[gcjx] Generalise visitor

[Tom Tromey]

>>>>> "Ranjit" == Ranjit Mathew <rmathew@gmail.com> writes:

Ranjit> The new methods are not exhaustive, but it's a start - technically,
Ranjit> I could have just added visit() to model_element and a visit_element()
Ranjit> to visitor and be done with it. However, I've attempted to declare
Ranjit> a few more. The implementations of the methods are dummies for now.

Ideally model_element::visit would be abstract.  Presumably there are
still other elements that aren't handled?

Ranjit> If this is not too gross, may I apply it?

Yes.

Ranjit> There's another patch to fix "gcc/java" for the new changes.

Please put it in too.

Ranjit> +  virtual void visit (visitor *);

I usually don't reiterate the 'virtual'.

Ranjit> +  void visit_forwarding_type (model_forwarding_type *,
Ranjit> +                              const model_type *)
Ranjit> +  {
Ranjit> +    // Nothing.
Ranjit> +  }

We should have mixins that implement different subsets of the
visitors, either as do-nothings or abort()s (or either -- write the
mixin as a template).  It seems to me that often a given visitor
really only wants to deal with some subset of the model.

In fact I considered doing this already, since fold already only wants
to visit expressions, not statements.

Tom