Don't despair! A quick CPAN search for 'vhdl' yields Hardware::Vhdl::Lexer, which, even if it doesn't do quite what you want, might provide some useful pointers if you look at the source code.

BTW, I read 'Pro Perl Parsing' some time ago, and it didn't leave any lasting impression on me (other than the fact that it was the first Perl book that I had read with absolutely no humour in it!)