modules for optimizing regular expressions

 This contains two modules, Regexp::List and Regexp::Optimizer.
 .
 Regexp::List offers a method which turns a list of words into an
 optimized regular expression which matches all words therein.
 The optimized regular expression is much more efficient than a
 simple-minded '|'-concatenation.
 .
 Regexp:Optimizer factors out common suffices/prefices in regular
 expressions (trie optimization). Currently, the user has to optimize
 "foo|far" and "foo|goo" into "f(?:oo|ar)" and "[fg]oo" by hand;
 this module does it automatically.