/*************************************************************************

> File Name: Generator.cpp

> Author: Netcan

> Blog: https://netcan.github.io/

> Mail: netcan1996@gmail.com

> Created Time: 2021-12-06 20:48

************************************************************************/

#include <iostream>

#include <coroutine>

#include <tuple>

#include <utility>

struct Generator {

struct promise_type;

using handle = std::coroutine_handle<promise_type>;

struct promise_type {

Generator get_return_object() { return {handle::from_promise(*this)}; }

auto initial_suspend() noexcept { return std::suspend_never{}; }

auto final_suspend() noexcept { return std::suspend_always{}; }

void unhandled_exception() { std::terminate(); }

void return_void() {}

auto yield_value(int value) {

current_value_ = value;

return std::suspend_always{};

}

int current_value_;

};

void next() { return coro_handle_.resume(); }

bool done() { return coro_handle_.done(); }

int current_value() { return coro_handle_.promise().current_value_; }

Generator(Generator&& rhs) noexcept:

coro_handle_(std::exchange(rhs.coro_handle_, {})) {}

~Generator() { if(coro_handle_) coro_handle_.destroy(); }

private:

Generator(handle h): coro_handle_(h) {}

handle coro_handle_;

};

Generator fibo() {

int a = 1, b = 1;

while (a < 1000000) {

co_yield a;

std::tie(a, b) = std::make_tuple(b, a + b);

}

co_return; // 可省略

}

int main() {

for (auto f = fibo(); !f.done(); f.next())

std::cout << f.current_value() << std::endl;

}