Move _StreamSinkImpl from dart:io to dart:async as StreamSinkAdapter.

sdk/lib/io/io_sink.dart

Index: sdk/lib/io/io_sink.dart
diff --git a/sdk/lib/io/io_sink.dart b/sdk/lib/io/io_sink.dart
index 0c2752244994d403db9773487ce45177bf22ba35..a41b5ef959205fa7fde847e9903c0875338757bf 100644
--- a/sdk/lib/io/io_sink.dart
+++ b/sdk/lib/io/io_sink.dart
@@ -12,7 +12,7 @@ part of dart.io;
  *
  * When the [IOSink] is bound to a stream (through [addStream]) any call
  * to the [IOSink] will throw a [StateError]. When the [addStream] completes,
- * the [IOSink] will again be open for all calls.
+ * the [IOSink] will again accept all method calls.
  *
  * If data is added to the [IOSink] after the sink is closed, the data will be
  * ignored. Use the [done] future to be notified when the [IOSink] is closed.
@@ -124,138 +124,8 @@ abstract class IOSink implements StreamSink<List<int>>, StringSink {
   Future get done;
 }
 
-class _StreamSinkImpl<T> implements StreamSink<T> {
-  final StreamConsumer<T> _target;
-  Completer _doneCompleter = new Completer();
-  Future _doneFuture;
-  StreamController<T> _controllerInstance;
-  Completer _controllerCompleter;
-  bool _isClosed = false;
-  bool _isBound = false;
-  bool _hasError = false;
 
-  _StreamSinkImpl(this._target) {
-    _doneFuture = _doneCompleter.future;
-  }
-
-  void add(T data) {
-    if (_isClosed) return;
-    _controller.add(data);
-  }
-
-  void addError(error, [StackTrace stackTrace]) =>
-      _controller.addError(error, stackTrace);
-
-  Future addStream(Stream<T> stream) {
-    if (_isBound) {
-      throw new StateError("StreamSink is already bound to a stream");
-    }
-    _isBound = true;
-    if (_hasError) return done;
-    // Wait for any sync operations to complete.
-    Future targetAddStream() {
-      return _target.addStream(stream)
-          .whenComplete(() {
-            _isBound = false;
-          });
-    }
-    if (_controllerInstance == null) return targetAddStream();
-    var future = _controllerCompleter.future;
-    _controllerInstance.close();
-    return future.then((_) => targetAddStream());
-  }
-
-  Future flush() {
-    if (_isBound) {
-      throw new StateError("StreamSink is bound to a stream");
-    }
-    if (_controllerInstance == null) return new Future.value(this);
-    // Adding an empty stream-controller will return a future that will complete
-    // when all data is done.
-    _isBound = true;
-    var future = _controllerCompleter.future;
-    _controllerInstance.close();
-    return future.whenComplete(() {
-          _isBound = false;
-        });
-  }
-
-  Future close() {
-    if (_isBound) {
-      throw new StateError("StreamSink is bound to a stream");
-    }
-    if (!_isClosed) {
-      _isClosed = true;
-      if (_controllerInstance != null) {
-        _controllerInstance.close();
-      } else {
-        _closeTarget();
-      }
-    }
-    return done;
-  }
-
-  void _closeTarget() {
-    _target.close()
-        .then((value) => _completeDone(value: value),
-              onError: (error) => _completeDone(error: error));
-  }
-
-  Future get done => _doneFuture;
-
-  void _completeDone({value, error}) {
-    if (_doneCompleter == null) return;
-    if (error == null) {
-      _doneCompleter.complete(value);
-    } else {
-      _hasError = true;
-      _doneCompleter.completeError(error);
-    }
-    _doneCompleter = null;
-  }
-
-  StreamController<T> get _controller {
-    if (_isBound) {
-      throw new StateError("StreamSink is bound to a stream");
-    }
-    if (_isClosed) {
-      throw new StateError("StreamSink is closed");
-    }
-    if (_controllerInstance == null) {
-      _controllerInstance = new StreamController<T>(sync: true);
-      _controllerCompleter = new Completer();
-      _target.addStream(_controller.stream)
-          .then(
-              (_) {
-                if (_isBound) {
-                  // A new stream takes over - forward values to that stream.
-                  _controllerCompleter.complete(this);
-                  _controllerCompleter = null;
-                  _controllerInstance = null;
-                } else {
-                  // No new stream, .close was called. Close _target.
-                  _closeTarget();
-                }
-              },
-              onError: (error) {
-                if (_isBound) {
-                  // A new stream takes over - forward errors to that stream.
-                  _controllerCompleter.completeError(error);
-                  _controllerCompleter = null;
-                  _controllerInstance = null;
-                } else {
-                  // No new stream. No need to close target, as it have already
-                  // failed.
-                  _completeDone(error: error);
-                }
-              });
-    }
-    return _controllerInstance;
-  }
-}
-
-
-class _IOSinkImpl extends _StreamSinkImpl<List<int>> implements IOSink {
+class _IOSinkImpl extends StreamSinkAdapter<List<int>> implements IOSink {
   Encoding _encoding;
   bool _encodingMutable = true;