On 2006-04-06, at 18:49:20 +0200, Akim Demaille wrote:
> >>> "Marcus" == Marcus Holland-Moritz <[EMAIL PROTECTED]> writes:
>
> > Hi,
> > I'm using bison for a C parser [1], for which I'm currently rewriting
> > the part that parses expressions.
>
> > While being at it, I wondered if it's possible to reuse a certain part
> > of a bison generated parser, e.g. by setting a different %start token
> > at runtime.
>
> I use the following technique.
>
> Suppose you want to branch on nonterminals foo and bar. Introduce
> fresh tokens START_FOO and START_BAR, and use the following real
> axiom:
>
> start:
> START_FOO foo
> | START_BAR bar
>
> then the trick is to have your scanner pass either START token first.
Cool, it seems like that was just what I was looking for.
I'll have a closer look when I've overcome my jetlag...
> If you have a bleeding edge bison supporting push parsers, that's
> trivial :) If you wrote yylex yourself, it shouldn't be too hard.
Yes, I wrote my own yylex.
Thank you very much for your help!
Marcus
--
Sattinger's Law:
It works better if you plug it in.
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