Rechercher une page de manuel
Regexp::Optimizer.3pm
Langue: en
Version: 2004-12-05 (ubuntu - 07/07/09)
Section: 3 (Bibliothèques de fonctions)
Sommaire
NAME
Regexp::Optimizer - optimizes regular expressionsSYNOPSIS
use Regexp::Optimizer; my $o = Regexp::Optimizer->new; my $re = $o->optimize(qr/foobar|fooxar|foozap/); # $re is now qr/foo(?:[bx]ar|zap)/
ABSTRACT
This module does, ahem, attempts to, optimize regular expressions.INSTALLATION
To install this module type the following:perl Makefile.PL make make test make install
DESCRIPTION
Here is a quote from perltodo.- Factoring out common suffices/prefices in regexps (trie optimization)
Currently, the user has to optimize ``foo|far'' and ``foo|goo'' into ``f(?:oo|ar)'' and ``[fg]oo'' by hand; this could be done automatically.
This module implements just that.
EXPORT
Since this is an OO module there is no symbol exported.METHODS
This module is implemented as a subclass of Regexp::List. For methods not listed here, see Regexp::List.- $o = Regexp::Optimizer->new;
- $o->set(key => value, ...)
- Just the same us Regexp::List except for the attribute below;
-
- unexpand
- When set to one, $o->optimize() tries to $o->expand before actually starting the operation.
# cases you need to set expand => 1 $o->set(expand => 1)->optimize(qr/ foobar| fooxar| foozar /x);
-
- $re = $o->optimize(regexp);
- Does the job. Note that unlike "->list2re()" in Regexp::List, the argument is the regular expression itself. What it basically does is to find groups will alterations and replace it with the result of "$o->list2re".
- $re = $o->list2re(list of words ...)
- Same as "list2re()" in Regexp::List in terms of functionality but how it tokenize ``atoms'' is different since the arguments can be regular expressions, not just strings. Here is a brief example.
my @expr = qw/foobar fooba+/; Regexp::List->new->list2re(@expr) eq qr/fooba[\+r]/; Regexp::Optimizer->new->list2re(@expr) eq qr/foob(?:a+ar)/;
CAVEATS
This module is still experimental. Do not assume that the result is the same as the unoptimized version.- •
- When you just want a regular expression which matches normal words with not metacharacters, use <Regexp::List>. It's more robus and much faster.
- •
- When you have a list of regular expessions which you want to aggregate, use "list2re" of THIS MODULE.
- •
- Use "->optimize()" when and only when you already have a big regular expression with alterations therein.
"->optimize()" does support nested groups but its parser is not tested very well.
BUGS
- •
- Regex parser in this module (which itself is implemented by regular expression) is not as thoroughly tested as Regexp::List
- •
- May still fall into deep recursion when you attempt to optimize deeply nested regexp. See ``PRACTICALITY''.
- •
- Does not grok (?{expression}) and (?(cond)yes|no) constructs yet
- •
- You need to escape characters in character classes.
$o->optimize(qr/[a-z()]|[A-Z]/); # wrong $o->optimize(qr/[a-z\(\)]|[A-Z]/); # right $o->optimize(qr/[0-9A-Za-z]|[\Q-_.!~*"'()\E]/ # right, too.
- •
- When character(?: class(?:es)?)? are aggregated, duplicate ranges are left as is. Though functionally OK, it is cosmetically ugly.
$o->optimize(qr/[0-5]|[5-9]|0123456789/); # simply turns into [0-5][5-9]0123456789] not [0-9]
I left it that way because marking-rearranging approach can result a humongous result when unicode characters are concerned (and \p{Properties}).
PRACTICALITY
Though this module is still experimental, It is still good enough even for such deeply nested regexes as the followng.# See 3.2.2 of http://www.ietf.org/rfc/rfc2616.txt # BNF faithfully turned into a regex http://(?:(?:(?:(?:(?:[a-z]|[A-Z])|[0-9])|(?:(?:[a-z]|[A-Z])|[0-9])(?:(?:(?:[a-z]|[A-Z])|[0-9])|-)*(?:(?:[a-z]|[A-Z])|[0-9]))\.)*(?:(?:[a-z]|[A-Z])|(?:[a-z]|[A-Z])(?:(?:(?:[a-z]|[A-Z])|[0-9])|-)*(?:(?:[a-z]|[A-Z])|[0-9]))\.?|[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+)(?::[0-9]*)?(?:/(?:(?:(?:(?:[a-z]|[A-Z])|[0-9])|[\-\_\.\!\~\*\'\(\)])|%(?:[0-9]|[A-Fa-f])(?:[0-9]|[A-Fa-f])|[:@&=+$,])*(?:;(?:(?:(?:(?:[a-z]|[A-Z])|[0-9])|[\-\_\.\!\~\*\'\(\)])|%(?:[0-9]|[A-Fa-f])(?:[0-9]|[A-Fa-f])|[:@&=+$,])*)*(?:/(?:(?:(?:(?:[a-z]|[A-Z])|[0-9])|[\-\_\.\!\~\*\'\(\)])|%(?:[0-9]|[A-Fa-f])(?:[0-9]|[A-Fa-f])|[:@&=+$,])*(?:;(?:(?:(?:(?:[a-z]|[A-Z])|[0-9])|[\-\_\.\!\~\*\'\(\)])|%(?:[0-9]|[A-Fa-f])(?:[0-9]|[A-Fa-f])|[:@&=+$,])*)*)*(?:\\?(?:[;/?:@&=+$,]|(?:(?:(?:[a-z]|[A-Z])|[0-9])|[\-\_\.\!\~\*\'\(\)])|%(?:[0-9]|[A-Fa-f])(?:[0-9]|[A-Fa-f]))*)?)? # and optimized http://(?::?[a-zA-Z0-9](?:[a-zA-Z0-9\-]*[a-zA-Z0-9])?\.[a-zA-Z]*(?:[a-zA-Z0-9\-]*[a-zA-Z0-9])?\.?|[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+)(?::[0-9]*)?(?:/(?:(?:(?:[a-zA-Z0-9\-\_\.\!\~\*\'\x28\x29]|%[0-9A-Fa-f][0-9A-Fa-f])|[:@&=+$,]))*(?:;(?:(?:(?:[a-zA-Z0-9\-\_\.\!\~\*\'\x28\x29]|%[0-9A-Fa-f][0-9A-Fa-f])|[:@&=+$,]))*)*(?:/(?:(?:(?:[a-zA-Z0-9\-\_\.\!\~\*\'\x28\x29]|%[0-9A-Fa-f][0-9A-Fa-f])|[:@&=+$,]))*(?:;(?:(?:(?:[a-zA-Z0-9\-\_\.\!\~\*\'\x28\x29]|%[0-9A-Fa-f][0-9A-Fa-f])|[:@&=+$,]))*)*)*(?:\\?(?:(?:[;/?:@&=+$,a-zA-Z0-9\-\_\.\!\~\*\'\x28\x29]|%[0-9A-Fa-f][0-9A-Fa-f]))*)?)?
By carefully examine both you can find that character classes are properly aggregated.
SEE ALSO
Regexp::List --- upon which this module is based"eg/" directory in this package contains example scripts.
- Perl standard documents
-
L<perltodo>, L<perlre>
- CPAN Modules
- Regexp::Presuf, Text::Trie
- Books
- Mastering Regular Expressions <http://www.oreilly.com/catalog/regex2/>
AUTHOR
Dan Kogai <dankogai@dan.co.jp>COPYRIGHT AND LICENSE
Copyright 2003 by Dan KogaiThis library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
Contenus ©2006-2024 Benjamin Poulain
Design ©2006-2024 Maxime Vantorre