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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;
using System.Reactive.Concurrency;
using System.Reactive.Disposables;
namespace System.Reactive.Linq.ObservableImpl
{
class ToObservable<TSource> : Producer<TSource>
{
private readonly IEnumerable<TSource> _source;
private readonly IScheduler _scheduler;
public ToObservable(IEnumerable<TSource> source, IScheduler scheduler)
{
_source = source;
_scheduler = scheduler;
}
protected override IDisposable Run(IObserver<TSource> observer, IDisposable cancel, Action<IDisposable> setSink)
{
var sink = new _(this, observer, cancel);
setSink(sink);
return sink.Run();
}
class _ : Sink<TSource>
{
private readonly ToObservable<TSource> _parent;
public _(ToObservable<TSource> parent, IObserver<TSource> observer, IDisposable cancel)
: base(observer, cancel)
{
_parent = parent;
}
public IDisposable Run()
{
var e = default(IEnumerator<TSource>);
try
{
e = _parent._source.GetEnumerator();
}
catch (Exception exception)
{
base._observer.OnError(exception);
base.Dispose();
return Disposable.Empty;
}
var longRunning = _parent._scheduler.AsLongRunning();
if (longRunning != null)
{
//
// Long-running schedulers have the contract they should *never* prevent
// the work from starting, such that the scheduled work has the chance
// to observe the cancellation and perform proper clean-up. In this case,
// we're sure Loop will be entered, allowing us to dispose the enumerator.
//
return longRunning.ScheduleLongRunning(e, Loop);
}
else
{
//
// We never allow the scheduled work to be cancelled. Instead, the flag
// is used to have LoopRec bail out and perform proper clean-up of the
// enumerator.
//
var flag = new BooleanDisposable();
_parent._scheduler.Schedule(new State(flag, e), LoopRec);
return flag;
}
}
class State
{
public readonly ICancelable flag;
public readonly IEnumerator<TSource> enumerator;
public State(ICancelable flag, IEnumerator<TSource> enumerator)
{
this.flag = flag;
this.enumerator = enumerator;
}
}
private void LoopRec(State state, Action<State> recurse)
{
var hasNext = false;
var ex = default(Exception);
var current = default(TSource);
if (state.flag.IsDisposed)
{
state.enumerator.Dispose();
return;
}
try
{
hasNext = state.enumerator.MoveNext();
if (hasNext)
current = state.enumerator.Current;
}
catch (Exception exception)
{
ex = exception;
}
if (ex != null)
{
state.enumerator.Dispose();
base._observer.OnError(ex);
base.Dispose();
return;
}
if (!hasNext)
{
state.enumerator.Dispose();
base._observer.OnCompleted();
base.Dispose();
return;
}
base._observer.OnNext(current);
recurse(state);
}
private void Loop(IEnumerator<TSource> enumerator, ICancelable cancel)
{
while (!cancel.IsDisposed)
{
var hasNext = false;
var ex = default(Exception);
var current = default(TSource);
try
{
hasNext = enumerator.MoveNext();
if (hasNext)
current = enumerator.Current;
}
catch (Exception exception)
{
ex = exception;
}
if (ex != null)
{
base._observer.OnError(ex);
break;
}
if (!hasNext)
{
base._observer.OnCompleted();
break;
}
base._observer.OnNext(current);
}
enumerator.Dispose();
base.Dispose();
}
}
}
}
#endif
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