Code tweaks to MemoryStream initialization

Author: Sergio0694

Microsoft.Toolkit.HighPerformance/Extensions/IMemoryOwnerExtensions.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System;
 using System.Buffers;
 using System.Diagnostics.Contracts;
 using System.IO;
@@ -24,6 +25,7 @@ public static class IMemoryOwnerExtensions
         /// The caller does not need to track the lifetime of the input <see cref="IMemoryOwner{T}"/> of <see cref="byte"/>
         /// instance, as the returned <see cref="Stream"/> will take care of disposing that buffer when it is closed.
         /// </remarks>
+        /// <exception cref="ArgumentException">Thrown when <paramref name="memoryOwner"/> has an invalid data store.</exception>
         [Pure]
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Stream AsStream(this IMemoryOwner<byte> memoryOwner)

Microsoft.Toolkit.HighPerformance/Extensions/MemoryExtensions.cs

@@ -26,6 +26,7 @@ public static class MemoryExtensions
         /// In particular, the caller must ensure that the target buffer is not disposed as long
         /// as the returned <see cref="Stream"/> is in use, to avoid unexpected issues.
         /// </remarks>
+        /// <exception cref="ArgumentException">Thrown when <paramref name="memory"/> has an invalid data store.</exception>
         [Pure]
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Stream AsStream(this Memory<byte> memory)

Microsoft.Toolkit.HighPerformance/Extensions/ReadOnlyMemoryExtensions.cs

@@ -25,6 +25,7 @@ public static class ReadOnlyMemoryExtensions
         /// In particular, the caller must ensure that the target buffer is not disposed as long
         /// as the returned <see cref="Stream"/> is in use, to avoid unexpected issues.
         /// </remarks>
+        /// <exception cref="ArgumentException">Thrown when <paramref name="memory"/> has an invalid data store.</exception>
         [Pure]
         public static Stream AsStream(this ReadOnlyMemory<byte> memory)
         {

Microsoft.Toolkit.HighPerformance/Streams/MemoryStream.cs

@@ -21,9 +21,16 @@ internal static partial class MemoryStream
         /// <param name="memory">The input <see cref="ReadOnlyMemory{T}"/> instance.</param>
         /// <param name="isReadOnly">Indicates whether or not <paramref name="memory"/> can be written to.</param>
         /// <returns>A <see cref="Stream"/> wrapping the underlying data for <paramref name="memory"/>.</returns>
+        /// <exception cref="ArgumentException">Thrown when <paramref name="memory"/> has an invalid data store.</exception>
         [Pure]
         public static Stream Create(ReadOnlyMemory<byte> memory, bool isReadOnly)
         {
+            if (memory.IsEmpty)
+            {
+                // Return an empty stream if the memory was empty
+                return new MemoryStream<ArrayOwner>(ArrayOwner.Empty, isReadOnly);
+            }
+
             if (MemoryMarshal.TryGetArray(memory, out ArraySegment<byte> segment))
             {
                 var arraySpanSource = new ArrayOwner(segment.Array!, segment.Offset, segment.Count);
@@ -38,20 +45,26 @@ public static Stream Create(ReadOnlyMemory<byte> memory, bool isReadOnly)
                 return new MemoryStream<MemoryManagerOwner>(memoryManagerSpanSource, isReadOnly);
             }
 
-            // Return an empty stream if the memory was empty
-            return new MemoryStream<ArrayOwner>(ArrayOwner.Empty, isReadOnly);
+            return ThrowNotSupportedExceptionForInvalidMemory();
         }
 
         /// <summary>
         /// Creates a new <see cref="Stream"/> from the input <see cref="IMemoryOwner{T}"/> of <see cref="byte"/> instance.
         /// </summary>
         /// <param name="memoryOwner">The input <see cref="IMemoryOwner{T}"/> instance.</param>
         /// <returns>A <see cref="Stream"/> wrapping the underlying data for <paramref name="memoryOwner"/>.</returns>
+        /// <exception cref="ArgumentException">Thrown when <paramref name="memoryOwner"/> has an invalid data store.</exception>
         [Pure]
         public static Stream Create(IMemoryOwner<byte> memoryOwner)
         {
             Memory<byte> memory = memoryOwner.Memory;
 
+            if (memory.IsEmpty)
+            {
+                // Return an empty stream if the memory was empty
+                return new IMemoryOwnerStream<ArrayOwner>(ArrayOwner.Empty, memoryOwner);
+            }
+
             if (MemoryMarshal.TryGetArray(memory, out ArraySegment<byte> segment))
             {
                 var arraySpanSource = new ArrayOwner(segment.Array!, segment.Offset, segment.Count);
@@ -66,8 +79,17 @@ public static Stream Create(IMemoryOwner<byte> memoryOwner)
                 return new IMemoryOwnerStream<MemoryManagerOwner>(memoryManagerSpanSource, memoryOwner);
             }
 
-            // Return an empty stream if the memory was empty
-            return new IMemoryOwnerStream<ArrayOwner>(ArrayOwner.Empty, memoryOwner);
+            return ThrowNotSupportedExceptionForInvalidMemory();
+        }
+
+        /// <summary>
+        /// Throws a <see cref="ArgumentException"/> when a given <see cref="Memory{T}"/>
+        /// or <see cref="IMemoryOwner{T}"/> instance has an unsupported backing store.
+        /// </summary>
+        /// <returns>Nothing, this method always throws.</returns>
+        private static Stream ThrowNotSupportedExceptionForInvalidMemory()
+        {
+            throw new ArgumentException("The input instance doesn't have a valid underlying data store.");
         }
     }
 }