namespace System.Reactive.Linq.ObservableImpl { internal sealed class IsEmpty<TSource> : Producer<bool, IsEmpty<TSource>._> { internal sealed class _ : Sink<TSource, bool> { public _(IObserver<bool> observer) : base(observer) { } public override void OnNext(TSource value) { ForwardOnNext(false); ForwardOnCompleted(); } public override void OnCompleted() { ForwardOnNext(true); ForwardOnCompleted(); } } private readonly IObservable<TSource> _source; public IsEmpty(IObservable<TSource> source) { _source = source; } protected override _ CreateSink(IObserver<bool> observer) { return new _(observer); } protected override void Run(_ sink) { sink.Run(_source); } } }