All~
On 7/1/05, Luke Palmer <[EMAIL PROTECTED]> wrote:
> > Attempting to come up with a simplistic math grammar that has one possible
> > operand (A) and one possible operator (*) - so that things like A, A*A, and
> > A*A*A*A*A are all parsed. This simplistic example (thanks to spinclad on
> > #perl6) cause PGE to explode.
> >
> > $ cat ta.p6r
> > grammar f;
> > rule atom { A }
> > rule binary { <expr> \* <atom> }
> > rule expr { <binary> }
>
> That probably shouldn't die so horribly, but it should die. We don't
> support left-recursive grammars, and this is one. A
> non-left-recursive grammar that matches the same language is:
>
> grammar f;
> rule atom { A }
> rule binary { <atom> \* <binary> }
Not to pick gnits or show off my ignorance too much, but shouldn't the
binary rule make the second part optional somehow?
rule binary { <atom> [\* <binary>]? }
Matt
--
"Computer Science is merely the post-Turing Decline of Formal Systems Theory."
-???
