sf_meta.hpp

/**
* @version 1.0.0
* @author skyfire
* @mail skyfireitdiy@hotmail.com
* @see http://github.com/skyfireitdiy/sflib
* @file sf_meta.hpp

* sflib第一版本发布
* 版本号1.0.0
* 发布日期：2018-10-22
*/

/*
 * sf_meta 元编程辅助函数
 */

#pragma once

#include "sf_meta.h"

namespace skyfire {


    template<int N>
    auto make_placeholders() {
        return typename
        decltype(__sf_placeholders_type(std::placeholders::_1))::template type<N>{};
    }

    template<typename _Type, typename Tuple>
    _Type *sf_make_obj_from_tuple(Tuple &&t) {
        constexpr auto size = std::tuple_size<typename std::decay<Tuple>::type>::value;
        return sf_make_obj_from_tuple_impl<_Type>(std::forward<Tuple>(t), std::make_index_sequence<size>{});
    }

    template<typename _Type, typename Tuple, size_t... Index>
    _Type *sf_make_obj_from_tuple_impl(Tuple &&t, std::index_sequence<Index...>) {
        return new _Type(std::get<Index>(std::forward<Tuple>(t))...);
    }

    template<typename Function, typename Tuple>
    decltype(auto) sf_invoke(Function &&func, Tuple &&t) {
        constexpr auto size = std::tuple_size<typename std::decay<Tuple>::type>::value;
        return sf_invoke_impl(std::forward<Function>(func), std::forward<Tuple>(t), std::make_index_sequence<size>{});
    }

    template<typename Function, typename Tuple, size_t... Index>
    decltype(auto) sf_invoke_impl(Function &&func, Tuple &&t, std::index_sequence<Index...>) {
        if constexpr (std::is_same<decltype(func(std::get<Index>(std::forward<Tuple>(t))...)), void>::value)
        {
            func(std::get<Index>(std::forward<Tuple>(t))...);
            return 0;
        } else
        {
            return func(std::get<Index>(std::forward<Tuple>(t))...);
        }
    }


}