添加项目文件。

common/Tnb.Common/Security/EqualityHelper.cs

@@ -0,0 +1,62 @@
+using JNPF.DependencyInjection;
+
+namespace JNPF.Common.Security;
+
+/// <summary>
+/// 相等比较辅助类，用于快速创建<see cref="IEqualityComparer{T}"/>的实例.
+/// </summary>
+/// <example>
+/// var equalityComparer1 = EqualityHelper[Person].CreateComparer(p => p.ID);
+/// var equalityComparer2 = EqualityHelper[Person].CreateComparer(p => p.Name);
+/// var equalityComparer3 = EqualityHelper[Person].CreateComparer(p => p.Birthday.Year).
+/// </example>
+/// <typeparam name="T">要比较的类型.</typeparam>
+[SuppressSniffer]
+public static class EqualityHelper<T>
+{
+    /// <summary>
+    /// 创建指定对比委托<paramref name="keySelector"/>的实例.
+    /// </summary>
+    public static IEqualityComparer<T> CreateComparer<TV>(Func<T, TV> keySelector)
+    {
+        return new CommonEqualityComparer<TV>(keySelector);
+    }
+
+    /// <summary>
+    /// 创建指定对比委托<paramref name="keySelector"/>与结果二次比较器<paramref name="comparer"/>的实例.
+    /// </summary>
+    public static IEqualityComparer<T> CreateComparer<TV>(Func<T, TV> keySelector, IEqualityComparer<TV> comparer)
+    {
+        return new CommonEqualityComparer<TV>(keySelector, comparer);
+    }
+
+    /// <summary>
+    /// 共同平等比较器.
+    /// </summary>
+    /// <typeparam name="TV">要比较的类型.</typeparam>
+    private class CommonEqualityComparer<TV> : IEqualityComparer<T>
+    {
+        private readonly IEqualityComparer<TV> _comparer;
+        private readonly Func<T, TV> _keySelector;
+
+        public CommonEqualityComparer(Func<T, TV> keySelector, IEqualityComparer<TV> comparer)
+        {
+            _keySelector = keySelector;
+            _comparer = comparer;
+        }
+
+        public CommonEqualityComparer(Func<T, TV> keySelector)
+            : this(keySelector, EqualityComparer<TV>.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));
+        }
+    }
+}