1 files changed, 32 insertions, 18 deletions
diff --git a/src/ProtocolBuffers/Collections/PopsicleList.cs b/src/ProtocolBuffers/Collections/PopsicleList.cs
index 33324303..48161e82 100644
--- a/src/ProtocolBuffers/Collections/PopsicleList.cs
+++ b/src/ProtocolBuffers/Collections/PopsicleList.cs
@@ -40,10 +40,12 @@ namespace Google.ProtocolBuffers.Collections
     /// to be made read-only (with the <see cref="MakeReadOnly" /> method), 
     /// after which any modifying methods throw <see cref="NotSupportedException" />.
     /// </summary>
-    public sealed class PopsicleList<T> : IPopsicleList<T>
+    public sealed class PopsicleList<T> : IPopsicleList<T>, ICastArray
     {
-        private readonly List<T> items = new List<T>();
-        private bool readOnly = false;
+        private static readonly IEnumerable<T> EmptySet = new T[0];
+
+        private List<T> items;
+        private bool readOnly;
 
         /// <summary>
         /// Makes this list read-only ("freezes the popsicle"). From this
@@ -57,7 +59,7 @@ namespace Google.ProtocolBuffers.Collections
 
         public int IndexOf(T item)
         {
-            return items.IndexOf(item);
+            return items == null ? -1 : items.IndexOf(item);
         }
 
         public void Insert(int index, T item)
@@ -74,7 +76,7 @@ namespace Google.ProtocolBuffers.Collections
 
         public T this[int index]
         {
-            get { return items[index]; }
+            get { if (items == null) throw new ArgumentOutOfRangeException(); return items[index]; }
             set
             {
                 ValidateModification();
@@ -96,17 +98,18 @@ namespace Google.ProtocolBuffers.Collections
 
         public bool Contains(T item)
         {
-            return items.Contains(item);
+            return items == null ? false : items.Contains(item);
         }
 
         public void CopyTo(T[] array, int arrayIndex)
         {
-            items.CopyTo(array, arrayIndex);
+            if (items != null)
+                items.CopyTo(array, arrayIndex);
         }
 
         public int Count
         {
-            get { return items.Count; }
+            get { return items == null ? 0 : items.Count; }
         }
 
         public bool IsReadOnly
@@ -120,18 +123,9 @@ namespace Google.ProtocolBuffers.Collections
             return items.Remove(item);
         }
 
-        public void Add(IEnumerable<T> collection)
-        {
-            if (readOnly)
-            {
-                throw new NotSupportedException("List is read-only");
-            }
-            items.AddRange(collection);
-        }
-
         public IEnumerator<T> GetEnumerator()
         {
-            return items.GetEnumerator();
+            return items == null ? EmptySet.GetEnumerator() : items.GetEnumerator();
         }
 
         IEnumerator IEnumerable.GetEnumerator()
@@ -139,12 +133,32 @@ namespace Google.ProtocolBuffers.Collections
             return GetEnumerator();
         }
 
+        public void Add(IEnumerable<T> collection)
+        {
+            if (readOnly)
+            {
+                throw new NotSupportedException("List is read-only");
+            }
+            if (items == null)
+                items = new List<T>();
+            items.AddRange(collection);
+        }
+
         private void ValidateModification()
         {
             if (readOnly)
             {
                 throw new NotSupportedException("List is read-only");
             }
+            if (items == null)
+                items = new List<T>();
+        }
+
+        IEnumerable<TItemType> ICastArray.CastArray<TItemType>()
+        {
+            if (items == null)
+                return new TItemType[0];
+            return (TItemType[])(object)items.ToArray();
         }
     }
 }
 \ No newline at end of file