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1  .TH PCREAPI 3  .TH PCREAPI 3 "29 October 2012" "PCRE 8.32"
2  .SH NAME  .SH NAME
3  PCRE - Perl-compatible regular expressions  PCRE - Perl-compatible regular expressions
 .SH "PCRE NATIVE API"  
 .rs  
4  .sp  .sp
5  .B #include <pcre.h>  .B #include <pcre.h>
6  .PP  .
7    .
8    .SH "PCRE NATIVE API BASIC FUNCTIONS"
9    .rs
10    .sp
11  .SM  .SM
12  .B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,  .B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,
13  .ti +5n  .ti +5n
# Line 25  PCRE - Perl-compatible regular expressio Line 27  PCRE - Perl-compatible regular expressio
27  .ti +5n  .ti +5n
28  .B const char **\fIerrptr\fP);  .B const char **\fIerrptr\fP);
29  .PP  .PP
30    .B void pcre_free_study(pcre_extra *\fIextra\fP);
31    .PP
32  .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"  .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
33  .ti +5n  .ti +5n
34  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
# Line 38  PCRE - Perl-compatible regular expressio Line 42  PCRE - Perl-compatible regular expressio
42  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,
43  .ti +5n  .ti +5n
44  .B int *\fIworkspace\fP, int \fIwscount\fP);  .B int *\fIworkspace\fP, int \fIwscount\fP);
45  .PP  .
46    .
47    .SH "PCRE NATIVE API STRING EXTRACTION FUNCTIONS"
48    .rs
49    .sp
50  .B int pcre_copy_named_substring(const pcre *\fIcode\fP,  .B int pcre_copy_named_substring(const pcre *\fIcode\fP,
51  .ti +5n  .ti +5n
52  .B const char *\fIsubject\fP, int *\fIovector\fP,  .B const char *\fIsubject\fP, int *\fIovector\fP,
# Line 82  PCRE - Perl-compatible regular expressio Line 90  PCRE - Perl-compatible regular expressio
90  .B void pcre_free_substring(const char *\fIstringptr\fP);  .B void pcre_free_substring(const char *\fIstringptr\fP);
91  .PP  .PP
92  .B void pcre_free_substring_list(const char **\fIstringptr\fP);  .B void pcre_free_substring_list(const char **\fIstringptr\fP);
93    .
94    .
95    .SH "PCRE NATIVE API AUXILIARY FUNCTIONS"
96    .rs
97    .sp
98    .B pcre_jit_stack *pcre_jit_stack_alloc(int \fIstartsize\fP, int \fImaxsize\fP);
99    .PP
100    .B void pcre_jit_stack_free(pcre_jit_stack *\fIstack\fP);
101    .PP
102    .B void pcre_assign_jit_stack(pcre_extra *\fIextra\fP,
103    .ti +5n
104    .B pcre_jit_callback \fIcallback\fP, void *\fIdata\fP);
105  .PP  .PP
106  .B const unsigned char *pcre_maketables(void);  .B const unsigned char *pcre_maketables(void);
107  .PP  .PP
# Line 89  PCRE - Perl-compatible regular expressio Line 109  PCRE - Perl-compatible regular expressio
109  .ti +5n  .ti +5n
110  .B int \fIwhat\fP, void *\fIwhere\fP);  .B int \fIwhat\fP, void *\fIwhere\fP);
111  .PP  .PP
 .B int pcre_info(const pcre *\fIcode\fP, int *\fIoptptr\fP, int  
 .B *\fIfirstcharptr\fP);  
 .PP  
112  .B int pcre_refcount(pcre *\fIcode\fP, int \fIadjust\fP);  .B int pcre_refcount(pcre *\fIcode\fP, int \fIadjust\fP);
113  .PP  .PP
114  .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);  .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
115  .PP  .PP
116  .B char *pcre_version(void);  .B const char *pcre_version(void);
117  .PP  .PP
118    .B int pcre_pattern_to_host_byte_order(pcre *\fIcode\fP,
119    .ti +5n
120    .B pcre_extra *\fIextra\fP, const unsigned char *\fItables\fP);
121    .
122    .
123    .SH "PCRE NATIVE API INDIRECTED FUNCTIONS"
124    .rs
125    .sp
126  .B void *(*pcre_malloc)(size_t);  .B void *(*pcre_malloc)(size_t);
127  .PP  .PP
128  .B void (*pcre_free)(void *);  .B void (*pcre_free)(void *);
# Line 109  PCRE - Perl-compatible regular expressio Line 134  PCRE - Perl-compatible regular expressio
134  .B int (*pcre_callout)(pcre_callout_block *);  .B int (*pcre_callout)(pcre_callout_block *);
135  .  .
136  .  .
137    .SH "PCRE 8-BIT, 16-BIT AND 32-BIT LIBRARIES"
138    .rs
139    .sp
140    From release 8.30, PCRE can be compiled as a library for handling 16-bit
141    character strings as well as, or instead of, the original library that handles
142    8-bit character strings. From release 8.32, PCRE can also be compiled as a
143    library for handling 32-bit character strings. To avoid too much complication,
144    this document describes the 8-bit versions of the functions, with only
145    occasional references to the 16-bit and 32-bit libraries.
146    .P
147    The 16-bit and 32-bit functions operate in the same way as their 8-bit
148    counterparts; they just use different data types for their arguments and
149    results, and their names start with \fBpcre16_\fP or \fBpcre32_\fP instead of
150    \fBpcre_\fP. For every option that has UTF8 in its name (for example,
151    PCRE_UTF8), there are corresponding 16-bit and 32-bit names with UTF8 replaced
152    by UTF16 or UTF32, respectively. This facility is in fact just cosmetic; the
153    16-bit and 32-bit option names define the same bit values.
154    .P
155    References to bytes and UTF-8 in this document should be read as references to
156    16-bit data quantities and UTF-16 when using the 16-bit library, or 32-bit data
157    quantities and UTF-32 when using the 32-bit library, unless specified
158    otherwise. More details of the specific differences for the 16-bit and 32-bit
159    libraries are given in the
160    .\" HREF
161    \fBpcre16\fP
162    .\"
163    and
164    .\" HREF
165    \fBpcre32\fP
166    .\"
167    pages.
168    .
169    .
170  .SH "PCRE API OVERVIEW"  .SH "PCRE API OVERVIEW"
171  .rs  .rs
172  .sp  .sp
173  PCRE has its own native API, which is described in this document. There are  PCRE has its own native API, which is described in this document. There are
174  also some wrapper functions that correspond to the POSIX regular expression  also some wrapper functions (for the 8-bit library only) that correspond to the
175  API. These are described in the  POSIX regular expression API, but they do not give access to all the
176    functionality. They are described in the
177  .\" HREF  .\" HREF
178  \fBpcreposix\fP  \fBpcreposix\fP
179  .\"  .\"
180  documentation. Both of these APIs define a set of C function calls. A C++  documentation. Both of these APIs define a set of C function calls. A C++
181  wrapper is distributed with PCRE. It is documented in the  wrapper (again for the 8-bit library only) is also distributed with PCRE. It is
182    documented in the
183  .\" HREF  .\" HREF
184  \fBpcrecpp\fP  \fBpcrecpp\fP
185  .\"  .\"
186  page.  page.
187  .P  .P
188  The native API C function prototypes are defined in the header file  The native API C function prototypes are defined in the header file
189  \fBpcre.h\fP, and on Unix systems the library itself is called \fBlibpcre\fP.  \fBpcre.h\fP, and on Unix-like systems the (8-bit) library itself is called
190  It can normally be accessed by adding \fB-lpcre\fP to the command for linking  \fBlibpcre\fP. It can normally be accessed by adding \fB-lpcre\fP to the
191  an application that uses PCRE. The header file defines the macros PCRE_MAJOR  command for linking an application that uses PCRE. The header file defines the
192  and PCRE_MINOR to contain the major and minor release numbers for the library.  macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release numbers
193  Applications can use these to include support for different releases of PCRE.  for the library. Applications can use these to include support for different
194    releases of PCRE.
195    .P
196    In a Windows environment, if you want to statically link an application program
197    against a non-dll \fBpcre.a\fP file, you must define PCRE_STATIC before
198    including \fBpcre.h\fP or \fBpcrecpp.h\fP, because otherwise the
199    \fBpcre_malloc()\fP and \fBpcre_free()\fP exported functions will be declared
200    \fB__declspec(dllimport)\fP, with unwanted results.
201  .P  .P
202  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,  The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,
203  and \fBpcre_exec()\fP are used for compiling and matching regular expressions  and \fBpcre_exec()\fP are used for compiling and matching regular expressions
204  in a Perl-compatible manner. A sample program that demonstrates the simplest  in a Perl-compatible manner. A sample program that demonstrates the simplest
205  way of using them is provided in the file called \fIpcredemo.c\fP in the source  way of using them is provided in the file called \fIpcredemo.c\fP in the PCRE
206  distribution. The  source distribution. A listing of this program is given in the
207    .\" HREF
208    \fBpcredemo\fP
209    .\"
210    documentation, and the
211  .\" HREF  .\" HREF
212  \fBpcresample\fP  \fBpcresample\fP
213  .\"  .\"
214  documentation describes how to run it.  documentation describes how to compile and run it.
215    .P
216    Just-in-time compiler support is an optional feature of PCRE that can be built
217    in appropriate hardware environments. It greatly speeds up the matching
218    performance of many patterns. Simple programs can easily request that it be
219    used if available, by setting an option that is ignored when it is not
220    relevant. More complicated programs might need to make use of the functions
221    \fBpcre_jit_stack_alloc()\fP, \fBpcre_jit_stack_free()\fP, and
222    \fBpcre_assign_jit_stack()\fP in order to control the JIT code's memory usage.
223    .P
224    From release 8.32 there is also a direct interface for JIT execution, which
225    gives improved performance. The JIT-specific functions are discussed in the
226    .\" HREF
227    \fBpcrejit\fP
228    .\"
229    documentation.
230  .P  .P
231  A second matching function, \fBpcre_dfa_exec()\fP, which is not  A second matching function, \fBpcre_dfa_exec()\fP, which is not
232  Perl-compatible, is also provided. This uses a different algorithm for the  Perl-compatible, is also provided. This uses a different algorithm for the
233  matching. The alternative algorithm finds all possible matches (at a given  matching. The alternative algorithm finds all possible matches (at a given
234  point in the subject), and scans the subject just once. However, this algorithm  point in the subject), and scans the subject just once (unless there are
235  does not return captured substrings. A description of the two matching  lookbehind assertions). However, this algorithm does not return captured
236  algorithms and their advantages and disadvantages is given in the  substrings. A description of the two matching algorithms and their advantages
237    and disadvantages is given in the
238  .\" HREF  .\" HREF
239  \fBpcrematching\fP  \fBpcrematching\fP
240  .\"  .\"
# Line 175  specialist use. Most commonly, no specia Line 262  specialist use. Most commonly, no specia
262  internal tables that are generated when PCRE is built are used.  internal tables that are generated when PCRE is built are used.
263  .P  .P
264  The function \fBpcre_fullinfo()\fP is used to find out information about a  The function \fBpcre_fullinfo()\fP is used to find out information about a
265  compiled pattern; \fBpcre_info()\fP is an obsolete version that returns only  compiled pattern. The function \fBpcre_version()\fP returns a pointer to a
266  some of the available information, but is retained for backwards compatibility.  string containing the version of PCRE and its date of release.
 The function \fBpcre_version()\fP returns a pointer to a string containing the  
 version of PCRE and its date of release.  
267  .P  .P
268  The function \fBpcre_refcount()\fP maintains a reference count in a data block  The function \fBpcre_refcount()\fP maintains a reference count in a data block
269  containing a compiled pattern. This is provided for the benefit of  containing a compiled pattern. This is provided for the benefit of
# Line 218  points during a matching operation. Deta Line 303  points during a matching operation. Deta
303  documentation.  documentation.
304  .  .
305  .  .
306    .\" HTML <a name="newlines"></a>
307  .SH NEWLINES  .SH NEWLINES
308  .rs  .rs
309  .sp  .sp
310  PCRE supports four different conventions for indicating line breaks in  PCRE supports five different conventions for indicating line breaks in
311  strings: a single CR (carriage return) character, a single LF (linefeed)  strings: a single CR (carriage return) character, a single LF (linefeed)
312  character, the two-character sequence CRLF, or any Unicode newline sequence.  character, the two-character sequence CRLF, any of the three preceding, or any
313  The Unicode newline sequences are the three just mentioned, plus the single  Unicode newline sequence. The Unicode newline sequences are the three just
314  characters VT (vertical tab, U+000B), FF (formfeed, U+000C), NEL (next line,  mentioned, plus the single characters VT (vertical tab, U+000B), FF (form feed,
315  U+0085), LS (line separator, U+2028), and PS (paragraph separator, U+2029).  U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
316    (paragraph separator, U+2029).
317  .P  .P
318  Each of the first three conventions is used by at least one operating system as  Each of the first three conventions is used by at least one operating system as
319  its standard newline sequence. When PCRE is built, a default can be specified.  its standard newline sequence. When PCRE is built, a default can be specified.
# Line 234  The default default is LF, which is the Line 321  The default default is LF, which is the
321  default can be overridden, either when a pattern is compiled, or when it is  default can be overridden, either when a pattern is compiled, or when it is
322  matched.  matched.
323  .P  .P
324    At compile time, the newline convention can be specified by the \fIoptions\fP
325    argument of \fBpcre_compile()\fP, or it can be specified by special text at the
326    start of the pattern itself; this overrides any other settings. See the
327    .\" HREF
328    \fBpcrepattern\fP
329    .\"
330    page for details of the special character sequences.
331    .P
332  In the PCRE documentation the word "newline" is used to mean "the character or  In the PCRE documentation the word "newline" is used to mean "the character or
333  pair of characters that indicate a line break". The choice of newline  pair of characters that indicate a line break". The choice of newline
334  convention affects the handling of the dot, circumflex, and dollar  convention affects the handling of the dot, circumflex, and dollar
335  metacharacters, the handling of #-comments in /x mode, and, when CRLF is a  metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
336  recognized line ending sequence, the match position advancement for a  recognized line ending sequence, the match position advancement for a
337  non-anchored pattern. The choice of newline convention does not affect the  non-anchored pattern. There is more detail about this in the
338  interpretation of the \en or \er escape sequences.  .\" HTML <a href="#execoptions">
339    .\" </a>
340    section on \fBpcre_exec()\fP options
341    .\"
342    below.
343    .P
344    The choice of newline convention does not affect the interpretation of
345    the \en or \er escape sequences, nor does it affect what \eR matches, which is
346    controlled in a similar way, but by separate options.
347  .  .
348  .  .
349  .SH MULTITHREADING  .SH MULTITHREADING
# Line 253  callout function pointed to by \fBpcre_c Line 356  callout function pointed to by \fBpcre_c
356  .P  .P
357  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
358  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.
359    .P
360    If the just-in-time optimization feature is being used, it needs separate
361    memory stack areas for each thread. See the
362    .\" HREF
363    \fBpcrejit\fP
364    .\"
365    documentation for more details.
366  .  .
367  .  .
368  .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"  .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"
# Line 264  which it was compiled. Details are given Line 374  which it was compiled. Details are given
374  .\" HREF  .\" HREF
375  \fBpcreprecompile\fP  \fBpcreprecompile\fP
376  .\"  .\"
377  documentation.  documentation, which includes a description of the
378    \fBpcre_pattern_to_host_byte_order()\fP function. However, compiling a regular
379    expression with one version of PCRE for use with a different version is not
380    guaranteed to work and may cause crashes.
381  .  .
382  .  .
383  .SH "CHECKING BUILD-TIME OPTIONS"  .SH "CHECKING BUILD-TIME OPTIONS"
# Line 281  documentation has more details about the Line 394  documentation has more details about the
394  .P  .P
395  The first argument for \fBpcre_config()\fP is an integer, specifying which  The first argument for \fBpcre_config()\fP is an integer, specifying which
396  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
397  which the information is placed. The following information is available:  which the information is placed. The returned value is zero on success, or the
398    negative error code PCRE_ERROR_BADOPTION if the value in the first argument is
399    not recognized. The following information is available:
400  .sp  .sp
401    PCRE_CONFIG_UTF8    PCRE_CONFIG_UTF8
402  .sp  .sp
403  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;
404  otherwise it is set to zero.  otherwise it is set to zero. This value should normally be given to the 8-bit
405    version of this function, \fBpcre_config()\fP. If it is given to the 16-bit
406    or 32-bit version of this function, the result is PCRE_ERROR_BADOPTION.
407    .sp
408      PCRE_CONFIG_UTF16
409    .sp
410    The output is an integer that is set to one if UTF-16 support is available;
411    otherwise it is set to zero. This value should normally be given to the 16-bit
412    version of this function, \fBpcre16_config()\fP. If it is given to the 8-bit
413    or 32-bit version of this function, the result is PCRE_ERROR_BADOPTION.
414    .sp
415      PCRE_CONFIG_UTF32
416    .sp
417    The output is an integer that is set to one if UTF-32 support is available;
418    otherwise it is set to zero. This value should normally be given to the 32-bit
419    version of this function, \fBpcre32_config()\fP. If it is given to the 8-bit
420    or 16-bit version of this function, the result is PCRE_ERROR_BADOPTION.
421  .sp  .sp
422    PCRE_CONFIG_UNICODE_PROPERTIES    PCRE_CONFIG_UNICODE_PROPERTIES
423  .sp  .sp
424  The output is an integer that is set to one if support for Unicode character  The output is an integer that is set to one if support for Unicode character
425  properties is available; otherwise it is set to zero.  properties is available; otherwise it is set to zero.
426  .sp  .sp
427      PCRE_CONFIG_JIT
428    .sp
429    The output is an integer that is set to one if support for just-in-time
430    compiling is available; otherwise it is set to zero.
431    .sp
432      PCRE_CONFIG_JITTARGET
433    .sp
434    The output is a pointer to a zero-terminated "const char *" string. If JIT
435    support is available, the string contains the name of the architecture for
436    which the JIT compiler is configured, for example "x86 32bit (little endian +
437    unaligned)". If JIT support is not available, the result is NULL.
438    .sp
439    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
440  .sp  .sp
441  The output is an integer whose value specifies the default character sequence  The output is an integer whose value specifies the default character sequence
442  that is recognized as meaning "newline". The four values that are supported  that is recognized as meaning "newline". The values that are supported in
443  are: 10 for LF, 13 for CR, 3338 for CRLF, and -1 for ANY. The default should  ASCII/Unicode environments are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for
444  normally be the standard sequence for your operating system.  ANYCRLF, and -1 for ANY. In EBCDIC environments, CR, ANYCRLF, and ANY yield the
445    same values. However, the value for LF is normally 21, though some EBCDIC
446    environments use 37. The corresponding values for CRLF are 3349 and 3365. The
447    default should normally correspond to the standard sequence for your operating
448    system.
449    .sp
450      PCRE_CONFIG_BSR
451    .sp
452    The output is an integer whose value indicates what character sequences the \eR
453    escape sequence matches by default. A value of 0 means that \eR matches any
454    Unicode line ending sequence; a value of 1 means that \eR matches only CR, LF,
455    or CRLF. The default can be overridden when a pattern is compiled or matched.
456  .sp  .sp
457    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
458  .sp  .sp
459  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
460  linkage in compiled regular expressions. The value is 2, 3, or 4. Larger values  linkage in compiled regular expressions. For the 8-bit library, the value can
461  allow larger regular expressions to be compiled, at the expense of slower  be 2, 3, or 4. For the 16-bit library, the value is either 2 or 4 and is still
462  matching. The default value of 2 is sufficient for all but the most massive  a number of bytes. For the 32-bit library, the value is either 2 or 4 and is
463  patterns, since it allows the compiled pattern to be up to 64K in size.  still a number of bytes. The default value of 2 is sufficient for all but the
464    most massive patterns, since it allows the compiled pattern to be up to 64K in
465    size. Larger values allow larger regular expressions to be compiled, at the
466    expense of slower matching.
467  .sp  .sp
468    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
469  .sp  .sp
# Line 320  documentation. Line 477  documentation.
477  .sp  .sp
478    PCRE_CONFIG_MATCH_LIMIT    PCRE_CONFIG_MATCH_LIMIT
479  .sp  .sp
480  The output is an integer that gives the default limit for the number of  The output is a long integer that gives the default limit for the number of
481  internal matching function calls in a \fBpcre_exec()\fP execution. Further  internal matching function calls in a \fBpcre_exec()\fP execution. Further
482  details are given with \fBpcre_exec()\fP below.  details are given with \fBpcre_exec()\fP below.
483  .sp  .sp
484    PCRE_CONFIG_MATCH_LIMIT_RECURSION    PCRE_CONFIG_MATCH_LIMIT_RECURSION
485  .sp  .sp
486  The output is an integer that gives the default limit for the depth of  The output is a long integer that gives the default limit for the depth of
487  recursion when calling the internal matching function in a \fBpcre_exec()\fP  recursion when calling the internal matching function in a \fBpcre_exec()\fP
488  execution. Further details are given with \fBpcre_exec()\fP below.  execution. Further details are given with \fBpcre_exec()\fP below.
489  .sp  .sp
# Line 361  avoiding the use of the stack. Line 518  avoiding the use of the stack.
518  Either of the functions \fBpcre_compile()\fP or \fBpcre_compile2()\fP can be  Either of the functions \fBpcre_compile()\fP or \fBpcre_compile2()\fP can be
519  called to compile a pattern into an internal form. The only difference between  called to compile a pattern into an internal form. The only difference between
520  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,
521  \fIerrorcodeptr\fP, via which a numerical error code can be returned.  \fIerrorcodeptr\fP, via which a numerical error code can be returned. To avoid
522    too much repetition, we refer just to \fBpcre_compile()\fP below, but the
523    information applies equally to \fBpcre_compile2()\fP.
524  .P  .P
525  The pattern is a C string terminated by a binary zero, and is passed in the  The pattern is a C string terminated by a binary zero, and is passed in the
526  \fIpattern\fP argument. A pointer to a single block of memory that is obtained  \fIpattern\fP argument. A pointer to a single block of memory that is obtained
# Line 377  argument, which is an address (see below Line 536  argument, which is an address (see below
536  .P  .P
537  The \fIoptions\fP argument contains various bit settings that affect the  The \fIoptions\fP argument contains various bit settings that affect the
538  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
539  options are described below. Some of them, in particular, those that are  options are described below. Some of them (in particular, those that are
540  compatible with Perl, can also be set and unset from within the pattern (see  compatible with Perl, but some others as well) can also be set and unset from
541  the detailed description in the  within the pattern (see the detailed description in the
542  .\" HREF  .\" HREF
543  \fBpcrepattern\fP  \fBpcrepattern\fP
544  .\"  .\"
545  documentation). For these options, the contents of the \fIoptions\fP argument  documentation). For those options that can be different in different parts of
546  specifies their initial settings at the start of compilation and execution. The  the pattern, the contents of the \fIoptions\fP argument specifies their
547  PCRE_ANCHORED and PCRE_NEWLINE_\fIxxx\fP options can be set at the time of  settings at the start of compilation and execution. The PCRE_ANCHORED,
548  matching as well as at compile time.  PCRE_BSR_\fIxxx\fP, PCRE_NEWLINE_\fIxxx\fP, PCRE_NO_UTF8_CHECK, and
549    PCRE_NO_START_OPTIMIZE options can be set at the time of matching as well as at
550    compile time.
551  .P  .P
552  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
553  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
554  NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual  NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual
555  error message. This is a static string that is part of the library. You must  error message. This is a static string that is part of the library. You must
556  not try to free it. The offset from the start of the pattern to the character  not try to free it. Normally, the offset from the start of the pattern to the
557  where the error was discovered is placed in the variable pointed to by  byte that was being processed when the error was discovered is placed in the
558  \fIerroffset\fP, which must not be NULL. If it is, an immediate error is given.  variable pointed to by \fIerroffset\fP, which must not be NULL (if it is, an
559    immediate error is given). However, for an invalid UTF-8 string, the offset is
560    that of the first byte of the failing character.
561    .P
562    Some errors are not detected until the whole pattern has been scanned; in these
563    cases, the offset passed back is the length of the pattern. Note that the
564    offset is in bytes, not characters, even in UTF-8 mode. It may sometimes point
565    into the middle of a UTF-8 character.
566  .P  .P
567  If \fBpcre_compile2()\fP is used instead of \fBpcre_compile()\fP, and the  If \fBpcre_compile2()\fP is used instead of \fBpcre_compile()\fP, and the
568  \fIerrorcodeptr\fP argument is not NULL, a non-zero error code number is  \fIerrorcodeptr\fP argument is not NULL, a non-zero error code number is
# Line 441  facility, see the Line 609  facility, see the
609  .\"  .\"
610  documentation.  documentation.
611  .sp  .sp
612      PCRE_BSR_ANYCRLF
613      PCRE_BSR_UNICODE
614    .sp
615    These options (which are mutually exclusive) control what the \eR escape
616    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
617    match any Unicode newline sequence. The default is specified when PCRE is
618    built. It can be overridden from within the pattern, or by setting an option
619    when a compiled pattern is matched.
620    .sp
621    PCRE_CASELESS    PCRE_CASELESS
622  .sp  .sp
623  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
# Line 464  pattern. Line 641  pattern.
641  .sp  .sp
642    PCRE_DOTALL    PCRE_DOTALL
643  .sp  .sp
644  If this bit is set, a dot metacharater in the pattern matches all characters,  If this bit is set, a dot metacharacter in the pattern matches a character of
645  including those that indicate newline. Without it, a dot does not match when  any value, including one that indicates a newline. However, it only ever
646  the current position is at a newline. This option is equivalent to Perl's /s  matches one character, even if newlines are coded as CRLF. Without this option,
647  option, and it can be changed within a pattern by a (?s) option setting. A  a dot does not match when the current position is at a newline. This option is
648  negative class such as [^a] always matches newline characters, independent of  equivalent to Perl's /s option, and it can be changed within a pattern by a
649  the setting of this option.  (?s) option setting. A negative class such as [^a] always matches newline
650    characters, independent of the setting of this option.
651  .sp  .sp
652    PCRE_DUPNAMES    PCRE_DUPNAMES
653  .sp  .sp
# Line 484  documentation. Line 662  documentation.
662  .sp  .sp
663    PCRE_EXTENDED    PCRE_EXTENDED
664  .sp  .sp
665  If this bit is set, whitespace data characters in the pattern are totally  If this bit is set, white space data characters in the pattern are totally
666  ignored except when escaped or inside a character class. Whitespace does not  ignored except when escaped or inside a character class. White space does not
667  include the VT character (code 11). In addition, characters between an  include the VT character (code 11). In addition, characters between an
668  unescaped # outside a character class and the next newline, inclusive, are also  unescaped # outside a character class and the next newline, inclusive, are also
669  ignored. This is equivalent to Perl's /x option, and it can be changed within a  ignored. This is equivalent to Perl's /x option, and it can be changed within a
670  pattern by a (?x) option setting.  pattern by a (?x) option setting.
671  .P  .P
672    Which characters are interpreted as newlines is controlled by the options
673    passed to \fBpcre_compile()\fP or by a special sequence at the start of the
674    pattern, as described in the section entitled
675    .\" HTML <a href="pcrepattern.html#newlines">
676    .\" </a>
677    "Newline conventions"
678    .\"
679    in the \fBpcrepattern\fP documentation. Note that the end of this type of
680    comment is a literal newline sequence in the pattern; escape sequences that
681    happen to represent a newline do not count.
682    .P
683  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
684  Note, however, that this applies only to data characters. Whitespace characters  Note, however, that this applies only to data characters. White space characters
685  may never appear within special character sequences in a pattern, for example  may never appear within special character sequences in a pattern, for example
686  within the sequence (?( which introduces a conditional subpattern.  within the sequence (?( that introduces a conditional subpattern.
687  .sp  .sp
688    PCRE_EXTRA    PCRE_EXTRA
689  .sp  .sp
# Line 504  set, any backslash in a pattern that is Line 693  set, any backslash in a pattern that is
693  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
694  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
695  special meaning is treated as a literal. (Perl can, however, be persuaded to  special meaning is treated as a literal. (Perl can, however, be persuaded to
696  give a warning for this.) There are at present no other features controlled by  give an error for this, by running it with the -w option.) There are at present
697  this option. It can also be set by a (?X) option setting within a pattern.  no other features controlled by this option. It can also be set by a (?X)
698    option setting within a pattern.
699  .sp  .sp
700    PCRE_FIRSTLINE    PCRE_FIRSTLINE
701  .sp  .sp
# Line 513  If this option is set, an unanchored pat Line 703  If this option is set, an unanchored pat
703  the first newline in the subject string, though the matched text may continue  the first newline in the subject string, though the matched text may continue
704  over the newline.  over the newline.
705  .sp  .sp
706      PCRE_JAVASCRIPT_COMPAT
707    .sp
708    If this option is set, PCRE's behaviour is changed in some ways so that it is
709    compatible with JavaScript rather than Perl. The changes are as follows:
710    .P
711    (1) A lone closing square bracket in a pattern causes a compile-time error,
712    because this is illegal in JavaScript (by default it is treated as a data
713    character). Thus, the pattern AB]CD becomes illegal when this option is set.
714    .P
715    (2) At run time, a back reference to an unset subpattern group matches an empty
716    string (by default this causes the current matching alternative to fail). A
717    pattern such as (\e1)(a) succeeds when this option is set (assuming it can find
718    an "a" in the subject), whereas it fails by default, for Perl compatibility.
719    .P
720    (3) \eU matches an upper case "U" character; by default \eU causes a compile
721    time error (Perl uses \eU to upper case subsequent characters).
722    .P
723    (4) \eu matches a lower case "u" character unless it is followed by four
724    hexadecimal digits, in which case the hexadecimal number defines the code point
725    to match. By default, \eu causes a compile time error (Perl uses it to upper
726    case the following character).
727    .P
728    (5) \ex matches a lower case "x" character unless it is followed by two
729    hexadecimal digits, in which case the hexadecimal number defines the code point
730    to match. By default, as in Perl, a hexadecimal number is always expected after
731    \ex, but it may have zero, one, or two digits (so, for example, \exz matches a
732    binary zero character followed by z).
733    .sp
734    PCRE_MULTILINE    PCRE_MULTILINE
735  .sp  .sp
736  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
# Line 532  occurrences of ^ or $ in a pattern, sett Line 750  occurrences of ^ or $ in a pattern, sett
750    PCRE_NEWLINE_CR    PCRE_NEWLINE_CR
751    PCRE_NEWLINE_LF    PCRE_NEWLINE_LF
752    PCRE_NEWLINE_CRLF    PCRE_NEWLINE_CRLF
753      PCRE_NEWLINE_ANYCRLF
754    PCRE_NEWLINE_ANY    PCRE_NEWLINE_ANY
755  .sp  .sp
756  These options override the default newline definition that was chosen when PCRE  These options override the default newline definition that was chosen when PCRE
757  was built. Setting the first or the second specifies that a newline is  was built. Setting the first or the second specifies that a newline is
758  indicated by a single character (CR or LF, respectively). Setting  indicated by a single character (CR or LF, respectively). Setting
759  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
760  CRLF sequence. Setting PCRE_NEWLINE_ANY specifies that any Unicode newline  CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three
761  sequence should be recognized. The Unicode newline sequences are the three just  preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies
762  mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed,  that any Unicode newline sequence should be recognized.
763  U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS  .P
764  (paragraph separator, U+2029). The last two are recognized only in UTF-8 mode.  In an ASCII/Unicode environment, the Unicode newline sequences are the three
765    just mentioned, plus the single characters VT (vertical tab, U+000B), FF (form
766    feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
767    (paragraph separator, U+2029). For the 8-bit library, the last two are
768    recognized only in UTF-8 mode.
769    .P
770    When PCRE is compiled to run in an EBCDIC (mainframe) environment, the code for
771    CR is 0x0d, the same as ASCII. However, the character code for LF is normally
772    0x15, though in some EBCDIC environments 0x25 is used. Whichever of these is
773    not LF is made to correspond to Unicode's NEL character. EBCDIC codes are all
774    less than 256. For more details, see the
775    .\" HREF
776    \fBpcrebuild\fP
777    .\"
778    documentation.
779  .P  .P
780  The newline setting in the options word uses three bits that are treated  The newline setting in the options word uses three bits that are treated
781  as a number, giving eight possibilities. Currently only five are used (default  as a number, giving eight possibilities. Currently only six are used (default
782  plus the four values above). This means that if you set more than one newline  plus the five values above). This means that if you set more than one newline
783  option, the combination may or may not be sensible. For example,  option, the combination may or may not be sensible. For example,
784  PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but  PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
785  other combinations yield unused numbers and cause an error.  other combinations may yield unused numbers and cause an error.
786  .P  .P
787  The only time that a line break is specially recognized when compiling a  The only time that a line break in a pattern is specially recognized when
788  pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character  compiling is when PCRE_EXTENDED is set. CR and LF are white space characters,
789  class is encountered. This indicates a comment that lasts until after the next  and so are ignored in this mode. Also, an unescaped # outside a character class
790  line break sequence. In other circumstances, line break sequences are treated  indicates a comment that lasts until after the next line break sequence. In
791  as literal data, except that in PCRE_EXTENDED mode, both CR and LF are treated  other circumstances, line break sequences in patterns are treated as literal
792  as whitespace characters and are therefore ignored.  data.
793  .P  .P
794  The newline option that is set at compile time becomes the default that is used  The newline option that is set at compile time becomes the default that is used
795  for \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, but it can be overridden.  for \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, but it can be overridden.
# Line 569  were followed by ?: but named parenthese Line 802  were followed by ?: but named parenthese
802  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
803  in Perl.  in Perl.
804  .sp  .sp
805      NO_START_OPTIMIZE
806    .sp
807    This is an option that acts at matching time; that is, it is really an option
808    for \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. If it is set at compile time,
809    it is remembered with the compiled pattern and assumed at matching time. For
810    details see the discussion of PCRE_NO_START_OPTIMIZE
811    .\" HTML <a href="#execoptions">
812    .\" </a>
813    below.
814    .\"
815    .sp
816      PCRE_UCP
817    .sp
818    This option changes the way PCRE processes \eB, \eb, \eD, \ed, \eS, \es, \eW,
819    \ew, and some of the POSIX character classes. By default, only ASCII characters
820    are recognized, but if PCRE_UCP is set, Unicode properties are used instead to
821    classify characters. More details are given in the section on
822    .\" HTML <a href="pcre.html#genericchartypes">
823    .\" </a>
824    generic character types
825    .\"
826    in the
827    .\" HREF
828    \fBpcrepattern\fP
829    .\"
830    page. If you set PCRE_UCP, matching one of the items it affects takes much
831    longer. The option is available only if PCRE has been compiled with Unicode
832    property support.
833    .sp
834    PCRE_UNGREEDY    PCRE_UNGREEDY
835  .sp  .sp
836  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
# Line 578  with Perl. It can also be set by a (?U) Line 840  with Perl. It can also be set by a (?U)
840    PCRE_UTF8    PCRE_UTF8
841  .sp  .sp
842  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
843  of UTF-8 characters instead of single-byte character strings. However, it is  of UTF-8 characters instead of single-byte strings. However, it is available
844  available only when PCRE is built to include UTF-8 support. If not, the use  only when PCRE is built to include UTF support. If not, the use of this option
845  of this option provokes an error. Details of how this option changes the  provokes an error. Details of how this option changes the behaviour of PCRE are
846  behaviour of PCRE are given in the  given in the
 .\" HTML <a href="pcre.html#utf8support">  
 .\" </a>  
 section on UTF-8 support  
 .\"  
 in the main  
847  .\" HREF  .\" HREF
848  \fBpcre\fP  \fBpcreunicode\fP
849  .\"  .\"
850  page.  page.
851  .sp  .sp
852    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
853  .sp  .sp
854  When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is  When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
855  automatically checked. If an invalid UTF-8 sequence of bytes is found,  automatically checked. There is a discussion about the
856  \fBpcre_compile()\fP returns an error. If you already know that your pattern is  .\" HTML <a href="pcreunicode.html#utf8strings">
857  valid, and you want to skip this check for performance reasons, you can set the  .\" </a>
858  PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid  validity of UTF-8 strings
859  UTF-8 string as a pattern is undefined. It may cause your program to crash.  .\"
860  Note that this option can also be passed to \fBpcre_exec()\fP and  in the
861  \fBpcre_dfa_exec()\fP, to suppress the UTF-8 validity checking of subject  .\" HREF
862  strings.  \fBpcreunicode\fP
863    .\"
864    page. If an invalid UTF-8 sequence is found, \fBpcre_compile()\fP returns an
865    error. If you already know that your pattern is valid, and you want to skip
866    this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK option.
867    When it is set, the effect of passing an invalid UTF-8 string as a pattern is
868    undefined. It may cause your program to crash. Note that this option can also
869    be passed to \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, to suppress the
870    validity checking of subject strings only. If the same string is being matched
871    many times, the option can be safely set for the second and subsequent
872    matchings to improve performance.
873  .  .
874  .  .
875  .SH "COMPILATION ERROR CODES"  .SH "COMPILATION ERROR CODES"
# Line 610  strings. Line 877  strings.
877  .sp  .sp
878  The following table lists the error codes than may be returned by  The following table lists the error codes than may be returned by
879  \fBpcre_compile2()\fP, along with the error messages that may be returned by  \fBpcre_compile2()\fP, along with the error messages that may be returned by
880  both compiling functions. As PCRE has developed, some error codes have fallen  both compiling functions. Note that error messages are always 8-bit ASCII
881  out of use. To avoid confusion, they have not been re-used.  strings, even in 16-bit or 32-bit mode. As PCRE has developed, some error codes
882    have fallen out of use. To avoid confusion, they have not been re-used.
883  .sp  .sp
884     0  no error     0  no error
885     1  \e at end of pattern     1  \e at end of pattern
# Line 625  out of use. To avoid confusion, they hav Line 893  out of use. To avoid confusion, they hav
893     9  nothing to repeat     9  nothing to repeat
894    10  [this code is not in use]    10  [this code is not in use]
895    11  internal error: unexpected repeat    11  internal error: unexpected repeat
896    12  unrecognized character after (?    12  unrecognized character after (? or (?-
897    13  POSIX named classes are supported only within a class    13  POSIX named classes are supported only within a class
898    14  missing )    14  missing )
899    15  reference to non-existent subpattern    15  reference to non-existent subpattern
# Line 633  out of use. To avoid confusion, they hav Line 901  out of use. To avoid confusion, they hav
901    17  unknown option bit(s) set    17  unknown option bit(s) set
902    18  missing ) after comment    18  missing ) after comment
903    19  [this code is not in use]    19  [this code is not in use]
904    20  regular expression too large    20  regular expression is too large
905    21  failed to get memory    21  failed to get memory
906    22  unmatched parentheses    22  unmatched parentheses
907    23  internal error: code overflow    23  internal error: code overflow
# Line 642  out of use. To avoid confusion, they hav Line 910  out of use. To avoid confusion, they hav
910    26  malformed number or name after (?(    26  malformed number or name after (?(
911    27  conditional group contains more than two branches    27  conditional group contains more than two branches
912    28  assertion expected after (?(    28  assertion expected after (?(
913    29  (?R or (?digits must be followed by )    29  (?R or (?[+-]digits must be followed by )
914    30  unknown POSIX class name    30  unknown POSIX class name
915    31  POSIX collating elements are not supported    31  POSIX collating elements are not supported
916    32  this version of PCRE is not compiled with PCRE_UTF8 support    32  this version of PCRE is compiled without UTF support
917    33  [this code is not in use]    33  [this code is not in use]
918    34  character value in \ex{...} sequence is too large    34  character value in \ex{...} sequence is too large
919    35  invalid condition (?(0)    35  invalid condition (?(0)
920    36  \eC not allowed in lookbehind assertion    36  \eC not allowed in lookbehind assertion
921    37  PCRE does not support \eL, \el, \eN, \eU, or \eu    37  PCRE does not support \eL, \el, \eN{name}, \eU, or \eu
922    38  number after (?C is > 255    38  number after (?C is > 255
923    39  closing ) for (?C expected    39  closing ) for (?C expected
924    40  recursive call could loop indefinitely    40  recursive call could loop indefinitely
925    41  unrecognized character after (?P    41  unrecognized character after (?P
926    42  syntax error in subpattern name (missing terminator)    42  syntax error in subpattern name (missing terminator)
927    43  two named subpatterns have the same name    43  two named subpatterns have the same name
928    44  invalid UTF-8 string    44  invalid UTF-8 string (specifically UTF-8)
929    45  support for \eP, \ep, and \eX has not been compiled    45  support for \eP, \ep, and \eX has not been compiled
930    46  malformed \eP or \ep sequence    46  malformed \eP or \ep sequence
931    47  unknown property name after \eP or \ep    47  unknown property name after \eP or \ep
932    48  subpattern name is too long (maximum 32 characters)    48  subpattern name is too long (maximum 32 characters)
933    49  too many named subpatterns (maximum 10,000)    49  too many named subpatterns (maximum 10000)
934    50  repeated subpattern is too long    50  [this code is not in use]
935    51  octal value is greater than \e377 (not in UTF-8 mode)    51  octal value is greater than \e377 in 8-bit non-UTF-8 mode
936    52  internal error: overran compiling workspace    52  internal error: overran compiling workspace
937    53  internal error: previously-checked referenced subpattern not found    53  internal error: previously-checked referenced subpattern
938            not found
939    54  DEFINE group contains more than one branch    54  DEFINE group contains more than one branch
940    55  repeating a DEFINE group is not allowed    55  repeating a DEFINE group is not allowed
941    56  inconsistent NEWLINE options"    56  inconsistent NEWLINE options
942      57  \eg is not followed by a braced, angle-bracketed, or quoted
943            name/number or by a plain number
944      58  a numbered reference must not be zero
945      59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
946      60  (*VERB) not recognized
947      61  number is too big
948      62  subpattern name expected
949      63  digit expected after (?+
950      64  ] is an invalid data character in JavaScript compatibility mode
951      65  different names for subpatterns of the same number are
952            not allowed
953      66  (*MARK) must have an argument
954      67  this version of PCRE is not compiled with Unicode property
955            support
956      68  \ec must be followed by an ASCII character
957      69  \ek is not followed by a braced, angle-bracketed, or quoted name
958      70  internal error: unknown opcode in find_fixedlength()
959      71  \eN is not supported in a class
960      72  too many forward references
961      73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
962      74  invalid UTF-16 string (specifically UTF-16)
963      75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
964      76  character value in \eu.... sequence is too large
965      77  invalid UTF-32 string (specifically UTF-32)
966    .sp
967    The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
968    be used if the limits were changed when PCRE was built.
969  .  .
970  .  .
971    .\" HTML <a name="studyingapattern"></a>
972  .SH "STUDYING A PATTERN"  .SH "STUDYING A PATTERN"
973  .rs  .rs
974  .sp  .sp
# Line 688  help speed up matching, \fBpcre_study()\ Line 985  help speed up matching, \fBpcre_study()\
985  results of the study.  results of the study.
986  .P  .P
987  The returned value from \fBpcre_study()\fP can be passed directly to  The returned value from \fBpcre_study()\fP can be passed directly to
988  \fBpcre_exec()\fP. However, a \fBpcre_extra\fP block also contains other  \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. However, a \fBpcre_extra\fP block
989  fields that can be set by the caller before the block is passed; these are  also contains other fields that can be set by the caller before the block is
990  described  passed; these are described
991  .\" HTML <a href="#extradata">  .\" HTML <a href="#extradata">
992  .\" </a>  .\" </a>
993  below  below
994  .\"  .\"
995  in the section on matching a pattern.  in the section on matching a pattern.
996  .P  .P
997  If studying the pattern does not produce any additional information  If studying the pattern does not produce any useful information,
998  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program  \fBpcre_study()\fP returns NULL by default. In that circumstance, if the
999  wants to pass any of the other fields to \fBpcre_exec()\fP, it must set up its  calling program wants to pass any of the other fields to \fBpcre_exec()\fP or
1000  own \fBpcre_extra\fP block.  \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block. However,
1001  .P  if \fBpcre_study()\fP is called with the PCRE_STUDY_EXTRA_NEEDED option, it
1002  The second argument of \fBpcre_study()\fP contains option bits. At present, no  returns a \fBpcre_extra\fP block even if studying did not find any additional
1003  options are defined, and this argument should always be zero.  information. It may still return NULL, however, if an error occurs in
1004    \fBpcre_study()\fP.
1005    .P
1006    The second argument of \fBpcre_study()\fP contains option bits. There are three
1007    further options in addition to PCRE_STUDY_EXTRA_NEEDED:
1008    .sp
1009      PCRE_STUDY_JIT_COMPILE
1010      PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
1011      PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
1012    .sp
1013    If any of these are set, and the just-in-time compiler is available, the
1014    pattern is further compiled into machine code that executes much faster than
1015    the \fBpcre_exec()\fP interpretive matching function. If the just-in-time
1016    compiler is not available, these options are ignored. All undefined bits in the
1017    \fIoptions\fP argument must be zero.
1018    .P
1019    JIT compilation is a heavyweight optimization. It can take some time for
1020    patterns to be analyzed, and for one-off matches and simple patterns the
1021    benefit of faster execution might be offset by a much slower study time.
1022    Not all patterns can be optimized by the JIT compiler. For those that cannot be
1023    handled, matching automatically falls back to the \fBpcre_exec()\fP
1024    interpreter. For more details, see the
1025    .\" HREF
1026    \fBpcrejit\fP
1027    .\"
1028    documentation.
1029  .P  .P
1030  The third argument for \fBpcre_study()\fP is a pointer for an error message. If  The third argument for \fBpcre_study()\fP is a pointer for an error message. If
1031  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
# Line 712  static string that is part of the librar Line 1034  static string that is part of the librar
1034  should test the error pointer for NULL after calling \fBpcre_study()\fP, to be  should test the error pointer for NULL after calling \fBpcre_study()\fP, to be
1035  sure that it has run successfully.  sure that it has run successfully.
1036  .P  .P
1037  This is a typical call to \fBpcre_study\fP():  When you are finished with a pattern, you can free the memory used for the
1038    study data by calling \fBpcre_free_study()\fP. This function was added to the
1039    API for release 8.20. For earlier versions, the memory could be freed with
1040    \fBpcre_free()\fP, just like the pattern itself. This will still work in cases
1041    where JIT optimization is not used, but it is advisable to change to the new
1042    function when convenient.
1043    .P
1044    This is a typical way in which \fBpcre_study\fP() is used (except that in a
1045    real application there should be tests for errors):
1046  .sp  .sp
1047    pcre_extra *pe;    int rc;
1048    pe = pcre_study(    pcre *re;
1049      pcre_extra *sd;
1050      re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
1051      sd = pcre_study(
1052      re,             /* result of pcre_compile() */      re,             /* result of pcre_compile() */
1053      0,              /* no options exist */      0,              /* no options */
1054      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
1055  .sp    rc = pcre_exec(   /* see below for details of pcre_exec() options */
1056  At present, studying a pattern is useful only for non-anchored patterns that do      re, sd, "subject", 7, 0, 0, ovector, 30);
1057  not have a single fixed starting character. A bitmap of possible starting    ...
1058  bytes is created.    pcre_free_study(sd);
1059      pcre_free(re);
1060    .sp
1061    Studying a pattern does two things: first, a lower bound for the length of
1062    subject string that is needed to match the pattern is computed. This does not
1063    mean that there are any strings of that length that match, but it does
1064    guarantee that no shorter strings match. The value is used to avoid wasting
1065    time by trying to match strings that are shorter than the lower bound. You can
1066    find out the value in a calling program via the \fBpcre_fullinfo()\fP function.
1067    .P
1068    Studying a pattern is also useful for non-anchored patterns that do not have a
1069    single fixed starting character. A bitmap of possible starting bytes is
1070    created. This speeds up finding a position in the subject at which to start
1071    matching. (In 16-bit mode, the bitmap is used for 16-bit values less than 256.
1072    In 32-bit mode, the bitmap is used for 32-bit values less than 256.)
1073    .P
1074    These two optimizations apply to both \fBpcre_exec()\fP and
1075    \fBpcre_dfa_exec()\fP, and the information is also used by the JIT compiler.
1076    The optimizations can be disabled by setting the PCRE_NO_START_OPTIMIZE option
1077    when calling \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP, but if this is done,
1078    JIT execution is also disabled. You might want to do this if your pattern
1079    contains callouts or (*MARK) and you want to make use of these facilities in
1080    cases where matching fails. See the discussion of PCRE_NO_START_OPTIMIZE
1081    .\" HTML <a href="#execoptions">
1082    .\" </a>
1083    below.
1084    .\"
1085  .  .
1086  .  .
1087  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
1088  .SH "LOCALE SUPPORT"  .SH "LOCALE SUPPORT"
1089  .rs  .rs
1090  .sp  .sp
1091  PCRE handles caseless matching, and determines whether characters are letters  PCRE handles caseless matching, and determines whether characters are letters,
1092  digits, or whatever, by reference to a set of tables, indexed by character  digits, or whatever, by reference to a set of tables, indexed by character
1093  value. When running in UTF-8 mode, this applies only to characters with codes  value. When running in UTF-8 mode, this applies only to characters
1094  less than 128. Higher-valued codes never match escapes such as \ew or \ed, but  with codes less than 128. By default, higher-valued codes never match escapes
1095  can be tested with \ep if PCRE is built with Unicode character property  such as \ew or \ed, but they can be tested with \ep if PCRE is built with
1096  support. The use of locales with Unicode is discouraged.  Unicode character property support. Alternatively, the PCRE_UCP option can be
1097  .P  set at compile time; this causes \ew and friends to use Unicode property
1098  An internal set of tables is created in the default C locale when PCRE is  support instead of built-in tables. The use of locales with Unicode is
1099  built. This is used when the final argument of \fBpcre_compile()\fP is NULL,  discouraged. If you are handling characters with codes greater than 128, you
1100  and is sufficient for many applications. An alternative set of tables can,  should either use UTF-8 and Unicode, or use locales, but not try to mix the
1101  however, be supplied. These may be created in a different locale from the  two.
1102  default. As more and more applications change to using Unicode, the need for  .P
1103  this locale support is expected to die away.  PCRE contains an internal set of tables that are used when the final argument
1104    of \fBpcre_compile()\fP is NULL. These are sufficient for many applications.
1105    Normally, the internal tables recognize only ASCII characters. However, when
1106    PCRE is built, it is possible to cause the internal tables to be rebuilt in the
1107    default "C" locale of the local system, which may cause them to be different.
1108    .P
1109    The internal tables can always be overridden by tables supplied by the
1110    application that calls PCRE. These may be created in a different locale from
1111    the default. As more and more applications change to using Unicode, the need
1112    for this locale support is expected to die away.
1113  .P  .P
1114  External tables are built by calling the \fBpcre_maketables()\fP function,  External tables are built by calling the \fBpcre_maketables()\fP function,
1115  which has no arguments, in the relevant locale. The result can then be passed  which has no arguments, in the relevant locale. The result can then be passed
# Line 754  the following code could be used: Line 1122  the following code could be used:
1122    tables = pcre_maketables();    tables = pcre_maketables();
1123    re = pcre_compile(..., tables);    re = pcre_compile(..., tables);
1124  .sp  .sp
1125    The locale name "fr_FR" is used on Linux and other Unix-like systems; if you
1126    are using Windows, the name for the French locale is "french".
1127    .P
1128  When \fBpcre_maketables()\fP runs, the tables are built in memory that is  When \fBpcre_maketables()\fP runs, the tables are built in memory that is
1129  obtained via \fBpcre_malloc\fP. It is the caller's responsibility to ensure  obtained via \fBpcre_malloc\fP. It is the caller's responsibility to ensure
1130  that the memory containing the tables remains available for as long as it is  that the memory containing the tables remains available for as long as it is
# Line 772  one in which it was compiled. Passing ta Line 1143  one in which it was compiled. Passing ta
1143  below in the section on matching a pattern.  below in the section on matching a pattern.
1144  .  .
1145  .  .
1146    .\" HTML <a name="infoaboutpattern"></a>
1147  .SH "INFORMATION ABOUT A PATTERN"  .SH "INFORMATION ABOUT A PATTERN"
1148  .rs  .rs
1149  .sp  .sp
# Line 780  below in the section on matching a patte Line 1152  below in the section on matching a patte
1152  .B int \fIwhat\fP, void *\fIwhere\fP);  .B int \fIwhat\fP, void *\fIwhere\fP);
1153  .PP  .PP
1154  The \fBpcre_fullinfo()\fP function returns information about a compiled  The \fBpcre_fullinfo()\fP function returns information about a compiled
1155  pattern. It replaces the obsolete \fBpcre_info()\fP function, which is  pattern. It replaces the \fBpcre_info()\fP function, which was removed from the
1156  nevertheless retained for backwards compability (and is documented below).  library at version 8.30, after more than 10 years of obsolescence.
1157  .P  .P
1158  The first argument for \fBpcre_fullinfo()\fP is a pointer to the compiled  The first argument for \fBpcre_fullinfo()\fP is a pointer to the compiled
1159  pattern. The second argument is the result of \fBpcre_study()\fP, or NULL if  pattern. The second argument is the result of \fBpcre_study()\fP, or NULL if
# Line 790  information is required, and the fourth Line 1162  information is required, and the fourth
1162  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
1163  the following negative numbers:  the following negative numbers:
1164  .sp  .sp
1165    PCRE_ERROR_NULL       the argument \fIcode\fP was NULL    PCRE_ERROR_NULL           the argument \fIcode\fP was NULL
1166                          the argument \fIwhere\fP was NULL                              the argument \fIwhere\fP was NULL
1167    PCRE_ERROR_BADMAGIC   the "magic number" was not found    PCRE_ERROR_BADMAGIC       the "magic number" was not found
1168    PCRE_ERROR_BADOPTION  the value of \fIwhat\fP was invalid    PCRE_ERROR_BADENDIANNESS  the pattern was compiled with different
1169                                endianness
1170      PCRE_ERROR_BADOPTION      the value of \fIwhat\fP was invalid
1171  .sp  .sp
1172  The "magic number" is placed at the start of each compiled pattern as an simple  The "magic number" is placed at the start of each compiled pattern as an simple
1173  check against passing an arbitrary memory pointer. Here is a typical call of  check against passing an arbitrary memory pointer. The endianness error can
1174  \fBpcre_fullinfo()\fP, to obtain the length of the compiled pattern:  occur if a compiled pattern is saved and reloaded on a different host. Here is
1175    a typical call of \fBpcre_fullinfo()\fP, to obtain the length of the compiled
1176    pattern:
1177  .sp  .sp
1178    int rc;    int rc;
1179    size_t length;    size_t length;
1180    rc = pcre_fullinfo(    rc = pcre_fullinfo(
1181      re,               /* result of pcre_compile() */      re,               /* result of pcre_compile() */
1182      pe,               /* result of pcre_study(), or NULL */      sd,               /* result of pcre_study(), or NULL */
1183      PCRE_INFO_SIZE,   /* what is required */      PCRE_INFO_SIZE,   /* what is required */
1184      &length);         /* where to put the data */      &length);         /* where to put the data */
1185  .sp  .sp
# Line 831  a NULL table pointer. Line 1207  a NULL table pointer.
1207  .sp  .sp
1208    PCRE_INFO_FIRSTBYTE    PCRE_INFO_FIRSTBYTE
1209  .sp  .sp
1210  Return information about the first byte of any matched string, for a  Return information about the first data unit of any matched string, for a
1211  non-anchored pattern. The fourth argument should point to an \fBint\fP  non-anchored pattern. (The name of this option refers to the 8-bit library,
1212  variable. (This option used to be called PCRE_INFO_FIRSTCHAR; the old name is  where data units are bytes.) The fourth argument should point to an \fBint\fP
1213  still recognized for backwards compatibility.)  variable.
1214    .P
1215    If there is a fixed first value, for example, the letter "c" from a pattern
1216    such as (cat|cow|coyote), its value is returned. In the 8-bit library, the
1217    value is always less than 256. In the 16-bit library the value can be up to
1218    0xffff. In the 32-bit library the value can be up to 0x10ffff.
1219  .P  .P
1220  If there is a fixed first byte, for example, from a pattern such as  If there is no fixed first value, and if either
 (cat|cow|coyote), its value is returned. Otherwise, if either  
1221  .sp  .sp
1222  (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
1223  starts with "^", or  starts with "^", or
# Line 848  starts with "^", or Line 1228  starts with "^", or
1228  -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
1229  subject string or after any newline within the string. Otherwise -2 is  subject string or after any newline within the string. Otherwise -2 is
1230  returned. For anchored patterns, -2 is returned.  returned. For anchored patterns, -2 is returned.
1231    .P
1232    Since for the 32-bit library using the non-UTF-32 mode, this function is unable
1233    to return the full 32-bit range of the character, this value is deprecated;
1234    instead the PCRE_INFO_FIRSTCHARACTERFLAGS and PCRE_INFO_FIRSTCHARACTER values
1235    should be used.
1236  .sp  .sp
1237    PCRE_INFO_FIRSTTABLE    PCRE_INFO_FIRSTTABLE
1238  .sp  .sp
1239  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
1240  table indicating a fixed set of bytes for the first byte in any matching  table indicating a fixed set of values for the first data unit in any matching
1241  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
1242  fourth argument should point to an \fBunsigned char *\fP variable.  fourth argument should point to an \fBunsigned char *\fP variable.
1243  .sp  .sp
1244      PCRE_INFO_HASCRORLF
1245    .sp
1246    Return 1 if the pattern contains any explicit matches for CR or LF characters,
1247    otherwise 0. The fourth argument should point to an \fBint\fP variable. An
1248    explicit match is either a literal CR or LF character, or \er or \en.
1249    .sp
1250      PCRE_INFO_JCHANGED
1251    .sp
1252    Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise
1253    0. The fourth argument should point to an \fBint\fP variable. (?J) and
1254    (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
1255    .sp
1256      PCRE_INFO_JIT
1257    .sp
1258    Return 1 if the pattern was studied with one of the JIT options, and
1259    just-in-time compiling was successful. The fourth argument should point to an
1260    \fBint\fP variable. A return value of 0 means that JIT support is not available
1261    in this version of PCRE, or that the pattern was not studied with a JIT option,
1262    or that the JIT compiler could not handle this particular pattern. See the
1263    .\" HREF
1264    \fBpcrejit\fP
1265    .\"
1266    documentation for details of what can and cannot be handled.
1267    .sp
1268      PCRE_INFO_JITSIZE
1269    .sp
1270    If the pattern was successfully studied with a JIT option, return the size of
1271    the JIT compiled code, otherwise return zero. The fourth argument should point
1272    to a \fBsize_t\fP variable.
1273    .sp
1274    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
1275  .sp  .sp
1276  Return the value of the rightmost literal byte that must exist in any matched  Return the value of the rightmost literal data unit that must exist in any
1277  string, other than at its start, if such a byte has been recorded. The fourth  matched string, other than at its start, if such a value has been recorded. The
1278  argument should point to an \fBint\fP variable. If there is no such byte, -1 is  fourth argument should point to an \fBint\fP variable. If there is no such
1279  returned. For anchored patterns, a last literal byte is recorded only if it  value, -1 is returned. For anchored patterns, a last literal value is recorded
1280  follows something of variable length. For example, for the pattern  only if it follows something of variable length. For example, for the pattern
1281  /^a\ed+z\ed+/ the returned value is "z", but for /^a\edz\ed/ the returned value  /^a\ed+z\ed+/ the returned value is "z", but for /^a\edz\ed/ the returned value
1282  is -1.  is -1.
1283    .P
1284    Since for the 32-bit library using the non-UTF-32 mode, this function is unable
1285    to return the full 32-bit range of the character, this value is deprecated;
1286    instead the PCRE_INFO_REQUIREDCHARFLAGS and PCRE_INFO_REQUIREDCHAR values should
1287    be used.
1288    .sp
1289      PCRE_INFO_MAXLOOKBEHIND
1290    .sp
1291    Return the number of characters (NB not bytes) in the longest lookbehind
1292    assertion in the pattern. Note that the simple assertions \eb and \eB require a
1293    one-character lookbehind. This information is useful when doing multi-segment
1294    matching using the partial matching facilities.
1295    .sp
1296      PCRE_INFO_MINLENGTH
1297    .sp
1298    If the pattern was studied and a minimum length for matching subject strings
1299    was computed, its value is returned. Otherwise the returned value is -1. The
1300    value is a number of characters, which in UTF-8 mode may be different from the
1301    number of bytes. The fourth argument should point to an \fBint\fP variable. A
1302    non-negative value is a lower bound to the length of any matching string. There
1303    may not be any strings of that length that do actually match, but every string
1304    that does match is at least that long.
1305  .sp  .sp
1306    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
1307    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
# Line 884  The map consists of a number of fixed-si Line 1321  The map consists of a number of fixed-si
1321  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
1322  entry; both of these return an \fBint\fP value. The entry size depends on the  entry; both of these return an \fBint\fP value. The entry size depends on the
1323  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
1324  entry of the table (a pointer to \fBchar\fP). The first two bytes of each entry  entry of the table. This is a pointer to \fBchar\fP in the 8-bit library, where
1325  are the number of the capturing parenthesis, most significant byte first. The  the first two bytes of each entry are the number of the capturing parenthesis,
1326  rest of the entry is the corresponding name, zero terminated. The names are in  most significant byte first. In the 16-bit library, the pointer points to
1327  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of  16-bit data units, the first of which contains the parenthesis number.
1328  their parentheses numbers. For example, consider the following pattern (assume  In the 32-bit library, the pointer points to 32-bit data units, the first of
1329  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  which contains the parenthesis number. The rest
1330    of the entry is the corresponding name, zero terminated.
1331    .P
1332    The names are in alphabetical order. Duplicate names may appear if (?| is used
1333    to create multiple groups with the same number, as described in the
1334    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1335    .\" </a>
1336    section on duplicate subpattern numbers
1337    .\"
1338    in the
1339    .\" HREF
1340    \fBpcrepattern\fP
1341    .\"
1342    page. Duplicate names for subpatterns with different numbers are permitted only
1343    if PCRE_DUPNAMES is set. In all cases of duplicate names, they appear in the
1344    table in the order in which they were found in the pattern. In the absence of
1345    (?| this is the order of increasing number; when (?| is used this is not
1346    necessarily the case because later subpatterns may have lower numbers.
1347    .P
1348    As a simple example of the name/number table, consider the following pattern
1349    after compilation by the 8-bit library (assume PCRE_EXTENDED is set, so white
1350    space - including newlines - is ignored):
1351  .sp  .sp
1352  .\" JOIN  .\" JOIN
1353    (?<date> (?<year>(\ed\ed)?\ed\ed) -    (?<date> (?<year>(\ed\ed)?\ed\ed) -
# Line 908  When writing code to extract data from n Line 1366  When writing code to extract data from n
1366  name-to-number map, remember that the length of the entries is likely to be  name-to-number map, remember that the length of the entries is likely to be
1367  different for each compiled pattern.  different for each compiled pattern.
1368  .sp  .sp
1369      PCRE_INFO_OKPARTIAL
1370    .sp
1371    Return 1 if the pattern can be used for partial matching with
1372    \fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
1373    \fBint\fP variable. From release 8.00, this always returns 1, because the
1374    restrictions that previously applied to partial matching have been lifted. The
1375    .\" HREF
1376    \fBpcrepartial\fP
1377    .\"
1378    documentation gives details of partial matching.
1379    .sp
1380    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1381  .sp  .sp
1382  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
1383  argument should point to an \fBunsigned long int\fP variable. These option bits  argument should point to an \fBunsigned long int\fP variable. These option bits
1384  are those specified in the call to \fBpcre_compile()\fP, modified by any  are those specified in the call to \fBpcre_compile()\fP, modified by any
1385  top-level option settings within the pattern itself.  top-level option settings at the start of the pattern itself. In other words,
1386    they are the options that will be in force when matching starts. For example,
1387    if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED option, the
1388    result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED.
1389  .P  .P
1390  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
1391  alternatives begin with one of the following:  alternatives begin with one of the following:
# Line 930  For such patterns, the PCRE_ANCHORED bit Line 1402  For such patterns, the PCRE_ANCHORED bit
1402  .sp  .sp
1403    PCRE_INFO_SIZE    PCRE_INFO_SIZE
1404  .sp  .sp
1405  Return the size of the compiled pattern, that is, the value that was passed as  Return the size of the compiled pattern in bytes (for both libraries). The
1406  the argument to \fBpcre_malloc()\fP when PCRE was getting memory in which to  fourth argument should point to a \fBsize_t\fP variable. This value does not
1407  place the compiled data. The fourth argument should point to a \fBsize_t\fP  include the size of the \fBpcre\fP structure that is returned by
1408  variable.  \fBpcre_compile()\fP. The value that is passed as the argument to
1409    \fBpcre_malloc()\fP when \fBpcre_compile()\fP is getting memory in which to
1410    place the compiled data is the value returned by this option plus the size of
1411    the \fBpcre\fP structure. Studying a compiled pattern, with or without JIT,
1412    does not alter the value returned by this option.
1413  .sp  .sp
1414    PCRE_INFO_STUDYSIZE    PCRE_INFO_STUDYSIZE
1415  .sp  .sp
1416  Return the size of the data block pointed to by the \fIstudy_data\fP field in  Return the size in bytes of the data block pointed to by the \fIstudy_data\fP
1417  a \fBpcre_extra\fP block. That is, it is the value that was passed to  field in a \fBpcre_extra\fP block. If \fBpcre_extra\fP is NULL, or there is no
1418  \fBpcre_malloc()\fP when PCRE was getting memory into which to place the data  study data, zero is returned. The fourth argument should point to a
1419  created by \fBpcre_study()\fP. The fourth argument should point to a  \fBsize_t\fP variable. The \fIstudy_data\fP field is set by \fBpcre_study()\fP
1420  \fBsize_t\fP variable.  to record information that will speed up matching (see the section entitled
1421  .  .\" HTML <a href="#studyingapattern">
1422  .  .\" </a>
1423  .SH "OBSOLETE INFO FUNCTION"  "Studying a pattern"
1424  .rs  .\"
1425    above). The format of the \fIstudy_data\fP block is private, but its length
1426    is made available via this option so that it can be saved and restored (see the
1427    .\" HREF
1428    \fBpcreprecompile\fP
1429    .\"
1430    documentation for details).
1431  .sp  .sp
1432  .B int pcre_info(const pcre *\fIcode\fP, int *\fIoptptr\fP, int    PCRE_INFO_FIRSTCHARACTERFLAGS
 .B *\fIfirstcharptr\fP);  
 .PP  
 The \fBpcre_info()\fP function is now obsolete because its interface is too  
 restrictive to return all the available data about a compiled pattern. New  
 programs should use \fBpcre_fullinfo()\fP instead. The yield of  
 \fBpcre_info()\fP is the number of capturing subpatterns, or one of the  
 following negative numbers:  
1433  .sp  .sp
1434    PCRE_ERROR_NULL       the argument \fIcode\fP was NULL  Return information about the first data unit of any matched string, for a
1435    PCRE_ERROR_BADMAGIC   the "magic number" was not found  non-anchored pattern. The fourth argument should point to an \fBint\fP
1436    variable.
1437    .P
1438    If there is a fixed first value, for example, the letter "c" from a pattern
1439    such as (cat|cow|coyote), 1 is returned, and the character value can be
1440    retrieved using PCRE_INFO_FIRSTCHARACTER.
1441    .P
1442    If there is no fixed first value, and if either
1443    .sp
1444    (a) the pattern was compiled with the PCRE_MULTILINE option, and every branch
1445    starts with "^", or
1446  .sp  .sp
1447  If the \fIoptptr\fP argument is not NULL, a copy of the options with which the  (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set
1448  pattern was compiled is placed in the integer it points to (see  (if it were set, the pattern would be anchored),
1449  PCRE_INFO_OPTIONS above).  .sp
1450    2 is returned, indicating that the pattern matches only at the start of a
1451    subject string or after any newline within the string. Otherwise 0 is
1452    returned. For anchored patterns, 0 is returned.
1453    .sp
1454      PCRE_INFO_FIRSTCHARACTER
1455    .sp
1456    Return the fixed first character value, if PCRE_INFO_FIRSTCHARACTERFLAGS
1457    returned 1; otherwise returns 0. The fourth argument should point to an
1458    \fBuint_t\fP variable.
1459    .P
1460    In the 8-bit library, the value is always less than 256. In the 16-bit library
1461    the value can be up to 0xffff. In the 32-bit library in UTF-32 mode the value
1462    can be up to 0x10ffff, and up to 0xffffffff when not using UTF-32 mode.
1463  .P  .P
1464  If the pattern is not anchored and the \fIfirstcharptr\fP argument is not NULL,  If there is no fixed first value, and if either
1465  it is used to pass back information about the first character of any matched  .sp
1466  string (see PCRE_INFO_FIRSTBYTE above).  (a) the pattern was compiled with the PCRE_MULTILINE option, and every branch
1467    starts with "^", or
1468    .sp
1469    (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set
1470    (if it were set, the pattern would be anchored),
1471    .sp
1472    -1 is returned, indicating that the pattern matches only at the start of a
1473    subject string or after any newline within the string. Otherwise -2 is
1474    returned. For anchored patterns, -2 is returned.
1475    .sp
1476      PCRE_INFO_REQUIREDCHARFLAGS
1477    .sp
1478    Returns 1 if there is a rightmost literal data unit that must exist in any
1479    matched string, other than at its start. The fourth argument should  point to
1480    an \fBint\fP variable. If there is no such value, 0 is returned. If returning
1481    1, the character value itself can be retrieved using PCRE_INFO_REQUIREDCHAR.
1482    .P
1483    For anchored patterns, a last literal value is recorded only if it follows
1484    something of variable length. For example, for the pattern /^a\ed+z\ed+/ the
1485    returned value 1 (with "z" returned from PCRE_INFO_REQUIREDCHAR), but for
1486    /^a\edz\ed/ the returned value is 0.
1487    .sp
1488      PCRE_INFO_REQUIREDCHAR
1489    .sp
1490    Return the value of the rightmost literal data unit that must exist in any
1491    matched string, other than at its start, if such a value has been recorded. The
1492    fourth argument should point to an \fBuint32_t\fP variable. If there is no such
1493    value, 0 is returned.
1494  .  .
1495  .  .
1496  .SH "REFERENCE COUNTS"  .SH "REFERENCE COUNTS"
# Line 1002  is different. (This seems a highly unlik Line 1527  is different. (This seems a highly unlik
1527  .P  .P
1528  The function \fBpcre_exec()\fP is called to match a subject string against a  The function \fBpcre_exec()\fP is called to match a subject string against a
1529  compiled pattern, which is passed in the \fIcode\fP argument. If the  compiled pattern, which is passed in the \fIcode\fP argument. If the
1530  pattern has been studied, the result of the study should be passed in the  pattern was studied, the result of the study should be passed in the
1531  \fIextra\fP argument. This function is the main matching facility of the  \fIextra\fP argument. You can call \fBpcre_exec()\fP with the same \fIcode\fP
1532  library, and it operates in a Perl-like manner. For specialist use there is  and \fIextra\fP arguments as many times as you like, in order to match
1533  also an alternative matching function, which is described  different subject strings with the same pattern.
1534    .P
1535    This function is the main matching facility of the library, and it operates in
1536    a Perl-like manner. For specialist use there is also an alternative matching
1537    function, which is described
1538  .\" HTML <a href="#dfamatch">  .\" HTML <a href="#dfamatch">
1539  .\" </a>  .\" </a>
1540  below  below
# Line 1036  Here is an example of a simple call to \ Line 1565  Here is an example of a simple call to \
1565      ovector,        /* vector of integers for substring information */      ovector,        /* vector of integers for substring information */
1566      30);            /* number of elements (NOT size in bytes) */      30);            /* number of elements (NOT size in bytes) */
1567  .  .
1568    .
1569  .\" HTML <a name="extradata"></a>  .\" HTML <a name="extradata"></a>
1570  .SS "Extra data for \fBpcre_exec()\fR"  .SS "Extra data for \fBpcre_exec()\fR"
1571  .rs  .rs
# Line 1048  fields (not necessarily in this order): Line 1578  fields (not necessarily in this order):
1578  .sp  .sp
1579    unsigned long int \fIflags\fP;    unsigned long int \fIflags\fP;
1580    void *\fIstudy_data\fP;    void *\fIstudy_data\fP;
1581      void *\fIexecutable_jit\fP;
1582    unsigned long int \fImatch_limit\fP;    unsigned long int \fImatch_limit\fP;
1583    unsigned long int \fImatch_limit_recursion\fP;    unsigned long int \fImatch_limit_recursion\fP;
1584    void *\fIcallout_data\fP;    void *\fIcallout_data\fP;
1585    const unsigned char *\fItables\fP;    const unsigned char *\fItables\fP;
1586      unsigned char **\fImark\fP;
1587  .sp  .sp
1588  The \fIflags\fP field is a bitmap that specifies which of the other fields  In the 16-bit version of this structure, the \fImark\fP field has type
1589  are set. The flag bits are:  "PCRE_UCHAR16 **".
1590  .sp  .sp
1591    PCRE_EXTRA_STUDY_DATA  In the 32-bit version of this structure, the \fImark\fP field has type
1592    "PCRE_UCHAR32 **".
1593    .P
1594    The \fIflags\fP field is used to specify which of the other fields are set. The
1595    flag bits are:
1596    .sp
1597      PCRE_EXTRA_CALLOUT_DATA
1598      PCRE_EXTRA_EXECUTABLE_JIT
1599      PCRE_EXTRA_MARK
1600    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1601    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1602    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_STUDY_DATA
1603    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1604  .sp  .sp
1605  Other flag bits should be set to zero. The \fIstudy_data\fP field is set in the  Other flag bits should be set to zero. The \fIstudy_data\fP field and sometimes
1606  \fBpcre_extra\fP block that is returned by \fBpcre_study()\fP, together with  the \fIexecutable_jit\fP field are set in the \fBpcre_extra\fP block that is
1607  the appropriate flag bit. You should not set this yourself, but you may add to  returned by \fBpcre_study()\fP, together with the appropriate flag bits. You
1608  the block by setting the other fields and their corresponding flag bits.  should not set these yourself, but you may add to the block by setting other
1609    fields and their corresponding flag bits.
1610  .P  .P
1611  The \fImatch_limit\fP field provides a means of preventing PCRE from using up a  The \fImatch_limit\fP field provides a means of preventing PCRE from using up a
1612  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,
1613  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
1614  classic example is the use of nested unlimited repeats.  classic example is a pattern that uses nested unlimited repeats.
1615  .P  .P
1616  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly  Internally, \fBpcre_exec()\fP uses a function called \fBmatch()\fP, which it
1617  (sometimes recursively). The limit set by \fImatch_limit\fP is imposed on the  calls repeatedly (sometimes recursively). The limit set by \fImatch_limit\fP is
1618  number of times this function is called during a match, which has the effect of  imposed on the number of times this function is called during a match, which
1619  limiting the amount of backtracking that can take place. For patterns that are  has the effect of limiting the amount of backtracking that can take place. For
1620  not anchored, the count restarts from zero for each position in the subject  patterns that are not anchored, the count restarts from zero for each position
1621  string.  in the subject string.
1622    .P
1623    When \fBpcre_exec()\fP is called with a pattern that was successfully studied
1624    with a JIT option, the way that the matching is executed is entirely different.
1625    However, there is still the possibility of runaway matching that goes on for a
1626    very long time, and so the \fImatch_limit\fP value is also used in this case
1627    (but in a different way) to limit how long the matching can continue.
1628  .P  .P
1629  The default value for the limit can be set when PCRE is built; the default  The default value for the limit can be set when PCRE is built; the default
1630  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
# Line 1092  limits the depth of recursion. The recur Line 1639  limits the depth of recursion. The recur
1639  total number of calls, because not all calls to \fBmatch()\fP are recursive.  total number of calls, because not all calls to \fBmatch()\fP are recursive.
1640  This limit is of use only if it is set smaller than \fImatch_limit\fP.  This limit is of use only if it is set smaller than \fImatch_limit\fP.
1641  .P  .P
1642  Limiting the recursion depth limits the amount of stack that can be used, or,  Limiting the recursion depth limits the amount of machine stack that can be
1643  when PCRE has been compiled to use memory on the heap instead of the stack, the  used, or, when PCRE has been compiled to use memory on the heap instead of the
1644  amount of heap memory that can be used.  stack, the amount of heap memory that can be used. This limit is not relevant,
1645    and is ignored, when matching is done using JIT compiled code.
1646  .P  .P
1647  The default value for \fImatch_limit_recursion\fP can be set when PCRE is  The default value for \fImatch_limit_recursion\fP can be set when PCRE is
1648  built; the default default is the same value as the default for  built; the default default is the same value as the default for
# Line 1103  with a \fBpcre_extra\fP block in which \ Line 1651  with a \fBpcre_extra\fP block in which \
1651  PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the \fIflags\fP field. If the limit  PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the \fIflags\fP field. If the limit
1652  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.  is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
1653  .P  .P
1654  The \fIpcre_callout\fP field is used in conjunction with the "callout" feature,  The \fIcallout_data\fP field is used in conjunction with the "callout" feature,
1655  which is described in the  and is described in the
1656  .\" HREF  .\" HREF
1657  \fBpcrecallout\fP  \fBpcrecallout\fP
1658  .\"  .\"
# Line 1123  called. See the Line 1671  called. See the
1671  \fBpcreprecompile\fP  \fBpcreprecompile\fP
1672  .\"  .\"
1673  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1674    .P
1675    If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1676    be set to point to a suitable variable. If the pattern contains any
1677    backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1678    a name to pass back, a pointer to the name string (zero terminated) is placed
1679    in the variable pointed to by the \fImark\fP field. The names are within the
1680    compiled pattern; if you wish to retain such a name you must copy it before
1681    freeing the memory of a compiled pattern. If there is no name to pass back, the
1682    variable pointed to by the \fImark\fP field is set to NULL. For details of the
1683    backtracking control verbs, see the section entitled
1684    .\" HTML <a href="pcrepattern#backtrackcontrol">
1685    .\" </a>
1686    "Backtracking control"
1687    .\"
1688    in the
1689    .\" HREF
1690    \fBpcrepattern\fP
1691    .\"
1692    documentation.
1693  .  .
1694    .
1695    .\" HTML <a name="execoptions"></a>
1696  .SS "Option bits for \fBpcre_exec()\fP"  .SS "Option bits for \fBpcre_exec()\fP"
1697  .rs  .rs
1698  .sp  .sp
1699  The unused bits of the \fIoptions\fP argument for \fBpcre_exec()\fP must be  The unused bits of the \fIoptions\fP argument for \fBpcre_exec()\fP must be
1700  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
1701  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1702    PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD, and
1703    PCRE_PARTIAL_SOFT.
1704    .P
1705    If the pattern was successfully studied with one of the just-in-time (JIT)
1706    compile options, the only supported options for JIT execution are
1707    PCRE_NO_UTF8_CHECK, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY,
1708    PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an
1709    unsupported option is used, JIT execution is disabled and the normal
1710    interpretive code in \fBpcre_exec()\fP is run.
1711  .sp  .sp
1712    PCRE_ANCHORED    PCRE_ANCHORED
1713  .sp  .sp
# Line 1138  matching position. If a pattern was comp Line 1716  matching position. If a pattern was comp
1716  to be anchored by virtue of its contents, it cannot be made unachored at  to be anchored by virtue of its contents, it cannot be made unachored at
1717  matching time.  matching time.
1718  .sp  .sp
1719      PCRE_BSR_ANYCRLF
1720      PCRE_BSR_UNICODE
1721    .sp
1722    These options (which are mutually exclusive) control what the \eR escape
1723    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
1724    match any Unicode newline sequence. These options override the choice that was
1725    made or defaulted when the pattern was compiled.
1726    .sp
1727    PCRE_NEWLINE_CR    PCRE_NEWLINE_CR
1728    PCRE_NEWLINE_LF    PCRE_NEWLINE_LF
1729    PCRE_NEWLINE_CRLF    PCRE_NEWLINE_CRLF
1730      PCRE_NEWLINE_ANYCRLF
1731    PCRE_NEWLINE_ANY    PCRE_NEWLINE_ANY
1732  .sp  .sp
1733  These options override the newline definition that was chosen or defaulted when  These options override the newline definition that was chosen or defaulted when
# Line 1148  the pattern was compiled. For details, s Line 1735  the pattern was compiled. For details, s
1735  \fBpcre_compile()\fP above. During matching, the newline choice affects the  \fBpcre_compile()\fP above. During matching, the newline choice affects the
1736  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1737  the way the match position is advanced after a match failure for an unanchored  the way the match position is advanced after a match failure for an unanchored
1738  pattern. When PCRE_NEWLINE_CRLF or PCRE_NEWLINE_ANY is set, and a match attempt  pattern.
1739  fails when the current position is at a CRLF sequence, the match position is  .P
1740  advanced by two characters instead of one, in other words, to after the CRLF.  When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a
1741    match attempt for an unanchored pattern fails when the current position is at a
1742    CRLF sequence, and the pattern contains no explicit matches for CR or LF
1743    characters, the match position is advanced by two characters instead of one, in
1744    other words, to after the CRLF.
1745    .P
1746    The above rule is a compromise that makes the most common cases work as
1747    expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
1748    set), it does not match the string "\er\enA" because, after failing at the
1749    start, it skips both the CR and the LF before retrying. However, the pattern
1750    [\er\en]A does match that string, because it contains an explicit CR or LF
1751    reference, and so advances only by one character after the first failure.
1752    .P
1753    An explicit match for CR of LF is either a literal appearance of one of those
1754    characters, or one of the \er or \en escape sequences. Implicit matches such as
1755    [^X] do not count, nor does \es (which includes CR and LF in the characters
1756    that it matches).
1757    .P
1758    Notwithstanding the above, anomalous effects may still occur when CRLF is a
1759    valid newline sequence and explicit \er or \en escapes appear in the pattern.
1760  .sp  .sp
1761    PCRE_NOTBOL    PCRE_NOTBOL
1762  .sp  .sp
# Line 1176  match the empty string, the entire match Line 1782  match the empty string, the entire match
1782  .sp  .sp
1783    a?b?    a?b?
1784  .sp  .sp
1785  is applied to a string not beginning with "a" or "b", it matches the empty  is applied to a string not beginning with "a" or "b", it matches an empty
1786  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
1787  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".
1788  .P  .sp
1789  Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a special case    PCRE_NOTEMPTY_ATSTART
1790  of a pattern match of the empty string within its \fBsplit()\fP function, and  .sp
1791  when using the /g modifier. It is possible to emulate Perl's behaviour after  This is like PCRE_NOTEMPTY, except that an empty string match that is not at
1792  matching a null string by first trying the match again at the same offset with  the start of the subject is permitted. If the pattern is anchored, such a match
1793  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the  can occur only if the pattern contains \eK.
1794  starting offset (see below) and trying an ordinary match again. There is some  .P
1795  code that demonstrates how to do this in the \fIpcredemo.c\fP sample program.  Perl has no direct equivalent of PCRE_NOTEMPTY or PCRE_NOTEMPTY_ATSTART, but it
1796    does make a special case of a pattern match of the empty string within its
1797    \fBsplit()\fP function, and when using the /g modifier. It is possible to
1798    emulate Perl's behaviour after matching a null string by first trying the match
1799    again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
1800    if that fails, by advancing the starting offset (see below) and trying an
1801    ordinary match again. There is some code that demonstrates how to do this in
1802    the
1803    .\" HREF
1804    \fBpcredemo\fP
1805    .\"
1806    sample program. In the most general case, you have to check to see if the
1807    newline convention recognizes CRLF as a newline, and if so, and the current
1808    character is CR followed by LF, advance the starting offset by two characters
1809    instead of one.
1810    .sp
1811      PCRE_NO_START_OPTIMIZE
1812    .sp
1813    There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
1814    a match, in order to speed up the process. For example, if it is known that an
1815    unanchored match must start with a specific character, it searches the subject
1816    for that character, and fails immediately if it cannot find it, without
1817    actually running the main matching function. This means that a special item
1818    such as (*COMMIT) at the start of a pattern is not considered until after a
1819    suitable starting point for the match has been found. When callouts or (*MARK)
1820    items are in use, these "start-up" optimizations can cause them to be skipped
1821    if the pattern is never actually used. The start-up optimizations are in effect
1822    a pre-scan of the subject that takes place before the pattern is run.
1823    .P
1824    The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
1825    causing performance to suffer, but ensuring that in cases where the result is
1826    "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
1827    are considered at every possible starting position in the subject string. If
1828    PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
1829    time. The use of PCRE_NO_START_OPTIMIZE disables JIT execution; when it is set,
1830    matching is always done using interpretively.
1831    .P
1832    Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
1833    Consider the pattern
1834    .sp
1835      (*COMMIT)ABC
1836    .sp
1837    When this is compiled, PCRE records the fact that a match must start with the
1838    character "A". Suppose the subject string is "DEFABC". The start-up
1839    optimization scans along the subject, finds "A" and runs the first match
1840    attempt from there. The (*COMMIT) item means that the pattern must match the
1841    current starting position, which in this case, it does. However, if the same
1842    match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
1843    subject string does not happen. The first match attempt is run starting from
1844    "D" and when this fails, (*COMMIT) prevents any further matches being tried, so
1845    the overall result is "no match". If the pattern is studied, more start-up
1846    optimizations may be used. For example, a minimum length for the subject may be
1847    recorded. Consider the pattern
1848    .sp
1849      (*MARK:A)(X|Y)
1850    .sp
1851    The minimum length for a match is one character. If the subject is "ABC", there
1852    will be attempts to match "ABC", "BC", "C", and then finally an empty string.
1853    If the pattern is studied, the final attempt does not take place, because PCRE
1854    knows that the subject is too short, and so the (*MARK) is never encountered.
1855    In this case, studying the pattern does not affect the overall match result,
1856    which is still "no match", but it does affect the auxiliary information that is
1857    returned.
1858  .sp  .sp
1859    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
1860  .sp  .sp
1861  When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8  When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8
1862  string is automatically checked when \fBpcre_exec()\fP is subsequently called.  string is automatically checked when \fBpcre_exec()\fP is subsequently called.
1863  The value of \fIstartoffset\fP is also checked to ensure that it points to the  The entire string is checked before any other processing takes place. The value
1864  start of a UTF-8 character. If an invalid UTF-8 sequence of bytes is found,  of \fIstartoffset\fP is also checked to ensure that it points to the start of a
1865  \fBpcre_exec()\fP returns the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP  UTF-8 character. There is a discussion about the
1866  contains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.  .\" HTML <a href="pcreunicode.html#utf8strings">
1867    .\" </a>
1868    validity of UTF-8 strings
1869    .\"
1870    in the
1871    .\" HREF
1872    \fBpcreunicode\fP
1873    .\"
1874    page. If an invalid sequence of bytes is found, \fBpcre_exec()\fP returns the
1875    error PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a
1876    truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In both
1877    cases, information about the precise nature of the error may also be returned
1878    (see the descriptions of these errors in the section entitled \fIError return
1879    values from\fP \fBpcre_exec()\fP
1880    .\" HTML <a href="#errorlist">
1881    .\" </a>
1882    below).
1883    .\"
1884    If \fIstartoffset\fP contains a value that does not point to the start of a
1885    UTF-8 character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
1886    returned.
1887  .P  .P
1888  If you already know that your subject is valid, and you want to skip these  If you already know that your subject is valid, and you want to skip these
1889  checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when  checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when
1890  calling \fBpcre_exec()\fP. You might want to do this for the second and  calling \fBpcre_exec()\fP. You might want to do this for the second and
1891  subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find  subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find
1892  all the matches in a single subject string. However, you should be sure that  all the matches in a single subject string. However, you should be sure that
1893  the value of \fIstartoffset\fP points to the start of a UTF-8 character. When  the value of \fIstartoffset\fP points to the start of a character (or the end
1894  PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid UTF-8 string as a  of the subject). When PCRE_NO_UTF8_CHECK is set, the effect of passing an
1895  subject, or a value of \fIstartoffset\fP that does not point to the start of a  invalid string as a subject or an invalid value of \fIstartoffset\fP is
1896  UTF-8 character, is undefined. Your program may crash.  undefined. Your program may crash.
1897  .sp  .sp
1898    PCRE_PARTIAL    PCRE_PARTIAL_HARD
1899  .sp    PCRE_PARTIAL_SOFT
1900  This option turns on the partial matching feature. If the subject string fails  .sp
1901  to match the pattern, but at some point during the matching process the end of  These options turn on the partial matching feature. For backwards
1902  the subject was reached (that is, the subject partially matches the pattern and  compatibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial match
1903  the failure to match occurred only because there were not enough subject  occurs if the end of the subject string is reached successfully, but there are
1904  characters), \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL instead of  not enough subject characters to complete the match. If this happens when
1905  PCRE_ERROR_NOMATCH. When PCRE_PARTIAL is used, there are restrictions on what  PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set, matching continues by
1906  may appear in the pattern. These are discussed in the  testing any remaining alternatives. Only if no complete match can be found is
1907    PCRE_ERROR_PARTIAL returned instead of PCRE_ERROR_NOMATCH. In other words,
1908    PCRE_PARTIAL_SOFT says that the caller is prepared to handle a partial match,
1909    but only if no complete match can be found.
1910    .P
1911    If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
1912    partial match is found, \fBpcre_exec()\fP immediately returns
1913    PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
1914    when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
1915    important that an alternative complete match.
1916    .P
1917    In both cases, the portion of the string that was inspected when the partial
1918    match was found is set as the first matching string. There is a more detailed
1919    discussion of partial and multi-segment matching, with examples, in the
1920  .\" HREF  .\" HREF
1921  \fBpcrepartial\fP  \fBpcrepartial\fP
1922  .\"  .\"
1923  documentation.  documentation.
1924  .  .
1925    .
1926  .SS "The string to be matched by \fBpcre_exec()\fP"  .SS "The string to be matched by \fBpcre_exec()\fP"
1927  .rs  .rs
1928  .sp  .sp
1929  The subject string is passed to \fBpcre_exec()\fP as a pointer in  The subject string is passed to \fBpcre_exec()\fP as a pointer in
1930  \fIsubject\fP, a length in \fIlength\fP, and a starting byte offset in  \fIsubject\fP, a length in bytes in \fIlength\fP, and a starting byte offset
1931  \fIstartoffset\fP. In UTF-8 mode, the byte offset must point to the start of a  in \fIstartoffset\fP. If this is negative or greater than the length of the
1932  UTF-8 character. Unlike the pattern string, the subject may contain binary zero  subject, \fBpcre_exec()\fP returns PCRE_ERROR_BADOFFSET. When the starting
1933  bytes. When the starting offset is zero, the search for a match starts at the  offset is zero, the search for a match starts at the beginning of the subject,
1934  beginning of the subject, and this is by far the most common case.  and this is by far the most common case. In UTF-8 mode, the byte offset must
1935    point to the start of a UTF-8 character (or the end of the subject). Unlike the
1936    pattern string, the subject may contain binary zero bytes.
1937  .P  .P
1938  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
1939  same subject by calling \fBpcre_exec()\fP again after a previous success.  same subject by calling \fBpcre_exec()\fP again after a previous success.
# Line 1249  start of the subject, which is deemed to Line 1953  start of the subject, which is deemed to
1953  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
1954  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.
1955  .P  .P
1956    Finding all the matches in a subject is tricky when the pattern can match an
1957    empty string. It is possible to emulate Perl's /g behaviour by first trying the
1958    match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
1959    PCRE_ANCHORED options, and then if that fails, advancing the starting offset
1960    and trying an ordinary match again. There is some code that demonstrates how to
1961    do this in the
1962    .\" HREF
1963    \fBpcredemo\fP
1964    .\"
1965    sample program. In the most general case, you have to check to see if the
1966    newline convention recognizes CRLF as a newline, and if so, and the current
1967    character is CR followed by LF, advance the starting offset by two characters
1968    instead of one.
1969    .P
1970  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
1971  attempt to match at the given offset is made. This can only succeed if the  attempt to match at the given offset is made. This can only succeed if the
1972  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.
1973  .  .
1974    .
1975  .SS "How \fBpcre_exec()\fP returns captured substrings"  .SS "How \fBpcre_exec()\fP returns captured substrings"
1976  .rs  .rs
1977  .sp  .sp
# Line 1263  pattern. Following the usage in Jeffrey Line 1982  pattern. Following the usage in Jeffrey
1982  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
1983  kinds of parenthesized subpattern that do not cause substrings to be captured.  kinds of parenthesized subpattern that do not cause substrings to be captured.
1984  .P  .P
1985  Captured substrings are returned to the caller via a vector of integer offsets  Captured substrings are returned to the caller via a vector of integers whose
1986  whose address is passed in \fIovector\fP. The number of elements in the vector  address is passed in \fIovector\fP. The number of elements in the vector is
1987  is passed in \fIovecsize\fP, which must be a non-negative number. \fBNote\fP:  passed in \fIovecsize\fP, which must be a non-negative number. \fBNote\fP: this
1988  this argument is NOT the size of \fIovector\fP in bytes.  argument is NOT the size of \fIovector\fP in bytes.
1989  .P  .P
1990  The first two-thirds of the vector is used to pass back captured substrings,  The first two-thirds of the vector is used to pass back captured substrings,
1991  each substring using a pair of integers. The remaining third of the vector is  each substring using a pair of integers. The remaining third of the vector is
1992  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,  used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
1993  and is not available for passing back information. The length passed in  and is not available for passing back information. The number passed in
1994  \fIovecsize\fP should always be a multiple of three. If it is not, it is  \fIovecsize\fP should always be a multiple of three. If it is not, it is
1995  rounded down.  rounded down.
1996  .P  .P
1997  When a match is successful, information about captured substrings is returned  When a match is successful, information about captured substrings is returned
1998  in pairs of integers, starting at the beginning of \fIovector\fP, and  in pairs of integers, starting at the beginning of \fIovector\fP, and
1999  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
2000  pair is set to the offset of the first character in a substring, and the second  each pair is set to the byte offset of the first character in a substring, and
2001  is set to the offset of the first character after the end of a substring. The  the second is set to the byte offset of the first character after the end of a
2002  first pair, \fIovector[0]\fP and \fIovector[1]\fP, identify the portion of the  substring. \fBNote\fP: these values are always byte offsets, even in UTF-8
2003  subject string matched by the entire pattern. The next pair is used for the  mode. They are not character counts.
2004  first capturing subpattern, and so on. The value returned by \fBpcre_exec()\fP  .P
2005  is one more than the highest numbered pair that has been set. For example, if  The first pair of integers, \fIovector[0]\fP and \fIovector[1]\fP, identify the
2006  two substrings have been captured, the returned value is 3. If there are no  portion of the subject string matched by the entire pattern. The next pair is
2007  capturing subpatterns, the return value from a successful match is 1,  used for the first capturing subpattern, and so on. The value returned by
2008  indicating that just the first pair of offsets has been set.  \fBpcre_exec()\fP is one more than the highest numbered pair that has been set.
2009    For example, if two substrings have been captured, the returned value is 3. If
2010    there are no capturing subpatterns, the return value from a successful match is
2011    1, indicating that just the first pair of offsets has been set.
2012  .P  .P
2013  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
2014  string that it matched that is returned.  string that it matched that is returned.
2015  .P  .P
2016  If the vector is too small to hold all the captured substring offsets, it is  If the vector is too small to hold all the captured substring offsets, it is
2017  used as far as possible (up to two-thirds of its length), and the function  used as far as possible (up to two-thirds of its length), and the function
2018  returns a value of zero. In particular, if the substring offsets are not of  returns a value of zero. If neither the actual string matched nor any captured
2019  interest, \fBpcre_exec()\fP may be called with \fIovector\fP passed as NULL and  substrings are of interest, \fBpcre_exec()\fP may be called with \fIovector\fP
2020  \fIovecsize\fP as zero. However, if the pattern contains back references and  passed as NULL and \fIovecsize\fP as zero. However, if the pattern contains
2021  the \fIovector\fP is not big enough to remember the related substrings, PCRE  back references and the \fIovector\fP is not big enough to remember the related
2022  has to get additional memory for use during matching. Thus it is usually  substrings, PCRE has to get additional memory for use during matching. Thus it
2023  advisable to supply an \fIovector\fP.  is usually advisable to supply an \fIovector\fP of reasonable size.
2024    .P
2025    There are some cases where zero is returned (indicating vector overflow) when
2026    in fact the vector is exactly the right size for the final match. For example,
2027    consider the pattern
2028    .sp
2029      (a)(?:(b)c|bd)
2030    .sp
2031    If a vector of 6 elements (allowing for only 1 captured substring) is given
2032    with subject string "abd", \fBpcre_exec()\fP will try to set the second
2033    captured string, thereby recording a vector overflow, before failing to match
2034    "c" and backing up to try the second alternative. The zero return, however,
2035    does correctly indicate that the maximum number of slots (namely 2) have been
2036    filled. In similar cases where there is temporary overflow, but the final
2037    number of used slots is actually less than the maximum, a non-zero value is
2038    returned.
2039  .P  .P
2040  The \fBpcre_info()\fP function can be used to find out how many capturing  The \fBpcre_fullinfo()\fP function can be used to find out how many capturing
2041  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
2042  \fIovector\fP that will allow for \fIn\fP captured substrings, in addition to  \fIovector\fP that will allow for \fIn\fP captured substrings, in addition to
2043  the offsets of the substring matched by the whole pattern, is (\fIn\fP+1)*3.  the offsets of the substring matched by the whole pattern, is (\fIn\fP+1)*3.
# Line 1316  Offset values that correspond to unused Line 2053  Offset values that correspond to unused
2053  expression are also set to -1. For example, if the string "abc" is matched  expression are also set to -1. For example, if the string "abc" is matched
2054  against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The  against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
2055  return from the function is 2, because the highest used capturing subpattern  return from the function is 2, because the highest used capturing subpattern
2056  number is 1. However, you can refer to the offsets for the second and third  number is 1, and the offsets for for the second and third capturing subpatterns
2057  capturing subpatterns if you wish (assuming the vector is large enough, of  (assuming the vector is large enough, of course) are set to -1.
2058  course).  .P
2059    \fBNote\fP: Elements in the first two-thirds of \fIovector\fP that do not
2060    correspond to capturing parentheses in the pattern are never changed. That is,
2061    if a pattern contains \fIn\fP capturing parentheses, no more than
2062    \fIovector[0]\fP to \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other
2063    elements (in the first two-thirds) retain whatever values they previously had.
2064  .P  .P
2065  Some convenience functions are provided for extracting the captured substrings  Some convenience functions are provided for extracting the captured substrings
2066  as separate strings. These are described below.  as separate strings. These are described below.
2067  .  .
2068    .
2069  .\" HTML <a name="errorlist"></a>  .\" HTML <a name="errorlist"></a>
2070  .SS "Error return values from \fBpcre_exec()\fP"  .SS "Error return values from \fBpcre_exec()\fP"
2071  .rs  .rs
# Line 1364  If a pattern contains back references, b Line 2107  If a pattern contains back references, b
2107  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
2108  call via \fBpcre_malloc()\fP fails, this error is given. The memory is  call via \fBpcre_malloc()\fP fails, this error is given. The memory is
2109  automatically freed at the end of matching.  automatically freed at the end of matching.
2110    .P
2111    This error is also given if \fBpcre_stack_malloc()\fP fails in
2112    \fBpcre_exec()\fP. This can happen only when PCRE has been compiled with
2113    \fB--disable-stack-for-recursion\fP.
2114  .sp  .sp
2115    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
2116  .sp  .sp
# Line 1388  documentation for details. Line 2135  documentation for details.
2135  .sp  .sp
2136    PCRE_ERROR_BADUTF8        (-10)    PCRE_ERROR_BADUTF8        (-10)
2137  .sp  .sp
2138  A string that contains an invalid UTF-8 byte sequence was passed as a subject.  A string that contains an invalid UTF-8 byte sequence was passed as a subject,
2139    and the PCRE_NO_UTF8_CHECK option was not set. If the size of the output vector
2140    (\fIovecsize\fP) is at least 2, the byte offset to the start of the the invalid
2141    UTF-8 character is placed in the first element, and a reason code is placed in
2142    the second element. The reason codes are listed in the
2143    .\" HTML <a href="#badutf8reasons">
2144    .\" </a>
2145    following section.
2146    .\"
2147    For backward compatibility, if PCRE_PARTIAL_HARD is set and the problem is a
2148    truncated UTF-8 character at the end of the subject (reason codes 1 to 5),
2149    PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
2150  .sp  .sp
2151    PCRE_ERROR_BADUTF8_OFFSET (-11)    PCRE_ERROR_BADUTF8_OFFSET (-11)
2152  .sp  .sp
2153  The UTF-8 byte sequence that was passed as a subject was valid, but the value  The UTF-8 byte sequence that was passed as a subject was checked and found to
2154  of \fIstartoffset\fP did not point to the beginning of a UTF-8 character.  be valid (the PCRE_NO_UTF8_CHECK option was not set), but the value of
2155    \fIstartoffset\fP did not point to the beginning of a UTF-8 character or the
2156    end of the subject.
2157  .sp  .sp
2158    PCRE_ERROR_PARTIAL        (-12)    PCRE_ERROR_PARTIAL        (-12)
2159  .sp  .sp
# Line 1405  documentation for details of partial mat Line 2165  documentation for details of partial mat
2165  .sp  .sp
2166    PCRE_ERROR_BADPARTIAL     (-13)    PCRE_ERROR_BADPARTIAL     (-13)
2167  .sp  .sp
2168  The PCRE_PARTIAL option was used with a compiled pattern containing items that  This code is no longer in use. It was formerly returned when the PCRE_PARTIAL
2169  are not supported for partial matching. See the  option was used with a compiled pattern containing items that were not
2170  .\" HREF  supported for partial matching. From release 8.00 onwards, there are no
2171  \fBpcrepartial\fP  restrictions on partial matching.
 .\"  
 documentation for details of partial matching.  
2172  .sp  .sp
2173    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
2174  .sp  .sp
# Line 1427  The internal recursion limit, as specifi Line 2185  The internal recursion limit, as specifi
2185  field in a \fBpcre_extra\fP structure (or defaulted) was reached. See the  field in a \fBpcre_extra\fP structure (or defaulted) was reached. See the
2186  description above.  description above.
2187  .sp  .sp
   PCRE_ERROR_NULLWSLIMIT    (-22)  
 .sp  
 When a group that can match an empty substring is repeated with an unbounded  
 upper limit, the subject position at the start of the group must be remembered,  
 so that a test for an empty string can be made when the end of the group is  
 reached. Some workspace is required for this; if it runs out, this error is  
 given.  
 .sp  
2188    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
2189  .sp  .sp
2190  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
2191    .sp
2192      PCRE_ERROR_BADOFFSET      (-24)
2193    .sp
2194    The value of \fIstartoffset\fP was negative or greater than the length of the
2195    subject, that is, the value in \fIlength\fP.
2196    .sp
2197      PCRE_ERROR_SHORTUTF8      (-25)
2198    .sp
2199    This error is returned instead of PCRE_ERROR_BADUTF8 when the subject string
2200    ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD option is set.
2201    Information about the failure is returned as for PCRE_ERROR_BADUTF8. It is in
2202    fact sufficient to detect this case, but this special error code for
2203    PCRE_PARTIAL_HARD precedes the implementation of returned information; it is
2204    retained for backwards compatibility.
2205    .sp
2206      PCRE_ERROR_RECURSELOOP    (-26)
2207    .sp
2208    This error is returned when \fBpcre_exec()\fP detects a recursion loop within
2209    the pattern. Specifically, it means that either the whole pattern or a
2210    subpattern has been called recursively for the second time at the same position
2211    in the subject string. Some simple patterns that might do this are detected and
2212    faulted at compile time, but more complicated cases, in particular mutual
2213    recursions between two different subpatterns, cannot be detected until run
2214    time.
2215    .sp
2216      PCRE_ERROR_JIT_STACKLIMIT (-27)
2217    .sp
2218    This error is returned when a pattern that was successfully studied using a
2219    JIT compile option is being matched, but the memory available for the
2220    just-in-time processing stack is not large enough. See the
2221    .\" HREF
2222    \fBpcrejit\fP
2223    .\"
2224    documentation for more details.
2225    .sp
2226      PCRE_ERROR_BADMODE        (-28)
2227    .sp
2228    This error is given if a pattern that was compiled by the 8-bit library is
2229    passed to a 16-bit or 32-bit library function, or vice versa.
2230    .sp
2231      PCRE_ERROR_BADENDIANNESS  (-29)
2232    .sp
2233    This error is given if a pattern that was compiled and saved is reloaded on a
2234    host with different endianness. The utility function
2235    \fBpcre_pattern_to_host_byte_order()\fP can be used to convert such a pattern
2236    so that it runs on the new host.
2237    .sp
2238      PCRE_ERROR_BADLENGTH      (-32)
2239    .sp
2240    This error is given if \fBpcre_exec()\fP is called with a negative value for
2241    the \fIlength\fP argument.
2242    .P
2243    Error numbers -16 to -20, -22, 30, and -31 are not used by \fBpcre_exec()\fP.
2244    .
2245    .
2246    .\" HTML <a name="badutf8reasons"></a>
2247    .SS "Reason codes for invalid UTF-8 strings"
2248    .rs
2249    .sp
2250    This section applies only to the 8-bit library. The corresponding information
2251    for the 16-bit library is given in the
2252    .\" HREF
2253    \fBpcre16\fP
2254    .\"
2255    page. The corresponding information for the 32-bit library is given in the
2256    .\" HREF
2257    \fBpcre32\fP
2258    .\"
2259    page.
2260  .P  .P
2261  Error numbers -16 to -20 are not used by \fBpcre_exec()\fP.  When \fBpcre_exec()\fP returns either PCRE_ERROR_BADUTF8 or
2262    PCRE_ERROR_SHORTUTF8, and the size of the output vector (\fIovecsize\fP) is at
2263    least 2, the offset of the start of the invalid UTF-8 character is placed in
2264    the first output vector element (\fIovector[0]\fP) and a reason code is placed
2265    in the second element (\fIovector[1]\fP). The reason codes are given names in
2266    the \fBpcre.h\fP header file:
2267    .sp
2268      PCRE_UTF8_ERR1
2269      PCRE_UTF8_ERR2
2270      PCRE_UTF8_ERR3
2271      PCRE_UTF8_ERR4
2272      PCRE_UTF8_ERR5
2273    .sp
2274    The string ends with a truncated UTF-8 character; the code specifies how many
2275    bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8 characters to be
2276    no longer than 4 bytes, the encoding scheme (originally defined by RFC 2279)
2277    allows for up to 6 bytes, and this is checked first; hence the possibility of
2278    4 or 5 missing bytes.
2279    .sp
2280      PCRE_UTF8_ERR6
2281      PCRE_UTF8_ERR7
2282      PCRE_UTF8_ERR8
2283      PCRE_UTF8_ERR9
2284      PCRE_UTF8_ERR10
2285    .sp
2286    The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of the
2287    character do not have the binary value 0b10 (that is, either the most
2288    significant bit is 0, or the next bit is 1).
2289    .sp
2290      PCRE_UTF8_ERR11
2291      PCRE_UTF8_ERR12
2292    .sp
2293    A character that is valid by the RFC 2279 rules is either 5 or 6 bytes long;
2294    these code points are excluded by RFC 3629.
2295    .sp
2296      PCRE_UTF8_ERR13
2297    .sp
2298    A 4-byte character has a value greater than 0x10fff; these code points are
2299    excluded by RFC 3629.
2300    .sp
2301      PCRE_UTF8_ERR14
2302    .sp
2303    A 3-byte character has a value in the range 0xd800 to 0xdfff; this range of
2304    code points are reserved by RFC 3629 for use with UTF-16, and so are excluded
2305    from UTF-8.
2306    .sp
2307      PCRE_UTF8_ERR15
2308      PCRE_UTF8_ERR16
2309      PCRE_UTF8_ERR17
2310      PCRE_UTF8_ERR18
2311      PCRE_UTF8_ERR19
2312    .sp
2313    A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes for a
2314    value that can be represented by fewer bytes, which is invalid. For example,
2315    the two bytes 0xc0, 0xae give the value 0x2e, whose correct coding uses just
2316    one byte.
2317    .sp
2318      PCRE_UTF8_ERR20
2319    .sp
2320    The two most significant bits of the first byte of a character have the binary
2321    value 0b10 (that is, the most significant bit is 1 and the second is 0). Such a
2322    byte can only validly occur as the second or subsequent byte of a multi-byte
2323    character.
2324    .sp
2325      PCRE_UTF8_ERR21
2326    .sp
2327    The first byte of a character has the value 0xfe or 0xff. These values can
2328    never occur in a valid UTF-8 string.
2329    .sp
2330      PCRE_UTF8_ERR2
2331    .sp
2332    Non-character. These are the last two characters in each plane (0xfffe, 0xffff,
2333    0x1fffe, 0x1ffff .. 0x10fffe, 0x10ffff), and the characters 0xfdd0..0xfdef.
2334  .  .
2335  .  .
2336  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
# Line 1585  pattern. This is needed in order to gain Line 2476  pattern. This is needed in order to gain
2476  translation table.  translation table.
2477  .P  .P
2478  These functions call \fBpcre_get_stringnumber()\fP, and if it succeeds, they  These functions call \fBpcre_get_stringnumber()\fP, and if it succeeds, they
2479  then call \fIpcre_copy_substring()\fP or \fIpcre_get_substring()\fP, as  then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
2480  appropriate.  appropriate. \fBNOTE:\fP If PCRE_DUPNAMES is set and there are duplicate names,
2481    the behaviour may not be what you want (see the next section).
2482    .P
2483    \fBWarning:\fP If the pattern uses the (?| feature to set up multiple
2484    subpatterns with the same number, as described in the
2485    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
2486    .\" </a>
2487    section on duplicate subpattern numbers
2488    .\"
2489    in the
2490    .\" HREF
2491    \fBpcrepattern\fP
2492    .\"
2493    page, you cannot use names to distinguish the different subpatterns, because
2494    names are not included in the compiled code. The matching process uses only
2495    numbers. For this reason, the use of different names for subpatterns of the
2496    same number causes an error at compile time.
2497  .  .
2498  .  .
2499  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
# Line 1597  appropriate. Line 2504  appropriate.
2504  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
2505  .PP  .PP
2506  When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns  When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
2507  are not required to be unique. Normally, patterns with duplicate names are such  are not required to be unique. (Duplicate names are always allowed for
2508  that in any one match, only one of the named subpatterns participates. An  subpatterns with the same number, created by using the (?| feature. Indeed, if
2509  example is shown in the  such subpatterns are named, they are required to use the same names.)
2510    .P
2511    Normally, patterns with duplicate names are such that in any one match, only
2512    one of the named subpatterns participates. An example is shown in the
2513  .\" HREF  .\" HREF
2514  \fBpcrepattern\fP  \fBpcrepattern\fP
2515  .\"  .\"
2516  documentation. When duplicates are present, \fBpcre_copy_named_substring()\fP  documentation.
2517  and \fBpcre_get_named_substring()\fP return the first substring corresponding  .P
2518  to the given name that is set. If none are set, an empty string is returned.  When duplicates are present, \fBpcre_copy_named_substring()\fP and
2519  The \fBpcre_get_stringnumber()\fP function returns one of the numbers that are  \fBpcre_get_named_substring()\fP return the first substring corresponding to
2520  associated with the name, but it is not defined which it is.  the given name that is set. If none are set, PCRE_ERROR_NOSUBSTRING (-7) is
2521  .sp  returned; no data is returned. The \fBpcre_get_stringnumber()\fP function
2522    returns one of the numbers that are associated with the name, but it is not
2523    defined which it is.
2524    .P
2525  If you want to get full details of all captured substrings for a given name,  If you want to get full details of all captured substrings for a given name,
2526  you must use the \fBpcre_get_stringtable_entries()\fP function. The first  you must use the \fBpcre_get_stringtable_entries()\fP function. The first
2527  argument is the compiled pattern, and the second is the name. The third and  argument is the compiled pattern, and the second is the name. The third and
# Line 1616  fourth are pointers to variables which a Line 2529  fourth are pointers to variables which a
2529  has run, they point to the first and last entries in the name-to-number table  has run, they point to the first and last entries in the name-to-number table
2530  for the given name. The function itself returns the length of each entry, or  for the given name. The function itself returns the length of each entry, or
2531  PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is  PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
2532  described above in the section entitled \fIInformation about a pattern\fP.  described above in the section entitled \fIInformation about a pattern\fP
2533    .\" HTML <a href="#infoaboutpattern">
2534    .\" </a>
2535    above.
2536    .\"
2537  Given all the relevant entries for the name, you can extract each of their  Given all the relevant entries for the name, you can extract each of their
2538  numbers, and hence the captured data, if any.  numbers, and hence the captured data, if any.
2539  .  .
# Line 1643  other alternatives. Ultimately, when it Line 2560  other alternatives. Ultimately, when it
2560  will yield PCRE_ERROR_NOMATCH.  will yield PCRE_ERROR_NOMATCH.
2561  .  .
2562  .  .
2563    .SH "OBTAINING AN ESTIMATE OF STACK USAGE"
2564    .rs
2565    .sp
2566    Matching certain patterns using \fBpcre_exec()\fP can use a lot of process
2567    stack, which in certain environments can be rather limited in size. Some users
2568    find it helpful to have an estimate of the amount of stack that is used by
2569    \fBpcre_exec()\fP, to help them set recursion limits, as described in the
2570    .\" HREF
2571    \fBpcrestack\fP
2572    .\"
2573    documentation. The estimate that is output by \fBpcretest\fP when called with
2574    the \fB-m\fP and \fB-C\fP options is obtained by calling \fBpcre_exec\fP with
2575    the values NULL, NULL, NULL, -999, and -999 for its first five arguments.
2576    .P
2577    Normally, if its first argument is NULL, \fBpcre_exec()\fP immediately returns
2578    the negative error code PCRE_ERROR_NULL, but with this special combination of
2579    arguments, it returns instead a negative number whose absolute value is the
2580    approximate stack frame size in bytes. (A negative number is used so that it is
2581    clear that no match has happened.) The value is approximate because in some
2582    cases, recursive calls to \fBpcre_exec()\fP occur when there are one or two
2583    additional variables on the stack.
2584    .P
2585    If PCRE has been compiled to use the heap instead of the stack for recursion,
2586    the value returned is the size of each block that is obtained from the heap.
2587    .
2588    .
2589  .\" HTML <a name="dfamatch"></a>  .\" HTML <a name="dfamatch"></a>
2590  .SH "MATCHING A PATTERN: THE ALTERNATIVE FUNCTION"  .SH "MATCHING A PATTERN: THE ALTERNATIVE FUNCTION"
2591  .rs  .rs
# Line 1660  a compiled pattern, using a matching alg Line 2603  a compiled pattern, using a matching alg
2603  just once, and does not backtrack. This has different characteristics to the  just once, and does not backtrack. This has different characteristics to the
2604  normal algorithm, and is not compatible with Perl. Some of the features of PCRE  normal algorithm, and is not compatible with Perl. Some of the features of PCRE
2605  patterns are not supported. Nevertheless, there are times when this kind of  patterns are not supported. Nevertheless, there are times when this kind of
2606  matching can be useful. For a discussion of the two matching algorithms, see  matching can be useful. For a discussion of the two matching algorithms, and a
2607  the  list of features that \fBpcre_dfa_exec()\fP does not support, see the
2608  .\" HREF  .\" HREF
2609  \fBpcrematching\fP  \fBpcrematching\fP
2610  .\"  .\"
# Line 1700  Here is an example of a simple call to \ Line 2643  Here is an example of a simple call to \
2643  .sp  .sp
2644  The unused bits of the \fIoptions\fP argument for \fBpcre_dfa_exec()\fP must be  The unused bits of the \fIoptions\fP argument for \fBpcre_dfa_exec()\fP must be
2645  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
2646  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
2647  PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last three of these are  PCRE_NO_UTF8_CHECK, PCRE_BSR_ANYCRLF, PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE,
2648  the same as for \fBpcre_exec()\fP, so their description is not repeated here.  PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART.
2649  .sp  All but the last four of these are exactly the same as for \fBpcre_exec()\fP,
2650    PCRE_PARTIAL  so their description is not repeated here.
2651  .sp  .sp
2652  This has the same general effect as it does for \fBpcre_exec()\fP, but the    PCRE_PARTIAL_HARD
2653  details are slightly different. When PCRE_PARTIAL is set for    PCRE_PARTIAL_SOFT
2654  \fBpcre_dfa_exec()\fP, the return code PCRE_ERROR_NOMATCH is converted into  .sp
2655  PCRE_ERROR_PARTIAL if the end of the subject is reached, there have been no  These have the same general effect as they do for \fBpcre_exec()\fP, but the
2656  complete matches, but there is still at least one matching possibility. The  details are slightly different. When PCRE_PARTIAL_HARD is set for
2657  portion of the string that provided the partial match is set as the first  \fBpcre_dfa_exec()\fP, it returns PCRE_ERROR_PARTIAL if the end of the subject
2658  matching string.  is reached and there is still at least one matching possibility that requires
2659    additional characters. This happens even if some complete matches have also
2660    been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
2661    is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
2662    there have been no complete matches, but there is still at least one matching
2663    possibility. The portion of the string that was inspected when the longest
2664    partial match was found is set as the first matching string in both cases.
2665    There is a more detailed discussion of partial and multi-segment matching, with
2666    examples, in the
2667    .\" HREF
2668    \fBpcrepartial\fP
2669    .\"
2670    documentation.
2671  .sp  .sp
2672    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
2673  .sp  .sp
# Line 1723  matching point in the subject string. Line 2678  matching point in the subject string.
2678  .sp  .sp
2679    PCRE_DFA_RESTART    PCRE_DFA_RESTART
2680  .sp  .sp
2681  When \fBpcre_dfa_exec()\fP is called with the PCRE_PARTIAL option, and returns  When \fBpcre_dfa_exec()\fP returns a partial match, it is possible to call it
2682  a partial match, it is possible to call it again, with additional subject  again, with additional subject characters, and have it continue with the same
2683  characters, and have it continue with the same match. The PCRE_DFA_RESTART  match. The PCRE_DFA_RESTART option requests this action; when it is set, the
2684  option requests this action; when it is set, the \fIworkspace\fP and  \fIworkspace\fP and \fIwscount\fP options must reference the same vector as
2685  \fIwscount\fP options must reference the same vector as before because data  before because data about the match so far is left in them after a partial
2686  about the match so far is left in them after a partial match. There is more  match. There is more discussion of this facility in the
 discussion of this facility in the  
2687  .\" HREF  .\" HREF
2688  \fBpcrepartial\fP  \fBpcrepartial\fP
2689  .\"  .\"
2690  documentation.  documentation.
2691  .  .
2692    .
2693  .SS "Successful returns from \fBpcre_dfa_exec()\fP"  .SS "Successful returns from \fBpcre_dfa_exec()\fP"
2694  .rs  .rs
2695  .sp  .sp
# Line 1766  returns data, even though the meaning of Line 2721  returns data, even though the meaning of
2721  The strings are returned in reverse order of length; that is, the longest  The strings are returned in reverse order of length; that is, the longest
2722  matching string is given first. If there were too many matches to fit into  matching string is given first. If there were too many matches to fit into
2723  \fIovector\fP, the yield of the function is zero, and the vector is filled with  \fIovector\fP, the yield of the function is zero, and the vector is filled with
2724  the longest matches.  the longest matches. Unlike \fBpcre_exec()\fP, \fBpcre_dfa_exec()\fP can use
2725    the entire \fIovector\fP for returning matched strings.
2726    .
2727  .  .
2728  .SS "Error returns from \fBpcre_dfa_exec()\fP"  .SS "Error returns from \fBpcre_dfa_exec()\fP"
2729  .rs  .rs
# Line 1795  group. These are not supported. Line 2752  group. These are not supported.
2752    PCRE_ERROR_DFA_UMLIMIT    (-18)    PCRE_ERROR_DFA_UMLIMIT    (-18)
2753  .sp  .sp
2754  This return is given if \fBpcre_dfa_exec()\fP is called with an \fIextra\fP  This return is given if \fBpcre_dfa_exec()\fP is called with an \fIextra\fP
2755  block that contains a setting of the \fImatch_limit\fP field. This is not  block that contains a setting of the \fImatch_limit\fP or
2756  supported (it is meaningless).  \fImatch_limit_recursion\fP fields. This is not supported (these fields are
2757    meaningless for DFA matching).
2758  .sp  .sp
2759    PCRE_ERROR_DFA_WSSIZE     (-19)    PCRE_ERROR_DFA_WSSIZE     (-19)
2760  .sp  .sp
# Line 1809  When a recursive subpattern is processed Line 2767  When a recursive subpattern is processed
2767  recursively, using private vectors for \fIovector\fP and \fIworkspace\fP. This  recursively, using private vectors for \fIovector\fP and \fIworkspace\fP. This
2768  error is given if the output vector is not large enough. This should be  error is given if the output vector is not large enough. This should be
2769  extremely rare, as a vector of size 1000 is used.  extremely rare, as a vector of size 1000 is used.
2770    .sp
2771      PCRE_ERROR_DFA_BADRESTART (-30)
2772    .sp
2773    When \fBpcre_dfa_exec()\fP is called with the \fBPCRE_DFA_RESTART\fP option,
2774    some plausibility checks are made on the contents of the workspace, which
2775    should contain data about the previous partial match. If any of these checks
2776    fail, this error is given.
2777  .  .
2778  .  .
2779  .SH "SEE ALSO"  .SH "SEE ALSO"
2780  .rs  .rs
2781  .sp  .sp
2782  \fBpcrebuild\fP(3), \fBpcrecallout\fP(3), \fBpcrecpp(3)\fP(3),  \fBpcre16\fP(3), \fBpcre32\fP(3), \fBpcrebuild\fP(3), \fBpcrecallout\fP(3),
2783  \fBpcrematching\fP(3), \fBpcrepartial\fP(3), \fBpcreposix\fP(3),  \fBpcrecpp(3)\fP(3), \fBpcrematching\fP(3), \fBpcrepartial\fP(3),
2784  \fBpcreprecompile\fP(3), \fBpcresample\fP(3), \fBpcrestack\fP(3).  \fBpcreposix\fP(3), \fBpcreprecompile\fP(3), \fBpcresample\fP(3),
2785    \fBpcrestack\fP(3).
2786  .  .
2787  .  .
2788  .SH AUTHOR  .SH AUTHOR
# Line 1833  Cambridge CB2 3QH, England. Line 2799  Cambridge CB2 3QH, England.
2799  .rs  .rs
2800  .sp  .sp
2801  .nf  .nf
2802  Last updated: 06 March 2007  Last updated: 29 October 2012
2803  Copyright (c) 1997-2007 University of Cambridge.  Copyright (c) 1997-2012 University of Cambridge.
2804  .fi  .fi

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