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1 <html>
2 <head>
3 <title>pcrebuild specification</title>
4 </head>
5 <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
6 <h1>pcrebuild man page</h1>
7 <p>
8 Return to the <a href="index.html">PCRE index page</a>.
9 </p>
10 <p>
11 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 <br>
15 <ul>
16 <li><a name="TOC1" href="#SEC1">PCRE BUILD-TIME OPTIONS</a>
17 <li><a name="TOC2" href="#SEC2">C++ SUPPORT</a>
18 <li><a name="TOC3" href="#SEC3">UTF-8 SUPPORT</a>
20 <li><a name="TOC5" href="#SEC5">CODE VALUE OF NEWLINE</a>
21 <li><a name="TOC6" href="#SEC6">WHAT \R MATCHES</a>
23 <li><a name="TOC8" href="#SEC8">POSIX MALLOC USAGE</a>
24 <li><a name="TOC9" href="#SEC9">HANDLING VERY LARGE PATTERNS</a>
25 <li><a name="TOC10" href="#SEC10">AVOIDING EXCESSIVE STACK USAGE</a>
26 <li><a name="TOC11" href="#SEC11">LIMITING PCRE RESOURCE USAGE</a>
27 <li><a name="TOC12" href="#SEC12">CREATING CHARACTER TABLES AT BUILD TIME</a>
28 <li><a name="TOC13" href="#SEC13">USING EBCDIC CODE</a>
30 <li><a name="TOC15" href="#SEC15">SEE ALSO</a>
31 <li><a name="TOC16" href="#SEC16">AUTHOR</a>
32 <li><a name="TOC17" href="#SEC17">REVISION</a>
33 </ul>
34 <br><a name="SEC1" href="#TOC1">PCRE BUILD-TIME OPTIONS</a><br>
35 <P>
36 This document describes the optional features of PCRE that can be selected when
37 the library is compiled. It assumes use of the <b>configure</b> script, where
38 the optional features are selected or deselected by providing options to
39 <b>configure</b> before running the <b>make</b> command. However, the same
40 options can be selected in both Unix-like and non-Unix-like environments using
41 the GUI facility of <b>CMakeSetup</b> if you are using <b>CMake</b> instead of
42 <b>configure</b> to build PCRE.
43 </P>
44 <P>
45 The complete list of options for <b>configure</b> (which includes the standard
46 ones such as the selection of the installation directory) can be obtained by
47 running
48 <pre>
49 ./configure --help
50 </pre>
51 The following sections include descriptions of options whose names begin with
52 --enable or --disable. These settings specify changes to the defaults for the
53 <b>configure</b> command. Because of the way that <b>configure</b> works,
54 --enable and --disable always come in pairs, so the complementary option always
55 exists as well, but as it specifies the default, it is not described.
56 </P>
57 <br><a name="SEC2" href="#TOC1">C++ SUPPORT</a><br>
58 <P>
59 By default, the <b>configure</b> script will search for a C++ compiler and C++
60 header files. If it finds them, it automatically builds the C++ wrapper library
61 for PCRE. You can disable this by adding
62 <pre>
63 --disable-cpp
64 </pre>
65 to the <b>configure</b> command.
66 </P>
67 <br><a name="SEC3" href="#TOC1">UTF-8 SUPPORT</a><br>
68 <P>
69 To build PCRE with support for UTF-8 character strings, add
70 <pre>
71 --enable-utf8
72 </pre>
73 to the <b>configure</b> command. Of itself, this does not make PCRE treat
74 strings as UTF-8. As well as compiling PCRE with this option, you also have
75 have to set the PCRE_UTF8 option when you call the <b>pcre_compile()</b>
76 function.
77 </P>
78 <br><a name="SEC4" href="#TOC1">UNICODE CHARACTER PROPERTY SUPPORT</a><br>
79 <P>
80 UTF-8 support allows PCRE to process character values greater than 255 in the
81 strings that it handles. On its own, however, it does not provide any
82 facilities for accessing the properties of such characters. If you want to be
83 able to use the pattern escapes \P, \p, and \X, which refer to Unicode
84 character properties, you must add
85 <pre>
86 --enable-unicode-properties
87 </pre>
88 to the <b>configure</b> command. This implies UTF-8 support, even if you have
89 not explicitly requested it.
90 </P>
91 <P>
92 Including Unicode property support adds around 30K of tables to the PCRE
93 library. Only the general category properties such as <i>Lu</i> and <i>Nd</i> are
94 supported. Details are given in the
95 <a href="pcrepattern.html"><b>pcrepattern</b></a>
96 documentation.
97 </P>
98 <br><a name="SEC5" href="#TOC1">CODE VALUE OF NEWLINE</a><br>
99 <P>
100 By default, PCRE interprets character 10 (linefeed, LF) as indicating the end
101 of a line. This is the normal newline character on Unix-like systems. You can
102 compile PCRE to use character 13 (carriage return, CR) instead, by adding
103 <pre>
104 --enable-newline-is-cr
105 </pre>
106 to the <b>configure</b> command. There is also a --enable-newline-is-lf option,
107 which explicitly specifies linefeed as the newline character.
108 <br>
109 <br>
110 Alternatively, you can specify that line endings are to be indicated by the two
111 character sequence CRLF. If you want this, add
112 <pre>
113 --enable-newline-is-crlf
114 </pre>
115 to the <b>configure</b> command. There is a fourth option, specified by
116 <pre>
117 --enable-newline-is-anycrlf
118 </pre>
119 which causes PCRE to recognize any of the three sequences CR, LF, or CRLF as
120 indicating a line ending. Finally, a fifth option, specified by
121 <pre>
122 --enable-newline-is-any
123 </pre>
124 causes PCRE to recognize any Unicode newline sequence.
125 </P>
126 <P>
127 Whatever line ending convention is selected when PCRE is built can be
128 overridden when the library functions are called. At build time it is
129 conventional to use the standard for your operating system.
130 </P>
131 <br><a name="SEC6" href="#TOC1">WHAT \R MATCHES</a><br>
132 <P>
133 By default, the sequence \R in a pattern matches any Unicode newline sequence,
134 whatever has been selected as the line ending sequence. If you specify
135 <pre>
136 --enable-bsr-anycrlf
137 </pre>
138 the default is changed so that \R matches only CR, LF, or CRLF. Whatever is
139 selected when PCRE is built can be overridden when the library functions are
140 called.
141 </P>
142 <br><a name="SEC7" href="#TOC1">BUILDING SHARED AND STATIC LIBRARIES</a><br>
143 <P>
144 The PCRE building process uses <b>libtool</b> to build both shared and static
145 Unix libraries by default. You can suppress one of these by adding one of
146 <pre>
147 --disable-shared
148 --disable-static
149 </pre>
150 to the <b>configure</b> command, as required.
151 </P>
152 <br><a name="SEC8" href="#TOC1">POSIX MALLOC USAGE</a><br>
153 <P>
154 When PCRE is called through the POSIX interface (see the
155 <a href="pcreposix.html"><b>pcreposix</b></a>
156 documentation), additional working storage is required for holding the pointers
157 to capturing substrings, because PCRE requires three integers per substring,
158 whereas the POSIX interface provides only two. If the number of expected
159 substrings is small, the wrapper function uses space on the stack, because this
160 is faster than using <b>malloc()</b> for each call. The default threshold above
161 which the stack is no longer used is 10; it can be changed by adding a setting
162 such as
163 <pre>
164 --with-posix-malloc-threshold=20
165 </pre>
166 to the <b>configure</b> command.
167 </P>
168 <br><a name="SEC9" href="#TOC1">HANDLING VERY LARGE PATTERNS</a><br>
169 <P>
170 Within a compiled pattern, offset values are used to point from one part to
171 another (for example, from an opening parenthesis to an alternation
172 metacharacter). By default, two-byte values are used for these offsets, leading
173 to a maximum size for a compiled pattern of around 64K. This is sufficient to
174 handle all but the most gigantic patterns. Nevertheless, some people do want to
175 process enormous patterns, so it is possible to compile PCRE to use three-byte
176 or four-byte offsets by adding a setting such as
177 <pre>
178 --with-link-size=3
179 </pre>
180 to the <b>configure</b> command. The value given must be 2, 3, or 4. Using
181 longer offsets slows down the operation of PCRE because it has to load
182 additional bytes when handling them.
183 </P>
184 <br><a name="SEC10" href="#TOC1">AVOIDING EXCESSIVE STACK USAGE</a><br>
185 <P>
186 When matching with the <b>pcre_exec()</b> function, PCRE implements backtracking
187 by making recursive calls to an internal function called <b>match()</b>. In
188 environments where the size of the stack is limited, this can severely limit
189 PCRE's operation. (The Unix environment does not usually suffer from this
190 problem, but it may sometimes be necessary to increase the maximum stack size.
191 There is a discussion in the
192 <a href="pcrestack.html"><b>pcrestack</b></a>
193 documentation.) An alternative approach to recursion that uses memory from the
194 heap to remember data, instead of using recursive function calls, has been
195 implemented to work round the problem of limited stack size. If you want to
196 build a version of PCRE that works this way, add
197 <pre>
198 --disable-stack-for-recursion
199 </pre>
200 to the <b>configure</b> command. With this configuration, PCRE will use the
201 <b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> variables to call memory
202 management functions. By default these point to <b>malloc()</b> and
203 <b>free()</b>, but you can replace the pointers so that your own functions are
204 used.
205 </P>
206 <P>
207 Separate functions are provided rather than using <b>pcre_malloc</b> and
208 <b>pcre_free</b> because the usage is very predictable: the block sizes
209 requested are always the same, and the blocks are always freed in reverse
210 order. A calling program might be able to implement optimized functions that
211 perform better than <b>malloc()</b> and <b>free()</b>. PCRE runs noticeably more
212 slowly when built in this way. This option affects only the <b>pcre_exec()</b>
213 function; it is not relevant for the the <b>pcre_dfa_exec()</b> function.
214 </P>
215 <br><a name="SEC11" href="#TOC1">LIMITING PCRE RESOURCE USAGE</a><br>
216 <P>
217 Internally, PCRE has a function called <b>match()</b>, which it calls repeatedly
218 (sometimes recursively) when matching a pattern with the <b>pcre_exec()</b>
219 function. By controlling the maximum number of times this function may be
220 called during a single matching operation, a limit can be placed on the
221 resources used by a single call to <b>pcre_exec()</b>. The limit can be changed
222 at run time, as described in the
223 <a href="pcreapi.html"><b>pcreapi</b></a>
224 documentation. The default is 10 million, but this can be changed by adding a
225 setting such as
226 <pre>
227 --with-match-limit=500000
228 </pre>
229 to the <b>configure</b> command. This setting has no effect on the
230 <b>pcre_dfa_exec()</b> matching function.
231 </P>
232 <P>
233 In some environments it is desirable to limit the depth of recursive calls of
234 <b>match()</b> more strictly than the total number of calls, in order to
235 restrict the maximum amount of stack (or heap, if --disable-stack-for-recursion
236 is specified) that is used. A second limit controls this; it defaults to the
237 value that is set for --with-match-limit, which imposes no additional
238 constraints. However, you can set a lower limit by adding, for example,
239 <pre>
240 --with-match-limit-recursion=10000
241 </pre>
242 to the <b>configure</b> command. This value can also be overridden at run time.
243 </P>
244 <br><a name="SEC12" href="#TOC1">CREATING CHARACTER TABLES AT BUILD TIME</a><br>
245 <P>
246 PCRE uses fixed tables for processing characters whose code values are less
247 than 256. By default, PCRE is built with a set of tables that are distributed
248 in the file <i>pcre_chartables.c.dist</i>. These tables are for ASCII codes
249 only. If you add
250 <pre>
251 --enable-rebuild-chartables
252 </pre>
253 to the <b>configure</b> command, the distributed tables are no longer used.
254 Instead, a program called <b>dftables</b> is compiled and run. This outputs the
255 source for new set of tables, created in the default locale of your C runtime
256 system. (This method of replacing the tables does not work if you are cross
257 compiling, because <b>dftables</b> is run on the local host. If you need to
258 create alternative tables when cross compiling, you will have to do so "by
259 hand".)
260 </P>
261 <br><a name="SEC13" href="#TOC1">USING EBCDIC CODE</a><br>
262 <P>
263 PCRE assumes by default that it will run in an environment where the character
264 code is ASCII (or Unicode, which is a superset of ASCII). This is the case for
265 most computer operating systems. PCRE can, however, be compiled to run in an
266 EBCDIC environment by adding
267 <pre>
268 --enable-ebcdic
269 </pre>
270 to the <b>configure</b> command. This setting implies
271 --enable-rebuild-chartables. You should only use it if you know that you are in
272 an EBCDIC environment (for example, an IBM mainframe operating system).
273 </P>
275 <P>
276 By default, <b>pcregrep</b> reads all files as plain text. You can build it so
277 that it recognizes files whose names end in <b>.gz</b> or <b>.bz2</b>, and reads
278 them with <b>libz</b> or <b>libbz2</b>, respectively, by adding one or both of
279 <pre>
280 --enable-pcregrep-libz
281 --enable-pcregrep-libbz2
282 </pre>
283 to the <b>configure</b> command. These options naturally require that the
284 relevant libraries are installed on your system. Configuration will fail if
285 they are not.
286 </P>
287 <br><a name="SEC15" href="#TOC1">SEE ALSO</a><br>
288 <P>
289 <b>pcreapi</b>(3), <b>pcre_config</b>(3).
290 </P>
291 <br><a name="SEC16" href="#TOC1">AUTHOR</a><br>
292 <P>
293 Philip Hazel
294 <br>
295 University Computing Service
296 <br>
297 Cambridge CB2 3QH, England.
298 <br>
299 </P>
300 <br><a name="SEC17" href="#TOC1">REVISION</a><br>
301 <P>
302 Last updated: 17 December 2007
303 <br>
304 Copyright &copy; 1997-2007 University of Cambridge.
305 <br>
306 <p>
307 Return to the <a href="index.html">PCRE index page</a>.
308 </p>


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