1 files changed, 49 insertions, 0 deletions
diff --git a/Rx.NET/System.Reactive.Linq/Reactive/Internal/ImmutableList.cs b/Rx.NET/System.Reactive.Linq/Reactive/Internal/ImmutableList.cs
new file mode 100644
index 0000000..5866778
--- /dev/null
+++ b/Rx.NET/System.Reactive.Linq/Reactive/Internal/ImmutableList.cs
@@ -0,0 +1,49 @@
+namespace System.Reactive
+{
+    class ImmutableList<T>
+    {
+        T[] data;
+
+        public ImmutableList()
+        {
+            data = new T[0];
+        }
+
+        public ImmutableList(T[] data)
+        {
+            this.data = data;
+        }
+
+        public ImmutableList<T> Add(T value)
+        {
+            var newData = new T[data.Length + 1];
+            Array.Copy(data, newData, data.Length);
+            newData[data.Length] = value;
+            return new ImmutableList<T>(newData);
+        }
+
+        public ImmutableList<T> Remove(T value)
+        {
+            var i = IndexOf(value);
+            if (i < 0)
+                return this;
+            var newData = new T[data.Length - 1];
+            Array.Copy(data, 0, newData, 0, i);
+            Array.Copy(data, i + 1, newData, i, data.Length - i - 1);
+            return new ImmutableList<T>(newData);
+        }
+
+        public int IndexOf(T value)
+        {
+            for (var i = 0; i < data.Length; ++i)
+                if (data[i].Equals(value))
+                    return i;
+            return -1;
+        }
+
+        public T[] Data
+        {
+            get { return data; }
+        }
+    }
+}