resumable test #2

resumable-idea.cpp

// resumable-idea.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"

using namespace std;
using namespace std::experimental;

struct resumable_thing
{
	struct promise_type
	{
		resumable_thing get_return_object()
		{
			return resumable_thing(coroutine_handle<promise_type>::from_promise(*this));
		}
		auto initial_suspend() { return suspend_never{}; }
		auto final_suspend() { return suspend_never{}; }
		void return_void() {}
	};
	coroutine_handle<promise_type> _coroutine = nullptr;
	resumable_thing() = default;
	resumable_thing(resumable_thing const&) = delete;
	resumable_thing& operator=(resumable_thing const&) = delete;
	resumable_thing(resumable_thing&& other)
		: _coroutine(other._coroutine) {
		other._coroutine = nullptr;
	}
	resumable_thing& operator = (resumable_thing&& other) {
		if (&other != this) {
			_coroutine = other._coroutine;
			other._coroutine = nullptr;
		}
	}
	explicit resumable_thing(coroutine_handle<promise_type> coroutine) : _coroutine(coroutine)
	{
	}
	~resumable_thing()
	{
		if (_coroutine) { _coroutine.destroy(); }
	}
	void resume() { _coroutine.resume(); }
};

resumable_thing counter() {
	cout << "counter: called\n";
	for (unsigned i = 1; ; i++)
	{
		co_await std::experimental::suspend_always{};
		cout << "counter:: resumed (#" << i << ")\n";
	}
}

void main()
{
	cout << "main:		calling counter\n";
	resumable_thing the_counter = counter();
	cout << "main:		resuming counter\n";
	the_counter.resume();
	the_counter.resume();
	cout << "main:		done\n";
}