resolved #196

Author: ymh199478

src/CatLib.Core.Tests/Support/Util/ArrTests.cs

@@ -391,6 +391,18 @@ public void TestFilter()
             Assert.AreEqual(5, result.Length);
         }
 
+        [TestMethod]
+        public void TestFilterExpected()
+        {
+            var result = Arr.Filter(new[] {1, 2, 3, 4, 5, 6, 7, 8, 9, 0}, (i) => i % 2 == 0, false);
+            Assert.AreEqual(1, result[0]);
+            Assert.AreEqual(3, result[1]);
+            Assert.AreEqual(5, result[2]);
+            Assert.AreEqual(7, result[3]);
+            Assert.AreEqual(9, result[4]);
+            Assert.AreEqual(5, result.Length);
+        }
+
         [TestMethod]
         public void TestFilterIEnumerable()
         {

src/CatLib.Core/Support/Util/Arr.cs

@@ -312,13 +312,14 @@ public static T[] Remove<T>(ref T[] source, Predicate<T> predicate)
         }
 
         /// <summary>
-        /// 输入数组中的每个值传给回调函数,如果回调函数返回 true，则把输入数组中的当前值加入结果数组中
+        /// 输入数组中的每个值传给回调函数,如果回调函数和期望值(<paramref name="expected"/>)相等，则把输入数组中的当前值加入结果数组中
         /// </summary>
         /// <typeparam name="T">数组类型</typeparam>
         /// <param name="source">规定数组</param>
         /// <param name="predicate">回调函数</param>
+        /// <param name="expected">回调函数的期望值</param>
         /// <returns>需求数组</returns>
-        public static T[] Filter<T>(T[] source, Predicate<T> predicate)
+        public static T[] Filter<T>(T[] source, Predicate<T> predicate, bool expected = true)
         {
             Guard.Requires<ArgumentNullException>(source != null);
             Guard.Requires<ArgumentNullException>(predicate != null);
@@ -327,7 +328,7 @@ public static T[] Filter<T>(T[] source, Predicate<T> predicate)
             var i = 0;
             foreach (var result in source)
             {
-                if (predicate.Invoke(result))
+                if (predicate.Invoke(result) == expected)
                 {
                     elements[i++] = result;
                 }
@@ -338,21 +339,22 @@ public static T[] Filter<T>(T[] source, Predicate<T> predicate)
         }
 
         /// <summary>
-        /// 将规定迭代器中的每个值传给回调函数,如果回调函数返回 true，则把规定迭代器中的当前值加入结果数组中
+        /// 将规定迭代器中的每个值传给回调函数,如果回调函数和期望值(<paramref name="expected"/>)相等，则把规定迭代器中的当前值加入结果数组中
         /// </summary>
         /// <typeparam name="T">数组类型</typeparam>
         /// <param name="source">规定迭代器</param>
         /// <param name="predicate">回调函数</param>
+        /// <param name="expected">回调函数的期望值</param>
         /// <returns>需求数组</returns>
-        public static T[] Filter<T>(IEnumerable<T> source, Predicate<T> predicate)
+        public static T[] Filter<T>(IEnumerable<T> source, Predicate<T> predicate, bool expected = true)
         {
             Guard.Requires<ArgumentNullException>(source != null);
             Guard.Requires<ArgumentNullException>(predicate != null);
 
             var results = new List<T>();
             foreach (var result in source)
             {
-                if (predicate.Invoke(result))
+                if (predicate.Invoke(result) == expected)
                 {
                     results.Add(result);
                 }