using System.Collections.Generic; namespace System.Reactive { internal abstract class ConcatSink<TSource> : TailRecursiveSink<TSource> { public ConcatSink(IObserver<TSource> observer, IDisposable cancel) : base(observer, cancel) { } protected override IEnumerable<IObservable<TSource>> Extract(IObservable<TSource> source) { return (source as IConcatenatable<TSource>)?.GetSources(); } public override void OnCompleted() { _recurse(); } } }