Re: Purple Dragon Book: Newbie questions on Chapter 4 text.

On Jun 10, 4:51 am, Joshua Cranmer <Pidgeo...@verizon.invalid> wrote:
> The reason that it's ambiguous is that if First(alpha) intersection
> Follow(A) is not empty, we can't tell if that terminal is part of alpha,
> and by consequent A, or if A is supposed to evaluate to epsilon and the
> terminal be part of Follow(A).




On Jun 10, 5:32 am, Felipe Angriman <felipeangri...@gmail.com> wrote:
>
> This means that when the parser need to make a choice between
> production rule 2 or 3 it will no be able to make such a choice
> because the select set are not disjoint.


Thanks, Josh and Felipe. FIRST(I) was having a difficulty but I think,
I FOLLOW(now). :-)


It seems, the three conditions will be necessary *only* when writing a
table-driven, predictive top-down parser and *not* when writing a
backtracking, top-down parser. Is this true, btw?

Return to the comp.compilers page.
Search the comp.compilers archives again.