$re = '/(?:\G\s?,\s?|^)(\w+)\/(\w+)(?:\+(\w+))?|(?<!^)\G(?:\s?;\s?(\w+)=([\w\.]+))/m';
$str = 'application/xhtml+xml; q=0.9; level=3 , text/html,application/json;test=hello
application/xhtml+xml; q=3; age=9; text/html image/png;mime=none
,application/xhtml+xml; q=3; age=9; text/html application/json;test=hello
application/xhtml+xml; q=3; age=9 text/html , application/json;test=hello';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php