public static IObservable <IEnumerable <TValue> > CachePerElement <TDescriptor, TValue>(
this IObservable <IEnumerable <TDescriptor> > items,
Func <TDescriptor, TValue> getValue,
Action <TValue> valueRemoved = null)
{
return(items.CachePerElement(d => d, getValue, valueRemoved));
}
IObservable <TOut> WatchSet <T, TOut>(IObservable <IEnumerable <T> > sets, Func <T, IObservable <TOut> > onItemAdded)
{
return(sets
.CachePerElement(
data => data,
(data) =>
{
var disposable = new BehaviorSubject <Optional <IDisposable> >(Optional.None());
var proxy = new Subject <TOut>();
var changes = Observable.Create <TOut>(
observer =>
{
var dis = proxy.Subscribe(observer);
if (!disposable.Value.HasValue)
{
disposable.OnNext(Optional.Some(onItemAdded(data).Subscribe(proxy)));
}
return dis;
});
return new
{
changes,
dispose = disposable
};
}, v => v.dispose.Value.Do(d => d.Dispose()))
.Select(p => p.Select(v => v.changes).Merge())
.Switch());
}