Several performance tweaks

- Removed default value assingment when default is equal to default(T)
- Added Benchmarks for most types and repeated/packed arrays
- Left PopsicleList's list fields uninitialized util needed
- Changed CodedInputStream's repated/packed reader
- Changed Enum writers to simply cast to int
- Changed the WriteEnum to use object rawValue that provides .ToString() if needed
- Should be fully on par with original library for performance, gaining 2x-3x in some cases

2 files changed, 40 insertions, 18 deletions

diff --git a/src/ProtocolBuffers/Collections/IPopsicleList.cs b/src/ProtocolBuffers/Collections/IPopsicleList.cs
index 7f6fd8bc..a1a75815 100644
--- a/src/ProtocolBuffers/Collections/IPopsicleList.cs
+++ b/src/ProtocolBuffers/Collections/IPopsicleList.cs
@@ -47,4 +47,12 @@ namespace Google.ProtocolBuffers.Collections
     {

         void Add(IEnumerable<T> collection);

     }

+

+    /// <summary>

+    /// Used to efficiently cast the elements of enumerations

+    /// </summary>

+    internal interface ICastArray

+    {

+        IEnumerable<TItemType> CastArray<TItemType>();

+    }

 }
\ No newline at end of file
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