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1  .TH PCRE 3  .TH PCREAPI 3 "07 September 2012" "PCRE 8.32"
2  .SH NAME  .SH NAME
3  PCRE - Perl-compatible regular expressions  PCRE - Perl-compatible regular expressions
 .SH SYNOPSIS OF PCRE API  
 .rs  
4  .sp  .sp
5  .B #include <pcre.h>  .B #include <pcre.h>
6  .PP  .
7    .
8    .SH "PCRE NATIVE API BASIC FUNCTIONS"
9    .rs
10    .sp
11  .SM  .SM
12  .br  .B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,
13  .B pcre *pcre_compile(const char *\fIpattern\fR, int \fIoptions\fR,  .ti +5n
14    .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
15    .ti +5n
16    .B const unsigned char *\fItableptr\fP);
17    .PP
18    .B pcre *pcre_compile2(const char *\fIpattern\fP, int \fIoptions\fP,
19    .ti +5n
20    .B int *\fIerrorcodeptr\fP,
21  .ti +5n  .ti +5n
22  .B const char **\fIerrptr\fR, int *\fIerroffset\fR,  .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
23  .ti +5n  .ti +5n
24  .B const unsigned char *\fItableptr\fR);  .B const unsigned char *\fItableptr\fP);
25  .PP  .PP
26  .br  .B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP,
 .B pcre_extra *pcre_study(const pcre *\fIcode\fR, int \fIoptions\fR,  
27  .ti +5n  .ti +5n
28  .B const char **\fIerrptr\fR);  .B const char **\fIerrptr\fP);
29  .PP  .PP
30  .br  .B void pcre_free_study(pcre_extra *\fIextra\fP);
31  .B int pcre_exec(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"  .PP
32    .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
33  .ti +5n  .ti +5n
34  .B "const char *\fIsubject\fR," int \fIlength\fR, int \fIstartoffset\fR,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
35  .ti +5n  .ti +5n
36  .B int \fIoptions\fR, int *\fIovector\fR, int \fIovecsize\fR);  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
37  .PP  .PP
38  .br  .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
39  .B int pcre_copy_named_substring(const pcre *\fIcode\fR,  .ti +5n
40    .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
41    .ti +5n
42    .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,
43    .ti +5n
44    .B int *\fIworkspace\fP, int \fIwscount\fP);
45    .
46    .
47    .SH "PCRE NATIVE API STRING EXTRACTION FUNCTIONS"
48    .rs
49    .sp
50    .B int pcre_copy_named_substring(const pcre *\fIcode\fP,
51  .ti +5n  .ti +5n
52  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B const char *\fIsubject\fP, int *\fIovector\fP,
53  .ti +5n  .ti +5n
54  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B int \fIstringcount\fP, const char *\fIstringname\fP,
55  .ti +5n  .ti +5n
56  .B char *\fIbuffer\fR, int \fIbuffersize\fR);  .B char *\fIbuffer\fP, int \fIbuffersize\fP);
57  .PP  .PP
58  .br  .B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\fP,
 .B int pcre_copy_substring(const char *\fIsubject\fR, int *\fIovector\fR,  
59  .ti +5n  .ti +5n
60  .B int \fIstringcount\fR, int \fIstringnumber\fR, char *\fIbuffer\fR,  .B int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP,
61  .ti +5n  .ti +5n
62  .B int \fIbuffersize\fR);  .B int \fIbuffersize\fP);
63  .PP  .PP
64  .br  .B int pcre_get_named_substring(const pcre *\fIcode\fP,
 .B int pcre_get_named_substring(const pcre *\fIcode\fR,  
65  .ti +5n  .ti +5n
66  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B const char *\fIsubject\fP, int *\fIovector\fP,
67  .ti +5n  .ti +5n
68  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B int \fIstringcount\fP, const char *\fIstringname\fP,
69    .ti +5n
70    .B const char **\fIstringptr\fP);
71    .PP
72    .B int pcre_get_stringnumber(const pcre *\fIcode\fP,
73  .ti +5n  .ti +5n
74  .B const char **\fIstringptr\fR);  .B const char *\fIname\fP);
75  .PP  .PP
76  .br  .B int pcre_get_stringtable_entries(const pcre *\fIcode\fP,
 .B int pcre_get_stringnumber(const pcre *\fIcode\fR,  
77  .ti +5n  .ti +5n
78  .B const char *\fIname\fR);  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
79  .PP  .PP
80  .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,  
81  .ti +5n  .ti +5n
82  .B int \fIstringcount\fR, int \fIstringnumber\fR,  .B int \fIstringcount\fP, int \fIstringnumber\fP,
83  .ti +5n  .ti +5n
84  .B const char **\fIstringptr\fR);  .B const char **\fIstringptr\fP);
85  .PP  .PP
86  .br  .B int pcre_get_substring_list(const char *\fIsubject\fP,
 .B int pcre_get_substring_list(const char *\fIsubject\fR,  
87  .ti +5n  .ti +5n
88  .B int *\fIovector\fR, int \fIstringcount\fR, "const char ***\fIlistptr\fR);"  .B int *\fIovector\fP, int \fIstringcount\fP, "const char ***\fIlistptr\fP);"
89  .PP  .PP
90  .br  .B void pcre_free_substring(const char *\fIstringptr\fP);
 .B void pcre_free_substring(const char *\fIstringptr\fR);  
91  .PP  .PP
92  .br  .B void pcre_free_substring_list(const char **\fIstringptr\fP);
93  .B void pcre_free_substring_list(const char **\fIstringptr\fR);  .
94    .
95    .SH "PCRE NATIVE API AUXILIARY FUNCTIONS"
96    .rs
97    .sp
98    .B pcre_jit_stack *pcre_jit_stack_alloc(int \fIstartsize\fP, int \fImaxsize\fP);
99    .PP
100    .B void pcre_jit_stack_free(pcre_jit_stack *\fIstack\fP);
101    .PP
102    .B void pcre_assign_jit_stack(pcre_extra *\fIextra\fP,
103    .ti +5n
104    .B pcre_jit_callback \fIcallback\fP, void *\fIdata\fP);
105  .PP  .PP
 .br  
106  .B const unsigned char *pcre_maketables(void);  .B const unsigned char *pcre_maketables(void);
107  .PP  .PP
108  .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,"  
109  .ti +5n  .ti +5n
110  .B int \fIwhat\fR, void *\fIwhere\fR);  .B int \fIwhat\fP, void *\fIwhere\fP);
111  .PP  .PP
112  .br  .B int pcre_refcount(pcre *\fIcode\fP, int \fIadjust\fP);
 .B int pcre_info(const pcre *\fIcode\fR, int *\fIoptptr\fR, int  
 .B *\fIfirstcharptr\fR);  
113  .PP  .PP
114  .br  .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
 .B int pcre_config(int \fIwhat\fR, void *\fIwhere\fR);  
115  .PP  .PP
116  .br  .B const char *pcre_version(void);
 .B char *pcre_version(void);  
117  .PP  .PP
118  .br  .B int pcre_pattern_to_host_byte_order(pcre *\fIcode\fP,
119    .ti +5n
120    .B pcre_extra *\fIextra\fP, const unsigned char *\fItables\fP);
121    .
122    .
123    .SH "PCRE NATIVE API INDIRECTED FUNCTIONS"
124    .rs
125    .sp
126  .B void *(*pcre_malloc)(size_t);  .B void *(*pcre_malloc)(size_t);
127  .PP  .PP
 .br  
128  .B void (*pcre_free)(void *);  .B void (*pcre_free)(void *);
129  .PP  .PP
130  .br  .B void *(*pcre_stack_malloc)(size_t);
131    .PP
132    .B void (*pcre_stack_free)(void *);
133    .PP
134  .B int (*pcre_callout)(pcre_callout_block *);  .B int (*pcre_callout)(pcre_callout_block *);
135    .
136  .SH PCRE API  .
137    .SH "PCRE 8-BIT AND 16-BIT LIBRARIES"
138    .rs
139    .sp
140    From release 8.30, PCRE can be compiled as a library for handling 16-bit
141    character strings as well as, or instead of, the original library that handles
142    8-bit character strings. To avoid too much complication, this document
143    describes the 8-bit versions of the functions, with only occasional references
144    to the 16-bit library.
145    .P
146    The 16-bit functions operate in the same way as their 8-bit counterparts; they
147    just use different data types for their arguments and results, and their names
148    start with \fBpcre16_\fP instead of \fBpcre_\fP. For every option that has UTF8
149    in its name (for example, PCRE_UTF8), there is a corresponding 16-bit name with
150    UTF8 replaced by UTF16. This facility is in fact just cosmetic; the 16-bit
151    option names define the same bit values.
152    .P
153    References to bytes and UTF-8 in this document should be read as references to
154    16-bit data quantities and UTF-16 when using the 16-bit library, unless
155    specified otherwise. More details of the specific differences for the 16-bit
156    library are given in the
157    .\" HREF
158    \fBpcre16\fP
159    .\"
160    page.
161    .
162    .
163    .SH "PCRE API OVERVIEW"
164  .rs  .rs
165  .sp  .sp
166  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
167  a set of wrapper functions that correspond to the POSIX regular expression API.  also some wrapper functions (for the 8-bit library only) that correspond to the
168  These are described in the \fBpcreposix\fR documentation.  POSIX regular expression API, but they do not give access to all the
169    functionality. They are described in the
170  The native API function prototypes are defined in the header file \fBpcre.h\fR,  .\" HREF
171  and on Unix systems the library itself is called \fBlibpcre.a\fR, so can be  \fBpcreposix\fP
172  accessed by adding \fB-lpcre\fR to the command for linking an application which  .\"
173  calls it. The header file defines the macros PCRE_MAJOR and PCRE_MINOR to  documentation. Both of these APIs define a set of C function calls. A C++
174  contain the major and minor release numbers for the library. Applications can  wrapper (again for the 8-bit library only) is also distributed with PCRE. It is
175  use these to include support for different releases.  documented in the
176    .\" HREF
177  The functions \fBpcre_compile()\fR, \fBpcre_study()\fR, and \fBpcre_exec()\fR  \fBpcrecpp\fP
178  are used for compiling and matching regular expressions. A sample program that  .\"
179  demonstrates the simplest way of using them is given in the file  page.
180  \fIpcredemo.c\fR. The \fBpcresample\fR documentation describes how to run it.  .P
181    The native API C function prototypes are defined in the header file
182  There are convenience functions for extracting captured substrings from a  \fBpcre.h\fP, and on Unix-like systems the (8-bit) library itself is called
183  matched subject string. They are:  \fBlibpcre\fP. It can normally be accessed by adding \fB-lpcre\fP to the
184    command for linking an application that uses PCRE. The header file defines the
185    \fBpcre_copy_substring()\fR  macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release numbers
186    \fBpcre_copy_named_substring()\fR  for the library. Applications can use these to include support for different
187    \fBpcre_get_substring()\fR  releases of PCRE.
188    \fBpcre_get_named_substring()\fR  .P
189    \fBpcre_get_substring_list()\fR  In a Windows environment, if you want to statically link an application program
190    against a non-dll \fBpcre.a\fP file, you must define PCRE_STATIC before
191  \fBpcre_free_substring()\fR and \fBpcre_free_substring_list()\fR are also  including \fBpcre.h\fP or \fBpcrecpp.h\fP, because otherwise the
192    \fBpcre_malloc()\fP and \fBpcre_free()\fP exported functions will be declared
193    \fB__declspec(dllimport)\fP, with unwanted results.
194    .P
195    The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,
196    and \fBpcre_exec()\fP are used for compiling and matching regular expressions
197    in a Perl-compatible manner. A sample program that demonstrates the simplest
198    way of using them is provided in the file called \fIpcredemo.c\fP in the PCRE
199    source distribution. A listing of this program is given in the
200    .\" HREF
201    \fBpcredemo\fP
202    .\"
203    documentation, and the
204    .\" HREF
205    \fBpcresample\fP
206    .\"
207    documentation describes how to compile and run it.
208    .P
209    Just-in-time compiler support is an optional feature of PCRE that can be built
210    in appropriate hardware environments. It greatly speeds up the matching
211    performance of many patterns. Simple programs can easily request that it be
212    used if available, by setting an option that is ignored when it is not
213    relevant. More complicated programs might need to make use of the functions
214    \fBpcre_jit_stack_alloc()\fP, \fBpcre_jit_stack_free()\fP, and
215    \fBpcre_assign_jit_stack()\fP in order to control the JIT code's memory usage.
216    These functions are discussed in the
217    .\" HREF
218    \fBpcrejit\fP
219    .\"
220    documentation.
221    .P
222    A second matching function, \fBpcre_dfa_exec()\fP, which is not
223    Perl-compatible, is also provided. This uses a different algorithm for the
224    matching. The alternative algorithm finds all possible matches (at a given
225    point in the subject), and scans the subject just once (unless there are
226    lookbehind assertions). However, this algorithm does not return captured
227    substrings. A description of the two matching algorithms and their advantages
228    and disadvantages is given in the
229    .\" HREF
230    \fBpcrematching\fP
231    .\"
232    documentation.
233    .P
234    In addition to the main compiling and matching functions, there are convenience
235    functions for extracting captured substrings from a subject string that is
236    matched by \fBpcre_exec()\fP. They are:
237    .sp
238      \fBpcre_copy_substring()\fP
239      \fBpcre_copy_named_substring()\fP
240      \fBpcre_get_substring()\fP
241      \fBpcre_get_named_substring()\fP
242      \fBpcre_get_substring_list()\fP
243      \fBpcre_get_stringnumber()\fP
244      \fBpcre_get_stringtable_entries()\fP
245    .sp
246    \fBpcre_free_substring()\fP and \fBpcre_free_substring_list()\fP are also
247  provided, to free the memory used for extracted strings.  provided, to free the memory used for extracted strings.
248    .P
249  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
250  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,
251    or \fBpcre_dfa_exec()\fP. This is an optional facility that is provided for
252  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
253  compiled pattern; \fBpcre_info()\fR is an obsolete version which returns only  internal tables that are generated when PCRE is built are used.
254  some of the available information, but is retained for backwards compatibility.  .P
255  The function \fBpcre_version()\fR returns a pointer to a string containing the  The function \fBpcre_fullinfo()\fP is used to find out information about a
256  version of PCRE and its date of release.  compiled pattern. The function \fBpcre_version()\fP returns a pointer to a
257    string containing the version of PCRE and its date of release.
258  The global variables \fBpcre_malloc\fR and \fBpcre_free\fR initially contain  .P
259  the entry points of the standard \fBmalloc()\fR and \fBfree()\fR functions  The function \fBpcre_refcount()\fP maintains a reference count in a data block
260    containing a compiled pattern. This is provided for the benefit of
261    object-oriented applications.
262    .P
263    The global variables \fBpcre_malloc\fP and \fBpcre_free\fP initially contain
264    the entry points of the standard \fBmalloc()\fP and \fBfree()\fP functions,
265  respectively. PCRE calls the memory management functions via these variables,  respectively. PCRE calls the memory management functions via these variables,
266  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
267  should be done before calling any PCRE functions.  should be done before calling any PCRE functions.
268    .P
269  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
270    indirections to memory management functions. These special functions are used
271    only when PCRE is compiled to use the heap for remembering data, instead of
272    recursive function calls, when running the \fBpcre_exec()\fP function. See the
273    .\" HREF
274    \fBpcrebuild\fP
275    .\"
276    documentation for details of how to do this. It is a non-standard way of
277    building PCRE, for use in environments that have limited stacks. Because of the
278    greater use of memory management, it runs more slowly. Separate functions are
279    provided so that special-purpose external code can be used for this case. When
280    used, these functions are always called in a stack-like manner (last obtained,
281    first freed), and always for memory blocks of the same size. There is a
282    discussion about PCRE's stack usage in the
283    .\" HREF
284    \fBpcrestack\fP
285    .\"
286    documentation.
287    .P
288    The global variable \fBpcre_callout\fP initially contains NULL. It can be set
289  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
290  points during a matching operation. Details are given in the \fBpcrecallout\fR  points during a matching operation. Details are given in the
291    .\" HREF
292    \fBpcrecallout\fP
293    .\"
294  documentation.  documentation.
295    .
296    .
297    .\" HTML <a name="newlines"></a>
298    .SH NEWLINES
299    .rs
300    .sp
301    PCRE supports five different conventions for indicating line breaks in
302    strings: a single CR (carriage return) character, a single LF (linefeed)
303    character, the two-character sequence CRLF, any of the three preceding, or any
304    Unicode newline sequence. The Unicode newline sequences are the three just
305    mentioned, plus the single characters VT (vertical tab, U+000B), FF (form feed,
306    U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
307    (paragraph separator, U+2029).
308    .P
309    Each of the first three conventions is used by at least one operating system as
310    its standard newline sequence. When PCRE is built, a default can be specified.
311    The default default is LF, which is the Unix standard. When PCRE is run, the
312    default can be overridden, either when a pattern is compiled, or when it is
313    matched.
314    .P
315    At compile time, the newline convention can be specified by the \fIoptions\fP
316    argument of \fBpcre_compile()\fP, or it can be specified by special text at the
317    start of the pattern itself; this overrides any other settings. See the
318    .\" HREF
319    \fBpcrepattern\fP
320    .\"
321    page for details of the special character sequences.
322    .P
323    In the PCRE documentation the word "newline" is used to mean "the character or
324    pair of characters that indicate a line break". The choice of newline
325    convention affects the handling of the dot, circumflex, and dollar
326    metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
327    recognized line ending sequence, the match position advancement for a
328    non-anchored pattern. There is more detail about this in the
329    .\" HTML <a href="#execoptions">
330    .\" </a>
331    section on \fBpcre_exec()\fP options
332    .\"
333    below.
334    .P
335    The choice of newline convention does not affect the interpretation of
336    the \en or \er escape sequences, nor does it affect what \eR matches, which is
337    controlled in a similar way, but by separate options.
338    .
339    .
340  .SH MULTITHREADING  .SH MULTITHREADING
341  .rs  .rs
342  .sp  .sp
343  The PCRE functions can be used in multi-threading applications, with the  The PCRE functions can be used in multi-threading applications, with the
344  proviso that the memory management functions pointed to by \fBpcre_malloc\fR  proviso that the memory management functions pointed to by \fBpcre_malloc\fP,
345  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
346  are shared by all threads.  callout function pointed to by \fBpcre_callout\fP, are shared by all threads.
347    .P
348  The compiled form of a regular expression is not altered during matching, so  The compiled form of a regular expression is not altered during matching, so
349  the same compiled pattern can safely be used by several threads at once.  the same compiled pattern can safely be used by several threads at once.
350    .P
351  .SH CHECKING BUILD-TIME OPTIONS  If the just-in-time optimization feature is being used, it needs separate
352    memory stack areas for each thread. See the
353    .\" HREF
354    \fBpcrejit\fP
355    .\"
356    documentation for more details.
357    .
358    .
359    .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"
360    .rs
361    .sp
362    The compiled form of a regular expression can be saved and re-used at a later
363    time, possibly by a different program, and even on a host other than the one on
364    which it was compiled. Details are given in the
365    .\" HREF
366    \fBpcreprecompile\fP
367    .\"
368    documentation, which includes a description of the
369    \fBpcre_pattern_to_host_byte_order()\fP function. However, compiling a regular
370    expression with one version of PCRE for use with a different version is not
371    guaranteed to work and may cause crashes.
372    .
373    .
374    .SH "CHECKING BUILD-TIME OPTIONS"
375  .rs  .rs
376  .sp  .sp
377  .B int pcre_config(int \fIwhat\fR, void *\fIwhere\fR);  .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
378  .PP  .PP
379  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
380  discover which optional features have been compiled into the PCRE library. The  discover which optional features have been compiled into the PCRE library. The
381  .\" HREF  .\" HREF
382  \fBpcrebuild\fR  \fBpcrebuild\fP
383  .\"  .\"
384  documentation has more details about these optional features.  documentation has more details about these optional features.
385    .P
386  The first argument for \fBpcre_config()\fR is an integer, specifying which  The first argument for \fBpcre_config()\fP is an integer, specifying which
387  information is required; the second argument is a pointer to a variable into  information is required; the second argument is a pointer to a variable into
388  which the information is placed. The following information is available:  which the information is placed. The returned value is zero on success, or the
389    negative error code PCRE_ERROR_BADOPTION if the value in the first argument is
390    not recognized. The following information is available:
391    .sp
392    PCRE_CONFIG_UTF8    PCRE_CONFIG_UTF8
393    .sp
394  The output is an integer that is set to one if UTF-8 support is available;  The output is an integer that is set to one if UTF-8 support is available;
395  otherwise it is set to zero.  otherwise it is set to zero. If this option is given to the 16-bit version of
396    this function, \fBpcre16_config()\fP, the result is PCRE_ERROR_BADOPTION.
397    .sp
398      PCRE_CONFIG_UTF16
399    .sp
400    The output is an integer that is set to one if UTF-16 support is available;
401    otherwise it is set to zero. This value should normally be given to the 16-bit
402    version of this function, \fBpcre16_config()\fP. If it is given to the 8-bit
403    version of this function, the result is PCRE_ERROR_BADOPTION.
404    .sp
405      PCRE_CONFIG_UNICODE_PROPERTIES
406    .sp
407    The output is an integer that is set to one if support for Unicode character
408    properties is available; otherwise it is set to zero.
409    .sp
410      PCRE_CONFIG_JIT
411    .sp
412    The output is an integer that is set to one if support for just-in-time
413    compiling is available; otherwise it is set to zero.
414    .sp
415      PCRE_CONFIG_JITTARGET
416    .sp
417    The output is a pointer to a zero-terminated "const char *" string. If JIT
418    support is available, the string contains the name of the architecture for
419    which the JIT compiler is configured, for example "x86 32bit (little endian +
420    unaligned)". If JIT support is not available, the result is NULL.
421    .sp
422    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
423    .sp
424  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
425  the newline character. It is either linefeed (10) or carriage return (13), and  that is recognized as meaning "newline". The values that are supported in
426  should normally be the standard character for your operating system.  ASCII/Unicode environments are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for
427    ANYCRLF, and -1 for ANY. In EBCDIC environments, CR, ANYCRLF, and ANY yield the
428    same values. However, the value for LF is normally 21, though some EBCDIC
429    environments use 37. The corresponding values for CRLF are 3349 and 3365. The
430    default should normally correspond to the standard sequence for your operating
431    system.
432    .sp
433      PCRE_CONFIG_BSR
434    .sp
435    The output is an integer whose value indicates what character sequences the \eR
436    escape sequence matches by default. A value of 0 means that \eR matches any
437    Unicode line ending sequence; a value of 1 means that \eR matches only CR, LF,
438    or CRLF. The default can be overridden when a pattern is compiled or matched.
439    .sp
440    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
441    .sp
442  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
443  linkage in compiled regular expressions. The value is 2, 3, or 4. Larger values  linkage in compiled regular expressions. For the 8-bit library, the value can
444  allow larger regular expressions to be compiled, at the expense of slower  be 2, 3, or 4. For the 16-bit library, the value is either 2 or 4 and is still
445  matching. The default value of 2 is sufficient for all but the most massive  a number of bytes. The default value of 2 is sufficient for all but the most
446  patterns, since it allows the compiled pattern to be up to 64K in size.  massive patterns, since it allows the compiled pattern to be up to 64K in size.
447    Larger values allow larger regular expressions to be compiled, at the expense
448    of slower matching.
449    .sp
450    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
451    .sp
452  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
453  interface uses \fBmalloc()\fR for output vectors. Further details are given in  interface uses \fBmalloc()\fP for output vectors. Further details are given in
454  the \fBpcreposix\fR documentation.  the
455    .\" HREF
456    \fBpcreposix\fP
457    .\"
458    documentation.
459    .sp
460    PCRE_CONFIG_MATCH_LIMIT    PCRE_CONFIG_MATCH_LIMIT
461    .sp
462  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
463  internal matching function calls in a \fBpcre_exec()\fR execution. Further  internal matching function calls in a \fBpcre_exec()\fP execution. Further
464  details are given with \fBpcre_exec()\fR below.  details are given with \fBpcre_exec()\fP below.
465    .sp
466  .SH COMPILING A PATTERN    PCRE_CONFIG_MATCH_LIMIT_RECURSION
467  .rs  .sp
468  .sp  The output is a long integer that gives the default limit for the depth of
469  .B pcre *pcre_compile(const char *\fIpattern\fR, int \fIoptions\fR,  recursion when calling the internal matching function in a \fBpcre_exec()\fP
470  .ti +5n  execution. Further details are given with \fBpcre_exec()\fP below.
471  .B const char **\fIerrptr\fR, int *\fIerroffset\fR,  .sp
472  .ti +5n    PCRE_CONFIG_STACKRECURSE
473  .B const unsigned char *\fItableptr\fR);  .sp
474  .PP  The output is an integer that is set to one if internal recursion when running
475    \fBpcre_exec()\fP is implemented by recursive function calls that use the stack
476  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
477  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
478  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
479  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
480  code and related data. The \fBpcre\fR type is defined for the returned block;  avoiding the use of the stack.
481  this is a typedef for a structure whose contents are not externally defined. It  .
482  is up to the caller to free the memory when it is no longer required.  .
483    .SH "COMPILING A PATTERN"
484    .rs
485    .sp
486    .B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,
487    .ti +5n
488    .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
489    .ti +5n
490    .B const unsigned char *\fItableptr\fP);
491    .sp
492    .B pcre *pcre_compile2(const char *\fIpattern\fP, int \fIoptions\fP,
493    .ti +5n
494    .B int *\fIerrorcodeptr\fP,
495    .ti +5n
496    .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
497    .ti +5n
498    .B const unsigned char *\fItableptr\fP);
499    .P
500    Either of the functions \fBpcre_compile()\fP or \fBpcre_compile2()\fP can be
501    called to compile a pattern into an internal form. The only difference between
502    the two interfaces is that \fBpcre_compile2()\fP has an additional argument,
503    \fIerrorcodeptr\fP, via which a numerical error code can be returned. To avoid
504    too much repetition, we refer just to \fBpcre_compile()\fP below, but the
505    information applies equally to \fBpcre_compile2()\fP.
506    .P
507    The pattern is a C string terminated by a binary zero, and is passed in the
508    \fIpattern\fP argument. A pointer to a single block of memory that is obtained
509    via \fBpcre_malloc\fP is returned. This contains the compiled code and related
510    data. The \fBpcre\fP type is defined for the returned block; this is a typedef
511    for a structure whose contents are not externally defined. It is up to the
512    caller to free the memory (via \fBpcre_free\fP) when it is no longer required.
513    .P
514  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
515  depend on memory location, the complete \fBpcre\fR data block is not  depend on memory location, the complete \fBpcre\fP data block is not
516  fully relocatable, because it contains a copy of the \fItableptr\fR argument,  fully relocatable, because it may contain a copy of the \fItableptr\fP
517  which is an address (see below).  argument, which is an address (see below).
518    .P
519  The \fIoptions\fR argument contains independent bits that affect the  The \fIoptions\fP argument contains various bit settings that affect the
520  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
521  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
522  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
523  in the \fBpcrepattern\fR documentation). For these options, the contents of the  within the pattern (see the detailed description in the
524  \fIoptions\fR argument specifies their initial settings at the start of  .\" HREF
525  compilation and execution. The PCRE_ANCHORED option can be set at the time of  \fBpcrepattern\fP
526  matching as well as at compile time.  .\"
527    documentation). For those options that can be different in different parts of
528  If \fIerrptr\fR is NULL, \fBpcre_compile()\fR returns NULL immediately.  the pattern, the contents of the \fIoptions\fP argument specifies their
529  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fR returns  settings at the start of compilation and execution. The PCRE_ANCHORED,
530  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
531  error message. The offset from the start of the pattern to the character where  PCRE_NO_START_OPTIMIZE options can be set at the time of matching as well as at
532  the error was discovered is placed in the variable pointed to by  compile time.
533  \fIerroffset\fR, which must not be NULL. If it is, an immediate error is given.  .P
534    If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
535  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
536  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
537  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
538  \fBpcre_maketables()\fR. See the section on locale support below.  not try to free it. Normally, the offset from the start of the pattern to the
539    byte that was being processed when the error was discovered is placed in the
540  This code fragment shows a typical straightforward call to \fBpcre_compile()\fR:  variable pointed to by \fIerroffset\fP, which must not be NULL (if it is, an
541    immediate error is given). However, for an invalid UTF-8 string, the offset is
542    that of the first byte of the failing character.
543    .P
544    Some errors are not detected until the whole pattern has been scanned; in these
545    cases, the offset passed back is the length of the pattern. Note that the
546    offset is in bytes, not characters, even in UTF-8 mode. It may sometimes point
547    into the middle of a UTF-8 character.
548    .P
549    If \fBpcre_compile2()\fP is used instead of \fBpcre_compile()\fP, and the
550    \fIerrorcodeptr\fP argument is not NULL, a non-zero error code number is
551    returned via this argument in the event of an error. This is in addition to the
552    textual error message. Error codes and messages are listed below.
553    .P
554    If the final argument, \fItableptr\fP, is NULL, PCRE uses a default set of
555    character tables that are built when PCRE is compiled, using the default C
556    locale. Otherwise, \fItableptr\fP must be an address that is the result of a
557    call to \fBpcre_maketables()\fP. This value is stored with the compiled
558    pattern, and used again by \fBpcre_exec()\fP, unless another table pointer is
559    passed to it. For more discussion, see the section on locale support below.
560    .P
561    This code fragment shows a typical straightforward call to \fBpcre_compile()\fP:
562    .sp
563    pcre *re;    pcre *re;
564    const char *error;    const char *error;
565    int erroffset;    int erroffset;
# Line 265  This code fragment shows a typical strai Line 569  This code fragment shows a typical strai
569      &error,           /* for error message */      &error,           /* for error message */
570      &erroffset,       /* for error offset */      &erroffset,       /* for error offset */
571      NULL);            /* use default character tables */      NULL);            /* use default character tables */
572    .sp
573  The following option bits are defined:  The following names for option bits are defined in the \fBpcre.h\fP header
574    file:
575    .sp
576    PCRE_ANCHORED    PCRE_ANCHORED
577    .sp
578  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
579  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
580  being searched (the "subject string"). This effect can also be achieved by  being searched (the "subject string"). This effect can also be achieved by
581  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
582  Perl.  Perl.
583    .sp
584      PCRE_AUTO_CALLOUT
585    .sp
586    If this bit is set, \fBpcre_compile()\fP automatically inserts callout items,
587    all with number 255, before each pattern item. For discussion of the callout
588    facility, see the
589    .\" HREF
590    \fBpcrecallout\fP
591    .\"
592    documentation.
593    .sp
594      PCRE_BSR_ANYCRLF
595      PCRE_BSR_UNICODE
596    .sp
597    These options (which are mutually exclusive) control what the \eR escape
598    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
599    match any Unicode newline sequence. The default is specified when PCRE is
600    built. It can be overridden from within the pattern, or by setting an option
601    when a compiled pattern is matched.
602    .sp
603    PCRE_CASELESS    PCRE_CASELESS
604    .sp
605  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
606  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
607  pattern by a (?i) option setting.  pattern by a (?i) option setting. In UTF-8 mode, PCRE always understands the
608    concept of case for characters whose values are less than 128, so caseless
609    matching is always possible. For characters with higher values, the concept of
610    case is supported if PCRE is compiled with Unicode property support, but not
611    otherwise. If you want to use caseless matching for characters 128 and above,
612    you must ensure that PCRE is compiled with Unicode property support as well as
613    with UTF-8 support.
614    .sp
615    PCRE_DOLLAR_ENDONLY    PCRE_DOLLAR_ENDONLY
616    .sp
617  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
618  end of the subject string. Without this option, a dollar also matches  end of the subject string. Without this option, a dollar also matches
619  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
620  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.
621  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
622  a pattern.  pattern.
623    .sp
624    PCRE_DOTALL    PCRE_DOTALL
625    .sp
626  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
627  including newlines. Without it, newlines are excluded. This option is  any value, including one that indicates a newline. However, it only ever
628    matches one character, even if newlines are coded as CRLF. Without this option,
629    a dot does not match when the current position is at a newline. This option is
630  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
631  (?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
632  character, independent of the setting of this option.  characters, independent of the setting of this option.
633    .sp
634      PCRE_DUPNAMES
635    .sp
636    If this bit is set, names used to identify capturing subpatterns need not be
637    unique. This can be helpful for certain types of pattern when it is known that
638    only one instance of the named subpattern can ever be matched. There are more
639    details of named subpatterns below; see also the
640    .\" HREF
641    \fBpcrepattern\fP
642    .\"
643    documentation.
644    .sp
645    PCRE_EXTENDED    PCRE_EXTENDED
646    .sp
647  If this bit is set, whitespace data characters in the pattern are totally  If this bit is set, white space data characters in the pattern are totally
648  ignored except when escaped or inside a character class. Whitespace does not  ignored except when escaped or inside a character class. White space does not
649  include the VT character (code 11). In addition, characters between an  include the VT character (code 11). In addition, characters between an
650  unescaped # outside a character class and the next newline character,  unescaped # outside a character class and the next newline, inclusive, are also
651  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
652  be changed within a pattern by a (?x) option setting.  pattern by a (?x) option setting.
653    .P
654    Which characters are interpreted as newlines is controlled by the options
655    passed to \fBpcre_compile()\fP or by a special sequence at the start of the
656    pattern, as described in the section entitled
657    .\" HTML <a href="pcrepattern.html#newlines">
658    .\" </a>
659    "Newline conventions"
660    .\"
661    in the \fBpcrepattern\fP documentation. Note that the end of this type of
662    comment is a literal newline sequence in the pattern; escape sequences that
663    happen to represent a newline do not count.
664    .P
665  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
666  Note, however, that this applies only to data characters. Whitespace characters  Note, however, that this applies only to data characters. White space characters
667  may never appear within special character sequences in a pattern, for example  may never appear within special character sequences in a pattern, for example
668  within the sequence (?( which introduces a conditional subpattern.  within the sequence (?( that introduces a conditional subpattern.
669    .sp
670    PCRE_EXTRA    PCRE_EXTRA
671    .sp
672  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
673  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
674  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
675  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
676  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
677  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
678  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
679  pattern.  no other features controlled by this option. It can also be set by a (?X)
680    option setting within a pattern.
681    .sp
682      PCRE_FIRSTLINE
683    .sp
684    If this option is set, an unanchored pattern is required to match before or at
685    the first newline in the subject string, though the matched text may continue
686    over the newline.
687    .sp
688      PCRE_JAVASCRIPT_COMPAT
689    .sp
690    If this option is set, PCRE's behaviour is changed in some ways so that it is
691    compatible with JavaScript rather than Perl. The changes are as follows:
692    .P
693    (1) A lone closing square bracket in a pattern causes a compile-time error,
694    because this is illegal in JavaScript (by default it is treated as a data
695    character). Thus, the pattern AB]CD becomes illegal when this option is set.
696    .P
697    (2) At run time, a back reference to an unset subpattern group matches an empty
698    string (by default this causes the current matching alternative to fail). A
699    pattern such as (\e1)(a) succeeds when this option is set (assuming it can find
700    an "a" in the subject), whereas it fails by default, for Perl compatibility.
701    .P
702    (3) \eU matches an upper case "U" character; by default \eU causes a compile
703    time error (Perl uses \eU to upper case subsequent characters).
704    .P
705    (4) \eu matches a lower case "u" character unless it is followed by four
706    hexadecimal digits, in which case the hexadecimal number defines the code point
707    to match. By default, \eu causes a compile time error (Perl uses it to upper
708    case the following character).
709    .P
710    (5) \ex matches a lower case "x" character unless it is followed by two
711    hexadecimal digits, in which case the hexadecimal number defines the code point
712    to match. By default, as in Perl, a hexadecimal number is always expected after
713    \ex, but it may have zero, one, or two digits (so, for example, \exz matches a
714    binary zero character followed by z).
715    .sp
716    PCRE_MULTILINE    PCRE_MULTILINE
717    .sp
718  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
719  characters (even if it actually contains several newlines). The "start of line"  characters (even if it actually contains newlines). The "start of line"
720  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
721  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
722  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
723  Perl.  Perl.
724    .P
725  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
726  match immediately following or immediately before any newline in the subject  match immediately following or immediately before internal newlines in the
727  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
728  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
729  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
730  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.
731    .sp
732      PCRE_NEWLINE_CR
733      PCRE_NEWLINE_LF
734      PCRE_NEWLINE_CRLF
735      PCRE_NEWLINE_ANYCRLF
736      PCRE_NEWLINE_ANY
737    .sp
738    These options override the default newline definition that was chosen when PCRE
739    was built. Setting the first or the second specifies that a newline is
740    indicated by a single character (CR or LF, respectively). Setting
741    PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
742    CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three
743    preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies
744    that any Unicode newline sequence should be recognized.
745    .P
746    In an ASCII/Unicode environment, the Unicode newline sequences are the three
747    just mentioned, plus the single characters VT (vertical tab, U+000B), FF (form
748    feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
749    (paragraph separator, U+2029). For the 8-bit library, the last two are
750    recognized only in UTF-8 mode.
751    .P
752    When PCRE is compiled to run in an EBCDIC (mainframe) environment, the code for
753    CR is 0x0d, the same as ASCII. However, the character code for LF is normally
754    0x15, though in some EBCDIC environments 0x25 is used. Whichever of these is
755    not LF is made to correspond to Unicode's NEL character. EBCDIC codes are all
756    less than 256. For more details, see the
757    .\" HREF
758    \fBpcrebuild\fP
759    .\"
760    documentation.
761    .P
762    The newline setting in the options word uses three bits that are treated
763    as a number, giving eight possibilities. Currently only six are used (default
764    plus the five values above). This means that if you set more than one newline
765    option, the combination may or may not be sensible. For example,
766    PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
767    other combinations may yield unused numbers and cause an error.
768    .P
769    The only time that a line break in a pattern is specially recognized when
770    compiling is when PCRE_EXTENDED is set. CR and LF are white space characters,
771    and so are ignored in this mode. Also, an unescaped # outside a character class
772    indicates a comment that lasts until after the next line break sequence. In
773    other circumstances, line break sequences in patterns are treated as literal
774    data.
775    .P
776    The newline option that is set at compile time becomes the default that is used
777    for \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, but it can be overridden.
778    .sp
779    PCRE_NO_AUTO_CAPTURE    PCRE_NO_AUTO_CAPTURE
780    .sp
781  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
782  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
783  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
784  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
785  in Perl.  in Perl.
786    .sp
787      NO_START_OPTIMIZE
788    .sp
789    This is an option that acts at matching time; that is, it is really an option
790    for \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. If it is set at compile time,
791    it is remembered with the compiled pattern and assumed at matching time. For
792    details see the discussion of PCRE_NO_START_OPTIMIZE
793    .\" HTML <a href="#execoptions">
794    .\" </a>
795    below.
796    .\"
797    .sp
798      PCRE_UCP
799    .sp
800    This option changes the way PCRE processes \eB, \eb, \eD, \ed, \eS, \es, \eW,
801    \ew, and some of the POSIX character classes. By default, only ASCII characters
802    are recognized, but if PCRE_UCP is set, Unicode properties are used instead to
803    classify characters. More details are given in the section on
804    .\" HTML <a href="pcre.html#genericchartypes">
805    .\" </a>
806    generic character types
807    .\"
808    in the
809    .\" HREF
810    \fBpcrepattern\fP
811    .\"
812    page. If you set PCRE_UCP, matching one of the items it affects takes much
813    longer. The option is available only if PCRE has been compiled with Unicode
814    property support.
815    .sp
816    PCRE_UNGREEDY    PCRE_UNGREEDY
817    .sp
818  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
819  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
820  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.
821    .sp
822    PCRE_UTF8    PCRE_UTF8
823    .sp
824  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
825  of UTF-8 characters instead of single-byte character strings. However, it is  of UTF-8 characters instead of single-byte strings. However, it is available
826  available only if PCRE has been built to include UTF-8 support. If not, the use  only when PCRE is built to include UTF support. If not, the use of this option
827  of this option provokes an error. Details of how this option changes the  provokes an error. Details of how this option changes the behaviour of PCRE are
828  behaviour of PCRE are given in the  given in the
829  .\" HTML <a href="pcre.html#utf8support">  .\" HREF
830    \fBpcreunicode\fP
831    .\"
832    page.
833    .sp
834      PCRE_NO_UTF8_CHECK
835    .sp
836    When PCRE_UTF8 is set, the validity of the pattern as a UTF-8
837    string is automatically checked. There is a discussion about the
838    .\" HTML <a href="pcreunicode.html#utf8strings">
839  .\" </a>  .\" </a>
840  section on UTF-8 support  validity of UTF-8 strings
841  .\"  .\"
842  in the main  in the
843  .\" HREF  .\" HREF
844  \fBpcre\fR  \fBpcreunicode\fP
845  .\"  .\"
846  page.  page. If an invalid UTF-8 sequence is found, \fBpcre_compile()\fP returns an
847    error. If you already know that your pattern is valid, and you want to skip
848  .SH STUDYING A PATTERN  this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK option.
849    When it is set, the effect of passing an invalid UTF-8 string as a pattern is
850    undefined. It may cause your program to crash. Note that this option can also
851    be passed to \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, to suppress the
852    validity checking of subject strings.
853    .
854    .
855    .SH "COMPILATION ERROR CODES"
856    .rs
857    .sp
858    The following table lists the error codes than may be returned by
859    \fBpcre_compile2()\fP, along with the error messages that may be returned by
860    both compiling functions. Note that error messages are always 8-bit ASCII
861    strings, even in 16-bit mode. As PCRE has developed, some error codes have
862    fallen out of use. To avoid confusion, they have not been re-used.
863    .sp
864       0  no error
865       1  \e at end of pattern
866       2  \ec at end of pattern
867       3  unrecognized character follows \e
868       4  numbers out of order in {} quantifier
869       5  number too big in {} quantifier
870       6  missing terminating ] for character class
871       7  invalid escape sequence in character class
872       8  range out of order in character class
873       9  nothing to repeat
874      10  [this code is not in use]
875      11  internal error: unexpected repeat
876      12  unrecognized character after (? or (?-
877      13  POSIX named classes are supported only within a class
878      14  missing )
879      15  reference to non-existent subpattern
880      16  erroffset passed as NULL
881      17  unknown option bit(s) set
882      18  missing ) after comment
883      19  [this code is not in use]
884      20  regular expression is too large
885      21  failed to get memory
886      22  unmatched parentheses
887      23  internal error: code overflow
888      24  unrecognized character after (?<
889      25  lookbehind assertion is not fixed length
890      26  malformed number or name after (?(
891      27  conditional group contains more than two branches
892      28  assertion expected after (?(
893      29  (?R or (?[+-]digits must be followed by )
894      30  unknown POSIX class name
895      31  POSIX collating elements are not supported
896      32  this version of PCRE is compiled without UTF support
897      33  [this code is not in use]
898      34  character value in \ex{...} sequence is too large
899      35  invalid condition (?(0)
900      36  \eC not allowed in lookbehind assertion
901      37  PCRE does not support \eL, \el, \eN{name}, \eU, or \eu
902      38  number after (?C is > 255
903      39  closing ) for (?C expected
904      40  recursive call could loop indefinitely
905      41  unrecognized character after (?P
906      42  syntax error in subpattern name (missing terminator)
907      43  two named subpatterns have the same name
908      44  invalid UTF-8 string (specifically UTF-8)
909      45  support for \eP, \ep, and \eX has not been compiled
910      46  malformed \eP or \ep sequence
911      47  unknown property name after \eP or \ep
912      48  subpattern name is too long (maximum 32 characters)
913      49  too many named subpatterns (maximum 10000)
914      50  [this code is not in use]
915      51  octal value is greater than \e377 in 8-bit non-UTF-8 mode
916      52  internal error: overran compiling workspace
917      53  internal error: previously-checked referenced subpattern
918            not found
919      54  DEFINE group contains more than one branch
920      55  repeating a DEFINE group is not allowed
921      56  inconsistent NEWLINE options
922      57  \eg is not followed by a braced, angle-bracketed, or quoted
923            name/number or by a plain number
924      58  a numbered reference must not be zero
925      59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
926      60  (*VERB) not recognized
927      61  number is too big
928      62  subpattern name expected
929      63  digit expected after (?+
930      64  ] is an invalid data character in JavaScript compatibility mode
931      65  different names for subpatterns of the same number are
932            not allowed
933      66  (*MARK) must have an argument
934      67  this version of PCRE is not compiled with Unicode property
935            support
936      68  \ec must be followed by an ASCII character
937      69  \ek is not followed by a braced, angle-bracketed, or quoted name
938      70  internal error: unknown opcode in find_fixedlength()
939      71  \eN is not supported in a class
940      72  too many forward references
941      73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
942      74  invalid UTF-16 string (specifically UTF-16)
943      75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
944      76  character value in \eu.... sequence is too large
945    .sp
946    The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
947    be used if the limits were changed when PCRE was built.
948    .
949    .
950    .\" HTML <a name="studyingapattern"></a>
951    .SH "STUDYING A PATTERN"
952  .rs  .rs
953  .sp  .sp
954  .B pcre_extra *pcre_study(const pcre *\fIcode\fR, int \fIoptions\fR,  .B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP
955  .ti +5n  .ti +5n
956  .B const char **\fIerrptr\fR);  .B const char **\fIerrptr\fP);
957  .PP  .PP
958  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
959  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
960  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
961  argument. If studing the pattern produces additional information that will help  argument. If studying the pattern produces additional information that will
962  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
963  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
964    results of the study.
965  The returned value from a \fBpcre_study()\fR can be passed directly to  .P
966  \fBpcre_exec()\fR. However, the \fBpcre_extra\fR block also contains other  The returned value from \fBpcre_study()\fP can be passed directly to
967  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
968  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
969  information, \fBpcre_study()\fR returns NULL. In that circumstance, if the  passed; these are described
970  calling program wants to pass some of the other fields to \fBpcre_exec()\fR, it  .\" HTML <a href="#extradata">
971  must set up its own \fBpcre_extra\fR block.  .\" </a>
972    below
973  The second argument contains option bits. At present, no options are defined  .\"
974  for \fBpcre_study()\fR, and this argument should always be zero.  in the section on matching a pattern.
975    .P
976  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,
977    \fBpcre_study()\fP returns NULL by default. In that circumstance, if the
978    calling program wants to pass any of the other fields to \fBpcre_exec()\fP or
979    \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block. However,
980    if \fBpcre_study()\fP is called with the PCRE_STUDY_EXTRA_NEEDED option, it
981    returns a \fBpcre_extra\fP block even if studying did not find any additional
982    information. It may still return NULL, however, if an error occurs in
983    \fBpcre_study()\fP.
984    .P
985    The second argument of \fBpcre_study()\fP contains option bits. There are three
986    further options in addition to PCRE_STUDY_EXTRA_NEEDED:
987    .sp
988      PCRE_STUDY_JIT_COMPILE
989      PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
990      PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
991    .sp
992    If any of these are set, and the just-in-time compiler is available, the
993    pattern is further compiled into machine code that executes much faster than
994    the \fBpcre_exec()\fP interpretive matching function. If the just-in-time
995    compiler is not available, these options are ignored. All undefined bits in the
996    \fIoptions\fP argument must be zero.
997    .P
998    JIT compilation is a heavyweight optimization. It can take some time for
999    patterns to be analyzed, and for one-off matches and simple patterns the
1000    benefit of faster execution might be offset by a much slower study time.
1001    Not all patterns can be optimized by the JIT compiler. For those that cannot be
1002    handled, matching automatically falls back to the \fBpcre_exec()\fP
1003    interpreter. For more details, see the
1004    .\" HREF
1005    \fBpcrejit\fP
1006    .\"
1007    documentation.
1008    .P
1009    The third argument for \fBpcre_study()\fP is a pointer for an error message. If
1010  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
1011  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
1012  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
1013  be sure that it has run successfully.  should test the error pointer for NULL after calling \fBpcre_study()\fP, to be
1014    sure that it has run successfully.
1015  This is a typical call to \fBpcre_study\fR():  .P
1016    When you are finished with a pattern, you can free the memory used for the
1017    pcre_extra *pe;  study data by calling \fBpcre_free_study()\fP. This function was added to the
1018    pe = pcre_study(  API for release 8.20. For earlier versions, the memory could be freed with
1019    \fBpcre_free()\fP, just like the pattern itself. This will still work in cases
1020    where JIT optimization is not used, but it is advisable to change to the new
1021    function when convenient.
1022    .P
1023    This is a typical way in which \fBpcre_study\fP() is used (except that in a
1024    real application there should be tests for errors):
1025    .sp
1026      int rc;
1027      pcre *re;
1028      pcre_extra *sd;
1029      re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
1030      sd = pcre_study(
1031      re,             /* result of pcre_compile() */      re,             /* result of pcre_compile() */
1032      0,              /* no options exist */      0,              /* no options */
1033      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
1034      rc = pcre_exec(   /* see below for details of pcre_exec() options */
1035  At present, studying a pattern is useful only for non-anchored patterns that do      re, sd, "subject", 7, 0, 0, ovector, 30);
1036  not have a single fixed starting character. A bitmap of possible starting    ...
1037  characters is created.    pcre_free_study(sd);
1038      pcre_free(re);
1039    .sp
1040    Studying a pattern does two things: first, a lower bound for the length of
1041    subject string that is needed to match the pattern is computed. This does not
1042    mean that there are any strings of that length that match, but it does
1043    guarantee that no shorter strings match. The value is used to avoid wasting
1044    time by trying to match strings that are shorter than the lower bound. You can
1045    find out the value in a calling program via the \fBpcre_fullinfo()\fP function.
1046    .P
1047    Studying a pattern is also useful for non-anchored patterns that do not have a
1048    single fixed starting character. A bitmap of possible starting bytes is
1049    created. This speeds up finding a position in the subject at which to start
1050    matching. (In 16-bit mode, the bitmap is used for 16-bit values less than 256.)
1051    .P
1052    These two optimizations apply to both \fBpcre_exec()\fP and
1053    \fBpcre_dfa_exec()\fP, and the information is also used by the JIT compiler.
1054    The optimizations can be disabled by setting the PCRE_NO_START_OPTIMIZE option
1055    when calling \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP, but if this is done,
1056    JIT execution is also disabled. You might want to do this if your pattern
1057    contains callouts or (*MARK) and you want to make use of these facilities in
1058    cases where matching fails. See the discussion of PCRE_NO_START_OPTIMIZE
1059    .\" HTML <a href="#execoptions">
1060    .\" </a>
1061    below.
1062    .\"
1063    .
1064    .
1065  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
1066  .SH LOCALE SUPPORT  .SH "LOCALE SUPPORT"
1067  .rs  .rs
1068  .sp  .sp
1069  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters,
1070  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
1071  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
1072  contains a default set of tables that is created in the default C locale when  with codes less than 128. By default, higher-valued codes never match escapes
1073  PCRE is compiled. This is used when the final argument of \fBpcre_compile()\fR  such as \ew or \ed, but they can be tested with \ep if PCRE is built with
1074  is NULL, and is sufficient for many applications.  Unicode character property support. Alternatively, the PCRE_UCP option can be
1075    set at compile time; this causes \ew and friends to use Unicode property
1076  An alternative set of tables can, however, be supplied. Such tables are built  support instead of built-in tables. The use of locales with Unicode is
1077  by calling the \fBpcre_maketables()\fR function, which has no arguments, in the  discouraged. If you are handling characters with codes greater than 128, you
1078  relevant locale. The result can then be passed to \fBpcre_compile()\fR as often  should either use UTF-8 and Unicode, or use locales, but not try to mix the
1079  as necessary. For example, to build and use tables that are appropriate for the  two.
1080  French locale (where accented characters with codes greater than 128 are  .P
1081  treated as letters), the following code could be used:  PCRE contains an internal set of tables that are used when the final argument
1082    of \fBpcre_compile()\fP is NULL. These are sufficient for many applications.
1083    setlocale(LC_CTYPE, "fr");  Normally, the internal tables recognize only ASCII characters. However, when
1084    PCRE is built, it is possible to cause the internal tables to be rebuilt in the
1085    default "C" locale of the local system, which may cause them to be different.
1086    .P
1087    The internal tables can always be overridden by tables supplied by the
1088    application that calls PCRE. These may be created in a different locale from
1089    the default. As more and more applications change to using Unicode, the need
1090    for this locale support is expected to die away.
1091    .P
1092    External tables are built by calling the \fBpcre_maketables()\fP function,
1093    which has no arguments, in the relevant locale. The result can then be passed
1094    to \fBpcre_compile()\fP or \fBpcre_exec()\fP as often as necessary. For
1095    example, to build and use tables that are appropriate for the French locale
1096    (where accented characters with values greater than 128 are treated as letters),
1097    the following code could be used:
1098    .sp
1099      setlocale(LC_CTYPE, "fr_FR");
1100    tables = pcre_maketables();    tables = pcre_maketables();
1101    re = pcre_compile(..., tables);    re = pcre_compile(..., tables);
1102    .sp
1103  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
1104  pointer that is passed to \fBpcre_compile\fR is saved with the compiled  are using Windows, the name for the French locale is "french".
1105  pattern, and the same tables are used via this pointer by \fBpcre_study()\fR  .P
1106  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
1107  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
1108  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
1109  memory containing the tables remains available for as long as it is needed.  needed.
1110    .P
1111  .SH INFORMATION ABOUT A PATTERN  The pointer that is passed to \fBpcre_compile()\fP is saved with the compiled
1112  .rs  pattern, and the same tables are used via this pointer by \fBpcre_study()\fP
1113  .sp  and normally also by \fBpcre_exec()\fP. Thus, by default, for any single
1114  .B int pcre_fullinfo(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"  pattern, compilation, studying and matching all happen in the same locale, but
1115  .ti +5n  different patterns can be compiled in different locales.
1116  .B int \fIwhat\fR, void *\fIwhere\fR);  .P
1117  .PP  It is possible to pass a table pointer or NULL (indicating the use of the
1118  The \fBpcre_fullinfo()\fR function returns information about a compiled  internal tables) to \fBpcre_exec()\fP. Although not intended for this purpose,
1119  pattern. It replaces the obsolete \fBpcre_info()\fR function, which is  this facility could be used to match a pattern in a different locale from the
1120  nevertheless retained for backwards compability (and is documented below).  one in which it was compiled. Passing table pointers at run time is discussed
1121    below in the section on matching a pattern.
1122  The first argument for \fBpcre_fullinfo()\fR is a pointer to the compiled  .
1123  pattern. The second argument is the result of \fBpcre_study()\fR, or NULL if  .
1124    .\" HTML <a name="infoaboutpattern"></a>
1125    .SH "INFORMATION ABOUT A PATTERN"
1126    .rs
1127    .sp
1128    .B int pcre_fullinfo(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
1129    .ti +5n
1130    .B int \fIwhat\fP, void *\fIwhere\fP);
1131    .PP
1132    The \fBpcre_fullinfo()\fP function returns information about a compiled
1133    pattern. It replaces the \fBpcre_info()\fP function, which was removed from the
1134    library at version 8.30, after more than 10 years of obsolescence.
1135    .P
1136    The first argument for \fBpcre_fullinfo()\fP is a pointer to the compiled
1137    pattern. The second argument is the result of \fBpcre_study()\fP, or NULL if
1138  the pattern was not studied. The third argument specifies which piece of  the pattern was not studied. The third argument specifies which piece of
1139  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
1140  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
1141  the following negative numbers:  the following negative numbers:
1142    .sp
1143    PCRE_ERROR_NULL       the argument \fIcode\fR was NULL    PCRE_ERROR_NULL           the argument \fIcode\fP was NULL
1144                          the argument \fIwhere\fR was NULL                              the argument \fIwhere\fP was NULL
1145    PCRE_ERROR_BADMAGIC   the "magic number" was not found    PCRE_ERROR_BADMAGIC       the "magic number" was not found
1146    PCRE_ERROR_BADOPTION  the value of \fIwhat\fR was invalid    PCRE_ERROR_BADENDIANNESS  the pattern was compiled with different
1147                                endianness
1148  Here is a typical call of \fBpcre_fullinfo()\fR, to obtain the length of the    PCRE_ERROR_BADOPTION      the value of \fIwhat\fP was invalid
1149  compiled pattern:  .sp
1150    The "magic number" is placed at the start of each compiled pattern as an simple
1151    check against passing an arbitrary memory pointer. The endianness error can
1152    occur if a compiled pattern is saved and reloaded on a different host. Here is
1153    a typical call of \fBpcre_fullinfo()\fP, to obtain the length of the compiled
1154    pattern:
1155    .sp
1156    int rc;    int rc;
1157    unsigned long int length;    size_t length;
1158    rc = pcre_fullinfo(    rc = pcre_fullinfo(
1159      re,               /* result of pcre_compile() */      re,               /* result of pcre_compile() */
1160      pe,               /* result of pcre_study(), or NULL */      sd,               /* result of pcre_study(), or NULL */
1161      PCRE_INFO_SIZE,   /* what is required */      PCRE_INFO_SIZE,   /* what is required */
1162      &length);         /* where to put the data */      &length);         /* where to put the data */
1163    .sp
1164  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
1165  as follows:  as follows:
1166    .sp
1167    PCRE_INFO_BACKREFMAX    PCRE_INFO_BACKREFMAX
1168    .sp
1169  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
1170  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
1171  no back references.  no back references.
1172    .sp
1173    PCRE_INFO_CAPTURECOUNT    PCRE_INFO_CAPTURECOUNT
1174    .sp
1175  Return the number of capturing subpatterns in the pattern. The fourth argument  Return the number of capturing subpatterns in the pattern. The fourth argument
1176  should point to an \fbint\fR variable.  should point to an \fBint\fP variable.
1177    .sp
1178      PCRE_INFO_DEFAULT_TABLES
1179    .sp
1180    Return a pointer to the internal default character tables within PCRE. The
1181    fourth argument should point to an \fBunsigned char *\fP variable. This
1182    information call is provided for internal use by the \fBpcre_study()\fP
1183    function. External callers can cause PCRE to use its internal tables by passing
1184    a NULL table pointer.
1185    .sp
1186    PCRE_INFO_FIRSTBYTE    PCRE_INFO_FIRSTBYTE
1187    .sp
1188  Return information about the first byte of any matched string, for a  Return information about the first data unit of any matched string, for a
1189  non-anchored pattern. (This option used to be called PCRE_INFO_FIRSTCHAR; the  non-anchored pattern. (The name of this option refers to the 8-bit library,
1190  old name is still recognized for backwards compatibility.)  where data units are bytes.) The fourth argument should point to an \fBint\fP
1191    variable.
1192  If there is a fixed first byte, e.g. from a pattern such as (cat|cow|coyote),  .P
1193  it is returned in the integer pointed to by \fIwhere\fR. Otherwise, if either  If there is a fixed first value, for example, the letter "c" from a pattern
1194    such as (cat|cow|coyote), its value is returned. In the 8-bit library, the
1195    value is always less than 256; in the 16-bit library the value can be up to
1196    0xffff.
1197    .P
1198    If there is no fixed first value, and if either
1199    .sp
1200  (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
1201  starts with "^", or  starts with "^", or
1202    .sp
1203  (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
1204  (if it were set, the pattern would be anchored),  (if it were set, the pattern would be anchored),
1205    .sp
1206  -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
1207  subject string or after any newline within the string. Otherwise -2 is  subject string or after any newline within the string. Otherwise -2 is
1208  returned. For anchored patterns, -2 is returned.  returned. For anchored patterns, -2 is returned.
1209    .sp
1210    PCRE_INFO_FIRSTTABLE    PCRE_INFO_FIRSTTABLE
1211    .sp
1212  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
1213  table indicating a fixed set of bytes for the first byte in any matching  table indicating a fixed set of values for the first data unit in any matching
1214  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
1215  fourth argument should point to an \fBunsigned char *\fR variable.  fourth argument should point to an \fBunsigned char *\fP variable.
1216    .sp
1217      PCRE_INFO_HASCRORLF
1218    .sp
1219    Return 1 if the pattern contains any explicit matches for CR or LF characters,
1220    otherwise 0. The fourth argument should point to an \fBint\fP variable. An
1221    explicit match is either a literal CR or LF character, or \er or \en.
1222    .sp
1223      PCRE_INFO_JCHANGED
1224    .sp
1225    Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise
1226    0. The fourth argument should point to an \fBint\fP variable. (?J) and
1227    (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
1228    .sp
1229      PCRE_INFO_JIT
1230    .sp
1231    Return 1 if the pattern was studied with one of the JIT options, and
1232    just-in-time compiling was successful. The fourth argument should point to an
1233    \fBint\fP variable. A return value of 0 means that JIT support is not available
1234    in this version of PCRE, or that the pattern was not studied with a JIT option,
1235    or that the JIT compiler could not handle this particular pattern. See the
1236    .\" HREF
1237    \fBpcrejit\fP
1238    .\"
1239    documentation for details of what can and cannot be handled.
1240    .sp
1241      PCRE_INFO_JITSIZE
1242    .sp
1243    If the pattern was successfully studied with a JIT option, return the size of
1244    the JIT compiled code, otherwise return zero. The fourth argument should point
1245    to a \fBsize_t\fP variable.
1246    .sp
1247    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
1248    .sp
1249  For a non-anchored pattern, return the value of the rightmost literal byte  Return the value of the rightmost literal data unit that must exist in any
1250  which must exist in any matched string, other than at its start. The fourth  matched string, other than at its start, if such a value has been recorded. The
1251  argument should point to an \fBint\fR variable. If there is no such byte, or if  fourth argument should point to an \fBint\fP variable. If there is no such
1252  the pattern is anchored, -1 is returned. For example, for the pattern  value, -1 is returned. For anchored patterns, a last literal value is recorded
1253  /a\\d+z\\d+/ the returned value is 'z'.  only if it follows something of variable length. For example, for the pattern
1254    /^a\ed+z\ed+/ the returned value is "z", but for /^a\edz\ed/ the returned value
1255    is -1.
1256    .sp
1257      PCRE_INFO_MAXLOOKBEHIND
1258    .sp
1259    Return the number of characters (NB not bytes) in the longest lookbehind
1260    assertion in the pattern. Note that the simple assertions \eb and \eB require a
1261    one-character lookbehind. This information is useful when doing multi-segment
1262    matching using the partial matching facilities.
1263    .sp
1264      PCRE_INFO_MINLENGTH
1265    .sp
1266    If the pattern was studied and a minimum length for matching subject strings
1267    was computed, its value is returned. Otherwise the returned value is -1. The
1268    value is a number of characters, which in UTF-8 mode may be different from the
1269    number of bytes. The fourth argument should point to an \fBint\fP variable. A
1270    non-negative value is a lower bound to the length of any matching string. There
1271    may not be any strings of that length that do actually match, but every string
1272    that does match is at least that long.
1273    .sp
1274    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
1275    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
1276    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
1277    .sp
1278  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
1279  names are just an additional way of identifying the parentheses, which still  names are just an additional way of identifying the parentheses, which still
1280  acquire a number. A caller that wants to extract data from a named subpattern  acquire numbers. Several convenience functions such as
1281  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
1282  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
1283  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
1284  table for the pattern.  output vector (described with \fBpcre_exec()\fP below). To do the conversion,
1285    you need to use the name-to-number map, which is described by these three
1286    values.
1287    .P
1288  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
1289  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
1290  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
1291  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
1292  entry of the table (a pointer to \fBchar\fR). The first two bytes of each entry  entry of the table. This is a pointer to \fBchar\fP in the 8-bit library, where
1293  are the number of the capturing parenthesis, most significant byte first. The  the first two bytes of each entry are the number of the capturing parenthesis,
1294  rest of the entry is the corresponding name, zero terminated. The names are in  most significant byte first. In the 16-bit library, the pointer points to
1295  alphabetical order. For example, consider the following pattern (assume  16-bit data units, the first of which contains the parenthesis number. The rest
1296  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  of the entry is the corresponding name, zero terminated.
1297    .P
1298    (?P<date> (?P<year>(\\d\\d)?\\d\\d) -  The names are in alphabetical order. Duplicate names may appear if (?| is used
1299    (?P<month>\\d\\d) - (?P<day>\\d\\d) )  to create multiple groups with the same number, as described in the
1300    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1301    .\" </a>
1302    section on duplicate subpattern numbers
1303    .\"
1304    in the
1305    .\" HREF
1306    \fBpcrepattern\fP
1307    .\"
1308    page. Duplicate names for subpatterns with different numbers are permitted only
1309    if PCRE_DUPNAMES is set. In all cases of duplicate names, they appear in the
1310    table in the order in which they were found in the pattern. In the absence of
1311    (?| this is the order of increasing number; when (?| is used this is not
1312    necessarily the case because later subpatterns may have lower numbers.
1313    .P
1314    As a simple example of the name/number table, consider the following pattern
1315    after compilation by the 8-bit library (assume PCRE_EXTENDED is set, so white
1316    space - including newlines - is ignored):
1317    .sp
1318    .\" JOIN
1319      (?<date> (?<year>(\ed\ed)?\ed\ed) -
1320      (?<month>\ed\ed) - (?<day>\ed\ed) )
1321    .sp
1322  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
1323  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
1324  bytes shows in hex, and undefined bytes shown as ??:  bytes shows in hexadecimal, and undefined bytes shown as ??:
1325    .sp
1326    00 01 d  a  t  e  00 ??    00 01 d  a  t  e  00 ??
1327    00 05 d  a  y  00 ?? ??    00 05 d  a  y  00 ?? ??
1328    00 04 m  o  n  t  h  00    00 04 m  o  n  t  h  00
1329    00 02 y  e  a  r  00 ??    00 02 y  e  a  r  00 ??
1330    .sp
1331  When writing code to extract data from named subpatterns, remember that the  When writing code to extract data from named subpatterns using the
1332  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
1333    different for each compiled pattern.
1334    .sp
1335      PCRE_INFO_OKPARTIAL
1336    .sp
1337    Return 1 if the pattern can be used for partial matching with
1338    \fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
1339    \fBint\fP variable. From release 8.00, this always returns 1, because the
1340    restrictions that previously applied to partial matching have been lifted. The
1341    .\" HREF
1342    \fBpcrepartial\fP
1343    .\"
1344    documentation gives details of partial matching.
1345    .sp
1346    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1347    .sp
1348  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
1349  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
1350  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
1351  top-level option settings within the pattern itself.  top-level option settings at the start of the pattern itself. In other words,
1352    they are the options that will be in force when matching starts. For example,
1353    if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED option, the
1354    result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED.
1355    .P
1356  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
1357  alternatives begin with one of the following:  alternatives begin with one of the following:
1358    .sp
1359    ^     unless PCRE_MULTILINE is set    ^     unless PCRE_MULTILINE is set
1360    \\A    always    \eA    always
1361    \\G    always    \eG    always
1362    .\" JOIN
1363    .*    if PCRE_DOTALL is set and there are no back    .*    if PCRE_DOTALL is set and there are no back
1364            references to the subpattern in which .* appears            references to the subpattern in which .* appears
1365    .sp
1366  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
1367  \fBpcre_fullinfo()\fR.  \fBpcre_fullinfo()\fP.
1368    .sp
1369    PCRE_INFO_SIZE    PCRE_INFO_SIZE
1370    .sp
1371  Return the size of the compiled pattern, that is, the value that was passed as  Return the size of the compiled pattern in bytes (for both libraries). The
1372  the argument to \fBpcre_malloc()\fR when PCRE was getting memory in which to  fourth argument should point to a \fBsize_t\fP variable. This value does not
1373  place the compiled data. The fourth argument should point to a \fBsize_t\fR  include the size of the \fBpcre\fP structure that is returned by
1374  variable.  \fBpcre_compile()\fP. The value that is passed as the argument to
1375    \fBpcre_malloc()\fP when \fBpcre_compile()\fP is getting memory in which to
1376    place the compiled data is the value returned by this option plus the size of
1377    the \fBpcre\fP structure. Studying a compiled pattern, with or without JIT,
1378    does not alter the value returned by this option.
1379    .sp
1380    PCRE_INFO_STUDYSIZE    PCRE_INFO_STUDYSIZE
1381    .sp
1382  Returns the size of the data block pointed to by the \fIstudy_data\fR field in  Return the size in bytes of the data block pointed to by the \fIstudy_data\fP
1383  a \fBpcre_extra\fR block. That is, it is the value that was passed to  field in a \fBpcre_extra\fP block. If \fBpcre_extra\fP is NULL, or there is no
1384  \fBpcre_malloc()\fR when PCRE was getting memory into which to place the data  study data, zero is returned. The fourth argument should point to a
1385  created by \fBpcre_study()\fR. The fourth argument should point to a  \fBsize_t\fP variable. The \fIstudy_data\fP field is set by \fBpcre_study()\fP
1386  \fBsize_t\fR variable.  to record information that will speed up matching (see the section entitled
1387    .\" HTML <a href="#studyingapattern">
1388  .SH OBSOLETE INFO FUNCTION  .\" </a>
1389  .rs  "Studying a pattern"
1390  .sp  .\"
1391  .B int pcre_info(const pcre *\fIcode\fR, int *\fIoptptr\fR, int  above). The format of the \fIstudy_data\fP block is private, but its length
1392  .B *\fIfirstcharptr\fR);  is made available via this option so that it can be saved and restored (see the
1393  .PP  .\" HREF
1394  The \fBpcre_info()\fR function is now obsolete because its interface is too  \fBpcreprecompile\fP
1395  restrictive to return all the available data about a compiled pattern. New  .\"
1396  programs should use \fBpcre_fullinfo()\fR instead. The yield of  documentation for details).
1397  \fBpcre_info()\fR is the number of capturing subpatterns, or one of the  .
1398  following negative numbers:  .
1399    .SH "REFERENCE COUNTS"
1400    PCRE_ERROR_NULL       the argument \fIcode\fR was NULL  .rs
1401    PCRE_ERROR_BADMAGIC   the "magic number" was not found  .sp
1402    .B int pcre_refcount(pcre *\fIcode\fP, int \fIadjust\fP);
1403  If the \fIoptptr\fR argument is not NULL, a copy of the options with which the  .PP
1404  pattern was compiled is placed in the integer it points to (see  The \fBpcre_refcount()\fP function is used to maintain a reference count in the
1405  PCRE_INFO_OPTIONS above).  data block that contains a compiled pattern. It is provided for the benefit of
1406    applications that operate in an object-oriented manner, where different parts
1407  If the pattern is not anchored and the \fIfirstcharptr\fR argument is not NULL,  of the application may be using the same compiled pattern, but you want to free
1408  it is used to pass back information about the first character of any matched  the block when they are all done.
1409  string (see PCRE_INFO_FIRSTBYTE above).  .P
1410    When a pattern is compiled, the reference count field is initialized to zero.
1411  .SH MATCHING A PATTERN  It is changed only by calling this function, whose action is to add the
1412  .rs  \fIadjust\fP value (which may be positive or negative) to it. The yield of the
1413  .sp  function is the new value. However, the value of the count is constrained to
1414  .B int pcre_exec(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"  lie between 0 and 65535, inclusive. If the new value is outside these limits,
1415  .ti +5n  it is forced to the appropriate limit value.
1416  .B "const char *\fIsubject\fR," int \fIlength\fR, int \fIstartoffset\fR,  .P
1417  .ti +5n  Except when it is zero, the reference count is not correctly preserved if a
1418  .B int \fIoptions\fR, int *\fIovector\fR, int \fIovecsize\fR);  pattern is compiled on one host and then transferred to a host whose byte-order
1419  .PP  is different. (This seems a highly unlikely scenario.)
1420  The function \fBpcre_exec()\fR is called to match a subject string against a  .
1421  pre-compiled pattern, which is passed in the \fIcode\fR argument. If the  .
1422  pattern has been studied, the result of the study should be passed in the  .SH "MATCHING A PATTERN: THE TRADITIONAL FUNCTION"
1423  \fIextra\fR argument.  .rs
1424    .sp
1425  Here is an example of a simple call to \fBpcre_exec()\fR:  .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
1426    .ti +5n
1427    .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
1428    .ti +5n
1429    .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
1430    .P
1431    The function \fBpcre_exec()\fP is called to match a subject string against a
1432    compiled pattern, which is passed in the \fIcode\fP argument. If the
1433    pattern was studied, the result of the study should be passed in the
1434    \fIextra\fP argument. You can call \fBpcre_exec()\fP with the same \fIcode\fP
1435    and \fIextra\fP arguments as many times as you like, in order to match
1436    different subject strings with the same pattern.
1437    .P
1438    This function is the main matching facility of the library, and it operates in
1439    a Perl-like manner. For specialist use there is also an alternative matching
1440    function, which is described
1441    .\" HTML <a href="#dfamatch">
1442    .\" </a>
1443    below
1444    .\"
1445    in the section about the \fBpcre_dfa_exec()\fP function.
1446    .P
1447    In most applications, the pattern will have been compiled (and optionally
1448    studied) in the same process that calls \fBpcre_exec()\fP. However, it is
1449    possible to save compiled patterns and study data, and then use them later
1450    in different processes, possibly even on different hosts. For a discussion
1451    about this, see the
1452    .\" HREF
1453    \fBpcreprecompile\fP
1454    .\"
1455    documentation.
1456    .P
1457    Here is an example of a simple call to \fBpcre_exec()\fP:
1458    .sp
1459    int rc;    int rc;
1460    int ovector[30];    int ovector[30];
1461    rc = pcre_exec(    rc = pcre_exec(
# Line 645  Here is an example of a simple call to \ Line 1465  Here is an example of a simple call to \
1465      11,             /* the length of the subject string */      11,             /* the length of the subject string */
1466      0,              /* start at offset 0 in the subject */      0,              /* start at offset 0 in the subject */
1467      0,              /* default options */      0,              /* default options */
1468      ovector,        /* vector for substring information */      ovector,        /* vector of integers for substring information */
1469      30);            /* number of elements in the vector */      30);            /* number of elements (NOT size in bytes) */
1470    .
1471  If the \fIextra\fR argument is not NULL, it must point to a \fBpcre_extra\fR  .
1472  data block. The \fBpcre_study()\fR function returns such a block (when it  .\" HTML <a name="extradata"></a>
1473    .SS "Extra data for \fBpcre_exec()\fR"
1474    .rs
1475    .sp
1476    If the \fIextra\fP argument is not NULL, it must point to a \fBpcre_extra\fP
1477    data block. The \fBpcre_study()\fP function returns such a block (when it
1478  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
1479  additional information in it. The fields in the block are as follows:  additional information in it. The \fBpcre_extra\fP block contains the following
1480    fields (not necessarily in this order):
1481    unsigned long int \fIflags\fR;  .sp
1482    void *\fIstudy_data\fR;    unsigned long int \fIflags\fP;
1483    unsigned long int \fImatch_limit\fR;    void *\fIstudy_data\fP;
1484    void *\fIcallout_data\fR;    void *\fIexecutable_jit\fP;
1485      unsigned long int \fImatch_limit\fP;
1486  The \fIflags\fR field is a bitmap that specifies which of the other fields    unsigned long int \fImatch_limit_recursion\fP;
1487  are set. The flag bits are:    void *\fIcallout_data\fP;
1488      const unsigned char *\fItables\fP;
1489    PCRE_EXTRA_STUDY_DATA    unsigned char **\fImark\fP;
1490    PCRE_EXTRA_MATCH_LIMIT  .sp
1491    In the 16-bit version of this structure, the \fImark\fP field has type
1492    "PCRE_UCHAR16 **".
1493    .P
1494    The \fIflags\fP field is used to specify which of the other fields are set. The
1495    flag bits are:
1496    .sp
1497    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1498      PCRE_EXTRA_EXECUTABLE_JIT
1499  Other flag bits should be set to zero. The \fIstudy_data\fR field is set in the    PCRE_EXTRA_MARK
1500  \fBpcre_extra\fR block that is returned by \fBpcre_study()\fR, together with    PCRE_EXTRA_MATCH_LIMIT
1501  the appropriate flag bit. You should not set this yourself, but you can add to    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1502  the block by setting the other fields.    PCRE_EXTRA_STUDY_DATA
1503      PCRE_EXTRA_TABLES
1504  The \fImatch_limit\fR field provides a means of preventing PCRE from using up a  .sp
1505    Other flag bits should be set to zero. The \fIstudy_data\fP field and sometimes
1506    the \fIexecutable_jit\fP field are set in the \fBpcre_extra\fP block that is
1507    returned by \fBpcre_study()\fP, together with the appropriate flag bits. You
1508    should not set these yourself, but you may add to the block by setting other
1509    fields and their corresponding flag bits.
1510    .P
1511    The \fImatch_limit\fP field provides a means of preventing PCRE from using up a
1512  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,
1513  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
1514  classic example is the use of nested unlimited repeats. Internally, PCRE uses a  classic example is a pattern that uses nested unlimited repeats.
1515  function called \fBmatch()\fR which it calls repeatedly (sometimes  .P
1516  recursively). The limit is imposed on the number of times this function is  Internally, \fBpcre_exec()\fP uses a function called \fBmatch()\fP, which it
1517  called during a match, which has the effect of limiting the amount of recursion  calls repeatedly (sometimes recursively). The limit set by \fImatch_limit\fP is
1518  and backtracking that can take place. For patterns that are not anchored, the  imposed on the number of times this function is called during a match, which
1519  count starts from zero for each position in the subject string.  has the effect of limiting the amount of backtracking that can take place. For
1520    patterns that are not anchored, the count restarts from zero for each position
1521  The default limit for the library can be set when PCRE is built; the default  in the subject string.
1522    .P
1523    When \fBpcre_exec()\fP is called with a pattern that was successfully studied
1524    with a JIT option, the way that the matching is executed is entirely different.
1525    However, there is still the possibility of runaway matching that goes on for a
1526    very long time, and so the \fImatch_limit\fP value is also used in this case
1527    (but in a different way) to limit how long the matching can continue.
1528    .P
1529    The default value for the limit can be set when PCRE is built; the default
1530  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
1531  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
1532  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
1533  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
1534  exceeded, \fBpcre_exec()\fR returns PCRE_ERROR_MATCHLIMIT.  PCRE_ERROR_MATCHLIMIT.
1535    .P
1536  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
1537  which is described in the \fBpcrecallout\fR documentation.  instead of limiting the total number of times that \fBmatch()\fP is called, it
1538    limits the depth of recursion. The recursion depth is a smaller number than the
1539  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.
1540  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.
1541  first matching position. However, if a pattern was compiled with PCRE_ANCHORED,  .P
1542  or turned out to be anchored by virtue of its contents, it cannot be made  Limiting the recursion depth limits the amount of machine stack that can be
1543  unachored at matching time.  used, or, when PCRE has been compiled to use memory on the heap instead of the
1544    stack, the amount of heap memory that can be used. This limit is not relevant,
1545  There are also three further options that can be set only at matching time:  and is ignored, when matching is done using JIT compiled code.
1546    .P
1547    The default value for \fImatch_limit_recursion\fP can be set when PCRE is
1548    built; the default default is the same value as the default for
1549    \fImatch_limit\fP. You can override the default by suppling \fBpcre_exec()\fP
1550    with a \fBpcre_extra\fP block in which \fImatch_limit_recursion\fP is set, and
1551    PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the \fIflags\fP field. If the limit
1552    is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1553    .P
1554    The \fIcallout_data\fP field is used in conjunction with the "callout" feature,
1555    and is described in the
1556    .\" HREF
1557    \fBpcrecallout\fP
1558    .\"
1559    documentation.
1560    .P
1561    The \fItables\fP field is used to pass a character tables pointer to
1562    \fBpcre_exec()\fP; this overrides the value that is stored with the compiled
1563    pattern. A non-NULL value is stored with the compiled pattern only if custom
1564    tables were supplied to \fBpcre_compile()\fP via its \fItableptr\fP argument.
1565    If NULL is passed to \fBpcre_exec()\fP using this mechanism, it forces PCRE's
1566    internal tables to be used. This facility is helpful when re-using patterns
1567    that have been saved after compiling with an external set of tables, because
1568    the external tables might be at a different address when \fBpcre_exec()\fP is
1569    called. See the
1570    .\" HREF
1571    \fBpcreprecompile\fP
1572    .\"
1573    documentation for a discussion of saving compiled patterns for later use.
1574    .P
1575    If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1576    be set to point to a suitable variable. If the pattern contains any
1577    backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1578    a name to pass back, a pointer to the name string (zero terminated) is placed
1579    in the variable pointed to by the \fImark\fP field. The names are within the
1580    compiled pattern; if you wish to retain such a name you must copy it before
1581    freeing the memory of a compiled pattern. If there is no name to pass back, the
1582    variable pointed to by the \fImark\fP field is set to NULL. For details of the
1583    backtracking control verbs, see the section entitled
1584    .\" HTML <a href="pcrepattern#backtrackcontrol">
1585    .\" </a>
1586    "Backtracking control"
1587    .\"
1588    in the
1589    .\" HREF
1590    \fBpcrepattern\fP
1591    .\"
1592    documentation.
1593    .
1594    .
1595    .\" HTML <a name="execoptions"></a>
1596    .SS "Option bits for \fBpcre_exec()\fP"
1597    .rs
1598    .sp
1599    The unused bits of the \fIoptions\fP argument for \fBpcre_exec()\fP must be
1600    zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
1601    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1602    PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD, and
1603    PCRE_PARTIAL_SOFT.
1604    .P
1605    If the pattern was successfully studied with one of the just-in-time (JIT)
1606    compile options, the only supported options for JIT execution are
1607    PCRE_NO_UTF8_CHECK, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY,
1608    PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an
1609    unsupported option is used, JIT execution is disabled and the normal
1610    interpretive code in \fBpcre_exec()\fP is run.
1611    .sp
1612      PCRE_ANCHORED
1613    .sp
1614    The PCRE_ANCHORED option limits \fBpcre_exec()\fP to matching at the first
1615    matching position. If a pattern was compiled with PCRE_ANCHORED, or turned out
1616    to be anchored by virtue of its contents, it cannot be made unachored at
1617    matching time.
1618    .sp
1619      PCRE_BSR_ANYCRLF
1620      PCRE_BSR_UNICODE
1621    .sp
1622    These options (which are mutually exclusive) control what the \eR escape
1623    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
1624    match any Unicode newline sequence. These options override the choice that was
1625    made or defaulted when the pattern was compiled.
1626    .sp
1627      PCRE_NEWLINE_CR
1628      PCRE_NEWLINE_LF
1629      PCRE_NEWLINE_CRLF
1630      PCRE_NEWLINE_ANYCRLF
1631      PCRE_NEWLINE_ANY
1632    .sp
1633    These options override the newline definition that was chosen or defaulted when
1634    the pattern was compiled. For details, see the description of
1635    \fBpcre_compile()\fP above. During matching, the newline choice affects the
1636    behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1637    the way the match position is advanced after a match failure for an unanchored
1638    pattern.
1639    .P
1640    When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a
1641    match attempt for an unanchored pattern fails when the current position is at a
1642    CRLF sequence, and the pattern contains no explicit matches for CR or LF
1643    characters, the match position is advanced by two characters instead of one, in
1644    other words, to after the CRLF.
1645    .P
1646    The above rule is a compromise that makes the most common cases work as
1647    expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
1648    set), it does not match the string "\er\enA" because, after failing at the
1649    start, it skips both the CR and the LF before retrying. However, the pattern
1650    [\er\en]A does match that string, because it contains an explicit CR or LF
1651    reference, and so advances only by one character after the first failure.
1652    .P
1653    An explicit match for CR of LF is either a literal appearance of one of those
1654    characters, or one of the \er or \en escape sequences. Implicit matches such as
1655    [^X] do not count, nor does \es (which includes CR and LF in the characters
1656    that it matches).
1657    .P
1658    Notwithstanding the above, anomalous effects may still occur when CRLF is a
1659    valid newline sequence and explicit \er or \en escapes appear in the pattern.
1660    .sp
1661    PCRE_NOTBOL    PCRE_NOTBOL
1662    .sp
1663  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
1664  circumflex metacharacter should not match before it. Setting this without  beginning of a line, so the circumflex metacharacter should not match before
1665  PCRE_MULTILINE (at compile time) causes circumflex never to match.  it. Setting this without PCRE_MULTILINE (at compile time) causes circumflex
1666    never to match. This option affects only the behaviour of the circumflex
1667    metacharacter. It does not affect \eA.
1668    .sp
1669    PCRE_NOTEOL    PCRE_NOTEOL
1670    .sp
1671  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
1672  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
1673  it. Setting this without PCRE_MULTILINE (at compile time) causes dollar never  mode) a newline immediately before it. Setting this without PCRE_MULTILINE (at
1674  to match.  compile time) causes dollar never to match. This option affects only the
1675    behaviour of the dollar metacharacter. It does not affect \eZ or \ez.
1676    .sp
1677    PCRE_NOTEMPTY    PCRE_NOTEMPTY
1678    .sp
1679  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
1680  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
1681  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
1682    .sp
1683    a?b?    a?b?
1684    .sp
1685  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
1686  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
1687  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".
1688    .sp
1689  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case    PCRE_NOTEMPTY_ATSTART
1690  of a pattern match of the empty string within its \fBsplit()\fR function, and  .sp
1691  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
1692  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
1693  PCRE_NOTEMPTY set, and then if that fails by advancing the starting offset (see  can occur only if the pattern contains \eK.
1694  below) and trying an ordinary match again.  .P
1695    Perl has no direct equivalent of PCRE_NOTEMPTY or PCRE_NOTEMPTY_ATSTART, but it
1696  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
1697  \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
1698  \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
1699  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
1700  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
1701    ordinary match again. There is some code that demonstrates how to do this in
1702  If the pattern was compiled with the PCRE_UTF8 option, the subject must be a  the
1703  sequence of bytes that is a valid UTF-8 string. If an invalid UTF-8 string is  .\" HREF
1704  passed, PCRE's behaviour is not defined.  \fBpcredemo\fP
1705    .\"
1706    sample program. In the most general case, you have to check to see if the
1707    newline convention recognizes CRLF as a newline, and if so, and the current
1708    character is CR followed by LF, advance the starting offset by two characters
1709    instead of one.
1710    .sp
1711      PCRE_NO_START_OPTIMIZE
1712    .sp
1713    There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1714    a match, in order to speed up the process. For example, if it is known that an
1715    unanchored match must start with a specific character, it searches the subject
1716    for that character, and fails immediately if it cannot find it, without
1717    actually running the main matching function. This means that a special item
1718    such as (*COMMIT) at the start of a pattern is not considered until after a
1719    suitable starting point for the match has been found. When callouts or (*MARK)
1720    items are in use, these "start-up" optimizations can cause them to be skipped
1721    if the pattern is never actually used. The start-up optimizations are in effect
1722    a pre-scan of the subject that takes place before the pattern is run.
1723    .P
1724    The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
1725    causing performance to suffer, but ensuring that in cases where the result is
1726    "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
1727    are considered at every possible starting position in the subject string. If
1728    PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
1729    time. The use of PCRE_NO_START_OPTIMIZE disables JIT execution; when it is set,
1730    matching is always done using interpretively.
1731    .P
1732    Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
1733    Consider the pattern
1734    .sp
1735      (*COMMIT)ABC
1736    .sp
1737    When this is compiled, PCRE records the fact that a match must start with the
1738    character "A". Suppose the subject string is "DEFABC". The start-up
1739    optimization scans along the subject, finds "A" and runs the first match
1740    attempt from there. The (*COMMIT) item means that the pattern must match the
1741    current starting position, which in this case, it does. However, if the same
1742    match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
1743    subject string does not happen. The first match attempt is run starting from
1744    "D" and when this fails, (*COMMIT) prevents any further matches being tried, so
1745    the overall result is "no match". If the pattern is studied, more start-up
1746    optimizations may be used. For example, a minimum length for the subject may be
1747    recorded. Consider the pattern
1748    .sp
1749      (*MARK:A)(X|Y)
1750    .sp
1751    The minimum length for a match is one character. If the subject is "ABC", there
1752    will be attempts to match "ABC", "BC", "C", and then finally an empty string.
1753    If the pattern is studied, the final attempt does not take place, because PCRE
1754    knows that the subject is too short, and so the (*MARK) is never encountered.
1755    In this case, studying the pattern does not affect the overall match result,
1756    which is still "no match", but it does affect the auxiliary information that is
1757    returned.
1758    .sp
1759      PCRE_NO_UTF8_CHECK
1760    .sp
1761    When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8
1762    string is automatically checked when \fBpcre_exec()\fP is subsequently called.
1763    The entire string is checked before any other processing takes place. The value
1764    of \fIstartoffset\fP is also checked to ensure that it points to the start of a
1765    UTF-8 character. There is a discussion about the
1766    .\" HTML <a href="pcreunicode.html#utf8strings">
1767    .\" </a>
1768    validity of UTF-8 strings
1769    .\"
1770    in the
1771    .\" HREF
1772    \fBpcreunicode\fP
1773    .\"
1774    page. If an invalid sequence of bytes is found, \fBpcre_exec()\fP returns the
1775    error PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a
1776    truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In both
1777    cases, information about the precise nature of the error may also be returned
1778    (see the descriptions of these errors in the section entitled \fIError return
1779    values from\fP \fBpcre_exec()\fP
1780    .\" HTML <a href="#errorlist">
1781    .\" </a>
1782    below).
1783    .\"
1784    If \fIstartoffset\fP contains a value that does not point to the start of a
1785    UTF-8 character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
1786    returned.
1787    .P
1788    If you already know that your subject is valid, and you want to skip these
1789    checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when
1790    calling \fBpcre_exec()\fP. You might want to do this for the second and
1791    subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find
1792    all the matches in a single subject string. However, you should be sure that
1793    the value of \fIstartoffset\fP points to the start of a character (or the end
1794    of the subject). When PCRE_NO_UTF8_CHECK is set, the effect of passing an
1795    invalid string as a subject or an invalid value of \fIstartoffset\fP is
1796    undefined. Your program may crash.
1797    .sp
1798      PCRE_PARTIAL_HARD
1799      PCRE_PARTIAL_SOFT
1800    .sp
1801    These options turn on the partial matching feature. For backwards
1802    compatibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial match
1803    occurs if the end of the subject string is reached successfully, but there are
1804    not enough subject characters to complete the match. If this happens when
1805    PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set, matching continues by
1806    testing any remaining alternatives. Only if no complete match can be found is
1807    PCRE_ERROR_PARTIAL returned instead of PCRE_ERROR_NOMATCH. In other words,
1808    PCRE_PARTIAL_SOFT says that the caller is prepared to handle a partial match,
1809    but only if no complete match can be found.
1810    .P
1811    If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
1812    partial match is found, \fBpcre_exec()\fP immediately returns
1813    PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
1814    when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
1815    important that an alternative complete match.
1816    .P
1817    In both cases, the portion of the string that was inspected when the partial
1818    match was found is set as the first matching string. There is a more detailed
1819    discussion of partial and multi-segment matching, with examples, in the
1820    .\" HREF
1821    \fBpcrepartial\fP
1822    .\"
1823    documentation.
1824    .
1825    .
1826    .SS "The string to be matched by \fBpcre_exec()\fP"
1827    .rs
1828    .sp
1829    The subject string is passed to \fBpcre_exec()\fP as a pointer in
1830    \fIsubject\fP, a length in bytes in \fIlength\fP, and a starting byte offset
1831    in \fIstartoffset\fP. If this is negative or greater than the length of the
1832    subject, \fBpcre_exec()\fP returns PCRE_ERROR_BADOFFSET. When the starting
1833    offset is zero, the search for a match starts at the beginning of the subject,
1834    and this is by far the most common case. In UTF-8 mode, the byte offset must
1835    point to the start of a UTF-8 character (or the end of the subject). Unlike the
1836    pattern string, the subject may contain binary zero bytes.
1837    .P
1838  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
1839  same subject by calling \fBpcre_exec()\fR again after a previous success.  same subject by calling \fBpcre_exec()\fP again after a previous success.
1840  Setting \fIstartoffset\fR differs from just passing over a shortened string and  Setting \fIstartoffset\fP differs from just passing over a shortened string and
1841  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
1842  lookbehind. For example, consider the pattern  lookbehind. For example, consider the pattern
1843    .sp
1844    \\Biss\\B    \eBiss\eB
1845    .sp
1846  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
1847  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
1848  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
1849  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
1850  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
1851  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
1852  \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
1853  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
1854  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.
1855    .P
1856    Finding all the matches in a subject is tricky when the pattern can match an
1857    empty string. It is possible to emulate Perl's /g behaviour by first trying the
1858    match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
1859    PCRE_ANCHORED options, and then if that fails, advancing the starting offset
1860    and trying an ordinary match again. There is some code that demonstrates how to
1861    do this in the
1862    .\" HREF
1863    \fBpcredemo\fP
1864    .\"
1865    sample program. In the most general case, you have to check to see if the
1866    newline convention recognizes CRLF as a newline, and if so, and the current
1867    character is CR followed by LF, advance the starting offset by two characters
1868    instead of one.
1869    .P
1870  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
1871  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
1872  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.
1873    .
1874    .
1875    .SS "How \fBpcre_exec()\fP returns captured substrings"
1876    .rs
1877    .sp
1878  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
1879  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
1880  pattern. Following the usage in Jeffrey Friedl's book, this is called  pattern. Following the usage in Jeffrey Friedl's book, this is called
1881  "capturing" in what follows, and the phrase "capturing subpattern" is used for  "capturing" in what follows, and the phrase "capturing subpattern" is used for
1882  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
1883  kinds of parenthesized subpattern that do not cause substrings to be captured.  kinds of parenthesized subpattern that do not cause substrings to be captured.
1884    .P
1885  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
1886  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
1887  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
1888  back captured substrings, each substring using a pair of integers. The  argument is NOT the size of \fIovector\fP in bytes.
1889  remaining third of the vector is used as workspace by \fBpcre_exec()\fR while  .P
1890  matching capturing subpatterns, and is not available for passing back  The first two-thirds of the vector is used to pass back captured substrings,
1891  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
1892  three. If it is not, it is rounded down.  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
1893    and is not available for passing back information. The number passed in
1894  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
1895  returned in pairs of integers, starting at the beginning of \fIovector\fR, and  rounded down.
1896  continuing up to two-thirds of its length at the most. The first element of a  .P
1897  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
1898  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
1899  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
1900  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
1901  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
1902  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
1903  subpatterns, the return value from a successful match is 1, indicating that  mode. They are not character counts.
1904  just the first pair of offsets has been set.  .P
1905    The first pair of integers, \fIovector[0]\fP and \fIovector[1]\fP, identify the
1906  Some convenience functions are provided for extracting the captured substrings  portion of the subject string matched by the entire pattern. The next pair is
1907  as separate strings. These are described in the following section.  used for the first capturing subpattern, and so on. The value returned by
1908    \fBpcre_exec()\fP is one more than the highest numbered pair that has been set.
1909  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
1910  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
1911  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.
1912  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.  
   
1913  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
1914  string that it matched that gets returned.  string that it matched that is returned.
1915    .P
1916  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
1917  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
1918  value of zero. In particular, if the substring offsets are not of interest,  returns a value of zero. If neither the actual string matched nor any captured
1919  \fBpcre_exec()\fR may be called with \fIovector\fR passed as NULL and  substrings are of interest, \fBpcre_exec()\fP may be called with \fIovector\fP
1920  \fIovecsize\fR as zero. However, if the pattern contains back references and  passed as NULL and \fIovecsize\fP as zero. However, if the pattern contains
1921  the \fIovector\fR isn't big enough to remember the related substrings, PCRE has  back references and the \fIovector\fP is not big enough to remember the related
1922  to get additional memory for use during matching. Thus it is usually advisable  substrings, PCRE has to get additional memory for use during matching. Thus it
1923  to supply an \fIovector\fR.  is usually advisable to supply an \fIovector\fP of reasonable size.
1924    .P
1925  Note that \fBpcre_info()\fR can be used to find out how many capturing  There are some cases where zero is returned (indicating vector overflow) when
1926    in fact the vector is exactly the right size for the final match. For example,
1927    consider the pattern
1928    .sp
1929      (a)(?:(b)c|bd)
1930    .sp
1931    If a vector of 6 elements (allowing for only 1 captured substring) is given
1932    with subject string "abd", \fBpcre_exec()\fP will try to set the second
1933    captured string, thereby recording a vector overflow, before failing to match
1934    "c" and backing up to try the second alternative. The zero return, however,
1935    does correctly indicate that the maximum number of slots (namely 2) have been
1936    filled. In similar cases where there is temporary overflow, but the final
1937    number of used slots is actually less than the maximum, a non-zero value is
1938    returned.
1939    .P
1940    The \fBpcre_fullinfo()\fP function can be used to find out how many capturing
1941  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1942  \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
1943  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.
1944    .P
1945  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
1946    the subject when subpattern \fIn\fP has not been used at all. For example, if
1947    the string "abc" is matched against the pattern (a|(z))(bc) the return from the
1948    function is 4, and subpatterns 1 and 3 are matched, but 2 is not. When this
1949    happens, both values in the offset pairs corresponding to unused subpatterns
1950    are set to -1.
1951    .P
1952    Offset values that correspond to unused subpatterns at the end of the
1953    expression are also set to -1. For example, if the string "abc" is matched
1954    against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
1955    return from the function is 2, because the highest used capturing subpattern
1956    number is 1, and the offsets for for the second and third capturing subpatterns
1957    (assuming the vector is large enough, of course) are set to -1.
1958    .P
1959    \fBNote\fP: Elements in the first two-thirds of \fIovector\fP that do not
1960    correspond to capturing parentheses in the pattern are never changed. That is,
1961    if a pattern contains \fIn\fP capturing parentheses, no more than
1962    \fIovector[0]\fP to \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other
1963    elements (in the first two-thirds) retain whatever values they previously had.
1964    .P
1965    Some convenience functions are provided for extracting the captured substrings
1966    as separate strings. These are described below.
1967    .
1968    .
1969    .\" HTML <a name="errorlist"></a>
1970    .SS "Error return values from \fBpcre_exec()\fP"
1971    .rs
1972    .sp
1973    If \fBpcre_exec()\fP fails, it returns a negative number. The following are
1974  defined in the header file:  defined in the header file:
1975    .sp
1976    PCRE_ERROR_NOMATCH        (-1)    PCRE_ERROR_NOMATCH        (-1)
1977    .sp
1978  The subject string did not match the pattern.  The subject string did not match the pattern.
1979    .sp
1980    PCRE_ERROR_NULL           (-2)    PCRE_ERROR_NULL           (-2)
1981    .sp
1982  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
1983  NULL and \fIovecsize\fR was not zero.  NULL and \fIovecsize\fP was not zero.
1984    .sp
1985    PCRE_ERROR_BADOPTION      (-3)    PCRE_ERROR_BADOPTION      (-3)
1986    .sp
1987  An unrecognized bit was set in the \fIoptions\fR argument.  An unrecognized bit was set in the \fIoptions\fP argument.
1988    .sp
1989    PCRE_ERROR_BADMAGIC       (-4)    PCRE_ERROR_BADMAGIC       (-4)
1990    .sp
1991  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
1992  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
1993  magic number isn't present.  compiled in an environment of one endianness is run in an environment with the
1994    other endianness. This is the error that PCRE gives when the magic number is
1995    PCRE_ERROR_UNKNOWN_NODE   (-5)  not present.
1996    .sp
1997      PCRE_ERROR_UNKNOWN_OPCODE (-5)
1998    .sp
1999  While running the pattern match, an unknown item was encountered in the  While running the pattern match, an unknown item was encountered in the
2000  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
2001  of the compiled pattern.  of the compiled pattern.
2002    .sp
2003    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
2004    .sp
2005  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
2006  \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
2007  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
2008  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
2009  the end of matching.  automatically freed at the end of matching.
2010    .P
2011    This error is also given if \fBpcre_stack_malloc()\fP fails in
2012    \fBpcre_exec()\fP. This can happen only when PCRE has been compiled with
2013    \fB--disable-stack-for-recursion\fP.
2014    .sp
2015    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
2016    .sp
2017  This error is used by the \fBpcre_copy_substring()\fR,  This error is used by the \fBpcre_copy_substring()\fP,
2018  \fBpcre_get_substring()\fR, and \fBpcre_get_substring_list()\fR functions (see  \fBpcre_get_substring()\fP, and \fBpcre_get_substring_list()\fP functions (see
2019  below). It is never returned by \fBpcre_exec()\fR.  below). It is never returned by \fBpcre_exec()\fP.
2020    .sp
2021    PCRE_ERROR_MATCHLIMIT     (-8)    PCRE_ERROR_MATCHLIMIT     (-8)
2022    .sp
2023  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
2024  field in a \fBpcre_extra\fR structure (or defaulted) was reached. See the  \fBpcre_extra\fP structure (or defaulted) was reached. See the description
2025  description above.  above.
2026    .sp
2027    PCRE_ERROR_CALLOUT        (-9)    PCRE_ERROR_CALLOUT        (-9)
2028    .sp
2029  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
2030  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
2031  \fBpcrecallout\fR documentation for details.  .\" HREF
2032    \fBpcrecallout\fP
2033  .SH EXTRACTING CAPTURED SUBSTRINGS BY NUMBER  .\"
2034    documentation for details.
2035    .sp
2036      PCRE_ERROR_BADUTF8        (-10)
2037    .sp
2038    A string that contains an invalid UTF-8 byte sequence was passed as a subject,
2039    and the PCRE_NO_UTF8_CHECK option was not set. If the size of the output vector
2040    (\fIovecsize\fP) is at least 2, the byte offset to the start of the the invalid
2041    UTF-8 character is placed in the first element, and a reason code is placed in
2042    the second element. The reason codes are listed in the
2043    .\" HTML <a href="#badutf8reasons">
2044    .\" </a>
2045    following section.
2046    .\"
2047    For backward compatibility, if PCRE_PARTIAL_HARD is set and the problem is a
2048    truncated UTF-8 character at the end of the subject (reason codes 1 to 5),
2049    PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
2050    .sp
2051      PCRE_ERROR_BADUTF8_OFFSET (-11)
2052    .sp
2053    The UTF-8 byte sequence that was passed as a subject was checked and found to
2054    be valid (the PCRE_NO_UTF8_CHECK option was not set), but the value of
2055    \fIstartoffset\fP did not point to the beginning of a UTF-8 character or the
2056    end of the subject.
2057    .sp
2058      PCRE_ERROR_PARTIAL        (-12)
2059    .sp
2060    The subject string did not match, but it did match partially. See the
2061    .\" HREF
2062    \fBpcrepartial\fP
2063    .\"
2064    documentation for details of partial matching.
2065    .sp
2066      PCRE_ERROR_BADPARTIAL     (-13)
2067    .sp
2068    This code is no longer in use. It was formerly returned when the PCRE_PARTIAL
2069    option was used with a compiled pattern containing items that were not
2070    supported for partial matching. From release 8.00 onwards, there are no
2071    restrictions on partial matching.
2072    .sp
2073      PCRE_ERROR_INTERNAL       (-14)
2074    .sp
2075    An unexpected internal error has occurred. This error could be caused by a bug
2076    in PCRE or by overwriting of the compiled pattern.
2077    .sp
2078      PCRE_ERROR_BADCOUNT       (-15)
2079    .sp
2080    This error is given if the value of the \fIovecsize\fP argument is negative.
2081    .sp
2082      PCRE_ERROR_RECURSIONLIMIT (-21)
2083    .sp
2084    The internal recursion limit, as specified by the \fImatch_limit_recursion\fP
2085    field in a \fBpcre_extra\fP structure (or defaulted) was reached. See the
2086    description above.
2087    .sp
2088      PCRE_ERROR_BADNEWLINE     (-23)
2089    .sp
2090    An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
2091    .sp
2092      PCRE_ERROR_BADOFFSET      (-24)
2093    .sp
2094    The value of \fIstartoffset\fP was negative or greater than the length of the
2095    subject, that is, the value in \fIlength\fP.
2096    .sp
2097      PCRE_ERROR_SHORTUTF8      (-25)
2098    .sp
2099    This error is returned instead of PCRE_ERROR_BADUTF8 when the subject string
2100    ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD option is set.
2101    Information about the failure is returned as for PCRE_ERROR_BADUTF8. It is in
2102    fact sufficient to detect this case, but this special error code for
2103    PCRE_PARTIAL_HARD precedes the implementation of returned information; it is
2104    retained for backwards compatibility.
2105    .sp
2106      PCRE_ERROR_RECURSELOOP    (-26)
2107    .sp
2108    This error is returned when \fBpcre_exec()\fP detects a recursion loop within
2109    the pattern. Specifically, it means that either the whole pattern or a
2110    subpattern has been called recursively for the second time at the same position
2111    in the subject string. Some simple patterns that might do this are detected and
2112    faulted at compile time, but more complicated cases, in particular mutual
2113    recursions between two different subpatterns, cannot be detected until run
2114    time.
2115    .sp
2116      PCRE_ERROR_JIT_STACKLIMIT (-27)
2117    .sp
2118    This error is returned when a pattern that was successfully studied using a
2119    JIT compile option is being matched, but the memory available for the
2120    just-in-time processing stack is not large enough. See the
2121    .\" HREF
2122    \fBpcrejit\fP
2123    .\"
2124    documentation for more details.
2125    .sp
2126      PCRE_ERROR_BADMODE        (-28)
2127    .sp
2128    This error is given if a pattern that was compiled by the 8-bit library is
2129    passed to a 16-bit library function, or vice versa.
2130    .sp
2131      PCRE_ERROR_BADENDIANNESS  (-29)
2132    .sp
2133    This error is given if a pattern that was compiled and saved is reloaded on a
2134    host with different endianness. The utility function
2135    \fBpcre_pattern_to_host_byte_order()\fP can be used to convert such a pattern
2136    so that it runs on the new host.
2137    .P
2138    Error numbers -16 to -20, -22, and -30 are not used by \fBpcre_exec()\fP.
2139    .
2140    .
2141    .\" HTML <a name="badutf8reasons"></a>
2142    .SS "Reason codes for invalid UTF-8 strings"
2143    .rs
2144    .sp
2145    This section applies only to the 8-bit library. The corresponding information
2146    for the 16-bit library is given in the
2147    .\" HREF
2148    \fBpcre16\fP
2149    .\"
2150    page.
2151    .P
2152    When \fBpcre_exec()\fP returns either PCRE_ERROR_BADUTF8 or
2153    PCRE_ERROR_SHORTUTF8, and the size of the output vector (\fIovecsize\fP) is at
2154    least 2, the offset of the start of the invalid UTF-8 character is placed in
2155    the first output vector element (\fIovector[0]\fP) and a reason code is placed
2156    in the second element (\fIovector[1]\fP). The reason codes are given names in
2157    the \fBpcre.h\fP header file:
2158    .sp
2159      PCRE_UTF8_ERR1
2160      PCRE_UTF8_ERR2
2161      PCRE_UTF8_ERR3
2162      PCRE_UTF8_ERR4
2163      PCRE_UTF8_ERR5
2164    .sp
2165    The string ends with a truncated UTF-8 character; the code specifies how many
2166    bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8 characters to be
2167    no longer than 4 bytes, the encoding scheme (originally defined by RFC 2279)
2168    allows for up to 6 bytes, and this is checked first; hence the possibility of
2169    4 or 5 missing bytes.
2170    .sp
2171      PCRE_UTF8_ERR6
2172      PCRE_UTF8_ERR7
2173      PCRE_UTF8_ERR8
2174      PCRE_UTF8_ERR9
2175      PCRE_UTF8_ERR10
2176    .sp
2177    The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of the
2178    character do not have the binary value 0b10 (that is, either the most
2179    significant bit is 0, or the next bit is 1).
2180    .sp
2181      PCRE_UTF8_ERR11
2182      PCRE_UTF8_ERR12
2183    .sp
2184    A character that is valid by the RFC 2279 rules is either 5 or 6 bytes long;
2185    these code points are excluded by RFC 3629.
2186    .sp
2187      PCRE_UTF8_ERR13
2188    .sp
2189    A 4-byte character has a value greater than 0x10fff; these code points are
2190    excluded by RFC 3629.
2191    .sp
2192      PCRE_UTF8_ERR14
2193    .sp
2194    A 3-byte character has a value in the range 0xd800 to 0xdfff; this range of
2195    code points are reserved by RFC 3629 for use with UTF-16, and so are excluded
2196    from UTF-8.
2197    .sp
2198      PCRE_UTF8_ERR15
2199      PCRE_UTF8_ERR16
2200      PCRE_UTF8_ERR17
2201      PCRE_UTF8_ERR18
2202      PCRE_UTF8_ERR19
2203    .sp
2204    A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes for a
2205    value that can be represented by fewer bytes, which is invalid. For example,
2206    the two bytes 0xc0, 0xae give the value 0x2e, whose correct coding uses just
2207    one byte.
2208    .sp
2209      PCRE_UTF8_ERR20
2210    .sp
2211    The two most significant bits of the first byte of a character have the binary
2212    value 0b10 (that is, the most significant bit is 1 and the second is 0). Such a
2213    byte can only validly occur as the second or subsequent byte of a multi-byte
2214    character.
2215    .sp
2216      PCRE_UTF8_ERR21
2217    .sp
2218    The first byte of a character has the value 0xfe or 0xff. These values can
2219    never occur in a valid UTF-8 string.
2220    .
2221    .
2222    .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
2223  .rs  .rs
2224  .sp  .sp
2225  .B int pcre_copy_substring(const char *\fIsubject\fR, int *\fIovector\fR,  .B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\fP,
2226  .ti +5n  .ti +5n
2227  .B int \fIstringcount\fR, int \fIstringnumber\fR, char *\fIbuffer\fR,  .B int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP,
2228  .ti +5n  .ti +5n
2229  .B int \fIbuffersize\fR);  .B int \fIbuffersize\fP);
2230  .PP  .PP
2231  .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,  
2232  .ti +5n  .ti +5n
2233  .B int \fIstringcount\fR, int \fIstringnumber\fR,  .B int \fIstringcount\fP, int \fIstringnumber\fP,
2234  .ti +5n  .ti +5n
2235  .B const char **\fIstringptr\fR);  .B const char **\fIstringptr\fP);
2236  .PP  .PP
2237  .br  .B int pcre_get_substring_list(const char *\fIsubject\fP,
 .B int pcre_get_substring_list(const char *\fIsubject\fR,  
2238  .ti +5n  .ti +5n
2239  .B int *\fIovector\fR, int \fIstringcount\fR, "const char ***\fIlistptr\fR);"  .B int *\fIovector\fP, int \fIstringcount\fP, "const char ***\fIlistptr\fP);"
2240  .PP  .PP
2241  Captured substrings can be accessed directly by using the offsets returned by  Captured substrings can be accessed directly by using the offsets returned by
2242  \fBpcre_exec()\fR in \fIovector\fR. For convenience, the functions  \fBpcre_exec()\fP in \fIovector\fP. For convenience, the functions
2243  \fBpcre_copy_substring()\fR, \fBpcre_get_substring()\fR, and  \fBpcre_copy_substring()\fP, \fBpcre_get_substring()\fP, and
2244  \fBpcre_get_substring_list()\fR are provided for extracting captured substrings  \fBpcre_get_substring_list()\fP are provided for extracting captured substrings
2245  as new, separate, zero-terminated strings. These functions identify substrings  as new, separate, zero-terminated strings. These functions identify substrings
2246  by number. The next section describes functions for extracting named  by number. The next section describes functions for extracting named
2247  substrings. A substring that contains a binary zero is correctly extracted and  substrings.
2248  has a further zero added on the end, but the result is not, of course,  .P
2249  a C string.  A substring that contains a binary zero is correctly extracted and has a
2250    further zero added on the end, but the result is not, of course, a C string.
2251    However, you can process such a string by referring to the length that is
2252    returned by \fBpcre_copy_substring()\fP and \fBpcre_get_substring()\fP.
2253    Unfortunately, the interface to \fBpcre_get_substring_list()\fP is not adequate
2254    for handling strings containing binary zeros, because the end of the final
2255    string is not independently indicated.
2256    .P
2257  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:
2258  \fIsubject\fR is the subject string which has just been successfully matched,  \fIsubject\fP is the subject string that has just been successfully matched,
2259  \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
2260  \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
2261  captured by the match, including the substring that matched the entire regular  captured by the match, including the substring that matched the entire regular
2262  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
2263  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
2264  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
2265  the vector divided by three.  number of elements in the vector divided by three.
2266    .P
2267  The functions \fBpcre_copy_substring()\fR and \fBpcre_get_substring()\fR  The functions \fBpcre_copy_substring()\fP and \fBpcre_get_substring()\fP
2268  extract a single substring, whose number is given as \fIstringnumber\fR. A  extract a single substring, whose number is given as \fIstringnumber\fP. A
2269  value of zero extracts the substring that matched the entire pattern, while  value of zero extracts the substring that matched the entire pattern, whereas
2270  higher values extract the captured substrings. For \fBpcre_copy_substring()\fR,  higher values extract the captured substrings. For \fBpcre_copy_substring()\fP,
2271  the string is placed in \fIbuffer\fR, whose length is given by  the string is placed in \fIbuffer\fP, whose length is given by
2272  \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
2273  obtained via \fBpcre_malloc\fR, and its address is returned via  obtained via \fBpcre_malloc\fP, and its address is returned via
2274  \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
2275  including the terminating zero, or one of  including the terminating zero, or one of these error codes:
2276    .sp
2277    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
2278    .sp
2279  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
2280  memory failed for \fBpcre_get_substring()\fR.  memory failed for \fBpcre_get_substring()\fP.
2281    .sp
2282    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
2283    .sp
2284  There is no substring whose number is \fIstringnumber\fR.  There is no substring whose number is \fIstringnumber\fP.
2285    .P
2286  The \fBpcre_get_substring_list()\fR function extracts all available substrings  The \fBpcre_get_substring_list()\fP function extracts all available substrings
2287  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
2288  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
2289  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
2290  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
2291  function is zero if all went well, or  function is zero if all went well, or the error code
2292    .sp
2293    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
2294    .sp
2295  if the attempt to get the memory block failed.  if the attempt to get the memory block failed.
2296    .P
2297  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
2298  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
2299  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
2300  string. This can be distinguished from a genuine zero-length substring by  string. This can be distinguished from a genuine zero-length substring by
2301  inspecting the appropriate offset in \fIovector\fR, which is negative for unset  inspecting the appropriate offset in \fIovector\fP, which is negative for unset
2302  substrings.  substrings.
2303    .P
2304  The two convenience functions \fBpcre_free_substring()\fR and  The two convenience functions \fBpcre_free_substring()\fP and
2305  \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
2306  a previous call of \fBpcre_get_substring()\fR or  a previous call of \fBpcre_get_substring()\fP or
2307  \fBpcre_get_substring_list()\fR, respectively. They do nothing more than call  \fBpcre_get_substring_list()\fP, respectively. They do nothing more than call
2308  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
2309  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
2310  linked via a special interface to another programming language which cannot use  linked via a special interface to another programming language that cannot use
2311  \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
2312  provided.  provided.
2313    .
2314  .SH EXTRACTING CAPTURED SUBSTRINGS BY NAME  .
2315    .SH "EXTRACTING CAPTURED SUBSTRINGS BY NAME"
2316  .rs  .rs
2317  .sp  .sp
2318  .B int pcre_copy_named_substring(const pcre *\fIcode\fR,  .B int pcre_get_stringnumber(const pcre *\fIcode\fP,
2319  .ti +5n  .ti +5n
2320  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B const char *\fIname\fP);
2321    .PP
2322    .B int pcre_copy_named_substring(const pcre *\fIcode\fP,
2323  .ti +5n  .ti +5n
2324  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B const char *\fIsubject\fP, int *\fIovector\fP,
2325  .ti +5n  .ti +5n
2326  .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,  
2327  .ti +5n  .ti +5n
2328  .B const char *\fIname\fR);  .B char *\fIbuffer\fP, int \fIbuffersize\fP);
2329  .PP  .PP
2330  .br  .B int pcre_get_named_substring(const pcre *\fIcode\fP,
 .B int pcre_get_named_substring(const pcre *\fIcode\fR,  
2331  .ti +5n  .ti +5n
2332  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B const char *\fIsubject\fP, int *\fIovector\fP,
2333  .ti +5n  .ti +5n
2334  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B int \fIstringcount\fP, const char *\fIstringname\fP,
2335  .ti +5n  .ti +5n
2336  .B const char **\fIstringptr\fR);  .B const char **\fIstringptr\fP);
2337  .PP  .PP
2338  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.
2339  can be done by calling \fBpcre_get_stringnumber()\fR. The first argument is the  For example, for this pattern
2340  compiled pattern, and the second is the name. For example, for this pattern  .sp
2341      (a+)b(?<xxx>\ed+)...
2342    ab(?<xxx>\\d+)...  .sp
2343    the number of the subpattern called "xxx" is 2. If the name is known to be
2344  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
2345  extract the substring directly, or use one of the functions described in the  calling \fBpcre_get_stringnumber()\fP. The first argument is the compiled
2346  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
2347  whole job.  subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if there is no subpattern of
2348    that name.
2349  Most of the arguments of \fIpcre_copy_named_substring()\fR and  .P
2350  \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
2351  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
2352  differences.  two functions that do the whole job.
2353    .P
2354    Most of the arguments of \fBpcre_copy_named_substring()\fP and
2355    \fBpcre_get_named_substring()\fP are the same as those for the similarly named
2356    functions that extract by number. As these are described in the previous
2357    section, they are not re-described here. There are just two differences:
2358    .P
2359  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
2360  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
2361  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
2362  translation table.  translation table.
2363    .P
2364  These functions call \fBpcre_get_stringnumber()\fR, and if it succeeds, they  These functions call \fBpcre_get_stringnumber()\fP, and if it succeeds, they
2365  then call \fIpcre_copy_substring()\fR or \fIpcre_get_substring()\fR, as  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
2366  appropriate.  appropriate. \fBNOTE:\fP If PCRE_DUPNAMES is set and there are duplicate names,
2367    the behaviour may not be what you want (see the next section).
2368  .in 0  .P
2369  Last updated: 03 February 2003  \fBWarning:\fP If the pattern uses the (?| feature to set up multiple
2370  .br  subpatterns with the same number, as described in the
2371  Copyright (c) 1997-2003 University of Cambridge.  .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
2372    .\" </a>
2373    section on duplicate subpattern numbers
2374    .\"
2375    in the
2376    .\" HREF
2377    \fBpcrepattern\fP
2378    .\"
2379    page, you cannot use names to distinguish the different subpatterns, because
2380    names are not included in the compiled code. The matching process uses only
2381    numbers. For this reason, the use of different names for subpatterns of the
2382    same number causes an error at compile time.
2383    .
2384    .
2385    .SH "DUPLICATE SUBPATTERN NAMES"
2386    .rs
2387    .sp
2388    .B int pcre_get_stringtable_entries(const pcre *\fIcode\fP,
2389    .ti +5n
2390    .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
2391    .PP
2392    When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
2393    are not required to be unique. (Duplicate names are always allowed for
2394    subpatterns with the same number, created by using the (?| feature. Indeed, if
2395    such subpatterns are named, they are required to use the same names.)
2396    .P
2397    Normally, patterns with duplicate names are such that in any one match, only
2398    one of the named subpatterns participates. An example is shown in the
2399    .\" HREF
2400    \fBpcrepattern\fP
2401    .\"
2402    documentation.
2403    .P
2404    When duplicates are present, \fBpcre_copy_named_substring()\fP and
2405    \fBpcre_get_named_substring()\fP return the first substring corresponding to
2406    the given name that is set. If none are set, PCRE_ERROR_NOSUBSTRING (-7) is
2407    returned; no data is returned. The \fBpcre_get_stringnumber()\fP function
2408    returns one of the numbers that are associated with the name, but it is not
2409    defined which it is.
2410    .P
2411    If you want to get full details of all captured substrings for a given name,
2412    you must use the \fBpcre_get_stringtable_entries()\fP function. The first
2413    argument is the compiled pattern, and the second is the name. The third and
2414    fourth are pointers to variables which are updated by the function. After it
2415    has run, they point to the first and last entries in the name-to-number table
2416    for the given name. The function itself returns the length of each entry, or
2417    PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
2418    described above in the section entitled \fIInformation about a pattern\fP
2419    .\" HTML <a href="#infoaboutpattern">
2420    .\" </a>
2421    above.
2422    .\"
2423    Given all the relevant entries for the name, you can extract each of their
2424    numbers, and hence the captured data, if any.
2425    .
2426    .
2427    .SH "FINDING ALL POSSIBLE MATCHES"
2428    .rs
2429    .sp
2430    The traditional matching function uses a similar algorithm to Perl, which stops
2431    when it finds the first match, starting at a given point in the subject. If you
2432    want to find all possible matches, or the longest possible match, consider
2433    using the alternative matching function (see below) instead. If you cannot use
2434    the alternative function, but still need to find all possible matches, you
2435    can kludge it up by making use of the callout facility, which is described in
2436    the
2437    .\" HREF
2438    \fBpcrecallout\fP
2439    .\"
2440    documentation.
2441    .P
2442    What you have to do is to insert a callout right at the end of the pattern.
2443    When your callout function is called, extract and save the current matched
2444    substring. Then return 1, which forces \fBpcre_exec()\fP to backtrack and try
2445    other alternatives. Ultimately, when it runs out of matches, \fBpcre_exec()\fP
2446    will yield PCRE_ERROR_NOMATCH.
2447    .
2448    .
2449    .SH "OBTAINING AN ESTIMATE OF STACK USAGE"
2450    .rs
2451    .sp
2452    Matching certain patterns using \fBpcre_exec()\fP can use a lot of process
2453    stack, which in certain environments can be rather limited in size. Some users
2454    find it helpful to have an estimate of the amount of stack that is used by
2455    \fBpcre_exec()\fP, to help them set recursion limits, as described in the
2456    .\" HREF
2457    \fBpcrestack\fP
2458    .\"
2459    documentation. The estimate that is output by \fBpcretest\fP when called with
2460    the \fB-m\fP and \fB-C\fP options is obtained by calling \fBpcre_exec\fP with
2461    the values NULL, NULL, NULL, -999, and -999 for its first five arguments.
2462    .P
2463    Normally, if its first argument is NULL, \fBpcre_exec()\fP immediately returns
2464    the negative error code PCRE_ERROR_NULL, but with this special combination of
2465    arguments, it returns instead a negative number whose absolute value is the
2466    approximate stack frame size in bytes. (A negative number is used so that it is
2467    clear that no match has happened.) The value is approximate because in some
2468    cases, recursive calls to \fBpcre_exec()\fP occur when there are one or two
2469    additional variables on the stack.
2470    .P
2471    If PCRE has been compiled to use the heap instead of the stack for recursion,
2472    the value returned is the size of each block that is obtained from the heap.
2473    .
2474    .
2475    .\" HTML <a name="dfamatch"></a>
2476    .SH "MATCHING A PATTERN: THE ALTERNATIVE FUNCTION"
2477    .rs
2478    .sp
2479    .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
2480    .ti +5n
2481    .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
2482    .ti +5n
2483    .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,
2484    .ti +5n
2485    .B int *\fIworkspace\fP, int \fIwscount\fP);
2486    .P
2487    The function \fBpcre_dfa_exec()\fP is called to match a subject string against
2488    a compiled pattern, using a matching algorithm that scans the subject string
2489    just once, and does not backtrack. This has different characteristics to the
2490    normal algorithm, and is not compatible with Perl. Some of the features of PCRE
2491    patterns are not supported. Nevertheless, there are times when this kind of
2492    matching can be useful. For a discussion of the two matching algorithms, and a
2493    list of features that \fBpcre_dfa_exec()\fP does not support, see the
2494    .\" HREF
2495    \fBpcrematching\fP
2496    .\"
2497    documentation.
2498    .P
2499    The arguments for the \fBpcre_dfa_exec()\fP function are the same as for
2500    \fBpcre_exec()\fP, plus two extras. The \fIovector\fP argument is used in a
2501    different way, and this is described below. The other common arguments are used
2502    in the same way as for \fBpcre_exec()\fP, so their description is not repeated
2503    here.
2504    .P
2505    The two additional arguments provide workspace for the function. The workspace
2506    vector should contain at least 20 elements. It is used for keeping track of
2507    multiple paths through the pattern tree. More workspace will be needed for
2508    patterns and subjects where there are a lot of potential matches.
2509    .P
2510    Here is an example of a simple call to \fBpcre_dfa_exec()\fP:
2511    .sp
2512      int rc;
2513      int ovector[10];
2514      int wspace[20];
2515      rc = pcre_dfa_exec(
2516        re,             /* result of pcre_compile() */
2517        NULL,           /* we didn't study the pattern */
2518        "some string",  /* the subject string */
2519        11,             /* the length of the subject string */
2520        0,              /* start at offset 0 in the subject */
2521        0,              /* default options */
2522        ovector,        /* vector of integers for substring information */
2523        10,             /* number of elements (NOT size in bytes) */
2524        wspace,         /* working space vector */
2525        20);            /* number of elements (NOT size in bytes) */
2526    .
2527    .SS "Option bits for \fBpcre_dfa_exec()\fP"
2528    .rs
2529    .sp
2530    The unused bits of the \fIoptions\fP argument for \fBpcre_dfa_exec()\fP must be
2531    zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
2532    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
2533    PCRE_NO_UTF8_CHECK, PCRE_BSR_ANYCRLF, PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE,
2534    PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART.
2535    All but the last four of these are exactly the same as for \fBpcre_exec()\fP,
2536    so their description is not repeated here.
2537    .sp
2538      PCRE_PARTIAL_HARD
2539      PCRE_PARTIAL_SOFT
2540    .sp
2541    These have the same general effect as they do for \fBpcre_exec()\fP, but the
2542    details are slightly different. When PCRE_PARTIAL_HARD is set for
2543    \fBpcre_dfa_exec()\fP, it returns PCRE_ERROR_PARTIAL if the end of the subject
2544    is reached and there is still at least one matching possibility that requires
2545    additional characters. This happens even if some complete matches have also
2546    been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
2547    is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
2548    there have been no complete matches, but there is still at least one matching
2549    possibility. The portion of the string that was inspected when the longest
2550    partial match was found is set as the first matching string in both cases.
2551    There is a more detailed discussion of partial and multi-segment matching, with
2552    examples, in the
2553    .\" HREF
2554    \fBpcrepartial\fP
2555    .\"
2556    documentation.
2557    .sp
2558      PCRE_DFA_SHORTEST
2559    .sp
2560    Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as
2561    soon as it has found one match. Because of the way the alternative algorithm
2562    works, this is necessarily the shortest possible match at the first possible
2563    matching point in the subject string.
2564    .sp
2565      PCRE_DFA_RESTART
2566    .sp
2567    When \fBpcre_dfa_exec()\fP returns a partial match, it is possible to call it
2568    again, with additional subject characters, and have it continue with the same
2569    match. The PCRE_DFA_RESTART option requests this action; when it is set, the
2570    \fIworkspace\fP and \fIwscount\fP options must reference the same vector as
2571    before because data about the match so far is left in them after a partial
2572    match. There is more discussion of this facility in the
2573    .\" HREF
2574    \fBpcrepartial\fP
2575    .\"
2576    documentation.
2577    .
2578    .
2579    .SS "Successful returns from \fBpcre_dfa_exec()\fP"
2580    .rs
2581    .sp
2582    When \fBpcre_dfa_exec()\fP succeeds, it may have matched more than one
2583    substring in the subject. Note, however, that all the matches from one run of
2584    the function start at the same point in the subject. The shorter matches are
2585    all initial substrings of the longer matches. For example, if the pattern
2586    .sp
2587      <.*>
2588    .sp
2589    is matched against the string
2590    .sp
2591      This is <something> <something else> <something further> no more
2592    .sp
2593    the three matched strings are
2594    .sp
2595      <something>
2596      <something> <something else>
2597      <something> <something else> <something further>
2598    .sp
2599    On success, the yield of the function is a number greater than zero, which is
2600    the number of matched substrings. The substrings themselves are returned in
2601    \fIovector\fP. Each string uses two elements; the first is the offset to the
2602    start, and the second is the offset to the end. In fact, all the strings have
2603    the same start offset. (Space could have been saved by giving this only once,
2604    but it was decided to retain some compatibility with the way \fBpcre_exec()\fP
2605    returns data, even though the meaning of the strings is different.)
2606    .P
2607    The strings are returned in reverse order of length; that is, the longest
2608    matching string is given first. If there were too many matches to fit into
2609    \fIovector\fP, the yield of the function is zero, and the vector is filled with
2610    the longest matches. Unlike \fBpcre_exec()\fP, \fBpcre_dfa_exec()\fP can use
2611    the entire \fIovector\fP for returning matched strings.
2612    .
2613    .
2614    .SS "Error returns from \fBpcre_dfa_exec()\fP"
2615    .rs
2616    .sp
2617    The \fBpcre_dfa_exec()\fP function returns a negative number when it fails.
2618    Many of the errors are the same as for \fBpcre_exec()\fP, and these are
2619    described
2620    .\" HTML <a href="#errorlist">
2621    .\" </a>
2622    above.
2623    .\"
2624    There are in addition the following errors that are specific to
2625    \fBpcre_dfa_exec()\fP:
2626    .sp
2627      PCRE_ERROR_DFA_UITEM      (-16)
2628    .sp
2629    This return is given if \fBpcre_dfa_exec()\fP encounters an item in the pattern
2630    that it does not support, for instance, the use of \eC or a back reference.
2631    .sp
2632      PCRE_ERROR_DFA_UCOND      (-17)
2633    .sp
2634    This return is given if \fBpcre_dfa_exec()\fP encounters a condition item that
2635    uses a back reference for the condition, or a test for recursion in a specific
2636    group. These are not supported.
2637    .sp
2638      PCRE_ERROR_DFA_UMLIMIT    (-18)
2639    .sp
2640    This return is given if \fBpcre_dfa_exec()\fP is called with an \fIextra\fP
2641    block that contains a setting of the \fImatch_limit\fP or
2642    \fImatch_limit_recursion\fP fields. This is not supported (these fields are
2643    meaningless for DFA matching).
2644    .sp
2645      PCRE_ERROR_DFA_WSSIZE     (-19)
2646    .sp
2647    This return is given if \fBpcre_dfa_exec()\fP runs out of space in the
2648    \fIworkspace\fP vector.
2649    .sp
2650      PCRE_ERROR_DFA_RECURSE    (-20)
2651    .sp
2652    When a recursive subpattern is processed, the matching function calls itself
2653    recursively, using private vectors for \fIovector\fP and \fIworkspace\fP. This
2654    error is given if the output vector is not large enough. This should be
2655    extremely rare, as a vector of size 1000 is used.
2656    .sp
2657      PCRE_ERROR_DFA_BADRESTART (-30)
2658    .sp
2659    When \fBpcre_dfa_exec()\fP is called with the \fBPCRE_DFA_RESTART\fP option,
2660    some plausibility checks are made on the contents of the workspace, which
2661    should contain data about the previous partial match. If any of these checks
2662    fail, this error is given.
2663    .
2664    .
2665    .SH "SEE ALSO"
2666    .rs
2667    .sp
2668    \fBpcre16\fP(3), \fBpcrebuild\fP(3), \fBpcrecallout\fP(3), \fBpcrecpp(3)\fP(3),
2669    \fBpcrematching\fP(3), \fBpcrepartial\fP(3), \fBpcreposix\fP(3),
2670    \fBpcreprecompile\fP(3), \fBpcresample\fP(3), \fBpcrestack\fP(3).
2671    .
2672    .
2673    .SH AUTHOR
2674    .rs
2675    .sp
2676    .nf
2677    Philip Hazel
2678    University Computing Service
2679    Cambridge CB2 3QH, England.
2680    .fi
2681    .
2682    .
2683    .SH REVISION
2684    .rs
2685    .sp
2686    .nf
2687    Last updated: 07 September 2012
2688    Copyright (c) 1997-2012 University of Cambridge.
2689    .fi

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