////////////////////////////////////////////////////////////////////////////////////////////////////
/// <summary> Remove a leaf node. </summary>
/// <remarks> Darrellp, 2/18/2011. </remarks>
/// <param name="lfn"> node to remove. </param>
////////////////////////////////////////////////////////////////////////////////////////////////////
private void RemoveLeaf(LeafNode lfn)
{
// If we're the root, then tree go bye bye...
if (lfn == NdRoot)
{
NdRoot = null;
return;
}
// If we're a child of the root then all we do is change the root to our immediate sibling
if (lfn.NdParent == NdRoot)
{
NdRoot = lfn.ImmediateSibling;
return;
}
// Remove the leaf node and its parent
//
// We remove both the leafnode and it's parent (it's parent represents the edge
// that just terminated in our new fortune vertex, hence it's need to be removed
// also). Our immediate sibling
// is moved up to be a child of the grandparent. This changes the height
// balance on the grandparent since it loses a level.
var innParent = lfn.NdParent;
var innGrandparent = innParent.NdParent;
var fIsParentLeftChild = innParent.IsLeftChild;
// Remove our parent
innParent.SnipFromParent();
// Insert our sibling in place of our parent
// Was our parent the left child of our grandparent?
if (fIsParentLeftChild)
{
// Move sibling to be the left child of our grandparent
innGrandparent.LeftChild = lfn.ImmediateSibling;
innGrandparent.DecDht();
}
else
{
// Move sibling to be the right child of our grandparent
innGrandparent.RightChild = lfn.ImmediateSibling;
innGrandparent.IncDht();
}
// Link our former siblings together
//
// Now that we've been removed, our former siblings become direct siblings so link them together
// in the adjacent leaf chain
lfn.LinkSiblingsTogether();
}
