protected function calculatePages()
    {
        if ($this->nb_record && $this->total > $this->nb_record) {
            $this->previous_page = $this->nb_page - 1;
            if ($this->previous_page == 0)
                $this->previous_page = false;

            $test = ($this->total / $this->nb_record);
            if ($this->nb_page == intval(ceil($test)))
                $this->next_page = false;
            else
                $this->next_page = $this->nb_page + 1;
        }
    }