[antlr-interest] Implementing if statements in a tree parsing Interpreter

[Matthew M. Burke]

Thanks to all who wrote with suggestions, etc. 

I finally twigged to a solution that allowed me to get the approach I 
had started to work---probably should have spotted this quicker.  In 
case anybody's interested, the key line of code is flagged below:

Matthew M. Burke wrote:
>
> Now in the tree parser, I have
>
> statement
>     : ...
>     | ^(SAME_CMD a=val b=val .) {
>                       int aval = $a.value;
>                       int bval = $b.value;
>                       if (a == b) {
>                             // HERE'S THE KEY
>   
                                                           CommonTree 
blockRoot = (CommonTree)($statement.start.getChild(2));
                                                          ......
>                       }
>     }
>     | ...
>     ;
>
>