private void OnUpdateCollection()
{
// Get the source collection from the wrapped object.
IEnumerable <T> sourceCollection = _getMethod();
// Create a list of new items.
List <CollectionItem <T> > items = new List <CollectionItem <T> >();
// Dump all previous items into a recycle bin.
using (RecycleBin <CollectionItem <T> > bin = new RecycleBin <CollectionItem <T> >())
{
foreach (T oldItem in _collection)
{
bin.AddObject(new CollectionItem <T>(_collection, oldItem, true));
}
// Add new objects to the list.
if (sourceCollection != null)
{
foreach (T obj in sourceCollection)
{
items.Add(bin.Extract(new CollectionItem <T>(_collection, obj, false)));
}
}
// All deleted items are removed from the collection at this point.
}
// Ensure that all items are added to the list.
int index = 0;
foreach (CollectionItem <T> item in items)
{
item.EnsureInCollection(index);
++index;
}
}
/// <summary>
/// Moves all objects into a new recycle bin, from which they can be extracted.
/// </summary>
/// <param name="objects">A collection of objects to add to the bin.</param>
/// <remarks>
/// After the objects are added to the bin, the collection
/// is cleared. Then it can be repopulated by extraction from
/// the bin.
/// </remarks>
public static RecycleBin <T> Recycle <T>(this ICollection <T> collection)
{
RecycleBin <T> bin = new RecycleBin <T>(collection);
if (collection != null)
{
collection.Clear();
}
return(bin);
}