Moving IRefCountList to its own file.

Ix.NET/Source/System.Interactive/System/Linq/IRefCountList.cs

@@ -0,0 +1,19 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information. 
+
+namespace System.Linq
+{
+    internal interface IRefCountList<T>
+    {
+        void Clear();
+
+        int Count { get; }
+
+        T this[int i] { get; }
+
+        void Add(T item);
+
+        void Done(int index);
+    }
+}

Ix.NET/Source/System.Interactive/System/Linq/Operators/Memoize.cs

@@ -240,22 +240,6 @@ namespace System.Linq
         }
     }
 
-    internal interface IRefCountList<T>
-    {
-        void Clear();
-
-        int Count { get; }
-
-        T this[int i]
-        {
-            get;
-        }
-
-        void Add(T item);
-
-        void Done(int index);
-    }
-
     internal sealed class MaxRefCountList<T> : IRefCountList<T>
     {
         private IList<T> _list = new List<T>();