Expose extension methods to wrap and unwrap adapters

samples/CoreApp/SessionExampleExtensions.cs

@@ -54,7 +54,7 @@ static void SetValue(HttpContext context, byte[] data)
 
         builder.MapGet("/count", (HttpContextCore ctx) =>
         {
-            var context = (HttpContext)ctx;
+            var context = ctx.AsSystemWeb();
 
             if (context.Session!["callCount"] is not int count)
             {
@@ -69,7 +69,7 @@ static void SetValue(HttpContext context, byte[] data)
 
         builder.MapGet("/item", (HttpContextCore ctx) =>
         {
-            var context = (HttpContext)ctx;
+            var context = ctx.AsSystemWeb();
 
             var result = context.Session!["item"];
             context.Session!["item"] = default(int);

src/Microsoft.AspNetCore.SystemWebAdapters.CoreServices/Features/HttpApplicationFeature.cs

@@ -41,7 +41,7 @@ public HttpApplicationFeature(HttpContextCore context, IHttpResponseEndFeature p
     private HttpApplication InitializeApplication(HttpContextCore context)
     {
         var app = _pool.Get();
-        app.Context = context;
+        app.Context = context.AsSystemWeb();
         _contextOrApplication = app;
         return app;
     }

src/Microsoft.AspNetCore.SystemWebAdapters.CoreServices/SessionEventsMiddleware.cs

@@ -19,7 +19,7 @@ public SessionEventsMiddleware(RequestDelegate next)
     public async Task InvokeAsync(HttpContextCore context)
     {
         var app = context.Features.GetRequired<IHttpApplicationFeature>();
-        var session = context.GetAdapter().Session;
+        var session = context.AsSystemWeb().Session;
 
         if (session is { IsNewSession: true })
         {

src/Microsoft.AspNetCore.SystemWebAdapters.CoreServices/SetDefaultResponseHeadersMiddleware.cs

@@ -22,7 +22,7 @@ public Task InvokeAsync(HttpContext context)
             var context = (HttpContext)state;
 
             WriteDefaultContentType(context);
-            context.Response.GetAdapter().Cache.UpdateHeaders();
+            context.Response.AsSystemWeb().Cache.UpdateHeaders();
 
             return Task.CompletedTask;
         }, context);

src/Microsoft.AspNetCore.SystemWebAdapters/FeatureCollectionExtensions.cs

@@ -0,0 +1,20 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using Microsoft.AspNetCore.Http.Features;
+
+namespace Microsoft.AspNetCore.SystemWebAdapters;
+
+internal static class FeatureCollectionExtensions
+{
+    internal static TFeature GetRequired<TFeature>(this IFeatureCollection features)
+    {
+        if (features.Get<TFeature>() is TFeature feature)
+        {
+            return feature;
+        }
+
+        throw new InvalidOperationException($"Feature {typeof(TFeature)} is not available");
+    }
+}

src/Microsoft.AspNetCore.SystemWebAdapters/Generated/ExcludedApis.txt

@@ -12,6 +12,7 @@ M:System.Web.HttpRequestBase.op_Implicit(Microsoft.AspNetCore.Http.HttpRequest)~
 
 T:Microsoft.AspNetCore.SystemWebAdapters.SessionState.ISessionState
 T:Microsoft.AspNetCore.SystemWebAdapters.SystemWebAdaptersOptions
+T:Microsoft.AspNetCore.SystemWebAdapters.SystemWebAdaptersConversionExtensions
 
 # We manually type forward this only for .NET 4.7.2+
 T:System.Web.SameSiteMode

src/Microsoft.AspNetCore.SystemWebAdapters/HttpCachePolicy.cs

@@ -49,7 +49,7 @@ private void UpdateCacheControl(CacheControlHeaderValue cacheControl)
         cacheControl.NoCache = GetCacheability() == HttpCacheability.NoCache;
     }
 
-    private ResponseHeaders Headers => _context.GetAdapter().Response.TypedHeaders;
+    private ResponseHeaders Headers => _context.AsSystemWeb().Response.TypedHeaders;
 
     public HttpCacheVaryByHeaders VaryByHeaders => _varyByHeaders ??= new();
 

src/Microsoft.AspNetCore.SystemWebAdapters/HttpContext.cs

@@ -12,6 +12,7 @@
 using Microsoft.AspNetCore.Http.Features.Authentication;
 using Microsoft.AspNetCore.SystemWebAdapters;
 using Microsoft.AspNetCore.SystemWebAdapters.Features;
+using Microsoft.AspNetCore.SystemWebAdapters.Internal;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 
@@ -44,7 +45,19 @@ internal HttpContext(HttpContextCore context)
 
     public HttpResponse Response => _response ??= new(_context.Response);
 
-    public IDictionary Items => _items ??= _context.Items.AsNonGeneric();
+    public IDictionary Items
+    {
+        get
+        {
+            if (_items is null)
+            {
+                var items = _context.Items;
+                _items = items is IDictionary d ? d : new NonGenericDictionaryWrapper(items);
+            }
+
+            return _items;
+        }
+    }
 
     public HttpServerUtility Server => _server ??= new(_context);
 
@@ -161,7 +174,7 @@ public ISubscriptionToken DisposeOnPipelineCompleted(IDisposable target)
     }
 
     [return: NotNullIfNotNull(nameof(context))]
-    public static implicit operator HttpContext?(HttpContextCore? context) => context?.GetAdapter();
+    public static implicit operator HttpContext?(HttpContextCore? context) => context?.AsSystemWeb();
 
     [return: NotNullIfNotNull(nameof(context))]
     public static implicit operator HttpContextCore?(HttpContext? context) => context?._context;

src/Microsoft.AspNetCore.SystemWebAdapters/HttpContextBase.cs

@@ -57,7 +57,7 @@ public virtual IPrincipal User
         public virtual object? GetService(Type serviceType) => throw new NotImplementedException();
 
         [return: NotNullIfNotNull(nameof(context))]
-        public static implicit operator HttpContextBase?(HttpContextCore? context) => context?.GetAdapterBase();
+        public static implicit operator HttpContextBase?(HttpContextCore? context) => context?.AsSystemWebBase();
 
         public virtual Caching.Cache Cache => throw new NotImplementedException();
 

src/Microsoft.AspNetCore.SystemWebAdapters/HttpCookieCollection.cs

@@ -29,10 +29,10 @@ internal HttpCookieCollection(IRequestCookieCollection cookies)
 
     internal HttpCookieCollection(HttpResponse response)
     {
-        response.UnwrapAdapter().OnStarting(static state =>
+        response.AsAspNetCore().OnStarting(static state =>
         {
             var response = (HttpResponse)state;
-            var headers = response.UnwrapAdapter().Headers;
+            var headers = response.AsAspNetCore().Headers;
             var isShareable = false;
 
             for (var i = 0; i < response.Cookies.Count; i++)
@@ -54,7 +54,7 @@ internal HttpCookieCollection(HttpResponse response)
             // Additionally, we should not set this header during an SSL request, as certain versions
             // of IE don't handle it properly and simply refuse to render the page. More info:
             // http://blogs.msdn.com/b/ieinternals/archive/2009/10/02/internet-explorer-cannot-download-over-https-when-no-cache.aspx
-            if (!isShareable && !response.UnwrapAdapter().HttpContext.Request.IsHttps && response.TypedHeaders.CacheControl is { Public: true } cacheControl)
+            if (!isShareable && !response.AsAspNetCore().HttpContext.Request.IsHttps && response.TypedHeaders.CacheControl is { Public: true } cacheControl)
             {
                 cacheControl.NoCache = true;
                 cacheControl.NoCacheHeaders.Add(HeaderNames.SetCookie);

src/Microsoft.AspNetCore.SystemWebAdapters/HttpRequest.cs

@@ -290,7 +290,7 @@ private static void WriteTo(Stream source, Stream destination)
         public void Abort() => _request.HttpContext.Abort();
 
         [return: NotNullIfNotNull(nameof(request))]
-        public static implicit operator HttpRequest?(HttpRequestCore? request) => request.GetAdapter();
+        public static implicit operator HttpRequest?(HttpRequestCore? request) => request?.AsSystemWeb();
 
         [return: NotNullIfNotNull(nameof(request))]
         public static implicit operator HttpRequestCore?(HttpRequest? request) => request?._request;

src/Microsoft.AspNetCore.SystemWebAdapters/HttpRequestBase.cs

@@ -93,6 +93,6 @@ public virtual string? ContentType
         public virtual void Abort() => throw new NotImplementedException();
 
         [return: NotNullIfNotNull(nameof(request))]
-        public static implicit operator HttpRequestBase?(HttpRequestCore? request) => request?.GetAdapterBase();
+        public static implicit operator HttpRequestBase?(HttpRequestCore? request) => request?.HttpContext.AsSystemWebBase().Request;
     }
 }

src/Microsoft.AspNetCore.SystemWebAdapters/HttpResponse.cs

@@ -294,7 +294,7 @@ public void TransmitFile(string filename, long offset, long length)
             => _response.SendFileAsync(filename, offset, length >= 0 ? length : null).GetAwaiter().GetResult();
 
         [return: NotNullIfNotNull(nameof(response))]
-        public static implicit operator HttpResponse?(HttpResponseCore? response) => response?.GetAdapter();
+        public static implicit operator HttpResponse?(HttpResponseCore? response) => response?.AsSystemWeb();
 
         [return: NotNullIfNotNull(nameof(response))]
         public static implicit operator HttpResponseCore?(HttpResponse? response) => response?._response;

src/Microsoft.AspNetCore.SystemWebAdapters/HttpResponseBase.cs

@@ -130,6 +130,6 @@ public virtual Stream Filter
         public virtual void TransmitFile(string filename, long offset, long length) => throw new NotImplementedException();
 
         [return: NotNullIfNotNull(nameof(response))]
-        public static implicit operator HttpResponseBase?(HttpResponseCore? response) => response?.GetAdapterBase();
+        public static implicit operator HttpResponseBase?(HttpResponseCore? response) => response?.HttpContext.AsSystemWebBase().Response;
     }
 }

src/Microsoft.AspNetCore.SystemWebAdapters/HttpServerUtility.cs

@@ -27,9 +27,9 @@ internal HttpServerUtility(HttpContextCore context)
     public string MapPath(string? path)
         => _context.RequestServices.GetRequiredService<IMapPathUtility>().MapPath(_context.Request.Path, path);
 
-    public Exception? GetLastError() => _context.GetAdapter().Error;
+    public Exception? GetLastError() => _context.AsSystemWeb().Error;
 
-    public void ClearError() => _context.GetAdapter().ClearError();
+    public void ClearError() => _context.AsSystemWeb().ClearError();
 
     /// <summary>
     /// This method is similar to <see cref="WebEncoders.Base64UrlDecode(string)"/> but handles the trailing character that <see cref="UrlTokenEncode(byte[])"/>
@@ -113,7 +113,7 @@ public static string UrlTokenEncode(byte[] input)
     public void Transfer(string path, bool preserveForm)
     {
         _context.Features.GetRequired<ITransferRequestFeature>().Transfer(path, preserveForm);
-        _context.Response.GetAdapter().End();
+        _context.Response.AsSystemWeb().End();
     }
 
     [Obsolete(Constants.TransferRequest.Message, DiagnosticId = Constants.TransferRequest.DiagnosticId)]

src/Microsoft.AspNetCore.SystemWebAdapters/Internal/NonGenericDictionaryWrapper.cs

@@ -36,7 +36,7 @@ public ICollection Keys
             {
                 if (_keys is null)
                 {
-                    _keys = _original.Keys.AsNonGeneric();
+                    _keys = AsNonGeneric(_original.Keys);
                 }
 
                 return _keys;
@@ -49,7 +49,7 @@ public ICollection Values
             {
                 if (_values is null)
                 {
-                    _values = _original.Values.AsNonGeneric();
+                    _values = AsNonGeneric(_original.Values);
                 }
 
                 return _values;
@@ -78,6 +78,9 @@ public void CopyTo(Array array, int index)
             }
         }
 
+        private static ICollection AsNonGeneric<T>(ICollection<T> collection)
+            => collection is ICollection c ? c : new NonGenericCollectionWrapper<T>(collection);
+
         public void Remove(object key) => _original.Remove(key);
 
         public IDictionaryEnumerator GetEnumerator() => new DictionaryEnumerator(_original);