public function test_that_left_holds_reference_to_left_node()
{
$monday = WeekDay::MONDAY();
$node = new RedBlackNode($monday, 'Monday', 1, RedBlackNode::RED);
$sunday = WeekDay::SUNDAY();
$left = new RedBlackNode($sunday, 'Sunday', 1, RedBlackNode::RED);
$node->setLeft($left);
$this->assertSame($left, $node->left());
}
/**
* Restores red-black tree invariant on insert
*
* @codeCoverageIgnore
*
* @param RedBlackNode $node The subtree root
*
* @return RedBlackNode
*/
protected function balanceOnInsert(RedBlackNode $node) : RedBlackNode
{
if ($this->isRed($node->right()) && !$this->isRed($node->left())) {
$node = $this->rotateLeft($node);
}
if ($this->isRed($node->left()) && $this->isRed($node->left()->left())) {
$node = $this->rotateRight($node);
}
if ($this->isRed($node->left()) && $this->isRed($node->right())) {
$this->flipColors($node);
}
$node->setSize(1 + $this->nodeSize($node->left()) + $this->nodeSize($node->right()));
return $node;
}