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Tue Mar 6 12:27:42 2007 UTC (8 years, 1 month ago) by ph10
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1. Move the comment about version numbers from pcre.h.in to configure.ac 
because that's where they are now set.
2. Update all the man pages to remove the use of .br and .in because this
causes trouble for some HTML converters. Also standardised the final sections 
giving author information and revision date.
3. Update the maintain/132html man page converter to handle .nf/.fi and to barf 
at .br/.in.

1 nigel 41 .TH PCRE 3
2     .SH NAME
3 nigel 63 PCRE - Perl-compatible regular expressions
5 nigel 63 .rs
6     .sp
7 nigel 41 The PCRE library is a set of functions that implement regular expression
8 nigel 63 pattern matching using the same syntax and semantics as Perl, with just a few
9 nigel 93 differences. (Certain features that appeared in Python and PCRE before they
10     appeared in Perl are also available using the Python syntax.)
11 nigel 75 .P
12 nigel 93 The current implementation of PCRE (release 7.x) corresponds approximately with
13     Perl 5.10, including support for UTF-8 encoded strings and Unicode general
14     category properties. However, UTF-8 and Unicode support has to be explicitly
15     enabled; it is not the default. The Unicode tables correspond to Unicode
16     release 5.0.0.
17     .P
18     In addition to the Perl-compatible matching function, PCRE contains an
19 nigel 77 alternative matching function that matches the same compiled patterns in a
20     different way. In certain circumstances, the alternative function has some
21     advantages. For a discussion of the two matching algorithms, see the
22     .\" HREF
23     \fBpcrematching\fP
24     .\"
25     page.
26     .P
27 nigel 75 PCRE is written in C and released as a C library. A number of people have
28 nigel 77 written wrappers and interfaces of various kinds. In particular, Google Inc.
29     have provided a comprehensive C++ wrapper. This is now included as part of the
30     PCRE distribution. The
31     .\" HREF
32     \fBpcrecpp\fP
33     .\"
34     page has details of this interface. Other people's contributions can be found
35     in the \fIContrib\fR directory at the primary FTP site, which is:
36 nigel 75 .sp
37 nigel 63 .\" HTML <a href="ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre">
38     .\" </a>
39     ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre
40 nigel 75 .P
41 nigel 63 Details of exactly which Perl regular expression features are and are not
42     supported by PCRE are given in separate documents. See the
43     .\" HREF
44     \fBpcrepattern\fR
45     .\"
46     and
47     .\" HREF
48     \fBpcrecompat\fR
49     .\"
50     pages.
51 nigel 75 .P
52 nigel 63 Some features of PCRE can be included, excluded, or changed when the library is
53     built. The
54     .\" HREF
55     \fBpcre_config()\fR
56     .\"
57     function makes it possible for a client to discover which features are
58 nigel 75 available. The features themselves are described in the
59     .\" HREF
60     \fBpcrebuild\fP
61     .\"
62     page. Documentation about building PCRE for various operating systems can be
63     found in the \fBREADME\fP file in the source distribution.
64 nigel 77 .P
65     The library contains a number of undocumented internal functions and data
66     tables that are used by more than one of the exported external functions, but
67     which are not intended for use by external callers. Their names all begin with
68 nigel 83 "_pcre_", which hopefully will not provoke any name clashes. In some
69     environments, it is possible to control which external symbols are exported
70     when a shared library is built, and in these cases the undocumented symbols are
71     not exported.
72 nigel 75 .
73     .
75 nigel 63 .rs
76     .sp
77 nigel 75 The user documentation for PCRE comprises a number of different sections. In
78     the "man" format, each of these is a separate "man page". In the HTML format,
79     each is a separate page, linked from the index page. In the plain text format,
80     all the sections are concatenated, for ease of searching. The sections are as
81     follows:
82     .sp
83 nigel 63 pcre this document
84 nigel 77 pcreapi details of PCRE's native C API
85 nigel 63 pcrebuild options for building PCRE
86     pcrecallout details of the callout feature
87     pcrecompat discussion of Perl compatibility
88 nigel 77 pcrecpp details of the C++ wrapper
89 nigel 75 pcregrep description of the \fBpcregrep\fP command
90 nigel 77 pcrematching discussion of the two matching algorithms
91 nigel 75 pcrepartial details of the partial matching facility
92     .\" JOIN
93 nigel 63 pcrepattern syntax and semantics of supported
94     regular expressions
95     pcreperform discussion of performance issues
96 nigel 77 pcreposix the POSIX-compatible C API
97 nigel 75 pcreprecompile details of saving and re-using precompiled patterns
98 nigel 63 pcresample discussion of the sample program
99 nigel 91 pcrestack discussion of stack usage
100 nigel 75 pcretest description of the \fBpcretest\fP testing command
101     .sp
102 nigel 63 In addition, in the "man" and HTML formats, there is a short page for each
103 nigel 77 C library function, listing its arguments and results.
104 nigel 75 .
105     .
106 nigel 41 .SH LIMITATIONS
107 nigel 63 .rs
108     .sp
109 nigel 41 There are some size limitations in PCRE but it is hoped that they will never in
110     practice be relevant.
111 nigel 75 .P
112 nigel 63 The maximum length of a compiled pattern is 65539 (sic) bytes if PCRE is
113     compiled with the default internal linkage size of 2. If you want to process
114     regular expressions that are truly enormous, you can compile PCRE with an
115 nigel 75 internal linkage size of 3 or 4 (see the \fBREADME\fP file in the source
116 nigel 63 distribution and the
117     .\" HREF
118 nigel 75 \fBpcrebuild\fP
119 nigel 63 .\"
120 nigel 75 documentation for details). In these cases the limit is substantially larger.
121 nigel 93 However, the speed of execution is slower.
122 nigel 75 .P
123 nigel 91 All values in repeating quantifiers must be less than 65536. The maximum
124     compiled length of subpattern with an explicit repeat count is 30000 bytes. The
125     maximum number of capturing subpatterns is 65535.
126 nigel 75 .P
127 nigel 93 There is no limit to the number of parenthesized subpatterns, but there can be
128     no more than 65535 capturing subpatterns.
129 nigel 75 .P
130 nigel 93 The maximum length of name for a named subpattern is 32 characters, and the
131     maximum number of named subpatterns is 10000.
132 nigel 91 .P
133 nigel 41 The maximum length of a subject string is the largest positive number that an
134 nigel 77 integer variable can hold. However, when using the traditional matching
135     function, PCRE uses recursion to handle subpatterns and indefinite repetition.
136     This means that the available stack space may limit the size of a subject
137 nigel 91 string that can be processed by certain patterns. For a discussion of stack
138     issues, see the
139     .\" HREF
140     \fBpcrestack\fP
141     .\"
142     documentation.
143 nigel 75 .sp
144 nigel 63 .\" HTML <a name="utf8support"></a>
145 nigel 75 .
146     .
148 nigel 63 .rs
149     .sp
150 nigel 75 From release 3.3, PCRE has had some support for character strings encoded in
151     the UTF-8 format. For release 4.0 this was greatly extended to cover most
152     common requirements, and in release 5.0 additional support for Unicode general
153     category properties was added.
154     .P
155 nigel 63 In order process UTF-8 strings, you must build PCRE to include UTF-8 support in
156     the code, and, in addition, you must call
157     .\" HREF
158 nigel 75 \fBpcre_compile()\fP
159 nigel 63 .\"
160     with the PCRE_UTF8 option flag. When you do this, both the pattern and any
161     subject strings that are matched against it are treated as UTF-8 strings
162     instead of just strings of bytes.
163 nigel 75 .P
164 nigel 49 If you compile PCRE with UTF-8 support, but do not use it at run time, the
165     library will be a bit bigger, but the additional run time overhead is limited
166 nigel 93 to testing the PCRE_UTF8 flag occasionally, so should not be very big.
167 nigel 75 .P
168     If PCRE is built with Unicode character property support (which implies UTF-8
169     support), the escape sequences \ep{..}, \eP{..}, and \eX are supported.
170     The available properties that can be tested are limited to the general
171     category properties such as Lu for an upper case letter or Nd for a decimal
172 nigel 87 number, the Unicode script names such as Arabic or Han, and the derived
173     properties Any and L&. A full list is given in the
174 nigel 75 .\" HREF
175     \fBpcrepattern\fP
176     .\"
177 nigel 87 documentation. Only the short names for properties are supported. For example,
178     \ep{L} matches a letter. Its Perl synonym, \ep{Letter}, is not supported.
179     Furthermore, in Perl, many properties may optionally be prefixed by "Is", for
180     compatibility with Perl 5.6. PCRE does not support this.
181 nigel 75 .P
182 nigel 63 The following comments apply when PCRE is running in UTF-8 mode:
183 nigel 75 .P
184 nigel 71 1. When you set the PCRE_UTF8 flag, the strings passed as patterns and subjects
185     are checked for validity on entry to the relevant functions. If an invalid
186     UTF-8 string is passed, an error return is given. In some situations, you may
187     already know that your strings are valid, and therefore want to skip these
188     checks in order to improve performance. If you set the PCRE_NO_UTF8_CHECK flag
189     at compile time or at run time, PCRE assumes that the pattern or subject it
190     is given (respectively) contains only valid UTF-8 codes. In this case, it does
191     not diagnose an invalid UTF-8 string. If you pass an invalid UTF-8 string to
192     PCRE when PCRE_NO_UTF8_CHECK is set, the results are undefined. Your program
193     may crash.
194 nigel 75 .P
195 nigel 87 2. An unbraced hexadecimal escape sequence (such as \exb3) matches a two-byte
196     UTF-8 character if the value is greater than 127.
197 nigel 75 .P
198 nigel 91 3. Octal numbers up to \e777 are recognized, and match two-byte UTF-8
199     characters for values greater than \e177.
200     .P
201     4. Repeat quantifiers apply to complete UTF-8 characters, not to individual
202 nigel 75 bytes, for example: \ex{100}{3}.
203     .P
204 nigel 91 5. The dot metacharacter matches one UTF-8 character instead of a single byte.
205 nigel 75 .P
206 nigel 91 6. The escape sequence \eC can be used to match a single byte in UTF-8 mode,
207 nigel 77 but its use can lead to some strange effects. This facility is not available in
208     the alternative matching function, \fBpcre_dfa_exec()\fP.
209 nigel 75 .P
210 nigel 91 7. The character escapes \eb, \eB, \ed, \eD, \es, \eS, \ew, and \eW correctly
211 nigel 63 test characters of any code value, but the characters that PCRE recognizes as
212     digits, spaces, or word characters remain the same set as before, all with
213 nigel 75 values less than 256. This remains true even when PCRE includes Unicode
214     property support, because to do otherwise would slow down PCRE in many common
215     cases. If you really want to test for a wider sense of, say, "digit", you
216     must use Unicode property tests such as \ep{Nd}.
217     .P
218 nigel 91 8. Similarly, characters that match the POSIX named character classes are all
219 nigel 75 low-valued characters.
220     .P
221 nigel 91 9. Case-insensitive matching applies only to characters whose values are less
222 nigel 75 than 128, unless PCRE is built with Unicode property support. Even when Unicode
223     property support is available, PCRE still uses its own character tables when
224     checking the case of low-valued characters, so as not to degrade performance.
225     The Unicode property information is used only for characters with higher
226 nigel 87 values. Even when Unicode property support is available, PCRE supports
227     case-insensitive matching only when there is a one-to-one mapping between a
228     letter's cases. There are a small number of many-to-one mappings in Unicode;
229     these are not supported by PCRE.
230 nigel 75 .
231 ph10 99 .
232 nigel 41 .SH AUTHOR
233 nigel 63 .rs
234     .sp
235 ph10 99 .nf
236 nigel 77 Philip Hazel
237 ph10 99 University Computing Service
238 nigel 93 Cambridge CB2 3QH, England.
239 ph10 99 .fi
240 nigel 77 .P
241     Putting an actual email address here seems to have been a spam magnet, so I've
242     taken it away. If you want to email me, use my initial and surname, separated
243     by a dot, at the domain ucs.cam.ac.uk.
244 ph10 99 .
245     .
246     .SH REVISION
247     .rs
248 nigel 75 .sp
249 ph10 99 .nf
250     Last updated: 06 March 2007
251     Copyright (c) 1997-2007 University of Cambridge.
252     .fi


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