Given that parsing text is one of Perl's core competencies, that may be a question without a really-good, on-target answer...
      ...or, I may just be iggerant.

However, for what you've described (at least as I understand it), you may be well served by parts of the "Perl Cookbook" and "Mastering Regular Expressions" (both pub by O'Reilly).

And if the rust is really heavy (or "free" is really crucial) http://www.perl.org/books/library.html.