public IObservable <IGroupChangeSet <TObject, TKey, TGroupKey> > Run()
{
return(Observable.Create <IGroupChangeSet <TObject, TKey, TGroupKey> >(
observer =>
{
var locker = new object();
// create source group cache
var sourceGroups = _source.Synchronize(locker).Group(_groupSelector).DisposeMany().AsObservableCache();
// create parent groups
var parentGroups = _resultGroupSource.Synchronize(locker).Transform(
x =>
{
// if child already has data, populate it.
var result = new ManagedGroup <TObject, TKey, TGroupKey>(x);
var child = sourceGroups.Lookup(x);
if (child.HasValue)
{
// dodgy cast but fine as a groups is always a ManagedGroup;
var group = (ManagedGroup <TObject, TKey, TGroupKey>)child.Value;
result.Update(updater => updater.Clone(group.GetInitialUpdates()));
}
return result;
}).DisposeMany().AsObservableCache();
// connect to each individual item and update the resulting group
var updatesFromChildren = sourceGroups.Connect().SubscribeMany(
x => x.Cache.Connect().Subscribe(
updates =>
{
var groupToUpdate = parentGroups.Lookup(x.Key);
if (groupToUpdate.HasValue)
{
groupToUpdate.Value.Update(updater => updater.Clone(updates));
}
})).DisposeMany().Subscribe();
var notifier = parentGroups.Connect().Select(
x =>
{
var groups = x.Select(s => new Change <IGroup <TObject, TKey, TGroupKey>, TGroupKey>(s.Reason, s.Key, s.Current));
return new GroupChangeSet <TObject, TKey, TGroupKey>(groups);
}).SubscribeSafe(observer);
return Disposable.Create(
() =>
{
notifier.Dispose();
sourceGroups.Dispose();
parentGroups.Dispose();
updatesFromChildren.Dispose();
});
}));
}
private Tuple <ManagedGroup <TObject, TKey, TGroupKey>, bool> GetCache(TGroupKey key)
{
var cache = _groupCache.Lookup(key);
if (cache.HasValue)
{
return(Tuple.Create(cache.Value, false));
}
var newcache = new ManagedGroup <TObject, TKey, TGroupKey>(key);
_groupCache[key] = newcache;
return(Tuple.Create(newcache, true));
}
private bool Equals(ManagedGroup <TObject, TKey, TGroupKey> other)
{
return(EqualityComparer <TGroupKey> .Default.Equals(Key, other.Key));
}