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using System; using System.Collections.Generic; using System.Linq; using System.Linq.Expressions; namespace OSS.ETS.OMS.Common { /// <summary> /// 構(gòu)造函數(shù)使用True時(shí)：?jiǎn)蝹€(gè)AND有效，多個(gè)AND有效；單個(gè)OR無(wú)效，多個(gè)OR無(wú)效；混合時(shí)寫(xiě)在AND后的OR有效 /// 構(gòu)造函數(shù)使用False時(shí)：?jiǎn)蝹€(gè)AND無(wú)效，多個(gè)AND無(wú)效；單個(gè)OR有效，多個(gè)OR有效；混合時(shí)寫(xiě)在OR后面的AND有效 /// </summary> /// 創(chuàng)建者：王宇 /// 創(chuàng)建日期：9/1/2014 10:38 AM /// 修改者： /// 修改時(shí)間： /// ------------------------------------ public static class PredicateExtensions { public static Expression<Func<T, bool>> True<T>() { return f => true; } public static Expression<Func<T, bool>> False<T>() { return f => false; } /// <summary> /// lambda表達(dá)式Or /// </summary> /// <typeparam name="T"></typeparam> /// <param name="expression1">The expression1.</param> /// <param name="expression2">The expression2.</param> /// <returns></returns> /// 創(chuàng)建者：王宇 /// 創(chuàng)建日期：9/1/2014 10:32 AM /// 修改者： /// 修改時(shí)間： /// ------------------------------------ public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> expression1, Expression<Func<T, bool>> expression2) { var invokedExpression = Expression.Invoke(expression2, expression1.Parameters); return Expression.Lambda<Func<T, bool>>(Expression.Or(expression1.Body, invokedExpression), expression1.Parameters); } /// <summary> /// lambda表達(dá)式And /// </summary> /// <typeparam name="T"></typeparam> /// <param name="expression1">The expression1.</param> /// <param name="expression2">The expression2.</param> /// <returns></returns> /// 創(chuàng)建者：王宇 /// 創(chuàng)建日期：9/1/2014 10:30 AM /// 修改者： /// 修改時(shí)間： /// ------------------------------------ public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> expression1, Expression<Func<T, bool>> expression2) { var invokedExpression = Expression.Invoke(expression2, expression1.Parameters); return Expression.Lambda<Func<T, bool>>(Expression.And(expression1.Body, invokedExpression), expression1.Parameters); } /// <summary> /// 排除重復(fù)數(shù)據(jù). /// </summary> /// <typeparam name="TSource"></typeparam> /// <typeparam name="TKey"></typeparam> /// <param name="source">集合.</param> /// <param name="keySelector">排重表達(dá)式.</param> /// <returns></returns> /// 創(chuàng)建者：王宇 /// 創(chuàng)建日期：9/1/2014 10:28 AM /// 修改者： /// 修改時(shí)間： /// ------------------------------------ public static IEnumerable<TSource> DistinctBy<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector) { var seenKeys = new HashSet<TKey>(); return source.Where(element => seenKeys.Add(keySelector(element))); } } } |
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來(lái)自： 修行的嘟嘟 > 《軟件開(kāi)發(fā)》
