private function getGroupedNodes()
{
$current = NULL;
$counter = 0;
$groups = array();
foreach ($this->_nodes as $node) {
$previous = $node->previousSibling;
while ($previous instanceof \DOMText && $previous->isWhitespaceInElementContent()) {
$previous = $previous->previousSibling;
}
if ($previous !== $current) {
$counter++;
}
$groups[$counter][] = $node;
$current = $node;
}
return count($groups) > 0 ? $groups : FALSE;
}