a (?x) option setting.
518    .P
519  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
520  Note, however, that this applies only to data characters. Whitespace characters  Note, however, that this applies only to data characters. Whitespace characters
521  may never appear within special character sequences in a pattern, for example  may never appear within special character sequences in a pattern, for example
522  within the sequence (?( which introduces a conditional subpattern.  within the sequence (?( which introduces a conditional subpattern.
523    .sp
524    PCRE_EXTRA    PCRE_EXTRA
525    .sp
526  This option was invented in order to turn on additional functionality of PCRE  This option was invented in order to turn on additional functionality of PCRE
527  that is incompatible with Perl, but it is currently of very little use. When  that is incompatible with Perl, but it is currently of very little use. When
528  set, any backslash in a pattern that is followed by a letter that has no  set, any backslash in a pattern that is followed by a letter that has no
529  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
530  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
531  special meaning is treated as a literal. There are at present no other features  special meaning is treated as a literal. (Perl can, however, be persuaded to
532  controlled by this option. It can also be set by a (?X) option setting within a  give a warning for this.) There are at present no other features controlled by
533  pattern.  this option. It can also be set by a (?X) option setting within a pattern.
534    .sp
535      PCRE_FIRSTLINE
536    .sp
537    If this option is set, an unanchored pattern is required to match before or at
538    the first newline in the subject string, though the matched text may continue
539    over the newline.
540    .sp
541    PCRE_MULTILINE    PCRE_MULTILINE
542    .sp
543  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
544  characters (even if it actually contains several newlines). The "start of line"  characters (even if it actually contains newlines). The "start of line"
545  metacharacter (^) matches only at the start of the string, while the "end of  metacharacter (^) matches only at the start of the string, while the "end of
546  line" metacharacter ($) matches only at the end of the string, or before a  line" metacharacter ($) matches only at the end of the string, or before a
547  terminating newline (unless PCRE_DOLLAR_ENDONLY is set). This is the same as  terminating newline (unless PCRE_DOLLAR_ENDONLY is set). This is the same as
548  Perl.  Perl.
549    .P
550  When PCRE_MULTILINE it is set, the "start of line" and "end of line" constructs  When PCRE_MULTILINE it is set, the "start of line" and "end of line" constructs
551  match immediately following or immediately before any newline in the subject  match immediately following or immediately before internal newlines in the
552  string, respectively, as well as at the very start and end. This is equivalent  subject string, respectively, as well as at the very start and end. This is
553  to Perl's /m option, and it can be changed within a pattern by a (?m) option  equivalent to Perl's /m option, and it can be changed within a pattern by a
554  setting. If there are no "\\n" characters in a subject string, or no  (?m) option setting. If there are no newlines in a subject string, or no
555  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.
556    .sp
557      PCRE_NEWLINE_CR
558      PCRE_NEWLINE_LF
559      PCRE_NEWLINE_CRLF
560      PCRE_NEWLINE_ANY
561    .sp
562    These options override the default newline definition that was chosen when PCRE
563    was built. Setting the first or the second specifies that a newline is
564    indicated by a single character (CR or LF, respectively). Setting
565    PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
566    CRLF sequence. Setting PCRE_NEWLINE_ANY specifies that any Unicode newline
567    sequence should be recognized. The Unicode newline sequences are the three just
568    mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed,
569    U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
570    (paragraph separator, U+2029). The last two are recognized only in UTF-8 mode.
571    .P
572    The newline setting in the options word uses three bits that are treated
573    as a number, giving eight possibilities. Currently only five are used (default
574    plus the four values above). This means that if you set more than one newline
575    option, the combination may or may not be sensible. For example,
576    PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
577    other combinations yield unused numbers and cause an error.
578    .P
579    The only time that a line break is specially recognized when compiling a
580    pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character
581    class is encountered. This indicates a comment that lasts until after the next
582    line break sequence. In other circumstances, line break sequences are treated
583    as literal data, except that in PCRE_EXTENDED mode, both CR and LF are treated
584    as whitespace characters and are therefore ignored.
585    .P
586    The newline option that is set at compile time becomes the default that is used
587    for \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, but it can be overridden.
588    .sp
589    PCRE_NO_AUTO_CAPTURE    PCRE_NO_AUTO_CAPTURE
590    .sp
591  If this option is set, it disables the use of numbered capturing parentheses in  If this option is set, it disables the use of numbered capturing parentheses in
592  the pattern. Any opening parenthesis that is not followed by ? behaves as if it  the pattern. Any opening parenthesis that is not followed by ? behaves as if it
593  were followed by ?: but named parentheses can still be used for capturing (and  were followed by ?: but named parentheses can still be used for capturing (and
594  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
595  in Perl.  in Perl.
596    .sp
597    PCRE_UNGREEDY    PCRE_UNGREEDY
598    .sp
599  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
600  greedy by default, but become greedy if followed by "?". It is not compatible  greedy by default, but become greedy if followed by "?". It is not compatible
601  with Perl. It can also be set by a (?U) option setting within the pattern.  with Perl. It can also be set by a (?U) option setting within the pattern.
602    .sp
603    PCRE_UTF8    PCRE_UTF8
604    .sp
605  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
606  of UTF-8 characters instead of single-byte character strings. However, it is  of UTF-8 characters instead of single-byte character strings. However, it is
607  available only if PCRE has been built to include UTF-8 support. If not, the use  available only when PCRE is built to include UTF-8 support. If not, the use
608  of this option provokes an error. Details of how this option changes the  of this option provokes an error. Details of how this option changes the
609  behaviour of PCRE are given in the  behaviour of PCRE are given in the
610  .\" HTML <a href="pcre.html#utf8support">  .\" HTML <a href="pcre.html#utf8support">
# Line 367  section on UTF-8 support Line 613  section on UTF-8 support
613  .\"  .\"
614  in the main  in the main
615  .\" HREF  .\" HREF
616  \fBpcre\fR  \fBpcre\fP
617  .\"  .\"
618  page.  page.
619    .sp
620    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
621    .sp
622  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 string is
623  automatically checked. If an invalid UTF-8 sequence of bytes is found,  automatically checked. If an invalid UTF-8 sequence of bytes is found,
624  \fBpcre_compile()\fR returns an error. If you already know that your pattern is  \fBpcre_compile()\fP returns an error. If you already know that your pattern is
625  valid, and you want to skip this check for performance reasons, you can set the  valid, and you want to skip this check for performance reasons, you can set the
626  PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid  PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid
627  UTF-8 string as a pattern is undefined. It may cause your program to crash.  UTF-8 string as a pattern is undefined. It may cause your program to crash.
628  Note that there is a similar option for suppressing the checking of subject  Note that this option can also be passed to \fBpcre_exec()\fP and
629  strings passed to \fBpcre_exec()\fR.  \fBpcre_dfa_exec()\fP, to suppress the UTF-8 validity checking of subject
630    strings.
631    .
632  .SH STUDYING A PATTERN  .
633  .rs  .SH "COMPILATION ERROR CODES"
634  .sp  .rs
635  .B pcre_extra *pcre_study(const pcre *\fIcode\fR, int \fIoptions\fR,  .sp
636  .ti +5n  The following table lists the error codes than may be returned by
637  .B const char **\fIerrptr\fR);  \fBpcre_compile2()\fP, along with the error messages that may be returned by
638  .PP  both compiling functions. As PCRE has developed, some error codes have fallen
639  When a pattern is going to be used several times, it is worth spending more  out of use. To avoid confusion, they have not been re-used.
640  time analyzing it in order to speed up the time taken for matching. The  .sp
641  function \fBpcre_study()\fR takes a pointer to a compiled pattern as its first     0  no error
642  argument. If studing the pattern produces additional information that will help     1  \e at end of pattern
643  speed up matching, \fBpcre_study()\fR returns a pointer to a \fBpcre_extra\fR     2  \ec at end of pattern
644  block, in which the \fIstudy_data\fR field points to the results of the study.     3  unrecognized character follows \e
645       4  numbers out of order in {} quantifier
646  The returned value from a \fBpcre_study()\fR can be passed directly to     5  number too big in {} quantifier
647  \fBpcre_exec()\fR. However, the \fBpcre_extra\fR block also contains other     6  missing terminating ] for character class
648       7  invalid escape sequence in character class
649       8  range out of order in character class
650       9  nothing to repeat
651      10  [this code is not in use]
652      11  internal error: unexpected repeat
653      12  unrecognized character after (?
654      13  POSIX named classes are supported only within a class
655      14  missing )
656      15  reference to non-existent subpattern
657      16  erroffset passed as NULL
658      17  unknown option bit(s) set
659      18  missing ) after comment
660      19  [this code is not in use]
661      20  regular expression too large
662      21  failed to get memory
663      22  unmatched parentheses
664      23  internal error: code overflow
665      24  unrecognized character after (?<
666      25  lookbehind assertion is not fixed length
667      26  malformed number or name after (?(
668      27  conditional group contains more than two branches
669      28  assertion expected after (?(
670      29  (?R or (?digits must be followed by )
671      30  unknown POSIX class name
672      31  POSIX collating elements are not supported
673      32  this version of PCRE is not compiled with PCRE_UTF8 support
674      33  [this code is not in use]
675      34  character value in \ex{...} sequence is too large
676      35  invalid condition (?(0)
677      36  \eC not allowed in lookbehind assertion
678      37  PCRE does not support \eL, \el, \eN, \eU, or \eu
679      38  number after (?C is > 255
680      39  closing ) for (?C expected
681      40  recursive call could loop indefinitely
682      41  unrecognized character after (?P
683      42  syntax error in subpattern name (missing terminator)
684      43  two named subpatterns have the same name
685      44  invalid UTF-8 string
686      45  support for \eP, \ep, and \eX has not been compiled
687      46  malformed \eP or \ep sequence
688      47  unknown property name after \eP or \ep
689      48  subpattern name is too long (maximum 32 characters)
690      49  too many named subpatterns (maximum 10,000)
691      50  repeated subpattern is too long
692      51  octal value is greater than \e377 (not in UTF-8 mode)
693      52  internal error: overran compiling workspace
694      53  internal error: previously-checked referenced subpattern not found
695      54  DEFINE group contains more than one branch
696      55  repeating a DEFINE group is not allowed
697      56  inconsistent NEWLINE options"
698    .
699    .
700    .SH "STUDYING A PATTERN"
701    .rs
702    .sp
703    .B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP
704    .ti +5n
705    .B const char **\fIerrptr\fP);
706    .PP
707    If a compiled pattern is going to be used several times, it is worth spending
708    more time analyzing it in order to speed up the time taken for matching. The
709    function \fBpcre_study()\fP takes a pointer to a compiled pattern as its first
710    argument. If studying the pattern produces additional information that will
711    help speed up matching, \fBpcre_study()\fP returns a pointer to a
712    \fBpcre_extra\fP block, in which the \fIstudy_data\fP field points to the
713    results of the study.
714    .P
715    The returned value from \fBpcre_study()\fP can be passed directly to
716    \fBpcre_exec()\fP. However, a \fBpcre_extra\fP block also contains other
717  fields that can be set by the caller before the block is passed; these are  fields that can be set by the caller before the block is passed; these are
718  described below. If studying the pattern does not produce any additional  described
719  information, \fBpcre_study()\fR returns NULL. In that circumstance, if the  .\" HTML <a href="#extradata">
720  calling program wants to pass some of the other fields to \fBpcre_exec()\fR, it  .\" </a>
721  must set up its own \fBpcre_extra\fR block.  below
722    .\"
723  The second argument contains option bits. At present, no options are defined  in the section on matching a pattern.
724  for \fBpcre_study()\fR, and this argument should always be zero.  .P
725    If studying the pattern does not produce any additional information
726  The third argument for \fBpcre_study()\fR is a pointer for an error message. If  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program
727    wants to pass any of the other fields to \fBpcre_exec()\fP, it must set up its
728    own \fBpcre_extra\fP block.
729    .P
730    The second argument of \fBpcre_study()\fP contains option bits. At present, no
731    options are defined, and this argument should always be zero.
732    .P
733    The third argument for \fBpcre_study()\fP is a pointer for an error message. If
734  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
735  set to NULL. Otherwise it points to a textual error message. You should  set to NULL. Otherwise it is set to point to a textual error message. This is a
736  therefore test the error pointer for NULL after calling \fBpcre_study()\fR, to  static string that is part of the library. You must not try to free it. You
737  be sure that it has run successfully.  should test the error pointer for NULL after calling \fBpcre_study()\fP, to be
738    sure that it has run successfully.
739  This is a typical call to \fBpcre_study\fR():  .P
740    This is a typical call to \fBpcre_study\fP():
741    .sp
742    pcre_extra *pe;    pcre_extra *pe;
743    pe = pcre_study(    pe = pcre_study(
744      re,             /* result of pcre_compile() */      re,             /* result of pcre_compile() */
745      0,              /* no options exist */      0,              /* no options exist */
746      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
747    .sp
748  At present, studying a pattern is useful only for non-anchored patterns that do  At present, studying a pattern is useful only for non-anchored patterns that do
749  not have a single fixed starting character. A bitmap of possible starting  not have a single fixed starting character. A bitmap of possible starting
750  characters is created.  bytes is created.
751    .
752    .
753  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
754  .SH LOCALE SUPPORT  .SH "LOCALE SUPPORT"
755  .rs  .rs
756  .sp  .sp
757  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters
758  digits, or whatever, by reference to a set of tables. When running in UTF-8  digits, or whatever, by reference to a set of tables, indexed by character
759  mode, this applies only to characters with codes less than 256. The library  value. When running in UTF-8 mode, this applies only to characters with codes
760  contains a default set of tables that is created in the default C locale when  less than 128. Higher-valued codes never match escapes such as \ew or \ed, but
761  PCRE is compiled. This is used when the final argument of \fBpcre_compile()\fR  can be tested with \ep if PCRE is built with Unicode character property
762  is NULL, and is sufficient for many applications.  support. The use of locales with Unicode is discouraged.
763    .P
764  An alternative set of tables can, however, be supplied. Such tables are built  An internal set of tables is created in the default C locale when PCRE is
765  by calling the \fBpcre_maketables()\fR function, which has no arguments, in the  built. This is used when the final argument of \fBpcre_compile()\fP is NULL,
766  relevant locale. The result can then be passed to \fBpcre_compile()\fR as often  and is sufficient for many applications. An alternative set of tables can,
767  as necessary. For example, to build and use tables that are appropriate for the  however, be supplied. These may be created in a different locale from the
768  French locale (where accented characters with codes greater than 128 are  default. As more and more applications change to using Unicode, the need for
769  treated as letters), the following code could be used:  this locale support is expected to die away.
770    .P
771    setlocale(LC_CTYPE, "fr");  External tables are built by calling the \fBpcre_maketables()\fP function,
772    which has no arguments, in the relevant locale. The result can then be passed
773    to \fBpcre_compile()\fP or \fBpcre_exec()\fP as often as necessary. For
774    example, to build and use tables that are appropriate for the French locale
775    (where accented characters with values greater than 128 are treated as letters),
776    the following code could be used:
777    .sp
778      setlocale(LC_CTYPE, "fr_FR");
779    tables = pcre_maketables();    tables = pcre_maketables();
780    re = pcre_compile(..., tables);    re = pcre_compile(..., tables);
781    .sp
782  The tables are built in memory that is obtained via \fBpcre_malloc\fR. The  When \fBpcre_maketables()\fP runs, the tables are built in memory that is
783  pointer that is passed to \fBpcre_compile\fR is saved with the compiled  obtained via \fBpcre_malloc\fP. It is the caller's responsibility to ensure
784  pattern, and the same tables are used via this pointer by \fBpcre_study()\fR  that the memory containing the tables remains available for as long as it is
785  and \fBpcre_exec()\fR. Thus, for any single pattern, compilation, studying and  needed.
786  matching all happen in the same locale, but different patterns can be compiled  .P
787  in different locales. It is the caller's responsibility to ensure that the  The pointer that is passed to \fBpcre_compile()\fP is saved with the compiled
788  memory containing the tables remains available for as long as it is needed.  pattern, and the same tables are used via this pointer by \fBpcre_study()\fP
789    and normally also by \fBpcre_exec()\fP. Thus, by default, for any single
790  .SH INFORMATION ABOUT A PATTERN  pattern, compilation, studying and matching all happen in the same locale, but
791    different patterns can be compiled in different locales.
792    .P
793    It is possible to pass a table pointer or NULL (indicating the use of the
794    internal tables) to \fBpcre_exec()\fP. Although not intended for this purpose,
795    this facility could be used to match a pattern in a different locale from the
796    one in which it was compiled. Passing table pointers at run time is discussed
797    below in the section on matching a pattern.
798    .
799    .
800    .SH "INFORMATION ABOUT A PATTERN"
801  .rs  .rs
802  .sp  .sp
803  .B int pcre_fullinfo(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"  .B int pcre_fullinfo(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
804  .ti +5n  .ti +5n
805  .B int \fIwhat\fR, void *\fIwhere\fR);  .B int \fIwhat\fP, void *\fIwhere\fP);
806  .PP  .PP
807  The \fBpcre_fullinfo()\fR function returns information about a compiled  The \fBpcre_fullinfo()\fP function returns information about a compiled
808  pattern. It replaces the obsolete \fBpcre_info()\fR function, which is  pattern. It replaces the obsolete \fBpcre_info()\fP function, which is
809  nevertheless retained for backwards compability (and is documented below).  nevertheless retained for backwards compability (and is documented below).
810    .P
811  The first argument for \fBpcre_fullinfo()\fR is a pointer to the compiled  The first argument for \fBpcre_fullinfo()\fP is a pointer to the compiled
812  pattern. The second argument is the result of \fBpcre_study()\fR, or NULL if  pattern. The second argument is the result of \fBpcre_study()\fP, or NULL if
813  the pattern was not studied. The third argument specifies which piece of  the pattern was not studied. The third argument specifies which piece of
814  information is required, and the fourth argument is a pointer to a variable  information is required, and the fourth argument is a pointer to a variable
815  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
816  the following negative numbers:  the following negative numbers:
817    .sp
818    PCRE_ERROR_NULL       the argument \fIcode\fR was NULL    PCRE_ERROR_NULL       the argument \fIcode\fP was NULL
819                          the argument \fIwhere\fR was NULL                          the argument \fIwhere\fP was NULL
820    PCRE_ERROR_BADMAGIC   the "magic number" was not found    PCRE_ERROR_BADMAGIC   the "magic number" was not found
821    PCRE_ERROR_BADOPTION  the value of \fIwhat\fR was invalid    PCRE_ERROR_BADOPTION  the value of \fIwhat\fP was invalid
822    .sp
823  Here is a typical call of \fBpcre_fullinfo()\fR, to obtain the length of the  The "magic number" is placed at the start of each compiled pattern as an simple
824  compiled pattern:  check against passing an arbitrary memory pointer. Here is a typical call of
825    \fBpcre_fullinfo()\fP, to obtain the length of the compiled pattern:
826    .sp
827    int rc;    int rc;
828    unsigned long int length;    size_t length;
829    rc = pcre_fullinfo(    rc = pcre_fullinfo(
830      re,               /* result of pcre_compile() */      re,               /* result of pcre_compile() */
831      pe,               /* result of pcre_study(), or NULL */      pe,               /* result of pcre_study(), or NULL */
832      PCRE_INFO_SIZE,   /* what is required */      PCRE_INFO_SIZE,   /* what is required */
833      &length);         /* where to put the data */      &length);         /* where to put the data */
834    .sp
835  The possible values for the third argument are defined in \fBpcre.h\fR, and are  The possible values for the third argument are defined in \fBpcre.h\fP, and are
836  as follows:  as follows:
837    .sp
838    PCRE_INFO_BACKREFMAX    PCRE_INFO_BACKREFMAX
839    .sp
840  Return the number of the highest back reference in the pattern. The fourth  Return the number of the highest back reference in the pattern. The fourth
841  argument should point to an \fBint\fR variable. Zero is returned if there are  argument should point to an \fBint\fP variable. Zero is returned if there are
842  no back references.  no back references.
843    .sp
844    PCRE_INFO_CAPTURECOUNT    PCRE_INFO_CAPTURECOUNT
845    .sp
846  Return the number of capturing subpatterns in the pattern. The fourth argument  Return the number of capturing subpatterns in the pattern. The fourth argument
847  should point to an \fbint\fR variable.  should point to an \fBint\fP variable.
848    .sp
849      PCRE_INFO_DEFAULT_TABLES
850    .sp
851    Return a pointer to the internal default character tables within PCRE. The
852    fourth argument should point to an \fBunsigned char *\fP variable. This
853    information call is provided for internal use by the \fBpcre_study()\fP
854    function. External callers can cause PCRE to use its internal tables by passing
855    a NULL table pointer.
856    .sp
857    PCRE_INFO_FIRSTBYTE    PCRE_INFO_FIRSTBYTE
858    .sp
859  Return information about the first byte of any matched string, for a  Return information about the first byte of any matched string, for a
860  non-anchored pattern. (This option used to be called PCRE_INFO_FIRSTCHAR; the  non-anchored pattern. The fourth argument should point to an \fBint\fP
861  old name is still recognized for backwards compatibility.)  variable. (This option used to be called PCRE_INFO_FIRSTCHAR; the old name is
862    still recognized for backwards compatibility.)
863  If there is a fixed first byte, e.g. from a pattern such as (cat|cow|coyote),  .P
864  it is returned in the integer pointed to by \fIwhere\fR. Otherwise, if either  If there is a fixed first byte, for example, from a pattern such as
865    (cat|cow|coyote), its value is returned. Otherwise, if either
866    .sp
867  (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
868  starts with "^", or  starts with "^", or
869    .sp
870  (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set  (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set
871  (if it were set, the pattern would be anchored),  (if it were set, the pattern would be anchored),
872    .sp
873  -1 is returned, indicating that the pattern matches only at the start of a  -1 is returned, indicating that the pattern matches only at the start of a
874  subject string or after any newline within the string. Otherwise -2 is  subject string or after any newline within the string. Otherwise -2 is
875  returned. For anchored patterns, -2 is returned.  returned. For anchored patterns, -2 is returned.
876    .sp
877    PCRE_INFO_FIRSTTABLE    PCRE_INFO_FIRSTTABLE
878    .sp
879  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
880  table indicating a fixed set of bytes for the first byte in any matching  table indicating a fixed set of bytes for the first byte in any matching
881  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
882  fourth argument should point to an \fBunsigned char *\fR variable.  fourth argument should point to an \fBunsigned char *\fP variable.
883    .sp
884    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
885    .sp
886  Return the value of the rightmost literal byte that must exist in any matched  Return the value of the rightmost literal byte that must exist in any matched
887  string, other than at its start, if such a byte has been recorded. The fourth  string, other than at its start, if such a byte has been recorded. The fourth
888  argument should point to an \fBint\fR variable. If there is no such byte, -1 is  argument should point to an \fBint\fP variable. If there is no such byte, -1 is
889  returned. For anchored patterns, a last literal byte is recorded only if it  returned. For anchored patterns, a last literal byte is recorded only if it
890  follows something of variable length. For example, for the pattern  follows something of variable length. For example, for the pattern
891  /^a\\d+z\\d+/ the returned value is "z", but for /^a\\dz\\d/ the returned value  /^a\ed+z\ed+/ the returned value is "z", but for /^a\edz\ed/ the returned value
892  is -1.  is -1.
893    .sp
894    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
895    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
896    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
897    .sp
898  PCRE supports the use of named as well as numbered capturing parentheses. The  PCRE supports the use of named as well as numbered capturing parentheses. The
899  names are just an additional way of identifying the parentheses, which still  names are just an additional way of identifying the parentheses, which still
900  acquire a number. A caller that wants to extract data from a named subpattern  acquire numbers. Several convenience functions such as
901  must convert the name to a number in order to access the correct pointers in  \fBpcre_get_named_substring()\fP are provided for extracting captured
902  the output vector (described with \fBpcre_exec()\fR below). In order to do  substrings by name. It is also possible to extract the data directly, by first
903  this, it must first use these three values to obtain the name-to-number mapping  converting the name to a number in order to access the correct pointers in the
904  table for the pattern.  output vector (described with \fBpcre_exec()\fP below). To do the conversion,
905    you need to use the name-to-number map, which is described by these three
906    values.
907    .P
908  The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT gives  The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT gives
909  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
910  entry; both of these return an \fBint\fR value. The entry size depends on the  entry; both of these return an \fBint\fP value. The entry size depends on the
911  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
912  entry of the table (a pointer to \fBchar\fR). The first two bytes of each entry  entry of the table (a pointer to \fBchar\fP). The first two bytes of each entry
913  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
914  rest of the entry is the corresponding name, zero terminated. The names are in  rest of the entry is the corresponding name, zero terminated. The names are in
915  alphabetical order. For example, consider the following pattern (assume  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of
916    their parentheses numbers. For example, consider the following pattern (assume
917  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  PCRE_EXTENDED is set, so white space - including newlines - is ignored):
918    .sp
919    (?P<date> (?P<year>(\\d\\d)?\\d\\d) -  .\" JOIN
920    (?P<month>\\d\\d) - (?P<day>\\d\\d) )    (?<date> (?<year>(\ed\ed)?\ed\ed) -
921      (?<month>\ed\ed) - (?<day>\ed\ed) )
922    .sp
923  There are four named subpatterns, so the table has four entries, and each entry  There are four named subpatterns, so the table has four entries, and each entry
924  in the table is eight bytes long. The table is as follows, with non-printing  in the table is eight bytes long. The table is as follows, with non-printing
925  bytes shows in hex, and undefined bytes shown as ??:  bytes shows in hexadecimal, and undefined bytes shown as ??:
926    .sp
927    00 01 d  a  t  e  00 ??    00 01 d  a  t  e  00 ??
928    00 05 d  a  y  00 ?? ??    00 05 d  a  y  00 ?? ??
929    00 04 m  o  n  t  h  00    00 04 m  o  n  t  h  00
930    00 02 y  e  a  r  00 ??    00 02 y  e  a  r  00 ??
931    .sp
932  When writing code to extract data from named subpatterns, remember that the  When writing code to extract data from named subpatterns using the
933  length of each entry may be different for each compiled pattern.  name-to-number map, remember that the length of the entries is likely to be
934    different for each compiled pattern.
935    .sp
936    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
937    .sp
938  Return a copy of the options with which the pattern was compiled. The fourth  Return a copy of the options with which the pattern was compiled. The fourth
939  argument should point to an \fBunsigned long int\fR variable. These option bits  argument should point to an \fBunsigned long int\fP variable. These option bits
940  are those specified in the call to \fBpcre_compile()\fR, modified by any  are those specified in the call to \fBpcre_compile()\fP, modified by any
941  top-level option settings within the pattern itself.  top-level option settings within the pattern itself.
942    .P
943  A pattern is automatically anchored by PCRE if all of its top-level  A pattern is automatically anchored by PCRE if all of its top-level
944  alternatives begin with one of the following:  alternatives begin with one of the following:
945    .sp
946    ^     unless PCRE_MULTILINE is set    ^     unless PCRE_MULTILINE is set
947    \\A    always    \eA    always
948    \\G    always    \eG    always
949    .\" JOIN
950    .*    if PCRE_DOTALL is set and there are no back    .*    if PCRE_DOTALL is set and there are no back
951            references to the subpattern in which .* appears            references to the subpattern in which .* appears
952    .sp
953  For such patterns, the PCRE_ANCHORED bit is set in the options returned by  For such patterns, the PCRE_ANCHORED bit is set in the options returned by
954  \fBpcre_fullinfo()\fR.  \fBpcre_fullinfo()\fP.
955    .sp
956    PCRE_INFO_SIZE    PCRE_INFO_SIZE
957    .sp
958  Return the size of the compiled pattern, that is, the value that was passed as  Return the size of the compiled pattern, that is, the value that was passed as
959  the argument to \fBpcre_malloc()\fR when PCRE was getting memory in which to  the argument to \fBpcre_malloc()\fP when PCRE was getting memory in which to
960  place the compiled data. The fourth argument should point to a \fBsize_t\fR  place the compiled data. The fourth argument should point to a \fBsize_t\fP
961  variable.  variable.
962    .sp
963    PCRE_INFO_STUDYSIZE    PCRE_INFO_STUDYSIZE
964    .sp
965  Returns the size of the data block pointed to by the \fIstudy_data\fR field in  Return the size of the data block pointed to by the \fIstudy_data\fP field in
966  a \fBpcre_extra\fR block. That is, it is the value that was passed to  a \fBpcre_extra\fP block. That is, it is the value that was passed to
967  \fBpcre_malloc()\fR when PCRE was getting memory into which to place the data  \fBpcre_malloc()\fP when PCRE was getting memory into which to place the data
968  created by \fBpcre_study()\fR. The fourth argument should point to a  created by \fBpcre_study()\fP. The fourth argument should point to a
969  \fBsize_t\fR variable.  \fBsize_t\fP variable.
970    .
971  .SH OBSOLETE INFO FUNCTION  .
972    .SH "OBSOLETE INFO FUNCTION"
973  .rs  .rs
974  .sp  .sp
975  .B int pcre_info(const pcre *\fIcode\fR, int *\fIoptptr\fR, int  .B int pcre_info(const pcre *\fIcode\fP, int *\fIoptptr\fP, int
976  .B *\fIfirstcharptr\fR);  .B *\fIfirstcharptr\fP);
977  .PP  .PP
978  The \fBpcre_info()\fR function is now obsolete because its interface is too  The \fBpcre_info()\fP function is now obsolete because its interface is too
979  restrictive to return all the available data about a compiled pattern. New  restrictive to return all the available data about a compiled pattern. New
980  programs should use \fBpcre_fullinfo()\fR instead. The yield of  programs should use \fBpcre_fullinfo()\fP instead. The yield of
981  \fBpcre_info()\fR is the number of capturing subpatterns, or one of the  \fBpcre_info()\fP is the number of capturing subpatterns, or one of the
982  following negative numbers:  following negative numbers:
983    .sp
984    PCRE_ERROR_NULL       the argument \fIcode\fR was NULL    PCRE_ERROR_NULL       the argument \fIcode\fP was NULL
985    PCRE_ERROR_BADMAGIC   the "magic number" was not found    PCRE_ERROR_BADMAGIC   the "magic number" was not found
986    .sp
987  If the \fIoptptr\fR argument is not NULL, a copy of the options with which the  If the \fIoptptr\fP argument is not NULL, a copy of the options with which the
988  pattern was compiled is placed in the integer it points to (see  pattern was compiled is placed in the integer it points to (see
989  PCRE_INFO_OPTIONS above).  PCRE_INFO_OPTIONS above).
990    .P
991  If the pattern is not anchored and the \fIfirstcharptr\fR argument is not NULL,  If the pattern is not anchored and the \fIfirstcharptr\fP argument is not NULL,
992  it is used to pass back information about the first character of any matched  it is used to pass back information about the first character of any matched
993  string (see PCRE_INFO_FIRSTBYTE above).  string (see PCRE_INFO_FIRSTBYTE above).
994    .
995  .SH MATCHING A PATTERN  .
996    .SH "REFERENCE COUNTS"
997    .rs
998    .sp
999    .B int pcre_refcount(pcre *\fIcode\fP, int \fIadjust\fP);
1000    .PP
1001    The \fBpcre_refcount()\fP function is used to maintain a reference count in the
1002    data block that contains a compiled pattern. It is provided for the benefit of
1003    applications that operate in an object-oriented manner, where different parts
1004    of the application may be using the same compiled pattern, but you want to free
1005    the block when they are all done.
1006    .P
1007    When a pattern is compiled, the reference count field is initialized to zero.
1008    It is changed only by calling this function, whose action is to add the
1009    \fIadjust\fP value (which may be positive or negative) to it. The yield of the
1010    function is the new value. However, the value of the count is constrained to
1011    lie between 0 and 65535, inclusive. If the new value is outside these limits,
1012    it is forced to the appropriate limit value.
1013    .P
1014    Except when it is zero, the reference count is not correctly preserved if a
1015    pattern is compiled on one host and then transferred to a host whose byte-order
1016    is different. (This seems a highly unlikely scenario.)
1017    .
1018    .
1019    .SH "MATCHING A PATTERN: THE TRADITIONAL FUNCTION"
1020  .rs  .rs
1021  .sp  .sp
1022  .B int pcre_exec(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"  .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
1023  .ti +5n  .ti +5n
1024  .B "const char *\fIsubject\fR," int \fIlength\fR, int \fIstartoffset\fR,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
1025  .ti +5n  .ti +5n
1026  .B int \fIoptions\fR, int *\fIovector\fR, int \fIovecsize\fR);  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
1027  .PP  .P
1028  The function \fBpcre_exec()\fR is called to match a subject string against a  The function \fBpcre_exec()\fP is called to match a subject string against a
1029  pre-compiled pattern, which is passed in the \fIcode\fR argument. If the  compiled pattern, which is passed in the \fIcode\fP argument. If the
1030  pattern has been studied, the result of the study should be passed in the  pattern has been studied, the result of the study should be passed in the
1031  \fIextra\fR argument.  \fIextra\fP argument. This function is the main matching facility of the
1032    library, and it operates in a Perl-like manner. For specialist use there is
1033  Here is an example of a simple call to \fBpcre_exec()\fR:  also an alternative matching function, which is described
1034    .\" HTML <a href="#dfamatch">
1035    .\" </a>
1036    below
1037    .\"
1038    in the section about the \fBpcre_dfa_exec()\fP function.
1039    .P
1040    In most applications, the pattern will have been compiled (and optionally
1041    studied) in the same process that calls \fBpcre_exec()\fP. However, it is
1042    possible to save compiled patterns and study data, and then use them later
1043    in different processes, possibly even on different hosts. For a discussion
1044    about this, see the
1045    .\" HREF
1046    \fBpcreprecompile\fP
1047    .\"
1048    documentation.
1049    .P
1050    Here is an example of a simple call to \fBpcre_exec()\fP:
1051    .sp
1052    int rc;    int rc;
1053    int ovector[30];    int ovector[30];
1054    rc = pcre_exec(    rc = pcre_exec(
# Line 659  Here is an example of a simple call to \ Line 1058  Here is an example of a simple call to \
1058      11,             /* the length of the subject string */      11,             /* the length of the subject string */
1059      0,              /* start at offset 0 in the subject */      0,              /* start at offset 0 in the subject */
1060      0,              /* default options */      0,              /* default options */
1061      ovector,        /* vector for substring information */      ovector,        /* vector of integers for substring information */
1062      30);            /* number of elements in the vector */      30);            /* number of elements (NOT size in bytes) */
1063    .
1064  If the \fIextra\fR argument is not NULL, it must point to a \fBpcre_extra\fR  .\" HTML <a name="extradata"></a>
1065  data block. The \fBpcre_study()\fR function returns such a block (when it  .SS "Extra data for \fBpcre_exec()\fR"
1066    .rs
1067    .sp
1068    If the \fIextra\fP argument is not NULL, it must point to a \fBpcre_extra\fP
1069    data block. The \fBpcre_study()\fP function returns such a block (when it
1070  doesn't return NULL), but you can also create one for yourself, and pass  doesn't return NULL), but you can also create one for yourself, and pass
1071  additional information in it. The fields in the block are as follows:  additional information in it. The \fBpcre_extra\fP block contains the following
1072    fields (not necessarily in this order):
1073    unsigned long int \fIflags\fR;  .sp
1074    void *\fIstudy_data\fR;    unsigned long int \fIflags\fP;
1075    unsigned long int \fImatch_limit\fR;    void *\fIstudy_data\fP;
1076    void *\fIcallout_data\fR;    unsigned long int \fImatch_limit\fP;
1077      unsigned long int \fImatch_limit_recursion\fP;
1078  The \fIflags\fR field is a bitmap that specifies which of the other fields    void *\fIcallout_data\fP;
1079      const unsigned char *\fItables\fP;
1080    .sp
1081    The \fIflags\fP field is a bitmap that specifies which of the other fields
1082  are set. The flag bits are:  are set. The flag bits are:
1083    .sp
1084    PCRE_EXTRA_STUDY_DATA    PCRE_EXTRA_STUDY_DATA
1085    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1086      PCRE_EXTRA_MATCH_LIMIT_RECURSION
1087    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1088      PCRE_EXTRA_TABLES
1089  Other flag bits should be set to zero. The \fIstudy_data\fR field is set in the  .sp
1090  \fBpcre_extra\fR block that is returned by \fBpcre_study()\fR, together with  Other flag bits should be set to zero. The \fIstudy_data\fP field is set in the
1091  the appropriate flag bit. You should not set this yourself, but you can add to  \fBpcre_extra\fP block that is returned by \fBpcre_study()\fP, together with
1092  the block by setting the other fields.  the appropriate flag bit. You should not set this yourself, but you may add to
1093    the block by setting the other fields and their corresponding flag bits.
1094  The \fImatch_limit\fR field provides a means of preventing PCRE from using up a  .P
1095    The \fImatch_limit\fP field provides a means of preventing PCRE from using up a
1096  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,
1097  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
1098  classic example is the use of nested unlimited repeats. Internally, PCRE uses a  classic example is the use of nested unlimited repeats.
1099  function called \fBmatch()\fR which it calls repeatedly (sometimes  .P
1100  recursively). The limit is imposed on the number of times this function is  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly
1101  called during a match, which has the effect of limiting the amount of recursion  (sometimes recursively). The limit set by \fImatch_limit\fP is imposed on the
1102  and backtracking that can take place. For patterns that are not anchored, the  number of times this function is called during a match, which has the effect of
1103  count starts from zero for each position in the subject string.  limiting the amount of backtracking that can take place. For patterns that are
1104    not anchored, the count restarts from zero for each position in the subject
1105  The default limit for the library can be set when PCRE is built; the default  string.
1106    .P
1107    The default value for the limit can be set when PCRE is built; the default
1108  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
1109  reduce the default by suppling \fBpcre_exec()\fR with a \fRpcre_extra\fR block  override the default by suppling \fBpcre_exec()\fP with a \fBpcre_extra\fP
1110  in which \fImatch_limit\fR is set to a smaller value, and  block in which \fImatch_limit\fP is set, and PCRE_EXTRA_MATCH_LIMIT is set in
1111  PCRE_EXTRA_MATCH_LIMIT is set in the \fIflags\fR field. If the limit is  the \fIflags\fP field. If the limit is exceeded, \fBpcre_exec()\fP returns
1112  exceeded, \fBpcre_exec()\fR returns PCRE_ERROR_MATCHLIMIT.  PCRE_ERROR_MATCHLIMIT.
1113    .P
1114  The \fIpcre_callout\fR field is used in conjunction with the "callout" feature,  The \fImatch_limit_recursion\fP field is similar to \fImatch_limit\fP, but
1115  which is described in the \fBpcrecallout\fR documentation.  instead of limiting the total number of times that \fBmatch()\fP is called, it
1116    limits the depth of recursion. The recursion depth is a smaller number than the
1117  The PCRE_ANCHORED option can be passed in the \fIoptions\fR argument, whose  total number of calls, because not all calls to \fBmatch()\fP are recursive.
1118  unused bits must be zero. This limits \fBpcre_exec()\fR to matching at the  This limit is of use only if it is set smaller than \fImatch_limit\fP.
1119  first matching position. However, if a pattern was compiled with PCRE_ANCHORED,  .P
1120  or turned out to be anchored by virtue of its contents, it cannot be made  Limiting the recursion depth limits the amount of stack that can be used, or,
1121  unachored at matching time.  when PCRE has been compiled to use memory on the heap instead of the stack, the
1122    amount of heap memory that can be used.
1123  When PCRE_UTF8 was set at compile time, the validity of the subject as a UTF-8  .P
1124  string is automatically checked. If an invalid UTF-8 sequence of bytes is  The default value for \fImatch_limit_recursion\fP can be set when PCRE is
1125  found, \fBpcre_exec()\fR returns the error PCRE_ERROR_BADUTF8. If you already  built; the default default is the same value as the default for
1126  know that your subject is valid, and you want to skip this check for  \fImatch_limit\fP. You can override the default by suppling \fBpcre_exec()\fP
1127  performance reasons, you can set the PCRE_NO_UTF8_CHECK option when calling  with a \fBpcre_extra\fP block in which \fImatch_limit_recursion\fP is set, and
1128  \fBpcre_exec()\fR. When this option is set, the effect of passing an invalid  PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the \fIflags\fP field. If the limit
1129  UTF-8 string as a subject is undefined. It may cause your program to crash.  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1130    .P
1131  There are also three further options that can be set only at matching time:  The \fIpcre_callout\fP field is used in conjunction with the "callout" feature,
1132    which is described in the
1133    .\" HREF
1134    \fBpcrecallout\fP
1135    .\"
1136    documentation.
1137    .P
1138    The \fItables\fP field is used to pass a character tables pointer to
1139    \fBpcre_exec()\fP; this overrides the value that is stored with the compiled
1140    pattern. A non-NULL value is stored with the compiled pattern only if custom
1141    tables were supplied to \fBpcre_compile()\fP via its \fItableptr\fP argument.
1142    If NULL is passed to \fBpcre_exec()\fP using this mechanism, it forces PCRE's
1143    internal tables to be used. This facility is helpful when re-using patterns
1144    that have been saved after compiling with an external set of tables, because
1145    the external tables might be at a different address when \fBpcre_exec()\fP is
1146    called. See the
1147    .\" HREF
1148    \fBpcreprecompile\fP
1149    .\"
1150    documentation for a discussion of saving compiled patterns for later use.
1151    .
1152    .SS "Option bits for \fBpcre_exec()\fP"
1153    .rs
1154    .sp
1155    The unused bits of the \fIoptions\fP argument for \fBpcre_exec()\fP must be
1156    zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
1157    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.
1158    .sp
1159      PCRE_ANCHORED
1160    .sp
1161    The PCRE_ANCHORED option limits \fBpcre_exec()\fP to matching at the first
1162    matching position. If a pattern was compiled with PCRE_ANCHORED, or turned out
1163    to be anchored by virtue of its contents, it cannot be made unachored at
1164    matching time.
1165    .sp
1166      PCRE_NEWLINE_CR
1167      PCRE_NEWLINE_LF
1168      PCRE_NEWLINE_CRLF
1169      PCRE_NEWLINE_ANY
1170    .sp
1171    These options override the newline definition that was chosen or defaulted when
1172    the pattern was compiled. For details, see the description of
1173    \fBpcre_compile()\fP above. During matching, the newline choice affects the
1174    behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1175    the way the match position is advanced after a match failure for an unanchored
1176    pattern. When PCRE_NEWLINE_CRLF or PCRE_NEWLINE_ANY is set, and a match attempt
1177    fails when the current position is at a CRLF sequence, the match position is
1178    advanced by two characters instead of one, in other words, to after the CRLF.
1179    .sp
1180    PCRE_NOTBOL    PCRE_NOTBOL
1181    .sp
1182  The first character of the string is not the beginning of a line, so the  This option specifies that first character of the subject string is not the
1183  circumflex metacharacter should not match before it. Setting this without  beginning of a line, so the circumflex metacharacter should not match before
1184  PCRE_MULTILINE (at compile time) causes circumflex never to match.  it. Setting this without PCRE_MULTILINE (at compile time) causes circumflex
1185    never to match. This option affects only the behaviour of the circumflex
1186    metacharacter. It does not affect \eA.
1187    .sp
1188    PCRE_NOTEOL    PCRE_NOTEOL
1189    .sp
1190  The end of the string is not the end of a line, so the dollar metacharacter  This option specifies that the end of the subject string is not the end of a
1191  should not match it nor (except in multiline mode) a newline immediately before  line, so the dollar metacharacter should not match it nor (except in multiline
1192  it. Setting this without PCRE_MULTILINE (at compile time) causes dollar never  mode) a newline immediately before it. Setting this without PCRE_MULTILINE (at
1193  to match.  compile time) causes dollar never to match. This option affects only the
1194    behaviour of the dollar metacharacter. It does not affect \eZ or \ez.
1195    .sp
1196    PCRE_NOTEMPTY    PCRE_NOTEMPTY
1197    .sp
1198  An empty string is not considered to be a valid match if this option is set. If  An empty string is not considered to be a valid match if this option is set. If
1199  there are alternatives in the pattern, they are tried. If all the alternatives  there are alternatives in the pattern, they are tried. If all the alternatives
1200  match the empty string, the entire match fails. For example, if the pattern  match the empty string, the entire match fails. For example, if the pattern
1201    .sp
1202    a?b?    a?b?
1203    .sp
1204  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 the empty
1205  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
1206  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".
1207    .P
1208  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case
1209  of a pattern match of the empty string within its \fBsplit()\fR function, and  of a pattern match of the empty string within its \fBsplit()\fP function, and
1210  when using the /g modifier. It is possible to emulate Perl's behaviour after  when using the /g modifier. It is possible to emulate Perl's behaviour after
1211  matching a null string by first trying the match again at the same offset with  matching a null string by first trying the match again at the same offset with
1212  PCRE_NOTEMPTY set, and then if that fails by advancing the starting offset (see  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the
1213  below) and trying an ordinary match again.  starting offset (see below) and trying an ordinary match again. There is some
1214    code that demonstrates how to do this in the \fIpcredemo.c\fP sample program.
1215  The subject string is passed to \fBpcre_exec()\fR as a pointer in  .sp
1216  \fIsubject\fR, a length in \fIlength\fR, and a starting offset in    PCRE_NO_UTF8_CHECK
1217  \fIstartoffset\fR. Unlike the pattern string, the subject may contain binary  .sp
1218  zero bytes. When the starting offset is zero, the search for a match starts at  When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8
1219  the beginning of the subject, and this is by far the most common case.  string is automatically checked when \fBpcre_exec()\fP is subsequently called.
1220    The value of \fIstartoffset\fP is also checked to ensure that it points to the
1221  If the pattern was compiled with the PCRE_UTF8 option, the subject must be a  start of a UTF-8 character. If an invalid UTF-8 sequence of bytes is found,
1222  sequence of bytes that is a valid UTF-8 string. If an invalid UTF-8 string is  \fBpcre_exec()\fP returns the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP
1223  passed, PCRE's behaviour is not defined.  contains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.
1224    .P
1225    If you already know that your subject is valid, and you want to skip these
1226    checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when
1227    calling \fBpcre_exec()\fP. You might want to do this for the second and
1228    subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find
1229    all the matches in a single subject string. However, you should be sure that
1230    the value of \fIstartoffset\fP points to the start of a UTF-8 character. When
1231    PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid UTF-8 string as a
1232    subject, or a value of \fIstartoffset\fP that does not point to the start of a
1233    UTF-8 character, is undefined. Your program may crash.
1234    .sp
1235      PCRE_PARTIAL
1236    .sp
1237    This option turns on the partial matching feature. If the subject string fails
1238    to match the pattern, but at some point during the matching process the end of
1239    the subject was reached (that is, the subject partially matches the pattern and
1240    the failure to match occurred only because there were not enough subject
1241    characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of
1242    PCRE_ERROR_NOMATCH. When PCRE_PARTIAL is used, there are restrictions on what
1243    may appear in the pattern. These are discussed in the
1244    .\" HREF
1245    \fBpcrepartial\fP
1246    .\"
1247    documentation.
1248    .
1249    .SS "The string to be matched by \fBpcre_exec()\fP"
1250    .rs
1251    .sp
1252    The subject string is passed to \fBpcre_exec()\fP as a pointer in
1253    \fIsubject\fP, a length in \fIlength\fP, and a starting byte offset in
1254    \fIstartoffset\fP. In UTF-8 mode, the byte offset must point to the start of a
1255    UTF-8 character. Unlike the pattern string, the subject may contain binary zero
1256    bytes. When the starting offset is zero, the search for a match starts at the
1257    beginning of the subject, and this is by far the most common case.
1258    .P
1259  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
1260  same subject by calling \fBpcre_exec()\fR again after a previous success.  same subject by calling \fBpcre_exec()\fP again after a previous success.
1261  Setting \fIstartoffset\fR differs from just passing over a shortened string and  Setting \fIstartoffset\fP differs from just passing over a shortened string and
1262  setting PCRE_NOTBOL in the case of a pattern that begins with any kind of  setting PCRE_NOTBOL in the case of a pattern that begins with any kind of
1263  lookbehind. For example, consider the pattern  lookbehind. For example, consider the pattern
1264    .sp
1265    \\Biss\\B    \eBiss\eB
1266    .sp
1267  which finds occurrences of "iss" in the middle of words. (\\B matches only if  which finds occurrences of "iss" in the middle of words. (\eB matches only if
1268  the current position in the subject is not a word boundary.) When applied to  the current position in the subject is not a word boundary.) When applied to
1269  the string "Mississipi" the first call to \fBpcre_exec()\fR finds the first  the string "Mississipi" the first call to \fBpcre_exec()\fP finds the first
1270  occurrence. If \fBpcre_exec()\fR is called again with just the remainder of the  occurrence. If \fBpcre_exec()\fP is called again with just the remainder of the
1271  subject, namely "issipi", it does not match, because \\B is always false at the  subject, namely "issipi", it does not match, because \eB is always false at the
1272  start of the subject, which is deemed to be a word boundary. However, if  start of the subject, which is deemed to be a word boundary. However, if
1273  \fBpcre_exec()\fR is passed the entire string again, but with \fIstartoffset\fR  \fBpcre_exec()\fP is passed the entire string again, but with \fIstartoffset\fP
1274  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
1275  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.
1276    .P
1277  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
1278  attempt to match at the given offset is tried. This can only succeed if the  attempt to match at the given offset is made. This can only succeed if the
1279  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.
1280    .
1281    .SS "How \fBpcre_exec()\fP returns captured substrings"
1282    .rs
1283    .sp
1284  In general, a pattern matches a certain portion of the subject, and in  In general, a pattern matches a certain portion of the subject, and in
1285  addition, further substrings from the subject may be picked out by parts of the  addition, further substrings from the subject may be picked out by parts of the
1286  pattern. Following the usage in Jeffrey Friedl's book, this is called  pattern. Following the usage in Jeffrey Friedl's book, this is called
1287  "capturing" in what follows, and the phrase "capturing subpattern" is used for  "capturing" in what follows, and the phrase "capturing subpattern" is used for
1288  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
1289  kinds of parenthesized subpattern that do not cause substrings to be captured.  kinds of parenthesized subpattern that do not cause substrings to be captured.
1290    .P
1291  Captured substrings are returned to the caller via a vector of integer offsets  Captured substrings are returned to the caller via a vector of integer offsets
1292  whose address is passed in \fIovector\fR. The number of elements in the vector  whose address is passed in \fIovector\fP. The number of elements in the vector
1293  is passed in \fIovecsize\fR. The first two-thirds of the vector is used to pass  is passed in \fIovecsize\fP, which must be a non-negative number. \fBNote\fP:
1294  back captured substrings, each substring using a pair of integers. The  this argument is NOT the size of \fIovector\fP in bytes.
1295  remaining third of the vector is used as workspace by \fBpcre_exec()\fR while  .P
1296  matching capturing subpatterns, and is not available for passing back  The first two-thirds of the vector is used to pass back captured substrings,
1297  information. The length passed in \fIovecsize\fR should always be a multiple of  each substring using a pair of integers. The remaining third of the vector is
1298  three. If it is not, it is rounded down.  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
1299    and is not available for passing back information. The length passed in
1300  When a match has been successful, information about captured substrings is  \fIovecsize\fP should always be a multiple of three. If it is not, it is
1301  returned in pairs of integers, starting at the beginning of \fIovector\fR, and  rounded down.
1302    .P
1303    When a match is successful, information about captured substrings is returned
1304    in pairs of integers, starting at the beginning of \fIovector\fP, and
1305  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 a
1306  pair is set to the offset of the first character in a substring, and the second  pair is set to the offset of the first character in a substring, and the second
1307  is set to the offset of the first character after the end of a substring. The  is set to the offset of the first character after the end of a substring. The
1308  first pair, \fIovector[0]\fR and \fIovector[1]\fR, identify the portion of the  first pair, \fIovector[0]\fP and \fIovector[1]\fP, identify the portion of the
1309  subject string matched by the entire pattern. The next pair is used for the  subject string matched by the entire pattern. The next pair is used for the
1310  first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fR  first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fP
1311  is the number of pairs that have been set. If there are no capturing  is one more than the highest numbered pair that has been set. For example, if
1312  subpatterns, the return value from a successful match is 1, indicating that  two substrings have been captured, the returned value is 3. If there are no
1313  just the first pair of offsets has been set.  capturing subpatterns, the return value from a successful match is 1,
1314    indicating that just the first pair of offsets has been set.
1315  Some convenience functions are provided for extracting the captured substrings  .P
 as separate strings. These are described in the following section.  
   
 It is possible for an capturing subpattern number \fIn+1\fR to match some  
 part of the subject when subpattern \fIn\fR has not been used at all. For  
 example, if the string "abc" is matched against the pattern (a|(z))(bc)  
 subpatterns 1 and 3 are matched, but 2 is not. When this happens, both offset  
 values corresponding to the unused subpattern are set to -1.  
   
1316  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
1317  string that it matched that gets returned.  string that it matched that is returned.
1318    .P
1319  If the vector is too small to hold all the captured substrings, it is used as  If the vector is too small to hold all the captured substring offsets, it is
1320  far as possible (up to two-thirds of its length), and the function returns a  used as far as possible (up to two-thirds of its length), and the function
1321  value of zero. In particular, if the substring offsets are not of interest,  returns a value of zero. In particular, if the substring offsets are not of
1322  \fBpcre_exec()\fR may be called with \fIovector\fR passed as NULL and  interest, \fBpcre_exec()\fP may be called with \fIovector\fP passed as NULL and
1323  \fIovecsize\fR as zero. However, if the pattern contains back references and  \fIovecsize\fP as zero. However, if the pattern contains back references and
1324  the \fIovector\fR isn't big enough to remember the related substrings, PCRE has  the \fIovector\fP is not big enough to remember the related substrings, PCRE
1325  to get additional memory for use during matching. Thus it is usually advisable  has to get additional memory for use during matching. Thus it is usually
1326  to supply an \fIovector\fR.  advisable to supply an \fIovector\fP.
1327    .P
1328  Note that \fBpcre_info()\fR can be used to find out how many capturing  The \fBpcre_info()\fP function can be used to find out how many capturing
1329  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1330  \fIovector\fR that will allow for \fIn\fR captured substrings, in addition to  \fIovector\fP that will allow for \fIn\fP captured substrings, in addition to
1331  the offsets of the substring matched by the whole pattern, is (\fIn\fR+1)*3.  the offsets of the substring matched by the whole pattern, is (\fIn\fP+1)*3.
1332    .P
1333  If \fBpcre_exec()\fR fails, it returns a negative number. The following are  It is possible for capturing subpattern number \fIn+1\fP to match some part of
1334    the subject when subpattern \fIn\fP has not been used at all. For example, if
1335    the string "abc" is matched against the pattern (a|(z))(bc) the return from the
1336    function is 4, and subpatterns 1 and 3 are matched, but 2 is not. When this
1337    happens, both values in the offset pairs corresponding to unused subpatterns
1338    are set to -1.
1339    .P
1340    Offset values that correspond to unused subpatterns at the end of the
1341    expression are also set to -1. For example, if the string "abc" is matched
1342    against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
1343    return from the function is 2, because the highest used capturing subpattern
1344    number is 1. However, you can refer to the offsets for the second and third
1345    capturing subpatterns if you wish (assuming the vector is large enough, of
1346    course).
1347    .P
1348    Some convenience functions are provided for extracting the captured substrings
1349    as separate strings. These are described below.
1350    .
1351    .\" HTML <a name="errorlist"></a>
1352    .SS "Error return values from \fBpcre_exec()\fP"
1353    .rs
1354    .sp
1355    If \fBpcre_exec()\fP fails, it returns a negative number. The following are
1356  defined in the header file:  defined in the header file:
1357    .sp
1358    PCRE_ERROR_NOMATCH        (-1)    PCRE_ERROR_NOMATCH        (-1)
1359    .sp
1360  The subject string did not match the pattern.  The subject string did not match the pattern.
1361    .sp
1362    PCRE_ERROR_NULL           (-2)    PCRE_ERROR_NULL           (-2)
1363    .sp
1364  Either \fIcode\fR or \fIsubject\fR was passed as NULL, or \fIovector\fR was  Either \fIcode\fP or \fIsubject\fP was passed as NULL, or \fIovector\fP was
1365  NULL and \fIovecsize\fR was not zero.  NULL and \fIovecsize\fP was not zero.
1366    .sp
1367    PCRE_ERROR_BADOPTION      (-3)    PCRE_ERROR_BADOPTION      (-3)
1368    .sp
1369  An unrecognized bit was set in the \fIoptions\fR argument.  An unrecognized bit was set in the \fIoptions\fP argument.
1370    .sp
1371    PCRE_ERROR_BADMAGIC       (-4)    PCRE_ERROR_BADMAGIC       (-4)
1372    .sp
1373  PCRE stores a 4-byte "magic number" at the start of the compiled code, to catch  PCRE stores a 4-byte "magic number" at the start of the compiled code, to catch
1374  the case when it is passed a junk pointer. This is the error it gives when the  the case when it is passed a junk pointer and to detect when a pattern that was
1375  magic number isn't present.  compiled in an environment of one endianness is run in an environment with the
1376    other endianness. This is the error that PCRE gives when the magic number is
1377    PCRE_ERROR_UNKNOWN_NODE   (-5)  not present.
1378    .sp
1379      PCRE_ERROR_UNKNOWN_OPCODE (-5)
1380    .sp
1381  While running the pattern match, an unknown item was encountered in the  While running the pattern match, an unknown item was encountered in the
1382  compiled pattern. This error could be caused by a bug in PCRE or by overwriting  compiled pattern. This error could be caused by a bug in PCRE or by overwriting
1383  of the compiled pattern.  of the compiled pattern.
1384    .sp
1385    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1386    .sp
1387  If a pattern contains back references, but the \fIovector\fR that is passed to  If a pattern contains back references, but the \fIovector\fP that is passed to
1388  \fBpcre_exec()\fR is not big enough to remember the referenced substrings, PCRE  \fBpcre_exec()\fP is not big enough to remember the referenced substrings, PCRE
1389  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
1390  call via \fBpcre_malloc()\fR fails, this error is given. The memory is freed at  call via \fBpcre_malloc()\fP fails, this error is given. The memory is
1391  the end of matching.  automatically freed at the end of matching.
1392    .sp
1393    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1394    .sp
1395  This error is used by the \fBpcre_copy_substring()\fR,  This error is used by the \fBpcre_copy_substring()\fP,
1396  \fBpcre_get_substring()\fR, and \fBpcre_get_substring_list()\fR functions (see  \fBpcre_get_substring()\fP, and \fBpcre_get_substring_list()\fP functions (see
1397  below). It is never returned by \fBpcre_exec()\fR.  below). It is never returned by \fBpcre_exec()\fP.
1398    .sp
1399    PCRE_ERROR_MATCHLIMIT     (-8)    PCRE_ERROR_MATCHLIMIT     (-8)
1400    .sp
1401  The recursion and backtracking limit, as specified by the \fImatch_limit\fR  The backtracking limit, as specified by the \fImatch_limit\fP field in a
1402  field in a \fBpcre_extra\fR structure (or defaulted) was reached. See the  \fBpcre_extra\fP structure (or defaulted) was reached. See the description
1403  description above.  above.
1404    .sp
1405    PCRE_ERROR_CALLOUT        (-9)    PCRE_ERROR_CALLOUT        (-9)
1406    .sp
1407  This error is never generated by \fBpcre_exec()\fR itself. It is provided for  This error is never generated by \fBpcre_exec()\fP itself. It is provided for
1408  use by callout functions that want to yield a distinctive error code. See the  use by callout functions that want to yield a distinctive error code. See the
1409  \fBpcrecallout\fR documentation for details.  .\" HREF
1410    \fBpcrecallout\fP
1411    PCRE_ERROR_BADUTF8       (-10)  .\"
1412    documentation for details.
1413    .sp
1414      PCRE_ERROR_BADUTF8        (-10)
1415    .sp
1416  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.
1417    .sp
1418  .SH EXTRACTING CAPTURED SUBSTRINGS BY NUMBER    PCRE_ERROR_BADUTF8_OFFSET (-11)
1419    .sp
1420    The UTF-8 byte sequence that was passed as a subject was valid, but the value
1421    of \fIstartoffset\fP did not point to the beginning of a UTF-8 character.
1422    .sp
1423      PCRE_ERROR_PARTIAL        (-12)
1424    .sp
1425    The subject string did not match, but it did match partially. See the
1426    .\" HREF
1427    \fBpcrepartial\fP
1428    .\"
1429    documentation for details of partial matching.
1430    .sp
1431      PCRE_ERROR_BADPARTIAL     (-13)
1432    .sp
1433    The PCRE_PARTIAL option was used with a compiled pattern containing items that
1434    are not supported for partial matching. See the
1435    .\" HREF
1436    \fBpcrepartial\fP
1437    .\"
1438    documentation for details of partial matching.
1439    .sp
1440      PCRE_ERROR_INTERNAL       (-14)
1441    .sp
1442    An unexpected internal error has occurred. This error could be caused by a bug
1443    in PCRE or by overwriting of the compiled pattern.
1444    .sp
1445      PCRE_ERROR_BADCOUNT       (-15)
1446    .sp
1447    This error is given if the value of the \fIovecsize\fP argument is negative.
1448    .sp
1449      PCRE_ERROR_RECURSIONLIMIT (-21)
1450    .sp
1451    The internal recursion limit, as specified by the \fImatch_limit_recursion\fP
1452    field in a \fBpcre_extra\fP structure (or defaulted) was reached. See the
1453    description above.
1454    .sp
1455      PCRE_ERROR_NULLWSLIMIT    (-22)
1456    .sp
1457    When a group that can match an empty substring is repeated with an unbounded
1458    upper limit, the subject position at the start of the group must be remembered,
1459    so that a test for an empty string can be made when the end of the group is
1460    reached. Some workspace is required for this; if it runs out, this error is
1461    given.
1462    .sp
1463      PCRE_ERROR_BADNEWLINE     (-23)
1464    .sp
1465    An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
1466    .P
1467    Error numbers -16 to -20 are not used by \fBpcre_exec()\fP.
1468    .
1469    .
1470    .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
1471  .rs  .rs
1472  .sp  .sp
1473  .B int pcre_copy_substring(const char *\fIsubject\fR, int *\fIovector\fR,  .B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\fP,
1474  .ti +5n  .ti +5n
1475  .B int \fIstringcount\fR, int \fIstringnumber\fR, char *\fIbuffer\fR,  .B int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP,
1476  .ti +5n  .ti +5n
1477  .B int \fIbuffersize\fR);  .B int \fIbuffersize\fP);
1478  .PP  .PP
1479  .br  .br
1480  .B int pcre_get_substring(const char *\fIsubject\fR, int *\fIovector\fR,  .B int pcre_get_substring(const char *\fIsubject\fP, int *\fIovector\fP,
1481  .ti +5n  .ti +5n
1482  .B int \fIstringcount\fR, int \fIstringnumber\fR,  .B int \fIstringcount\fP, int \fIstringnumber\fP,
1483  .ti +5n  .ti +5n
1484  .B const char **\fIstringptr\fR);  .B const char **\fIstringptr\fP);
1485  .PP  .PP
1486  .br  .br
1487  .B int pcre_get_substring_list(const char *\fIsubject\fR,  .B int pcre_get_substring_list(const char *\fIsubject\fP,
1488  .ti +5n  .ti +5n
1489  .B int *\fIovector\fR, int \fIstringcount\fR, "const char ***\fIlistptr\fR);"  .B int *\fIovector\fP, int \fIstringcount\fP, "const char ***\fIlistptr\fP);"
1490  .PP  .PP
1491  Captured substrings can be accessed directly by using the offsets returned by  Captured substrings can be accessed directly by using the offsets returned by
1492  \fBpcre_exec()\fR in \fIovector\fR. For convenience, the functions  \fBpcre_exec()\fP in \fIovector\fP. For convenience, the functions
1493  \fBpcre_copy_substring()\fR, \fBpcre_get_substring()\fR, and  \fBpcre_copy_substring()\fP, \fBpcre_get_substring()\fP, and
1494  \fBpcre_get_substring_list()\fR are provided for extracting captured substrings  \fBpcre_get_substring_list()\fP are provided for extracting captured substrings
1495  as new, separate, zero-terminated strings. These functions identify substrings  as new, separate, zero-terminated strings. These functions identify substrings
1496  by number. The next section describes functions for extracting named  by number. The next section describes functions for extracting named
1497  substrings. A substring that contains a binary zero is correctly extracted and  substrings.
1498  has a further zero added on the end, but the result is not, of course,  .P
1499  a C string.  A substring that contains a binary zero is correctly extracted and has a
1500    further zero added on the end, but the result is not, of course, a C string.
1501    However, you can process such a string by referring to the length that is
1502    returned by \fBpcre_copy_substring()\fP and \fBpcre_get_substring()\fP.
1503    Unfortunately, the interface to \fBpcre_get_substring_list()\fP is not adequate
1504    for handling strings containing binary zeros, because the end of the final
1505    string is not independently indicated.
1506    .P
1507  The first three arguments are the same for all three of these functions:  The first three arguments are the same for all three of these functions:
1508  \fIsubject\fR is the subject string which has just been successfully matched,  \fIsubject\fP is the subject string that has just been successfully matched,
1509  \fIovector\fR is a pointer to the vector of integer offsets that was passed to  \fIovector\fP is a pointer to the vector of integer offsets that was passed to
1510  \fBpcre_exec()\fR, and \fIstringcount\fR is the number of substrings that were  \fBpcre_exec()\fP, and \fIstringcount\fP is the number of substrings that were
1511  captured by the match, including the substring that matched the entire regular  captured by the match, including the substring that matched the entire regular
1512  expression. This is the value returned by \fBpcre_exec\fR if it is greater than  expression. This is the value returned by \fBpcre_exec()\fP if it is greater
1513  zero. If \fBpcre_exec()\fR returned zero, indicating that it ran out of space  than zero. If \fBpcre_exec()\fP returned zero, indicating that it ran out of
1514  in \fIovector\fR, the value passed as \fIstringcount\fR should be the size of  space in \fIovector\fP, the value passed as \fIstringcount\fP should be the
1515  the vector divided by three.  number of elements in the vector divided by three.
1516    .P
1517  The functions \fBpcre_copy_substring()\fR and \fBpcre_get_substring()\fR  The functions \fBpcre_copy_substring()\fP and \fBpcre_get_substring()\fP
1518  extract a single substring, whose number is given as \fIstringnumber\fR. A  extract a single substring, whose number is given as \fIstringnumber\fP. A
1519  value of zero extracts the substring that matched the entire pattern, while  value of zero extracts the substring that matched the entire pattern, whereas
1520  higher values extract the captured substrings. For \fBpcre_copy_substring()\fR,  higher values extract the captured substrings. For \fBpcre_copy_substring()\fP,
1521  the string is placed in \fIbuffer\fR, whose length is given by  the string is placed in \fIbuffer\fP, whose length is given by
1522  \fIbuffersize\fR, while for \fBpcre_get_substring()\fR a new block of memory is  \fIbuffersize\fP, while for \fBpcre_get_substring()\fP a new block of memory is
1523  obtained via \fBpcre_malloc\fR, and its address is returned via  obtained via \fBpcre_malloc\fP, and its address is returned via
1524  \fIstringptr\fR. The yield of the function is the length of the string, not  \fIstringptr\fP. The yield of the function is the length of the string, not
1525  including the terminating zero, or one of  including the terminating zero, or one of these error codes:
1526    .sp
1527    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1528    .sp
1529  The buffer was too small for \fBpcre_copy_substring()\fR, or the attempt to get  The buffer was too small for \fBpcre_copy_substring()\fP, or the attempt to get
1530  memory failed for \fBpcre_get_substring()\fR.  memory failed for \fBpcre_get_substring()\fP.
1531    .sp
1532    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1533    .sp
1534  There is no substring whose number is \fIstringnumber\fR.  There is no substring whose number is \fIstringnumber\fP.
1535    .P
1536  The \fBpcre_get_substring_list()\fR function extracts all available substrings  The \fBpcre_get_substring_list()\fP function extracts all available substrings
1537  and builds a list of pointers to them. All this is done in a single block of  and builds a list of pointers to them. All this is done in a single block of
1538  memory which is obtained via \fBpcre_malloc\fR. The address of the memory block  memory that is obtained via \fBpcre_malloc\fP. The address of the memory block
1539  is returned via \fIlistptr\fR, which is also the start of the list of string  is returned via \fIlistptr\fP, which is also the start of the list of string
1540  pointers. The end of the list is marked by a NULL pointer. The yield of the  pointers. The end of the list is marked by a NULL pointer. The yield of the
1541  function is zero if all went well, or  function is zero if all went well, or the error code
1542    .sp
1543    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1544    .sp
1545  if the attempt to get the memory block failed.  if the attempt to get the memory block failed.
1546    .P
1547  When any of these functions encounter a substring that is unset, which can  When any of these functions encounter a substring that is unset, which can
1548  happen when capturing subpattern number \fIn+1\fR matches some part of the  happen when capturing subpattern number \fIn+1\fP matches some part of the
1549  subject, but subpattern \fIn\fR has not been used at all, they return an empty  subject, but subpattern \fIn\fP has not been used at all, they return an empty
1550  string. This can be distinguished from a genuine zero-length substring by  string. This can be distinguished from a genuine zero-length substring by
1551  inspecting the appropriate offset in \fIovector\fR, which is negative for unset  inspecting the appropriate offset in \fIovector\fP, which is negative for unset
1552  substrings.  substrings.
1553    .P
1554  The two convenience functions \fBpcre_free_substring()\fR and  The two convenience functions \fBpcre_free_substring()\fP and
1555  \fBpcre_free_substring_list()\fR can be used to free the memory returned by  \fBpcre_free_substring_list()\fP can be used to free the memory returned by
1556  a previous call of \fBpcre_get_substring()\fR or  a previous call of \fBpcre_get_substring()\fP or
1557  \fBpcre_get_substring_list()\fR, respectively. They do nothing more than call  \fBpcre_get_substring_list()\fP, respectively. They do nothing more than call
1558  the function pointed to by \fBpcre_free\fR, which of course could be called  the function pointed to by \fBpcre_free\fP, which of course could be called
1559  directly from a C program. However, PCRE is used in some situations where it is  directly from a C program. However, PCRE is used in some situations where it is
1560  linked via a special interface to another programming language which cannot use  linked via a special interface to another programming language that cannot use
1561  \fBpcre_free\fR directly; it is for these cases that the functions are  \fBpcre_free\fP directly; it is for these cases that the functions are
1562  provided.  provided.
1563    .
1564  .SH EXTRACTING CAPTURED SUBSTRINGS BY NAME  .
1565    .SH "EXTRACTING CAPTURED SUBSTRINGS BY NAME"
1566  .rs  .rs
1567  .sp  .sp
1568  .B int pcre_copy_named_substring(const pcre *\fIcode\fR,  .B int pcre_get_stringnumber(const pcre *\fIcode\fP,
 .ti +5n  
 .B const char *\fIsubject\fR, int *\fIovector\fR,  
1569  .ti +5n  .ti +5n
1570  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B const char *\fIname\fP);
 .ti +5n  
 .B char *\fIbuffer\fR, int \fIbuffersize\fR);  
1571  .PP  .PP
1572  .br  .br
1573  .B int pcre_get_stringnumber(const pcre *\fIcode\fR,  .B int pcre_copy_named_substring(const pcre *\fIcode\fP,
1574    .ti +5n
1575    .B const char *\fIsubject\fP, int *\fIovector\fP,
1576    .ti +5n
1577    .B int \fIstringcount\fP, const char *\fIstringname\fP,
1578  .ti +5n  .ti +5n
1579  .B const char *\fIname\fR);  .B char *\fIbuffer\fP, int \fIbuffersize\fP);
1580  .PP  .PP
1581  .br  .br
1582  .B int pcre_get_named_substring(const pcre *\fIcode\fR,  .B int pcre_get_named_substring(const pcre *\fIcode\fP,
1583  .ti +5n  .ti +5n
1584  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B const char *\fIsubject\fP, int *\fIovector\fP,
1585  .ti +5n  .ti +5n
1586  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B int \fIstringcount\fP, const char *\fIstringname\fP,
1587  .ti +5n  .ti +5n
1588  .B const char **\fIstringptr\fR);  .B const char **\fIstringptr\fP);
1589  .PP  .PP
1590  To extract a substring by name, you first have to find associated number. This  To extract a substring by name, you first have to find associated number.
1591  can be done by calling \fBpcre_get_stringnumber()\fR. The first argument is the  For example, for this pattern
1592  compiled pattern, and the second is the name. For example, for this pattern  .sp
1593      (a+)b(?<xxx>\ed+)...
1594    ab(?<xxx>\\d+)...  .sp
1595    the number of the subpattern called "xxx" is 2. If the name is known to be
1596  the number of the subpattern called "xxx" is 1. Given the number, you can then  unique (PCRE_DUPNAMES was not set), you can find the number from the name by
1597  extract the substring directly, or use one of the functions described in the  calling \fBpcre_get_stringnumber()\fP. The first argument is the compiled
1598  previous section. For convenience, there are also two functions that do the  pattern, and the second is the name. The yield of the function is the
1599  whole job.  subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if there is no subpattern of
1600    that name.
1601  Most of the arguments of \fIpcre_copy_named_substring()\fR and  .P
1602  \fIpcre_get_named_substring()\fR are the same as those for the functions that  Given the number, you can extract the substring directly, or use one of the
1603  extract by number, and so are not re-described here. There are just two  functions described in the previous section. For convenience, there are also
1604  differences.  two functions that do the whole job.
1605    .P
1606    Most of the arguments of \fBpcre_copy_named_substring()\fP and
1607    \fBpcre_get_named_substring()\fP are the same as those for the similarly named
1608    functions that extract by number. As these are described in the previous
1609    section, they are not re-described here. There are just two differences:
1610    .P
1611  First, instead of a substring number, a substring name is given. Second, there  First, instead of a substring number, a substring name is given. Second, there
1612  is an extra argument, given at the start, which is a pointer to the compiled  is an extra argument, given at the start, which is a pointer to the compiled
1613  pattern. This is needed in order to gain access to the name-to-number  pattern. This is needed in order to gain access to the name-to-number
1614  translation table.  translation table.
1615    .P
1616  These functions call \fBpcre_get_stringnumber()\fR, and if it succeeds, they  These functions call \fBpcre_get_stringnumber()\fP, and if it succeeds, they
1617  then call \fIpcre_copy_substring()\fR or \fIpcre_get_substring()\fR, as  then call \fIpcre_copy_substring()\fP or \fIpcre_get_substring()\fP, as
1618  appropriate.  appropriate.
1619    .
1620    .
1621    .SH "DUPLICATE SUBPATTERN NAMES"
1622    .rs
1623    .sp
1624    .B int pcre_get_stringtable_entries(const pcre *\fIcode\fP,
1625    .ti +5n
1626    .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
1627    .PP
1628    When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
1629    are not required to be unique. Normally, patterns with duplicate names are such
1630    that in any one match, only one of the named subpatterns participates. An
1631    example is shown in the
1632    .\" HREF
1633    \fBpcrepattern\fP
1634    .\"
1635    documentation. When duplicates are present, \fBpcre_copy_named_substring()\fP
1636    and \fBpcre_get_named_substring()\fP return the first substring corresponding
1637    to the given name that is set. If none are set, an empty string is returned.
1638    The \fBpcre_get_stringnumber()\fP function returns one of the numbers that are
1639    associated with the name, but it is not defined which it is.
1640    .sp
1641    If you want to get full details of all captured substrings for a given name,
1642    you must use the \fBpcre_get_stringtable_entries()\fP function. The first
1643    argument is the compiled pattern, and the second is the name. The third and
1644    fourth are pointers to variables which are updated by the function. After it
1645    has run, they point to the first and last entries in the name-to-number table
1646    for the given name. The function itself returns the length of each entry, or
1647    PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
1648    described above in the section entitled \fIInformation about a pattern\fP.
1649    Given all the relevant entries for the name, you can extract each of their
1650    numbers, and hence the captured data, if any.
1651    .
1652    .
1653    .SH "FINDING ALL POSSIBLE MATCHES"
1654    .rs
1655    .sp
1656    The traditional matching function uses a similar algorithm to Perl, which stops
1657    when it finds the first match, starting at a given point in the subject. If you
1658    want to find all possible matches, or the longest possible match, consider
1659    using the alternative matching function (see below) instead. If you cannot use
1660    the alternative function, but still need to find all possible matches, you
1661    can kludge it up by making use of the callout facility, which is described in
1662    the
1663    .\" HREF
1664    \fBpcrecallout\fP
1665    .\"
1666    documentation.
1667    .P
1668    What you have to do is to insert a callout right at the end of the pattern.
1669    When your callout function is called, extract and save the current matched
1670    substring. Then return 1, which forces \fBpcre_exec()\fP to backtrack and try
1671    other alternatives. Ultimately, when it runs out of matches, \fBpcre_exec()\fP
1672    will yield PCRE_ERROR_NOMATCH.
1673    .
1674    .
1675    .\" HTML <a name="dfamatch"></a>
1676    .SH "MATCHING A PATTERN: THE ALTERNATIVE FUNCTION"
1677    .rs
1678    .sp
1679    .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
1680    .ti +5n
1681    .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
1682    .ti +5n
1683    .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,
1684    .ti +5n
1685    .B int *\fIworkspace\fP, int \fIwscount\fP);
1686    .P
1687    The function \fBpcre_dfa_exec()\fP is called to match a subject string against
1688    a compiled pattern, using a matching algorithm that scans the subject string
1689    just once, and does not backtrack. This has different characteristics to the
1690    normal algorithm, and is not compatible with Perl. Some of the features of PCRE
1691    patterns are not supported. Nevertheless, there are times when this kind of
1692    matching can be useful. For a discussion of the two matching algorithms, see
1693    the
1694    .\" HREF
1695    \fBpcrematching\fP
1696    .\"
1697    documentation.
1698    .P
1699    The arguments for the \fBpcre_dfa_exec()\fP function are the same as for
1700    \fBpcre_exec()\fP, plus two extras. The \fIovector\fP argument is used in a
1701    different way, and this is described below. The other common arguments are used
1702    in the same way as for \fBpcre_exec()\fP, so their description is not repeated
1703    here.
1704    .P
1705    The two additional arguments provide workspace for the function. The workspace
1706    vector should contain at least 20 elements. It is used for keeping track of
1707    multiple paths through the pattern tree. More workspace will be needed for
1708    patterns and subjects where there are a lot of potential matches.
1709    .P
1710    Here is an example of a simple call to \fBpcre_dfa_exec()\fP:
1711    .sp
1712      int rc;
1713      int ovector[10];
1714      int wspace[20];
1715      rc = pcre_dfa_exec(
1716        re,             /* result of pcre_compile() */
1717        NULL,           /* we didn't study the pattern */
1718        "some string",  /* the subject string */
1719        11,             /* the length of the subject string */
1720        0,              /* start at offset 0 in the subject */
1721        0,              /* default options */
1722        ovector,        /* vector of integers for substring information */
1723        10,             /* number of elements (NOT size in bytes) */
1724        wspace,         /* working space vector */
1725        20);            /* number of elements (NOT size in bytes) */
1726    .
1727    .SS "Option bits for \fBpcre_dfa_exec()\fP"
1728    .rs
1729    .sp
1730    The unused bits of the \fIoptions\fP argument for \fBpcre_dfa_exec()\fP must be
1731    zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
1732    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,
1733    PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last three of these are
1734    the same as for \fBpcre_exec()\fP, so their description is not repeated here.
1735    .sp
1736      PCRE_PARTIAL
1737    .sp
1738    This has the same general effect as it does for \fBpcre_exec()\fP, but the
1739    details are slightly different. When PCRE_PARTIAL is set for
1740    \fBpcre_dfa_exec()\fP, the return code PCRE_ERROR_NOMATCH is converted into
1741    PCRE_ERROR_PARTIAL if the end of the subject is reached, there have been no
1742    complete matches, but there is still at least one matching possibility. The
1743    portion of the string that provided the partial match is set as the first
1744    matching string.
1745    .sp
1746      PCRE_DFA_SHORTEST
1747    .sp
1748    Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as
1749    soon as it has found one match. Because of the way the alternative algorithm
1750    works, this is necessarily the shortest possible match at the first possible
1751    matching point in the subject string.
1752    .sp
1753      PCRE_DFA_RESTART
1754    .sp
1755    When \fBpcre_dfa_exec()\fP is called with the PCRE_PARTIAL option, and returns
1756    a partial match, it is possible to call it again, with additional subject
1757    characters, and have it continue with the same match. The PCRE_DFA_RESTART
1758    option requests this action; when it is set, the \fIworkspace\fP and
1759    \fIwscount\fP options must reference the same vector as before because data
1760    about the match so far is left in them after a partial match. There is more
1761    discussion of this facility in the
1762    .\" HREF
1763    \fBpcrepartial\fP
1764    .\"
1765    documentation.
1766    .
1767    .SS "Successful returns from \fBpcre_dfa_exec()\fP"
1768    .rs
1769    .sp
1770    When \fBpcre_dfa_exec()\fP succeeds, it may have matched more than one
1771    substring in the subject. Note, however, that all the matches from one run of
1772    the function start at the same point in the subject. The shorter matches are
1773    all initial substrings of the longer matches. For example, if the pattern
1774    .sp
1775      <.*>
1776    .sp
1777    is matched against the string
1778    .sp
1779      This is <something> <something else> <something further> no more
1780    .sp
1781    the three matched strings are
1782    .sp
1783      <something>
1784      <something> <something else>
1785      <something> <something else> <something further>
1786    .sp
1787    On success, the yield of the function is a number greater than zero, which is
1788    the number of matched substrings. The substrings themselves are returned in
1789    \fIovector\fP. Each string uses two elements; the first is the offset to the
1790    start, and the second is the offset to the end. In fact, all the strings have
1791    the same start offset. (Space could have been saved by giving this only once,
1792    but it was decided to retain some compatibility with the way \fBpcre_exec()\fP
1793    returns data, even though the meaning of the strings is different.)
1794    .P
1795    The strings are returned in reverse order of length; that is, the longest
1796    matching string is given first. If there were too many matches to fit into
1797    \fIovector\fP, the yield of the function is zero, and the vector is filled with
1798    the longest matches.
1799    .
1800    .SS "Error returns from \fBpcre_dfa_exec()\fP"
1801    .rs
1802    .sp
1803    The \fBpcre_dfa_exec()\fP function returns a negative number when it fails.
1804    Many of the errors are the same as for \fBpcre_exec()\fP, and these are
1805    described
1806    .\" HTML <a href="#errorlist">
1807    .\" </a>
1808    above.
1809    .\"
1810    There are in addition the following errors that are specific to
1811    \fBpcre_dfa_exec()\fP:
1812    .sp
1813      PCRE_ERROR_DFA_UITEM      (-16)
1814    .sp
1815    This return is given if \fBpcre_dfa_exec()\fP encounters an item in the pattern
1816    that it does not support, for instance, the use of \eC or a back reference.
1817    .sp
1818      PCRE_ERROR_DFA_UCOND      (-17)
1819    .sp
1820    This return is given if \fBpcre_dfa_exec()\fP encounters a condition item that
1821    uses a back reference for the condition, or a test for recursion in a specific
1822    group. These are not supported.
1823    .sp
1824      PCRE_ERROR_DFA_UMLIMIT    (-18)
1825    .sp
1826    This return is given if \fBpcre_dfa_exec()\fP is called with an \fIextra\fP
1827    block that contains a setting of the \fImatch_limit\fP field. This is not
1828    supported (it is meaningless).
1829    .sp
1830      PCRE_ERROR_DFA_WSSIZE     (-19)
1831    .sp
1832    This return is given if \fBpcre_dfa_exec()\fP runs out of space in the
1833    \fIworkspace\fP vector.
1834    .sp
1835      PCRE_ERROR_DFA_RECURSE    (-20)
1836    .sp
1837    When a recursive subpattern is processed, the matching function calls itself
1838    recursively, using private vectors for \fIovector\fP and \fIworkspace\fP. This
1839    error is given if the output vector is not large enough. This should be
1840    extremely rare, as a vector of size 1000 is used.
1841    .
1842    .
1843    .SH "SEE ALSO"
1844    .rs
1845    .sp
1846    \fBpcrebuild\fP(3), \fBpcrecallout\fP(3), \fBpcrecpp(3)\fP(3),
1847    \fBpcrematching\fP(3), \fBpcrepartial\fP(3), \fBpcreposix\fP(3),
1848    \fBpcreprecompile\fP(3), \fBpcresample\fP(3), \fBpcrestack\fP(3).
1849    .P
1850  .in 0  .in 0
1851  Last updated: 20 August 2003  Last updated: 30 November 2006
1852  .br  .br
1853  Copyright (c) 1997-2003 University of Cambridge.  Copyright (c) 1997-2006 University of Cambridge.

Legend:
Removed from v.71  
changed lines
  Added in v.93

  ViewVC Help
Powered by ViewVC 1.1.5