using System.Collections.Generic; namespace System.Reactive.Linq.ObservableImpl { internal sealed class Distinct<TSource, TKey> : Producer<TSource, Distinct<TSource, TKey>._> { internal sealed class _ : IdentitySink<TSource> { private readonly Func<TSource, TKey> _keySelector; private readonly HashSet<TKey> _hashSet; public _(Distinct<TSource, TKey> parent, IObserver<TSource> observer) : base(observer) { _keySelector = parent._keySelector; _hashSet = new HashSet<TKey>(parent._comparer); } public override void OnNext(TSource value) { TKey val = default(TKey); bool flag = false; try { val = _keySelector(value); flag = _hashSet.Add(val); } catch (Exception error) { ForwardOnError(error); return; } if (flag) ForwardOnNext(value); } } private readonly IObservable<TSource> _source; private readonly Func<TSource, TKey> _keySelector; private readonly IEqualityComparer<TKey> _comparer; public Distinct(IObservable<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer) { _source = source; _keySelector = keySelector; _comparer = comparer; } protected override _ CreateSink(IObserver<TSource> observer) { return new _(this, observer); } protected override void Run(_ sink) { sink.Run(_source); } } }