From 686dfeba521308fe962101d1bba1be343a765f33 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christian=20K=C3=B6llner?= <christian.koellner.80@gmail.com>
Date: Mon, 17 Feb 2020 21:23:44 +0100
Subject: [PATCH] Perf. opt.

---
 .../ListOfPrimitivesDeserializer.cs           | 11 ++--
 .../ListOfPrimitivesSerializer.cs             | 50 ++++++++++++-------
 2 files changed, 40 insertions(+), 21 deletions(-)

diff --git a/Capnp.Net.Runtime/ListOfPrimitivesDeserializer.cs b/Capnp.Net.Runtime/ListOfPrimitivesDeserializer.cs
index c2cae63..072d371 100644
--- a/Capnp.Net.Runtime/ListOfPrimitivesDeserializer.cs
+++ b/Capnp.Net.Runtime/ListOfPrimitivesDeserializer.cs
@@ -7,7 +7,7 @@ using System.Text;
 namespace Capnp
 {
     /// <summary>
-    /// ListDeserializer specialization for List(Int*), List(UInt*), List(Float*), and List(Enum).
+    /// ListDeserializer specialization for unmanaged primitive types (including enum).
     /// </summary>
     /// <typeparam name="T">List element type</typeparam>
     public class ListOfPrimitivesDeserializer<T>: ListDeserializer, IReadOnlyList<T>
@@ -84,7 +84,10 @@ namespace Capnp
         /// </summary>
         public override ListKind Kind => _kind;
 
-        ReadOnlySpan<T> Data => MemoryMarshal.Cast<ulong, T>(State.CurrentSegment.Slice(State.Offset)).Slice(0, Count);
+        /// <summary>
+        /// Retrieves the underlying memory span of this object
+        /// </summary>
+        public ReadOnlySpan<T> Span => MemoryMarshal.Cast<ulong, T>(State.CurrentSegment.Slice(State.Offset)).Slice(0, Count);
 
         /// <summary>
         /// Returns the element at given index.
@@ -92,7 +95,7 @@ namespace Capnp
         /// <param name="index">Element index</param>
         /// <returns>Element value</returns>
         /// <exception cref="IndexOutOfRangeException"><paramref name="index"/> is out of range.</exception>
-        public T this[int index] => Data[index];
+        public T this[int index] => Span[index];
 
         ListOfPrimitivesDeserializer<U> PrimitiveCast<U>() where U: unmanaged
         {
@@ -202,7 +205,7 @@ namespace Capnp
         /// <exception cref="NotSupportedException">Element size is different from 1 byte.</exception>
         public override string CastText()
         {
-            var utf8Bytes = PrimitiveCast<byte>().Data;
+            var utf8Bytes = PrimitiveCast<byte>().Span;
             if (utf8Bytes.Length == 0) return string.Empty;
             var utf8GytesNoZterm = utf8Bytes.Slice(0, utf8Bytes.Length - 1);
             return Encoding.UTF8.GetString(utf8GytesNoZterm.ToArray());
diff --git a/Capnp.Net.Runtime/ListOfPrimitivesSerializer.cs b/Capnp.Net.Runtime/ListOfPrimitivesSerializer.cs
index d901ad7..a67df9a 100644
--- a/Capnp.Net.Runtime/ListOfPrimitivesSerializer.cs
+++ b/Capnp.Net.Runtime/ListOfPrimitivesSerializer.cs
@@ -6,13 +6,13 @@ using System.Runtime.InteropServices;
 namespace Capnp
 {
     /// <summary>
-    /// SerializerState specialization for List(Int*), List(UInt*), List(Float*), and List(Enum).
+    /// SerializerState specialization for unmanaged primitive types (including enum).
     /// </summary>
     /// <typeparam name="T">List element type, must be primitive. Static constructor will throw if the type does not work.</typeparam>
     public class ListOfPrimitivesSerializer<T> :
         SerializerState,
         IReadOnlyList<T>
-        where T : struct
+        where T : unmanaged
     {
         static readonly int ElementSize;
 
@@ -28,7 +28,10 @@ namespace Capnp
             }
         }
 
-        Span<T> Data => MemoryMarshal.Cast<ulong, T>(RawData);
+        /// <summary>
+        /// Retrieves the underlying memory span of the represented items.
+        /// </summary>
+        public Span<T> Span => MemoryMarshal.Cast<ulong, T>(RawData);
 
         /// <summary>
         /// Gets or sets the value at given index.
@@ -37,8 +40,8 @@ namespace Capnp
         /// <returns>Element value</returns>
         public T this[int index]
         {
-            get => Data[index];
-            set => Data[index] = value;
+            get => Span[index];
+            set => Span[index] = value;
         }
 
         /// <summary>
@@ -78,25 +81,38 @@ namespace Capnp
 
             Init(items.Count);
 
-            if (items is T[] array)
+            switch (items)
             {
-                array.CopyTo(Data);
-            }
-            else
-            {
-                for (int i = 0; i < items.Count; i++)
-                {
-                    this[i] = items[i];
-                }
+                case T[] array:
+                    array.CopyTo(Span);
+                    break;
+
+                case ArraySegment<T> segment:
+                    segment.AsSpan().CopyTo(Span);
+                    break;
+
+                case ListOfPrimitivesDeserializer<T> deser:
+                    deser.Span.CopyTo(Span);
+                    break;
+
+                case ListOfPrimitivesSerializer<T> ser:
+                    ser.Span.CopyTo(Span);
+                    break;
+
+                default:
+                    for (int i = 0; i < items.Count; i++)
+                    {
+                        this[i] = items[i];
+                    }
+                    break;
             }
         }
 
         /// <summary>
         /// Implements <see cref="IEnumerable{T}"/>.
         /// </summary>
-        /// <returns></returns>
-        public IEnumerator<T> GetEnumerator() => (IEnumerator<T>)Data.ToArray().GetEnumerator();
+        public IEnumerator<T> GetEnumerator() => (IEnumerator<T>)Span.ToArray().GetEnumerator();
 
-        IEnumerator IEnumerable.GetEnumerator() => Data.ToArray().GetEnumerator();
+        IEnumerator IEnumerable.GetEnumerator() => Span.ToArray().GetEnumerator();
     }
 }
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