protected function _parseAccept() {
		if ($this->_acceptContent) {
			return $this->_acceptContent;
		}
		$accept = $this->env('HTTP_ACCEPT');
		$accept = (preg_match('/[a-z,-]/i', $accept)) ? explode(',', $accept) : array('text/html');

		foreach (array_reverse($accept) as $i => $type) {
			unset($accept[$i]);
			list($type, $q) = (explode(';q=', $type, 2) + array($type, 1.0 + $i / 100));
			$accept[$type] = ($type == '*/*') ? 0.1 : floatval($q);
		}
		arsort($accept, SORT_NUMERIC);

		if (isset($accept['application/xhtml+xml']) && $accept['application/xhtml+xml'] >= 1) {
			unset($accept['application/xml']);
		}
		$media = $this->_classes['media'];

		if (isset($this->params['type']) && ($handler = $media::type($this->params['type']))) {
			if (isset($handler['content'])) {
				$type = (array) $handler['content'];
				$accept = array(current($type) => 1) + $accept;
			}
		}
		return $this->_acceptContent = array_keys($accept);
	}