Returning multiple values in ANTLR rule

7
votes

I have an ANTLR rule like this

receive returns[Evaluator e,String message]
  : RECEIVE FILENAME {$e= new ReceiveEvaluator($FILENAME.text);}
  ;

I have added a new return message and I want to put the file content in that. One way I could do is make the evaluator return the String when I walk the tree by calling the evaluate() method.

I was wondering if I could do it strightaway here - but am not aware how to set multiple return values and access them later.

Thanks Hari

1
antlr

1 Answers

7
votes

Here's how to set- and use multiple return values:

parse
  :  r=receive {
       Evaluator e = $r.evaluator;
       String m = $r.message;
     }
  ;

receive returns[Evaluator evaluator, String message]
  :  RECEIVE f=FILENAME {
       $evaluator = new ReceiveEvaluator($f.text);
       $message = "Some message here...";
     }
  ;