From 727c0dc1fae6c7b72f59fb29f47a52f133618461 Mon Sep 17 00:00:00 2001
From: Jean-Rémy Bancel <dev@bancel.me>
Date: Wed, 12 Jul 2017 00:25:30 -0700
Subject: C#: Implement IReadOnlyDictionary<K,V> in MapField<K,V>

---
 .../src/Google.Protobuf.Test/Collections/MapFieldTest.cs | 16 ++++++++++++++++
 csharp/src/Google.Protobuf/Collections/MapField.cs       | 11 +++++++++++
 2 files changed, 27 insertions(+)

(limited to 'csharp/src')

diff --git a/csharp/src/Google.Protobuf.Test/Collections/MapFieldTest.cs b/csharp/src/Google.Protobuf.Test/Collections/MapFieldTest.cs
index 9d3d69af..68b4de45 100644
--- a/csharp/src/Google.Protobuf.Test/Collections/MapFieldTest.cs
+++ b/csharp/src/Google.Protobuf.Test/Collections/MapFieldTest.cs
@@ -540,6 +540,22 @@ namespace Google.Protobuf.Collections
             Assert.Throws<ArgumentException>(() => map.ToString());
         }
 
+#if !NET35
+        [Test]
+        public void IDictionaryKeys_Equals_IReadOnlyDictionaryKeys()
+        {
+            var map = new MapField<string, string> { { "foo", "bar" }, { "x", "y" } };
+            CollectionAssert.AreEquivalent(((IDictionary<string, string>)map).Keys, ((IReadOnlyDictionary<string, string>)map).Keys);
+        }
+
+        [Test]
+        public void IDictionaryValues_Equals_IReadOnlyDictionaryValues()
+        {
+            var map = new MapField<string, string> { { "foo", "bar" }, { "x", "y" } };
+            CollectionAssert.AreEquivalent(((IDictionary<string, string>)map).Values, ((IReadOnlyDictionary<string, string>)map).Values);
+        }
+#endif
+
         private static KeyValuePair<TKey, TValue> NewKeyValuePair<TKey, TValue>(TKey key, TValue value)
         {
             return new KeyValuePair<TKey, TValue>(key, value);
diff --git a/csharp/src/Google.Protobuf/Collections/MapField.cs b/csharp/src/Google.Protobuf/Collections/MapField.cs
index ef5651c9..8dac8e30 100644
--- a/csharp/src/Google.Protobuf/Collections/MapField.cs
+++ b/csharp/src/Google.Protobuf/Collections/MapField.cs
@@ -67,6 +67,9 @@ namespace Google.Protobuf.Collections
     /// </para>
     /// </remarks>
     public sealed class MapField<TKey, TValue> : IDeepCloneable<MapField<TKey, TValue>>, IDictionary<TKey, TValue>, IEquatable<MapField<TKey, TValue>>, IDictionary
+#if !NET35
+        , IReadOnlyDictionary<TKey, TValue>
+#endif
     {
         // TODO: Don't create the map/list until we have an entry. (Assume many maps will be empty.)
         private readonly Dictionary<TKey, LinkedListNode<KeyValuePair<TKey, TValue>>> map =
@@ -548,6 +551,14 @@ namespace Google.Protobuf.Collections
         }
         #endregion
 
+        #region IReadOnlyDictionary explicit interface implementation
+#if !NET35
+        IEnumerable<TKey> IReadOnlyDictionary<TKey, TValue>.Keys => Keys;
+
+        IEnumerable<TValue> IReadOnlyDictionary<TKey, TValue>.Values => Values;
+#endif
+        #endregion
+
         private class DictionaryEnumerator : IDictionaryEnumerator
         {
             private readonly IEnumerator<KeyValuePair<TKey, TValue>> enumerator;
-- 
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