[antlr-interest] example where backtracking fails

[Terence Parr]

Folks,

I remember that years ago there was a nice example of a backtracking LL 
parser failing to correctly match the input.  Naturally this must be 
because use of lookahead myopically removes a path in the parse that 
will eventually lead to the correct parse.  Intuitively that sort of 
makes sense, but I can't remember where I saw that grammar.  Since a 
backtracker always tries all possibilities, i was surprised to find an 
example that didn't work (now I conclude it must be because of 
lookahead).

Can anybody help find that thing.  I've spent an hour in google and 
yahoogroups.com and dejanews.com :(

Thanks,
Ter
--
Co-founder, http://www.jguru.com
Creator, ANTLR Parser Generator: http://www.antlr.org
Lecturer in Comp. Sci., University of San Francisco


 

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