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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    <li><a name="TOC20" href="#SEC20">SEE ALSO</a>
36    <li><a name="TOC21" href="#SEC21">AUTHOR</a>
37    <li><a name="TOC22" href="#SEC22">REVISION</a>
38  </ul>  </ul>
39  <br><a name="SEC1" href="#TOC1">SYNOPSIS OF PCRE API</a><br>  <br><a name="SEC1" href="#TOC1">PCRE NATIVE API</a><br>
40  <P>  <P>
41  <b>#include &#60;pcre.h&#62;</b>  <b>#include &#60;pcre.h&#62;</b>
42  </P>  </P>
# Line 30  conversion went wrong.<br> Line 46  conversion went wrong.<br>
46  <b>const unsigned char *<i>tableptr</i>);</b>  <b>const unsigned char *<i>tableptr</i>);</b>
47  </P>  </P>
48  <P>  <P>
49    <b>pcre *pcre_compile2(const char *<i>pattern</i>, int <i>options</i>,</b>
50    <b>int *<i>errorcodeptr</i>,</b>
51    <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
52    <b>const unsigned char *<i>tableptr</i>);</b>
53    </P>
54    <P>
55  <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>
56  <b>const char **<i>errptr</i>);</b>  <b>const char **<i>errptr</i>);</b>
57  </P>  </P>
# Line 39  conversion went wrong.<br> Line 61  conversion went wrong.<br>
61  <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>
62  </P>  </P>
63  <P>  <P>
64    <b>int pcre_dfa_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
65    <b>const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
66    <b>int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b>
67    <b>int *<i>workspace</i>, int <i>wscount</i>);</b>
68    </P>
69    <P>
70  <b>int pcre_copy_named_substring(const pcre *<i>code</i>,</b>  <b>int pcre_copy_named_substring(const pcre *<i>code</i>,</b>
71  <b>const char *<i>subject</i>, int *<i>ovector</i>,</b>  <b>const char *<i>subject</i>, int *<i>ovector</i>,</b>
72  <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 88  conversion went wrong.<br>
88  <b>const char *<i>name</i>);</b>  <b>const char *<i>name</i>);</b>
89  </P>  </P>
90  <P>  <P>
91    <b>int pcre_get_stringtable_entries(const pcre *<i>code</i>,</b>
92    <b>const char *<i>name</i>, char **<i>first</i>, char **<i>last</i>);</b>
93    </P>
94    <P>
95  <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>
96  <b>int <i>stringcount</i>, int <i>stringnumber</i>,</b>  <b>int <i>stringcount</i>, int <i>stringnumber</i>,</b>
97  <b>const char **<i>stringptr</i>);</b>  <b>const char **<i>stringptr</i>);</b>
# Line 86  conversion went wrong.<br> Line 118  conversion went wrong.<br>
118  <b>*<i>firstcharptr</i>);</b>  <b>*<i>firstcharptr</i>);</b>
119  </P>  </P>
120  <P>  <P>
121    <b>int pcre_refcount(pcre *<i>code</i>, int <i>adjust</i>);</b>
122    </P>
123    <P>
124  <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>
125  </P>  </P>
126  <P>  <P>
# Line 98  conversion went wrong.<br> Line 133  conversion went wrong.<br>
133  <b>void (*pcre_free)(void *);</b>  <b>void (*pcre_free)(void *);</b>
134  </P>  </P>
135  <P>  <P>
136  <b>int (*pcre_callout)(pcre_callout_block *);</b>  <b>void *(*pcre_stack_malloc)(size_t);</b>
137  </P>  </P>
 <br><a name="SEC2" href="#TOC1">PCRE API</a><br>  
138  <P>  <P>
139  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.  
140  </P>  </P>
141  <P>  <P>
142  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.  
143  </P>  </P>
144    <br><a name="SEC2" href="#TOC1">PCRE API OVERVIEW</a><br>
145  <P>  <P>
146  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 are
147  are used for compiling and matching regular expressions. A sample program that  also some wrapper functions that correspond to the POSIX regular expression
148  demonstrates the simplest way of using them is given in the file  API. These are described in the
149  <i>pcredemo.c</i>. The <b>pcresample</b> documentation describes how to run it.  <a href="pcreposix.html"><b>pcreposix</b></a>
150    documentation. Both of these APIs define a set of C function calls. A C++
151    wrapper is distributed with PCRE. It is documented in the
152    <a href="pcrecpp.html"><b>pcrecpp</b></a>
153    page.
154  </P>  </P>
155  <P>  <P>
156  There are convenience functions for extracting captured substrings from a  The native API C function prototypes are defined in the header file
157  matched subject string. They are:  <b>pcre.h</b>, and on Unix systems the library itself is called <b>libpcre</b>.
158    It can normally be accessed by adding <b>-lpcre</b> to the command for linking
159    an application that uses PCRE. The header file defines the macros PCRE_MAJOR
160    and PCRE_MINOR to contain the major and minor release numbers for the library.
161    Applications can use these to include support for different releases of PCRE.
162    </P>
163    <P>
164    The functions <b>pcre_compile()</b>, <b>pcre_compile2()</b>, <b>pcre_study()</b>,
165    and <b>pcre_exec()</b> are used for compiling and matching regular expressions
166    in a Perl-compatible manner. A sample program that demonstrates the simplest
167    way of using them is provided in the file called <i>pcredemo.c</i> in the source
168    distribution. The
169    <a href="pcresample.html"><b>pcresample</b></a>
170    documentation describes how to run it.
171    </P>
172    <P>
173    A second matching function, <b>pcre_dfa_exec()</b>, which is not
174    Perl-compatible, is also provided. This uses a different algorithm for the
175    matching. The alternative algorithm finds all possible matches (at a given
176    point in the subject), and scans the subject just once. However, this algorithm
177    does not return captured substrings. A description of the two matching
178    algorithms and their advantages and disadvantages is given in the
179    <a href="pcrematching.html"><b>pcrematching</b></a>
180    documentation.
181  </P>  </P>
182  <P>  <P>
183    In addition to the main compiling and matching functions, there are convenience
184    functions for extracting captured substrings from a subject string that is
185    matched by <b>pcre_exec()</b>. They are:
186  <pre>  <pre>
187    <b>pcre_copy_substring()</b>    <b>pcre_copy_substring()</b>
188    <b>pcre_copy_named_substring()</b>    <b>pcre_copy_named_substring()</b>
189    <b>pcre_get_substring()</b>    <b>pcre_get_substring()</b>
190    <b>pcre_get_named_substring()</b>    <b>pcre_get_named_substring()</b>
191    <b>pcre_get_substring_list()</b>    <b>pcre_get_substring_list()</b>
192  </PRE>    <b>pcre_get_stringnumber()</b>
193  </P>    <b>pcre_get_stringtable_entries()</b>
194  <P>  </pre>
195  <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
196  provided, to free the memory used for extracted strings.  provided, to free the memory used for extracted strings.
197  </P>  </P>
198  <P>  <P>
199  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
200  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>,
201    or <b>pcre_dfa_exec()</b>. This is an optional facility that is provided for
202    specialist use. Most commonly, no special tables are passed, in which case
203    internal tables that are generated when PCRE is built are used.
204  </P>  </P>
205  <P>  <P>
206  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
207  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
208  some of the available information, but is retained for backwards compatibility.  some of the available information, but is retained for backwards compatibility.
209  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
210  version of PCRE and its date of release.  version of PCRE and its date of release.
211  </P>  </P>
212  <P>  <P>
213    The function <b>pcre_refcount()</b> maintains a reference count in a data block
214    containing a compiled pattern. This is provided for the benefit of
215    object-oriented applications.
216    </P>
217    <P>
218  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
219  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,
220  respectively. PCRE calls the memory management functions via these variables,  respectively. PCRE calls the memory management functions via these variables,
221  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
222  should be done before calling any PCRE functions.  should be done before calling any PCRE functions.
223  </P>  </P>
224  <P>  <P>
225    The global variables <b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> are also
226    indirections to memory management functions. These special functions are used
227    only when PCRE is compiled to use the heap for remembering data, instead of
228    recursive function calls, when running the <b>pcre_exec()</b> function. See the
229    <a href="pcrebuild.html"><b>pcrebuild</b></a>
230    documentation for details of how to do this. It is a non-standard way of
231    building PCRE, for use in environments that have limited stacks. Because of the
232    greater use of memory management, it runs more slowly. Separate functions are
233    provided so that special-purpose external code can be used for this case. When
234    used, these functions are always called in a stack-like manner (last obtained,
235    first freed), and always for memory blocks of the same size. There is a
236    discussion about PCRE's stack usage in the
237    <a href="pcrestack.html"><b>pcrestack</b></a>
238    documentation.
239    </P>
240    <P>
241  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
242  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
243  points during a matching operation. Details are given in the <b>pcrecallout</b>  points during a matching operation. Details are given in the
244    <a href="pcrecallout.html"><b>pcrecallout</b></a>
245  documentation.  documentation.
246    <a name="newlines"></a></P>
247    <br><a name="SEC3" href="#TOC1">NEWLINES</a><br>
248    <P>
249    PCRE supports five different conventions for indicating line breaks in
250    strings: a single CR (carriage return) character, a single LF (linefeed)
251    character, the two-character sequence CRLF, any of the three preceding, or any
252    Unicode newline sequence. The Unicode newline sequences are the three just
253    mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed,
254    U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
255    (paragraph separator, U+2029).
256    </P>
257    <P>
258    Each of the first three conventions is used by at least one operating system as
259    its standard newline sequence. When PCRE is built, a default can be specified.
260    The default default is LF, which is the Unix standard. When PCRE is run, the
261    default can be overridden, either when a pattern is compiled, or when it is
262    matched.
263    </P>
264    <P>
265    At compile time, the newline convention can be specified by the <i>options</i>
266    argument of <b>pcre_compile()</b>, or it can be specified by special text at the
267    start of the pattern itself; this overrides any other settings. See the
268    <a href="pcrepattern.html"><b>pcrepattern</b></a>
269    page for details of the special character sequences.
270    </P>
271    <P>
272    In the PCRE documentation the word "newline" is used to mean "the character or
273    pair of characters that indicate a line break". The choice of newline
274    convention affects the handling of the dot, circumflex, and dollar
275    metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
276    recognized line ending sequence, the match position advancement for a
277    non-anchored pattern. There is more detail about this in the
278    <a href="#execoptions">section on <b>pcre_exec()</b> options</a>
279    below.
280    </P>
281    <P>
282    The choice of newline convention does not affect the interpretation of
283    the \n or \r escape sequences, nor does it affect what \R matches, which is
284    controlled in a similar way, but by separate options.
285  </P>  </P>
286  <br><a name="SEC3" href="#TOC1">MULTITHREADING</a><br>  <br><a name="SEC4" href="#TOC1">MULTITHREADING</a><br>
287  <P>  <P>
288  The PCRE functions can be used in multi-threading applications, with the  The PCRE functions can be used in multi-threading applications, with the
289  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>,
290  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
291  are shared by all threads.  callout function pointed to by <b>pcre_callout</b>, are shared by all threads.
292  </P>  </P>
293  <P>  <P>
294  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
295  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.
296  </P>  </P>
297  <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>
298    <P>
299    The compiled form of a regular expression can be saved and re-used at a later
300    time, possibly by a different program, and even on a host other than the one on
301    which it was compiled. Details are given in the
302    <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
303    documentation. However, compiling a regular expression with one version of PCRE
304    for use with a different version is not guaranteed to work and may cause
305    crashes.
306    </P>
307    <br><a name="SEC6" href="#TOC1">CHECKING BUILD-TIME OPTIONS</a><br>
308  <P>  <P>
309  <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>
310  </P>  </P>
# Line 186  documentation has more details about the Line 318  documentation has more details about the
318  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
319  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
320  which the information is placed. The following information is available:  which the information is placed. The following information is available:
 </P>  
 <P>  
321  <pre>  <pre>
322    PCRE_CONFIG_UTF8    PCRE_CONFIG_UTF8
323  </PRE>  </pre>
 </P>  
 <P>  
324  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;
325  otherwise it is set to zero.  otherwise it is set to zero.
326  </P>  <pre>
327  <P>    PCRE_CONFIG_UNICODE_PROPERTIES
328    </pre>
329    The output is an integer that is set to one if support for Unicode character
330    properties is available; otherwise it is set to zero.
331  <pre>  <pre>
332    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
333  </PRE>  </pre>
334  </P>  The output is an integer whose value specifies the default character sequence
335  <P>  that is recognized as meaning "newline". The four values that are supported
336  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, 3338 for CRLF, -2 for ANYCRLF, and -1 for ANY. The
337  the newline character. It is either linefeed (10) or carriage return (13), and  default should normally be the standard sequence for your operating system.
338  should normally be the standard character for your operating system.  <pre>
339  </P>    PCRE_CONFIG_BSR
340  <P>  </pre>
341    The output is an integer whose value indicates what character sequences the \R
342    escape sequence matches by default. A value of 0 means that \R matches any
343    Unicode line ending sequence; a value of 1 means that \R matches only CR, LF,
344    or CRLF. The default can be overridden when a pattern is compiled or matched.
345  <pre>  <pre>
346    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
347  </PRE>  </pre>
 </P>  
 <P>  
348  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
349  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
350  allow larger regular expressions to be compiled, at the expense of slower  allow larger regular expressions to be compiled, at the expense of slower
351  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
352  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>  
353  <pre>  <pre>
354    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD    PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
355  </PRE>  </pre>
 </P>  
 <P>  
356  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
357  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
358  the <b>pcreposix</b> documentation.  the
359  </P>  <a href="pcreposix.html"><b>pcreposix</b></a>
360  <P>  documentation.
361  <pre>  <pre>
362    PCRE_CONFIG_MATCH_LIMIT    PCRE_CONFIG_MATCH_LIMIT
363  </PRE>  </pre>
 </P>  
 <P>  
364  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
365  internal matching function calls in a <b>pcre_exec()</b> execution. Further  internal matching function calls in a <b>pcre_exec()</b> execution. Further
366  details are given with <b>pcre_exec()</b> below.  details are given with <b>pcre_exec()</b> below.
367    <pre>
368      PCRE_CONFIG_MATCH_LIMIT_RECURSION
369    </pre>
370    The output is an integer that gives the default limit for the depth of
371    recursion when calling the internal matching function in a <b>pcre_exec()</b>
372    execution. Further details are given with <b>pcre_exec()</b> below.
373    <pre>
374      PCRE_CONFIG_STACKRECURSE
375    </pre>
376    The output is an integer that is set to one if internal recursion when running
377    <b>pcre_exec()</b> is implemented by recursive function calls that use the stack
378    to remember their state. This is the usual way that PCRE is compiled. The
379    output is zero if PCRE was compiled to use blocks of data on the heap instead
380    of recursive function calls. In this case, <b>pcre_stack_malloc</b> and
381    <b>pcre_stack_free</b> are called to manage memory blocks on the heap, thus
382    avoiding the use of the stack.
383  </P>  </P>
384  <br><a name="SEC5" href="#TOC1">COMPILING A PATTERN</a><br>  <br><a name="SEC7" href="#TOC1">COMPILING A PATTERN</a><br>
385  <P>  <P>
386  <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>
387  <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b>  <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
388  <b>const unsigned char *<i>tableptr</i>);</b>  <b>const unsigned char *<i>tableptr</i>);</b>
389    <b>pcre *pcre_compile2(const char *<i>pattern</i>, int <i>options</i>,</b>
390    <b>int *<i>errorcodeptr</i>,</b>
391    <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
392    <b>const unsigned char *<i>tableptr</i>);</b>
393    </P>
394    <P>
395    Either of the functions <b>pcre_compile()</b> or <b>pcre_compile2()</b> can be
396    called to compile a pattern into an internal form. The only difference between
397    the two interfaces is that <b>pcre_compile2()</b> has an additional argument,
398    <i>errorcodeptr</i>, via which a numerical error code can be returned.
399  </P>  </P>
400  <P>  <P>
401  The function <b>pcre_compile()</b> is called to compile a pattern into an  The pattern is a C string terminated by a binary zero, and is passed in the
402  internal form. The pattern is a C string terminated by a binary zero, and  <i>pattern</i> argument. A pointer to a single block of memory that is obtained
403  is passed in the argument <i>pattern</i>. A pointer to a single block of memory  via <b>pcre_malloc</b> is returned. This contains the compiled code and related
404  that is obtained via <b>pcre_malloc</b> is returned. This contains the compiled  data. The <b>pcre</b> type is defined for the returned block; this is a typedef
405  code and related data. The <b>pcre</b> type is defined for the returned block;  for a structure whose contents are not externally defined. It is up to the
406  this is a typedef for a structure whose contents are not externally defined. It  caller to free the memory (via <b>pcre_free</b>) when it is no longer required.
 is up to the caller to free the memory when it is no longer required.  
407  </P>  </P>
408  <P>  <P>
409  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
410  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
411  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>
412  which is an address (see below).  argument, which is an address (see below).
413  </P>  </P>
414  <P>  <P>
415  The <i>options</i> argument contains independent bits that affect the  The <i>options</i> argument contains various bit settings that affect the
416  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
417  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
418  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
419  in the <b>pcrepattern</b> documentation). For these options, the contents of the  the detailed description in the
420  <i>options</i> argument specifies their initial settings at the start of  <a href="pcrepattern.html"><b>pcrepattern</b></a>
421  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
422    specifies their initial settings at the start of compilation and execution. The
423    PCRE_ANCHORED and PCRE_NEWLINE_<i>xxx</i> options can be set at the time of
424  matching as well as at compile time.  matching as well as at compile time.
425  </P>  </P>
426  <P>  <P>
427  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.
428  Otherwise, if compilation of a pattern fails, <b>pcre_compile()</b> returns  Otherwise, if compilation of a pattern fails, <b>pcre_compile()</b> returns
429  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
430  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
431  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
432    where the error was discovered is placed in the variable pointed to by
433  <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.
434  </P>  </P>
435  <P>  <P>
436  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
437  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
438  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
439  <b>pcre_maketables()</b>. See the section on locale support below.  textual error message. Error codes and messages are listed below.
440  </P>  </P>
441  <P>  <P>
442  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
443    character tables that are built when PCRE is compiled, using the default C
444    locale. Otherwise, <i>tableptr</i> must be an address that is the result of a
445    call to <b>pcre_maketables()</b>. This value is stored with the compiled
446    pattern, and used again by <b>pcre_exec()</b>, unless another table pointer is
447    passed to it. For more discussion, see the section on locale support below.
448  </P>  </P>
449  <P>  <P>
450    This code fragment shows a typical straightforward call to <b>pcre_compile()</b>:
451  <pre>  <pre>
452    pcre *re;    pcre *re;
453    const char *error;    const char *error;
# Line 297  This code fragment shows a typical strai Line 458  This code fragment shows a typical strai
458      &error,           /* for error message */      &error,           /* for error message */
459      &erroffset,       /* for error offset */      &erroffset,       /* for error offset */
460      NULL);            /* use default character tables */      NULL);            /* use default character tables */
461  </PRE>  </pre>
462  </P>  The following names for option bits are defined in the <b>pcre.h</b> header
463  <P>  file:
 The following option bits are defined:  
 </P>  
 <P>  
464  <pre>  <pre>
465    PCRE_ANCHORED    PCRE_ANCHORED
466  </PRE>  </pre>
 </P>  
 <P>  
467  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
468  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
469  being searched (the "subject string"). This effect can also be achieved by  being searched (the "subject string"). This effect can also be achieved by
470  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
471  Perl.  Perl.
472  </P>  <pre>
473  <P>    PCRE_AUTO_CALLOUT
474    </pre>
475    If this bit is set, <b>pcre_compile()</b> automatically inserts callout items,
476    all with number 255, before each pattern item. For discussion of the callout
477    facility, see the
478    <a href="pcrecallout.html"><b>pcrecallout</b></a>
479    documentation.
480    <pre>
481      PCRE_BSR_ANYCRLF
482      PCRE_BSR_UNICODE
483    </pre>
484    These options (which are mutually exclusive) control what the \R escape
485    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
486    match any Unicode newline sequence. The default is specified when PCRE is
487    built. It can be overridden from within the pattern, or by setting an option
488    when a compiled pattern is matched.
489  <pre>  <pre>
490    PCRE_CASELESS    PCRE_CASELESS
491  </PRE>  </pre>
 </P>  
 <P>  
492  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
493  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
494  pattern by a (?i) option setting.  pattern by a (?i) option setting. In UTF-8 mode, PCRE always understands the
495  </P>  concept of case for characters whose values are less than 128, so caseless
496  <P>  matching is always possible. For characters with higher values, the concept of
497    case is supported if PCRE is compiled with Unicode property support, but not
498    otherwise. If you want to use caseless matching for characters 128 and above,
499    you must ensure that PCRE is compiled with Unicode property support as well as
500    with UTF-8 support.
501  <pre>  <pre>
502    PCRE_DOLLAR_ENDONLY    PCRE_DOLLAR_ENDONLY
503  </PRE>  </pre>
 </P>  
 <P>  
504  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
505  end of the subject string. Without this option, a dollar also matches  end of the subject string. Without this option, a dollar also matches
506  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
507  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.
508  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
509  a pattern.  pattern.
 </P>  
 <P>  
510  <pre>  <pre>
511    PCRE_DOTALL    PCRE_DOTALL
512  </PRE>  </pre>
 </P>  
 <P>  
513  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,
514  including newlines. Without it, newlines are excluded. This option is  including those that indicate newline. Without it, a dot does not match when
515  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
516  (?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
517  character, independent of the setting of this option.  negative class such as [^a] always matches newline characters, independent of
518  </P>  the setting of this option.
519  <P>  <pre>
520      PCRE_DUPNAMES
521    </pre>
522    If this bit is set, names used to identify capturing subpatterns need not be
523    unique. This can be helpful for certain types of pattern when it is known that
524    only one instance of the named subpattern can ever be matched. There are more
525    details of named subpatterns below; see also the
526    <a href="pcrepattern.html"><b>pcrepattern</b></a>
527    documentation.
528  <pre>  <pre>
529    PCRE_EXTENDED    PCRE_EXTENDED
530  </PRE>  </pre>
 </P>  
 <P>  
531  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
532  ignored except when escaped or inside a character class. Whitespace does not  ignored except when escaped or inside a character class. Whitespace does not
533  include the VT character (code 11). In addition, characters between an  include the VT character (code 11). In addition, characters between an
534  unescaped # outside a character class and the next newline character,  unescaped # outside a character class and the next newline, inclusive, are also
535  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
536  be changed within a pattern by a (?x) option setting.  pattern by a (?x) option setting.
537  </P>  </P>
538  <P>  <P>
539  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
540  Note, however, that this applies only to data characters. Whitespace characters  Note, however, that this applies only to data characters. Whitespace characters
541  may never appear within special character sequences in a pattern, for example  may never appear within special character sequences in a pattern, for example
542  within the sequence (?( which introduces a conditional subpattern.  within the sequence (?( which introduces a conditional subpattern.
 </P>  
 <P>  
543  <pre>  <pre>
544    PCRE_EXTRA    PCRE_EXTRA
545  </PRE>  </pre>
 </P>  
 <P>  
546  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
547  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
548  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
549  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
550  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
551  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
552  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
553  pattern.  this option. It can also be set by a (?X) option setting within a pattern.
554  </P>  <pre>
555  <P>    PCRE_FIRSTLINE
556    </pre>
557    If this option is set, an unanchored pattern is required to match before or at
558    the first newline in the subject string, though the matched text may continue
559    over the newline.
560  <pre>  <pre>
561    PCRE_MULTILINE    PCRE_MULTILINE
562  </PRE>  </pre>
563  </P>  By default, PCRE treats the subject string as consisting of a single line of
564  <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"  
565  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
566  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
567  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 569  Perl.
569  </P>  </P>
570  <P>  <P>
571  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
572  match immediately following or immediately before any newline in the subject  match immediately following or immediately before internal newlines in the
573  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
574  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
575  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
576  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.
577    <pre>
578      PCRE_NEWLINE_CR
579      PCRE_NEWLINE_LF
580      PCRE_NEWLINE_CRLF
581      PCRE_NEWLINE_ANYCRLF
582      PCRE_NEWLINE_ANY
583    </pre>
584    These options override the default newline definition that was chosen when PCRE
585    was built. Setting the first or the second specifies that a newline is
586    indicated by a single character (CR or LF, respectively). Setting
587    PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
588    CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three
589    preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies
590    that any Unicode newline sequence should be recognized. The Unicode newline
591    sequences are the three just mentioned, plus the single characters VT (vertical
592    tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS (line
593    separator, U+2028), and PS (paragraph separator, U+2029). The last two are
594    recognized only in UTF-8 mode.
595    </P>
596    <P>
597    The newline setting in the options word uses three bits that are treated
598    as a number, giving eight possibilities. Currently only six are used (default
599    plus the five values above). This means that if you set more than one newline
600    option, the combination may or may not be sensible. For example,
601    PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
602    other combinations may yield unused numbers and cause an error.
603    </P>
604    <P>
605    The only time that a line break is specially recognized when compiling a
606    pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character
607    class is encountered. This indicates a comment that lasts until after the next
608    line break sequence. In other circumstances, line break sequences are treated
609    as literal data, except that in PCRE_EXTENDED mode, both CR and LF are treated
610    as whitespace characters and are therefore ignored.
611  </P>  </P>
612  <P>  <P>
613    The newline option that is set at compile time becomes the default that is used
614    for <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>, but it can be overridden.
615  <pre>  <pre>
616    PCRE_NO_AUTO_CAPTURE    PCRE_NO_AUTO_CAPTURE
617  </PRE>  </pre>
 </P>  
 <P>  
618  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
619  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
620  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
621  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
622  in Perl.  in Perl.
 </P>  
 <P>  
623  <pre>  <pre>
624    PCRE_UNGREEDY    PCRE_UNGREEDY
625  </PRE>  </pre>
 </P>  
 <P>  
626  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
627  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
628  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>  
629  <pre>  <pre>
630    PCRE_UTF8    PCRE_UTF8
631  </PRE>  </pre>
 </P>  
 <P>  
632  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
633  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
634  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
635  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
636  behaviour of PCRE are given in the  behaviour of PCRE are given in the
637  <a href="pcre.html#utf8support">section on UTF-8 support</a>  <a href="pcre.html#utf8support">section on UTF-8 support</a>
638  in the main  in the main
639  <a href="pcre.html"><b>pcre</b></a>  <a href="pcre.html"><b>pcre</b></a>
640  page.  page.
641    <pre>
642      PCRE_NO_UTF8_CHECK
643    </pre>
644    When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
645    automatically checked. There is a discussion about the
646    <a href="pcre.html#utf8strings">validity of UTF-8 strings</a>
647    in the main
648    <a href="pcre.html"><b>pcre</b></a>
649    page. If an invalid UTF-8 sequence of bytes is found, <b>pcre_compile()</b>
650    returns an error. If you already know that your pattern is valid, and you want
651    to skip this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK
652    option. When it is set, the effect of passing an invalid UTF-8 string as a
653    pattern is undefined. It may cause your program to crash. Note that this option
654    can also be passed to <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>, to suppress
655    the UTF-8 validity checking of subject strings.
656    </P>
657    <br><a name="SEC8" href="#TOC1">COMPILATION ERROR CODES</a><br>
658    <P>
659    The following table lists the error codes than may be returned by
660    <b>pcre_compile2()</b>, along with the error messages that may be returned by
661    both compiling functions. As PCRE has developed, some error codes have fallen
662    out of use. To avoid confusion, they have not been re-used.
663    <pre>
664       0  no error
665       1  \ at end of pattern
666       2  \c at end of pattern
667       3  unrecognized character follows \
668       4  numbers out of order in {} quantifier
669       5  number too big in {} quantifier
670       6  missing terminating ] for character class
671       7  invalid escape sequence in character class
672       8  range out of order in character class
673       9  nothing to repeat
674      10  [this code is not in use]
675      11  internal error: unexpected repeat
676      12  unrecognized character after (? or (?-
677      13  POSIX named classes are supported only within a class
678      14  missing )
679      15  reference to non-existent subpattern
680      16  erroffset passed as NULL
681      17  unknown option bit(s) set
682      18  missing ) after comment
683      19  [this code is not in use]
684      20  regular expression is too large
685      21  failed to get memory
686      22  unmatched parentheses
687      23  internal error: code overflow
688      24  unrecognized character after (?&#60;
689      25  lookbehind assertion is not fixed length
690      26  malformed number or name after (?(
691      27  conditional group contains more than two branches
692      28  assertion expected after (?(
693      29  (?R or (?[+-]digits must be followed by )
694      30  unknown POSIX class name
695      31  POSIX collating elements are not supported
696      32  this version of PCRE is not compiled with PCRE_UTF8 support
697      33  [this code is not in use]
698      34  character value in \x{...} sequence is too large
699      35  invalid condition (?(0)
700      36  \C not allowed in lookbehind assertion
701      37  PCRE does not support \L, \l, \N, \U, or \u
702      38  number after (?C is &#62; 255
703      39  closing ) for (?C expected
704      40  recursive call could loop indefinitely
705      41  unrecognized character after (?P
706      42  syntax error in subpattern name (missing terminator)
707      43  two named subpatterns have the same name
708      44  invalid UTF-8 string
709      45  support for \P, \p, and \X has not been compiled
710      46  malformed \P or \p sequence
711      47  unknown property name after \P or \p
712      48  subpattern name is too long (maximum 32 characters)
713      49  too many named subpatterns (maximum 10000)
714      50  [this code is not in use]
715      51  octal value is greater than \377 (not in UTF-8 mode)
716      52  internal error: overran compiling workspace
717      53  internal error: previously-checked referenced subpattern not found
718      54  DEFINE group contains more than one branch
719      55  repeating a DEFINE group is not allowed
720      56  inconsistent NEWLINE options
721      57  \g is not followed by a braced name or an optionally braced
722            non-zero number
723      58  (?+ or (?- or (?(+ or (?(- must be followed by a non-zero number
724      59  (*VERB) with an argument is not supported
725      60  (*VERB) not recognized
726      61  number is too big
727      62  subpattern name expected
728      63  digit expected after (?+
729    </pre>
730    The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
731    be used if the limits were changed when PCRE was built.
732  </P>  </P>
733  <br><a name="SEC6" href="#TOC1">STUDYING A PATTERN</a><br>  <br><a name="SEC9" href="#TOC1">STUDYING A PATTERN</a><br>
734  <P>  <P>
735  <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>
736  <b>const char **<i>errptr</i>);</b>  <b>const char **<i>errptr</i>);</b>
737  </P>  </P>
738  <P>  <P>
739  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
740  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
741  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
742  argument. If studing the pattern produces additional information that will help  argument. If studying the pattern produces additional information that will
743  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
744  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
745    results of the study.
746  </P>  </P>
747  <P>  <P>
748  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
749  <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
750  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
751  described below. If studying the pattern does not produce any additional  described
752  information, <b>pcre_study()</b> returns NULL. In that circumstance, if the  <a href="#extradata">below</a>
753  calling program wants to pass some of the other fields to <b>pcre_exec()</b>, it  in the section on matching a pattern.
 must set up its own <b>pcre_extra</b> block.  
754  </P>  </P>
755  <P>  <P>
756  The second argument contains option bits. At present, no options are defined  If studying the pattern does not produce any additional information
757  for <b>pcre_study()</b>, and this argument should always be zero.  <b>pcre_study()</b> returns NULL. In that circumstance, if the calling program
758    wants to pass any of the other fields to <b>pcre_exec()</b>, it must set up its
759    own <b>pcre_extra</b> block.
760    </P>
761    <P>
762    The second argument of <b>pcre_study()</b> contains option bits. At present, no
763    options are defined, and this argument should always be zero.
764  </P>  </P>
765  <P>  <P>
766  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
767  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
768  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
769  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
770  be sure that it has run successfully.  should test the error pointer for NULL after calling <b>pcre_study()</b>, to be
771    sure that it has run successfully.
772  </P>  </P>
773  <P>  <P>
774  This is a typical call to <b>pcre_study</b>():  This is a typical call to <b>pcre_study</b>():
 </P>  
 <P>  
775  <pre>  <pre>
776    pcre_extra *pe;    pcre_extra *pe;
777    pe = pcre_study(    pe = pcre_study(
778      re,             /* result of pcre_compile() */      re,             /* result of pcre_compile() */
779      0,              /* no options exist */      0,              /* no options exist */
780      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
781  </PRE>  </pre>
 </P>  
 <P>  
782  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
783  not have a single fixed starting character. A bitmap of possible starting  not have a single fixed starting character. A bitmap of possible starting
784  characters is created.  bytes is created.
785  </P>  <a name="localesupport"></a></P>
786  <a name="localesupport"></a><br><a name="SEC7" href="#TOC1">LOCALE SUPPORT</a><br>  <br><a name="SEC10" href="#TOC1">LOCALE SUPPORT</a><br>
787  <P>  <P>
788  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters,
789  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
790  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
791  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
792  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
793  is NULL, and is sufficient for many applications.  support. The use of locales with Unicode is discouraged. If you are handling
794  </P>  characters with codes greater than 128, you should either use UTF-8 and
795  <P>  Unicode, or use locales, but not try to mix the two.
796  An alternative set of tables can, however, be supplied. Such tables are built  </P>
797  by calling the <b>pcre_maketables()</b> function, which has no arguments, in the  <P>
798  relevant locale. The result can then be passed to <b>pcre_compile()</b> as often  PCRE contains an internal set of tables that are used when the final argument
799  as necessary. For example, to build and use tables that are appropriate for the  of <b>pcre_compile()</b> is NULL. These are sufficient for many applications.
800  French locale (where accented characters with codes greater than 128 are  Normally, the internal tables recognize only ASCII characters. However, when
801  treated as letters), the following code could be used:  PCRE is built, it is possible to cause the internal tables to be rebuilt in the
802  </P>  default "C" locale of the local system, which may cause them to be different.
803  <P>  </P>
804    <P>
805    The internal tables can always be overridden by tables supplied by the
806    application that calls PCRE. These may be created in a different locale from
807    the default. As more and more applications change to using Unicode, the need
808    for this locale support is expected to die away.
809    </P>
810    <P>
811    External tables are built by calling the <b>pcre_maketables()</b> function,
812    which has no arguments, in the relevant locale. The result can then be passed
813    to <b>pcre_compile()</b> or <b>pcre_exec()</b> as often as necessary. For
814    example, to build and use tables that are appropriate for the French locale
815    (where accented characters with values greater than 128 are treated as letters),
816    the following code could be used:
817  <pre>  <pre>
818    setlocale(LC_CTYPE, "fr");    setlocale(LC_CTYPE, "fr_FR");
819    tables = pcre_maketables();    tables = pcre_maketables();
820    re = pcre_compile(..., tables);    re = pcre_compile(..., tables);
821  </PRE>  </pre>
822    The locale name "fr_FR" is used on Linux and other Unix-like systems; if you
823    are using Windows, the name for the French locale is "french".
824  </P>  </P>
825  <P>  <P>
826  The tables are built in memory that is obtained via <b>pcre_malloc</b>. The  When <b>pcre_maketables()</b> runs, the tables are built in memory that is
827  pointer that is passed to <b>pcre_compile</b> is saved with the compiled  obtained via <b>pcre_malloc</b>. It is the caller's responsibility to ensure
828    that the memory containing the tables remains available for as long as it is
829    needed.
830    </P>
831    <P>
832    The pointer that is passed to <b>pcre_compile()</b> is saved with the compiled
833  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>
834  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
835  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
836  in different locales. It is the caller's responsibility to ensure that the  different patterns can be compiled in different locales.
837  memory containing the tables remains available for as long as it is needed.  </P>
838    <P>
839    It is possible to pass a table pointer or NULL (indicating the use of the
840    internal tables) to <b>pcre_exec()</b>. Although not intended for this purpose,
841    this facility could be used to match a pattern in a different locale from the
842    one in which it was compiled. Passing table pointers at run time is discussed
843    below in the section on matching a pattern.
844  </P>  </P>
845  <br><a name="SEC8" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br>  <br><a name="SEC11" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br>
846  <P>  <P>
847  <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>
848  <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 859  the pattern was not studied. The third a
859  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
860  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
861  the following negative numbers:  the following negative numbers:
 </P>  
 <P>  
862  <pre>  <pre>
863    PCRE_ERROR_NULL       the argument <i>code</i> was NULL    PCRE_ERROR_NULL       the argument <i>code</i> was NULL
864                          the argument <i>where</i> was NULL                          the argument <i>where</i> was NULL
865    PCRE_ERROR_BADMAGIC   the "magic number" was not found    PCRE_ERROR_BADMAGIC   the "magic number" was not found
866    PCRE_ERROR_BADOPTION  the value of <i>what</i> was invalid    PCRE_ERROR_BADOPTION  the value of <i>what</i> was invalid
867  </PRE>  </pre>
868  </P>  The "magic number" is placed at the start of each compiled pattern as an simple
869  <P>  check against passing an arbitrary memory pointer. Here is a typical call of
870  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>  
871  <pre>  <pre>
872    int rc;    int rc;
873    unsigned long int length;    size_t length;
874    rc = pcre_fullinfo(    rc = pcre_fullinfo(
875      re,               /* result of pcre_compile() */      re,               /* result of pcre_compile() */
876      pe,               /* result of pcre_study(), or NULL */      pe,               /* result of pcre_study(), or NULL */
877      PCRE_INFO_SIZE,   /* what is required */      PCRE_INFO_SIZE,   /* what is required */
878      &length);         /* where to put the data */      &length);         /* where to put the data */
879  </PRE>  </pre>
 </P>  
 <P>  
880  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
881  as follows:  as follows:
 </P>  
 <P>  
882  <pre>  <pre>
883    PCRE_INFO_BACKREFMAX    PCRE_INFO_BACKREFMAX
884  </PRE>  </pre>
 </P>  
 <P>  
885  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
886  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
887  no back references.  no back references.
 </P>  
 <P>  
888  <pre>  <pre>
889    PCRE_INFO_CAPTURECOUNT    PCRE_INFO_CAPTURECOUNT
890  </PRE>  </pre>
 </P>  
 <P>  
891  Return the number of capturing subpatterns in the pattern. The fourth argument  Return the number of capturing subpatterns in the pattern. The fourth argument
892  should point to an \fbint\fR variable.  should point to an <b>int</b> variable.
893  </P>  <pre>
894  <P>    PCRE_INFO_DEFAULT_TABLES
895    </pre>
896    Return a pointer to the internal default character tables within PCRE. The
897    fourth argument should point to an <b>unsigned char *</b> variable. This
898    information call is provided for internal use by the <b>pcre_study()</b>
899    function. External callers can cause PCRE to use its internal tables by passing
900    a NULL table pointer.
901  <pre>  <pre>
902    PCRE_INFO_FIRSTBYTE    PCRE_INFO_FIRSTBYTE
903  </PRE>  </pre>
 </P>  
 <P>  
904  Return information about the first byte of any matched string, for a  Return information about the first byte of any matched string, for a
905  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>
906  old name is still recognized for backwards compatibility.)  variable. (This option used to be called PCRE_INFO_FIRSTCHAR; the old name is
907  </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  
908  </P>  </P>
909  <P>  <P>
910    If there is a fixed first byte, for example, from a pattern such as
911    (cat|cow|coyote), its value is returned. Otherwise, if either
912    <br>
913    <br>
914  (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
915  starts with "^", or  starts with "^", or
916  </P>  <br>
917  <P>  <br>
918  (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
919  (if it were set, the pattern would be anchored),  (if it were set, the pattern would be anchored),
920  </P>  <br>
921  <P>  <br>
922  -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
923  subject string or after any newline within the string. Otherwise -2 is  subject string or after any newline within the string. Otherwise -2 is
924  returned. For anchored patterns, -2 is returned.  returned. For anchored patterns, -2 is returned.
 </P>  
 <P>  
925  <pre>  <pre>
926    PCRE_INFO_FIRSTTABLE    PCRE_INFO_FIRSTTABLE
927  </PRE>  </pre>
 </P>  
 <P>  
928  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
929  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
930  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
931  fourth argument should point to an <b>unsigned char *</b> variable.  fourth argument should point to an <b>unsigned char *</b> variable.
932  </P>  <pre>
933  <P>    PCRE_INFO_HASCRORLF
934    </pre>
935    Return 1 if the pattern contains any explicit matches for CR or LF characters,
936    otherwise 0. The fourth argument should point to an <b>int</b> variable. An
937    explicit match is either a literal CR or LF character, or \r or \n.
938    <pre>
939      PCRE_INFO_JCHANGED
940    </pre>
941    Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise
942    0. The fourth argument should point to an <b>int</b> variable. (?J) and
943    (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
944  <pre>  <pre>
945    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
946  </PRE>  </pre>
 </P>  
 <P>  
947  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
948  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
949  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 951  returned. For anchored patterns, a last
951  follows something of variable length. For example, for the pattern  follows something of variable length. For example, for the pattern
952  /^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
953  is -1.  is -1.
 </P>  
 <P>  
954  <pre>  <pre>
955    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
956    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
957    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
958  </PRE>  </pre>
 </P>  
 <P>  
959  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
960  names are just an additional way of identifying the parentheses, which still  names are just an additional way of identifying the parentheses, which still
961  acquire a number. A caller that wants to extract data from a named subpattern  acquire numbers. Several convenience functions such as
962  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
963  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
964  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
965  table for the pattern.  output vector (described with <b>pcre_exec()</b> below). To do the conversion,
966    you need to use the name-to-number map, which is described by these three
967    values.
968  </P>  </P>
969  <P>  <P>
970  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 974  length of the longest name. PCRE_INFO_NA
974  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
975  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
976  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
977  alphabetical order. For example, consider the following pattern (assume  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of
978    their parentheses numbers. For example, consider the following pattern (assume
979  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  PCRE_EXTENDED is set, so white space - including newlines - is ignored):
 </P>  
 <P>  
980  <pre>  <pre>
981    (?P&#60;date&#62; (?P&#60;year&#62;(\d\d)?\d\d) -    (?&#60;date&#62; (?&#60;year&#62;(\d\d)?\d\d) - (?&#60;month&#62;\d\d) - (?&#60;day&#62;\d\d) )
982    (?P&#60;month&#62;\d\d) - (?P&#60;day&#62;\d\d) )  </pre>
 </PRE>  
 </P>  
 <P>  
983  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
984  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
985  bytes shows in hex, and undefined bytes shown as ??:  bytes shows in hexadecimal, and undefined bytes shown as ??:
 </P>  
 <P>  
986  <pre>  <pre>
987    00 01 d  a  t  e  00 ??    00 01 d  a  t  e  00 ??
988    00 05 d  a  y  00 ?? ??    00 05 d  a  y  00 ?? ??
989    00 04 m  o  n  t  h  00    00 04 m  o  n  t  h  00
990    00 02 y  e  a  r  00 ??    00 02 y  e  a  r  00 ??
991  </PRE>  </pre>
992  </P>  When writing code to extract data from named subpatterns using the
993  <P>  name-to-number map, remember that the length of the entries is likely to be
994  When writing code to extract data from named subpatterns, remember that the  different for each compiled pattern.
995  length of each entry may be different for each compiled pattern.  <pre>
996  </P>    PCRE_INFO_OKPARTIAL
997  <P>  </pre>
998    Return 1 if the pattern can be used for partial matching, otherwise 0. The
999    fourth argument should point to an <b>int</b> variable. The
1000    <a href="pcrepartial.html"><b>pcrepartial</b></a>
1001    documentation lists the restrictions that apply to patterns when partial
1002    matching is used.
1003  <pre>  <pre>
1004    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
1005  </PRE>  </pre>
 </P>  
 <P>  
1006  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
1007  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
1008  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
1009  top-level option settings within the pattern itself.  top-level option settings at the start of the pattern itself. In other words,
1010    they are the options that will be in force when matching starts. For example,
1011    if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED option, the
1012    result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED.
1013  </P>  </P>
1014  <P>  <P>
1015  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
1016  alternatives begin with one of the following:  alternatives begin with one of the following:
 </P>  
 <P>  
1017  <pre>  <pre>
1018    ^     unless PCRE_MULTILINE is set    ^     unless PCRE_MULTILINE is set
1019    \A    always    \A    always
1020    \G    always    \G    always
1021    .*    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
1022            references to the subpattern in which .* appears  </pre>
 </PRE>  
 </P>  
 <P>  
1023  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
1024  <b>pcre_fullinfo()</b>.  <b>pcre_fullinfo()</b>.
 </P>  
 <P>  
1025  <pre>  <pre>
1026    PCRE_INFO_SIZE    PCRE_INFO_SIZE
1027  </PRE>  </pre>
 </P>  
 <P>  
1028  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
1029  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
1030  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>
1031  variable.  variable.
 </P>  
 <P>  
1032  <pre>  <pre>
1033    PCRE_INFO_STUDYSIZE    PCRE_INFO_STUDYSIZE
1034  </PRE>  </pre>
1035  </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  
1036  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
1037  <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
1038  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
1039  <b>size_t</b> variable.  <b>size_t</b> variable.
1040  </P>  </P>
1041  <br><a name="SEC9" href="#TOC1">OBSOLETE INFO FUNCTION</a><br>  <br><a name="SEC12" href="#TOC1">OBSOLETE INFO FUNCTION</a><br>
1042  <P>  <P>
1043  <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>
1044  <b>*<i>firstcharptr</i>);</b>  <b>*<i>firstcharptr</i>);</b>
# Line 753  restrictive to return all the available Line 1049  restrictive to return all the available
1049  programs should use <b>pcre_fullinfo()</b> instead. The yield of  programs should use <b>pcre_fullinfo()</b> instead. The yield of
1050  <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
1051  following negative numbers:  following negative numbers:
 </P>  
 <P>  
1052  <pre>  <pre>
1053    PCRE_ERROR_NULL       the argument <i>code</i> was NULL    PCRE_ERROR_NULL       the argument <i>code</i> was NULL
1054    PCRE_ERROR_BADMAGIC   the "magic number" was not found    PCRE_ERROR_BADMAGIC   the "magic number" was not found
1055  </PRE>  </pre>
 </P>  
 <P>  
1056  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
1057  pattern was compiled is placed in the integer it points to (see  pattern was compiled is placed in the integer it points to (see
1058  PCRE_INFO_OPTIONS above).  PCRE_INFO_OPTIONS above).
# Line 770  If the pattern is not anchored and the < Line 1062  If the pattern is not anchored and the <
1062  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
1063  string (see PCRE_INFO_FIRSTBYTE above).  string (see PCRE_INFO_FIRSTBYTE above).
1064  </P>  </P>
1065  <br><a name="SEC10" href="#TOC1">MATCHING A PATTERN</a><br>  <br><a name="SEC13" href="#TOC1">REFERENCE COUNTS</a><br>
1066    <P>
1067    <b>int pcre_refcount(pcre *<i>code</i>, int <i>adjust</i>);</b>
1068    </P>
1069    <P>
1070    The <b>pcre_refcount()</b> function is used to maintain a reference count in the
1071    data block that contains a compiled pattern. It is provided for the benefit of
1072    applications that operate in an object-oriented manner, where different parts
1073    of the application may be using the same compiled pattern, but you want to free
1074    the block when they are all done.
1075    </P>
1076    <P>
1077    When a pattern is compiled, the reference count field is initialized to zero.
1078    It is changed only by calling this function, whose action is to add the
1079    <i>adjust</i> value (which may be positive or negative) to it. The yield of the
1080    function is the new value. However, the value of the count is constrained to
1081    lie between 0 and 65535, inclusive. If the new value is outside these limits,
1082    it is forced to the appropriate limit value.
1083    </P>
1084    <P>
1085    Except when it is zero, the reference count is not correctly preserved if a
1086    pattern is compiled on one host and then transferred to a host whose byte-order
1087    is different. (This seems a highly unlikely scenario.)
1088    </P>
1089    <br><a name="SEC14" href="#TOC1">MATCHING A PATTERN: THE TRADITIONAL FUNCTION</a><br>
1090  <P>  <P>
1091  <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>
1092  <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 1094  string (see PCRE_INFO_FIRSTBYTE above).
1094  </P>  </P>
1095  <P>  <P>
1096  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
1097  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
1098  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
1099  <i>extra</i> argument.  <i>extra</i> argument. This function is the main matching facility of the
1100    library, and it operates in a Perl-like manner. For specialist use there is
1101    also an alternative matching function, which is described
1102    <a href="#dfamatch">below</a>
1103    in the section about the <b>pcre_dfa_exec()</b> function.
1104  </P>  </P>
1105  <P>  <P>
1106  Here is an example of a simple call to <b>pcre_exec()</b>:  In most applications, the pattern will have been compiled (and optionally
1107    studied) in the same process that calls <b>pcre_exec()</b>. However, it is
1108    possible to save compiled patterns and study data, and then use them later
1109    in different processes, possibly even on different hosts. For a discussion
1110    about this, see the
1111    <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
1112    documentation.
1113  </P>  </P>
1114  <P>  <P>
1115    Here is an example of a simple call to <b>pcre_exec()</b>:
1116  <pre>  <pre>
1117    int rc;    int rc;
1118    int ovector[30];    int ovector[30];
# Line 796  Here is an example of a simple call to < Line 1123  Here is an example of a simple call to <
1123      11,             /* the length of the subject string */      11,             /* the length of the subject string */
1124      0,              /* start at offset 0 in the subject */      0,              /* start at offset 0 in the subject */
1125      0,              /* default options */      0,              /* default options */
1126      ovector,        /* vector for substring information */      ovector,        /* vector of integers for substring information */
1127      30);            /* number of elements in the vector */      30);            /* number of elements (NOT size in bytes) */
1128  </PRE>  <a name="extradata"></a></PRE>
1129  </P>  </P>
1130    <br><b>
1131    Extra data for <b>pcre_exec()</b>
1132    </b><br>
1133  <P>  <P>
1134  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>
1135  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
1136  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
1137  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
1138  </P>  fields (not necessarily in this order):
 <P>  
1139  <pre>  <pre>
1140    unsigned long int <i>flags</i>;    unsigned long int <i>flags</i>;
1141    void *<i>study_data</i>;    void *<i>study_data</i>;
1142    unsigned long int <i>match_limit</i>;    unsigned long int <i>match_limit</i>;
1143      unsigned long int <i>match_limit_recursion</i>;
1144    void *<i>callout_data</i>;    void *<i>callout_data</i>;
1145  </PRE>    const unsigned char *<i>tables</i>;
1146  </P>  </pre>
 <P>  
1147  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
1148  are set. The flag bits are:  are set. The flag bits are:
 </P>  
 <P>  
1149  <pre>  <pre>
1150    PCRE_EXTRA_STUDY_DATA    PCRE_EXTRA_STUDY_DATA
1151    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1152      PCRE_EXTRA_MATCH_LIMIT_RECURSION
1153    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1154  </PRE>    PCRE_EXTRA_TABLES
1155  </P>  </pre>
 <P>  
1156  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
1157  <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
1158  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
1159  the block by setting the other fields.  the block by setting the other fields and their corresponding flag bits.
1160  </P>  </P>
1161  <P>  <P>
1162  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
1163  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,
1164  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
1165  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.  
1166  </P>  </P>
1167  <P>  <P>
1168  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
1169    (sometimes recursively). The limit set by <i>match_limit</i> is imposed on the
1170    number of times this function is called during a match, which has the effect of
1171    limiting the amount of backtracking that can take place. For patterns that are
1172    not anchored, the count restarts from zero for each position in the subject
1173    string.
1174    </P>
1175    <P>
1176    The default value for the limit can be set when PCRE is built; the default
1177  default is 10 million, which handles all but the most extreme cases. You can  default is 10 million, which handles all but the most extreme cases. You can
1178  reduce the default by suppling <b>pcre_exec()</b> with a \fRpcre_extra\fR block  override the default by suppling <b>pcre_exec()</b> with a <b>pcre_extra</b>
1179  in which <i>match_limit</i> is set to a smaller value, and  block in which <i>match_limit</i> is set, and PCRE_EXTRA_MATCH_LIMIT is set in
1180  PCRE_EXTRA_MATCH_LIMIT is set in the <i>flags</i> field. If the limit is  the <i>flags</i> field. If the limit is exceeded, <b>pcre_exec()</b> returns
1181  exceeded, <b>pcre_exec()</b> returns PCRE_ERROR_MATCHLIMIT.  PCRE_ERROR_MATCHLIMIT.
1182    </P>
1183    <P>
1184    The <i>match_limit_recursion</i> field is similar to <i>match_limit</i>, but
1185    instead of limiting the total number of times that <b>match()</b> is called, it
1186    limits the depth of recursion. The recursion depth is a smaller number than the
1187    total number of calls, because not all calls to <b>match()</b> are recursive.
1188    This limit is of use only if it is set smaller than <i>match_limit</i>.
1189    </P>
1190    <P>
1191    Limiting the recursion depth limits the amount of stack that can be used, or,
1192    when PCRE has been compiled to use memory on the heap instead of the stack, the
1193    amount of heap memory that can be used.
1194    </P>
1195    <P>
1196    The default value for <i>match_limit_recursion</i> can be set when PCRE is
1197    built; the default default is the same value as the default for
1198    <i>match_limit</i>. You can override the default by suppling <b>pcre_exec()</b>
1199    with a <b>pcre_extra</b> block in which <i>match_limit_recursion</i> is set, and
1200    PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the <i>flags</i> field. If the limit
1201    is exceeded, <b>pcre_exec()</b> returns PCRE_ERROR_RECURSIONLIMIT.
1202  </P>  </P>
1203  <P>  <P>
1204  The <i>pcre_callout</i> field is used in conjunction with the "callout" feature,  The <i>pcre_callout</i> field is used in conjunction with the "callout" feature,
1205  which is described in the <b>pcrecallout</b> documentation.  which is described in the
1206    <a href="pcrecallout.html"><b>pcrecallout</b></a>
1207    documentation.
1208  </P>  </P>
1209  <P>  <P>
1210  The PCRE_ANCHORED option can be passed in the <i>options</i> argument, whose  The <i>tables</i> field is used to pass a character tables pointer to
1211  unused bits must be zero. This limits <b>pcre_exec()</b> to matching at the  <b>pcre_exec()</b>; this overrides the value that is stored with the compiled
1212  first matching position. However, if a pattern was compiled with PCRE_ANCHORED,  pattern. A non-NULL value is stored with the compiled pattern only if custom
1213  or turned out to be anchored by virtue of its contents, it cannot be made  tables were supplied to <b>pcre_compile()</b> via its <i>tableptr</i> argument.
1214  unachored at matching time.  If NULL is passed to <b>pcre_exec()</b> using this mechanism, it forces PCRE's
1215    internal tables to be used. This facility is helpful when re-using patterns
1216    that have been saved after compiling with an external set of tables, because
1217    the external tables might be at a different address when <b>pcre_exec()</b> is
1218    called. See the
1219    <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
1220    documentation for a discussion of saving compiled patterns for later use.
1221    <a name="execoptions"></a></P>
1222    <br><b>
1223    Option bits for <b>pcre_exec()</b>
1224    </b><br>
1225    <P>
1226    The unused bits of the <i>options</i> argument for <b>pcre_exec()</b> must be
1227    zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_<i>xxx</i>,
1228    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.
1229    <pre>
1230      PCRE_ANCHORED
1231    </pre>
1232    The PCRE_ANCHORED option limits <b>pcre_exec()</b> to matching at the first
1233    matching position. If a pattern was compiled with PCRE_ANCHORED, or turned out
1234    to be anchored by virtue of its contents, it cannot be made unachored at
1235    matching time.
1236    <pre>
1237      PCRE_BSR_ANYCRLF
1238      PCRE_BSR_UNICODE
1239    </pre>
1240    These options (which are mutually exclusive) control what the \R escape
1241    sequence matches. The choice is either to match only CR, LF, or CRLF, or to
1242    match any Unicode newline sequence. These options override the choice that was
1243    made or defaulted when the pattern was compiled.
1244    <pre>
1245      PCRE_NEWLINE_CR
1246      PCRE_NEWLINE_LF
1247      PCRE_NEWLINE_CRLF
1248      PCRE_NEWLINE_ANYCRLF
1249      PCRE_NEWLINE_ANY
1250    </pre>
1251    These options override the newline definition that was chosen or defaulted when
1252    the pattern was compiled. For details, see the description of
1253    <b>pcre_compile()</b> above. During matching, the newline choice affects the
1254    behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1255    the way the match position is advanced after a match failure for an unanchored
1256    pattern.
1257  </P>  </P>
1258  <P>  <P>
1259  There are also three further options that can be set only at matching time:  When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a
1260    match attempt for an unanchored pattern fails when the current position is at a
1261    CRLF sequence, and the pattern contains no explicit matches for CR or LF
1262    characters, the match position is advanced by two characters instead of one, in
1263    other words, to after the CRLF.
1264  </P>  </P>
1265  <P>  <P>
1266  <pre>  The above rule is a compromise that makes the most common cases work as
1267    PCRE_NOTBOL  expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
1268  </PRE>  set), it does not match the string "\r\nA" because, after failing at the
1269    start, it skips both the CR and the LF before retrying. However, the pattern
1270    [\r\n]A does match that string, because it contains an explicit CR or LF
1271    reference, and so advances only by one character after the first failure.
1272  </P>  </P>
1273  <P>  <P>
1274  The first character of the string is not the beginning of a line, so the  An explicit match for CR of LF is either a literal appearance of one of those
1275  circumflex metacharacter should not match before it. Setting this without  characters, or one of the \r or \n escape sequences. Implicit matches such as
1276  PCRE_MULTILINE (at compile time) causes circumflex never to match.  [^X] do not count, nor does \s (which includes CR and LF in the characters
1277    that it matches).
1278  </P>  </P>
1279  <P>  <P>
1280    Notwithstanding the above, anomalous effects may still occur when CRLF is a
1281    valid newline sequence and explicit \r or \n escapes appear in the pattern.
1282    <pre>
1283      PCRE_NOTBOL
1284    </pre>
1285    This option specifies that first character of the subject string is not the
1286    beginning of a line, so the circumflex metacharacter should not match before
1287    it. Setting this without PCRE_MULTILINE (at compile time) causes circumflex
1288    never to match. This option affects only the behaviour of the circumflex
1289    metacharacter. It does not affect \A.
1290  <pre>  <pre>
1291    PCRE_NOTEOL    PCRE_NOTEOL
1292  </PRE>  </pre>
1293  </P>  This option specifies that the end of the subject string is not the end of a
1294  <P>  line, so the dollar metacharacter should not match it nor (except in multiline
1295  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
1296  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
1297  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>  
1298  <pre>  <pre>
1299    PCRE_NOTEMPTY    PCRE_NOTEMPTY
1300  </PRE>  </pre>
 </P>  
 <P>  
1301  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
1302  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
1303  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>  
1304  <pre>  <pre>
1305    a?b?    a?b?
1306  </PRE>  </pre>
 </P>  
 <P>  
1307  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
1308  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
1309  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 1313  Perl has no direct equivalent of PCRE_NO
1313  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
1314  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
1315  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
1316  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
1317  below) and trying an ordinary match again.  starting offset (see below) and trying an ordinary match again. There is some
1318    code that demonstrates how to do this in the <i>pcredemo.c</i> sample program.
1319    <pre>
1320      PCRE_NO_UTF8_CHECK
1321    </pre>
1322    When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8
1323    string is automatically checked when <b>pcre_exec()</b> is subsequently called.
1324    The value of <i>startoffset</i> is also checked to ensure that it points to the
1325    start of a UTF-8 character. There is a discussion about the validity of UTF-8
1326    strings in the
1327    <a href="pcre.html#utf8strings">section on UTF-8 support</a>
1328    in the main
1329    <a href="pcre.html"><b>pcre</b></a>
1330    page. If an invalid UTF-8 sequence of bytes is found, <b>pcre_exec()</b> returns
1331    the error PCRE_ERROR_BADUTF8. If <i>startoffset</i> contains an invalid value,
1332    PCRE_ERROR_BADUTF8_OFFSET is returned.
1333    </P>
1334    <P>
1335    If you already know that your subject is valid, and you want to skip these
1336    checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when
1337    calling <b>pcre_exec()</b>. You might want to do this for the second and
1338    subsequent calls to <b>pcre_exec()</b> if you are making repeated calls to find
1339    all the matches in a single subject string. However, you should be sure that
1340    the value of <i>startoffset</i> points to the start of a UTF-8 character. When
1341    PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid UTF-8 string as a
1342    subject, or a value of <i>startoffset</i> that does not point to the start of a
1343    UTF-8 character, is undefined. Your program may crash.
1344    <pre>
1345      PCRE_PARTIAL
1346    </pre>
1347    This option turns on the partial matching feature. If the subject string fails
1348    to match the pattern, but at some point during the matching process the end of
1349    the subject was reached (that is, the subject partially matches the pattern and
1350    the failure to match occurred only because there were not enough subject
1351    characters), <b>pcre_exec()</b> returns PCRE_ERROR_PARTIAL instead of
1352    PCRE_ERROR_NOMATCH. When PCRE_PARTIAL is used, there are restrictions on what
1353    may appear in the pattern. These are discussed in the
1354    <a href="pcrepartial.html"><b>pcrepartial</b></a>
1355    documentation.
1356  </P>  </P>
1357    <br><b>
1358    The string to be matched by <b>pcre_exec()</b>
1359    </b><br>
1360  <P>  <P>
1361  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
1362  <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
1363  <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
1364  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
1365  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
1366  </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.  
1367  </P>  </P>
1368  <P>  <P>
1369  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 1371  same subject by calling <b>pcre_exec()</
1371  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
1372  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
1373  lookbehind. For example, consider the pattern  lookbehind. For example, consider the pattern
 </P>  
 <P>  
1374  <pre>  <pre>
1375    \Biss\B    \Biss\B
1376  </PRE>  </pre>
 </P>  
 <P>  
1377  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
1378  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
1379  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 1386  behind the starting point to discover th
1386  </P>  </P>
1387  <P>  <P>
1388  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
1389  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
1390  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.
1391  </P>  </P>
1392    <br><b>
1393    How <b>pcre_exec()</b> returns captured substrings
1394    </b><br>
1395  <P>  <P>
1396  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
1397  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 1403  kinds of parenthesized subpattern that d
1403  <P>  <P>
1404  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
1405  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
1406  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>:
1407  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.  
1408  </P>  </P>
1409  <P>  <P>
1410  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,
1411  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
1412    used as workspace by <b>pcre_exec()</b> while matching capturing subpatterns,
1413    and is not available for passing back information. The length passed in
1414    <i>ovecsize</i> should always be a multiple of three. If it is not, it is
1415    rounded down.
1416    </P>
1417    <P>
1418    When a match is successful, information about captured substrings is returned
1419    in pairs of integers, starting at the beginning of <i>ovector</i>, and
1420  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
1421  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
1422  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
1423  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
1424  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
1425  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>
1426  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
1427  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
1428  just the first pair of offsets has been set.  capturing subpatterns, the return value from a successful match is 1,
1429  </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.  
1430  </P>  </P>
1431  <P>  <P>
1432  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
1433  string that it matched that gets returned.  string that it matched that is returned.
1434  </P>  </P>
1435  <P>  <P>
1436  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
1437  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
1438  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
1439  <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
1440  <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
1441  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
1442  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
1443  to supply an <i>ovector</i>.  advisable to supply an <i>ovector</i>.
1444  </P>  </P>
1445  <P>  <P>
1446  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
1447  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1448  <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
1449  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.
1450  </P>  </P>
1451  <P>  <P>
1452  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
1453  defined in the header file:  the subject when subpattern <i>n</i> has not been used at all. For example, if
1454    the string "abc" is matched against the pattern (a|(z))(bc) the return from the
1455    function is 4, and subpatterns 1 and 3 are matched, but 2 is not. When this
1456    happens, both values in the offset pairs corresponding to unused subpatterns
1457    are set to -1.
1458  </P>  </P>
1459  <P>  <P>
1460  <pre>  Offset values that correspond to unused subpatterns at the end of the
1461    PCRE_ERROR_NOMATCH        (-1)  expression are also set to -1. For example, if the string "abc" is matched
1462  </PRE>  against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
1463    return from the function is 2, because the highest used capturing subpattern
1464    number is 1. However, you can refer to the offsets for the second and third
1465    capturing subpatterns if you wish (assuming the vector is large enough, of
1466    course).
1467  </P>  </P>
1468  <P>  <P>
1469  The subject string did not match the pattern.  Some convenience functions are provided for extracting the captured substrings
1470  </P>  as separate strings. These are described below.
1471    <a name="errorlist"></a></P>
1472    <br><b>
1473    Error return values from <b>pcre_exec()</b>
1474    </b><br>
1475  <P>  <P>
1476    If <b>pcre_exec()</b> fails, it returns a negative number. The following are
1477    defined in the header file:
1478    <pre>
1479      PCRE_ERROR_NOMATCH        (-1)
1480    </pre>
1481    The subject string did not match the pattern.
1482  <pre>  <pre>
1483    PCRE_ERROR_NULL           (-2)    PCRE_ERROR_NULL           (-2)
1484  </PRE>  </pre>
 </P>  
 <P>  
1485  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
1486  NULL and <i>ovecsize</i> was not zero.  NULL and <i>ovecsize</i> was not zero.
 </P>  
 <P>  
1487  <pre>  <pre>
1488    PCRE_ERROR_BADOPTION      (-3)    PCRE_ERROR_BADOPTION      (-3)
1489  </PRE>  </pre>
 </P>  
 <P>  
1490  An unrecognized bit was set in the <i>options</i> argument.  An unrecognized bit was set in the <i>options</i> argument.
 </P>  
 <P>  
1491  <pre>  <pre>
1492    PCRE_ERROR_BADMAGIC       (-4)    PCRE_ERROR_BADMAGIC       (-4)
1493  </PRE>  </pre>
 </P>  
 <P>  
1494  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
1495  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
1496  magic number isn't present.  compiled in an environment of one endianness is run in an environment with the
1497  </P>  other endianness. This is the error that PCRE gives when the magic number is
1498  <P>  not present.
1499  <pre>  <pre>
1500    PCRE_ERROR_UNKNOWN_NODE   (-5)    PCRE_ERROR_UNKNOWN_OPCODE (-5)
1501  </PRE>  </pre>
 </P>  
 <P>  
1502  While running the pattern match, an unknown item was encountered in the  While running the pattern match, an unknown item was encountered in the
1503  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
1504  of the compiled pattern.  of the compiled pattern.
 </P>  
 <P>  
1505  <pre>  <pre>
1506    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1507  </PRE>  </pre>
 </P>  
 <P>  
1508  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
1509  <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
1510  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
1511  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
1512  the end of matching.  automatically freed at the end of matching.
 </P>  
 <P>  
1513  <pre>  <pre>
1514    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1515  </PRE>  </pre>
 </P>  
 <P>  
1516  This error is used by the <b>pcre_copy_substring()</b>,  This error is used by the <b>pcre_copy_substring()</b>,
1517  <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
1518  below). It is never returned by <b>pcre_exec()</b>.  below). It is never returned by <b>pcre_exec()</b>.
 </P>  
 <P>  
1519  <pre>  <pre>
1520    PCRE_ERROR_MATCHLIMIT     (-8)    PCRE_ERROR_MATCHLIMIT     (-8)
1521  </PRE>  </pre>
1522  </P>  The backtracking limit, as specified by the <i>match_limit</i> field in a
1523  <P>  <b>pcre_extra</b> structure (or defaulted) was reached. See the description
1524  The recursion and backtracking limit, as specified by the <i>match_limit</i>  above.
1525    <pre>
1526      PCRE_ERROR_CALLOUT        (-9)
1527    </pre>
1528    This error is never generated by <b>pcre_exec()</b> itself. It is provided for
1529    use by callout functions that want to yield a distinctive error code. See the
1530    <a href="pcrecallout.html"><b>pcrecallout</b></a>
1531    documentation for details.
1532    <pre>
1533      PCRE_ERROR_BADUTF8        (-10)
1534    </pre>
1535    A string that contains an invalid UTF-8 byte sequence was passed as a subject.
1536    <pre>
1537      PCRE_ERROR_BADUTF8_OFFSET (-11)
1538    </pre>
1539    The UTF-8 byte sequence that was passed as a subject was valid, but the value
1540    of <i>startoffset</i> did not point to the beginning of a UTF-8 character.
1541    <pre>
1542      PCRE_ERROR_PARTIAL        (-12)
1543    </pre>
1544    The subject string did not match, but it did match partially. See the
1545    <a href="pcrepartial.html"><b>pcrepartial</b></a>
1546    documentation for details of partial matching.
1547    <pre>
1548      PCRE_ERROR_BADPARTIAL     (-13)
1549    </pre>
1550    The PCRE_PARTIAL option was used with a compiled pattern containing items that
1551    are not supported for partial matching. See the
1552    <a href="pcrepartial.html"><b>pcrepartial</b></a>
1553    documentation for details of partial matching.
1554    <pre>
1555      PCRE_ERROR_INTERNAL       (-14)
1556    </pre>
1557    An unexpected internal error has occurred. This error could be caused by a bug
1558    in PCRE or by overwriting of the compiled pattern.
1559    <pre>
1560      PCRE_ERROR_BADCOUNT       (-15)
1561    </pre>
1562    This error is given if the value of the <i>ovecsize</i> argument is negative.
1563    <pre>
1564      PCRE_ERROR_RECURSIONLIMIT (-21)
1565    </pre>
1566    The internal recursion limit, as specified by the <i>match_limit_recursion</i>
1567  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
1568  description above.  description above.
 </P>  
 <P>  
1569  <pre>  <pre>
1570    PCRE_ERROR_CALLOUT        (-9)    PCRE_ERROR_BADNEWLINE     (-23)
1571  </PRE>  </pre>
1572    An invalid combination of PCRE_NEWLINE_<i>xxx</i> options was given.
1573  </P>  </P>
1574  <P>  <P>
1575  This error is never generated by <b>pcre_exec()</b> itself. It is provided for  Error numbers -16 to -20 and -22 are not used by <b>pcre_exec()</b>.
 use by callout functions that want to yield a distinctive error code. See the  
 <b>pcrecallout</b> documentation for details.  
1576  </P>  </P>
1577  <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>
1578  <P>  <P>
1579  <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>
1580  <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 1596  Captured substrings can be accessed dire
1596  <b>pcre_get_substring_list()</b> are provided for extracting captured substrings  <b>pcre_get_substring_list()</b> are provided for extracting captured substrings
1597  as new, separate, zero-terminated strings. These functions identify substrings  as new, separate, zero-terminated strings. These functions identify substrings
1598  by number. The next section describes functions for extracting named  by number. The next section describes functions for extracting named
1599  substrings. A substring that contains a binary zero is correctly extracted and  substrings.
1600  has a further zero added on the end, but the result is not, of course,  </P>
1601  a C string.  <P>
1602    A substring that contains a binary zero is correctly extracted and has a
1603    further zero added on the end, but the result is not, of course, a C string.
1604    However, you can process such a string by referring to the length that is
1605    returned by <b>pcre_copy_substring()</b> and <b>pcre_get_substring()</b>.
1606    Unfortunately, the interface to <b>pcre_get_substring_list()</b> is not adequate
1607    for handling strings containing binary zeros, because the end of the final
1608    string is not independently indicated.
1609  </P>  </P>
1610  <P>  <P>
1611  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:
1612  <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,
1613  <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
1614  <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
1615  captured by the match, including the substring that matched the entire regular  captured by the match, including the substring that matched the entire regular
1616  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
1617  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
1618  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
1619  the vector divided by three.  number of elements in the vector divided by three.
1620  </P>  </P>
1621  <P>  <P>
1622  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>
1623  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
1624  value of zero extracts the substring that matched the entire pattern, while  value of zero extracts the substring that matched the entire pattern, whereas
1625  higher values extract the captured substrings. For <b>pcre_copy_substring()</b>,  higher values extract the captured substrings. For <b>pcre_copy_substring()</b>,
1626  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
1627  <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
1628  obtained via <b>pcre_malloc</b>, and its address is returned via  obtained via <b>pcre_malloc</b>, and its address is returned via
1629  <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
1630  including the terminating zero, or one of  including the terminating zero, or one of these error codes:
 </P>  
 <P>  
1631  <pre>  <pre>
1632    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1633  </PRE>  </pre>
 </P>  
 <P>  
1634  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
1635  memory failed for <b>pcre_get_substring()</b>.  memory failed for <b>pcre_get_substring()</b>.
 </P>  
 <P>  
1636  <pre>  <pre>
1637    PCRE_ERROR_NOSUBSTRING    (-7)    PCRE_ERROR_NOSUBSTRING    (-7)
1638  </PRE>  </pre>
 </P>  
 <P>  
1639  There is no substring whose number is <i>stringnumber</i>.  There is no substring whose number is <i>stringnumber</i>.
1640  </P>  </P>
1641  <P>  <P>
1642  The <b>pcre_get_substring_list()</b> function extracts all available substrings  The <b>pcre_get_substring_list()</b> function extracts all available substrings
1643  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
1644  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
1645  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
1646  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
1647  function is zero if all went well, or  function is zero if all went well, or the error code
 </P>  
 <P>  
1648  <pre>  <pre>
1649    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1650  </PRE>  </pre>
 </P>  
 <P>  
1651  if the attempt to get the memory block failed.  if the attempt to get the memory block failed.
1652  </P>  </P>
1653  <P>  <P>
# Line 1202  a previous call of <b>pcre_get_substring Line 1665  a previous call of <b>pcre_get_substring
1665  <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
1666  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
1667  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
1668  linked via a special interface to another programming language which cannot use  linked via a special interface to another programming language that cannot use
1669  <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
1670  provided.  provided.
1671  </P>  </P>
1672  <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>
1673    <P>
1674    <b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b>
1675    <b>const char *<i>name</i>);</b>
1676    </P>
1677  <P>  <P>
1678  <b>int pcre_copy_named_substring(const pcre *<i>code</i>,</b>  <b>int pcre_copy_named_substring(const pcre *<i>code</i>,</b>
1679  <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 1681  provided.
1681  <b>char *<i>buffer</i>, int <i>buffersize</i>);</b>  <b>char *<i>buffer</i>, int <i>buffersize</i>);</b>
1682  </P>  </P>
1683  <P>  <P>
 <b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b>  
 <b>const char *<i>name</i>);</b>  
 </P>  
 <P>  
1684  <b>int pcre_get_named_substring(const pcre *<i>code</i>,</b>  <b>int pcre_get_named_substring(const pcre *<i>code</i>,</b>
1685  <b>const char *<i>subject</i>, int *<i>ovector</i>,</b>  <b>const char *<i>subject</i>, int *<i>ovector</i>,</b>
1686  <b>int <i>stringcount</i>, const char *<i>stringname</i>,</b>  <b>int <i>stringcount</i>, const char *<i>stringname</i>,</b>
1687  <b>const char **<i>stringptr</i>);</b>  <b>const char **<i>stringptr</i>);</b>
1688  </P>  </P>
1689  <P>  <P>
1690  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.
1691  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>  
1692  <pre>  <pre>
1693    ab(?&#60;xxx&#62;\d+)...    (a+)b(?&#60;xxx&#62;\d+)...
1694  </PRE>  </pre>
1695  </P>  the number of the subpattern called "xxx" is 2. If the name is known to be
1696  <P>  unique (PCRE_DUPNAMES was not set), you can find the number from the name by
1697  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
1698  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
1699  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
1700  whole job.  that name.
1701  </P>  </P>
1702  <P>  <P>
1703  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
1704  <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
1705  extract by number, and so are not re-described here. There are just two  two functions that do the whole job.
1706  differences.  </P>
1707    <P>
1708    Most of the arguments of <b>pcre_copy_named_substring()</b> and
1709    <b>pcre_get_named_substring()</b> are the same as those for the similarly named
1710    functions that extract by number. As these are described in the previous
1711    section, they are not re-described here. There are just two differences:
1712  </P>  </P>
1713  <P>  <P>
1714  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 1253  translation table. Line 1718  translation table.
1718  </P>  </P>
1719  <P>  <P>
1720  These functions call <b>pcre_get_stringnumber()</b>, and if it succeeds, they  These functions call <b>pcre_get_stringnumber()</b>, and if it succeeds, they
1721  then call <i>pcre_copy_substring()</i> or <i>pcre_get_substring()</i>, as  then call <b>pcre_copy_substring()</b> or <b>pcre_get_substring()</b>, as
1722  appropriate.  appropriate. <b>NOTE:</b> If PCRE_DUPNAMES is set and there are duplicate names,
1723    the behaviour may not be what you want (see the next section).
1724    </P>
1725    <br><a name="SEC17" href="#TOC1">DUPLICATE SUBPATTERN NAMES</a><br>
1726    <P>
1727    <b>int pcre_get_stringtable_entries(const pcre *<i>code</i>,</b>
1728    <b>const char *<i>name</i>, char **<i>first</i>, char **<i>last</i>);</b>
1729    </P>
1730    <P>
1731    When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
1732    are not required to be unique. Normally, patterns with duplicate names are such
1733    that in any one match, only one of the named subpatterns participates. An
1734    example is shown in the
1735    <a href="pcrepattern.html"><b>pcrepattern</b></a>
1736    documentation.
1737    </P>
1738    <P>
1739    When duplicates are present, <b>pcre_copy_named_substring()</b> and
1740    <b>pcre_get_named_substring()</b> return the first substring corresponding to
1741    the given name that is set. If none are set, PCRE_ERROR_NOSUBSTRING (-7) is
1742    returned; no data is returned. The <b>pcre_get_stringnumber()</b> function
1743    returns one of the numbers that are associated with the name, but it is not
1744    defined which it is.
1745    </P>
1746    <P>
1747    If you want to get full details of all captured substrings for a given name,
1748    you must use the <b>pcre_get_stringtable_entries()</b> function. The first
1749    argument is the compiled pattern, and the second is the name. The third and
1750    fourth are pointers to variables which are updated by the function. After it
1751    has run, they point to the first and last entries in the name-to-number table
1752    for the given name. The function itself returns the length of each entry, or
1753    PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
1754    described above in the section entitled <i>Information about a pattern</i>.
1755    Given all the relevant entries for the name, you can extract each of their
1756    numbers, and hence the captured data, if any.
1757    </P>
1758    <br><a name="SEC18" href="#TOC1">FINDING ALL POSSIBLE MATCHES</a><br>
1759    <P>
1760    The traditional matching function uses a similar algorithm to Perl, which stops
1761    when it finds the first match, starting at a given point in the subject. If you
1762    want to find all possible matches, or the longest possible match, consider
1763    using the alternative matching function (see below) instead. If you cannot use
1764    the alternative function, but still need to find all possible matches, you
1765    can kludge it up by making use of the callout facility, which is described in
1766    the
1767    <a href="pcrecallout.html"><b>pcrecallout</b></a>
1768    documentation.
1769    </P>
1770    <P>
1771    What you have to do is to insert a callout right at the end of the pattern.
1772    When your callout function is called, extract and save the current matched
1773    substring. Then return 1, which forces <b>pcre_exec()</b> to backtrack and try
1774    other alternatives. Ultimately, when it runs out of matches, <b>pcre_exec()</b>
1775    will yield PCRE_ERROR_NOMATCH.
1776    <a name="dfamatch"></a></P>
1777    <br><a name="SEC19" href="#TOC1">MATCHING A PATTERN: THE ALTERNATIVE FUNCTION</a><br>
1778    <P>
1779    <b>int pcre_dfa_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
1780    <b>const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
1781    <b>int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b>
1782    <b>int *<i>workspace</i>, int <i>wscount</i>);</b>
1783    </P>
1784    <P>
1785    The function <b>pcre_dfa_exec()</b> is called to match a subject string against
1786    a compiled pattern, using a matching algorithm that scans the subject string
1787    just once, and does not backtrack. This has different characteristics to the
1788    normal algorithm, and is not compatible with Perl. Some of the features of PCRE
1789    patterns are not supported. Nevertheless, there are times when this kind of
1790    matching can be useful. For a discussion of the two matching algorithms, see
1791    the
1792    <a href="pcrematching.html"><b>pcrematching</b></a>
1793    documentation.
1794    </P>
1795    <P>
1796    The arguments for the <b>pcre_dfa_exec()</b> function are the same as for
1797    <b>pcre_exec()</b>, plus two extras. The <i>ovector</i> argument is used in a
1798    different way, and this is described below. The other common arguments are used
1799    in the same way as for <b>pcre_exec()</b>, so their description is not repeated
1800    here.
1801    </P>
1802    <P>
1803    The two additional arguments provide workspace for the function. The workspace
1804    vector should contain at least 20 elements. It is used for keeping track of
1805    multiple paths through the pattern tree. More workspace will be needed for
1806    patterns and subjects where there are a lot of potential matches.
1807    </P>
1808    <P>
1809    Here is an example of a simple call to <b>pcre_dfa_exec()</b>:
1810    <pre>
1811      int rc;
1812      int ovector[10];
1813      int wspace[20];
1814      rc = pcre_dfa_exec(
1815        re,             /* result of pcre_compile() */
1816        NULL,           /* we didn't study the pattern */
1817        "some string",  /* the subject string */
1818        11,             /* the length of the subject string */
1819        0,              /* start at offset 0 in the subject */
1820        0,              /* default options */
1821        ovector,        /* vector of integers for substring information */
1822        10,             /* number of elements (NOT size in bytes) */
1823        wspace,         /* working space vector */
1824        20);            /* number of elements (NOT size in bytes) */
1825    </PRE>
1826    </P>
1827    <br><b>
1828    Option bits for <b>pcre_dfa_exec()</b>
1829    </b><br>
1830    <P>
1831    The unused bits of the <i>options</i> argument for <b>pcre_dfa_exec()</b> must be
1832    zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_<i>xxx</i>,
1833    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,
1834    PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last three of these are
1835    the same as for <b>pcre_exec()</b>, so their description is not repeated here.
1836    <pre>
1837      PCRE_PARTIAL
1838    </pre>
1839    This has the same general effect as it does for <b>pcre_exec()</b>, but the
1840    details are slightly different. When PCRE_PARTIAL is set for
1841    <b>pcre_dfa_exec()</b>, the return code PCRE_ERROR_NOMATCH is converted into
1842    PCRE_ERROR_PARTIAL if the end of the subject is reached, there have been no
1843    complete matches, but there is still at least one matching possibility. The
1844    portion of the string that provided the partial match is set as the first
1845    matching string.
1846    <pre>
1847      PCRE_DFA_SHORTEST
1848    </pre>
1849    Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as
1850    soon as it has found one match. Because of the way the alternative algorithm
1851    works, this is necessarily the shortest possible match at the first possible
1852    matching point in the subject string.
1853    <pre>
1854      PCRE_DFA_RESTART
1855    </pre>
1856    When <b>pcre_dfa_exec()</b> is called with the PCRE_PARTIAL option, and returns
1857    a partial match, it is possible to call it again, with additional subject
1858    characters, and have it continue with the same match. The PCRE_DFA_RESTART
1859    option requests this action; when it is set, the <i>workspace</i> and
1860    <i>wscount</i> options must reference the same vector as before because data
1861    about the match so far is left in them after a partial match. There is more
1862    discussion of this facility in the
1863    <a href="pcrepartial.html"><b>pcrepartial</b></a>
1864    documentation.
1865    </P>
1866    <br><b>
1867    Successful returns from <b>pcre_dfa_exec()</b>
1868    </b><br>
1869    <P>
1870    When <b>pcre_dfa_exec()</b> succeeds, it may have matched more than one
1871    substring in the subject. Note, however, that all the matches from one run of
1872    the function start at the same point in the subject. The shorter matches are
1873    all initial substrings of the longer matches. For example, if the pattern
1874    <pre>
1875      &#60;.*&#62;
1876    </pre>
1877    is matched against the string
1878    <pre>
1879      This is &#60;something&#62; &#60;something else&#62; &#60;something further&#62; no more
1880    </pre>
1881    the three matched strings are
1882    <pre>
1883      &#60;something&#62;
1884      &#60;something&#62; &#60;something else&#62;
1885      &#60;something&#62; &#60;something else&#62; &#60;something further&#62;
1886    </pre>
1887    On success, the yield of the function is a number greater than zero, which is
1888    the number of matched substrings. The substrings themselves are returned in
1889    <i>ovector</i>. Each string uses two elements; the first is the offset to the
1890    start, and the second is the offset to the end. In fact, all the strings have
1891    the same start offset. (Space could have been saved by giving this only once,
1892    but it was decided to retain some compatibility with the way <b>pcre_exec()</b>
1893    returns data, even though the meaning of the strings is different.)
1894    </P>
1895    <P>
1896    The strings are returned in reverse order of length; that is, the longest
1897    matching string is given first. If there were too many matches to fit into
1898    <i>ovector</i>, the yield of the function is zero, and the vector is filled with
1899    the longest matches.
1900    </P>
1901    <br><b>
1902    Error returns from <b>pcre_dfa_exec()</b>
1903    </b><br>
1904    <P>
1905    The <b>pcre_dfa_exec()</b> function returns a negative number when it fails.
1906    Many of the errors are the same as for <b>pcre_exec()</b>, and these are
1907    described
1908    <a href="#errorlist">above.</a>
1909    There are in addition the following errors that are specific to
1910    <b>pcre_dfa_exec()</b>:
1911    <pre>
1912      PCRE_ERROR_DFA_UITEM      (-16)
1913    </pre>
1914    This return is given if <b>pcre_dfa_exec()</b> encounters an item in the pattern
1915    that it does not support, for instance, the use of \C or a back reference.
1916    <pre>
1917      PCRE_ERROR_DFA_UCOND      (-17)
1918    </pre>
1919    This return is given if <b>pcre_dfa_exec()</b> encounters a condition item that
1920    uses a back reference for the condition, or a test for recursion in a specific
1921    group. These are not supported.
1922    <pre>
1923      PCRE_ERROR_DFA_UMLIMIT    (-18)
1924    </pre>
1925    This return is given if <b>pcre_dfa_exec()</b> is called with an <i>extra</i>
1926    block that contains a setting of the <i>match_limit</i> field. This is not
1927    supported (it is meaningless).
1928    <pre>
1929      PCRE_ERROR_DFA_WSSIZE     (-19)
1930    </pre>
1931    This return is given if <b>pcre_dfa_exec()</b> runs out of space in the
1932    <i>workspace</i> vector.
1933    <pre>
1934      PCRE_ERROR_DFA_RECURSE    (-20)
1935    </pre>
1936    When a recursive subpattern is processed, the matching function calls itself
1937    recursively, using private vectors for <i>ovector</i> and <i>workspace</i>. This
1938    error is given if the output vector is not large enough. This should be
1939    extremely rare, as a vector of size 1000 is used.
1940    </P>
1941    <br><a name="SEC20" href="#TOC1">SEE ALSO</a><br>
1942    <P>
1943    <b>pcrebuild</b>(3), <b>pcrecallout</b>(3), <b>pcrecpp(3)</b>(3),
1944    <b>pcrematching</b>(3), <b>pcrepartial</b>(3), <b>pcreposix</b>(3),
1945    <b>pcreprecompile</b>(3), <b>pcresample</b>(3), <b>pcrestack</b>(3).
1946  </P>  </P>
1947    <br><a name="SEC21" href="#TOC1">AUTHOR</a><br>
1948  <P>  <P>
1949  Last updated: 03 February 2003  Philip Hazel
1950    <br>
1951    University Computing Service
1952    <br>
1953    Cambridge CB2 3QH, England.
1954    <br>
1955    </P>
1956    <br><a name="SEC22" href="#TOC1">REVISION</a><br>
1957    <P>
1958    Last updated: 26 December 2007
1959    <br>
1960    Copyright &copy; 1997-2007 University of Cambridge.
1961  <br>  <br>
1962  Copyright &copy; 1997-2003 University of Cambridge.  <p>
1963    Return to the <a href="index.html">PCRE index page</a>.
1964    </p>

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