Implement reference_wrapper and invoke to allow invoke_result_t implementation
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bc40515636
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95
func.hpp
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95
func.hpp
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@ -0,0 +1,95 @@
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#pragma once
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#include "util.hpp"
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#include "../type/type.hpp"
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namespace util {
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// <functional>
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// clang-format off
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namespace detail {
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template <typename> constexpr bool is_reference_wrapper_v = false;
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template <typename U> constexpr bool is_reference_wrapper_v<reference_wrapper<U>> = true;
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template <typename T, typename Type, typename T1, typename... Args>
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constexpr decltype(auto) INVOKE(Type T::*f, T1 &&t1, Args &&... args)
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{
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if constexpr (type::is_member_function_pointer_v<decltype(f)>) {
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if constexpr (type::is_base_of_v<T, type::decay_t<T1>>)
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return (util::forward<T1>(t1).*f)(util::forward<Args>(args)...);
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else if constexpr (is_reference_wrapper_v<type::decay_t<T1>>)
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return (t1.get().*f)(util::forward<Args>(args)...);
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else
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return ((*util::forward<T1>(t1)).*f)(util::forward<Args>(args)...);
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} else {
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static_assert(type::is_member_object_pointer_v<decltype(f)>);
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static_assert(sizeof...(args) == 0);
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if constexpr (type::is_base_of_v<T, type::decay_t<T1>>)
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return util::forward<T1>(t1).*f;
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else if constexpr (is_reference_wrapper_v<type::decay_t<T1>>)
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return t1.get().*f;
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else
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return (*util::forward<T1>(t1)).*f;
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}
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}
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template <typename Fn, typename... Args>
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constexpr decltype(auto) INVOKE(Fn &&f, Args &&... args)
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{
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return util::forward<Fn>(f)(util::forward<Args>(args)...);
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}
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template <typename T> constexpr T &FUN(T &t) noexcept { return t; }
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template <typename T> void FUN(T &&) = delete;
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} // namespace detail
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template <typename Fn, typename... Args>
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constexpr type::invoke_result_t<Fn, Args...> invoke(Fn &&f, Args &&... args)
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noexcept(type::is_nothrow_invocable_v<Fn, Args...>)
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{
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return detail::INVOKE(util::forward<Fn>(f), util::forward<Args>(args)...);
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}
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template <typename T>
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class reference_wrapper {
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public:
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// construct/copy/destroy
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template <typename U,
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typename = decltype(detail::FUN<T>(util::declval<U>()),
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type::enable_if_t<!type::is_same_v<reference_wrapper, type::remove_cvref_t<U>>>())>
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constexpr reference_wrapper(U &&u) noexcept(noexcept(detail::FUN<T>(util::forward<U>(u))))
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: _ptr(util::addressof(detail::FUN<T>(util::forward<U>(u))))
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{}
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reference_wrapper(const reference_wrapper &) noexcept = default;
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// assignment
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reference_wrapper &operator=(const reference_wrapper &) noexcept = default;
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// access
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constexpr operator T &() const noexcept { return *_ptr; }
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constexpr T &get() const noexcept { return *_ptr; }
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template <typename... ArgTypes>
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constexpr type::invoke_result_t<T &, ArgTypes...> operator()(ArgTypes &&... args) const
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{
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return invoke(get(), util::forward<ArgTypes>(args)...);
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}
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// types
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using type = T;
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private:
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T *_ptr;
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};
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// deduction guides
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template <typename T> reference_wrapper(T &) -> reference_wrapper<T>;
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// clang-format on
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} // namespace util
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66
util.hpp
66
util.hpp
@ -6,6 +6,26 @@
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namespace util {
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// <memory>
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// clang-format off
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template <typename T>
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type::enable_if_t<type::is_object_v<T>, T *> addressof(T &arg) noexcept
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{
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return reinterpret_cast<T *>(&const_cast<char &>(reinterpret_cast<const volatile char &>(arg)));
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}
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template <typename T>
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type::enable_if_t<!type::is_object_v<T>, T *> addressof(T &arg) noexcept
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{
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return &arg;
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}
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// <utility>
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template <typename T> type::add_rvalue_reference_t<T> declval() noexcept;
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template <typename T>
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inline constexpr type::remove_reference_t<T> &&move(T &&t) noexcept
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{
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@ -36,33 +56,26 @@ struct integer_sequence {
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}
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};
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template <size_t... Ints>
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using index_sequence = integer_sequence<size_t, Ints...>;
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template <size_t... Ints> using index_sequence = integer_sequence<size_t, Ints...>;
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namespace detail {
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template <typename T, typename Seq1, typename Seq2>
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struct concat;
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template <typename T, typename Seq1, typename Seq2> struct concat;
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template <typename T, T... Ints1, T... Ints2>
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struct concat<T, integer_sequence<T, Ints1...>, integer_sequence<T, Ints2...>>
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: integer_sequence<T, Ints1..., (sizeof...(Ints1) + Ints2)...> {
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};
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: integer_sequence<T, Ints1..., (sizeof...(Ints1) + Ints2)...>
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{};
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// uint64_t because this must be able to hold all possible sizes and cannot be T, because then the specialization for 0
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// and 1 are not possible
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template <typename T, uint64_t N>
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struct gen_integer_sequence : detail::concat<T, typename gen_integer_sequence<T, N / 2>::__type,
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typename gen_integer_sequence<T, N - N / 2>::__type> {
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};
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typename gen_integer_sequence<T, N - N / 2>::__type>
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{};
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template <typename T>
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struct gen_integer_sequence<T, 0> : integer_sequence<T> {
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};
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template <typename T>
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struct gen_integer_sequence<T, 1> : integer_sequence<T, 0> {
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};
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template <typename T> struct gen_integer_sequence<T, 0> : integer_sequence<T> {};
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template <typename T> struct gen_integer_sequence<T, 1> : integer_sequence<T, 0> {};
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} // namespace detail
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@ -71,21 +84,16 @@ struct make_integer_sequence : detail::gen_integer_sequence<T, N> {
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static_assert(N >= 0, "Integer sequence cannot be negative");
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};
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template <size_t N>
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using make_index_sequence = make_integer_sequence<size_t, N>;
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template <size_t N> using make_index_sequence = make_integer_sequence<size_t, N>;
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template <typename... T>
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using index_sequence_for = make_index_sequence<sizeof...(T)>;
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template <typename... T> using index_sequence_for = make_index_sequence<sizeof...(T)>;
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// Not part of <utility>, but very useful
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namespace detail {
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template <typename T, T Offset, T... Ints>
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inline constexpr integer_sequence<T, (Offset + Ints)...> add_offset(integer_sequence<T, Ints...>)
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{
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return {};
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}
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inline constexpr integer_sequence<T, (Offset + Ints)...> add_offset(integer_sequence<T, Ints...>) { return {}; }
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} // namespace detail
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@ -101,10 +109,18 @@ inline constexpr auto make_offset_index_sequence()
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return make_offset_integer_sequence<size_t, Offset, N>();
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}
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template <class Fn, size_t... Ints>
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void for_constexpr(Fn &&func, index_sequence<Ints...>)
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template <typename Fn, size_t... Ints>
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auto for_constexpr(Fn &&func, index_sequence<Ints...>)
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{
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if constexpr (type::is_void_v<type::invoke_result_t<Fn, type::integral_constant<size_t, 0>>>) {
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(func(type::integral_constant<size_t, Ints>{}), ...);
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} else {
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if ((func(type::integral_constant<size_t, Ints>{}) && ...))
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return true;
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return false;
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}
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}
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// clang-format on
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} // namespace util
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