case MOD:
expressions[index] = mode == INTEGER ? new ModInteger(exp,
expressions[index + 1]) : new ModDouble(exp, expressions[index + 1]);
break;
case ADD:
expressions[index] = mode == INTEGER ? new AddInteger(exp,
expressions[index + 1]) : new AddDouble(exp, expressions[index + 1]);
break;
case SUB:
expressions[index] = mode == INTEGER ? new SubInteger(exp,
expressions[index + 1]) : new SubDouble(exp, expressions[index + 1]);