Add completion support for plugins

pkg/analyzer_plugin/lib/utilities/generator.dart

Index: pkg/analyzer_plugin/lib/utilities/generator.dart
diff --git a/pkg/analyzer_plugin/lib/utilities/generator.dart b/pkg/analyzer_plugin/lib/utilities/generator.dart
new file mode 100644
index 0000000000000000000000000000000000000000..30d27b19beafd541e3791580884d85d2eb9908f2
--- /dev/null
+++ b/pkg/analyzer_plugin/lib/utilities/generator.dart
@@ -0,0 +1,42 @@
+// Copyright (c) 2017, 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 'package:analyzer_plugin/channel/channel.dart';
+import 'package:analyzer_plugin/protocol/protocol.dart';
+import 'package:analyzer_plugin/src/protocol/protocol_internal.dart';
+
+/**
+ * The result produced by a generator.
+ *
+ * Clients may not extend, implement or mix-in this class.
+ */
+class GeneratorResult {
+  /**
+   * The result to be sent to the server, or `null` if there is no response, as
+   * when the generator is generating a notification.
+   */
+  final ResponseResult result;
+
+  /**
+   * The notifications that should be sent to the server. The list will be empty
+   * if there are no notifications.
+   */
+  final List<Notification> notifications;
+
+  /**
+   * Initialize a newly created generator result with the given [result] and
+   * [notifications].
+   */
+  GeneratorResult(this.result, this.notifications);
+
+  /**
+   * Use the given communications [channel] to send the notifications to the
+   * server.
+   */
+  void sendNotifications(PluginCommunicationChannel channel) {
+    for (final notification in notifications) {

[mfairhurst, 2017/05/31 21:49:35]

could be `notifications.forEach(channel.sendNotification)`

[Brian Wilkerson, 2017/06/03 16:44:37]

Yes, but last I checked, that's quite a bit less efficient.

+      channel.sendNotification(notification);
+    }
+  }
+}