Re: Syntax diagram driven parser

VBDis <vbdis@aol.com> wrote:
>
> The resulting grammar uses my own extensions to BNF, with context
> variables.


Ah. This sounds similar van Wijngaarden Two-Level grammars. These are
context-sensitive, just like your grammar is. They can also be used
to express typing constraints, so you wrote something much more
powerful than you might have intended.


> In the OPL syntax also cases exist, where the kind of a symbol is
> important, whether it represents e.g. a constant value, a module name
> etc. I'm not very familiar with theory of grammars, but I doubt that
> a parser would be able to determine the kind of a symbol, which is
> imported from another module, and thus *cannot* know which syntax rule
> to use.


Hmmm... you'd have to parse the imported module as well to gain that
information. Or learn how to decipher the format of compiled Delphi
modules.
Yuck.


I don't know the actual Delphi syntax and what you're exactly trying to
do. It might be a good idea to write a grammar that's context free and
occasionally accepts a grammatically wrong Delphi program. (That's the
classical approach for add-on tools that are not compilers in
themselves.)


Regards,
Joachim

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