#include <concepts>
#include <coroutine>
#include <iostream>

struct CT {
	struct promise_type;
	using handle_type = std::coroutine_handle<promise_type>;

	struct promise_type {
		int m_Value;

		CT get_return_object() { return CT{ handle_type::from_promise(*this) }; }
		std::suspend_never initial_suspend() { return {}; }
		std::suspend_always final_suspend() noexcept { return {}; }

		std::suspend_always yield_value(int x)
		{
			m_Value = x;
			return {};
		}

		void return_void() {};
		void unhandled_exception() {};
	};

	handle_type m_Handle;
	
	CT(handle_type h) : m_Handle(h) {}
	~CT() { m_Handle.destroy(); }

	int val() { return m_Handle.promise().m_Value; }
	void advance() { if(!m_Handle.done()) m_Handle.resume(); }
	bool done() { return m_Handle.done(); }
};

CT gen_steps(int start, int end, int stride = 1) {
	for (int i = start; i < end; i += stride) {
		co_yield i;
	}
}

int main (int argc, char *argv[]) {
	for(auto gen = gen_steps(0, 10, 2); !gen.done(); gen.advance())
		std::cout << gen.val() << std::endl;

	return 0;
}