public static function quote($string)
{
if (false === strpos($string, '"')) {
return '"' . $string . '"';
}
if (false === strpos($string, "'")) {
return "'" . $string . "'";
}
$exp = explode('\'', $string);
return 'concat(' . implode(', ', array_map(function ($val) {
return Xpath::quote($val);
}, $exp)) . ')';
}
