[antlr-interest] Re: ANTLR 3.0 question about common actions

[Terence Parr]

On Jul 28, 2004, at 3:13 PM, thrutchy wrote:
> I would kind of like the ability to go in the complete opposite
> direction: express the complete grammar directly in the target
> language in a nice concise manner.

That is called JavaCC :)

> I haven't thought through this all the way, but
> here's what I was thinking:
>
> * Parser/lexer rules/sub-rules would be objects.  All of these would
> belong to a superclass (or interface) - I'll call it "Syntax" for now.
>
> * Some of the more generic Syntax sub-classes might be LoopSyntax:()*,
> AlterationSyntax:(|), ConditionalSyntax:()?, IgnoreSyntax:()!,
> CodeSyntax:{}, SequenceSyntax:() (),  etc.
>
> * You'd just use new to create a new Syntax object:
>
> Syntax mexpr = new SequenceSyntax( atom, new LoopSyntax( new
> SequenceSyntax( STAR, atom) ) );
>
> ...

> One of the disadvantages I see immediately is ANTLR's ability to
> detect ambiguities at compile time.  I'm not sure how that would be
> best handled.

Yup...and why build a parse tree manually for a grammar when you can 
just type the grammar? ;)  Grammars are damn hard to beat as far as I 
can tell for specifying language syntax.

> What do you think?

Interesting thoughts, Eric.  Thanks!

Ter
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