Medusa\Tree\PersistentRedBlackTree::add PHP Метод

    public function add($key, $value)
    {
        $c = $this->compare($key, $this->key);
        if ($c === 0) {
            $t = new self($key, $value, $this->left, $this->right, $this->color, $this->isRoot);
        } else {
            if ($c < 0) {
                $t = new self($this->key, $this->value, $this->addLeft($key, $value), $this->right, $this->color, $this->isRoot);
            } else {
                $t = new self($this->key, $this->value, $this->left, $this->addRight($key, $value), $this->color, $this->isRoot);
            }
        }
        if ($this->isRed($t->right()) && !$this->isRed($t->left())) {
            $t = $this->rotateLeft($t);
        }
        if ($this->isRed($t->left()) && $this->isRed($t->left()->left())) {
            $t = $this->rotateRight($t);
        }
        if ($this->isRed($t->right()) && $this->isRed($t->left())) {
            $t = $this->flipColors($t);
        }
        return $t;
    }