Add Server.isClosed and Client.isClosed.

lib/src/client.dart

 // Copyright (c) 2014, 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 json_rpc_2.client;
 
 import 'dart:async';
 
 import 'package:stack_trace/stack_trace.dart';
 
@@ skipping 19 matching lines @@
 
   /// The map of request ids for pending requests to [Completer]s that will be
   /// completed with those requests' responses.
   final _pendingRequests = new Map<int, Completer>();
 
   /// Returns a [Future] that completes when the connection is closed.
   ///
   /// This is the same future that's returned by [listen].
   Future get done => _streams.done;
 
+  /// Whether the connection is closed.
+  bool get isClosed => _streams.isClosed;
+
   /// Creates a [Client] that writes requests to [requests] and reads responses
   /// from [responses].
   ///
   /// If [responses] is a [StreamSink] as well as a [Stream] (for example, a
   /// `WebSocket`), [requests] may be omitted.
   ///
   /// Note that the client won't begin listening to [responses] until
   /// [Client.listen] is called.
   Client(Stream<String> responses, [StreamSink<String> requests])
       : _streams = new TwoWayStream(
@@ skipping 141 matching lines @@
     if (response.containsKey("result")) return true;
 
     if (!response.containsKey("error")) return false;
     var error = response["error"];
     if (error is! Map) return false;
     if (error["code"] is! int) return false;
     if (error["message"] is! String) return false;
     return true;
   }
 }