private static TSource SingleOrDefaultInternal <TSource>(IObservable <TSource> source, bool throwOnEmpty)
{
var value = default(TSource);
var seenValue = false;
var moreThanOneElement = false;
var ex = default(Exception);
using (var evt = new WaitAndSetOnce())
{
//
// [OK] Use of unsafe Subscribe: fine to throw to our caller, behavior indistinguishable from going through the sink.
//
using (source.Subscribe/*Unsafe*/ (new AnonymousObserver <TSource>(
v =>
{
if (seenValue)
{
moreThanOneElement = true;
evt.Set();
}
value = v;
seenValue = true;
},
e =>
{
ex = e;
evt.Set();
},
() =>
{
evt.Set();
})))
{
evt.WaitOne();
}
}
ex.ThrowIfNotNull();
if (moreThanOneElement)
{
throw new InvalidOperationException(Strings_Linq.MORE_THAN_ONE_ELEMENT);
}
if (throwOnEmpty && !seenValue)
{
throw new InvalidOperationException(Strings_Linq.NO_ELEMENTS);
}
return(value);
}
public virtual void ForEach <TSource>(IObservable <TSource> source, Action <TSource, int> onNext)
{
using (var evt = new WaitAndSetOnce())
{
var sink = new ForEach <TSource> .ObserverIndexed(onNext, () => evt.Set());
using (source.SubscribeSafe(sink))
{
evt.WaitOne();
}
sink.Error.ThrowIfNotNull();
}
}
public virtual void ForEach <TSource>(IObservable <TSource> source, Action <TSource> onNext)
{
#if !NO_PERF
using (var evt = new WaitAndSetOnce())
{
var sink = new ForEach <TSource> ._(onNext, () => evt.Set());
using (source.SubscribeSafe(sink))
{
evt.WaitOne();
}
sink.Error.ThrowIfNotNull();
}
#else
ForEach_(source, onNext);
#endif
}