invoke.hpp

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/*******************************************************************************
 * This file is part of the "https://github.com/blackmatov/invoke.hpp"
 * For conditions of distribution and use, see copyright notice in LICENSE.md
 * Copyright (C) 2018-2020, by Matvey Cherevko (blackmatov@gmail.com)
 ******************************************************************************/
 
#pragma once
 
#include <tuple>
#include <utility>
#include <functional>
#include <type_traits>
 
#define INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(...) \
    noexcept(noexcept(__VA_ARGS__)) -> decltype (__VA_ARGS__) { return __VA_ARGS__; }
 
//
// void_t
//
 
namespace invoke_hpp
{
    namespace impl
    {
        template < typename... Args >
        struct make_void {
            using type = void;
        };
    }
 
    template < typename... Args >
    using void_t = typename impl::make_void<Args...>::type;
}
 
//
// integer_sequence
//
 
namespace invoke_hpp
{
    template < typename T, T... Ints >
    struct integer_sequence {
        using value_type = T;
        static constexpr std::size_t size() noexcept { return sizeof...(Ints); }
    };
 
    template < std::size_t... Ints >
    using index_sequence = integer_sequence<std::size_t, Ints...>;
 
    namespace impl
    {
        template < typename T, std::size_t N, T... Ints >
        struct make_integer_sequence_impl
        : make_integer_sequence_impl<T, N - 1, N - 1, Ints...> {};
 
        template < typename T, T... Ints >
        struct make_integer_sequence_impl<T, 0, Ints...>
        : integer_sequence<T, Ints...> {};
    }
 
    template < typename T, std::size_t N >
    using make_integer_sequence = impl::make_integer_sequence_impl<T, N>;
 
    template < std::size_t N >
    using make_index_sequence = make_integer_sequence<std::size_t, N>;
 
    template < typename... Ts >
    using index_sequence_for = make_index_sequence<sizeof...(Ts)>;
}
 
//
// is_reference_wrapper
//
 
namespace invoke_hpp
{
    namespace impl
    {
        template < typename T >
        struct is_reference_wrapper_impl
        : std::false_type {};
 
        template < typename U >
        struct is_reference_wrapper_impl<std::reference_wrapper<U>>
        : std::true_type {};
    }
 
    template < typename T >
    struct is_reference_wrapper
    : impl::is_reference_wrapper_impl<typename std::remove_cv<T>::type> {};
}
 
//
// invoke
//
 
namespace invoke_hpp
{
    namespace impl
    {
        //
        // invoke_member_object_impl
        //
 
        template
        <
            typename Base, typename F, typename Derived,
            typename std::enable_if<std::is_base_of<Base, typename std::decay<Derived>::type>::value, int>::type = 0
        >
        constexpr auto invoke_member_object_impl(F Base::* f, Derived&& ref)
        INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
            std::forward<Derived>(ref).*f)
 
        template
        <
            typename Base, typename F, typename RefWrap,
            typename std::enable_if<is_reference_wrapper<typename std::decay<RefWrap>::type>::value, int>::type = 0
        >
        constexpr auto invoke_member_object_impl(F Base::* f, RefWrap&& ref)
        INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
            ref.get().*f)
 
        template
        <
            typename Base, typename F, typename Pointer,
            typename std::enable_if<
                !std::is_base_of<Base, typename std::decay<Pointer>::type>::value &&
                !is_reference_wrapper<typename std::decay<Pointer>::type>::value
            , int>::type = 0
        >
        constexpr auto invoke_member_object_impl(F Base::* f, Pointer&& ptr)
        INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
            (*std::forward<Pointer>(ptr)).*f)
 
        //
        // invoke_member_function_impl
        //
 
        template
        <
            typename Base, typename F, typename Derived, typename... Args,
            typename std::enable_if<std::is_base_of<Base, typename std::decay<Derived>::type>::value, int>::type = 0
        >
        constexpr auto invoke_member_function_impl(F Base::* f, Derived&& ref, Args&&... args)
        INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
            (std::forward<Derived>(ref).*f)(std::forward<Args>(args)...))
 
        template
        <
            typename Base, typename F, typename RefWrap, typename... Args,
            typename std::enable_if<is_reference_wrapper<typename std::decay<RefWrap>::type>::value, int>::type = 0
        >
        constexpr auto invoke_member_function_impl(F Base::* f, RefWrap&& ref, Args&&... args)
        INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
            (ref.get().*f)(std::forward<Args>(args)...))
 
        template
        <
            typename Base, typename F, typename Pointer, typename... Args,
            typename std::enable_if<
                !std::is_base_of<Base, typename std::decay<Pointer>::type>::value &&
                !is_reference_wrapper<typename std::decay<Pointer>::type>::value
            , int>::type = 0
        >
        constexpr auto invoke_member_function_impl(F Base::* f, Pointer&& ptr, Args&&... args)
        INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
            ((*std::forward<Pointer>(ptr)).*f)(std::forward<Args>(args)...))
    }
 
    template
    <
        typename F, typename... Args,
        typename std::enable_if<!std::is_member_pointer<typename std::decay<F>::type>::value, int>::type = 0
    >
    constexpr auto invoke(F&& f, Args&&... args)
    INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
        std::forward<F>(f)(std::forward<Args>(args)...))
 
    template
    <
        typename F, typename T,
        typename std::enable_if<std::is_member_object_pointer<typename std::decay<F>::type>::value, int>::type = 0
    >
    constexpr auto invoke(F&& f, T&& t)
    INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
        impl::invoke_member_object_impl(std::forward<F>(f), std::forward<T>(t)))
 
    template
    <
        typename F, typename... Args,
        typename std::enable_if<std::is_member_function_pointer<typename std::decay<F>::type>::value, int>::type = 0
    >
    constexpr auto invoke(F&& f, Args&&... args)
    INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
        impl::invoke_member_function_impl(std::forward<F>(f), std::forward<Args>(args)...))
}
 
//
// invoke_result
//
 
namespace invoke_hpp
{
    namespace impl
    {
        struct invoke_result_impl_tag {};
 
        template < typename Void, typename F, typename... Args >
        struct invoke_result_impl {};
 
        template < typename F, typename... Args >
        struct invoke_result_impl<void_t<invoke_result_impl_tag, decltype(invoke_hpp::invoke(std::declval<F>(), std::declval<Args>()...))>, F, Args...> {
            using type = decltype(invoke_hpp::invoke(std::declval<F>(), std::declval<Args>()...));
        };
    }
 
    template < typename F, typename... Args >
    struct invoke_result
    : impl::invoke_result_impl<void, F, Args...> {};
 
    template < typename F, typename... Args >
    using invoke_result_t = typename invoke_result<F, Args...>::type;
}
 
//
// is_invocable
//
 
namespace invoke_hpp
{
    namespace impl
    {
        struct is_invocable_r_impl_tag {};
 
        template < typename Void, typename R, typename F, typename... Args >
        struct is_invocable_r_impl
        : std::false_type {};
 
        template < typename R, typename F, typename... Args >
        struct is_invocable_r_impl<void_t<is_invocable_r_impl_tag, invoke_result_t<F, Args...>>, R, F, Args...>
        : std::conditional<
            std::is_void<R>::value,
            std::true_type,
            std::is_convertible<invoke_result_t<F, Args...>, R>>::type {};
    }
 
    template < typename R, typename F, typename... Args >
    struct is_invocable_r
    : impl::is_invocable_r_impl<void, R, F, Args...> {};
 
    template < typename F, typename... Args >
    using is_invocable = is_invocable_r<void, F, Args...>;
}
 
//
// apply
//
 
namespace invoke_hpp
{
    namespace impl
    {
        template < typename F, typename Tuple, std::size_t... I >
        constexpr auto apply_impl(F&& f, Tuple&& args, index_sequence<I...>)
        INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
            invoke_hpp::invoke(
                std::forward<F>(f),
                std::get<I>(std::forward<Tuple>(args))...))
    }
 
    template < typename F, typename Tuple >
    constexpr auto apply(F&& f, Tuple&& args)
    INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
        impl::apply_impl(
            std::forward<F>(f),
            std::forward<Tuple>(args),
            make_index_sequence<std::tuple_size<typename std::decay<Tuple>::type>::value>()))
}
 
#undef INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN