--- code/trunk/doc/html/pcrebuild.html 2007/02/24 21:40:30 73 +++ code/trunk/doc/html/pcrebuild.html 2007/02/24 21:40:37 75 @@ -3,35 +3,38 @@ pcrebuild specification -This HTML document has been generated automatically from the original man page. -If there is any nonsense in it, please consult the man page, in case the -conversion went wrong.
+

pcrebuild man page

+

+Return to the PCRE index page. +

+

+This page is part of the PCRE HTML documentation. It was generated automatically +from the original man page. If there is any nonsense in it, please consult the +man page, in case the conversion went wrong. +


PCRE BUILD-TIME OPTIONS

This document describes the optional features of PCRE that can be selected when the library is compiled. They are all selected, or deselected, by providing -options to the configure script which is run before the make +options to the configure script that is run before the make command. The complete list of options for configure (which includes the standard ones such as the selection of the installation directory) can be obtained by running -

-

   ./configure --help
-
-

-

+ The following sections describe certain options whose names begin with --enable or --disable. These settings specify changes to the defaults for the configure command. Because of the way that configure works, @@ -41,100 +44,99 @@
UTF-8 SUPPORT

To build PCRE with support for UTF-8 character strings, add -

-

   --enable-utf8
-
-

-

+ to the configure command. Of itself, this does not make PCRE treat strings as UTF-8. As well as compiling PCRE with this option, you also have have to set the PCRE_UTF8 option when you call the pcre_compile() function.

-
CODE VALUE OF NEWLINE
+
UNICODE CHARACTER PROPERTY SUPPORT
+

+UTF-8 support allows PCRE to process character values greater than 255 in the +strings that it handles. On its own, however, it does not provide any +facilities for accessing the properties of such characters. If you want to be +able to use the pattern escapes \P, \p, and \X, which refer to Unicode +character properties, you must add +

+  --enable-unicode-properties
+
+to the configure command. This implies UTF-8 support, even if you have +not explicitly requested it. +

+

+Including Unicode property support adds around 90K of tables to the PCRE +library, approximately doubling its size. Only the general category properties +such as Lu and Nd are supported. Details are given in the +pcrepattern +documentation. +

+
CODE VALUE OF NEWLINE

By default, PCRE treats character 10 (linefeed) as the newline character. This is the normal newline character on Unix-like systems. You can compile PCRE to use character 13 (carriage return) instead by adding -

-

   --enable-newline-is-cr
-
-

-

+ to the configure command. For completeness there is also a --enable-newline-is-lf option, which explicitly specifies linefeed as the newline character.

-
BUILDING SHARED AND STATIC LIBRARIES
+
BUILDING SHARED AND STATIC LIBRARIES

The PCRE building process uses libtool to build both shared and static Unix libraries by default. You can suppress one of these by adding one of -

-

   --disable-shared
   --disable-static
-
-

-

+ to the configure command, as required.

-
POSIX MALLOC USAGE
+
POSIX MALLOC USAGE

-When PCRE is called through the POSIX interface (see the pcreposix +When PCRE is called through the POSIX interface (see the +pcreposix documentation), additional working storage is required for holding the pointers -to capturing substrings because PCRE requires three integers per substring, +to capturing substrings, because PCRE requires three integers per substring, whereas the POSIX interface provides only two. If the number of expected substrings is small, the wrapper function uses space on the stack, because this is faster than using malloc() for each call. The default threshold above which the stack is no longer used is 10; it can be changed by adding a setting such as -

-

   --with-posix-malloc-threshold=20
-
-

-

+ to the configure command.

-
LIMITING PCRE RESOURCE USAGE
-

-Internally, PCRE has a function called match() which it calls repeatedly -(possibly recursively) when performing a matching operation. By limiting the -number of times this function may be called, a limit can be placed on the -resources used by a single call to pcre_exec(). The limit can be changed -at run time, as described in the pcreapi documentation. The default is 10 -million, but this can be changed by adding a setting such as -

+
LIMITING PCRE RESOURCE USAGE

+Internally, PCRE has a function called match(), which it calls repeatedly +(possibly recursively) when matching a pattern. 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 +pcre_exec(). The limit can be changed at run time, as described in the +pcreapi +documentation. The default is 10 million, but this can be changed by adding a +setting such as

   --with-match-limit=500000
-
-

-

+ to the configure command.

-
HANDLING VERY LARGE PATTERNS
+
HANDLING VERY LARGE PATTERNS

Within a compiled pattern, offset values are used to point from one part to another (for example, from an opening parenthesis to an alternation -metacharacter). By default two-byte values are used for these offsets, leading +metacharacter). By default, two-byte values are used for these offsets, leading to a maximum size for a compiled pattern of around 64K. This is sufficient to handle all but the most gigantic patterns. Nevertheless, some people do want to process enormous patterns, so it is possible to compile PCRE to use three-byte or four-byte offsets by adding a setting such as -

-

   --with-link-size=3
-
-

-

+ to the configure command. The value given must be 2, 3, or 4. Using longer offsets slows down the operation of PCRE because it has to load additional bytes when handling them. @@ -144,7 +146,7 @@ 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.

-
AVOIDING EXCESSIVE STACK USAGE
+
AVOIDING EXCESSIVE STACK USAGE

PCRE implements backtracking while matching by making recursive calls to an internal function called match(). In environments where the size of the @@ -153,13 +155,9 @@ that uses memory from the heap to remember data, instead of using recursive function calls, has been implemented to work round this problem. If you want to build a version of PCRE that works this way, add -

-

   --disable-stack-for-recursion
-
-

-

+ to the configure command. With this configuration, PCRE will use the pcre_stack_malloc and pcre_stack_free variables to call memory management functions. Separate functions are provided because the usage is very @@ -169,21 +167,20 @@ free() functions. PCRE runs noticeably more slowly when built in this way.

-
USING EBCDIC CODE
+
USING EBCDIC CODE

PCRE assumes by default that it will run in an environment where the character -code is ASCII (or UTF-8, 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 compiled to run in an EBCDIC environment by adding -

-

   --enable-ebcdic
-
-

-

+ to the configure command.

-Last updated: 09 December 2003 +Last updated: 09 September 2004
-Copyright © 1997-2003 University of Cambridge. +Copyright © 1997-2004 University of Cambridge. +

+Return to the PCRE index page. +