[antlr-interest] Re: Building hierarchical grammars

John D. Mitchell johnm-antlr at non.net
Sun Mar 28 15:00:58 PST 2004


>>>>> "Mike" == Mike Lischke <lists at lischke-online.de> writes:
[...]

> However, building things up hierarchically works great with ANTLR. But
> maybe only when build the hierarchy up with protected tokens?

Exactly.


>> Lexers, on the other hand, have to pick from among ALL the Lexer rules
>> each and every time they are asked for the next token.  They don't
>> 'know' where they are called from in the parser, and so can't restrict
>> the set of token parses for a particular case.

> Thanks for pointing this out. This is an important point IMO, also when
> it comes to performance. And it explains a lot.

So, using the "protected" qualifier effectively hides those
sub-rules/-hierarchies.

Have fun,
	John



 
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