gistfile1.php

function mystify(&$handler, $newhandler) {
    $regex = '@(\w+)="([^"]+)"@imsU';
    preg_match($regex, $newhandler, $newhandlerpart);

    $new = array();
    $has_handle = false;
    if (preg_match_all($regex, $handler, $handlerparts)) {
        foreach($handlerparts[1] AS $idx => $handle) {
            if ($handle == $newhandlerpart[1]) {
                $has_handle = true;
                $new[$newhandlerpart[1]] = $handlerparts[2][$idx] . ' ' . $newhandlerpart[2];
            } else {
                $new[$handle] = $handlerparts[2][$idx];
            }
        }
    }

    if (!$has_handle) {
        $new[$newhandlerpart[1]] = $newhandlerpart[2];
    }

    $handler = '';
    foreach($new AS $hkey => $hval) {
        $handler .= $hkey .= '="' . $hval . '" ';
    }
}