[Baypiggies] extended LL(1) parser with backtrack ?

[Rick Kwan]

I know this seems like an oxymoron, but ...  before I write my own
thing, I'm looking for an extended LL(1) parser with backtrack.  (If
"extended LL(1)" doesn't register with you, think extended BNF or
railroad tracks courtesy of Niklaus Wirth.  And if that doesn't cut
it, you may want to ignore this message.)

Why in the world would I want to backtrack?  This is for user input,
where the user is able to go back and give a different set of tokens
from what was originally given.

Of course, I'm looking for something which executes in Python.  (I've
looked at ANTLR and YAPPS2; I don't think either handles
backtracking.)

--Rick Kwan