Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System/compmod/system/componentmodel/ArraySubsetEnumerator.cs

@@ -0,0 +1,56 @@
+//------------------------------------------------------------------------------
+// <copyright file="ArraySubsetEnumerator.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+namespace System.ComponentModel {        
+
+    using System;
+    using System.Collections;
+    using System.Diagnostics;
+    using System.Security.Permissions;
+
+    [HostProtection(SharedState = true)]
+    internal class ArraySubsetEnumerator : IEnumerator
+    {
+
+        private Array array;
+        private int total;
+        private int current;
+
+        public ArraySubsetEnumerator(Array array, int count) {
+            Debug.Assert(count == 0 || array != null, "if array is null, count should be 0");
+            Debug.Assert(array == null || count <= array.Length, "Trying to enumerate more than the array contains");
+            this.array = array;
+            this.total = count;
+            current = -1;
+        }
+
+        public bool MoveNext() {
+            if (current < total - 1) {
+                current++;
+                return true;
+            }
+            else {
+                return false;
+            }
+        }
+
+        public void Reset() {
+            current = -1;
+        }
+
+        public object Current {
+            get {
+                if (current == -1) {
+                    throw new InvalidOperationException();
+                }
+                else {
+                    return array.GetValue(current);
+                }
+            }
+        }
+    }
+}
+