/// <summary>
/// Inserts a new entry to this node, assuming it's a leaf node.
/// </summary>
public void InsertAsLeaf(K key, V value, int index)
{
Debug.Assert(IsLeaf, "This node is not a leaf node.");
entries.Insert(index, new Tuple <K, V>(key, value));
nodeManager.MarkAsChanged(this);
}
//
// Public Methods
//
/// <summary>
/// Remove an entry from this instance.
/// </summary>
public void Remove(int removeAt)
{
// Validate argument
if (false == (removeAt >= 0) && (removeAt < this.entries.Count))
{
throw new ArgumentOutOfRangeException();
}
// http://webdocs.cs.ualberta.ca/~holte/T26/del-b-tree.html
// https://en.wikipedia.org/wiki/B-tree#Deletion
// If this is a node leave, flagged entry will be removed
if (IsLeaf)
{
// Step 1: Remove X from the current node.
// Being a leaf node there are no subtrees to worry about.
entries.RemoveAt(removeAt);
nodeManager.MarkAsChanged(this);
// If the removal does not cause underflow then we are done here
if ((EntriesCount >= nodeManager.MinEntriesPerNode) || (parentId == 0))
{
return;
}
// Otherwise, rebalance this node
else
{
Rebalance();
}
}
// If the value to be deleted does not occur in a leaf,
// we replace it with the largest value in its left subtree
// and then proceed to delete that value from the node that
// originally contained it
else
{
// Grab the largest entry on the left subtree
var leftSubTree = nodeManager.Find(this.childrenIds[removeAt]);
TreeNode <K, V> largestNode; int largestIndex;
leftSubTree.FindLargest(out largestNode, out largestIndex);
var replacementEntry = largestNode.GetEntry(largestIndex);
// REplace it
this.entries[removeAt] = replacementEntry;
nodeManager.MarkAsChanged(this);
// Remove it from the node we took it from
largestNode.Remove(largestIndex);
}
}