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revision 77 by nigel, Sat Feb 24 21:40:45 2007 UTC revision 227 by ph10, Tue Aug 21 15:00:15 2007 UTC
# Line 15  man page, in case the conversion went wr Line 15  man page, in case the conversion went wr
15  <ul>  <ul>
16  <li><a name="TOC1" href="#SEC1">PCRE NATIVE API</a>  <li><a name="TOC1" href="#SEC1">PCRE NATIVE API</a>
17  <li><a name="TOC2" href="#SEC2">PCRE API OVERVIEW</a>  <li><a name="TOC2" href="#SEC2">PCRE API OVERVIEW</a>
18  <li><a name="TOC3" href="#SEC3">MULTITHREADING</a>  <li><a name="TOC3" href="#SEC3">NEWLINES</a>
19  <li><a name="TOC4" href="#SEC4">SAVING PRECOMPILED PATTERNS FOR LATER USE</a>  <li><a name="TOC4" href="#SEC4">MULTITHREADING</a>
20  <li><a name="TOC5" href="#SEC5">CHECKING BUILD-TIME OPTIONS</a>  <li><a name="TOC5" href="#SEC5">SAVING PRECOMPILED PATTERNS FOR LATER USE</a>
21  <li><a name="TOC6" href="#SEC6">COMPILING A PATTERN</a>  <li><a name="TOC6" href="#SEC6">CHECKING BUILD-TIME OPTIONS</a>
22  <li><a name="TOC7" href="#SEC7">COMPILATION ERROR CODES</a>  <li><a name="TOC7" href="#SEC7">COMPILING A PATTERN</a>
23  <li><a name="TOC8" href="#SEC8">STUDYING A PATTERN</a>  <li><a name="TOC8" href="#SEC8">COMPILATION ERROR CODES</a>
24  <li><a name="TOC9" href="#SEC9">LOCALE SUPPORT</a>  <li><a name="TOC9" href="#SEC9">STUDYING A PATTERN</a>
25  <li><a name="TOC10" href="#SEC10">INFORMATION ABOUT A PATTERN</a>  <li><a name="TOC10" href="#SEC10">LOCALE SUPPORT</a>
26  <li><a name="TOC11" href="#SEC11">OBSOLETE INFO FUNCTION</a>  <li><a name="TOC11" href="#SEC11">INFORMATION ABOUT A PATTERN</a>
27  <li><a name="TOC12" href="#SEC12">REFERENCE COUNTS</a>  <li><a name="TOC12" href="#SEC12">OBSOLETE INFO FUNCTION</a>
28  <li><a name="TOC13" href="#SEC13">MATCHING A PATTERN: THE TRADITIONAL FUNCTION</a>  <li><a name="TOC13" href="#SEC13">REFERENCE COUNTS</a>
29  <li><a name="TOC14" href="#SEC14">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a>  <li><a name="TOC14" href="#SEC14">MATCHING A PATTERN: THE TRADITIONAL FUNCTION</a>
30  <li><a name="TOC15" href="#SEC15">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a>  <li><a name="TOC15" href="#SEC15">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a>
31  <li><a name="TOC16" href="#SEC16">FINDING ALL POSSIBLE MATCHES</a>  <li><a name="TOC16" href="#SEC16">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a>
32  <li><a name="TOC17" href="#SEC17">MATCHING A PATTERN: THE ALTERNATIVE FUNCTION</a>  <li><a name="TOC17" href="#SEC17">DUPLICATE SUBPATTERN NAMES</a>
33    <li><a name="TOC18" href="#SEC18">FINDING ALL POSSIBLE MATCHES</a>
34    <li><a name="TOC19" href="#SEC19">MATCHING A PATTERN: THE ALTERNATIVE FUNCTION</a>
35    <li><a name="TOC20" href="#SEC20">SEE ALSO</a>
36    <li><a name="TOC21" href="#SEC21">AUTHOR</a>
37    <li><a name="TOC22" href="#SEC22">REVISION</a>
38  </ul>  </ul>
39  <br><a name="SEC1" href="#TOC1">PCRE NATIVE API</a><br>  <br><a name="SEC1" href="#TOC1">PCRE NATIVE API</a><br>
40  <P>  <P>
# Line 83  man page, in case the conversion went wr Line 88  man page, in case the conversion went wr
88  <b>const char *<i>name</i>);</b>  <b>const char *<i>name</i>);</b>
89  </P>  </P>
90  <P>  <P>
91    <b>int pcre_get_stringtable_entries(const pcre *<i>code</i>,</b>
92    <b>const char *<i>name</i>, char **<i>first</i>, char **<i>last</i>);</b>
93    </P>
94    <P>
95  <b>int pcre_get_substring(const char *<i>subject</i>, int *<i>ovector</i>,</b>  <b>int pcre_get_substring(const char *<i>subject</i>, int *<i>ovector</i>,</b>
96  <b>int <i>stringcount</i>, int <i>stringnumber</i>,</b>  <b>int <i>stringcount</i>, int <i>stringnumber</i>,</b>
97  <b>const char **<i>stringptr</i>);</b>  <b>const char **<i>stringptr</i>);</b>
# Line 134  man page, in case the conversion went wr Line 143  man page, in case the conversion went wr
143  </P>  </P>
144  <br><a name="SEC2" href="#TOC1">PCRE API OVERVIEW</a><br>  <br><a name="SEC2" href="#TOC1">PCRE API OVERVIEW</a><br>
145  <P>  <P>
146  PCRE has its own native API, which is described in this document. There is  PCRE has its own native API, which is described in this document. There are
147  also a set of wrapper functions that correspond to the POSIX regular expression  also some wrapper functions that correspond to the POSIX regular expression
148  API. These are described in the  API. These are described in the
149  <a href="pcreposix.html"><b>pcreposix</b></a>  <a href="pcreposix.html"><b>pcreposix</b></a>
150  documentation. Both of these APIs define a set of C function calls. A C++  documentation. Both of these APIs define a set of C function calls. A C++
# Line 163  documentation describes how to run it. Line 172  documentation describes how to run it.
172  <P>  <P>
173  A second matching function, <b>pcre_dfa_exec()</b>, which is not  A second matching function, <b>pcre_dfa_exec()</b>, which is not
174  Perl-compatible, is also provided. This uses a different algorithm for the  Perl-compatible, is also provided. This uses a different algorithm for the
175  matching. This allows it to find all possible matches (at a given point in the  matching. The alternative algorithm finds all possible matches (at a given
176  subject), not just one. However, this algorithm does not return captured  point in the subject), and scans the subject just once. However, this algorithm
177  substrings. A description of the two matching algorithms and their advantages  does not return captured substrings. A description of the two matching
178  and disadvantages is given in the  algorithms and their advantages and disadvantages is given in the
179  <a href="pcrematching.html"><b>pcrematching</b></a>  <a href="pcrematching.html"><b>pcrematching</b></a>
180  documentation.  documentation.
181  </P>  </P>
# Line 181  matched by <b>pcre_exec()</b>. They are: Line 190  matched by <b>pcre_exec()</b>. They are:
190    <b>pcre_get_named_substring()</b>    <b>pcre_get_named_substring()</b>
191    <b>pcre_get_substring_list()</b>    <b>pcre_get_substring_list()</b>
192    <b>pcre_get_stringnumber()</b>    <b>pcre_get_stringnumber()</b>
193      <b>pcre_get_stringtable_entries()</b>
194  </pre>  </pre>
195  <b>pcre_free_substring()</b> and <b>pcre_free_substring_list()</b> are also  <b>pcre_free_substring()</b> and <b>pcre_free_substring_list()</b> are also
196  provided, to free the memory used for extracted strings.  provided, to free the memory used for extracted strings.
# Line 215  should be done before calling any PCRE f Line 225  should be done before calling any PCRE f
225  The global variables <b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> are also  The global variables <b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> are also
226  indirections to memory management functions. These special functions are used  indirections to memory management functions. These special functions are used
227  only when PCRE is compiled to use the heap for remembering data, instead of  only when PCRE is compiled to use the heap for remembering data, instead of
228  recursive function calls, when running the <b>pcre_exec()</b> function. This is  recursive function calls, when running the <b>pcre_exec()</b> function. See the
229  a non-standard way of building PCRE, for use in environments that have limited  <a href="pcrebuild.html"><b>pcrebuild</b></a>
230  stacks. Because of the greater use of memory management, it runs more slowly.  documentation for details of how to do this. It is a non-standard way of
231  Separate functions are provided so that special-purpose external code can be  building PCRE, for use in environments that have limited stacks. Because of the
232  used for this case. When used, these functions are always called in a  greater use of memory management, it runs more slowly. Separate functions are
233  stack-like manner (last obtained, first freed), and always for memory blocks of  provided so that special-purpose external code can be used for this case. When
234  the same size.  used, these functions are always called in a stack-like manner (last obtained,
235    first freed), and always for memory blocks of the same size. There is a
236    discussion about PCRE's stack usage in the
237    <a href="pcrestack.html"><b>pcrestack</b></a>
238    documentation.
239  </P>  </P>
240  <P>  <P>
241  The global variable <b>pcre_callout</b> initially contains NULL. It can be set  The global variable <b>pcre_callout</b> initially contains NULL. It can be set
# Line 229  by the caller to a "callout" function, w Line 243  by the caller to a "callout" function, w
243  points during a matching operation. Details are given in the  points during a matching operation. Details are given in the
244  <a href="pcrecallout.html"><b>pcrecallout</b></a>  <a href="pcrecallout.html"><b>pcrecallout</b></a>
245  documentation.  documentation.
246    <a name="newlines"></a></P>
247    <br><a name="SEC3" href="#TOC1">NEWLINES</a><br>
248    <P>
249    PCRE supports five different conventions for indicating line breaks in
250    strings: a single CR (carriage return) character, a single LF (linefeed)
251    character, the two-character sequence CRLF, any of the three preceding, or any
252    Unicode newline sequence. The Unicode newline sequences are the three just
253    mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed,
254    U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
255    (paragraph separator, U+2029).
256    </P>
257    <P>
258    Each of the first three conventions is used by at least one operating system as
259    its standard newline sequence. When PCRE is built, a default can be specified.
260    The default default is LF, which is the Unix standard. When PCRE is run, the
261    default can be overridden, either when a pattern is compiled, or when it is
262    matched.
263    </P>
264    <P>
265    At compile time, the newline convention can be specified by the <i>options</i>
266    argument of <b>pcre_compile()</b>, or it can be specified by special text at the
267    start of the pattern itself; this overrides any other settings. See the
268    <a href="pcrepattern.html"><b>pcrepattern</b></a>
269    page for details of the special character sequences.
270  </P>  </P>
271  <br><a name="SEC3" href="#TOC1">MULTITHREADING</a><br>  <P>
272    In the PCRE documentation the word "newline" is used to mean "the character or
273    pair of characters that indicate a line break". The choice of newline
274    convention affects the handling of the dot, circumflex, and dollar
275    metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
276    recognized line ending sequence, the match position advancement for a
277    non-anchored pattern. There is more detail about this in the
278    <a href="#execoptions">section on <b>pcre_exec()</b> options</a>
279    below. The choice of newline convention does not affect the interpretation of
280    the \n or \r escape sequences.
281    </P>
282    <br><a name="SEC4" href="#TOC1">MULTITHREADING</a><br>
283  <P>  <P>
284  The PCRE functions can be used in multi-threading applications, with the  The PCRE functions can be used in multi-threading applications, with the
285  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 290  callout function pointed to by <b>pcre_c
290  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
291  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.
292  </P>  </P>
293  <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>
294  <P>  <P>
295  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
296  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
297  which it was compiled. Details are given in the  which it was compiled. Details are given in the
298  <a href="pcreprecompile.html"><b>pcreprecompile</b></a>  <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
299  documentation.  documentation. However, compiling a regular expression with one version of PCRE
300    for use with a different version is not guaranteed to work and may cause
301    crashes.
302  </P>  </P>
303  <br><a name="SEC5" href="#TOC1">CHECKING BUILD-TIME OPTIONS</a><br>  <br><a name="SEC6" href="#TOC1">CHECKING BUILD-TIME OPTIONS</a><br>
304  <P>  <P>
305  <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>
306  </P>  </P>
# Line 276  properties is available; otherwise it is Line 327  properties is available; otherwise it is
327  <pre>  <pre>
328    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
329  </pre>  </pre>
330  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
331  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
332  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
333    default should normally be the standard sequence for your operating system.
334  <pre>  <pre>
335    PCRE_CONFIG_LINK_SIZE    PCRE_CONFIG_LINK_SIZE
336  </pre>  </pre>
# Line 302  The output is an integer that gives the Line 354  The output is an integer that gives the
354  internal matching function calls in a <b>pcre_exec()</b> execution. Further  internal matching function calls in a <b>pcre_exec()</b> execution. Further
355  details are given with <b>pcre_exec()</b> below.  details are given with <b>pcre_exec()</b> below.
356  <pre>  <pre>
357      PCRE_CONFIG_MATCH_LIMIT_RECURSION
358    </pre>
359    The output is an integer that gives the default limit for the depth of
360    recursion when calling the internal matching function in a <b>pcre_exec()</b>
361    execution. Further details are given with <b>pcre_exec()</b> below.
362    <pre>
363    PCRE_CONFIG_STACKRECURSE    PCRE_CONFIG_STACKRECURSE
364  </pre>  </pre>
365  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 370  of recursive function calls. In this cas
370  <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
371  avoiding the use of the stack.  avoiding the use of the stack.
372  </P>  </P>
373  <br><a name="SEC6" href="#TOC1">COMPILING A PATTERN</a><br>  <br><a name="SEC7" href="#TOC1">COMPILING A PATTERN</a><br>
374  <P>  <P>
375  <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>
376  <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 392  The pattern is a C string terminated by
392  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
393  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
394  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
395  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.
396  </P>  </P>
397  <P>  <P>
398  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 401  fully relocatable, because it may contai
401  argument, which is an address (see below).  argument, which is an address (see below).
402  </P>  </P>
403  <P>  <P>
404  The <i>options</i> argument contains independent bits that affect the  The <i>options</i> argument contains various bit settings that affect the
405  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
406  options are described below. Some of them, in particular, those that are  options are described below. Some of them, in particular, those that are
407  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 409  the detailed description in the
409  <a href="pcrepattern.html"><b>pcrepattern</b></a>  <a href="pcrepattern.html"><b>pcrepattern</b></a>
410  documentation). For these options, the contents of the <i>options</i> argument  documentation). For these options, the contents of the <i>options</i> argument
411  specifies their initial settings at the start of compilation and execution. The  specifies their initial settings at the start of compilation and execution. The
412  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
413  time.  matching as well as at compile time.
414  </P>  </P>
415  <P>  <P>
416  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.
417  Otherwise, if compilation of a pattern fails, <b>pcre_compile()</b> returns  Otherwise, if compilation of a pattern fails, <b>pcre_compile()</b> returns
418  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
419  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
420  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
421    where the error was discovered is placed in the variable pointed to by
422  <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.
423  </P>  </P>
424  <P>  <P>
# Line 424  with UTF-8 support. Line 483  with UTF-8 support.
483  </pre>  </pre>
484  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
485  end of the subject string. Without this option, a dollar also matches  end of the subject string. Without this option, a dollar also matches
486  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
487  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.
488  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
489  a pattern.  pattern.
490  <pre>  <pre>
491    PCRE_DOTALL    PCRE_DOTALL
492  </pre>  </pre>
493  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,
494  including newlines. Without it, newlines are excluded. This option is  including those that indicate newline. Without it, a dot does not match when
495  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
496  (?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
497  character, independent of the setting of this option.  negative class such as [^a] always matches newline characters, independent of
498    the setting of this option.
499    <pre>
500      PCRE_DUPNAMES
501    </pre>
502    If this bit is set, names used to identify capturing subpatterns need not be
503    unique. This can be helpful for certain types of pattern when it is known that
504    only one instance of the named subpattern can ever be matched. There are more
505    details of named subpatterns below; see also the
506    <a href="pcrepattern.html"><b>pcrepattern</b></a>
507    documentation.
508  <pre>  <pre>
509    PCRE_EXTENDED    PCRE_EXTENDED
510  </pre>  </pre>
511  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
512  ignored except when escaped or inside a character class. Whitespace does not  ignored except when escaped or inside a character class. Whitespace does not
513  include the VT character (code 11). In addition, characters between an  include the VT character (code 11). In addition, characters between an
514  unescaped # outside a character class and the next newline character,  unescaped # outside a character class and the next newline, inclusive, are also
515  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
516  be changed within a pattern by a (?x) option setting.  pattern by a (?x) option setting.
517  </P>  </P>
518  <P>  <P>
519  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 528  that is incompatible with Perl, but it i
528  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
529  special meaning causes an error, thus reserving these combinations for future  special meaning causes an error, thus reserving these combinations for future
530  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
531  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
532  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
533  pattern.  this option. It can also be set by a (?X) option setting within a pattern.
534  <pre>  <pre>
535    PCRE_FIRSTLINE    PCRE_FIRSTLINE
536  </pre>  </pre>
537  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
538  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
539  continue over the newline.  over the newline.
540  <pre>  <pre>
541    PCRE_MULTILINE    PCRE_MULTILINE
542  </pre>  </pre>
# Line 480  Perl. Line 549  Perl.
549  </P>  </P>
550  <P>  <P>
551  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
552  match immediately following or immediately before any newline in the subject  match immediately following or immediately before internal newlines in the
553  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
554  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
555  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
556  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.  occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.
557  <pre>  <pre>
558      PCRE_NEWLINE_CR
559      PCRE_NEWLINE_LF
560      PCRE_NEWLINE_CRLF
561      PCRE_NEWLINE_ANYCRLF
562      PCRE_NEWLINE_ANY
563    </pre>
564    These options override the default newline definition that was chosen when PCRE
565    was built. Setting the first or the second specifies that a newline is
566    indicated by a single character (CR or LF, respectively). Setting
567    PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
568    CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three
569    preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies
570    that any Unicode newline sequence should be recognized. The Unicode newline
571    sequences are the three just mentioned, plus the single characters VT (vertical
572    tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS (line
573    separator, U+2028), and PS (paragraph separator, U+2029). The last two are
574    recognized only in UTF-8 mode.
575    </P>
576    <P>
577    The newline setting in the options word uses three bits that are treated
578    as a number, giving eight possibilities. Currently only six are used (default
579    plus the five values above). This means that if you set more than one newline
580    option, the combination may or may not be sensible. For example,
581    PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
582    other combinations may yield unused numbers and cause an error.
583    </P>
584    <P>
585    The only time that a line break is specially recognized when compiling a
586    pattern is if PCRE_EXTENDED is set, and an unescaped # outside a character
587    class is encountered. This indicates a comment that lasts until after the next
588    line break sequence. In other circumstances, line break sequences are treated
589    as literal data, except that in PCRE_EXTENDED mode, both CR and LF are treated
590    as whitespace characters and are therefore ignored.
591    </P>
592    <P>
593    The newline option that is set at compile time becomes the default that is used
594    for <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>, but it can be overridden.
595    <pre>
596    PCRE_NO_AUTO_CAPTURE    PCRE_NO_AUTO_CAPTURE
597  </pre>  </pre>
598  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 515  page. Line 622  page.
622    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
623  </pre>  </pre>
624  When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is  When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
625  automatically checked. If an invalid UTF-8 sequence of bytes is found,  automatically checked. There is a discussion about the
626  <b>pcre_compile()</b> returns an error. If you already know that your pattern is  <a href="pcre.html#utf8strings">validity of UTF-8 strings</a>
627  valid, and you want to skip this check for performance reasons, you can set the  in the main
628  PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid  <a href="pcre.html"><b>pcre</b></a>
629  UTF-8 string as a pattern is undefined. It may cause your program to crash.  page. If an invalid UTF-8 sequence of bytes is found, <b>pcre_compile()</b>
630  Note that this option can also be passed to <b>pcre_exec()</b> and  returns an error. If you already know that your pattern is valid, and you want
631  <b>pcre_dfa_exec()</b>, to suppress the UTF-8 validity checking of subject  to skip this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK
632  strings.  option. When it is set, the effect of passing an invalid UTF-8 string as a
633    pattern is undefined. It may cause your program to crash. Note that this option
634    can also be passed to <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>, to suppress
635    the UTF-8 validity checking of subject strings.
636  </P>  </P>
637  <br><a name="SEC7" href="#TOC1">COMPILATION ERROR CODES</a><br>  <br><a name="SEC8" href="#TOC1">COMPILATION ERROR CODES</a><br>
638  <P>  <P>
639  The following table lists the error codes than may be returned by  The following table lists the error codes than may be returned by
640  <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
641  both compiling functions.  both compiling functions. As PCRE has developed, some error codes have fallen
642    out of use. To avoid confusion, they have not been re-used.
643  <pre>  <pre>
644     0  no error     0  no error
645     1  \ at end of pattern     1  \ at end of pattern
# Line 540  both compiling functions. Line 651  both compiling functions.
651     7  invalid escape sequence in character class     7  invalid escape sequence in character class
652     8  range out of order in character class     8  range out of order in character class
653     9  nothing to repeat     9  nothing to repeat
654    10  operand of unlimited repeat could match the empty string    10  [this code is not in use]
655    11  internal error: unexpected repeat    11  internal error: unexpected repeat
656    12  unrecognized character after (?    12  unrecognized character after (?
657    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 660  both compiling functions.
660    16  erroffset passed as NULL    16  erroffset passed as NULL
661    17  unknown option bit(s) set    17  unknown option bit(s) set
662    18  missing ) after comment    18  missing ) after comment
663    19  parentheses nested too deeply    19  [this code is not in use]
664    20  regular expression too large    20  regular expression too large
665    21  failed to get memory    21  failed to get memory
666    22  unmatched parentheses    22  unmatched parentheses
667    23  internal error: code overflow    23  internal error: code overflow
668    24  unrecognized character after (?&#60;    24  unrecognized character after (?&#60;
669    25  lookbehind assertion is not fixed length    25  lookbehind assertion is not fixed length
670    26  malformed number after (?(    26  malformed number or name after (?(
671    27  conditional group contains more than two branches    27  conditional group contains more than two branches
672    28  assertion expected after (?(    28  assertion expected after (?(
673    29  (?R or (?digits must be followed by )    29  (?R or (?[+-]digits must be followed by )
674    30  unknown POSIX class name    30  unknown POSIX class name
675    31  POSIX collating elements are not supported    31  POSIX collating elements are not supported
676    32  this version of PCRE is not compiled with PCRE_UTF8 support    32  this version of PCRE is not compiled with PCRE_UTF8 support
677    33  spare error    33  [this code is not in use]
678    34  character value in \x{...} sequence is too large    34  character value in \x{...} sequence is too large
679    35  invalid condition (?(0)    35  invalid condition (?(0)
680    36  \C not allowed in lookbehind assertion    36  \C not allowed in lookbehind assertion
# Line 572  both compiling functions. Line 683  both compiling functions.
683    39  closing ) for (?C expected    39  closing ) for (?C expected
684    40  recursive call could loop indefinitely    40  recursive call could loop indefinitely
685    41  unrecognized character after (?P    41  unrecognized character after (?P
686    42  syntax error after (?P    42  syntax error in subpattern name (missing terminator)
687    43  two named groups have the same name    43  two named subpatterns have the same name
688    44  invalid UTF-8 string    44  invalid UTF-8 string
689    45  support for \P, \p, and \X has not been compiled    45  support for \P, \p, and \X has not been compiled
690    46  malformed \P or \p sequence    46  malformed \P or \p sequence
691    47  unknown property name after \P or \p    47  unknown property name after \P or \p
692      48  subpattern name is too long (maximum 32 characters)
693      49  too many named subpatterns (maximum 10,000)
694      50  [this code is not in use]
695      51  octal value is greater than \377 (not in UTF-8 mode)
696      52  internal error: overran compiling workspace
697      53  internal error: previously-checked referenced subpattern not found
698      54  DEFINE group contains more than one branch
699      55  repeating a DEFINE group is not allowed
700      56  inconsistent NEWLINE options"
701      57  \g is not followed by a braced name or an optionally braced
702            non-zero number
703      58  (?+ or (?- or (?(+ or (?(- must be followed by a non-zero number
704  </PRE>  </PRE>
705  </P>  </P>
706  <br><a name="SEC8" href="#TOC1">STUDYING A PATTERN</a><br>  <br><a name="SEC9" href="#TOC1">STUDYING A PATTERN</a><br>
707  <P>  <P>
708  <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>
709  <b>const char **<i>errptr</i>);</b>  <b>const char **<i>errptr</i>);</b>
# Line 615  options are defined, and this argument s Line 738  options are defined, and this argument s
738  <P>  <P>
739  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
740  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
741  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
742  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
743  be sure that it has run successfully.  should test the error pointer for NULL after calling <b>pcre_study()</b>, to be
744    sure that it has run successfully.
745  </P>  </P>
746  <P>  <P>
747  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 756  At present, studying a pattern is useful
756  not have a single fixed starting character. A bitmap of possible starting  not have a single fixed starting character. A bitmap of possible starting
757  bytes is created.  bytes is created.
758  <a name="localesupport"></a></P>  <a name="localesupport"></a></P>
759  <br><a name="SEC9" href="#TOC1">LOCALE SUPPORT</a><br>  <br><a name="SEC10" href="#TOC1">LOCALE SUPPORT</a><br>
760  <P>  <P>
761  PCRE handles caseless matching, and determines whether characters are letters  PCRE handles caseless matching, and determines whether characters are letters,
762  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
763  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
764  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
765  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
766  support.  support. The use of locales with Unicode is discouraged. If you are handling
767  </P>  characters with codes greater than 128, you should either use UTF-8 and
768  <P>  Unicode, or use locales, but not try to mix the two.
769  An internal set of tables is created in the default C locale when PCRE is  </P>
770  built. This is used when the final argument of <b>pcre_compile()</b> is NULL,  <P>
771  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
772  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.
773  default. As more and more applications change to using Unicode, the need for  Normally, the internal tables recognize only ASCII characters. However, when
774  this locale support is expected to die away.  PCRE is built, it is possible to cause the internal tables to be rebuilt in the
775    default "C" locale of the local system, which may cause them to be different.
776    </P>
777    <P>
778    The internal tables can always be overridden by tables supplied by the
779    application that calls PCRE. These may be created in a different locale from
780    the default. As more and more applications change to using Unicode, the need
781    for this locale support is expected to die away.
782  </P>  </P>
783  <P>  <P>
784  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 661  the following code could be used: Line 792  the following code could be used:
792    tables = pcre_maketables();    tables = pcre_maketables();
793    re = pcre_compile(..., tables);    re = pcre_compile(..., tables);
794  </pre>  </pre>
795    The locale name "fr_FR" is used on Linux and other Unix-like systems; if you
796    are using Windows, the name for the French locale is "french".
797    </P>
798    <P>
799  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
800  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
801  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 680  this facility could be used to match a p Line 815  this facility could be used to match a p
815  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
816  below in the section on matching a pattern.  below in the section on matching a pattern.
817  </P>  </P>
818  <br><a name="SEC10" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br>  <br><a name="SEC11" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br>
819  <P>  <P>
820  <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>
821  <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 843  check against passing an arbitrary memor
843  <b>pcre_fullinfo()</b>, to obtain the length of the compiled pattern:  <b>pcre_fullinfo()</b>, to obtain the length of the compiled pattern:
844  <pre>  <pre>
845    int rc;    int rc;
846    unsigned long int length;    size_t length;
847    rc = pcre_fullinfo(    rc = pcre_fullinfo(
848      re,               /* result of pcre_compile() */      re,               /* result of pcre_compile() */
849      pe,               /* result of pcre_study(), or NULL */      pe,               /* result of pcre_study(), or NULL */
# Line 740  a NULL table pointer. Line 875  a NULL table pointer.
875    PCRE_INFO_FIRSTBYTE    PCRE_INFO_FIRSTBYTE
876  </pre>  </pre>
877  Return information about the first byte of any matched string, for a  Return information about the first byte of any matched string, for a
878  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>
879  old name is still recognized for backwards compatibility.)  variable. (This option used to be called PCRE_INFO_FIRSTCHAR; the old name is
880    still recognized for backwards compatibility.)
881  </P>  </P>
882  <P>  <P>
883  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
884  (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  
885  <br>  <br>
886  <br>  <br>
887  (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 768  table indicating a fixed set of bytes fo Line 903  table indicating a fixed set of bytes fo
903  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
904  fourth argument should point to an <b>unsigned char *</b> variable.  fourth argument should point to an <b>unsigned char *</b> variable.
905  <pre>  <pre>
906      PCRE_INFO_HASCRORLF
907    </pre>
908    Return 1 if the pattern contains any explicit matches for CR or LF characters,
909    otherwise 0. The fourth argument should point to an <b>int</b> variable.
910    <pre>
911      PCRE_INFO_JCHANGED
912    </pre>
913    Return 1 if the (?J) option setting is used in the pattern, otherwise 0. The
914    fourth argument should point to an <b>int</b> variable. The (?J) internal option
915    setting changes the local PCRE_DUPNAMES option.
916    <pre>
917    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
918  </pre>  </pre>
919  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 784  is -1. Line 930  is -1.
930  </pre>  </pre>
931  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
932  names are just an additional way of identifying the parentheses, which still  names are just an additional way of identifying the parentheses, which still
933  acquire numbers. A convenience function called <b>pcre_get_named_substring()</b>  acquire numbers. Several convenience functions such as
934  is provided for extracting an individual captured substring by name. It is also  <b>pcre_get_named_substring()</b> are provided for extracting captured
935  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
936  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
937  <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,
938  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
939    values.
940  </P>  </P>
941  <P>  <P>
942  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 946  length of the longest name. PCRE_INFO_NA
946  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
947  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
948  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
949  alphabetical order. For example, consider the following pattern (assume  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of
950    their parentheses numbers. For example, consider the following pattern (assume
951  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  PCRE_EXTENDED is set, so white space - including newlines - is ignored):
952  <pre>  <pre>
953    (?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) )
954  </pre>  </pre>
955  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
956  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 962  bytes shows in hexadecimal, and undefine
962    00 02 y  e  a  r  00 ??    00 02 y  e  a  r  00 ??
963  </pre>  </pre>
964  When writing code to extract data from named subpatterns using the  When writing code to extract data from named subpatterns using the
965  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
966  different for each compiled pattern.  different for each compiled pattern.
967  <pre>  <pre>
968      PCRE_INFO_OKPARTIAL
969    </pre>
970    Return 1 if the pattern can be used for partial matching, otherwise 0. The
971    fourth argument should point to an <b>int</b> variable. The
972    <a href="pcrepartial.html"><b>pcrepartial</b></a>
973    documentation lists the restrictions that apply to patterns when partial
974    matching is used.
975    <pre>
976    PCRE_INFO_OPTIONS    PCRE_INFO_OPTIONS
977  </pre>  </pre>
978  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
979  argument should point to an <b>unsigned long int</b> variable. These option bits  argument should point to an <b>unsigned long int</b> variable. These option bits
980  are those specified in the call to <b>pcre_compile()</b>, modified by any  are those specified in the call to <b>pcre_compile()</b>, modified by any
981  top-level option settings within the pattern itself.  top-level option settings at the start of the pattern itself. In other words,
982    they are the options that will be in force when matching starts. For example,
983    if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED option, the
984    result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED.
985  </P>  </P>
986  <P>  <P>
987  A pattern is automatically anchored by PCRE if all of its top-level  A pattern is automatically anchored by PCRE if all of its top-level
# Line 851  a <b>pcre_extra</b> block. That is, it i Line 1010  a <b>pcre_extra</b> block. That is, it i
1010  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
1011  <b>size_t</b> variable.  <b>size_t</b> variable.
1012  </P>  </P>
1013  <br><a name="SEC11" href="#TOC1">OBSOLETE INFO FUNCTION</a><br>  <br><a name="SEC12" href="#TOC1">OBSOLETE INFO FUNCTION</a><br>
1014  <P>  <P>
1015  <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>
1016  <b>*<i>firstcharptr</i>);</b>  <b>*<i>firstcharptr</i>);</b>
# Line 875  If the pattern is not anchored and the < Line 1034  If the pattern is not anchored and the <
1034  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
1035  string (see PCRE_INFO_FIRSTBYTE above).  string (see PCRE_INFO_FIRSTBYTE above).
1036  </P>  </P>
1037  <br><a name="SEC12" href="#TOC1">REFERENCE COUNTS</a><br>  <br><a name="SEC13" href="#TOC1">REFERENCE COUNTS</a><br>
1038  <P>  <P>
1039  <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>
1040  </P>  </P>
# Line 899  Except when it is zero, the reference co Line 1058  Except when it is zero, the reference co
1058  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
1059  is different. (This seems a highly unlikely scenario.)  is different. (This seems a highly unlikely scenario.)
1060  </P>  </P>
1061  <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>
1062  <P>  <P>
1063  <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>
1064  <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 1106  Extra data for <b>pcre_exec()</b>
1106  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>
1107  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
1108  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
1109  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
1110  follows:  fields (not necessarily in this order):
1111  <pre>  <pre>
1112    unsigned long int <i>flags</i>;    unsigned long int <i>flags</i>;
1113    void *<i>study_data</i>;    void *<i>study_data</i>;
1114    unsigned long int <i>match_limit</i>;    unsigned long int <i>match_limit</i>;
1115      unsigned long int <i>match_limit_recursion</i>;
1116    void *<i>callout_data</i>;    void *<i>callout_data</i>;
1117    const unsigned char *<i>tables</i>;    const unsigned char *<i>tables</i>;
1118  </pre>  </pre>
# Line 961  are set. The flag bits are: Line 1121  are set. The flag bits are:
1121  <pre>  <pre>
1122    PCRE_EXTRA_STUDY_DATA    PCRE_EXTRA_STUDY_DATA
1123    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1124      PCRE_EXTRA_MATCH_LIMIT_RECURSION
1125    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1126    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1127  </pre>  </pre>
# Line 977  classic example is the use of nested unl Line 1138  classic example is the use of nested unl
1138  </P>  </P>
1139  <P>  <P>
1140  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
1141  (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
1142  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
1143  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
1144  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
1145    string.
1146  </P>  </P>
1147  <P>  <P>
1148  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
1149  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
1150  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>
1151  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
1152  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
1153  exceeded, <b>pcre_exec()</b> returns PCRE_ERROR_MATCHLIMIT.  PCRE_ERROR_MATCHLIMIT.
1154    </P>
1155    <P>
1156    The <i>match_limit_recursion</i> field is similar to <i>match_limit</i>, but
1157    instead of limiting the total number of times that <b>match()</b> is called, it
1158    limits the depth of recursion. The recursion depth is a smaller number than the
1159    total number of calls, because not all calls to <b>match()</b> are recursive.
1160    This limit is of use only if it is set smaller than <i>match_limit</i>.
1161    </P>
1162    <P>
1163    Limiting the recursion depth limits the amount of stack that can be used, or,
1164    when PCRE has been compiled to use memory on the heap instead of the stack, the
1165    amount of heap memory that can be used.
1166    </P>
1167    <P>
1168    The default value for <i>match_limit_recursion</i> can be set when PCRE is
1169    built; the default default is the same value as the default for
1170    <i>match_limit</i>. You can override the default by suppling <b>pcre_exec()</b>
1171    with a <b>pcre_extra</b> block in which <i>match_limit_recursion</i> is set, and
1172    PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the <i>flags</i> field. If the limit
1173    is exceeded, <b>pcre_exec()</b> returns PCRE_ERROR_RECURSIONLIMIT.
1174  </P>  </P>
1175  <P>  <P>
1176  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 1008  the external tables might be at a differ Line 1190  the external tables might be at a differ
1190  called. See the  called. See the
1191  <a href="pcreprecompile.html"><b>pcreprecompile</b></a>  <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
1192  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1193  </P>  <a name="execoptions"></a></P>
1194  <br><b>  <br><b>
1195  Option bits for <b>pcre_exec()</b>  Option bits for <b>pcre_exec()</b>
1196  </b><br>  </b><br>
1197  <P>  <P>
1198  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
1199  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>,
1200  PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.
1201  <pre>  <pre>
1202    PCRE_ANCHORED    PCRE_ANCHORED
1203  </pre>  </pre>
# Line 1024  matching position. If a pattern was comp Line 1206  matching position. If a pattern was comp
1206  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
1207  matching time.  matching time.
1208  <pre>  <pre>
1209      PCRE_NEWLINE_CR
1210      PCRE_NEWLINE_LF
1211      PCRE_NEWLINE_CRLF
1212      PCRE_NEWLINE_ANYCRLF
1213      PCRE_NEWLINE_ANY
1214    </pre>
1215    These options override the newline definition that was chosen or defaulted when
1216    the pattern was compiled. For details, see the description of
1217    <b>pcre_compile()</b> above. During matching, the newline choice affects the
1218    behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1219    the way the match position is advanced after a match failure for an unanchored
1220    pattern.
1221    </P>
1222    <P>
1223    When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a
1224    match attempt for an unanchored pattern fails when the current position is at a
1225    CRLF sequence, and the pattern contains no explicit matches for CR or NL
1226    characters, the match position is advanced by two characters instead of one, in
1227    other words, to after the CRLF.
1228    </P>
1229    <P>
1230    The above rule is a compromise that makes the most common cases work as
1231    expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
1232    set), it does not match the string "\r\nA" because, after failing at the
1233    start, it skips both the CR and the LF before retrying. However, the pattern
1234    [\r\n]A does match that string, because it contains an explicit CR or LF
1235    reference, and so advances only by one character after the first failure.
1236    Note than an explicit CR or LF reference occurs for negated character classes
1237    such as [^X] because they can match CR or LF characters.
1238    </P>
1239    <P>
1240    Notwithstanding the above, anomalous effects may still occur when CRLF is a
1241    valid newline sequence and explicit \r or \n escapes appear in the pattern.
1242    <pre>
1243    PCRE_NOTBOL    PCRE_NOTBOL
1244  </pre>  </pre>
1245  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 1066  code that demonstrates how to do this in Line 1282  code that demonstrates how to do this in
1282  When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8  When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8
1283  string is automatically checked when <b>pcre_exec()</b> is subsequently called.  string is automatically checked when <b>pcre_exec()</b> is subsequently called.
1284  The value of <i>startoffset</i> is also checked to ensure that it points to the  The value of <i>startoffset</i> is also checked to ensure that it points to the
1285  start of a UTF-8 character. If an invalid UTF-8 sequence of bytes is found,  start of a UTF-8 character. There is a discussion about the validity of UTF-8
1286  <b>pcre_exec()</b> returns the error PCRE_ERROR_BADUTF8. If <i>startoffset</i>  strings in the
1287  contains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.  <a href="pcre.html#utf8strings">section on UTF-8 support</a>
1288    in the main
1289    <a href="pcre.html"><b>pcre</b></a>
1290    page. If an invalid UTF-8 sequence of bytes is found, <b>pcre_exec()</b> returns
1291    the error PCRE_ERROR_BADUTF8. If <i>startoffset</i> contains an invalid value,
1292    PCRE_ERROR_BADUTF8_OFFSET is returned.
1293  </P>  </P>
1294  <P>  <P>
1295  If you already know that your subject is valid, and you want to skip these  If you already know that your subject is valid, and you want to skip these
# Line 1162  is set to the offset of the first charac Line 1383  is set to the offset of the first charac
1383  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
1384  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
1385  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>
1386  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
1387  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
1388  just the first pair of offsets has been set.  capturing subpatterns, the return value from a successful match is 1,
1389  </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.  
1390  </P>  </P>
1391  <P>  <P>
1392  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 1403  has to get additional memory for use dur
1403  advisable to supply an <i>ovector</i>.  advisable to supply an <i>ovector</i>.
1404  </P>  </P>
1405  <P>  <P>
1406  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
1407  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1408  <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
1409  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.
1410    </P>
1411    <P>
1412    It is possible for capturing subpattern number <i>n+1</i> to match some part of
1413    the subject when subpattern <i>n</i> has not been used at all. For example, if
1414    the string "abc" is matched against the pattern (a|(z))(bc) the return from the
1415    function is 4, and subpatterns 1 and 3 are matched, but 2 is not. When this
1416    happens, both values in the offset pairs corresponding to unused subpatterns
1417    are set to -1.
1418    </P>
1419    <P>
1420    Offset values that correspond to unused subpatterns at the end of the
1421    expression are also set to -1. For example, if the string "abc" is matched
1422    against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
1423    return from the function is 2, because the highest used capturing subpattern
1424    number is 1. However, you can refer to the offsets for the second and third
1425    capturing subpatterns if you wish (assuming the vector is large enough, of
1426    course).
1427    </P>
1428    <P>
1429    Some convenience functions are provided for extracting the captured substrings
1430    as separate strings. These are described below.
1431  <a name="errorlist"></a></P>  <a name="errorlist"></a></P>
1432  <br><b>  <br><b>
1433  Return values from <b>pcre_exec()</b>  Error return values from <b>pcre_exec()</b>
1434  </b><br>  </b><br>
1435  <P>  <P>
1436  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 1457  compiled in an environment of one endian
1457  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
1458  not present.  not present.
1459  <pre>  <pre>
1460    PCRE_ERROR_UNKNOWN_NODE   (-5)    PCRE_ERROR_UNKNOWN_OPCODE (-5)
1461  </pre>  </pre>
1462  While running the pattern match, an unknown item was encountered in the  While running the pattern match, an unknown item was encountered in the
1463  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 1479  below). It is never returned by <b>pcre_
1479  <pre>  <pre>
1480    PCRE_ERROR_MATCHLIMIT     (-8)    PCRE_ERROR_MATCHLIMIT     (-8)
1481  </pre>  </pre>
1482  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
1483  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
1484  description above.  above.
1485  <pre>  <pre>
1486    PCRE_ERROR_CALLOUT        (-9)    PCRE_ERROR_CALLOUT        (-9)
1487  </pre>  </pre>
# Line 1288  in PCRE or by overwriting of the compile Line 1520  in PCRE or by overwriting of the compile
1520    PCRE_ERROR_BADCOUNT       (-15)    PCRE_ERROR_BADCOUNT       (-15)
1521  </pre>  </pre>
1522  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.
1523    <pre>
1524      PCRE_ERROR_RECURSIONLIMIT (-21)
1525    </pre>
1526    The internal recursion limit, as specified by the <i>match_limit_recursion</i>
1527    field in a <b>pcre_extra</b> structure (or defaulted) was reached. See the
1528    description above.
1529    <pre>
1530      PCRE_ERROR_BADNEWLINE     (-23)
1531    </pre>
1532    An invalid combination of PCRE_NEWLINE_<i>xxx</i> options was given.
1533  </P>  </P>
1534  <br><a name="SEC14" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>  <P>
1535    Error numbers -16 to -20 and -22 are not used by <b>pcre_exec()</b>.
1536    </P>
1537    <br><a name="SEC15" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>
1538  <P>  <P>
1539  <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>
1540  <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 1556  Captured substrings can be accessed dire
1556  <b>pcre_get_substring_list()</b> are provided for extracting captured substrings  <b>pcre_get_substring_list()</b> are provided for extracting captured substrings
1557  as new, separate, zero-terminated strings. These functions identify substrings  as new, separate, zero-terminated strings. These functions identify substrings
1558  by number. The next section describes functions for extracting named  by number. The next section describes functions for extracting named
1559  substrings. A substring that contains a binary zero is correctly extracted and  substrings.
1560  has a further zero added on the end, but the result is not, of course,  </P>
1561  a C string.  <P>
1562    A substring that contains a binary zero is correctly extracted and has a
1563    further zero added on the end, but the result is not, of course, a C string.
1564    However, you can process such a string by referring to the length that is
1565    returned by <b>pcre_copy_substring()</b> and <b>pcre_get_substring()</b>.
1566    Unfortunately, the interface to <b>pcre_get_substring_list()</b> is not adequate
1567    for handling strings containing binary zeros, because the end of the final
1568    string is not independently indicated.
1569  </P>  </P>
1570  <P>  <P>
1571  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 1587  the string is placed in <i>buffer</i>, w
1587  <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
1588  obtained via <b>pcre_malloc</b>, and its address is returned via  obtained via <b>pcre_malloc</b>, and its address is returned via
1589  <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
1590  including the terminating zero, or one of  including the terminating zero, or one of these error codes:
1591  <pre>  <pre>
1592    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1593  </pre>  </pre>
# Line 1352  and builds a list of pointers to them. A Line 1604  and builds a list of pointers to them. A
1604  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
1605  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
1606  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
1607  function is zero if all went well, or  function is zero if all went well, or the error code
1608  <pre>  <pre>
1609    PCRE_ERROR_NOMEMORY       (-6)    PCRE_ERROR_NOMEMORY       (-6)
1610  </pre>  </pre>
# Line 1373  a previous call of <b>pcre_get_substring Line 1625  a previous call of <b>pcre_get_substring
1625  <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
1626  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
1627  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
1628  linked via a special interface to another programming language which cannot use  linked via a special interface to another programming language that cannot use
1629  <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
1630  provided.  provided.
1631  </P>  </P>
1632  <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>
1633  <P>  <P>
1634  <b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b>  <b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b>
1635  <b>const char *<i>name</i>);</b>  <b>const char *<i>name</i>);</b>
# Line 1400  For example, for this pattern Line 1652  For example, for this pattern
1652  <pre>  <pre>
1653    (a+)b(?&#60;xxx&#62;\d+)...    (a+)b(?&#60;xxx&#62;\d+)...
1654  </pre>  </pre>
1655  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
1656  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
1657  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
1658    pattern, and the second is the name. The yield of the function is the
1659  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
1660  that name.  that name.
1661  </P>  </P>
# Line 1412  functions described in the previous sect Line 1665  functions described in the previous sect
1665  two functions that do the whole job.  two functions that do the whole job.
1666  </P>  </P>
1667  <P>  <P>
1668  Most of the arguments of <i>pcre_copy_named_substring()</i> and  Most of the arguments of <b>pcre_copy_named_substring()</b> and
1669  <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
1670  functions that extract by number. As these are described in the previous  functions that extract by number. As these are described in the previous
1671  section, they are not re-described here. There are just two differences:  section, they are not re-described here. There are just two differences:
1672  </P>  </P>
# Line 1425  translation table. Line 1678  translation table.
1678  </P>  </P>
1679  <P>  <P>
1680  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
1681  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
1682  appropriate.  appropriate. <b>NOTE:</b> If PCRE_DUPNAMES is set and there are duplicate names,
1683    the behaviour may not be what you want (see the next section).
1684    </P>
1685    <br><a name="SEC17" href="#TOC1">DUPLICATE SUBPATTERN NAMES</a><br>
1686    <P>
1687    <b>int pcre_get_stringtable_entries(const pcre *<i>code</i>,</b>
1688    <b>const char *<i>name</i>, char **<i>first</i>, char **<i>last</i>);</b>
1689  </P>  </P>
1690  <br><a name="SEC16" href="#TOC1">FINDING ALL POSSIBLE MATCHES</a><br>  <P>
1691    When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
1692    are not required to be unique. Normally, patterns with duplicate names are such
1693    that in any one match, only one of the named subpatterns participates. An
1694    example is shown in the
1695    <a href="pcrepattern.html"><b>pcrepattern</b></a>
1696    documentation.
1697    </P>
1698    <P>
1699    When duplicates are present, <b>pcre_copy_named_substring()</b> and
1700    <b>pcre_get_named_substring()</b> return the first substring corresponding to
1701    the given name that is set. If none are set, PCRE_ERROR_NOSUBSTRING (-7) is
1702    returned; no data is returned. The <b>pcre_get_stringnumber()</b> function
1703    returns one of the numbers that are associated with the name, but it is not
1704    defined which it is.
1705    </P>
1706    <P>
1707    If you want to get full details of all captured substrings for a given name,
1708    you must use the <b>pcre_get_stringtable_entries()</b> function. The first
1709    argument is the compiled pattern, and the second is the name. The third and
1710    fourth are pointers to variables which are updated by the function. After it
1711    has run, they point to the first and last entries in the name-to-number table
1712    for the given name. The function itself returns the length of each entry, or
1713    PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
1714    described above in the section entitled <i>Information about a pattern</i>.
1715    Given all the relevant entries for the name, you can extract each of their
1716    numbers, and hence the captured data, if any.
1717    </P>
1718    <br><a name="SEC18" href="#TOC1">FINDING ALL POSSIBLE MATCHES</a><br>
1719  <P>  <P>
1720  The traditional matching function uses a similar algorithm to Perl, which stops  The traditional matching function uses a similar algorithm to Perl, which stops
1721  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 1734  substring. Then return 1, which forces <
1734  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>
1735  will yield PCRE_ERROR_NOMATCH.  will yield PCRE_ERROR_NOMATCH.
1736  <a name="dfamatch"></a></P>  <a name="dfamatch"></a></P>
1737  <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>
1738  <P>  <P>
1739  <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>
1740  <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 1743  will yield PCRE_ERROR_NOMATCH.
1743  </P>  </P>
1744  <P>  <P>
1745  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
1746  a compiled pattern, using a "DFA" matching algorithm. This has different  a compiled pattern, using a matching algorithm that scans the subject string
1747  characteristics to the normal algorithm, and is not compatible with Perl. Some  just once, and does not backtrack. This has different characteristics to the
1748  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
1749  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
1750  matching algorithms, see the  matching can be useful. For a discussion of the two matching algorithms, see
1751    the
1752  <a href="pcrematching.html"><b>pcrematching</b></a>  <a href="pcrematching.html"><b>pcrematching</b></a>
1753  documentation.  documentation.
1754  </P>  </P>
# Line 1475  here. Line 1763  here.
1763  The two additional arguments provide workspace for the function. The workspace  The two additional arguments provide workspace for the function. The workspace
1764  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
1765  multiple paths through the pattern tree. More workspace will be needed for  multiple paths through the pattern tree. More workspace will be needed for
1766  patterns and subjects where there are a lot of possible matches.  patterns and subjects where there are a lot of potential matches.
1767  </P>  </P>
1768  <P>  <P>
1769  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>:
1770  <pre>  <pre>
1771    int rc;    int rc;
1772    int ovector[10];    int ovector[10];
1773    int wspace[20];    int wspace[20];
1774    rc = pcre_exec(    rc = pcre_dfa_exec(
1775      re,             /* result of pcre_compile() */      re,             /* result of pcre_compile() */
1776      NULL,           /* we didn't study the pattern */      NULL,           /* we didn't study the pattern */
1777      "some string",  /* the subject string */      "some string",  /* the subject string */
# Line 1501  Option bits for <b>pcre_dfa_exec()</b> Line 1789  Option bits for <b>pcre_dfa_exec()</b>
1789  </b><br>  </b><br>
1790  <P>  <P>
1791  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
1792  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>,
1793  PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL,
1794  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
1795  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.
1796  <pre>  <pre>
# Line 1519  matching string. Line 1807  matching string.
1807    PCRE_DFA_SHORTEST    PCRE_DFA_SHORTEST
1808  </pre>  </pre>
1809  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
1810  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
1811  this is necessarily the shortest possible match at the first possible matching  works, this is necessarily the shortest possible match at the first possible
1812  point in the subject string.  matching point in the subject string.
1813  <pre>  <pre>
1814    PCRE_DFA_RESTART    PCRE_DFA_RESTART
1815  </pre>  </pre>
# Line 1559  the three matched strings are Line 1847  the three matched strings are
1847  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
1848  the number of matched substrings. The substrings themselves are returned in  the number of matched substrings. The substrings themselves are returned in
1849  <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
1850  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
1851  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,
1852  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>
1853  data, even though the meaning of the strings is different.)  returns data, even though the meaning of the strings is different.)
1854  </P>  </P>
1855  <P>  <P>
1856  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 1876  that it does not support, for instance,
1876  <pre>  <pre>
1877    PCRE_ERROR_DFA_UCOND      (-17)    PCRE_ERROR_DFA_UCOND      (-17)
1878  </pre>  </pre>
1879  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
1880  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
1881    group. These are not supported.
1882  <pre>  <pre>
1883    PCRE_ERROR_DFA_UMLIMIT    (-18)    PCRE_ERROR_DFA_UMLIMIT    (-18)
1884  </pre>  </pre>
# Line 1609  recursively, using private vectors for < Line 1898  recursively, using private vectors for <
1898  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
1899  extremely rare, as a vector of size 1000 is used.  extremely rare, as a vector of size 1000 is used.
1900  </P>  </P>
1901    <br><a name="SEC20" href="#TOC1">SEE ALSO</a><br>
1902    <P>
1903    <b>pcrebuild</b>(3), <b>pcrecallout</b>(3), <b>pcrecpp(3)</b>(3),
1904    <b>pcrematching</b>(3), <b>pcrepartial</b>(3), <b>pcreposix</b>(3),
1905    <b>pcreprecompile</b>(3), <b>pcresample</b>(3), <b>pcrestack</b>(3).
1906    </P>
1907    <br><a name="SEC21" href="#TOC1">AUTHOR</a><br>
1908    <P>
1909    Philip Hazel
1910    <br>
1911    University Computing Service
1912    <br>
1913    Cambridge CB2 3QH, England.
1914    <br>
1915    </P>
1916    <br><a name="SEC22" href="#TOC1">REVISION</a><br>
1917  <P>  <P>
1918  Last updated: 16 May 2005  Last updated: 21 August 2007
1919    <br>
1920    Copyright &copy; 1997-2007 University of Cambridge.
1921  <br>  <br>
 Copyright &copy; 1997-2005 University of Cambridge.  
1922  <p>  <p>
1923  Return to the <a href="index.html">PCRE index page</a>.  Return to the <a href="index.html">PCRE index page</a>.
1924  </p>  </p>

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