Awaitable WPF Dispatcher

awaitableWPF.cs

	public static class WpfExtensions
	{
		public static DispatcherAwaiter GetAwaiter(this Dispatcher dispatcher)
		{
			return new DispatcherAwaiter(dispatcher, DispatcherPriority.Normal);
		}
		
		public static Tuple<Dispatcher, DispatcherPriority> WithPriority(this Dispatcher dispatcher, DispatcherPriority priority)
		{
			return Tuple.Create(dispatcher, priority);
		}
		
		public static DispatcherAwaiter GetAwaiter(this Tuple<Dispatcher, DispatcherPriority> tuple)
		{
			return new DispatcherAwaiter(tuple.Item1, tuple.Item2);
		}
		
		public struct DispatcherAwaiter : System.Runtime.CompilerServices.INotifyCompletion
		{
			readonly Dispatcher dispatcher;
			readonly DispatcherPriority priority;
			
			public DispatcherAwaiter(Dispatcher dispatcher, DispatcherPriority priority)
			{
				if (dispatcher == null)
					throw new ArgumentNullException("dispatcher");
				this.dispatcher = dispatcher;
				this.priority = priority;
			}
			
			public DispatcherAwaiter WithPriority(DispatcherPriority priority)
			{
				return new DispatcherAwaiter(dispatcher, priority);
			}
			
			public bool IsCompleted { get { return false; } }
			
			public void GetResult() { }
			
			public void OnCompleted(Action continuation)
			{
				dispatcher.BeginInvoke(priority, continuation);
			}
		}
	}