/**
* Delete node by key in sub tree. Returns node from which we start
* @param Node $node
* @param KeyInterface $key
* @return Node
*/
private function _delete(Node $node, KeyInterface $key) : Node
{
if (!$node->getLength()) {
return new Node(new Key(''), null);
}
$cmp = $node->getKey()->compare($key);
if ($cmp > 0) {
$node->setLeft($this->_delete($node->getLeft(), $key));
} else {
if ($cmp < 0) {
$node->setRight($this->_delete($node->getRight(), $key));
} else {
if (!$node->getRight()->getLength()) {
// if node have empty right link replace it with his left link
return $node->getLeft();
}
if (!$node->getLeft()->getLength()) {
// if node have empty left link replace it with his right link
return $node->getRight();
}
// save link
$tmp = $node;
// get min node in right branch
$node = $this->_min($tmp->getRight());
// delete min node in tree and set right link in min node with right branch of deleted node
$node->setRight($this->_deleteMin($tmp->getRight()));
// set left link in min node with left branch of deleted node
$node->setLeft($tmp->getLeft());
}
}
return $node;
}
private function rotateRight(Node $node) : Node
{
$tmp = $node->getLeft();
$node->setLeft($tmp->getRight());
$tmp->setRight($node);
$tmp->setColor($node->getColor());
$node->setColor(Node::RED);
return $tmp;
}
