17        $name = 
$config->getDefinition(
'HTML')->doctype->name;
 
   18        if ($name == 
"XHTML 1.1" || $name == 
"XHTML 2.0") {
 
   19            return parent::split($string, 
$config, $context);
 
   21            return preg_split(
'/\s+/', $string);
 
   33        $allowed = 
$config->get(
'Attr.AllowedClasses');
 
   34        $forbidden = 
$config->get(
'Attr.ForbiddenClasses');
 
   36        foreach ($tokens as $token) {
 
   37            if (($allowed === 
null || isset($allowed[$token])) &&
 
   38                !isset($forbidden[$token]) &&
 
   41                !in_array($token, 
$ret, 
true)
 
An exception for terminatinating execution or to throw for unit testing.
Implements special behavior for class attribute (normally NMTOKENS)
filter($tokens, $config, $context)
split($string, $config, $context)
Validates contents based on NMTOKENS attribute type.