C++协程

参考C++那些事之C++20协程

#include <iostream>
#include <coroutine>

struct generator {
    struct promise_type {
        int current_value;
        std::suspend_always yield_value(int value) {
            current_value = value;
            return {};
        }
        std::suspend_always initial_suspend() { return {}; }
        std::suspend_always final_suspend()  noexcept  { return {}; }
        generator get_return_object() { return generator{this}; }
        void return_void() {}
        void unhandled_exception() {}
    };

    generator(promise_type* p)
        : coroutine_handle{std::coroutine_handle<promise_type>::from_promise(*p)} {}

    ~generator() { coroutine_handle.destroy(); }

    std::coroutine_handle<promise_type> coroutine_handle; // 协程句柄，用于管理暂停或执行的协程以及Promise对象

    int next() {
        coroutine_handle.resume();
        return coroutine_handle.promise().current_value;
    }
};

generator fib(int n) {
    int a = 0, b = 1;
    while (n--) {
        co_yield b;
        auto t = a;
        a = b;
        b += t;
    }
}

int main() {
    auto gen = fib(10);
    for (int i = 0; i < 10; i++) {
        std::cout << gen.next() << '\n';
    }
}