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revision 77 by nigel, Sat Feb 24 21:40:45 2007 UTC revision 91 by nigel, Sat Feb 24 21:41:34 2007 UTC
# Line 14  man page, in case the conversion went wr Line 14  man page, in case the conversion went wr
14  <br>  <br>
15  <ul>  <ul>
16  <li><a name="TOC1" href="#SEC1">PCRE BUILD-TIME OPTIONS</a>  <li><a name="TOC1" href="#SEC1">PCRE BUILD-TIME OPTIONS</a>
17  <li><a name="TOC2" href="#SEC2">UTF-8 SUPPORT</a>  <li><a name="TOC2" href="#SEC2">C++ SUPPORT</a>
18  <li><a name="TOC3" href="#SEC3">UNICODE CHARACTER PROPERTY SUPPORT</a>  <li><a name="TOC3" href="#SEC3">UTF-8 SUPPORT</a>
19  <li><a name="TOC4" href="#SEC4">CODE VALUE OF NEWLINE</a>  <li><a name="TOC4" href="#SEC4">UNICODE CHARACTER PROPERTY SUPPORT</a>
20  <li><a name="TOC5" href="#SEC5">BUILDING SHARED AND STATIC LIBRARIES</a>  <li><a name="TOC5" href="#SEC5">CODE VALUE OF NEWLINE</a>
21  <li><a name="TOC6" href="#SEC6">POSIX MALLOC USAGE</a>  <li><a name="TOC6" href="#SEC6">BUILDING SHARED AND STATIC LIBRARIES</a>
22  <li><a name="TOC7" href="#SEC7">LIMITING PCRE RESOURCE USAGE</a>  <li><a name="TOC7" href="#SEC7">POSIX MALLOC USAGE</a>
23  <li><a name="TOC8" href="#SEC8">HANDLING VERY LARGE PATTERNS</a>  <li><a name="TOC8" href="#SEC8">HANDLING VERY LARGE PATTERNS</a>
24  <li><a name="TOC9" href="#SEC9">AVOIDING EXCESSIVE STACK USAGE</a>  <li><a name="TOC9" href="#SEC9">AVOIDING EXCESSIVE STACK USAGE</a>
25  <li><a name="TOC10" href="#SEC10">USING EBCDIC CODE</a>  <li><a name="TOC10" href="#SEC10">LIMITING PCRE RESOURCE USAGE</a>
26    <li><a name="TOC11" href="#SEC11">USING EBCDIC CODE</a>
27  </ul>  </ul>
28  <br><a name="SEC1" href="#TOC1">PCRE BUILD-TIME OPTIONS</a><br>  <br><a name="SEC1" href="#TOC1">PCRE BUILD-TIME OPTIONS</a><br>
29  <P>  <P>
# Line 41  or --disable. These settings specify cha Line 42  or --disable. These settings specify cha
42  --enable and --disable always come in pairs, so the complementary option always  --enable and --disable always come in pairs, so the complementary option always
43  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.
44  </P>  </P>
45  <br><a name="SEC2" href="#TOC1">UTF-8 SUPPORT</a><br>  <br><a name="SEC2" href="#TOC1">C++ SUPPORT</a><br>
46    <P>
47    By default, the <b>configure</b> script will search for a C++ compiler and C++
48    header files. If it finds them, it automatically builds the C++ wrapper library
49    for PCRE. You can disable this by adding
50    <pre>
51      --disable-cpp
52    </pre>
53    to the <b>configure</b> command.
54    </P>
55    <br><a name="SEC3" href="#TOC1">UTF-8 SUPPORT</a><br>
56  <P>  <P>
57  To build PCRE with support for UTF-8 character strings, add  To build PCRE with support for UTF-8 character strings, add
58  <pre>  <pre>
# Line 52  strings as UTF-8. As well as compiling P Line 63  strings as UTF-8. As well as compiling P
63  have to set the PCRE_UTF8 option when you call the <b>pcre_compile()</b>  have to set the PCRE_UTF8 option when you call the <b>pcre_compile()</b>
64  function.  function.
65  </P>  </P>
66  <br><a name="SEC3" href="#TOC1">UNICODE CHARACTER PROPERTY SUPPORT</a><br>  <br><a name="SEC4" href="#TOC1">UNICODE CHARACTER PROPERTY SUPPORT</a><br>
67  <P>  <P>
68  UTF-8 support allows PCRE to process character values greater than 255 in the  UTF-8 support allows PCRE to process character values greater than 255 in the
69  strings that it handles. On its own, however, it does not provide any  strings that it handles. On its own, however, it does not provide any
# Line 72  such as <i>Lu</i> and <i>Nd</i> are supp Line 83  such as <i>Lu</i> and <i>Nd</i> are supp
83  <a href="pcrepattern.html"><b>pcrepattern</b></a>  <a href="pcrepattern.html"><b>pcrepattern</b></a>
84  documentation.  documentation.
85  </P>  </P>
86  <br><a name="SEC4" href="#TOC1">CODE VALUE OF NEWLINE</a><br>  <br><a name="SEC5" href="#TOC1">CODE VALUE OF NEWLINE</a><br>
87  <P>  <P>
88  By default, PCRE treats character 10 (linefeed) as the newline character. This  By default, PCRE interprets character 10 (linefeed, LF) as indicating the end
89  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
90  use character 13 (carriage return) instead by adding  compile PCRE to use character 13 (carriage return, CR) instead, by adding
91  <pre>  <pre>
92    --enable-newline-is-cr    --enable-newline-is-cr
93  </pre>  </pre>
94  to the <b>configure</b> command. For completeness there is also a  to the <b>configure</b> command. There is also a --enable-newline-is-lf option,
95  --enable-newline-is-lf option, which explicitly specifies linefeed as the  which explicitly specifies linefeed as the newline character.
96  newline character.  <br>
97    <br>
98    Alternatively, you can specify that line endings are to be indicated by the two
99    character sequence CRLF. If you want this, add
100    <pre>
101      --enable-newline-is-crlf
102    </pre>
103    to the <b>configure</b> command. Whatever line ending convention is selected
104    when PCRE is built can be overridden when the library functions are called. At
105    build time it is conventional to use the standard for your operating system.
106  </P>  </P>
107  <br><a name="SEC5" href="#TOC1">BUILDING SHARED AND STATIC LIBRARIES</a><br>  <br><a name="SEC6" href="#TOC1">BUILDING SHARED AND STATIC LIBRARIES</a><br>
108  <P>  <P>
109  The PCRE building process uses <b>libtool</b> to build both shared and static  The PCRE building process uses <b>libtool</b> to build both shared and static
110  Unix libraries by default. You can suppress one of these by adding one of  Unix libraries by default. You can suppress one of these by adding one of
# Line 94  Unix libraries by default. You can suppr Line 114  Unix libraries by default. You can suppr
114  </pre>  </pre>
115  to the <b>configure</b> command, as required.  to the <b>configure</b> command, as required.
116  </P>  </P>
117  <br><a name="SEC6" href="#TOC1">POSIX MALLOC USAGE</a><br>  <br><a name="SEC7" href="#TOC1">POSIX MALLOC USAGE</a><br>
118  <P>  <P>
119  When PCRE is called through the POSIX interface (see the  When PCRE is called through the POSIX interface (see the
120  <a href="pcreposix.html"><b>pcreposix</b></a>  <a href="pcreposix.html"><b>pcreposix</b></a>
# Line 110  such as Line 130  such as
130  </pre>  </pre>
131  to the <b>configure</b> command.  to the <b>configure</b> command.
132  </P>  </P>
 <br><a name="SEC7" href="#TOC1">LIMITING PCRE RESOURCE USAGE</a><br>  
 <P>  
 Internally, PCRE has a function called <b>match()</b>, which it calls repeatedly  
 (possibly recursively) when matching a pattern with the <b>pcre_exec()</b>  
 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 <b>pcre_exec()</b>. The limit can be changed  
 at run time, as described in the  
 <a href="pcreapi.html"><b>pcreapi</b></a>  
 documentation. The default is 10 million, but this can be changed by adding a  
 setting such as  
 <pre>  
   --with-match-limit=500000  
 </pre>  
 to the <b>configure</b> command. This setting has no effect on the  
 <b>pcre_dfa_exec()</b> matching function.  
 </P>  
133  <br><a name="SEC8" href="#TOC1">HANDLING VERY LARGE PATTERNS</a><br>  <br><a name="SEC8" href="#TOC1">HANDLING VERY LARGE PATTERNS</a><br>
134  <P>  <P>
135  Within a compiled pattern, offset values are used to point from one part to  Within a compiled pattern, offset values are used to point from one part to
# Line 154  When matching with the <b>pcre_exec()</b Line 157  When matching with the <b>pcre_exec()</b
157  by making recursive calls to an internal function called <b>match()</b>. In  by making recursive calls to an internal function called <b>match()</b>. In
158  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
159  PCRE's operation. (The Unix environment does not usually suffer from this  PCRE's operation. (The Unix environment does not usually suffer from this
160  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.
161  data, instead of using recursive function calls, has been implemented to work  There is a discussion in the
162  round this problem. If you want to build a version of PCRE that works this way,  <a href="pcrestack.html"><b>pcrestack</b></a>
163  add  documentation.) An alternative approach to recursion that uses memory from the
164    heap to remember data, instead of using recursive function calls, has been
165    implemented to work round the problem of limited stack size. If you want to
166    build a version of PCRE that works this way, add
167  <pre>  <pre>
168    --disable-stack-for-recursion    --disable-stack-for-recursion
169  </pre>  </pre>
# Line 171  optimized functions that perform better Line 177  optimized functions that perform better
177  way. This option affects only the <b>pcre_exec()</b> function; it is not  way. This option affects only the <b>pcre_exec()</b> function; it is not
178  relevant for the the <b>pcre_dfa_exec()</b> function.  relevant for the the <b>pcre_dfa_exec()</b> function.
179  </P>  </P>
180  <br><a name="SEC10" href="#TOC1">USING EBCDIC CODE</a><br>  <br><a name="SEC10" href="#TOC1">LIMITING PCRE RESOURCE USAGE</a><br>
181    <P>
182    Internally, PCRE has a function called <b>match()</b>, which it calls repeatedly
183    (sometimes recursively) when matching a pattern with the <b>pcre_exec()</b>
184    function. By controlling the maximum number of times this function may be
185    called during a single matching operation, a limit can be placed on the
186    resources used by a single call to <b>pcre_exec()</b>. The limit can be changed
187    at run time, as described in the
188    <a href="pcreapi.html"><b>pcreapi</b></a>
189    documentation. The default is 10 million, but this can be changed by adding a
190    setting such as
191    <pre>
192      --with-match-limit=500000
193    </pre>
194    to the <b>configure</b> command. This setting has no effect on the
195    <b>pcre_dfa_exec()</b> matching function.
196    </P>
197    <P>
198    In some environments it is desirable to limit the depth of recursive calls of
199    <b>match()</b> more strictly than the total number of calls, in order to
200    restrict the maximum amount of stack (or heap, if --disable-stack-for-recursion
201    is specified) that is used. A second limit controls this; it defaults to the
202    value that is set for --with-match-limit, which imposes no additional
203    constraints. However, you can set a lower limit by adding, for example,
204    <pre>
205      --with-match-limit-recursion=10000
206    </pre>
207    to the <b>configure</b> command. This value can also be overridden at run time.
208    </P>
209    <br><a name="SEC11" href="#TOC1">USING EBCDIC CODE</a><br>
210  <P>  <P>
211  PCRE assumes by default that it will run in an environment where the character  PCRE assumes by default that it will run in an environment where the character
212  code is ASCII (or Unicode, which is a superset of ASCII). PCRE can, however, be  code is ASCII (or Unicode, which is a superset of ASCII). PCRE can, however, be
# Line 182  compiled to run in an EBCDIC environment Line 217  compiled to run in an EBCDIC environment
217  to the <b>configure</b> command.  to the <b>configure</b> command.
218  </P>  </P>
219  <P>  <P>
220  Last updated: 28 February 2005  Last updated: 06 June 2006
221  <br>  <br>
222  Copyright &copy; 1997-2005 University of Cambridge.  Copyright &copy; 1997-2006 University of Cambridge.
223  <p>  <p>
224  Return to the <a href="index.html">PCRE index page</a>.  Return to the <a href="index.html">PCRE index page</a>.
225  </p>  </p>

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