对枚举和数组增加缩减Reduce方法

Falcon.SugarApi.Test/IEnumerableExtendTest.cs

@@ -77,6 +77,36 @@ namespace Falcon.SugarApi.Test
 
 
         }
+
+        [TestMethod("Reduce测试")]
+        public void ReduceTest() {
+            var list = new List<int> { 1, 2, 3, 4 };
+            var sum = list.Reduce((a, b) => a + b, 0);
+            Assert.IsTrue(sum == 10, "对数组求和错误");
+
+            var people = new List<person> {
+                new person{ IsMan=true,age=30 },
+                new person{ IsMan=false,age=40 },
+                new person{ IsMan=true,age=50 },
+                new person{ IsMan=true,age=60 },
+            };
+            var sumage = people.Reduce((a, b) => a + (b.IsMan ? b.age : 0), 0);
+            Assert.IsTrue(sumage == 30 + 50 + 60, "有条件求和错误");
+
+            var men = people.Reduce((a, b) => {
+                if (b.IsMan) {
+                    a.Add(b);
+                }
+                return a;
+            }, new List<person>());
+            foreach (var p in men) {
+                Assert.IsTrue(p.IsMan, "缩减为男性集合错误！");
+            }
+
+            var arr = new string[] { };
+            var initVal = arr.Reduce((a, b) => throw new Exception("空集合不可以调用缩减方法"), "abc");
+            Assert.IsTrue(initVal == "abc", "空集合返回初始值，并且不调用缩减方法。");
+        }
     }
 
     internal class ToDataTableTestModel
@@ -85,5 +115,11 @@ namespace Falcon.SugarApi.Test
         public string Name { get; set; }
     }
 
+    internal class person
+    {
+        public int age { get; set; }
+        public bool IsMan { get; set; }
+    }
+
 }
 

Falcon.SugarApi/IEnumerableExtend.cs

@@ -84,5 +84,25 @@ namespace Falcon.SugarApi
             }
             return dt;
         }
+
+        /// <summary>
+        /// 对枚举进行缩减，并返回缩减后的结果。
+        /// </summary>
+        /// <typeparam name="T">枚举的类型</typeparam>
+        /// <typeparam name="TR">缩减结果类型</typeparam>
+        /// <param name="source">原枚举</param>
+        /// <param name="reduceFunc">缩减方法</param>
+        /// <param name="initialValue">缩减初始值</param>
+        /// <returns>缩减结果</returns>
+        public static TR Reduce<T, TR>(this IEnumerable<T> source, Func<TR, T, TR> reduceFunc, TR initialValue) {
+            if (reduceFunc == null) {
+                throw new ArgumentNullException(nameof(reduceFunc));
+            }
+            var result = initialValue;
+            foreach (var i in source) {
+                result = reduceFunc(result, i);
+            }
+            return result;
+        }
     }
 }