imenu for methods using coroutine

[dmh43]

I've been using bluebird's coroutine and coffeescript's yield in my async code. However, now the regex for building the function index for imenu no longer matches for all my function definitions. To work around this, I have in my emacs init:

(setq coffee-lambda-regexp "\\(?:coroutine\\s-*\\)?\\(?:([^)]*)\\)?\\s-*\\(->\\|=>\\)")

of course, this wont work if the project uses co instead of coroutine or some other API which wraps the generators created by coffeescript.

Any ideas for a more robust solution?