71 lines
2.2 KiB
C#
71 lines
2.2 KiB
C#
using JNPF.DependencyInjection;
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namespace JNPF.Common.Security;
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/// <summary>
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/// 比较器辅助类，用于快速创建<see cref="IComparer{T}"/>接口的实例.
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/// </summary>
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/// <example>
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/// var comparer1 = Comparison[Person].CreateComparer(p => p.ID); var comparer2 = Comparison[Person].CreateComparer(p => p.Name); var comparer3 = Comparison[Person].CreateComparer(p => p.Birthday.Year).
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/// </example>
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/// <typeparam name="T">要比较的类型.</typeparam>
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[SuppressSniffer]
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public static class ComparisonHelper<T>
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{
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/// <summary>
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/// 创建指定对比委托<paramref name="keySelector"/>的实例.
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/// </summary>
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public static IComparer<T> CreateComparer<TV>(Func<T, TV> keySelector)
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{
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return new CommonComparer<TV>(keySelector);
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}
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/// <summary>
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/// 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
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/// </summary>
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public static IComparer<T> CreateComparer<TV>(Func<T, TV> keySelector, IComparer<TV> comparer)
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{
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return new CommonComparer<TV>(keySelector, comparer);
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}
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/// <summary>
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/// 常见的比较器.
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/// </summary>
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/// <typeparam name="TV">要比较的类型.</typeparam>
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private class CommonComparer<TV> : IComparer<T>
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{
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private readonly IComparer<TV> _comparer;
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private readonly Func<T, TV> _keySelector;
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/// <summary>
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/// 构造函数.
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/// </summary>
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/// <param name="keySelector"></param>
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/// <param name="comparer"></param>
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public CommonComparer(Func<T, TV> keySelector, IComparer<TV> comparer)
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{
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_keySelector = keySelector;
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_comparer = comparer;
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}
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/// <summary>
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/// 构造函数.
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/// </summary>
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/// <param name="keySelector"></param>
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public CommonComparer(Func<T, TV> keySelector)
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: this(keySelector, Comparer<TV>.Default)
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{
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}
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/// <summary>
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/// 比较.
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/// </summary>
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/// <param name="x"></param>
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/// <param name="y"></param>
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/// <returns></returns>
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public int Compare(T? x, T? y)
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{
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return _comparer.Compare(_keySelector(x), _keySelector(y));
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}
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}
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} |