[antlr-interest] Re: more lexical determinism
howardckatz
howardk at fatdog.com
Wed Dec 5 14:24:47 PST 2001
--- In antlr-interest at y..., Terence Parr <parrt at j...> wrote:
...
> As for distinguishing between the two kinds of words/ids, you could
> do the following in one rule (assume Word unless you see _ or
> digit):
>
> Word: ( Letter | '_' {$setType(Identifier);}) (Letter |
> Digit{$setType(Identifier);})*;
That didn't quite do it, I think, Doesn't the above say that anything
starting with a Letter is a Word? But that's not what I want, since
valid Identifiers can start with Letters too. The following should be
legal input,
id : word
but throws an "Unexpected token: id" error. I would guess the parser
sees this as "Word : Word" and accordingly chokes. Or am I
misunderstanding something?
Howard
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