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revision 87 by nigel, Sat Feb 24 21:41:21 2007 UTC revision 182 by ph10, Wed Jun 13 15:09:54 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 pcre_exec(). They are: Line 190  matched by pcre_exec(). 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 five different conventions for indicating line breaks in
250    strings: a single CR (carriage return) character, a single LF (linefeed)
251    character, the two-character sequence CRLF, any of the three preceding, or any
252    Unicode newline sequence. The Unicode newline sequences are the three just
253    mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed,
254    U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
255    (paragraph separator, U+2029).
256    </P>
257    <P>
258    Each of the first three conventions is used by at least one operating system as
259    its standard newline sequence. When PCRE is built, a default can be specified.
260    The default default is LF, which is the Unix standard. When PCRE is run, the
261    default can be overridden, either when a pattern is compiled, or when it is
262    matched.
263    </P>
264    <P>
265    In the PCRE documentation the word "newline" is used to mean "the character or
266    pair of characters that indicate a line break". The choice of newline
267    convention affects the handling of the dot, circumflex, and dollar
268    metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
269    recognized line ending sequence, the match position advancement for a
270    non-anchored pattern. The choice of newline convention does not affect the
271    interpretation of the \n or \r escape sequences.
272    </P>
273    <br><a name="SEC4" href="#TOC1">MULTITHREADING</a><br>
274  <P>  <P>
275  The PCRE functions can be used in multi-threading applications, with the  The PCRE functions can be used in multi-threading applications, with the
276  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 pcre_c Line 281  callout function pointed to by pcre_c
281  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
282  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.
283  </P>  </P>
284  <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>
285  <P>  <P>
286  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
287  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
288  which it was compiled. Details are given in the  which it was compiled. Details are given in the
289  <a href="pcreprecompile.html"><b>pcreprecompile</b></a>  <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
290  documentation.  documentation. However, compiling a regular expression with one version of PCRE
291    for use with a different version is not guaranteed to work and may cause
292    crashes.
293  </P>  </P>
294  <br><a name="SEC5" href="#TOC1">CHECKING BUILD-TIME OPTIONS</a><br>  <br><a name="SEC6" href="#TOC1">CHECKING BUILD-TIME OPTIONS</a><br>
295  <P>  <P>
296  <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>
297  </P>  </P>
# Line 276  properties is available; otherwise it is Line 318  properties is available; otherwise it is
318  <pre>  <pre>
319    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
320  </pre>  </pre>
321  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
322  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
323  should normally be the standard character for your operating system.  are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF, and -1 for ANY. The
324    default should normally be the standard sequence for your operating system.
325  <pre>  <pre>
326    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
327  </pre>  </pre>
# Line 318  of recursive function calls. In this cas Line 361  of recursive function calls. In this cas
361  <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
362  avoiding the use of the stack.  avoiding the use of the stack.
363  </P>  </P>
364  <br><a name="SEC6" href="#TOC1">COMPILING A PATTERN</a><br>  <br><a name="SEC7" href="#TOC1">COMPILING A PATTERN</a><br>
365  <P>  <P>
366  <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>
367  <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b>  <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
# Line 340  The pattern is a C string terminated by Line 383  The pattern is a C string terminated by
383  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
384  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
385  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
386  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.
387  </P>  </P>
388  <P>  <P>
389  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 349  fully relocatable, because it may contai Line 392  fully relocatable, because it may contai
392  argument, which is an address (see below).  argument, which is an address (see below).
393  </P>  </P>
394  <P>  <P>
395  The <i>options</i> argument contains independent bits that affect the  The <i>options</i> argument contains various bit settings that affect the
396  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
397  options are described below. Some of them, in particular, those that are  options are described below. Some of them, in particular, those that are
398  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 357  the detailed description in the Line 400  the detailed description in the
400  <a href="pcrepattern.html"><b>pcrepattern</b></a>  <a href="pcrepattern.html"><b>pcrepattern</b></a>
401  documentation). For these options, the contents of the <i>options</i> argument  documentation). For these options, the contents of the <i>options</i> argument
402  specifies their initial settings at the start of compilation and execution. The  specifies their initial settings at the start of compilation and execution. The
403  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
404  time.  matching as well as at compile time.
405  </P>  </P>
406  <P>  <P>
407  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.
# Line 431  with UTF-8 support. Line 474  with UTF-8 support.
474  </pre>  </pre>
475  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
476  end of the subject string. Without this option, a dollar also matches  end of the subject string. Without this option, a dollar also matches
477  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
478  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.
479  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
480  a pattern.  pattern.
481  <pre>  <pre>
482    PCRE_DOTALL    PCRE_DOTALL
483  </pre>  </pre>
484  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,
485  including newlines. Without it, newlines are excluded. This option is  including those that indicate newline. Without it, a dot does not match when
486  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
487  (?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
488  character, independent of the setting of this option.  negative class such as [^a] always matches newline characters, independent of
489    the setting of this option.
490    <pre>
491      PCRE_DUPNAMES
492    </pre>
493    If this bit is set, names used to identify capturing subpatterns need not be
494    unique. This can be helpful for certain types of pattern when it is known that
495    only one instance of the named subpattern can ever be matched. There are more
496    details of named subpatterns below; see also the
497    <a href="pcrepattern.html"><b>pcrepattern</b></a>
498    documentation.
499  <pre>  <pre>
500    PCRE_EXTENDED    PCRE_EXTENDED
501  </pre>  </pre>
502  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
503  ignored except when escaped or inside a character class. Whitespace does not  ignored except when escaped or inside a character class. Whitespace does not
504  include the VT character (code 11). In addition, characters between an  include the VT character (code 11). In addition, characters between an
505  unescaped # outside a character class and the next newline character,  unescaped # outside a character class and the next newline, inclusive, are also
506  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
507  be changed within a pattern by a (?x) option setting.  pattern by a (?x) option setting.
508  </P>  </P>
509  <P>  <P>
510  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
# Line 466  that is incompatible with Perl, but it i Line 519  that is incompatible with Perl, but it i
519  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
520  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
521  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
522  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
523  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
524  pattern.  this option. It can also be set by a (?X) option setting within a pattern.
525  <pre>  <pre>
526    PCRE_FIRSTLINE    PCRE_FIRSTLINE
527  </pre>  </pre>
528  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
529  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
530  continue over the newline.  over the newline.
531  <pre>  <pre>
532    PCRE_MULTILINE    PCRE_MULTILINE
533  </pre>  </pre>
# Line 487  Perl. Line 540  Perl.
540  </P>  </P>
541  <P>  <P>
542  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
543  match immediately following or immediately before any newline in the subject  match immediately following or immediately before internal newlines in the
544  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
545  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
546  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
547  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.
548  <pre>  <pre>
549      PCRE_NEWLINE_CR
550      PCRE_NEWLINE_LF
551      PCRE_NEWLINE_CRLF
552      PCRE_NEWLINE_ANYCRLF
553      PCRE_NEWLINE_ANY
554    </pre>
555    These options override the default newline definition that was chosen when PCRE
556    was built. Setting the first or the second specifies that a newline is
557    indicated by a single character (CR or LF, respectively). Setting
558    PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
559    CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three
560    preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies
561    that any Unicode newline sequence should be recognized. The Unicode newline
562    sequences are the three just mentioned, plus the single characters VT (vertical
563    tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS (line
564    separator, U+2028), and PS (paragraph separator, U+2029). The last two are
565    recognized only in UTF-8 mode.
566    </P>
567    <P>
568    The newline setting in the options word uses three bits that are treated
569    as a number, giving eight possibilities. Currently only six are used (default
570    plus the five values above). This means that if you set more than one newline
571    option, the combination may or may not be sensible. For example,
572    PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
573    other combinations may yield unused numbers and cause an error.
574    </P>
575    <P>
576    The only time that a line break is specially recognized when compiling a
577    pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character
578    class is encountered. This indicates a comment that lasts until after the next
579    line break sequence. In other circumstances, line break sequences are treated
580    as literal data, except that in PCRE_EXTENDED mode, both CR and LF are treated
581    as whitespace characters and are therefore ignored.
582    </P>
583    <P>
584    The newline option that is set at compile time becomes the default that is used
585    for <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>, but it can be overridden.
586    <pre>
587    PCRE_NO_AUTO_CAPTURE    PCRE_NO_AUTO_CAPTURE
588  </pre>  </pre>
589  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 531  Note that this option can also be passed Line 622  Note that this option can also be passed
622  <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
623  strings.  strings.
624  </P>  </P>
625  <br><a name="SEC7" href="#TOC1">COMPILATION ERROR CODES</a><br>  <br><a name="SEC8" href="#TOC1">COMPILATION ERROR CODES</a><br>
626  <P>  <P>
627  The following table lists the error codes than may be returned by  The following table lists the error codes than may be returned by
628  <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
629  both compiling functions.  both compiling functions. As PCRE has developed, some error codes have fallen
630    out of use. To avoid confusion, they have not been re-used.
631  <pre>  <pre>
632     0  no error     0  no error
633     1  \ at end of pattern     1  \ at end of pattern
# Line 547  both compiling functions. Line 639  both compiling functions.
639     7  invalid escape sequence in character class     7  invalid escape sequence in character class
640     8  range out of order in character class     8  range out of order in character class
641     9  nothing to repeat     9  nothing to repeat
642    10  operand of unlimited repeat could match the empty string    10  [this code is not in use]
643    11  internal error: unexpected repeat    11  internal error: unexpected repeat
644    12  unrecognized character after (?    12  unrecognized character after (?
645    13  POSIX named classes are supported only within a class    13  POSIX named classes are supported only within a class
# Line 556  both compiling functions. Line 648  both compiling functions.
648    16  erroffset passed as NULL    16  erroffset passed as NULL
649    17  unknown option bit(s) set    17  unknown option bit(s) set
650    18  missing ) after comment    18  missing ) after comment
651    19  parentheses nested too deeply    19  [this code is not in use]
652    20  regular expression too large    20  regular expression too large
653    21  failed to get memory    21  failed to get memory
654    22  unmatched parentheses    22  unmatched parentheses
655    23  internal error: code overflow    23  internal error: code overflow
656    24  unrecognized character after (?&#60;    24  unrecognized character after (?&#60;
657    25  lookbehind assertion is not fixed length    25  lookbehind assertion is not fixed length
658    26  malformed number after (?(    26  malformed number or name after (?(
659    27  conditional group contains more than two branches    27  conditional group contains more than two branches
660    28  assertion expected after (?(    28  assertion expected after (?(
661    29  (?R or (?digits must be followed by )    29  (?R or (?[+-]digits must be followed by )
662    30  unknown POSIX class name    30  unknown POSIX class name
663    31  POSIX collating elements are not supported    31  POSIX collating elements are not supported
664    32  this version of PCRE is not compiled with PCRE_UTF8 support    32  this version of PCRE is not compiled with PCRE_UTF8 support
665    33  spare error    33  [this code is not in use]
666    34  character value in \x{...} sequence is too large    34  character value in \x{...} sequence is too large
667    35  invalid condition (?(0)    35  invalid condition (?(0)
668    36  \C not allowed in lookbehind assertion    36  \C not allowed in lookbehind assertion
# Line 579  both compiling functions. Line 671  both compiling functions.
671    39  closing ) for (?C expected    39  closing ) for (?C expected
672    40  recursive call could loop indefinitely    40  recursive call could loop indefinitely
673    41  unrecognized character after (?P    41  unrecognized character after (?P
674    42  syntax error after (?P    42  syntax error in subpattern name (missing terminator)
675    43  two named groups have the same name    43  two named subpatterns have the same name
676    44  invalid UTF-8 string    44  invalid UTF-8 string
677    45  support for \P, \p, and \X has not been compiled    45  support for \P, \p, and \X has not been compiled
678    46  malformed \P or \p sequence    46  malformed \P or \p sequence
679    47  unknown property name after \P or \p    47  unknown property name after \P or \p
680      48  subpattern name is too long (maximum 32 characters)
681      49  too many named subpatterns (maximum 10,000)
682      50  repeated subpattern is too long
683      51  octal value is greater than \377 (not in UTF-8 mode)
684      52  internal error: overran compiling workspace
685      53  internal error: previously-checked referenced subpattern not found
686      54  DEFINE group contains more than one branch
687      55  repeating a DEFINE group is not allowed
688      56  inconsistent NEWLINE options"
689      57  \g is not followed by a braced name or an optionally braced
690            non-zero number
691      58  (?+ or (?- or (?(+ or (?(- must be followed by a non-zero number
692  </PRE>  </PRE>
693  </P>  </P>
694  <br><a name="SEC8" href="#TOC1">STUDYING A PATTERN</a><br>  <br><a name="SEC9" href="#TOC1">STUDYING A PATTERN</a><br>
695  <P>  <P>
696  <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>
697  <b>const char **<i>errptr</i>);</b>  <b>const char **<i>errptr</i>);</b>
# Line 640  At present, studying a pattern is useful Line 744  At present, studying a pattern is useful
744  not have a single fixed starting character. A bitmap of possible starting  not have a single fixed starting character. A bitmap of possible starting
745  bytes is created.  bytes is created.
746  <a name="localesupport"></a></P>  <a name="localesupport"></a></P>
747  <br><a name="SEC9" href="#TOC1">LOCALE SUPPORT</a><br>  <br><a name="SEC10" href="#TOC1">LOCALE SUPPORT</a><br>
748  <P>  <P>
749  PCRE handles caseless matching, and determines whether characters are letters  PCRE handles caseless matching, and determines whether characters are letters,
750  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
751  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
752  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
753  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
754  support. The use of locales with Unicode is discouraged.  support. The use of locales with Unicode is discouraged. If you are handling
755  </P>  characters with codes greater than 128, you should either use UTF-8 and
756  <P>  Unicode, or use locales, but not try to mix the two.
757  An internal set of tables is created in the default C locale when PCRE is  </P>
758  built. This is used when the final argument of <b>pcre_compile()</b> is NULL,  <P>
759  and is sufficient for many applications. An alternative set of tables can,  PCRE contains an internal set of tables that are used when the final argument
760  however, be supplied. These may be created in a different locale from the  of <b>pcre_compile()</b> is NULL. These are sufficient for many applications.
761  default. As more and more applications change to using Unicode, the need for  Normally, the internal tables recognize only ASCII characters. However, when
762  this locale support is expected to die away.  PCRE is built, it is possible to cause the internal tables to be rebuilt in the
763    default "C" locale of the local system, which may cause them to be different.
764    </P>
765    <P>
766    The internal tables can always be overridden by tables supplied by the
767    application that calls PCRE. These may be created in a different locale from
768    the default. As more and more applications change to using Unicode, the need
769    for this locale support is expected to die away.
770  </P>  </P>
771  <P>  <P>
772  External tables are built by calling the <b>pcre_maketables()</b> function,  External tables are built by calling the <b>pcre_maketables()</b> function,
# Line 669  the following code could be used: Line 780  the following code could be used:
780    tables = pcre_maketables();    tables = pcre_maketables();
781    re = pcre_compile(..., tables);    re = pcre_compile(..., tables);
782  </pre>  </pre>
783    The locale name "fr_FR" is used on Linux and other Unix-like systems; if you
784    are using Windows, the name for the French locale is "french".
785    </P>
786    <P>
787  When <b>pcre_maketables()</b> runs, the tables are built in memory that is  When <b>pcre_maketables()</b> runs, the tables are built in memory that is
788  obtained via <b>pcre_malloc</b>. It is the caller's responsibility to ensure  obtained via <b>pcre_malloc</b>. It is the caller's responsibility to ensure
789  that the memory containing the tables remains available for as long as it is  that the memory containing the tables remains available for as long as it is
# Line 688  this facility could be used to match a p Line 803  this facility could be used to match a p
803  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
804  below in the section on matching a pattern.  below in the section on matching a pattern.
805  </P>  </P>
806  <br><a name="SEC10" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br>  <br><a name="SEC11" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br>
807  <P>  <P>
808  <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>
809  <b>int <i>what</i>, void *<i>where</i>);</b>  <b>int <i>what</i>, void *<i>where</i>);</b>
# Line 716  check against passing an arbitrary memor Line 831  check against passing an arbitrary memor
831  <b>pcre_fullinfo()</b>, to obtain the length of the compiled pattern:  <b>pcre_fullinfo()</b>, to obtain the length of the compiled pattern:
832  <pre>  <pre>
833    int rc;    int rc;
834    unsigned long int length;    size_t length;
835    rc = pcre_fullinfo(    rc = pcre_fullinfo(
836      re,               /* result of pcre_compile() */      re,               /* result of pcre_compile() */
837      pe,               /* result of pcre_study(), or NULL */      pe,               /* result of pcre_study(), or NULL */
# Line 748  a NULL table pointer. Line 863  a NULL table pointer.
863    PCRE_INFO_FIRSTBYTE    PCRE_INFO_FIRSTBYTE
864  </pre>  </pre>
865  Return information about the first byte of any matched string, for a  Return information about the first byte of any matched string, for a
866  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>
867  old name is still recognized for backwards compatibility.)  variable. (This option used to be called PCRE_INFO_FIRSTCHAR; the old name is
868    still recognized for backwards compatibility.)
869  </P>  </P>
870  <P>  <P>
871  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
872  (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  
873  <br>  <br>
874  <br>  <br>
875  (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 776  table indicating a fixed set of bytes fo Line 891  table indicating a fixed set of bytes fo
891  string, a pointer to the table is returned. Otherwise NULL is returned. The  string, a pointer to the table is returned. Otherwise NULL is returned. The
892  fourth argument should point to an <b>unsigned char *</b> variable.  fourth argument should point to an <b>unsigned char *</b> variable.
893  <pre>  <pre>
894      PCRE_INFO_JCHANGED
895    </pre>
896    Return 1 if the (?J) option setting is used in the pattern, otherwise 0. The
897    fourth argument should point to an <b>int</b> variable. The (?J) internal option
898    setting changes the local PCRE_DUPNAMES option.
899    <pre>
900    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
901  </pre>  </pre>
902  Return the value of the rightmost literal byte that must exist in any matched  Return the value of the rightmost literal byte that must exist in any matched
# Line 792  is -1. Line 913  is -1.
913  </pre>  </pre>
914  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
915  names are just an additional way of identifying the parentheses, which still  names are just an additional way of identifying the parentheses, which still
916  acquire numbers. A convenience function called <b>pcre_get_named_substring()</b>  acquire numbers. Several convenience functions such as
917  is provided for extracting an individual captured substring by name. It is also  <b>pcre_get_named_substring()</b> are provided for extracting captured
918  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
919  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
920  <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,
921  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
922    values.
923  </P>  </P>
924  <P>  <P>
925  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 807  length of the longest name. PCRE_INFO_NA Line 929  length of the longest name. PCRE_INFO_NA
929  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
930  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
931  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
932  alphabetical order. For example, consider the following pattern (assume  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of
933    their parentheses numbers. For example, consider the following pattern (assume
934  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  PCRE_EXTENDED is set, so white space - including newlines - is ignored):
935  <pre>  <pre>
936    (?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) )
937  </pre>  </pre>
938  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
939  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 822  bytes shows in hexadecimal, and undefine Line 945  bytes shows in hexadecimal, and undefine
945    00 02 y  e  a  r  00 ??    00 02 y  e  a  r  00 ??
946  </pre>  </pre>
947  When writing code to extract data from named subpatterns using the  When writing code to extract data from named subpatterns using the
948  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
949  different for each compiled pattern.  different for each compiled pattern.
950  <pre>  <pre>
951      PCRE_INFO_OKPARTIAL
952    </pre>
953    Return 1 if the pattern can be used for partial matching, otherwise 0. The
954    fourth argument should point to an <b>int</b> variable. The
955    <a href="pcrepartial.html"><b>pcrepartial</b></a>
956    documentation lists the restrictions that apply to patterns when partial
957    matching is used.
958    <pre>
959    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
960  </pre>  </pre>
961  Return a copy of the options with which the pattern was compiled. The fourth  Return a copy of the options with which the pattern was compiled. The fourth
# Line 859  a pcre_extra block. That is, it i Line 990  a pcre_extra block. That is, it i
990  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
991  <b>size_t</b> variable.  <b>size_t</b> variable.
992  </P>  </P>
993  <br><a name="SEC11" href="#TOC1">OBSOLETE INFO FUNCTION</a><br>  <br><a name="SEC12" href="#TOC1">OBSOLETE INFO FUNCTION</a><br>
994  <P>  <P>
995  <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>
996  <b>*<i>firstcharptr</i>);</b>  <b>*<i>firstcharptr</i>);</b>
# Line 883  If the pattern is not anchored and the < Line 1014  If the pattern is not anchored and the <
1014  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
1015  string (see PCRE_INFO_FIRSTBYTE above).  string (see PCRE_INFO_FIRSTBYTE above).
1016  </P>  </P>
1017  <br><a name="SEC12" href="#TOC1">REFERENCE COUNTS</a><br>  <br><a name="SEC13" href="#TOC1">REFERENCE COUNTS</a><br>
1018  <P>  <P>
1019  <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>
1020  </P>  </P>
# Line 907  Except when it is zero, the reference co Line 1038  Except when it is zero, the reference co
1038  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
1039  is different. (This seems a highly unlikely scenario.)  is different. (This seems a highly unlikely scenario.)
1040  </P>  </P>
1041  <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>
1042  <P>  <P>
1043  <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>
1044  <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 1045  Option bits for pcre_exec() Line 1176  Option bits for pcre_exec()
1176  </b><br>  </b><br>
1177  <P>  <P>
1178  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
1179  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>,
1180  PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.
1181  <pre>  <pre>
1182    PCRE_ANCHORED    PCRE_ANCHORED
1183  </pre>  </pre>
# Line 1055  matching position. If a pattern was comp Line 1186  matching position. If a pattern was comp
1186  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
1187  matching time.  matching time.
1188  <pre>  <pre>
1189      PCRE_NEWLINE_CR
1190      PCRE_NEWLINE_LF
1191      PCRE_NEWLINE_CRLF
1192      PCRE_NEWLINE_ANYCRLF
1193      PCRE_NEWLINE_ANY
1194    </pre>
1195    These options override the newline definition that was chosen or defaulted when
1196    the pattern was compiled. For details, see the description of
1197    <b>pcre_compile()</b> above. During matching, the newline choice affects the
1198    behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1199    the way the match position is advanced after a match failure for an unanchored
1200    pattern. When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is
1201    set, and a match attempt fails when the current position is at a CRLF sequence,
1202    the match position is advanced by two characters instead of one, in other
1203    words, to after the CRLF.
1204    <pre>
1205    PCRE_NOTBOL    PCRE_NOTBOL
1206  </pre>  </pre>
1207  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 1193  is set to the offset of the first charac Line 1340  is set to the offset of the first charac
1340  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
1341  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
1342  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>
1343  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
1344  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
1345  just the first pair of offsets has been set.  capturing subpatterns, the return value from a successful match is 1,
1346  </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.  
1347  </P>  </P>
1348  <P>  <P>
1349  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 1223  has to get additional memory for use dur Line 1360  has to get additional memory for use dur
1360  advisable to supply an <i>ovector</i>.  advisable to supply an <i>ovector</i>.
1361  </P>  </P>
1362  <P>  <P>
1363  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
1364  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1365  <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
1366  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.
1367    </P>
1368    <P>
1369    It is possible for capturing subpattern number <i>n+1</i> to match some part of
1370    the subject when subpattern <i>n</i> has not been used at all. For example, if
1371    the string "abc" is matched against the pattern (a|(z))(bc) the return from the
1372    function is 4, and subpatterns 1 and 3 are matched, but 2 is not. When this
1373    happens, both values in the offset pairs corresponding to unused subpatterns
1374    are set to -1.
1375    </P>
1376    <P>
1377    Offset values that correspond to unused subpatterns at the end of the
1378    expression are also set to -1. For example, if the string "abc" is matched
1379    against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
1380    return from the function is 2, because the highest used capturing subpattern
1381    number is 1. However, you can refer to the offsets for the second and third
1382    capturing subpatterns if you wish (assuming the vector is large enough, of
1383    course).
1384    </P>
1385    <P>
1386    Some convenience functions are provided for extracting the captured substrings
1387    as separate strings. These are described below.
1388  <a name="errorlist"></a></P>  <a name="errorlist"></a></P>
1389  <br><b>  <br><b>
1390  Return values from <b>pcre_exec()</b>  Error return values from <b>pcre_exec()</b>
1391  </b><br>  </b><br>
1392  <P>  <P>
1393  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 1256  compiled in an environment of one endian Line 1414  compiled in an environment of one endian
1414  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
1415  not present.  not present.
1416  <pre>  <pre>
1417    PCRE_ERROR_UNKNOWN_NODE   (-5)    PCRE_ERROR_UNKNOWN_OPCODE (-5)
1418  </pre>  </pre>
1419  While running the pattern match, an unknown item was encountered in the  While running the pattern match, an unknown item was encountered in the
1420  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 1282  The backtracking limit, as specified by Line 1440  The backtracking limit, as specified by
1440  <b>pcre_extra</b> structure (or defaulted) was reached. See the description  <b>pcre_extra</b> structure (or defaulted) was reached. See the description
1441  above.  above.
1442  <pre>  <pre>
   PCRE_ERROR_RECURSIONLIMIT (-21)  
 </pre>  
 The internal recursion limit, as specified by the <i>match_limit_recursion</i>  
 field in a <b>pcre_extra</b> structure (or defaulted) was reached. See the  
 description above.  
 <pre>  
1443    PCRE_ERROR_CALLOUT        (-9)    PCRE_ERROR_CALLOUT        (-9)
1444  </pre>  </pre>
1445  This error is never generated by <b>pcre_exec()</b> itself. It is provided for  This error is never generated by <b>pcre_exec()</b> itself. It is provided for
# Line 1325  in PCRE or by overwriting of the compile Line 1477  in PCRE or by overwriting of the compile
1477    PCRE_ERROR_BADCOUNT       (-15)    PCRE_ERROR_BADCOUNT       (-15)
1478  </pre>  </pre>
1479  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.
1480    <pre>
1481      PCRE_ERROR_RECURSIONLIMIT (-21)
1482    </pre>
1483    The internal recursion limit, as specified by the <i>match_limit_recursion</i>
1484    field in a <b>pcre_extra</b> structure (or defaulted) was reached. See the
1485    description above.
1486    <pre>
1487      PCRE_ERROR_NULLWSLIMIT    (-22)
1488    </pre>
1489    When a group that can match an empty substring is repeated with an unbounded
1490    upper limit, the subject position at the start of the group must be remembered,
1491    so that a test for an empty string can be made when the end of the group is
1492    reached. Some workspace is required for this; if it runs out, this error is
1493    given.
1494    <pre>
1495      PCRE_ERROR_BADNEWLINE     (-23)
1496    </pre>
1497    An invalid combination of PCRE_NEWLINE_<i>xxx</i> options was given.
1498    </P>
1499    <P>
1500    Error numbers -16 to -20 are not used by <b>pcre_exec()</b>.
1501  </P>  </P>
1502  <br><a name="SEC14" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>  <br><a name="SEC15" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>
1503  <P>  <P>
1504  <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>
1505  <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 1348  Captured substrings can be accessed dire Line 1521  Captured substrings can be accessed dire
1521  <b>pcre_get_substring_list()</b> are provided for extracting captured substrings  <b>pcre_get_substring_list()</b> are provided for extracting captured substrings
1522  as new, separate, zero-terminated strings. These functions identify substrings  as new, separate, zero-terminated strings. These functions identify substrings
1523  by number. The next section describes functions for extracting named  by number. The next section describes functions for extracting named
1524  substrings. A substring that contains a binary zero is correctly extracted and  substrings.
1525  has a further zero added on the end, but the result is not, of course,  </P>
1526  a C string.  <P>
1527    A substring that contains a binary zero is correctly extracted and has a
1528    further zero added on the end, but the result is not, of course, a C string.
1529    However, you can process such a string by referring to the length that is
1530    returned by <b>pcre_copy_substring()</b> and <b>pcre_get_substring()</b>.
1531    Unfortunately, the interface to <b>pcre_get_substring_list()</b> is not adequate
1532    for handling strings containing binary zeros, because the end of the final
1533    string is not independently indicated.
1534  </P>  </P>
1535  <P>  <P>
1536  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 1372  the string is placed in buffer, w Line 1552  the string is placed in buffer, w
1552  <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
1553  obtained via <b>pcre_malloc</b>, and its address is returned via  obtained via <b>pcre_malloc</b>, and its address is returned via
1554  <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
1555  including the terminating zero, or one of  including the terminating zero, or one of these error codes:
1556  <pre>  <pre>
1557    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1558  </pre>  </pre>
# Line 1389  and builds a list of pointers to them. A Line 1569  and builds a list of pointers to them. A
1569  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
1570  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
1571  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
1572  function is zero if all went well, or  function is zero if all went well, or the error code
1573  <pre>  <pre>
1574    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1575  </pre>  </pre>
# Line 1410  a previous call of pcre_get_substring Line 1590  a previous call of pcre_get_substring
1590  <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
1591  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
1592  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
1593  linked via a special interface to another programming language which cannot use  linked via a special interface to another programming language that cannot use
1594  <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
1595  provided.  provided.
1596  </P>  </P>
1597  <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>
1598  <P>  <P>
1599  <b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b>  <b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b>
1600  <b>const char *<i>name</i>);</b>  <b>const char *<i>name</i>);</b>
# Line 1435  provided. Line 1615  provided.
1615  To extract a substring by name, you first have to find associated number.  To extract a substring by name, you first have to find associated number.
1616  For example, for this pattern  For example, for this pattern
1617  <pre>  <pre>
1618    (a+)b(?P&#60;xxx&#62;\d+)...    (a+)b(?&#60;xxx&#62;\d+)...
1619  </pre>  </pre>
1620  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
1621  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
1622  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
1623    pattern, and the second is the name. The yield of the function is the
1624  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
1625  that name.  that name.
1626  </P>  </P>
# Line 1449  functions described in the previous sect Line 1630  functions described in the previous sect
1630  two functions that do the whole job.  two functions that do the whole job.
1631  </P>  </P>
1632  <P>  <P>
1633  Most of the arguments of <i>pcre_copy_named_substring()</i> and  Most of the arguments of <b>pcre_copy_named_substring()</b> and
1634  <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
1635  functions that extract by number. As these are described in the previous  functions that extract by number. As these are described in the previous
1636  section, they are not re-described here. There are just two differences:  section, they are not re-described here. There are just two differences:
1637  </P>  </P>
# Line 1462  translation table. Line 1643  translation table.
1643  </P>  </P>
1644  <P>  <P>
1645  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
1646  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
1647  appropriate.  appropriate. <b>NOTE:</b> If PCRE_DUPNAMES is set and there are duplicate names,
1648    the behaviour may not be what you want (see the next section).
1649    </P>
1650    <br><a name="SEC17" href="#TOC1">DUPLICATE SUBPATTERN NAMES</a><br>
1651    <P>
1652    <b>int pcre_get_stringtable_entries(const pcre *<i>code</i>,</b>
1653    <b>const char *<i>name</i>, char **<i>first</i>, char **<i>last</i>);</b>
1654    </P>
1655    <P>
1656    When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
1657    are not required to be unique. Normally, patterns with duplicate names are such
1658    that in any one match, only one of the named subpatterns participates. An
1659    example is shown in the
1660    <a href="pcrepattern.html"><b>pcrepattern</b></a>
1661    documentation. When duplicates are present, <b>pcre_copy_named_substring()</b>
1662    and <b>pcre_get_named_substring()</b> return the first substring corresponding
1663    to the given name that is set. If none are set, an empty string is returned.
1664    The <b>pcre_get_stringnumber()</b> function returns one of the numbers that are
1665    associated with the name, but it is not defined which it is.
1666    <br>
1667    <br>
1668    If you want to get full details of all captured substrings for a given name,
1669    you must use the <b>pcre_get_stringtable_entries()</b> function. The first
1670    argument is the compiled pattern, and the second is the name. The third and
1671    fourth are pointers to variables which are updated by the function. After it
1672    has run, they point to the first and last entries in the name-to-number table
1673    for the given name. The function itself returns the length of each entry, or
1674    PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
1675    described above in the section entitled <i>Information about a pattern</i>.
1676    Given all the relevant entries for the name, you can extract each of their
1677    numbers, and hence the captured data, if any.
1678  </P>  </P>
1679  <br><a name="SEC16" href="#TOC1">FINDING ALL POSSIBLE MATCHES</a><br>  <br><a name="SEC18" href="#TOC1">FINDING ALL POSSIBLE MATCHES</a><br>
1680  <P>  <P>
1681  The traditional matching function uses a similar algorithm to Perl, which stops  The traditional matching function uses a similar algorithm to Perl, which stops
1682  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 1484  substring. Then return 1, which forces < Line 1695  substring. Then return 1, which forces <
1695  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>
1696  will yield PCRE_ERROR_NOMATCH.  will yield PCRE_ERROR_NOMATCH.
1697  <a name="dfamatch"></a></P>  <a name="dfamatch"></a></P>
1698  <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>
1699  <P>  <P>
1700  <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>
1701  <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 1493  will yield PCRE_ERROR_NOMATCH. Line 1704  will yield PCRE_ERROR_NOMATCH.
1704  </P>  </P>
1705  <P>  <P>
1706  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
1707  a compiled pattern, using a "DFA" matching algorithm. This has different  a compiled pattern, using a matching algorithm that scans the subject string
1708  characteristics to the normal algorithm, and is not compatible with Perl. Some  just once, and does not backtrack. This has different characteristics to the
1709  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
1710  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
1711  matching algorithms, see the  matching can be useful. For a discussion of the two matching algorithms, see
1712    the
1713  <a href="pcrematching.html"><b>pcrematching</b></a>  <a href="pcrematching.html"><b>pcrematching</b></a>
1714  documentation.  documentation.
1715  </P>  </P>
# Line 1512  here. Line 1724  here.
1724  The two additional arguments provide workspace for the function. The workspace  The two additional arguments provide workspace for the function. The workspace
1725  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
1726  multiple paths through the pattern tree. More workspace will be needed for  multiple paths through the pattern tree. More workspace will be needed for
1727  patterns and subjects where there are a lot of possible matches.  patterns and subjects where there are a lot of potential matches.
1728  </P>  </P>
1729  <P>  <P>
1730  Here is an example of a simple call to <b>pcre_dfa_exec()</b>:  Here is an example of a simple call to <b>pcre_dfa_exec()</b>:
# Line 1538  Option bits for pcre_dfa_exec() Line 1750  Option bits for pcre_dfa_exec()
1750  </b><br>  </b><br>
1751  <P>  <P>
1752  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
1753  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>,
1754  PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,
1755  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
1756  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.
1757  <pre>  <pre>
# Line 1556  matching string. Line 1768  matching string.
1768    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
1769  </pre>  </pre>
1770  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
1771  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
1772  this is necessarily the shortest possible match at the first possible matching  works, this is necessarily the shortest possible match at the first possible
1773  point in the subject string.  matching point in the subject string.
1774  <pre>  <pre>
1775    PCRE_DFA_RESTART    PCRE_DFA_RESTART
1776  </pre>  </pre>
# Line 1596  the three matched strings are Line 1808  the three matched strings are
1808  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
1809  the number of matched substrings. The substrings themselves are returned in  the number of matched substrings. The substrings themselves are returned in
1810  <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
1811  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
1812  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,
1813  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>
1814  data, even though the meaning of the strings is different.)  returns data, even though the meaning of the strings is different.)
1815  </P>  </P>
1816  <P>  <P>
1817  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 1625  that it does not support, for instance, Line 1837  that it does not support, for instance,
1837  <pre>  <pre>
1838    PCRE_ERROR_DFA_UCOND      (-17)    PCRE_ERROR_DFA_UCOND      (-17)
1839  </pre>  </pre>
1840  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
1841  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
1842    group. These are not supported.
1843  <pre>  <pre>
1844    PCRE_ERROR_DFA_UMLIMIT    (-18)    PCRE_ERROR_DFA_UMLIMIT    (-18)
1845  </pre>  </pre>
# Line 1646  recursively, using private vectors for < Line 1859  recursively, using private vectors for <
1859  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
1860  extremely rare, as a vector of size 1000 is used.  extremely rare, as a vector of size 1000 is used.
1861  </P>  </P>
1862    <br><a name="SEC20" href="#TOC1">SEE ALSO</a><br>
1863    <P>
1864    <b>pcrebuild</b>(3), <b>pcrecallout</b>(3), <b>pcrecpp(3)</b>(3),
1865    <b>pcrematching</b>(3), <b>pcrepartial</b>(3), <b>pcreposix</b>(3),
1866    <b>pcreprecompile</b>(3), <b>pcresample</b>(3), <b>pcrestack</b>(3).
1867    </P>
1868    <br><a name="SEC21" href="#TOC1">AUTHOR</a><br>
1869  <P>  <P>
1870  Last updated: 18 January 2006  Philip Hazel
1871    <br>
1872    University Computing Service
1873    <br>
1874    Cambridge CB2 3QH, England.
1875    <br>
1876    </P>
1877    <br><a name="SEC22" href="#TOC1">REVISION</a><br>
1878    <P>
1879    Last updated: 13 June 2007
1880    <br>
1881    Copyright &copy; 1997-2007 University of Cambridge.
1882  <br>  <br>
 Copyright &copy; 1997-2006 University of Cambridge.  
1883  <p>  <p>
1884  Return to the <a href="index.html">PCRE index page</a>.  Return to the <a href="index.html">PCRE index page</a>.
1885  </p>  </p>

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