Re: Maintaining scope while parsing C with a YACC grammar

On Apr 26, 7:22 pm, Robert A Duff <bobd...@shell01.TheWorld.com>
wrote:
> eliben <eli...@gmail.com> writes:
> > [There's a couple of possibilities. One is to add separate rules for
> > the open and close braces with action code that increments and
> > decrements the nesting level, so you know when you reduce the
> > declaration what scope it is in. Another is to parse the whole thing
> > into an AST without trying to interpret the symbols other than making
> > pointers to a generic symbol table entry per name, then walk the AST
> > and add the scope and type info. Perhaps people will have other
> > suggestions. -John]
>
> I strongly recommend the "build a tree" solution. It might seem like
> a lot of trouble at first, but it will simplify things in the long
> run.
>
> Do all the interesting work during a subsequent walk of the tree. Or
> multiple walks.


Since it's parsing of C I'm talking about, this approach will have to
somehow handle ambiguity of this kind:


T * x;


This can be either a declaration or a multiplication, depending on
earlier symbol table information (whether T is a type or not).


So are you proposing to build an ambiguous AST that contains *both*
parses and resolve between them in later passes? Or just pick one and
maybe modify it later? Do you have references (papers, books, etc.)
explaining this technique?


Thanks in advance

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