Correctly return finished

[facontidavide]

Hi,

I think this change makes the behavior of resume more semantically correct.

Consider the following code

void routine_func()
{
    std::cout << "step1" << std::endl;
    coroutine::yield();

    std::cout << "step2" << std::endl;
    coroutine::yield();

    std::cout << "step3"<< std::endl;
    coroutine::yiel3();

     std::cout << "done" << std::endl;
}

int main()
{
    coroutine::routine_t rt = coroutine::create(routine_func);

    std::cout << coroutine::resume(rt) << std::endl;
    std::cout << coroutine::resume(rt) << std::endl;
    std::cout << coroutine::resume(rt) << std::endl;
    std::cout << coroutine::resume(rt) << std::endl;

   return 0;
}

I think it is reasonable to expect an output like

step1
0
step2
0
step3
0
done
-2

I would also suggest to add an enum like this

enum ResumeResult{
    INVALID = -1,
    FINISHED = -2,
    YIELD = 0
};

Cheers

Davide

[tonbit]

After co-routine is created, it will not start to run until thread owner resumes it. This behavior makes co-routine more flexible, splits object instantiating and routine running.

[facontidavide]

The PR doesn't affect the behavior when routine is created

[tonbit]

PR means ?

[facontidavide]

PR = Pull request :)

What I mean, is that in the example I provided, the 4th resume would return 0, even if the end of the coroutine was reached.
I think it is more intuitive that -2 (finished) is returned instead... since the couroutine finished at resume number 4