public PrgState execute(PrgState state)
 {
     Exp difSwitch = new ArithExp (Exp, "-", ExpCase2);
     Exp difSwitch2 = new ArithExp (Exp, "-", ExpCase1);
     IStmt ifSwitch = new IfStmt (difSwitch2, DefaultCase, Case1);
     IStmt switchStmt = new IfStmt (difSwitch, ifSwitch, Case2);
     state.ExeStack.Push (switchStmt);
     return null;
 }
        public PrgState execute(PrgState state)
        {
            Exp   difSwitch  = new ArithExp(Exp, "-", ExpCase2);
            Exp   difSwitch2 = new ArithExp(Exp, "-", ExpCase1);
            IStmt ifSwitch   = new IfStmt(difSwitch2, DefaultCase, Case1);
            IStmt switchStmt = new IfStmt(difSwitch, ifSwitch, Case2);

            state.ExeStack.Push(switchStmt);
            return(null);
        }