Index: packages/async/lib/src/delegate/stream.dart |
diff --git a/packages/async/lib/src/delegate/stream.dart b/packages/async/lib/src/delegate/stream.dart |
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+++ b/packages/async/lib/src/delegate/stream.dart |
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+// Copyright (c) 2016, the Dart project authors. Please see the AUTHORS file |
+// for details. All rights reserved. Use of this source code is governed by a |
+// BSD-style license that can be found in the LICENSE file. |
+ |
+import 'dart:async'; |
+ |
+import '../typed/stream.dart'; |
+ |
+/// Simple delegating wrapper around a [Stream]. |
+/// |
+/// Subclasses can override individual methods, or use this to expose only the |
+/// [Stream] methods of a subclass. |
+/// |
+/// Note that this is identical to [StreamView] in `dart:async`. It's provided |
+/// under this name for consistency with other `Delegating*` classes. |
+class DelegatingStream<T> extends StreamView<T> { |
+ DelegatingStream(Stream<T> stream) : super(stream); |
+ |
+ /// Creates a wrapper which throws if [stream]'s events aren't instances of |
+ /// `T`. |
+ /// |
+ /// This soundly converts a [Stream] to a `Stream<T>`, regardless of its |
+ /// original generic type, by asserting that its events are instances of `T` |
+ /// whenever they're provided. If they're not, the stream throws a |
+ /// [CastError]. |
+ static Stream<T> typed<T>(Stream stream) => |
+ stream is Stream<T> ? stream : new TypeSafeStream<T>(stream); |
+} |