/// <summary>
/// If pathSeparator argument is null, the Path property will not be computed.
/// </summary>
public static HierarchyInfo[] Compute(HierarchyItem[] items, string pathSeparator)
{
if (items.Length == 0)
return new HierarchyInfo[] { };
var roots = items.Where(item => !item.ParentID.HasValue).ToArray();
if (roots.Count() == 0)
throw new HierarchyCircularReferenceException();
var children = items.Where(item => item.ParentID.HasValue)
.GroupBy(item => item.ParentID.Value)
.ToDictionary(group => group.Key, group => group.ToArray());
var result = items.Select(item => new HierarchyInfo { ID = item.ID }).ToArray();
var index = 1;
foreach (var root in roots)
FillIndexes(root, 0, ref index, null, children, result.ToDictionary(i => i.ID), pathSeparator);
return result;
}
private static void FillIndexes(HierarchyItem currentItem, int level, ref int index, string parentPath,
IDictionary<Guid, HierarchyItem[]> children, IDictionary<Guid, HierarchyInfo> infos, string pathSeparator)
{
var currentInfo = infos[currentItem.ID];
if (currentInfo.LeftIndex != 0)
throw new HierarchyCircularReferenceException();
currentInfo.LeftIndex = index++;
currentInfo.Level = level;
if (pathSeparator != null)
if (parentPath == null)
currentInfo.Path = currentItem.Name ?? "";
else
currentInfo.Path = parentPath + pathSeparator + (currentItem.Name ?? "");
HierarchyItem[] currentChildren;
children.TryGetValue(currentItem.ID, out currentChildren);
if (currentChildren != null)
foreach (var child in currentChildren)
FillIndexes(child, level + 1, ref index, currentInfo.Path, children, infos, pathSeparator);
currentInfo.RightIndex = index++;
}
private static void FillIndexes(HierarchyItem currentItem, int level, ref int index, string parentPath,
IDictionary <Guid, HierarchyItem[]> children, IDictionary <Guid, HierarchyInfo> infos, string pathSeparator)
{
var currentInfo = infos[currentItem.ID];
if (currentInfo.LeftIndex != 0)
{
throw new HierarchyCircularReferenceException();
}
currentInfo.LeftIndex = index++;
currentInfo.Level = level;
if (pathSeparator != null)
{
if (parentPath == null)
{
currentInfo.Path = currentItem.Name ?? "";
}
else
{
currentInfo.Path = parentPath + pathSeparator + (currentItem.Name ?? "");
}
}
HierarchyItem[] currentChildren;
children.TryGetValue(currentItem.ID, out currentChildren);
if (currentChildren != null)
{
foreach (var child in currentChildren)
{
FillIndexes(child, level + 1, ref index, currentInfo.Path, children, infos, pathSeparator);
}
}
currentInfo.RightIndex = index++;
}