/// <summary>
/// Initializes an empty node.
/// </summary>
/// <param name="rangeComparer">The comparer used to compare two items.</param>
public RangeTreeNode(IComparer <T> rangeComparer = null)
{
if (rangeComparer != null)
{
_sRangeComparer = rangeComparer;
}
_center = default;
_leftNode = null;
_rightNode = null;
_items = null;
}
/// <summary>
/// Initializes a node with a list of items, builds the sub tree.
/// </summary>
/// <param name="items">Items collection</param>
/// <param name="rangeComparer">The comparer used to compare two items.</param>
public RangeTreeNode(IEnumerable <T> items, IComparer <T> rangeComparer = null)
{
if (rangeComparer != null)
{
_sRangeComparer = rangeComparer;
}
// first, find the median
var endPoints = new List <TKey>();
var itemsArray = items as T[] ?? items.ToArray();
foreach (var o in itemsArray)
{
var range = o.Range;
endPoints.Add(range.From);
endPoints.Add(range.To);
}
endPoints.Sort();
// the median is used as center value
_center = endPoints[endPoints.Count / 2];
_items = new List <T>();
var left = new List <T>();
var right = new List <T>();
// iterate over all items
// if the range of an item is completely left of the center, add it to the left items
// if it is on the right of the center, add it to the right items
// otherwise (range overlaps the center), add the item to this node's items
foreach (var o in itemsArray)
{
var range = o.Range;
if (range.To.CompareTo(_center) < 0)
{
left.Add(o);
}
else if (range.From.CompareTo(_center) > 0)
{
right.Add(o);
}
else
{
_items.Add(o);
}
}
// sort the items, this way the query is faster later on
if (_items.Count > 0)
{
_items.Sort(_sRangeComparer);
}
else
{
_items = null;
}
// create left and right nodes, if there are any items
if (left.Count > 0)
{
_leftNode = new RangeTreeNode <TKey, T>(left);
}
if (right.Count > 0)
{
_rightNode = new RangeTreeNode <TKey, T>(right);
}
}