/[pcre]/code/trunk/doc/html/pcrebuild.html
ViewVC logotype

Contents of /code/trunk/doc/html/pcrebuild.html

Parent Directory Parent Directory | Revision Log Revision Log


Revision 111 - (hide annotations) (download) (as text)
Thu Mar 8 16:53:09 2007 UTC (7 years, 7 months ago) by ph10
File MIME type: text/html
File size: 10564 byte(s)
Create the PrepareRelease script to process the documentation and create the 
.generic files for distribution, also to remove trailing spaces. Update a lot 
more of the build-time documentation. Arrange for PrepareRelease and its 
sub-scripts to be distributed.

1 nigel 63 <html>
2     <head>
3     <title>pcrebuild specification</title>
4     </head>
5     <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
6 nigel 75 <h1>pcrebuild man page</h1>
7     <p>
8     Return to the <a href="index.html">PCRE index page</a>.
9     </p>
10 ph10 111 <p>
11 nigel 75 This page is part of the PCRE HTML documentation. It was generated automatically
12     from the original man page. If there is any nonsense in it, please consult the
13     man page, in case the conversion went wrong.
14 ph10 111 <br>
15 nigel 63 <ul>
16     <li><a name="TOC1" href="#SEC1">PCRE BUILD-TIME OPTIONS</a>
17 nigel 83 <li><a name="TOC2" href="#SEC2">C++ SUPPORT</a>
18     <li><a name="TOC3" href="#SEC3">UTF-8 SUPPORT</a>
19     <li><a name="TOC4" href="#SEC4">UNICODE CHARACTER PROPERTY SUPPORT</a>
20     <li><a name="TOC5" href="#SEC5">CODE VALUE OF NEWLINE</a>
21     <li><a name="TOC6" href="#SEC6">BUILDING SHARED AND STATIC LIBRARIES</a>
22     <li><a name="TOC7" href="#SEC7">POSIX MALLOC USAGE</a>
23 nigel 91 <li><a name="TOC8" href="#SEC8">HANDLING VERY LARGE PATTERNS</a>
24     <li><a name="TOC9" href="#SEC9">AVOIDING EXCESSIVE STACK USAGE</a>
25     <li><a name="TOC10" href="#SEC10">LIMITING PCRE RESOURCE USAGE</a>
26 nigel 83 <li><a name="TOC11" href="#SEC11">USING EBCDIC CODE</a>
27 nigel 93 <li><a name="TOC12" href="#SEC12">SEE ALSO</a>
28 ph10 99 <li><a name="TOC13" href="#SEC13">AUTHOR</a>
29     <li><a name="TOC14" href="#SEC14">REVISION</a>
30 nigel 63 </ul>
31     <br><a name="SEC1" href="#TOC1">PCRE BUILD-TIME OPTIONS</a><br>
32     <P>
33     This document describes the optional features of PCRE that can be selected when
34     the library is compiled. They are all selected, or deselected, by providing
35 nigel 75 options to the <b>configure</b> script that is run before the <b>make</b>
36 nigel 63 command. The complete list of options for <b>configure</b> (which includes the
37     standard ones such as the selection of the installation directory) can be
38     obtained by running
39     <pre>
40     ./configure --help
41 nigel 75 </pre>
42 nigel 63 The following sections describe certain options whose names begin with --enable
43     or --disable. These settings specify changes to the defaults for the
44     <b>configure</b> command. Because of the way that <b>configure</b> works,
45     --enable and --disable always come in pairs, so the complementary option always
46     exists as well, but as it specifies the default, it is not described.
47     </P>
48 nigel 83 <br><a name="SEC2" href="#TOC1">C++ SUPPORT</a><br>
49 nigel 63 <P>
50 nigel 83 By default, the <b>configure</b> script will search for a C++ compiler and C++
51     header files. If it finds them, it automatically builds the C++ wrapper library
52     for PCRE. You can disable this by adding
53     <pre>
54     --disable-cpp
55     </pre>
56     to the <b>configure</b> command.
57     </P>
58     <br><a name="SEC3" href="#TOC1">UTF-8 SUPPORT</a><br>
59     <P>
60 nigel 63 To build PCRE with support for UTF-8 character strings, add
61     <pre>
62     --enable-utf8
63 nigel 75 </pre>
64 nigel 63 to the <b>configure</b> command. Of itself, this does not make PCRE treat
65     strings as UTF-8. As well as compiling PCRE with this option, you also have
66     have to set the PCRE_UTF8 option when you call the <b>pcre_compile()</b>
67     function.
68     </P>
69 nigel 83 <br><a name="SEC4" href="#TOC1">UNICODE CHARACTER PROPERTY SUPPORT</a><br>
70 nigel 63 <P>
71 nigel 75 UTF-8 support allows PCRE to process character values greater than 255 in the
72     strings that it handles. On its own, however, it does not provide any
73     facilities for accessing the properties of such characters. If you want to be
74     able to use the pattern escapes \P, \p, and \X, which refer to Unicode
75     character properties, you must add
76     <pre>
77     --enable-unicode-properties
78     </pre>
79     to the <b>configure</b> command. This implies UTF-8 support, even if you have
80     not explicitly requested it.
81     </P>
82     <P>
83     Including Unicode property support adds around 90K of tables to the PCRE
84     library, approximately doubling its size. Only the general category properties
85     such as <i>Lu</i> and <i>Nd</i> are supported. Details are given in the
86     <a href="pcrepattern.html"><b>pcrepattern</b></a>
87     documentation.
88     </P>
89 nigel 83 <br><a name="SEC5" href="#TOC1">CODE VALUE OF NEWLINE</a><br>
90 nigel 75 <P>
91 nigel 91 By default, PCRE interprets character 10 (linefeed, LF) as indicating the end
92     of a line. This is the normal newline character on Unix-like systems. You can
93     compile PCRE to use character 13 (carriage return, CR) instead, by adding
94 nigel 63 <pre>
95     --enable-newline-is-cr
96 nigel 75 </pre>
97 nigel 91 to the <b>configure</b> command. There is also a --enable-newline-is-lf option,
98     which explicitly specifies linefeed as the newline character.
99     <br>
100     <br>
101     Alternatively, you can specify that line endings are to be indicated by the two
102     character sequence CRLF. If you want this, add
103     <pre>
104     --enable-newline-is-crlf
105     </pre>
106 nigel 93 to the <b>configure</b> command. There is a fourth option, specified by
107     <pre>
108     --enable-newline-is-any
109     </pre>
110     which causes PCRE to recognize any Unicode newline sequence.
111 nigel 63 </P>
112 nigel 93 <P>
113     Whatever line ending convention is selected when PCRE is built can be
114     overridden when the library functions are called. At build time it is
115     conventional to use the standard for your operating system.
116     </P>
117 nigel 83 <br><a name="SEC6" href="#TOC1">BUILDING SHARED AND STATIC LIBRARIES</a><br>
118 nigel 63 <P>
119     The PCRE building process uses <b>libtool</b> to build both shared and static
120     Unix libraries by default. You can suppress one of these by adding one of
121     <pre>
122     --disable-shared
123     --disable-static
124 nigel 75 </pre>
125 nigel 63 to the <b>configure</b> command, as required.
126     </P>
127 nigel 83 <br><a name="SEC7" href="#TOC1">POSIX MALLOC USAGE</a><br>
128 nigel 63 <P>
129 nigel 75 When PCRE is called through the POSIX interface (see the
130     <a href="pcreposix.html"><b>pcreposix</b></a>
131 nigel 63 documentation), additional working storage is required for holding the pointers
132 nigel 75 to capturing substrings, because PCRE requires three integers per substring,
133 nigel 63 whereas the POSIX interface provides only two. If the number of expected
134     substrings is small, the wrapper function uses space on the stack, because this
135     is faster than using <b>malloc()</b> for each call. The default threshold above
136     which the stack is no longer used is 10; it can be changed by adding a setting
137     such as
138     <pre>
139     --with-posix-malloc-threshold=20
140 nigel 75 </pre>
141 nigel 63 to the <b>configure</b> command.
142     </P>
143 nigel 91 <br><a name="SEC8" href="#TOC1">HANDLING VERY LARGE PATTERNS</a><br>
144 nigel 63 <P>
145     Within a compiled pattern, offset values are used to point from one part to
146     another (for example, from an opening parenthesis to an alternation
147 nigel 75 metacharacter). By default, two-byte values are used for these offsets, leading
148 nigel 63 to a maximum size for a compiled pattern of around 64K. This is sufficient to
149     handle all but the most gigantic patterns. Nevertheless, some people do want to
150     process enormous patterns, so it is possible to compile PCRE to use three-byte
151     or four-byte offsets by adding a setting such as
152     <pre>
153     --with-link-size=3
154 nigel 75 </pre>
155 nigel 63 to the <b>configure</b> command. The value given must be 2, 3, or 4. Using
156     longer offsets slows down the operation of PCRE because it has to load
157     additional bytes when handling them.
158     </P>
159     <P>
160     If you build PCRE with an increased link size, test 2 (and test 5 if you are
161     using UTF-8) will fail. Part of the output of these tests is a representation
162     of the compiled pattern, and this changes with the link size.
163     </P>
164 nigel 91 <br><a name="SEC9" href="#TOC1">AVOIDING EXCESSIVE STACK USAGE</a><br>
165 nigel 63 <P>
166 nigel 77 When matching with the <b>pcre_exec()</b> function, PCRE implements backtracking
167     by making recursive calls to an internal function called <b>match()</b>. In
168     environments where the size of the stack is limited, this can severely limit
169     PCRE's operation. (The Unix environment does not usually suffer from this
170 nigel 91 problem, but it may sometimes be necessary to increase the maximum stack size.
171     There is a discussion in the
172     <a href="pcrestack.html"><b>pcrestack</b></a>
173     documentation.) An alternative approach to recursion that uses memory from the
174     heap to remember data, instead of using recursive function calls, has been
175     implemented to work round the problem of limited stack size. If you want to
176     build a version of PCRE that works this way, add
177 nigel 73 <pre>
178     --disable-stack-for-recursion
179 nigel 75 </pre>
180 nigel 73 to the <b>configure</b> command. With this configuration, PCRE will use the
181     <b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> variables to call memory
182     management functions. Separate functions are provided because the usage is very
183     predictable: the block sizes requested are always the same, and the blocks are
184     always freed in reverse order. A calling program might be able to implement
185     optimized functions that perform better than the standard <b>malloc()</b> and
186     <b>free()</b> functions. PCRE runs noticeably more slowly when built in this
187 nigel 77 way. This option affects only the <b>pcre_exec()</b> function; it is not
188     relevant for the the <b>pcre_dfa_exec()</b> function.
189 nigel 73 </P>
190 nigel 91 <br><a name="SEC10" href="#TOC1">LIMITING PCRE RESOURCE USAGE</a><br>
191     <P>
192     Internally, PCRE has a function called <b>match()</b>, which it calls repeatedly
193     (sometimes recursively) when matching a pattern with the <b>pcre_exec()</b>
194     function. By controlling the maximum number of times this function may be
195     called during a single matching operation, a limit can be placed on the
196     resources used by a single call to <b>pcre_exec()</b>. The limit can be changed
197     at run time, as described in the
198     <a href="pcreapi.html"><b>pcreapi</b></a>
199     documentation. The default is 10 million, but this can be changed by adding a
200     setting such as
201     <pre>
202     --with-match-limit=500000
203     </pre>
204     to the <b>configure</b> command. This setting has no effect on the
205     <b>pcre_dfa_exec()</b> matching function.
206     </P>
207     <P>
208     In some environments it is desirable to limit the depth of recursive calls of
209     <b>match()</b> more strictly than the total number of calls, in order to
210     restrict the maximum amount of stack (or heap, if --disable-stack-for-recursion
211     is specified) that is used. A second limit controls this; it defaults to the
212     value that is set for --with-match-limit, which imposes no additional
213     constraints. However, you can set a lower limit by adding, for example,
214     <pre>
215     --with-match-limit-recursion=10000
216     </pre>
217     to the <b>configure</b> command. This value can also be overridden at run time.
218     </P>
219 nigel 83 <br><a name="SEC11" href="#TOC1">USING EBCDIC CODE</a><br>
220 nigel 73 <P>
221     PCRE assumes by default that it will run in an environment where the character
222 nigel 75 code is ASCII (or Unicode, which is a superset of ASCII). PCRE can, however, be
223 nigel 73 compiled to run in an EBCDIC environment by adding
224     <pre>
225     --enable-ebcdic
226 nigel 75 </pre>
227 nigel 73 to the <b>configure</b> command.
228     </P>
229 nigel 93 <br><a name="SEC12" href="#TOC1">SEE ALSO</a><br>
230 nigel 73 <P>
231 nigel 93 <b>pcreapi</b>(3), <b>pcre_config</b>(3).
232     </P>
233 ph10 99 <br><a name="SEC13" href="#TOC1">AUTHOR</a><br>
234 nigel 93 <P>
235 ph10 99 Philip Hazel
236 nigel 63 <br>
237 ph10 99 University Computing Service
238     <br>
239     Cambridge CB2 3QH, England.
240     <br>
241     </P>
242     <br><a name="SEC14" href="#TOC1">REVISION</a><br>
243     <P>
244     Last updated: 06 March 2007
245     <br>
246     Copyright &copy; 1997-2007 University of Cambridge.
247     <br>
248 nigel 75 <p>
249     Return to the <a href="index.html">PCRE index page</a>.
250     </p>

Properties

Name Value
svn:eol-style native
svn:keywords "Author Date Id Revision Url"

webmaster@exim.org
ViewVC Help
Powered by ViewVC 1.1.12