Promise.hpp

/*
** Copyright (C) 2020 Sylvain Fargier
**
** This software is provided 'as-is', without any express or implied
** warranty.  In no event will the authors be held liable for any damages
** arising from the use of this software.
**
** Permission is granted to anyone to use this software for any purpose,
** including commercial applications, and to alter it and redistribute it
** freely, subject to the following restrictions:
**
** 1. The origin of this software must not be misrepresented; you must not
**    claim that you wrote the original software. If you use this software
**    in a product, an acknowledgment in the product documentation would be
**    appreciated but is not required.
** 2. Altered source versions must be plainly marked as such, and must not be
**    misrepresented as being the original software.
** 3. This notice may not be removed or altered from any source distribution.
**
** Created on: 2022-02-19T10:08:28+01:00
**     Author: Sylvain Fargier <fargie_s> <fargier.sylvain@gmail.com>
**
*/
 
#ifndef PROMISE_HPP__
#define PROMISE_HPP__
 
#include <future>
 
#include "../Exception.hpp"
 
namespace smc {
namespace internal {
struct PromiseBase
{
    virtual ~PromiseBase() {}
    virtual void set_exception(const Exception &ex) = 0;
 
    template<typename T>
    std::promise<T> &get();
};
 
template<typename T>
struct Promise : public PromiseBase
{
    void set_exception(const Exception &ex) override
    {
        prom.set_exception(std::make_exception_ptr(ex));
    }
 
    std::promise<T> prom;
};
 
template<typename T>
std::promise<T> &PromiseBase::get()
{
    return static_cast<Promise<T> &>(*this).prom;
}
 
} // namespace internal
} // namespace smc
 
#endif