Address some static analysis and TODOs (#12)

src/Common/Polyfills/System/Collections/Generic/CollectionExtensions.cs

@@ -1,3 +1,5 @@
+using ModelContextProtocol.Utils;
+
 namespace System.Collections.Generic;
 
 internal static class CollectionExtensions
@@ -9,10 +11,7 @@ internal static class CollectionExtensions
 
     public static TValue GetValueOrDefault<TKey, TValue>(this IReadOnlyDictionary<TKey, TValue> dictionary, TKey key, TValue defaultValue)
     {
-        if (dictionary is null)
-        {
-            throw new ArgumentNullException(nameof(dictionary));
-        }
+        Throw.IfNull(dictionary);
 
         return dictionary.TryGetValue(key, out TValue? value) ? value : defaultValue;
     }

src/Common/Polyfills/System/IO/StreamExtensions.cs

@@ -0,0 +1,36 @@
+using ModelContextProtocol.Utils;
+using System.Buffers;
+using System.Runtime.InteropServices;
+
+namespace System.IO;
+
+internal static class StreamExtensions
+{
+    public static ValueTask WriteAsync(this Stream stream, ReadOnlyMemory<byte> buffer, CancellationToken cancellationToken)
+    {
+        Throw.IfNull(stream);
+
+        if (MemoryMarshal.TryGetArray(buffer, out ArraySegment<byte> segment))
+        {
+            return new ValueTask(stream.WriteAsync(segment.Array, segment.Offset, segment.Count, cancellationToken));
+        }
+        else
+        {
+            return WriteAsyncCore(stream, buffer, cancellationToken);
+
+            static async ValueTask WriteAsyncCore(Stream stream, ReadOnlyMemory<byte> buffer, CancellationToken cancellationToken)
+            {
+                byte[] array = ArrayPool<byte>.Shared.Rent(buffer.Length);
+                try
+                {
+                    buffer.Span.CopyTo(array);
+                    await stream.WriteAsync(array, 0, buffer.Length, cancellationToken).ConfigureAwait(false);
+                }
+                finally
+                {
+                    ArrayPool<byte>.Shared.Return(array);
+                }
+            }
+        }
+    }
+}

src/Common/Polyfills/System/IO/TextReaderExtensions.cs

@@ -4,7 +4,21 @@ internal static class TextReaderExtensions
 {
     public static Task<string> ReadLineAsync(this TextReader reader, CancellationToken cancellationToken)
     {
-        _ = cancellationToken;
+        if (cancellationToken.IsCancellationRequested)
+        {
+            return Task.FromCanceled<string>(cancellationToken);
+        }
+
         return reader.ReadLineAsync();
     }
+
+    public static Task<string> ReadToEndAsync(this TextReader reader, CancellationToken cancellationToken)
+    {
+        if (cancellationToken.IsCancellationRequested)
+        {
+            return Task.FromCanceled<string>(cancellationToken);
+        }
+
+        return reader.ReadToEndAsync();
+    }
 }

src/Common/Polyfills/System/IO/TextWriterExtensions.cs

@@ -1,3 +1,4 @@
+using ModelContextProtocol.Utils;
 using System.Runtime.InteropServices;
 
 namespace System.IO;
@@ -6,10 +7,7 @@ internal static class TextWriterExtensions
 {
     public static async Task WriteLineAsync(this TextWriter writer, ReadOnlyMemory<char> value, CancellationToken cancellationToken)
     {
-        if (writer is null)
-        {
-            throw new ArgumentNullException(nameof(writer));
-        }
+        Throw.IfNull(writer);
 
         if (value.IsEmpty)
         {

src/Common/Polyfills/System/Net/Http/HttpClientExtensions.cs

@@ -1,13 +1,12 @@
+using ModelContextProtocol.Utils;
+
 namespace System.Net.Http;
 
 internal static class HttpClientExtensions
 {
     public static async Task<Stream> ReadAsStreamAsync(this HttpContent content, CancellationToken cancellationToken)
     {
-        if (content is null)
-        {
-            throw new ArgumentNullException(nameof(content));
-        }
+        Throw.IfNull(content);
 
         cancellationToken.ThrowIfCancellationRequested();
         return await content.ReadAsStreamAsync();
@@ -15,10 +14,7 @@ internal static class HttpClientExtensions
 
     public static async Task<string> ReadAsStringAsync(this HttpContent content, CancellationToken cancellationToken)
     {
-        if (content is null)
-        {
-            throw new ArgumentNullException(nameof(content));
-        }
+        Throw.IfNull(content);
 
         cancellationToken.ThrowIfCancellationRequested();
         return await content.ReadAsStringAsync();

src/Common/Polyfills/System/Threading/CancellationTokenSourceExtensions.cs

@@ -1,13 +1,12 @@
+using ModelContextProtocol.Utils;
+
 namespace System.Threading.Tasks;
 
 internal static class CancellationTokenSourceExtensions
 {
     public static Task CancelAsync(this CancellationTokenSource cancellationTokenSource)
     {
-        if (cancellationTokenSource is null)
-        {
-            throw new ArgumentNullException(nameof(cancellationTokenSource));
-        }
+        Throw.IfNull(cancellationTokenSource);
 
         cancellationTokenSource.Cancel();
         return Task.CompletedTask;

src/Common/Polyfills/System/Threading/ForceYielding.cs

@@ -0,0 +1,17 @@
+using System.Runtime.CompilerServices;
+
+namespace System.Threading;
+
+/// <summary>
+/// await default(ForceYielding) to provide the same behavior as
+/// await Task.CompletedTask.ConfigureAwait(ConfigureAwaitOptions.ForceYielding).
+/// </summary>
+internal readonly struct ForceYielding : INotifyCompletion, ICriticalNotifyCompletion
+{
+    public ForceYielding GetAwaiter() => this;
+
+    public bool IsCompleted => false;
+    public void OnCompleted(Action continuation) => ThreadPool.QueueUserWorkItem(a => ((Action)a!)(), continuation);
+    public void UnsafeOnCompleted(Action continuation) => ThreadPool.UnsafeQueueUserWorkItem(a => ((Action)a!)(), continuation);
+    public void GetResult() { }
+}

src/Common/Polyfills/System/Threading/Tasks/TaskExtensions.cs

@@ -1,3 +1,5 @@
+using ModelContextProtocol.Utils;
+
 namespace System.Threading.Tasks;
 
 internal static class TaskExtensions
@@ -15,10 +17,7 @@ internal static class TaskExtensions
 
     public static async Task WaitAsync(this Task task, TimeSpan timeout, CancellationToken cancellationToken)
     {
-        if (task is null)
-        {
-            throw new ArgumentNullException(nameof(task));
-        }
+        Throw.IfNull(task);
 
         if (timeout < TimeSpan.Zero && timeout != Timeout.InfiniteTimeSpan)
         {