[gcjx] Expand visitor interface

[Tom Tromey]

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

Ranjit>   My maniacal obsession with the visitor interface and the
Ranjit> pretty-printer continues. This patch seeks to bring as many
Ranjit> of the remaining model classes as possible under the visitor.

Thanks.

Ranjit>   3. Classes like model_annotation and
Ranjit>   model_annotation_initializer that just abort() in their
Ranjit>   visit() implementations.

This was just an error-catching move on my part; some of these inhabit
an odd place where they are derived classes for implementation
convenience, but visiting them in a traditional code generation sense
would be a mistake.  With the enlarged visitor approach, removing
these abort()s makes sense.

Ranjit> This is also the reason for some of the quirky parameters
Ranjit> for some of the visit_xxx methods and why I had to
Ranjit> make model_block::statements, etc. protected instead of
Ranjit> private.

Interesting; now I've learned more about why inheritance is sucky.
Or something.

Ranjit> OK?

Yes, thanks.

Tom