/// <summary>
/// Initializes an empty node.
/// </summary>
/// <param name="comparer">The comparer used to compare two items.</param>
public RangeTreeNode(IComparer <TKey> comparer)
{
_comparer = comparer ?? Comparer <TKey> .Default;
_center = default(TKey);
_leftNode = null;
_rightNode = null;
_items = null;
}
/// <summary>
/// Rebuilds the tree if it is out of sync.
/// </summary>
public void Rebuild()
{
if (_isInSync)
{
return;
}
if (_items.Count > 0)
{
_root = new RangeTreeNode <TKey, TValue>(_items, _comparer);
}
else
{
_root = new RangeTreeNode <TKey, TValue>(_comparer);
}
_isInSync = true;
_items.TrimExcess();
}
/// <summary>
/// Initializes a node with a list of items, builds the sub tree.
/// </summary>
/// <param name="comparer">The comparer used to compare two items.</param>
public RangeTreeNode(IList <RangeValuePair <TKey, TValue> > items, IComparer <TKey> comparer)
{
_comparer = comparer ?? Comparer <TKey> .Default;
// first, find the median
var endPoints = new List <TKey>(items.Count * 2);
foreach (var item in items)
{
endPoints.Add(item.From);
endPoints.Add(item.To);
}
endPoints.Sort(_comparer);
// the median is used as center value
_center = endPoints[endPoints.Count / 2];
var inner = new List <RangeValuePair <TKey, TValue> >();
var left = new List <RangeValuePair <TKey, TValue> >();
var right = new List <RangeValuePair <TKey, TValue> >();
// 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)
{
if (_comparer.Compare(o.To, _center) < 0)
{
left.Add(o);
}
else if (_comparer.Compare(o.From, _center) > 0)
{
right.Add(o);
}
else
{
inner.Add(o);
}
}
// sort the items, this way the query is faster later on
if (inner.Count > 0)
{
if (inner.Count > 1)
{
inner.Sort(this);
}
_items = inner.ToArray();
}
else
{
_items = null;
}
// create left and right nodes, if there are any items
if (left.Count > 0)
{
_leftNode = new RangeTreeNode <TKey, TValue>(left, _comparer);
}
if (right.Count > 0)
{
_rightNode = new RangeTreeNode <TKey, TValue>(right, _comparer);
}
}
/// <summary>
/// Clears the tree (removes all items).
/// </summary>
public void Clear()
{
_root = new RangeTreeNode <TKey, TValue>(_comparer);
_items = new List <RangeValuePair <TKey, TValue> >();
_isInSync = true;
}
