abnf extracting code?

Does anyone have some code that does a good job of extracting ABNF 
information from an RFC/I-D?

If we can find some code that does a decent job, an idea for 
tools.ietf.org would be

	tools.ietf.org/abnf/RFC#

It would work just like tools.ietf.org/html/, but show the extracted 
ABNF code from the given RFC or I-D.

	Tony Hansen
	tony <at> att.com