using System.Collections.Generic; namespace System.Reactive.Linq.ObservableImpl { internal sealed class MaxBy<TSource, TKey> : Producer<IList<TSource>, MaxBy<TSource, TKey>._> { internal sealed class _ : Sink<TSource, IList<TSource>> { private readonly Func<TSource, TKey> _keySelector; private readonly IComparer<TKey> _comparer; private bool _hasValue; private TKey _lastKey; private List<TSource> _list; public _(MaxBy<TSource, TKey> parent, IObserver<IList<TSource>> observer) : base(observer) { _keySelector = parent._keySelector; _comparer = parent._comparer; _list = new List<TSource>(); } public override void OnNext(TSource value) { TKey val = default(TKey); try { val = _keySelector(value); } catch (Exception error) { _list = null; _lastKey = default(TKey); ForwardOnError(error); return; } int num = 0; if (_hasValue) try { num = _comparer.Compare(val, _lastKey); } catch (Exception error2) { _list = null; _lastKey = default(TKey); ForwardOnError(error2); return; } else { _hasValue = true; _lastKey = val; } if (num > 0) { _lastKey = val; _list.Clear(); } if (num >= 0) _list.Add(value); } public override void OnError(Exception error) { _lastKey = default(TKey); _list = null; base.OnError(error); } public override void OnCompleted() { List<TSource> list = _list; _list = null; _lastKey = default(TKey); ForwardOnNext(list); ForwardOnCompleted(); } } private readonly IObservable<TSource> _source; private readonly Func<TSource, TKey> _keySelector; private readonly IComparer<TKey> _comparer; public MaxBy(IObservable<TSource> source, Func<TSource, TKey> keySelector, IComparer<TKey> comparer) { _source = source; _keySelector = keySelector; _comparer = comparer; } protected override _ CreateSink(IObserver<IList<TSource>> observer) { return new _(this, observer); } protected override void Run(_ sink) { sink.Run(_source); } } }