public function write($fileName=null)
    {
        $this->_resetFileName($fileName);

        ksort($this->data);
        $output = array();

        foreach ($this->data as $path => $hash) {
            array_push($output, "$hash $path\n");
        }

        writeFileText(
            $this->fileName,
            $this->fileEncoding,
            implode('', $output)
        );
    }