public override INotificationResult Notify(IList <INotificationResult> sources)
{
var added = new List <TResult>();
var removed = new List <TResult>();
foreach (var change in sources)
{
if (change.Source == source)
{
var sourceChange = (CollectionChangedNotificationResult <TSource>)change;
if (sourceChange.IsReset)
{
foreach (var item in lambdaInstances.Values)
{
item.Successors.Unset(this);
}
lambdaInstances.Clear();
foreach (var item in source)
{
AttachItem(item);
}
OnCleared();
return(new CollectionChangedNotificationResult <TResult>(this));
}
else
{
NotifySource(sourceChange, added, removed);
}
}
else
{
var itemChange = (ValueChangedNotificationResult <TResult>)change;
if (source.Count() > 1)
{
// if there are multiple changes, we need to check whether the change belongs to items
// we just added or removed
var addIndex = added.IndexOf(itemChange.OldValue);
var removeIndex = removed.IndexOf(itemChange.NewValue);
if (addIndex == -1)
{
if (removeIndex == -1)
{
// the changed item was not added or removed
removed.Add(itemChange.OldValue);
added.Add(itemChange.NewValue);
}
else
{
// if the value is removed, remove the old value only
removed[removeIndex] = itemChange.OldValue;
}
}
else
{
if (removeIndex == -1)
{
// an added item changed
added[addIndex] = itemChange.NewValue;
}
else
{
// an added item turns out to be the same as a removed item, so erase the change
added.RemoveAt(addIndex);
removed.RemoveAt(removeIndex);
}
}
}
else
{
removed.Add(itemChange.OldValue);
added.Add(itemChange.NewValue);
}
}
}
RaiseEvents(added, removed, null);
return(new CollectionChangedNotificationResult <TResult>(this, added, removed));
}