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)); }
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)); }