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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;
namespace System.Reactive.Linq.ObservableImpl
{
class ElementAt<TSource> : Producer<TSource>
{
private readonly IObservable<TSource> _source;
private readonly int _index;
private readonly bool _throwOnEmpty;
public ElementAt(IObservable<TSource> source, int index, bool throwOnEmpty)
{
_source = source;
_index = index;
_throwOnEmpty = throwOnEmpty;
}
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 ElementAt<TSource> _parent;
private int _i;
public _(ElementAt<TSource> parent, IObserver<TSource> observer, IDisposable cancel)
: base(observer, cancel)
{
_parent = parent;
_i = _parent._index;
}
public void OnNext(TSource value)
{
if (_i == 0)
{
base._observer.OnNext(value);
base._observer.OnCompleted();
base.Dispose();
}
_i--;
}
public void OnError(Exception error)
{
base._observer.OnError(error);
base.Dispose();
}
public void OnCompleted()
{
if (_parent._throwOnEmpty)
{
base._observer.OnError(new ArgumentOutOfRangeException("index"));
}
else
{
base._observer.OnNext(default(TSource));
base._observer.OnCompleted();
}
base.Dispose();
}
}
}
}
#endif
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