Method buildInit

/**
 * Do some initial processing for building a URL
 *
 * @param   SiteRouter  &$router  Router object
 * @param   Uri         &$uri     URI object to process
 *
 * @return  void
 *
 * @since   4.0.0
 */
public function buildInit(&$router, &$uri)
{
    $itemid = $uri->getVar('Itemid');
    // If no Itemid and option given, merge in the current requests data
    if (!$itemid && !$uri->getVar('option')) {
        $uri->setQuery(array_merge($this->getVars(), $uri->getQuery(true)));
    }
    // If Itemid is given, but no option, set the option from the menu item
    if ($itemid && !$uri->getVar('option')) {
        if ($item = $this->menu->getItem($itemid)) {
            $uri->setVar('option', $item->component);
        }
    }
}