public virtual GroupCollection <T> Perform(
IReadOnlyCollection <T> items,
int level,
Group <T> parent)
{
GroupDescriptorCollection groupDescriptors = this.index.CollectionView.GroupDescriptors;
if (level >= groupDescriptors.Count)
{
return(GroupCollection <T> .Empty);
}
IGroupFactory <T> groupFactory = this.index.CollectionView.GroupFactory;
GroupCollection <T> cachedGroups = this.GetCachedGroups(items, level);
if (!GroupBuilder <T> .IsValid(level, groupDescriptors))
{
cachedGroups?.Dispose();
return(groupFactory.CreateCollection((IList <Group <T> >)GroupBuilder <T> .Empty));
}
IComparer <Group <T> > comparer = Activator.CreateInstance(this.Comparer.GetType()) as IComparer <Group <T> > ?? this.Comparer;
if (comparer is GroupComparer <T> )
{
((GroupComparer <T>)comparer).Directions = this.GetComparerDirections(level);
}
AvlTree <Group <T> > avlTree1 = new AvlTree <Group <T> >(comparer);
AvlTree <Group <T> > avlTree2 = new AvlTree <Group <T> >((IComparer <Group <T> >) new GroupComparer <T>(this.GetComparerDirections(level)));
foreach (T key1 in !this.CollectionView.CanPage || level != 0 || !this.CollectionView.PagingBeforeGrouping ? (IEnumerable <T>)items : (IEnumerable <T>) this.index.GetItemsOnPage(this.CollectionView.PageIndex))
{
object key2 = this.GroupPredicate(key1, level);
Group <T> group1 = (Group <T>) new DataItemGroup <T>(key2);
Group <T> group2 = avlTree2.Find(group1);
if (group2 == null)
{
group2 = this.GetGroup(cachedGroups, group1, parent, key2, level);
avlTree2.Add(group2);
}
group2.Items.Add(key1);
if (this.itemGroupsCache.ContainsKey(key1))
{
this.itemGroupsCache[key1] = group2;
}
else
{
this.itemGroupsCache.Add(key1, group2);
}
}
for (int index = 0; index < avlTree2.Count; ++index)
{
avlTree1.Add(avlTree2[index]);
}
cachedGroups?.Dispose();
return(groupFactory.CreateCollection((IList <Group <T> >)avlTree1));
}
/// <summary>
/// Performs the grouping operation for specified items.
/// </summary>
/// <param name="items">The items.</param>
/// <param name="level">The level.</param>
/// <param name="parent">The parent.</param>
/// <returns></returns>
public virtual GroupCollection <T> Perform(IReadOnlyCollection <T> items, int level, Group <T> parent)
{
GroupDescriptorCollection groupDescriptors = this.index.CollectionView.GroupDescriptors;
if (level >= groupDescriptors.Count)
{
return(GroupCollection <T> .Empty);
}
IGroupFactory <T> groupFactory = this.index.CollectionView.GroupFactory;
GroupCollection <T> cache = GetCachedGroups(items, level);
if (!IsValid(level, groupDescriptors))
{
if (cache != null)
{
cache.Dispose();
}
return(this.index.CollectionView.GroupFactory.CreateCollection(GroupBuilder <T> .Empty));
}
IComparer <Group <T> > newComparer = Activator.CreateInstance(this.Comparer.GetType()) as IComparer <Group <T> >;
if (newComparer == null)
{
newComparer = this.Comparer;
}
if (newComparer is GroupComparer <T> )
{
((GroupComparer <T>)newComparer).Directions = this.GetComparerDirections(level);
}
AvlTree <Group <T> > groupList = new AvlTree <Group <T> >(newComparer);
AvlTree <Group <T> > list = new AvlTree <Group <T> >(new GroupComparer <T>(this.GetComparerDirections(level)));
foreach (T item in items)
{
object key = this.GroupPredicate(item, level);
Group <T> group, newGroup = new DataItemGroup <T>(key);
group = list.Find(newGroup); groupList.Find(newGroup);
if (group == null)
{
group = GroupBuilder <T> .GetCachedGroup(cache, newGroup);
if (group == null)
{
group = groupFactory.CreateGroup(key, parent);
DataItemGroup <T> dataGroup = group as DataItemGroup <T>;
dataGroup.GroupBuilder = this;
}
list.Add(group);// groupList.Add(group);
}
group.Items.Add(item);
}
for (int i = 0; i < list.Count; i++)
{
groupList.Add(list[i]);
}
if (cache != null)
{
cache.Dispose();
}
return(groupFactory.CreateCollection(groupList));
}