coro-dbg.cpp

#include <experimental/coroutine>

class resumable {
public:
  struct promise_type;
  using coro_handle = std::experimental::coroutine_handle<promise_type>;
  resumable(coro_handle handle) : handle_(handle) { }
  resumable(resumable&) = delete;
  resumable(resumable&&) = delete;
  bool resume() {
    if (not handle_.done())
      handle_.resume();
    return not handle_.done();
  }
  ~resumable() { handle_.destroy(); }
private:
  coro_handle handle_;
};

struct resumable::promise_type {
  using coro_handle = std::experimental::coroutine_handle<promise_type>;
  auto get_return_object() {
    return coro_handle::from_promise(*this);
  }
  auto initial_suspend() {
    return std::experimental::suspend_always();
  }
  auto final_suspend() noexcept {
    return std::experimental::suspend_always();
  }
  void return_void() {}
  void unhandled_exception() {
    std::terminate();
  }
};

resumable foo() {
  int x[10] = {};
  int a = 3;
  co_await std::experimental::suspend_always();
  a++;
  x[0] = 1;
  a += 2;
  x[1] = 2;
  a += 3;
  x[2] = 3;
}

int main(){
  resumable res = foo();
  while (res.resume());
}