Avoid wrapping List<int>/Stream<List<int>> response bodies in a CastList/CastStream

CHANGELOG.md

@@ -1,3 +1,9 @@
+## 1.1.1
+
+* Avoid wrapping response bodies that already contained `List<int>` or
+  `Stream<List<int>>` in a `CastList`/`CastStream` to improve
+  performance.
+
 ## 1.1.0
 
 * Change `Request.hijack` return type from `void` to `Never`. This may cause

lib/src/body.dart

@@ -52,9 +52,16 @@ class Body {
         contentLength = encoded.length;
         stream = Stream.fromIterable([encoded]);
       }
+    } else if (body is List<int>) {
+      // Avoid performance overhead from an unnecessary cast.
+      contentLength = body.length;
+      stream = Stream.value(body);
     } else if (body is List) {
       contentLength = body.length;
-      stream = Stream.fromIterable([body.cast()]);
+      stream = Stream.value(body.cast());
+    } else if (body is Stream<List<int>>) {
+      // Avoid performance overhead from an unnecessary cast.
+      stream = body;
     } else if (body is Stream) {
       stream = body.cast();
     } else {

pubspec.yaml

@@ -1,5 +1,5 @@
 name: shelf
-version: 1.1.0
+version: 1.1.1
 description: >-
   A model for web server middleware that encourages composition and easy reuse
 repository: https://github.com/dart-lang/shelf

test/response_test.dart

@@ -4,6 +4,7 @@
 
 import 'dart:async';
 import 'dart:convert';
+import 'dart:typed_data';
 
 import 'package:shelf/shelf.dart' hide Request;
 import 'package:test/test.dart';
@@ -25,6 +26,38 @@ void main() {
     });
   });
 
+  test('supports a Uint8List body without copying', () async {
+    var bytes = Uint8List(10);
+    var response = Response.ok(bytes);
+
+    expect(response.contentLength, 10);
+    expect(await response.read().single, same(bytes));
+  });
+
+  test('supports a List<int> body without copying', () async {
+    var bytes = <int>[1, 2, 3, 4];
+    var response = Response.ok(bytes);
+
+    expect(response.contentLength, 4);
+    expect(await response.read().single, same(bytes));
+  });
+
+  test('supports a Stream<List<int>> body without copying', () async {
+    var bytes = Stream.value(<int>[1, 2, 3, 4]);
+    var response = Response.ok(bytes);
+
+    expect(response.read(), same(bytes));
+  });
+
+  test('Copies a dynamic list of int elements', () async {
+    var bytes = <dynamic>[1, 2, 3, 4];
+    var response = Response.ok(bytes);
+
+    expect(response.contentLength, 4);
+    expect(await response.read().single,
+        isA<List<int>>().having((values) => values, 'values', [1, 2, 3, 4]));
+  });
+
   group('new Response.internalServerError without a body', () {
     test('sets the body to "Internal Server Error"', () {
       var response = Response.internalServerError();