C# で Between（やりすぎバージョン）

はじめに

　前回の Between() は、上限値と下限値をそれぞれ「含む」「含まない」を選択することができませんでした。今回、できるものをつくってみました。

　しかし、ちょっと重厚長大になりすぎる嫌いがあるので、有用ではないかもしれません。

サンプルコード

using System;

namespace BetweenTest
{
    class EndPoint<T>
    {
        public enum OperatorType
        {
            Including,
            Excluding
        }

        public T Value { get; set; }
        public OperatorType Operator { get; private set; }

        public EndPoint(T t) { Value = t; }

        public static EndPoint<T> Including(T val)
        {
            return new EndPoint<T>(val)
            {
                Operator = OperatorType.Including
            };
        }

        public static EndPoint<T> Excluding(T val)
        {
            return new EndPoint<T>(val)
            {
                Operator = OperatorType.Excluding
            };
        }
    }

    static class Ext
    {
        public static bool Between<T>(this T source, T low, T high) where T : IComparable
        {
            if (low.CompareTo(high) > 0) { throw new ArgumentException(); }

            return source.CompareTo(low) >= 0 && source.CompareTo(high) <= 0;
        }

        public static bool Between<T>(this T source, EndPoint<T> low, EndPoint<T> high) where T : IComparable
        {
            if (low.Value.CompareTo(high.Value) > 0) { throw new ArgumentException(); }

            bool validLow;
            if (low.Operator == EndPoint<T>.OperatorType.Including)
            {
                validLow = source.CompareTo(low.Value) >= 0;
            }
            else
            {
                validLow = source.CompareTo(low.Value) > 0;
            }

            bool validHigh;
            if (high.Operator == EndPoint<T>.OperatorType.Including)
            {
                validHigh = source.CompareTo(high.Value) <= 0;
            }
            else
            {
                validHigh = source.CompareTo(high.Value) < 0;
            }

            return validLow && validHigh;
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            if (5.Between(1, 6))
            {
                Console.WriteLine("Hello World!");
            }

            if ("5".Between("0", "9"))
            {
                Console.WriteLine("Hello World!");
            }

            var validRangeFrom = EndPoint<int>.Excluding(0);
            var validRangeLimit = EndPoint<int>.Including(5);

            if (5.Between(validRangeFrom, validRangeLimit))
            {
                Console.WriteLine("Hello World!");
            }
        }
    }
}