如何使用ANTLR词法分析器和解析器编写MIN MAX操作？

Question

For my project I have to define a new grammar rule while will calculate the MIN or MAX of giving argument.Below is the example.

MIN(3, 4, 5, 6) = 3

MIN(3, 5, 6, 7, 8) = 3

Basically the problem I am facing is defining the TreeWalker function, where it should take variable number of argument.

The language I am using is Java.

OK I will put a snippet of the code which is more or less similar but not the exact one

Parser Rule:

minExpr
  : MIN^ LPAREN! minExprStmt RPAREN!
  ;

minExprStmt
  : digitExpr (COMA! digitExpr)+
  ;

Lexer Rule:

token{
  MIN="MIN"
}

TreeWalker:

getNode return [double r]
 {ExpNode a=null; r = null;}
 : #(MIN a=getNode)
      {try{r=new MinExpNode();}catch(Exception e){throw new RecognitionException(e.toString();}}

So now what I want is that MinExpNode should take a list or an array of ExpNode in constructor, which in turn will give the computed value of each expNode.

I am not using any external libraries for this.

Answer 1

Well after some research I think I found a solutions, TreeWalker Code:

getNode return [double r]
  {ExpNode a=null; List<ExpNode> list = new ArrayLis<ExpNode>(); r = null;}
  : #(MIN a=getNode {list.add(a);} ({ExpNode b = getNode; list.add(b);})*)
       {try{r=new MinExpNode(list);}catch(Exception e){throw new RecognitionException(e.toString();}}

But still if you can suggest me a better one it would be very helpful.