using System.Collections.Generic; namespace System.Reactive.Linq.ObservableImpl { internal sealed class DistinctUntilChanged<TSource, TKey> : Producer<TSource, DistinctUntilChanged<TSource, TKey>._> { internal sealed class _ : IdentitySink<TSource> { private readonly Func<TSource, TKey> _keySelector; private readonly IEqualityComparer<TKey> _comparer; private TKey _currentKey; private bool _hasCurrentKey; public _(DistinctUntilChanged<TSource, TKey> parent, IObserver<TSource> observer) : base(observer) { _keySelector = parent._keySelector; _comparer = parent._comparer; } public override void OnNext(TSource value) { TKey val; try { val = _keySelector(value); } catch (Exception error) { ForwardOnError(error); return; } bool flag = false; if (_hasCurrentKey) try { flag = _comparer.Equals(_currentKey, val); } catch (Exception error2) { ForwardOnError(error2); return; } if (!_hasCurrentKey || !flag) { _hasCurrentKey = true; _currentKey = val; ForwardOnNext(value); } } } private readonly IObservable<TSource> _source; private readonly Func<TSource, TKey> _keySelector; private readonly IEqualityComparer<TKey> _comparer; public DistinctUntilChanged(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); } } }