public static IHierarchyObject GetCommonAncestor(this IHierarchyObject source, IHierarchyObject other)
{
if (object.ReferenceEquals(other, source)) {
return source;
} else if (other.IsAncestorOf(source)) {
return other;
} else if (other.IsDescendentOf(source)) {
return source;
} else {
// Scan the hierarchy
foreach (IHierarchyObject ancestor in GetAncestors(other)) {
// Check the ancestry - skip the starting instance; we already
// performed that check
if (ancestor.ParentObject != null
&& ancestor.ParentObject.IsAncestorOf(source)) {
return ancestor.ParentObject;
}
}
return null;
}
}