private static void ChildToAggregateMapUnmap <T>(this ConcurrentObservableCollection <T> source, ConcurrentObservableCollection <T> dest, MapUnmap mapUnmap)
{
NotifyCollectionChangedEventHandler collectionChangedHander = (s, e) =>
{
foreach (var item in e?.OldItems?.OfType <T>() ?? Enumerable.Empty <T>())
{
dest.Remove(item);
}
foreach (var item in e?.NewItems?.OfType <T>() ?? Enumerable.Empty <T>())
{
dest.Add(item);
}
};
using (var freezeToken = source.FreezeUpdates())
{
if (mapUnmap == MapUnmap.Map)
{
dest.AddRange(source);
source.CollectionChanged += collectionChangedHander;
}
else if (mapUnmap == MapUnmap.Unmap)
{
dest.RemoveRange(source);
source.CollectionChanged -= collectionChangedHander;
}
}
}
public static void MapChildListToAggregate <T, K>(this ConcurrentObservableCollection <T> source, ConcurrentObservableCollection <K> dest, Func <T, ConcurrentObservableCollection <K> > selectChildList)
{
NotifyCollectionChangedEventHandler collectionChangedHander = (s, e) =>
{
foreach (var item in e?.OldItems?.OfType <T>() ?? Enumerable.Empty <T>())
{
selectChildList(item).UnmapChildToAggregate(dest);
}
foreach (var item in e?.NewItems?.OfType <T>() ?? Enumerable.Empty <T>())
{
selectChildList(item).MapChildToAggregate(dest);
}
};
using (var freezeToken = source.FreezeUpdates())
{
source.CollectionChanged += collectionChangedHander;
foreach (var item in source)
{
selectChildList(item).MapChildToAggregate(dest);
}
}
}
public static void UnmapChildToAggregate <T>(this ConcurrentObservableCollection <T> source, ConcurrentObservableCollection <T> dest)
{
source.ChildToAggregateMapUnmap(dest, MapUnmap.Unmap);
}