Re: draft-fielding-uri-rfc2396bis-07 ABNF


I think you need to be careful about conflating a grammar as a 
specification of correct sentences (and correspo0nding parse trees) with a 
grammar as guiding a particular parser implementation.  The importance of 
grammars satisfying certain properties for LL(1) or LALR parser generation 
is that they permit creation of the parse tree without backtracking.

In this case, I think it's sufficient that the grammar satisfies the former 
purpose;  implementation is a matter for the, er, implementer.


At 13:34 06/12/04 -0500, Bruce Lilly wrote:

>On Mon December 6 2004 12:00, Graham Klyne wrote:
> > >Are there any implementations using the ABNF as specified in the draft?
> >
> > My Haskell implementation [1] is hand-coded, but attempts to follow the
> > given syntax very closely.  But my approach is top-down, not LALR, so that
> > probably doesn't answer your question.
>Thanks for the pointers, but you're right that it doesn't answer
>my question.  My concern is with the specification of the
>grammar, which I believe to be incomplete (and therefore
>unimplementable as an LALR parser in a manner which
>guarantees interoperability) as there is no specified set of
>precedence relationships necessary to resolve the existing
>conflicts (ideally, there are no conflicts in a well-designed

Graham Klyne
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Received on Tuesday, 7 December 2004 11:35:41 UTC