IEqualityComparer 应用 Distinct Contains 扩展功能实现某个字段的对比

最新推荐文章于 2022-11-11 11:22:18 发布

土豆赛叩

最新推荐文章于 2022-11-11 11:22:18 发布

阅读量426

点赞数

CC 4.0 BY-SA版权

分类专栏： C#

本文链接：https://blog.youkuaiyun.com/Vblegend_2013/article/details/78991751

C# 专栏收录该内容

83 篇文章

订阅专栏

本文介绍了一种.NET中自定义的扩展方法，通过创建通用比较器实现对特定字段的重复检查和包含判断，适用于集合操作。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

创建以下两个类  即可使用 Distinct   Contains 扩展功能 实现某个字段的对比

    public static class Equality<T>
    {
        public static IEqualityComparer<T> CreateComparer<V>(Func<T, V> keySelector)
        {
            return new CommonEqualityComparer<V>(keySelector);
        }
        public static IEqualityComparer<T> CreateComparer<V>(Func<T, V> keySelector, IEqualityComparer<V> comparer)
        {
            return new CommonEqualityComparer<V>(keySelector, comparer);
        }
        public class CommonEqualityComparer<V> : IEqualityComparer<T>
        {
            private Func<T, V> keySelector;
            private IEqualityComparer<V> comparer;

            public CommonEqualityComparer(Func<T, V> keySelector, IEqualityComparer<V> comparer)
            {
                this.keySelector = keySelector;
                this.comparer = comparer;
            }
            public CommonEqualityComparer(Func<T, V> keySelector)
                : this(keySelector, EqualityComparer<V>.Default)
            { }

            public bool Equals(T x, T y)
            {
                return comparer.Equals(keySelector(x), keySelector(y));
            }
            public int GetHashCode(T obj)
            {
                return comparer.GetHashCode(keySelector(obj));
            }
        }
    }

    /// <summary>
    /// 扩展类
    /// </summary>
    public static class Extensions
    {
        /// <summary>
        /// 指定某个字段的重复
        /// </summary>
        /// <returns></returns>
        public static IEnumerable<T> Distinct<T, V>(this IEnumerable<T> source, Func<T, V> keySelector)
        {
            return source.Distinct(Equality<T>.CreateComparer(keySelector));
        }
        /// <summary>
        /// 指定某个字段的重复
        /// </summary>
        /// <returns></returns>
        public static IEnumerable<T> Distinct<T, V>(this IEnumerable<T> source, Func<T, V> keySelector, IEqualityComparer<V> comparer)
        {
            return source.Distinct(Equality<T>.CreateComparer(keySelector, comparer));
        }

        /// <summary>
        /// 指定某个字段的包含
        /// </summary>
        /// <returns></returns>
        public static bool Contains<T, V>(this IEnumerable<T> source, T value, Func<T, V> keySelector)
        {
            return source.Contains(value, Equality<T>.CreateComparer(keySelector));
        }
    }