src/Router.php
protected function transformParam($param, $k)
    {
        if (isset($this->routeMapParse[$k][$param]) and !is_array($this->routeMapParse[$k][$param])) {
            return $this->routeMapParse[$k][$param];
        } else {
            return '(.+?)';
        }
    }
protected function transformParam($param, $k)
    {
        if (isset($this->routeMapParse[$k][$param]) and !is_array($this->routeMapParse[$k][$param])) {
            return $this->routeMapParse[$k][$param];
        } else {
            return '(.+?)';
        }
    }
Prepares the regexp

@param string $param
@param string $k

@return string