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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     <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 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 nigel 63 </ul>
29     <br><a name="SEC1" href="#TOC1">PCRE BUILD-TIME OPTIONS</a><br>
30     <P>
31     This document describes the optional features of PCRE that can be selected when
32     the library is compiled. They are all selected, or deselected, by providing
33 nigel 75 options to the <b>configure</b> script that is run before the <b>make</b>
34 nigel 63 command. The complete list of options for <b>configure</b> (which includes the
35     standard ones such as the selection of the installation directory) can be
36     obtained by running
37     <pre>
38     ./configure --help
39 nigel 75 </pre>
40 nigel 63 The following sections describe certain options whose names begin with --enable
41     or --disable. These settings specify changes to the defaults for the
42     <b>configure</b> command. Because of the way that <b>configure</b> works,
43     --enable and --disable always come in pairs, so the complementary option always
44     exists as well, but as it specifies the default, it is not described.
45     </P>
46 nigel 83 <br><a name="SEC2" href="#TOC1">C++ SUPPORT</a><br>
47 nigel 63 <P>
48 nigel 83 By default, the <b>configure</b> script will search for a C++ compiler and C++
49     header files. If it finds them, it automatically builds the C++ wrapper library
50     for PCRE. You can disable this by adding
51     <pre>
52     --disable-cpp
53     </pre>
54     to the <b>configure</b> command.
55     </P>
56     <br><a name="SEC3" href="#TOC1">UTF-8 SUPPORT</a><br>
57     <P>
58 nigel 63 To build PCRE with support for UTF-8 character strings, add
59     <pre>
60     --enable-utf8
61 nigel 75 </pre>
62 nigel 63 to the <b>configure</b> command. Of itself, this does not make PCRE treat
63     strings as UTF-8. As well as compiling PCRE with this option, you also have
64     have to set the PCRE_UTF8 option when you call the <b>pcre_compile()</b>
65     function.
66     </P>
67 nigel 83 <br><a name="SEC4" href="#TOC1">UNICODE CHARACTER PROPERTY SUPPORT</a><br>
68 nigel 63 <P>
69 nigel 75 UTF-8 support allows PCRE to process character values greater than 255 in the
70     strings that it handles. On its own, however, it does not provide any
71     facilities for accessing the properties of such characters. If you want to be
72     able to use the pattern escapes \P, \p, and \X, which refer to Unicode
73     character properties, you must add
74     <pre>
75     --enable-unicode-properties
76     </pre>
77     to the <b>configure</b> command. This implies UTF-8 support, even if you have
78     not explicitly requested it.
79     </P>
80     <P>
81     Including Unicode property support adds around 90K of tables to the PCRE
82     library, approximately doubling its size. Only the general category properties
83     such as <i>Lu</i> and <i>Nd</i> are supported. Details are given in the
84     <a href="pcrepattern.html"><b>pcrepattern</b></a>
85     documentation.
86     </P>
87 nigel 83 <br><a name="SEC5" href="#TOC1">CODE VALUE OF NEWLINE</a><br>
88 nigel 75 <P>
89 nigel 91 By default, PCRE interprets character 10 (linefeed, LF) as indicating the end
90     of a line. This is the normal newline character on Unix-like systems. You can
91     compile PCRE to use character 13 (carriage return, CR) instead, by adding
92 nigel 63 <pre>
93     --enable-newline-is-cr
94 nigel 75 </pre>
95 nigel 91 to the <b>configure</b> command. There is also a --enable-newline-is-lf option,
96     which explicitly specifies linefeed as the newline character.
97     <br>
98     <br>
99     Alternatively, you can specify that line endings are to be indicated by the two
100     character sequence CRLF. If you want this, add
101     <pre>
102     --enable-newline-is-crlf
103     </pre>
104 nigel 93 to the <b>configure</b> command. There is a fourth option, specified by
105     <pre>
106     --enable-newline-is-any
107     </pre>
108     which causes PCRE to recognize any Unicode newline sequence.
109 nigel 63 </P>
110 nigel 93 <P>
111     Whatever line ending convention is selected when PCRE is built can be
112     overridden when the library functions are called. At build time it is
113     conventional to use the standard for your operating system.
114     </P>
115 nigel 83 <br><a name="SEC6" href="#TOC1">BUILDING SHARED AND STATIC LIBRARIES</a><br>
116 nigel 63 <P>
117     The PCRE building process uses <b>libtool</b> to build both shared and static
118     Unix libraries by default. You can suppress one of these by adding one of
119     <pre>
120     --disable-shared
121     --disable-static
122 nigel 75 </pre>
123 nigel 63 to the <b>configure</b> command, as required.
124     </P>
125 nigel 83 <br><a name="SEC7" href="#TOC1">POSIX MALLOC USAGE</a><br>
126 nigel 63 <P>
127 nigel 75 When PCRE is called through the POSIX interface (see the
128     <a href="pcreposix.html"><b>pcreposix</b></a>
129 nigel 63 documentation), additional working storage is required for holding the pointers
130 nigel 75 to capturing substrings, because PCRE requires three integers per substring,
131 nigel 63 whereas the POSIX interface provides only two. If the number of expected
132     substrings is small, the wrapper function uses space on the stack, because this
133     is faster than using <b>malloc()</b> for each call. The default threshold above
134     which the stack is no longer used is 10; it can be changed by adding a setting
135     such as
136     <pre>
137     --with-posix-malloc-threshold=20
138 nigel 75 </pre>
139 nigel 63 to the <b>configure</b> command.
140     </P>
141 nigel 91 <br><a name="SEC8" href="#TOC1">HANDLING VERY LARGE PATTERNS</a><br>
142 nigel 63 <P>
143     Within a compiled pattern, offset values are used to point from one part to
144     another (for example, from an opening parenthesis to an alternation
145 nigel 75 metacharacter). By default, two-byte values are used for these offsets, leading
146 nigel 63 to a maximum size for a compiled pattern of around 64K. This is sufficient to
147     handle all but the most gigantic patterns. Nevertheless, some people do want to
148     process enormous patterns, so it is possible to compile PCRE to use three-byte
149     or four-byte offsets by adding a setting such as
150     <pre>
151     --with-link-size=3
152 nigel 75 </pre>
153 nigel 63 to the <b>configure</b> command. The value given must be 2, 3, or 4. Using
154     longer offsets slows down the operation of PCRE because it has to load
155     additional bytes when handling them.
156     </P>
157     <P>
158     If you build PCRE with an increased link size, test 2 (and test 5 if you are
159     using UTF-8) will fail. Part of the output of these tests is a representation
160     of the compiled pattern, and this changes with the link size.
161     </P>
162 nigel 91 <br><a name="SEC9" href="#TOC1">AVOIDING EXCESSIVE STACK USAGE</a><br>
163 nigel 63 <P>
164 nigel 77 When matching with the <b>pcre_exec()</b> function, PCRE implements backtracking
165     by making recursive calls to an internal function called <b>match()</b>. In
166     environments where the size of the stack is limited, this can severely limit
167     PCRE's operation. (The Unix environment does not usually suffer from this
168 nigel 91 problem, but it may sometimes be necessary to increase the maximum stack size.
169     There is a discussion in the
170     <a href="pcrestack.html"><b>pcrestack</b></a>
171     documentation.) An alternative approach to recursion that uses memory from the
172     heap to remember data, instead of using recursive function calls, has been
173     implemented to work round the problem of limited stack size. If you want to
174     build a version of PCRE that works this way, add
175 nigel 73 <pre>
176     --disable-stack-for-recursion
177 nigel 75 </pre>
178 nigel 73 to the <b>configure</b> command. With this configuration, PCRE will use the
179     <b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> variables to call memory
180     management functions. Separate functions are provided because the usage is very
181     predictable: the block sizes requested are always the same, and the blocks are
182     always freed in reverse order. A calling program might be able to implement
183     optimized functions that perform better than the standard <b>malloc()</b> and
184     <b>free()</b> functions. PCRE runs noticeably more slowly when built in this
185 nigel 77 way. This option affects only the <b>pcre_exec()</b> function; it is not
186     relevant for the the <b>pcre_dfa_exec()</b> function.
187 nigel 73 </P>
188 nigel 91 <br><a name="SEC10" href="#TOC1">LIMITING PCRE RESOURCE USAGE</a><br>
189     <P>
190     Internally, PCRE has a function called <b>match()</b>, which it calls repeatedly
191     (sometimes recursively) when matching a pattern with the <b>pcre_exec()</b>
192     function. By controlling the maximum number of times this function may be
193     called during a single matching operation, a limit can be placed on the
194     resources used by a single call to <b>pcre_exec()</b>. The limit can be changed
195     at run time, as described in the
196     <a href="pcreapi.html"><b>pcreapi</b></a>
197     documentation. The default is 10 million, but this can be changed by adding a
198     setting such as
199     <pre>
200     --with-match-limit=500000
201     </pre>
202     to the <b>configure</b> command. This setting has no effect on the
203     <b>pcre_dfa_exec()</b> matching function.
204     </P>
205     <P>
206     In some environments it is desirable to limit the depth of recursive calls of
207     <b>match()</b> more strictly than the total number of calls, in order to
208     restrict the maximum amount of stack (or heap, if --disable-stack-for-recursion
209     is specified) that is used. A second limit controls this; it defaults to the
210     value that is set for --with-match-limit, which imposes no additional
211     constraints. However, you can set a lower limit by adding, for example,
212     <pre>
213     --with-match-limit-recursion=10000
214     </pre>
215     to the <b>configure</b> command. This value can also be overridden at run time.
216     </P>
217 nigel 83 <br><a name="SEC11" href="#TOC1">USING EBCDIC CODE</a><br>
218 nigel 73 <P>
219     PCRE assumes by default that it will run in an environment where the character
220 nigel 75 code is ASCII (or Unicode, which is a superset of ASCII). PCRE can, however, be
221 nigel 73 compiled to run in an EBCDIC environment by adding
222     <pre>
223     --enable-ebcdic
224 nigel 75 </pre>
225 nigel 73 to the <b>configure</b> command.
226     </P>
227 nigel 93 <br><a name="SEC12" href="#TOC1">SEE ALSO</a><br>
228 nigel 73 <P>
229 nigel 93 <b>pcreapi</b>(3), <b>pcre_config</b>(3).
230     </P>
231     <P>
232     Last updated: 30 November 2006
233 nigel 63 <br>
234 nigel 91 Copyright &copy; 1997-2006 University of Cambridge.
235 nigel 75 <p>
236     Return to the <a href="index.html">PCRE index page</a>.
237     </p>

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