Re: Determining LR(k)-ness

[Philip Aker]

On 2009-11-18, at 14:41:29, John Levine wrote:

> > > For an arbitrary .y file, I'd like to know if it's possible to get
> > > some report detail that would tell me (when using the %glr-parser
> > > option) what was the maximum 'k' lookahead used for that grammar.
> >
> > Unless it has been changed lately, it just uses LALR(1) and splits  
> > the
> > parse when ambiguous.
>
> That's what it does.  Bison can tell you whether a grammar is LALR(1),
> but if it's not it can't tell you what class of language it is.

Hi John,

> It is my impression that most practical GLR grammars have parses  
> that collapse pretty quickly after they split,

For the info which I would find useful, this would be an important  
part -- i.e.

glrinfo: split level 1, split at state 216 (somename: someothername, …)


> but I don't have any statistics to back that up.


Philip Aker
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