A source code transformation tool to transform so called "generator functions", those are the ones using yield, to something that works in ES5.
Usage: Include unyield.js and the three files from lib in a project. Call unyield(input); and it returns you the transformed output.
Mainly a toy project. Probably won't be maintained, mainly a proof of concept "this is how I would do it" etc.
Little effort went into making it look nice. There's some low hanging fruit but output aesthetics were not a goal parameter for this project.
Complete clean-room implementation. I had not looked at Regenerator or how Traceur did this before finishing. It's also based on ZeParser2, which makes the approach inherently different anyways :)
Known limitations:
- finally: screw implementing that. It can be done, not worth my time.
- catch var after yield in catch scope: Yeah like, don't, it won't work :)
- eval: I didn't even bother with the
evalfamilies - ASI related issues can pop up. Did not thoroughly test all ASI cases for this project.
- Multiple yields in the same expression won't work. It was too much fiddling to get something like
a(yield)(yield)orx = yield + yieldto work. Note that multiple yields in a block or sub-statement should work fine. .throw(), though this API call can easily be added, good exercise for the reader ;)
You can find a live typing demo at http://unyield.qfox.nl/index.html and the test suite at http://unyield.qfox.nl/tests.html.
I wrote a blog post before working on this project. Post mortem blog post coming to a browser near you soon.