functional.h

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/**********************************************************************
 * LeechCraft - modular cross-platform feature rich internet client.
 * Copyright (C) 2006-2014  Georg Rudoy
 *
 * Distributed under the Boost Software License, Version 1.0.
 * (See accompanying file LICENSE or copy at https://www.boost.org/LICENSE_1_0.txt)
 **********************************************************************/
 
#pragma once
 
#include <type_traits>
 
namespace LC
{
namespace Util
{
    template<typename R, typename B, typename C, typename... Args>
    auto BindMemFn (R (B::*fn) (Args...), C *c)
    {
        static_assert (std::is_base_of<B, C> {}, "Base class where the member pointer belongs must be convertible to the binded object's class.");
        return [fn, c] (Args... args) { return (c->*fn) (args...); };
    }
 
    template<typename R, typename B, typename C, typename... Args>
    auto BindMemFn (R (B::*fn) (Args...) const, const C *c)
    {
        static_assert (std::is_base_of<B, C> {}, "Base class where the member pointer belongs must be convertible to the binded object's class.");
        return [fn, c] (Args... args) { return (c->*fn) (args...); };
    }
 
    template<typename To>
    struct Caster
    {
        template<typename From>
        std::enable_if_t<!std::is_base_of<To, std::decay_t<From>>::value, To> operator() (From&& from) const
        {
            return To { std::forward<From> (from) };
        }
 
        template<typename From>
        std::enable_if_t<std::is_base_of<To, std::decay_t<From>>::value, To> operator() (From&& from) const
        {
            return from;
        }
    };
 
    template<typename To>
    struct Upcaster;
 
    template<typename To>
    struct Upcaster<To*>
    {
        template<typename From, typename = std::enable_if_t<std::is_base_of_v<To, std::decay_t<From>>>>
        To* operator() (From *from) const
        {
            return from;
        }
    };
 
    template<typename To>
    constexpr auto Upcast = Upcaster<To> {};
}
}