querySelector.php

<?php

// composer require symfony/css-selector
// Easy to use CSS selectors on XML and HTML docs. 

use Symfony\Component\CssSelector\CssSelectorConverter;

include_once "vendor/autoload.php";

// $xml = simplexml_load_file('test.xml');

function querySelector($simple_xml, $query) {
    $converter = new CssSelectorConverter();
    $res = $simple_xml->xpath($converter->toXPath($query));
    return $res;
}

// $res = querySelector($xml, 'css > tag > another');