以后用到的话可以参考如下链接：
http://safehammad.com/downloads/domain-specific-languages-and-python-2011-04-21.pdf
http://www.dabeaz.com/ply/PLYTalk.pdf
http://www.ptmcg.com/geo/python/confs/pyCon2006_pres2.html
Python的DSL无非三种实现思路：
- PyParsing – An easy to use Pythonic parser where the grammar is written directly in Python.
- PLY – A more traditional Python parser based on lex and yacc.
- import re – Compact and easy to use for simple languages.