/// <summary>
/// Initializes a tree with a list of items to be added.
/// </summary>
public RangeTree(IEnumerable <IInterval <T> > items, IComparer <IInterval <T> > rangeComparer = null)
{
this._rangeComparer = rangeComparer ?? Comparer <IInterval <T> > .Default;
this._items = items != null?items.ToList() : new List <IInterval <T> >();
this._root = new RangeTreeNode <T>(this._items, rangeComparer);
this._isInSync = true;
this._autoRebuild = true;
}
/// <summary>
/// Rebuilds the tree if it is out of sync.
/// </summary>
public void Rebuild()
{
if (this._isInSync)
{
return;
}
this._root = new RangeTreeNode <T>(this._items, this._rangeComparer);
this._isInSync = true;
}
/// <summary>
/// Initializes a node with a list of items, builds the sub tree.
/// </summary>
/// <param name="items">Data to include in this node.</param>
/// <param name="rangeComparer">The comparer used to compare two items.</param>
public RangeTreeNode(IEnumerable <IInterval <T> > items, IComparer <IInterval <T> > rangeComparer = null)
{
rangeComparer = rangeComparer ?? Comparer <IInterval <T> > .Default;
// No items? nothing to do
if (items == null || !items.Any())
{
return;
}
// first, find the median
var endPoints = new List <T>();
foreach (var o in items)
{
var range = o;
endPoints.Add(range.Min.Value);
endPoints.Add(range.Max.Value);
}
endPoints.Sort();
// the median is used as center value
this._center = endPoints[endPoints.Count / 2];
this._items = new List <IInterval <T> >();
var left = new List <IInterval <T> >();
var right = new List <IInterval <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 items)
{
var range = o;
if (range.Max.Value.CompareTo(this._center) < 0)
{
left.Add(o);
}
else if (range.Min.Value.CompareTo(this._center) > 0)
{
right.Add(o);
}
else
{
this._items.Add(o);
}
}
// sort the items, this way the query is faster later on
if (this._items.Count > 0)
{
this._items.Sort(rangeComparer);
}
else
{
this._items = null;
}
// create left and right nodes, if there are any items
if (left.Count > 0)
{
this._leftNode = new RangeTreeNode <T>(left);
}
if (right.Count > 0)
{
this._rightNode = new RangeTreeNode <T>(right);
}
}
/// <summary>
/// Clears the tree (removes all items).
/// </summary>
public void Clear()
{
this._root = new RangeTreeNode <T>(this._rangeComparer);
this._items = new List <IInterval <T> >();
this._isInSync = true;
}
