prepared_coro.h

#pragma once
 
#include <coroutine>
#include "trace.h"
 
namespace coro {
 
 
 
class prepared_coro {
public:
 
    prepared_coro() = default;
    prepared_coro(std::coroutine_handle<> h):_h(h) {}
    template<typename X>
    prepared_coro(std::coroutine_handle<X> h):_h(h) {}
    prepared_coro(prepared_coro &&other):_h(other.release()) {}
    prepared_coro &operator=(prepared_coro &&other) {
        if (this != &other) {
            (*this)();
            _h = other.release();
        }
        return *this;
    }
 
    ~prepared_coro() {
        if (_h) {
            trace::resume(_h);
        }
    }
 
    std::coroutine_handle<> release() {
        auto h = _h;
        _h = {};
        return h;
    }
 
 
    std::coroutine_handle<> symmetric_transfer() {
        if (_h) return release();
        else return std::noop_coroutine();
    }
 
    void operator()() {
        auto h = release();
        if (h) {
            trace::resume(h);
        }
    }
 
    operator bool() const {return _h != nullptr;}
 
    bool done() const {return _h.done();}
 
protected:
    std::coroutine_handle<> _h;
 
};
 
 
}