/[pcre]/code/trunk/doc/pcrebuild.3
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revision 79 by nigel, Sat Feb 24 21:40:52 2007 UTC revision 128 by ph10, Tue Mar 20 11:46:50 2007 UTC
# Line 13  obtained by running Line 13  obtained by running
13  .sp  .sp
14    ./configure --help    ./configure --help
15  .sp  .sp
16  The following sections describe certain options whose names begin with --enable  The following sections include descriptions of options whose names begin with
17  or --disable. These settings specify changes to the defaults for the  --enable or --disable. These settings specify changes to the defaults for the
18  \fBconfigure\fP command. Because of the way that \fBconfigure\fP works,  \fBconfigure\fP command. Because of the way that \fBconfigure\fP works,
19  --enable and --disable always come in pairs, so the complementary option always  --enable and --disable always come in pairs, so the complementary option always
20  exists as well, but as it specifies the default, it is not described.  exists as well, but as it specifies the default, it is not described.
21  .  .
22    .SH "C++ SUPPORT"
23    .rs
24    .sp
25    By default, the \fBconfigure\fP script will search for a C++ compiler and C++
26    header files. If it finds them, it automatically builds the C++ wrapper library
27    for PCRE. You can disable this by adding
28    .sp
29      --disable-cpp
30    .sp
31    to the \fBconfigure\fP command.
32    .
33  .SH "UTF-8 SUPPORT"  .SH "UTF-8 SUPPORT"
34  .rs  .rs
35  .sp  .sp
# Line 45  character properties, you must add Line 56  character properties, you must add
56  to the \fBconfigure\fP command. This implies UTF-8 support, even if you have  to the \fBconfigure\fP command. This implies UTF-8 support, even if you have
57  not explicitly requested it.  not explicitly requested it.
58  .P  .P
59  Including Unicode property support adds around 90K of tables to the PCRE  Including Unicode property support adds around 30K of tables to the PCRE
60  library, approximately doubling its size. Only the general category properties  library. Only the general category properties such as \fILu\fP and \fINd\fP are
61  such as \fILu\fP and \fINd\fP are supported. Details are given in the  supported. Details are given in the
62  .\" HREF  .\" HREF
63  \fBpcrepattern\fP  \fBpcrepattern\fP
64  .\"  .\"
# Line 56  documentation. Line 67  documentation.
67  .SH "CODE VALUE OF NEWLINE"  .SH "CODE VALUE OF NEWLINE"
68  .rs  .rs
69  .sp  .sp
70  By default, PCRE treats character 10 (linefeed) as the newline character. This  By default, PCRE interprets character 10 (linefeed, LF) as indicating the end
71  is the normal newline character on Unix-like systems. You can compile PCRE to  of a line. This is the normal newline character on Unix-like systems. You can
72  use character 13 (carriage return) instead by adding  compile PCRE to use character 13 (carriage return, CR) instead, by adding
73  .sp  .sp
74    --enable-newline-is-cr    --enable-newline-is-cr
75  .sp  .sp
76  to the \fBconfigure\fP command. For completeness there is also a  to the \fBconfigure\fP command. There is also a --enable-newline-is-lf option,
77  --enable-newline-is-lf option, which explicitly specifies linefeed as the  which explicitly specifies linefeed as the newline character.
78  newline character.  .sp
79    Alternatively, you can specify that line endings are to be indicated by the two
80    character sequence CRLF. If you want this, add
81    .sp
82      --enable-newline-is-crlf
83    .sp
84    to the \fBconfigure\fP command. There is a fourth option, specified by
85    .sp
86      --enable-newline-is-any
87    .sp
88    which causes PCRE to recognize any Unicode newline sequence.
89    .P
90    Whatever line ending convention is selected when PCRE is built can be
91    overridden when the library functions are called. At build time it is
92    conventional to use the standard for your operating system.
93  .  .
94  .SH "BUILDING SHARED AND STATIC LIBRARIES"  .SH "BUILDING SHARED AND STATIC LIBRARIES"
95  .rs  .rs
# Line 96  such as Line 121  such as
121  .sp  .sp
122  to the \fBconfigure\fP command.  to the \fBconfigure\fP command.
123  .  .
 .SH "LIMITING PCRE RESOURCE USAGE"  
 .rs  
 .sp  
 Internally, PCRE has a function called \fBmatch()\fP, which it calls repeatedly  
 (possibly recursively) when matching a pattern with the \fBpcre_exec()\fP  
 function. By controlling the maximum number of times this function may be  
 called during a single matching operation, a limit can be placed on the  
 resources used by a single call to \fBpcre_exec()\fP. The limit can be changed  
 at run time, as described in the  
 .\" HREF  
 \fBpcreapi\fP  
 .\"  
 documentation. The default is 10 million, but this can be changed by adding a  
 setting such as  
 .sp  
   --with-match-limit=500000  
 .sp  
 to the \fBconfigure\fP command. This setting has no effect on the  
 \fBpcre_dfa_exec()\fP matching function.  
 .  
124  .SH "HANDLING VERY LARGE PATTERNS"  .SH "HANDLING VERY LARGE PATTERNS"
125  .rs  .rs
126  .sp  .sp
# Line 132  or four-byte offsets by adding a setting Line 137  or four-byte offsets by adding a setting
137  to the \fBconfigure\fP command. The value given must be 2, 3, or 4. Using  to the \fBconfigure\fP command. The value given must be 2, 3, or 4. Using
138  longer offsets slows down the operation of PCRE because it has to load  longer offsets slows down the operation of PCRE because it has to load
139  additional bytes when handling them.  additional bytes when handling them.
 .P  
 If you build PCRE with an increased link size, test 2 (and test 5 if you are  
 using UTF-8) will fail. Part of the output of these tests is a representation  
 of the compiled pattern, and this changes with the link size.  
140  .  .
141  .SH "AVOIDING EXCESSIVE STACK USAGE"  .SH "AVOIDING EXCESSIVE STACK USAGE"
142  .rs  .rs
# Line 144  When matching with the \fBpcre_exec()\fP Line 145  When matching with the \fBpcre_exec()\fP
145  by making recursive calls to an internal function called \fBmatch()\fP. In  by making recursive calls to an internal function called \fBmatch()\fP. In
146  environments where the size of the stack is limited, this can severely limit  environments where the size of the stack is limited, this can severely limit
147  PCRE's operation. (The Unix environment does not usually suffer from this  PCRE's operation. (The Unix environment does not usually suffer from this
148  problem.) An alternative approach that uses memory from the heap to remember  problem, but it may sometimes be necessary to increase the maximum stack size.
149  data, instead of using recursive function calls, has been implemented to work  There is a discussion in the
150  round this problem. If you want to build a version of PCRE that works this way,  .\" HREF
151  add  \fBpcrestack\fP
152    .\"
153    documentation.) An alternative approach to recursion that uses memory from the
154    heap to remember data, instead of using recursive function calls, has been
155    implemented to work round the problem of limited stack size. If you want to
156    build a version of PCRE that works this way, add
157  .sp  .sp
158    --disable-stack-for-recursion    --disable-stack-for-recursion
159  .sp  .sp
# Line 161  optimized functions that perform better Line 167  optimized functions that perform better
167  way. This option affects only the \fBpcre_exec()\fP function; it is not  way. This option affects only the \fBpcre_exec()\fP function; it is not
168  relevant for the the \fBpcre_dfa_exec()\fP function.  relevant for the the \fBpcre_dfa_exec()\fP function.
169  .  .
170    .SH "LIMITING PCRE RESOURCE USAGE"
171    .rs
172    .sp
173    Internally, PCRE has a function called \fBmatch()\fP, which it calls repeatedly
174    (sometimes recursively) when matching a pattern with the \fBpcre_exec()\fP
175    function. By controlling the maximum number of times this function may be
176    called during a single matching operation, a limit can be placed on the
177    resources used by a single call to \fBpcre_exec()\fP. The limit can be changed
178    at run time, as described in the
179    .\" HREF
180    \fBpcreapi\fP
181    .\"
182    documentation. The default is 10 million, but this can be changed by adding a
183    setting such as
184    .sp
185      --with-match-limit=500000
186    .sp
187    to the \fBconfigure\fP command. This setting has no effect on the
188    \fBpcre_dfa_exec()\fP matching function.
189    .P
190    In some environments it is desirable to limit the depth of recursive calls of
191    \fBmatch()\fP more strictly than the total number of calls, in order to
192    restrict the maximum amount of stack (or heap, if --disable-stack-for-recursion
193    is specified) that is used. A second limit controls this; it defaults to the
194    value that is set for --with-match-limit, which imposes no additional
195    constraints. However, you can set a lower limit by adding, for example,
196    .sp
197      --with-match-limit-recursion=10000
198    .sp
199    to the \fBconfigure\fP command. This value can also be overridden at run time.
200    .
201    .SH "CREATING CHARACTER TABLES AT BUILD TIME"
202    .rs
203    .sp
204    PCRE uses fixed tables for processing characters whose code values are less
205    than 256. By default, PCRE is built with a set of tables that are distributed
206    in the file \fIpcre_chartables.c.dist\fP. These tables are for ASCII codes
207    only. If you add
208    .sp
209      --enable-rebuild-chartables
210    .sp
211    to the \fBconfigure\fP command, the distributed tables are no longer used.
212    Instead, a program called \fBdftables\fP is compiled and run. This outputs the
213    source for new set of tables, created in the default locale of your C runtime
214    system. (This method of replacing the tables does not work if you are cross
215    compiling, because \fBdftables\fP is run on the local host. If you need to
216    create alternative tables when cross compiling, you will have to do so "by
217    hand".)
218    .
219  .SH "USING EBCDIC CODE"  .SH "USING EBCDIC CODE"
220  .rs  .rs
221  .sp  .sp
# Line 170  compiled to run in an EBCDIC environment Line 225  compiled to run in an EBCDIC environment
225  .sp  .sp
226    --enable-ebcdic    --enable-ebcdic
227  .sp  .sp
228  to the \fBconfigure\fP command.  to the \fBconfigure\fP command. This setting implies
229  .P  --enable-rebuild-chartables.
230  .in 0  .
231  Last updated: 28 February 2005  .
232  .br  .SH "SEE ALSO"
233  Copyright (c) 1997-2005 University of Cambridge.  .rs
234    .sp
235    \fBpcreapi\fP(3), \fBpcre_config\fP(3).
236    .
237    .
238    .SH AUTHOR
239    .rs
240    .sp
241    .nf
242    Philip Hazel
243    University Computing Service
244    Cambridge CB2 3QH, England.
245    .fi
246    .
247    .
248    .SH REVISION
249    .rs
250    .sp
251    .nf
252    Last updated: 20 March 2007
253    Copyright (c) 1997-2007 University of Cambridge.
254    .fi

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