EmPy is a system for embedding Python expressions and statements in template text. It takes an EmPy source file, processes it, and produces output. This is accomplished via expansions, which are special signals to the EmPy system and are set off by a special prefix (by default the at sign, '@'). It can expand arbitrary Python expressions and statements in this way, as well as a variety of special forms. Textual data not explicitly delimited in this way is sent unaffected to the output, allowing Python to be used in effect as a markup language. Also supported are callbacks via hooks, recording and playback via diversions, and dynamic, chainable filters. The system is highly configurable via command line options and embedded commands.
libSieve is an implementation of the Sieve mail sorting language originally developed for the Cyrus mail system. libSieve helps to bring mail sorting functionality into your mail server application without the need to reinvent the wheel. As a library, it is not intended for end users expecting a ready-to-run program.
PyBison is a sophisticated yet easy-to-use parser creation toolkit for Python that interfaces directly to Bison (yacc)-based parsers. It provides full LALR(1) grammar support, allowing for simple parsing tasks through to writing compilers for high-level languages. Parser code is automatically generated from rules within user-created Parser classes (written in Python), and then, compiled, yacc'ed and linked into a shared library, which is loaded into the running process. All this happens automatically. When the parser runs, it connects directly with the yyparse() routine, and takes event callbacks upon parse targets being reached.