Index: lib/src/stream_channel_transformer.dart |
diff --git a/lib/src/stream_channel_transformer.dart b/lib/src/stream_channel_transformer.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 'dart:convert'; |
+ |
+import 'package:async/async.dart'; |
+ |
+import '../stream_channel.dart'; |
+ |
+/// A [StreamChannelTransformer] transforms the events being passed to and |
+/// emitted by a [StreamChannel]. |
+/// |
+/// This works on the same principle as [StreamTransformer] and |
+/// [StreamSinkTransformer]. Each transformer defines a [bind] method that takes |
+/// in the original [StreamChannel] and returns the transformed version. |
+/// |
+/// Transformers must be able to have `bind` called multiple times. |
+class StreamChannelTransformer<S, T> { |
+ /// The transformer to use on the channel's stream. |
+ final StreamTransformer _streamTransformer; |
+ |
+ /// The transformer to use on the channel's sink. |
+ final StreamSinkTransformer _sinkTransformer; |
+ |
+ /// Creates a [StreamChannelTransformer] from existing stream and sink |
+ /// transformers. |
+ const StreamChannelTransformer( |
+ this._streamTransformer, this._sinkTransformer); |
+ |
+ /// Creates a [StreamChannelTransformer] from a codec's encoder and decoder. |
+ /// |
+ /// All input to the inner channel's sink is encoded using [Codec.encoder], |
+ /// and all output from its stream is decoded using [Codec.decoder]. |
+ StreamChannelTransformer.fromCodec(Codec<S, T> codec) |
+ : this( |
+ codec.decoder, |
+ new StreamSinkTransformer.fromStreamTransformer(codec.encoder)); |
+ |
+ /// Transforms the events sent to and emitted by [channel]. |
+ /// |
+ /// Creates a new channel. When events are passed to the returned channel's |
+ /// sink, the transformer will transform them and pass the transformed |
+ /// versions to `channel.sink`. When events are emitted from the |
+ /// `channel.straem`, the transformer will transform them and pass the |
+ /// transformed versions to the returned channel's stream. |
+ StreamChannel<S> bind(StreamChannel<T> channel) => |
+ new StreamChannel<S>( |
+ channel.stream.transform(_streamTransformer), |
+ _sinkTransformer.bind(channel.sink)); |
+} |