pcrebuild specification

From 582b500cd996c96054615870fd13d6ab0ea77428 Mon Sep 17 00:00:00 2001 From: Jay Berkenbilt Date: Sat, 10 Oct 2009 15:10:05 +0000 Subject: start integrating windows port git-svn-id: svn+q:///qpdf/trunk@757 71b93d88-0707-0410-a8cf-f5a4172ac649 --- external-libs/pcre/doc/html/pcrebuild.html | 189 +++++++++++++++++++++++++++++ 1 file changed, 189 insertions(+) create mode 100644 external-libs/pcre/doc/html/pcrebuild.html (limited to 'external-libs/pcre/doc/html/pcrebuild.html') diff --git a/external-libs/pcre/doc/html/pcrebuild.html b/external-libs/pcre/doc/html/pcrebuild.html new file mode 100644 index 00000000..c70f8221 --- /dev/null +++ b/external-libs/pcre/doc/html/pcrebuild.html @@ -0,0 +1,189 @@ + + +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.
+

PCRE BUILD-TIME OPTIONS +
UTF-8 SUPPORT +
CODE VALUE OF NEWLINE +
BUILDING SHARED AND STATIC LIBRARIES +
POSIX MALLOC USAGE +
LIMITING PCRE RESOURCE USAGE +
HANDLING VERY LARGE PATTERNS +
AVOIDING EXCESSIVE STACK USAGE +
USING EBCDIC CODE +

+
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 +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, +--enable and --disable always come in pairs, so the complementary option always +exists as well, but as it specifies the default, it is not described. +

+
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
+

+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
+

+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
+

+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, +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 +

+  --with-match-limit=500000
+

+to the configure command. +

+
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 +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. +

+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. +

+
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 +stack is limited, this can severely limit PCRE's operation. (The Unix +environment does not usually suffer from this problem.) An alternative approach +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 +predictable: the block sizes requested are always the same, and the blocks are +always freed in reverse order. A calling program might be able to implement +optimized functions that perform better than the standard malloc() and +free() functions. PCRE runs noticeably more slowly when built in this +way. +

+
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 +compiled to run in an EBCDIC environment by adding +

+  --enable-ebcdic
+

+to the configure command. +