C#在Dictionary中使用枚举作为键

 1  public class EnumComparer<T> : IEqualityComparer<T> where T : struct
 2     {
 3         #region IEqualityComparer<T> 泛型接口实现
 4 
 5         public bool Equals(T first, T second)
 6         {
 7             var firstParam = Expression.Parameter(typeof(T), "first");
 8             var secondParam = Expression.Parameter(typeof(T), "second");
 9             var equalExpression = Expression.Equal(firstParam, secondParam);
10 
11             return Expression.Lambda<Func<T, T, bool>>
12                 (equalExpression, firstParam, secondParam).
13                 Compile().Invoke(first, second);
14         }
15 
16         public int GetHashCode(T instance)
17         {
18             var parameter = Expression.Parameter(typeof(T), "instance");
19             var convertExpression = Expression.Convert(parameter, typeof(int));
20 
21             return Expression.Lambda<Func<T, int>>
22                 (convertExpression, parameter).
23                 Compile().Invoke(instance);
24         }
25 
26         #endregion
27     }