------ Original Message (Saturday, August 14, 2010 2:13:47
AM) From: Joachim Schrod ------
Subject: [antlr-interest] Best practice to handle Lexer backtracking demand
Doubt that there is any one true best practice. A truism that may help
is "try not to do too much in the lexer."
Given that your valid input text is pretty much defined by
> CHAR : . ;
>
likely best to defer key word matching to the parser
> name : n=text ( { helper.isKeyword($n) }? text )? ;
> text : CHAR+ ;
>
> CHAR : . ;
and provide for the helper in the parser::members block.
> Using syntactic predicates? I tried that but did not succeed.
> AFAIU, they are a parser feature, but I'd need them in the lexer.
No, they work in the lexer as well. It is just that the lexer defaults
effectively k=1, so the predicated alternatives need to be specified.
Or, use an embedded options block to push up the value of k.
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