https://blog.wongcw.com/2018/10/20/%e5%9c%a8%e7%ba%bf%e6%ad%a3%e5%88%99%e8%a1%a8%e8%be%be%e5%bc%8f%e9%aa%8c%e8%af%81%e5%b7%a5%e5%85%b7%ef%bc%9aregexpal/