typegetter.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 <tuple>

namespace LC::Util
{
    namespace detail
    {
        template<typename R, typename... Args>
        std::tuple<R, Args...>* TypeGetter (R (*) (Args...));

        template<typename F>
        auto TypeGetter (F&& f) -> decltype (TypeGetter (+f));

        template<typename C, typename R, typename... Args>
        std::tuple<R, const C, Args...>* TypeGetter (R (C::*) (Args...) const);

        template<typename C, typename R, typename... Args>
        std::tuple<R, C, Args...>* TypeGetter (R (C::*) (Args...));

        template<typename C, typename R>
        std::tuple<R, C>* TypeGetter (R (C::*));

        template<typename C, typename R, typename... Args>
        std::tuple<R, Args...>* TypeGetterNoClass (R (C::*) (Args...) const);

        template<typename C, typename R, typename... Args>
        std::tuple<R, Args...>* TypeGetterNoClass (R (C::*) (Args...));

        template<typename C>
        decltype (TypeGetterNoClass (&C::operator ())) TypeGetter (const C& c);

        template<typename F>
        using CallTypeGetter_t = std::decay_t<decltype (*detail::TypeGetter (*static_cast<F*> (nullptr)))>;
    }

    template<typename F>
    concept SomeInvokable = requires (F f) { detail::TypeGetter (f); };

    template<SomeInvokable F, size_t Idx>
    using ArgType_t = std::tuple_element_t<Idx + 1, detail::CallTypeGetter_t<F>>;

    template<SomeInvokable F>
    using RetType_t = std::tuple_element_t<0, detail::CallTypeGetter_t<F>>;

    template<SomeInvokable F>
    inline constexpr auto ArgCount_v = std::tuple_size_v<detail::CallTypeGetter_t<F>> - 1;

    namespace detail
    {
        template<typename>
        struct DecomposeMemberPtr
        {
        };

        template<typename R, typename C>
        struct DecomposeMemberPtr<R (C::*)>
        {
            using Value_t = R;
            using StructType_t = C;
        };
    }

    template<typename PtrType>
    using MemberTypeType_t = typename detail::DecomposeMemberPtr<PtrType>::Value_t;

    template<typename PtrType>
    using MemberTypeStruct_t = typename detail::DecomposeMemberPtr<PtrType>::StructType_t;

    template<auto Ptr>
    using MemberPtrType_t = MemberTypeType_t<decltype (Ptr)>;

    template<auto Ptr>
    using MemberPtrStruct_t = MemberTypeStruct_t<decltype (Ptr)>;
}