private static function parseContextPrefix(Request &$request, $serverVars = array())
    {
        // Since apache 2.3.13 we have now an additional index which provides the context
        if (isset($serverVars['CONTEXT_PREFIX']) && $serverVars['CONTEXT_PREFIX'] != '') {
            $request->setContextPrefix( $serverVars['CONTEXT_PREFIX'] . '/' );
        } elseif (isset($serverVars['REDIRECT_BASE'])) {
            // Try to determine the context from redirect base
            $request->setContextPrefix ( $serverVars['REDIRECT_BASE'] );
        } elseif (isset($serverVars['SCRIPT_FILENAME']) && isset($serverVars['SCRIPT_NAME'])) {
            // Fallback - get context out of script path
            if (isset($serverVars['HTTP_HOST'])) {
                $scriptName = preg_replace('/^.+[\\\\\\/]/', '', $serverVars['SCRIPT_FILENAME']);
                $request->contextPrefix = str_replace($scriptName, '', $serverVars['SCRIPT_NAME']);
            }
        }
    }