|
From: | Hans Aberg |
Subject: | Re: Are Google summer of code 2006 ideas still available? |
Date: | Tue, 20 Mar 2007 20:57:13 +0100 |
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
[Prev in Thread] | Current Thread | [Next in Thread] |