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1  .TH PCRE 3  .TH PCREAPI 3
2  .SH NAME  .SH NAME
3  PCRE - Perl-compatible regular expressions  PCRE - Perl-compatible regular expressions
4  .SH SYNOPSIS OF PCRE API  .SH "PCRE NATIVE API BASIC FUNCTIONS"
5  .rs  .rs
6  .sp  .sp
7  .B #include <pcre.h>  .B #include <pcre.h>
8  .PP  .PP
9  .SM  .SM
10  .br  .B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,
 .B pcre *pcre_compile(const char *\fIpattern\fR, int \fIoptions\fR,  
11  .ti +5n  .ti +5n
12  .B const char **\fIerrptr\fR, int *\fIerroffset\fR,  .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
13  .ti +5n  .ti +5n
14  .B const unsigned char *\fItableptr\fR);  .B const unsigned char *\fItableptr\fP);
15  .PP  .PP
16  .br  .B pcre *pcre_compile2(const char *\fIpattern\fP, int \fIoptions\fP,
 .B pcre_extra *pcre_study(const pcre *\fIcode\fR, int \fIoptions\fR,  
17  .ti +5n  .ti +5n
18  .B const char **\fIerrptr\fR);  .B int *\fIerrorcodeptr\fP,
19    .ti +5n
20    .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
21    .ti +5n
22    .B const unsigned char *\fItableptr\fP);
23    .PP
24    .B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP,
25    .ti +5n
26    .B const char **\fIerrptr\fP);
27  .PP  .PP
28  .br  .B void pcre_free_study(pcre_extra *\fIextra\fP);
29  .B int pcre_exec(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"  .PP
30    .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
31  .ti +5n  .ti +5n
32  .B "const char *\fIsubject\fR," int \fIlength\fR, int \fIstartoffset\fR,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
33  .ti +5n  .ti +5n
34  .B int \fIoptions\fR, int *\fIovector\fR, int \fIovecsize\fR);  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
35    .
36    .
37    .SH "PCRE NATIVE API AUXILIARY FUNCTIONS"
38    .rs
39    .sp
40    .B pcre_jit_stack *pcre_jit_stack_alloc(int \fIstartsize\fP, int \fImaxsize\fP);
41    .PP
42    .B void pcre_jit_stack_free(pcre_jit_stack *\fIstack\fP);
43  .PP  .PP
44  .br  .B void pcre_assign_jit_stack(pcre_extra *\fIextra\fP,
 .B int pcre_copy_named_substring(const pcre *\fIcode\fR,  
45  .ti +5n  .ti +5n
46  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B pcre_jit_callback \fIcallback\fP, void *\fIdata\fP);
47    .PP
48    .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
49    .ti +5n
50    .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
51  .ti +5n  .ti +5n
52  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,
53  .ti +5n  .ti +5n
54  .B char *\fIbuffer\fR, int \fIbuffersize\fR);  .B int *\fIworkspace\fP, int \fIwscount\fP);
55  .PP  .PP
56  .br  .B int pcre_copy_named_substring(const pcre *\fIcode\fP,
 .B int pcre_copy_substring(const char *\fIsubject\fR, int *\fIovector\fR,  
57  .ti +5n  .ti +5n
58  .B int \fIstringcount\fR, int \fIstringnumber\fR, char *\fIbuffer\fR,  .B const char *\fIsubject\fP, int *\fIovector\fP,
59  .ti +5n  .ti +5n
60  .B int \fIbuffersize\fR);  .B int \fIstringcount\fP, const char *\fIstringname\fP,
61    .ti +5n
62    .B char *\fIbuffer\fP, int \fIbuffersize\fP);
63  .PP  .PP
64  .br  .B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\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 int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP,
67  .ti +5n  .ti +5n
68  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B int \fIbuffersize\fP);
69    .PP
70    .B int pcre_get_named_substring(const pcre *\fIcode\fP,
71  .ti +5n  .ti +5n
72  .B const char **\fIstringptr\fR);  .B const char *\fIsubject\fP, int *\fIovector\fP,
73    .ti +5n
74    .B int \fIstringcount\fP, const char *\fIstringname\fP,
75    .ti +5n
76    .B const char **\fIstringptr\fP);
77  .PP  .PP
78  .br  .B int pcre_get_stringnumber(const pcre *\fIcode\fP,
 .B int pcre_get_stringnumber(const pcre *\fIcode\fR,  
79  .ti +5n  .ti +5n
80  .B const char *\fIname\fR);  .B const char *\fIname\fP);
81  .PP  .PP
82  .br  .B int pcre_get_stringtable_entries(const pcre *\fIcode\fP,
 .B int pcre_get_substring(const char *\fIsubject\fR, int *\fIovector\fR,  
83  .ti +5n  .ti +5n
84  .B int \fIstringcount\fR, int \fIstringnumber\fR,  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
85    .PP
86    .B int pcre_get_substring(const char *\fIsubject\fP, int *\fIovector\fP,
87  .ti +5n  .ti +5n
88  .B const char **\fIstringptr\fR);  .B int \fIstringcount\fP, int \fIstringnumber\fP,
89    .ti +5n
90    .B const char **\fIstringptr\fP);
91  .PP  .PP
92  .br  .B int pcre_get_substring_list(const char *\fIsubject\fP,
 .B int pcre_get_substring_list(const char *\fIsubject\fR,  
93  .ti +5n  .ti +5n
94  .B int *\fIovector\fR, int \fIstringcount\fR, "const char ***\fIlistptr\fR);"  .B int *\fIovector\fP, int \fIstringcount\fP, "const char ***\fIlistptr\fP);"
95  .PP  .PP
96  .br  .B void pcre_free_substring(const char *\fIstringptr\fP);
 .B void pcre_free_substring(const char *\fIstringptr\fR);  
97  .PP  .PP
98  .br  .B void pcre_free_substring_list(const char **\fIstringptr\fP);
 .B void pcre_free_substring_list(const char **\fIstringptr\fR);  
99  .PP  .PP
 .br  
100  .B const unsigned char *pcre_maketables(void);  .B const unsigned char *pcre_maketables(void);
101  .PP  .PP
102  .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,"  
103  .ti +5n  .ti +5n
104  .B int \fIwhat\fR, void *\fIwhere\fR);  .B int \fIwhat\fP, void *\fIwhere\fP);
105    .PP
106    .B int pcre_info(const pcre *\fIcode\fP, int *\fIoptptr\fP, int
107    .B *\fIfirstcharptr\fP);
108  .PP  .PP
109  .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);  
110  .PP  .PP
111  .br  .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
 .B int pcre_config(int \fIwhat\fR, void *\fIwhere\fR);  
112  .PP  .PP
 .br  
113  .B char *pcre_version(void);  .B char *pcre_version(void);
114  .PP  .PP
 .br  
115  .B void *(*pcre_malloc)(size_t);  .B void *(*pcre_malloc)(size_t);
116  .PP  .PP
 .br  
117  .B void (*pcre_free)(void *);  .B void (*pcre_free)(void *);
118  .PP  .PP
119  .br  .B void *(*pcre_stack_malloc)(size_t);
120    .PP
121    .B void (*pcre_stack_free)(void *);
122    .PP
123  .B int (*pcre_callout)(pcre_callout_block *);  .B int (*pcre_callout)(pcre_callout_block *);
124    .
125  .SH PCRE API  .
126    .SH "PCRE API OVERVIEW"
127  .rs  .rs
128  .sp  .sp
129  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
130  a set of wrapper functions that correspond to the POSIX regular expression API.  also some wrapper functions that correspond to the POSIX regular expression
131  These are described in the \fBpcreposix\fR documentation.  API, but they do not give access to all the functionality. They are described
132    in the
133  The native API function prototypes are defined in the header file \fBpcre.h\fR,  .\" HREF
134  and on Unix systems the library itself is called \fBlibpcre.a\fR, so can be  \fBpcreposix\fP
135  accessed by adding \fB-lpcre\fR to the command for linking an application which  .\"
136  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++
137  contain the major and minor release numbers for the library. Applications can  wrapper is also distributed with PCRE. It is documented in the
138  use these to include support for different releases.  .\" HREF
139    \fBpcrecpp\fP
140  The functions \fBpcre_compile()\fR, \fBpcre_study()\fR, and \fBpcre_exec()\fR  .\"
141  are used for compiling and matching regular expressions. A sample program that  page.
142  demonstrates the simplest way of using them is given in the file  .P
143  \fIpcredemo.c\fR. The \fBpcresample\fR documentation describes how to run it.  The native API C function prototypes are defined in the header file
144    \fBpcre.h\fP, and on Unix systems the library itself is called \fBlibpcre\fP.
145  There are convenience functions for extracting captured substrings from a  It can normally be accessed by adding \fB-lpcre\fP to the command for linking
146  matched subject string. They are:  an application that uses PCRE. The header file defines the macros PCRE_MAJOR
147    and PCRE_MINOR to contain the major and minor release numbers for the library.
148    \fBpcre_copy_substring()\fR  Applications can use these to include support for different releases of PCRE.
149    \fBpcre_copy_named_substring()\fR  .P
150    \fBpcre_get_substring()\fR  In a Windows environment, if you want to statically link an application program
151    \fBpcre_get_named_substring()\fR  against a non-dll \fBpcre.a\fP file, you must define PCRE_STATIC before
152    \fBpcre_get_substring_list()\fR  including \fBpcre.h\fP or \fBpcrecpp.h\fP, because otherwise the
153    \fBpcre_malloc()\fP and \fBpcre_free()\fP exported functions will be declared
154  \fBpcre_free_substring()\fR and \fBpcre_free_substring_list()\fR are also  \fB__declspec(dllimport)\fP, with unwanted results.
155    .P
156    The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,
157    and \fBpcre_exec()\fP are used for compiling and matching regular expressions
158    in a Perl-compatible manner. A sample program that demonstrates the simplest
159    way of using them is provided in the file called \fIpcredemo.c\fP in the PCRE
160    source distribution. A listing of this program is given in the
161    .\" HREF
162    \fBpcredemo\fP
163    .\"
164    documentation, and the
165    .\" HREF
166    \fBpcresample\fP
167    .\"
168    documentation describes how to compile and run it.
169    .P
170    Just-in-time compiler support is an optional feature of PCRE that can be built
171    in appropriate hardware environments. It greatly speeds up the matching
172    performance of many patterns. Simple programs can request its use if available.
173    More complicated programs might need to make use of the
174    \fBpcre_jit_stack_alloc()\fP, \fBpcre_jit_stack_free()\fP, and
175    \fBpcre_assign_jit_stack()\fP functions in order to control its memory usage.
176    These functions are discussed in the
177    .\" HREF
178    \fBpcrejit\fP
179    .\"
180    documentation.
181    .P
182    A second matching function, \fBpcre_dfa_exec()\fP, which is not
183    Perl-compatible, is also provided. This uses a different algorithm for the
184    matching. The alternative algorithm finds all possible matches (at a given
185    point in the subject), and scans the subject just once (unless there are
186    lookbehind assertions). However, this algorithm does not return captured
187    substrings. A description of the two matching algorithms and their advantages
188    and disadvantages is given in the
189    .\" HREF
190    \fBpcrematching\fP
191    .\"
192    documentation.
193    .P
194    In addition to the main compiling and matching functions, there are convenience
195    functions for extracting captured substrings from a subject string that is
196    matched by \fBpcre_exec()\fP. They are:
197    .sp
198      \fBpcre_copy_substring()\fP
199      \fBpcre_copy_named_substring()\fP
200      \fBpcre_get_substring()\fP
201      \fBpcre_get_named_substring()\fP
202      \fBpcre_get_substring_list()\fP
203      \fBpcre_get_stringnumber()\fP
204      \fBpcre_get_stringtable_entries()\fP
205    .sp
206    \fBpcre_free_substring()\fP and \fBpcre_free_substring_list()\fP are also
207  provided, to free the memory used for extracted strings.  provided, to free the memory used for extracted strings.
208    .P
209  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
210  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,
211    or \fBpcre_dfa_exec()\fP. This is an optional facility that is provided for
212  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
213  compiled pattern; \fBpcre_info()\fR is an obsolete version which returns only  internal tables that are generated when PCRE is built are used.
214    .P
215    The function \fBpcre_fullinfo()\fP is used to find out information about a
216    compiled pattern; \fBpcre_info()\fP is an obsolete version that returns only
217  some of the available information, but is retained for backwards compatibility.  some of the available information, but is retained for backwards compatibility.
218  The function \fBpcre_version()\fR returns a pointer to a string containing the  The function \fBpcre_version()\fP returns a pointer to a string containing the
219  version of PCRE and its date of release.  version of PCRE and its date of release.
220    .P
221  The global variables \fBpcre_malloc\fR and \fBpcre_free\fR initially contain  The function \fBpcre_refcount()\fP maintains a reference count in a data block
222  the entry points of the standard \fBmalloc()\fR and \fBfree()\fR functions  containing a compiled pattern. This is provided for the benefit of
223    object-oriented applications.
224    .P
225    The global variables \fBpcre_malloc\fP and \fBpcre_free\fP initially contain
226    the entry points of the standard \fBmalloc()\fP and \fBfree()\fP functions,
227  respectively. PCRE calls the memory management functions via these variables,  respectively. PCRE calls the memory management functions via these variables,
228  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
229  should be done before calling any PCRE functions.  should be done before calling any PCRE functions.
230    .P
231  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
232    indirections to memory management functions. These special functions are used
233    only when PCRE is compiled to use the heap for remembering data, instead of
234    recursive function calls, when running the \fBpcre_exec()\fP function. See the
235    .\" HREF
236    \fBpcrebuild\fP
237    .\"
238    documentation for details of how to do this. It is a non-standard way of
239    building PCRE, for use in environments that have limited stacks. Because of the
240    greater use of memory management, it runs more slowly. Separate functions are
241    provided so that special-purpose external code can be used for this case. When
242    used, these functions are always called in a stack-like manner (last obtained,
243    first freed), and always for memory blocks of the same size. There is a
244    discussion about PCRE's stack usage in the
245    .\" HREF
246    \fBpcrestack\fP
247    .\"
248    documentation.
249    .P
250    The global variable \fBpcre_callout\fP initially contains NULL. It can be set
251  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
252  points during a matching operation. Details are given in the \fBpcrecallout\fR  points during a matching operation. Details are given in the
253    .\" HREF
254    \fBpcrecallout\fP
255    .\"
256  documentation.  documentation.
257    .
258    .
259    .\" HTML <a name="newlines"></a>
260    .SH NEWLINES
261    .rs
262    .sp
263    PCRE supports five different conventions for indicating line breaks in
264    strings: a single CR (carriage return) character, a single LF (linefeed)
265    character, the two-character sequence CRLF, any of the three preceding, or any
266    Unicode newline sequence. The Unicode newline sequences are the three just
267    mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed,
268    U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
269    (paragraph separator, U+2029).
270    .P
271    Each of the first three conventions is used by at least one operating system as
272    its standard newline sequence. When PCRE is built, a default can be specified.
273    The default default is LF, which is the Unix standard. When PCRE is run, the
274    default can be overridden, either when a pattern is compiled, or when it is
275    matched.
276    .P
277    At compile time, the newline convention can be specified by the \fIoptions\fP
278    argument of \fBpcre_compile()\fP, or it can be specified by special text at the
279    start of the pattern itself; this overrides any other settings. See the
280    .\" HREF
281    \fBpcrepattern\fP
282    .\"
283    page for details of the special character sequences.
284    .P
285    In the PCRE documentation the word "newline" is used to mean "the character or
286    pair of characters that indicate a line break". The choice of newline
287    convention affects the handling of the dot, circumflex, and dollar
288    metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
289    recognized line ending sequence, the match position advancement for a
290    non-anchored pattern. There is more detail about this in the
291    .\" HTML <a href="#execoptions">
292    .\" </a>
293    section on \fBpcre_exec()\fP options
294    .\"
295    below.
296    .P
297    The choice of newline convention does not affect the interpretation of
298    the \en or \er escape sequences, nor does it affect what \eR matches, which is
299    controlled in a similar way, but by separate options.
300    .
301    .
302  .SH MULTITHREADING  .SH MULTITHREADING
303  .rs  .rs
304  .sp  .sp
305  The PCRE functions can be used in multi-threading applications, with the  The PCRE functions can be used in multi-threading applications, with the
306  proviso that the memory management functions pointed to by \fBpcre_malloc\fR  proviso that the memory management functions pointed to by \fBpcre_malloc\fP,
307  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
308  are shared by all threads.  callout function pointed to by \fBpcre_callout\fP, are shared by all threads.
309    .P
310  The compiled form of a regular expression is not altered during matching, so  The compiled form of a regular expression is not altered during matching, so
311  the same compiled pattern can safely be used by several threads at once.  the same compiled pattern can safely be used by several threads at once.
312    .P
313  .SH CHECKING BUILD-TIME OPTIONS  If the just-in-time optimization feature is being used, it needs separate
314    memory stack areas for each thread. See the
315    .\" HREF
316    \fBpcrejit\fP
317    .\"
318    documentation for more details.
319    .
320    .
321    .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"
322  .rs  .rs
323  .sp  .sp
324  .B int pcre_config(int \fIwhat\fR, void *\fIwhere\fR);  The compiled form of a regular expression can be saved and re-used at a later
325    time, possibly by a different program, and even on a host other than the one on
326    which it was compiled. Details are given in the
327    .\" HREF
328    \fBpcreprecompile\fP
329    .\"
330    documentation. However, compiling a regular expression with one version of PCRE
331    for use with a different version is not guaranteed to work and may cause
332    crashes.
333    .
334    .
335    .SH "CHECKING BUILD-TIME OPTIONS"
336    .rs
337    .sp
338    .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
339  .PP  .PP
340  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
341  discover which optional features have been compiled into the PCRE library. The  discover which optional features have been compiled into the PCRE library. The
342  .\" HREF  .\" HREF
343  \fBpcrebuild\fR  \fBpcrebuild\fP
344  .\"  .\"
345  documentation has more details about these optional features.  documentation has more details about these optional features.
346    .P
347  The first argument for \fBpcre_config()\fR is an integer, specifying which  The first argument for \fBpcre_config()\fP is an integer, specifying which
348  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
349  which the information is placed. The following information is available:  which the information is placed. The following information is available:
350    .sp
351    PCRE_CONFIG_UTF8    PCRE_CONFIG_UTF8
352    .sp
353  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;
354  otherwise it is set to zero.  otherwise it is set to zero.
355    .sp
356      PCRE_CONFIG_UNICODE_PROPERTIES
357    .sp
358    The output is an integer that is set to one if support for Unicode character
359    properties is available; otherwise it is set to zero.
360    .sp
361      PCRE_CONFIG_JIT
362    .sp
363    The output is an integer that is set to one if support for just-in-time
364    compiling is available; otherwise it is set to zero.
365    .sp
366    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
367    .sp
368  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
369  the newline character. It is either linefeed (10) or carriage return (13), and  that is recognized as meaning "newline". The four values that are supported
370  should normally be the standard character for your operating system.  are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF, and -1 for ANY.
371    Though they are derived from ASCII, the same values are returned in EBCDIC
372    environments. The default should normally correspond to the standard sequence
373    for your operating system.
374    .sp
375      PCRE_CONFIG_BSR
376    .sp
377    The output is an integer whose value indicates what character sequences the \eR
378    escape sequence matches by default. A value of 0 means that \eR matches any
379    Unicode line ending sequence; a value of 1 means that \eR matches only CR, LF,
380    or CRLF. The default can be overridden when a pattern is compiled or matched.
381    .sp
382    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
383    .sp
384  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
385  linkage in compiled regular expressions. The value is 2, 3, or 4. Larger values  linkage in compiled regular expressions. The value is 2, 3, or 4. Larger values
386  allow larger regular expressions to be compiled, at the expense of slower  allow larger regular expressions to be compiled, at the expense of slower
387  matching. The default value of 2 is sufficient for all but the most massive  matching. The default value of 2 is sufficient for all but the most massive
388  patterns, since it allows the compiled pattern to be up to 64K in size.  patterns, since it allows the compiled pattern to be up to 64K in size.
389    .sp
390    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
391    .sp
392  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
393  interface uses \fBmalloc()\fR for output vectors. Further details are given in  interface uses \fBmalloc()\fP for output vectors. Further details are given in
394  the \fBpcreposix\fR documentation.  the
395    .\" HREF
396    \fBpcreposix\fP
397    .\"
398    documentation.
399    .sp
400    PCRE_CONFIG_MATCH_LIMIT    PCRE_CONFIG_MATCH_LIMIT
401    .sp
402  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
403  internal matching function calls in a \fBpcre_exec()\fR execution. Further  internal matching function calls in a \fBpcre_exec()\fP execution. Further
404  details are given with \fBpcre_exec()\fR below.  details are given with \fBpcre_exec()\fP below.
405    .sp
406  .SH COMPILING A PATTERN    PCRE_CONFIG_MATCH_LIMIT_RECURSION
407  .rs  .sp
408  .sp  The output is a long integer that gives the default limit for the depth of
409  .B pcre *pcre_compile(const char *\fIpattern\fR, int \fIoptions\fR,  recursion when calling the internal matching function in a \fBpcre_exec()\fP
410  .ti +5n  execution. Further details are given with \fBpcre_exec()\fP below.
411  .B const char **\fIerrptr\fR, int *\fIerroffset\fR,  .sp
412  .ti +5n    PCRE_CONFIG_STACKRECURSE
413  .B const unsigned char *\fItableptr\fR);  .sp
414  .PP  The output is an integer that is set to one if internal recursion when running
415    \fBpcre_exec()\fP is implemented by recursive function calls that use the stack
416  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
417  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
418  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
419  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
420  code and related data. The \fBpcre\fR type is defined for the returned block;  avoiding the use of the stack.
421  this is a typedef for a structure whose contents are not externally defined. It  .
422  is up to the caller to free the memory when it is no longer required.  .
423    .SH "COMPILING A PATTERN"
424    .rs
425    .sp
426    .B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,
427    .ti +5n
428    .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
429    .ti +5n
430    .B const unsigned char *\fItableptr\fP);
431    .sp
432    .B pcre *pcre_compile2(const char *\fIpattern\fP, int \fIoptions\fP,
433    .ti +5n
434    .B int *\fIerrorcodeptr\fP,
435    .ti +5n
436    .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
437    .ti +5n
438    .B const unsigned char *\fItableptr\fP);
439    .P
440    Either of the functions \fBpcre_compile()\fP or \fBpcre_compile2()\fP can be
441    called to compile a pattern into an internal form. The only difference between
442    the two interfaces is that \fBpcre_compile2()\fP has an additional argument,
443    \fIerrorcodeptr\fP, via which a numerical error code can be returned. To avoid
444    too much repetition, we refer just to \fBpcre_compile()\fP below, but the
445    information applies equally to \fBpcre_compile2()\fP.
446    .P
447    The pattern is a C string terminated by a binary zero, and is passed in the
448    \fIpattern\fP argument. A pointer to a single block of memory that is obtained
449    via \fBpcre_malloc\fP is returned. This contains the compiled code and related
450    data. The \fBpcre\fP type is defined for the returned block; this is a typedef
451    for a structure whose contents are not externally defined. It is up to the
452    caller to free the memory (via \fBpcre_free\fP) when it is no longer required.
453    .P
454  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
455  depend on memory location, the complete \fBpcre\fR data block is not  depend on memory location, the complete \fBpcre\fP data block is not
456  fully relocatable, because it contains a copy of the \fItableptr\fR argument,  fully relocatable, because it may contain a copy of the \fItableptr\fP
457  which is an address (see below).  argument, which is an address (see below).
458    .P
459  The \fIoptions\fR argument contains independent bits that affect the  The \fIoptions\fP argument contains various bit settings that affect the
460  compilation. It should be zero if no options are required. Some of the options,  compilation. It should be zero if no options are required. The available
461  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
462  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
463  in the \fBpcrepattern\fR documentation). For these options, the contents of the  within the pattern (see the detailed description in the
464  \fIoptions\fR argument specifies their initial settings at the start of  .\" HREF
465  compilation and execution. The PCRE_ANCHORED option can be set at the time of  \fBpcrepattern\fP
466  matching as well as at compile time.  .\"
467    documentation). For those options that can be different in different parts of
468  If \fIerrptr\fR is NULL, \fBpcre_compile()\fR returns NULL immediately.  the pattern, the contents of the \fIoptions\fP argument specifies their
469  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fR returns  settings at the start of compilation and execution. The PCRE_ANCHORED,
470  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
471  error message. The offset from the start of the pattern to the character where  PCRE_NO_START_OPT options can be set at the time of matching as well as at
472  the error was discovered is placed in the variable pointed to by  compile time.
473  \fIerroffset\fR, which must not be NULL. If it is, an immediate error is given.  .P
474    If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
475  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
476  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
477  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
478  \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
479    byte that was being processed when the error was discovered is placed in the
480  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
481    immediate error is given). However, for an invalid UTF-8 string, the offset is
482    that of the first byte of the failing character. Also, some errors are not
483    detected until checks are carried out when the whole pattern has been scanned;
484    in these cases the offset passed back is the length of the pattern.
485    .P
486    Note that the offset is in bytes, not characters, even in UTF-8 mode. It may
487    sometimes point into the middle of a UTF-8 character.
488    .P
489    If \fBpcre_compile2()\fP is used instead of \fBpcre_compile()\fP, and the
490    \fIerrorcodeptr\fP argument is not NULL, a non-zero error code number is
491    returned via this argument in the event of an error. This is in addition to the
492    textual error message. Error codes and messages are listed below.
493    .P
494    If the final argument, \fItableptr\fP, is NULL, PCRE uses a default set of
495    character tables that are built when PCRE is compiled, using the default C
496    locale. Otherwise, \fItableptr\fP must be an address that is the result of a
497    call to \fBpcre_maketables()\fP. This value is stored with the compiled
498    pattern, and used again by \fBpcre_exec()\fP, unless another table pointer is
499    passed to it. For more discussion, see the section on locale support below.
500    .P
501    This code fragment shows a typical straightforward call to \fBpcre_compile()\fP:
502    .sp
503    pcre *re;    pcre *re;
504    const char *error;    const char *error;
505    int erroffset;    int erroffset;
# Line 265  This code fragment shows a typical strai Line 509  This code fragment shows a typical strai
509      &error,           /* for error message */      &error,           /* for error message */
510      &erroffset,       /* for error offset */      &erroffset,       /* for error offset */
511      NULL);            /* use default character tables */      NULL);            /* use default character tables */
512    .sp
513  The following option bits are defined:  The following names for option bits are defined in the \fBpcre.h\fP header
514    file:
515    .sp
516    PCRE_ANCHORED    PCRE_ANCHORED
517    .sp
518  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
519  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
520  being searched (the "subject string"). This effect can also be achieved by  being searched (the "subject string"). This effect can also be achieved by
521  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
522  Perl.  Perl.
523    .sp
524      PCRE_AUTO_CALLOUT
525    .sp
526    If this bit is set, \fBpcre_compile()\fP automatically inserts callout items,
527    all with number 255, before each pattern item. For discussion of the callout
528    facility, see the
529    .\" HREF
530    \fBpcrecallout\fP
531    .\"
532    documentation.
533    .sp
534      PCRE_BSR_ANYCRLF
535      PCRE_BSR_UNICODE
536    .sp
537    These options (which are mutually exclusive) control what the \eR escape
538    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
539    match any Unicode newline sequence. The default is specified when PCRE is
540    built. It can be overridden from within the pattern, or by setting an option
541    when a compiled pattern is matched.
542    .sp
543    PCRE_CASELESS    PCRE_CASELESS
544    .sp
545  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
546  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
547  pattern by a (?i) option setting.  pattern by a (?i) option setting. In UTF-8 mode, PCRE always understands the
548    concept of case for characters whose values are less than 128, so caseless
549    matching is always possible. For characters with higher values, the concept of
550    case is supported if PCRE is compiled with Unicode property support, but not
551    otherwise. If you want to use caseless matching for characters 128 and above,
552    you must ensure that PCRE is compiled with Unicode property support as well as
553    with UTF-8 support.
554    .sp
555    PCRE_DOLLAR_ENDONLY    PCRE_DOLLAR_ENDONLY
556    .sp
557  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
558  end of the subject string. Without this option, a dollar also matches  end of the subject string. Without this option, a dollar also matches
559  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
560  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.
561  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
562  a pattern.  pattern.
563    .sp
564    PCRE_DOTALL    PCRE_DOTALL
565    .sp
566  If this bit is set, a dot metacharater in the pattern matches all characters,  If this bit is set, a dot metacharacter in the pattern matches a character of
567  including newlines. Without it, newlines are excluded. This option is  any value, including one that indicates a newline. However, it only ever
568    matches one character, even if newlines are coded as CRLF. Without this option,
569    a dot does not match when the current position is at a newline. This option is
570  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
571  (?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
572  character, independent of the setting of this option.  characters, independent of the setting of this option.
573    .sp
574      PCRE_DUPNAMES
575    .sp
576    If this bit is set, names used to identify capturing subpatterns need not be
577    unique. This can be helpful for certain types of pattern when it is known that
578    only one instance of the named subpattern can ever be matched. There are more
579    details of named subpatterns below; see also the
580    .\" HREF
581    \fBpcrepattern\fP
582    .\"
583    documentation.
584    .sp
585    PCRE_EXTENDED    PCRE_EXTENDED
586    .sp
587  If this bit is set, whitespace data characters in the pattern are totally  If this bit is set, whitespace data characters in the pattern are totally
588  ignored except when escaped or inside a character class. Whitespace does not  ignored except when escaped or inside a character class. Whitespace does not
589  include the VT character (code 11). In addition, characters between an  include the VT character (code 11). In addition, characters between an
590  unescaped # outside a character class and the next newline character,  unescaped # outside a character class and the next newline, inclusive, are also
591  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
592  be changed within a pattern by a (?x) option setting.  pattern by a (?x) option setting.
593    .P
594    Which characters are interpreted as newlines is controlled by the options
595    passed to \fBpcre_compile()\fP or by a special sequence at the start of the
596    pattern, as described in the section entitled
597    .\" HTML <a href="pcrepattern.html#newlines">
598    .\" </a>
599    "Newline conventions"
600    .\"
601    in the \fBpcrepattern\fP documentation. Note that the end of this type of
602    comment is a literal newline sequence in the pattern; escape sequences that
603    happen to represent a newline do not count.
604    .P
605  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
606  Note, however, that this applies only to data characters. Whitespace characters  Note, however, that this applies only to data characters. Whitespace characters
607  may never appear within special character sequences in a pattern, for example  may never appear within special character sequences in a pattern, for example
608  within the sequence (?( which introduces a conditional subpattern.  within the sequence (?( that introduces a conditional subpattern.
609    .sp
610    PCRE_EXTRA    PCRE_EXTRA
611    .sp
612  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
613  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
614  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
615  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
616  expansion. By default, as in Perl, a backslash followed by a letter with no  expansion. By default, as in Perl, a backslash followed by a letter with no
617  special meaning is treated as a literal. There are at present no other features  special meaning is treated as a literal. (Perl can, however, be persuaded to
618  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
619  pattern.  no other features controlled by this option. It can also be set by a (?X)
620    option setting within a pattern.
621    .sp
622      PCRE_FIRSTLINE
623    .sp
624    If this option is set, an unanchored pattern is required to match before or at
625    the first newline in the subject string, though the matched text may continue
626    over the newline.
627    .sp
628      PCRE_JAVASCRIPT_COMPAT
629    .sp
630    If this option is set, PCRE's behaviour is changed in some ways so that it is
631    compatible with JavaScript rather than Perl. The changes are as follows:
632    .P
633    (1) A lone closing square bracket in a pattern causes a compile-time error,
634    because this is illegal in JavaScript (by default it is treated as a data
635    character). Thus, the pattern AB]CD becomes illegal when this option is set.
636    .P
637    (2) At run time, a back reference to an unset subpattern group matches an empty
638    string (by default this causes the current matching alternative to fail). A
639    pattern such as (\e1)(a) succeeds when this option is set (assuming it can find
640    an "a" in the subject), whereas it fails by default, for Perl compatibility.
641    .sp
642    PCRE_MULTILINE    PCRE_MULTILINE
643    .sp
644  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
645  characters (even if it actually contains several newlines). The "start of line"  characters (even if it actually contains newlines). The "start of line"
646  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
647  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
648  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
649  Perl.  Perl.
650    .P
651  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
652  match immediately following or immediately before any newline in the subject  match immediately following or immediately before internal newlines in the
653  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
654  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
655  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
656  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.
657    .sp
658      PCRE_NEWLINE_CR
659      PCRE_NEWLINE_LF
660      PCRE_NEWLINE_CRLF
661      PCRE_NEWLINE_ANYCRLF
662      PCRE_NEWLINE_ANY
663    .sp
664    These options override the default newline definition that was chosen when PCRE
665    was built. Setting the first or the second specifies that a newline is
666    indicated by a single character (CR or LF, respectively). Setting
667    PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
668    CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three
669    preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies
670    that any Unicode newline sequence should be recognized. The Unicode newline
671    sequences are the three just mentioned, plus the single characters VT (vertical
672    tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS (line
673    separator, U+2028), and PS (paragraph separator, U+2029). The last two are
674    recognized only in UTF-8 mode.
675    .P
676    The newline setting in the options word uses three bits that are treated
677    as a number, giving eight possibilities. Currently only six are used (default
678    plus the five values above). This means that if you set more than one newline
679    option, the combination may or may not be sensible. For example,
680    PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
681    other combinations may yield unused numbers and cause an error.
682    .P
683    The only time that a line break in a pattern is specially recognized when
684    compiling is when PCRE_EXTENDED is set. CR and LF are whitespace characters,
685    and so are ignored in this mode. Also, an unescaped # outside a character class
686    indicates a comment that lasts until after the next line break sequence. In
687    other circumstances, line break sequences in patterns are treated as literal
688    data.
689    .P
690    The newline option that is set at compile time becomes the default that is used
691    for \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, but it can be overridden.
692    .sp
693    PCRE_NO_AUTO_CAPTURE    PCRE_NO_AUTO_CAPTURE
694    .sp
695  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
696  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
697  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
698  they acquire numbers in the usual way). There is no equivalent of this option  they acquire numbers in the usual way). There is no equivalent of this option
699  in Perl.  in Perl.
700    .sp
701      NO_START_OPTIMIZE
702    .sp
703    This is an option that acts at matching time; that is, it is really an option
704    for \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. If it is set at compile time,
705    it is remembered with the compiled pattern and assumed at matching time. For
706    details see the discussion of PCRE_NO_START_OPTIMIZE
707    .\" HTML <a href="#execoptions">
708    .\" </a>
709    below.
710    .\"
711    .sp
712      PCRE_UCP
713    .sp
714    This option changes the way PCRE processes \eB, \eb, \eD, \ed, \eS, \es, \eW,
715    \ew, and some of the POSIX character classes. By default, only ASCII characters
716    are recognized, but if PCRE_UCP is set, Unicode properties are used instead to
717    classify characters. More details are given in the section on
718    .\" HTML <a href="pcre.html#genericchartypes">
719    .\" </a>
720    generic character types
721    .\"
722    in the
723    .\" HREF
724    \fBpcrepattern\fP
725    .\"
726    page. If you set PCRE_UCP, matching one of the items it affects takes much
727    longer. The option is available only if PCRE has been compiled with Unicode
728    property support.
729    .sp
730    PCRE_UNGREEDY    PCRE_UNGREEDY
731    .sp
732  This option inverts the "greediness" of the quantifiers so that they are not  This option inverts the "greediness" of the quantifiers so that they are not
733  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
734  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.
735    .sp
736    PCRE_UTF8    PCRE_UTF8
737    .sp
738  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
739  of UTF-8 characters instead of single-byte character strings. However, it is  of UTF-8 characters instead of single-byte character strings. However, it is
740  available only if PCRE has been built to include UTF-8 support. If not, the use  available only when PCRE is built to include UTF-8 support. If not, the use
741  of this option provokes an error. Details of how this option changes the  of this option provokes an error. Details of how this option changes the
742  behaviour of PCRE are given in the  behaviour of PCRE are given in the
743  .\" HTML <a href="pcre.html#utf8support">  .\" HREF
744    \fBpcreunicode\fP
745    .\"
746    page.
747    .sp
748      PCRE_NO_UTF8_CHECK
749    .sp
750    When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
751    automatically checked. There is a discussion about the
752    .\" HTML <a href="pcre.html#utf8strings">
753  .\" </a>  .\" </a>
754  section on UTF-8 support  validity of UTF-8 strings
755  .\"  .\"
756  in the main  in the main
757  .\" HREF  .\" HREF
758  \fBpcre\fR  \fBpcre\fP
759  .\"  .\"
760  page.  page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_compile()\fP
761    returns an error. If you already know that your pattern is valid, and you want
762  .SH STUDYING A PATTERN  to skip this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK
763    option. When it is set, the effect of passing an invalid UTF-8 string as a
764    pattern is undefined. It may cause your program to crash. Note that this option
765    can also be passed to \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, to suppress
766    the UTF-8 validity checking of subject strings.
767    .
768    .
769    .SH "COMPILATION ERROR CODES"
770    .rs
771    .sp
772    The following table lists the error codes than may be returned by
773    \fBpcre_compile2()\fP, along with the error messages that may be returned by
774    both compiling functions. As PCRE has developed, some error codes have fallen
775    out of use. To avoid confusion, they have not been re-used.
776    .sp
777       0  no error
778       1  \e at end of pattern
779       2  \ec at end of pattern
780       3  unrecognized character follows \e
781       4  numbers out of order in {} quantifier
782       5  number too big in {} quantifier
783       6  missing terminating ] for character class
784       7  invalid escape sequence in character class
785       8  range out of order in character class
786       9  nothing to repeat
787      10  [this code is not in use]
788      11  internal error: unexpected repeat
789      12  unrecognized character after (? or (?-
790      13  POSIX named classes are supported only within a class
791      14  missing )
792      15  reference to non-existent subpattern
793      16  erroffset passed as NULL
794      17  unknown option bit(s) set
795      18  missing ) after comment
796      19  [this code is not in use]
797      20  regular expression is too large
798      21  failed to get memory
799      22  unmatched parentheses
800      23  internal error: code overflow
801      24  unrecognized character after (?<
802      25  lookbehind assertion is not fixed length
803      26  malformed number or name after (?(
804      27  conditional group contains more than two branches
805      28  assertion expected after (?(
806      29  (?R or (?[+-]digits must be followed by )
807      30  unknown POSIX class name
808      31  POSIX collating elements are not supported
809      32  this version of PCRE is not compiled with PCRE_UTF8 support
810      33  [this code is not in use]
811      34  character value in \ex{...} sequence is too large
812      35  invalid condition (?(0)
813      36  \eC not allowed in lookbehind assertion
814      37  PCRE does not support \eL, \el, \eN{name}, \eU, or \eu
815      38  number after (?C is > 255
816      39  closing ) for (?C expected
817      40  recursive call could loop indefinitely
818      41  unrecognized character after (?P
819      42  syntax error in subpattern name (missing terminator)
820      43  two named subpatterns have the same name
821      44  invalid UTF-8 string
822      45  support for \eP, \ep, and \eX has not been compiled
823      46  malformed \eP or \ep sequence
824      47  unknown property name after \eP or \ep
825      48  subpattern name is too long (maximum 32 characters)
826      49  too many named subpatterns (maximum 10000)
827      50  [this code is not in use]
828      51  octal value is greater than \e377 (not in UTF-8 mode)
829      52  internal error: overran compiling workspace
830      53  internal error: previously-checked referenced subpattern
831            not found
832      54  DEFINE group contains more than one branch
833      55  repeating a DEFINE group is not allowed
834      56  inconsistent NEWLINE options
835      57  \eg is not followed by a braced, angle-bracketed, or quoted
836            name/number or by a plain number
837      58  a numbered reference must not be zero
838      59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
839      60  (*VERB) not recognized
840      61  number is too big
841      62  subpattern name expected
842      63  digit expected after (?+
843      64  ] is an invalid data character in JavaScript compatibility mode
844      65  different names for subpatterns of the same number are
845            not allowed
846      66  (*MARK) must have an argument
847      67  this version of PCRE is not compiled with PCRE_UCP support
848      68  \ec must be followed by an ASCII character
849      69  \ek is not followed by a braced, angle-bracketed, or quoted name
850    .sp
851    The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
852    be used if the limits were changed when PCRE was built.
853    .
854    .
855    .\" HTML <a name="studyingapattern"></a>
856    .SH "STUDYING A PATTERN"
857  .rs  .rs
858  .sp  .sp
859  .B pcre_extra *pcre_study(const pcre *\fIcode\fR, int \fIoptions\fR,  .B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP
860  .ti +5n  .ti +5n
861  .B const char **\fIerrptr\fR);  .B const char **\fIerrptr\fP);
862  .PP  .PP
863  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
864  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
865  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
866  argument. If studing the pattern produces additional information that will help  argument. If studying the pattern produces additional information that will
867  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
868  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
869    results of the study.
870  The returned value from a \fBpcre_study()\fR can be passed directly to  .P
871  \fBpcre_exec()\fR. However, the \fBpcre_extra\fR block also contains other  The returned value from \fBpcre_study()\fP can be passed directly to
872  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
873  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
874  information, \fBpcre_study()\fR returns NULL. In that circumstance, if the  passed; these are described
875  calling program wants to pass some of the other fields to \fBpcre_exec()\fR, it  .\" HTML <a href="#extradata">
876  must set up its own \fBpcre_extra\fR block.  .\" </a>
877    below
878  The second argument contains option bits. At present, no options are defined  .\"
879  for \fBpcre_study()\fR, and this argument should always be zero.  in the section on matching a pattern.
880    .P
881  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,
882    \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program
883    wants to pass any of the other fields to \fBpcre_exec()\fP or
884    \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block.
885    .P
886    The second argument of \fBpcre_study()\fP contains option bits. There is only
887    one option: PCRE_STUDY_JIT_COMPILE. If this is set, and the just-in-time
888    compiler is available, the pattern is further compiled into machine code that
889    executes much faster than the \fBpcre_exec()\fP matching function. If
890    the just-in-time compiler is not available, this option is ignored. All other
891    bits in the \fIoptions\fP argument must be zero.
892    .P
893    JIT compilation is a heavyweight optimization. It can take some time for
894    patterns to be analyzed, and for one-off matches and simple patterns the
895    benefit of faster execution might be offset by a much slower study time.
896    Not all patterns can be optimized by the JIT compiler. For those that cannot be
897    handled, matching automatically falls back to the \fBpcre_exec()\fP
898    interpreter. For more details, see the
899    .\" HREF
900    \fBpcrejit\fP
901    .\"
902    documentation.
903    .P
904    The third argument for \fBpcre_study()\fP is a pointer for an error message. If
905  studying succeeds (even if no data is returned), the variable it points to is  studying succeeds (even if no data is returned), the variable it points to is
906  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
907  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
908  be sure that it has run successfully.  should test the error pointer for NULL after calling \fBpcre_study()\fP, to be
909    sure that it has run successfully.
910  This is a typical call to \fBpcre_study\fR():  .P
911    When you are finished with a pattern, you can free the memory used for the
912    pcre_extra *pe;  study data by calling \fBpcre_free_study()\fP. This function was added to the
913    pe = pcre_study(  API for release 8.20. For earlier versions, the memory could be freed with
914    \fBpcre_free()\fP, just like the pattern itself. This will still work in cases
915    where PCRE_STUDY_JIT_COMPILE is not used, but it is advisable to change to the
916    new function when convenient.
917    .P
918    This is a typical way in which \fBpcre_study\fP() is used (except that in a
919    real application there should be tests for errors):
920    .sp
921      int rc;
922      pcre *re;
923      pcre_extra *sd;
924      re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
925      sd = pcre_study(
926      re,             /* result of pcre_compile() */      re,             /* result of pcre_compile() */
927      0,              /* no options exist */      0,              /* no options */
928      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
929      rc = pcre_exec(   /* see below for details of pcre_exec() options */
930  At present, studying a pattern is useful only for non-anchored patterns that do      re, sd, "subject", 7, 0, 0, ovector, 30);
931  not have a single fixed starting character. A bitmap of possible starting    ...
932  characters is created.    pcre_free_study(sd);
933      pcre_free(re);
934    .sp
935    Studying a pattern does two things: first, a lower bound for the length of
936    subject string that is needed to match the pattern is computed. This does not
937    mean that there are any strings of that length that match, but it does
938    guarantee that no shorter strings match. The value is used by
939    \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP to avoid wasting time by trying to
940    match strings that are shorter than the lower bound. You can find out the value
941    in a calling program via the \fBpcre_fullinfo()\fP function.
942    .P
943    Studying a pattern is also useful for non-anchored patterns that do not have a
944    single fixed starting character. A bitmap of possible starting bytes is
945    created. This speeds up finding a position in the subject at which to start
946    matching.
947    .P
948    These two optimizations apply to both \fBpcre_exec()\fP and
949    \fBpcre_dfa_exec()\fP. However, they are not used by \fBpcre_exec()\fP if
950    \fBpcre_study()\fP is called with the PCRE_STUDY_JIT_COMPILE option, and
951    just-in-time compiling is successful. The optimizations can be disabled by
952    setting the PCRE_NO_START_OPTIMIZE option when calling \fBpcre_exec()\fP or
953    \fBpcre_dfa_exec()\fP. You might want to do this if your pattern contains
954    callouts or (*MARK) (which cannot be handled by the JIT compiler), and you want
955    to make use of these facilities in cases where matching fails. See the
956    discussion of PCRE_NO_START_OPTIMIZE
957    .\" HTML <a href="#execoptions">
958    .\" </a>
959    below.
960    .\"
961    .
962    .
963  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
964  .SH LOCALE SUPPORT  .SH "LOCALE SUPPORT"
965  .rs  .rs
966  .sp  .sp
967  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters,
968  digits, or whatever, by reference to a set of tables. When running in UTF-8  digits, or whatever, by reference to a set of tables, indexed by character
969  mode, this applies only to characters with codes less than 256. The library  value. When running in UTF-8 mode, this applies only to characters with codes
970  contains a default set of tables that is created in the default C locale when  less than 128. By default, higher-valued codes never match escapes such as \ew
971  PCRE is compiled. This is used when the final argument of \fBpcre_compile()\fR  or \ed, but they can be tested with \ep if PCRE is built with Unicode character
972  is NULL, and is sufficient for many applications.  property support. Alternatively, the PCRE_UCP option can be set at compile
973    time; this causes \ew and friends to use Unicode property support instead of
974  An alternative set of tables can, however, be supplied. Such tables are built  built-in tables. The use of locales with Unicode is discouraged. If you are
975  by calling the \fBpcre_maketables()\fR function, which has no arguments, in the  handling characters with codes greater than 128, you should either use UTF-8
976  relevant locale. The result can then be passed to \fBpcre_compile()\fR as often  and Unicode, or use locales, but not try to mix the two.
977  as necessary. For example, to build and use tables that are appropriate for the  .P
978  French locale (where accented characters with codes greater than 128 are  PCRE contains an internal set of tables that are used when the final argument
979  treated as letters), the following code could be used:  of \fBpcre_compile()\fP is NULL. These are sufficient for many applications.
980    Normally, the internal tables recognize only ASCII characters. However, when
981    setlocale(LC_CTYPE, "fr");  PCRE is built, it is possible to cause the internal tables to be rebuilt in the
982    default "C" locale of the local system, which may cause them to be different.
983    .P
984    The internal tables can always be overridden by tables supplied by the
985    application that calls PCRE. These may be created in a different locale from
986    the default. As more and more applications change to using Unicode, the need
987    for this locale support is expected to die away.
988    .P
989    External tables are built by calling the \fBpcre_maketables()\fP function,
990    which has no arguments, in the relevant locale. The result can then be passed
991    to \fBpcre_compile()\fP or \fBpcre_exec()\fP as often as necessary. For
992    example, to build and use tables that are appropriate for the French locale
993    (where accented characters with values greater than 128 are treated as letters),
994    the following code could be used:
995    .sp
996      setlocale(LC_CTYPE, "fr_FR");
997    tables = pcre_maketables();    tables = pcre_maketables();
998    re = pcre_compile(..., tables);    re = pcre_compile(..., tables);
999    .sp
1000  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
1001  pointer that is passed to \fBpcre_compile\fR is saved with the compiled  are using Windows, the name for the French locale is "french".
1002  pattern, and the same tables are used via this pointer by \fBpcre_study()\fR  .P
1003  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
1004  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
1005  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
1006  memory containing the tables remains available for as long as it is needed.  needed.
1007    .P
1008  .SH INFORMATION ABOUT A PATTERN  The pointer that is passed to \fBpcre_compile()\fP is saved with the compiled
1009    pattern, and the same tables are used via this pointer by \fBpcre_study()\fP
1010    and normally also by \fBpcre_exec()\fP. Thus, by default, for any single
1011    pattern, compilation, studying and matching all happen in the same locale, but
1012    different patterns can be compiled in different locales.
1013    .P
1014    It is possible to pass a table pointer or NULL (indicating the use of the
1015    internal tables) to \fBpcre_exec()\fP. Although not intended for this purpose,
1016    this facility could be used to match a pattern in a different locale from the
1017    one in which it was compiled. Passing table pointers at run time is discussed
1018    below in the section on matching a pattern.
1019    .
1020    .
1021    .\" HTML <a name="infoaboutpattern"></a>
1022    .SH "INFORMATION ABOUT A PATTERN"
1023  .rs  .rs
1024  .sp  .sp
1025  .B int pcre_fullinfo(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"  .B int pcre_fullinfo(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
1026  .ti +5n  .ti +5n
1027  .B int \fIwhat\fR, void *\fIwhere\fR);  .B int \fIwhat\fP, void *\fIwhere\fP);
1028  .PP  .PP
1029  The \fBpcre_fullinfo()\fR function returns information about a compiled  The \fBpcre_fullinfo()\fP function returns information about a compiled
1030  pattern. It replaces the obsolete \fBpcre_info()\fR function, which is  pattern. It replaces the obsolete \fBpcre_info()\fP function, which is
1031  nevertheless retained for backwards compability (and is documented below).  nevertheless retained for backwards compability (and is documented below).
1032    .P
1033  The first argument for \fBpcre_fullinfo()\fR is a pointer to the compiled  The first argument for \fBpcre_fullinfo()\fP is a pointer to the compiled
1034  pattern. The second argument is the result of \fBpcre_study()\fR, or NULL if  pattern. The second argument is the result of \fBpcre_study()\fP, or NULL if
1035  the pattern was not studied. The third argument specifies which piece of  the pattern was not studied. The third argument specifies which piece of
1036  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
1037  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
1038  the following negative numbers:  the following negative numbers:
1039    .sp
1040    PCRE_ERROR_NULL       the argument \fIcode\fR was NULL    PCRE_ERROR_NULL       the argument \fIcode\fP was NULL
1041                          the argument \fIwhere\fR was NULL                          the argument \fIwhere\fP was NULL
1042    PCRE_ERROR_BADMAGIC   the "magic number" was not found    PCRE_ERROR_BADMAGIC   the "magic number" was not found
1043    PCRE_ERROR_BADOPTION  the value of \fIwhat\fR was invalid    PCRE_ERROR_BADOPTION  the value of \fIwhat\fP was invalid
1044    .sp
1045  Here is a typical call of \fBpcre_fullinfo()\fR, to obtain the length of the  The "magic number" is placed at the start of each compiled pattern as an simple
1046  compiled pattern:  check against passing an arbitrary memory pointer. Here is a typical call of
1047    \fBpcre_fullinfo()\fP, to obtain the length of the compiled pattern:
1048    .sp
1049    int rc;    int rc;
1050    unsigned long int length;    size_t length;
1051    rc = pcre_fullinfo(    rc = pcre_fullinfo(
1052      re,               /* result of pcre_compile() */      re,               /* result of pcre_compile() */
1053      pe,               /* result of pcre_study(), or NULL */      sd,               /* result of pcre_study(), or NULL */
1054      PCRE_INFO_SIZE,   /* what is required */      PCRE_INFO_SIZE,   /* what is required */
1055      &length);         /* where to put the data */      &length);         /* where to put the data */
1056    .sp
1057  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
1058  as follows:  as follows:
1059    .sp
1060    PCRE_INFO_BACKREFMAX    PCRE_INFO_BACKREFMAX
1061    .sp
1062  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
1063  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
1064  no back references.  no back references.
1065    .sp
1066    PCRE_INFO_CAPTURECOUNT    PCRE_INFO_CAPTURECOUNT
1067    .sp
1068  Return the number of capturing subpatterns in the pattern. The fourth argument  Return the number of capturing subpatterns in the pattern. The fourth argument
1069  should point to an \fbint\fR variable.  should point to an \fBint\fP variable.
1070    .sp
1071      PCRE_INFO_DEFAULT_TABLES
1072    .sp
1073    Return a pointer to the internal default character tables within PCRE. The
1074    fourth argument should point to an \fBunsigned char *\fP variable. This
1075    information call is provided for internal use by the \fBpcre_study()\fP
1076    function. External callers can cause PCRE to use its internal tables by passing
1077    a NULL table pointer.
1078    .sp
1079    PCRE_INFO_FIRSTBYTE    PCRE_INFO_FIRSTBYTE
1080    .sp
1081  Return information about the first byte of any matched string, for a  Return information about the first byte of any matched string, for a
1082  non-anchored pattern. (This option used to be called PCRE_INFO_FIRSTCHAR; the  non-anchored pattern. The fourth argument should point to an \fBint\fP
1083  old name is still recognized for backwards compatibility.)  variable. (This option used to be called PCRE_INFO_FIRSTCHAR; the old name is
1084    still recognized for backwards compatibility.)
1085  If there is a fixed first byte, e.g. from a pattern such as (cat|cow|coyote),  .P
1086  it is returned in the integer pointed to by \fIwhere\fR. Otherwise, if either  If there is a fixed first byte, for example, from a pattern such as
1087    (cat|cow|coyote), its value is returned. Otherwise, if either
1088    .sp
1089  (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
1090  starts with "^", or  starts with "^", or
1091    .sp
1092  (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
1093  (if it were set, the pattern would be anchored),  (if it were set, the pattern would be anchored),
1094    .sp
1095  -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
1096  subject string or after any newline within the string. Otherwise -2 is  subject string or after any newline within the string. Otherwise -2 is
1097  returned. For anchored patterns, -2 is returned.  returned. For anchored patterns, -2 is returned.
1098    .sp
1099    PCRE_INFO_FIRSTTABLE    PCRE_INFO_FIRSTTABLE
1100    .sp
1101  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
1102  table indicating a fixed set of bytes for the first byte in any matching  table indicating a fixed set of bytes for the first byte in any matching
1103  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
1104  fourth argument should point to an \fBunsigned char *\fR variable.  fourth argument should point to an \fBunsigned char *\fP variable.
1105    .sp
1106      PCRE_INFO_HASCRORLF
1107    .sp
1108    Return 1 if the pattern contains any explicit matches for CR or LF characters,
1109    otherwise 0. The fourth argument should point to an \fBint\fP variable. An
1110    explicit match is either a literal CR or LF character, or \er or \en.
1111    .sp
1112      PCRE_INFO_JCHANGED
1113    .sp
1114    Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise
1115    0. The fourth argument should point to an \fBint\fP variable. (?J) and
1116    (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
1117    .sp
1118      PCRE_INFO_JIT
1119    .sp
1120    Return 1 if the pattern was studied with the PCRE_STUDY_JIT_COMPILE option, and
1121    just-in-time compiling was successful. The fourth argument should point to an
1122    \fBint\fP variable. A return value of 0 means that JIT support is not available
1123    in this version of PCRE, or that the pattern was not studied with the
1124    PCRE_STUDY_JIT_COMPILE option, or that the JIT compiler could not handle this
1125    particular pattern. See the
1126    .\" HREF
1127    \fBpcrejit\fP
1128    .\"
1129    documentation for details of what can and cannot be handled.
1130    .sp
1131    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
1132    .sp
1133  For a non-anchored pattern, return the value of the rightmost literal byte  Return the value of the rightmost literal byte that must exist in any matched
1134  which must exist in any matched string, other than at its start. The fourth  string, other than at its start, if such a byte has been recorded. The fourth
1135  argument should point to an \fBint\fR variable. If there is no such byte, or if  argument should point to an \fBint\fP variable. If there is no such byte, -1 is
1136  the pattern is anchored, -1 is returned. For example, for the pattern  returned. For anchored patterns, a last literal byte is recorded only if it
1137  /a\\d+z\\d+/ the returned value is 'z'.  follows something of variable length. For example, for the pattern
1138    /^a\ed+z\ed+/ the returned value is "z", but for /^a\edz\ed/ the returned value
1139    is -1.
1140    .sp
1141      PCRE_INFO_MINLENGTH
1142    .sp
1143    If the pattern was studied and a minimum length for matching subject strings
1144    was computed, its value is returned. Otherwise the returned value is -1. The
1145    value is a number of characters, not bytes (this may be relevant in UTF-8
1146    mode). The fourth argument should point to an \fBint\fP variable. A
1147    non-negative value is a lower bound to the length of any matching string. There
1148    may not be any strings of that length that do actually match, but every string
1149    that does match is at least that long.
1150    .sp
1151    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
1152    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
1153    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
1154    .sp
1155  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
1156  names are just an additional way of identifying the parentheses, which still  names are just an additional way of identifying the parentheses, which still
1157  acquire a number. A caller that wants to extract data from a named subpattern  acquire numbers. Several convenience functions such as
1158  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
1159  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
1160  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
1161  table for the pattern.  output vector (described with \fBpcre_exec()\fP below). To do the conversion,
1162    you need to use the name-to-number map, which is described by these three
1163    values.
1164    .P
1165  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
1166  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
1167  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
1168  length of the longest name. PCRE_INFO_NAMETABLE returns a pointer to the first  length of the longest name. PCRE_INFO_NAMETABLE returns a pointer to the first
1169  entry of the table (a pointer to \fBchar\fR). The first two bytes of each entry  entry of the table (a pointer to \fBchar\fP). The first two bytes of each entry
1170  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
1171  rest of the entry is the corresponding name, zero terminated. The names are in  rest of the entry is the corresponding name, zero terminated.
1172  alphabetical order. For example, consider the following pattern (assume  .P
1173  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  The names are in alphabetical order. Duplicate names may appear if (?| is used
1174    to create multiple groups with the same number, as described in the
1175    (?P<date> (?P<year>(\\d\\d)?\\d\\d) -  .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1176    (?P<month>\\d\\d) - (?P<day>\\d\\d) )  .\" </a>
1177    section on duplicate subpattern numbers
1178    .\"
1179    in the
1180    .\" HREF
1181    \fBpcrepattern\fP
1182    .\"
1183    page. Duplicate names for subpatterns with different numbers are permitted only
1184    if PCRE_DUPNAMES is set. In all cases of duplicate names, they appear in the
1185    table in the order in which they were found in the pattern. In the absence of
1186    (?| this is the order of increasing number; when (?| is used this is not
1187    necessarily the case because later subpatterns may have lower numbers.
1188    .P
1189    As a simple example of the name/number table, consider the following pattern
1190    (assume PCRE_EXTENDED is set, so white space - including newlines - is
1191    ignored):
1192    .sp
1193    .\" JOIN
1194      (?<date> (?<year>(\ed\ed)?\ed\ed) -
1195      (?<month>\ed\ed) - (?<day>\ed\ed) )
1196    .sp
1197  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
1198  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
1199  bytes shows in hex, and undefined bytes shown as ??:  bytes shows in hexadecimal, and undefined bytes shown as ??:
1200    .sp
1201    00 01 d  a  t  e  00 ??    00 01 d  a  t  e  00 ??
1202    00 05 d  a  y  00 ?? ??    00 05 d  a  y  00 ?? ??
1203    00 04 m  o  n  t  h  00    00 04 m  o  n  t  h  00
1204    00 02 y  e  a  r  00 ??    00 02 y  e  a  r  00 ??
1205    .sp
1206  When writing code to extract data from named subpatterns, remember that the  When writing code to extract data from named subpatterns using the
1207  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
1208    different for each compiled pattern.
1209    .sp
1210      PCRE_INFO_OKPARTIAL
1211    .sp
1212    Return 1 if the pattern can be used for partial matching with
1213    \fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
1214    \fBint\fP variable. From release 8.00, this always returns 1, because the
1215    restrictions that previously applied to partial matching have been lifted. The
1216    .\" HREF
1217    \fBpcrepartial\fP
1218    .\"
1219    documentation gives details of partial matching.
1220    .sp
1221    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1222    .sp
1223  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
1224  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
1225  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
1226  top-level option settings within the pattern itself.  top-level option settings at the start of the pattern itself. In other words,
1227    they are the options that will be in force when matching starts. For example,
1228    if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED option, the
1229    result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED.
1230    .P
1231  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
1232  alternatives begin with one of the following:  alternatives begin with one of the following:
1233    .sp
1234    ^     unless PCRE_MULTILINE is set    ^     unless PCRE_MULTILINE is set
1235    \\A    always    \eA    always
1236    \\G    always    \eG    always
1237    .\" JOIN
1238    .*    if PCRE_DOTALL is set and there are no back    .*    if PCRE_DOTALL is set and there are no back
1239            references to the subpattern in which .* appears            references to the subpattern in which .* appears
1240    .sp
1241  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
1242  \fBpcre_fullinfo()\fR.  \fBpcre_fullinfo()\fP.
1243    .sp
1244    PCRE_INFO_SIZE    PCRE_INFO_SIZE
1245    .sp
1246  Return the size of the compiled pattern, that is, the value that was passed as  Return the size of the compiled pattern, that is, the value that was passed as
1247  the argument to \fBpcre_malloc()\fR when PCRE was getting memory in which to  the argument to \fBpcre_malloc()\fP when PCRE was getting memory in which to
1248  place the compiled data. The fourth argument should point to a \fBsize_t\fR  place the compiled data. The fourth argument should point to a \fBsize_t\fP
1249  variable.  variable.
1250    .sp
1251    PCRE_INFO_STUDYSIZE    PCRE_INFO_STUDYSIZE
1252    .sp
1253  Returns the size of the data block pointed to by the \fIstudy_data\fR field in  Return the size of the data block pointed to by the \fIstudy_data\fP field in a
1254  a \fBpcre_extra\fR block. That is, it is the value that was passed to  \fBpcre_extra\fP block. If \fBpcre_extra\fP is NULL, or there is no study data,
1255  \fBpcre_malloc()\fR when PCRE was getting memory into which to place the data  zero is returned. The fourth argument should point to a \fBsize_t\fP variable.
1256  created by \fBpcre_study()\fR. The fourth argument should point to a  The \fIstudy_data\fP field is set by \fBpcre_study()\fP to record information
1257  \fBsize_t\fR variable.  that will speed up matching (see the section entitled
1258    .\" HTML <a href="#studyingapattern">
1259  .SH OBSOLETE INFO FUNCTION  .\" </a>
1260    "Studying a pattern"
1261    .\"
1262    above). The format of the \fIstudy_data\fP block is private, but its length
1263    is made available via this option so that it can be saved and restored (see the
1264    .\" HREF
1265    \fBpcreprecompile\fP
1266    .\"
1267    documentation for details).
1268    .
1269    .
1270    .SH "OBSOLETE INFO FUNCTION"
1271  .rs  .rs
1272  .sp  .sp
1273  .B int pcre_info(const pcre *\fIcode\fR, int *\fIoptptr\fR, int  .B int pcre_info(const pcre *\fIcode\fP, int *\fIoptptr\fP, int
1274  .B *\fIfirstcharptr\fR);  .B *\fIfirstcharptr\fP);
1275  .PP  .PP
1276  The \fBpcre_info()\fR function is now obsolete because its interface is too  The \fBpcre_info()\fP function is now obsolete because its interface is too
1277  restrictive to return all the available data about a compiled pattern. New  restrictive to return all the available data about a compiled pattern. New
1278  programs should use \fBpcre_fullinfo()\fR instead. The yield of  programs should use \fBpcre_fullinfo()\fP instead. The yield of
1279  \fBpcre_info()\fR is the number of capturing subpatterns, or one of the  \fBpcre_info()\fP is the number of capturing subpatterns, or one of the
1280  following negative numbers:  following negative numbers:
1281    .sp
1282    PCRE_ERROR_NULL       the argument \fIcode\fR was NULL    PCRE_ERROR_NULL       the argument \fIcode\fP was NULL
1283    PCRE_ERROR_BADMAGIC   the "magic number" was not found    PCRE_ERROR_BADMAGIC   the "magic number" was not found
1284    .sp
1285  If the \fIoptptr\fR argument is not NULL, a copy of the options with which the  If the \fIoptptr\fP argument is not NULL, a copy of the options with which the
1286  pattern was compiled is placed in the integer it points to (see  pattern was compiled is placed in the integer it points to (see
1287  PCRE_INFO_OPTIONS above).  PCRE_INFO_OPTIONS above).
1288    .P
1289  If the pattern is not anchored and the \fIfirstcharptr\fR argument is not NULL,  If the pattern is not anchored and the \fIfirstcharptr\fP argument is not NULL,
1290  it is used to pass back information about the first character of any matched  it is used to pass back information about the first character of any matched
1291  string (see PCRE_INFO_FIRSTBYTE above).  string (see PCRE_INFO_FIRSTBYTE above).
1292    .
1293  .SH MATCHING A PATTERN  .
1294    .SH "REFERENCE COUNTS"
1295    .rs
1296    .sp
1297    .B int pcre_refcount(pcre *\fIcode\fP, int \fIadjust\fP);
1298    .PP
1299    The \fBpcre_refcount()\fP function is used to maintain a reference count in the
1300    data block that contains a compiled pattern. It is provided for the benefit of
1301    applications that operate in an object-oriented manner, where different parts
1302    of the application may be using the same compiled pattern, but you want to free
1303    the block when they are all done.
1304    .P
1305    When a pattern is compiled, the reference count field is initialized to zero.
1306    It is changed only by calling this function, whose action is to add the
1307    \fIadjust\fP value (which may be positive or negative) to it. The yield of the
1308    function is the new value. However, the value of the count is constrained to
1309    lie between 0 and 65535, inclusive. If the new value is outside these limits,
1310    it is forced to the appropriate limit value.
1311    .P
1312    Except when it is zero, the reference count is not correctly preserved if a
1313    pattern is compiled on one host and then transferred to a host whose byte-order
1314    is different. (This seems a highly unlikely scenario.)
1315    .
1316    .
1317    .SH "MATCHING A PATTERN: THE TRADITIONAL FUNCTION"
1318  .rs  .rs
1319  .sp  .sp
1320  .B int pcre_exec(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"  .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
1321  .ti +5n  .ti +5n
1322  .B "const char *\fIsubject\fR," int \fIlength\fR, int \fIstartoffset\fR,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
1323  .ti +5n  .ti +5n
1324  .B int \fIoptions\fR, int *\fIovector\fR, int \fIovecsize\fR);  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
1325  .PP  .P
1326  The function \fBpcre_exec()\fR is called to match a subject string against a  The function \fBpcre_exec()\fP is called to match a subject string against a
1327  pre-compiled pattern, which is passed in the \fIcode\fR argument. If the  compiled pattern, which is passed in the \fIcode\fP argument. If the
1328  pattern has been studied, the result of the study should be passed in the  pattern was studied, the result of the study should be passed in the
1329  \fIextra\fR argument.  \fIextra\fP argument. This function is the main matching facility of the
1330    library, and it operates in a Perl-like manner. For specialist use there is
1331  Here is an example of a simple call to \fBpcre_exec()\fR:  also an alternative matching function, which is described
1332    .\" HTML <a href="#dfamatch">
1333    .\" </a>
1334    below
1335    .\"
1336    in the section about the \fBpcre_dfa_exec()\fP function.
1337    .P
1338    In most applications, the pattern will have been compiled (and optionally
1339    studied) in the same process that calls \fBpcre_exec()\fP. However, it is
1340    possible to save compiled patterns and study data, and then use them later
1341    in different processes, possibly even on different hosts. For a discussion
1342    about this, see the
1343    .\" HREF
1344    \fBpcreprecompile\fP
1345    .\"
1346    documentation.
1347    .P
1348    Here is an example of a simple call to \fBpcre_exec()\fP:
1349    .sp
1350    int rc;    int rc;
1351    int ovector[30];    int ovector[30];
1352    rc = pcre_exec(    rc = pcre_exec(
# Line 645  Here is an example of a simple call to \ Line 1356  Here is an example of a simple call to \
1356      11,             /* the length of the subject string */      11,             /* the length of the subject string */
1357      0,              /* start at offset 0 in the subject */      0,              /* start at offset 0 in the subject */
1358      0,              /* default options */      0,              /* default options */
1359      ovector,        /* vector for substring information */      ovector,        /* vector of integers for substring information */
1360      30);            /* number of elements in the vector */      30);            /* number of elements (NOT size in bytes) */
1361    .
1362  If the \fIextra\fR argument is not NULL, it must point to a \fBpcre_extra\fR  .
1363  data block. The \fBpcre_study()\fR function returns such a block (when it  .\" HTML <a name="extradata"></a>
1364    .SS "Extra data for \fBpcre_exec()\fR"
1365    .rs
1366    .sp
1367    If the \fIextra\fP argument is not NULL, it must point to a \fBpcre_extra\fP
1368    data block. The \fBpcre_study()\fP function returns such a block (when it
1369  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
1370  additional information in it. The fields in the block are as follows:  additional information in it. The \fBpcre_extra\fP block contains the following
1371    fields (not necessarily in this order):
1372    unsigned long int \fIflags\fR;  .sp
1373    void *\fIstudy_data\fR;    unsigned long int \fIflags\fP;
1374    unsigned long int \fImatch_limit\fR;    void *\fIstudy_data\fP;
1375    void *\fIcallout_data\fR;    void *\fIexecutable_jit\fP;
1376      unsigned long int \fImatch_limit\fP;
1377  The \fIflags\fR field is a bitmap that specifies which of the other fields    unsigned long int \fImatch_limit_recursion\fP;
1378      void *\fIcallout_data\fP;
1379      const unsigned char *\fItables\fP;
1380      unsigned char **\fImark\fP;
1381    .sp
1382    The \fIflags\fP field is a bitmap that specifies which of the other fields
1383  are set. The flag bits are:  are set. The flag bits are:
1384    .sp
1385    PCRE_EXTRA_STUDY_DATA    PCRE_EXTRA_STUDY_DATA
1386      PCRE_EXTRA_EXECUTABLE_JIT
1387    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1388      PCRE_EXTRA_MATCH_LIMIT_RECURSION
1389    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1390      PCRE_EXTRA_TABLES
1391  Other flag bits should be set to zero. The \fIstudy_data\fR field is set in the    PCRE_EXTRA_MARK
1392  \fBpcre_extra\fR block that is returned by \fBpcre_study()\fR, together with  .sp
1393  the appropriate flag bit. You should not set this yourself, but you can add to  Other flag bits should be set to zero. The \fIstudy_data\fP field and sometimes
1394  the block by setting the other fields.  the \fIexecutable_jit\fP field are set in the \fBpcre_extra\fP block that is
1395    returned by \fBpcre_study()\fP, together with the appropriate flag bits. You
1396  The \fImatch_limit\fR field provides a means of preventing PCRE from using up a  should not set these yourself, but you may add to the block by setting the
1397    other fields and their corresponding flag bits.
1398    .P
1399    The \fImatch_limit\fP field provides a means of preventing PCRE from using up a
1400  vast amount of resources when running patterns that are not going to match,  vast amount of resources when running patterns that are not going to match,
1401  but which have a very large number of possibilities in their search trees. The  but which have a very large number of possibilities in their search trees. The
1402  classic example is the use of nested unlimited repeats. Internally, PCRE uses a  classic example is a pattern that uses nested unlimited repeats.
1403  function called \fBmatch()\fR which it calls repeatedly (sometimes  .P
1404  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
1405  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
1406  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
1407  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
1408    patterns that are not anchored, the count restarts from zero for each position
1409  The default limit for the library can be set when PCRE is built; the default  in the subject string.
1410    .P
1411    When \fBpcre_exec()\fP is called with a pattern that was successfully studied
1412    with the PCRE_STUDY_JIT_COMPILE option, the way that the matching is executed
1413    is entirely different. However, there is still the possibility of runaway
1414    matching that goes on for a very long time, and so the \fImatch_limit\fP value
1415    is also used in this case (but in a different way) to limit how long the
1416    matching can continue.
1417    .P
1418    The default value for the limit can be set when PCRE is built; the default
1419  default is 10 million, which handles all but the most extreme cases. You can  default is 10 million, which handles all but the most extreme cases. You can
1420  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
1421  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
1422  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
1423  exceeded, \fBpcre_exec()\fR returns PCRE_ERROR_MATCHLIMIT.  PCRE_ERROR_MATCHLIMIT.
1424    .P
1425  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
1426  which is described in the \fBpcrecallout\fR documentation.  instead of limiting the total number of times that \fBmatch()\fP is called, it
1427    limits the depth of recursion. The recursion depth is a smaller number than the
1428  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.
1429  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.
1430  first matching position. However, if a pattern was compiled with PCRE_ANCHORED,  .P
1431  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
1432  unachored at matching time.  used, or, when PCRE has been compiled to use memory on the heap instead of the
1433    stack, the amount of heap memory that can be used. This limit is relevant, and
1434  There are also three further options that can be set only at matching time:  is ignored, when the pattern was successfully studied with
1435    PCRE_STUDY_JIT_COMPILE.
1436    .P
1437    The default value for \fImatch_limit_recursion\fP can be set when PCRE is
1438    built; the default default is the same value as the default for
1439    \fImatch_limit\fP. You can override the default by suppling \fBpcre_exec()\fP
1440    with a \fBpcre_extra\fP block in which \fImatch_limit_recursion\fP is set, and
1441    PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the \fIflags\fP field. If the limit
1442    is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1443    .P
1444    The \fIcallout_data\fP field is used in conjunction with the "callout" feature,
1445    and is described in the
1446    .\" HREF
1447    \fBpcrecallout\fP
1448    .\"
1449    documentation.
1450    .P
1451    The \fItables\fP field is used to pass a character tables pointer to
1452    \fBpcre_exec()\fP; this overrides the value that is stored with the compiled
1453    pattern. A non-NULL value is stored with the compiled pattern only if custom
1454    tables were supplied to \fBpcre_compile()\fP via its \fItableptr\fP argument.
1455    If NULL is passed to \fBpcre_exec()\fP using this mechanism, it forces PCRE's
1456    internal tables to be used. This facility is helpful when re-using patterns
1457    that have been saved after compiling with an external set of tables, because
1458    the external tables might be at a different address when \fBpcre_exec()\fP is
1459    called. See the
1460    .\" HREF
1461    \fBpcreprecompile\fP
1462    .\"
1463    documentation for a discussion of saving compiled patterns for later use.
1464    .P
1465    If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1466    be set to point to a \fBchar *\fP variable. If the pattern contains any
1467    backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1468    a name to pass back, a pointer to the name string (zero terminated) is placed
1469    in the variable pointed to by the \fImark\fP field. The names are within the
1470    compiled pattern; if you wish to retain such a name you must copy it before
1471    freeing the memory of a compiled pattern. If there is no name to pass back, the
1472    variable pointed to by the \fImark\fP field set to NULL. For details of the
1473    backtracking control verbs, see the section entitled
1474    .\" HTML <a href="pcrepattern#backtrackcontrol">
1475    .\" </a>
1476    "Backtracking control"
1477    .\"
1478    in the
1479    .\" HREF
1480    \fBpcrepattern\fP
1481    .\"
1482    documentation.
1483    .
1484    .
1485    .\" HTML <a name="execoptions"></a>
1486    .SS "Option bits for \fBpcre_exec()\fP"
1487    .rs
1488    .sp
1489    The unused bits of the \fIoptions\fP argument for \fBpcre_exec()\fP must be
1490    zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
1491    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1492    PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
1493    PCRE_PARTIAL_HARD.
1494    .sp
1495      PCRE_ANCHORED
1496    .sp
1497    The PCRE_ANCHORED option limits \fBpcre_exec()\fP to matching at the first
1498    matching position. If a pattern was compiled with PCRE_ANCHORED, or turned out
1499    to be anchored by virtue of its contents, it cannot be made unachored at
1500    matching time.
1501    .sp
1502      PCRE_BSR_ANYCRLF
1503      PCRE_BSR_UNICODE
1504    .sp
1505    These options (which are mutually exclusive) control what the \eR escape
1506    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
1507    match any Unicode newline sequence. These options override the choice that was
1508    made or defaulted when the pattern was compiled.
1509    .sp
1510      PCRE_NEWLINE_CR
1511      PCRE_NEWLINE_LF
1512      PCRE_NEWLINE_CRLF
1513      PCRE_NEWLINE_ANYCRLF
1514      PCRE_NEWLINE_ANY
1515    .sp
1516    These options override the newline definition that was chosen or defaulted when
1517    the pattern was compiled. For details, see the description of
1518    \fBpcre_compile()\fP above. During matching, the newline choice affects the
1519    behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1520    the way the match position is advanced after a match failure for an unanchored
1521    pattern.
1522    .P
1523    When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a
1524    match attempt for an unanchored pattern fails when the current position is at a
1525    CRLF sequence, and the pattern contains no explicit matches for CR or LF
1526    characters, the match position is advanced by two characters instead of one, in
1527    other words, to after the CRLF.
1528    .P
1529    The above rule is a compromise that makes the most common cases work as
1530    expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
1531    set), it does not match the string "\er\enA" because, after failing at the
1532    start, it skips both the CR and the LF before retrying. However, the pattern
1533    [\er\en]A does match that string, because it contains an explicit CR or LF
1534    reference, and so advances only by one character after the first failure.
1535    .P
1536    An explicit match for CR of LF is either a literal appearance of one of those
1537    characters, or one of the \er or \en escape sequences. Implicit matches such as
1538    [^X] do not count, nor does \es (which includes CR and LF in the characters
1539    that it matches).
1540    .P
1541    Notwithstanding the above, anomalous effects may still occur when CRLF is a
1542    valid newline sequence and explicit \er or \en escapes appear in the pattern.
1543    .sp
1544    PCRE_NOTBOL    PCRE_NOTBOL
1545    .sp
1546  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
1547  circumflex metacharacter should not match before it. Setting this without  beginning of a line, so the circumflex metacharacter should not match before
1548  PCRE_MULTILINE (at compile time) causes circumflex never to match.  it. Setting this without PCRE_MULTILINE (at compile time) causes circumflex
1549    never to match. This option affects only the behaviour of the circumflex
1550    metacharacter. It does not affect \eA.
1551    .sp
1552    PCRE_NOTEOL    PCRE_NOTEOL
1553    .sp
1554  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
1555  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
1556  it. Setting this without PCRE_MULTILINE (at compile time) causes dollar never  mode) a newline immediately before it. Setting this without PCRE_MULTILINE (at
1557  to match.  compile time) causes dollar never to match. This option affects only the
1558    behaviour of the dollar metacharacter. It does not affect \eZ or \ez.
1559    .sp
1560    PCRE_NOTEMPTY    PCRE_NOTEMPTY
1561    .sp
1562  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
1563  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
1564  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
1565    .sp
1566    a?b?    a?b?
1567    .sp
1568  is applied to a string not beginning with "a" or "b", it matches the empty  is applied to a string not beginning with "a" or "b", it matches an empty
1569  string at the start of the subject. With PCRE_NOTEMPTY set, this match is not  string at the start of the subject. With PCRE_NOTEMPTY set, this match is not
1570  valid, so PCRE searches further into the string for occurrences of "a" or "b".  valid, so PCRE searches further into the string for occurrences of "a" or "b".
1571    .sp
1572  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case    PCRE_NOTEMPTY_ATSTART
1573  of a pattern match of the empty string within its \fBsplit()\fR function, and  .sp
1574  when using the /g modifier. It is possible to emulate Perl's behaviour after  This is like PCRE_NOTEMPTY, except that an empty string match that is not at
1575  matching a null string by first trying the match again at the same offset with  the start of the subject is permitted. If the pattern is anchored, such a match
1576  PCRE_NOTEMPTY set, and then if that fails by advancing the starting offset (see  can occur only if the pattern contains \eK.
1577  below) and trying an ordinary match again.  .P
1578    Perl has no direct equivalent of PCRE_NOTEMPTY or PCRE_NOTEMPTY_ATSTART, but it
1579  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
1580  \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
1581  \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
1582  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
1583  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
1584    ordinary match again. There is some code that demonstrates how to do this in
1585  If the pattern was compiled with the PCRE_UTF8 option, the subject must be a  the
1586  sequence of bytes that is a valid UTF-8 string. If an invalid UTF-8 string is  .\" HREF
1587  passed, PCRE's behaviour is not defined.  \fBpcredemo\fP
1588    .\"
1589    sample program. In the most general case, you have to check to see if the
1590    newline convention recognizes CRLF as a newline, and if so, and the current
1591    character is CR followed by LF, advance the starting offset by two characters
1592    instead of one.
1593    .sp
1594      PCRE_NO_START_OPTIMIZE
1595    .sp
1596    There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1597    a match, in order to speed up the process. For example, if it is known that an
1598    unanchored match must start with a specific character, it searches the subject
1599    for that character, and fails immediately if it cannot find it, without
1600    actually running the main matching function. This means that a special item
1601    such as (*COMMIT) at the start of a pattern is not considered until after a
1602    suitable starting point for the match has been found. When callouts or (*MARK)
1603    items are in use, these "start-up" optimizations can cause them to be skipped
1604    if the pattern is never actually used. The start-up optimizations are in effect
1605    a pre-scan of the subject that takes place before the pattern is run.
1606    .P
1607    The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
1608    causing performance to suffer, but ensuring that in cases where the result is
1609    "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
1610    are considered at every possible starting position in the subject string. If
1611    PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
1612    time.
1613    .P
1614    Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
1615    Consider the pattern
1616    .sp
1617      (*COMMIT)ABC
1618    .sp
1619    When this is compiled, PCRE records the fact that a match must start with the
1620    character "A". Suppose the subject string is "DEFABC". The start-up
1621    optimization scans along the subject, finds "A" and runs the first match
1622    attempt from there. The (*COMMIT) item means that the pattern must match the
1623    current starting position, which in this case, it does. However, if the same
1624    match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
1625    subject string does not happen. The first match attempt is run starting from
1626    "D" and when this fails, (*COMMIT) prevents any further matches being tried, so
1627    the overall result is "no match". If the pattern is studied, more start-up
1628    optimizations may be used. For example, a minimum length for the subject may be
1629    recorded. Consider the pattern
1630    .sp
1631      (*MARK:A)(X|Y)
1632    .sp
1633    The minimum length for a match is one character. If the subject is "ABC", there
1634    will be attempts to match "ABC", "BC", "C", and then finally an empty string.
1635    If the pattern is studied, the final attempt does not take place, because PCRE
1636    knows that the subject is too short, and so the (*MARK) is never encountered.
1637    In this case, studying the pattern does not affect the overall match result,
1638    which is still "no match", but it does affect the auxiliary information that is
1639    returned.
1640    .sp
1641      PCRE_NO_UTF8_CHECK
1642    .sp
1643    When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8
1644    string is automatically checked when \fBpcre_exec()\fP is subsequently called.
1645    The value of \fIstartoffset\fP is also checked to ensure that it points to the
1646    start of a UTF-8 character. There is a discussion about the validity of UTF-8
1647    strings in the
1648    .\" HTML <a href="pcre.html#utf8strings">
1649    .\" </a>
1650    section on UTF-8 support
1651    .\"
1652    in the main
1653    .\" HREF
1654    \fBpcre\fP
1655    .\"
1656    page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns
1657    the error PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is
1658    a truncated UTF-8 character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
1659    both cases, information about the precise nature of the error may also be
1660    returned (see the descriptions of these errors in the section entitled \fIError
1661    return values from\fP \fBpcre_exec()\fP
1662    .\" HTML <a href="#errorlist">
1663    .\" </a>
1664    below).
1665    .\"
1666    If \fIstartoffset\fP contains a value that does not point to the start of a
1667    UTF-8 character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
1668    returned.
1669    .P
1670    If you already know that your subject is valid, and you want to skip these
1671    checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when
1672    calling \fBpcre_exec()\fP. You might want to do this for the second and
1673    subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find
1674    all the matches in a single subject string. However, you should be sure that
1675    the value of \fIstartoffset\fP points to the start of a UTF-8 character (or the
1676    end of the subject). When PCRE_NO_UTF8_CHECK is set, the effect of passing an
1677    invalid UTF-8 string as a subject or an invalid value of \fIstartoffset\fP is
1678    undefined. Your program may crash.
1679    .sp
1680      PCRE_PARTIAL_HARD
1681      PCRE_PARTIAL_SOFT
1682    .sp
1683    These options turn on the partial matching feature. For backwards
1684    compatibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial match
1685    occurs if the end of the subject string is reached successfully, but there are
1686    not enough subject characters to complete the match. If this happens when
1687    PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set, matching continues by
1688    testing any remaining alternatives. Only if no complete match can be found is
1689    PCRE_ERROR_PARTIAL returned instead of PCRE_ERROR_NOMATCH. In other words,
1690    PCRE_PARTIAL_SOFT says that the caller is prepared to handle a partial match,
1691    but only if no complete match can be found.
1692    .P
1693    If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
1694    partial match is found, \fBpcre_exec()\fP immediately returns
1695    PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
1696    when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
1697    important that an alternative complete match.
1698    .P
1699    In both cases, the portion of the string that was inspected when the partial
1700    match was found is set as the first matching string. There is a more detailed
1701    discussion of partial and multi-segment matching, with examples, in the
1702    .\" HREF
1703    \fBpcrepartial\fP
1704    .\"
1705    documentation.
1706    .
1707    .
1708    .SS "The string to be matched by \fBpcre_exec()\fP"
1709    .rs
1710    .sp
1711    The subject string is passed to \fBpcre_exec()\fP as a pointer in
1712    \fIsubject\fP, a length (in bytes) in \fIlength\fP, and a starting byte offset
1713    in \fIstartoffset\fP. If this is negative or greater than the length of the
1714    subject, \fBpcre_exec()\fP returns PCRE_ERROR_BADOFFSET. When the starting
1715    offset is zero, the search for a match starts at the beginning of the subject,
1716    and this is by far the most common case. In UTF-8 mode, the byte offset must
1717    point to the start of a UTF-8 character (or the end of the subject). Unlike the
1718    pattern string, the subject may contain binary zero bytes.
1719    .P
1720  A non-zero starting offset is useful when searching for another match in the  A non-zero starting offset is useful when searching for another match in the
1721  same subject by calling \fBpcre_exec()\fR again after a previous success.  same subject by calling \fBpcre_exec()\fP again after a previous success.
1722  Setting \fIstartoffset\fR differs from just passing over a shortened string and  Setting \fIstartoffset\fP differs from just passing over a shortened string and
1723  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
1724  lookbehind. For example, consider the pattern  lookbehind. For example, consider the pattern
1725    .sp
1726    \\Biss\\B    \eBiss\eB
1727    .sp
1728  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
1729  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
1730  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
1731  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
1732  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
1733  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
1734  \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
1735  set to 4, it finds the second occurrence of "iss" because it is able to look  set to 4, it finds the second occurrence of "iss" because it is able to look
1736  behind the starting point to discover that it is preceded by a letter.  behind the starting point to discover that it is preceded by a letter.
1737    .P
1738    Finding all the matches in a subject is tricky when the pattern can match an
1739    empty string. It is possible to emulate Perl's /g behaviour by first trying the
1740    match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
1741    PCRE_ANCHORED options, and then if that fails, advancing the starting offset
1742    and trying an ordinary match again. There is some code that demonstrates how to
1743    do this in the
1744    .\" HREF
1745    \fBpcredemo\fP
1746    .\"
1747    sample program. In the most general case, you have to check to see if the
1748    newline convention recognizes CRLF as a newline, and if so, and the current
1749    character is CR followed by LF, advance the starting offset by two characters
1750    instead of one.
1751    .P
1752  If a non-zero starting offset is passed when the pattern is anchored, one  If a non-zero starting offset is passed when the pattern is anchored, one
1753  attempt to match at the given offset is tried. This can only succeed if the  attempt to match at the given offset is made. This can only succeed if the
1754  pattern does not require the match to be at the start of the subject.  pattern does not require the match to be at the start of the subject.
1755    .
1756    .
1757    .SS "How \fBpcre_exec()\fP returns captured substrings"
1758    .rs
1759    .sp
1760  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
1761  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
1762  pattern. Following the usage in Jeffrey Friedl's book, this is called  pattern. Following the usage in Jeffrey Friedl's book, this is called
1763  "capturing" in what follows, and the phrase "capturing subpattern" is used for  "capturing" in what follows, and the phrase "capturing subpattern" is used for
1764  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
1765  kinds of parenthesized subpattern that do not cause substrings to be captured.  kinds of parenthesized subpattern that do not cause substrings to be captured.
1766    .P
1767  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
1768  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
1769  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
1770  back captured substrings, each substring using a pair of integers. The  argument is NOT the size of \fIovector\fP in bytes.
1771  remaining third of the vector is used as workspace by \fBpcre_exec()\fR while  .P
1772  matching capturing subpatterns, and is not available for passing back  The first two-thirds of the vector is used to pass back captured substrings,
1773  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
1774  three. If it is not, it is rounded down.  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
1775    and is not available for passing back information. The number passed in
1776  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
1777  returned in pairs of integers, starting at the beginning of \fIovector\fR, and  rounded down.
1778  continuing up to two-thirds of its length at the most. The first element of a  .P
1779  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
1780  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
1781  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
1782  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
1783  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
1784  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
1785  subpatterns, the return value from a successful match is 1, indicating that  mode. They are not character counts.
1786  just the first pair of offsets has been set.  .P
1787    The first pair of integers, \fIovector[0]\fP and \fIovector[1]\fP, identify the
1788  Some convenience functions are provided for extracting the captured substrings  portion of the subject string matched by the entire pattern. The next pair is
1789  as separate strings. These are described in the following section.  used for the first capturing subpattern, and so on. The value returned by
1790    \fBpcre_exec()\fP is one more than the highest numbered pair that has been set.
1791  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
1792  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
1793  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.
1794  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.  
   
1795  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
1796  string that it matched that gets returned.  string that it matched that is returned.
1797    .P
1798  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
1799  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
1800  value of zero. In particular, if the substring offsets are not of interest,  returns a value of zero. If the substring offsets are not of interest,
1801  \fBpcre_exec()\fR may be called with \fIovector\fR passed as NULL and  \fBpcre_exec()\fP may be called with \fIovector\fP passed as NULL and
1802  \fIovecsize\fR as zero. However, if the pattern contains back references and  \fIovecsize\fP as zero. However, if the pattern contains back references and
1803  the \fIovector\fR isn't big enough to remember the related substrings, PCRE has  the \fIovector\fP is not big enough to remember the related substrings, PCRE
1804  to get additional memory for use during matching. Thus it is usually advisable  has to get additional memory for use during matching. Thus it is usually
1805  to supply an \fIovector\fR.  advisable to supply an \fIovector\fP.
1806    .P
1807  Note that \fBpcre_info()\fR can be used to find out how many capturing  The \fBpcre_fullinfo()\fP function can be used to find out how many capturing
1808  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1809  \fIovector\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
1810  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.
1811    .P
1812  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
1813    the subject when subpattern \fIn\fP has not been used at all. For example, if
1814    the string "abc" is matched against the pattern (a|(z))(bc) the return from the
1815    function is 4, and subpatterns 1 and 3 are matched, but 2 is not. When this
1816    happens, both values in the offset pairs corresponding to unused subpatterns
1817    are set to -1.
1818    .P
1819    Offset values that correspond to unused subpatterns at the end of the
1820    expression are also set to -1. For example, if the string "abc" is matched
1821    against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
1822    return from the function is 2, because the highest used capturing subpattern
1823    number is 1, and the offsets for for the second and third capturing subpatterns
1824    (assuming the vector is large enough, of course) are set to -1.
1825    .P
1826    \fBNote\fP: Elements of \fIovector\fP that do not correspond to capturing
1827    parentheses in the pattern are never changed. That is, if a pattern contains
1828    \fIn\fP capturing parentheses, no more than \fIovector[0]\fP to
1829    \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other elements retain
1830    whatever values they previously had.
1831    .P
1832    Some convenience functions are provided for extracting the captured substrings
1833    as separate strings. These are described below.
1834    .
1835    .
1836    .\" HTML <a name="errorlist"></a>
1837    .SS "Error return values from \fBpcre_exec()\fP"
1838    .rs
1839    .sp
1840    If \fBpcre_exec()\fP fails, it returns a negative number. The following are
1841  defined in the header file:  defined in the header file:
1842    .sp
1843    PCRE_ERROR_NOMATCH        (-1)    PCRE_ERROR_NOMATCH        (-1)
1844    .sp
1845  The subject string did not match the pattern.  The subject string did not match the pattern.
1846    .sp
1847    PCRE_ERROR_NULL           (-2)    PCRE_ERROR_NULL           (-2)
1848    .sp
1849  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
1850  NULL and \fIovecsize\fR was not zero.  NULL and \fIovecsize\fP was not zero.
1851    .sp
1852    PCRE_ERROR_BADOPTION      (-3)    PCRE_ERROR_BADOPTION      (-3)
1853    .sp
1854  An unrecognized bit was set in the \fIoptions\fR argument.  An unrecognized bit was set in the \fIoptions\fP argument.
1855    .sp
1856    PCRE_ERROR_BADMAGIC       (-4)    PCRE_ERROR_BADMAGIC       (-4)
1857    .sp
1858  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
1859  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
1860  magic number isn't present.  compiled in an environment of one endianness is run in an environment with the
1861    other endianness. This is the error that PCRE gives when the magic number is
1862    PCRE_ERROR_UNKNOWN_NODE   (-5)  not present.
1863    .sp
1864      PCRE_ERROR_UNKNOWN_OPCODE (-5)
1865    .sp
1866  While running the pattern match, an unknown item was encountered in the  While running the pattern match, an unknown item was encountered in the
1867  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
1868  of the compiled pattern.  of the compiled pattern.
1869    .sp
1870    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1871    .sp
1872  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
1873  \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
1874  gets a block of memory at the start of matching to use for this purpose. If the  gets a block of memory at the start of matching to use for this purpose. If the
1875  call via \fBpcre_malloc()\fR fails, this error is given. The memory is freed at  call via \fBpcre_malloc()\fP fails, this error is given. The memory is
1876  the end of matching.  automatically freed at the end of matching.
1877    .P
1878    This error is also given if \fBpcre_stack_malloc()\fP fails in
1879    \fBpcre_exec()\fP. This can happen only when PCRE has been compiled with
1880    \fB--disable-stack-for-recursion\fP.
1881    .sp
1882    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1883    .sp
1884  This error is used by the \fBpcre_copy_substring()\fR,  This error is used by the \fBpcre_copy_substring()\fP,
1885  \fBpcre_get_substring()\fR, and \fBpcre_get_substring_list()\fR functions (see  \fBpcre_get_substring()\fP, and \fBpcre_get_substring_list()\fP functions (see
1886  below). It is never returned by \fBpcre_exec()\fR.  below). It is never returned by \fBpcre_exec()\fP.
1887    .sp
1888    PCRE_ERROR_MATCHLIMIT     (-8)    PCRE_ERROR_MATCHLIMIT     (-8)
1889    .sp
1890  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
1891  field in a \fBpcre_extra\fR structure (or defaulted) was reached. See the  \fBpcre_extra\fP structure (or defaulted) was reached. See the description
1892  description above.  above.
1893    .sp
1894    PCRE_ERROR_CALLOUT        (-9)    PCRE_ERROR_CALLOUT        (-9)
1895    .sp
1896  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
1897  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
1898  \fBpcrecallout\fR documentation for details.  .\" HREF
1899    \fBpcrecallout\fP
1900  .SH EXTRACTING CAPTURED SUBSTRINGS BY NUMBER  .\"
1901    documentation for details.
1902    .sp
1903      PCRE_ERROR_BADUTF8        (-10)
1904    .sp
1905    A string that contains an invalid UTF-8 byte sequence was passed as a subject,
1906    and the PCRE_NO_UTF8_CHECK option was not set. If the size of the output vector
1907    (\fIovecsize\fP) is at least 2, the byte offset to the start of the the invalid
1908    UTF-8 character is placed in the first element, and a reason code is placed in
1909    the second element. The reason codes are listed in the
1910    .\" HTML <a href="#badutf8reasons">
1911    .\" </a>
1912    following section.
1913    .\"
1914    For backward compatibility, if PCRE_PARTIAL_HARD is set and the problem is a
1915    truncated UTF-8 character at the end of the subject (reason codes 1 to 5),
1916    PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
1917    .sp
1918      PCRE_ERROR_BADUTF8_OFFSET (-11)
1919    .sp
1920    The UTF-8 byte sequence that was passed as a subject was checked and found to
1921    be valid (the PCRE_NO_UTF8_CHECK option was not set), but the value of
1922    \fIstartoffset\fP did not point to the beginning of a UTF-8 character or the
1923    end of the subject.
1924    .sp
1925      PCRE_ERROR_PARTIAL        (-12)
1926    .sp
1927    The subject string did not match, but it did match partially. See the
1928    .\" HREF
1929    \fBpcrepartial\fP
1930    .\"
1931    documentation for details of partial matching.
1932    .sp
1933      PCRE_ERROR_BADPARTIAL     (-13)
1934    .sp
1935    This code is no longer in use. It was formerly returned when the PCRE_PARTIAL
1936    option was used with a compiled pattern containing items that were not
1937    supported for partial matching. From release 8.00 onwards, there are no
1938    restrictions on partial matching.
1939    .sp
1940      PCRE_ERROR_INTERNAL       (-14)
1941    .sp
1942    An unexpected internal error has occurred. This error could be caused by a bug
1943    in PCRE or by overwriting of the compiled pattern.
1944    .sp
1945      PCRE_ERROR_BADCOUNT       (-15)
1946    .sp
1947    This error is given if the value of the \fIovecsize\fP argument is negative.
1948    .sp
1949      PCRE_ERROR_RECURSIONLIMIT (-21)
1950    .sp
1951    The internal recursion limit, as specified by the \fImatch_limit_recursion\fP
1952    field in a \fBpcre_extra\fP structure (or defaulted) was reached. See the
1953    description above.
1954    .sp
1955      PCRE_ERROR_BADNEWLINE     (-23)
1956    .sp
1957    An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
1958    .sp
1959      PCRE_ERROR_BADOFFSET      (-24)
1960    .sp
1961    The value of \fIstartoffset\fP was negative or greater than the length of the
1962    subject, that is, the value in \fIlength\fP.
1963    .sp
1964      PCRE_ERROR_SHORTUTF8      (-25)
1965    .sp
1966    This error is returned instead of PCRE_ERROR_BADUTF8 when the subject string
1967    ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD option is set.
1968    Information about the failure is returned as for PCRE_ERROR_BADUTF8. It is in
1969    fact sufficient to detect this case, but this special error code for
1970    PCRE_PARTIAL_HARD precedes the implementation of returned information; it is
1971    retained for backwards compatibility.
1972    .sp
1973      PCRE_ERROR_RECURSELOOP    (-26)
1974    .sp
1975    This error is returned when \fBpcre_exec()\fP detects a recursion loop within
1976    the pattern. Specifically, it means that either the whole pattern or a
1977    subpattern has been called recursively for the second time at the same position
1978    in the subject string. Some simple patterns that might do this are detected and
1979    faulted at compile time, but more complicated cases, in particular mutual
1980    recursions between two different subpatterns, cannot be detected until run
1981    time.
1982    .sp
1983      PCRE_ERROR_JIT_STACKLIMIT (-27)
1984    .sp
1985    This error is returned when a pattern that was successfully studied using the
1986    PCRE_STUDY_JIT_COMPILE option is matched, but the memory available for the
1987    just-in-time processing stack is not large enough. See the
1988    .\" HREF
1989    \fBpcrejit\fP
1990    .\"
1991    documentation for more details.
1992    .P
1993    Error numbers -16 to -20 and -22 are not used by \fBpcre_exec()\fP.
1994    .
1995    .
1996    .\" HTML <a name="badutf8reasons"></a>
1997    .SS "Reason codes for invalid UTF-8 strings"
1998  .rs  .rs
1999  .sp  .sp
2000  .B int pcre_copy_substring(const char *\fIsubject\fR, int *\fIovector\fR,  When \fBpcre_exec()\fP returns either PCRE_ERROR_BADUTF8 or
2001    PCRE_ERROR_SHORTUTF8, and the size of the output vector (\fIovecsize\fP) is at
2002    least 2, the offset of the start of the invalid UTF-8 character is placed in
2003    the first output vector element (\fIovector[0]\fP) and a reason code is placed
2004    in the second element (\fIovector[1]\fP). The reason codes are given names in
2005    the \fBpcre.h\fP header file:
2006    .sp
2007      PCRE_UTF8_ERR1
2008      PCRE_UTF8_ERR2
2009      PCRE_UTF8_ERR3
2010      PCRE_UTF8_ERR4
2011      PCRE_UTF8_ERR5
2012    .sp
2013    The string ends with a truncated UTF-8 character; the code specifies how many
2014    bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8 characters to be
2015    no longer than 4 bytes, the encoding scheme (originally defined by RFC 2279)
2016    allows for up to 6 bytes, and this is checked first; hence the possibility of
2017    4 or 5 missing bytes.
2018    .sp
2019      PCRE_UTF8_ERR6
2020      PCRE_UTF8_ERR7
2021      PCRE_UTF8_ERR8
2022      PCRE_UTF8_ERR9
2023      PCRE_UTF8_ERR10
2024    .sp
2025    The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of the
2026    character do not have the binary value 0b10 (that is, either the most
2027    significant bit is 0, or the next bit is 1).
2028    .sp
2029      PCRE_UTF8_ERR11
2030      PCRE_UTF8_ERR12
2031    .sp
2032    A character that is valid by the RFC 2279 rules is either 5 or 6 bytes long;
2033    these code points are excluded by RFC 3629.
2034    .sp
2035      PCRE_UTF8_ERR13
2036    .sp
2037    A 4-byte character has a value greater than 0x10fff; these code points are
2038    excluded by RFC 3629.
2039    .sp
2040      PCRE_UTF8_ERR14
2041    .sp
2042    A 3-byte character has a value in the range 0xd800 to 0xdfff; this range of
2043    code points are reserved by RFC 3629 for use with UTF-16, and so are excluded
2044    from UTF-8.
2045    .sp
2046      PCRE_UTF8_ERR15
2047      PCRE_UTF8_ERR16
2048      PCRE_UTF8_ERR17
2049      PCRE_UTF8_ERR18
2050      PCRE_UTF8_ERR19
2051    .sp
2052    A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes for a
2053    value that can be represented by fewer bytes, which is invalid. For example,
2054    the two bytes 0xc0, 0xae give the value 0x2e, whose correct coding uses just
2055    one byte.
2056    .sp
2057      PCRE_UTF8_ERR20
2058    .sp
2059    The two most significant bits of the first byte of a character have the binary
2060    value 0b10 (that is, the most significant bit is 1 and the second is 0). Such a
2061    byte can only validly occur as the second or subsequent byte of a multi-byte
2062    character.
2063    .sp
2064      PCRE_UTF8_ERR21
2065    .sp
2066    The first byte of a character has the value 0xfe or 0xff. These values can
2067    never occur in a valid UTF-8 string.
2068    .
2069    .
2070    .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
2071    .rs
2072    .sp
2073    .B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\fP,
2074  .ti +5n  .ti +5n
2075  .B int \fIstringcount\fR, int \fIstringnumber\fR, char *\fIbuffer\fR,  .B int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP,
2076  .ti +5n  .ti +5n
2077  .B int \fIbuffersize\fR);  .B int \fIbuffersize\fP);
2078  .PP  .PP
2079  .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,  
2080  .ti +5n  .ti +5n
2081  .B int \fIstringcount\fR, int \fIstringnumber\fR,  .B int \fIstringcount\fP, int \fIstringnumber\fP,
2082  .ti +5n  .ti +5n
2083  .B const char **\fIstringptr\fR);  .B const char **\fIstringptr\fP);
2084  .PP  .PP
2085  .br  .B int pcre_get_substring_list(const char *\fIsubject\fP,
 .B int pcre_get_substring_list(const char *\fIsubject\fR,  
2086  .ti +5n  .ti +5n
2087  .B int *\fIovector\fR, int \fIstringcount\fR, "const char ***\fIlistptr\fR);"  .B int *\fIovector\fP, int \fIstringcount\fP, "const char ***\fIlistptr\fP);"
2088  .PP  .PP
2089  Captured substrings can be accessed directly by using the offsets returned by  Captured substrings can be accessed directly by using the offsets returned by
2090  \fBpcre_exec()\fR in \fIovector\fR. For convenience, the functions  \fBpcre_exec()\fP in \fIovector\fP. For convenience, the functions
2091  \fBpcre_copy_substring()\fR, \fBpcre_get_substring()\fR, and  \fBpcre_copy_substring()\fP, \fBpcre_get_substring()\fP, and
2092  \fBpcre_get_substring_list()\fR are provided for extracting captured substrings  \fBpcre_get_substring_list()\fP are provided for extracting captured substrings
2093  as new, separate, zero-terminated strings. These functions identify substrings  as new, separate, zero-terminated strings. These functions identify substrings
2094  by number. The next section describes functions for extracting named  by number. The next section describes functions for extracting named
2095  substrings. A substring that contains a binary zero is correctly extracted and  substrings.
2096  has a further zero added on the end, but the result is not, of course,  .P
2097  a C string.  A substring that contains a binary zero is correctly extracted and has a
2098    further zero added on the end, but the result is not, of course, a C string.
2099    However, you can process such a string by referring to the length that is
2100    returned by \fBpcre_copy_substring()\fP and \fBpcre_get_substring()\fP.
2101    Unfortunately, the interface to \fBpcre_get_substring_list()\fP is not adequate
2102    for handling strings containing binary zeros, because the end of the final
2103    string is not independently indicated.
2104    .P
2105  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:
2106  \fIsubject\fR is the subject string which has just been successfully matched,  \fIsubject\fP is the subject string that has just been successfully matched,
2107  \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
2108  \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
2109  captured by the match, including the substring that matched the entire regular  captured by the match, including the substring that matched the entire regular
2110  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
2111  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
2112  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
2113  the vector divided by three.  number of elements in the vector divided by three.
2114    .P
2115  The functions \fBpcre_copy_substring()\fR and \fBpcre_get_substring()\fR  The functions \fBpcre_copy_substring()\fP and \fBpcre_get_substring()\fP
2116  extract a single substring, whose number is given as \fIstringnumber\fR. A  extract a single substring, whose number is given as \fIstringnumber\fP. A
2117  value of zero extracts the substring that matched the entire pattern, while  value of zero extracts the substring that matched the entire pattern, whereas
2118  higher values extract the captured substrings. For \fBpcre_copy_substring()\fR,  higher values extract the captured substrings. For \fBpcre_copy_substring()\fP,
2119  the string is placed in \fIbuffer\fR, whose length is given by  the string is placed in \fIbuffer\fP, whose length is given by
2120  \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
2121  obtained via \fBpcre_malloc\fR, and its address is returned via  obtained via \fBpcre_malloc\fP, and its address is returned via
2122  \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
2123  including the terminating zero, or one of  including the terminating zero, or one of these error codes:
2124    .sp
2125    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
2126    .sp
2127  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
2128  memory failed for \fBpcre_get_substring()\fR.  memory failed for \fBpcre_get_substring()\fP.
2129    .sp
2130    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
2131    .sp
2132  There is no substring whose number is \fIstringnumber\fR.  There is no substring whose number is \fIstringnumber\fP.
2133    .P
2134  The \fBpcre_get_substring_list()\fR function extracts all available substrings  The \fBpcre_get_substring_list()\fP function extracts all available substrings
2135  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
2136  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
2137  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
2138  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
2139  function is zero if all went well, or  function is zero if all went well, or the error code
2140    .sp
2141    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
2142    .sp
2143  if the attempt to get the memory block failed.  if the attempt to get the memory block failed.
2144    .P
2145  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
2146  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
2147  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
2148  string. This can be distinguished from a genuine zero-length substring by  string. This can be distinguished from a genuine zero-length substring by
2149  inspecting the appropriate offset in \fIovector\fR, which is negative for unset  inspecting the appropriate offset in \fIovector\fP, which is negative for unset
2150  substrings.  substrings.
2151    .P
2152  The two convenience functions \fBpcre_free_substring()\fR and  The two convenience functions \fBpcre_free_substring()\fP and
2153  \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
2154  a previous call of \fBpcre_get_substring()\fR or  a previous call of \fBpcre_get_substring()\fP or
2155  \fBpcre_get_substring_list()\fR, respectively. They do nothing more than call  \fBpcre_get_substring_list()\fP, respectively. They do nothing more than call
2156  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
2157  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
2158  linked via a special interface to another programming language which cannot use  linked via a special interface to another programming language that cannot use
2159  \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
2160  provided.  provided.
2161    .
2162  .SH EXTRACTING CAPTURED SUBSTRINGS BY NAME  .
2163    .SH "EXTRACTING CAPTURED SUBSTRINGS BY NAME"
2164  .rs  .rs
2165  .sp  .sp
2166  .B int pcre_copy_named_substring(const pcre *\fIcode\fR,  .B int pcre_get_stringnumber(const pcre *\fIcode\fP,
2167  .ti +5n  .ti +5n
2168  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B const char *\fIname\fP);
2169    .PP
2170    .B int pcre_copy_named_substring(const pcre *\fIcode\fP,
2171  .ti +5n  .ti +5n
2172  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B const char *\fIsubject\fP, int *\fIovector\fP,
2173  .ti +5n  .ti +5n
2174  .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,  
2175  .ti +5n  .ti +5n
2176  .B const char *\fIname\fR);  .B char *\fIbuffer\fP, int \fIbuffersize\fP);
2177  .PP  .PP
2178  .br  .B int pcre_get_named_substring(const pcre *\fIcode\fP,
 .B int pcre_get_named_substring(const pcre *\fIcode\fR,  
2179  .ti +5n  .ti +5n
2180  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B const char *\fIsubject\fP, int *\fIovector\fP,
2181  .ti +5n  .ti +5n
2182  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B int \fIstringcount\fP, const char *\fIstringname\fP,
2183  .ti +5n  .ti +5n
2184  .B const char **\fIstringptr\fR);  .B const char **\fIstringptr\fP);
2185  .PP  .PP
2186  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.
2187  can be done by calling \fBpcre_get_stringnumber()\fR. The first argument is the  For example, for this pattern
2188  compiled pattern, and the second is the name. For example, for this pattern  .sp
2189      (a+)b(?<xxx>\ed+)...
2190    ab(?<xxx>\\d+)...  .sp
2191    the number of the subpattern called "xxx" is 2. If the name is known to be
2192  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
2193  extract the substring directly, or use one of the functions described in the  calling \fBpcre_get_stringnumber()\fP. The first argument is the compiled
2194  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
2195  whole job.  subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if there is no subpattern of
2196    that name.
2197  Most of the arguments of \fIpcre_copy_named_substring()\fR and  .P
2198  \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
2199  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
2200  differences.  two functions that do the whole job.
2201    .P
2202    Most of the arguments of \fBpcre_copy_named_substring()\fP and
2203    \fBpcre_get_named_substring()\fP are the same as those for the similarly named
2204    functions that extract by number. As these are described in the previous
2205    section, they are not re-described here. There are just two differences:
2206    .P
2207  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
2208  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
2209  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
2210  translation table.  translation table.
2211    .P
2212  These functions call \fBpcre_get_stringnumber()\fR, and if it succeeds, they  These functions call \fBpcre_get_stringnumber()\fP, and if it succeeds, they
2213  then call \fIpcre_copy_substring()\fR or \fIpcre_get_substring()\fR, as  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
2214  appropriate.  appropriate. \fBNOTE:\fP If PCRE_DUPNAMES is set and there are duplicate names,
2215    the behaviour may not be what you want (see the next section).
2216  .in 0  .P
2217  Last updated: 03 February 2003  \fBWarning:\fP If the pattern uses the (?| feature to set up multiple
2218  .br  subpatterns with the same number, as described in the
2219  Copyright (c) 1997-2003 University of Cambridge.  .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
2220    .\" </a>
2221    section on duplicate subpattern numbers
2222    .\"
2223    in the
2224    .\" HREF
2225    \fBpcrepattern\fP
2226    .\"
2227    page, you cannot use names to distinguish the different subpatterns, because
2228    names are not included in the compiled code. The matching process uses only
2229    numbers. For this reason, the use of different names for subpatterns of the
2230    same number causes an error at compile time.
2231    .
2232    .SH "DUPLICATE SUBPATTERN NAMES"
2233    .rs
2234    .sp
2235    .B int pcre_get_stringtable_entries(const pcre *\fIcode\fP,
2236    .ti +5n
2237    .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
2238    .PP
2239    When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
2240    are not required to be unique. (Duplicate names are always allowed for
2241    subpatterns with the same number, created by using the (?| feature. Indeed, if
2242    such subpatterns are named, they are required to use the same names.)
2243    .P
2244    Normally, patterns with duplicate names are such that in any one match, only
2245    one of the named subpatterns participates. An example is shown in the
2246    .\" HREF
2247    \fBpcrepattern\fP
2248    .\"
2249    documentation.
2250    .P
2251    When duplicates are present, \fBpcre_copy_named_substring()\fP and
2252    \fBpcre_get_named_substring()\fP return the first substring corresponding to
2253    the given name that is set. If none are set, PCRE_ERROR_NOSUBSTRING (-7) is
2254    returned; no data is returned. The \fBpcre_get_stringnumber()\fP function
2255    returns one of the numbers that are associated with the name, but it is not
2256    defined which it is.
2257    .P
2258    If you want to get full details of all captured substrings for a given name,
2259    you must use the \fBpcre_get_stringtable_entries()\fP function. The first
2260    argument is the compiled pattern, and the second is the name. The third and
2261    fourth are pointers to variables which are updated by the function. After it
2262    has run, they point to the first and last entries in the name-to-number table
2263    for the given name. The function itself returns the length of each entry, or
2264    PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
2265    described above in the section entitled \fIInformation about a pattern\fP
2266    .\" HTML <a href="#infoaboutpattern">
2267    .\" </a>
2268    above.
2269    .\"
2270    Given all the relevant entries for the name, you can extract each of their
2271    numbers, and hence the captured data, if any.
2272    .
2273    .
2274    .SH "FINDING ALL POSSIBLE MATCHES"
2275    .rs
2276    .sp
2277    The traditional matching function uses a similar algorithm to Perl, which stops
2278    when it finds the first match, starting at a given point in the subject. If you
2279    want to find all possible matches, or the longest possible match, consider
2280    using the alternative matching function (see below) instead. If you cannot use
2281    the alternative function, but still need to find all possible matches, you
2282    can kludge it up by making use of the callout facility, which is described in
2283    the
2284    .\" HREF
2285    \fBpcrecallout\fP
2286    .\"
2287    documentation.
2288    .P
2289    What you have to do is to insert a callout right at the end of the pattern.
2290    When your callout function is called, extract and save the current matched
2291    substring. Then return 1, which forces \fBpcre_exec()\fP to backtrack and try
2292    other alternatives. Ultimately, when it runs out of matches, \fBpcre_exec()\fP
2293    will yield PCRE_ERROR_NOMATCH.
2294    .
2295    .
2296    .\" HTML <a name="dfamatch"></a>
2297    .SH "MATCHING A PATTERN: THE ALTERNATIVE FUNCTION"
2298    .rs
2299    .sp
2300    .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
2301    .ti +5n
2302    .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
2303    .ti +5n
2304    .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,
2305    .ti +5n
2306    .B int *\fIworkspace\fP, int \fIwscount\fP);
2307    .P
2308    The function \fBpcre_dfa_exec()\fP is called to match a subject string against
2309    a compiled pattern, using a matching algorithm that scans the subject string
2310    just once, and does not backtrack. This has different characteristics to the
2311    normal algorithm, and is not compatible with Perl. Some of the features of PCRE
2312    patterns are not supported. Nevertheless, there are times when this kind of
2313    matching can be useful. For a discussion of the two matching algorithms, and a
2314    list of features that \fBpcre_dfa_exec()\fP does not support, see the
2315    .\" HREF
2316    \fBpcrematching\fP
2317    .\"
2318    documentation.
2319    .P
2320    The arguments for the \fBpcre_dfa_exec()\fP function are the same as for
2321    \fBpcre_exec()\fP, plus two extras. The \fIovector\fP argument is used in a
2322    different way, and this is described below. The other common arguments are used
2323    in the same way as for \fBpcre_exec()\fP, so their description is not repeated
2324    here.
2325    .P
2326    The two additional arguments provide workspace for the function. The workspace
2327    vector should contain at least 20 elements. It is used for keeping track of
2328    multiple paths through the pattern tree. More workspace will be needed for
2329    patterns and subjects where there are a lot of potential matches.
2330    .P
2331    Here is an example of a simple call to \fBpcre_dfa_exec()\fP:
2332    .sp
2333      int rc;
2334      int ovector[10];
2335      int wspace[20];
2336      rc = pcre_dfa_exec(
2337        re,             /* result of pcre_compile() */
2338        NULL,           /* we didn't study the pattern */
2339        "some string",  /* the subject string */
2340        11,             /* the length of the subject string */
2341        0,              /* start at offset 0 in the subject */
2342        0,              /* default options */
2343        ovector,        /* vector of integers for substring information */
2344        10,             /* number of elements (NOT size in bytes) */
2345        wspace,         /* working space vector */
2346        20);            /* number of elements (NOT size in bytes) */
2347    .
2348    .SS "Option bits for \fBpcre_dfa_exec()\fP"
2349    .rs
2350    .sp
2351    The unused bits of the \fIoptions\fP argument for \fBpcre_dfa_exec()\fP must be
2352    zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
2353    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
2354    PCRE_NO_UTF8_CHECK, PCRE_BSR_ANYCRLF, PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE,
2355    PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART.
2356    All but the last four of these are exactly the same as for \fBpcre_exec()\fP,
2357    so their description is not repeated here.
2358    .sp
2359      PCRE_PARTIAL_HARD
2360      PCRE_PARTIAL_SOFT
2361    .sp
2362    These have the same general effect as they do for \fBpcre_exec()\fP, but the
2363    details are slightly different. When PCRE_PARTIAL_HARD is set for
2364    \fBpcre_dfa_exec()\fP, it returns PCRE_ERROR_PARTIAL if the end of the subject
2365    is reached and there is still at least one matching possibility that requires
2366    additional characters. This happens even if some complete matches have also
2367    been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
2368    is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
2369    there have been no complete matches, but there is still at least one matching
2370    possibility. The portion of the string that was inspected when the longest
2371    partial match was found is set as the first matching string in both cases.
2372    There is a more detailed discussion of partial and multi-segment matching, with
2373    examples, in the
2374    .\" HREF
2375    \fBpcrepartial\fP
2376    .\"
2377    documentation.
2378    .sp
2379      PCRE_DFA_SHORTEST
2380    .sp
2381    Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as
2382    soon as it has found one match. Because of the way the alternative algorithm
2383    works, this is necessarily the shortest possible match at the first possible
2384    matching point in the subject string.
2385    .sp
2386      PCRE_DFA_RESTART
2387    .sp
2388    When \fBpcre_dfa_exec()\fP returns a partial match, it is possible to call it
2389    again, with additional subject characters, and have it continue with the same
2390    match. The PCRE_DFA_RESTART option requests this action; when it is set, the
2391    \fIworkspace\fP and \fIwscount\fP options must reference the same vector as
2392    before because data about the match so far is left in them after a partial
2393    match. There is more discussion of this facility in the
2394    .\" HREF
2395    \fBpcrepartial\fP
2396    .\"
2397    documentation.
2398    .
2399    .
2400    .SS "Successful returns from \fBpcre_dfa_exec()\fP"
2401    .rs
2402    .sp
2403    When \fBpcre_dfa_exec()\fP succeeds, it may have matched more than one
2404    substring in the subject. Note, however, that all the matches from one run of
2405    the function start at the same point in the subject. The shorter matches are
2406    all initial substrings of the longer matches. For example, if the pattern
2407    .sp
2408      <.*>
2409    .sp
2410    is matched against the string
2411    .sp
2412      This is <something> <something else> <something further> no more
2413    .sp
2414    the three matched strings are
2415    .sp
2416      <something>
2417      <something> <something else>
2418      <something> <something else> <something further>
2419    .sp
2420    On success, the yield of the function is a number greater than zero, which is
2421    the number of matched substrings. The substrings themselves are returned in
2422    \fIovector\fP. Each string uses two elements; the first is the offset to the
2423    start, and the second is the offset to the end. In fact, all the strings have
2424    the same start offset. (Space could have been saved by giving this only once,
2425    but it was decided to retain some compatibility with the way \fBpcre_exec()\fP
2426    returns data, even though the meaning of the strings is different.)
2427    .P
2428    The strings are returned in reverse order of length; that is, the longest
2429    matching string is given first. If there were too many matches to fit into
2430    \fIovector\fP, the yield of the function is zero, and the vector is filled with
2431    the longest matches.
2432    .
2433    .
2434    .SS "Error returns from \fBpcre_dfa_exec()\fP"
2435    .rs
2436    .sp
2437    The \fBpcre_dfa_exec()\fP function returns a negative number when it fails.
2438    Many of the errors are the same as for \fBpcre_exec()\fP, and these are
2439    described
2440    .\" HTML <a href="#errorlist">
2441    .\" </a>
2442    above.
2443    .\"
2444    There are in addition the following errors that are specific to
2445    \fBpcre_dfa_exec()\fP:
2446    .sp
2447      PCRE_ERROR_DFA_UITEM      (-16)
2448    .sp
2449    This return is given if \fBpcre_dfa_exec()\fP encounters an item in the pattern
2450    that it does not support, for instance, the use of \eC or a back reference.
2451    .sp
2452      PCRE_ERROR_DFA_UCOND      (-17)
2453    .sp
2454    This return is given if \fBpcre_dfa_exec()\fP encounters a condition item that
2455    uses a back reference for the condition, or a test for recursion in a specific
2456    group. These are not supported.
2457    .sp
2458      PCRE_ERROR_DFA_UMLIMIT    (-18)
2459    .sp
2460    This return is given if \fBpcre_dfa_exec()\fP is called with an \fIextra\fP
2461    block that contains a setting of the \fImatch_limit\fP or
2462    \fImatch_limit_recursion\fP fields. This is not supported (these fields are
2463    meaningless for DFA matching).
2464    .sp
2465      PCRE_ERROR_DFA_WSSIZE     (-19)
2466    .sp
2467    This return is given if \fBpcre_dfa_exec()\fP runs out of space in the
2468    \fIworkspace\fP vector.
2469    .sp
2470      PCRE_ERROR_DFA_RECURSE    (-20)
2471    .sp
2472    When a recursive subpattern is processed, the matching function calls itself
2473    recursively, using private vectors for \fIovector\fP and \fIworkspace\fP. This
2474    error is given if the output vector is not large enough. This should be
2475    extremely rare, as a vector of size 1000 is used.
2476    .
2477    .
2478    .SH "SEE ALSO"
2479    .rs
2480    .sp
2481    \fBpcrebuild\fP(3), \fBpcrecallout\fP(3), \fBpcrecpp(3)\fP(3),
2482    \fBpcrematching\fP(3), \fBpcrepartial\fP(3), \fBpcreposix\fP(3),
2483    \fBpcreprecompile\fP(3), \fBpcresample\fP(3), \fBpcrestack\fP(3).
2484    .
2485    .
2486    .SH AUTHOR
2487    .rs
2488    .sp
2489    .nf
2490    Philip Hazel
2491    University Computing Service
2492    Cambridge CB2 3QH, England.
2493    .fi
2494    .
2495    .
2496    .SH REVISION
2497    .rs
2498    .sp
2499    .nf
2500    Last updated: 27 August 2011
2501    Copyright (c) 1997-2011 University of Cambridge.
2502    .fi

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