定长有序列表类

Falcon.SugarApi/FixedLengthStortedList.cs

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+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Falcon.SugarApi
+{
+    /// <summary>
+    /// 固定长度，有序列表
+    /// </summary>
+    public class FixedLengthStortedList<T>:IEnumerable<T>, ICollection<T>
+    {
+        /// <summary>
+        /// 数据列表
+        /// </summary>
+        public List<T> List { get; private set; }
+        /// <summary>
+        /// 长度
+        /// </summary>
+        public int Length { get; set; }
+
+        int ICollection<T>.Count => (this.List as ICollection<T>).Count;
+
+        bool ICollection<T>.IsReadOnly => (this.List as ICollection<T>).IsReadOnly;
+
+        /// <summary>
+        /// 通过提供长度初始化列表
+        /// </summary>
+        /// <param name="length"></param>
+        public FixedLengthStortedList(int length) {
+            this.List ??= new List<T>(length);
+            this.Length = length;
+        }
+
+        IEnumerator<T> IEnumerable<T>.GetEnumerator() {
+            return (this.List as IEnumerable<T>).GetEnumerator();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator() {
+            return (this.List as IEnumerable).GetEnumerator();
+        }
+        private static object _lockObj = new object();
+
+        void ICollection<T>.Add(T item) {
+            lock(_lockObj) {
+                this.List.Add(item);
+                RemoveMoreItems();
+            }
+        }
+
+        /// <summary>
+        /// 增加列表项目
+        /// </summary>
+        /// <param name="items">新添加的项目</param>
+        /// <returns>定长排序列表</returns>
+        public FixedLengthStortedList<T> Add(T[] items) {
+            lock(_lockObj) {
+                this.List.AddRange(items);
+                RemoveMoreItems();
+            }
+            return this;
+        }
+
+        /// <summary>
+        /// 增加列表项目
+        /// </summary>
+        /// <param name="items">新添加的项目</param>
+        /// <returns>定长排序列表</returns>
+        public FixedLengthStortedList<T> Add(IEnumerable<T> items) {
+            return Add(items.ToArray());
+        }
+
+        void ICollection<T>.Clear() => this.List.Clear();
+
+        bool ICollection<T>.Contains(T item) => this.List.Contains(item);
+
+        void ICollection<T>.CopyTo(T[] array,int arrayIndex) => this.List.CopyTo(array,arrayIndex);
+
+        bool ICollection<T>.Remove(T item) => this.List.Remove(item);
+
+        /// <summary>
+        /// 从头部移除多余的元素
+        /// </summary>
+        private void RemoveMoreItems() {
+            while(this.List.Count > this.Length) {
+                this.List.RemoveAt(0);
+            }
+        }
+    }
+}