Re: "No attempt has been made to compare performance. " Absolutely! I thought about rolling that in, but the question was already long and complex. I totally agree that should be measured and factored in, however, a few saying around that -- "premature optimization is a bane". Similar to priorities on code development: 1) get something working, 2) then look at other issues (like perf, etc).

Of the solutions I've seen, both seem like they wouldn't be too different as they use similar methodology. A multi-state parser might be faster than an RE, but maybe not if written in interpreted perl code. One might have to go to 'XS' to gain speed that way.