My recommendation for a project like this would be SimpleParse <http://simpleparse.sourceforge.net>
Some examples are here <http://simpleparse.sourceforge.net/simpleparse_grammars.html> and <http://www-128.ibm.com/developerworks/linux/library/l-simple.html> /Jean Brouwers -- http://mail.python.org/mailman/listinfo/python-list
