Symfony\Component\DomCrawler\Crawler::createDOMXPath PHP Method

    private function createDOMXPath(\DOMDocument $document, array $prefixes = array())
    {
        $domxpath = new \DOMXPath($document);
        foreach ($prefixes as $prefix) {
            $namespace = $this->discoverNamespace($domxpath, $prefix);
            if (null !== $namespace) {
                $domxpath->registerNamespace($prefix, $namespace);
            }
        }
        return $domxpath;
    }