Implement Generators

[robertwb]

Merged into mainline now.

[dagss]

Assuming one selects a "switch-statement-to-resume-function"-strategy:

I just read about something called "threaded dispatch" which could be used to speed up this over a standard switch statement; basically GCC allowes one to take addresses of labels and dispatch to them later.

One should be able to make conditional macros for this so that it falls backs to a switch dispatch.

[scoder]

That's basically how I always thought about this anyway: When yielding a value, keep a pointer to the continuation point and store the local function state away, then return. When continuing, check if the continuation pointer is NULL (in which case we are just starting), otherwise, restore the local function state and jump to the label the pointer points to.

[scoder]

See CEP 307:

 http://wiki.cython.org/enhancements/generators