From 77ab2c12d2b865ef99dae60dc8107984ae0fcea3 Mon Sep 17 00:00:00 2001
From: Justin Van Patten <jvp@justinvp.com>
Date: Wed, 7 Jan 2015 22:35:51 -0800
Subject: [PATCH] Implement IList<string> and IReadOnlyList<string>

---
 .../Specialized/StringCollection.cs           | 50 +++++++++++++++----
 1 file changed, 40 insertions(+), 10 deletions(-)

diff --git a/src/System.Collections.Specialized/src/System/Collections/Specialized/StringCollection.cs b/src/System.Collections.Specialized/src/System/Collections/Specialized/StringCollection.cs
index f1ee10745af1..1716e305de3d 100644
--- a/src/System.Collections.Specialized/src/System/Collections/Specialized/StringCollection.cs
+++ b/src/System.Collections.Specialized/src/System/Collections/Specialized/StringCollection.cs
@@ -3,13 +3,14 @@
 
 using System.Diagnostics;
 using System.Collections;
+using System.Collections.Generic;
 
 namespace System.Collections.Specialized
 {
     /// <devdoc>
     ///    <para>Represents a collection of strings.</para>
     /// </devdoc>
-    public class StringCollection : IList
+    public class StringCollection : IList<string>, IReadOnlyList<string>, IList
     {
         private readonly ArrayList _data = new ArrayList();
 
@@ -56,7 +57,6 @@ bool IList.IsFixedSize
             }
         }
 
-
         /// <devdoc>
         ///    <para>Adds a string with the specified value to the 
         ///    <see cref='System.Collections.Specialized.StringCollection'/> .</para>
@@ -112,7 +112,8 @@ public void CopyTo(string[] array, int index)
         /// </devdoc>
         public StringEnumerator GetEnumerator()
         {
-            return new StringEnumerator(this);
+            IEnumerator enumerator = _data.GetEnumerator();
+            return new StringEnumerator(enumerator);
         }
 
         /// <devdoc>
@@ -207,7 +208,6 @@ bool IList.Contains(object value)
             return Contains((string)value);
         }
 
-
         int IList.IndexOf(object value)
         {
             return IndexOf((string)value);
@@ -232,17 +232,38 @@ IEnumerator IEnumerable.GetEnumerator()
         {
             return _data.GetEnumerator();
         }
+
+        void ICollection<string>.Add(string item)
+        {
+            Add(item);
+        }
+
+        bool ICollection<string>.Remove(string item)
+        {
+            int index = IndexOf(item);
+            if (index >= 0)
+            {
+                RemoveAt(index);
+                return true;
+            }
+
+            return false;
+        }
+
+        IEnumerator<string> IEnumerable<string>.GetEnumerator()
+        {
+            return GetEnumerator();
+        }
     }
 
-    public class StringEnumerator
+    public class StringEnumerator : IEnumerator<string>
     {
-        private System.Collections.IEnumerator _baseEnumerator;
-        private System.Collections.IEnumerable _temp;
+        private readonly IEnumerator _baseEnumerator;
 
-        internal StringEnumerator(StringCollection mappings)
+        internal StringEnumerator(IEnumerator enumerator)
         {
-            _temp = (IEnumerable)(mappings);
-            _baseEnumerator = _temp.GetEnumerator();
+            Debug.Assert(enumerator != null, "enumerator must not be null.");
+            _baseEnumerator = enumerator;
         }
 
         public string Current
@@ -262,6 +283,15 @@ public void Reset()
         {
             _baseEnumerator.Reset();
         }
+
+        object IEnumerator.Current
+        {
+            get { return _baseEnumerator.Current; }
+        }
+
+        void IDisposable.Dispose()
+        {
+        }
     }
 }