639      * @param string $language programming language to use for syntax highlighting
643     public function file($text, $language = null, $filename = null, $options = null)  argument
645         $this->_highlight('file', $text, $language, $filename, $options);
652      * @param string $language programming language to use for syntax highlighting
656     public function code($text, $language = null, $filename = null, $options = null)  argument
658         $this->_highlight('code', $text, $language, $filename, $options);
666      * @param string $language programming language to use for syntax highlighting
671     public function _highlight($type, $text, $language = null, $filename = null, $options = null)  argument
677         $language = preg_replace(PREG_PATTERN_VALID_LANGUAGE, '', $language ?? '');
704         if (empty($language)) { // empty is faster than is_null and can prevent '' string
710             $this->doc .= "<pre class=\"$class $language\">" .
711                 p_xhtml_cached_geshi($text, $language, '', $options) .