/// <summary>Returns all sub-trees enumerated from left to right.</summary>
/// <returns>Enumerated sub-trees or empty if tree is empty.</returns>
public IEnumerable <ImMap <V> > Enumerate()
{
if (Height == 0)
{
yield break;
}
var parents = new ImMap <V> [Height];
var node = this;
var parentCount = -1;
while (node.Height != 0 || parentCount != -1)
{
if (node.Height != 0)
{
parents[++parentCount] = node;
node = node.Left;
}
else
{
node = parents[parentCount--];
yield return(node);
node = node.Right;
}
}
}
private ImMap(int key, V value, ImMap <V> left, ImMap <V> right, int height)
{
Key = key;
Value = value;
Left = left;
Right = right;
Height = height;
}
private ImMap(int key, V value, ImMap <V> left, ImMap <V> right)
{
Key = key;
Value = value;
Left = left;
Right = right;
Height = 1 + (left.Height > right.Height ? left.Height : right.Height);
}
private ImMap(int key, V value)
{
Key = key;
Value = value;
Left = Empty;
Right = Empty;
Height = 1;
}
private ImMap <V> RemoveImpl(int key, bool ignoreKey = false)
{
if (Height == 0)
{
return(this);
}
ImMap <V> result;
if (key == Key || ignoreKey) // found node
{
if (Height == 1) // remove node
{
return(Empty);
}
if (Right.IsEmpty)
{
result = Left;
}
else if (Left.IsEmpty)
{
result = Right;
}
else
{
// we have two children, so remove the next highest node and replace this node with it.
var successor = Right;
while (!successor.Left.IsEmpty)
{
successor = successor.Left;
}
result = new ImMap <V>(successor.Key, successor.Value,
Left, Right.RemoveImpl(successor.Key, ignoreKey: true));
}
}
else if (key < Key)
{
result = new ImMap <V>(Key, Value, Left.RemoveImpl(key), Right);
}
else
{
result = new ImMap <V>(Key, Value, Left, Right.RemoveImpl(key));
}
return(result.KeepBalance());
}