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1  .TH PCRE 3  .TH PCREAPI 3
2  .SH NAME  .SH NAME
3  PCRE - Perl-compatible regular expressions  PCRE - Perl-compatible regular expressions
4  .SH SYNOPSIS OF PCRE API  .SH "PCRE NATIVE API"
5  .rs  .rs
6  .sp  .sp
7  .B #include <pcre.h>  .B #include <pcre.h>
8  .PP  .PP
9  .SM  .SM
10  .br  .B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,
 .B pcre *pcre_compile(const char *\fIpattern\fR, int \fIoptions\fR,  
11  .ti +5n  .ti +5n
12  .B const char **\fIerrptr\fR, int *\fIerroffset\fR,  .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
13  .ti +5n  .ti +5n
14  .B const unsigned char *\fItableptr\fR);  .B const unsigned char *\fItableptr\fP);
15  .PP  .PP
16  .br  .B pcre *pcre_compile2(const char *\fIpattern\fP, int \fIoptions\fP,
 .B pcre_extra *pcre_study(const pcre *\fIcode\fR, int \fIoptions\fR,  
17  .ti +5n  .ti +5n
18  .B const char **\fIerrptr\fR);  .B int *\fIerrorcodeptr\fP,
19    .ti +5n
20    .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
21    .ti +5n
22    .B const unsigned char *\fItableptr\fP);
23    .PP
24    .B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP,
25    .ti +5n
26    .B const char **\fIerrptr\fP);
27  .PP  .PP
28  .br  .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
 .B int pcre_exec(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"  
29  .ti +5n  .ti +5n
30  .B "const char *\fIsubject\fR," int \fIlength\fR, int \fIstartoffset\fR,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
31  .ti +5n  .ti +5n
32  .B int \fIoptions\fR, int *\fIovector\fR, int \fIovecsize\fR);  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
33  .PP  .PP
34  .br  .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
 .B int pcre_copy_named_substring(const pcre *\fIcode\fR,  
35  .ti +5n  .ti +5n
36  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
37  .ti +5n  .ti +5n
38  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,
39  .ti +5n  .ti +5n
40  .B char *\fIbuffer\fR, int \fIbuffersize\fR);  .B int *\fIworkspace\fP, int \fIwscount\fP);
41  .PP  .PP
42  .br  .B int pcre_copy_named_substring(const pcre *\fIcode\fP,
43  .B int pcre_copy_substring(const char *\fIsubject\fR, int *\fIovector\fR,  .ti +5n
44    .B const char *\fIsubject\fP, int *\fIovector\fP,
45  .ti +5n  .ti +5n
46  .B int \fIstringcount\fR, int \fIstringnumber\fR, char *\fIbuffer\fR,  .B int \fIstringcount\fP, const char *\fIstringname\fP,
47  .ti +5n  .ti +5n
48  .B int \fIbuffersize\fR);  .B char *\fIbuffer\fP, int \fIbuffersize\fP);
49  .PP  .PP
50  .br  .B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\fP,
 .B int pcre_get_named_substring(const pcre *\fIcode\fR,  
51  .ti +5n  .ti +5n
52  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP,
53  .ti +5n  .ti +5n
54  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B int \fIbuffersize\fP);
55    .PP
56    .B int pcre_get_named_substring(const pcre *\fIcode\fP,
57  .ti +5n  .ti +5n
58  .B const char **\fIstringptr\fR);  .B const char *\fIsubject\fP, int *\fIovector\fP,
59    .ti +5n
60    .B int \fIstringcount\fP, const char *\fIstringname\fP,
61    .ti +5n
62    .B const char **\fIstringptr\fP);
63  .PP  .PP
64  .br  .B int pcre_get_stringnumber(const pcre *\fIcode\fP,
 .B int pcre_get_stringnumber(const pcre *\fIcode\fR,  
65  .ti +5n  .ti +5n
66  .B const char *\fIname\fR);  .B const char *\fIname\fP);
67  .PP  .PP
68  .br  .B int pcre_get_stringtable_entries(const pcre *\fIcode\fP,
 .B int pcre_get_substring(const char *\fIsubject\fR, int *\fIovector\fR,  
69  .ti +5n  .ti +5n
70  .B int \fIstringcount\fR, int \fIstringnumber\fR,  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
71    .PP
72    .B int pcre_get_substring(const char *\fIsubject\fP, int *\fIovector\fP,
73  .ti +5n  .ti +5n
74  .B const char **\fIstringptr\fR);  .B int \fIstringcount\fP, int \fIstringnumber\fP,
75    .ti +5n
76    .B const char **\fIstringptr\fP);
77  .PP  .PP
78  .br  .B int pcre_get_substring_list(const char *\fIsubject\fP,
 .B int pcre_get_substring_list(const char *\fIsubject\fR,  
79  .ti +5n  .ti +5n
80  .B int *\fIovector\fR, int \fIstringcount\fR, "const char ***\fIlistptr\fR);"  .B int *\fIovector\fP, int \fIstringcount\fP, "const char ***\fIlistptr\fP);"
81  .PP  .PP
82  .br  .B void pcre_free_substring(const char *\fIstringptr\fP);
 .B void pcre_free_substring(const char *\fIstringptr\fR);  
83  .PP  .PP
84  .br  .B void pcre_free_substring_list(const char **\fIstringptr\fP);
 .B void pcre_free_substring_list(const char **\fIstringptr\fR);  
85  .PP  .PP
 .br  
86  .B const unsigned char *pcre_maketables(void);  .B const unsigned char *pcre_maketables(void);
87  .PP  .PP
88  .br  .B int pcre_fullinfo(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
 .B int pcre_fullinfo(const pcre *\fIcode\fR, "const pcre_extra *\fIextra\fR,"  
89  .ti +5n  .ti +5n
90  .B int \fIwhat\fR, void *\fIwhere\fR);  .B int \fIwhat\fP, void *\fIwhere\fP);
91    .PP
92    .B int pcre_info(const pcre *\fIcode\fP, int *\fIoptptr\fP, int
93    .B *\fIfirstcharptr\fP);
94  .PP  .PP
95  .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);  
96  .PP  .PP
97  .br  .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
 .B int pcre_config(int \fIwhat\fR, void *\fIwhere\fR);  
98  .PP  .PP
 .br  
99  .B char *pcre_version(void);  .B char *pcre_version(void);
100  .PP  .PP
 .br  
101  .B void *(*pcre_malloc)(size_t);  .B void *(*pcre_malloc)(size_t);
102  .PP  .PP
 .br  
103  .B void (*pcre_free)(void *);  .B void (*pcre_free)(void *);
104  .PP  .PP
105  .br  .B void *(*pcre_stack_malloc)(size_t);
106    .PP
107    .B void (*pcre_stack_free)(void *);
108    .PP
109  .B int (*pcre_callout)(pcre_callout_block *);  .B int (*pcre_callout)(pcre_callout_block *);
110    .
111  .SH PCRE API  .
112    .SH "PCRE API OVERVIEW"
113  .rs  .rs
114  .sp  .sp
115  PCRE has its own native API, which is described in this document. There is also  PCRE has its own native API, which is described in this document. There are
116  a set of wrapper functions that correspond to the POSIX regular expression API.  also some wrapper functions that correspond to the POSIX regular expression
117  These are described in the \fBpcreposix\fR documentation.  API. These are described in the
118    .\" HREF
119  The native API function prototypes are defined in the header file \fBpcre.h\fR,  \fBpcreposix\fP
120  and on Unix systems the library itself is called \fBlibpcre.a\fR, so can be  .\"
121  accessed by adding \fB-lpcre\fR to the command for linking an application which  documentation. Both of these APIs define a set of C function calls. A C++
122  calls it. The header file defines the macros PCRE_MAJOR and PCRE_MINOR to  wrapper is distributed with PCRE. It is documented in the
123  contain the major and minor release numbers for the library. Applications can  .\" HREF
124  use these to include support for different releases.  \fBpcrecpp\fP
125    .\"
126  The functions \fBpcre_compile()\fR, \fBpcre_study()\fR, and \fBpcre_exec()\fR  page.
127  are used for compiling and matching regular expressions. A sample program that  .P
128  demonstrates the simplest way of using them is given in the file  The native API C function prototypes are defined in the header file
129  \fIpcredemo.c\fR. The \fBpcresample\fR documentation describes how to run it.  \fBpcre.h\fP, and on Unix systems the library itself is called \fBlibpcre\fP.
130    It can normally be accessed by adding \fB-lpcre\fP to the command for linking
131  There are convenience functions for extracting captured substrings from a  an application that uses PCRE. The header file defines the macros PCRE_MAJOR
132  matched subject string. They are:  and PCRE_MINOR to contain the major and minor release numbers for the library.
133    Applications can use these to include support for different releases of PCRE.
134    \fBpcre_copy_substring()\fR  .P
135    \fBpcre_copy_named_substring()\fR  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,
136    \fBpcre_get_substring()\fR  and \fBpcre_exec()\fP are used for compiling and matching regular expressions
137    \fBpcre_get_named_substring()\fR  in a Perl-compatible manner. A sample program that demonstrates the simplest
138    \fBpcre_get_substring_list()\fR  way of using them is provided in the file called \fIpcredemo.c\fP in the source
139    distribution. The
140  \fBpcre_free_substring()\fR and \fBpcre_free_substring_list()\fR are also  .\" HREF
141    \fBpcresample\fP
142    .\"
143    documentation describes how to run it.
144    .P
145    A second matching function, \fBpcre_dfa_exec()\fP, which is not
146    Perl-compatible, is also provided. This uses a different algorithm for the
147    matching. The alternative algorithm finds all possible matches (at a given
148    point in the subject), and scans the subject just once. However, this algorithm
149    does not return captured substrings. A description of the two matching
150    algorithms and their advantages and disadvantages is given in the
151    .\" HREF
152    \fBpcrematching\fP
153    .\"
154    documentation.
155    .P
156    In addition to the main compiling and matching functions, there are convenience
157    functions for extracting captured substrings from a subject string that is
158    matched by \fBpcre_exec()\fP. They are:
159    .sp
160      \fBpcre_copy_substring()\fP
161      \fBpcre_copy_named_substring()\fP
162      \fBpcre_get_substring()\fP
163      \fBpcre_get_named_substring()\fP
164      \fBpcre_get_substring_list()\fP
165      \fBpcre_get_stringnumber()\fP
166      \fBpcre_get_stringtable_entries()\fP
167    .sp
168    \fBpcre_free_substring()\fP and \fBpcre_free_substring_list()\fP are also
169  provided, to free the memory used for extracted strings.  provided, to free the memory used for extracted strings.
170    .P
171  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
172  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,
173    or \fBpcre_dfa_exec()\fP. This is an optional facility that is provided for
174  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
175  compiled pattern; \fBpcre_info()\fR is an obsolete version which returns only  internal tables that are generated when PCRE is built are used.
176    .P
177    The function \fBpcre_fullinfo()\fP is used to find out information about a
178    compiled pattern; \fBpcre_info()\fP is an obsolete version that returns only
179  some of the available information, but is retained for backwards compatibility.  some of the available information, but is retained for backwards compatibility.
180  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
181  version of PCRE and its date of release.  version of PCRE and its date of release.
182    .P
183  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
184  the entry points of the standard \fBmalloc()\fR and \fBfree()\fR functions  containing a compiled pattern. This is provided for the benefit of
185    object-oriented applications.
186    .P
187    The global variables \fBpcre_malloc\fP and \fBpcre_free\fP initially contain
188    the entry points of the standard \fBmalloc()\fP and \fBfree()\fP functions,
189  respectively. PCRE calls the memory management functions via these variables,  respectively. PCRE calls the memory management functions via these variables,
190  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
191  should be done before calling any PCRE functions.  should be done before calling any PCRE functions.
192    .P
193  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
194    indirections to memory management functions. These special functions are used
195    only when PCRE is compiled to use the heap for remembering data, instead of
196    recursive function calls, when running the \fBpcre_exec()\fP function. See the
197    .\" HREF
198    \fBpcrebuild\fP
199    .\"
200    documentation for details of how to do this. It is a non-standard way of
201    building PCRE, for use in environments that have limited stacks. Because of the
202    greater use of memory management, it runs more slowly. Separate functions are
203    provided so that special-purpose external code can be used for this case. When
204    used, these functions are always called in a stack-like manner (last obtained,
205    first freed), and always for memory blocks of the same size. There is a
206    discussion about PCRE's stack usage in the
207    .\" HREF
208    \fBpcrestack\fP
209    .\"
210    documentation.
211    .P
212    The global variable \fBpcre_callout\fP initially contains NULL. It can be set
213  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
214  points during a matching operation. Details are given in the \fBpcrecallout\fR  points during a matching operation. Details are given in the
215    .\" HREF
216    \fBpcrecallout\fP
217    .\"
218  documentation.  documentation.
219    .
220    .
221    .SH NEWLINES
222    .rs
223    .sp
224    PCRE supports five different conventions for indicating line breaks in
225    strings: a single CR (carriage return) character, a single LF (linefeed)
226    character, the two-character sequence CRLF, any of the three preceding, or any
227    Unicode newline sequence. The Unicode newline sequences are the three just
228    mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed,
229    U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
230    (paragraph separator, U+2029).
231    .P
232    Each of the first three conventions is used by at least one operating system as
233    its standard newline sequence. When PCRE is built, a default can be specified.
234    The default default is LF, which is the Unix standard. When PCRE is run, the
235    default can be overridden, either when a pattern is compiled, or when it is
236    matched.
237    .P
238    In the PCRE documentation the word "newline" is used to mean "the character or
239    pair of characters that indicate a line break". The choice of newline
240    convention affects the handling of the dot, circumflex, and dollar
241    metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
242    recognized line ending sequence, the match position advancement for a
243    non-anchored pattern. The choice of newline convention does not affect the
244    interpretation of the \en or \er escape sequences.
245    .
246    .
247  .SH MULTITHREADING  .SH MULTITHREADING
248  .rs  .rs
249  .sp  .sp
250  The PCRE functions can be used in multi-threading applications, with the  The PCRE functions can be used in multi-threading applications, with the
251  proviso that the memory management functions pointed to by \fBpcre_malloc\fR  proviso that the memory management functions pointed to by \fBpcre_malloc\fP,
252  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
253  are shared by all threads.  callout function pointed to by \fBpcre_callout\fP, are shared by all threads.
254    .P
255  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
256  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.
257    .
258  .SH CHECKING BUILD-TIME OPTIONS  .
259    .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"
260    .rs
261    .sp
262    The compiled form of a regular expression can be saved and re-used at a later
263    time, possibly by a different program, and even on a host other than the one on
264    which it was compiled. Details are given in the
265    .\" HREF
266    \fBpcreprecompile\fP
267    .\"
268    documentation.
269    .
270    .
271    .SH "CHECKING BUILD-TIME OPTIONS"
272  .rs  .rs
273  .sp  .sp
274  .B int pcre_config(int \fIwhat\fR, void *\fIwhere\fR);  .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
275  .PP  .PP
276  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
277  discover which optional features have been compiled into the PCRE library. The  discover which optional features have been compiled into the PCRE library. The
278  .\" HREF  .\" HREF
279  \fBpcrebuild\fR  \fBpcrebuild\fP
280  .\"  .\"
281  documentation has more details about these optional features.  documentation has more details about these optional features.
282    .P
283  The first argument for \fBpcre_config()\fR is an integer, specifying which  The first argument for \fBpcre_config()\fP is an integer, specifying which
284  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
285  which the information is placed. The following information is available:  which the information is placed. The following information is available:
286    .sp
287    PCRE_CONFIG_UTF8    PCRE_CONFIG_UTF8
288    .sp
289  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;
290  otherwise it is set to zero.  otherwise it is set to zero.
291    .sp
292      PCRE_CONFIG_UNICODE_PROPERTIES
293    .sp
294    The output is an integer that is set to one if support for Unicode character
295    properties is available; otherwise it is set to zero.
296    .sp
297    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
298    .sp
299  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
300  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
301  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. The
302    default should normally be the standard sequence for your operating system.
303    .sp
304    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
305    .sp
306  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
307  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
308  allow larger regular expressions to be compiled, at the expense of slower  allow larger regular expressions to be compiled, at the expense of slower
309  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
310  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.
311    .sp
312    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
313    .sp
314  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
315  interface uses \fBmalloc()\fR for output vectors. Further details are given in  interface uses \fBmalloc()\fP for output vectors. Further details are given in
316  the \fBpcreposix\fR documentation.  the
317    .\" HREF
318    \fBpcreposix\fP
319    .\"
320    documentation.
321    .sp
322    PCRE_CONFIG_MATCH_LIMIT    PCRE_CONFIG_MATCH_LIMIT
323    .sp
324  The output is an integer that gives the default limit for the number of  The output is an integer that gives the default limit for the number of
325  internal matching function calls in a \fBpcre_exec()\fR execution. Further  internal matching function calls in a \fBpcre_exec()\fP execution. Further
326  details are given with \fBpcre_exec()\fR below.  details are given with \fBpcre_exec()\fP below.
327    .sp
328  .SH COMPILING A PATTERN    PCRE_CONFIG_MATCH_LIMIT_RECURSION
329  .rs  .sp
330  .sp  The output is an integer that gives the default limit for the depth of
331  .B pcre *pcre_compile(const char *\fIpattern\fR, int \fIoptions\fR,  recursion when calling the internal matching function in a \fBpcre_exec()\fP
332  .ti +5n  execution. Further details are given with \fBpcre_exec()\fP below.
333  .B const char **\fIerrptr\fR, int *\fIerroffset\fR,  .sp
334  .ti +5n    PCRE_CONFIG_STACKRECURSE
335  .B const unsigned char *\fItableptr\fR);  .sp
336  .PP  The output is an integer that is set to one if internal recursion when running
337    \fBpcre_exec()\fP is implemented by recursive function calls that use the stack
338  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
339  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
340  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
341  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
342  code and related data. The \fBpcre\fR type is defined for the returned block;  avoiding the use of the stack.
343  this is a typedef for a structure whose contents are not externally defined. It  .
344  is up to the caller to free the memory when it is no longer required.  .
345    .SH "COMPILING A PATTERN"
346    .rs
347    .sp
348    .B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,
349    .ti +5n
350    .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
351    .ti +5n
352    .B const unsigned char *\fItableptr\fP);
353    .sp
354    .B pcre *pcre_compile2(const char *\fIpattern\fP, int \fIoptions\fP,
355    .ti +5n
356    .B int *\fIerrorcodeptr\fP,
357    .ti +5n
358    .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
359    .ti +5n
360    .B const unsigned char *\fItableptr\fP);
361    .P
362    Either of the functions \fBpcre_compile()\fP or \fBpcre_compile2()\fP can be
363    called to compile a pattern into an internal form. The only difference between
364    the two interfaces is that \fBpcre_compile2()\fP has an additional argument,
365    \fIerrorcodeptr\fP, via which a numerical error code can be returned.
366    .P
367    The pattern is a C string terminated by a binary zero, and is passed in the
368    \fIpattern\fP argument. A pointer to a single block of memory that is obtained
369    via \fBpcre_malloc\fP is returned. This contains the compiled code and related
370    data. The \fBpcre\fP type is defined for the returned block; this is a typedef
371    for a structure whose contents are not externally defined. It is up to the
372    caller to free the memory (via \fBpcre_free\fP) when it is no longer required.
373    .P
374  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
375  depend on memory location, the complete \fBpcre\fR data block is not  depend on memory location, the complete \fBpcre\fP data block is not
376  fully relocatable, because it contains a copy of the \fItableptr\fR argument,  fully relocatable, because it may contain a copy of the \fItableptr\fP
377  which is an address (see below).  argument, which is an address (see below).
378    .P
379  The \fIoptions\fR argument contains independent bits that affect the  The \fIoptions\fP argument contains various bit settings that affect the
380  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
381  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
382  from within the pattern (see the detailed description of regular expressions  compatible with Perl, can also be set and unset from within the pattern (see
383  in the \fBpcrepattern\fR documentation). For these options, the contents of the  the detailed description in the
384  \fIoptions\fR argument specifies their initial settings at the start of  .\" HREF
385  compilation and execution. The PCRE_ANCHORED option can be set at the time of  \fBpcrepattern\fP
386    .\"
387    documentation). For these options, the contents of the \fIoptions\fP argument
388    specifies their initial settings at the start of compilation and execution. The
389    PCRE_ANCHORED and PCRE_NEWLINE_\fIxxx\fP options can be set at the time of
390  matching as well as at compile time.  matching as well as at compile time.
391    .P
392  If \fIerrptr\fR is NULL, \fBpcre_compile()\fR returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
393  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fR returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
394  NULL, and sets the variable pointed to by \fIerrptr\fR to point to a textual  NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual
395  error message. The offset from the start of the pattern to the character where  error message. This is a static string that is part of the library. You must
396  the error was discovered is placed in the variable pointed to by  not try to free it. The offset from the start of the pattern to the character
397  \fIerroffset\fR, which must not be NULL. If it is, an immediate error is given.  where the error was discovered is placed in the variable pointed to by
398    \fIerroffset\fP, which must not be NULL. If it is, an immediate error is given.
399  If the final argument, \fItableptr\fR, is NULL, PCRE uses a default set of  .P
400  character tables which are built when it is compiled, using the default C  If \fBpcre_compile2()\fP is used instead of \fBpcre_compile()\fP, and the
401  locale. Otherwise, \fItableptr\fR must be the result of a call to  \fIerrorcodeptr\fP argument is not NULL, a non-zero error code number is
402  \fBpcre_maketables()\fR. See the section on locale support below.  returned via this argument in the event of an error. This is in addition to the
403    textual error message. Error codes and messages are listed below.
404  This code fragment shows a typical straightforward call to \fBpcre_compile()\fR:  .P
405    If the final argument, \fItableptr\fP, is NULL, PCRE uses a default set of
406    character tables that are built when PCRE is compiled, using the default C
407    locale. Otherwise, \fItableptr\fP must be an address that is the result of a
408    call to \fBpcre_maketables()\fP. This value is stored with the compiled
409    pattern, and used again by \fBpcre_exec()\fP, unless another table pointer is
410    passed to it. For more discussion, see the section on locale support below.
411    .P
412    This code fragment shows a typical straightforward call to \fBpcre_compile()\fP:
413    .sp
414    pcre *re;    pcre *re;
415    const char *error;    const char *error;
416    int erroffset;    int erroffset;
# Line 265  This code fragment shows a typical strai Line 420  This code fragment shows a typical strai
420      &error,           /* for error message */      &error,           /* for error message */
421      &erroffset,       /* for error offset */      &erroffset,       /* for error offset */
422      NULL);            /* use default character tables */      NULL);            /* use default character tables */
423    .sp
424  The following option bits are defined:  The following names for option bits are defined in the \fBpcre.h\fP header
425    file:
426    .sp
427    PCRE_ANCHORED    PCRE_ANCHORED
428    .sp
429  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
430  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
431  being searched (the "subject string"). This effect can also be achieved by  being searched (the "subject string"). This effect can also be achieved by
432  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
433  Perl.  Perl.
434    .sp
435      PCRE_AUTO_CALLOUT
436    .sp
437    If this bit is set, \fBpcre_compile()\fP automatically inserts callout items,
438    all with number 255, before each pattern item. For discussion of the callout
439    facility, see the
440    .\" HREF
441    \fBpcrecallout\fP
442    .\"
443    documentation.
444    .sp
445    PCRE_CASELESS    PCRE_CASELESS
446    .sp
447  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
448  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
449  pattern by a (?i) option setting.  pattern by a (?i) option setting. In UTF-8 mode, PCRE always understands the
450    concept of case for characters whose values are less than 128, so caseless
451    matching is always possible. For characters with higher values, the concept of
452    case is supported if PCRE is compiled with Unicode property support, but not
453    otherwise. If you want to use caseless matching for characters 128 and above,
454    you must ensure that PCRE is compiled with Unicode property support as well as
455    with UTF-8 support.
456    .sp
457    PCRE_DOLLAR_ENDONLY    PCRE_DOLLAR_ENDONLY
458    .sp
459  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
460  end of the subject string. Without this option, a dollar also matches  end of the subject string. Without this option, a dollar also matches
461  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
462  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.
463  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
464  a pattern.  pattern.
465    .sp
466    PCRE_DOTALL    PCRE_DOTALL
467    .sp
468  If this bit is set, a dot metacharater in the pattern matches all characters,  If this bit is set, a dot metacharater in the pattern matches all characters,
469  including newlines. Without it, newlines are excluded. This option is  including those that indicate newline. Without it, a dot does not match when
470  equivalent to Perl's /s option, and it can be changed within a pattern by a  the current position is at a newline. This option is equivalent to Perl's /s
471  (?s) option setting. A negative class such as [^a] always matches a newline  option, and it can be changed within a pattern by a (?s) option setting. A
472  character, independent of the setting of this option.  negative class such as [^a] always matches newline characters, independent of
473    the setting of this option.
474    .sp
475      PCRE_DUPNAMES
476    .sp
477    If this bit is set, names used to identify capturing subpatterns need not be
478    unique. This can be helpful for certain types of pattern when it is known that
479    only one instance of the named subpattern can ever be matched. There are more
480    details of named subpatterns below; see also the
481    .\" HREF
482    \fBpcrepattern\fP
483    .\"
484    documentation.
485    .sp
486    PCRE_EXTENDED    PCRE_EXTENDED
487    .sp
488  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
489  ignored except when escaped or inside a character class. Whitespace does not  ignored except when escaped or inside a character class. Whitespace does not
490  include the VT character (code 11). In addition, characters between an  include the VT character (code 11). In addition, characters between an
491  unescaped # outside a character class and the next newline character,  unescaped # outside a character class and the next newline, inclusive, are also
492  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
493  be changed within a pattern by a (?x) option setting.  pattern by a (?x) option setting.
494    .P
495  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
496  Note, however, that this applies only to data characters. Whitespace characters  Note, however, that this applies only to data characters. Whitespace characters
497  may never appear within special character sequences in a pattern, for example  may never appear within special character sequences in a pattern, for example
498  within the sequence (?( which introduces a conditional subpattern.  within the sequence (?( which introduces a conditional subpattern.
499    .sp
500    PCRE_EXTRA    PCRE_EXTRA
501    .sp
502  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
503  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
504  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
505  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
506  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
507  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
508  controlled by this option. It can also be set by a (?X) option setting within a  give a warning for this.) There are at present no other features controlled by
509  pattern.  this option. It can also be set by a (?X) option setting within a pattern.
510    .sp
511      PCRE_FIRSTLINE
512    .sp
513    If this option is set, an unanchored pattern is required to match before or at
514    the first newline in the subject string, though the matched text may continue
515    over the newline.
516    .sp
517    PCRE_MULTILINE    PCRE_MULTILINE
518    .sp
519  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
520  characters (even if it actually contains several newlines). The "start of line"  characters (even if it actually contains newlines). The "start of line"
521  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
522  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
523  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
524  Perl.  Perl.
525    .P
526  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
527  match immediately following or immediately before any newline in the subject  match immediately following or immediately before internal newlines in the
528  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
529  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
530  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
531  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.
532    .sp
533      PCRE_NEWLINE_CR
534      PCRE_NEWLINE_LF
535      PCRE_NEWLINE_CRLF
536      PCRE_NEWLINE_ANYCRLF
537      PCRE_NEWLINE_ANY
538    .sp
539    These options override the default newline definition that was chosen when PCRE
540    was built. Setting the first or the second specifies that a newline is
541    indicated by a single character (CR or LF, respectively). Setting
542    PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
543    CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three
544    preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies
545    that any Unicode newline sequence should be recognized. The Unicode newline
546    sequences are the three just mentioned, plus the single characters VT (vertical
547    tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS (line
548    separator, U+2028), and PS (paragraph separator, U+2029). The last two are
549    recognized only in UTF-8 mode.
550    .P
551    The newline setting in the options word uses three bits that are treated
552    as a number, giving eight possibilities. Currently only six are used (default
553    plus the five values above). This means that if you set more than one newline
554    option, the combination may or may not be sensible. For example,
555    PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
556    other combinations may yield unused numbers and cause an error.
557    .P
558    The only time that a line break is specially recognized when compiling a
559    pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character
560    class is encountered. This indicates a comment that lasts until after the next
561    line break sequence. In other circumstances, line break sequences are treated
562    as literal data, except that in PCRE_EXTENDED mode, both CR and LF are treated
563    as whitespace characters and are therefore ignored.
564    .P
565    The newline option that is set at compile time becomes the default that is used
566    for \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, but it can be overridden.
567    .sp
568    PCRE_NO_AUTO_CAPTURE    PCRE_NO_AUTO_CAPTURE
569    .sp
570  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
571  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
572  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
573  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
574  in Perl.  in Perl.
575    .sp
576    PCRE_UNGREEDY    PCRE_UNGREEDY
577    .sp
578  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
579  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
580  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.
581    .sp
582    PCRE_UTF8    PCRE_UTF8
583    .sp
584  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
585  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
586  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
587  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
588  behaviour of PCRE are given in the  behaviour of PCRE are given in the
589  .\" HTML <a href="pcre.html#utf8support">  .\" HTML <a href="pcre.html#utf8support">
# Line 367  section on UTF-8 support Line 592  section on UTF-8 support
592  .\"  .\"
593  in the main  in the main
594  .\" HREF  .\" HREF
595  \fBpcre\fR  \fBpcre\fP
596  .\"  .\"
597  page.  page.
598    .sp
599  .SH STUDYING A PATTERN    PCRE_NO_UTF8_CHECK
600    .sp
601    When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
602    automatically checked. If an invalid UTF-8 sequence of bytes is found,
603    \fBpcre_compile()\fP returns an error. If you already know that your pattern is
604    valid, and you want to skip this check for performance reasons, you can set the
605    PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid
606    UTF-8 string as a pattern is undefined. It may cause your program to crash.
607    Note that this option can also be passed to \fBpcre_exec()\fP and
608    \fBpcre_dfa_exec()\fP, to suppress the UTF-8 validity checking of subject
609    strings.
610    .
611    .
612    .SH "COMPILATION ERROR CODES"
613  .rs  .rs
614  .sp  .sp
615  .B pcre_extra *pcre_study(const pcre *\fIcode\fR, int \fIoptions\fR,  The following table lists the error codes than may be returned by
616    \fBpcre_compile2()\fP, along with the error messages that may be returned by
617    both compiling functions. As PCRE has developed, some error codes have fallen
618    out of use. To avoid confusion, they have not been re-used.
619    .sp
620       0  no error
621       1  \e at end of pattern
622       2  \ec at end of pattern
623       3  unrecognized character follows \e
624       4  numbers out of order in {} quantifier
625       5  number too big in {} quantifier
626       6  missing terminating ] for character class
627       7  invalid escape sequence in character class
628       8  range out of order in character class
629       9  nothing to repeat
630      10  [this code is not in use]
631      11  internal error: unexpected repeat
632      12  unrecognized character after (?
633      13  POSIX named classes are supported only within a class
634      14  missing )
635      15  reference to non-existent subpattern
636      16  erroffset passed as NULL
637      17  unknown option bit(s) set
638      18  missing ) after comment
639      19  [this code is not in use]
640      20  regular expression too large
641      21  failed to get memory
642      22  unmatched parentheses
643      23  internal error: code overflow
644      24  unrecognized character after (?<
645      25  lookbehind assertion is not fixed length
646      26  malformed number or name after (?(
647      27  conditional group contains more than two branches
648      28  assertion expected after (?(
649      29  (?R or (?digits must be followed by )
650      30  unknown POSIX class name
651      31  POSIX collating elements are not supported
652      32  this version of PCRE is not compiled with PCRE_UTF8 support
653      33  [this code is not in use]
654      34  character value in \ex{...} sequence is too large
655      35  invalid condition (?(0)
656      36  \eC not allowed in lookbehind assertion
657      37  PCRE does not support \eL, \el, \eN, \eU, or \eu
658      38  number after (?C is > 255
659      39  closing ) for (?C expected
660      40  recursive call could loop indefinitely
661      41  unrecognized character after (?P
662      42  syntax error in subpattern name (missing terminator)
663      43  two named subpatterns have the same name
664      44  invalid UTF-8 string
665      45  support for \eP, \ep, and \eX has not been compiled
666      46  malformed \eP or \ep sequence
667      47  unknown property name after \eP or \ep
668      48  subpattern name is too long (maximum 32 characters)
669      49  too many named subpatterns (maximum 10,000)
670      50  repeated subpattern is too long
671      51  octal value is greater than \e377 (not in UTF-8 mode)
672      52  internal error: overran compiling workspace
673      53  internal error: previously-checked referenced subpattern not found
674      54  DEFINE group contains more than one branch
675      55  repeating a DEFINE group is not allowed
676      56  inconsistent NEWLINE options"
677    .
678    .
679    .SH "STUDYING A PATTERN"
680    .rs
681    .sp
682    .B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP
683  .ti +5n  .ti +5n
684  .B const char **\fIerrptr\fR);  .B const char **\fIerrptr\fP);
685  .PP  .PP
686  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
687  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
688  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
689  argument. If studing the pattern produces additional information that will help  argument. If studying the pattern produces additional information that will
690  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
691  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
692    results of the study.
693  The returned value from a \fBpcre_study()\fR can be passed directly to  .P
694  \fBpcre_exec()\fR. However, the \fBpcre_extra\fR block also contains other  The returned value from \fBpcre_study()\fP can be passed directly to
695    \fBpcre_exec()\fP. However, a \fBpcre_extra\fP block also contains other
696  fields that can be set by the caller before the block is passed; these are  fields that can be set by the caller before the block is passed; these are
697  described below. If studying the pattern does not produce any additional  described
698  information, \fBpcre_study()\fR returns NULL. In that circumstance, if the  .\" HTML <a href="#extradata">
699  calling program wants to pass some of the other fields to \fBpcre_exec()\fR, it  .\" </a>
700  must set up its own \fBpcre_extra\fR block.  below
701    .\"
702  The second argument contains option bits. At present, no options are defined  in the section on matching a pattern.
703  for \fBpcre_study()\fR, and this argument should always be zero.  .P
704    If studying the pattern does not produce any additional information
705  The third argument for \fBpcre_study()\fR is a pointer for an error message. If  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program
706    wants to pass any of the other fields to \fBpcre_exec()\fP, it must set up its
707    own \fBpcre_extra\fP block.
708    .P
709    The second argument of \fBpcre_study()\fP contains option bits. At present, no
710    options are defined, and this argument should always be zero.
711    .P
712    The third argument for \fBpcre_study()\fP is a pointer for an error message. If
713  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
714  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
715  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
716  be sure that it has run successfully.  should test the error pointer for NULL after calling \fBpcre_study()\fP, to be
717    sure that it has run successfully.
718  This is a typical call to \fBpcre_study\fR():  .P
719    This is a typical call to \fBpcre_study\fP():
720    .sp
721    pcre_extra *pe;    pcre_extra *pe;
722    pe = pcre_study(    pe = pcre_study(
723      re,             /* result of pcre_compile() */      re,             /* result of pcre_compile() */
724      0,              /* no options exist */      0,              /* no options exist */
725      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
726    .sp
727  At present, studying a pattern is useful only for non-anchored patterns that do  At present, studying a pattern is useful only for non-anchored patterns that do
728  not have a single fixed starting character. A bitmap of possible starting  not have a single fixed starting character. A bitmap of possible starting
729  characters is created.  bytes is created.
730    .
731    .
732  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
733  .SH LOCALE SUPPORT  .SH "LOCALE SUPPORT"
734  .rs  .rs
735  .sp  .sp
736  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters,
737  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
738  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
739  contains a default set of tables that is created in the default C locale when  less than 128. Higher-valued codes never match escapes such as \ew or \ed, but
740  PCRE is compiled. This is used when the final argument of \fBpcre_compile()\fR  can be tested with \ep if PCRE is built with Unicode character property
741  is NULL, and is sufficient for many applications.  support. The use of locales with Unicode is discouraged. If you are handling
742    characters with codes greater than 128, you should either use UTF-8 and
743  An alternative set of tables can, however, be supplied. Such tables are built  Unicode, or use locales, but not try to mix the two.
744  by calling the \fBpcre_maketables()\fR function, which has no arguments, in the  .P
745  relevant locale. The result can then be passed to \fBpcre_compile()\fR as often  PCRE contains an internal set of tables that are used when the final argument
746  as necessary. For example, to build and use tables that are appropriate for the  of \fBpcre_compile()\fP is NULL. These are sufficient for many applications.
747  French locale (where accented characters with codes greater than 128 are  Normally, the internal tables recognize only ASCII characters. However, when
748  treated as letters), the following code could be used:  PCRE is built, it is possible to cause the internal tables to be rebuilt in the
749    default "C" locale of the local system, which may cause them to be different.
750    setlocale(LC_CTYPE, "fr");  .P
751    The internal tables can always be overridden by tables supplied by the
752    application that calls PCRE. These may be created in a different locale from
753    the default. As more and more applications change to using Unicode, the need
754    for this locale support is expected to die away.
755    .P
756    External tables are built by calling the \fBpcre_maketables()\fP function,
757    which has no arguments, in the relevant locale. The result can then be passed
758    to \fBpcre_compile()\fP or \fBpcre_exec()\fP as often as necessary. For
759    example, to build and use tables that are appropriate for the French locale
760    (where accented characters with values greater than 128 are treated as letters),
761    the following code could be used:
762    .sp
763      setlocale(LC_CTYPE, "fr_FR");
764    tables = pcre_maketables();    tables = pcre_maketables();
765    re = pcre_compile(..., tables);    re = pcre_compile(..., tables);
766    .sp
767  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
768  pointer that is passed to \fBpcre_compile\fR is saved with the compiled  are using Windows, the name for the French locale is "french".
769  pattern, and the same tables are used via this pointer by \fBpcre_study()\fR  .P
770  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
771  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
772  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
773  memory containing the tables remains available for as long as it is needed.  needed.
774    .P
775  .SH INFORMATION ABOUT A PATTERN  The pointer that is passed to \fBpcre_compile()\fP is saved with the compiled
776    pattern, and the same tables are used via this pointer by \fBpcre_study()\fP
777    and normally also by \fBpcre_exec()\fP. Thus, by default, for any single
778    pattern, compilation, studying and matching all happen in the same locale, but
779    different patterns can be compiled in different locales.
780    .P
781    It is possible to pass a table pointer or NULL (indicating the use of the
782    internal tables) to \fBpcre_exec()\fP. Although not intended for this purpose,
783    this facility could be used to match a pattern in a different locale from the
784    one in which it was compiled. Passing table pointers at run time is discussed
785    below in the section on matching a pattern.
786    .
787    .
788    .SH "INFORMATION ABOUT A PATTERN"
789  .rs  .rs
790  .sp  .sp
791  .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,"
792  .ti +5n  .ti +5n
793  .B int \fIwhat\fR, void *\fIwhere\fR);  .B int \fIwhat\fP, void *\fIwhere\fP);
794  .PP  .PP
795  The \fBpcre_fullinfo()\fR function returns information about a compiled  The \fBpcre_fullinfo()\fP function returns information about a compiled
796  pattern. It replaces the obsolete \fBpcre_info()\fR function, which is  pattern. It replaces the obsolete \fBpcre_info()\fP function, which is
797  nevertheless retained for backwards compability (and is documented below).  nevertheless retained for backwards compability (and is documented below).
798    .P
799  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
800  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
801  the pattern was not studied. The third argument specifies which piece of  the pattern was not studied. The third argument specifies which piece of
802  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
803  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
804  the following negative numbers:  the following negative numbers:
805    .sp
806    PCRE_ERROR_NULL       the argument \fIcode\fR was NULL    PCRE_ERROR_NULL       the argument \fIcode\fP was NULL
807                          the argument \fIwhere\fR was NULL                          the argument \fIwhere\fP was NULL
808    PCRE_ERROR_BADMAGIC   the "magic number" was not found    PCRE_ERROR_BADMAGIC   the "magic number" was not found
809    PCRE_ERROR_BADOPTION  the value of \fIwhat\fR was invalid    PCRE_ERROR_BADOPTION  the value of \fIwhat\fP was invalid
810    .sp
811  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
812  compiled pattern:  check against passing an arbitrary memory pointer. Here is a typical call of
813    \fBpcre_fullinfo()\fP, to obtain the length of the compiled pattern:
814    .sp
815    int rc;    int rc;
816    unsigned long int length;    size_t length;
817    rc = pcre_fullinfo(    rc = pcre_fullinfo(
818      re,               /* result of pcre_compile() */      re,               /* result of pcre_compile() */
819      pe,               /* result of pcre_study(), or NULL */      pe,               /* result of pcre_study(), or NULL */
820      PCRE_INFO_SIZE,   /* what is required */      PCRE_INFO_SIZE,   /* what is required */
821      &length);         /* where to put the data */      &length);         /* where to put the data */
822    .sp
823  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
824  as follows:  as follows:
825    .sp
826    PCRE_INFO_BACKREFMAX    PCRE_INFO_BACKREFMAX
827    .sp
828  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
829  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
830  no back references.  no back references.
831    .sp
832    PCRE_INFO_CAPTURECOUNT    PCRE_INFO_CAPTURECOUNT
833    .sp
834  Return the number of capturing subpatterns in the pattern. The fourth argument  Return the number of capturing subpatterns in the pattern. The fourth argument
835  should point to an \fbint\fR variable.  should point to an \fBint\fP variable.
836    .sp
837      PCRE_INFO_DEFAULT_TABLES
838    .sp
839    Return a pointer to the internal default character tables within PCRE. The
840    fourth argument should point to an \fBunsigned char *\fP variable. This
841    information call is provided for internal use by the \fBpcre_study()\fP
842    function. External callers can cause PCRE to use its internal tables by passing
843    a NULL table pointer.
844    .sp
845    PCRE_INFO_FIRSTBYTE    PCRE_INFO_FIRSTBYTE
846    .sp
847  Return information about the first byte of any matched string, for a  Return information about the first byte of any matched string, for a
848  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
849  old name is still recognized for backwards compatibility.)  variable. (This option used to be called PCRE_INFO_FIRSTCHAR; the old name is
850    still recognized for backwards compatibility.)
851  If there is a fixed first byte, e.g. from a pattern such as (cat|cow|coyote),  .P
852  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
853    (cat|cow|coyote), its value is returned. Otherwise, if either
854    .sp
855  (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
856  starts with "^", or  starts with "^", or
857    .sp
858  (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
859  (if it were set, the pattern would be anchored),  (if it were set, the pattern would be anchored),
860    .sp
861  -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
862  subject string or after any newline within the string. Otherwise -2 is  subject string or after any newline within the string. Otherwise -2 is
863  returned. For anchored patterns, -2 is returned.  returned. For anchored patterns, -2 is returned.
864    .sp
865    PCRE_INFO_FIRSTTABLE    PCRE_INFO_FIRSTTABLE
866    .sp
867  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
868  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
869  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
870  fourth argument should point to an \fBunsigned char *\fR variable.  fourth argument should point to an \fBunsigned char *\fP variable.
871    .sp
872    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
873    .sp
874  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
875  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
876  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
877  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
878  /a\\d+z\\d+/ the returned value is 'z'.  follows something of variable length. For example, for the pattern
879    /^a\ed+z\ed+/ the returned value is "z", but for /^a\edz\ed/ the returned value
880    is -1.
881    .sp
882    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
883    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
884    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
885    .sp
886  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
887  names are just an additional way of identifying the parentheses, which still  names are just an additional way of identifying the parentheses, which still
888  acquire a number. A caller that wants to extract data from a named subpattern  acquire numbers. Several convenience functions such as
889  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
890  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
891  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
892  table for the pattern.  output vector (described with \fBpcre_exec()\fP below). To do the conversion,
893    you need to use the name-to-number map, which is described by these three
894    values.
895    .P
896  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
897  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
898  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
899  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
900  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
901  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
902  rest of the entry is the corresponding name, zero terminated. The names are in  rest of the entry is the corresponding name, zero terminated. The names are in
903  alphabetical order. For example, consider the following pattern (assume  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of
904    their parentheses numbers. For example, consider the following pattern (assume
905  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  PCRE_EXTENDED is set, so white space - including newlines - is ignored):
906    .sp
907    (?P<date> (?P<year>(\\d\\d)?\\d\\d) -  .\" JOIN
908    (?P<month>\\d\\d) - (?P<day>\\d\\d) )    (?<date> (?<year>(\ed\ed)?\ed\ed) -
909      (?<month>\ed\ed) - (?<day>\ed\ed) )
910    .sp
911  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
912  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
913  bytes shows in hex, and undefined bytes shown as ??:  bytes shows in hexadecimal, and undefined bytes shown as ??:
914    .sp
915    00 01 d  a  t  e  00 ??    00 01 d  a  t  e  00 ??
916    00 05 d  a  y  00 ?? ??    00 05 d  a  y  00 ?? ??
917    00 04 m  o  n  t  h  00    00 04 m  o  n  t  h  00
918    00 02 y  e  a  r  00 ??    00 02 y  e  a  r  00 ??
919    .sp
920  When writing code to extract data from named subpatterns, remember that the  When writing code to extract data from named subpatterns using the
921  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
922    different for each compiled pattern.
923    .sp
924    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
925    .sp
926  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
927  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
928  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
929  top-level option settings within the pattern itself.  top-level option settings within the pattern itself.
930    .P
931  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
932  alternatives begin with one of the following:  alternatives begin with one of the following:
933    .sp
934    ^     unless PCRE_MULTILINE is set    ^     unless PCRE_MULTILINE is set
935    \\A    always    \eA    always
936    \\G    always    \eG    always
937    .\" JOIN
938    .*    if PCRE_DOTALL is set and there are no back    .*    if PCRE_DOTALL is set and there are no back
939            references to the subpattern in which .* appears            references to the subpattern in which .* appears
940    .sp
941  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
942  \fBpcre_fullinfo()\fR.  \fBpcre_fullinfo()\fP.
943    .sp
944    PCRE_INFO_SIZE    PCRE_INFO_SIZE
945    .sp
946  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
947  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
948  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
949  variable.  variable.
950    .sp
951    PCRE_INFO_STUDYSIZE    PCRE_INFO_STUDYSIZE
952    .sp
953  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
954  a \fBpcre_extra\fR block. That is, it is the value that was passed to  a \fBpcre_extra\fP block. That is, it is the value that was passed to
955  \fBpcre_malloc()\fR when PCRE was getting memory into which to place the data  \fBpcre_malloc()\fP when PCRE was getting memory into which to place the data
956  created by \fBpcre_study()\fR. The fourth argument should point to a  created by \fBpcre_study()\fP. The fourth argument should point to a
957  \fBsize_t\fR variable.  \fBsize_t\fP variable.
958    .
959  .SH OBSOLETE INFO FUNCTION  .
960    .SH "OBSOLETE INFO FUNCTION"
961  .rs  .rs
962  .sp  .sp
963  .B int pcre_info(const pcre *\fIcode\fR, int *\fIoptptr\fR, int  .B int pcre_info(const pcre *\fIcode\fP, int *\fIoptptr\fP, int
964  .B *\fIfirstcharptr\fR);  .B *\fIfirstcharptr\fP);
965  .PP  .PP
966  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
967  restrictive to return all the available data about a compiled pattern. New  restrictive to return all the available data about a compiled pattern. New
968  programs should use \fBpcre_fullinfo()\fR instead. The yield of  programs should use \fBpcre_fullinfo()\fP instead. The yield of
969  \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
970  following negative numbers:  following negative numbers:
971    .sp
972    PCRE_ERROR_NULL       the argument \fIcode\fR was NULL    PCRE_ERROR_NULL       the argument \fIcode\fP was NULL
973    PCRE_ERROR_BADMAGIC   the "magic number" was not found    PCRE_ERROR_BADMAGIC   the "magic number" was not found
974    .sp
975  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
976  pattern was compiled is placed in the integer it points to (see  pattern was compiled is placed in the integer it points to (see
977  PCRE_INFO_OPTIONS above).  PCRE_INFO_OPTIONS above).
978    .P
979  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,
980  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
981  string (see PCRE_INFO_FIRSTBYTE above).  string (see PCRE_INFO_FIRSTBYTE above).
982    .
983  .SH MATCHING A PATTERN  .
984    .SH "REFERENCE COUNTS"
985    .rs
986    .sp
987    .B int pcre_refcount(pcre *\fIcode\fP, int \fIadjust\fP);
988    .PP
989    The \fBpcre_refcount()\fP function is used to maintain a reference count in the
990    data block that contains a compiled pattern. It is provided for the benefit of
991    applications that operate in an object-oriented manner, where different parts
992    of the application may be using the same compiled pattern, but you want to free
993    the block when they are all done.
994    .P
995    When a pattern is compiled, the reference count field is initialized to zero.
996    It is changed only by calling this function, whose action is to add the
997    \fIadjust\fP value (which may be positive or negative) to it. The yield of the
998    function is the new value. However, the value of the count is constrained to
999    lie between 0 and 65535, inclusive. If the new value is outside these limits,
1000    it is forced to the appropriate limit value.
1001    .P
1002    Except when it is zero, the reference count is not correctly preserved if a
1003    pattern is compiled on one host and then transferred to a host whose byte-order
1004    is different. (This seems a highly unlikely scenario.)
1005    .
1006    .
1007    .SH "MATCHING A PATTERN: THE TRADITIONAL FUNCTION"
1008  .rs  .rs
1009  .sp  .sp
1010  .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,"
1011  .ti +5n  .ti +5n
1012  .B "const char *\fIsubject\fR," int \fIlength\fR, int \fIstartoffset\fR,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
1013  .ti +5n  .ti +5n
1014  .B int \fIoptions\fR, int *\fIovector\fR, int \fIovecsize\fR);  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
1015  .PP  .P
1016  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
1017  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
1018  pattern has been studied, the result of the study should be passed in the  pattern has been studied, the result of the study should be passed in the
1019  \fIextra\fR argument.  \fIextra\fP argument. This function is the main matching facility of the
1020    library, and it operates in a Perl-like manner. For specialist use there is
1021  Here is an example of a simple call to \fBpcre_exec()\fR:  also an alternative matching function, which is described
1022    .\" HTML <a href="#dfamatch">
1023    .\" </a>
1024    below
1025    .\"
1026    in the section about the \fBpcre_dfa_exec()\fP function.
1027    .P
1028    In most applications, the pattern will have been compiled (and optionally
1029    studied) in the same process that calls \fBpcre_exec()\fP. However, it is
1030    possible to save compiled patterns and study data, and then use them later
1031    in different processes, possibly even on different hosts. For a discussion
1032    about this, see the
1033    .\" HREF
1034    \fBpcreprecompile\fP
1035    .\"
1036    documentation.
1037    .P
1038    Here is an example of a simple call to \fBpcre_exec()\fP:
1039    .sp
1040    int rc;    int rc;
1041    int ovector[30];    int ovector[30];
1042    rc = pcre_exec(    rc = pcre_exec(
# Line 645  Here is an example of a simple call to \ Line 1046  Here is an example of a simple call to \
1046      11,             /* the length of the subject string */      11,             /* the length of the subject string */
1047      0,              /* start at offset 0 in the subject */      0,              /* start at offset 0 in the subject */
1048      0,              /* default options */      0,              /* default options */
1049      ovector,        /* vector for substring information */      ovector,        /* vector of integers for substring information */
1050      30);            /* number of elements in the vector */      30);            /* number of elements (NOT size in bytes) */
1051    .
1052  If the \fIextra\fR argument is not NULL, it must point to a \fBpcre_extra\fR  .\" HTML <a name="extradata"></a>
1053  data block. The \fBpcre_study()\fR function returns such a block (when it  .SS "Extra data for \fBpcre_exec()\fR"
1054    .rs
1055    .sp
1056    If the \fIextra\fP argument is not NULL, it must point to a \fBpcre_extra\fP
1057    data block. The \fBpcre_study()\fP function returns such a block (when it
1058  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
1059  additional information in it. The fields in the block are as follows:  additional information in it. The \fBpcre_extra\fP block contains the following
1060    fields (not necessarily in this order):
1061    unsigned long int \fIflags\fR;  .sp
1062    void *\fIstudy_data\fR;    unsigned long int \fIflags\fP;
1063    unsigned long int \fImatch_limit\fR;    void *\fIstudy_data\fP;
1064    void *\fIcallout_data\fR;    unsigned long int \fImatch_limit\fP;
1065      unsigned long int \fImatch_limit_recursion\fP;
1066  The \fIflags\fR field is a bitmap that specifies which of the other fields    void *\fIcallout_data\fP;
1067      const unsigned char *\fItables\fP;
1068    .sp
1069    The \fIflags\fP field is a bitmap that specifies which of the other fields
1070  are set. The flag bits are:  are set. The flag bits are:
1071    .sp
1072    PCRE_EXTRA_STUDY_DATA    PCRE_EXTRA_STUDY_DATA
1073    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1074      PCRE_EXTRA_MATCH_LIMIT_RECURSION
1075    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1076      PCRE_EXTRA_TABLES
1077  Other flag bits should be set to zero. The \fIstudy_data\fR field is set in the  .sp
1078  \fBpcre_extra\fR block that is returned by \fBpcre_study()\fR, together with  Other flag bits should be set to zero. The \fIstudy_data\fP field is set in the
1079  the appropriate flag bit. You should not set this yourself, but you can add to  \fBpcre_extra\fP block that is returned by \fBpcre_study()\fP, together with
1080  the block by setting the other fields.  the appropriate flag bit. You should not set this yourself, but you may add to
1081    the block by setting the other fields and their corresponding flag bits.
1082  The \fImatch_limit\fR field provides a means of preventing PCRE from using up a  .P
1083    The \fImatch_limit\fP field provides a means of preventing PCRE from using up a
1084  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,
1085  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
1086  classic example is the use of nested unlimited repeats. Internally, PCRE uses a  classic example is the use of nested unlimited repeats.
1087  function called \fBmatch()\fR which it calls repeatedly (sometimes  .P
1088  recursively). The limit is imposed on the number of times this function is  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly
1089  called during a match, which has the effect of limiting the amount of recursion  (sometimes recursively). The limit set by \fImatch_limit\fP is imposed on the
1090  and backtracking that can take place. For patterns that are not anchored, the  number of times this function is called during a match, which has the effect of
1091  count starts from zero for each position in the subject string.  limiting the amount of backtracking that can take place. For patterns that are
1092    not anchored, the count restarts from zero for each position in the subject
1093  The default limit for the library can be set when PCRE is built; the default  string.
1094    .P
1095    The default value for the limit can be set when PCRE is built; the default
1096  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
1097  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
1098  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
1099  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
1100  exceeded, \fBpcre_exec()\fR returns PCRE_ERROR_MATCHLIMIT.  PCRE_ERROR_MATCHLIMIT.
1101    .P
1102  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
1103  which is described in the \fBpcrecallout\fR documentation.  instead of limiting the total number of times that \fBmatch()\fP is called, it
1104    limits the depth of recursion. The recursion depth is a smaller number than the
1105  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.
1106  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.
1107  first matching position. However, if a pattern was compiled with PCRE_ANCHORED,  .P
1108  or turned out to be anchored by virtue of its contents, it cannot be made  Limiting the recursion depth limits the amount of stack that can be used, or,
1109  unachored at matching time.  when PCRE has been compiled to use memory on the heap instead of the stack, the
1110    amount of heap memory that can be used.
1111  There are also three further options that can be set only at matching time:  .P
1112    The default value for \fImatch_limit_recursion\fP can be set when PCRE is
1113    built; the default default is the same value as the default for
1114    \fImatch_limit\fP. You can override the default by suppling \fBpcre_exec()\fP
1115    with a \fBpcre_extra\fP block in which \fImatch_limit_recursion\fP is set, and
1116    PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the \fIflags\fP field. If the limit
1117    is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1118    .P
1119    The \fIpcre_callout\fP field is used in conjunction with the "callout" feature,
1120    which is described in the
1121    .\" HREF
1122    \fBpcrecallout\fP
1123    .\"
1124    documentation.
1125    .P
1126    The \fItables\fP field is used to pass a character tables pointer to
1127    \fBpcre_exec()\fP; this overrides the value that is stored with the compiled
1128    pattern. A non-NULL value is stored with the compiled pattern only if custom
1129    tables were supplied to \fBpcre_compile()\fP via its \fItableptr\fP argument.
1130    If NULL is passed to \fBpcre_exec()\fP using this mechanism, it forces PCRE's
1131    internal tables to be used. This facility is helpful when re-using patterns
1132    that have been saved after compiling with an external set of tables, because
1133    the external tables might be at a different address when \fBpcre_exec()\fP is
1134    called. See the
1135    .\" HREF
1136    \fBpcreprecompile\fP
1137    .\"
1138    documentation for a discussion of saving compiled patterns for later use.
1139    .
1140    .SS "Option bits for \fBpcre_exec()\fP"
1141    .rs
1142    .sp
1143    The unused bits of the \fIoptions\fP argument for \fBpcre_exec()\fP must be
1144    zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
1145    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.
1146    .sp
1147      PCRE_ANCHORED
1148    .sp
1149    The PCRE_ANCHORED option limits \fBpcre_exec()\fP to matching at the first
1150    matching position. If a pattern was compiled with PCRE_ANCHORED, or turned out
1151    to be anchored by virtue of its contents, it cannot be made unachored at
1152    matching time.
1153    .sp
1154      PCRE_NEWLINE_CR
1155      PCRE_NEWLINE_LF
1156      PCRE_NEWLINE_CRLF
1157      PCRE_NEWLINE_ANYCRLF
1158      PCRE_NEWLINE_ANY
1159    .sp
1160    These options override the newline definition that was chosen or defaulted when
1161    the pattern was compiled. For details, see the description of
1162    \fBpcre_compile()\fP above. During matching, the newline choice affects the
1163    behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1164    the way the match position is advanced after a match failure for an unanchored
1165    pattern. When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is
1166    set, and a match attempt fails when the current position is at a CRLF sequence,
1167    the match position is advanced by two characters instead of one, in other
1168    words, to after the CRLF.
1169    .sp
1170    PCRE_NOTBOL    PCRE_NOTBOL
1171    .sp
1172  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
1173  circumflex metacharacter should not match before it. Setting this without  beginning of a line, so the circumflex metacharacter should not match before
1174  PCRE_MULTILINE (at compile time) causes circumflex never to match.  it. Setting this without PCRE_MULTILINE (at compile time) causes circumflex
1175    never to match. This option affects only the behaviour of the circumflex
1176    metacharacter. It does not affect \eA.
1177    .sp
1178    PCRE_NOTEOL    PCRE_NOTEOL
1179    .sp
1180  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
1181  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
1182  it. Setting this without PCRE_MULTILINE (at compile time) causes dollar never  mode) a newline immediately before it. Setting this without PCRE_MULTILINE (at
1183  to match.  compile time) causes dollar never to match. This option affects only the
1184    behaviour of the dollar metacharacter. It does not affect \eZ or \ez.
1185    .sp
1186    PCRE_NOTEMPTY    PCRE_NOTEMPTY
1187    .sp
1188  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
1189  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
1190  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
1191    .sp
1192    a?b?    a?b?
1193    .sp
1194  is applied to a string not beginning with "a" or "b", it matches the empty  is applied to a string not beginning with "a" or "b", it matches the empty
1195  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
1196  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".
1197    .P
1198  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case
1199  of a pattern match of the empty string within its \fBsplit()\fR function, and  of a pattern match of the empty string within its \fBsplit()\fP function, and
1200  when using the /g modifier. It is possible to emulate Perl's behaviour after  when using the /g modifier. It is possible to emulate Perl's behaviour after
1201  matching a null string by first trying the match again at the same offset with  matching a null string by first trying the match again at the same offset with
1202  PCRE_NOTEMPTY set, and then if that fails by advancing the starting offset (see  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the
1203  below) and trying an ordinary match again.  starting offset (see below) and trying an ordinary match again. There is some
1204    code that demonstrates how to do this in the \fIpcredemo.c\fP sample program.
1205  The subject string is passed to \fBpcre_exec()\fR as a pointer in  .sp
1206  \fIsubject\fR, a length in \fIlength\fR, and a starting offset in    PCRE_NO_UTF8_CHECK
1207  \fIstartoffset\fR. Unlike the pattern string, the subject may contain binary  .sp
1208  zero bytes. When the starting offset is zero, the search for a match starts at  When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8
1209  the beginning of the subject, and this is by far the most common case.  string is automatically checked when \fBpcre_exec()\fP is subsequently called.
1210    The value of \fIstartoffset\fP is also checked to ensure that it points to the
1211  If the pattern was compiled with the PCRE_UTF8 option, the subject must be a  start of a UTF-8 character. If an invalid UTF-8 sequence of bytes is found,
1212  sequence of bytes that is a valid UTF-8 string. If an invalid UTF-8 string is  \fBpcre_exec()\fP returns the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP
1213  passed, PCRE's behaviour is not defined.  contains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.
1214    .P
1215    If you already know that your subject is valid, and you want to skip these
1216    checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when
1217    calling \fBpcre_exec()\fP. You might want to do this for the second and
1218    subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find
1219    all the matches in a single subject string. However, you should be sure that
1220    the value of \fIstartoffset\fP points to the start of a UTF-8 character. When
1221    PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid UTF-8 string as a
1222    subject, or a value of \fIstartoffset\fP that does not point to the start of a
1223    UTF-8 character, is undefined. Your program may crash.
1224    .sp
1225      PCRE_PARTIAL
1226    .sp
1227    This option turns on the partial matching feature. If the subject string fails
1228    to match the pattern, but at some point during the matching process the end of
1229    the subject was reached (that is, the subject partially matches the pattern and
1230    the failure to match occurred only because there were not enough subject
1231    characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of
1232    PCRE_ERROR_NOMATCH. When PCRE_PARTIAL is used, there are restrictions on what
1233    may appear in the pattern. These are discussed in the
1234    .\" HREF
1235    \fBpcrepartial\fP
1236    .\"
1237    documentation.
1238    .
1239    .SS "The string to be matched by \fBpcre_exec()\fP"
1240    .rs
1241    .sp
1242    The subject string is passed to \fBpcre_exec()\fP as a pointer in
1243    \fIsubject\fP, a length in \fIlength\fP, and a starting byte offset in
1244    \fIstartoffset\fP. In UTF-8 mode, the byte offset must point to the start of a
1245    UTF-8 character. Unlike the pattern string, the subject may contain binary zero
1246    bytes. When the starting offset is zero, the search for a match starts at the
1247    beginning of the subject, and this is by far the most common case.
1248    .P
1249  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
1250  same subject by calling \fBpcre_exec()\fR again after a previous success.  same subject by calling \fBpcre_exec()\fP again after a previous success.
1251  Setting \fIstartoffset\fR differs from just passing over a shortened string and  Setting \fIstartoffset\fP differs from just passing over a shortened string and
1252  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
1253  lookbehind. For example, consider the pattern  lookbehind. For example, consider the pattern
1254    .sp
1255    \\Biss\\B    \eBiss\eB
1256    .sp
1257  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
1258  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
1259  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
1260  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
1261  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
1262  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
1263  \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
1264  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
1265  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.
1266    .P
1267  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
1268  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
1269  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.
1270    .
1271    .SS "How \fBpcre_exec()\fP returns captured substrings"
1272    .rs
1273    .sp
1274  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
1275  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
1276  pattern. Following the usage in Jeffrey Friedl's book, this is called  pattern. Following the usage in Jeffrey Friedl's book, this is called
1277  "capturing" in what follows, and the phrase "capturing subpattern" is used for  "capturing" in what follows, and the phrase "capturing subpattern" is used for
1278  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
1279  kinds of parenthesized subpattern that do not cause substrings to be captured.  kinds of parenthesized subpattern that do not cause substrings to be captured.
1280    .P
1281  Captured substrings are returned to the caller via a vector of integer offsets  Captured substrings are returned to the caller via a vector of integer offsets
1282  whose address is passed in \fIovector\fR. The number of elements in the vector  whose address is passed in \fIovector\fP. The number of elements in the vector
1283  is passed in \fIovecsize\fR. The first two-thirds of the vector is used to pass  is passed in \fIovecsize\fP, which must be a non-negative number. \fBNote\fP:
1284  back captured substrings, each substring using a pair of integers. The  this argument is NOT the size of \fIovector\fP in bytes.
1285  remaining third of the vector is used as workspace by \fBpcre_exec()\fR while  .P
1286  matching capturing subpatterns, and is not available for passing back  The first two-thirds of the vector is used to pass back captured substrings,
1287  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
1288  three. If it is not, it is rounded down.  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
1289    and is not available for passing back information. The length passed in
1290  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
1291  returned in pairs of integers, starting at the beginning of \fIovector\fR, and  rounded down.
1292    .P
1293    When a match is successful, information about captured substrings is returned
1294    in pairs of integers, starting at the beginning of \fIovector\fP, and
1295  continuing up to two-thirds of its length at the most. The first element of a  continuing up to two-thirds of its length at the most. The first element of a
1296  pair is set to the offset of the first character in a substring, and the second  pair is set to the offset of the first character in a substring, and the second
1297  is set to the offset of the first character after the end of a substring. The  is set to the offset of the first character after the end of a substring. The
1298  first pair, \fIovector[0]\fR and \fIovector[1]\fR, identify the portion of the  first pair, \fIovector[0]\fP and \fIovector[1]\fP, identify the portion of the
1299  subject string matched by the entire pattern. The next pair is used for the  subject string matched by the entire pattern. The next pair is used for the
1300  first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fR  first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fP
1301  is the number of pairs that have been set. If there are no capturing  is one more than the highest numbered pair that has been set. For example, if
1302  subpatterns, the return value from a successful match is 1, indicating that  two substrings have been captured, the returned value is 3. If there are no
1303  just the first pair of offsets has been set.  capturing subpatterns, the return value from a successful match is 1,
1304    indicating that just the first pair of offsets has been set.
1305  Some convenience functions are provided for extracting the captured substrings  .P
 as separate strings. These are described in the following section.  
   
 It is possible for an capturing subpattern number \fIn+1\fR to match some  
 part of the subject when subpattern \fIn\fR has not been used at all. For  
 example, if the string "abc" is matched against the pattern (a|(z))(bc)  
 subpatterns 1 and 3 are matched, but 2 is not. When this happens, both offset  
 values corresponding to the unused subpattern are set to -1.  
   
1306  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
1307  string that it matched that gets returned.  string that it matched that is returned.
1308    .P
1309  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
1310  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
1311  value of zero. In particular, if the substring offsets are not of interest,  returns a value of zero. In particular, if the substring offsets are not of
1312  \fBpcre_exec()\fR may be called with \fIovector\fR passed as NULL and  interest, \fBpcre_exec()\fP may be called with \fIovector\fP passed as NULL and
1313  \fIovecsize\fR as zero. However, if the pattern contains back references and  \fIovecsize\fP as zero. However, if the pattern contains back references and
1314  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
1315  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
1316  to supply an \fIovector\fR.  advisable to supply an \fIovector\fP.
1317    .P
1318  Note that \fBpcre_info()\fR can be used to find out how many capturing  The \fBpcre_info()\fP function can be used to find out how many capturing
1319  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1320  \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
1321  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.
1322    .P
1323  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
1324    the subject when subpattern \fIn\fP has not been used at all. For example, if
1325    the string "abc" is matched against the pattern (a|(z))(bc) the return from the
1326    function is 4, and subpatterns 1 and 3 are matched, but 2 is not. When this
1327    happens, both values in the offset pairs corresponding to unused subpatterns
1328    are set to -1.
1329    .P
1330    Offset values that correspond to unused subpatterns at the end of the
1331    expression are also set to -1. For example, if the string "abc" is matched
1332    against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
1333    return from the function is 2, because the highest used capturing subpattern
1334    number is 1. However, you can refer to the offsets for the second and third
1335    capturing subpatterns if you wish (assuming the vector is large enough, of
1336    course).
1337    .P
1338    Some convenience functions are provided for extracting the captured substrings
1339    as separate strings. These are described below.
1340    .
1341    .\" HTML <a name="errorlist"></a>
1342    .SS "Error return values from \fBpcre_exec()\fP"
1343    .rs
1344    .sp
1345    If \fBpcre_exec()\fP fails, it returns a negative number. The following are
1346  defined in the header file:  defined in the header file:
1347    .sp
1348    PCRE_ERROR_NOMATCH        (-1)    PCRE_ERROR_NOMATCH        (-1)
1349    .sp
1350  The subject string did not match the pattern.  The subject string did not match the pattern.
1351    .sp
1352    PCRE_ERROR_NULL           (-2)    PCRE_ERROR_NULL           (-2)
1353    .sp
1354  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
1355  NULL and \fIovecsize\fR was not zero.  NULL and \fIovecsize\fP was not zero.
1356    .sp
1357    PCRE_ERROR_BADOPTION      (-3)    PCRE_ERROR_BADOPTION      (-3)
1358    .sp
1359  An unrecognized bit was set in the \fIoptions\fR argument.  An unrecognized bit was set in the \fIoptions\fP argument.
1360    .sp
1361    PCRE_ERROR_BADMAGIC       (-4)    PCRE_ERROR_BADMAGIC       (-4)
1362    .sp
1363  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
1364  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
1365  magic number isn't present.  compiled in an environment of one endianness is run in an environment with the
1366    other endianness. This is the error that PCRE gives when the magic number is
1367    PCRE_ERROR_UNKNOWN_NODE   (-5)  not present.
1368    .sp
1369      PCRE_ERROR_UNKNOWN_OPCODE (-5)
1370    .sp
1371  While running the pattern match, an unknown item was encountered in the  While running the pattern match, an unknown item was encountered in the
1372  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
1373  of the compiled pattern.  of the compiled pattern.
1374    .sp
1375    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1376    .sp
1377  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
1378  \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
1379  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
1380  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
1381  the end of matching.  automatically freed at the end of matching.
1382    .sp
1383    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1384    .sp
1385  This error is used by the \fBpcre_copy_substring()\fR,  This error is used by the \fBpcre_copy_substring()\fP,
1386  \fBpcre_get_substring()\fR, and \fBpcre_get_substring_list()\fR functions (see  \fBpcre_get_substring()\fP, and \fBpcre_get_substring_list()\fP functions (see
1387  below). It is never returned by \fBpcre_exec()\fR.  below). It is never returned by \fBpcre_exec()\fP.
1388    .sp
1389    PCRE_ERROR_MATCHLIMIT     (-8)    PCRE_ERROR_MATCHLIMIT     (-8)
1390    .sp
1391  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
1392  field in a \fBpcre_extra\fR structure (or defaulted) was reached. See the  \fBpcre_extra\fP structure (or defaulted) was reached. See the description
1393  description above.  above.
1394    .sp
1395    PCRE_ERROR_CALLOUT        (-9)    PCRE_ERROR_CALLOUT        (-9)
1396    .sp
1397  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
1398  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
1399  \fBpcrecallout\fR documentation for details.  .\" HREF
1400    \fBpcrecallout\fP
1401  .SH EXTRACTING CAPTURED SUBSTRINGS BY NUMBER  .\"
1402    documentation for details.
1403    .sp
1404      PCRE_ERROR_BADUTF8        (-10)
1405    .sp
1406    A string that contains an invalid UTF-8 byte sequence was passed as a subject.
1407    .sp
1408      PCRE_ERROR_BADUTF8_OFFSET (-11)
1409    .sp
1410    The UTF-8 byte sequence that was passed as a subject was valid, but the value
1411    of \fIstartoffset\fP did not point to the beginning of a UTF-8 character.
1412    .sp
1413      PCRE_ERROR_PARTIAL        (-12)
1414    .sp
1415    The subject string did not match, but it did match partially. See the
1416    .\" HREF
1417    \fBpcrepartial\fP
1418    .\"
1419    documentation for details of partial matching.
1420    .sp
1421      PCRE_ERROR_BADPARTIAL     (-13)
1422    .sp
1423    The PCRE_PARTIAL option was used with a compiled pattern containing items that
1424    are not supported for partial matching. See the
1425    .\" HREF
1426    \fBpcrepartial\fP
1427    .\"
1428    documentation for details of partial matching.
1429    .sp
1430      PCRE_ERROR_INTERNAL       (-14)
1431    .sp
1432    An unexpected internal error has occurred. This error could be caused by a bug
1433    in PCRE or by overwriting of the compiled pattern.
1434    .sp
1435      PCRE_ERROR_BADCOUNT       (-15)
1436    .sp
1437    This error is given if the value of the \fIovecsize\fP argument is negative.
1438    .sp
1439      PCRE_ERROR_RECURSIONLIMIT (-21)
1440    .sp
1441    The internal recursion limit, as specified by the \fImatch_limit_recursion\fP
1442    field in a \fBpcre_extra\fP structure (or defaulted) was reached. See the
1443    description above.
1444    .sp
1445      PCRE_ERROR_NULLWSLIMIT    (-22)
1446    .sp
1447    When a group that can match an empty substring is repeated with an unbounded
1448    upper limit, the subject position at the start of the group must be remembered,
1449    so that a test for an empty string can be made when the end of the group is
1450    reached. Some workspace is required for this; if it runs out, this error is
1451    given.
1452    .sp
1453      PCRE_ERROR_BADNEWLINE     (-23)
1454    .sp
1455    An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
1456    .P
1457    Error numbers -16 to -20 are not used by \fBpcre_exec()\fP.
1458    .
1459    .
1460    .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
1461  .rs  .rs
1462  .sp  .sp
1463  .B int pcre_copy_substring(const char *\fIsubject\fR, int *\fIovector\fR,  .B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\fP,
1464  .ti +5n  .ti +5n
1465  .B int \fIstringcount\fR, int \fIstringnumber\fR, char *\fIbuffer\fR,  .B int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP,
1466  .ti +5n  .ti +5n
1467  .B int \fIbuffersize\fR);  .B int \fIbuffersize\fP);
1468  .PP  .PP
1469  .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,  
1470  .ti +5n  .ti +5n
1471  .B int \fIstringcount\fR, int \fIstringnumber\fR,  .B int \fIstringcount\fP, int \fIstringnumber\fP,
1472  .ti +5n  .ti +5n
1473  .B const char **\fIstringptr\fR);  .B const char **\fIstringptr\fP);
1474  .PP  .PP
1475  .br  .B int pcre_get_substring_list(const char *\fIsubject\fP,
 .B int pcre_get_substring_list(const char *\fIsubject\fR,  
1476  .ti +5n  .ti +5n
1477  .B int *\fIovector\fR, int \fIstringcount\fR, "const char ***\fIlistptr\fR);"  .B int *\fIovector\fP, int \fIstringcount\fP, "const char ***\fIlistptr\fP);"
1478  .PP  .PP
1479  Captured substrings can be accessed directly by using the offsets returned by  Captured substrings can be accessed directly by using the offsets returned by
1480  \fBpcre_exec()\fR in \fIovector\fR. For convenience, the functions  \fBpcre_exec()\fP in \fIovector\fP. For convenience, the functions
1481  \fBpcre_copy_substring()\fR, \fBpcre_get_substring()\fR, and  \fBpcre_copy_substring()\fP, \fBpcre_get_substring()\fP, and
1482  \fBpcre_get_substring_list()\fR are provided for extracting captured substrings  \fBpcre_get_substring_list()\fP are provided for extracting captured substrings
1483  as new, separate, zero-terminated strings. These functions identify substrings  as new, separate, zero-terminated strings. These functions identify substrings
1484  by number. The next section describes functions for extracting named  by number. The next section describes functions for extracting named
1485  substrings. A substring that contains a binary zero is correctly extracted and  substrings.
1486  has a further zero added on the end, but the result is not, of course,  .P
1487  a C string.  A substring that contains a binary zero is correctly extracted and has a
1488    further zero added on the end, but the result is not, of course, a C string.
1489    However, you can process such a string by referring to the length that is
1490    returned by \fBpcre_copy_substring()\fP and \fBpcre_get_substring()\fP.
1491    Unfortunately, the interface to \fBpcre_get_substring_list()\fP is not adequate
1492    for handling strings containing binary zeros, because the end of the final
1493    string is not independently indicated.
1494    .P
1495  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:
1496  \fIsubject\fR is the subject string which has just been successfully matched,  \fIsubject\fP is the subject string that has just been successfully matched,
1497  \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
1498  \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
1499  captured by the match, including the substring that matched the entire regular  captured by the match, including the substring that matched the entire regular
1500  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
1501  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
1502  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
1503  the vector divided by three.  number of elements in the vector divided by three.
1504    .P
1505  The functions \fBpcre_copy_substring()\fR and \fBpcre_get_substring()\fR  The functions \fBpcre_copy_substring()\fP and \fBpcre_get_substring()\fP
1506  extract a single substring, whose number is given as \fIstringnumber\fR. A  extract a single substring, whose number is given as \fIstringnumber\fP. A
1507  value of zero extracts the substring that matched the entire pattern, while  value of zero extracts the substring that matched the entire pattern, whereas
1508  higher values extract the captured substrings. For \fBpcre_copy_substring()\fR,  higher values extract the captured substrings. For \fBpcre_copy_substring()\fP,
1509  the string is placed in \fIbuffer\fR, whose length is given by  the string is placed in \fIbuffer\fP, whose length is given by
1510  \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
1511  obtained via \fBpcre_malloc\fR, and its address is returned via  obtained via \fBpcre_malloc\fP, and its address is returned via
1512  \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
1513  including the terminating zero, or one of  including the terminating zero, or one of these error codes:
1514    .sp
1515    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1516    .sp
1517  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
1518  memory failed for \fBpcre_get_substring()\fR.  memory failed for \fBpcre_get_substring()\fP.
1519    .sp
1520    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1521    .sp
1522  There is no substring whose number is \fIstringnumber\fR.  There is no substring whose number is \fIstringnumber\fP.
1523    .P
1524  The \fBpcre_get_substring_list()\fR function extracts all available substrings  The \fBpcre_get_substring_list()\fP function extracts all available substrings
1525  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
1526  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
1527  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
1528  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
1529  function is zero if all went well, or  function is zero if all went well, or the error code
1530    .sp
1531    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1532    .sp
1533  if the attempt to get the memory block failed.  if the attempt to get the memory block failed.
1534    .P
1535  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
1536  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
1537  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
1538  string. This can be distinguished from a genuine zero-length substring by  string. This can be distinguished from a genuine zero-length substring by
1539  inspecting the appropriate offset in \fIovector\fR, which is negative for unset  inspecting the appropriate offset in \fIovector\fP, which is negative for unset
1540  substrings.  substrings.
1541    .P
1542  The two convenience functions \fBpcre_free_substring()\fR and  The two convenience functions \fBpcre_free_substring()\fP and
1543  \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
1544  a previous call of \fBpcre_get_substring()\fR or  a previous call of \fBpcre_get_substring()\fP or
1545  \fBpcre_get_substring_list()\fR, respectively. They do nothing more than call  \fBpcre_get_substring_list()\fP, respectively. They do nothing more than call
1546  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
1547  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
1548  linked via a special interface to another programming language which cannot use  linked via a special interface to another programming language that cannot use
1549  \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
1550  provided.  provided.
1551    .
1552  .SH EXTRACTING CAPTURED SUBSTRINGS BY NAME  .
1553    .SH "EXTRACTING CAPTURED SUBSTRINGS BY NAME"
1554  .rs  .rs
1555  .sp  .sp
1556  .B int pcre_copy_named_substring(const pcre *\fIcode\fR,  .B int pcre_get_stringnumber(const pcre *\fIcode\fP,
1557  .ti +5n  .ti +5n
1558  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B const char *\fIname\fP);
1559    .PP
1560    .B int pcre_copy_named_substring(const pcre *\fIcode\fP,
1561  .ti +5n  .ti +5n
1562  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B const char *\fIsubject\fP, int *\fIovector\fP,
1563  .ti +5n  .ti +5n
1564  .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,  
1565  .ti +5n  .ti +5n
1566  .B const char *\fIname\fR);  .B char *\fIbuffer\fP, int \fIbuffersize\fP);
1567  .PP  .PP
1568  .br  .B int pcre_get_named_substring(const pcre *\fIcode\fP,
 .B int pcre_get_named_substring(const pcre *\fIcode\fR,  
1569  .ti +5n  .ti +5n
1570  .B const char *\fIsubject\fR, int *\fIovector\fR,  .B const char *\fIsubject\fP, int *\fIovector\fP,
1571  .ti +5n  .ti +5n
1572  .B int \fIstringcount\fR, const char *\fIstringname\fR,  .B int \fIstringcount\fP, const char *\fIstringname\fP,
1573  .ti +5n  .ti +5n
1574  .B const char **\fIstringptr\fR);  .B const char **\fIstringptr\fP);
1575  .PP  .PP
1576  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.
1577  can be done by calling \fBpcre_get_stringnumber()\fR. The first argument is the  For example, for this pattern
1578  compiled pattern, and the second is the name. For example, for this pattern  .sp
1579      (a+)b(?<xxx>\ed+)...
1580    ab(?<xxx>\\d+)...  .sp
1581    the number of the subpattern called "xxx" is 2. If the name is known to be
1582  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
1583  extract the substring directly, or use one of the functions described in the  calling \fBpcre_get_stringnumber()\fP. The first argument is the compiled
1584  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
1585  whole job.  subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if there is no subpattern of
1586    that name.
1587  Most of the arguments of \fIpcre_copy_named_substring()\fR and  .P
1588  \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
1589  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
1590  differences.  two functions that do the whole job.
1591    .P
1592    Most of the arguments of \fBpcre_copy_named_substring()\fP and
1593    \fBpcre_get_named_substring()\fP are the same as those for the similarly named
1594    functions that extract by number. As these are described in the previous
1595    section, they are not re-described here. There are just two differences:
1596    .P
1597  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
1598  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
1599  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
1600  translation table.  translation table.
1601    .P
1602  These functions call \fBpcre_get_stringnumber()\fR, and if it succeeds, they  These functions call \fBpcre_get_stringnumber()\fP, and if it succeeds, they
1603  then call \fIpcre_copy_substring()\fR or \fIpcre_get_substring()\fR, as  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
1604  appropriate.  appropriate. \fBNOTE:\fP If PCRE_DUPNAMES is set and there are duplicate names,
1605    the behaviour may not be what you want (see the next section).
1606  .in 0  .
1607  Last updated: 03 February 2003  .
1608  .br  .SH "DUPLICATE SUBPATTERN NAMES"
1609  Copyright (c) 1997-2003 University of Cambridge.  .rs
1610    .sp
1611    .B int pcre_get_stringtable_entries(const pcre *\fIcode\fP,
1612    .ti +5n
1613    .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
1614    .PP
1615    When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
1616    are not required to be unique. Normally, patterns with duplicate names are such
1617    that in any one match, only one of the named subpatterns participates. An
1618    example is shown in the
1619    .\" HREF
1620    \fBpcrepattern\fP
1621    .\"
1622    documentation. When duplicates are present, \fBpcre_copy_named_substring()\fP
1623    and \fBpcre_get_named_substring()\fP return the first substring corresponding
1624    to the given name that is set. If none are set, an empty string is returned.
1625    The \fBpcre_get_stringnumber()\fP function returns one of the numbers that are
1626    associated with the name, but it is not defined which it is.
1627    .sp
1628    If you want to get full details of all captured substrings for a given name,
1629    you must use the \fBpcre_get_stringtable_entries()\fP function. The first
1630    argument is the compiled pattern, and the second is the name. The third and
1631    fourth are pointers to variables which are updated by the function. After it
1632    has run, they point to the first and last entries in the name-to-number table
1633    for the given name. The function itself returns the length of each entry, or
1634    PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
1635    described above in the section entitled \fIInformation about a pattern\fP.
1636    Given all the relevant entries for the name, you can extract each of their
1637    numbers, and hence the captured data, if any.
1638    .
1639    .
1640    .SH "FINDING ALL POSSIBLE MATCHES"
1641    .rs
1642    .sp
1643    The traditional matching function uses a similar algorithm to Perl, which stops
1644    when it finds the first match, starting at a given point in the subject. If you
1645    want to find all possible matches, or the longest possible match, consider
1646    using the alternative matching function (see below) instead. If you cannot use
1647    the alternative function, but still need to find all possible matches, you
1648    can kludge it up by making use of the callout facility, which is described in
1649    the
1650    .\" HREF
1651    \fBpcrecallout\fP
1652    .\"
1653    documentation.
1654    .P
1655    What you have to do is to insert a callout right at the end of the pattern.
1656    When your callout function is called, extract and save the current matched
1657    substring. Then return 1, which forces \fBpcre_exec()\fP to backtrack and try
1658    other alternatives. Ultimately, when it runs out of matches, \fBpcre_exec()\fP
1659    will yield PCRE_ERROR_NOMATCH.
1660    .
1661    .
1662    .\" HTML <a name="dfamatch"></a>
1663    .SH "MATCHING A PATTERN: THE ALTERNATIVE FUNCTION"
1664    .rs
1665    .sp
1666    .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
1667    .ti +5n
1668    .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
1669    .ti +5n
1670    .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,
1671    .ti +5n
1672    .B int *\fIworkspace\fP, int \fIwscount\fP);
1673    .P
1674    The function \fBpcre_dfa_exec()\fP is called to match a subject string against
1675    a compiled pattern, using a matching algorithm that scans the subject string
1676    just once, and does not backtrack. This has different characteristics to the
1677    normal algorithm, and is not compatible with Perl. Some of the features of PCRE
1678    patterns are not supported. Nevertheless, there are times when this kind of
1679    matching can be useful. For a discussion of the two matching algorithms, see
1680    the
1681    .\" HREF
1682    \fBpcrematching\fP
1683    .\"
1684    documentation.
1685    .P
1686    The arguments for the \fBpcre_dfa_exec()\fP function are the same as for
1687    \fBpcre_exec()\fP, plus two extras. The \fIovector\fP argument is used in a
1688    different way, and this is described below. The other common arguments are used
1689    in the same way as for \fBpcre_exec()\fP, so their description is not repeated
1690    here.
1691    .P
1692    The two additional arguments provide workspace for the function. The workspace
1693    vector should contain at least 20 elements. It is used for keeping track of
1694    multiple paths through the pattern tree. More workspace will be needed for
1695    patterns and subjects where there are a lot of potential matches.
1696    .P
1697    Here is an example of a simple call to \fBpcre_dfa_exec()\fP:
1698    .sp
1699      int rc;
1700      int ovector[10];
1701      int wspace[20];
1702      rc = pcre_dfa_exec(
1703        re,             /* result of pcre_compile() */
1704        NULL,           /* we didn't study the pattern */
1705        "some string",  /* the subject string */
1706        11,             /* the length of the subject string */
1707        0,              /* start at offset 0 in the subject */
1708        0,              /* default options */
1709        ovector,        /* vector of integers for substring information */
1710        10,             /* number of elements (NOT size in bytes) */
1711        wspace,         /* working space vector */
1712        20);            /* number of elements (NOT size in bytes) */
1713    .
1714    .SS "Option bits for \fBpcre_dfa_exec()\fP"
1715    .rs
1716    .sp
1717    The unused bits of the \fIoptions\fP argument for \fBpcre_dfa_exec()\fP must be
1718    zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
1719    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,
1720    PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last three of these are
1721    the same as for \fBpcre_exec()\fP, so their description is not repeated here.
1722    .sp
1723      PCRE_PARTIAL
1724    .sp
1725    This has the same general effect as it does for \fBpcre_exec()\fP, but the
1726    details are slightly different. When PCRE_PARTIAL is set for
1727    \fBpcre_dfa_exec()\fP, the return code PCRE_ERROR_NOMATCH is converted into
1728    PCRE_ERROR_PARTIAL if the end of the subject is reached, there have been no
1729    complete matches, but there is still at least one matching possibility. The
1730    portion of the string that provided the partial match is set as the first
1731    matching string.
1732    .sp
1733      PCRE_DFA_SHORTEST
1734    .sp
1735    Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as
1736    soon as it has found one match. Because of the way the alternative algorithm
1737    works, this is necessarily the shortest possible match at the first possible
1738    matching point in the subject string.
1739    .sp
1740      PCRE_DFA_RESTART
1741    .sp
1742    When \fBpcre_dfa_exec()\fP is called with the PCRE_PARTIAL option, and returns
1743    a partial match, it is possible to call it again, with additional subject
1744    characters, and have it continue with the same match. The PCRE_DFA_RESTART
1745    option requests this action; when it is set, the \fIworkspace\fP and
1746    \fIwscount\fP options must reference the same vector as before because data
1747    about the match so far is left in them after a partial match. There is more
1748    discussion of this facility in the
1749    .\" HREF
1750    \fBpcrepartial\fP
1751    .\"
1752    documentation.
1753    .
1754    .SS "Successful returns from \fBpcre_dfa_exec()\fP"
1755    .rs
1756    .sp
1757    When \fBpcre_dfa_exec()\fP succeeds, it may have matched more than one
1758    substring in the subject. Note, however, that all the matches from one run of
1759    the function start at the same point in the subject. The shorter matches are
1760    all initial substrings of the longer matches. For example, if the pattern
1761    .sp
1762      <.*>
1763    .sp
1764    is matched against the string
1765    .sp
1766      This is <something> <something else> <something further> no more
1767    .sp
1768    the three matched strings are
1769    .sp
1770      <something>
1771      <something> <something else>
1772      <something> <something else> <something further>
1773    .sp
1774    On success, the yield of the function is a number greater than zero, which is
1775    the number of matched substrings. The substrings themselves are returned in
1776    \fIovector\fP. Each string uses two elements; the first is the offset to the
1777    start, and the second is the offset to the end. In fact, all the strings have
1778    the same start offset. (Space could have been saved by giving this only once,
1779    but it was decided to retain some compatibility with the way \fBpcre_exec()\fP
1780    returns data, even though the meaning of the strings is different.)
1781    .P
1782    The strings are returned in reverse order of length; that is, the longest
1783    matching string is given first. If there were too many matches to fit into
1784    \fIovector\fP, the yield of the function is zero, and the vector is filled with
1785    the longest matches.
1786    .
1787    .SS "Error returns from \fBpcre_dfa_exec()\fP"
1788    .rs
1789    .sp
1790    The \fBpcre_dfa_exec()\fP function returns a negative number when it fails.
1791    Many of the errors are the same as for \fBpcre_exec()\fP, and these are
1792    described
1793    .\" HTML <a href="#errorlist">
1794    .\" </a>
1795    above.
1796    .\"
1797    There are in addition the following errors that are specific to
1798    \fBpcre_dfa_exec()\fP:
1799    .sp
1800      PCRE_ERROR_DFA_UITEM      (-16)
1801    .sp
1802    This return is given if \fBpcre_dfa_exec()\fP encounters an item in the pattern
1803    that it does not support, for instance, the use of \eC or a back reference.
1804    .sp
1805      PCRE_ERROR_DFA_UCOND      (-17)
1806    .sp
1807    This return is given if \fBpcre_dfa_exec()\fP encounters a condition item that
1808    uses a back reference for the condition, or a test for recursion in a specific
1809    group. These are not supported.
1810    .sp
1811      PCRE_ERROR_DFA_UMLIMIT    (-18)
1812    .sp
1813    This return is given if \fBpcre_dfa_exec()\fP is called with an \fIextra\fP
1814    block that contains a setting of the \fImatch_limit\fP field. This is not
1815    supported (it is meaningless).
1816    .sp
1817      PCRE_ERROR_DFA_WSSIZE     (-19)
1818    .sp
1819    This return is given if \fBpcre_dfa_exec()\fP runs out of space in the
1820    \fIworkspace\fP vector.
1821    .sp
1822      PCRE_ERROR_DFA_RECURSE    (-20)
1823    .sp
1824    When a recursive subpattern is processed, the matching function calls itself
1825    recursively, using private vectors for \fIovector\fP and \fIworkspace\fP. This
1826    error is given if the output vector is not large enough. This should be
1827    extremely rare, as a vector of size 1000 is used.
1828    .
1829    .
1830    .SH "SEE ALSO"
1831    .rs
1832    .sp
1833    \fBpcrebuild\fP(3), \fBpcrecallout\fP(3), \fBpcrecpp(3)\fP(3),
1834    \fBpcrematching\fP(3), \fBpcrepartial\fP(3), \fBpcreposix\fP(3),
1835    \fBpcreprecompile\fP(3), \fBpcresample\fP(3), \fBpcrestack\fP(3).
1836    .
1837    .
1838    .SH AUTHOR
1839    .rs
1840    .sp
1841    .nf
1842    Philip Hazel
1843    University Computing Service
1844    Cambridge CB2 3QH, England.
1845    .fi
1846    .
1847    .
1848    .SH REVISION
1849    .rs
1850    .sp
1851    .nf
1852    Last updated: 16 April 2007
1853    Copyright (c) 1997-2007 University of Cambridge.
1854    .fi

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