namespace System.Reactive.Linq.ObservableImpl { internal sealed class AverageDouble : Producer<double, AverageDouble._> { internal sealed class _ : IdentitySink<double> { private double _sum; private long _count; public _(IObserver<double> observer) : base(observer) { _sum = 0; _count = 0; } public override void OnNext(double value) { try { _sum += value; checked { _count++; } } catch (Exception error) { ForwardOnError(error); } } public override void OnCompleted() { if (_count > 0) { ForwardOnNext(_sum / (double)_count); ForwardOnCompleted(); } else ForwardOnError(new InvalidOperationException(Strings_Linq.NO_ELEMENTS)); } } private readonly IObservable<double> _source; public AverageDouble(IObservable<double> source) { _source = source; } protected override _ CreateSink(IObserver<double> observer) { return new _(observer); } protected override void Run(_ sink) { sink.Run(_source); } } }