diff options
| author | ph10 <ph10@6239d852-aaf2-0410-a92c-79f79f948069> | 2014-09-29 16:45:37 +0000 |
|---|---|---|
| committer | ph10 <ph10@6239d852-aaf2-0410-a92c-79f79f948069> | 2014-09-29 16:45:37 +0000 |
| commit | c90bcfa7556b71fb9fab19a07cbc42f175021845 (patch) | |
| tree | 3593d47b1a9bd49df9abcc1da84b3138611e113d /doc/html/pcre2limits.html | |
| parent | f30ff3deb77413a8059cfe06dc6db30047e8dcde (diff) | |
| download | pcre2-c90bcfa7556b71fb9fab19a07cbc42f175021845.tar.gz | |
More documentation.
git-svn-id: svn://vcs.exim.org/pcre2/code/trunk@83 6239d852-aaf2-0410-a92c-79f79f948069
Diffstat (limited to 'doc/html/pcre2limits.html')
| -rw-r--r-- | doc/html/pcre2limits.html | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/doc/html/pcre2limits.html b/doc/html/pcre2limits.html new file mode 100644 index 0000000..4de3cf1 --- /dev/null +++ b/doc/html/pcre2limits.html @@ -0,0 +1,89 @@ +<html> +<head> +<title>pcre2limits specification</title> +</head> +<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB"> +<h1>pcre2limits man page</h1> +<p> +Return to the <a href="index.html">PCRE2 index page</a>. +</p> +<p> +This page is part of the PCRE2 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. +<br> +<br><b> +SIZE AND OTHER LIMITATIONS +</b><br> +<P> +There are some size limitations in PCRE2 but it is hoped that they will never +in practice be relevant. +</P> +<P> +The maximum size of a compiled pattern is approximately 64K code units for the +8-bit and 16-bit libraries if PCRE2 is compiled with the default internal +linkage size, which is 2 bytes for these libraries. If you want to process +regular expressions that are truly enormous, you can compile PCRE2 with an +internal linkage size of 3 or 4 (when building the 16-bit library, 3 is rounded +up to 4). See the <b>README</b> file in the source distribution and the +<a href="pcre2build.html"><b>pcre2build</b></a> +documentation for details. In these cases the limit is substantially larger. +However, the speed of execution is slower. In the 32-bit library, the internal +linkage size is always 4. +</P> +<P> +All values in repeating quantifiers must be less than 65536. +</P> +<P> +There is no limit to the number of parenthesized subpatterns, but there can be +no more than 65535 capturing subpatterns. There is, however, a limit to the +depth of nesting of parenthesized subpatterns of all kinds. This is imposed in +order to limit the amount of system stack used at compile time. The limit can +be specified when PCRE2 is built; the default is 250. +</P> +<P> +There is a limit to the number of forward references to subsequent subpatterns +of around 200,000. Repeated forward references with fixed upper limits, for +example, (?2){0,100} when subpattern number 2 is to the right, are included in +the count. There is no limit to the number of backward references. +</P> +<P> +The maximum length of name for a named subpattern is 32 code units, and the +maximum number of named subpatterns is 10000. +</P> +<P> +The maximum length of a name in a (*MARK), (*PRUNE), (*SKIP), or (*THEN) verb +is 255 for the 8-bit library and 65535 for the 16-bit and 32-bit libraries. +</P> +<P> +The maximum length of a subject string is the largest number a PCRE2_SIZE +variable can hold. PCRE2_SIZE is an unsigned integer type, usually defined as +size_t. However, when using the traditional matching function, PCRE2 uses +recursion to handle subpatterns and indefinite repetition. This means that the +available stack space may limit the size of a subject string that can be +processed by certain patterns. For a discussion of stack issues, see the +<a href="pcre2stack.html"><b>pcre2stack</b></a> +documentation. +</P> +<br><b> +AUTHOR +</b><br> +<P> +Philip Hazel +<br> +University Computing Service +<br> +Cambridge CB2 3QH, England. +<br> +</P> +<br><b> +REVISION +</b><br> +<P> +Last updated: 29 September 2014 +<br> +Copyright © 1997-2014 University of Cambridge. +<br> +<p> +Return to the <a href="index.html">PCRE2 index page</a>. +</p> |