public IEnumerable <IObserver <DomEvent> > GetObservers(DomNode node, DomObserverEventScope scope)
{
var answer = scope.AncestorsAndSelf.SelectMany(
s => _items.GetValueOrDefault(s, Array.Empty <DomObserverTarget>())
);
// TODO Should have a heuristic for freeing DomObserverTargets when they are
// disposed or their lists become empty
return(answer.Where(a => a.AppliesTo(node)).Select(a => a.Observer));
}
private IList <DomObserverTarget> GetItemsForScope(DomObserverEventScope scope)
{
IList <DomObserverTarget> list;
if (!_items.TryGetValue(scope, out list))
{
// CopyOnWriteList for observers because it is possible new observers could be added in callbacks
_items[scope] = list = new CopyOnWriteList <DomObserverTarget>();
}
return(list);
}
internal void AttributeValueChanged(DomAttribute attr, DomElement element, string oldValue)
{
DomAttributeEvent evt = null;
foreach (var o in GetObservers(DomObserverEventScope.SpecificAttribute(attr.Name), element))
{
if (evt == null)
{
evt = new DomAttributeEvent(element, attr.Name, oldValue);
}
o.OnNext(evt);
}
}
public void RegisterObserver(DomObserver observer, DomNode target, DomScope scope, DomObserverEventScope events)
{
var list = GetItemsForScope(events);
list.Add(new ScopedDomObserverTarget(observer, target, scope));
}
private IEnumerable <IObserver <DomEvent> > GetObservers(DomObserverEventScope s, DomNode node)
{
return(_observers.GetObservers(node, s));
}