[antlr-interest] Proposal: Change Java templates to eliminate redundant casts based on labelType

[Austin Hastings]

I'm not sure who is maintaining the Java codegen templates, so this goes 
to everybody.

I'd like to eliminate the redundant cast warnings in the java templates.

Currently there is a labelType parameter, declared: labelType = "Token" 
which I think specifies a default value.

The labelType gets used in two ways. It can be a type in its own right, 
or a type name in a cast:

<labelType> next_token = (<labelType>) input.LT(1);

I think the type cast can be replaced by a 'function' that returns a 
cast if the labelType is set:

<if(labelType)>(<labelType>)<endif>

Similarly, the declaration side could be handled by replacing the 
"default value" by a condition:

<if(labelType)><labelType><else>Token<endif>

I believe this would clean up the redundant casts of LT(1) to (Token) 
that appear in nearly every generated rule.

=Austin