| // Copyright (c) 2015, 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'; |
| |
| /// Simple delegating wrapper around a [StreamConsumer]. |
| /// |
| /// Subclasses can override individual methods, or use this to expose only the |
| /// [StreamConsumer] methods of a subclass. |
| class DelegatingStreamConsumer<T> implements StreamConsumer<T> { |
| final StreamConsumer _consumer; |
| |
| /// Create a delegating consumer forwarding calls to [consumer]. |
| DelegatingStreamConsumer(StreamConsumer<T> consumer) : _consumer = consumer; |
| |
| DelegatingStreamConsumer._(this._consumer); |
| |
| /// Creates a wrapper that coerces the type of [consumer]. |
| /// |
| /// Unlike [new StreamConsumer], this only requires its argument to be an |
| /// instance of `StreamConsumer`, not `StreamConsumer<T>`. This means that |
| /// calls to [addStream] may throw a [CastError] if the argument type doesn't |
| /// match the reified type of [consumer]. |
| static StreamConsumer<T> typed<T>(StreamConsumer consumer) => |
| consumer is StreamConsumer<T> |
| ? consumer |
| : DelegatingStreamConsumer._(consumer); |
| |
| Future addStream(Stream<T> stream) => _consumer.addStream(stream); |
| |
| Future close() => _consumer.close(); |
| } |