Update charted to 0.4.8 and roll

packages/async/lib/src/stream_completer.dart

 // 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.
 
-library async.stream_completer;
-
 import "dart:async";
 
 /// A single-subscription [stream] where the contents are provided later.
 ///
 /// It is generally recommended that you never create a `Future<Stream>`
 /// because you can just directly create a stream that doesn't do anything
 /// until it's ready to do so.
 /// This class can be used to create such a stream.
 ///
 /// The [stream] is a normal stream that you can listen to immediately,
 /// but until either [setSourceStream] or [setEmpty] is called,
 /// the stream won't produce any events.
 ///
 /// The same effect can be achieved by using a [StreamController]
 /// and adding the stream using `addStream` when both
 /// the controller's stream is listened to and the source stream is ready.
 /// This class attempts to shortcut some of the overhead when possible.
 /// For example, if the [stream] is only listened to
 /// after the source stream has been set,
 /// the listen is performed directly on the source stream.
 class StreamCompleter<T> {
   /// The stream doing the actual work, is returned by [stream].
-  final _CompleterStream _stream = new _CompleterStream<T>();
+  final _stream = new _CompleterStream<T>();
 
   /// Convert a `Future<Stream>` to a `Stream`.
   ///
   /// This creates a stream using a stream completer,
   /// and sets the source stream to the result of the future when the
   /// future completes.
   ///
   /// If the future completes with an error, the returned stream will
   /// instead contain just that error.
-  static Stream fromFuture(Future<Stream> streamFuture) {
-    var completer = new StreamCompleter();
-    streamFuture.then(completer.setSourceStream,
-                      onError: (e, s) {
-                        completer.setSourceStream(streamFuture.asStream());
-                      });
+  static Stream<T> fromFuture<T>(Future<Stream<T>> streamFuture) {
+    var completer = new StreamCompleter<T>();
+    streamFuture.then(completer.setSourceStream, onError: completer.setError);
     return completer.stream;
   }
 
   /// The stream of this completer.
   ///
   /// This stream is always a single-subscription stream.
   ///
   /// When a source stream is provided, its events will be forwarded to
   /// listeners on this stream.
   ///
@@ skipping 14 matching lines @@
   /// normal subscription, and can be paused or canceled, but it won't
   /// produce any events until a source stream is provided.
   ///
   /// If the `stream` subscription is canceled before a source stream is set,
   /// the source stream will be listened to and immediately canceled again.
   ///
   /// Otherwise, when the source stream is then set,
   /// it is immediately listened to, and its events are forwarded to the
   /// existing subscription.
   ///
-  /// Either [setSourceStream] or [setEmpty] may be called at most once.
-  /// Trying to call either of them again will fail.
+  /// Any one of [setSourceStream], [setEmpty], and [setError] may be called at
+  /// most once. Trying to call any of them again will fail.
   void setSourceStream(Stream<T> sourceStream) {
     if (_stream._isSourceStreamSet) {
       throw new StateError("Source stream already set");
     }
     _stream._setSourceStream(sourceStream);
   }
 
   /// Equivalent to setting an empty stream using [setSourceStream].
   ///
-  /// Either [setSourceStream] or [setEmpty] may be called at most once.
-  /// Trying to call either of them again will fail.
+  /// Any one of [setSourceStream], [setEmpty], and [setError] may be called at
+  /// most once. Trying to call any of them again will fail.
   void setEmpty() {
     if (_stream._isSourceStreamSet) {
       throw new StateError("Source stream already set");
     }
     _stream._setEmpty();
   }
+
+  /// Completes this to a stream that emits [error] and then closes.
+  ///
+  /// This is useful when the process of creating the data for the stream fails.
+  ///
+  /// Any one of [setSourceStream], [setEmpty], and [setError] may be called at
+  /// most once. Trying to call any of them again will fail.
+  void setError(error, [StackTrace stackTrace]) {
+    setSourceStream(new Stream.fromFuture(new Future.error(error, stackTrace)));
+  }
 }
 
 /// Stream completed by [StreamCompleter].
 class _CompleterStream<T> extends Stream<T> {
   /// Controller for an intermediate stream.
   ///
   /// Created if the user listens on this stream before the source stream
   /// is set, or if using [_setEmpty] so there is no source stream.
-  StreamController _controller;
+  StreamController<T> _controller;
 
   /// Source stream for the events provided by this stream.
   ///
   /// Set when the completer sets the source stream using [_setSourceStream]
   /// or [_setEmpty].
-  Stream _sourceStream;
+  Stream<T> _sourceStream;
 
   StreamSubscription<T> listen(onData(T data),
-                               {Function onError,
-                                void onDone(),
-                                bool cancelOnError}) {
+      {Function onError, void onDone(), bool cancelOnError}) {
     if (_controller == null) {
       if (_sourceStream != null && !_sourceStream.isBroadcast) {
         // If the source stream is itself single subscription,
         // just listen to it directly instead of creating a controller.
-        return _sourceStream.listen(onData, onError: onError, onDone: onDone,
-                                    cancelOnError: cancelOnError);
+        return _sourceStream.listen(onData,
+            onError: onError, onDone: onDone, cancelOnError: cancelOnError);
       }
       _createController();
       if (_sourceStream != null) {
         _linkStreamToController();
       }
     }
-    return _controller.stream.listen(onData, onError: onError, onDone: onDone,
-                                     cancelOnError: cancelOnError);
+    return _controller.stream.listen(onData,
+        onError: onError, onDone: onDone, cancelOnError: cancelOnError);
   }
 
   /// Whether a source stream has been set.
   ///
   /// Used to throw an error if trying to set a source stream twice.
   bool get _isSourceStreamSet => _sourceStream != null;
 
   /// Sets the source stream providing the events for this stream.
   ///
   /// If set before the user listens, listen calls will be directed directly
   /// to the source stream. If the user listenes earlier, and intermediate
   /// stream is created using a stream controller, and the source stream is
   /// linked into that stream later.
   void _setSourceStream(Stream<T> sourceStream) {
     assert(_sourceStream == null);
     _sourceStream = sourceStream;
     if (_controller != null) {
       // User has already listened, so provide the data through controller.
       _linkStreamToController();
     }
   }
 
   /// Links source stream to controller when both are available.
   void _linkStreamToController() {
     assert(_controller != null);
     assert(_sourceStream != null);
-    _controller.addStream(_sourceStream, cancelOnError: false)
-               .whenComplete(_controller.close);
+    _controller
+        .addStream(_sourceStream, cancelOnError: false)
+        .whenComplete(_controller.close);
   }
 
   /// Sets an empty source stream.
   ///
   /// Uses [_controller] for the stream, then closes the controller
   /// immediately.
   void _setEmpty() {
     assert(_sourceStream == null);
     if (_controller == null) {
       _createController();
     }
-    _sourceStream = _controller.stream;  // Mark stream as set.
+    _sourceStream = _controller.stream; // Mark stream as set.
     _controller.close();
   }
 
   // Creates the [_controller].
   void _createController() {
     assert(_controller == null);
     _controller = new StreamController<T>(sync: true);
   }
 }