flex & bison related
https://pypi.org/project/ply/
http://www.dabeaz.com/ply/
http://www.dalkescientific.com/writings/diary/archive/2007/11/03/antlr_java.html
http://www.dalkescientific.com/writings/NBN/parsing_with_ply.html
https://zhuanlan.zhihu.com/p/143867739