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revision 75 by nigel, Sat Feb 24 21:40:37 2007 UTC revision 77 by nigel, Sat Feb 24 21:40:45 2007 UTC
# Line 19  man page, in case the conversion went wr Line 19  man page, in case the conversion went wr
19  <li><a name="TOC4" href="#SEC4">SAVING PRECOMPILED PATTERNS FOR LATER USE</a>  <li><a name="TOC4" href="#SEC4">SAVING PRECOMPILED PATTERNS FOR LATER USE</a>
20  <li><a name="TOC5" href="#SEC5">CHECKING BUILD-TIME OPTIONS</a>  <li><a name="TOC5" href="#SEC5">CHECKING BUILD-TIME OPTIONS</a>
21  <li><a name="TOC6" href="#SEC6">COMPILING A PATTERN</a>  <li><a name="TOC6" href="#SEC6">COMPILING A PATTERN</a>
22  <li><a name="TOC7" href="#SEC7">STUDYING A PATTERN</a>  <li><a name="TOC7" href="#SEC7">COMPILATION ERROR CODES</a>
23  <li><a name="TOC8" href="#SEC8">LOCALE SUPPORT</a>  <li><a name="TOC8" href="#SEC8">STUDYING A PATTERN</a>
24  <li><a name="TOC9" href="#SEC9">INFORMATION ABOUT A PATTERN</a>  <li><a name="TOC9" href="#SEC9">LOCALE SUPPORT</a>
25  <li><a name="TOC10" href="#SEC10">OBSOLETE INFO FUNCTION</a>  <li><a name="TOC10" href="#SEC10">INFORMATION ABOUT A PATTERN</a>
26  <li><a name="TOC11" href="#SEC11">MATCHING A PATTERN</a>  <li><a name="TOC11" href="#SEC11">OBSOLETE INFO FUNCTION</a>
27  <li><a name="TOC12" href="#SEC12">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a>  <li><a name="TOC12" href="#SEC12">REFERENCE COUNTS</a>
28  <li><a name="TOC13" href="#SEC13">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a>  <li><a name="TOC13" href="#SEC13">MATCHING A PATTERN: THE TRADITIONAL FUNCTION</a>
29    <li><a name="TOC14" href="#SEC14">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a>
30    <li><a name="TOC15" href="#SEC15">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a>
31    <li><a name="TOC16" href="#SEC16">FINDING ALL POSSIBLE MATCHES</a>
32    <li><a name="TOC17" href="#SEC17">MATCHING A PATTERN: THE ALTERNATIVE FUNCTION</a>
33  </ul>  </ul>
34  <br><a name="SEC1" href="#TOC1">PCRE NATIVE API</a><br>  <br><a name="SEC1" href="#TOC1">PCRE NATIVE API</a><br>
35  <P>  <P>
# Line 37  man page, in case the conversion went wr Line 41  man page, in case the conversion went wr
41  <b>const unsigned char *<i>tableptr</i>);</b>  <b>const unsigned char *<i>tableptr</i>);</b>
42  </P>  </P>
43  <P>  <P>
44    <b>pcre *pcre_compile2(const char *<i>pattern</i>, int <i>options</i>,</b>
45    <b>int *<i>errorcodeptr</i>,</b>
46    <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
47    <b>const unsigned char *<i>tableptr</i>);</b>
48    </P>
49    <P>
50  <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>
51  <b>const char **<i>errptr</i>);</b>  <b>const char **<i>errptr</i>);</b>
52  </P>  </P>
# Line 46  man page, in case the conversion went wr Line 56  man page, in case the conversion went wr
56  <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>
57  </P>  </P>
58  <P>  <P>
59    <b>int pcre_dfa_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
60    <b>const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
61    <b>int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b>
62    <b>int *<i>workspace</i>, int <i>wscount</i>);</b>
63    </P>
64    <P>
65  <b>int pcre_copy_named_substring(const pcre *<i>code</i>,</b>  <b>int pcre_copy_named_substring(const pcre *<i>code</i>,</b>
66  <b>const char *<i>subject</i>, int *<i>ovector</i>,</b>  <b>const char *<i>subject</i>, int *<i>ovector</i>,</b>
67  <b>int <i>stringcount</i>, const char *<i>stringname</i>,</b>  <b>int <i>stringcount</i>, const char *<i>stringname</i>,</b>
# Line 93  man page, in case the conversion went wr Line 109  man page, in case the conversion went wr
109  <b>*<i>firstcharptr</i>);</b>  <b>*<i>firstcharptr</i>);</b>
110  </P>  </P>
111  <P>  <P>
112    <b>int pcre_refcount(pcre *<i>code</i>, int <i>adjust</i>);</b>
113    </P>
114    <P>
115  <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>
116  </P>  </P>
117  <P>  <P>
# Line 115  man page, in case the conversion went wr Line 134  man page, in case the conversion went wr
134  </P>  </P>
135  <br><a name="SEC2" href="#TOC1">PCRE API OVERVIEW</a><br>  <br><a name="SEC2" href="#TOC1">PCRE API OVERVIEW</a><br>
136  <P>  <P>
137  PCRE has its own native API, which is described in this document. There is also  PCRE has its own native API, which is described in this document. There is
138  a set of wrapper functions that correspond to the POSIX regular expression API.  also a set of wrapper functions that correspond to the POSIX regular expression
139  These are described in the  API. These are described in the
140  <a href="pcreposix.html"><b>pcreposix</b></a>  <a href="pcreposix.html"><b>pcreposix</b></a>
141  documentation.  documentation. Both of these APIs define a set of C function calls. A C++
142    wrapper is distributed with PCRE. It is documented in the
143    <a href="pcrecpp.html"><b>pcrecpp</b></a>
144    page.
145  </P>  </P>
146  <P>  <P>
147  The native API function prototypes are defined in the header file <b>pcre.h</b>,  The native API C function prototypes are defined in the header file
148  and on Unix systems the library itself is called <b>libpcre</b>. It can  <b>pcre.h</b>, and on Unix systems the library itself is called <b>libpcre</b>.
149  normally be accessed by adding <b>-lpcre</b> to the command for linking an  It can normally be accessed by adding <b>-lpcre</b> to the command for linking
150  application that uses PCRE. The header file defines the macros PCRE_MAJOR and  an application that uses PCRE. The header file defines the macros PCRE_MAJOR
151  PCRE_MINOR to contain the major and minor release numbers for the library.  and PCRE_MINOR to contain the major and minor release numbers for the library.
152  Applications can use these to include support for different releases of PCRE.  Applications can use these to include support for different releases of PCRE.
153  </P>  </P>
154  <P>  <P>
155  The functions <b>pcre_compile()</b>, <b>pcre_study()</b>, and <b>pcre_exec()</b>  The functions <b>pcre_compile()</b>, <b>pcre_compile2()</b>, <b>pcre_study()</b>,
156  are used for compiling and matching regular expressions. A sample program that  and <b>pcre_exec()</b> are used for compiling and matching regular expressions
157  demonstrates the simplest way of using them is provided in the file called  in a Perl-compatible manner. A sample program that demonstrates the simplest
158  <i>pcredemo.c</i> in the source distribution. The  way of using them is provided in the file called <i>pcredemo.c</i> in the source
159    distribution. The
160  <a href="pcresample.html"><b>pcresample</b></a>  <a href="pcresample.html"><b>pcresample</b></a>
161  documentation describes how to run it.  documentation describes how to run it.
162  </P>  </P>
163  <P>  <P>
164    A second matching function, <b>pcre_dfa_exec()</b>, which is not
165    Perl-compatible, is also provided. This uses a different algorithm for the
166    matching. This allows it to find all possible matches (at a given point in the
167    subject), not just one. However, this algorithm does not return captured
168    substrings. A description of the two matching algorithms and their advantages
169    and disadvantages is given in the
170    <a href="pcrematching.html"><b>pcrematching</b></a>
171    documentation.
172    </P>
173    <P>
174  In addition to the main compiling and matching functions, there are convenience  In addition to the main compiling and matching functions, there are convenience
175  functions for extracting captured substrings from a matched subject string.  functions for extracting captured substrings from a subject string that is
176  They are:  matched by <b>pcre_exec()</b>. They are:
177  <pre>  <pre>
178    <b>pcre_copy_substring()</b>    <b>pcre_copy_substring()</b>
179    <b>pcre_copy_named_substring()</b>    <b>pcre_copy_named_substring()</b>
# Line 154  provided, to free the memory used for ex Line 187  provided, to free the memory used for ex
187  </P>  </P>
188  <P>  <P>
189  The function <b>pcre_maketables()</b> is used to build a set of character tables  The function <b>pcre_maketables()</b> is used to build a set of character tables
190  in the current locale for passing to <b>pcre_compile()</b> or <b>pcre_exec()</b>.  in the current locale for passing to <b>pcre_compile()</b>, <b>pcre_exec()</b>,
191  This is an optional facility that is provided for specialist use. Most  or <b>pcre_dfa_exec()</b>. This is an optional facility that is provided for
192  commonly, no special tables are passed, in which case internal tables that are  specialist use. Most commonly, no special tables are passed, in which case
193  generated when PCRE is built are used.  internal tables that are generated when PCRE is built are used.
194  </P>  </P>
195  <P>  <P>
196  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
# Line 167  The function pcre_version() retur Line 200  The function pcre_version() retur
200  version of PCRE and its date of release.  version of PCRE and its date of release.
201  </P>  </P>
202  <P>  <P>
203    The function <b>pcre_refcount()</b> maintains a reference count in a data block
204    containing a compiled pattern. This is provided for the benefit of
205    object-oriented applications.
206    </P>
207    <P>
208  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
209  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,
210  respectively. PCRE calls the memory management functions via these variables,  respectively. PCRE calls the memory management functions via these variables,
# Line 177  should be done before calling any PCRE f Line 215  should be done before calling any PCRE f
215  The global variables <b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> are also  The global variables <b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> are also
216  indirections to memory management functions. These special functions are used  indirections to memory management functions. These special functions are used
217  only when PCRE is compiled to use the heap for remembering data, instead of  only when PCRE is compiled to use the heap for remembering data, instead of
218  recursive function calls. This is a non-standard way of building PCRE, for use  recursive function calls, when running the <b>pcre_exec()</b> function. This is
219  in environments that have limited stacks. Because of the greater use of memory  a non-standard way of building PCRE, for use in environments that have limited
220  management, it runs more slowly. Separate functions are provided so that  stacks. Because of the greater use of memory management, it runs more slowly.
221  special-purpose external code can be used for this case. When used, these  Separate functions are provided so that special-purpose external code can be
222  functions are always called in a stack-like manner (last obtained, first  used for this case. When used, these functions are always called in a
223  freed), and always for memory blocks of the same size.  stack-like manner (last obtained, first freed), and always for memory blocks of
224    the same size.
225  </P>  </P>
226  <P>  <P>
227  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
# Line 265  details are given with pcre_exec() Line 304  details are given with pcre_exec()
304  <pre>  <pre>
305    PCRE_CONFIG_STACKRECURSE    PCRE_CONFIG_STACKRECURSE
306  </pre>  </pre>
307  The output is an integer that is set to one if internal recursion is  The output is an integer that is set to one if internal recursion when running
308  implemented by recursive function calls that use the stack to remember their  <b>pcre_exec()</b> is implemented by recursive function calls that use the stack
309  state. This is the usual way that PCRE is compiled. The output is zero if PCRE  to remember their state. This is the usual way that PCRE is compiled. The
310  was compiled to use blocks of data on the heap instead of recursive function  output is zero if PCRE was compiled to use blocks of data on the heap instead
311  calls. In this case, <b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> are  of recursive function calls. In this case, <b>pcre_stack_malloc</b> and
312  called to manage memory blocks on the heap, thus avoiding the use of the stack.  <b>pcre_stack_free</b> are called to manage memory blocks on the heap, thus
313    avoiding the use of the stack.
314  </P>  </P>
315  <br><a name="SEC6" href="#TOC1">COMPILING A PATTERN</a><br>  <br><a name="SEC6" href="#TOC1">COMPILING A PATTERN</a><br>
316  <P>  <P>
317  <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>
318  <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b>  <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
319  <b>const unsigned char *<i>tableptr</i>);</b>  <b>const unsigned char *<i>tableptr</i>);</b>
320    <b>pcre *pcre_compile2(const char *<i>pattern</i>, int <i>options</i>,</b>
321    <b>int *<i>errorcodeptr</i>,</b>
322    <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
323    <b>const unsigned char *<i>tableptr</i>);</b>
324    </P>
325    <P>
326    Either of the functions <b>pcre_compile()</b> or <b>pcre_compile2()</b> can be
327    called to compile a pattern into an internal form. The only difference between
328    the two interfaces is that <b>pcre_compile2()</b> has an additional argument,
329    <i>errorcodeptr</i>, via which a numerical error code can be returned.
330  </P>  </P>
331  <P>  <P>
332  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
333  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
334  is passed in the <i>pattern</i> argument. A pointer to a single block of memory  via <b>pcre_malloc</b> is returned. This contains the compiled code and related
335  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
336  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
337  this is a typedef for a structure whose contents are not externally defined. It  caller to free the memory when it is no longer required.
 is up to the caller to free the memory when it is no longer required.  
338  </P>  </P>
339  <P>  <P>
340  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
# Line 314  the error was discovered is placed in th Line 363  the error was discovered is placed in th
363  <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.
364  </P>  </P>
365  <P>  <P>
366    If <b>pcre_compile2()</b> is used instead of <b>pcre_compile()</b>, and the
367    <i>errorcodeptr</i> argument is not NULL, a non-zero error code number is
368    returned via this argument in the event of an error. This is in addition to the
369    textual error message. Error codes and messages are listed below.
370    </P>
371    <P>
372  If the final argument, <i>tableptr</i>, is NULL, PCRE uses a default set of  If the final argument, <i>tableptr</i>, is NULL, PCRE uses a default set of
373  character tables that are built when PCRE is compiled, using the default C  character tables that are built when PCRE is compiled, using the default C
374  locale. Otherwise, <i>tableptr</i> must be an address that is the result of a  locale. Otherwise, <i>tableptr</i> must be an address that is the result of a
# Line 357  documentation. Line 412  documentation.
412  </pre>  </pre>
413  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
414  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
415  pattern by a (?i) option setting. When running in UTF-8 mode, case support for  pattern by a (?i) option setting. In UTF-8 mode, PCRE always understands the
416  high-valued characters is available only when PCRE is built with Unicode  concept of case for characters whose values are less than 128, so caseless
417  character property support.  matching is always possible. For characters with higher values, the concept of
418    case is supported if PCRE is compiled with Unicode property support, but not
419    otherwise. If you want to use caseless matching for characters 128 and above,
420    you must ensure that PCRE is compiled with Unicode property support as well as
421    with UTF-8 support.
422  <pre>  <pre>
423    PCRE_DOLLAR_ENDONLY    PCRE_DOLLAR_ENDONLY
424  </pre>  </pre>
# Line 404  special meaning is treated as a literal. Line 463  special meaning is treated as a literal.
463  controlled by this option. It can also be set by a (?X) option setting within a  controlled by this option. It can also be set by a (?X) option setting within a
464  pattern.  pattern.
465  <pre>  <pre>
466      PCRE_FIRSTLINE
467    </pre>
468    If this option is set, an unanchored pattern is required to match before or at
469    the first newline character in the subject string, though the matched text may
470    continue over the newline.
471    <pre>
472    PCRE_MULTILINE    PCRE_MULTILINE
473  </pre>  </pre>
474  By default, PCRE treats the subject string as consisting of a single line of  By default, PCRE treats the subject string as consisting of a single line of
# Line 455  automatically checked. If an invalid UTF Line 520  automatically checked. If an invalid UTF
520  valid, and you want to skip this check for performance reasons, you can set the  valid, and you want to skip this check for performance reasons, you can set the
521  PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid  PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid
522  UTF-8 string as a pattern is undefined. It may cause your program to crash.  UTF-8 string as a pattern is undefined. It may cause your program to crash.
523  Note that this option can also be passed to <b>pcre_exec()</b>, to suppress the  Note that this option can also be passed to <b>pcre_exec()</b> and
524  UTF-8 validity checking of subject strings.  <b>pcre_dfa_exec()</b>, to suppress the UTF-8 validity checking of subject
525    strings.
526    </P>
527    <br><a name="SEC7" href="#TOC1">COMPILATION ERROR CODES</a><br>
528    <P>
529    The following table lists the error codes than may be returned by
530    <b>pcre_compile2()</b>, along with the error messages that may be returned by
531    both compiling functions.
532    <pre>
533       0  no error
534       1  \ at end of pattern
535       2  \c at end of pattern
536       3  unrecognized character follows \
537       4  numbers out of order in {} quantifier
538       5  number too big in {} quantifier
539       6  missing terminating ] for character class
540       7  invalid escape sequence in character class
541       8  range out of order in character class
542       9  nothing to repeat
543      10  operand of unlimited repeat could match the empty string
544      11  internal error: unexpected repeat
545      12  unrecognized character after (?
546      13  POSIX named classes are supported only within a class
547      14  missing )
548      15  reference to non-existent subpattern
549      16  erroffset passed as NULL
550      17  unknown option bit(s) set
551      18  missing ) after comment
552      19  parentheses nested too deeply
553      20  regular expression too large
554      21  failed to get memory
555      22  unmatched parentheses
556      23  internal error: code overflow
557      24  unrecognized character after (?&#60;
558      25  lookbehind assertion is not fixed length
559      26  malformed number after (?(
560      27  conditional group contains more than two branches
561      28  assertion expected after (?(
562      29  (?R or (?digits must be followed by )
563      30  unknown POSIX class name
564      31  POSIX collating elements are not supported
565      32  this version of PCRE is not compiled with PCRE_UTF8 support
566      33  spare error
567      34  character value in \x{...} sequence is too large
568      35  invalid condition (?(0)
569      36  \C not allowed in lookbehind assertion
570      37  PCRE does not support \L, \l, \N, \U, or \u
571      38  number after (?C is &#62; 255
572      39  closing ) for (?C expected
573      40  recursive call could loop indefinitely
574      41  unrecognized character after (?P
575      42  syntax error after (?P
576      43  two named groups have the same name
577      44  invalid UTF-8 string
578      45  support for \P, \p, and \X has not been compiled
579      46  malformed \P or \p sequence
580      47  unknown property name after \P or \p
581    </PRE>
582  </P>  </P>
583  <br><a name="SEC7" href="#TOC1">STUDYING A PATTERN</a><br>  <br><a name="SEC8" href="#TOC1">STUDYING A PATTERN</a><br>
584  <P>  <P>
585  <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>
586  <b>const char **<i>errptr</i>);</b>  <b>const char **<i>errptr</i>);</b>
587  </P>  </P>
588  <P>  <P>
# Line 481  described Line 603  described
603  in the section on matching a pattern.  in the section on matching a pattern.
604  </P>  </P>
605  <P>  <P>
606  If studying the pattern does not produce any additional information,  If studying the pattern does not produce any additional information
607  <b>pcre_study()</b> returns NULL. In that circumstance, if the calling program  <b>pcre_study()</b> returns NULL. In that circumstance, if the calling program
608  wants to pass any of the other fields to <b>pcre_exec()</b>, it must set up its  wants to pass any of the other fields to <b>pcre_exec()</b>, it must set up its
609  own <b>pcre_extra</b> block.  own <b>pcre_extra</b> block.
# Line 510  At present, studying a pattern is useful Line 632  At present, studying a pattern is useful
632  not have a single fixed starting character. A bitmap of possible starting  not have a single fixed starting character. A bitmap of possible starting
633  bytes is created.  bytes is created.
634  <a name="localesupport"></a></P>  <a name="localesupport"></a></P>
635  <br><a name="SEC8" href="#TOC1">LOCALE SUPPORT</a><br>  <br><a name="SEC9" href="#TOC1">LOCALE SUPPORT</a><br>
636  <P>  <P>
637  PCRE handles caseless matching, and determines whether characters are letters,  PCRE handles caseless matching, and determines whether characters are letters
638  digits, or whatever, by reference to a set of tables, indexed by character  digits, or whatever, by reference to a set of tables, indexed by character
639  value. (When running in UTF-8 mode, this applies only to characters with codes  value. When running in UTF-8 mode, this applies only to characters with codes
640  less than 128. Higher-valued codes never match escapes such as \w or \d, but  less than 128. Higher-valued codes never match escapes such as \w or \d, but
641  can be tested with \p if PCRE is built with Unicode character property  can be tested with \p if PCRE is built with Unicode character property
642  support.)  support.
643  </P>  </P>
644  <P>  <P>
645  An internal set of tables is created in the default C locale when PCRE is  An internal set of tables is created in the default C locale when PCRE is
# Line 558  this facility could be used to match a p Line 680  this facility could be used to match a p
680  one in which it was compiled. Passing table pointers at run time is discussed  one in which it was compiled. Passing table pointers at run time is discussed
681  below in the section on matching a pattern.  below in the section on matching a pattern.
682  </P>  </P>
683  <br><a name="SEC9" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br>  <br><a name="SEC10" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br>
684  <P>  <P>
685  <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>
686  <b>int <i>what</i>, void *<i>where</i>);</b>  <b>int <i>what</i>, void *<i>where</i>);</b>
# Line 607  no back references. Line 729  no back references.
729  Return the number of capturing subpatterns in the pattern. The fourth argument  Return the number of capturing subpatterns in the pattern. The fourth argument
730  should point to an <b>int</b> variable.  should point to an <b>int</b> variable.
731  <pre>  <pre>
732    PCRE_INFO_DEFAULTTABLES    PCRE_INFO_DEFAULT_TABLES
733  </pre>  </pre>
734  Return a pointer to the internal default character tables within PCRE. The  Return a pointer to the internal default character tables within PCRE. The
735  fourth argument should point to an <b>unsigned char *</b> variable. This  fourth argument should point to an <b>unsigned char *</b> variable. This
# Line 729  a pcre_extra block. That is, it i Line 851  a pcre_extra block. That is, it i
851  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
852  <b>size_t</b> variable.  <b>size_t</b> variable.
853  </P>  </P>
854  <br><a name="SEC10" href="#TOC1">OBSOLETE INFO FUNCTION</a><br>  <br><a name="SEC11" href="#TOC1">OBSOLETE INFO FUNCTION</a><br>
855  <P>  <P>
856  <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>
857  <b>*<i>firstcharptr</i>);</b>  <b>*<i>firstcharptr</i>);</b>
# Line 753  If the pattern is not anchored and the < Line 875  If the pattern is not anchored and the <
875  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
876  string (see PCRE_INFO_FIRSTBYTE above).  string (see PCRE_INFO_FIRSTBYTE above).
877  </P>  </P>
878  <br><a name="SEC11" href="#TOC1">MATCHING A PATTERN</a><br>  <br><a name="SEC12" href="#TOC1">REFERENCE COUNTS</a><br>
879    <P>
880    <b>int pcre_refcount(pcre *<i>code</i>, int <i>adjust</i>);</b>
881    </P>
882    <P>
883    The <b>pcre_refcount()</b> function is used to maintain a reference count in the
884    data block that contains a compiled pattern. It is provided for the benefit of
885    applications that operate in an object-oriented manner, where different parts
886    of the application may be using the same compiled pattern, but you want to free
887    the block when they are all done.
888    </P>
889    <P>
890    When a pattern is compiled, the reference count field is initialized to zero.
891    It is changed only by calling this function, whose action is to add the
892    <i>adjust</i> value (which may be positive or negative) to it. The yield of the
893    function is the new value. However, the value of the count is constrained to
894    lie between 0 and 65535, inclusive. If the new value is outside these limits,
895    it is forced to the appropriate limit value.
896    </P>
897    <P>
898    Except when it is zero, the reference count is not correctly preserved if a
899    pattern is compiled on one host and then transferred to a host whose byte-order
900    is different. (This seems a highly unlikely scenario.)
901    </P>
902    <br><a name="SEC13" href="#TOC1">MATCHING A PATTERN: THE TRADITIONAL FUNCTION</a><br>
903  <P>  <P>
904  <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>
905  <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 763  string (see PCRE_INFO_FIRSTBYTE above). Line 909  string (see PCRE_INFO_FIRSTBYTE above).
909  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
910  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
911  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
912  <i>extra</i> argument.  <i>extra</i> argument. This function is the main matching facility of the
913    library, and it operates in a Perl-like manner. For specialist use there is
914    also an alternative matching function, which is described
915    <a href="#dfamatch">below</a>
916    in the section about the <b>pcre_dfa_exec()</b> function.
917  </P>  </P>
918  <P>  <P>
919  In most applications, the pattern will have been compiled (and optionally  In most applications, the pattern will have been compiled (and optionally
# Line 787  Here is an example of a simple call to < Line 937  Here is an example of a simple call to <
937      0,              /* start at offset 0 in the subject */      0,              /* start at offset 0 in the subject */
938      0,              /* default options */      0,              /* default options */
939      ovector,        /* vector of integers for substring information */      ovector,        /* vector of integers for substring information */
940      30);            /* number of elements in the vector (NOT size in bytes) */      30);            /* number of elements (NOT size in bytes) */
941  <a name="extradata"></a></PRE>  <a name="extradata"></a></PRE>
942  </P>  </P>
943  <br><b>  <br><b>
# Line 1046  Note that pcre_info() can be used Line 1196  Note that pcre_info() can be used
1196  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1197  <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
1198  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.
1199  </P>  <a name="errorlist"></a></P>
1200  <br><b>  <br><b>
1201  Return values from <b>pcre_exec()</b>  Return values from <b>pcre_exec()</b>
1202  </b><br>  </b><br>
# Line 1117  A string that contains an invalid UTF-8 Line 1267  A string that contains an invalid UTF-8
1267  The UTF-8 byte sequence that was passed as a subject was valid, but the value  The UTF-8 byte sequence that was passed as a subject was valid, but the value
1268  of <i>startoffset</i> did not point to the beginning of a UTF-8 character.  of <i>startoffset</i> did not point to the beginning of a UTF-8 character.
1269  <pre>  <pre>
1270    PCRE_ERROR_PARTIAL (-12)    PCRE_ERROR_PARTIAL        (-12)
1271  </pre>  </pre>
1272  The subject string did not match, but it did match partially. See the  The subject string did not match, but it did match partially. See the
1273  <a href="pcrepartial.html"><b>pcrepartial</b></a>  <a href="pcrepartial.html"><b>pcrepartial</b></a>
1274  documentation for details of partial matching.  documentation for details of partial matching.
1275  <pre>  <pre>
1276    PCRE_ERROR_BAD_PARTIAL (-13)    PCRE_ERROR_BADPARTIAL     (-13)
1277  </pre>  </pre>
1278  The PCRE_PARTIAL option was used with a compiled pattern containing items that  The PCRE_PARTIAL option was used with a compiled pattern containing items that
1279  are not supported for partial matching. See the  are not supported for partial matching. See the
1280  <a href="pcrepartial.html"><b>pcrepartial</b></a>  <a href="pcrepartial.html"><b>pcrepartial</b></a>
1281  documentation for details of partial matching.  documentation for details of partial matching.
1282  <pre>  <pre>
1283    PCRE_ERROR_INTERNAL (-14)    PCRE_ERROR_INTERNAL       (-14)
1284  </pre>  </pre>
1285  An unexpected internal error has occurred. This error could be caused by a bug  An unexpected internal error has occurred. This error could be caused by a bug
1286  in PCRE or by overwriting of the compiled pattern.  in PCRE or by overwriting of the compiled pattern.
1287  <pre>  <pre>
1288    PCRE_ERROR_BADCOUNT (-15)    PCRE_ERROR_BADCOUNT       (-15)
1289  </pre>  </pre>
1290  This error is given if the value of the <i>ovecsize</i> argument is negative.  This error is given if the value of the <i>ovecsize</i> argument is negative.
1291  </P>  </P>
1292  <br><a name="SEC12" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>  <br><a name="SEC14" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>
1293  <P>  <P>
1294  <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>
1295  <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 1227  linked via a special interface to anothe Line 1377  linked via a special interface to anothe
1377  <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
1378  provided.  provided.
1379  </P>  </P>
1380  <br><a name="SEC13" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a><br>  <br><a name="SEC15" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a><br>
1381  <P>  <P>
1382  <b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b>  <b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b>
1383  <b>const char *<i>name</i>);</b>  <b>const char *<i>name</i>);</b>
# Line 1278  These functions call pcre_get_stringn Line 1428  These functions call pcre_get_stringn
1428  then call <i>pcre_copy_substring()</i> or <i>pcre_get_substring()</i>, as  then call <i>pcre_copy_substring()</i> or <i>pcre_get_substring()</i>, as
1429  appropriate.  appropriate.
1430  </P>  </P>
1431    <br><a name="SEC16" href="#TOC1">FINDING ALL POSSIBLE MATCHES</a><br>
1432    <P>
1433    The traditional matching function uses a similar algorithm to Perl, which stops
1434    when it finds the first match, starting at a given point in the subject. If you
1435    want to find all possible matches, or the longest possible match, consider
1436    using the alternative matching function (see below) instead. If you cannot use
1437    the alternative function, but still need to find all possible matches, you
1438    can kludge it up by making use of the callout facility, which is described in
1439    the
1440    <a href="pcrecallout.html"><b>pcrecallout</b></a>
1441    documentation.
1442    </P>
1443    <P>
1444    What you have to do is to insert a callout right at the end of the pattern.
1445    When your callout function is called, extract and save the current matched
1446    substring. Then return 1, which forces <b>pcre_exec()</b> to backtrack and try
1447    other alternatives. Ultimately, when it runs out of matches, <b>pcre_exec()</b>
1448    will yield PCRE_ERROR_NOMATCH.
1449    <a name="dfamatch"></a></P>
1450    <br><a name="SEC17" href="#TOC1">MATCHING A PATTERN: THE ALTERNATIVE FUNCTION</a><br>
1451    <P>
1452    <b>int pcre_dfa_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
1453    <b>const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
1454    <b>int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b>
1455    <b>int *<i>workspace</i>, int <i>wscount</i>);</b>
1456    </P>
1457    <P>
1458    The function <b>pcre_dfa_exec()</b> is called to match a subject string against
1459    a compiled pattern, using a "DFA" matching algorithm. This has different
1460    characteristics to the normal algorithm, and is not compatible with Perl. Some
1461    of the features of PCRE patterns are not supported. Nevertheless, there are
1462    times when this kind of matching can be useful. For a discussion of the two
1463    matching algorithms, see the
1464    <a href="pcrematching.html"><b>pcrematching</b></a>
1465    documentation.
1466    </P>
1467    <P>
1468    The arguments for the <b>pcre_dfa_exec()</b> function are the same as for
1469    <b>pcre_exec()</b>, plus two extras. The <i>ovector</i> argument is used in a
1470    different way, and this is described below. The other common arguments are used
1471    in the same way as for <b>pcre_exec()</b>, so their description is not repeated
1472    here.
1473    </P>
1474    <P>
1475    The two additional arguments provide workspace for the function. The workspace
1476    vector should contain at least 20 elements. It is used for keeping track of
1477    multiple paths through the pattern tree. More workspace will be needed for
1478    patterns and subjects where there are a lot of possible matches.
1479    </P>
1480    <P>
1481    Here is an example of a simple call to <b>pcre_exec()</b>:
1482    <pre>
1483      int rc;
1484      int ovector[10];
1485      int wspace[20];
1486      rc = pcre_exec(
1487        re,             /* result of pcre_compile() */
1488        NULL,           /* we didn't study the pattern */
1489        "some string",  /* the subject string */
1490        11,             /* the length of the subject string */
1491        0,              /* start at offset 0 in the subject */
1492        0,              /* default options */
1493        ovector,        /* vector of integers for substring information */
1494        10,             /* number of elements (NOT size in bytes) */
1495        wspace,         /* working space vector */
1496        20);            /* number of elements (NOT size in bytes) */
1497    </PRE>
1498    </P>
1499    <br><b>
1500    Option bits for <b>pcre_dfa_exec()</b>
1501    </b><br>
1502    <P>
1503    The unused bits of the <i>options</i> argument for <b>pcre_dfa_exec()</b> must be
1504    zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NOTBOL,
1505    PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,
1506    PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last three of these are
1507    the same as for <b>pcre_exec()</b>, so their description is not repeated here.
1508    <pre>
1509      PCRE_PARTIAL
1510    </pre>
1511    This has the same general effect as it does for <b>pcre_exec()</b>, but the
1512    details are slightly different. When PCRE_PARTIAL is set for
1513    <b>pcre_dfa_exec()</b>, the return code PCRE_ERROR_NOMATCH is converted into
1514    PCRE_ERROR_PARTIAL if the end of the subject is reached, there have been no
1515    complete matches, but there is still at least one matching possibility. The
1516    portion of the string that provided the partial match is set as the first
1517    matching string.
1518    <pre>
1519      PCRE_DFA_SHORTEST
1520    </pre>
1521    Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as
1522    soon as it has found one match. Because of the way the DFA algorithm works,
1523    this is necessarily the shortest possible match at the first possible matching
1524    point in the subject string.
1525    <pre>
1526      PCRE_DFA_RESTART
1527    </pre>
1528    When <b>pcre_dfa_exec()</b> is called with the PCRE_PARTIAL option, and returns
1529    a partial match, it is possible to call it again, with additional subject
1530    characters, and have it continue with the same match. The PCRE_DFA_RESTART
1531    option requests this action; when it is set, the <i>workspace</i> and
1532    <i>wscount</i> options must reference the same vector as before because data
1533    about the match so far is left in them after a partial match. There is more
1534    discussion of this facility in the
1535    <a href="pcrepartial.html"><b>pcrepartial</b></a>
1536    documentation.
1537    </P>
1538    <br><b>
1539    Successful returns from <b>pcre_dfa_exec()</b>
1540    </b><br>
1541    <P>
1542    When <b>pcre_dfa_exec()</b> succeeds, it may have matched more than one
1543    substring in the subject. Note, however, that all the matches from one run of
1544    the function start at the same point in the subject. The shorter matches are
1545    all initial substrings of the longer matches. For example, if the pattern
1546    <pre>
1547      &#60;.*&#62;
1548    </pre>
1549    is matched against the string
1550    <pre>
1551      This is &#60;something&#62; &#60;something else&#62; &#60;something further&#62; no more
1552    </pre>
1553    the three matched strings are
1554    <pre>
1555      &#60;something&#62;
1556      &#60;something&#62; &#60;something else&#62;
1557      &#60;something&#62; &#60;something else&#62; &#60;something further&#62;
1558    </pre>
1559    On success, the yield of the function is a number greater than zero, which is
1560    the number of matched substrings. The substrings themselves are returned in
1561    <i>ovector</i>. Each string uses two elements; the first is the offset to the
1562    start, and the second is the offset to the end. All the strings have the same
1563    start offset. (Space could have been saved by giving this only once, but it was
1564    decided to retain some compatibility with the way <b>pcre_exec()</b> returns
1565    data, even though the meaning of the strings is different.)
1566    </P>
1567    <P>
1568    The strings are returned in reverse order of length; that is, the longest
1569    matching string is given first. If there were too many matches to fit into
1570    <i>ovector</i>, the yield of the function is zero, and the vector is filled with
1571    the longest matches.
1572    </P>
1573    <br><b>
1574    Error returns from <b>pcre_dfa_exec()</b>
1575    </b><br>
1576    <P>
1577    The <b>pcre_dfa_exec()</b> function returns a negative number when it fails.
1578    Many of the errors are the same as for <b>pcre_exec()</b>, and these are
1579    described
1580    <a href="#errorlist">above.</a>
1581    There are in addition the following errors that are specific to
1582    <b>pcre_dfa_exec()</b>:
1583    <pre>
1584      PCRE_ERROR_DFA_UITEM      (-16)
1585    </pre>
1586    This return is given if <b>pcre_dfa_exec()</b> encounters an item in the pattern
1587    that it does not support, for instance, the use of \C or a back reference.
1588    <pre>
1589      PCRE_ERROR_DFA_UCOND      (-17)
1590    </pre>
1591    This return is given if <b>pcre_dfa_exec()</b> encounters a condition item in a
1592    pattern that uses a back reference for the condition. This is not supported.
1593    <pre>
1594      PCRE_ERROR_DFA_UMLIMIT    (-18)
1595    </pre>
1596    This return is given if <b>pcre_dfa_exec()</b> is called with an <i>extra</i>
1597    block that contains a setting of the <i>match_limit</i> field. This is not
1598    supported (it is meaningless).
1599    <pre>
1600      PCRE_ERROR_DFA_WSSIZE     (-19)
1601    </pre>
1602    This return is given if <b>pcre_dfa_exec()</b> runs out of space in the
1603    <i>workspace</i> vector.
1604    <pre>
1605      PCRE_ERROR_DFA_RECURSE    (-20)
1606    </pre>
1607    When a recursive subpattern is processed, the matching function calls itself
1608    recursively, using private vectors for <i>ovector</i> and <i>workspace</i>. This
1609    error is given if the output vector is not large enough. This should be
1610    extremely rare, as a vector of size 1000 is used.
1611    </P>
1612  <P>  <P>
1613  Last updated: 09 September 2004  Last updated: 16 May 2005
1614  <br>  <br>
1615  Copyright &copy; 1997-2004 University of Cambridge.  Copyright &copy; 1997-2005 University of Cambridge.
1616  <p>  <p>
1617  Return to the <a href="index.html">PCRE index page</a>.  Return to the <a href="index.html">PCRE index page</a>.
1618  </p>  </p>

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