/**
  * @param EntityId $entityId
  * @param RevisionData $rev
  * @param int $count
  *
  * @return string HTML
  */
 private function buildDiffLink(EntityId $entityId, RevisionData $rev, $count)
 {
     $params = array('title' => $this->repoLinker->getEntityTitle($entityId), 'curid' => $rev->getPageId(), 'diff' => $rev->getRevId(), 'oldid' => $rev->getParentId());
     $url = $this->repoLinker->addQueryParams($this->repoLinker->getIndexUrl(), $params);
     return $this->repoLinker->formatLink($url, wfMessage('diff')->text(), array('class' => 'plainlinks', 'tabindex' => $count));
 }