namespace System.Reactive.Linq.ObservableImpl { internal static class FirstAsync<TSource> { internal sealed class Sequence : Producer<TSource, Sequence._> { internal sealed class _ : IdentitySink<TSource> { private bool _found; public _(IObserver<TSource> observer) : base(observer) { } public override void OnNext(TSource value) { _found = true; ForwardOnNext(value); ForwardOnCompleted(); } public override void OnCompleted() { if (!_found) ForwardOnError(new InvalidOperationException(Strings_Linq.NO_ELEMENTS)); } } private readonly IObservable<TSource> _source; public Sequence(IObservable<TSource> source) { _source = source; } protected override _ CreateSink(IObserver<TSource> observer) { return new _(observer); } protected override void Run(_ sink) { sink.Run(_source); } } internal sealed class Predicate : Producer<TSource, Predicate._> { internal sealed class _ : IdentitySink<TSource> { private readonly Func<TSource, bool> _predicate; private bool _found; public _(Func<TSource, bool> predicate, IObserver<TSource> observer) : base(observer) { _predicate = predicate; } public override void OnNext(TSource value) { bool flag = false; try { flag = _predicate(value); } catch (Exception error) { ForwardOnError(error); return; } if (flag) { _found = true; ForwardOnNext(value); ForwardOnCompleted(); } } public override void OnCompleted() { if (!_found) ForwardOnError(new InvalidOperationException(Strings_Linq.NO_MATCHING_ELEMENTS)); } } private readonly IObservable<TSource> _source; private readonly Func<TSource, bool> _predicate; public Predicate(IObservable<TSource> source, Func<TSource, bool> predicate) { _source = source; _predicate = predicate; } protected override _ CreateSink(IObserver<TSource> observer) { return new _(_predicate, observer); } protected override void Run(_ sink) { sink.Run(_source); } } } }