[antlr-interest] Variable definition annoyances

[Scott Stanchfield]

> Yep, that is really annoying.  I racked my brain over it for 
> a long time.  It turns out you don't need to define them 
> anymore.  You can do
> this:
> 
> start : r=rule { @r.i ... @r.s ... } ;

I pretty-much like, but can't we infer a variable for the rule? So it would
just be:

  start
    : rule { @rule.i ... } ;

You could easily do this by genning

  ResultType __rule = rule();
  __rule.i

Or some such thing.

For multiple refs. They could be numbered:

  start
    : rule otherRule rule { @rule[1].i ... @rule[2] ... }
    ;

Which could expand to 

  __rule_1 = rule();
  __otherRule = otherRule();
  __rule_2 = rule();
  ...


Though while we're at it, I'd really like to define a standard syntax that
can be for antlr replacement in action code with an obvious start and end,
which is why I suggested a paired delimiter like :: on either end. We'd just
need to pick something not super likely to appear in the action code...

> rule returns [int i, String s] : ... {@i=3; @s="foo";} ... ;
> 
> Cool eh?  Does this satisfy you?  It integrates very nicely 
> with the dynamically scoped attributes and trees etc...

Actually, why would we need to use the @ in that syntax? In ANTLR 2.0 with
the same syntax we just use i and s...  Wait a sec... Multiple return
values? Are you pushing them on a stack or something?

-- Scott