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> but we shouldn't forget that this kind of failure can only happen starting from an ambiguous grammar specification I don't think that's true. The following C
by yatac42 2y ago
> but we shouldn't forget that this kind of failure can only happen starting from an ambiguous grammar specification
I don't think that's true. The following CFG is unambiguous:
S ::= A S | A
A ::= 'a' | 'a' 'b'
Yet if we translate this 1-to-1 to a PEG (without changing the order of the alternatives), it's not going to match any input with 'b's in it, so it doesn't match the same language.
- HelloNurse 2y agoThis grammar is difficult to adapt to ordered choice, having 4 possible variants that mostly define different languages from each other and from the "same" grammar with traditional parsing. It's a formally very different problem from spontaneously and arbitrarily disambiguating an ambiguous grammar, but in practice it causes the same kind of suffering and it's likely to be a more common issue.