sympy/sympy — pull request #1804 by mrocklin (2013-02-19 17:58:02+00:00)
Title: Refactor strategies

A general refactoring of the strategies module

1. Introduce stategic all `sall` and refactor `top_down` and `bottom_up` tree traversals. Add `top_down_once` and `bottom_up_once`.
2. Rename files `strat_pure.py` -> `core.py`. Move some functions around into better locations
3. I'd like to rename the `rules` directory to `strategies`. The majority of this directory is about strategies to apply functions, not about rewrite rules. Rewriterule code is actually found in `unify`. I suspect this is a bit confusing.