namespace System.Reactive.Linq.ObservableImpl { internal sealed class MinDoubleNullable : Producer<double?, MinDoubleNullable._> { internal sealed class _ : IdentitySink<double?> { private double? _lastValue; public _(IObserver<double?> observer) : base(observer) { } public override void OnNext(double? value) { if (value.HasValue) { if (_lastValue.HasValue) { if (value < _lastValue || double.IsNaN(value.Value)) _lastValue = value; } else _lastValue = value; } } public override void OnCompleted() { ForwardOnNext(_lastValue); ForwardOnCompleted(); } } private readonly IObservable<double?> _source; public MinDoubleNullable(IObservable<double?> source) { _source = source; } protected override _ CreateSink(IObserver<double?> observer) { return new _(observer); } protected override void Run(_ sink) { sink.Run(_source); } } }