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Re: extra lookahead sets in report
From: |
Akim Demaille |
Subject: |
Re: extra lookahead sets in report |
Date: |
Thu, 18 Oct 2007 12:18:54 +0200 |
User-agent: |
Gnus/5.110006 (No Gnus v0.6) Emacs/22.0.95 (gnu/linux) |
>>> "JED" == Joel E Denny <address@hidden> writes:
> I committed this. Is it significant enough for NEWS?
I would say so.
> +# Within a single state, Bison used to print a reduction's lookahead set
> next
> +# to all items of the associated rule. Instead, it should only print it
> next
> +# to the item that is of the associated rule and whose dot is at the end of
> the
> +# RHS. Printing it next to items whose dot is not at the end of the RHS is
> +# sometimes redundant and, as in this test case, is sometimes incorrect.
I don't remember the details, but are you saying that the lookahead
set is not computed for each item, but rather for a single rule?
I found it quite convenient to have all the lookahead sets when trying
to understand some conflicts but following the lookaheads starting
from $start (more LR(1) than LALR(1), but still useful to understand
what's going on).
Even if the result is incorrect (excuse my Bison's French ;)
état 1
2 start: 'a' . a 'a'
3 a: . 'a' [$end]
3 | 'a' . [$end]
'a' décalage et aller à l'état 4
$défaut réduction par utilisation de la règle 3 (a)
a aller à l'état 5
it does faithfully reflect the automaton, right?