/// <summary>
/// Call methods 'onAdd' and 'onRemove' whenever an object is added or
/// removed from a collection. This class correctly handles both when
/// a collection is initialized, as well as when the collection is Reset.
/// </summary>
/// <param name="onAdd">A method to be called when an object is added
/// to the collection.</param>
/// <param name="onRemove">A method to be called when an object is removed
/// from the collection.</param>
/// <returns>A Disposable that deactivates this behavior.</returns>
public static IDisposable ActOnEveryObject <T>(this IReactiveCollection <T> This, Action <T> onAdd, Action <T> onRemove)
where T : IReactiveObject
{
foreach (var v in This)
{
onAdd(v);
}
var changingDisp = This.Changing
.Where(x => x.Action == NotifyCollectionChangedAction.Reset)
.Subscribe(
_ => This.ForEach(x => onRemove(x)));
var changedDisp = This.Changed.Subscribe(x => {
switch (x.Action)
{
case NotifyCollectionChangedAction.Add:
foreach (T v in x.NewItems)
{
onAdd(v);
}
break;
case NotifyCollectionChangedAction.Replace:
foreach (T v in x.OldItems)
{
onRemove(v);
}
foreach (T v in x.NewItems)
{
onAdd(v);
}
break;
case NotifyCollectionChangedAction.Remove:
foreach (T v in x.OldItems)
{
onRemove(v);
}
break;
case NotifyCollectionChangedAction.Reset:
foreach (T v in This)
{
onAdd(v);
}
break;
default:
break;
}
});
return(Disposable.Create(() => {
changingDisp.Dispose();
changedDisp.Dispose();
This.ForEach(x => onRemove(x));
}));
}