libpypa is a Python parser implemented in pure C++. It neither uses any tools like flex, yacc, bison etc, nor is it using any parser framework like Boost.Spirit. It's implementation is pure C++ code. I started getting involved into the pyston project where it had an entry in their getting involved list for implementing a parser for Python. Never having properly tackled the problem of creating a parser library for any language, I decided it might be worth a try, since most of the libraries I found, where basically just using the builtin Python parser or where implemented in Python itself.