Re: Free Ada parser

["Robert I. Eachus" <rieachus@comcast.net>]

Oliver Kellogg wrote:

> True, I had to resolve a couple of those ambiguities
> while developing the ANTLR Ada grammar, but once you
> really get into the ANTLR way of thinking it's not too bad.
> Plus, this is a single-shot problem - it only affects the
> development of the grammar itself but not its users.

It is a property of writing grammars in general, doesn't matter how good 
the tools are.  If you write a grammar and it is say, LALR2 instead of 
LALR1, how likely is it that the tools can point to what you will think 
is the error?

Very unlikely of course.  The error that you made will almost certainly 
  be some production with a lookahead of one.  It is one or more 
potential prefixes of that production that will need to have a lookahead 
of two.

So when I am creating a grammar, I start with a 'skeleton' that has all 
the main features, then add details like identifier lists in object 
declarations.  Since I check the grammar after every extension, the 
problem must involve one of the productions I just added.


-- 
                                           Robert I. Eachus

100% Ada, no bugs--the only way to create software.