Re: Lookahead vs. Scanner Feedback

In article 92-01-012 hjelm+@cs.cmu.edu (Mark Hjelm) writes:
      How do I KNOW that there are no situations
      which, due to parser lookahead, would cause the scanner to return an
      incorrect token type for an identifier (i.e. return "identifier", even
      though the identifier was just/will be made into a "typedef name")?


Well, I assume that you're being careful about redeclarations. For
instance,


typedef int a;
{
float a;
a++;
}


is legal in ANSI C. What you need, of course, is to have a few places
in the grammar that allow either an identifier or a typedef name.


In general, I know of no way of verifying that your parser has
everything right, although meticulous comparison of the ANSI rules and
your parser will help, and thorough exercising with C validation
suites will help.


Dale Worley Dept. of Math., MIT drw@math.mit.edu
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