Stop running pub get at gclient sync time and fix build bugs

mojo/public/dart/third_party/barback/lib/src/utils/stream_replayer.dart

+// Copyright (c) 2013, 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 barback.utils.stream_replayer;
+
+import 'dart:async';
+import 'dart:collection';
+
+import '../utils.dart';
+
+/// Records the values and errors that are sent through a stream and allows them
+/// to be replayed arbitrarily many times.
+///
+/// This only listens to the wrapped stream when a replayed stream gets a
+/// listener.
+class StreamReplayer<T> {
+  /// The wrapped stream.
+  final Stream<T> _stream;
+
+  /// Whether or not [this] has started listening to [_stream].
+  bool _isSubscribed = false;
+
+  /// Whether or not [_stream] has been closed.
+  bool _isClosed = false;
+
+  /// The buffer of events or errors that have already been emitted by
+  /// [_stream].
+  ///
+  /// Each element is a [Fallible] that's either a value or an error sent
+  /// through the stream.
+  final _buffer = new Queue<Fallible<T>>();
+
+  /// The controllers that are listening for future events from [_stream].
+  final _controllers = new Set<StreamController<T>>();
+
+  StreamReplayer(this._stream);
+
+  /// Returns a stream that replays the values and errors of the input stream.
+  ///
+  /// This stream is a buffered stream.
+  Stream<T> getReplay() {
+    var controller = new StreamController<T>(onListen: _subscribe);
+
+    for (var eventOrError in _buffer) {
+      if (eventOrError.hasValue) {
+        controller.add(eventOrError.value);
+      } else {
+        controller.addError(eventOrError.error, eventOrError.stackTrace);
+      }
+    }
+    if (_isClosed) {
+      controller.close();
+    } else {
+      _controllers.add(controller);
+    }
+    return controller.stream;
+  }
+
+  /// Subscribe to [_stream] if we haven't yet done so.
+  void _subscribe() {
+    if (_isSubscribed || _isClosed) return;
+    _isSubscribed = true;
+
+    _stream.listen((data) {
+      _buffer.add(new Fallible<T>.withValue(data));
+      for (var controller in _controllers) {
+        controller.add(data);
+      }
+    }, onError: (error, [stackTrace]) {
+      _buffer.add(new Fallible<T>.withError(error, stackTrace));
+      for (var controller in _controllers) {
+        controller.addError(error, stackTrace);
+      }
+    }, onDone: () {
+      _isClosed = true;
+      for (var controller in _controllers) {
+        controller.close();
+      }
+      _controllers.clear();
+    });
+  }
+}