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revision 76 by nigel, Sat Feb 24 21:40:37 2007 UTC revision 77 by nigel, Sat Feb 24 21:40:45 2007 UTC
# Line 6  PCRE - Perl-compatible regular expressio Line 6  PCRE - Perl-compatible regular expressio
6  .sp  .sp
7  The PCRE library is a set of functions that implement regular expression  The PCRE library is a set of functions that implement regular expression
8  pattern matching using the same syntax and semantics as Perl, with just a few  pattern matching using the same syntax and semantics as Perl, with just a few
9  differences. The current implementation of PCRE (release 5.x) corresponds  differences. The current implementation of PCRE (release 6.x) corresponds
10  approximately with Perl 5.8, including support for UTF-8 encoded strings and  approximately with Perl 5.8, including support for UTF-8 encoded strings and
11  Unicode general category properties. However, this support has to be explicitly  Unicode general category properties. However, this support has to be explicitly
12  enabled; it is not the default.  enabled; it is not the default.
13  .P  .P
14    In addition to the Perl-compatible matching function, PCRE also contains an
15    alternative matching function that matches the same compiled patterns in a
16    different way. In certain circumstances, the alternative function has some
17    advantages. For a discussion of the two matching algorithms, see the
18    .\" HREF
19    \fBpcrematching\fP
20    .\"
21    page.
22    .P
23  PCRE is written in C and released as a C library. A number of people have  PCRE is written in C and released as a C library. A number of people have
24  written wrappers and interfaces of various kinds. A C++ class is included in  written wrappers and interfaces of various kinds. In particular, Google Inc.
25  these contributions, which can be found in the \fIContrib\fR directory at the  have provided a comprehensive C++ wrapper. This is now included as part of the
26  primary FTP site, which is:  PCRE distribution. The
27    .\" HREF
28    \fBpcrecpp\fP
29    .\"
30    page has details of this interface. Other people's contributions can be found
31    in the \fIContrib\fR directory at the primary FTP site, which is:
32  .sp  .sp
33  .\" HTML <a href="ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre">  .\" HTML <a href="ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre">
34  .\" </a>  .\" </a>
# Line 43  available. The features themselves are d Line 57  available. The features themselves are d
57  .\"  .\"
58  page. Documentation about building PCRE for various operating systems can be  page. Documentation about building PCRE for various operating systems can be
59  found in the \fBREADME\fP file in the source distribution.  found in the \fBREADME\fP file in the source distribution.
60    .P
61    The library contains a number of undocumented internal functions and data
62    tables that are used by more than one of the exported external functions, but
63    which are not intended for use by external callers. Their names all begin with
64    "_pcre_", which hopefully will not provoke any name clashes.
65  .  .
66  .  .
67  .SH "USER DOCUMENTATION"  .SH "USER DOCUMENTATION"
# Line 55  all the sections are concatenated, for e Line 74  all the sections are concatenated, for e
74  follows:  follows:
75  .sp  .sp
76    pcre              this document    pcre              this document
77    pcreapi           details of PCRE's native API    pcreapi           details of PCRE's native C API
78    pcrebuild         options for building PCRE    pcrebuild         options for building PCRE
79    pcrecallout       details of the callout feature    pcrecallout       details of the callout feature
80    pcrecompat        discussion of Perl compatibility    pcrecompat        discussion of Perl compatibility
81      pcrecpp           details of the C++ wrapper
82    pcregrep          description of the \fBpcregrep\fP command    pcregrep          description of the \fBpcregrep\fP command
83      pcrematching      discussion of the two matching algorithms
84    pcrepartial       details of the partial matching facility    pcrepartial       details of the partial matching facility
85  .\" JOIN  .\" JOIN
86    pcrepattern       syntax and semantics of supported    pcrepattern       syntax and semantics of supported
87                        regular expressions                        regular expressions
88    pcreperform       discussion of performance issues    pcreperform       discussion of performance issues
89    pcreposix         the POSIX-compatible API    pcreposix         the POSIX-compatible C API
90    pcreprecompile    details of saving and re-using precompiled patterns    pcreprecompile    details of saving and re-using precompiled patterns
91    pcresample        discussion of the sample program    pcresample        discussion of the sample program
92    pcretest          description of the \fBpcretest\fP testing command    pcretest          description of the \fBpcretest\fP testing command
93  .sp  .sp
94  In addition, in the "man" and HTML formats, there is a short page for each  In addition, in the "man" and HTML formats, there is a short page for each
95  library function, listing its arguments and results.  C library function, listing its arguments and results.
96  .  .
97  .  .
98  .SH LIMITATIONS  .SH LIMITATIONS
# Line 99  depth of nesting of all kinds of parenth Line 120  depth of nesting of all kinds of parenth
120  subpatterns, assertions, and other types of subpattern, is 200.  subpatterns, assertions, and other types of subpattern, is 200.
121  .P  .P
122  The maximum length of a subject string is the largest positive number that an  The maximum length of a subject string is the largest positive number that an
123  integer variable can hold. However, PCRE uses recursion to handle subpatterns  integer variable can hold. However, when using the traditional matching
124  and indefinite repetition. This means that the available stack space may limit  function, PCRE uses recursion to handle subpatterns and indefinite repetition.
125  the size of a subject string that can be processed by certain patterns.  This means that the available stack space may limit the size of a subject
126    string that can be processed by certain patterns.
127  .sp  .sp
128  .\" HTML <a name="utf8support"></a>  .\" HTML <a name="utf8support"></a>
129  .  .
# Line 167  bytes, for example: \ex{100}{3}. Line 189  bytes, for example: \ex{100}{3}.
189  5. The dot metacharacter matches one UTF-8 character instead of a single byte.  5. The dot metacharacter matches one UTF-8 character instead of a single byte.
190  .P  .P
191  6. The escape sequence \eC can be used to match a single byte in UTF-8 mode,  6. The escape sequence \eC can be used to match a single byte in UTF-8 mode,
192  but its use can lead to some strange effects.  but its use can lead to some strange effects. This facility is not available in
193    the alternative matching function, \fBpcre_dfa_exec()\fP.
194  .P  .P
195  7. The character escapes \eb, \eB, \ed, \eD, \es, \eS, \ew, and \eW correctly  7. The character escapes \eb, \eB, \ed, \eD, \es, \eS, \ew, and \eW correctly
196  test characters of any code value, but the characters that PCRE recognizes as  test characters of any code value, but the characters that PCRE recognizes as
# Line 190  values. Line 213  values.
213  .SH AUTHOR  .SH AUTHOR
214  .rs  .rs
215  .sp  .sp
216  Philip Hazel <ph10@cam.ac.uk>  Philip Hazel
217  .br  .br
218  University Computing Service,  University Computing Service,
219  .br  .br
220  Cambridge CB2 3QG, England.  Cambridge CB2 3QG, England.
221  .br  .P
222  Phone: +44 1223 334714  Putting an actual email address here seems to have been a spam magnet, so I've
223    taken it away. If you want to email me, use my initial and surname, separated
224    by a dot, at the domain ucs.cam.ac.uk.
225  .sp  .sp
226  .in 0  .in 0
227  Last updated: 09 September 2004  Last updated: 07 March 2005
228  .br  .br
229  Copyright (c) 1997-2004 University of Cambridge.  Copyright (c) 1997-2005 University of Cambridge.

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