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Revision 846 - (show annotations)
Tue Jan 3 13:57:27 2012 UTC (7 years, 9 months ago) by ph10
File size: 6084 byte(s)
Documentation update for 16-bit.
1 .TH PCRE 3
3 PCRE - Perl-compatible regular expressions
5 .rs
6 .sp
7 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
9 differences. Some features that appeared in Python and PCRE before they
10 appeared in Perl are also available using the Python syntax, there is some
11 support for one or two .NET and Oniguruma syntax items, and there is an option
12 for requesting some minor changes that give better JavaScript compatibility.
13 .P
14 Starting with release 8.30, it is possible to compile two separate PCRE
15 libraries: the original, which supports 8-bit character strings (including
16 UTF-8 strings), and a second library that supports 16-bit character strings
17 (including UTF-16 strings). The build process allows either one or both to be
18 built. The majority of the work to make this possible was done by Zoltan
19 Herczeg.
20 .P
21 The two libraries contain identical sets of functions, except that the names in
22 the 16-bit library start with \fBpcre16_\fP instead of \fBpcre_\fP. To avoid
23 over-complication and reduce the documentation maintenance load, most of the
24 documentation describes the 8-bit library, with the differences for the 16-bit
25 library described separately in the
26 .\" HREF
27 \fBpcre16\fP
28 .\"
29 page.
30 .P
31 The current implementation of PCRE corresponds approximately with Perl 5.12,
32 including support for UTF-8/16 encoded strings and Unicode general category
33 properties. However, UTF-8/16 and Unicode support has to be explicitly enabled;
34 it is not the default. The Unicode tables correspond to Unicode release 6.0.0.
35 .P
36 In addition to the Perl-compatible matching function, PCRE contains an
37 alternative function that matches the same compiled patterns in a different
38 way. In certain circumstances, the alternative function has some advantages.
39 For a discussion of the two matching algorithms, see the
40 .\" HREF
41 \fBpcrematching\fP
42 .\"
43 page.
44 .P
45 PCRE is written in C and released as a C library. A number of people have
46 written wrappers and interfaces of various kinds. In particular, Google Inc.
47 have provided a comprehensive C++ wrapper for the 8-bit library. This is now
48 included as part of the PCRE distribution. The
49 .\" HREF
50 \fBpcrecpp\fP
51 .\"
52 page has details of this interface. Other people's contributions can be found
53 in the \fIContrib\fP directory at the primary FTP site, which is:
54 .sp
55 .\" HTML <a href="ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre">
56 .\" </a>
57 ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre
58 .P
59 Details of exactly which Perl regular expression features are and are not
60 supported by PCRE are given in separate documents. See the
61 .\" HREF
62 \fBpcrepattern\fP
63 .\"
64 and
65 .\" HREF
66 \fBpcrecompat\fP
67 .\"
68 pages. There is a syntax summary in the
69 .\" HREF
70 \fBpcresyntax\fP
71 .\"
72 page.
73 .P
74 Some features of PCRE can be included, excluded, or changed when the library is
75 built. The
76 .\" HREF
77 \fBpcre_config()\fP
78 .\"
79 function makes it possible for a client to discover which features are
80 available. The features themselves are described in the
81 .\" HREF
82 \fBpcrebuild\fP
83 .\"
84 page. Documentation about building PCRE for various operating systems can be
85 found in the \fBREADME\fP and \fBNON-UNIX-USE\fP files in the source
86 distribution.
87 .P
88 The libraries contains a number of undocumented internal functions and data
89 tables that are used by more than one of the exported external functions, but
90 which are not intended for use by external callers. Their names all begin with
91 "_pcre_" or "_pcre16_", which hopefully will not provoke any name clashes. In
92 some environments, it is possible to control which external symbols are
93 exported when a shared library is built, and in these cases the undocumented
94 symbols are not exported.
95 .
96 .
98 .rs
99 .sp
100 The user documentation for PCRE comprises a number of different sections. In
101 the "man" format, each of these is a separate "man page". In the HTML format,
102 each is a separate page, linked from the index page. In the plain text format,
103 all the sections, except the \fBpcredemo\fP section, are concatenated, for ease
104 of searching. The sections are as follows:
105 .sp
106 pcre this document
107 pcre16 details of the 16-bit library
108 pcre-config show PCRE installation configuration information
109 pcreapi details of PCRE's native C API
110 pcrebuild options for building PCRE
111 pcrecallout details of the callout feature
112 pcrecompat discussion of Perl compatibility
113 pcrecpp details of the C++ wrapper for the 8-bit library
114 pcredemo a demonstration C program that uses PCRE
115 pcregrep description of the \fBpcregrep\fP command (8-bit only)
116 pcrejit discussion of the just-in-time optimization support
117 pcrelimits details of size and other limits
118 pcrematching discussion of the two matching algorithms
119 pcrepartial details of the partial matching facility
120 .\" JOIN
121 pcrepattern syntax and semantics of supported
122 regular expressions
123 pcreperform discussion of performance issues
124 pcreposix the POSIX-compatible C API for the 8-bit library
125 pcreprecompile details of saving and re-using precompiled patterns
126 pcresample discussion of the pcredemo program
127 pcrestack discussion of stack usage
128 pcresyntax quick syntax reference
129 pcretest description of the \fBpcretest\fP testing command
130 pcreunicode discussion of Unicode and UTF-8/16 support
131 .sp
132 In addition, in the "man" and HTML formats, there is a short page for each
133 8-bit C library function, listing its arguments and results.
134 .
135 .
137 .rs
138 .sp
139 .nf
140 Philip Hazel
141 University Computing Service
142 Cambridge CB2 3QH, England.
143 .fi
144 .P
145 Putting an actual email address here seems to have been a spam magnet, so I've
146 taken it away. If you want to email me, use my two initials, followed by the
147 two digits 10, at the domain cam.ac.uk.
148 .
149 .
151 .rs
152 .sp
153 .nf
154 Last updated: 01 January 2012
155 Copyright (c) 1997-2012 University of Cambridge.
156 .fi


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