using System.Collections; using System.Collections.Generic; using System.Diagnostics.CodeAnalysis; using System.Reactive.Disposables; using System.Runtime.CompilerServices; namespace System.Reactive.Linq.ObservableImpl { internal abstract class PushToPullSink<[System.Runtime.CompilerServices.Nullable(2)] TSource, [System.Runtime.CompilerServices.Nullable(2)] TResult> : IObserver<TSource>, IEnumerator<TResult>, IEnumerator, IDisposable { private SingleAssignmentDisposableValue _upstream; private bool _done; public TResult Current { get; set; } object IEnumerator.Current { get { return Current; } } [System.Runtime.CompilerServices.NullableContext(1)] public abstract void OnNext(TSource value); [System.Runtime.CompilerServices.NullableContext(1)] public abstract void OnError(Exception error); public abstract void OnCompleted(); [System.Runtime.CompilerServices.NullableContext(1)] public abstract bool TryMoveNext([MaybeNullWhen(false)] out TResult current); public bool MoveNext() { if (!_done) { if (TryMoveNext(out TResult current)) { Current = current; return true; } _done = true; Dispose(); } return false; } public void Reset() { throw new NotSupportedException(); } public void Dispose() { _upstream.Dispose(); } [System.Runtime.CompilerServices.NullableContext(1)] public void SetUpstream(IDisposable d) { _upstream.Disposable = d; } } }