/// <summary>TODO</summary>
public static async Task <Unit> ExecuteTrafficLight <T>
(this ITrafficLight <T> e)
{
e.ContractedNotNull("e");
Contract.Ensures(Contract.Result <Task <Unit> >() != null); // not supported for async/await
try {
var trafficLightState = await LightStates <T> .Start(e)(e);
while (trafficLightState != null)
{
trafficLightState = await trafficLightState()(e);
}
} catch (OperationCanceledException) {; }
return(Unit._);
}
//[Pure]
internal static Reader <ITrafficLight <T>, Task <LightStates <T> .TrafficLightState> > GetState <T>(
this LightStates <T> .Transition transition,
int delayTenthsSeconds,
IO <Unit> action
)
{
transition.ContractedNotNull("transition");
Contract.Ensures(Contract.Result <Reader <ITrafficLight <T>, Task <LightStates <T> .TrafficLightState> > >() != null);
return(e => from _ in (from _ in action
select Task.Delay(TimeSpan.FromMilliseconds(100 * delayTenthsSeconds)
, e.CancellationToken)
).Invoke()
select new LightStates <T> .TrafficLightState(() => transition(e)));
}
private async Task <Unit> StartLights()
{
return(await LightStates.ExecuteTrafficLight <Image>(_trafficLight));
}