public static function getStringOperands($includeSelector = false)
    {
        $values = array(
            self::STRING_STARTS,
            self::STRING_ENDS,
            self::STRING_EQUALS,
            self::STRING_CONTAINS,
        );

        if ($includeSelector) {
            $values[] = self::OPERAND_SELECTOR;
        }

        return $values;
    }