public static function getPath($class)
    {
        if (strncmp('HTMLPurifier', $class, 12) !== 0) {
            return false;
        }
        // Custom implementations
        if (strncmp('HTMLPurifier_Language_', $class, 22) === 0) {
            $code = str_replace('_', '-', substr($class, 22));
            $file = 'HTMLPurifier/Language/classes/' . $code . '.php';
        } else {
            $file = str_replace('_', '/', $class) . '.php';
        }
        if (!file_exists(HTMLPURIFIER_PREFIX . '/' . $file)) {
            return false;
        }
        return $file;
    }