Keyboard-Calculator/Calculator/OperationElement.cs

namespace Calculator
{
    internal class OperationElement : CalculationElement
    {
        public Operation Operation { get; }

        public OperationElement(Operation operation)
        {
            Operation = operation;
        }

        public override string ToString()
        {
            switch (Operation)
            {
                case Operation.Add:
                    return "+";

                case Operation.Subtract:
                    return "-";

                case Operation.Muliply:
                    return "*";

                case Operation.Divide:
                    return "/";

                default:
                    return "Null";
            }
        }

        public override bool Equals(object obj)
        {
            return Equals(obj as OperationElement);
        }

        public bool Equals(OperationElement other)
        {
            return other != null &&
                   Operation == other.Operation;
        }

        public override int GetHashCode()
        {
            return 1706920598 + Operation.GetHashCode();
        }
    }

    internal enum Operation
    {
        Add,
        Subtract,
        Muliply,
        Divide
    }
}