Yapps (Yet Another Python Parser System) is an easy to use parser
generator that is written in Python and generates Python code.  Yapps
is simple, is easy to use, and produces human-readable parsers. It is
not fast, powerful, or particularly flexible.  Yapps is designed to be
used when regular expressions are not enough and other parser systems
are too much: situations where you may write your own recursive
descent parser.  Yapps 1 is more like a functional language (concise
grammars of the form when you see this, return this), while Yapps 2 is
more like an imperative language (more verbose grammars of the form
if/while you see this, do this).  Yapps 2 is more flexible than Yapps
1 but it requires Python 1.5 and is not backwards-compatible with
Yapps 1.

This is the development version of Yapps 2.

WWW: http://theory.stanford.edu/~amitp/yapps/