78 lines
2.5 KiB
C#
78 lines
2.5 KiB
C#
// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT License.
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// See the LICENSE file in the project root for more information.
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using System.Collections.Generic;
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namespace System.Reactive.Linq.ObservableImpl
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{
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internal sealed class DistinctUntilChanged<TSource, TKey> : Producer<TSource, DistinctUntilChanged<TSource, TKey>._>
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{
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private readonly IObservable<TSource> _source;
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private readonly Func<TSource, TKey> _keySelector;
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private readonly IEqualityComparer<TKey> _comparer;
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public DistinctUntilChanged(IObservable<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer)
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{
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_source = source;
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_keySelector = keySelector;
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_comparer = comparer;
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}
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protected override _ CreateSink(IObserver<TSource> observer) => new(this, observer);
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protected override void Run(_ sink) => sink.Run(_source);
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internal sealed class _ : IdentitySink<TSource>
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{
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private readonly Func<TSource, TKey> _keySelector;
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private readonly IEqualityComparer<TKey> _comparer;
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private TKey? _currentKey;
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private bool _hasCurrentKey;
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public _(DistinctUntilChanged<TSource, TKey> parent, IObserver<TSource> observer)
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: base(observer)
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{
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_keySelector = parent._keySelector;
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_comparer = parent._comparer;
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}
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public override void OnNext(TSource value)
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{
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TKey key;
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try
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{
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key = _keySelector(value);
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}
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catch (Exception exception)
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{
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ForwardOnError(exception);
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return;
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}
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var comparerEquals = false;
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if (_hasCurrentKey)
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{
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try
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{
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comparerEquals = _comparer.Equals(_currentKey!, key);
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}
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catch (Exception exception)
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{
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ForwardOnError(exception);
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return;
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}
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}
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if (!_hasCurrentKey || !comparerEquals)
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{
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_hasCurrentKey = true;
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_currentKey = key;
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ForwardOnNext(value);
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}
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}
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}
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}
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}
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