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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 MaxBy<TSource, TKey> : Producer<IList<TSource>>
{
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 IDisposable Run(IObserver<IList<TSource>> observer, IDisposable cancel, Action<IDisposable> setSink)
{
var sink = new _(this, observer, cancel);
setSink(sink);
return _source.SubscribeSafe(sink);
}
class _ : Sink<IList<TSource>>, IObserver<TSource>
{
private readonly MaxBy<TSource, TKey> _parent;
private bool _hasValue;
private TKey _lastKey;
private List<TSource> _list;
public _(MaxBy<TSource, TKey> parent, IObserver<IList<TSource>> observer, IDisposable cancel)
: base(observer, cancel)
{
_parent = parent;
_hasValue = false;
_lastKey = default(TKey);
_list = new List<TSource>();
}
public void OnNext(TSource value)
{
var key = default(TKey);
try
{
key = _parent._keySelector(value);
}
catch (Exception ex)
{
base._observer.OnError(ex);
base.Dispose();
return;
}
var comparison = 0;
if (!_hasValue)
{
_hasValue = true;
_lastKey = key;
}
else
{
try
{
comparison = _parent._comparer.Compare(key, _lastKey);
}
catch (Exception ex)
{
base._observer.OnError(ex);
base.Dispose();
return;
}
}
if (comparison > 0)
{
_lastKey = key;
_list.Clear();
}
if (comparison >= 0)
{
_list.Add(value);
}
}
public void OnError(Exception error)
{
base._observer.OnError(error);
base.Dispose();
}
public void OnCompleted()
{
base._observer.OnNext(_list);
base._observer.OnCompleted();
base.Dispose();
}
}
}
}
#endif
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