add areas cache

Atomx.Utils/Extension/TreeExtension.cs

@@ -0,0 +1,36 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Atomx.Utils.Extension
+{
+    public static class TreeExtension
+    {
+        public static List<T> ToTree<T>(this List<T> list, Func<T, string> getId, Func<T, string> getParentId, Action<T, List<T>> setChildren, string rootParentId = "0")
+        {
+            var lookup = new Dictionary<string, T>();
+            var result = new List<T>();
+            foreach (var item in list)
+            {
+                var id = getId(item);
+                lookup[id] = item;
+            }
+            foreach (var item in list)
+            {
+                var parentId = getParentId(item);
+                if (parentId == rootParentId || !lookup.ContainsKey(parentId))
+                {
+                    result.Add(item);
+                }
+                else
+                {
+                    var parent = lookup[parentId];
+                    var children = new List<T>();
+                    setChildren(parent, children);
+                    children.Add(item);
+                }
+            }
+            return result;
+        }
+    }
+}