object Expr.IVisitor <object> .Visit(Expr.Prefix _prefix)
{
object right = Evaluate(_prefix.right);
switch (_prefix.opp.type)
{
case TokenType.MINUS:
CheckNumberOperand(_prefix.opp, right);
return(-(double)right);
case TokenType.BANG:
return(!IsTruthy(right));
default:
break;
}
//unreachable
return(null);
}
string Expr.IVisitor <string> .Visit(Expr.Prefix _prefix)
{
return(Parenthesize(_prefix.opp.lexeme, _prefix.right));
}
public object Visit(Expr.Prefix _prefix)
{
Resolve(_prefix.right);
return(null);
}