/** * Extracts an oEmbed response format from a link tag. * * @param $Link Link tag. * @return Tag string|null Format. */ protected function _extractFormat(Tag $Link) { $isAlternate = $Link->matches('rel', '~alternate~i'); $hasFormat = $Link->matches('type', '~(?<format>json|xml)~i', $matches); if ($isAlternate && $hasFormat) { return $matches['format']; } return null; }