private static IDisposable ItemPropertyChangedCore <TCollection, TItem, TProperty, T>(
this IObservable <TCollection> source,
IObserver <T> observer,
Expression <Func <TItem, TProperty> > property,
Func <TItem, object, PropertyChangedEventArgs, SourceAndValue <INotifyPropertyChanged, TProperty>, T> create)
where TCollection : class, IEnumerable <TItem>, INotifyCollectionChanged
where TItem : class, INotifyPropertyChanged
{
var tracker = ItemsTracker.Create((TCollection)null, NotifyingPath.GetOrCreate(property));
tracker.TrackedItemChanged += Handler;
var subscription = source.Subscribe(x => tracker.UpdateSource(x));
return(new CompositeDisposable(3)
{
Disposable.Create(() => tracker.TrackedItemChanged -= Handler),
tracker,
subscription,
});
void Handler(TItem item, object sender, PropertyChangedEventArgs args, SourceAndValue <INotifyPropertyChanged, TProperty> sourceAndValue)
{
observer.OnNext(create(item, sender, args, sourceAndValue));
}
}
private static IDisposable ObserveItemPropertyChangedCore <TCollection, TItem, TProperty, T>(
this TCollection source,
IObserver <T> o,
Expression <Func <TItem, TProperty> > property,
bool signalInitial,
Func <TItem, object, PropertyChangedEventArgs, SourceAndValue <INotifyPropertyChanged, TProperty>, T> create)
where TCollection : class, IEnumerable <TItem>, INotifyCollectionChanged
where TItem : class, INotifyPropertyChanged
{
var tracker = ItemsTracker.Create(
signalInitial
? null
: source,
NotifyingPath.GetOrCreate(property));
TrackedItemPropertyChangedEventHandler <TItem, TProperty> handler =
(item, sender, args, sourceAndValue) => o.OnNext(
create(
item,
sender,
args,
sourceAndValue));
tracker.TrackedItemChanged += handler;
if (signalInitial)
{
tracker.UpdateSource(source);
}
return(new CompositeDisposable(2)
{
Disposable.Create(() => tracker.TrackedItemChanged -= handler),
tracker
});
}