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revision 65 by nigel, Sat Feb 24 21:40:08 2007 UTC revision 579 by ph10, Wed Nov 24 17:39:25 2010 UTC
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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  .B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,
 .B pcre *pcre_compile(const char *\fIpattern\fR, int \fIoptions\fR,  
11  .ti +5n  .ti +5n
12  .B const char **\fIerrptr\fR, int *\fIerroffset\fR,  .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
13  .ti +5n  .ti +5n
14  .B const unsigned char *\fItableptr\fR);  .B const unsigned char *\fItableptr\fP);
15  .PP  .PP
16  .br  .B pcre *pcre_compile2(const char *\fIpattern\fP, int \fIoptions\fP,
 .B pcre_extra *pcre_study(const pcre *\fIcode\fR, int \fIoptions\fR,  
17  .ti +5n  .ti +5n
18  .B const char **\fIerrptr\fR);  .B int *\fIerrorcodeptr\fP,
19    .ti +5n
20    .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
21    .ti +5n
22    .B const unsigned char *\fItableptr\fP);
23    .PP
24    .B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP,
25    .ti +5n
26    .B const char **\fIerrptr\fP);
27  .PP  .PP
28  .br  .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
 .B int pcre_exec(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"  
29  .ti +5n  .ti +5n
30  .B "const char *\fIsubject\fR," int \fIlength\fR, int \fIstartoffset\fR,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
31  .ti +5n  .ti +5n
32  .B int \fIoptions\fR, int *\fIovector\fR, int \fIovecsize\fR);  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
33  .PP  .PP
34  .br  .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
 .B int pcre_copy_named_substring(const pcre *\fIcode\fR,  
35  .ti +5n  .ti +5n
36  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
37  .ti +5n  .ti +5n
38  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,
39  .ti +5n  .ti +5n
40  .B char *\fIbuffer\fR, int \fIbuffersize\fR);  .B int *\fIworkspace\fP, int \fIwscount\fP);
41  .PP  .PP
42  .br  .B int pcre_copy_named_substring(const pcre *\fIcode\fP,
 .B int pcre_copy_substring(const char *\fIsubject\fR, int *\fIovector\fR,  
43  .ti +5n  .ti +5n
44  .B int \fIstringcount\fR, int \fIstringnumber\fR, char *\fIbuffer\fR,  .B const char *\fIsubject\fP, int *\fIovector\fP,
45  .ti +5n  .ti +5n
46  .B int \fIbuffersize\fR);  .B int \fIstringcount\fP, const char *\fIstringname\fP,
47    .ti +5n
48    .B char *\fIbuffer\fP, int \fIbuffersize\fP);
49  .PP  .PP
50  .br  .B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\fP,
51  .B int pcre_get_named_substring(const pcre *\fIcode\fR,  .ti +5n
52    .B int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP,
53  .ti +5n  .ti +5n
54  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B int \fIbuffersize\fP);
55    .PP
56    .B int pcre_get_named_substring(const pcre *\fIcode\fP,
57  .ti +5n  .ti +5n
58  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B const char *\fIsubject\fP, int *\fIovector\fP,
59  .ti +5n  .ti +5n
60  .B const char **\fIstringptr\fR);  .B int \fIstringcount\fP, const char *\fIstringname\fP,
61    .ti +5n
62    .B const char **\fIstringptr\fP);
63    .PP
64    .B int pcre_get_stringnumber(const pcre *\fIcode\fP,
65    .ti +5n
66    .B const char *\fIname\fP);
67  .PP  .PP
68  .br  .B int pcre_get_stringtable_entries(const pcre *\fIcode\fP,
 .B int pcre_get_stringnumber(const pcre *\fIcode\fR,  
69  .ti +5n  .ti +5n
70  .B const char *\fIname\fR);  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
71  .PP  .PP
72  .br  .B int pcre_get_substring(const char *\fIsubject\fP, int *\fIovector\fP,
 .B int pcre_get_substring(const char *\fIsubject\fR, int *\fIovector\fR,  
73  .ti +5n  .ti +5n
74  .B int \fIstringcount\fR, int \fIstringnumber\fR,  .B int \fIstringcount\fP, int \fIstringnumber\fP,
75  .ti +5n  .ti +5n
76  .B const char **\fIstringptr\fR);  .B const char **\fIstringptr\fP);
77  .PP  .PP
78  .br  .B int pcre_get_substring_list(const char *\fIsubject\fP,
 .B int pcre_get_substring_list(const char *\fIsubject\fR,  
79  .ti +5n  .ti +5n
80  .B int *\fIovector\fR, int \fIstringcount\fR, "const char ***\fIlistptr\fR);"  .B int *\fIovector\fP, int \fIstringcount\fP, "const char ***\fIlistptr\fP);"
81  .PP  .PP
82  .br  .B void pcre_free_substring(const char *\fIstringptr\fP);
 .B void pcre_free_substring(const char *\fIstringptr\fR);  
83  .PP  .PP
84  .br  .B void pcre_free_substring_list(const char **\fIstringptr\fP);
 .B void pcre_free_substring_list(const char **\fIstringptr\fR);  
85  .PP  .PP
 .br  
86  .B const unsigned char *pcre_maketables(void);  .B const unsigned char *pcre_maketables(void);
87  .PP  .PP
88  .br  .B int pcre_fullinfo(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
 .B int pcre_fullinfo(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"  
89  .ti +5n  .ti +5n
90  .B int \fIwhat\fR, void *\fIwhere\fR);  .B int \fIwhat\fP, void *\fIwhere\fP);
91  .PP  .PP
92  .br  .B int pcre_info(const pcre *\fIcode\fP, int *\fIoptptr\fP, int
93  .B int pcre_info(const pcre *\fIcode\fR, int *\fIoptptr\fR, int  .B *\fIfirstcharptr\fP);
 .B *\fIfirstcharptr\fR);  
94  .PP  .PP
95  .br  .B int pcre_refcount(pcre *\fIcode\fP, int \fIadjust\fP);
96  .B int pcre_config(int \fIwhat\fR, void *\fIwhere\fR);  .PP
97    .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
98  .PP  .PP
 .br  
99  .B char *pcre_version(void);  .B char *pcre_version(void);
100  .PP  .PP
 .br  
101  .B void *(*pcre_malloc)(size_t);  .B void *(*pcre_malloc)(size_t);
102  .PP  .PP
 .br  
103  .B void (*pcre_free)(void *);  .B void (*pcre_free)(void *);
104  .PP  .PP
105  .br  .B void *(*pcre_stack_malloc)(size_t);
106    .PP
107    .B void (*pcre_stack_free)(void *);
108    .PP
109  .B int (*pcre_callout)(pcre_callout_block *);  .B int (*pcre_callout)(pcre_callout_block *);
110    .
111  .SH PCRE API  .
112    .SH "PCRE API OVERVIEW"
113  .rs  .rs
114  .sp  .sp
115  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
116  a set of wrapper functions that correspond to the POSIX regular expression API.  also some wrapper functions that correspond to the POSIX regular expression
117  These are described in the \fBpcreposix\fR documentation.  API. These are described in the
118    .\" HREF
119  The native API function prototypes are defined in the header file \fBpcre.h\fR,  \fBpcreposix\fP
120  and on Unix systems the library itself is called \fBlibpcre.a\fR, so can be  .\"
121  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++
122  calls it. The header file defines the macros PCRE_MAJOR and PCRE_MINOR to  wrapper is distributed with PCRE. It is documented in the
123  contain the major and minor release numbers for the library. Applications can  .\" HREF
124  use these to include support for different releases.  \fBpcrecpp\fP
125    .\"
126  The functions \fBpcre_compile()\fR, \fBpcre_study()\fR, and \fBpcre_exec()\fR  page.
127  are used for compiling and matching regular expressions. A sample program that  .P
128  demonstrates the simplest way of using them is given in the file  The native API C function prototypes are defined in the header file
129  \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.
130    It can normally be accessed by adding \fB-lpcre\fP to the command for linking
131  There are convenience functions for extracting captured substrings from a  an application that uses PCRE. The header file defines the macros PCRE_MAJOR
132  matched subject string. They are:  and PCRE_MINOR to contain the major and minor release numbers for the library.
133    Applications can use these to include support for different releases of PCRE.
134    \fBpcre_copy_substring()\fR  .P
135    \fBpcre_copy_named_substring()\fR  In a Windows environment, if you want to statically link an application program
136    \fBpcre_get_substring()\fR  against a non-dll \fBpcre.a\fP file, you must define PCRE_STATIC before
137    \fBpcre_get_named_substring()\fR  including \fBpcre.h\fP or \fBpcrecpp.h\fP, because otherwise the
138    \fBpcre_get_substring_list()\fR  \fBpcre_malloc()\fP and \fBpcre_free()\fP exported functions will be declared
139    \fB__declspec(dllimport)\fP, with unwanted results.
140  \fBpcre_free_substring()\fR and \fBpcre_free_substring_list()\fR are also  .P
141    The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,
142    and \fBpcre_exec()\fP are used for compiling and matching regular expressions
143    in a Perl-compatible manner. A sample program that demonstrates the simplest
144    way of using them is provided in the file called \fIpcredemo.c\fP in the PCRE
145    source distribution. A listing of this program is given in the
146    .\" HREF
147    \fBpcredemo\fP
148    .\"
149    documentation, and the
150    .\" HREF
151    \fBpcresample\fP
152    .\"
153    documentation describes how to compile and run it.
154    .P
155    A second matching function, \fBpcre_dfa_exec()\fP, which is not
156    Perl-compatible, is also provided. This uses a different algorithm for the
157    matching. The alternative algorithm finds all possible matches (at a given
158    point in the subject), and scans the subject just once (unless there are
159    lookbehind assertions). However, this algorithm does not return captured
160    substrings. A description of the two matching algorithms and their advantages
161    and disadvantages is given in the
162    .\" HREF
163    \fBpcrematching\fP
164    .\"
165    documentation.
166    .P
167    In addition to the main compiling and matching functions, there are convenience
168    functions for extracting captured substrings from a subject string that is
169    matched by \fBpcre_exec()\fP. They are:
170    .sp
171      \fBpcre_copy_substring()\fP
172      \fBpcre_copy_named_substring()\fP
173      \fBpcre_get_substring()\fP
174      \fBpcre_get_named_substring()\fP
175      \fBpcre_get_substring_list()\fP
176      \fBpcre_get_stringnumber()\fP
177      \fBpcre_get_stringtable_entries()\fP
178    .sp
179    \fBpcre_free_substring()\fP and \fBpcre_free_substring_list()\fP are also
180  provided, to free the memory used for extracted strings.  provided, to free the memory used for extracted strings.
181    .P
182  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
183  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,
184    or \fBpcre_dfa_exec()\fP. This is an optional facility that is provided for
185  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
186  compiled pattern; \fBpcre_info()\fR is an obsolete version which returns only  internal tables that are generated when PCRE is built are used.
187    .P
188    The function \fBpcre_fullinfo()\fP is used to find out information about a
189    compiled pattern; \fBpcre_info()\fP is an obsolete version that returns only
190  some of the available information, but is retained for backwards compatibility.  some of the available information, but is retained for backwards compatibility.
191  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
192  version of PCRE and its date of release.  version of PCRE and its date of release.
193    .P
194  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
195  the entry points of the standard \fBmalloc()\fR and \fBfree()\fR functions  containing a compiled pattern. This is provided for the benefit of
196    object-oriented applications.
197    .P
198    The global variables \fBpcre_malloc\fP and \fBpcre_free\fP initially contain
199    the entry points of the standard \fBmalloc()\fP and \fBfree()\fP functions,
200  respectively. PCRE calls the memory management functions via these variables,  respectively. PCRE calls the memory management functions via these variables,
201  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
202  should be done before calling any PCRE functions.  should be done before calling any PCRE functions.
203    .P
204  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
205    indirections to memory management functions. These special functions are used
206    only when PCRE is compiled to use the heap for remembering data, instead of
207    recursive function calls, when running the \fBpcre_exec()\fP function. See the
208    .\" HREF
209    \fBpcrebuild\fP
210    .\"
211    documentation for details of how to do this. It is a non-standard way of
212    building PCRE, for use in environments that have limited stacks. Because of the
213    greater use of memory management, it runs more slowly. Separate functions are
214    provided so that special-purpose external code can be used for this case. When
215    used, these functions are always called in a stack-like manner (last obtained,
216    first freed), and always for memory blocks of the same size. There is a
217    discussion about PCRE's stack usage in the
218    .\" HREF
219    \fBpcrestack\fP
220    .\"
221    documentation.
222    .P
223    The global variable \fBpcre_callout\fP initially contains NULL. It can be set
224  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
225  points during a matching operation. Details are given in the \fBpcrecallout\fR  points during a matching operation. Details are given in the
226    .\" HREF
227    \fBpcrecallout\fP
228    .\"
229  documentation.  documentation.
230    .
231    .
232    .\" HTML <a name="newlines"></a>
233    .SH NEWLINES
234    .rs
235    .sp
236    PCRE supports five different conventions for indicating line breaks in
237    strings: a single CR (carriage return) character, a single LF (linefeed)
238    character, the two-character sequence CRLF, any of the three preceding, or any
239    Unicode newline sequence. The Unicode newline sequences are the three just
240    mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed,
241    U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
242    (paragraph separator, U+2029).
243    .P
244    Each of the first three conventions is used by at least one operating system as
245    its standard newline sequence. When PCRE is built, a default can be specified.
246    The default default is LF, which is the Unix standard. When PCRE is run, the
247    default can be overridden, either when a pattern is compiled, or when it is
248    matched.
249    .P
250    At compile time, the newline convention can be specified by the \fIoptions\fP
251    argument of \fBpcre_compile()\fP, or it can be specified by special text at the
252    start of the pattern itself; this overrides any other settings. See the
253    .\" HREF
254    \fBpcrepattern\fP
255    .\"
256    page for details of the special character sequences.
257    .P
258    In the PCRE documentation the word "newline" is used to mean "the character or
259    pair of characters that indicate a line break". The choice of newline
260    convention affects the handling of the dot, circumflex, and dollar
261    metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
262    recognized line ending sequence, the match position advancement for a
263    non-anchored pattern. There is more detail about this in the
264    .\" HTML <a href="#execoptions">
265    .\" </a>
266    section on \fBpcre_exec()\fP options
267    .\"
268    below.
269    .P
270    The choice of newline convention does not affect the interpretation of
271    the \en or \er escape sequences, nor does it affect what \eR matches, which is
272    controlled in a similar way, but by separate options.
273    .
274    .
275  .SH MULTITHREADING  .SH MULTITHREADING
276  .rs  .rs
277  .sp  .sp
278  The PCRE functions can be used in multi-threading applications, with the  The PCRE functions can be used in multi-threading applications, with the
279  proviso that the memory management functions pointed to by \fBpcre_malloc\fR  proviso that the memory management functions pointed to by \fBpcre_malloc\fP,
280  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
281  are shared by all threads.  callout function pointed to by \fBpcre_callout\fP, are shared by all threads.
282    .P
283  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
284  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.
285    .
286  .SH CHECKING BUILD-TIME OPTIONS  .
287    .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"
288    .rs
289    .sp
290    The compiled form of a regular expression can be saved and re-used at a later
291    time, possibly by a different program, and even on a host other than the one on
292    which it was compiled. Details are given in the
293    .\" HREF
294    \fBpcreprecompile\fP
295    .\"
296    documentation. However, compiling a regular expression with one version of PCRE
297    for use with a different version is not guaranteed to work and may cause
298    crashes.
299    .
300    .
301    .SH "CHECKING BUILD-TIME OPTIONS"
302  .rs  .rs
303  .sp  .sp
304  .B int pcre_config(int \fIwhat\fR, void *\fIwhere\fR);  .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
305  .PP  .PP
306  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
307  discover which optional features have been compiled into the PCRE library. The  discover which optional features have been compiled into the PCRE library. The
308  .\" HREF  .\" HREF
309  \fBpcrebuild\fR  \fBpcrebuild\fP
310  .\"  .\"
311  documentation has more details about these optional features.  documentation has more details about these optional features.
312    .P
313  The first argument for \fBpcre_config()\fR is an integer, specifying which  The first argument for \fBpcre_config()\fP is an integer, specifying which
314  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
315  which the information is placed. The following information is available:  which the information is placed. The following information is available:
316    .sp
317    PCRE_CONFIG_UTF8    PCRE_CONFIG_UTF8
318    .sp
319  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;
320  otherwise it is set to zero.  otherwise it is set to zero.
321    .sp
322      PCRE_CONFIG_UNICODE_PROPERTIES
323    .sp
324    The output is an integer that is set to one if support for Unicode character
325    properties is available; otherwise it is set to zero.
326    .sp
327    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
328    .sp
329  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
330  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
331  should normally be the standard character for your operating system.  are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF, and -1 for ANY.
332    Though they are derived from ASCII, the same values are returned in EBCDIC
333    environments. The default should normally correspond to the standard sequence
334    for your operating system.
335    .sp
336      PCRE_CONFIG_BSR
337    .sp
338    The output is an integer whose value indicates what character sequences the \eR
339    escape sequence matches by default. A value of 0 means that \eR matches any
340    Unicode line ending sequence; a value of 1 means that \eR matches only CR, LF,
341    or CRLF. The default can be overridden when a pattern is compiled or matched.
342    .sp
343    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
344    .sp
345  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
346  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
347  allow larger regular expressions to be compiled, at the expense of slower  allow larger regular expressions to be compiled, at the expense of slower
348  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
349  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.
350    .sp
351    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
352    .sp
353  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
354  interface uses \fBmalloc()\fR for output vectors. Further details are given in  interface uses \fBmalloc()\fP for output vectors. Further details are given in
355  the \fBpcreposix\fR documentation.  the
356    .\" HREF
357    \fBpcreposix\fP
358    .\"
359    documentation.
360    .sp
361    PCRE_CONFIG_MATCH_LIMIT    PCRE_CONFIG_MATCH_LIMIT
362    .sp
363  The output is an integer that gives the default limit for the number of  The output is a long integer that gives the default limit for the number of
364  internal matching function calls in a \fBpcre_exec()\fR execution. Further  internal matching function calls in a \fBpcre_exec()\fP execution. Further
365  details are given with \fBpcre_exec()\fR below.  details are given with \fBpcre_exec()\fP below.
366    .sp
367  .SH COMPILING A PATTERN    PCRE_CONFIG_MATCH_LIMIT_RECURSION
368  .rs  .sp
369  .sp  The output is a long integer that gives the default limit for the depth of
370  .B pcre *pcre_compile(const char *\fIpattern\fR, int \fIoptions\fR,  recursion when calling the internal matching function in a \fBpcre_exec()\fP
371  .ti +5n  execution. Further details are given with \fBpcre_exec()\fP below.
372  .B const char **\fIerrptr\fR, int *\fIerroffset\fR,  .sp
373  .ti +5n    PCRE_CONFIG_STACKRECURSE
374  .B const unsigned char *\fItableptr\fR);  .sp
375  .PP  The output is an integer that is set to one if internal recursion when running
376    \fBpcre_exec()\fP is implemented by recursive function calls that use the stack
377  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
378  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
379  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
380  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
381  code and related data. The \fBpcre\fR type is defined for the returned block;  avoiding the use of the stack.
382  this is a typedef for a structure whose contents are not externally defined. It  .
383  is up to the caller to free the memory when it is no longer required.  .
384    .SH "COMPILING A PATTERN"
385    .rs
386    .sp
387    .B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,
388    .ti +5n
389    .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
390    .ti +5n
391    .B const unsigned char *\fItableptr\fP);
392    .sp
393    .B pcre *pcre_compile2(const char *\fIpattern\fP, int \fIoptions\fP,
394    .ti +5n
395    .B int *\fIerrorcodeptr\fP,
396    .ti +5n
397    .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
398    .ti +5n
399    .B const unsigned char *\fItableptr\fP);
400    .P
401    Either of the functions \fBpcre_compile()\fP or \fBpcre_compile2()\fP can be
402    called to compile a pattern into an internal form. The only difference between
403    the two interfaces is that \fBpcre_compile2()\fP has an additional argument,
404    \fIerrorcodeptr\fP, via which a numerical error code can be returned. To avoid
405    too much repetition, we refer just to \fBpcre_compile()\fP below, but the
406    information applies equally to \fBpcre_compile2()\fP.
407    .P
408    The pattern is a C string terminated by a binary zero, and is passed in the
409    \fIpattern\fP argument. A pointer to a single block of memory that is obtained
410    via \fBpcre_malloc\fP is returned. This contains the compiled code and related
411    data. The \fBpcre\fP type is defined for the returned block; this is a typedef
412    for a structure whose contents are not externally defined. It is up to the
413    caller to free the memory (via \fBpcre_free\fP) when it is no longer required.
414    .P
415  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
416  depend on memory location, the complete \fBpcre\fR data block is not  depend on memory location, the complete \fBpcre\fP data block is not
417  fully relocatable, because it contains a copy of the \fItableptr\fR argument,  fully relocatable, because it may contain a copy of the \fItableptr\fP
418  which is an address (see below).  argument, which is an address (see below).
419    .P
420  The \fIoptions\fR argument contains independent bits that affect the  The \fIoptions\fP argument contains various bit settings that affect the
421  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
422  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
423  from within the pattern (see the detailed description of regular expressions  compatible with Perl, but some others as well) can also be set and unset from
424  in the \fBpcrepattern\fR documentation). For these options, the contents of the  within the pattern (see the detailed description in the
425  \fIoptions\fR argument specifies their initial settings at the start of  .\" HREF
426  compilation and execution. The PCRE_ANCHORED option can be set at the time of  \fBpcrepattern\fP
427  matching as well as at compile time.  .\"
428    documentation). For those options that can be different in different parts of
429  If \fIerrptr\fR is NULL, \fBpcre_compile()\fR returns NULL immediately.  the pattern, the contents of the \fIoptions\fP argument specifies their
430  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fR returns  settings at the start of compilation and execution. The PCRE_ANCHORED,
431  NULL, and sets the variable pointed to by \fIerrptr\fR to point to a textual  PCRE_BSR_\fIxxx\fP, PCRE_NEWLINE_\fIxxx\fP, PCRE_NO_UTF8_CHECK, and
432  error message. The offset from the start of the pattern to the character where  PCRE_NO_START_OPT options can be set at the time of matching as well as at
433  the error was discovered is placed in the variable pointed to by  compile time.
434  \fIerroffset\fR, which must not be NULL. If it is, an immediate error is given.  .P
435    If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
436  If the final argument, \fItableptr\fR, is NULL, PCRE uses a default set of  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
437  character tables which are built when it is compiled, using the default C  NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual
438  locale. Otherwise, \fItableptr\fR must be the result of a call to  error message. This is a static string that is part of the library. You must
439  \fBpcre_maketables()\fR. See the section on locale support below.  not try to free it. The offset from the start of the pattern to the byte that
440    was being processed when the error was discovered is placed in the variable
441  This code fragment shows a typical straightforward call to \fBpcre_compile()\fR:  pointed to by \fIerroffset\fP, which must not be NULL. If it is, an immediate
442    error is given. Some errors are not detected until checks are carried out when
443    the whole pattern has been scanned; in this case the offset is set to the end
444    of the pattern.
445    .P
446    Note that the offset is in bytes, not characters, even in UTF-8 mode. It may
447    point into the middle of a UTF-8 character (for example, when
448    PCRE_ERROR_BADUTF8 is returned for an invalid UTF-8 string).
449    .P
450    If \fBpcre_compile2()\fP is used instead of \fBpcre_compile()\fP, and the
451    \fIerrorcodeptr\fP argument is not NULL, a non-zero error code number is
452    returned via this argument in the event of an error. This is in addition to the
453    textual error message. Error codes and messages are listed below.
454    .P
455    If the final argument, \fItableptr\fP, is NULL, PCRE uses a default set of
456    character tables that are built when PCRE is compiled, using the default C
457    locale. Otherwise, \fItableptr\fP must be an address that is the result of a
458    call to \fBpcre_maketables()\fP. This value is stored with the compiled
459    pattern, and used again by \fBpcre_exec()\fP, unless another table pointer is
460    passed to it. For more discussion, see the section on locale support below.
461    .P
462    This code fragment shows a typical straightforward call to \fBpcre_compile()\fP:
463    .sp
464    pcre *re;    pcre *re;
465    const char *error;    const char *error;
466    int erroffset;    int erroffset;
# Line 265  This code fragment shows a typical strai Line 470  This code fragment shows a typical strai
470      &error,           /* for error message */      &error,           /* for error message */
471      &erroffset,       /* for error offset */      &erroffset,       /* for error offset */
472      NULL);            /* use default character tables */      NULL);            /* use default character tables */
473    .sp
474  The following option bits are defined:  The following names for option bits are defined in the \fBpcre.h\fP header
475    file:
476    .sp
477    PCRE_ANCHORED    PCRE_ANCHORED
478    .sp
479  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
480  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
481  being searched (the "subject string"). This effect can also be achieved by  being searched (the "subject string"). This effect can also be achieved by
482  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
483  Perl.  Perl.
484    .sp
485      PCRE_AUTO_CALLOUT
486    .sp
487    If this bit is set, \fBpcre_compile()\fP automatically inserts callout items,
488    all with number 255, before each pattern item. For discussion of the callout
489    facility, see the
490    .\" HREF
491    \fBpcrecallout\fP
492    .\"
493    documentation.
494    .sp
495      PCRE_BSR_ANYCRLF
496      PCRE_BSR_UNICODE
497    .sp
498    These options (which are mutually exclusive) control what the \eR escape
499    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
500    match any Unicode newline sequence. The default is specified when PCRE is
501    built. It can be overridden from within the pattern, or by setting an option
502    when a compiled pattern is matched.
503    .sp
504    PCRE_CASELESS    PCRE_CASELESS
505    .sp
506  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
507  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
508  pattern by a (?i) option setting.  pattern by a (?i) option setting. In UTF-8 mode, PCRE always understands the
509    concept of case for characters whose values are less than 128, so caseless
510    matching is always possible. For characters with higher values, the concept of
511    case is supported if PCRE is compiled with Unicode property support, but not
512    otherwise. If you want to use caseless matching for characters 128 and above,
513    you must ensure that PCRE is compiled with Unicode property support as well as
514    with UTF-8 support.
515    .sp
516    PCRE_DOLLAR_ENDONLY    PCRE_DOLLAR_ENDONLY
517    .sp
518  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
519  end of the subject string. Without this option, a dollar also matches  end of the subject string. Without this option, a dollar also matches
520  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
521  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.
522  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
523  a pattern.  pattern.
524    .sp
525    PCRE_DOTALL    PCRE_DOTALL
526    .sp
527  If this bit is set, a dot metacharater in the pattern matches all characters,  If this bit is set, a dot metacharacter in the pattern matches a character of
528  including newlines. Without it, newlines are excluded. This option is  any value, including one that indicates a newline. However, it only ever
529    matches one character, even if newlines are coded as CRLF. Without this option,
530    a dot does not match when the current position is at a newline. This option is
531  equivalent to Perl's /s option, and it can be changed within a pattern by a  equivalent to Perl's /s option, and it can be changed within a pattern by a
532  (?s) option setting. A negative class such as [^a] always matches a newline  (?s) option setting. A negative class such as [^a] always matches newline
533  character, independent of the setting of this option.  characters, independent of the setting of this option.
534    .sp
535      PCRE_DUPNAMES
536    .sp
537    If this bit is set, names used to identify capturing subpatterns need not be
538    unique. This can be helpful for certain types of pattern when it is known that
539    only one instance of the named subpattern can ever be matched. There are more
540    details of named subpatterns below; see also the
541    .\" HREF
542    \fBpcrepattern\fP
543    .\"
544    documentation.
545    .sp
546    PCRE_EXTENDED    PCRE_EXTENDED
547    .sp
548  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
549  ignored except when escaped or inside a character class. Whitespace does not  ignored except when escaped or inside a character class. Whitespace does not
550  include the VT character (code 11). In addition, characters between an  include the VT character (code 11). In addition, characters between an
551  unescaped # outside a character class and the next newline character,  unescaped # outside a character class and the next newline, inclusive, are also
552  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
553  be changed within a pattern by a (?x) option setting.  pattern by a (?x) option setting.
554    .P
555    Which characters are interpreted as newlines
556    is controlled by the options passed to \fBpcre_compile()\fP or by a special
557    sequence at the start of the pattern, as described in the section entitled
558    .\" HTML <a href="pcrepattern.html#newlines">
559    .\" </a>
560    "Newline conventions"
561    .\"
562    in the \fBpcrepattern\fP documentation. Note that the end of this type of
563    comment is a literal newline sequence in the pattern; escape sequences that
564    happen to represent a newline do not count.
565    .P
566  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
567  Note, however, that this applies only to data characters. Whitespace characters  Note, however, that this applies only to data characters. Whitespace characters
568  may never appear within special character sequences in a pattern, for example  may never appear within special character sequences in a pattern, for example
569  within the sequence (?( which introduces a conditional subpattern.  within the sequence (?( that introduces a conditional subpattern.
570    .sp
571    PCRE_EXTRA    PCRE_EXTRA
572    .sp
573  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
574  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
575  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
576  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
577  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
578  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
579  controlled by this option. It can also be set by a (?X) option setting within a  give an error for this, by running it with the -w option.) There are at present
580  pattern.  no other features controlled by this option. It can also be set by a (?X)
581    option setting within a pattern.
582    .sp
583      PCRE_FIRSTLINE
584    .sp
585    If this option is set, an unanchored pattern is required to match before or at
586    the first newline in the subject string, though the matched text may continue
587    over the newline.
588    .sp
589      PCRE_JAVASCRIPT_COMPAT
590    .sp
591    If this option is set, PCRE's behaviour is changed in some ways so that it is
592    compatible with JavaScript rather than Perl. The changes are as follows:
593    .P
594    (1) A lone closing square bracket in a pattern causes a compile-time error,
595    because this is illegal in JavaScript (by default it is treated as a data
596    character). Thus, the pattern AB]CD becomes illegal when this option is set.
597    .P
598    (2) At run time, a back reference to an unset subpattern group matches an empty
599    string (by default this causes the current matching alternative to fail). A
600    pattern such as (\e1)(a) succeeds when this option is set (assuming it can find
601    an "a" in the subject), whereas it fails by default, for Perl compatibility.
602    .sp
603    PCRE_MULTILINE    PCRE_MULTILINE
604    .sp
605  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
606  characters (even if it actually contains several newlines). The "start of line"  characters (even if it actually contains newlines). The "start of line"
607  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
608  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
609  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
610  Perl.  Perl.
611    .P
612  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
613  match immediately following or immediately before any newline in the subject  match immediately following or immediately before internal newlines in the
614  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
615  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
616  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
617  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.
618    .sp
619      PCRE_NEWLINE_CR
620      PCRE_NEWLINE_LF
621      PCRE_NEWLINE_CRLF
622      PCRE_NEWLINE_ANYCRLF
623      PCRE_NEWLINE_ANY
624    .sp
625    These options override the default newline definition that was chosen when PCRE
626    was built. Setting the first or the second specifies that a newline is
627    indicated by a single character (CR or LF, respectively). Setting
628    PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
629    CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three
630    preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies
631    that any Unicode newline sequence should be recognized. The Unicode newline
632    sequences are the three just mentioned, plus the single characters VT (vertical
633    tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS (line
634    separator, U+2028), and PS (paragraph separator, U+2029). The last two are
635    recognized only in UTF-8 mode.
636    .P
637    The newline setting in the options word uses three bits that are treated
638    as a number, giving eight possibilities. Currently only six are used (default
639    plus the five values above). This means that if you set more than one newline
640    option, the combination may or may not be sensible. For example,
641    PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
642    other combinations may yield unused numbers and cause an error.
643    .P
644    The only time that a line break in a pattern is specially recognized when
645    compiling is when PCRE_EXTENDED is set. CR and LF are whitespace characters,
646    and so are ignored in this mode. Also, an unescaped # outside a character class
647    indicates a comment that lasts until after the next line break sequence. In
648    other circumstances, line break sequences in patterns are treated as literal
649    data.
650    .P
651    The newline option that is set at compile time becomes the default that is used
652    for \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, but it can be overridden.
653    .sp
654    PCRE_NO_AUTO_CAPTURE    PCRE_NO_AUTO_CAPTURE
655    .sp
656  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
657  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
658  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
659  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
660  in Perl.  in Perl.
661    .sp
662      NO_START_OPTIMIZE
663    .sp
664    This is an option that acts at matching time; that is, it is really an option
665    for \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. If it is set at compile time,
666    it is remembered with the compiled pattern and assumed at matching time. For
667    details see the discussion of PCRE_NO_START_OPTIMIZE
668    .\" HTML <a href="#execoptions">
669    .\" </a>
670    below.
671    .\"
672    .sp
673      PCRE_UCP
674    .sp
675    This option changes the way PCRE processes \eB, \eb, \eD, \ed, \eS, \es, \eW,
676    \ew, and some of the POSIX character classes. By default, only ASCII characters
677    are recognized, but if PCRE_UCP is set, Unicode properties are used instead to
678    classify characters. More details are given in the section on
679    .\" HTML <a href="pcre.html#genericchartypes">
680    .\" </a>
681    generic character types
682    .\"
683    in the
684    .\" HREF
685    \fBpcrepattern\fP
686    .\"
687    page. If you set PCRE_UCP, matching one of the items it affects takes much
688    longer. The option is available only if PCRE has been compiled with Unicode
689    property support.
690    .sp
691    PCRE_UNGREEDY    PCRE_UNGREEDY
692    .sp
693  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
694  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
695  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.
696    .sp
697    PCRE_UTF8    PCRE_UTF8
698    .sp
699  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
700  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
701  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
702  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
703  behaviour of PCRE are given in the  behaviour of PCRE are given in the
704  .\" HTML <a href="pcre.html#utf8support">  .\" HTML <a href="pcre.html#utf8support">
# Line 367  section on UTF-8 support Line 707  section on UTF-8 support
707  .\"  .\"
708  in the main  in the main
709  .\" HREF  .\" HREF
710  \fBpcre\fR  \fBpcre\fP
711  .\"  .\"
712  page.  page.
713    .sp
714  .SH STUDYING A PATTERN    PCRE_NO_UTF8_CHECK
715    .sp
716    When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
717    automatically checked. There is a discussion about the
718    .\" HTML <a href="pcre.html#utf8strings">
719    .\" </a>
720    validity of UTF-8 strings
721    .\"
722    in the main
723    .\" HREF
724    \fBpcre\fP
725    .\"
726    page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_compile()\fP
727    returns an error. If you already know that your pattern is valid, and you want
728    to skip this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK
729    option. When it is set, the effect of passing an invalid UTF-8 string as a
730    pattern is undefined. It may cause your program to crash. Note that this option
731    can also be passed to \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, to suppress
732    the UTF-8 validity checking of subject strings.
733    .
734    .
735    .SH "COMPILATION ERROR CODES"
736    .rs
737    .sp
738    The following table lists the error codes than may be returned by
739    \fBpcre_compile2()\fP, along with the error messages that may be returned by
740    both compiling functions. As PCRE has developed, some error codes have fallen
741    out of use. To avoid confusion, they have not been re-used.
742    .sp
743       0  no error
744       1  \e at end of pattern
745       2  \ec at end of pattern
746       3  unrecognized character follows \e
747       4  numbers out of order in {} quantifier
748       5  number too big in {} quantifier
749       6  missing terminating ] for character class
750       7  invalid escape sequence in character class
751       8  range out of order in character class
752       9  nothing to repeat
753      10  [this code is not in use]
754      11  internal error: unexpected repeat
755      12  unrecognized character after (? or (?-
756      13  POSIX named classes are supported only within a class
757      14  missing )
758      15  reference to non-existent subpattern
759      16  erroffset passed as NULL
760      17  unknown option bit(s) set
761      18  missing ) after comment
762      19  [this code is not in use]
763      20  regular expression is too large
764      21  failed to get memory
765      22  unmatched parentheses
766      23  internal error: code overflow
767      24  unrecognized character after (?<
768      25  lookbehind assertion is not fixed length
769      26  malformed number or name after (?(
770      27  conditional group contains more than two branches
771      28  assertion expected after (?(
772      29  (?R or (?[+-]digits must be followed by )
773      30  unknown POSIX class name
774      31  POSIX collating elements are not supported
775      32  this version of PCRE is not compiled with PCRE_UTF8 support
776      33  [this code is not in use]
777      34  character value in \ex{...} sequence is too large
778      35  invalid condition (?(0)
779      36  \eC not allowed in lookbehind assertion
780      37  PCRE does not support \eL, \el, \eN, \eU, or \eu
781      38  number after (?C is > 255
782      39  closing ) for (?C expected
783      40  recursive call could loop indefinitely
784      41  unrecognized character after (?P
785      42  syntax error in subpattern name (missing terminator)
786      43  two named subpatterns have the same name
787      44  invalid UTF-8 string
788      45  support for \eP, \ep, and \eX has not been compiled
789      46  malformed \eP or \ep sequence
790      47  unknown property name after \eP or \ep
791      48  subpattern name is too long (maximum 32 characters)
792      49  too many named subpatterns (maximum 10000)
793      50  [this code is not in use]
794      51  octal value is greater than \e377 (not in UTF-8 mode)
795      52  internal error: overran compiling workspace
796      53  internal error: previously-checked referenced subpattern
797            not found
798      54  DEFINE group contains more than one branch
799      55  repeating a DEFINE group is not allowed
800      56  inconsistent NEWLINE options
801      57  \eg is not followed by a braced, angle-bracketed, or quoted
802            name/number or by a plain number
803      58  a numbered reference must not be zero
804      59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
805      60  (*VERB) not recognized
806      61  number is too big
807      62  subpattern name expected
808      63  digit expected after (?+
809      64  ] is an invalid data character in JavaScript compatibility mode
810      65  different names for subpatterns of the same number are
811            not allowed
812      66  (*MARK) must have an argument
813      67  this version of PCRE is not compiled with PCRE_UCP support
814    .sp
815    The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
816    be used if the limits were changed when PCRE was built.
817    .
818    .
819    .SH "STUDYING A PATTERN"
820  .rs  .rs
821  .sp  .sp
822  .B pcre_extra *pcre_study(const pcre *\fIcode\fR, int \fIoptions\fR,  .B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP
823  .ti +5n  .ti +5n
824  .B const char **\fIerrptr\fR);  .B const char **\fIerrptr\fP);
825  .PP  .PP
826  When a pattern is going to be used several times, it is worth spending more  If a compiled pattern is going to be used several times, it is worth spending
827  time analyzing it in order to speed up the time taken for matching. The  more time analyzing it in order to speed up the time taken for matching. The
828  function \fBpcre_study()\fR takes a pointer to a compiled pattern as its first  function \fBpcre_study()\fP takes a pointer to a compiled pattern as its first
829  argument. If studing the pattern produces additional information that will help  argument. If studying the pattern produces additional information that will
830  speed up matching, \fBpcre_study()\fR returns a pointer to a \fBpcre_extra\fR  help speed up matching, \fBpcre_study()\fP returns a pointer to a
831  block, in which the \fIstudy_data\fR field points to the results of the study.  \fBpcre_extra\fP block, in which the \fIstudy_data\fP field points to the
832    results of the study.
833  The returned value from a \fBpcre_study()\fR can be passed directly to  .P
834  \fBpcre_exec()\fR. However, the \fBpcre_extra\fR block also contains other  The returned value from \fBpcre_study()\fP can be passed directly to
835  fields that can be set by the caller before the block is passed; these are  \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. However, a \fBpcre_extra\fP block
836  described below. If studying the pattern does not produce any additional  also contains other fields that can be set by the caller before the block is
837  information, \fBpcre_study()\fR returns NULL. In that circumstance, if the  passed; these are described
838  calling program wants to pass some of the other fields to \fBpcre_exec()\fR, it  .\" HTML <a href="#extradata">
839  must set up its own \fBpcre_extra\fR block.  .\" </a>
840    below
841  The second argument contains option bits. At present, no options are defined  .\"
842  for \fBpcre_study()\fR, and this argument should always be zero.  in the section on matching a pattern.
843    .P
844  The third argument for \fBpcre_study()\fR is a pointer for an error message. If  If studying the pattern does not produce any useful information,
845    \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program
846    wants to pass any of the other fields to \fBpcre_exec()\fP or
847    \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block.
848    .P
849    The second argument of \fBpcre_study()\fP contains option bits. At present, no
850    options are defined, and this argument should always be zero.
851    .P
852    The third argument for \fBpcre_study()\fP is a pointer for an error message. If
853  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
854  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
855  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
856  be sure that it has run successfully.  should test the error pointer for NULL after calling \fBpcre_study()\fP, to be
857    sure that it has run successfully.
858  This is a typical call to \fBpcre_study\fR():  .P
859    This is a typical call to \fBpcre_study\fP():
860    .sp
861    pcre_extra *pe;    pcre_extra *pe;
862    pe = pcre_study(    pe = pcre_study(
863      re,             /* result of pcre_compile() */      re,             /* result of pcre_compile() */
864      0,              /* no options exist */      0,              /* no options exist */
865      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
866    .sp
867  At present, studying a pattern is useful only for non-anchored patterns that do  Studying a pattern does two things: first, a lower bound for the length of
868  not have a single fixed starting character. A bitmap of possible starting  subject string that is needed to match the pattern is computed. This does not
869  characters is created.  mean that there are any strings of that length that match, but it does
870    guarantee that no shorter strings match. The value is used by
871    \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP to avoid wasting time by trying to
872    match strings that are shorter than the lower bound. You can find out the value
873    in a calling program via the \fBpcre_fullinfo()\fP function.
874    .P
875    Studying a pattern is also useful for non-anchored patterns that do not have a
876    single fixed starting character. A bitmap of possible starting bytes is
877    created. This speeds up finding a position in the subject at which to start
878    matching.
879    .P
880    The two optimizations just described can be disabled by setting the
881    PCRE_NO_START_OPTIMIZE option when calling \fBpcre_exec()\fP or
882    \fBpcre_dfa_exec()\fP. You might want to do this if your pattern contains
883    callouts or (*MARK), and you want to make use of these facilities in cases
884    where matching fails. See the discussion of PCRE_NO_START_OPTIMIZE
885    .\" HTML <a href="#execoptions">
886    .\" </a>
887    below.
888    .\"
889    .
890    .
891  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
892  .SH LOCALE SUPPORT  .SH "LOCALE SUPPORT"
893  .rs  .rs
894  .sp  .sp
895  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters,
896  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
897  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
898  contains a default set of tables that is created in the default C locale when  less than 128. By default, higher-valued codes never match escapes such as \ew
899  PCRE is compiled. This is used when the final argument of \fBpcre_compile()\fR  or \ed, but they can be tested with \ep if PCRE is built with Unicode character
900  is NULL, and is sufficient for many applications.  property support. Alternatively, the PCRE_UCP option can be set at compile
901    time; this causes \ew and friends to use Unicode property support instead of
902  An alternative set of tables can, however, be supplied. Such tables are built  built-in tables. The use of locales with Unicode is discouraged. If you are
903  by calling the \fBpcre_maketables()\fR function, which has no arguments, in the  handling characters with codes greater than 128, you should either use UTF-8
904  relevant locale. The result can then be passed to \fBpcre_compile()\fR as often  and Unicode, or use locales, but not try to mix the two.
905  as necessary. For example, to build and use tables that are appropriate for the  .P
906  French locale (where accented characters with codes greater than 128 are  PCRE contains an internal set of tables that are used when the final argument
907  treated as letters), the following code could be used:  of \fBpcre_compile()\fP is NULL. These are sufficient for many applications.
908    Normally, the internal tables recognize only ASCII characters. However, when
909    setlocale(LC_CTYPE, "fr");  PCRE is built, it is possible to cause the internal tables to be rebuilt in the
910    default "C" locale of the local system, which may cause them to be different.
911    .P
912    The internal tables can always be overridden by tables supplied by the
913    application that calls PCRE. These may be created in a different locale from
914    the default. As more and more applications change to using Unicode, the need
915    for this locale support is expected to die away.
916    .P
917    External tables are built by calling the \fBpcre_maketables()\fP function,
918    which has no arguments, in the relevant locale. The result can then be passed
919    to \fBpcre_compile()\fP or \fBpcre_exec()\fP as often as necessary. For
920    example, to build and use tables that are appropriate for the French locale
921    (where accented characters with values greater than 128 are treated as letters),
922    the following code could be used:
923    .sp
924      setlocale(LC_CTYPE, "fr_FR");
925    tables = pcre_maketables();    tables = pcre_maketables();
926    re = pcre_compile(..., tables);    re = pcre_compile(..., tables);
927    .sp
928  The tables are built in memory that is obtained via \fBpcre_malloc\fR. The  The locale name "fr_FR" is used on Linux and other Unix-like systems; if you
929  pointer that is passed to \fBpcre_compile\fR is saved with the compiled  are using Windows, the name for the French locale is "french".
930  pattern, and the same tables are used via this pointer by \fBpcre_study()\fR  .P
931  and \fBpcre_exec()\fR. Thus, for any single pattern, compilation, studying and  When \fBpcre_maketables()\fP runs, the tables are built in memory that is
932  matching all happen in the same locale, but different patterns can be compiled  obtained via \fBpcre_malloc\fP. It is the caller's responsibility to ensure
933  in different locales. It is the caller's responsibility to ensure that the  that the memory containing the tables remains available for as long as it is
934  memory containing the tables remains available for as long as it is needed.  needed.
935    .P
936  .SH INFORMATION ABOUT A PATTERN  The pointer that is passed to \fBpcre_compile()\fP is saved with the compiled
937    pattern, and the same tables are used via this pointer by \fBpcre_study()\fP
938    and normally also by \fBpcre_exec()\fP. Thus, by default, for any single
939    pattern, compilation, studying and matching all happen in the same locale, but
940    different patterns can be compiled in different locales.
941    .P
942    It is possible to pass a table pointer or NULL (indicating the use of the
943    internal tables) to \fBpcre_exec()\fP. Although not intended for this purpose,
944    this facility could be used to match a pattern in a different locale from the
945    one in which it was compiled. Passing table pointers at run time is discussed
946    below in the section on matching a pattern.
947    .
948    .
949    .SH "INFORMATION ABOUT A PATTERN"
950  .rs  .rs
951  .sp  .sp
952  .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,"
953  .ti +5n  .ti +5n
954  .B int \fIwhat\fR, void *\fIwhere\fR);  .B int \fIwhat\fP, void *\fIwhere\fP);
955  .PP  .PP
956  The \fBpcre_fullinfo()\fR function returns information about a compiled  The \fBpcre_fullinfo()\fP function returns information about a compiled
957  pattern. It replaces the obsolete \fBpcre_info()\fR function, which is  pattern. It replaces the obsolete \fBpcre_info()\fP function, which is
958  nevertheless retained for backwards compability (and is documented below).  nevertheless retained for backwards compability (and is documented below).
959    .P
960  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
961  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
962  the pattern was not studied. The third argument specifies which piece of  the pattern was not studied. The third argument specifies which piece of
963  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
964  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
965  the following negative numbers:  the following negative numbers:
966    .sp
967    PCRE_ERROR_NULL       the argument \fIcode\fR was NULL    PCRE_ERROR_NULL       the argument \fIcode\fP was NULL
968                          the argument \fIwhere\fR was NULL                          the argument \fIwhere\fP was NULL
969    PCRE_ERROR_BADMAGIC   the "magic number" was not found    PCRE_ERROR_BADMAGIC   the "magic number" was not found
970    PCRE_ERROR_BADOPTION  the value of \fIwhat\fR was invalid    PCRE_ERROR_BADOPTION  the value of \fIwhat\fP was invalid
971    .sp
972  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
973  compiled pattern:  check against passing an arbitrary memory pointer. Here is a typical call of
974    \fBpcre_fullinfo()\fP, to obtain the length of the compiled pattern:
975    .sp
976    int rc;    int rc;
977    unsigned long int length;    size_t length;
978    rc = pcre_fullinfo(    rc = pcre_fullinfo(
979      re,               /* result of pcre_compile() */      re,               /* result of pcre_compile() */
980      pe,               /* result of pcre_study(), or NULL */      pe,               /* result of pcre_study(), or NULL */
981      PCRE_INFO_SIZE,   /* what is required */      PCRE_INFO_SIZE,   /* what is required */
982      &length);         /* where to put the data */      &length);         /* where to put the data */
983    .sp
984  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
985  as follows:  as follows:
986    .sp
987    PCRE_INFO_BACKREFMAX    PCRE_INFO_BACKREFMAX
988    .sp
989  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
990  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
991  no back references.  no back references.
992    .sp
993    PCRE_INFO_CAPTURECOUNT    PCRE_INFO_CAPTURECOUNT
994    .sp
995  Return the number of capturing subpatterns in the pattern. The fourth argument  Return the number of capturing subpatterns in the pattern. The fourth argument
996  should point to an \fbint\fR variable.  should point to an \fBint\fP variable.
997    .sp
998      PCRE_INFO_DEFAULT_TABLES
999    .sp
1000    Return a pointer to the internal default character tables within PCRE. The
1001    fourth argument should point to an \fBunsigned char *\fP variable. This
1002    information call is provided for internal use by the \fBpcre_study()\fP
1003    function. External callers can cause PCRE to use its internal tables by passing
1004    a NULL table pointer.
1005    .sp
1006    PCRE_INFO_FIRSTBYTE    PCRE_INFO_FIRSTBYTE
1007    .sp
1008  Return information about the first byte of any matched string, for a  Return information about the first byte of any matched string, for a
1009  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
1010  old name is still recognized for backwards compatibility.)  variable. (This option used to be called PCRE_INFO_FIRSTCHAR; the old name is
1011    still recognized for backwards compatibility.)
1012  If there is a fixed first byte, e.g. from a pattern such as (cat|cow|coyote),  .P
1013  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
1014    (cat|cow|coyote), its value is returned. Otherwise, if either
1015    .sp
1016  (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
1017  starts with "^", or  starts with "^", or
1018    .sp
1019  (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
1020  (if it were set, the pattern would be anchored),  (if it were set, the pattern would be anchored),
1021    .sp
1022  -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
1023  subject string or after any newline within the string. Otherwise -2 is  subject string or after any newline within the string. Otherwise -2 is
1024  returned. For anchored patterns, -2 is returned.  returned. For anchored patterns, -2 is returned.
1025    .sp
1026    PCRE_INFO_FIRSTTABLE    PCRE_INFO_FIRSTTABLE
1027    .sp
1028  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
1029  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
1030  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
1031  fourth argument should point to an \fBunsigned char *\fR variable.  fourth argument should point to an \fBunsigned char *\fP variable.
1032    .sp
1033      PCRE_INFO_HASCRORLF
1034    .sp
1035    Return 1 if the pattern contains any explicit matches for CR or LF characters,
1036    otherwise 0. The fourth argument should point to an \fBint\fP variable. An
1037    explicit match is either a literal CR or LF character, or \er or \en.
1038    .sp
1039      PCRE_INFO_JCHANGED
1040    .sp
1041    Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise
1042    0. The fourth argument should point to an \fBint\fP variable. (?J) and
1043    (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
1044    .sp
1045    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
1046    .sp
1047  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
1048  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
1049  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
1050  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
1051  follows something of variable length. For example, for the pattern  follows something of variable length. For example, for the pattern
1052  /^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
1053  is -1.  is -1.
1054    .sp
1055      PCRE_INFO_MINLENGTH
1056    .sp
1057    If the pattern was studied and a minimum length for matching subject strings
1058    was computed, its value is returned. Otherwise the returned value is -1. The
1059    value is a number of characters, not bytes (this may be relevant in UTF-8
1060    mode). The fourth argument should point to an \fBint\fP variable. A
1061    non-negative value is a lower bound to the length of any matching string. There
1062    may not be any strings of that length that do actually match, but every string
1063    that does match is at least that long.
1064    .sp
1065    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
1066    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
1067    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
1068    .sp
1069  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
1070  names are just an additional way of identifying the parentheses, which still  names are just an additional way of identifying the parentheses, which still
1071  acquire a number. A caller that wants to extract data from a named subpattern  acquire numbers. Several convenience functions such as
1072  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
1073  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
1074  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
1075  table for the pattern.  output vector (described with \fBpcre_exec()\fP below). To do the conversion,
1076    you need to use the name-to-number map, which is described by these three
1077    values.
1078    .P
1079  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
1080  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
1081  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
1082  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
1083  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
1084  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
1085  rest of the entry is the corresponding name, zero terminated. The names are in  rest of the entry is the corresponding name, zero terminated.
1086  alphabetical order. For example, consider the following pattern (assume  .P
1087  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  The names are in alphabetical order. Duplicate names may appear if (?| is used
1088    to create multiple groups with the same number, as described in the
1089    (?P<date> (?P<year>(\\d\\d)?\\d\\d) -  .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1090    (?P<month>\\d\\d) - (?P<day>\\d\\d) )  .\" </a>
1091    section on duplicate subpattern numbers
1092    .\"
1093    in the
1094    .\" HREF
1095    \fBpcrepattern\fP
1096    .\"
1097    page. Duplicate names for subpatterns with different numbers are permitted only
1098    if PCRE_DUPNAMES is set. In all cases of duplicate names, they appear in the
1099    table in the order in which they were found in the pattern. In the absence of
1100    (?| this is the order of increasing number; when (?| is used this is not
1101    necessarily the case because later subpatterns may have lower numbers.
1102    .P
1103    As a simple example of the name/number table, consider the following pattern
1104    (assume PCRE_EXTENDED is set, so white space - including newlines - is
1105    ignored):
1106    .sp
1107    .\" JOIN
1108      (?<date> (?<year>(\ed\ed)?\ed\ed) -
1109      (?<month>\ed\ed) - (?<day>\ed\ed) )
1110    .sp
1111  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
1112  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
1113  bytes shows in hex, and undefined bytes shown as ??:  bytes shows in hexadecimal, and undefined bytes shown as ??:
1114    .sp
1115    00 01 d  a  t  e  00 ??    00 01 d  a  t  e  00 ??
1116    00 05 d  a  y  00 ?? ??    00 05 d  a  y  00 ?? ??
1117    00 04 m  o  n  t  h  00    00 04 m  o  n  t  h  00
1118    00 02 y  e  a  r  00 ??    00 02 y  e  a  r  00 ??
1119    .sp
1120  When writing code to extract data from named subpatterns, remember that the  When writing code to extract data from named subpatterns using the
1121  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
1122    different for each compiled pattern.
1123    .sp
1124      PCRE_INFO_OKPARTIAL
1125    .sp
1126    Return 1 if the pattern can be used for partial matching with
1127    \fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
1128    \fBint\fP variable. From release 8.00, this always returns 1, because the
1129    restrictions that previously applied to partial matching have been lifted. The
1130    .\" HREF
1131    \fBpcrepartial\fP
1132    .\"
1133    documentation gives details of partial matching.
1134    .sp
1135    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1136    .sp
1137  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
1138  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
1139  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
1140  top-level option settings within the pattern itself.  top-level option settings at the start of the pattern itself. In other words,
1141    they are the options that will be in force when matching starts. For example,
1142    if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED option, the
1143    result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED.
1144    .P
1145  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
1146  alternatives begin with one of the following:  alternatives begin with one of the following:
1147    .sp
1148    ^     unless PCRE_MULTILINE is set    ^     unless PCRE_MULTILINE is set
1149    \\A    always    \eA    always
1150    \\G    always    \eG    always
1151    .\" JOIN
1152    .*    if PCRE_DOTALL is set and there are no back    .*    if PCRE_DOTALL is set and there are no back
1153            references to the subpattern in which .* appears            references to the subpattern in which .* appears
1154    .sp
1155  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
1156  \fBpcre_fullinfo()\fR.  \fBpcre_fullinfo()\fP.
1157    .sp
1158    PCRE_INFO_SIZE    PCRE_INFO_SIZE
1159    .sp
1160  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
1161  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
1162  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
1163  variable.  variable.
1164    .sp
1165    PCRE_INFO_STUDYSIZE    PCRE_INFO_STUDYSIZE
1166    .sp
1167  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
1168  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
1169  \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
1170  created by \fBpcre_study()\fR. The fourth argument should point to a  created by \fBpcre_study()\fP. If \fBpcre_extra\fP is NULL, or there is no
1171  \fBsize_t\fR variable.  study data, zero is returned. The fourth argument should point to a
1172    \fBsize_t\fP variable.
1173  .SH OBSOLETE INFO FUNCTION  .
1174    .
1175    .SH "OBSOLETE INFO FUNCTION"
1176  .rs  .rs
1177  .sp  .sp
1178  .B int pcre_info(const pcre *\fIcode\fR, int *\fIoptptr\fR, int  .B int pcre_info(const pcre *\fIcode\fP, int *\fIoptptr\fP, int
1179  .B *\fIfirstcharptr\fR);  .B *\fIfirstcharptr\fP);
1180  .PP  .PP
1181  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
1182  restrictive to return all the available data about a compiled pattern. New  restrictive to return all the available data about a compiled pattern. New
1183  programs should use \fBpcre_fullinfo()\fR instead. The yield of  programs should use \fBpcre_fullinfo()\fP instead. The yield of
1184  \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
1185  following negative numbers:  following negative numbers:
1186    .sp
1187    PCRE_ERROR_NULL       the argument \fIcode\fR was NULL    PCRE_ERROR_NULL       the argument \fIcode\fP was NULL
1188    PCRE_ERROR_BADMAGIC   the "magic number" was not found    PCRE_ERROR_BADMAGIC   the "magic number" was not found
1189    .sp
1190  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
1191  pattern was compiled is placed in the integer it points to (see  pattern was compiled is placed in the integer it points to (see
1192  PCRE_INFO_OPTIONS above).  PCRE_INFO_OPTIONS above).
1193    .P
1194  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,
1195  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
1196  string (see PCRE_INFO_FIRSTBYTE above).  string (see PCRE_INFO_FIRSTBYTE above).
1197    .
1198  .SH MATCHING A PATTERN  .
1199    .SH "REFERENCE COUNTS"
1200  .rs  .rs
1201  .sp  .sp
1202  .B int pcre_exec(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"  .B int pcre_refcount(pcre *\fIcode\fP, int \fIadjust\fP);
1203    .PP
1204    The \fBpcre_refcount()\fP function is used to maintain a reference count in the
1205    data block that contains a compiled pattern. It is provided for the benefit of
1206    applications that operate in an object-oriented manner, where different parts
1207    of the application may be using the same compiled pattern, but you want to free
1208    the block when they are all done.
1209    .P
1210    When a pattern is compiled, the reference count field is initialized to zero.
1211    It is changed only by calling this function, whose action is to add the
1212    \fIadjust\fP value (which may be positive or negative) to it. The yield of the
1213    function is the new value. However, the value of the count is constrained to
1214    lie between 0 and 65535, inclusive. If the new value is outside these limits,
1215    it is forced to the appropriate limit value.
1216    .P
1217    Except when it is zero, the reference count is not correctly preserved if a
1218    pattern is compiled on one host and then transferred to a host whose byte-order
1219    is different. (This seems a highly unlikely scenario.)
1220    .
1221    .
1222    .SH "MATCHING A PATTERN: THE TRADITIONAL FUNCTION"
1223    .rs
1224    .sp
1225    .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
1226  .ti +5n  .ti +5n
1227  .B "const char *\fIsubject\fR," int \fIlength\fR, int \fIstartoffset\fR,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
1228  .ti +5n  .ti +5n
1229  .B int \fIoptions\fR, int *\fIovector\fR, int \fIovecsize\fR);  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
1230  .PP  .P
1231  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
1232  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
1233  pattern has been studied, the result of the study should be passed in the  pattern was studied, the result of the study should be passed in the
1234  \fIextra\fR argument.  \fIextra\fP argument. This function is the main matching facility of the
1235    library, and it operates in a Perl-like manner. For specialist use there is
1236  Here is an example of a simple call to \fBpcre_exec()\fR:  also an alternative matching function, which is described
1237    .\" HTML <a href="#dfamatch">
1238    .\" </a>
1239    below
1240    .\"
1241    in the section about the \fBpcre_dfa_exec()\fP function.
1242    .P
1243    In most applications, the pattern will have been compiled (and optionally
1244    studied) in the same process that calls \fBpcre_exec()\fP. However, it is
1245    possible to save compiled patterns and study data, and then use them later
1246    in different processes, possibly even on different hosts. For a discussion
1247    about this, see the
1248    .\" HREF
1249    \fBpcreprecompile\fP
1250    .\"
1251    documentation.
1252    .P
1253    Here is an example of a simple call to \fBpcre_exec()\fP:
1254    .sp
1255    int rc;    int rc;
1256    int ovector[30];    int ovector[30];
1257    rc = pcre_exec(    rc = pcre_exec(
# Line 647  Here is an example of a simple call to \ Line 1261  Here is an example of a simple call to \
1261      11,             /* the length of the subject string */      11,             /* the length of the subject string */
1262      0,              /* start at offset 0 in the subject */      0,              /* start at offset 0 in the subject */
1263      0,              /* default options */      0,              /* default options */
1264      ovector,        /* vector for substring information */      ovector,        /* vector of integers for substring information */
1265      30);            /* number of elements in the vector */      30);            /* number of elements (NOT size in bytes) */
1266    .
1267  If the \fIextra\fR argument is not NULL, it must point to a \fBpcre_extra\fR  .\" HTML <a name="extradata"></a>
1268  data block. The \fBpcre_study()\fR function returns such a block (when it  .SS "Extra data for \fBpcre_exec()\fR"
1269    .rs
1270    .sp
1271    If the \fIextra\fP argument is not NULL, it must point to a \fBpcre_extra\fP
1272    data block. The \fBpcre_study()\fP function returns such a block (when it
1273  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
1274  additional information in it. The fields in the block are as follows:  additional information in it. The \fBpcre_extra\fP block contains the following
1275    fields (not necessarily in this order):
1276    unsigned long int \fIflags\fR;  .sp
1277    void *\fIstudy_data\fR;    unsigned long int \fIflags\fP;
1278    unsigned long int \fImatch_limit\fR;    void *\fIstudy_data\fP;
1279    void *\fIcallout_data\fR;    unsigned long int \fImatch_limit\fP;
1280      unsigned long int \fImatch_limit_recursion\fP;
1281  The \fIflags\fR field is a bitmap that specifies which of the other fields    void *\fIcallout_data\fP;
1282      const unsigned char *\fItables\fP;
1283      unsigned char **\fImark\fP;
1284    .sp
1285    The \fIflags\fP field is a bitmap that specifies which of the other fields
1286  are set. The flag bits are:  are set. The flag bits are:
1287    .sp
1288    PCRE_EXTRA_STUDY_DATA    PCRE_EXTRA_STUDY_DATA
1289    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1290      PCRE_EXTRA_MATCH_LIMIT_RECURSION
1291    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1292      PCRE_EXTRA_TABLES
1293  Other flag bits should be set to zero. The \fIstudy_data\fR field is set in the    PCRE_EXTRA_MARK
1294  \fBpcre_extra\fR block that is returned by \fBpcre_study()\fR, together with  .sp
1295  the appropriate flag bit. You should not set this yourself, but you can add to  Other flag bits should be set to zero. The \fIstudy_data\fP field is set in the
1296  the block by setting the other fields.  \fBpcre_extra\fP block that is returned by \fBpcre_study()\fP, together with
1297    the appropriate flag bit. You should not set this yourself, but you may add to
1298  The \fImatch_limit\fR field provides a means of preventing PCRE from using up a  the block by setting the other fields and their corresponding flag bits.
1299    .P
1300    The \fImatch_limit\fP field provides a means of preventing PCRE from using up a
1301  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,
1302  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
1303  classic example is the use of nested unlimited repeats. Internally, PCRE uses a  classic example is a pattern that uses nested unlimited repeats.
1304  function called \fBmatch()\fR which it calls repeatedly (sometimes  .P
1305  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
1306  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
1307  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
1308  count starts from zero for each position in the subject string.  limiting the amount of backtracking that can take place. For patterns that are
1309    not anchored, the count restarts from zero for each position in the subject
1310  The default limit for the library can be set when PCRE is built; the default  string.
1311    .P
1312    The default value for the limit can be set when PCRE is built; the default
1313  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
1314  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
1315  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
1316  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
1317  exceeded, \fBpcre_exec()\fR returns PCRE_ERROR_MATCHLIMIT.  PCRE_ERROR_MATCHLIMIT.
1318    .P
1319  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
1320  which is described in the \fBpcrecallout\fR documentation.  instead of limiting the total number of times that \fBmatch()\fP is called, it
1321    limits the depth of recursion. The recursion depth is a smaller number than the
1322  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.
1323  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.
1324  first matching position. However, if a pattern was compiled with PCRE_ANCHORED,  .P
1325  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,
1326  unachored at matching time.  when PCRE has been compiled to use memory on the heap instead of the stack, the
1327    amount of heap memory that can be used.
1328  There are also three further options that can be set only at matching time:  .P
1329    The default value for \fImatch_limit_recursion\fP can be set when PCRE is
1330    built; the default default is the same value as the default for
1331    \fImatch_limit\fP. You can override the default by suppling \fBpcre_exec()\fP
1332    with a \fBpcre_extra\fP block in which \fImatch_limit_recursion\fP is set, and
1333    PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the \fIflags\fP field. If the limit
1334    is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1335    .P
1336    The \fIcallout_data\fP field is used in conjunction with the "callout" feature,
1337    and is described in the
1338    .\" HREF
1339    \fBpcrecallout\fP
1340    .\"
1341    documentation.
1342    .P
1343    The \fItables\fP field is used to pass a character tables pointer to
1344    \fBpcre_exec()\fP; this overrides the value that is stored with the compiled
1345    pattern. A non-NULL value is stored with the compiled pattern only if custom
1346    tables were supplied to \fBpcre_compile()\fP via its \fItableptr\fP argument.
1347    If NULL is passed to \fBpcre_exec()\fP using this mechanism, it forces PCRE's
1348    internal tables to be used. This facility is helpful when re-using patterns
1349    that have been saved after compiling with an external set of tables, because
1350    the external tables might be at a different address when \fBpcre_exec()\fP is
1351    called. See the
1352    .\" HREF
1353    \fBpcreprecompile\fP
1354    .\"
1355    documentation for a discussion of saving compiled patterns for later use.
1356    .P
1357    If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1358    be set to point to a \fBchar *\fP variable. If the pattern contains any
1359    backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1360    a name to pass back, a pointer to the name string (zero terminated) is placed
1361    in the variable pointed to by the \fImark\fP field. The names are within the
1362    compiled pattern; if you wish to retain such a name you must copy it before
1363    freeing the memory of a compiled pattern. If there is no name to pass back, the
1364    variable pointed to by the \fImark\fP field set to NULL. For details of the
1365    backtracking control verbs, see the section entitled
1366    .\" HTML <a href="pcrepattern#backtrackcontrol">
1367    .\" </a>
1368    "Backtracking control"
1369    .\"
1370    in the
1371    .\" HREF
1372    \fBpcrepattern\fP
1373    .\"
1374    documentation.
1375    .
1376    .
1377    .\" HTML <a name="execoptions"></a>
1378    .SS "Option bits for \fBpcre_exec()\fP"
1379    .rs
1380    .sp
1381    The unused bits of the \fIoptions\fP argument for \fBpcre_exec()\fP must be
1382    zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
1383    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1384    PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
1385    PCRE_PARTIAL_HARD.
1386    .sp
1387      PCRE_ANCHORED
1388    .sp
1389    The PCRE_ANCHORED option limits \fBpcre_exec()\fP to matching at the first
1390    matching position. If a pattern was compiled with PCRE_ANCHORED, or turned out
1391    to be anchored by virtue of its contents, it cannot be made unachored at
1392    matching time.
1393    .sp
1394      PCRE_BSR_ANYCRLF
1395      PCRE_BSR_UNICODE
1396    .sp
1397    These options (which are mutually exclusive) control what the \eR escape
1398    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
1399    match any Unicode newline sequence. These options override the choice that was
1400    made or defaulted when the pattern was compiled.
1401    .sp
1402      PCRE_NEWLINE_CR
1403      PCRE_NEWLINE_LF
1404      PCRE_NEWLINE_CRLF
1405      PCRE_NEWLINE_ANYCRLF
1406      PCRE_NEWLINE_ANY
1407    .sp
1408    These options override the newline definition that was chosen or defaulted when
1409    the pattern was compiled. For details, see the description of
1410    \fBpcre_compile()\fP above. During matching, the newline choice affects the
1411    behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1412    the way the match position is advanced after a match failure for an unanchored
1413    pattern.
1414    .P
1415    When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a
1416    match attempt for an unanchored pattern fails when the current position is at a
1417    CRLF sequence, and the pattern contains no explicit matches for CR or LF
1418    characters, the match position is advanced by two characters instead of one, in
1419    other words, to after the CRLF.
1420    .P
1421    The above rule is a compromise that makes the most common cases work as
1422    expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
1423    set), it does not match the string "\er\enA" because, after failing at the
1424    start, it skips both the CR and the LF before retrying. However, the pattern
1425    [\er\en]A does match that string, because it contains an explicit CR or LF
1426    reference, and so advances only by one character after the first failure.
1427    .P
1428    An explicit match for CR of LF is either a literal appearance of one of those
1429    characters, or one of the \er or \en escape sequences. Implicit matches such as
1430    [^X] do not count, nor does \es (which includes CR and LF in the characters
1431    that it matches).
1432    .P
1433    Notwithstanding the above, anomalous effects may still occur when CRLF is a
1434    valid newline sequence and explicit \er or \en escapes appear in the pattern.
1435    .sp
1436    PCRE_NOTBOL    PCRE_NOTBOL
1437    .sp
1438  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
1439  circumflex metacharacter should not match before it. Setting this without  beginning of a line, so the circumflex metacharacter should not match before
1440  PCRE_MULTILINE (at compile time) causes circumflex never to match.  it. Setting this without PCRE_MULTILINE (at compile time) causes circumflex
1441    never to match. This option affects only the behaviour of the circumflex
1442    metacharacter. It does not affect \eA.
1443    .sp
1444    PCRE_NOTEOL    PCRE_NOTEOL
1445    .sp
1446  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
1447  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
1448  it. Setting this without PCRE_MULTILINE (at compile time) causes dollar never  mode) a newline immediately before it. Setting this without PCRE_MULTILINE (at
1449  to match.  compile time) causes dollar never to match. This option affects only the
1450    behaviour of the dollar metacharacter. It does not affect \eZ or \ez.
1451    .sp
1452    PCRE_NOTEMPTY    PCRE_NOTEMPTY
1453    .sp
1454  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
1455  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
1456  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
1457    .sp
1458    a?b?    a?b?
1459    .sp
1460  is applied to a string not beginning with "a" or "b", it matches the empty  is applied to a string not beginning with "a" or "b", it matches an empty
1461  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
1462  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".
1463    .sp
1464  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case    PCRE_NOTEMPTY_ATSTART
1465  of a pattern match of the empty string within its \fBsplit()\fR function, and  .sp
1466  when using the /g modifier. It is possible to emulate Perl's behaviour after  This is like PCRE_NOTEMPTY, except that an empty string match that is not at
1467  matching a null string by first trying the match again at the same offset with  the start of the subject is permitted. If the pattern is anchored, such a match
1468  PCRE_NOTEMPTY set, and then if that fails by advancing the starting offset (see  can occur only if the pattern contains \eK.
1469  below) and trying an ordinary match again.  .P
1470    Perl has no direct equivalent of PCRE_NOTEMPTY or PCRE_NOTEMPTY_ATSTART, but it
1471  The subject string is passed to \fBpcre_exec()\fR as a pointer in  does make a special case of a pattern match of the empty string within its
1472  \fIsubject\fR, a length in \fIlength\fR, and a starting offset in  \fBsplit()\fP function, and when using the /g modifier. It is possible to
1473  \fIstartoffset\fR. Unlike the pattern string, the subject may contain binary  emulate Perl's behaviour after matching a null string by first trying the match
1474  zero bytes. When the starting offset is zero, the search for a match starts at  again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
1475  the beginning of the subject, and this is by far the most common case.  if that fails, by advancing the starting offset (see below) and trying an
1476    ordinary match again. There is some code that demonstrates how to do this in
1477  If the pattern was compiled with the PCRE_UTF8 option, the subject must be a  the
1478  sequence of bytes that is a valid UTF-8 string. If an invalid UTF-8 string is  .\" HREF
1479  passed, PCRE's behaviour is not defined.  \fBpcredemo\fP
1480    .\"
1481    sample program. In the most general case, you have to check to see if the
1482    newline convention recognizes CRLF as a newline, and if so, and the current
1483    character is CR followed by LF, advance the starting offset by two characters
1484    instead of one.
1485    .sp
1486      PCRE_NO_START_OPTIMIZE
1487    .sp
1488    There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1489    a match, in order to speed up the process. For example, if it is known that an
1490    unanchored match must start with a specific character, it searches the subject
1491    for that character, and fails immediately if it cannot find it, without
1492    actually running the main matching function. This means that a special item
1493    such as (*COMMIT) at the start of a pattern is not considered until after a
1494    suitable starting point for the match has been found. When callouts or (*MARK)
1495    items are in use, these "start-up" optimizations can cause them to be skipped
1496    if the pattern is never actually used. The start-up optimizations are in effect
1497    a pre-scan of the subject that takes place before the pattern is run.
1498    .P
1499    The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
1500    causing performance to suffer, but ensuring that in cases where the result is
1501    "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
1502    are considered at every possible starting position in the subject string. If
1503    PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
1504    time.
1505    .P
1506    Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
1507    Consider the pattern
1508    .sp
1509      (*COMMIT)ABC
1510    .sp
1511    When this is compiled, PCRE records the fact that a match must start with the
1512    character "A". Suppose the subject string is "DEFABC". The start-up
1513    optimization scans along the subject, finds "A" and runs the first match
1514    attempt from there. The (*COMMIT) item means that the pattern must match the
1515    current starting position, which in this case, it does. However, if the same
1516    match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
1517    subject string does not happen. The first match attempt is run starting from
1518    "D" and when this fails, (*COMMIT) prevents any further matches being tried, so
1519    the overall result is "no match". If the pattern is studied, more start-up
1520    optimizations may be used. For example, a minimum length for the subject may be
1521    recorded. Consider the pattern
1522    .sp
1523      (*MARK:A)(X|Y)
1524    .sp
1525    The minimum length for a match is one character. If the subject is "ABC", there
1526    will be attempts to match "ABC", "BC", "C", and then finally an empty string.
1527    If the pattern is studied, the final attempt does not take place, because PCRE
1528    knows that the subject is too short, and so the (*MARK) is never encountered.
1529    In this case, studying the pattern does not affect the overall match result,
1530    which is still "no match", but it does affect the auxiliary information that is
1531    returned.
1532    .sp
1533      PCRE_NO_UTF8_CHECK
1534    .sp
1535    When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8
1536    string is automatically checked when \fBpcre_exec()\fP is subsequently called.
1537    The value of \fIstartoffset\fP is also checked to ensure that it points to the
1538    start of a UTF-8 character. There is a discussion about the validity of UTF-8
1539    strings in the
1540    .\" HTML <a href="pcre.html#utf8strings">
1541    .\" </a>
1542    section on UTF-8 support
1543    .\"
1544    in the main
1545    .\" HREF
1546    \fBpcre\fP
1547    .\"
1548    page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns
1549    the error PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is
1550    a truncated UTF-8 character at the end of the subject, PCRE_ERROR_SHORTUTF8. If
1551    \fIstartoffset\fP contains a value that does not point to the start of a UTF-8
1552    character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
1553    returned.
1554    .P
1555    If you already know that your subject is valid, and you want to skip these
1556    checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when
1557    calling \fBpcre_exec()\fP. You might want to do this for the second and
1558    subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find
1559    all the matches in a single subject string. However, you should be sure that
1560    the value of \fIstartoffset\fP points to the start of a UTF-8 character (or the
1561    end of the subject). When PCRE_NO_UTF8_CHECK is set, the effect of passing an
1562    invalid UTF-8 string as a subject or an invalid value of \fIstartoffset\fP is
1563    undefined. Your program may crash.
1564    .sp
1565      PCRE_PARTIAL_HARD
1566      PCRE_PARTIAL_SOFT
1567    .sp
1568    These options turn on the partial matching feature. For backwards
1569    compatibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial match
1570    occurs if the end of the subject string is reached successfully, but there are
1571    not enough subject characters to complete the match. If this happens when
1572    PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set, matching continues by
1573    testing any remaining alternatives. Only if no complete match can be found is
1574    PCRE_ERROR_PARTIAL returned instead of PCRE_ERROR_NOMATCH. In other words,
1575    PCRE_PARTIAL_SOFT says that the caller is prepared to handle a partial match,
1576    but only if no complete match can be found.
1577    .P
1578    If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
1579    partial match is found, \fBpcre_exec()\fP immediately returns
1580    PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
1581    when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
1582    important that an alternative complete match.
1583    .P
1584    In both cases, the portion of the string that was inspected when the partial
1585    match was found is set as the first matching string. There is a more detailed
1586    discussion of partial and multi-segment matching, with examples, in the
1587    .\" HREF
1588    \fBpcrepartial\fP
1589    .\"
1590    documentation.
1591    .
1592    .
1593    .SS "The string to be matched by \fBpcre_exec()\fP"
1594    .rs
1595    .sp
1596    The subject string is passed to \fBpcre_exec()\fP as a pointer in
1597    \fIsubject\fP, a length (in bytes) in \fIlength\fP, and a starting byte offset
1598    in \fIstartoffset\fP. If this is negative or greater than the length of the
1599    subject, \fBpcre_exec()\fP returns PCRE_ERROR_BADOFFSET. When the starting
1600    offset is zero, the search for a match starts at the beginning of the subject,
1601    and this is by far the most common case. In UTF-8 mode, the byte offset must
1602    point to the start of a UTF-8 character (or the end of the subject). Unlike the
1603    pattern string, the subject may contain binary zero bytes.
1604    .P
1605  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
1606  same subject by calling \fBpcre_exec()\fR again after a previous success.  same subject by calling \fBpcre_exec()\fP again after a previous success.
1607  Setting \fIstartoffset\fR differs from just passing over a shortened string and  Setting \fIstartoffset\fP differs from just passing over a shortened string and
1608  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
1609  lookbehind. For example, consider the pattern  lookbehind. For example, consider the pattern
1610    .sp
1611    \\Biss\\B    \eBiss\eB
1612    .sp
1613  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
1614  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
1615  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
1616  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
1617  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
1618  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
1619  \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
1620  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
1621  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.
1622    .P
1623    Finding all the matches in a subject is tricky when the pattern can match an
1624    empty string. It is possible to emulate Perl's /g behaviour by first trying the
1625    match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
1626    PCRE_ANCHORED options, and then if that fails, advancing the starting offset
1627    and trying an ordinary match again. There is some code that demonstrates how to
1628    do this in the
1629    .\" HREF
1630    \fBpcredemo\fP
1631    .\"
1632    sample program. In the most general case, you have to check to see if the
1633    newline convention recognizes CRLF as a newline, and if so, and the current
1634    character is CR followed by LF, advance the starting offset by two characters
1635    instead of one.
1636    .P
1637  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
1638  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
1639  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.
1640    .
1641    .
1642    .SS "How \fBpcre_exec()\fP returns captured substrings"
1643    .rs
1644    .sp
1645  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
1646  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
1647  pattern. Following the usage in Jeffrey Friedl's book, this is called  pattern. Following the usage in Jeffrey Friedl's book, this is called
1648  "capturing" in what follows, and the phrase "capturing subpattern" is used for  "capturing" in what follows, and the phrase "capturing subpattern" is used for
1649  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
1650  kinds of parenthesized subpattern that do not cause substrings to be captured.  kinds of parenthesized subpattern that do not cause substrings to be captured.
1651    .P
1652  Captured substrings are returned to the caller via a vector of integer offsets  Captured substrings are returned to the caller via a vector of integers whose
1653  whose address is passed in \fIovector\fR. The number of elements in the vector  address is passed in \fIovector\fP. The number of elements in the vector is
1654  is passed in \fIovecsize\fR. The first two-thirds of the vector is used to pass  passed in \fIovecsize\fP, which must be a non-negative number. \fBNote\fP: this
1655  back captured substrings, each substring using a pair of integers. The  argument is NOT the size of \fIovector\fP in bytes.
1656  remaining third of the vector is used as workspace by \fBpcre_exec()\fR while  .P
1657  matching capturing subpatterns, and is not available for passing back  The first two-thirds of the vector is used to pass back captured substrings,
1658  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
1659  three. If it is not, it is rounded down.  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
1660    and is not available for passing back information. The number passed in
1661  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
1662  returned in pairs of integers, starting at the beginning of \fIovector\fR, and  rounded down.
1663  continuing up to two-thirds of its length at the most. The first element of a  .P
1664  pair is set to the offset of the first character in a substring, and the second  When a match is successful, information about captured substrings is returned
1665  is set to the offset of the first character after the end of a substring. The  in pairs of integers, starting at the beginning of \fIovector\fP, and
1666  first pair, \fIovector[0]\fR and \fIovector[1]\fR, identify the portion of the  continuing up to two-thirds of its length at the most. The first element of
1667  subject string matched by the entire pattern. The next pair is used for the  each pair is set to the byte offset of the first character in a substring, and
1668  first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fR  the second is set to the byte offset of the first character after the end of a
1669  is the number of pairs that have been set. If there are no capturing  substring. \fBNote\fP: these values are always byte offsets, even in UTF-8
1670  subpatterns, the return value from a successful match is 1, indicating that  mode. They are not character counts.
1671  just the first pair of offsets has been set.  .P
1672    The first pair of integers, \fIovector[0]\fP and \fIovector[1]\fP, identify the
1673  Some convenience functions are provided for extracting the captured substrings  portion of the subject string matched by the entire pattern. The next pair is
1674  as separate strings. These are described in the following section.  used for the first capturing subpattern, and so on. The value returned by
1675    \fBpcre_exec()\fP is one more than the highest numbered pair that has been set.
1676  It is possible for an capturing subpattern number \fIn+1\fR to match some  For example, if two substrings have been captured, the returned value is 3. If
1677  part of the subject when subpattern \fIn\fR has not been used at all. For  there are no capturing subpatterns, the return value from a successful match is
1678  example, if the string "abc" is matched against the pattern (a|(z))(bc)  1, indicating that just the first pair of offsets has been set.
1679  subpatterns 1 and 3 are matched, but 2 is not. When this happens, both offset  .P
 values corresponding to the unused subpattern are set to -1.  
   
1680  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
1681  string that it matched that gets returned.  string that it matched that is returned.
1682    .P
1683  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
1684  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
1685  value of zero. In particular, if the substring offsets are not of interest,  returns a value of zero. If the substring offsets are not of interest,
1686  \fBpcre_exec()\fR may be called with \fIovector\fR passed as NULL and  \fBpcre_exec()\fP may be called with \fIovector\fP passed as NULL and
1687  \fIovecsize\fR as zero. However, if the pattern contains back references and  \fIovecsize\fP as zero. However, if the pattern contains back references and
1688  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
1689  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
1690  to supply an \fIovector\fR.  advisable to supply an \fIovector\fP.
1691    .P
1692  Note that \fBpcre_info()\fR can be used to find out how many capturing  The \fBpcre_fullinfo()\fP function can be used to find out how many capturing
1693  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1694  \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
1695  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.
1696    .P
1697  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
1698    the subject when subpattern \fIn\fP has not been used at all. For example, if
1699    the string "abc" is matched against the pattern (a|(z))(bc) the return from the
1700    function is 4, and subpatterns 1 and 3 are matched, but 2 is not. When this
1701    happens, both values in the offset pairs corresponding to unused subpatterns
1702    are set to -1.
1703    .P
1704    Offset values that correspond to unused subpatterns at the end of the
1705    expression are also set to -1. For example, if the string "abc" is matched
1706    against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
1707    return from the function is 2, because the highest used capturing subpattern
1708    number is 1, and the offsets for for the second and third capturing subpatterns
1709    (assuming the vector is large enough, of course) are set to -1.
1710    .P
1711    \fBNote\fP: Elements of \fIovector\fP that do not correspond to capturing
1712    parentheses in the pattern are never changed. That is, if a pattern contains
1713    \fIn\fP capturing parentheses, no more than \fIovector[0]\fP to
1714    \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other elements retain
1715    whatever values they previously had.
1716    .P
1717    Some convenience functions are provided for extracting the captured substrings
1718    as separate strings. These are described below.
1719    .
1720    .\" HTML <a name="errorlist"></a>
1721    .SS "Error return values from \fBpcre_exec()\fP"
1722    .rs
1723    .sp
1724    If \fBpcre_exec()\fP fails, it returns a negative number. The following are
1725  defined in the header file:  defined in the header file:
1726    .sp
1727    PCRE_ERROR_NOMATCH        (-1)    PCRE_ERROR_NOMATCH        (-1)
1728    .sp
1729  The subject string did not match the pattern.  The subject string did not match the pattern.
1730    .sp
1731    PCRE_ERROR_NULL           (-2)    PCRE_ERROR_NULL           (-2)
1732    .sp
1733  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
1734  NULL and \fIovecsize\fR was not zero.  NULL and \fIovecsize\fP was not zero.
1735    .sp
1736    PCRE_ERROR_BADOPTION      (-3)    PCRE_ERROR_BADOPTION      (-3)
1737    .sp
1738  An unrecognized bit was set in the \fIoptions\fR argument.  An unrecognized bit was set in the \fIoptions\fP argument.
1739    .sp
1740    PCRE_ERROR_BADMAGIC       (-4)    PCRE_ERROR_BADMAGIC       (-4)
1741    .sp
1742  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
1743  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
1744  magic number isn't present.  compiled in an environment of one endianness is run in an environment with the
1745    other endianness. This is the error that PCRE gives when the magic number is
1746    PCRE_ERROR_UNKNOWN_NODE   (-5)  not present.
1747    .sp
1748      PCRE_ERROR_UNKNOWN_OPCODE (-5)
1749    .sp
1750  While running the pattern match, an unknown item was encountered in the  While running the pattern match, an unknown item was encountered in the
1751  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
1752  of the compiled pattern.  of the compiled pattern.
1753    .sp
1754    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1755    .sp
1756  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
1757  \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
1758  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
1759  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
1760  the end of matching.  automatically freed at the end of matching.
1761    .P
1762    This error is also given if \fBpcre_stack_malloc()\fP fails in
1763    \fBpcre_exec()\fP. This can happen only when PCRE has been compiled with
1764    \fB--disable-stack-for-recursion\fP.
1765    .sp
1766    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1767    .sp
1768  This error is used by the \fBpcre_copy_substring()\fR,  This error is used by the \fBpcre_copy_substring()\fP,
1769  \fBpcre_get_substring()\fR, and \fBpcre_get_substring_list()\fR functions (see  \fBpcre_get_substring()\fP, and \fBpcre_get_substring_list()\fP functions (see
1770  below). It is never returned by \fBpcre_exec()\fR.  below). It is never returned by \fBpcre_exec()\fP.
1771    .sp
1772    PCRE_ERROR_MATCHLIMIT     (-8)    PCRE_ERROR_MATCHLIMIT     (-8)
1773    .sp
1774  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
1775  field in a \fBpcre_extra\fR structure (or defaulted) was reached. See the  \fBpcre_extra\fP structure (or defaulted) was reached. See the description
1776  description above.  above.
1777    .sp
1778    PCRE_ERROR_CALLOUT        (-9)    PCRE_ERROR_CALLOUT        (-9)
1779    .sp
1780  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
1781  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
1782  \fBpcrecallout\fR documentation for details.  .\" HREF
1783    \fBpcrecallout\fP
1784  .SH EXTRACTING CAPTURED SUBSTRINGS BY NUMBER  .\"
1785    documentation for details.
1786    .sp
1787      PCRE_ERROR_BADUTF8        (-10)
1788    .sp
1789    A string that contains an invalid UTF-8 byte sequence was passed as a subject.
1790    However, if PCRE_PARTIAL_HARD is set and the problem is a truncated UTF-8
1791    character at the end of the subject, PCRE_ERROR_SHORTUTF8 is used instead.
1792    .sp
1793      PCRE_ERROR_BADUTF8_OFFSET (-11)
1794    .sp
1795    The UTF-8 byte sequence that was passed as a subject was valid, but the value
1796    of \fIstartoffset\fP did not point to the beginning of a UTF-8 character or the
1797    end of the subject.
1798    .sp
1799      PCRE_ERROR_PARTIAL        (-12)
1800    .sp
1801    The subject string did not match, but it did match partially. See the
1802    .\" HREF
1803    \fBpcrepartial\fP
1804    .\"
1805    documentation for details of partial matching.
1806    .sp
1807      PCRE_ERROR_BADPARTIAL     (-13)
1808    .sp
1809    This code is no longer in use. It was formerly returned when the PCRE_PARTIAL
1810    option was used with a compiled pattern containing items that were not
1811    supported for partial matching. From release 8.00 onwards, there are no
1812    restrictions on partial matching.
1813    .sp
1814      PCRE_ERROR_INTERNAL       (-14)
1815    .sp
1816    An unexpected internal error has occurred. This error could be caused by a bug
1817    in PCRE or by overwriting of the compiled pattern.
1818    .sp
1819      PCRE_ERROR_BADCOUNT       (-15)
1820    .sp
1821    This error is given if the value of the \fIovecsize\fP argument is negative.
1822    .sp
1823      PCRE_ERROR_RECURSIONLIMIT (-21)
1824    .sp
1825    The internal recursion limit, as specified by the \fImatch_limit_recursion\fP
1826    field in a \fBpcre_extra\fP structure (or defaulted) was reached. See the
1827    description above.
1828    .sp
1829      PCRE_ERROR_BADNEWLINE     (-23)
1830    .sp
1831    An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
1832    .sp
1833      PCRE_ERROR_BADOFFSET      (-24)
1834    .sp
1835    The value of \fIstartoffset\fP was negative or greater than the length of the
1836    subject, that is, the value in \fIlength\fP.
1837    .sp
1838      PCRE_ERROR_SHORTUTF8      (-25)
1839    .sp
1840    The subject string ended with an incomplete (truncated) UTF-8 character, and
1841    the PCRE_PARTIAL_HARD option was set. Without this option, PCRE_ERROR_BADUTF8
1842    is returned in this situation.
1843    .P
1844    Error numbers -16 to -20 and -22 are not used by \fBpcre_exec()\fP.
1845    .
1846    .
1847    .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
1848  .rs  .rs
1849  .sp  .sp
1850  .B int pcre_copy_substring(const char *\fIsubject\fR, int *\fIovector\fR,  .B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\fP,
1851  .ti +5n  .ti +5n
1852  .B int \fIstringcount\fR, int \fIstringnumber\fR, char *\fIbuffer\fR,  .B int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP,
1853  .ti +5n  .ti +5n
1854  .B int \fIbuffersize\fR);  .B int \fIbuffersize\fP);
1855  .PP  .PP
1856  .br  .B int pcre_get_substring(const char *\fIsubject\fP, int *\fIovector\fP,
 .B int pcre_get_substring(const char *\fIsubject\fR, int *\fIovector\fR,  
1857  .ti +5n  .ti +5n
1858  .B int \fIstringcount\fR, int \fIstringnumber\fR,  .B int \fIstringcount\fP, int \fIstringnumber\fP,
1859  .ti +5n  .ti +5n
1860  .B const char **\fIstringptr\fR);  .B const char **\fIstringptr\fP);
1861  .PP  .PP
1862  .br  .B int pcre_get_substring_list(const char *\fIsubject\fP,
 .B int pcre_get_substring_list(const char *\fIsubject\fR,  
1863  .ti +5n  .ti +5n
1864  .B int *\fIovector\fR, int \fIstringcount\fR, "const char ***\fIlistptr\fR);"  .B int *\fIovector\fP, int \fIstringcount\fP, "const char ***\fIlistptr\fP);"
1865  .PP  .PP
1866  Captured substrings can be accessed directly by using the offsets returned by  Captured substrings can be accessed directly by using the offsets returned by
1867  \fBpcre_exec()\fR in \fIovector\fR. For convenience, the functions  \fBpcre_exec()\fP in \fIovector\fP. For convenience, the functions
1868  \fBpcre_copy_substring()\fR, \fBpcre_get_substring()\fR, and  \fBpcre_copy_substring()\fP, \fBpcre_get_substring()\fP, and
1869  \fBpcre_get_substring_list()\fR are provided for extracting captured substrings  \fBpcre_get_substring_list()\fP are provided for extracting captured substrings
1870  as new, separate, zero-terminated strings. These functions identify substrings  as new, separate, zero-terminated strings. These functions identify substrings
1871  by number. The next section describes functions for extracting named  by number. The next section describes functions for extracting named
1872  substrings. A substring that contains a binary zero is correctly extracted and  substrings.
1873  has a further zero added on the end, but the result is not, of course,  .P
1874  a C string.  A substring that contains a binary zero is correctly extracted and has a
1875    further zero added on the end, but the result is not, of course, a C string.
1876    However, you can process such a string by referring to the length that is
1877    returned by \fBpcre_copy_substring()\fP and \fBpcre_get_substring()\fP.
1878    Unfortunately, the interface to \fBpcre_get_substring_list()\fP is not adequate
1879    for handling strings containing binary zeros, because the end of the final
1880    string is not independently indicated.
1881    .P
1882  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:
1883  \fIsubject\fR is the subject string which has just been successfully matched,  \fIsubject\fP is the subject string that has just been successfully matched,
1884  \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
1885  \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
1886  captured by the match, including the substring that matched the entire regular  captured by the match, including the substring that matched the entire regular
1887  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
1888  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
1889  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
1890  the vector divided by three.  number of elements in the vector divided by three.
1891    .P
1892  The functions \fBpcre_copy_substring()\fR and \fBpcre_get_substring()\fR  The functions \fBpcre_copy_substring()\fP and \fBpcre_get_substring()\fP
1893  extract a single substring, whose number is given as \fIstringnumber\fR. A  extract a single substring, whose number is given as \fIstringnumber\fP. A
1894  value of zero extracts the substring that matched the entire pattern, while  value of zero extracts the substring that matched the entire pattern, whereas
1895  higher values extract the captured substrings. For \fBpcre_copy_substring()\fR,  higher values extract the captured substrings. For \fBpcre_copy_substring()\fP,
1896  the string is placed in \fIbuffer\fR, whose length is given by  the string is placed in \fIbuffer\fP, whose length is given by
1897  \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
1898  obtained via \fBpcre_malloc\fR, and its address is returned via  obtained via \fBpcre_malloc\fP, and its address is returned via
1899  \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
1900  including the terminating zero, or one of  including the terminating zero, or one of these error codes:
1901    .sp
1902    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1903    .sp
1904  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
1905  memory failed for \fBpcre_get_substring()\fR.  memory failed for \fBpcre_get_substring()\fP.
1906    .sp
1907    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1908    .sp
1909  There is no substring whose number is \fIstringnumber\fR.  There is no substring whose number is \fIstringnumber\fP.
1910    .P
1911  The \fBpcre_get_substring_list()\fR function extracts all available substrings  The \fBpcre_get_substring_list()\fP function extracts all available substrings
1912  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
1913  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
1914  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
1915  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
1916  function is zero if all went well, or  function is zero if all went well, or the error code
1917    .sp
1918    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1919    .sp
1920  if the attempt to get the memory block failed.  if the attempt to get the memory block failed.
1921    .P
1922  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
1923  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
1924  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
1925  string. This can be distinguished from a genuine zero-length substring by  string. This can be distinguished from a genuine zero-length substring by
1926  inspecting the appropriate offset in \fIovector\fR, which is negative for unset  inspecting the appropriate offset in \fIovector\fP, which is negative for unset
1927  substrings.  substrings.
1928    .P
1929  The two convenience functions \fBpcre_free_substring()\fR and  The two convenience functions \fBpcre_free_substring()\fP and
1930  \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
1931  a previous call of \fBpcre_get_substring()\fR or  a previous call of \fBpcre_get_substring()\fP or
1932  \fBpcre_get_substring_list()\fR, respectively. They do nothing more than call  \fBpcre_get_substring_list()\fP, respectively. They do nothing more than call
1933  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
1934  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
1935  linked via a special interface to another programming language which cannot use  linked via a special interface to another programming language that cannot use
1936  \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
1937  provided.  provided.
1938    .
1939  .SH EXTRACTING CAPTURED SUBSTRINGS BY NAME  .
1940    .SH "EXTRACTING CAPTURED SUBSTRINGS BY NAME"
1941  .rs  .rs
1942  .sp  .sp
1943  .B int pcre_copy_named_substring(const pcre *\fIcode\fR,  .B int pcre_get_stringnumber(const pcre *\fIcode\fP,
1944  .ti +5n  .ti +5n
1945  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B const char *\fIname\fP);
1946    .PP
1947    .B int pcre_copy_named_substring(const pcre *\fIcode\fP,
1948  .ti +5n  .ti +5n
1949  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B const char *\fIsubject\fP, int *\fIovector\fP,
1950  .ti +5n  .ti +5n
1951  .B char *\fIbuffer\fR, int \fIbuffersize\fR);  .B int \fIstringcount\fP, const char *\fIstringname\fP,
 .PP  
 .br  
 .B int pcre_get_stringnumber(const pcre *\fIcode\fR,  
1952  .ti +5n  .ti +5n
1953  .B const char *\fIname\fR);  .B char *\fIbuffer\fP, int \fIbuffersize\fP);
1954  .PP  .PP
1955  .br  .B int pcre_get_named_substring(const pcre *\fIcode\fP,
 .B int pcre_get_named_substring(const pcre *\fIcode\fR,  
1956  .ti +5n  .ti +5n
1957  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B const char *\fIsubject\fP, int *\fIovector\fP,
1958  .ti +5n  .ti +5n
1959  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B int \fIstringcount\fP, const char *\fIstringname\fP,
1960  .ti +5n  .ti +5n
1961  .B const char **\fIstringptr\fR);  .B const char **\fIstringptr\fP);
1962  .PP  .PP
1963  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.
1964  can be done by calling \fBpcre_get_stringnumber()\fR. The first argument is the  For example, for this pattern
1965  compiled pattern, and the second is the name. For example, for this pattern  .sp
1966      (a+)b(?<xxx>\ed+)...
1967    ab(?<xxx>\\d+)...  .sp
1968    the number of the subpattern called "xxx" is 2. If the name is known to be
1969  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
1970  extract the substring directly, or use one of the functions described in the  calling \fBpcre_get_stringnumber()\fP. The first argument is the compiled
1971  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
1972  whole job.  subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if there is no subpattern of
1973    that name.
1974  Most of the arguments of \fIpcre_copy_named_substring()\fR and  .P
1975  \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
1976  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
1977  differences.  two functions that do the whole job.
1978    .P
1979    Most of the arguments of \fBpcre_copy_named_substring()\fP and
1980    \fBpcre_get_named_substring()\fP are the same as those for the similarly named
1981    functions that extract by number. As these are described in the previous
1982    section, they are not re-described here. There are just two differences:
1983    .P
1984  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
1985  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
1986  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
1987  translation table.  translation table.
1988    .P
1989  These functions call \fBpcre_get_stringnumber()\fR, and if it succeeds, they  These functions call \fBpcre_get_stringnumber()\fP, and if it succeeds, they
1990  then call \fIpcre_copy_substring()\fR or \fIpcre_get_substring()\fR, as  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
1991  appropriate.  appropriate. \fBNOTE:\fP If PCRE_DUPNAMES is set and there are duplicate names,
1992    the behaviour may not be what you want (see the next section).
1993  .in 0  .P
1994  Last updated: 03 February 2003  \fBWarning:\fP If the pattern uses the (?| feature to set up multiple
1995  .br  subpatterns with the same number, as described in the
1996  Copyright (c) 1997-2003 University of Cambridge.  .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1997    .\" </a>
1998    section on duplicate subpattern numbers
1999    .\"
2000    in the
2001    .\" HREF
2002    \fBpcrepattern\fP
2003    .\"
2004    page, you cannot use names to distinguish the different subpatterns, because
2005    names are not included in the compiled code. The matching process uses only
2006    numbers. For this reason, the use of different names for subpatterns of the
2007    same number causes an error at compile time.
2008    .
2009    .SH "DUPLICATE SUBPATTERN NAMES"
2010    .rs
2011    .sp
2012    .B int pcre_get_stringtable_entries(const pcre *\fIcode\fP,
2013    .ti +5n
2014    .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
2015    .PP
2016    When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
2017    are not required to be unique. (Duplicate names are always allowed for
2018    subpatterns with the same number, created by using the (?| feature. Indeed, if
2019    such subpatterns are named, they are required to use the same names.)
2020    .P
2021    Normally, patterns with duplicate names are such that in any one match, only
2022    one of the named subpatterns participates. An example is shown in the
2023    .\" HREF
2024    \fBpcrepattern\fP
2025    .\"
2026    documentation.
2027    .P
2028    When duplicates are present, \fBpcre_copy_named_substring()\fP and
2029    \fBpcre_get_named_substring()\fP return the first substring corresponding to
2030    the given name that is set. If none are set, PCRE_ERROR_NOSUBSTRING (-7) is
2031    returned; no data is returned. The \fBpcre_get_stringnumber()\fP function
2032    returns one of the numbers that are associated with the name, but it is not
2033    defined which it is.
2034    .P
2035    If you want to get full details of all captured substrings for a given name,
2036    you must use the \fBpcre_get_stringtable_entries()\fP function. The first
2037    argument is the compiled pattern, and the second is the name. The third and
2038    fourth are pointers to variables which are updated by the function. After it
2039    has run, they point to the first and last entries in the name-to-number table
2040    for the given name. The function itself returns the length of each entry, or
2041    PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
2042    described above in the section entitled \fIInformation about a pattern\fP.
2043    Given all the relevant entries for the name, you can extract each of their
2044    numbers, and hence the captured data, if any.
2045    .
2046    .
2047    .SH "FINDING ALL POSSIBLE MATCHES"
2048    .rs
2049    .sp
2050    The traditional matching function uses a similar algorithm to Perl, which stops
2051    when it finds the first match, starting at a given point in the subject. If you
2052    want to find all possible matches, or the longest possible match, consider
2053    using the alternative matching function (see below) instead. If you cannot use
2054    the alternative function, but still need to find all possible matches, you
2055    can kludge it up by making use of the callout facility, which is described in
2056    the
2057    .\" HREF
2058    \fBpcrecallout\fP
2059    .\"
2060    documentation.
2061    .P
2062    What you have to do is to insert a callout right at the end of the pattern.
2063    When your callout function is called, extract and save the current matched
2064    substring. Then return 1, which forces \fBpcre_exec()\fP to backtrack and try
2065    other alternatives. Ultimately, when it runs out of matches, \fBpcre_exec()\fP
2066    will yield PCRE_ERROR_NOMATCH.
2067    .
2068    .
2069    .\" HTML <a name="dfamatch"></a>
2070    .SH "MATCHING A PATTERN: THE ALTERNATIVE FUNCTION"
2071    .rs
2072    .sp
2073    .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
2074    .ti +5n
2075    .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
2076    .ti +5n
2077    .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,
2078    .ti +5n
2079    .B int *\fIworkspace\fP, int \fIwscount\fP);
2080    .P
2081    The function \fBpcre_dfa_exec()\fP is called to match a subject string against
2082    a compiled pattern, using a matching algorithm that scans the subject string
2083    just once, and does not backtrack. This has different characteristics to the
2084    normal algorithm, and is not compatible with Perl. Some of the features of PCRE
2085    patterns are not supported. Nevertheless, there are times when this kind of
2086    matching can be useful. For a discussion of the two matching algorithms, and a
2087    list of features that \fBpcre_dfa_exec()\fP does not support, see the
2088    .\" HREF
2089    \fBpcrematching\fP
2090    .\"
2091    documentation.
2092    .P
2093    The arguments for the \fBpcre_dfa_exec()\fP function are the same as for
2094    \fBpcre_exec()\fP, plus two extras. The \fIovector\fP argument is used in a
2095    different way, and this is described below. The other common arguments are used
2096    in the same way as for \fBpcre_exec()\fP, so their description is not repeated
2097    here.
2098    .P
2099    The two additional arguments provide workspace for the function. The workspace
2100    vector should contain at least 20 elements. It is used for keeping track of
2101    multiple paths through the pattern tree. More workspace will be needed for
2102    patterns and subjects where there are a lot of potential matches.
2103    .P
2104    Here is an example of a simple call to \fBpcre_dfa_exec()\fP:
2105    .sp
2106      int rc;
2107      int ovector[10];
2108      int wspace[20];
2109      rc = pcre_dfa_exec(
2110        re,             /* result of pcre_compile() */
2111        NULL,           /* we didn't study the pattern */
2112        "some string",  /* the subject string */
2113        11,             /* the length of the subject string */
2114        0,              /* start at offset 0 in the subject */
2115        0,              /* default options */
2116        ovector,        /* vector of integers for substring information */
2117        10,             /* number of elements (NOT size in bytes) */
2118        wspace,         /* working space vector */
2119        20);            /* number of elements (NOT size in bytes) */
2120    .
2121    .SS "Option bits for \fBpcre_dfa_exec()\fP"
2122    .rs
2123    .sp
2124    The unused bits of the \fIoptions\fP argument for \fBpcre_dfa_exec()\fP must be
2125    zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
2126    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
2127    PCRE_NO_UTF8_CHECK, PCRE_BSR_ANYCRLF, PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE,
2128    PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART.
2129    All but the last four of these are exactly the same as for \fBpcre_exec()\fP,
2130    so their description is not repeated here.
2131    .sp
2132      PCRE_PARTIAL_HARD
2133      PCRE_PARTIAL_SOFT
2134    .sp
2135    These have the same general effect as they do for \fBpcre_exec()\fP, but the
2136    details are slightly different. When PCRE_PARTIAL_HARD is set for
2137    \fBpcre_dfa_exec()\fP, it returns PCRE_ERROR_PARTIAL if the end of the subject
2138    is reached and there is still at least one matching possibility that requires
2139    additional characters. This happens even if some complete matches have also
2140    been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
2141    is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
2142    there have been no complete matches, but there is still at least one matching
2143    possibility. The portion of the string that was inspected when the longest
2144    partial match was found is set as the first matching string in both cases.
2145    There is a more detailed discussion of partial and multi-segment matching, with
2146    examples, in the
2147    .\" HREF
2148    \fBpcrepartial\fP
2149    .\"
2150    documentation.
2151    .sp
2152      PCRE_DFA_SHORTEST
2153    .sp
2154    Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as
2155    soon as it has found one match. Because of the way the alternative algorithm
2156    works, this is necessarily the shortest possible match at the first possible
2157    matching point in the subject string.
2158    .sp
2159      PCRE_DFA_RESTART
2160    .sp
2161    When \fBpcre_dfa_exec()\fP returns a partial match, it is possible to call it
2162    again, with additional subject characters, and have it continue with the same
2163    match. The PCRE_DFA_RESTART option requests this action; when it is set, the
2164    \fIworkspace\fP and \fIwscount\fP options must reference the same vector as
2165    before because data about the match so far is left in them after a partial
2166    match. There is more discussion of this facility in the
2167    .\" HREF
2168    \fBpcrepartial\fP
2169    .\"
2170    documentation.
2171    .
2172    .SS "Successful returns from \fBpcre_dfa_exec()\fP"
2173    .rs
2174    .sp
2175    When \fBpcre_dfa_exec()\fP succeeds, it may have matched more than one
2176    substring in the subject. Note, however, that all the matches from one run of
2177    the function start at the same point in the subject. The shorter matches are
2178    all initial substrings of the longer matches. For example, if the pattern
2179    .sp
2180      <.*>
2181    .sp
2182    is matched against the string
2183    .sp
2184      This is <something> <something else> <something further> no more
2185    .sp
2186    the three matched strings are
2187    .sp
2188      <something>
2189      <something> <something else>
2190      <something> <something else> <something further>
2191    .sp
2192    On success, the yield of the function is a number greater than zero, which is
2193    the number of matched substrings. The substrings themselves are returned in
2194    \fIovector\fP. Each string uses two elements; the first is the offset to the
2195    start, and the second is the offset to the end. In fact, all the strings have
2196    the same start offset. (Space could have been saved by giving this only once,
2197    but it was decided to retain some compatibility with the way \fBpcre_exec()\fP
2198    returns data, even though the meaning of the strings is different.)
2199    .P
2200    The strings are returned in reverse order of length; that is, the longest
2201    matching string is given first. If there were too many matches to fit into
2202    \fIovector\fP, the yield of the function is zero, and the vector is filled with
2203    the longest matches.
2204    .
2205    .SS "Error returns from \fBpcre_dfa_exec()\fP"
2206    .rs
2207    .sp
2208    The \fBpcre_dfa_exec()\fP function returns a negative number when it fails.
2209    Many of the errors are the same as for \fBpcre_exec()\fP, and these are
2210    described
2211    .\" HTML <a href="#errorlist">
2212    .\" </a>
2213    above.
2214    .\"
2215    There are in addition the following errors that are specific to
2216    \fBpcre_dfa_exec()\fP:
2217    .sp
2218      PCRE_ERROR_DFA_UITEM      (-16)
2219    .sp
2220    This return is given if \fBpcre_dfa_exec()\fP encounters an item in the pattern
2221    that it does not support, for instance, the use of \eC or a back reference.
2222    .sp
2223      PCRE_ERROR_DFA_UCOND      (-17)
2224    .sp
2225    This return is given if \fBpcre_dfa_exec()\fP encounters a condition item that
2226    uses a back reference for the condition, or a test for recursion in a specific
2227    group. These are not supported.
2228    .sp
2229      PCRE_ERROR_DFA_UMLIMIT    (-18)
2230    .sp
2231    This return is given if \fBpcre_dfa_exec()\fP is called with an \fIextra\fP
2232    block that contains a setting of the \fImatch_limit\fP field. This is not
2233    supported (it is meaningless).
2234    .sp
2235      PCRE_ERROR_DFA_WSSIZE     (-19)
2236    .sp
2237    This return is given if \fBpcre_dfa_exec()\fP runs out of space in the
2238    \fIworkspace\fP vector.
2239    .sp
2240      PCRE_ERROR_DFA_RECURSE    (-20)
2241    .sp
2242    When a recursive subpattern is processed, the matching function calls itself
2243    recursively, using private vectors for \fIovector\fP and \fIworkspace\fP. This
2244    error is given if the output vector is not large enough. This should be
2245    extremely rare, as a vector of size 1000 is used.
2246    .
2247    .
2248    .SH "SEE ALSO"
2249    .rs
2250    .sp
2251    \fBpcrebuild\fP(3), \fBpcrecallout\fP(3), \fBpcrecpp(3)\fP(3),
2252    \fBpcrematching\fP(3), \fBpcrepartial\fP(3), \fBpcreposix\fP(3),
2253    \fBpcreprecompile\fP(3), \fBpcresample\fP(3), \fBpcrestack\fP(3).
2254    .
2255    .
2256    .SH AUTHOR
2257    .rs
2258    .sp
2259    .nf
2260    Philip Hazel
2261    University Computing Service
2262    Cambridge CB2 3QH, England.
2263    .fi
2264    .
2265    .
2266    .SH REVISION
2267    .rs
2268    .sp
2269    .nf
2270    Last updated: 21 November 2010
2271    Copyright (c) 1997-2010 University of Cambridge.
2272    .fi

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