/**
  * Helper function for getQueryDescription() that prepares a single value
  * string, possibly extracting comparators. $value is changed to consist
  * only of the remaining effective value string (without the comparator).
  *
  * @param string $value
  * @param string $comparator
  */
 protected static function prepareValue(&$value, &$comparator)
 {
     // Loop over the comparators to determine which one is used and what the actual value is.
     foreach (SMWQueryLanguage::getComparatorStrings() as $string) {
         if (strpos($value, $string) === 0) {
             $comparator = SMWQueryLanguage::getComparatorFromString(substr($value, 0, strlen($string)));
             $value = substr($value, strlen($string));
             break;
         }
     }
 }