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// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
#if !NO_PERF
using System;
using System.Collections.Generic;
namespace System.Reactive.Linq.Observαble
{
class DistinctUntilChanged<TSource, TKey> : Producer<TSource>
{
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 IDisposable Run(IObserver<TSource> observer, IDisposable cancel, Action<IDisposable> setSink)
{
var sink = new _(this, observer, cancel);
setSink(sink);
return _source.SubscribeSafe(sink);
}
class _ : Sink<TSource>, IObserver<TSource>
{
private readonly DistinctUntilChanged<TSource, TKey> _parent;
private TKey _currentKey;
private bool _hasCurrentKey;
public _(DistinctUntilChanged<TSource, TKey> parent, IObserver<TSource> observer, IDisposable cancel)
: base(observer, cancel)
{
_parent = parent;
_currentKey = default(TKey);
_hasCurrentKey = false;
}
public void OnNext(TSource value)
{
var key = default(TKey);
try
{
key = _parent._keySelector(value);
}
catch (Exception exception)
{
base._observer.OnError(exception);
base.Dispose();
return;
}
var comparerEquals = false;
if (_hasCurrentKey)
{
try
{
comparerEquals = _parent._comparer.Equals(_currentKey, key);
}
catch (Exception exception)
{
base._observer.OnError(exception);
base.Dispose();
return;
}
}
if (!_hasCurrentKey || !comparerEquals)
{
_hasCurrentKey = true;
_currentKey = key;
base._observer.OnNext(value);
}
}
public void OnError(Exception error)
{
base._observer.OnError(error);
base.Dispose();
}
public void OnCompleted()
{
base._observer.OnCompleted();
base.Dispose();
}
}
}
}
#endif
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