Method setParent

/**
 * Set the parent of this category
 *
 * If the category already has a parent, the link is unset
 *
 * @param   CategoryNode|null  $parent  CategoryNode for the parent to be set or null
 *
 * @return  void
 *
 * @since   1.6
 */
public function setParent(NodeInterface $parent)
{
    if (!\is_null($this->_parent)) {
        $key = array_search($this, $this->_parent->_children);
        unset($this->_parent->_children[$key]);
    }
    $this->_parent = $parent;
    $this->_parent->_children[] =& $this;
    if (\count($this->_parent->_children) > 1) {
        end($this->_parent->_children);
        $this->_leftSibling = prev($this->_parent->_children);
        $this->_leftSibling->_rightsibling =& $this;
    }
    if ($this->parent_id != 1) {
        $this->_path = $parent->getPath();
    }
    $this->_path[$this->id] = $this->id . ':' . $this->alias;
}