private function _unescape($string, $escapeChar)
    {
        if ($escapeChar) {
            $regexp = '/'.'\\'.$escapeChar.'/';
            $this->buffer = array('escapeChar'=> $escapeChar, 'i' => 0);

            return preg_replace_callback(
                $regexp,
                array(&$this, '_unescapeBis'),
                $string
            );

        } else {
            return $string;
        }
    }