HTMLPurifier_AttrDef_HTML_Nmtokens::validate PHP Метод

    public function validate($string, $config, $context)
    {
        $string = trim($string);
        // early abort: '' and '0' (strings that convert to false) are invalid
        if (!$string) {
            return false;
        }
        $tokens = $this->split($string, $config, $context);
        $tokens = $this->filter($tokens, $config, $context);
        if (empty($tokens)) {
            return false;
        }
        return implode(' ', $tokens);
    }