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3  <title>pcreapi specification</title>  <title>pcreapi specification</title>
4  </head>  </head>
5  <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">  <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
6  This HTML document has been generated automatically from the original man page.  <h1>pcreapi man page</h1>
7  If there is any nonsense in it, please consult the man page, in case the  <p>
8  conversion went wrong.<br>  Return to the <a href="index.html">PCRE index page</a>.
9    </p>
10    <p>
11    This page is part of the PCRE HTML documentation. It was generated automatically
12    from the original man page. If there is any nonsense in it, please consult the
13    man page, in case the conversion went wrong.
14    <br>
15  <ul>  <ul>
16  <li><a name="TOC1" href="#SEC1">SYNOPSIS OF PCRE API</a>  <li><a name="TOC1" href="#SEC1">PCRE NATIVE API</a>
17  <li><a name="TOC2" href="#SEC2">PCRE API</a>  <li><a name="TOC2" href="#SEC2">PCRE API OVERVIEW</a>
18  <li><a name="TOC3" href="#SEC3">MULTITHREADING</a>  <li><a name="TOC3" href="#SEC3">NEWLINES</a>
19  <li><a name="TOC4" href="#SEC4">CHECKING BUILD-TIME OPTIONS</a>  <li><a name="TOC4" href="#SEC4">MULTITHREADING</a>
20  <li><a name="TOC5" href="#SEC5">COMPILING A PATTERN</a>  <li><a name="TOC5" href="#SEC5">SAVING PRECOMPILED PATTERNS FOR LATER USE</a>
21  <li><a name="TOC6" href="#SEC6">STUDYING A PATTERN</a>  <li><a name="TOC6" href="#SEC6">CHECKING BUILD-TIME OPTIONS</a>
22  <li><a name="TOC7" href="#SEC7">LOCALE SUPPORT</a>  <li><a name="TOC7" href="#SEC7">COMPILING A PATTERN</a>
23  <li><a name="TOC8" href="#SEC8">INFORMATION ABOUT A PATTERN</a>  <li><a name="TOC8" href="#SEC8">COMPILATION ERROR CODES</a>
24  <li><a name="TOC9" href="#SEC9">OBSOLETE INFO FUNCTION</a>  <li><a name="TOC9" href="#SEC9">STUDYING A PATTERN</a>
25  <li><a name="TOC10" href="#SEC10">MATCHING A PATTERN</a>  <li><a name="TOC10" href="#SEC10">LOCALE SUPPORT</a>
26  <li><a name="TOC11" href="#SEC11">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a>  <li><a name="TOC11" href="#SEC11">INFORMATION ABOUT A PATTERN</a>
27  <li><a name="TOC12" href="#SEC12">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a>  <li><a name="TOC12" href="#SEC12">OBSOLETE INFO FUNCTION</a>
28    <li><a name="TOC13" href="#SEC13">REFERENCE COUNTS</a>
29    <li><a name="TOC14" href="#SEC14">MATCHING A PATTERN: THE TRADITIONAL FUNCTION</a>
30    <li><a name="TOC15" href="#SEC15">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a>
31    <li><a name="TOC16" href="#SEC16">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a>
32    <li><a name="TOC17" href="#SEC17">DUPLICATE SUBPATTERN NAMES</a>
33    <li><a name="TOC18" href="#SEC18">FINDING ALL POSSIBLE MATCHES</a>
34    <li><a name="TOC19" href="#SEC19">MATCHING A PATTERN: THE ALTERNATIVE FUNCTION</a>
35  </ul>  </ul>
36  <br><a name="SEC1" href="#TOC1">SYNOPSIS OF PCRE API</a><br>  <br><a name="SEC1" href="#TOC1">PCRE NATIVE API</a><br>
37  <P>  <P>
38  <b>#include &#60;pcre.h&#62;</b>  <b>#include &#60;pcre.h&#62;</b>
39  </P>  </P>
# Line 30  conversion went wrong.<br> Line 43  conversion went wrong.<br>
43  <b>const unsigned char *<i>tableptr</i>);</b>  <b>const unsigned char *<i>tableptr</i>);</b>
44  </P>  </P>
45  <P>  <P>
46    <b>pcre *pcre_compile2(const char *<i>pattern</i>, int <i>options</i>,</b>
47    <b>int *<i>errorcodeptr</i>,</b>
48    <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
49    <b>const unsigned char *<i>tableptr</i>);</b>
50    </P>
51    <P>
52  <b>pcre_extra *pcre_study(const pcre *<i>code</i>, int <i>options</i>,</b>  <b>pcre_extra *pcre_study(const pcre *<i>code</i>, int <i>options</i>,</b>
53  <b>const char **<i>errptr</i>);</b>  <b>const char **<i>errptr</i>);</b>
54  </P>  </P>
# Line 39  conversion went wrong.<br> Line 58  conversion went wrong.<br>
58  <b>int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>);</b>  <b>int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>);</b>
59  </P>  </P>
60  <P>  <P>
61    <b>int pcre_dfa_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
62    <b>const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
63    <b>int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b>
64    <b>int *<i>workspace</i>, int <i>wscount</i>);</b>
65    </P>
66    <P>
67  <b>int pcre_copy_named_substring(const pcre *<i>code</i>,</b>  <b>int pcre_copy_named_substring(const pcre *<i>code</i>,</b>
68  <b>const char *<i>subject</i>, int *<i>ovector</i>,</b>  <b>const char *<i>subject</i>, int *<i>ovector</i>,</b>
69  <b>int <i>stringcount</i>, const char *<i>stringname</i>,</b>  <b>int <i>stringcount</i>, const char *<i>stringname</i>,</b>
# Line 60  conversion went wrong.<br> Line 85  conversion went wrong.<br>
85  <b>const char *<i>name</i>);</b>  <b>const char *<i>name</i>);</b>
86  </P>  </P>
87  <P>  <P>
88    <b>int pcre_get_stringtable_entries(const pcre *<i>code</i>,</b>
89    <b>const char *<i>name</i>, char **<i>first</i>, char **<i>last</i>);</b>
90    </P>
91    <P>
92  <b>int pcre_get_substring(const char *<i>subject</i>, int *<i>ovector</i>,</b>  <b>int pcre_get_substring(const char *<i>subject</i>, int *<i>ovector</i>,</b>
93  <b>int <i>stringcount</i>, int <i>stringnumber</i>,</b>  <b>int <i>stringcount</i>, int <i>stringnumber</i>,</b>
94  <b>const char **<i>stringptr</i>);</b>  <b>const char **<i>stringptr</i>);</b>
# Line 86  conversion went wrong.<br> Line 115  conversion went wrong.<br>
115  <b>*<i>firstcharptr</i>);</b>  <b>*<i>firstcharptr</i>);</b>
116  </P>  </P>
117  <P>  <P>
118    <b>int pcre_refcount(pcre *<i>code</i>, int <i>adjust</i>);</b>
119    </P>
120    <P>
121  <b>int pcre_config(int <i>what</i>, void *<i>where</i>);</b>  <b>int pcre_config(int <i>what</i>, void *<i>where</i>);</b>
122  </P>  </P>
123  <P>  <P>
# Line 98  conversion went wrong.<br> Line 130  conversion went wrong.<br>
130  <b>void (*pcre_free)(void *);</b>  <b>void (*pcre_free)(void *);</b>
131  </P>  </P>
132  <P>  <P>
133  <b>int (*pcre_callout)(pcre_callout_block *);</b>  <b>void *(*pcre_stack_malloc)(size_t);</b>
134  </P>  </P>
 <br><a name="SEC2" href="#TOC1">PCRE API</a><br>  
135  <P>  <P>
136  PCRE has its own native API, which is described in this document. There is also  <b>void (*pcre_stack_free)(void *);</b>
 a set of wrapper functions that correspond to the POSIX regular expression API.  
 These are described in the <b>pcreposix</b> documentation.  
137  </P>  </P>
138  <P>  <P>
139  The native API function prototypes are defined in the header file <b>pcre.h</b>,  <b>int (*pcre_callout)(pcre_callout_block *);</b>
 and on Unix systems the library itself is called <b>libpcre.a</b>, so can be  
 accessed by adding <b>-lpcre</b> to the command for linking an application which  
 calls it. The header file defines the macros PCRE_MAJOR and PCRE_MINOR to  
 contain the major and minor release numbers for the library. Applications can  
 use these to include support for different releases.  
140  </P>  </P>
141    <br><a name="SEC2" href="#TOC1">PCRE API OVERVIEW</a><br>
142  <P>  <P>
143  The functions <b>pcre_compile()</b>, <b>pcre_study()</b>, and <b>pcre_exec()</b>  PCRE has its own native API, which is described in this document. There is
144  are used for compiling and matching regular expressions. A sample program that  also a set of wrapper functions that correspond to the POSIX regular expression
145  demonstrates the simplest way of using them is given in the file  API. These are described in the
146  <i>pcredemo.c</i>. The <b>pcresample</b> documentation describes how to run it.  <a href="pcreposix.html"><b>pcreposix</b></a>
147    documentation. Both of these APIs define a set of C function calls. A C++
148    wrapper is distributed with PCRE. It is documented in the
149    <a href="pcrecpp.html"><b>pcrecpp</b></a>
150    page.
151  </P>  </P>
152  <P>  <P>
153  There are convenience functions for extracting captured substrings from a  The native API C function prototypes are defined in the header file
154  matched subject string. They are:  <b>pcre.h</b>, and on Unix systems the library itself is called <b>libpcre</b>.
155    It can normally be accessed by adding <b>-lpcre</b> to the command for linking
156    an application that uses PCRE. The header file defines the macros PCRE_MAJOR
157    and PCRE_MINOR to contain the major and minor release numbers for the library.
158    Applications can use these to include support for different releases of PCRE.
159    </P>
160    <P>
161    The functions <b>pcre_compile()</b>, <b>pcre_compile2()</b>, <b>pcre_study()</b>,
162    and <b>pcre_exec()</b> are used for compiling and matching regular expressions
163    in a Perl-compatible manner. A sample program that demonstrates the simplest
164    way of using them is provided in the file called <i>pcredemo.c</i> in the source
165    distribution. The
166    <a href="pcresample.html"><b>pcresample</b></a>
167    documentation describes how to run it.
168    </P>
169    <P>
170    A second matching function, <b>pcre_dfa_exec()</b>, which is not
171    Perl-compatible, is also provided. This uses a different algorithm for the
172    matching. The alternative algorithm finds all possible matches (at a given
173    point in the subject). However, this algorithm does not return captured
174    substrings. A description of the two matching algorithms and their advantages
175    and disadvantages is given in the
176    <a href="pcrematching.html"><b>pcrematching</b></a>
177    documentation.
178  </P>  </P>
179  <P>  <P>
180    In addition to the main compiling and matching functions, there are convenience
181    functions for extracting captured substrings from a subject string that is
182    matched by <b>pcre_exec()</b>. They are:
183  <pre>  <pre>
184    <b>pcre_copy_substring()</b>    <b>pcre_copy_substring()</b>
185    <b>pcre_copy_named_substring()</b>    <b>pcre_copy_named_substring()</b>
186    <b>pcre_get_substring()</b>    <b>pcre_get_substring()</b>
187    <b>pcre_get_named_substring()</b>    <b>pcre_get_named_substring()</b>
188    <b>pcre_get_substring_list()</b>    <b>pcre_get_substring_list()</b>
189  </PRE>    <b>pcre_get_stringnumber()</b>
190  </P>    <b>pcre_get_stringtable_entries()</b>
191  <P>  </pre>
192  <b>pcre_free_substring()</b> and <b>pcre_free_substring_list()</b> are also  <b>pcre_free_substring()</b> and <b>pcre_free_substring_list()</b> are also
193  provided, to free the memory used for extracted strings.  provided, to free the memory used for extracted strings.
194  </P>  </P>
195  <P>  <P>
196  The function <b>pcre_maketables()</b> is used (optionally) to build a set of  The function <b>pcre_maketables()</b> is used to build a set of character tables
197  character tables in the current locale for passing to <b>pcre_compile()</b>.  in the current locale for passing to <b>pcre_compile()</b>, <b>pcre_exec()</b>,
198    or <b>pcre_dfa_exec()</b>. This is an optional facility that is provided for
199    specialist use. Most commonly, no special tables are passed, in which case
200    internal tables that are generated when PCRE is built are used.
201  </P>  </P>
202  <P>  <P>
203  The function <b>pcre_fullinfo()</b> is used to find out information about a  The function <b>pcre_fullinfo()</b> is used to find out information about a
204  compiled pattern; <b>pcre_info()</b> is an obsolete version which returns only  compiled pattern; <b>pcre_info()</b> is an obsolete version that returns only
205  some of the available information, but is retained for backwards compatibility.  some of the available information, but is retained for backwards compatibility.
206  The function <b>pcre_version()</b> returns a pointer to a string containing the  The function <b>pcre_version()</b> returns a pointer to a string containing the
207  version of PCRE and its date of release.  version of PCRE and its date of release.
208  </P>  </P>
209  <P>  <P>
210    The function <b>pcre_refcount()</b> maintains a reference count in a data block
211    containing a compiled pattern. This is provided for the benefit of
212    object-oriented applications.
213    </P>
214    <P>
215  The global variables <b>pcre_malloc</b> and <b>pcre_free</b> initially contain  The global variables <b>pcre_malloc</b> and <b>pcre_free</b> initially contain
216  the entry points of the standard <b>malloc()</b> and <b>free()</b> functions  the entry points of the standard <b>malloc()</b> and <b>free()</b> functions,
217  respectively. PCRE calls the memory management functions via these variables,  respectively. PCRE calls the memory management functions via these variables,
218  so a calling program can replace them if it wishes to intercept the calls. This  so a calling program can replace them if it wishes to intercept the calls. This
219  should be done before calling any PCRE functions.  should be done before calling any PCRE functions.
220  </P>  </P>
221  <P>  <P>
222    The global variables <b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> are also
223    indirections to memory management functions. These special functions are used
224    only when PCRE is compiled to use the heap for remembering data, instead of
225    recursive function calls, when running the <b>pcre_exec()</b> function. See the
226    <a href="pcrebuild.html"><b>pcrebuild</b></a>
227    documentation for details of how to do this. It is a non-standard way of
228    building PCRE, for use in environments that have limited stacks. Because of the
229    greater use of memory management, it runs more slowly. Separate functions are
230    provided so that special-purpose external code can be used for this case. When
231    used, these functions are always called in a stack-like manner (last obtained,
232    first freed), and always for memory blocks of the same size. There is a
233    discussion about PCRE's stack usage in the
234    <a href="pcrestack.html"><b>pcrestack</b></a>
235    documentation.
236    </P>
237    <P>
238  The global variable <b>pcre_callout</b> initially contains NULL. It can be set  The global variable <b>pcre_callout</b> initially contains NULL. It can be set
239  by the caller to a "callout" function, which PCRE will then call at specified  by the caller to a "callout" function, which PCRE will then call at specified
240  points during a matching operation. Details are given in the <b>pcrecallout</b>  points during a matching operation. Details are given in the
241    <a href="pcrecallout.html"><b>pcrecallout</b></a>
242  documentation.  documentation.
243  </P>  </P>
244  <br><a name="SEC3" href="#TOC1">MULTITHREADING</a><br>  <br><a name="SEC3" href="#TOC1">NEWLINES</a><br>
245    <P>
246    PCRE supports three different conventions for indicating line breaks in
247    strings: a single CR character, a single LF character, or the two-character
248    sequence CRLF. All three are used as "standard" by different operating systems.
249    When PCRE is built, a default can be specified. The default default is LF,
250    which is the Unix standard. When PCRE is run, the default can be overridden,
251    either when a pattern is compiled, or when it is matched.
252    <br>
253    <br>
254    In the PCRE documentation the word "newline" is used to mean "the character or
255    pair of characters that indicate a line break".
256    </P>
257    <br><a name="SEC4" href="#TOC1">MULTITHREADING</a><br>
258  <P>  <P>
259  The PCRE functions can be used in multi-threading applications, with the  The PCRE functions can be used in multi-threading applications, with the
260  proviso that the memory management functions pointed to by <b>pcre_malloc</b>  proviso that the memory management functions pointed to by <b>pcre_malloc</b>,
261  and <b>pcre_free</b>, and the callout function pointed to by <b>pcre_callout</b>,  <b>pcre_free</b>, <b>pcre_stack_malloc</b>, and <b>pcre_stack_free</b>, and the
262  are shared by all threads.  callout function pointed to by <b>pcre_callout</b>, are shared by all threads.
263  </P>  </P>
264  <P>  <P>
265  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
266  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.
267  </P>  </P>
268  <br><a name="SEC4" href="#TOC1">CHECKING BUILD-TIME OPTIONS</a><br>  <br><a name="SEC5" href="#TOC1">SAVING PRECOMPILED PATTERNS FOR LATER USE</a><br>
269    <P>
270    The compiled form of a regular expression can be saved and re-used at a later
271    time, possibly by a different program, and even on a host other than the one on
272    which it was compiled. Details are given in the
273    <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
274    documentation.
275    </P>
276    <br><a name="SEC6" href="#TOC1">CHECKING BUILD-TIME OPTIONS</a><br>
277  <P>  <P>
278  <b>int pcre_config(int <i>what</i>, void *<i>where</i>);</b>  <b>int pcre_config(int <i>what</i>, void *<i>where</i>);</b>
279  </P>  </P>
# Line 186  documentation has more details about the Line 287  documentation has more details about the
287  The first argument for <b>pcre_config()</b> is an integer, specifying which  The first argument for <b>pcre_config()</b> is an integer, specifying which
288  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
289  which the information is placed. The following information is available:  which the information is placed. The following information is available:
 </P>  
 <P>  
290  <pre>  <pre>
291    PCRE_CONFIG_UTF8    PCRE_CONFIG_UTF8
292  </PRE>  </pre>
 </P>  
 <P>  
293  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;
294  otherwise it is set to zero.  otherwise it is set to zero.
295  </P>  <pre>
296  <P>    PCRE_CONFIG_UNICODE_PROPERTIES
297    </pre>
298    The output is an integer that is set to one if support for Unicode character
299    properties is available; otherwise it is set to zero.
300  <pre>  <pre>
301    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
302  </PRE>  </pre>
303  </P>  The output is an integer whose value specifies the default character sequence
304  <P>  that is recognized as meaning "newline". The three values that are supported
305  The output is an integer that is set to the value of the code that is used for  are: 10 for LF, 13 for CR, and 3338 for CRLF. The default should normally be
306  the newline character. It is either linefeed (10) or carriage return (13), and  the standard sequence for your operating system.
 should normally be the standard character for your operating system.  
 </P>  
 <P>  
307  <pre>  <pre>
308    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
309  </PRE>  </pre>
 </P>  
 <P>  
310  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
311  linkage in compiled regular expressions. The value is 2, 3, or 4. Larger values  linkage in compiled regular expressions. The value is 2, 3, or 4. Larger values
312  allow larger regular expressions to be compiled, at the expense of slower  allow larger regular expressions to be compiled, at the expense of slower
313  matching. The default value of 2 is sufficient for all but the most massive  matching. The default value of 2 is sufficient for all but the most massive
314  patterns, since it allows the compiled pattern to be up to 64K in size.  patterns, since it allows the compiled pattern to be up to 64K in size.
 </P>  
 <P>  
315  <pre>  <pre>
316    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
317  </PRE>  </pre>
 </P>  
 <P>  
318  The output is an integer that contains the threshold above which the POSIX  The output is an integer that contains the threshold above which the POSIX
319  interface uses <b>malloc()</b> for output vectors. Further details are given in  interface uses <b>malloc()</b> for output vectors. Further details are given in
320  the <b>pcreposix</b> documentation.  the
321  </P>  <a href="pcreposix.html"><b>pcreposix</b></a>
322  <P>  documentation.
323  <pre>  <pre>
324    PCRE_CONFIG_MATCH_LIMIT    PCRE_CONFIG_MATCH_LIMIT
325  </PRE>  </pre>
 </P>  
 <P>  
326  The output is an integer that gives the default limit for the number of  The output is an integer that gives the default limit for the number of
327  internal matching function calls in a <b>pcre_exec()</b> execution. Further  internal matching function calls in a <b>pcre_exec()</b> execution. Further
328  details are given with <b>pcre_exec()</b> below.  details are given with <b>pcre_exec()</b> below.
329    <pre>
330      PCRE_CONFIG_MATCH_LIMIT_RECURSION
331    </pre>
332    The output is an integer that gives the default limit for the depth of
333    recursion when calling the internal matching function in a <b>pcre_exec()</b>
334    execution. Further details are given with <b>pcre_exec()</b> below.
335    <pre>
336      PCRE_CONFIG_STACKRECURSE
337    </pre>
338    The output is an integer that is set to one if internal recursion when running
339    <b>pcre_exec()</b> is implemented by recursive function calls that use the stack
340    to remember their state. This is the usual way that PCRE is compiled. The
341    output is zero if PCRE was compiled to use blocks of data on the heap instead
342    of recursive function calls. In this case, <b>pcre_stack_malloc</b> and
343    <b>pcre_stack_free</b> are called to manage memory blocks on the heap, thus
344    avoiding the use of the stack.
345  </P>  </P>
346  <br><a name="SEC5" href="#TOC1">COMPILING A PATTERN</a><br>  <br><a name="SEC7" href="#TOC1">COMPILING A PATTERN</a><br>
347  <P>  <P>
348  <b>pcre *pcre_compile(const char *<i>pattern</i>, int <i>options</i>,</b>  <b>pcre *pcre_compile(const char *<i>pattern</i>, int <i>options</i>,</b>
349  <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b>  <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
350  <b>const unsigned char *<i>tableptr</i>);</b>  <b>const unsigned char *<i>tableptr</i>);</b>
351    <b>pcre *pcre_compile2(const char *<i>pattern</i>, int <i>options</i>,</b>
352    <b>int *<i>errorcodeptr</i>,</b>
353    <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
354    <b>const unsigned char *<i>tableptr</i>);</b>
355  </P>  </P>
356  <P>  <P>
357  The function <b>pcre_compile()</b> is called to compile a pattern into an  Either of the functions <b>pcre_compile()</b> or <b>pcre_compile2()</b> can be
358  internal form. The pattern is a C string terminated by a binary zero, and  called to compile a pattern into an internal form. The only difference between
359  is passed in the argument <i>pattern</i>. A pointer to a single block of memory  the two interfaces is that <b>pcre_compile2()</b> has an additional argument,
360  that is obtained via <b>pcre_malloc</b> is returned. This contains the compiled  <i>errorcodeptr</i>, via which a numerical error code can be returned.
361  code and related data. The <b>pcre</b> type is defined for the returned block;  </P>
362  this is a typedef for a structure whose contents are not externally defined. It  <P>
363  is up to the caller to free the memory when it is no longer required.  The pattern is a C string terminated by a binary zero, and is passed in the
364    <i>pattern</i> argument. A pointer to a single block of memory that is obtained
365    via <b>pcre_malloc</b> is returned. This contains the compiled code and related
366    data. The <b>pcre</b> type is defined for the returned block; this is a typedef
367    for a structure whose contents are not externally defined. It is up to the
368    caller to free the memory (via <b>pcre_free</b>) when it is no longer required.
369  </P>  </P>
370  <P>  <P>
371  Although the compiled code of a PCRE regex is relocatable, that is, it does not  Although the compiled code of a PCRE regex is relocatable, that is, it does not
372  depend on memory location, the complete <b>pcre</b> data block is not  depend on memory location, the complete <b>pcre</b> data block is not
373  fully relocatable, because it contains a copy of the <i>tableptr</i> argument,  fully relocatable, because it may contain a copy of the <i>tableptr</i>
374  which is an address (see below).  argument, which is an address (see below).
375  </P>  </P>
376  <P>  <P>
377  The <i>options</i> argument contains independent bits that affect the  The <i>options</i> argument contains independent bits that affect the
378  compilation. It should be zero if no options are required. Some of the options,  compilation. It should be zero if no options are required. The available
379  in particular, those that are compatible with Perl, can also be set and unset  options are described below. Some of them, in particular, those that are
380  from within the pattern (see the detailed description of regular expressions  compatible with Perl, can also be set and unset from within the pattern (see
381  in the <b>pcrepattern</b> documentation). For these options, the contents of the  the detailed description in the
382  <i>options</i> argument specifies their initial settings at the start of  <a href="pcrepattern.html"><b>pcrepattern</b></a>
383  compilation and execution. The PCRE_ANCHORED option can be set at the time of  documentation). For these options, the contents of the <i>options</i> argument
384    specifies their initial settings at the start of compilation and execution. The
385    PCRE_ANCHORED and PCRE_NEWLINE_<i>xxx</i> options can be set at the time of
386  matching as well as at compile time.  matching as well as at compile time.
387  </P>  </P>
388  <P>  <P>
389  If <i>errptr</i> is NULL, <b>pcre_compile()</b> returns NULL immediately.  If <i>errptr</i> is NULL, <b>pcre_compile()</b> returns NULL immediately.
390  Otherwise, if compilation of a pattern fails, <b>pcre_compile()</b> returns  Otherwise, if compilation of a pattern fails, <b>pcre_compile()</b> returns
391  NULL, and sets the variable pointed to by <i>errptr</i> to point to a textual  NULL, and sets the variable pointed to by <i>errptr</i> to point to a textual
392  error message. The offset from the start of the pattern to the character where  error message. This is a static string that is part of the library. You must
393  the error was discovered is placed in the variable pointed to by  not try to free it. The offset from the start of the pattern to the character
394    where the error was discovered is placed in the variable pointed to by
395  <i>erroffset</i>, which must not be NULL. If it is, an immediate error is given.  <i>erroffset</i>, which must not be NULL. If it is, an immediate error is given.
396  </P>  </P>
397  <P>  <P>
398  If the final argument, <i>tableptr</i>, is NULL, PCRE uses a default set of  If <b>pcre_compile2()</b> is used instead of <b>pcre_compile()</b>, and the
399  character tables which are built when it is compiled, using the default C  <i>errorcodeptr</i> argument is not NULL, a non-zero error code number is
400  locale. Otherwise, <i>tableptr</i> must be the result of a call to  returned via this argument in the event of an error. This is in addition to the
401  <b>pcre_maketables()</b>. See the section on locale support below.  textual error message. Error codes and messages are listed below.
402  </P>  </P>
403  <P>  <P>
404  This code fragment shows a typical straightforward call to <b>pcre_compile()</b>:  If the final argument, <i>tableptr</i>, is NULL, PCRE uses a default set of
405    character tables that are built when PCRE is compiled, using the default C
406    locale. Otherwise, <i>tableptr</i> must be an address that is the result of a
407    call to <b>pcre_maketables()</b>. This value is stored with the compiled
408    pattern, and used again by <b>pcre_exec()</b>, unless another table pointer is
409    passed to it. For more discussion, see the section on locale support below.
410  </P>  </P>
411  <P>  <P>
412    This code fragment shows a typical straightforward call to <b>pcre_compile()</b>:
413  <pre>  <pre>
414    pcre *re;    pcre *re;
415    const char *error;    const char *error;
# Line 297  This code fragment shows a typical strai Line 420  This code fragment shows a typical strai
420      &error,           /* for error message */      &error,           /* for error message */
421      &erroffset,       /* for error offset */      &erroffset,       /* for error offset */
422      NULL);            /* use default character tables */      NULL);            /* use default character tables */
423  </PRE>  </pre>
424  </P>  The following names for option bits are defined in the <b>pcre.h</b> header
425  <P>  file:
 The following option bits are defined:  
 </P>  
 <P>  
426  <pre>  <pre>
427    PCRE_ANCHORED    PCRE_ANCHORED
428  </PRE>  </pre>
 </P>  
 <P>  
429  If this bit is set, the pattern is forced to be "anchored", that is, it is  If this bit is set, the pattern is forced to be "anchored", that is, it is
430  constrained to match only at the first matching point in the string which is  constrained to match only at the first matching point in the string that is
431  being searched (the "subject string"). This effect can also be achieved by  being searched (the "subject string"). This effect can also be achieved by
432  appropriate constructs in the pattern itself, which is the only way to do it in  appropriate constructs in the pattern itself, which is the only way to do it in
433  Perl.  Perl.
434  </P>  <pre>
435  <P>    PCRE_AUTO_CALLOUT
436    </pre>
437    If this bit is set, <b>pcre_compile()</b> automatically inserts callout items,
438    all with number 255, before each pattern item. For discussion of the callout
439    facility, see the
440    <a href="pcrecallout.html"><b>pcrecallout</b></a>
441    documentation.
442  <pre>  <pre>
443    PCRE_CASELESS    PCRE_CASELESS
444  </PRE>  </pre>
 </P>  
 <P>  
445  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
446  letters. It is equivalent to Perl's /i option, and it can be changed within a  letters. It is equivalent to Perl's /i option, and it can be changed within a
447  pattern by a (?i) option setting.  pattern by a (?i) option setting. In UTF-8 mode, PCRE always understands the
448  </P>  concept of case for characters whose values are less than 128, so caseless
449  <P>  matching is always possible. For characters with higher values, the concept of
450    case is supported if PCRE is compiled with Unicode property support, but not
451    otherwise. If you want to use caseless matching for characters 128 and above,
452    you must ensure that PCRE is compiled with Unicode property support as well as
453    with UTF-8 support.
454  <pre>  <pre>
455    PCRE_DOLLAR_ENDONLY    PCRE_DOLLAR_ENDONLY
456  </PRE>  </pre>
 </P>  
 <P>  
457  If this bit is set, a dollar metacharacter in the pattern matches only at the  If this bit is set, a dollar metacharacter in the pattern matches only at the
458  end of the subject string. Without this option, a dollar also matches  end of the subject string. Without this option, a dollar also matches
459  immediately before the final character if it is a newline (but not before any  immediately before a newline at the end of the string (but not before any other
460  other newlines). The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is  newlines). The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is set.
461  set. There is no equivalent to this option in Perl, and no way to set it within  There is no equivalent to this option in Perl, and no way to set it within a
462  a pattern.  pattern.
 </P>  
 <P>  
463  <pre>  <pre>
464    PCRE_DOTALL    PCRE_DOTALL
465  </PRE>  </pre>
 </P>  
 <P>  
466  If this bit is set, a dot metacharater in the pattern matches all characters,  If this bit is set, a dot metacharater in the pattern matches all characters,
467  including newlines. Without it, newlines are excluded. This option is  including those that indicate newline. Without it, a dot does not match when
468  equivalent to Perl's /s option, and it can be changed within a pattern by a  the current position is at a newline. This option is equivalent to Perl's /s
469  (?s) option setting. A negative class such as [^a] always matches a newline  option, and it can be changed within a pattern by a (?s) option setting. A
470  character, independent of the setting of this option.  negative class such as [^a] always matches newlines, independent of the setting
471  </P>  of this option.
472  <P>  <pre>
473      PCRE_DUPNAMES
474    </pre>
475    If this bit is set, names used to identify capturing subpatterns need not be
476    unique. This can be helpful for certain types of pattern when it is known that
477    only one instance of the named subpattern can ever be matched. There are more
478    details of named subpatterns below; see also the
479    <a href="pcrepattern.html"><b>pcrepattern</b></a>
480    documentation.
481  <pre>  <pre>
482    PCRE_EXTENDED    PCRE_EXTENDED
483  </PRE>  </pre>
 </P>  
 <P>  
484  If this bit is set, whitespace data characters in the pattern are totally  If this bit is set, whitespace data characters in the pattern are totally
485  ignored except when escaped or inside a character class. Whitespace does not  ignored except when escaped or inside a character class. Whitespace does not
486  include the VT character (code 11). In addition, characters between an  include the VT character (code 11). In addition, characters between an
487  unescaped # outside a character class and the next newline character,  unescaped # outside a character class and the next newline, inclusive, are also
488  inclusive, are also ignored. This is equivalent to Perl's /x option, and it can  ignored. This is equivalent to Perl's /x option, and it can be changed within a
489  be changed within a pattern by a (?x) option setting.  pattern by a (?x) option setting.
490  </P>  </P>
491  <P>  <P>
492  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
493  Note, however, that this applies only to data characters. Whitespace characters  Note, however, that this applies only to data characters. Whitespace characters
494  may never appear within special character sequences in a pattern, for example  may never appear within special character sequences in a pattern, for example
495  within the sequence (?( which introduces a conditional subpattern.  within the sequence (?( which introduces a conditional subpattern.
 </P>  
 <P>  
496  <pre>  <pre>
497    PCRE_EXTRA    PCRE_EXTRA
498  </PRE>  </pre>
 </P>  
 <P>  
499  This option was invented in order to turn on additional functionality of PCRE  This option was invented in order to turn on additional functionality of PCRE
500  that is incompatible with Perl, but it is currently of very little use. When  that is incompatible with Perl, but it is currently of very little use. When
501  set, any backslash in a pattern that is followed by a letter that has no  set, any backslash in a pattern that is followed by a letter that has no
502  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
503  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
504  special meaning is treated as a literal. There are at present no other features  special meaning is treated as a literal. (Perl can, however, be persuaded to
505  controlled by this option. It can also be set by a (?X) option setting within a  give a warning for this.) There are at present no other features controlled by
506  pattern.  this option. It can also be set by a (?X) option setting within a pattern.
507  </P>  <pre>
508  <P>    PCRE_FIRSTLINE
509    </pre>
510    If this option is set, an unanchored pattern is required to match before or at
511    the first newline in the subject string, though the matched text may continue
512    over the newline.
513  <pre>  <pre>
514    PCRE_MULTILINE    PCRE_MULTILINE
515  </PRE>  </pre>
516  </P>  By default, PCRE treats the subject string as consisting of a single line of
517  <P>  characters (even if it actually contains newlines). The "start of line"
 By default, PCRE treats the subject string as consisting of a single "line" of  
 characters (even if it actually contains several newlines). The "start of line"  
518  metacharacter (^) matches only at the start of the string, while the "end of  metacharacter (^) matches only at the start of the string, while the "end of
519  line" metacharacter ($) matches only at the end of the string, or before a  line" metacharacter ($) matches only at the end of the string, or before a
520  terminating newline (unless PCRE_DOLLAR_ENDONLY is set). This is the same as  terminating newline (unless PCRE_DOLLAR_ENDONLY is set). This is the same as
# Line 398  Perl. Line 522  Perl.
522  </P>  </P>
523  <P>  <P>
524  When PCRE_MULTILINE it is set, the "start of line" and "end of line" constructs  When PCRE_MULTILINE it is set, the "start of line" and "end of line" constructs
525  match immediately following or immediately before any newline in the subject  match immediately following or immediately before internal newlines in the
526  string, respectively, as well as at the very start and end. This is equivalent  subject string, respectively, as well as at the very start and end. This is
527  to Perl's /m option, and it can be changed within a pattern by a (?m) option  equivalent to Perl's /m option, and it can be changed within a pattern by a
528  setting. If there are no "\n" characters in a subject string, or no  (?m) option setting. If there are no newlines in a subject string, or no
529  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.
530    <pre>
531      PCRE_NEWLINE_CR
532      PCRE_NEWLINE_LF
533      PCRE_NEWLINE_CRLF
534    </pre>
535    These options override the default newline definition that was chosen when PCRE
536    was built. Setting the first or the second specifies that a newline is
537    indicated by a single character (CR or LF, respectively). Setting both of them
538    specifies that a newline is indicated by the two-character CRLF sequence. For
539    convenience, PCRE_NEWLINE_CRLF is defined to contain both bits. The only time
540    that a line break is relevant when compiling a pattern is if PCRE_EXTENDED is
541    set, and an unescaped # outside a character class is encountered. This
542    indicates a comment that lasts until after the next newline.
543  </P>  </P>
544  <P>  <P>
545    The newline option set at compile time becomes the default that is used for
546    <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>, but it can be overridden.
547  <pre>  <pre>
548    PCRE_NO_AUTO_CAPTURE    PCRE_NO_AUTO_CAPTURE
549  </PRE>  </pre>
 </P>  
 <P>  
550  If this option is set, it disables the use of numbered capturing parentheses in  If this option is set, it disables the use of numbered capturing parentheses in
551  the pattern. Any opening parenthesis that is not followed by ? behaves as if it  the pattern. Any opening parenthesis that is not followed by ? behaves as if it
552  were followed by ?: but named parentheses can still be used for capturing (and  were followed by ?: but named parentheses can still be used for capturing (and
553  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
554  in Perl.  in Perl.
 </P>  
 <P>  
555  <pre>  <pre>
556    PCRE_UNGREEDY    PCRE_UNGREEDY
557  </PRE>  </pre>
 </P>  
 <P>  
558  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
559  greedy by default, but become greedy if followed by "?". It is not compatible  greedy by default, but become greedy if followed by "?". It is not compatible
560  with Perl. It can also be set by a (?U) option setting within the pattern.  with Perl. It can also be set by a (?U) option setting within the pattern.
 </P>  
 <P>  
561  <pre>  <pre>
562    PCRE_UTF8    PCRE_UTF8
563  </PRE>  </pre>
 </P>  
 <P>  
564  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
565  of UTF-8 characters instead of single-byte character strings. However, it is  of UTF-8 characters instead of single-byte character strings. However, it is
566  available only if PCRE has been built to include UTF-8 support. If not, the use  available only when PCRE is built to include UTF-8 support. If not, the use
567  of this option provokes an error. Details of how this option changes the  of this option provokes an error. Details of how this option changes the
568  behaviour of PCRE are given in the  behaviour of PCRE are given in the
569  <a href="pcre.html#utf8support">section on UTF-8 support</a>  <a href="pcre.html#utf8support">section on UTF-8 support</a>
570  in the main  in the main
571  <a href="pcre.html"><b>pcre</b></a>  <a href="pcre.html"><b>pcre</b></a>
572  page.  page.
573    <pre>
574      PCRE_NO_UTF8_CHECK
575    </pre>
576    When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
577    automatically checked. If an invalid UTF-8 sequence of bytes is found,
578    <b>pcre_compile()</b> returns an error. If you already know that your pattern is
579    valid, and you want to skip this check for performance reasons, you can set the
580    PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid
581    UTF-8 string as a pattern is undefined. It may cause your program to crash.
582    Note that this option can also be passed to <b>pcre_exec()</b> and
583    <b>pcre_dfa_exec()</b>, to suppress the UTF-8 validity checking of subject
584    strings.
585    </P>
586    <br><a name="SEC8" href="#TOC1">COMPILATION ERROR CODES</a><br>
587    <P>
588    The following table lists the error codes than may be returned by
589    <b>pcre_compile2()</b>, along with the error messages that may be returned by
590    both compiling functions.
591    <pre>
592       0  no error
593       1  \ at end of pattern
594       2  \c at end of pattern
595       3  unrecognized character follows \
596       4  numbers out of order in {} quantifier
597       5  number too big in {} quantifier
598       6  missing terminating ] for character class
599       7  invalid escape sequence in character class
600       8  range out of order in character class
601       9  nothing to repeat
602      10  operand of unlimited repeat could match the empty string
603      11  internal error: unexpected repeat
604      12  unrecognized character after (?
605      13  POSIX named classes are supported only within a class
606      14  missing )
607      15  reference to non-existent subpattern
608      16  erroffset passed as NULL
609      17  unknown option bit(s) set
610      18  missing ) after comment
611      19  parentheses nested too deeply
612      20  regular expression too large
613      21  failed to get memory
614      22  unmatched parentheses
615      23  internal error: code overflow
616      24  unrecognized character after (?&#60;
617      25  lookbehind assertion is not fixed length
618      26  malformed number or name after (?(
619      27  conditional group contains more than two branches
620      28  assertion expected after (?(
621      29  (?R or (?digits must be followed by )
622      30  unknown POSIX class name
623      31  POSIX collating elements are not supported
624      32  this version of PCRE is not compiled with PCRE_UTF8 support
625      33  spare error
626      34  character value in \x{...} sequence is too large
627      35  invalid condition (?(0)
628      36  \C not allowed in lookbehind assertion
629      37  PCRE does not support \L, \l, \N, \U, or \u
630      38  number after (?C is &#62; 255
631      39  closing ) for (?C expected
632      40  recursive call could loop indefinitely
633      41  unrecognized character after (?P
634      42  syntax error after (?P
635      43  two named subpatterns have the same name
636      44  invalid UTF-8 string
637      45  support for \P, \p, and \X has not been compiled
638      46  malformed \P or \p sequence
639      47  unknown property name after \P or \p
640      48  subpattern name is too long (maximum 32 characters)
641      49  too many named subpatterns (maximum 10,000)
642      50  repeated subpattern is too long
643      51  octal value is greater than \377 (not in UTF-8 mode)
644    </PRE>
645  </P>  </P>
646  <br><a name="SEC6" href="#TOC1">STUDYING A PATTERN</a><br>  <br><a name="SEC9" href="#TOC1">STUDYING A PATTERN</a><br>
647  <P>  <P>
648  <b>pcre_extra *pcre_study(const pcre *<i>code</i>, int <i>options</i>,</b>  <b>pcre_extra *pcre_study(const pcre *<i>code</i>, int <i>options</i></b>
649  <b>const char **<i>errptr</i>);</b>  <b>const char **<i>errptr</i>);</b>
650  </P>  </P>
651  <P>  <P>
652  When a pattern is going to be used several times, it is worth spending more  If a compiled pattern is going to be used several times, it is worth spending
653  time analyzing it in order to speed up the time taken for matching. The  more time analyzing it in order to speed up the time taken for matching. The
654  function <b>pcre_study()</b> takes a pointer to a compiled pattern as its first  function <b>pcre_study()</b> takes a pointer to a compiled pattern as its first
655  argument. If studing the pattern produces additional information that will help  argument. If studying the pattern produces additional information that will
656  speed up matching, <b>pcre_study()</b> returns a pointer to a <b>pcre_extra</b>  help speed up matching, <b>pcre_study()</b> returns a pointer to a
657  block, in which the <i>study_data</i> field points to the results of the study.  <b>pcre_extra</b> block, in which the <i>study_data</i> field points to the
658    results of the study.
659  </P>  </P>
660  <P>  <P>
661  The returned value from a <b>pcre_study()</b> can be passed directly to  The returned value from <b>pcre_study()</b> can be passed directly to
662  <b>pcre_exec()</b>. However, the <b>pcre_extra</b> block also contains other  <b>pcre_exec()</b>. However, a <b>pcre_extra</b> block also contains other
663  fields that can be set by the caller before the block is passed; these are  fields that can be set by the caller before the block is passed; these are
664  described below. If studying the pattern does not produce any additional  described
665  information, <b>pcre_study()</b> returns NULL. In that circumstance, if the  <a href="#extradata">below</a>
666  calling program wants to pass some of the other fields to <b>pcre_exec()</b>, it  in the section on matching a pattern.
667  must set up its own <b>pcre_extra</b> block.  </P>
668    <P>
669    If studying the pattern does not produce any additional information
670    <b>pcre_study()</b> returns NULL. In that circumstance, if the calling program
671    wants to pass any of the other fields to <b>pcre_exec()</b>, it must set up its
672    own <b>pcre_extra</b> block.
673  </P>  </P>
674  <P>  <P>
675  The second argument contains option bits. At present, no options are defined  The second argument of <b>pcre_study()</b> contains option bits. At present, no
676  for <b>pcre_study()</b>, and this argument should always be zero.  options are defined, and this argument should always be zero.
677  </P>  </P>
678  <P>  <P>
679  The third argument for <b>pcre_study()</b> is a pointer for an error message. If  The third argument for <b>pcre_study()</b> is a pointer for an error message. If
680  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
681  set to NULL. Otherwise it points to a textual error message. You should  set to NULL. Otherwise it is set to point to a textual error message. This is a
682  therefore test the error pointer for NULL after calling <b>pcre_study()</b>, to  static string that is part of the library. You must not try to free it. You
683  be sure that it has run successfully.  should test the error pointer for NULL after calling <b>pcre_study()</b>, to be
684    sure that it has run successfully.
685  </P>  </P>
686  <P>  <P>
687  This is a typical call to <b>pcre_study</b>():  This is a typical call to <b>pcre_study</b>():
 </P>  
 <P>  
688  <pre>  <pre>
689    pcre_extra *pe;    pcre_extra *pe;
690    pe = pcre_study(    pe = pcre_study(
691      re,             /* result of pcre_compile() */      re,             /* result of pcre_compile() */
692      0,              /* no options exist */      0,              /* no options exist */
693      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
694  </PRE>  </pre>
 </P>  
 <P>  
695  At present, studying a pattern is useful only for non-anchored patterns that do  At present, studying a pattern is useful only for non-anchored patterns that do
696  not have a single fixed starting character. A bitmap of possible starting  not have a single fixed starting character. A bitmap of possible starting
697  characters is created.  bytes is created.
698  </P>  <a name="localesupport"></a></P>
699  <a name="localesupport"></a><br><a name="SEC7" href="#TOC1">LOCALE SUPPORT</a><br>  <br><a name="SEC10" href="#TOC1">LOCALE SUPPORT</a><br>
700  <P>  <P>
701  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters
702  digits, or whatever, by reference to a set of tables. When running in UTF-8  digits, or whatever, by reference to a set of tables, indexed by character
703  mode, this applies only to characters with codes less than 256. The library  value. When running in UTF-8 mode, this applies only to characters with codes
704  contains a default set of tables that is created in the default C locale when  less than 128. Higher-valued codes never match escapes such as \w or \d, but
705  PCRE is compiled. This is used when the final argument of <b>pcre_compile()</b>  can be tested with \p if PCRE is built with Unicode character property
706  is NULL, and is sufficient for many applications.  support. The use of locales with Unicode is discouraged.
707  </P>  </P>
708  <P>  <P>
709  An alternative set of tables can, however, be supplied. Such tables are built  An internal set of tables is created in the default C locale when PCRE is
710  by calling the <b>pcre_maketables()</b> function, which has no arguments, in the  built. This is used when the final argument of <b>pcre_compile()</b> is NULL,
711  relevant locale. The result can then be passed to <b>pcre_compile()</b> as often  and is sufficient for many applications. An alternative set of tables can,
712  as necessary. For example, to build and use tables that are appropriate for the  however, be supplied. These may be created in a different locale from the
713  French locale (where accented characters with codes greater than 128 are  default. As more and more applications change to using Unicode, the need for
714  treated as letters), the following code could be used:  this locale support is expected to die away.
715  </P>  </P>
716  <P>  <P>
717    External tables are built by calling the <b>pcre_maketables()</b> function,
718    which has no arguments, in the relevant locale. The result can then be passed
719    to <b>pcre_compile()</b> or <b>pcre_exec()</b> as often as necessary. For
720    example, to build and use tables that are appropriate for the French locale
721    (where accented characters with values greater than 128 are treated as letters),
722    the following code could be used:
723  <pre>  <pre>
724    setlocale(LC_CTYPE, "fr");    setlocale(LC_CTYPE, "fr_FR");
725    tables = pcre_maketables();    tables = pcre_maketables();
726    re = pcre_compile(..., tables);    re = pcre_compile(..., tables);
727  </PRE>  </pre>
728    When <b>pcre_maketables()</b> runs, the tables are built in memory that is
729    obtained via <b>pcre_malloc</b>. It is the caller's responsibility to ensure
730    that the memory containing the tables remains available for as long as it is
731    needed.
732  </P>  </P>
733  <P>  <P>
734  The tables are built in memory that is obtained via <b>pcre_malloc</b>. The  The pointer that is passed to <b>pcre_compile()</b> is saved with the compiled
 pointer that is passed to <b>pcre_compile</b> is saved with the compiled  
735  pattern, and the same tables are used via this pointer by <b>pcre_study()</b>  pattern, and the same tables are used via this pointer by <b>pcre_study()</b>
736  and <b>pcre_exec()</b>. Thus, for any single pattern, compilation, studying and  and normally also by <b>pcre_exec()</b>. Thus, by default, for any single
737  matching all happen in the same locale, but different patterns can be compiled  pattern, compilation, studying and matching all happen in the same locale, but
738  in different locales. It is the caller's responsibility to ensure that the  different patterns can be compiled in different locales.
 memory containing the tables remains available for as long as it is needed.  
739  </P>  </P>
740  <br><a name="SEC8" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br>  <P>
741    It is possible to pass a table pointer or NULL (indicating the use of the
742    internal tables) to <b>pcre_exec()</b>. Although not intended for this purpose,
743    this facility could be used to match a pattern in a different locale from the
744    one in which it was compiled. Passing table pointers at run time is discussed
745    below in the section on matching a pattern.
746    </P>
747    <br><a name="SEC11" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br>
748  <P>  <P>
749  <b>int pcre_fullinfo(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>  <b>int pcre_fullinfo(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
750  <b>int <i>what</i>, void *<i>where</i>);</b>  <b>int <i>what</i>, void *<i>where</i>);</b>
# Line 542  the pattern was not studied. The third a Line 761  the pattern was not studied. The third a
761  information is required, and the fourth argument is a pointer to a variable  information is required, and the fourth argument is a pointer to a variable
762  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
763  the following negative numbers:  the following negative numbers:
 </P>  
 <P>  
764  <pre>  <pre>
765    PCRE_ERROR_NULL       the argument <i>code</i> was NULL    PCRE_ERROR_NULL       the argument <i>code</i> was NULL
766                          the argument <i>where</i> was NULL                          the argument <i>where</i> was NULL
767    PCRE_ERROR_BADMAGIC   the "magic number" was not found    PCRE_ERROR_BADMAGIC   the "magic number" was not found
768    PCRE_ERROR_BADOPTION  the value of <i>what</i> was invalid    PCRE_ERROR_BADOPTION  the value of <i>what</i> was invalid
769  </PRE>  </pre>
770  </P>  The "magic number" is placed at the start of each compiled pattern as an simple
771  <P>  check against passing an arbitrary memory pointer. Here is a typical call of
772  Here is a typical call of <b>pcre_fullinfo()</b>, to obtain the length of the  <b>pcre_fullinfo()</b>, to obtain the length of the compiled pattern:
 compiled pattern:  
 </P>  
 <P>  
773  <pre>  <pre>
774    int rc;    int rc;
775    unsigned long int length;    size_t length;
776    rc = pcre_fullinfo(    rc = pcre_fullinfo(
777      re,               /* result of pcre_compile() */      re,               /* result of pcre_compile() */
778      pe,               /* result of pcre_study(), or NULL */      pe,               /* result of pcre_study(), or NULL */
779      PCRE_INFO_SIZE,   /* what is required */      PCRE_INFO_SIZE,   /* what is required */
780      &length);         /* where to put the data */      &length);         /* where to put the data */
781  </PRE>  </pre>
 </P>  
 <P>  
782  The possible values for the third argument are defined in <b>pcre.h</b>, and are  The possible values for the third argument are defined in <b>pcre.h</b>, and are
783  as follows:  as follows:
 </P>  
 <P>  
784  <pre>  <pre>
785    PCRE_INFO_BACKREFMAX    PCRE_INFO_BACKREFMAX
786  </PRE>  </pre>
 </P>  
 <P>  
787  Return the number of the highest back reference in the pattern. The fourth  Return the number of the highest back reference in the pattern. The fourth
788  argument should point to an <b>int</b> variable. Zero is returned if there are  argument should point to an <b>int</b> variable. Zero is returned if there are
789  no back references.  no back references.
 </P>  
 <P>  
790  <pre>  <pre>
791    PCRE_INFO_CAPTURECOUNT    PCRE_INFO_CAPTURECOUNT
792  </PRE>  </pre>
 </P>  
 <P>  
793  Return the number of capturing subpatterns in the pattern. The fourth argument  Return the number of capturing subpatterns in the pattern. The fourth argument
794  should point to an \fbint\fR variable.  should point to an <b>int</b> variable.
795  </P>  <pre>
796  <P>    PCRE_INFO_DEFAULT_TABLES
797    </pre>
798    Return a pointer to the internal default character tables within PCRE. The
799    fourth argument should point to an <b>unsigned char *</b> variable. This
800    information call is provided for internal use by the <b>pcre_study()</b>
801    function. External callers can cause PCRE to use its internal tables by passing
802    a NULL table pointer.
803  <pre>  <pre>
804    PCRE_INFO_FIRSTBYTE    PCRE_INFO_FIRSTBYTE
805  </PRE>  </pre>
 </P>  
 <P>  
806  Return information about the first byte of any matched string, for a  Return information about the first byte of any matched string, for a
807  non-anchored pattern. (This option used to be called PCRE_INFO_FIRSTCHAR; the  non-anchored pattern. The fourth argument should point to an <b>int</b>
808  old name is still recognized for backwards compatibility.)  variable. (This option used to be called PCRE_INFO_FIRSTCHAR; the old name is
809  </P>  still recognized for backwards compatibility.)
 <P>  
 If there is a fixed first byte, e.g. from a pattern such as (cat|cow|coyote),  
 it is returned in the integer pointed to by <i>where</i>. Otherwise, if either  
810  </P>  </P>
811  <P>  <P>
812    If there is a fixed first byte, for example, from a pattern such as
813    (cat|cow|coyote). Otherwise, if either
814    <br>
815    <br>
816  (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
817  starts with "^", or  starts with "^", or
818  </P>  <br>
819  <P>  <br>
820  (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set  (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set
821  (if it were set, the pattern would be anchored),  (if it were set, the pattern would be anchored),
822  </P>  <br>
823  <P>  <br>
824  -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
825  subject string or after any newline within the string. Otherwise -2 is  subject string or after any newline within the string. Otherwise -2 is
826  returned. For anchored patterns, -2 is returned.  returned. For anchored patterns, -2 is returned.
 </P>  
 <P>  
827  <pre>  <pre>
828    PCRE_INFO_FIRSTTABLE    PCRE_INFO_FIRSTTABLE
829  </PRE>  </pre>
 </P>  
 <P>  
830  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
831  table indicating a fixed set of bytes for the first byte in any matching  table indicating a fixed set of bytes for the first byte in any matching
832  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
833  fourth argument should point to an <b>unsigned char *</b> variable.  fourth argument should point to an <b>unsigned char *</b> variable.
 </P>  
 <P>  
834  <pre>  <pre>
835    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
836  </PRE>  </pre>
 </P>  
 <P>  
837  Return the value of the rightmost literal byte that must exist in any matched  Return the value of the rightmost literal byte that must exist in any matched
838  string, other than at its start, if such a byte has been recorded. The fourth  string, other than at its start, if such a byte has been recorded. The fourth
839  argument should point to an <b>int</b> variable. If there is no such byte, -1 is  argument should point to an <b>int</b> variable. If there is no such byte, -1 is
# Line 640  returned. For anchored patterns, a last Line 841  returned. For anchored patterns, a last
841  follows something of variable length. For example, for the pattern  follows something of variable length. For example, for the pattern
842  /^a\d+z\d+/ the returned value is "z", but for /^a\dz\d/ the returned value  /^a\d+z\d+/ the returned value is "z", but for /^a\dz\d/ the returned value
843  is -1.  is -1.
 </P>  
 <P>  
844  <pre>  <pre>
845    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
846    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
847    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
848  </PRE>  </pre>
 </P>  
 <P>  
849  PCRE supports the use of named as well as numbered capturing parentheses. The  PCRE supports the use of named as well as numbered capturing parentheses. The
850  names are just an additional way of identifying the parentheses, which still  names are just an additional way of identifying the parentheses, which still
851  acquire a number. A caller that wants to extract data from a named subpattern  acquire numbers. Several convenience functions such as
852  must convert the name to a number in order to access the correct pointers in  <b>pcre_get_named_substring()</b> are provided for extracting captured
853  the output vector (described with <b>pcre_exec()</b> below). In order to do  substrings by name. It is also possible to extract the data directly, by first
854  this, it must first use these three values to obtain the name-to-number mapping  converting the name to a number in order to access the correct pointers in the
855  table for the pattern.  output vector (described with <b>pcre_exec()</b> below). To do the conversion,
856    you need to use the name-to-number map, which is described by these three
857    values.
858  </P>  </P>
859  <P>  <P>
860  The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT gives  The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT gives
# Line 665  length of the longest name. PCRE_INFO_NA Line 864  length of the longest name. PCRE_INFO_NA
864  entry of the table (a pointer to <b>char</b>). The first two bytes of each entry  entry of the table (a pointer to <b>char</b>). The first two bytes of each entry
865  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
866  rest of the entry is the corresponding name, zero terminated. The names are in  rest of the entry is the corresponding name, zero terminated. The names are in
867  alphabetical order. For example, consider the following pattern (assume  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of
868    their parentheses numbers. For example, consider the following pattern (assume
869  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  PCRE_EXTENDED is set, so white space - including newlines - is ignored):
 </P>  
 <P>  
870  <pre>  <pre>
871    (?P&#60;date&#62; (?P&#60;year&#62;(\d\d)?\d\d) -    (?P&#60;date&#62; (?P&#60;year&#62;(\d\d)?\d\d) - (?P&#60;month&#62;\d\d) - (?P&#60;day&#62;\d\d) )
872    (?P&#60;month&#62;\d\d) - (?P&#60;day&#62;\d\d) )  </pre>
 </PRE>  
 </P>  
 <P>  
873  There are four named subpatterns, so the table has four entries, and each entry  There are four named subpatterns, so the table has four entries, and each entry
874  in the table is eight bytes long. The table is as follows, with non-printing  in the table is eight bytes long. The table is as follows, with non-printing
875  bytes shows in hex, and undefined bytes shown as ??:  bytes shows in hexadecimal, and undefined bytes shown as ??:
 </P>  
 <P>  
876  <pre>  <pre>
877    00 01 d  a  t  e  00 ??    00 01 d  a  t  e  00 ??
878    00 05 d  a  y  00 ?? ??    00 05 d  a  y  00 ?? ??
879    00 04 m  o  n  t  h  00    00 04 m  o  n  t  h  00
880    00 02 y  e  a  r  00 ??    00 02 y  e  a  r  00 ??
881  </PRE>  </pre>
882  </P>  When writing code to extract data from named subpatterns using the
883  <P>  name-to-number map, remember that the length of the entries is likely to be
884  When writing code to extract data from named subpatterns, remember that the  different for each compiled pattern.
 length of each entry may be different for each compiled pattern.  
 </P>  
 <P>  
885  <pre>  <pre>
886    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
887  </PRE>  </pre>
 </P>  
 <P>  
888  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
889  argument should point to an <b>unsigned long int</b> variable. These option bits  argument should point to an <b>unsigned long int</b> variable. These option bits
890  are those specified in the call to <b>pcre_compile()</b>, modified by any  are those specified in the call to <b>pcre_compile()</b>, modified by any
# Line 705  top-level option settings within the pat Line 893  top-level option settings within the pat
893  <P>  <P>
894  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
895  alternatives begin with one of the following:  alternatives begin with one of the following:
 </P>  
 <P>  
896  <pre>  <pre>
897    ^     unless PCRE_MULTILINE is set    ^     unless PCRE_MULTILINE is set
898    \A    always    \A    always
899    \G    always    \G    always
900    .*    if PCRE_DOTALL is set and there are no back    .*    if PCRE_DOTALL is set and there are no back references to the subpattern in which .* appears
901            references to the subpattern in which .* appears  </pre>
 </PRE>  
 </P>  
 <P>  
902  For such patterns, the PCRE_ANCHORED bit is set in the options returned by  For such patterns, the PCRE_ANCHORED bit is set in the options returned by
903  <b>pcre_fullinfo()</b>.  <b>pcre_fullinfo()</b>.
 </P>  
 <P>  
904  <pre>  <pre>
905    PCRE_INFO_SIZE    PCRE_INFO_SIZE
906  </PRE>  </pre>
 </P>  
 <P>  
907  Return the size of the compiled pattern, that is, the value that was passed as  Return the size of the compiled pattern, that is, the value that was passed as
908  the argument to <b>pcre_malloc()</b> when PCRE was getting memory in which to  the argument to <b>pcre_malloc()</b> when PCRE was getting memory in which to
909  place the compiled data. The fourth argument should point to a <b>size_t</b>  place the compiled data. The fourth argument should point to a <b>size_t</b>
910  variable.  variable.
 </P>  
 <P>  
911  <pre>  <pre>
912    PCRE_INFO_STUDYSIZE    PCRE_INFO_STUDYSIZE
913  </PRE>  </pre>
914  </P>  Return the size of the data block pointed to by the <i>study_data</i> field in
 <P>  
 Returns the size of the data block pointed to by the <i>study_data</i> field in  
915  a <b>pcre_extra</b> block. That is, it is the value that was passed to  a <b>pcre_extra</b> block. That is, it is the value that was passed to
916  <b>pcre_malloc()</b> when PCRE was getting memory into which to place the data  <b>pcre_malloc()</b> when PCRE was getting memory into which to place the data
917  created by <b>pcre_study()</b>. The fourth argument should point to a  created by <b>pcre_study()</b>. The fourth argument should point to a
918  <b>size_t</b> variable.  <b>size_t</b> variable.
919  </P>  </P>
920  <br><a name="SEC9" href="#TOC1">OBSOLETE INFO FUNCTION</a><br>  <br><a name="SEC12" href="#TOC1">OBSOLETE INFO FUNCTION</a><br>
921  <P>  <P>
922  <b>int pcre_info(const pcre *<i>code</i>, int *<i>optptr</i>, int</b>  <b>int pcre_info(const pcre *<i>code</i>, int *<i>optptr</i>, int</b>
923  <b>*<i>firstcharptr</i>);</b>  <b>*<i>firstcharptr</i>);</b>
# Line 753  restrictive to return all the available Line 928  restrictive to return all the available
928  programs should use <b>pcre_fullinfo()</b> instead. The yield of  programs should use <b>pcre_fullinfo()</b> instead. The yield of
929  <b>pcre_info()</b> is the number of capturing subpatterns, or one of the  <b>pcre_info()</b> is the number of capturing subpatterns, or one of the
930  following negative numbers:  following negative numbers:
 </P>  
 <P>  
931  <pre>  <pre>
932    PCRE_ERROR_NULL       the argument <i>code</i> was NULL    PCRE_ERROR_NULL       the argument <i>code</i> was NULL
933    PCRE_ERROR_BADMAGIC   the "magic number" was not found    PCRE_ERROR_BADMAGIC   the "magic number" was not found
934  </PRE>  </pre>
 </P>  
 <P>  
935  If the <i>optptr</i> argument is not NULL, a copy of the options with which the  If the <i>optptr</i> argument is not NULL, a copy of the options with which the
936  pattern was compiled is placed in the integer it points to (see  pattern was compiled is placed in the integer it points to (see
937  PCRE_INFO_OPTIONS above).  PCRE_INFO_OPTIONS above).
# Line 770  If the pattern is not anchored and the < Line 941  If the pattern is not anchored and the <
941  it is used to pass back information about the first character of any matched  it is used to pass back information about the first character of any matched
942  string (see PCRE_INFO_FIRSTBYTE above).  string (see PCRE_INFO_FIRSTBYTE above).
943  </P>  </P>
944  <br><a name="SEC10" href="#TOC1">MATCHING A PATTERN</a><br>  <br><a name="SEC13" href="#TOC1">REFERENCE COUNTS</a><br>
945    <P>
946    <b>int pcre_refcount(pcre *<i>code</i>, int <i>adjust</i>);</b>
947    </P>
948    <P>
949    The <b>pcre_refcount()</b> function is used to maintain a reference count in the
950    data block that contains a compiled pattern. It is provided for the benefit of
951    applications that operate in an object-oriented manner, where different parts
952    of the application may be using the same compiled pattern, but you want to free
953    the block when they are all done.
954    </P>
955    <P>
956    When a pattern is compiled, the reference count field is initialized to zero.
957    It is changed only by calling this function, whose action is to add the
958    <i>adjust</i> value (which may be positive or negative) to it. The yield of the
959    function is the new value. However, the value of the count is constrained to
960    lie between 0 and 65535, inclusive. If the new value is outside these limits,
961    it is forced to the appropriate limit value.
962    </P>
963    <P>
964    Except when it is zero, the reference count is not correctly preserved if a
965    pattern is compiled on one host and then transferred to a host whose byte-order
966    is different. (This seems a highly unlikely scenario.)
967    </P>
968    <br><a name="SEC14" href="#TOC1">MATCHING A PATTERN: THE TRADITIONAL FUNCTION</a><br>
969  <P>  <P>
970  <b>int pcre_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>  <b>int pcre_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
971  <b>const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>  <b>const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
# Line 778  string (see PCRE_INFO_FIRSTBYTE above). Line 973  string (see PCRE_INFO_FIRSTBYTE above).
973  </P>  </P>
974  <P>  <P>
975  The function <b>pcre_exec()</b> is called to match a subject string against a  The function <b>pcre_exec()</b> is called to match a subject string against a
976  pre-compiled pattern, which is passed in the <i>code</i> argument. If the  compiled pattern, which is passed in the <i>code</i> argument. If the
977  pattern has been studied, the result of the study should be passed in the  pattern has been studied, the result of the study should be passed in the
978  <i>extra</i> argument.  <i>extra</i> argument. This function is the main matching facility of the
979    library, and it operates in a Perl-like manner. For specialist use there is
980    also an alternative matching function, which is described
981    <a href="#dfamatch">below</a>
982    in the section about the <b>pcre_dfa_exec()</b> function.
983  </P>  </P>
984  <P>  <P>
985  Here is an example of a simple call to <b>pcre_exec()</b>:  In most applications, the pattern will have been compiled (and optionally
986    studied) in the same process that calls <b>pcre_exec()</b>. However, it is
987    possible to save compiled patterns and study data, and then use them later
988    in different processes, possibly even on different hosts. For a discussion
989    about this, see the
990    <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
991    documentation.
992  </P>  </P>
993  <P>  <P>
994    Here is an example of a simple call to <b>pcre_exec()</b>:
995  <pre>  <pre>
996    int rc;    int rc;
997    int ovector[30];    int ovector[30];
# Line 796  Here is an example of a simple call to < Line 1002  Here is an example of a simple call to <
1002      11,             /* the length of the subject string */      11,             /* the length of the subject string */
1003      0,              /* start at offset 0 in the subject */      0,              /* start at offset 0 in the subject */
1004      0,              /* default options */      0,              /* default options */
1005      ovector,        /* vector for substring information */      ovector,        /* vector of integers for substring information */
1006      30);            /* number of elements in the vector */      30);            /* number of elements (NOT size in bytes) */
1007  </PRE>  <a name="extradata"></a></PRE>
1008  </P>  </P>
1009    <br><b>
1010    Extra data for <b>pcre_exec()</b>
1011    </b><br>
1012  <P>  <P>
1013  If the <i>extra</i> argument is not NULL, it must point to a <b>pcre_extra</b>  If the <i>extra</i> argument is not NULL, it must point to a <b>pcre_extra</b>
1014  data block. The <b>pcre_study()</b> function returns such a block (when it  data block. The <b>pcre_study()</b> function returns such a block (when it
1015  doesn't return NULL), but you can also create one for yourself, and pass  doesn't return NULL), but you can also create one for yourself, and pass
1016  additional information in it. The fields in the block are as follows:  additional information in it. The <b>pcre_extra</b> block contains the following
1017  </P>  fields (not necessarily in this order):
 <P>  
1018  <pre>  <pre>
1019    unsigned long int <i>flags</i>;    unsigned long int <i>flags</i>;
1020    void *<i>study_data</i>;    void *<i>study_data</i>;
1021    unsigned long int <i>match_limit</i>;    unsigned long int <i>match_limit</i>;
1022      unsigned long int <i>match_limit_recursion</i>;
1023    void *<i>callout_data</i>;    void *<i>callout_data</i>;
1024  </PRE>    const unsigned char *<i>tables</i>;
1025  </P>  </pre>
 <P>  
1026  The <i>flags</i> field is a bitmap that specifies which of the other fields  The <i>flags</i> field is a bitmap that specifies which of the other fields
1027  are set. The flag bits are:  are set. The flag bits are:
 </P>  
 <P>  
1028  <pre>  <pre>
1029    PCRE_EXTRA_STUDY_DATA    PCRE_EXTRA_STUDY_DATA
1030    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1031      PCRE_EXTRA_MATCH_LIMIT_RECURSION
1032    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1033  </PRE>    PCRE_EXTRA_TABLES
1034  </P>  </pre>
 <P>  
1035  Other flag bits should be set to zero. The <i>study_data</i> field is set in the  Other flag bits should be set to zero. The <i>study_data</i> field is set in the
1036  <b>pcre_extra</b> block that is returned by <b>pcre_study()</b>, together with  <b>pcre_extra</b> block that is returned by <b>pcre_study()</b>, together with
1037  the appropriate flag bit. You should not set this yourself, but you can add to  the appropriate flag bit. You should not set this yourself, but you may add to
1038  the block by setting the other fields.  the block by setting the other fields and their corresponding flag bits.
1039  </P>  </P>
1040  <P>  <P>
1041  The <i>match_limit</i> field provides a means of preventing PCRE from using up a  The <i>match_limit</i> field provides a means of preventing PCRE from using up a
1042  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,
1043  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
1044  classic example is the use of nested unlimited repeats. Internally, PCRE uses a  classic example is the use of nested unlimited repeats.
 function called <b>match()</b> which it calls repeatedly (sometimes  
 recursively). The limit is imposed on the number of times this function is  
 called during a match, which has the effect of limiting the amount of recursion  
 and backtracking that can take place. For patterns that are not anchored, the  
 count starts from zero for each position in the subject string.  
1045  </P>  </P>
1046  <P>  <P>
1047  The default limit for the library can be set when PCRE is built; the default  Internally, PCRE uses a function called <b>match()</b> which it calls repeatedly
1048  default is 10 million, which handles all but the most extreme cases. You can  (sometimes recursively). The limit set by <i>match_limit</i> is imposed on the
1049  reduce the default by suppling <b>pcre_exec()</b> with a \fRpcre_extra\fR block  number of times this function is called during a match, which has the effect of
1050  in which <i>match_limit</i> is set to a smaller value, and  limiting the amount of backtracking that can take place. For patterns that are
1051  PCRE_EXTRA_MATCH_LIMIT is set in the <i>flags</i> field. If the limit is  not anchored, the count restarts from zero for each position in the subject
1052  exceeded, <b>pcre_exec()</b> returns PCRE_ERROR_MATCHLIMIT.  string.
1053  </P>  </P>
1054  <P>  <P>
1055  The <i>pcre_callout</i> field is used in conjunction with the "callout" feature,  The default value for the limit can be set when PCRE is built; the default
1056  which is described in the <b>pcrecallout</b> documentation.  default is 10 million, which handles all but the most extreme cases. You can
1057  </P>  override the default by suppling <b>pcre_exec()</b> with a <b>pcre_extra</b>
1058  <P>  block in which <i>match_limit</i> is set, and PCRE_EXTRA_MATCH_LIMIT is set in
1059  The PCRE_ANCHORED option can be passed in the <i>options</i> argument, whose  the <i>flags</i> field. If the limit is exceeded, <b>pcre_exec()</b> returns
1060  unused bits must be zero. This limits <b>pcre_exec()</b> to matching at the  PCRE_ERROR_MATCHLIMIT.
1061  first matching position. However, if a pattern was compiled with PCRE_ANCHORED,  </P>
1062  or turned out to be anchored by virtue of its contents, it cannot be made  <P>
1063  unachored at matching time.  The <i>match_limit_recursion</i> field is similar to <i>match_limit</i>, but
1064    instead of limiting the total number of times that <b>match()</b> is called, it
1065    limits the depth of recursion. The recursion depth is a smaller number than the
1066    total number of calls, because not all calls to <b>match()</b> are recursive.
1067    This limit is of use only if it is set smaller than <i>match_limit</i>.
1068    </P>
1069    <P>
1070    Limiting the recursion depth limits the amount of stack that can be used, or,
1071    when PCRE has been compiled to use memory on the heap instead of the stack, the
1072    amount of heap memory that can be used.
1073    </P>
1074    <P>
1075    The default value for <i>match_limit_recursion</i> can be set when PCRE is
1076    built; the default default is the same value as the default for
1077    <i>match_limit</i>. You can override the default by suppling <b>pcre_exec()</b>
1078    with a <b>pcre_extra</b> block in which <i>match_limit_recursion</i> is set, and
1079    PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the <i>flags</i> field. If the limit
1080    is exceeded, <b>pcre_exec()</b> returns PCRE_ERROR_RECURSIONLIMIT.
1081  </P>  </P>
1082  <P>  <P>
1083  There are also three further options that can be set only at matching time:  The <i>pcre_callout</i> field is used in conjunction with the "callout" feature,
1084    which is described in the
1085    <a href="pcrecallout.html"><b>pcrecallout</b></a>
1086    documentation.
1087  </P>  </P>
1088  <P>  <P>
1089    The <i>tables</i> field is used to pass a character tables pointer to
1090    <b>pcre_exec()</b>; this overrides the value that is stored with the compiled
1091    pattern. A non-NULL value is stored with the compiled pattern only if custom
1092    tables were supplied to <b>pcre_compile()</b> via its <i>tableptr</i> argument.
1093    If NULL is passed to <b>pcre_exec()</b> using this mechanism, it forces PCRE's
1094    internal tables to be used. This facility is helpful when re-using patterns
1095    that have been saved after compiling with an external set of tables, because
1096    the external tables might be at a different address when <b>pcre_exec()</b> is
1097    called. See the
1098    <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
1099    documentation for a discussion of saving compiled patterns for later use.
1100    </P>
1101    <br><b>
1102    Option bits for <b>pcre_exec()</b>
1103    </b><br>
1104    <P>
1105    The unused bits of the <i>options</i> argument for <b>pcre_exec()</b> must be
1106    zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_<i>xxx</i>,
1107    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.
1108    <pre>
1109      PCRE_ANCHORED
1110    </pre>
1111    The PCRE_ANCHORED option limits <b>pcre_exec()</b> to matching at the first
1112    matching position. If a pattern was compiled with PCRE_ANCHORED, or turned out
1113    to be anchored by virtue of its contents, it cannot be made unachored at
1114    matching time.
1115    <pre>
1116      PCRE_NEWLINE_CR
1117      PCRE_NEWLINE_LF
1118      PCRE_NEWLINE_CRLF
1119    </pre>
1120    These options override the newline definition that was chosen or defaulted when
1121    the pattern was compiled. For details, see the description <b>pcre_compile()</b>
1122    above. During matching, the newline choice affects the behaviour of the dot,
1123    circumflex, and dollar metacharacters.
1124  <pre>  <pre>
1125    PCRE_NOTBOL    PCRE_NOTBOL
1126  </PRE>  </pre>
1127  </P>  This option specifies that first character of the subject string is not the
1128  <P>  beginning of a line, so the circumflex metacharacter should not match before
1129  The first character of the string is not the beginning of a line, so the  it. Setting this without PCRE_MULTILINE (at compile time) causes circumflex
1130  circumflex metacharacter should not match before it. Setting this without  never to match. This option affects only the behaviour of the circumflex
1131  PCRE_MULTILINE (at compile time) causes circumflex never to match.  metacharacter. It does not affect \A.
 </P>  
 <P>  
1132  <pre>  <pre>
1133    PCRE_NOTEOL    PCRE_NOTEOL
1134  </PRE>  </pre>
1135  </P>  This option specifies that the end of the subject string is not the end of a
1136  <P>  line, so the dollar metacharacter should not match it nor (except in multiline
1137  The end of the string is not the end of a line, so the dollar metacharacter  mode) a newline immediately before it. Setting this without PCRE_MULTILINE (at
1138  should not match it nor (except in multiline mode) a newline immediately before  compile time) causes dollar never to match. This option affects only the
1139  it. Setting this without PCRE_MULTILINE (at compile time) causes dollar never  behaviour of the dollar metacharacter. It does not affect \Z or \z.
 to match.  
 </P>  
 <P>  
1140  <pre>  <pre>
1141    PCRE_NOTEMPTY    PCRE_NOTEMPTY
1142  </PRE>  </pre>
 </P>  
 <P>  
1143  An empty string is not considered to be a valid match if this option is set. If  An empty string is not considered to be a valid match if this option is set. If
1144  there are alternatives in the pattern, they are tried. If all the alternatives  there are alternatives in the pattern, they are tried. If all the alternatives
1145  match the empty string, the entire match fails. For example, if the pattern  match the empty string, the entire match fails. For example, if the pattern
 </P>  
 <P>  
1146  <pre>  <pre>
1147    a?b?    a?b?
1148  </PRE>  </pre>
 </P>  
 <P>  
1149  is applied to a string not beginning with "a" or "b", it matches the empty  is applied to a string not beginning with "a" or "b", it matches the empty
1150  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
1151  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".
# Line 910  Perl has no direct equivalent of PCRE_NO Line 1155  Perl has no direct equivalent of PCRE_NO
1155  of a pattern match of the empty string within its <b>split()</b> function, and  of a pattern match of the empty string within its <b>split()</b> function, and
1156  when using the /g modifier. It is possible to emulate Perl's behaviour after  when using the /g modifier. It is possible to emulate Perl's behaviour after
1157  matching a null string by first trying the match again at the same offset with  matching a null string by first trying the match again at the same offset with
1158  PCRE_NOTEMPTY set, and then if that fails by advancing the starting offset (see  PCRE_NOTEMPTY and PCRE_ANCHORED, and then if that fails by advancing the
1159  below) and trying an ordinary match again.  starting offset (see below) and trying an ordinary match again. There is some
1160    code that demonstrates how to do this in the <i>pcredemo.c</i> sample program.
1161    <pre>
1162      PCRE_NO_UTF8_CHECK
1163    </pre>
1164    When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8
1165    string is automatically checked when <b>pcre_exec()</b> is subsequently called.
1166    The value of <i>startoffset</i> is also checked to ensure that it points to the
1167    start of a UTF-8 character. If an invalid UTF-8 sequence of bytes is found,
1168    <b>pcre_exec()</b> returns the error PCRE_ERROR_BADUTF8. If <i>startoffset</i>
1169    contains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.
1170    </P>
1171    <P>
1172    If you already know that your subject is valid, and you want to skip these
1173    checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when
1174    calling <b>pcre_exec()</b>. You might want to do this for the second and
1175    subsequent calls to <b>pcre_exec()</b> if you are making repeated calls to find
1176    all the matches in a single subject string. However, you should be sure that
1177    the value of <i>startoffset</i> points to the start of a UTF-8 character. When
1178    PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid UTF-8 string as a
1179    subject, or a value of <i>startoffset</i> that does not point to the start of a
1180    UTF-8 character, is undefined. Your program may crash.
1181    <pre>
1182      PCRE_PARTIAL
1183    </pre>
1184    This option turns on the partial matching feature. If the subject string fails
1185    to match the pattern, but at some point during the matching process the end of
1186    the subject was reached (that is, the subject partially matches the pattern and
1187    the failure to match occurred only because there were not enough subject
1188    characters), <b>pcre_exec()</b> returns PCRE_ERROR_PARTIAL instead of
1189    PCRE_ERROR_NOMATCH. When PCRE_PARTIAL is used, there are restrictions on what
1190    may appear in the pattern. These are discussed in the
1191    <a href="pcrepartial.html"><b>pcrepartial</b></a>
1192    documentation.
1193  </P>  </P>
1194    <br><b>
1195    The string to be matched by <b>pcre_exec()</b>
1196    </b><br>
1197  <P>  <P>
1198  The subject string is passed to <b>pcre_exec()</b> as a pointer in  The subject string is passed to <b>pcre_exec()</b> as a pointer in
1199  <i>subject</i>, a length in <i>length</i>, and a starting offset in  <i>subject</i>, a length in <i>length</i>, and a starting byte offset in
1200  <i>startoffset</i>. Unlike the pattern string, the subject may contain binary  <i>startoffset</i>. In UTF-8 mode, the byte offset must point to the start of a
1201  zero bytes. When the starting offset is zero, the search for a match starts at  UTF-8 character. Unlike the pattern string, the subject may contain binary zero
1202  the beginning of the subject, and this is by far the most common case.  bytes. When the starting offset is zero, the search for a match starts at the
1203  </P>  beginning of the subject, and this is by far the most common case.
 <P>  
 If the pattern was compiled with the PCRE_UTF8 option, the subject must be a  
 sequence of bytes that is a valid UTF-8 string. If an invalid UTF-8 string is  
 passed, PCRE's behaviour is not defined.  
1204  </P>  </P>
1205  <P>  <P>
1206  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
# Line 931  same subject by calling <b>pcre_exec()</ Line 1208  same subject by calling <b>pcre_exec()</
1208  Setting <i>startoffset</i> differs from just passing over a shortened string and  Setting <i>startoffset</i> differs from just passing over a shortened string and
1209  setting PCRE_NOTBOL in the case of a pattern that begins with any kind of  setting PCRE_NOTBOL in the case of a pattern that begins with any kind of
1210  lookbehind. For example, consider the pattern  lookbehind. For example, consider the pattern
 </P>  
 <P>  
1211  <pre>  <pre>
1212    \Biss\B    \Biss\B
1213  </PRE>  </pre>
 </P>  
 <P>  
1214  which finds occurrences of "iss" in the middle of words. (\B matches only if  which finds occurrences of "iss" in the middle of words. (\B matches only if
1215  the current position in the subject is not a word boundary.) When applied to  the current position in the subject is not a word boundary.) When applied to
1216  the string "Mississipi" the first call to <b>pcre_exec()</b> finds the first  the string "Mississipi" the first call to <b>pcre_exec()</b> finds the first
# Line 950  behind the starting point to discover th Line 1223  behind the starting point to discover th
1223  </P>  </P>
1224  <P>  <P>
1225  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
1226  attempt to match at the given offset is tried. This can only succeed if the  attempt to match at the given offset is made. This can only succeed if the
1227  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.
1228  </P>  </P>
1229    <br><b>
1230    How <b>pcre_exec()</b> returns captured substrings
1231    </b><br>
1232  <P>  <P>
1233  In general, a pattern matches a certain portion of the subject, and in  In general, a pattern matches a certain portion of the subject, and in
1234  addition, further substrings from the subject may be picked out by parts of the  addition, further substrings from the subject may be picked out by parts of the
# Line 964  kinds of parenthesized subpattern that d Line 1240  kinds of parenthesized subpattern that d
1240  <P>  <P>
1241  Captured substrings are returned to the caller via a vector of integer offsets  Captured substrings are returned to the caller via a vector of integer offsets
1242  whose address is passed in <i>ovector</i>. The number of elements in the vector  whose address is passed in <i>ovector</i>. The number of elements in the vector
1243  is passed in <i>ovecsize</i>. The first two-thirds of the vector is used to pass  is passed in <i>ovecsize</i>, which must be a non-negative number. <b>Note</b>:
1244  back captured substrings, each substring using a pair of integers. The  this argument is NOT the size of <i>ovector</i> in bytes.
 remaining third of the vector is used as workspace by <b>pcre_exec()</b> while  
 matching capturing subpatterns, and is not available for passing back  
 information. The length passed in <i>ovecsize</i> should always be a multiple of  
 three. If it is not, it is rounded down.  
1245  </P>  </P>
1246  <P>  <P>
1247  When a match has been successful, information about captured substrings is  The first two-thirds of the vector is used to pass back captured substrings,
1248  returned in pairs of integers, starting at the beginning of <i>ovector</i>, and  each substring using a pair of integers. The remaining third of the vector is
1249    used as workspace by <b>pcre_exec()</b> while matching capturing subpatterns,
1250    and is not available for passing back information. The length passed in
1251    <i>ovecsize</i> should always be a multiple of three. If it is not, it is
1252    rounded down.
1253    </P>
1254    <P>
1255    When a match is successful, information about captured substrings is returned
1256    in pairs of integers, starting at the beginning of <i>ovector</i>, and
1257  continuing up to two-thirds of its length at the most. The first element of a  continuing up to two-thirds of its length at the most. The first element of a
1258  pair is set to the offset of the first character in a substring, and the second  pair is set to the offset of the first character in a substring, and the second
1259  is set to the offset of the first character after the end of a substring. The  is set to the offset of the first character after the end of a substring. The
1260  first pair, <i>ovector[0]</i> and <i>ovector[1]</i>, identify the portion of the  first pair, <i>ovector[0]</i> and <i>ovector[1]</i>, identify the portion of the
1261  subject string matched by the entire pattern. The next pair is used for the  subject string matched by the entire pattern. The next pair is used for the
1262  first capturing subpattern, and so on. The value returned by <b>pcre_exec()</b>  first capturing subpattern, and so on. The value returned by <b>pcre_exec()</b>
1263  is the number of pairs that have been set. If there are no capturing  is one more than the highest numbered pair that has been set. For example, if
1264  subpatterns, the return value from a successful match is 1, indicating that  two substrings have been captured, the returned value is 3. If there are no
1265  just the first pair of offsets has been set.  capturing subpatterns, the return value from a successful match is 1,
1266  </P>  indicating that just the first pair of offsets has been set.
 <P>  
 Some convenience functions are provided for extracting the captured substrings  
 as separate strings. These are described in the following section.  
 </P>  
 <P>  
 It is possible for an capturing subpattern number <i>n+1</i> to match some  
 part of the subject when subpattern <i>n</i> has not been used at all. For  
 example, if the string "abc" is matched against the pattern (a|(z))(bc)  
 subpatterns 1 and 3 are matched, but 2 is not. When this happens, both offset  
 values corresponding to the unused subpattern are set to -1.  
1267  </P>  </P>
1268  <P>  <P>
1269  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
1270  string that it matched that gets returned.  string that it matched that is returned.
1271  </P>  </P>
1272  <P>  <P>
1273  If the vector is too small to hold all the captured substrings, it is used as  If the vector is too small to hold all the captured substring offsets, it is
1274  far as possible (up to two-thirds of its length), and the function returns a  used as far as possible (up to two-thirds of its length), and the function
1275  value of zero. In particular, if the substring offsets are not of interest,  returns a value of zero. In particular, if the substring offsets are not of
1276  <b>pcre_exec()</b> may be called with <i>ovector</i> passed as NULL and  interest, <b>pcre_exec()</b> may be called with <i>ovector</i> passed as NULL and
1277  <i>ovecsize</i> as zero. However, if the pattern contains back references and  <i>ovecsize</i> as zero. However, if the pattern contains back references and
1278  the <i>ovector</i> isn't big enough to remember the related substrings, PCRE has  the <i>ovector</i> is not big enough to remember the related substrings, PCRE
1279  to get additional memory for use during matching. Thus it is usually advisable  has to get additional memory for use during matching. Thus it is usually
1280  to supply an <i>ovector</i>.  advisable to supply an <i>ovector</i>.
1281  </P>  </P>
1282  <P>  <P>
1283  Note that <b>pcre_info()</b> can be used to find out how many capturing  The <b>pcre_info()</b> function can be used to find out how many capturing
1284  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1285  <i>ovector</i> that will allow for <i>n</i> captured substrings, in addition to  <i>ovector</i> that will allow for <i>n</i> captured substrings, in addition to
1286  the offsets of the substring matched by the whole pattern, is (<i>n</i>+1)*3.  the offsets of the substring matched by the whole pattern, is (<i>n</i>+1)*3.
1287  </P>  </P>
1288  <P>  <P>
1289  If <b>pcre_exec()</b> fails, it returns a negative number. The following are  It is possible for capturing subpattern number <i>n+1</i> to match some part of
1290  defined in the header file:  the subject when subpattern <i>n</i> has not been used at all. For example, if
1291    the string "abc" is matched against the pattern (a|(z))(bc) the return from the
1292    function is 4, and subpatterns 1 and 3 are matched, but 2 is not. When this
1293    happens, both values in the offset pairs corresponding to unused subpatterns
1294    are set to -1.
1295  </P>  </P>
1296  <P>  <P>
1297  <pre>  Offset values that correspond to unused subpatterns at the end of the
1298    PCRE_ERROR_NOMATCH        (-1)  expression are also set to -1. For example, if the string "abc" is matched
1299  </PRE>  against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
1300    return from the function is 2, because the highest used capturing subpattern
1301    number is 1. However, you can refer to the offsets for the second and third
1302    capturing subpatterns if you wish (assuming the vector is large enough, of
1303    course).
1304  </P>  </P>
1305  <P>  <P>
1306  The subject string did not match the pattern.  Some convenience functions are provided for extracting the captured substrings
1307  </P>  as separate strings. These are described below.
1308    <a name="errorlist"></a></P>
1309    <br><b>
1310    Error return values from <b>pcre_exec()</b>
1311    </b><br>
1312  <P>  <P>
1313    If <b>pcre_exec()</b> fails, it returns a negative number. The following are
1314    defined in the header file:
1315    <pre>
1316      PCRE_ERROR_NOMATCH        (-1)
1317    </pre>
1318    The subject string did not match the pattern.
1319  <pre>  <pre>
1320    PCRE_ERROR_NULL           (-2)    PCRE_ERROR_NULL           (-2)
1321  </PRE>  </pre>
 </P>  
 <P>  
1322  Either <i>code</i> or <i>subject</i> was passed as NULL, or <i>ovector</i> was  Either <i>code</i> or <i>subject</i> was passed as NULL, or <i>ovector</i> was
1323  NULL and <i>ovecsize</i> was not zero.  NULL and <i>ovecsize</i> was not zero.
 </P>  
 <P>  
1324  <pre>  <pre>
1325    PCRE_ERROR_BADOPTION      (-3)    PCRE_ERROR_BADOPTION      (-3)
1326  </PRE>  </pre>
 </P>  
 <P>  
1327  An unrecognized bit was set in the <i>options</i> argument.  An unrecognized bit was set in the <i>options</i> argument.
 </P>  
 <P>  
1328  <pre>  <pre>
1329    PCRE_ERROR_BADMAGIC       (-4)    PCRE_ERROR_BADMAGIC       (-4)
1330  </PRE>  </pre>
 </P>  
 <P>  
1331  PCRE stores a 4-byte "magic number" at the start of the compiled code, to catch  PCRE stores a 4-byte "magic number" at the start of the compiled code, to catch
1332  the case when it is passed a junk pointer. This is the error it gives when the  the case when it is passed a junk pointer and to detect when a pattern that was
1333  magic number isn't present.  compiled in an environment of one endianness is run in an environment with the
1334  </P>  other endianness. This is the error that PCRE gives when the magic number is
1335  <P>  not present.
1336  <pre>  <pre>
1337    PCRE_ERROR_UNKNOWN_NODE   (-5)    PCRE_ERROR_UNKNOWN_NODE   (-5)
1338  </PRE>  </pre>
 </P>  
 <P>  
1339  While running the pattern match, an unknown item was encountered in the  While running the pattern match, an unknown item was encountered in the
1340  compiled pattern. This error could be caused by a bug in PCRE or by overwriting  compiled pattern. This error could be caused by a bug in PCRE or by overwriting
1341  of the compiled pattern.  of the compiled pattern.
 </P>  
 <P>  
1342  <pre>  <pre>
1343    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1344  </PRE>  </pre>
 </P>  
 <P>  
1345  If a pattern contains back references, but the <i>ovector</i> that is passed to  If a pattern contains back references, but the <i>ovector</i> that is passed to
1346  <b>pcre_exec()</b> is not big enough to remember the referenced substrings, PCRE  <b>pcre_exec()</b> is not big enough to remember the referenced substrings, PCRE
1347  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
1348  call via <b>pcre_malloc()</b> fails, this error is given. The memory is freed at  call via <b>pcre_malloc()</b> fails, this error is given. The memory is
1349  the end of matching.  automatically freed at the end of matching.
 </P>  
 <P>  
1350  <pre>  <pre>
1351    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1352  </PRE>  </pre>
 </P>  
 <P>  
1353  This error is used by the <b>pcre_copy_substring()</b>,  This error is used by the <b>pcre_copy_substring()</b>,
1354  <b>pcre_get_substring()</b>, and <b>pcre_get_substring_list()</b> functions (see  <b>pcre_get_substring()</b>, and <b>pcre_get_substring_list()</b> functions (see
1355  below). It is never returned by <b>pcre_exec()</b>.  below). It is never returned by <b>pcre_exec()</b>.
 </P>  
 <P>  
1356  <pre>  <pre>
1357    PCRE_ERROR_MATCHLIMIT     (-8)    PCRE_ERROR_MATCHLIMIT     (-8)
1358  </PRE>  </pre>
1359  </P>  The backtracking limit, as specified by the <i>match_limit</i> field in a
1360  <P>  <b>pcre_extra</b> structure (or defaulted) was reached. See the description
1361  The recursion and backtracking limit, as specified by the <i>match_limit</i>  above.
1362    <pre>
1363      PCRE_ERROR_RECURSIONLIMIT (-21)
1364    </pre>
1365    The internal recursion limit, as specified by the <i>match_limit_recursion</i>
1366  field in a <b>pcre_extra</b> structure (or defaulted) was reached. See the  field in a <b>pcre_extra</b> structure (or defaulted) was reached. See the
1367  description above.  description above.
 </P>  
 <P>  
1368  <pre>  <pre>
1369    PCRE_ERROR_CALLOUT        (-9)    PCRE_ERROR_CALLOUT        (-9)
1370  </PRE>  </pre>
 </P>  
 <P>  
1371  This error is never generated by <b>pcre_exec()</b> itself. It is provided for  This error is never generated by <b>pcre_exec()</b> itself. It is provided for
1372  use by callout functions that want to yield a distinctive error code. See the  use by callout functions that want to yield a distinctive error code. See the
1373  <b>pcrecallout</b> documentation for details.  <a href="pcrecallout.html"><b>pcrecallout</b></a>
1374    documentation for details.
1375    <pre>
1376      PCRE_ERROR_BADUTF8        (-10)
1377    </pre>
1378    A string that contains an invalid UTF-8 byte sequence was passed as a subject.
1379    <pre>
1380      PCRE_ERROR_BADUTF8_OFFSET (-11)
1381    </pre>
1382    The UTF-8 byte sequence that was passed as a subject was valid, but the value
1383    of <i>startoffset</i> did not point to the beginning of a UTF-8 character.
1384    <pre>
1385      PCRE_ERROR_PARTIAL        (-12)
1386    </pre>
1387    The subject string did not match, but it did match partially. See the
1388    <a href="pcrepartial.html"><b>pcrepartial</b></a>
1389    documentation for details of partial matching.
1390    <pre>
1391      PCRE_ERROR_BADPARTIAL     (-13)
1392    </pre>
1393    The PCRE_PARTIAL option was used with a compiled pattern containing items that
1394    are not supported for partial matching. See the
1395    <a href="pcrepartial.html"><b>pcrepartial</b></a>
1396    documentation for details of partial matching.
1397    <pre>
1398      PCRE_ERROR_INTERNAL       (-14)
1399    </pre>
1400    An unexpected internal error has occurred. This error could be caused by a bug
1401    in PCRE or by overwriting of the compiled pattern.
1402    <pre>
1403      PCRE_ERROR_BADCOUNT       (-15)
1404    </pre>
1405    This error is given if the value of the <i>ovecsize</i> argument is negative.
1406  </P>  </P>
1407  <br><a name="SEC11" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>  <br><a name="SEC15" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>
1408  <P>  <P>
1409  <b>int pcre_copy_substring(const char *<i>subject</i>, int *<i>ovector</i>,</b>  <b>int pcre_copy_substring(const char *<i>subject</i>, int *<i>ovector</i>,</b>
1410  <b>int <i>stringcount</i>, int <i>stringnumber</i>, char *<i>buffer</i>,</b>  <b>int <i>stringcount</i>, int <i>stringnumber</i>, char *<i>buffer</i>,</b>
# Line 1128  Captured substrings can be accessed dire Line 1426  Captured substrings can be accessed dire
1426  <b>pcre_get_substring_list()</b> are provided for extracting captured substrings  <b>pcre_get_substring_list()</b> are provided for extracting captured substrings
1427  as new, separate, zero-terminated strings. These functions identify substrings  as new, separate, zero-terminated strings. These functions identify substrings
1428  by number. The next section describes functions for extracting named  by number. The next section describes functions for extracting named
1429  substrings. A substring that contains a binary zero is correctly extracted and  substrings.
1430  has a further zero added on the end, but the result is not, of course,  </P>
1431  a C string.  <P>
1432    A substring that contains a binary zero is correctly extracted and has a
1433    further zero added on the end, but the result is not, of course, a C string.
1434    However, you can process such a string by referring to the length that is
1435    returned by <b>pcre_copy_substring()</b> and <b>pcre_get_substring()</b>.
1436    Unfortunately, the interface to <b>pcre_get_substring_list()</b> is not adequate
1437    for handling strings containing binary zeros, because the end of the final
1438    string is not independently indicated.
1439  </P>  </P>
1440  <P>  <P>
1441  The first three arguments are the same for all three of these functions:  The first three arguments are the same for all three of these functions:
1442  <i>subject</i> is the subject string which has just been successfully matched,  <i>subject</i> is the subject string that has just been successfully matched,
1443  <i>ovector</i> is a pointer to the vector of integer offsets that was passed to  <i>ovector</i> is a pointer to the vector of integer offsets that was passed to
1444  <b>pcre_exec()</b>, and <i>stringcount</i> is the number of substrings that were  <b>pcre_exec()</b>, and <i>stringcount</i> is the number of substrings that were
1445  captured by the match, including the substring that matched the entire regular  captured by the match, including the substring that matched the entire regular
1446  expression. This is the value returned by <b>pcre_exec</b> if it is greater than  expression. This is the value returned by <b>pcre_exec()</b> if it is greater
1447  zero. If <b>pcre_exec()</b> returned zero, indicating that it ran out of space  than zero. If <b>pcre_exec()</b> returned zero, indicating that it ran out of
1448  in <i>ovector</i>, the value passed as <i>stringcount</i> should be the size of  space in <i>ovector</i>, the value passed as <i>stringcount</i> should be the
1449  the vector divided by three.  number of elements in the vector divided by three.
1450  </P>  </P>
1451  <P>  <P>
1452  The functions <b>pcre_copy_substring()</b> and <b>pcre_get_substring()</b>  The functions <b>pcre_copy_substring()</b> and <b>pcre_get_substring()</b>
1453  extract a single substring, whose number is given as <i>stringnumber</i>. A  extract a single substring, whose number is given as <i>stringnumber</i>. A
1454  value of zero extracts the substring that matched the entire pattern, while  value of zero extracts the substring that matched the entire pattern, whereas
1455  higher values extract the captured substrings. For <b>pcre_copy_substring()</b>,  higher values extract the captured substrings. For <b>pcre_copy_substring()</b>,
1456  the string is placed in <i>buffer</i>, whose length is given by  the string is placed in <i>buffer</i>, whose length is given by
1457  <i>buffersize</i>, while for <b>pcre_get_substring()</b> a new block of memory is  <i>buffersize</i>, while for <b>pcre_get_substring()</b> a new block of memory is
1458  obtained via <b>pcre_malloc</b>, and its address is returned via  obtained via <b>pcre_malloc</b>, and its address is returned via
1459  <i>stringptr</i>. The yield of the function is the length of the string, not  <i>stringptr</i>. The yield of the function is the length of the string, not
1460  including the terminating zero, or one of  including the terminating zero, or one of
 </P>  
 <P>  
1461  <pre>  <pre>
1462    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1463  </PRE>  </pre>
 </P>  
 <P>  
1464  The buffer was too small for <b>pcre_copy_substring()</b>, or the attempt to get  The buffer was too small for <b>pcre_copy_substring()</b>, or the attempt to get
1465  memory failed for <b>pcre_get_substring()</b>.  memory failed for <b>pcre_get_substring()</b>.
 </P>  
 <P>  
1466  <pre>  <pre>
1467    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1468  </PRE>  </pre>
 </P>  
 <P>  
1469  There is no substring whose number is <i>stringnumber</i>.  There is no substring whose number is <i>stringnumber</i>.
1470  </P>  </P>
1471  <P>  <P>
1472  The <b>pcre_get_substring_list()</b> function extracts all available substrings  The <b>pcre_get_substring_list()</b> function extracts all available substrings
1473  and builds a list of pointers to them. All this is done in a single block of  and builds a list of pointers to them. All this is done in a single block of
1474  memory which is obtained via <b>pcre_malloc</b>. The address of the memory block  memory that is obtained via <b>pcre_malloc</b>. The address of the memory block
1475  is returned via <i>listptr</i>, which is also the start of the list of string  is returned via <i>listptr</i>, which is also the start of the list of string
1476  pointers. The end of the list is marked by a NULL pointer. The yield of the  pointers. The end of the list is marked by a NULL pointer. The yield of the
1477  function is zero if all went well, or  function is zero if all went well, or
 </P>  
 <P>  
1478  <pre>  <pre>
1479    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1480  </PRE>  </pre>
 </P>  
 <P>  
1481  if the attempt to get the memory block failed.  if the attempt to get the memory block failed.
1482  </P>  </P>
1483  <P>  <P>
# Line 1202  a previous call of <b>pcre_get_substring Line 1495  a previous call of <b>pcre_get_substring
1495  <b>pcre_get_substring_list()</b>, respectively. They do nothing more than call  <b>pcre_get_substring_list()</b>, respectively. They do nothing more than call
1496  the function pointed to by <b>pcre_free</b>, which of course could be called  the function pointed to by <b>pcre_free</b>, which of course could be called
1497  directly from a C program. However, PCRE is used in some situations where it is  directly from a C program. However, PCRE is used in some situations where it is
1498  linked via a special interface to another programming language which cannot use  linked via a special interface to another programming language that cannot use
1499  <b>pcre_free</b> directly; it is for these cases that the functions are  <b>pcre_free</b> directly; it is for these cases that the functions are
1500  provided.  provided.
1501  </P>  </P>
1502  <br><a name="SEC12" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a><br>  <br><a name="SEC16" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a><br>
1503    <P>
1504    <b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b>
1505    <b>const char *<i>name</i>);</b>
1506    </P>
1507  <P>  <P>
1508  <b>int pcre_copy_named_substring(const pcre *<i>code</i>,</b>  <b>int pcre_copy_named_substring(const pcre *<i>code</i>,</b>
1509  <b>const char *<i>subject</i>, int *<i>ovector</i>,</b>  <b>const char *<i>subject</i>, int *<i>ovector</i>,</b>
# Line 1214  provided. Line 1511  provided.
1511  <b>char *<i>buffer</i>, int <i>buffersize</i>);</b>  <b>char *<i>buffer</i>, int <i>buffersize</i>);</b>
1512  </P>  </P>
1513  <P>  <P>
 <b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b>  
 <b>const char *<i>name</i>);</b>  
 </P>  
 <P>  
1514  <b>int pcre_get_named_substring(const pcre *<i>code</i>,</b>  <b>int pcre_get_named_substring(const pcre *<i>code</i>,</b>
1515  <b>const char *<i>subject</i>, int *<i>ovector</i>,</b>  <b>const char *<i>subject</i>, int *<i>ovector</i>,</b>
1516  <b>int <i>stringcount</i>, const char *<i>stringname</i>,</b>  <b>int <i>stringcount</i>, const char *<i>stringname</i>,</b>
1517  <b>const char **<i>stringptr</i>);</b>  <b>const char **<i>stringptr</i>);</b>
1518  </P>  </P>
1519  <P>  <P>
1520  To extract a substring by name, you first have to find associated number. This  To extract a substring by name, you first have to find associated number.
1521  can be done by calling <b>pcre_get_stringnumber()</b>. The first argument is the  For example, for this pattern
 compiled pattern, and the second is the name. For example, for this pattern  
 </P>  
 <P>  
1522  <pre>  <pre>
1523    ab(?&#60;xxx&#62;\d+)...    (a+)b(?P&#60;xxx&#62;\d+)...
1524  </PRE>  </pre>
1525  </P>  the number of the subpattern called "xxx" is 2. If the name is known to be
1526  <P>  unique (PCRE_DUPNAMES was not set), you can find the number from the name by
1527  the number of the subpattern called "xxx" is 1. Given the number, you can then  calling <b>pcre_get_stringnumber()</b>. The first argument is the compiled
1528  extract the substring directly, or use one of the functions described in the  pattern, and the second is the name. The yield of the function is the
1529  previous section. For convenience, there are also two functions that do the  subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if there is no subpattern of
1530  whole job.  that name.
1531  </P>  </P>
1532  <P>  <P>
1533  Most of the arguments of <i>pcre_copy_named_substring()</i> and  Given the number, you can extract the substring directly, or use one of the
1534  <i>pcre_get_named_substring()</i> are the same as those for the functions that  functions described in the previous section. For convenience, there are also
1535  extract by number, and so are not re-described here. There are just two  two functions that do the whole job.
1536  differences.  </P>
1537    <P>
1538    Most of the arguments of <b>pcre_copy_named_substring()</b> and
1539    <b>pcre_get_named_substring()</b> are the same as those for the similarly named
1540    functions that extract by number. As these are described in the previous
1541    section, they are not re-described here. There are just two differences:
1542  </P>  </P>
1543  <P>  <P>
1544  First, instead of a substring number, a substring name is given. Second, there  First, instead of a substring number, a substring name is given. Second, there
# Line 1256  These functions call <b>pcre_get_stringn Line 1551  These functions call <b>pcre_get_stringn
1551  then call <i>pcre_copy_substring()</i> or <i>pcre_get_substring()</i>, as  then call <i>pcre_copy_substring()</i> or <i>pcre_get_substring()</i>, as
1552  appropriate.  appropriate.
1553  </P>  </P>
1554    <br><a name="SEC17" href="#TOC1">DUPLICATE SUBPATTERN NAMES</a><br>
1555    <P>
1556    <b>int pcre_get_stringtable_entries(const pcre *<i>code</i>,</b>
1557    <b>const char *<i>name</i>, char **<i>first</i>, char **<i>last</i>);</b>
1558    </P>
1559    <P>
1560    When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
1561    are not required to be unique. Normally, patterns with duplicate names are such
1562    that in any one match, only one of the named subpatterns participates. An
1563    example is shown in the
1564    <a href="pcrepattern.html"><b>pcrepattern</b></a>
1565    documentation. When duplicates are present, <b>pcre_copy_named_substring()</b>
1566    and <b>pcre_get_named_substring()</b> return the first substring corresponding
1567    to the given name that is set. If none are set, an empty string is returned.
1568    The <b>pcre_get_stringnumber()</b> function returns one of the numbers that are
1569    associated with the name, but it is not defined which it is.
1570    <br>
1571    <br>
1572    If you want to get full details of all captured substrings for a given name,
1573    you must use the <b>pcre_get_stringtable_entries()</b> function. The first
1574    argument is the compiled pattern, and the second is the name. The third and
1575    fourth are pointers to variables which are updated by the function. After it
1576    has run, they point to the first and last entries in the name-to-number table
1577    for the given name. The function itself returns the length of each entry, or
1578    PCRE_ERROR_NOSUBSTRING if there are none. The format of the table is described
1579    above in the section entitled <i>Information about a pattern</i>. Given all the
1580    relevant entries for the name, you can extract each of their numbers, and hence
1581    the captured data, if any.
1582    </P>
1583    <br><a name="SEC18" href="#TOC1">FINDING ALL POSSIBLE MATCHES</a><br>
1584    <P>
1585    The traditional matching function uses a similar algorithm to Perl, which stops
1586    when it finds the first match, starting at a given point in the subject. If you
1587    want to find all possible matches, or the longest possible match, consider
1588    using the alternative matching function (see below) instead. If you cannot use
1589    the alternative function, but still need to find all possible matches, you
1590    can kludge it up by making use of the callout facility, which is described in
1591    the
1592    <a href="pcrecallout.html"><b>pcrecallout</b></a>
1593    documentation.
1594    </P>
1595    <P>
1596    What you have to do is to insert a callout right at the end of the pattern.
1597    When your callout function is called, extract and save the current matched
1598    substring. Then return 1, which forces <b>pcre_exec()</b> to backtrack and try
1599    other alternatives. Ultimately, when it runs out of matches, <b>pcre_exec()</b>
1600    will yield PCRE_ERROR_NOMATCH.
1601    <a name="dfamatch"></a></P>
1602    <br><a name="SEC19" href="#TOC1">MATCHING A PATTERN: THE ALTERNATIVE FUNCTION</a><br>
1603    <P>
1604    <b>int pcre_dfa_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
1605    <b>const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
1606    <b>int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b>
1607    <b>int *<i>workspace</i>, int <i>wscount</i>);</b>
1608    </P>
1609    <P>
1610    The function <b>pcre_dfa_exec()</b> is called to match a subject string against
1611    a compiled pattern, using a "DFA" matching algorithm. This has different
1612    characteristics to the normal algorithm, and is not compatible with Perl. Some
1613    of the features of PCRE patterns are not supported. Nevertheless, there are
1614    times when this kind of matching can be useful. For a discussion of the two
1615    matching algorithms, see the
1616    <a href="pcrematching.html"><b>pcrematching</b></a>
1617    documentation.
1618    </P>
1619    <P>
1620    The arguments for the <b>pcre_dfa_exec()</b> function are the same as for
1621    <b>pcre_exec()</b>, plus two extras. The <i>ovector</i> argument is used in a
1622    different way, and this is described below. The other common arguments are used
1623    in the same way as for <b>pcre_exec()</b>, so their description is not repeated
1624    here.
1625    </P>
1626    <P>
1627    The two additional arguments provide workspace for the function. The workspace
1628    vector should contain at least 20 elements. It is used for keeping track of
1629    multiple paths through the pattern tree. More workspace will be needed for
1630    patterns and subjects where there are a lot of potential matches.
1631    </P>
1632    <P>
1633    Here is an example of a simple call to <b>pcre_dfa_exec()</b>:
1634    <pre>
1635      int rc;
1636      int ovector[10];
1637      int wspace[20];
1638      rc = pcre_dfa_exec(
1639        re,             /* result of pcre_compile() */
1640        NULL,           /* we didn't study the pattern */
1641        "some string",  /* the subject string */
1642        11,             /* the length of the subject string */
1643        0,              /* start at offset 0 in the subject */
1644        0,              /* default options */
1645        ovector,        /* vector of integers for substring information */
1646        10,             /* number of elements (NOT size in bytes) */
1647        wspace,         /* working space vector */
1648        20);            /* number of elements (NOT size in bytes) */
1649    </PRE>
1650    </P>
1651    <br><b>
1652    Option bits for <b>pcre_dfa_exec()</b>
1653    </b><br>
1654    <P>
1655    The unused bits of the <i>options</i> argument for <b>pcre_dfa_exec()</b> must be
1656    zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_<i>xxx</i>,
1657    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,
1658    PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last three of these are
1659    the same as for <b>pcre_exec()</b>, so their description is not repeated here.
1660    <pre>
1661      PCRE_PARTIAL
1662    </pre>
1663    This has the same general effect as it does for <b>pcre_exec()</b>, but the
1664    details are slightly different. When PCRE_PARTIAL is set for
1665    <b>pcre_dfa_exec()</b>, the return code PCRE_ERROR_NOMATCH is converted into
1666    PCRE_ERROR_PARTIAL if the end of the subject is reached, there have been no
1667    complete matches, but there is still at least one matching possibility. The
1668    portion of the string that provided the partial match is set as the first
1669    matching string.
1670    <pre>
1671      PCRE_DFA_SHORTEST
1672    </pre>
1673    Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as
1674    soon as it has found one match. Because of the way the DFA algorithm works,
1675    this is necessarily the shortest possible match at the first possible matching
1676    point in the subject string.
1677    <pre>
1678      PCRE_DFA_RESTART
1679    </pre>
1680    When <b>pcre_dfa_exec()</b> is called with the PCRE_PARTIAL option, and returns
1681    a partial match, it is possible to call it again, with additional subject
1682    characters, and have it continue with the same match. The PCRE_DFA_RESTART
1683    option requests this action; when it is set, the <i>workspace</i> and
1684    <i>wscount</i> options must reference the same vector as before because data
1685    about the match so far is left in them after a partial match. There is more
1686    discussion of this facility in the
1687    <a href="pcrepartial.html"><b>pcrepartial</b></a>
1688    documentation.
1689    </P>
1690    <br><b>
1691    Successful returns from <b>pcre_dfa_exec()</b>
1692    </b><br>
1693    <P>
1694    When <b>pcre_dfa_exec()</b> succeeds, it may have matched more than one
1695    substring in the subject. Note, however, that all the matches from one run of
1696    the function start at the same point in the subject. The shorter matches are
1697    all initial substrings of the longer matches. For example, if the pattern
1698    <pre>
1699      &#60;.*&#62;
1700    </pre>
1701    is matched against the string
1702    <pre>
1703      This is &#60;something&#62; &#60;something else&#62; &#60;something further&#62; no more
1704    </pre>
1705    the three matched strings are
1706    <pre>
1707      &#60;something&#62;
1708      &#60;something&#62; &#60;something else&#62;
1709      &#60;something&#62; &#60;something else&#62; &#60;something further&#62;
1710    </pre>
1711    On success, the yield of the function is a number greater than zero, which is
1712    the number of matched substrings. The substrings themselves are returned in
1713    <i>ovector</i>. Each string uses two elements; the first is the offset to the
1714    start, and the second is the offset to the end. All the strings have the same
1715    start offset. (Space could have been saved by giving this only once, but it was
1716    decided to retain some compatibility with the way <b>pcre_exec()</b> returns
1717    data, even though the meaning of the strings is different.)
1718    </P>
1719    <P>
1720    The strings are returned in reverse order of length; that is, the longest
1721    matching string is given first. If there were too many matches to fit into
1722    <i>ovector</i>, the yield of the function is zero, and the vector is filled with
1723    the longest matches.
1724    </P>
1725    <br><b>
1726    Error returns from <b>pcre_dfa_exec()</b>
1727    </b><br>
1728    <P>
1729    The <b>pcre_dfa_exec()</b> function returns a negative number when it fails.
1730    Many of the errors are the same as for <b>pcre_exec()</b>, and these are
1731    described
1732    <a href="#errorlist">above.</a>
1733    There are in addition the following errors that are specific to
1734    <b>pcre_dfa_exec()</b>:
1735    <pre>
1736      PCRE_ERROR_DFA_UITEM      (-16)
1737    </pre>
1738    This return is given if <b>pcre_dfa_exec()</b> encounters an item in the pattern
1739    that it does not support, for instance, the use of \C or a back reference.
1740    <pre>
1741      PCRE_ERROR_DFA_UCOND      (-17)
1742    </pre>
1743    This return is given if <b>pcre_dfa_exec()</b> encounters a condition item in a
1744    pattern that uses a back reference for the condition. This is not supported.
1745    <pre>
1746      PCRE_ERROR_DFA_UMLIMIT    (-18)
1747    </pre>
1748    This return is given if <b>pcre_dfa_exec()</b> is called with an <i>extra</i>
1749    block that contains a setting of the <i>match_limit</i> field. This is not
1750    supported (it is meaningless).
1751    <pre>
1752      PCRE_ERROR_DFA_WSSIZE     (-19)
1753    </pre>
1754    This return is given if <b>pcre_dfa_exec()</b> runs out of space in the
1755    <i>workspace</i> vector.
1756    <pre>
1757      PCRE_ERROR_DFA_RECURSE    (-20)
1758    </pre>
1759    When a recursive subpattern is processed, the matching function calls itself
1760    recursively, using private vectors for <i>ovector</i> and <i>workspace</i>. This
1761    error is given if the output vector is not large enough. This should be
1762    extremely rare, as a vector of size 1000 is used.
1763    </P>
1764  <P>  <P>
1765  Last updated: 03 February 2003  Last updated: 08 June 2006
1766  <br>  <br>
1767  Copyright &copy; 1997-2003 University of Cambridge.  Copyright &copy; 1997-2006 University of Cambridge.
1768    <p>
1769    Return to the <a href="index.html">PCRE index page</a>.
1770    </p>

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