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# 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  </ul>  </ul>
37  <br><a name="SEC1" href="#TOC1">PCRE NATIVE API</a><br>  <br><a name="SEC1" href="#TOC1">PCRE NATIVE API</a><br>
38  <P>  <P>
# Line 83  man page, in case the conversion went wr Line 86  man page, in case the conversion went wr
86  <b>const char *<i>name</i>);</b>  <b>const char *<i>name</i>);</b>
87  </P>  </P>
88  <P>  <P>
89    <b>int pcre_get_stringtable_entries(const pcre *<i>code</i>,</b>
90    <b>const char *<i>name</i>, char **<i>first</i>, char **<i>last</i>);</b>
91    </P>
92    <P>
93  <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>
94  <b>int <i>stringcount</i>, int <i>stringnumber</i>,</b>  <b>int <i>stringcount</i>, int <i>stringnumber</i>,</b>
95  <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 141  man page, in case the conversion went wr
141  </P>  </P>
142  <br><a name="SEC2" href="#TOC1">PCRE API OVERVIEW</a><br>  <br><a name="SEC2" href="#TOC1">PCRE API OVERVIEW</a><br>
143  <P>  <P>
144  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
145  also a set of wrapper functions that correspond to the POSIX regular expression  also some wrapper functions that correspond to the POSIX regular expression
146  API. These are described in the  API. These are described in the
147  <a href="pcreposix.html"><b>pcreposix</b></a>  <a href="pcreposix.html"><b>pcreposix</b></a>
148  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 170  documentation describes how to run it.
170  <P>  <P>
171  A second matching function, <b>pcre_dfa_exec()</b>, which is not  A second matching function, <b>pcre_dfa_exec()</b>, which is not
172  Perl-compatible, is also provided. This uses a different algorithm for the  Perl-compatible, is also provided. This uses a different algorithm for the
173  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
174  subject), not just one. However, this algorithm does not return captured  point in the subject), and scans the subject just once. However, this algorithm
175  substrings. A description of the two matching algorithms and their advantages  does not return captured substrings. A description of the two matching
176  and disadvantages is given in the  algorithms and their advantages and disadvantages is given in the
177  <a href="pcrematching.html"><b>pcrematching</b></a>  <a href="pcrematching.html"><b>pcrematching</b></a>
178  documentation.  documentation.
179  </P>  </P>
# Line 181  matched by <b>pcre_exec()</b>. They are: Line 188  matched by <b>pcre_exec()</b>. They are:
188    <b>pcre_get_named_substring()</b>    <b>pcre_get_named_substring()</b>
189    <b>pcre_get_substring_list()</b>    <b>pcre_get_substring_list()</b>
190    <b>pcre_get_stringnumber()</b>    <b>pcre_get_stringnumber()</b>
191      <b>pcre_get_stringtable_entries()</b>
192  </pre>  </pre>
193  <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
194  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 223  should be done before calling any PCRE f
223  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
224  indirections to memory management functions. These special functions are used  indirections to memory management functions. These special functions are used
225  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
226  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
227  a non-standard way of building PCRE, for use in environments that have limited  <a href="pcrebuild.html"><b>pcrebuild</b></a>
228  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
229  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
230  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
231  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
232  the same size.  used, these functions are always called in a stack-like manner (last obtained,
233    first freed), and always for memory blocks of the same size. There is a
234    discussion about PCRE's stack usage in the
235    <a href="pcrestack.html"><b>pcrestack</b></a>
236    documentation.
237  </P>  </P>
238  <P>  <P>
239  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 242  points during a matching operation. Deta
242  <a href="pcrecallout.html"><b>pcrecallout</b></a>  <a href="pcrecallout.html"><b>pcrecallout</b></a>
243  documentation.  documentation.
244  </P>  </P>
245  <br><a name="SEC3" href="#TOC1">MULTITHREADING</a><br>  <br><a name="SEC3" href="#TOC1">NEWLINES</a><br>
246    <P>
247    PCRE supports four different conventions for indicating line breaks in
248    strings: a single CR (carriage return) character, a single LF (linefeed)
249    character, the two-character sequence CRLF, or any Unicode newline sequence.
250    The Unicode newline sequences are the three just mentioned, plus the single
251    characters VT (vertical tab, U+000B), FF (formfeed, U+000C), NEL (next line,
252    U+0085), LS (line separator, U+2028), and PS (paragraph separator, U+2029).
253    </P>
254    <P>
255    Each of the first three conventions is used by at least one operating system as
256    its standard newline sequence. When PCRE is built, a default can be specified.
257    The default default is LF, which is the Unix standard. When PCRE is run, the
258    default can be overridden, either when a pattern is compiled, or when it is
259    matched.
260    </P>
261    <P>
262    In the PCRE documentation the word "newline" is used to mean "the character or
263    pair of characters that indicate a line break". The choice of newline
264    convention affects the handling of the dot, circumflex, and dollar
265    metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
266    recognized line ending sequence, the match position advancement for a
267    non-anchored pattern. The choice of newline convention does not affect the
268    interpretation of the \n or \r escape sequences.
269    </P>
270    <br><a name="SEC4" href="#TOC1">MULTITHREADING</a><br>
271  <P>  <P>
272  The PCRE functions can be used in multi-threading applications, with the  The PCRE functions can be used in multi-threading applications, with the
273  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 278  callout function pointed to by <b>pcre_c
278  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
279  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.
280  </P>  </P>
281  <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>
282  <P>  <P>
283  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
284  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 286  which it was compiled. Details are given
286  <a href="pcreprecompile.html"><b>pcreprecompile</b></a>  <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
287  documentation.  documentation.
288  </P>  </P>
289  <br><a name="SEC5" href="#TOC1">CHECKING BUILD-TIME OPTIONS</a><br>  <br><a name="SEC6" href="#TOC1">CHECKING BUILD-TIME OPTIONS</a><br>
290  <P>  <P>
291  <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>
292  </P>  </P>
# Line 276  properties is available; otherwise it is Line 313  properties is available; otherwise it is
313  <pre>  <pre>
314    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
315  </pre>  </pre>
316  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
317  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
318  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
319    normally be the standard sequence for your operating system.
320  <pre>  <pre>
321    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
322  </pre>  </pre>
# Line 302  The output is an integer that gives the Line 340  The output is an integer that gives the
340  internal matching function calls in a <b>pcre_exec()</b> execution. Further  internal matching function calls in a <b>pcre_exec()</b> execution. Further
341  details are given with <b>pcre_exec()</b> below.  details are given with <b>pcre_exec()</b> below.
342  <pre>  <pre>
343      PCRE_CONFIG_MATCH_LIMIT_RECURSION
344    </pre>
345    The output is an integer that gives the default limit for the depth of
346    recursion when calling the internal matching function in a <b>pcre_exec()</b>
347    execution. Further details are given with <b>pcre_exec()</b> below.
348    <pre>
349    PCRE_CONFIG_STACKRECURSE    PCRE_CONFIG_STACKRECURSE
350  </pre>  </pre>
351  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 356  of recursive function calls. In this cas
356  <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
357  avoiding the use of the stack.  avoiding the use of the stack.
358  </P>  </P>
359  <br><a name="SEC6" href="#TOC1">COMPILING A PATTERN</a><br>  <br><a name="SEC7" href="#TOC1">COMPILING A PATTERN</a><br>
360  <P>  <P>
361  <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>
362  <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 378  The pattern is a C string terminated by
378  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
379  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
380  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
381  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.
382  </P>  </P>
383  <P>  <P>
384  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 387  fully relocatable, because it may contai
387  argument, which is an address (see below).  argument, which is an address (see below).
388  </P>  </P>
389  <P>  <P>
390  The <i>options</i> argument contains independent bits that affect the  The <i>options</i> argument contains various bit settings that affect the
391  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
392  options are described below. Some of them, in particular, those that are  options are described below. Some of them, in particular, those that are
393  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 395  the detailed description in the
395  <a href="pcrepattern.html"><b>pcrepattern</b></a>  <a href="pcrepattern.html"><b>pcrepattern</b></a>
396  documentation). For these options, the contents of the <i>options</i> argument  documentation). For these options, the contents of the <i>options</i> argument
397  specifies their initial settings at the start of compilation and execution. The  specifies their initial settings at the start of compilation and execution. The
398  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
399  time.  matching as well as at compile time.
400  </P>  </P>
401  <P>  <P>
402  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.
403  Otherwise, if compilation of a pattern fails, <b>pcre_compile()</b> returns  Otherwise, if compilation of a pattern fails, <b>pcre_compile()</b> returns
404  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
405  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
406  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
407    where the error was discovered is placed in the variable pointed to by
408  <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.
409  </P>  </P>
410  <P>  <P>
# Line 424  with UTF-8 support. Line 469  with UTF-8 support.
469  </pre>  </pre>
470  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
471  end of the subject string. Without this option, a dollar also matches  end of the subject string. Without this option, a dollar also matches
472  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
473  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.
474  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
475  a pattern.  pattern.
476  <pre>  <pre>
477    PCRE_DOTALL    PCRE_DOTALL
478  </pre>  </pre>
479  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,
480  including newlines. Without it, newlines are excluded. This option is  including those that indicate newline. Without it, a dot does not match when
481  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
482  (?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
483  character, independent of the setting of this option.  negative class such as [^a] always matches newline characters, independent of
484    the setting of this option.
485    <pre>
486      PCRE_DUPNAMES
487    </pre>
488    If this bit is set, names used to identify capturing subpatterns need not be
489    unique. This can be helpful for certain types of pattern when it is known that
490    only one instance of the named subpattern can ever be matched. There are more
491    details of named subpatterns below; see also the
492    <a href="pcrepattern.html"><b>pcrepattern</b></a>
493    documentation.
494  <pre>  <pre>
495    PCRE_EXTENDED    PCRE_EXTENDED
496  </pre>  </pre>
497  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
498  ignored except when escaped or inside a character class. Whitespace does not  ignored except when escaped or inside a character class. Whitespace does not
499  include the VT character (code 11). In addition, characters between an  include the VT character (code 11). In addition, characters between an
500  unescaped # outside a character class and the next newline character,  unescaped # outside a character class and the next newline, inclusive, are also
501  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
502  be changed within a pattern by a (?x) option setting.  pattern by a (?x) option setting.
503  </P>  </P>
504  <P>  <P>
505  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 514  that is incompatible with Perl, but it i
514  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
515  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
516  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
517  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
518  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
519  pattern.  this option. It can also be set by a (?X) option setting within a pattern.
520  <pre>  <pre>
521    PCRE_FIRSTLINE    PCRE_FIRSTLINE
522  </pre>  </pre>
523  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
524  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
525  continue over the newline.  over the newline.
526  <pre>  <pre>
527    PCRE_MULTILINE    PCRE_MULTILINE
528  </pre>  </pre>
# Line 480  Perl. Line 535  Perl.
535  </P>  </P>
536  <P>  <P>
537  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
538  match immediately following or immediately before any newline in the subject  match immediately following or immediately before internal newlines in the
539  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
540  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
541  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
542  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.
543  <pre>  <pre>
544      PCRE_NEWLINE_CR
545      PCRE_NEWLINE_LF
546      PCRE_NEWLINE_CRLF
547      PCRE_NEWLINE_ANY
548    </pre>
549    These options override the default newline definition that was chosen when PCRE
550    was built. Setting the first or the second specifies that a newline is
551    indicated by a single character (CR or LF, respectively). Setting
552    PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
553    CRLF sequence. Setting PCRE_NEWLINE_ANY specifies that any Unicode newline
554    sequence should be recognized. The Unicode newline sequences are the three just
555    mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed,
556    U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
557    (paragraph separator, U+2029). The last two are recognized only in UTF-8 mode.
558    </P>
559    <P>
560    The newline setting in the options word uses three bits that are treated
561    as a number, giving eight possibilities. Currently only five are used (default
562    plus the four values above). This means that if you set more than one newline
563    option, the combination may or may not be sensible. For example,
564    PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
565    other combinations yield unused numbers and cause an error.
566    </P>
567    <P>
568    The only time that a line break is specially recognized when compiling a
569    pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character
570    class is encountered. This indicates a comment that lasts until after the next
571    line break sequence. In other circumstances, line break sequences are treated
572    as literal data, except that in PCRE_EXTENDED mode, both CR and LF are treated
573    as whitespace characters and are therefore ignored.
574    </P>
575    <P>
576    The newline option that is set at compile time becomes the default that is used
577    for <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>, but it can be overridden.
578    <pre>
579    PCRE_NO_AUTO_CAPTURE    PCRE_NO_AUTO_CAPTURE
580  </pre>  </pre>
581  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 614  Note that this option can also be passed
614  <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
615  strings.  strings.
616  </P>  </P>
617  <br><a name="SEC7" href="#TOC1">COMPILATION ERROR CODES</a><br>  <br><a name="SEC8" href="#TOC1">COMPILATION ERROR CODES</a><br>
618  <P>  <P>
619  The following table lists the error codes than may be returned by  The following table lists the error codes than may be returned by
620  <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
621  both compiling functions.  both compiling functions. As PCRE has developed, some error codes have fallen
622    out of use. To avoid confusion, they have not been re-used.
623  <pre>  <pre>
624     0  no error     0  no error
625     1  \ at end of pattern     1  \ at end of pattern
# Line 540  both compiling functions. Line 631  both compiling functions.
631     7  invalid escape sequence in character class     7  invalid escape sequence in character class
632     8  range out of order in character class     8  range out of order in character class
633     9  nothing to repeat     9  nothing to repeat
634    10  operand of unlimited repeat could match the empty string    10  [this code is not in use]
635    11  internal error: unexpected repeat    11  internal error: unexpected repeat
636    12  unrecognized character after (?    12  unrecognized character after (?
637    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 640  both compiling functions.
640    16  erroffset passed as NULL    16  erroffset passed as NULL
641    17  unknown option bit(s) set    17  unknown option bit(s) set
642    18  missing ) after comment    18  missing ) after comment
643    19  parentheses nested too deeply    19  [this code is not in use]
644    20  regular expression too large    20  regular expression too large
645    21  failed to get memory    21  failed to get memory
646    22  unmatched parentheses    22  unmatched parentheses
647    23  internal error: code overflow    23  internal error: code overflow
648    24  unrecognized character after (?&#60;    24  unrecognized character after (?&#60;
649    25  lookbehind assertion is not fixed length    25  lookbehind assertion is not fixed length
650    26  malformed number after (?(    26  malformed number or name after (?(
651    27  conditional group contains more than two branches    27  conditional group contains more than two branches
652    28  assertion expected after (?(    28  assertion expected after (?(
653    29  (?R or (?digits must be followed by )    29  (?R or (?digits must be followed by )
654    30  unknown POSIX class name    30  unknown POSIX class name
655    31  POSIX collating elements are not supported    31  POSIX collating elements are not supported
656    32  this version of PCRE is not compiled with PCRE_UTF8 support    32  this version of PCRE is not compiled with PCRE_UTF8 support
657    33  spare error    33  [this code is not in use]
658    34  character value in \x{...} sequence is too large    34  character value in \x{...} sequence is too large
659    35  invalid condition (?(0)    35  invalid condition (?(0)
660    36  \C not allowed in lookbehind assertion    36  \C not allowed in lookbehind assertion
# Line 572  both compiling functions. Line 663  both compiling functions.
663    39  closing ) for (?C expected    39  closing ) for (?C expected
664    40  recursive call could loop indefinitely    40  recursive call could loop indefinitely
665    41  unrecognized character after (?P    41  unrecognized character after (?P
666    42  syntax error after (?P    42  syntax error in subpattern name (missing terminator)
667    43  two named groups have the same name    43  two named subpatterns have the same name
668    44  invalid UTF-8 string    44  invalid UTF-8 string
669    45  support for \P, \p, and \X has not been compiled    45  support for \P, \p, and \X has not been compiled
670    46  malformed \P or \p sequence    46  malformed \P or \p sequence
671    47  unknown property name after \P or \p    47  unknown property name after \P or \p
672      48  subpattern name is too long (maximum 32 characters)
673      49  too many named subpatterns (maximum 10,000)
674      50  repeated subpattern is too long
675      51  octal value is greater than \377 (not in UTF-8 mode)
676      52  internal error: overran compiling workspace
677      53  internal error: previously-checked referenced subpattern not found
678      54  DEFINE group contains more than one branch
679      55  repeating a DEFINE group is not allowed
680      56  inconsistent NEWLINE options"
681  </PRE>  </PRE>
682  </P>  </P>
683  <br><a name="SEC8" href="#TOC1">STUDYING A PATTERN</a><br>  <br><a name="SEC9" href="#TOC1">STUDYING A PATTERN</a><br>
684  <P>  <P>
685  <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>
686  <b>const char **<i>errptr</i>);</b>  <b>const char **<i>errptr</i>);</b>
# Line 615  options are defined, and this argument s Line 715  options are defined, and this argument s
715  <P>  <P>
716  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
717  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
718  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
719  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
720  be sure that it has run successfully.  should test the error pointer for NULL after calling <b>pcre_study()</b>, to be
721    sure that it has run successfully.
722  </P>  </P>
723  <P>  <P>
724  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 733  At present, studying a pattern is useful
733  not have a single fixed starting character. A bitmap of possible starting  not have a single fixed starting character. A bitmap of possible starting
734  bytes is created.  bytes is created.
735  <a name="localesupport"></a></P>  <a name="localesupport"></a></P>
736  <br><a name="SEC9" href="#TOC1">LOCALE SUPPORT</a><br>  <br><a name="SEC10" href="#TOC1">LOCALE SUPPORT</a><br>
737  <P>  <P>
738  PCRE handles caseless matching, and determines whether characters are letters  PCRE handles caseless matching, and determines whether characters are letters
739  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
740  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
741  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
742  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
743  support.  support. The use of locales with Unicode is discouraged.
744  </P>  </P>
745  <P>  <P>
746  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 781  this facility could be used to match a p
781  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
782  below in the section on matching a pattern.  below in the section on matching a pattern.
783  </P>  </P>
784  <br><a name="SEC10" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br>  <br><a name="SEC11" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br>
785  <P>  <P>
786  <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>
787  <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 809  check against passing an arbitrary memor
809  <b>pcre_fullinfo()</b>, to obtain the length of the compiled pattern:  <b>pcre_fullinfo()</b>, to obtain the length of the compiled pattern:
810  <pre>  <pre>
811    int rc;    int rc;
812    unsigned long int length;    size_t length;
813    rc = pcre_fullinfo(    rc = pcre_fullinfo(
814      re,               /* result of pcre_compile() */      re,               /* result of pcre_compile() */
815      pe,               /* result of pcre_study(), or NULL */      pe,               /* result of pcre_study(), or NULL */
# Line 740  a NULL table pointer. Line 841  a NULL table pointer.
841    PCRE_INFO_FIRSTBYTE    PCRE_INFO_FIRSTBYTE
842  </pre>  </pre>
843  Return information about the first byte of any matched string, for a  Return information about the first byte of any matched string, for a
844  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>
845  old name is still recognized for backwards compatibility.)  variable. (This option used to be called PCRE_INFO_FIRSTCHAR; the old name is
846    still recognized for backwards compatibility.)
847  </P>  </P>
848  <P>  <P>
849  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
850  (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  
851  <br>  <br>
852  <br>  <br>
853  (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 885  is -1.
885  </pre>  </pre>
886  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
887  names are just an additional way of identifying the parentheses, which still  names are just an additional way of identifying the parentheses, which still
888  acquire numbers. A convenience function called <b>pcre_get_named_substring()</b>  acquire numbers. Several convenience functions such as
889  is provided for extracting an individual captured substring by name. It is also  <b>pcre_get_named_substring()</b> are provided for extracting captured
890  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
891  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
892  <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,
893  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
894    values.
895  </P>  </P>
896  <P>  <P>
897  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 901  length of the longest name. PCRE_INFO_NA
901  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
902  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
903  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
904  alphabetical order. For example, consider the following pattern (assume  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of
905    their parentheses numbers. For example, consider the following pattern (assume
906  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  PCRE_EXTENDED is set, so white space - including newlines - is ignored):
907  <pre>  <pre>
908    (?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) )
909  </pre>  </pre>
910  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
911  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 917  bytes shows in hexadecimal, and undefine
917    00 02 y  e  a  r  00 ??    00 02 y  e  a  r  00 ??
918  </pre>  </pre>
919  When writing code to extract data from named subpatterns using the  When writing code to extract data from named subpatterns using the
920  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
921  different for each compiled pattern.  different for each compiled pattern.
922  <pre>  <pre>
923    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
# Line 851  a <b>pcre_extra</b> block. That is, it i Line 954  a <b>pcre_extra</b> block. That is, it i
954  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
955  <b>size_t</b> variable.  <b>size_t</b> variable.
956  </P>  </P>
957  <br><a name="SEC11" href="#TOC1">OBSOLETE INFO FUNCTION</a><br>  <br><a name="SEC12" href="#TOC1">OBSOLETE INFO FUNCTION</a><br>
958  <P>  <P>
959  <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>
960  <b>*<i>firstcharptr</i>);</b>  <b>*<i>firstcharptr</i>);</b>
# Line 875  If the pattern is not anchored and the < Line 978  If the pattern is not anchored and the <
978  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
979  string (see PCRE_INFO_FIRSTBYTE above).  string (see PCRE_INFO_FIRSTBYTE above).
980  </P>  </P>
981  <br><a name="SEC12" href="#TOC1">REFERENCE COUNTS</a><br>  <br><a name="SEC13" href="#TOC1">REFERENCE COUNTS</a><br>
982  <P>  <P>
983  <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>
984  </P>  </P>
# Line 899  Except when it is zero, the reference co Line 1002  Except when it is zero, the reference co
1002  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
1003  is different. (This seems a highly unlikely scenario.)  is different. (This seems a highly unlikely scenario.)
1004  </P>  </P>
1005  <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>
1006  <P>  <P>
1007  <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>
1008  <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 1050  Extra data for <b>pcre_exec()</b>
1050  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>
1051  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
1052  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
1053  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
1054  follows:  fields (not necessarily in this order):
1055  <pre>  <pre>
1056    unsigned long int <i>flags</i>;    unsigned long int <i>flags</i>;
1057    void *<i>study_data</i>;    void *<i>study_data</i>;
1058    unsigned long int <i>match_limit</i>;    unsigned long int <i>match_limit</i>;
1059      unsigned long int <i>match_limit_recursion</i>;
1060    void *<i>callout_data</i>;    void *<i>callout_data</i>;
1061    const unsigned char *<i>tables</i>;    const unsigned char *<i>tables</i>;
1062  </pre>  </pre>
# Line 961  are set. The flag bits are: Line 1065  are set. The flag bits are:
1065  <pre>  <pre>
1066    PCRE_EXTRA_STUDY_DATA    PCRE_EXTRA_STUDY_DATA
1067    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1068      PCRE_EXTRA_MATCH_LIMIT_RECURSION
1069    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1070    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1071  </pre>  </pre>
# Line 977  classic example is the use of nested unl Line 1082  classic example is the use of nested unl
1082  </P>  </P>
1083  <P>  <P>
1084  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
1085  (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
1086  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
1087  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
1088  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
1089    string.
1090  </P>  </P>
1091  <P>  <P>
1092  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
1093  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
1094  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>
1095  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
1096  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
1097  exceeded, <b>pcre_exec()</b> returns PCRE_ERROR_MATCHLIMIT.  PCRE_ERROR_MATCHLIMIT.
1098    </P>
1099    <P>
1100    The <i>match_limit_recursion</i> field is similar to <i>match_limit</i>, but
1101    instead of limiting the total number of times that <b>match()</b> is called, it
1102    limits the depth of recursion. The recursion depth is a smaller number than the
1103    total number of calls, because not all calls to <b>match()</b> are recursive.
1104    This limit is of use only if it is set smaller than <i>match_limit</i>.
1105    </P>
1106    <P>
1107    Limiting the recursion depth limits the amount of stack that can be used, or,
1108    when PCRE has been compiled to use memory on the heap instead of the stack, the
1109    amount of heap memory that can be used.
1110    </P>
1111    <P>
1112    The default value for <i>match_limit_recursion</i> can be set when PCRE is
1113    built; the default default is the same value as the default for
1114    <i>match_limit</i>. You can override the default by suppling <b>pcre_exec()</b>
1115    with a <b>pcre_extra</b> block in which <i>match_limit_recursion</i> is set, and
1116    PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the <i>flags</i> field. If the limit
1117    is exceeded, <b>pcre_exec()</b> returns PCRE_ERROR_RECURSIONLIMIT.
1118  </P>  </P>
1119  <P>  <P>
1120  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 1140  Option bits for <b>pcre_exec()</b>
1140  </b><br>  </b><br>
1141  <P>  <P>
1142  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
1143  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>,
1144  PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.
1145  <pre>  <pre>
1146    PCRE_ANCHORED    PCRE_ANCHORED
1147  </pre>  </pre>
# Line 1024  matching position. If a pattern was comp Line 1150  matching position. If a pattern was comp
1150  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
1151  matching time.  matching time.
1152  <pre>  <pre>
1153      PCRE_NEWLINE_CR
1154      PCRE_NEWLINE_LF
1155      PCRE_NEWLINE_CRLF
1156      PCRE_NEWLINE_ANY
1157    </pre>
1158    These options override the newline definition that was chosen or defaulted when
1159    the pattern was compiled. For details, see the description of
1160    <b>pcre_compile()</b> above. During matching, the newline choice affects the
1161    behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1162    the way the match position is advanced after a match failure for an unanchored
1163    pattern. When PCRE_NEWLINE_CRLF or PCRE_NEWLINE_ANY is set, and a match attempt
1164    fails when the current position is at a CRLF sequence, the match position is
1165    advanced by two characters instead of one, in other words, to after the CRLF.
1166    <pre>
1167    PCRE_NOTBOL    PCRE_NOTBOL
1168  </pre>  </pre>
1169  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 1302  is set to the offset of the first charac
1302  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
1303  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
1304  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>
1305  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
1306  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
1307  just the first pair of offsets has been set.  capturing subpatterns, the return value from a successful match is 1,
1308  </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.  
1309  </P>  </P>
1310  <P>  <P>
1311  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 1322  has to get additional memory for use dur
1322  advisable to supply an <i>ovector</i>.  advisable to supply an <i>ovector</i>.
1323  </P>  </P>
1324  <P>  <P>
1325  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
1326  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1327  <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
1328  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.
1329    </P>
1330    <P>
1331    It is possible for capturing subpattern number <i>n+1</i> to match some part of
1332    the subject when subpattern <i>n</i> has not been used at all. For example, if
1333    the string "abc" is matched against the pattern (a|(z))(bc) the return from the
1334    function is 4, and subpatterns 1 and 3 are matched, but 2 is not. When this
1335    happens, both values in the offset pairs corresponding to unused subpatterns
1336    are set to -1.
1337    </P>
1338    <P>
1339    Offset values that correspond to unused subpatterns at the end of the
1340    expression are also set to -1. For example, if the string "abc" is matched
1341    against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
1342    return from the function is 2, because the highest used capturing subpattern
1343    number is 1. However, you can refer to the offsets for the second and third
1344    capturing subpatterns if you wish (assuming the vector is large enough, of
1345    course).
1346    </P>
1347    <P>
1348    Some convenience functions are provided for extracting the captured substrings
1349    as separate strings. These are described below.
1350  <a name="errorlist"></a></P>  <a name="errorlist"></a></P>
1351  <br><b>  <br><b>
1352  Return values from <b>pcre_exec()</b>  Error return values from <b>pcre_exec()</b>
1353  </b><br>  </b><br>
1354  <P>  <P>
1355  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 1376  compiled in an environment of one endian
1376  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
1377  not present.  not present.
1378  <pre>  <pre>
1379    PCRE_ERROR_UNKNOWN_NODE   (-5)    PCRE_ERROR_UNKNOWN_OPCODE (-5)
1380  </pre>  </pre>
1381  While running the pattern match, an unknown item was encountered in the  While running the pattern match, an unknown item was encountered in the
1382  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 1398  below). It is never returned by <b>pcre_
1398  <pre>  <pre>
1399    PCRE_ERROR_MATCHLIMIT     (-8)    PCRE_ERROR_MATCHLIMIT     (-8)
1400  </pre>  </pre>
1401  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
1402  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
1403  description above.  above.
1404  <pre>  <pre>
1405    PCRE_ERROR_CALLOUT        (-9)    PCRE_ERROR_CALLOUT        (-9)
1406  </pre>  </pre>
# Line 1288  in PCRE or by overwriting of the compile Line 1439  in PCRE or by overwriting of the compile
1439    PCRE_ERROR_BADCOUNT       (-15)    PCRE_ERROR_BADCOUNT       (-15)
1440  </pre>  </pre>
1441  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.
1442    <pre>
1443      PCRE_ERROR_RECURSIONLIMIT (-21)
1444    </pre>
1445    The internal recursion limit, as specified by the <i>match_limit_recursion</i>
1446    field in a <b>pcre_extra</b> structure (or defaulted) was reached. See the
1447    description above.
1448    <pre>
1449      PCRE_ERROR_NULLWSLIMIT    (-22)
1450    </pre>
1451    When a group that can match an empty substring is repeated with an unbounded
1452    upper limit, the subject position at the start of the group must be remembered,
1453    so that a test for an empty string can be made when the end of the group is
1454    reached. Some workspace is required for this; if it runs out, this error is
1455    given.
1456    <pre>
1457      PCRE_ERROR_BADNEWLINE     (-23)
1458    </pre>
1459    An invalid combination of PCRE_NEWLINE_<i>xxx</i> options was given.
1460  </P>  </P>
1461  <br><a name="SEC14" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>  <P>
1462    Error numbers -16 to -20 are not used by <b>pcre_exec()</b>.
1463    </P>
1464    <br><a name="SEC15" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>
1465  <P>  <P>
1466  <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>
1467  <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 1483  Captured substrings can be accessed dire
1483  <b>pcre_get_substring_list()</b> are provided for extracting captured substrings  <b>pcre_get_substring_list()</b> are provided for extracting captured substrings
1484  as new, separate, zero-terminated strings. These functions identify substrings  as new, separate, zero-terminated strings. These functions identify substrings
1485  by number. The next section describes functions for extracting named  by number. The next section describes functions for extracting named
1486  substrings. A substring that contains a binary zero is correctly extracted and  substrings.
1487  has a further zero added on the end, but the result is not, of course,  </P>
1488  a C string.  <P>
1489    A substring that contains a binary zero is correctly extracted and has a
1490    further zero added on the end, but the result is not, of course, a C string.
1491    However, you can process such a string by referring to the length that is
1492    returned by <b>pcre_copy_substring()</b> and <b>pcre_get_substring()</b>.
1493    Unfortunately, the interface to <b>pcre_get_substring_list()</b> is not adequate
1494    for handling strings containing binary zeros, because the end of the final
1495    string is not independently indicated.
1496  </P>  </P>
1497  <P>  <P>
1498  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 1514  the string is placed in <i>buffer</i>, w
1514  <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
1515  obtained via <b>pcre_malloc</b>, and its address is returned via  obtained via <b>pcre_malloc</b>, and its address is returned via
1516  <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
1517  including the terminating zero, or one of  including the terminating zero, or one of these error codes:
1518  <pre>  <pre>
1519    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1520  </pre>  </pre>
# Line 1352  and builds a list of pointers to them. A Line 1531  and builds a list of pointers to them. A
1531  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
1532  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
1533  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
1534  function is zero if all went well, or  function is zero if all went well, or the error code
1535  <pre>  <pre>
1536    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1537  </pre>  </pre>
# Line 1373  a previous call of <b>pcre_get_substring Line 1552  a previous call of <b>pcre_get_substring
1552  <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
1553  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
1554  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
1555  linked via a special interface to another programming language which cannot use  linked via a special interface to another programming language that cannot use
1556  <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
1557  provided.  provided.
1558  </P>  </P>
1559  <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>
1560  <P>  <P>
1561  <b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b>  <b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b>
1562  <b>const char *<i>name</i>);</b>  <b>const char *<i>name</i>);</b>
# Line 1400  For example, for this pattern Line 1579  For example, for this pattern
1579  <pre>  <pre>
1580    (a+)b(?&#60;xxx&#62;\d+)...    (a+)b(?&#60;xxx&#62;\d+)...
1581  </pre>  </pre>
1582  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
1583  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
1584  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
1585    pattern, and the second is the name. The yield of the function is the
1586  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
1587  that name.  that name.
1588  </P>  </P>
# Line 1412  functions described in the previous sect Line 1592  functions described in the previous sect
1592  two functions that do the whole job.  two functions that do the whole job.
1593  </P>  </P>
1594  <P>  <P>
1595  Most of the arguments of <i>pcre_copy_named_substring()</i> and  Most of the arguments of <b>pcre_copy_named_substring()</b> and
1596  <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
1597  functions that extract by number. As these are described in the previous  functions that extract by number. As these are described in the previous
1598  section, they are not re-described here. There are just two differences:  section, they are not re-described here. There are just two differences:
1599  </P>  </P>
# Line 1428  These functions call <b>pcre_get_stringn Line 1608  These functions call <b>pcre_get_stringn
1608  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
1609  appropriate.  appropriate.
1610  </P>  </P>
1611  <br><a name="SEC16" href="#TOC1">FINDING ALL POSSIBLE MATCHES</a><br>  <br><a name="SEC17" href="#TOC1">DUPLICATE SUBPATTERN NAMES</a><br>
1612    <P>
1613    <b>int pcre_get_stringtable_entries(const pcre *<i>code</i>,</b>
1614    <b>const char *<i>name</i>, char **<i>first</i>, char **<i>last</i>);</b>
1615    </P>
1616    <P>
1617    When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
1618    are not required to be unique. Normally, patterns with duplicate names are such
1619    that in any one match, only one of the named subpatterns participates. An
1620    example is shown in the
1621    <a href="pcrepattern.html"><b>pcrepattern</b></a>
1622    documentation. When duplicates are present, <b>pcre_copy_named_substring()</b>
1623    and <b>pcre_get_named_substring()</b> return the first substring corresponding
1624    to the given name that is set. If none are set, an empty string is returned.
1625    The <b>pcre_get_stringnumber()</b> function returns one of the numbers that are
1626    associated with the name, but it is not defined which it is.
1627    <br>
1628    <br>
1629    If you want to get full details of all captured substrings for a given name,
1630    you must use the <b>pcre_get_stringtable_entries()</b> function. The first
1631    argument is the compiled pattern, and the second is the name. The third and
1632    fourth are pointers to variables which are updated by the function. After it
1633    has run, they point to the first and last entries in the name-to-number table
1634    for the given name. The function itself returns the length of each entry, or
1635    PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
1636    described above in the section entitled <i>Information about a pattern</i>.
1637    Given all the relevant entries for the name, you can extract each of their
1638    numbers, and hence the captured data, if any.
1639    </P>
1640    <br><a name="SEC18" href="#TOC1">FINDING ALL POSSIBLE MATCHES</a><br>
1641  <P>  <P>
1642  The traditional matching function uses a similar algorithm to Perl, which stops  The traditional matching function uses a similar algorithm to Perl, which stops
1643  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 1656  substring. Then return 1, which forces <
1656  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>
1657  will yield PCRE_ERROR_NOMATCH.  will yield PCRE_ERROR_NOMATCH.
1658  <a name="dfamatch"></a></P>  <a name="dfamatch"></a></P>
1659  <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>
1660  <P>  <P>
1661  <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>
1662  <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 1665  will yield PCRE_ERROR_NOMATCH.
1665  </P>  </P>
1666  <P>  <P>
1667  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
1668  a compiled pattern, using a "DFA" matching algorithm. This has different  a compiled pattern, using a matching algorithm that scans the subject string
1669  characteristics to the normal algorithm, and is not compatible with Perl. Some  just once, and does not backtrack. This has different characteristics to the
1670  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
1671  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
1672  matching algorithms, see the  matching can be useful. For a discussion of the two matching algorithms, see
1673    the
1674  <a href="pcrematching.html"><b>pcrematching</b></a>  <a href="pcrematching.html"><b>pcrematching</b></a>
1675  documentation.  documentation.
1676  </P>  </P>
# Line 1475  here. Line 1685  here.
1685  The two additional arguments provide workspace for the function. The workspace  The two additional arguments provide workspace for the function. The workspace
1686  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
1687  multiple paths through the pattern tree. More workspace will be needed for  multiple paths through the pattern tree. More workspace will be needed for
1688  patterns and subjects where there are a lot of possible matches.  patterns and subjects where there are a lot of potential matches.
1689  </P>  </P>
1690  <P>  <P>
1691  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>:
1692  <pre>  <pre>
1693    int rc;    int rc;
1694    int ovector[10];    int ovector[10];
1695    int wspace[20];    int wspace[20];
1696    rc = pcre_exec(    rc = pcre_dfa_exec(
1697      re,             /* result of pcre_compile() */      re,             /* result of pcre_compile() */
1698      NULL,           /* we didn't study the pattern */      NULL,           /* we didn't study the pattern */
1699      "some string",  /* the subject string */      "some string",  /* the subject string */
# Line 1501  Option bits for <b>pcre_dfa_exec()</b> Line 1711  Option bits for <b>pcre_dfa_exec()</b>
1711  </b><br>  </b><br>
1712  <P>  <P>
1713  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
1714  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>,
1715  PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,
1716  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
1717  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.
1718  <pre>  <pre>
# Line 1519  matching string. Line 1729  matching string.
1729    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
1730  </pre>  </pre>
1731  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
1732  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
1733  this is necessarily the shortest possible match at the first possible matching  works, this is necessarily the shortest possible match at the first possible
1734  point in the subject string.  matching point in the subject string.
1735  <pre>  <pre>
1736    PCRE_DFA_RESTART    PCRE_DFA_RESTART
1737  </pre>  </pre>
# Line 1559  the three matched strings are Line 1769  the three matched strings are
1769  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
1770  the number of matched substrings. The substrings themselves are returned in  the number of matched substrings. The substrings themselves are returned in
1771  <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
1772  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
1773  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,
1774  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>
1775  data, even though the meaning of the strings is different.)  returns data, even though the meaning of the strings is different.)
1776  </P>  </P>
1777  <P>  <P>
1778  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 1798  that it does not support, for instance,
1798  <pre>  <pre>
1799    PCRE_ERROR_DFA_UCOND      (-17)    PCRE_ERROR_DFA_UCOND      (-17)
1800  </pre>  </pre>
1801  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
1802  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
1803    group. These are not supported.
1804  <pre>  <pre>
1805    PCRE_ERROR_DFA_UMLIMIT    (-18)    PCRE_ERROR_DFA_UMLIMIT    (-18)
1806  </pre>  </pre>
# Line 1609  recursively, using private vectors for < Line 1820  recursively, using private vectors for <
1820  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
1821  extremely rare, as a vector of size 1000 is used.  extremely rare, as a vector of size 1000 is used.
1822  </P>  </P>
1823    <br><a name="SEC20" href="#TOC1">SEE ALSO</a><br>
1824    <P>
1825    <b>pcrebuild</b>(3), <b>pcrecallout</b>(3), <b>pcrecpp(3)</b>(3),
1826    <b>pcrematching</b>(3), <b>pcrepartial</b>(3), <b>pcreposix</b>(3),
1827    <b>pcreprecompile</b>(3), <b>pcresample</b>(3), <b>pcrestack</b>(3).
1828    </P>
1829  <P>  <P>
1830  Last updated: 16 May 2005  Last updated: 30 November 2006
1831  <br>  <br>
1832  Copyright &copy; 1997-2005 University of Cambridge.  Copyright &copy; 1997-2006 University of Cambridge.
1833  <p>  <p>
1834  Return to the <a href="index.html">PCRE index page</a>.  Return to the <a href="index.html">PCRE index page</a>.
1835  </p>  </p>

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