1 | #include <iostream> |
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2 | #include <experimental/coroutine> |
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3 | |
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4 | struct suspend_never { |
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5 | bool await_ready() noexcept { |
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6 | return true; |
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7 | } |
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8 | |
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9 | void await_suspend(std::experimental::coroutine_handle<>) noexcept {} |
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10 | void await_resume() noexcept {} |
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11 | }; |
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12 | |
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13 | struct suspend_always { |
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14 | bool await_ready() noexcept { |
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15 | return false; |
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16 | } |
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17 | |
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18 | void await_suspend(std::experimental::coroutine_handle<>) noexcept {} |
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19 | void await_resume() noexcept {} |
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20 | }; |
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21 | |
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22 | struct counter_cor { |
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23 | struct promise_type { |
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24 | counter_cor get_return_object() { |
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25 | return counter_cor(std::experimental::coroutine_handle<promise_type>::from_promise(*this)); |
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26 | } |
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27 | |
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28 | auto initial_suspend() { return suspend_never(); } |
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29 | auto final_suspend() { return suspend_never(); } |
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30 | |
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31 | void return_void() {} |
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32 | |
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33 | void unhandled_exception() {} |
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34 | }; |
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35 | |
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36 | std::experimental::coroutine_handle<promise_type> _coroutine = nullptr; |
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37 | |
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38 | explicit counter_cor(std::experimental::coroutine_handle<promise_type> coroutine) |
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39 | : _coroutine(coroutine) |
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40 | {} |
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41 | |
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42 | ~counter_cor() { |
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43 | if(_coroutine) { _coroutine.destroy(); } |
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44 | } |
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45 | |
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46 | counter_cor() = default; |
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47 | counter_cor(counter_cor const &) = delete; |
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48 | counter_cor& operator=(counter_cor const &) = delete; |
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49 | |
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50 | counter_cor(counter_cor&& other) { |
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51 | std::swap(_coroutine, other._coroutine); |
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52 | } |
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53 | |
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54 | counter_cor& operator=(counter_cor&& other) { |
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55 | if(&other != this) { |
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56 | _coroutine = other._coroutine; |
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57 | other._coroutine = nullptr; |
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58 | } |
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59 | return *this; |
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60 | } |
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61 | |
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62 | void resume() { _coroutine.resume(); } |
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63 | }; |
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64 | |
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65 | counter_cor counter() { |
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66 | std::cout << "Counter: called\n"; |
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67 | for(unsigned i = 1;; i++) { |
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68 | co_await suspend_always{}; |
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69 | std::cout << "Counter: Resumed " << i << " time(s)\n"; |
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70 | } |
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71 | } |
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72 | |
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73 | int main() { |
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74 | std::cout << "Main: calling counter\n"; |
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75 | auto c = counter(); |
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76 | std::cout << "Main: resumes\n"; |
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77 | c.resume(); |
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78 | c.resume(); |
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79 | std::cout << "Main: done\n"; |
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80 | } |
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