public static INotifyValue <KeyValuePair <TItem, TKey>[]> CreateSelectorComparer(INotifyEnumerable <TItem> source, int x, Expression <Func <TItem, TKey> > selector, IComparer <TKey> comparer)
{
var ordered = new ObservableOrderBy <TItem, TKey>(source, selector, new ReverseComparer <TKey>(comparer));
var topx = new ObservableTopX <TItem, TKey>(ordered, x);
topx.Successors.SetDummy();
return(topx);
}
private ObservableTopX(ObservableOrderBy <TItem, TKey> source, int x)
{
this.source = source;
X = x;
value = new KeyValuePair <TItem, TKey> [0];
Successors.Attached += (obj, e) => Attach();
Successors.Detached += (obj, e) => Detach();
}