Re: Are Google summer of code 2006 ideas still available?

[Hans Aberg]

On 20 Mar 2007, at 20:46, Ramón García wrote:

> > As for the "Burke-Fisher Error Correction", error recovery is poor in
> > Bison because the LALR(1) algorithm may, when an error token appears
> > in the input, performed some reductions before the error is reported.
>
> Perhaps I am wrong, but I think that these wrong reductions also
> exists when using efficient (non cannonical) LR(1) implementations.
> What they do is to apply the LALR(1) simplifications, but only when no
> ambiguity is added. In particular, if a grammar is LALR(1), the
> efficient LR(1) performs exactly the same shits and reductions.

I haven't looked too careful at these "efficient" LR(1).

If it is, as you suggest, that they still merge states in a way that  
error tokens are not reported immediately but some reductions can  
take place, then the ability of good error reporting, as well being  
able to report interactively possible token completions are  
properties that will be destroyed.

And adding LR(1) just in order to get a larger grammar class may not  
be so important, in view of GLR applied to LALR(1).

  Hans Aberg