1 files changed, 55 insertions, 0 deletions
diff --git a/src/mscorlib/src/System/Collections/Generic/KeyValuePair.cs b/src/mscorlib/src/System/Collections/Generic/KeyValuePair.cs
new file mode 100644
index 0000000000..d232e20d8b
--- /dev/null
+++ b/src/mscorlib/src/System/Collections/Generic/KeyValuePair.cs
@@ -0,0 +1,55 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+/*============================================================
+**
+** Interface:  KeyValuePair
+** 
+** 
+**
+**
+** Purpose: Generic key-value pair for dictionary enumerators.
+**
+** 
+===========================================================*/
+namespace System.Collections.Generic {
+    
+    using System;
+    using System.Text;
+
+    // A KeyValuePair holds a key and a value from a dictionary.
+    // It is used by the IEnumerable<T> implementation for both IDictionary<TKey, TValue>
+    // and IReadOnlyDictionary<TKey, TValue>.
+    [Serializable]
+    public struct KeyValuePair<TKey, TValue> {
+        private TKey key;
+        private TValue value;
+
+        public KeyValuePair(TKey key, TValue value) {
+            this.key = key;
+            this.value = value;
+        }
+
+        public TKey Key {
+            get { return key; }
+        }
+
+        public TValue Value {
+            get { return value; }
+        }
+
+        public override string ToString() {
+            StringBuilder s = StringBuilderCache.Acquire();
+            s.Append('[');
+            if( Key != null) {
+                s.Append(Key.ToString());
+            }
+            s.Append(", ");
+            if( Value != null) {
+               s.Append(Value.ToString());
+            }
+            s.Append(']');
+            return StringBuilderCache.GetStringAndRelease(s);
+        }
+    }
+}