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revision 77 by nigel, Sat Feb 24 21:40:45 2007 UTC revision 128 by ph10, Tue Mar 20 11:46:50 2007 UTC
# Line 15  man page, in case the conversion went wr Line 15  man page, in case the conversion went wr
15  <ul>  <ul>
16  <li><a name="TOC1" href="#SEC1">PCRE NATIVE API</a>  <li><a name="TOC1" href="#SEC1">PCRE NATIVE API</a>
17  <li><a name="TOC2" href="#SEC2">PCRE API OVERVIEW</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">SAVING PRECOMPILED PATTERNS FOR LATER USE</a>  <li><a name="TOC4" href="#SEC4">MULTITHREADING</a>
20  <li><a name="TOC5" href="#SEC5">CHECKING BUILD-TIME OPTIONS</a>  <li><a name="TOC5" href="#SEC5">SAVING PRECOMPILED PATTERNS FOR LATER USE</a>
21  <li><a name="TOC6" href="#SEC6">COMPILING A PATTERN</a>  <li><a name="TOC6" href="#SEC6">CHECKING BUILD-TIME OPTIONS</a>
22  <li><a name="TOC7" href="#SEC7">COMPILATION ERROR CODES</a>  <li><a name="TOC7" href="#SEC7">COMPILING A PATTERN</a>
23  <li><a name="TOC8" href="#SEC8">STUDYING A PATTERN</a>  <li><a name="TOC8" href="#SEC8">COMPILATION ERROR CODES</a>
24  <li><a name="TOC9" href="#SEC9">LOCALE SUPPORT</a>  <li><a name="TOC9" href="#SEC9">STUDYING A PATTERN</a>
25  <li><a name="TOC10" href="#SEC10">INFORMATION ABOUT A PATTERN</a>  <li><a name="TOC10" href="#SEC10">LOCALE SUPPORT</a>
26  <li><a name="TOC11" href="#SEC11">OBSOLETE INFO FUNCTION</a>  <li><a name="TOC11" href="#SEC11">INFORMATION ABOUT A PATTERN</a>
27  <li><a name="TOC12" href="#SEC12">REFERENCE COUNTS</a>  <li><a name="TOC12" href="#SEC12">OBSOLETE INFO FUNCTION</a>
28  <li><a name="TOC13" href="#SEC13">MATCHING A PATTERN: THE TRADITIONAL FUNCTION</a>  <li><a name="TOC13" href="#SEC13">REFERENCE COUNTS</a>
29  <li><a name="TOC14" href="#SEC14">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a>  <li><a name="TOC14" href="#SEC14">MATCHING A PATTERN: THE TRADITIONAL FUNCTION</a>
30  <li><a name="TOC15" href="#SEC15">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a>  <li><a name="TOC15" href="#SEC15">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a>
31  <li><a name="TOC16" href="#SEC16">FINDING ALL POSSIBLE MATCHES</a>  <li><a name="TOC16" href="#SEC16">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a>
32  <li><a name="TOC17" href="#SEC17">MATCHING A PATTERN: THE ALTERNATIVE FUNCTION</a>  <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">PCRE NATIVE API</a><br>  <br><a name="SEC1" href="#TOC1">PCRE NATIVE API</a><br>
40  <P>  <P>
# Line 83  man page, in case the conversion went wr Line 88  man page, in case the conversion went wr
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 134  man page, in case the conversion went wr Line 143  man page, in case the conversion went wr
143  </P>  </P>
144  <br><a name="SEC2" href="#TOC1">PCRE API OVERVIEW</a><br>  <br><a name="SEC2" href="#TOC1">PCRE API OVERVIEW</a><br>
145  <P>  <P>
146  PCRE has its own native API, which is described in this document. There is  PCRE has its own native API, which is described in this document. There are
147  also a set of wrapper functions that correspond to the POSIX regular expression  also some wrapper functions that correspond to the POSIX regular expression
148  API. These are described in the  API. These are described in the
149  <a href="pcreposix.html"><b>pcreposix</b></a>  <a href="pcreposix.html"><b>pcreposix</b></a>
150  documentation. Both of these APIs define a set of C function calls. A C++  documentation. Both of these APIs define a set of C function calls. A C++
# Line 163  documentation describes how to run it. Line 172  documentation describes how to run it.
172  <P>  <P>
173  A second matching function, <b>pcre_dfa_exec()</b>, which is not  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  Perl-compatible, is also provided. This uses a different algorithm for the
175  matching. This allows it to find all possible matches (at a given point in the  matching. The alternative algorithm finds all possible matches (at a given
176  subject), not just one. However, this algorithm does not return captured  point in the subject), and scans the subject just once. However, this algorithm
177  substrings. A description of the two matching algorithms and their advantages  does not return captured substrings. A description of the two matching
178  and disadvantages is given in the  algorithms and their advantages and disadvantages is given in the
179  <a href="pcrematching.html"><b>pcrematching</b></a>  <a href="pcrematching.html"><b>pcrematching</b></a>
180  documentation.  documentation.
181  </P>  </P>
# Line 181  matched by <b>pcre_exec()</b>. They are: Line 190  matched by <b>pcre_exec()</b>. They are:
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    <b>pcre_get_stringnumber()</b>    <b>pcre_get_stringnumber()</b>
193      <b>pcre_get_stringtable_entries()</b>
194  </pre>  </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.
# Line 215  should be done before calling any PCRE f Line 225  should be done before calling any PCRE f
225  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
226  indirections to memory management functions. These special functions are used  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  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. This is  recursive function calls, when running the <b>pcre_exec()</b> function. See the
229  a non-standard way of building PCRE, for use in environments that have limited  <a href="pcrebuild.html"><b>pcrebuild</b></a>
230  stacks. Because of the greater use of memory management, it runs more slowly.  documentation for details of how to do this. It is a non-standard way of
231  Separate functions are provided so that special-purpose external code can be  building PCRE, for use in environments that have limited stacks. Because of the
232  used for this case. When used, these functions are always called in a  greater use of memory management, it runs more slowly. Separate functions are
233  stack-like manner (last obtained, first freed), and always for memory blocks of  provided so that special-purpose external code can be used for this case. When
234  the same size.  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>  </P>
240  <P>  <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
# Line 230  points during a matching operation. Deta Line 244  points during a matching operation. Deta
244  <a href="pcrecallout.html"><b>pcrecallout</b></a>  <a href="pcrecallout.html"><b>pcrecallout</b></a>
245  documentation.  documentation.
246  </P>  </P>
247  <br><a name="SEC3" href="#TOC1">MULTITHREADING</a><br>  <br><a name="SEC3" href="#TOC1">NEWLINES</a><br>
248    <P>
249    PCRE supports four 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, or any Unicode newline sequence.
252    The Unicode newline sequences are the three just mentioned, plus the single
253    characters VT (vertical tab, U+000B), FF (formfeed, U+000C), NEL (next line,
254    U+0085), LS (line separator, U+2028), and PS (paragraph separator, U+2029).
255    </P>
256    <P>
257    Each of the first three conventions is used by at least one operating system as
258    its standard newline sequence. When PCRE is built, a default can be specified.
259    The default default is LF, which is the Unix standard. When PCRE is run, the
260    default can be overridden, either when a pattern is compiled, or when it is
261    matched.
262    </P>
263    <P>
264    In the PCRE documentation the word "newline" is used to mean "the character or
265    pair of characters that indicate a line break". The choice of newline
266    convention affects the handling of the dot, circumflex, and dollar
267    metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
268    recognized line ending sequence, the match position advancement for a
269    non-anchored pattern. The choice of newline convention does not affect the
270    interpretation of the \n or \r escape sequences.
271    </P>
272    <br><a name="SEC4" href="#TOC1">MULTITHREADING</a><br>
273  <P>  <P>
274  The PCRE functions can be used in multi-threading applications, with the  The PCRE functions can be used in multi-threading applications, with the
275  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>,
# Line 241  callout function pointed to by <b>pcre_c Line 280  callout function pointed to by <b>pcre_c
280  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
281  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.
282  </P>  </P>
283  <br><a name="SEC4" href="#TOC1">SAVING PRECOMPILED PATTERNS FOR LATER USE</a><br>  <br><a name="SEC5" href="#TOC1">SAVING PRECOMPILED PATTERNS FOR LATER USE</a><br>
284  <P>  <P>
285  The compiled form of a regular expression can be saved and re-used at a later  The compiled form of a regular expression can be saved and re-used at a later
286  time, possibly by a different program, and even on a host other than the one on  time, possibly by a different program, and even on a host other than the one on
# Line 249  which it was compiled. Details are given Line 288  which it was compiled. Details are given
288  <a href="pcreprecompile.html"><b>pcreprecompile</b></a>  <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
289  documentation.  documentation.
290  </P>  </P>
291  <br><a name="SEC5" href="#TOC1">CHECKING BUILD-TIME OPTIONS</a><br>  <br><a name="SEC6" href="#TOC1">CHECKING BUILD-TIME OPTIONS</a><br>
292  <P>  <P>
293  <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>
294  </P>  </P>
# Line 276  properties is available; otherwise it is Line 315  properties is available; otherwise it is
315  <pre>  <pre>
316    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
317  </pre>  </pre>
318  The output is an integer that is set to the value of the code that is used for  The output is an integer whose value specifies the default character sequence
319  the newline character. It is either linefeed (10) or carriage return (13), and  that is recognized as meaning "newline". The four values that are supported
320  should normally be the standard character for your operating system.  are: 10 for LF, 13 for CR, 3338 for CRLF, and -1 for ANY. The default should
321    normally be the standard sequence for your operating system.
322  <pre>  <pre>
323    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
324  </pre>  </pre>
# Line 302  The output is an integer that gives the Line 342  The output is an integer that gives the
342  internal matching function calls in a <b>pcre_exec()</b> execution. Further  internal matching function calls in a <b>pcre_exec()</b> execution. Further
343  details are given with <b>pcre_exec()</b> below.  details are given with <b>pcre_exec()</b> below.
344  <pre>  <pre>
345      PCRE_CONFIG_MATCH_LIMIT_RECURSION
346    </pre>
347    The output is an integer that gives the default limit for the depth of
348    recursion when calling the internal matching function in a <b>pcre_exec()</b>
349    execution. Further details are given with <b>pcre_exec()</b> below.
350    <pre>
351    PCRE_CONFIG_STACKRECURSE    PCRE_CONFIG_STACKRECURSE
352  </pre>  </pre>
353  The output is an integer that is set to one if internal recursion when running  The output is an integer that is set to one if internal recursion when running
# Line 312  of recursive function calls. In this cas Line 358  of recursive function calls. In this cas
358  <b>pcre_stack_free</b> are called to manage memory blocks on the heap, thus  <b>pcre_stack_free</b> are called to manage memory blocks on the heap, thus
359  avoiding the use of the stack.  avoiding the use of the stack.
360  </P>  </P>
361  <br><a name="SEC6" href="#TOC1">COMPILING A PATTERN</a><br>  <br><a name="SEC7" href="#TOC1">COMPILING A PATTERN</a><br>
362  <P>  <P>
363  <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>
364  <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b>  <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
# Line 334  The pattern is a C string terminated by Line 380  The pattern is a C string terminated by
380  via <b>pcre_malloc</b> is returned. This contains the compiled code and related  via <b>pcre_malloc</b> is returned. This contains the compiled code and related
381  data. The <b>pcre</b> type is defined for the returned block; this is a typedef  data. The <b>pcre</b> type is defined for the returned block; this is a typedef
382  for a structure whose contents are not externally defined. It is up to the  for a structure whose contents are not externally defined. It is up to the
383  caller to free the memory when it is no longer required.  caller to free the memory (via <b>pcre_free</b>) when it is no longer required.
384  </P>  </P>
385  <P>  <P>
386  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 343  fully relocatable, because it may contai Line 389  fully relocatable, because it may contai
389  argument, which is an address (see below).  argument, which is an address (see below).
390  </P>  </P>
391  <P>  <P>
392  The <i>options</i> argument contains independent bits that affect the  The <i>options</i> argument contains various bit settings that affect the
393  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
394  options are described below. Some of them, in particular, those that are  options are described below. Some of them, in particular, those that are
395  compatible with Perl, can also be set and unset from within the pattern (see  compatible with Perl, can also be set and unset from within the pattern (see
# Line 351  the detailed description in the Line 397  the detailed description in the
397  <a href="pcrepattern.html"><b>pcrepattern</b></a>  <a href="pcrepattern.html"><b>pcrepattern</b></a>
398  documentation). For these options, the contents of the <i>options</i> argument  documentation). For these options, the contents of the <i>options</i> argument
399  specifies their initial settings at the start of compilation and execution. The  specifies their initial settings at the start of compilation and execution. The
400  PCRE_ANCHORED option can be set at the time of matching as well as at compile  PCRE_ANCHORED and PCRE_NEWLINE_<i>xxx</i> options can be set at the time of
401  time.  matching as well as at compile time.
402  </P>  </P>
403  <P>  <P>
404  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.
405  Otherwise, if compilation of a pattern fails, <b>pcre_compile()</b> returns  Otherwise, if compilation of a pattern fails, <b>pcre_compile()</b> returns
406  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
407  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
408  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
409    where the error was discovered is placed in the variable pointed to by
410  <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.
411  </P>  </P>
412  <P>  <P>
# Line 424  with UTF-8 support. Line 471  with UTF-8 support.
471  </pre>  </pre>
472  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
473  end of the subject string. Without this option, a dollar also matches  end of the subject string. Without this option, a dollar also matches
474  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
475  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.
476  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
477  a pattern.  pattern.
478  <pre>  <pre>
479    PCRE_DOTALL    PCRE_DOTALL
480  </pre>  </pre>
481  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,
482  including newlines. Without it, newlines are excluded. This option is  including those that indicate newline. Without it, a dot does not match when
483  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
484  (?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
485  character, independent of the setting of this option.  negative class such as [^a] always matches newline characters, independent of
486    the setting of this option.
487    <pre>
488      PCRE_DUPNAMES
489    </pre>
490    If this bit is set, names used to identify capturing subpatterns need not be
491    unique. This can be helpful for certain types of pattern when it is known that
492    only one instance of the named subpattern can ever be matched. There are more
493    details of named subpatterns below; see also the
494    <a href="pcrepattern.html"><b>pcrepattern</b></a>
495    documentation.
496  <pre>  <pre>
497    PCRE_EXTENDED    PCRE_EXTENDED
498  </pre>  </pre>
499  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
500  ignored except when escaped or inside a character class. Whitespace does not  ignored except when escaped or inside a character class. Whitespace does not
501  include the VT character (code 11). In addition, characters between an  include the VT character (code 11). In addition, characters between an
502  unescaped # outside a character class and the next newline character,  unescaped # outside a character class and the next newline, inclusive, are also
503  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
504  be changed within a pattern by a (?x) option setting.  pattern by a (?x) option setting.
505  </P>  </P>
506  <P>  <P>
507  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
# Line 459  that is incompatible with Perl, but it i Line 516  that is incompatible with Perl, but it i
516  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
517  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
518  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
519  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
520  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
521  pattern.  this option. It can also be set by a (?X) option setting within a pattern.
522  <pre>  <pre>
523    PCRE_FIRSTLINE    PCRE_FIRSTLINE
524  </pre>  </pre>
525  If this option is set, an unanchored pattern is required to match before or at  If this option is set, an unanchored pattern is required to match before or at
526  the first newline character in the subject string, though the matched text may  the first newline in the subject string, though the matched text may continue
527  continue over the newline.  over the newline.
528  <pre>  <pre>
529    PCRE_MULTILINE    PCRE_MULTILINE
530  </pre>  </pre>
# Line 480  Perl. Line 537  Perl.
537  </P>  </P>
538  <P>  <P>
539  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
540  match immediately following or immediately before any newline in the subject  match immediately following or immediately before internal newlines in the
541  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
542  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
543  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
544  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.
545  <pre>  <pre>
546      PCRE_NEWLINE_CR
547      PCRE_NEWLINE_LF
548      PCRE_NEWLINE_CRLF
549      PCRE_NEWLINE_ANY
550    </pre>
551    These options override the default newline definition that was chosen when PCRE
552    was built. Setting the first or the second specifies that a newline is
553    indicated by a single character (CR or LF, respectively). Setting
554    PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
555    CRLF sequence. Setting PCRE_NEWLINE_ANY specifies that any Unicode newline
556    sequence should be recognized. The Unicode newline sequences are the three just
557    mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed,
558    U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
559    (paragraph separator, U+2029). The last two are recognized only in UTF-8 mode.
560    </P>
561    <P>
562    The newline setting in the options word uses three bits that are treated
563    as a number, giving eight possibilities. Currently only five are used (default
564    plus the four values above). This means that if you set more than one newline
565    option, the combination may or may not be sensible. For example,
566    PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
567    other combinations yield unused numbers and cause an error.
568    </P>
569    <P>
570    The only time that a line break is specially recognized when compiling a
571    pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character
572    class is encountered. This indicates a comment that lasts until after the next
573    line break sequence. In other circumstances, line break sequences are treated
574    as literal data, except that in PCRE_EXTENDED mode, both CR and LF are treated
575    as whitespace characters and are therefore ignored.
576    </P>
577    <P>
578    The newline option that is set at compile time becomes the default that is used
579    for <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>, but it can be overridden.
580    <pre>
581    PCRE_NO_AUTO_CAPTURE    PCRE_NO_AUTO_CAPTURE
582  </pre>  </pre>
583  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
# Line 524  Note that this option can also be passed Line 616  Note that this option can also be passed
616  <b>pcre_dfa_exec()</b>, to suppress the UTF-8 validity checking of subject  <b>pcre_dfa_exec()</b>, to suppress the UTF-8 validity checking of subject
617  strings.  strings.
618  </P>  </P>
619  <br><a name="SEC7" href="#TOC1">COMPILATION ERROR CODES</a><br>  <br><a name="SEC8" href="#TOC1">COMPILATION ERROR CODES</a><br>
620  <P>  <P>
621  The following table lists the error codes than may be returned by  The following table lists the error codes than may be returned by
622  <b>pcre_compile2()</b>, along with the error messages that may be returned by  <b>pcre_compile2()</b>, along with the error messages that may be returned by
623  both compiling functions.  both compiling functions. As PCRE has developed, some error codes have fallen
624    out of use. To avoid confusion, they have not been re-used.
625  <pre>  <pre>
626     0  no error     0  no error
627     1  \ at end of pattern     1  \ at end of pattern
# Line 540  both compiling functions. Line 633  both compiling functions.
633     7  invalid escape sequence in character class     7  invalid escape sequence in character class
634     8  range out of order in character class     8  range out of order in character class
635     9  nothing to repeat     9  nothing to repeat
636    10  operand of unlimited repeat could match the empty string    10  [this code is not in use]
637    11  internal error: unexpected repeat    11  internal error: unexpected repeat
638    12  unrecognized character after (?    12  unrecognized character after (?
639    13  POSIX named classes are supported only within a class    13  POSIX named classes are supported only within a class
# Line 549  both compiling functions. Line 642  both compiling functions.
642    16  erroffset passed as NULL    16  erroffset passed as NULL
643    17  unknown option bit(s) set    17  unknown option bit(s) set
644    18  missing ) after comment    18  missing ) after comment
645    19  parentheses nested too deeply    19  [this code is not in use]
646    20  regular expression too large    20  regular expression too large
647    21  failed to get memory    21  failed to get memory
648    22  unmatched parentheses    22  unmatched parentheses
649    23  internal error: code overflow    23  internal error: code overflow
650    24  unrecognized character after (?&#60;    24  unrecognized character after (?&#60;
651    25  lookbehind assertion is not fixed length    25  lookbehind assertion is not fixed length
652    26  malformed number after (?(    26  malformed number or name after (?(
653    27  conditional group contains more than two branches    27  conditional group contains more than two branches
654    28  assertion expected after (?(    28  assertion expected after (?(
655    29  (?R or (?digits must be followed by )    29  (?R or (?digits must be followed by )
656    30  unknown POSIX class name    30  unknown POSIX class name
657    31  POSIX collating elements are not supported    31  POSIX collating elements are not supported
658    32  this version of PCRE is not compiled with PCRE_UTF8 support    32  this version of PCRE is not compiled with PCRE_UTF8 support
659    33  spare error    33  [this code is not in use]
660    34  character value in \x{...} sequence is too large    34  character value in \x{...} sequence is too large
661    35  invalid condition (?(0)    35  invalid condition (?(0)
662    36  \C not allowed in lookbehind assertion    36  \C not allowed in lookbehind assertion
# Line 572  both compiling functions. Line 665  both compiling functions.
665    39  closing ) for (?C expected    39  closing ) for (?C expected
666    40  recursive call could loop indefinitely    40  recursive call could loop indefinitely
667    41  unrecognized character after (?P    41  unrecognized character after (?P
668    42  syntax error after (?P    42  syntax error in subpattern name (missing terminator)
669    43  two named groups have the same name    43  two named subpatterns have the same name
670    44  invalid UTF-8 string    44  invalid UTF-8 string
671    45  support for \P, \p, and \X has not been compiled    45  support for \P, \p, and \X has not been compiled
672    46  malformed \P or \p sequence    46  malformed \P or \p sequence
673    47  unknown property name after \P or \p    47  unknown property name after \P or \p
674      48  subpattern name is too long (maximum 32 characters)
675      49  too many named subpatterns (maximum 10,000)
676      50  repeated subpattern is too long
677      51  octal value is greater than \377 (not in UTF-8 mode)
678      52  internal error: overran compiling workspace
679      53  internal error: previously-checked referenced subpattern not found
680      54  DEFINE group contains more than one branch
681      55  repeating a DEFINE group is not allowed
682      56  inconsistent NEWLINE options"
683  </PRE>  </PRE>
684  </P>  </P>
685  <br><a name="SEC8" href="#TOC1">STUDYING A PATTERN</a><br>  <br><a name="SEC9" href="#TOC1">STUDYING A PATTERN</a><br>
686  <P>  <P>
687  <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>
688  <b>const char **<i>errptr</i>);</b>  <b>const char **<i>errptr</i>);</b>
# Line 615  options are defined, and this argument s Line 717  options are defined, and this argument s
717  <P>  <P>
718  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
719  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
720  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
721  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
722  be sure that it has run successfully.  should test the error pointer for NULL after calling <b>pcre_study()</b>, to be
723    sure that it has run successfully.
724  </P>  </P>
725  <P>  <P>
726  This is a typical call to <b>pcre_study</b>():  This is a typical call to <b>pcre_study</b>():
# Line 632  At present, studying a pattern is useful Line 735  At present, studying a pattern is useful
735  not have a single fixed starting character. A bitmap of possible starting  not have a single fixed starting character. A bitmap of possible starting
736  bytes is created.  bytes is created.
737  <a name="localesupport"></a></P>  <a name="localesupport"></a></P>
738  <br><a name="SEC9" href="#TOC1">LOCALE SUPPORT</a><br>  <br><a name="SEC10" href="#TOC1">LOCALE SUPPORT</a><br>
739  <P>  <P>
740  PCRE handles caseless matching, and determines whether characters are letters  PCRE handles caseless matching, and determines whether characters are letters
741  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
742  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
743  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
744  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
745  support.  support. The use of locales with Unicode is discouraged.
746  </P>  </P>
747  <P>  <P>
748  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 680  this facility could be used to match a p Line 783  this facility could be used to match a p
783  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
784  below in the section on matching a pattern.  below in the section on matching a pattern.
785  </P>  </P>
786  <br><a name="SEC10" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br>  <br><a name="SEC11" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br>
787  <P>  <P>
788  <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>
789  <b>int <i>what</i>, void *<i>where</i>);</b>  <b>int <i>what</i>, void *<i>where</i>);</b>
# Line 708  check against passing an arbitrary memor Line 811  check against passing an arbitrary memor
811  <b>pcre_fullinfo()</b>, to obtain the length of the compiled pattern:  <b>pcre_fullinfo()</b>, to obtain the length of the compiled pattern:
812  <pre>  <pre>
813    int rc;    int rc;
814    unsigned long int length;    size_t length;
815    rc = pcre_fullinfo(    rc = pcre_fullinfo(
816      re,               /* result of pcre_compile() */      re,               /* result of pcre_compile() */
817      pe,               /* result of pcre_study(), or NULL */      pe,               /* result of pcre_study(), or NULL */
# Line 740  a NULL table pointer. Line 843  a NULL table pointer.
843    PCRE_INFO_FIRSTBYTE    PCRE_INFO_FIRSTBYTE
844  </pre>  </pre>
845  Return information about the first byte of any matched string, for a  Return information about the first byte of any matched string, for a
846  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>
847  old name is still recognized for backwards compatibility.)  variable. (This option used to be called PCRE_INFO_FIRSTCHAR; the old name is
848    still recognized for backwards compatibility.)
849  </P>  </P>
850  <P>  <P>
851  If there is a fixed first byte, for example, from a pattern such as  If there is a fixed first byte, for example, from a pattern such as
852  (cat|cow|coyote), it is returned in the integer pointed to by <i>where</i>.  (cat|cow|coyote), its value is returned. Otherwise, if either
 Otherwise, if either  
853  <br>  <br>
854  <br>  <br>
855  (a) the pattern was compiled with the PCRE_MULTILINE option, and every branch  (a) the pattern was compiled with the PCRE_MULTILINE option, and every branch
# Line 784  is -1. Line 887  is -1.
887  </pre>  </pre>
888  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
889  names are just an additional way of identifying the parentheses, which still  names are just an additional way of identifying the parentheses, which still
890  acquire numbers. A convenience function called <b>pcre_get_named_substring()</b>  acquire numbers. Several convenience functions such as
891  is provided for extracting an individual captured substring by name. It is also  <b>pcre_get_named_substring()</b> are provided for extracting captured
892  possible to extract the data directly, by first converting the name to a number  substrings by name. It is also possible to extract the data directly, by first
893  in order to access the correct pointers in the output vector (described with  converting the name to a number in order to access the correct pointers in the
894  <b>pcre_exec()</b> below). To do the conversion, you need to use the  output vector (described with <b>pcre_exec()</b> below). To do the conversion,
895  name-to-number map, which is described by these three values.  you need to use the name-to-number map, which is described by these three
896    values.
897  </P>  </P>
898  <P>  <P>
899  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 799  length of the longest name. PCRE_INFO_NA Line 903  length of the longest name. PCRE_INFO_NA
903  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
904  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
905  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
906  alphabetical order. For example, consider the following pattern (assume  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of
907    their parentheses numbers. For example, consider the following pattern (assume
908  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  PCRE_EXTENDED is set, so white space - including newlines - is ignored):
909  <pre>  <pre>
910    (?P&#60;date&#62; (?P&#60;year&#62;(\d\d)?\d\d) - (?P&#60;month&#62;\d\d) - (?P&#60;day&#62;\d\d) )    (?&#60;date&#62; (?&#60;year&#62;(\d\d)?\d\d) - (?&#60;month&#62;\d\d) - (?&#60;day&#62;\d\d) )
911  </pre>  </pre>
912  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
913  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
# Line 814  bytes shows in hexadecimal, and undefine Line 919  bytes shows in hexadecimal, and undefine
919    00 02 y  e  a  r  00 ??    00 02 y  e  a  r  00 ??
920  </pre>  </pre>
921  When writing code to extract data from named subpatterns using the  When writing code to extract data from named subpatterns using the
922  name-to-number map, remember that the length of each entry is likely to be  name-to-number map, remember that the length of the entries is likely to be
923  different for each compiled pattern.  different for each compiled pattern.
924  <pre>  <pre>
925    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
# Line 851  a <b>pcre_extra</b> block. That is, it i Line 956  a <b>pcre_extra</b> block. That is, it i
956  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
957  <b>size_t</b> variable.  <b>size_t</b> variable.
958  </P>  </P>
959  <br><a name="SEC11" href="#TOC1">OBSOLETE INFO FUNCTION</a><br>  <br><a name="SEC12" href="#TOC1">OBSOLETE INFO FUNCTION</a><br>
960  <P>  <P>
961  <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>
962  <b>*<i>firstcharptr</i>);</b>  <b>*<i>firstcharptr</i>);</b>
# Line 875  If the pattern is not anchored and the < Line 980  If the pattern is not anchored and the <
980  it is used to pass back information about the first character of any matched  it is used to pass back information about the first character of any matched
981  string (see PCRE_INFO_FIRSTBYTE above).  string (see PCRE_INFO_FIRSTBYTE above).
982  </P>  </P>
983  <br><a name="SEC12" href="#TOC1">REFERENCE COUNTS</a><br>  <br><a name="SEC13" href="#TOC1">REFERENCE COUNTS</a><br>
984  <P>  <P>
985  <b>int pcre_refcount(pcre *<i>code</i>, int <i>adjust</i>);</b>  <b>int pcre_refcount(pcre *<i>code</i>, int <i>adjust</i>);</b>
986  </P>  </P>
# Line 899  Except when it is zero, the reference co Line 1004  Except when it is zero, the reference co
1004  pattern is compiled on one host and then transferred to a host whose byte-order  pattern is compiled on one host and then transferred to a host whose byte-order
1005  is different. (This seems a highly unlikely scenario.)  is different. (This seems a highly unlikely scenario.)
1006  </P>  </P>
1007  <br><a name="SEC13" href="#TOC1">MATCHING A PATTERN: THE TRADITIONAL FUNCTION</a><br>  <br><a name="SEC14" href="#TOC1">MATCHING A PATTERN: THE TRADITIONAL FUNCTION</a><br>
1008  <P>  <P>
1009  <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>
1010  <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 947  Extra data for <b>pcre_exec()</b> Line 1052  Extra data for <b>pcre_exec()</b>
1052  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>
1053  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
1054  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
1055  additional information in it. The fields in a <b>pcre_extra</b> block are as  additional information in it. The <b>pcre_extra</b> block contains the following
1056  follows:  fields (not necessarily in this order):
1057  <pre>  <pre>
1058    unsigned long int <i>flags</i>;    unsigned long int <i>flags</i>;
1059    void *<i>study_data</i>;    void *<i>study_data</i>;
1060    unsigned long int <i>match_limit</i>;    unsigned long int <i>match_limit</i>;
1061      unsigned long int <i>match_limit_recursion</i>;
1062    void *<i>callout_data</i>;    void *<i>callout_data</i>;
1063    const unsigned char *<i>tables</i>;    const unsigned char *<i>tables</i>;
1064  </pre>  </pre>
# Line 961  are set. The flag bits are: Line 1067  are set. The flag bits are:
1067  <pre>  <pre>
1068    PCRE_EXTRA_STUDY_DATA    PCRE_EXTRA_STUDY_DATA
1069    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1070      PCRE_EXTRA_MATCH_LIMIT_RECURSION
1071    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1072    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1073  </pre>  </pre>
# Line 977  classic example is the use of nested unl Line 1084  classic example is the use of nested unl
1084  </P>  </P>
1085  <P>  <P>
1086  Internally, PCRE uses a function called <b>match()</b> which it calls repeatedly  Internally, PCRE uses a function called <b>match()</b> which it calls repeatedly
1087  (sometimes recursively). The limit is imposed on the number of times this  (sometimes recursively). The limit set by <i>match_limit</i> is imposed on the
1088  function is called during a match, which has the effect of limiting the amount  number of times this function is called during a match, which has the effect of
1089  of recursion and backtracking that can take place. For patterns that are not  limiting the amount of backtracking that can take place. For patterns that are
1090  anchored, the count starts from zero for each position in the subject string.  not anchored, the count restarts from zero for each position in the subject
1091    string.
1092  </P>  </P>
1093  <P>  <P>
1094  The default limit for the library can be set when PCRE is built; the default  The default value for the limit can be set when PCRE is built; the default
1095  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
1096  reduce the default by suppling <b>pcre_exec()</b> with a <b>pcre_extra</b> block  override the default by suppling <b>pcre_exec()</b> with a <b>pcre_extra</b>
1097  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
1098  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
1099  exceeded, <b>pcre_exec()</b> returns PCRE_ERROR_MATCHLIMIT.  PCRE_ERROR_MATCHLIMIT.
1100    </P>
1101    <P>
1102    The <i>match_limit_recursion</i> field is similar to <i>match_limit</i>, but
1103    instead of limiting the total number of times that <b>match()</b> is called, it
1104    limits the depth of recursion. The recursion depth is a smaller number than the
1105    total number of calls, because not all calls to <b>match()</b> are recursive.
1106    This limit is of use only if it is set smaller than <i>match_limit</i>.
1107    </P>
1108    <P>
1109    Limiting the recursion depth limits the amount of stack that can be used, or,
1110    when PCRE has been compiled to use memory on the heap instead of the stack, the
1111    amount of heap memory that can be used.
1112    </P>
1113    <P>
1114    The default value for <i>match_limit_recursion</i> can be set when PCRE is
1115    built; the default default is the same value as the default for
1116    <i>match_limit</i>. You can override the default by suppling <b>pcre_exec()</b>
1117    with a <b>pcre_extra</b> block in which <i>match_limit_recursion</i> is set, and
1118    PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the <i>flags</i> field. If the limit
1119    is exceeded, <b>pcre_exec()</b> returns PCRE_ERROR_RECURSIONLIMIT.
1120  </P>  </P>
1121  <P>  <P>
1122  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,
# Line 1014  Option bits for <b>pcre_exec()</b> Line 1142  Option bits for <b>pcre_exec()</b>
1142  </b><br>  </b><br>
1143  <P>  <P>
1144  The unused bits of the <i>options</i> argument for <b>pcre_exec()</b> must be  The unused bits of the <i>options</i> argument for <b>pcre_exec()</b> must be
1145  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NOTBOL,  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_<i>xxx</i>,
1146  PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.
1147  <pre>  <pre>
1148    PCRE_ANCHORED    PCRE_ANCHORED
1149  </pre>  </pre>
# Line 1024  matching position. If a pattern was comp Line 1152  matching position. If a pattern was comp
1152  to be anchored by virtue of its contents, it cannot be made unachored at  to be anchored by virtue of its contents, it cannot be made unachored at
1153  matching time.  matching time.
1154  <pre>  <pre>
1155      PCRE_NEWLINE_CR
1156      PCRE_NEWLINE_LF
1157      PCRE_NEWLINE_CRLF
1158      PCRE_NEWLINE_ANY
1159    </pre>
1160    These options override the newline definition that was chosen or defaulted when
1161    the pattern was compiled. For details, see the description of
1162    <b>pcre_compile()</b> above. During matching, the newline choice affects the
1163    behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1164    the way the match position is advanced after a match failure for an unanchored
1165    pattern. When PCRE_NEWLINE_CRLF or PCRE_NEWLINE_ANY is set, and a match attempt
1166    fails when the current position is at a CRLF sequence, the match position is
1167    advanced by two characters instead of one, in other words, to after the CRLF.
1168    <pre>
1169    PCRE_NOTBOL    PCRE_NOTBOL
1170  </pre>  </pre>
1171  This option specifies that first character of the subject string is not the  This option specifies that first character of the subject string is not the
# Line 1162  is set to the offset of the first charac Line 1304  is set to the offset of the first charac
1304  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
1305  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
1306  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>
1307  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
1308  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
1309  just the first pair of offsets has been set.  capturing subpatterns, the return value from a successful match is 1,
1310  </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.  
1311  </P>  </P>
1312  <P>  <P>
1313  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
# Line 1192  has to get additional memory for use dur Line 1324  has to get additional memory for use dur
1324  advisable to supply an <i>ovector</i>.  advisable to supply an <i>ovector</i>.
1325  </P>  </P>
1326  <P>  <P>
1327  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
1328  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1329  <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
1330  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.
1331    </P>
1332    <P>
1333    It is possible for capturing subpattern number <i>n+1</i> to match some part of
1334    the subject when subpattern <i>n</i> has not been used at all. For example, if
1335    the string "abc" is matched against the pattern (a|(z))(bc) the return from the
1336    function is 4, and subpatterns 1 and 3 are matched, but 2 is not. When this
1337    happens, both values in the offset pairs corresponding to unused subpatterns
1338    are set to -1.
1339    </P>
1340    <P>
1341    Offset values that correspond to unused subpatterns at the end of the
1342    expression are also set to -1. For example, if the string "abc" is matched
1343    against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
1344    return from the function is 2, because the highest used capturing subpattern
1345    number is 1. However, you can refer to the offsets for the second and third
1346    capturing subpatterns if you wish (assuming the vector is large enough, of
1347    course).
1348    </P>
1349    <P>
1350    Some convenience functions are provided for extracting the captured substrings
1351    as separate strings. These are described below.
1352  <a name="errorlist"></a></P>  <a name="errorlist"></a></P>
1353  <br><b>  <br><b>
1354  Return values from <b>pcre_exec()</b>  Error return values from <b>pcre_exec()</b>
1355  </b><br>  </b><br>
1356  <P>  <P>
1357  If <b>pcre_exec()</b> fails, it returns a negative number. The following are  If <b>pcre_exec()</b> fails, it returns a negative number. The following are
# Line 1225  compiled in an environment of one endian Line 1378  compiled in an environment of one endian
1378  other endianness. This is the error that PCRE gives when the magic number is  other endianness. This is the error that PCRE gives when the magic number is
1379  not present.  not present.
1380  <pre>  <pre>
1381    PCRE_ERROR_UNKNOWN_NODE   (-5)    PCRE_ERROR_UNKNOWN_OPCODE (-5)
1382  </pre>  </pre>
1383  While running the pattern match, an unknown item was encountered in the  While running the pattern match, an unknown item was encountered in the
1384  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
# Line 1247  below). It is never returned by <b>pcre_ Line 1400  below). It is never returned by <b>pcre_
1400  <pre>  <pre>
1401    PCRE_ERROR_MATCHLIMIT     (-8)    PCRE_ERROR_MATCHLIMIT     (-8)
1402  </pre>  </pre>
1403  The recursion and backtracking limit, as specified by the <i>match_limit</i>  The backtracking limit, as specified by the <i>match_limit</i> field in a
1404  field in a <b>pcre_extra</b> structure (or defaulted) was reached. See the  <b>pcre_extra</b> structure (or defaulted) was reached. See the description
1405  description above.  above.
1406  <pre>  <pre>
1407    PCRE_ERROR_CALLOUT        (-9)    PCRE_ERROR_CALLOUT        (-9)
1408  </pre>  </pre>
# Line 1288  in PCRE or by overwriting of the compile Line 1441  in PCRE or by overwriting of the compile
1441    PCRE_ERROR_BADCOUNT       (-15)    PCRE_ERROR_BADCOUNT       (-15)
1442  </pre>  </pre>
1443  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.
1444    <pre>
1445      PCRE_ERROR_RECURSIONLIMIT (-21)
1446    </pre>
1447    The internal recursion limit, as specified by the <i>match_limit_recursion</i>
1448    field in a <b>pcre_extra</b> structure (or defaulted) was reached. See the
1449    description above.
1450    <pre>
1451      PCRE_ERROR_NULLWSLIMIT    (-22)
1452    </pre>
1453    When a group that can match an empty substring is repeated with an unbounded
1454    upper limit, the subject position at the start of the group must be remembered,
1455    so that a test for an empty string can be made when the end of the group is
1456    reached. Some workspace is required for this; if it runs out, this error is
1457    given.
1458    <pre>
1459      PCRE_ERROR_BADNEWLINE     (-23)
1460    </pre>
1461    An invalid combination of PCRE_NEWLINE_<i>xxx</i> options was given.
1462  </P>  </P>
1463  <br><a name="SEC14" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>  <P>
1464    Error numbers -16 to -20 are not used by <b>pcre_exec()</b>.
1465    </P>
1466    <br><a name="SEC15" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>
1467  <P>  <P>
1468  <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>
1469  <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 1311  Captured substrings can be accessed dire Line 1485  Captured substrings can be accessed dire
1485  <b>pcre_get_substring_list()</b> are provided for extracting captured substrings  <b>pcre_get_substring_list()</b> are provided for extracting captured substrings
1486  as new, separate, zero-terminated strings. These functions identify substrings  as new, separate, zero-terminated strings. These functions identify substrings
1487  by number. The next section describes functions for extracting named  by number. The next section describes functions for extracting named
1488  substrings. A substring that contains a binary zero is correctly extracted and  substrings.
1489  has a further zero added on the end, but the result is not, of course,  </P>
1490  a C string.  <P>
1491    A substring that contains a binary zero is correctly extracted and has a
1492    further zero added on the end, but the result is not, of course, a C string.
1493    However, you can process such a string by referring to the length that is
1494    returned by <b>pcre_copy_substring()</b> and <b>pcre_get_substring()</b>.
1495    Unfortunately, the interface to <b>pcre_get_substring_list()</b> is not adequate
1496    for handling strings containing binary zeros, because the end of the final
1497    string is not independently indicated.
1498  </P>  </P>
1499  <P>  <P>
1500  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:
# Line 1335  the string is placed in <i>buffer</i>, w Line 1516  the string is placed in <i>buffer</i>, w
1516  <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
1517  obtained via <b>pcre_malloc</b>, and its address is returned via  obtained via <b>pcre_malloc</b>, and its address is returned via
1518  <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
1519  including the terminating zero, or one of  including the terminating zero, or one of these error codes:
1520  <pre>  <pre>
1521    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1522  </pre>  </pre>
# Line 1352  and builds a list of pointers to them. A Line 1533  and builds a list of pointers to them. A
1533  memory that 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
1534  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
1535  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
1536  function is zero if all went well, or  function is zero if all went well, or the error code
1537  <pre>  <pre>
1538    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1539  </pre>  </pre>
# Line 1373  a previous call of <b>pcre_get_substring Line 1554  a previous call of <b>pcre_get_substring
1554  <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
1555  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
1556  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
1557  linked via a special interface to another programming language which cannot use  linked via a special interface to another programming language that cannot use
1558  <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
1559  provided.  provided.
1560  </P>  </P>
1561  <br><a name="SEC15" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a><br>  <br><a name="SEC16" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a><br>
1562  <P>  <P>
1563  <b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b>  <b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b>
1564  <b>const char *<i>name</i>);</b>  <b>const char *<i>name</i>);</b>
# Line 1400  For example, for this pattern Line 1581  For example, for this pattern
1581  <pre>  <pre>
1582    (a+)b(?&#60;xxx&#62;\d+)...    (a+)b(?&#60;xxx&#62;\d+)...
1583  </pre>  </pre>
1584  the number of the subpattern called "xxx" is 2. You can find the number from  the number of the subpattern called "xxx" is 2. If the name is known to be
1585  the name by calling <b>pcre_get_stringnumber()</b>. The first argument is the  unique (PCRE_DUPNAMES was not set), you can find the number from the name by
1586  compiled pattern, and the second is the name. The yield of the function is the  calling <b>pcre_get_stringnumber()</b>. The first argument is the compiled
1587    pattern, and the second is the name. The yield of the function is the
1588  subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if there is no subpattern of  subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if there is no subpattern of
1589  that name.  that name.
1590  </P>  </P>
# Line 1412  functions described in the previous sect Line 1594  functions described in the previous sect
1594  two functions that do the whole job.  two functions that do the whole job.
1595  </P>  </P>
1596  <P>  <P>
1597  Most of the arguments of <i>pcre_copy_named_substring()</i> and  Most of the arguments of <b>pcre_copy_named_substring()</b> and
1598  <i>pcre_get_named_substring()</i> are the same as those for the similarly named  <b>pcre_get_named_substring()</b> are the same as those for the similarly named
1599  functions that extract by number. As these are described in the previous  functions that extract by number. As these are described in the previous
1600  section, they are not re-described here. There are just two differences:  section, they are not re-described here. There are just two differences:
1601  </P>  </P>
# Line 1425  translation table. Line 1607  translation table.
1607  </P>  </P>
1608  <P>  <P>
1609  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
1610  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
1611  appropriate.  appropriate. <b>NOTE:</b> If PCRE_DUPNAMES is set and there are duplicate names,
1612    the behaviour may not be what you want (see the next section).
1613    </P>
1614    <br><a name="SEC17" href="#TOC1">DUPLICATE SUBPATTERN NAMES</a><br>
1615    <P>
1616    <b>int pcre_get_stringtable_entries(const pcre *<i>code</i>,</b>
1617    <b>const char *<i>name</i>, char **<i>first</i>, char **<i>last</i>);</b>
1618    </P>
1619    <P>
1620    When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
1621    are not required to be unique. Normally, patterns with duplicate names are such
1622    that in any one match, only one of the named subpatterns participates. An
1623    example is shown in the
1624    <a href="pcrepattern.html"><b>pcrepattern</b></a>
1625    documentation. When duplicates are present, <b>pcre_copy_named_substring()</b>
1626    and <b>pcre_get_named_substring()</b> return the first substring corresponding
1627    to the given name that is set. If none are set, an empty string is returned.
1628    The <b>pcre_get_stringnumber()</b> function returns one of the numbers that are
1629    associated with the name, but it is not defined which it is.
1630    <br>
1631    <br>
1632    If you want to get full details of all captured substrings for a given name,
1633    you must use the <b>pcre_get_stringtable_entries()</b> function. The first
1634    argument is the compiled pattern, and the second is the name. The third and
1635    fourth are pointers to variables which are updated by the function. After it
1636    has run, they point to the first and last entries in the name-to-number table
1637    for the given name. The function itself returns the length of each entry, or
1638    PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
1639    described above in the section entitled <i>Information about a pattern</i>.
1640    Given all the relevant entries for the name, you can extract each of their
1641    numbers, and hence the captured data, if any.
1642  </P>  </P>
1643  <br><a name="SEC16" href="#TOC1">FINDING ALL POSSIBLE MATCHES</a><br>  <br><a name="SEC18" href="#TOC1">FINDING ALL POSSIBLE MATCHES</a><br>
1644  <P>  <P>
1645  The traditional matching function uses a similar algorithm to Perl, which stops  The traditional matching function uses a similar algorithm to Perl, which stops
1646  when it finds the first match, starting at a given point in the subject. If you  when it finds the first match, starting at a given point in the subject. If you
# Line 1447  substring. Then return 1, which forces < Line 1659  substring. Then return 1, which forces <
1659  other alternatives. Ultimately, when it runs out of matches, <b>pcre_exec()</b>  other alternatives. Ultimately, when it runs out of matches, <b>pcre_exec()</b>
1660  will yield PCRE_ERROR_NOMATCH.  will yield PCRE_ERROR_NOMATCH.
1661  <a name="dfamatch"></a></P>  <a name="dfamatch"></a></P>
1662  <br><a name="SEC17" href="#TOC1">MATCHING A PATTERN: THE ALTERNATIVE FUNCTION</a><br>  <br><a name="SEC19" href="#TOC1">MATCHING A PATTERN: THE ALTERNATIVE FUNCTION</a><br>
1663  <P>  <P>
1664  <b>int pcre_dfa_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>  <b>int pcre_dfa_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
1665  <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 1456  will yield PCRE_ERROR_NOMATCH. Line 1668  will yield PCRE_ERROR_NOMATCH.
1668  </P>  </P>
1669  <P>  <P>
1670  The function <b>pcre_dfa_exec()</b> is called to match a subject string against  The function <b>pcre_dfa_exec()</b> is called to match a subject string against
1671  a compiled pattern, using a "DFA" matching algorithm. This has different  a compiled pattern, using a matching algorithm that scans the subject string
1672  characteristics to the normal algorithm, and is not compatible with Perl. Some  just once, and does not backtrack. This has different characteristics to the
1673  of the features of PCRE patterns are not supported. Nevertheless, there are  normal algorithm, and is not compatible with Perl. Some of the features of PCRE
1674  times when this kind of matching can be useful. For a discussion of the two  patterns are not supported. Nevertheless, there are times when this kind of
1675  matching algorithms, see the  matching can be useful. For a discussion of the two matching algorithms, see
1676    the
1677  <a href="pcrematching.html"><b>pcrematching</b></a>  <a href="pcrematching.html"><b>pcrematching</b></a>
1678  documentation.  documentation.
1679  </P>  </P>
# Line 1475  here. Line 1688  here.
1688  The two additional arguments provide workspace for the function. The workspace  The two additional arguments provide workspace for the function. The workspace
1689  vector should contain at least 20 elements. It is used for keeping track of  vector should contain at least 20 elements. It is used for keeping track of
1690  multiple paths through the pattern tree. More workspace will be needed for  multiple paths through the pattern tree. More workspace will be needed for
1691  patterns and subjects where there are a lot of possible matches.  patterns and subjects where there are a lot of potential matches.
1692  </P>  </P>
1693  <P>  <P>
1694  Here is an example of a simple call to <b>pcre_exec()</b>:  Here is an example of a simple call to <b>pcre_dfa_exec()</b>:
1695  <pre>  <pre>
1696    int rc;    int rc;
1697    int ovector[10];    int ovector[10];
1698    int wspace[20];    int wspace[20];
1699    rc = pcre_exec(    rc = pcre_dfa_exec(
1700      re,             /* result of pcre_compile() */      re,             /* result of pcre_compile() */
1701      NULL,           /* we didn't study the pattern */      NULL,           /* we didn't study the pattern */
1702      "some string",  /* the subject string */      "some string",  /* the subject string */
# Line 1501  Option bits for <b>pcre_dfa_exec()</b> Line 1714  Option bits for <b>pcre_dfa_exec()</b>
1714  </b><br>  </b><br>
1715  <P>  <P>
1716  The unused bits of the <i>options</i> argument for <b>pcre_dfa_exec()</b> must be  The unused bits of the <i>options</i> argument for <b>pcre_dfa_exec()</b> must be
1717  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NOTBOL,  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_<i>xxx</i>,
1718  PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,
1719  PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last three of these are  PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last three of these are
1720  the same as for <b>pcre_exec()</b>, so their description is not repeated here.  the same as for <b>pcre_exec()</b>, so their description is not repeated here.
1721  <pre>  <pre>
# Line 1519  matching string. Line 1732  matching string.
1732    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
1733  </pre>  </pre>
1734  Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as  Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as
1735  soon as it has found one match. Because of the way the DFA algorithm works,  soon as it has found one match. Because of the way the alternative algorithm
1736  this is necessarily the shortest possible match at the first possible matching  works, this is necessarily the shortest possible match at the first possible
1737  point in the subject string.  matching point in the subject string.
1738  <pre>  <pre>
1739    PCRE_DFA_RESTART    PCRE_DFA_RESTART
1740  </pre>  </pre>
# Line 1559  the three matched strings are Line 1772  the three matched strings are
1772  On success, the yield of the function is a number greater than zero, which is  On success, the yield of the function is a number greater than zero, which is
1773  the number of matched substrings. The substrings themselves are returned in  the number of matched substrings. The substrings themselves are returned in
1774  <i>ovector</i>. Each string uses two elements; the first is the offset to the  <i>ovector</i>. Each string uses two elements; the first is the offset to the
1775  start, and the second is the offset to the end. All the strings have the same  start, and the second is the offset to the end. In fact, all the strings have
1776  start offset. (Space could have been saved by giving this only once, but it was  the same start offset. (Space could have been saved by giving this only once,
1777  decided to retain some compatibility with the way <b>pcre_exec()</b> returns  but it was decided to retain some compatibility with the way <b>pcre_exec()</b>
1778  data, even though the meaning of the strings is different.)  returns data, even though the meaning of the strings is different.)
1779  </P>  </P>
1780  <P>  <P>
1781  The strings are returned in reverse order of length; that is, the longest  The strings are returned in reverse order of length; that is, the longest
# Line 1588  that it does not support, for instance, Line 1801  that it does not support, for instance,
1801  <pre>  <pre>
1802    PCRE_ERROR_DFA_UCOND      (-17)    PCRE_ERROR_DFA_UCOND      (-17)
1803  </pre>  </pre>
1804  This return is given if <b>pcre_dfa_exec()</b> encounters a condition item in a  This return is given if <b>pcre_dfa_exec()</b> encounters a condition item that
1805  pattern that uses a back reference for the condition. This is not supported.  uses a back reference for the condition, or a test for recursion in a specific
1806    group. These are not supported.
1807  <pre>  <pre>
1808    PCRE_ERROR_DFA_UMLIMIT    (-18)    PCRE_ERROR_DFA_UMLIMIT    (-18)
1809  </pre>  </pre>
# Line 1609  recursively, using private vectors for < Line 1823  recursively, using private vectors for <
1823  error is given if the output vector is not large enough. This should be  error is given if the output vector is not large enough. This should be
1824  extremely rare, as a vector of size 1000 is used.  extremely rare, as a vector of size 1000 is used.
1825  </P>  </P>
1826    <br><a name="SEC20" href="#TOC1">SEE ALSO</a><br>
1827  <P>  <P>
1828  Last updated: 16 May 2005  <b>pcrebuild</b>(3), <b>pcrecallout</b>(3), <b>pcrecpp(3)</b>(3),
1829    <b>pcrematching</b>(3), <b>pcrepartial</b>(3), <b>pcreposix</b>(3),
1830    <b>pcreprecompile</b>(3), <b>pcresample</b>(3), <b>pcrestack</b>(3).
1831    </P>
1832    <br><a name="SEC21" href="#TOC1">AUTHOR</a><br>
1833    <P>
1834    Philip Hazel
1835    <br>
1836    University Computing Service
1837    <br>
1838    Cambridge CB2 3QH, England.
1839    <br>
1840    </P>
1841    <br><a name="SEC22" href="#TOC1">REVISION</a><br>
1842    <P>
1843    Last updated: 06 March 2007
1844    <br>
1845    Copyright &copy; 1997-2007 University of Cambridge.
1846  <br>  <br>
 Copyright &copy; 1997-2005 University of Cambridge.  
1847  <p>  <p>
1848  Return to the <a href="index.html">PCRE index page</a>.  Return to the <a href="index.html">PCRE index page</a>.
1849  </p>  </p>

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