Re: LL(1) parser table

Sean Case <>
7 Jan 2002 01:14:25 -0500

          From comp.compilers

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From: Sean Case <>
Newsgroups: comp.compilers
Date: 7 Jan 2002 01:14:25 -0500
Organization: Marginal
References: 02-01-026
Keywords: LL(1), parse
Posted-Date: 07 Jan 2002 01:14:25 EST

>, (lee) wrote:

> I am trying construct a LL1 parser table for the following grammar.

I have some questions about your grammar.

> S -> E
> E -> ++E | E++ | E-E | E/E | id

> where symbols have usual meanings.

1. Why no support for parentheses? (Try adding them - I think that
      it might make things clearer.)

> However in the final table this grammar seems to be ambiguous. I
> actually first transformed the above into this disambiguous form.

> S -> E
> E -> E-T | T
> T -> T/F | F
> F -> F++ | G
> G -> ++E | id

2. What is it about G that gives rise to a different kind of rule
      from those for T and F?

3. Suppose that you reversed the priority of prefix- and postfix-++
      (which I think you might have backwards anyway, but I'm not in a
      C frame of mind right now) -- what would be different about your
      transformed grammar?

Sean Case

Sean Case

Code is an illusion. Only assertions are real.

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