NAME

Regexp::Optimizer - optimizes regular expressions

SYNOPSIS

      use Regexp::Optimizer;
      my $o  = Regexp::List->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;
$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 Regex::List
• Does not grok (?{expression}) and (?(cond)yes|no) constructs yet

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 Kogai

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.