private IVirtualChangeSet <TObject, TKey> Virtualise(ISortedChangeSet <TObject, TKey> updates = null)
{
if (_isLoaded == false)
{
return(null);
}
var previous = _current;
var virualised = _all.Skip(_parameters.StartIndex)
.Take(_parameters.Size)
.ToList();
_current = new KeyValueCollection <TObject, TKey>(virualised, _all.Comparer, updates?.SortedItems.SortReason ?? SortReason.DataChanged, _all.Optimisations);
////check for changes within the current virtualised page. Notify if there have been changes or if the overall count has changed
var notifications = _changedCalculator.Calculate(_current, previous, updates);
if (notifications.Count == 0 && (previous.Count != _current.Count))
{
return(null);
}
var response = new VirtualResponse(_parameters.Size, _parameters.StartIndex, _all.Count);
return(new VirtualChangeSet <TObject, TKey>(notifications, _current, response));
}
private IPagedChangeSet <TObject, TKey>?Paginate(ISortedChangeSet <TObject, TKey>?updates = null)
{
if (_isLoaded == false)
{
return(null);
}
var previous = _current;
int pages = CalculatePages();
int page = _request.Page > pages ? pages : _request.Page;
int skip = _request.Size * (page - 1);
var paged = _all.Skip(skip).Take(_request.Size).ToList();
_current = new KeyValueCollection <TObject, TKey>(paged, _all.Comparer, updates?.SortedItems.SortReason ?? SortReason.DataChanged, _all.Optimisations);
// check for changes within the current virtualised page. Notify if there have been changes or if the overall count has changed
var notifications = FilteredIndexCalculator <TObject, TKey> .Calculate(_current, previous, updates);
if (notifications.Count == 0 && (previous.Count != _current.Count))
{
return(null);
}
var response = new PageResponse(_request.Size, _all.Count, page, pages);
return(new PagedChangeSet <TObject, TKey>(_current, notifications, response));
}