public function extract_pages(tpost $post, $s)
{
$post->deletepages();
$pages = explode('<!--nextpage-->', $s);
$firstpage = $this->filter(array_shift($pages));
foreach ($pages as $page) {
$page = trim($page);
if ($page) {
$post->addpage($this->filter($page));
}
}
return $firstpage;
}