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proxy.h
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// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.
#ifndef _MSFT_PROXY_
#define _MSFT_PROXY_
#include <cassert>
#include <cstddef>
#include <cstdlib>
#include <bit>
#include <concepts>
#include <exception>
#include <initializer_list>
#include <limits>
#include <memory>
#include <new>
#include <tuple>
#include <type_traits>
#include <utility>
#if __STDC_HOSTED__
#include <atomic>
#include <format>
#endif // __STDC_HOSTED__
#if __cpp_rtti >= 199711L
#include <optional>
#include <typeinfo>
#endif // __cpp_rtti >= 199711L
#if __has_cpp_attribute(msvc::no_unique_address)
#define ___PRO_NO_UNIQUE_ADDRESS_ATTRIBUTE msvc::no_unique_address
#elif __has_cpp_attribute(no_unique_address)
#define ___PRO_NO_UNIQUE_ADDRESS_ATTRIBUTE no_unique_address
#else
#error "Proxy requires C++20 attribute no_unique_address"
#endif
#if __cpp_exceptions >= 199711L
#define ___PRO_THROW(...) throw __VA_ARGS__
#else
#define ___PRO_THROW(...) std::abort()
#endif // __cpp_exceptions >= 199711L
#if __cpp_static_call_operator >= 202207L
#define ___PRO_STATIC_CALL(__R, ...) static __R operator()(__VA_ARGS__)
#else
#define ___PRO_STATIC_CALL(__R, ...) __R operator()(__VA_ARGS__) const
#endif // __cpp_static_call_operator >= 202207L
#ifdef _MSC_VER
#define ___PRO_ENFORCE_EBO __declspec(empty_bases)
#else
#define ___PRO_ENFORCE_EBO
#endif // _MSC_VER
#ifdef NDEBUG
#define ___PRO_DEBUG(...)
#else
#define ___PRO_DEBUG(...) __VA_ARGS__
#endif // NDEBUG
#define __msft_lib_proxy 202503L
namespace pro {
namespace details {
struct applicable_traits { static constexpr bool applicable = true; };
struct inapplicable_traits { static constexpr bool applicable = false; };
template <template <class, class> class R, class O, class... Is>
struct recursive_reduction : std::type_identity<O> {};
template <template <class, class> class R, class O, class I, class... Is>
struct recursive_reduction<R, O, I, Is...>
: recursive_reduction<R, R<O, I>, Is...> {};
template <template <class, class> class R, class O, class... Is>
using recursive_reduction_t = typename recursive_reduction<R, O, Is...>::type;
template <class Expr>
consteval bool is_consteval(Expr)
{ return requires { typename std::bool_constant<(Expr{}(), false)>; }; }
template <class T, std::size_t I>
concept has_tuple_element = requires { typename std::tuple_element_t<I, T>; };
template <class T>
consteval bool is_tuple_like_well_formed() {
if constexpr (requires { { std::tuple_size<T>::value } ->
std::same_as<const std::size_t&>; }) {
if constexpr (is_consteval([] { return std::tuple_size<T>::value; })) {
return []<std::size_t... I>(std::index_sequence<I...>) {
return (has_tuple_element<T, I> && ...);
}(std::make_index_sequence<std::tuple_size_v<T>>{});
}
}
return false;
}
template <template <class...> class T, class TL, class Is, class... Args>
struct instantiated_traits;
template <template <class...> class T, class TL, std::size_t... Is,
class... Args>
struct instantiated_traits<T, TL, std::index_sequence<Is...>, Args...>
: std::type_identity<T<Args..., std::tuple_element_t<Is, TL>...>> {};
template <template <class...> class T, class TL, class... Args>
using instantiated_t = typename instantiated_traits<
T, TL, std::make_index_sequence<std::tuple_size_v<TL>>, Args...>::type;
template <class F> struct basic_facade_traits;
} // namespace details
enum class constraint_level { none, nontrivial, nothrow, trivial };
struct proxiable_ptr_constraints {
std::size_t max_size;
std::size_t max_align;
constraint_level copyability;
constraint_level relocatability;
constraint_level destructibility;
};
template <template <class> class O>
struct facade_aware_overload_t { facade_aware_overload_t() = delete; };
template <class F>
concept facade = details::basic_facade_traits<F>::applicable;
template <facade F> struct proxy_indirect_accessor;
template <facade F> class ___PRO_ENFORCE_EBO proxy;
namespace details {
enum class qualifier_type { lv, const_lv, rv, const_rv };
template <class T, qualifier_type Q> struct add_qualifier_traits;
template <class T>
struct add_qualifier_traits<T, qualifier_type::lv> : std::type_identity<T&> {};
template <class T>
struct add_qualifier_traits<T, qualifier_type::const_lv>
: std::type_identity<const T&> {};
template <class T>
struct add_qualifier_traits<T, qualifier_type::rv> : std::type_identity<T&&> {};
template <class T>
struct add_qualifier_traits<T, qualifier_type::const_rv>
: std::type_identity<const T&&> {};
template <class T, qualifier_type Q>
using add_qualifier_t = typename add_qualifier_traits<T, Q>::type;
template <class T, qualifier_type Q>
using add_qualifier_ptr_t = std::remove_reference_t<add_qualifier_t<T, Q>>*;
template <class T>
consteval bool has_copyability(constraint_level level) {
switch (level) {
case constraint_level::none: return true;
case constraint_level::nontrivial: return std::is_copy_constructible_v<T>;
case constraint_level::nothrow:
return std::is_nothrow_copy_constructible_v<T>;
case constraint_level::trivial:
return std::is_trivially_copy_constructible_v<T> &&
std::is_trivially_destructible_v<T>;
default: return false;
}
}
template <class T>
consteval bool has_relocatability(constraint_level level) {
switch (level) {
case constraint_level::none: return true;
case constraint_level::nontrivial:
return std::is_move_constructible_v<T> && std::is_destructible_v<T>;
case constraint_level::nothrow:
return std::is_nothrow_move_constructible_v<T> &&
std::is_nothrow_destructible_v<T>;
case constraint_level::trivial:
return std::is_trivially_move_constructible_v<T> &&
std::is_trivially_destructible_v<T>;
default: return false;
}
}
template <class T>
consteval bool has_destructibility(constraint_level level) {
switch (level) {
case constraint_level::none: return true;
case constraint_level::nontrivial: return std::is_destructible_v<T>;
case constraint_level::nothrow: return std::is_nothrow_destructible_v<T>;
case constraint_level::trivial: return std::is_trivially_destructible_v<T>;
default: return false;
}
}
template <class F>
struct proxy_helper {
static inline const auto& get_meta(const proxy<F>& p) noexcept {
assert(p.has_value());
return *p.meta_.operator->();
}
static inline void reset_meta(proxy<F>& p) noexcept { p.meta_.reset(); }
template <class P, qualifier_type Q>
static add_qualifier_t<P, Q> get_ptr(add_qualifier_t<proxy<F>, Q> p) {
if constexpr (std::is_same_v<P, proxy<F>>) {
return std::forward<add_qualifier_t<P, Q>>(p);
} else {
return static_cast<add_qualifier_t<P, Q>>(
*std::launder(reinterpret_cast<add_qualifier_ptr_t<P, Q>>(p.ptr_)));
}
}
};
template <class F, class P>
class proxy_resetting_guard {
public:
explicit proxy_resetting_guard(proxy<F>& p) noexcept : p_(p) {}
proxy_resetting_guard(const proxy_resetting_guard&) = delete;
~proxy_resetting_guard() noexcept(false) {
if constexpr (std::is_same_v<P, proxy<F>>) {
p_.reset();
} else {
std::destroy_at(std::addressof(
proxy_helper<F>::template get_ptr<P, qualifier_type::lv>(p_)));
proxy_helper<F>::reset_meta(p_);
}
}
private:
proxy<F>& p_;
};
template <bool IsDirect, class P, qualifier_type Q>
struct operand_traits : add_qualifier_traits<P, Q> {};
template <class P, qualifier_type Q>
struct operand_traits<false, P, Q>
: std::type_identity<decltype(*std::declval<add_qualifier_t<P, Q>>())> {};
template <bool IsDirect, class P, qualifier_type Q>
using operand_t = typename operand_traits<IsDirect, P, Q>::type;
template <class D, bool NE, class R, class... Args>
concept invocable_dispatch = (NE && std::is_nothrow_invocable_r_v<
R, D, Args...>) || (!NE && std::is_invocable_r_v<R, D, Args...>);
template <bool IsDirect, class D, class P, qualifier_type Q, bool NE, class R,
class... Args>
concept invocable_dispatch_ptr =
(IsDirect || (requires { *std::declval<add_qualifier_t<P, Q>>(); } &&
(!NE || noexcept(*std::declval<add_qualifier_t<P, Q>>())))) &&
invocable_dispatch<D, NE, R, operand_t<IsDirect, P, Q>, Args...> &&
(Q != qualifier_type::rv || (NE && std::is_nothrow_destructible_v<P>) ||
(!NE && std::is_destructible_v<P>));
template <class D, class R, class... Args>
R invoke_dispatch(Args&&... args) {
if constexpr (std::is_void_v<R>) {
D{}(std::forward<Args>(args)...);
} else {
return D{}(std::forward<Args>(args)...);
}
}
template <bool IsDirect, class P>
decltype(auto) get_operand(P&& ptr) {
if constexpr (IsDirect) {
return std::forward<P>(ptr);
} else {
if constexpr (std::is_constructible_v<bool, P&>) { assert(ptr); }
return *std::forward<P>(ptr);
}
}
template <class F, bool IsDirect, class D, class P, qualifier_type Q, class R,
class... Args>
R conv_dispatcher(add_qualifier_t<proxy<F>, Q> self, Args... args)
noexcept(invocable_dispatch_ptr<IsDirect, D, P, Q, true, R, Args...>) {
if constexpr (Q == qualifier_type::rv) {
proxy_resetting_guard<F, P> guard{self};
return invoke_dispatch<D, R>(
get_operand<IsDirect>(proxy_helper<F>::template get_ptr<P, Q>(
std::move(self))),
std::forward<Args>(args)...);
} else {
return invoke_dispatch<D, R>(
get_operand<IsDirect>(proxy_helper<F>::template get_ptr<P, Q>(
std::forward<add_qualifier_t<proxy<F>, Q>>(self))),
std::forward<Args>(args)...);
}
}
template <class O> struct overload_traits : inapplicable_traits {};
template <qualifier_type Q, bool NE, class R, class... Args>
struct overload_traits_impl : applicable_traits {
using return_type = R;
using view_type = R(Args...) const noexcept(NE);
template <class F>
using dispatcher_type =
R (*)(add_qualifier_t<proxy<F>, Q>, Args...) noexcept(NE);
template <class F, bool IsDirect, class D, class P>
static consteval bool is_applicable_ptr() {
if constexpr (invocable_dispatch_ptr<IsDirect, D, P, Q, NE, R, Args...>) {
return true;
} else {
return invocable_dispatch_ptr<IsDirect, D, proxy<F>, Q, NE, R, Args...>;
}
}
template <class F, bool IsDirect, class D, class P>
static consteval dispatcher_type<F> get_dispatcher() {
if constexpr (invocable_dispatch_ptr<IsDirect, D, P, Q, NE, R, Args...>) {
return &conv_dispatcher<F, IsDirect, D, P, Q, R, Args...>;
} else {
return &conv_dispatcher<F, IsDirect, D, proxy<F>, Q, R, Args...>;
}
}
static constexpr qualifier_type qualifier = Q;
};
template <class R, class... Args>
struct overload_traits<R(Args...)>
: overload_traits_impl<qualifier_type::lv, false, R, Args...> {};
template <class R, class... Args>
struct overload_traits<R(Args...) noexcept>
: overload_traits_impl<qualifier_type::lv, true, R, Args...> {};
template <class R, class... Args>
struct overload_traits<R(Args...) &>
: overload_traits_impl<qualifier_type::lv, false, R, Args...> {};
template <class R, class... Args>
struct overload_traits<R(Args...) & noexcept>
: overload_traits_impl<qualifier_type::lv, true, R, Args...> {};
template <class R, class... Args>
struct overload_traits<R(Args...) &&>
: overload_traits_impl<qualifier_type::rv, false, R, Args...> {};
template <class R, class... Args>
struct overload_traits<R(Args...) && noexcept>
: overload_traits_impl<qualifier_type::rv, true, R, Args...> {};
template <class R, class... Args>
struct overload_traits<R(Args...) const>
: overload_traits_impl<qualifier_type::const_lv, false, R, Args...> {};
template <class R, class... Args>
struct overload_traits<R(Args...) const noexcept>
: overload_traits_impl<qualifier_type::const_lv, true, R, Args...> {};
template <class R, class... Args>
struct overload_traits<R(Args...) const&>
: overload_traits_impl<qualifier_type::const_lv, false, R, Args...> {};
template <class R, class... Args>
struct overload_traits<R(Args...) const& noexcept>
: overload_traits_impl<qualifier_type::const_lv, true, R, Args...> {};
template <class R, class... Args>
struct overload_traits<R(Args...) const&&>
: overload_traits_impl<qualifier_type::const_rv, false, R, Args...> {};
template <class R, class... Args>
struct overload_traits<R(Args...) const&& noexcept>
: overload_traits_impl<qualifier_type::const_rv, true, R, Args...> {};
template <class O>
struct overload_substitution_traits
: inapplicable_traits { template <class> using type = O; };
template <template <class> class O>
struct overload_substitution_traits<facade_aware_overload_t<O>>
: applicable_traits { template <class F> using type = O<F>; };
template <class O, class F>
using substituted_overload_t =
typename overload_substitution_traits<O>::template type<F>;
template <class O>
concept extended_overload = overload_traits<O>::applicable ||
overload_substitution_traits<O>::applicable;
template <class P, class F, bool IsDirect, class D, class O>
consteval bool diagnose_proxiable_required_convention_not_implemented() {
constexpr bool verdict =
overload_traits<substituted_overload_t<O, F>>::applicable &&
overload_traits<substituted_overload_t<O, F>>
::template is_applicable_ptr<F, IsDirect, D, P>();
static_assert(verdict,
"not proxiable due to a required convention not implemented");
return verdict;
}
template <class F, bool IsDirect, class D, class O>
struct invocation_meta {
constexpr invocation_meta() noexcept : dispatcher(nullptr) {}
template <class P>
constexpr explicit invocation_meta(std::in_place_type_t<P>) noexcept
: dispatcher(overload_traits<O>
::template get_dispatcher<F, IsDirect, D, P>()) {}
typename overload_traits<O>::template dispatcher_type<F> dispatcher;
};
template <class... Ms>
struct composite_meta_impl : Ms... {
constexpr composite_meta_impl() noexcept = default;
template <class P>
constexpr explicit composite_meta_impl(std::in_place_type_t<P>) noexcept
: Ms(std::in_place_type<P>)... {}
};
template <class O, class I> struct meta_reduction : std::type_identity<O> {};
template <class... Ms, class I> requires(!std::is_void_v<I>)
struct meta_reduction<composite_meta_impl<Ms...>, I>
: std::type_identity<composite_meta_impl<Ms..., I>> {};
template <class... Ms1, class... Ms2>
struct meta_reduction<composite_meta_impl<Ms1...>, composite_meta_impl<Ms2...>>
: std::type_identity<composite_meta_impl<Ms1..., Ms2...>> {};
template <class O, class I>
using meta_reduction_t = typename meta_reduction<O, I>::type;
template <class... Ms>
using composite_meta =
recursive_reduction_t<meta_reduction_t, composite_meta_impl<>, Ms...>;
template <class T>
consteval bool is_is_direct_well_formed() {
if constexpr (requires { { T::is_direct } -> std::same_as<const bool&>; }) {
if constexpr (is_consteval([] { return T::is_direct; })) {
return true;
}
}
return false;
}
template <class C, class... Os>
struct basic_conv_traits_impl : inapplicable_traits {};
template <class C, extended_overload... Os> requires(sizeof...(Os) > 0u)
struct basic_conv_traits_impl<C, Os...> : applicable_traits {};
template <class C> struct basic_conv_traits : inapplicable_traits {};
template <class C>
requires(
requires {
typename C::dispatch_type;
typename C::overload_types;
} &&
is_is_direct_well_formed<C>() &&
std::is_trivial_v<typename C::dispatch_type> &&
is_tuple_like_well_formed<typename C::overload_types>())
struct basic_conv_traits<C>
: instantiated_t<basic_conv_traits_impl, typename C::overload_types, C> {};
template <class C, class F, class... Os>
struct conv_traits_impl : inapplicable_traits {};
template <class C, class F, class... Os>
requires(overload_traits<substituted_overload_t<Os, F>>::applicable && ...)
struct conv_traits_impl<C, F, Os...> : applicable_traits {
using meta = composite_meta_impl<invocation_meta<F, C::is_direct,
typename C::dispatch_type, substituted_overload_t<Os, F>>...>;
template <class P>
static consteval bool diagnose_proxiable() {
bool verdict = true;
((verdict &= diagnose_proxiable_required_convention_not_implemented<
P, F, C::is_direct, typename C::dispatch_type, Os>()), ...);
return verdict;
}
template <class P>
static constexpr bool applicable_ptr = (overload_traits<
substituted_overload_t<Os, F>>::template is_applicable_ptr<
F, C::is_direct, typename C::dispatch_type, P>() && ...);
};
template <class C, class F>
struct conv_traits
: instantiated_t<conv_traits_impl, typename C::overload_types, C, F> {};
template <bool IsDirect, class R>
struct refl_meta {
template <class P> requires(IsDirect)
constexpr explicit refl_meta(std::in_place_type_t<P>)
: reflector(std::in_place_type<P>) {}
template <class P> requires(!IsDirect)
constexpr explicit refl_meta(std::in_place_type_t<P>) : reflector(
std::in_place_type<typename std::pointer_traits<P>::element_type>) {}
R reflector;
};
template <class R> struct basic_refl_traits : inapplicable_traits {};
template <class R>
requires(requires { typename R::reflector_type; } &&
is_is_direct_well_formed<R>())
struct basic_refl_traits<R> : applicable_traits {};
template <class T, bool IsDirect, class R>
consteval bool is_reflector_well_formed() {
if constexpr (IsDirect) {
if constexpr (std::is_constructible_v<R, std::in_place_type_t<T>>) {
if constexpr (is_consteval([] { return R{std::in_place_type<T>}; })) {
return true;
}
}
} else {
return is_reflector_well_formed<
typename std::pointer_traits<T>::element_type, true, R>();
}
return false;
}
template <class P, class F, bool IsDirect, class R>
consteval bool diagnose_proxiable_required_reflection_not_implemented() {
constexpr bool verdict = is_reflector_well_formed<P, IsDirect, R>();
static_assert(verdict,
"not proxiable due to a required reflection not implemented");
return verdict;
}
template <class R>
struct refl_traits {
using meta = refl_meta<R::is_direct, typename R::reflector_type>;
template <class P, class F>
static consteval bool diagnose_proxiable() {
return diagnose_proxiable_required_reflection_not_implemented<
P, F, R::is_direct, typename R::reflector_type>();
}
template <class P>
static constexpr bool applicable_ptr =
is_reflector_well_formed<P, R::is_direct, typename R::reflector_type>();
};
struct copy_dispatch {
template <class T, class F>
___PRO_STATIC_CALL(void, T&& self, proxy<F>& rhs)
noexcept(std::is_nothrow_constructible_v<std::decay_t<T>, T>)
requires(std::is_constructible_v<std::decay_t<T>, T>)
{ std::construct_at(&rhs, std::forward<T>(self)); }
};
struct destroy_dispatch {
template <class T>
___PRO_STATIC_CALL(void, T& self) noexcept(std::is_nothrow_destructible_v<T>)
requires(std::is_destructible_v<T>) { std::destroy_at(&self); }
};
template <class F, class D, class ONE, class OE, constraint_level C>
struct lifetime_meta_traits : std::type_identity<void> {};
template <class F, class D, class ONE, class OE>
struct lifetime_meta_traits<F, D, ONE, OE, constraint_level::nothrow>
: std::type_identity<invocation_meta<F, true, D, ONE>> {};
template <class F, class D, class ONE, class OE>
struct lifetime_meta_traits<F, D, ONE, OE, constraint_level::nontrivial>
: std::type_identity<invocation_meta<F, true, D, OE>> {};
template <class F, class D, class ONE, class OE, constraint_level C>
using lifetime_meta_t = typename lifetime_meta_traits<F, D, ONE, OE, C>::type;
template <class... As>
class ___PRO_ENFORCE_EBO composite_accessor_impl : public As... {
template <facade> friend class pro::proxy;
template <facade> friend struct pro::proxy_indirect_accessor;
composite_accessor_impl() noexcept = default;
composite_accessor_impl(const composite_accessor_impl&) noexcept = default;
composite_accessor_impl& operator=(const composite_accessor_impl&) noexcept
= default;
};
template <class T>
struct accessor_traits_impl : std::type_identity<void> {};
template <class T>
requires(std::is_nothrow_default_constructible_v<T> &&
std::is_trivially_copyable_v<T> && !std::is_final_v<T>)
struct accessor_traits_impl<T> : std::type_identity<T> {};
template <class SFINAE, class T, class F>
struct accessor_traits : std::type_identity<void> {};
template <class T, class F>
struct accessor_traits<std::void_t<typename T::template accessor<F>>, T, F>
: accessor_traits_impl<typename T::template accessor<F>> {};
template <class T, class F>
using accessor_t = typename accessor_traits<void, T, F>::type;
template <bool IsDirect, class F, class O, class I>
struct composite_accessor_reduction : std::type_identity<O> {};
template <bool IsDirect, class F, class... As, class I>
requires(IsDirect == I::is_direct && !std::is_void_v<accessor_t<I, F>>)
struct composite_accessor_reduction<
IsDirect, F, composite_accessor_impl<As...>, I>
: std::type_identity<composite_accessor_impl<As..., accessor_t<I, F>>> {};
template <bool IsDirect, class F>
struct composite_accessor_helper {
template <class O, class I>
using reduction_t =
typename composite_accessor_reduction<IsDirect, F, O, I>::type;
};
template <bool IsDirect, class F, class... Ts>
using composite_accessor = recursive_reduction_t<
composite_accessor_helper<IsDirect, F>::template reduction_t,
composite_accessor_impl<>, Ts...>;
template <class A1, class A2> struct composite_accessor_merge_traits;
template <class... A1, class... A2>
struct composite_accessor_merge_traits<
composite_accessor_impl<A1...>, composite_accessor_impl<A2...>>
: std::type_identity<composite_accessor_impl<A1..., A2...>> {};
template <class A1, class A2>
using merged_composite_accessor =
typename composite_accessor_merge_traits<A1, A2>::type;
template <class P> struct ptr_traits : inapplicable_traits {};
template <class P>
requires(requires { typename std::pointer_traits<P>::element_type; })
struct ptr_traits<P> : applicable_traits {};
template <class F> struct ptr_traits<proxy<F>> : inapplicable_traits {};
template <class P, class F, std::size_t ActualSize, std::size_t MaxSize>
consteval bool diagnose_proxiable_size_too_large() {
constexpr bool verdict = ActualSize <= MaxSize;
static_assert(verdict, "not proxiable due to size too large");
return verdict;
}
template <class P, class F, std::size_t ActualAlign, std::size_t MaxAlign>
consteval bool diagnose_proxiable_align_too_large() {
constexpr bool verdict = ActualAlign <= MaxAlign;
static_assert(verdict, "not proxiable due to alignment too large");
return verdict;
}
template <class P, class F, constraint_level RequiredCopyability>
consteval bool diagnose_proxiable_insufficient_copyability() {
constexpr bool verdict = has_copyability<P>(RequiredCopyability);
static_assert(verdict, "not proxiable due to insufficient copyability");
return verdict;
}
template <class P, class F, constraint_level RequiredRelocatability>
consteval bool diagnose_proxiable_insufficient_relocatability() {
constexpr bool verdict = has_relocatability<P>(RequiredRelocatability);
static_assert(verdict, "not proxiable due to insufficient relocatability");
return verdict;
}
template <class P, class F, constraint_level RequiredDestructibility>
consteval bool diagnose_proxiable_insufficient_destructibility() {
constexpr bool verdict = has_destructibility<P>(RequiredDestructibility);
static_assert(verdict, "not proxiable due to insufficient destructibility");
return verdict;
}
template <class F>
consteval bool is_facade_constraints_well_formed() {
if constexpr (requires {
{ F::constraints } -> std::same_as<const proxiable_ptr_constraints&>; }) {
if constexpr (is_consteval([] { return F::constraints; })) {
return std::has_single_bit(F::constraints.max_align) &&
F::constraints.max_size % F::constraints.max_align == 0u;
}
}
return false;
}
template <class... Cs>
struct basic_facade_conv_traits_impl : inapplicable_traits {};
template <class... Cs> requires(basic_conv_traits<Cs>::applicable && ...)
struct basic_facade_conv_traits_impl<Cs...> : applicable_traits {};
template <class... Rs>
struct basic_facade_refl_traits_impl : inapplicable_traits {};
template <class... Rs> requires(basic_refl_traits<Rs>::applicable && ...)
struct basic_facade_refl_traits_impl<Rs...> : applicable_traits {};
template <class F> struct basic_facade_traits : inapplicable_traits {};
template <class F>
requires(
requires {
typename F::convention_types;
typename F::reflection_types;
} &&
is_facade_constraints_well_formed<F>() &&
is_tuple_like_well_formed<typename F::convention_types>() &&
instantiated_t<basic_facade_conv_traits_impl,
typename F::convention_types>::applicable &&
is_tuple_like_well_formed<typename F::reflection_types>() &&
instantiated_t<basic_facade_refl_traits_impl,
typename F::reflection_types>::applicable)
struct basic_facade_traits<F> : applicable_traits {};
template <class F, class... Cs>
struct facade_conv_traits_impl : inapplicable_traits {};
template <class F, class... Cs> requires(conv_traits<Cs, F>::applicable && ...)
struct facade_conv_traits_impl<F, Cs...> : applicable_traits {
using conv_meta = composite_meta<typename conv_traits<Cs, F>::meta...>;
using conv_indirect_accessor = composite_accessor<false, F, Cs...>;
using conv_direct_accessor = composite_accessor<true, F, Cs...>;
template <class P>
static consteval bool diagnose_proxiable_conv() {
bool verdict = true;
((verdict &= conv_traits<Cs, F>::template diagnose_proxiable<P>()), ...);
return verdict;
}
template <class P>
static constexpr bool conv_applicable_ptr =
(conv_traits<Cs, F>::template applicable_ptr<P> && ...);
template <bool IsDirect, class D, class O>
static constexpr bool is_invocable = std::is_base_of_v<
invocation_meta<F, IsDirect, D, O>, conv_meta>;
};
template <class F, class... Rs>
struct facade_refl_traits_impl {
using refl_meta = composite_meta<typename refl_traits<Rs>::meta...>;
using refl_indirect_accessor = composite_accessor<false, F, Rs...>;
using refl_direct_accessor = composite_accessor<true, F, Rs...>;
template <class P>
static consteval bool diagnose_proxiable_refl() {
bool verdict = true;
((verdict &= refl_traits<Rs>::template diagnose_proxiable<P, F>()), ...);
return verdict;
}
template <class P>
static constexpr bool refl_applicable_ptr =
(refl_traits<Rs>::template applicable_ptr<P> && ...);
};
template <class F> struct facade_traits : inapplicable_traits {};
template <class F> requires(instantiated_t<
facade_conv_traits_impl, typename F::convention_types, F>::applicable)
struct facade_traits<F>
: instantiated_t<facade_conv_traits_impl, typename F::convention_types, F>,
instantiated_t<facade_refl_traits_impl, typename F::reflection_types, F> {
using meta = composite_meta<
lifetime_meta_t<F, copy_dispatch, void(proxy<F>&) const noexcept,
void(proxy<F>&) const, F::constraints.copyability>,
lifetime_meta_t<F, copy_dispatch, void(proxy<F>&) && noexcept,
void(proxy<F>&) &&, F::constraints.relocatability>,
lifetime_meta_t<F, destroy_dispatch, void() noexcept, void(),
F::constraints.destructibility>, typename facade_traits::conv_meta,
typename facade_traits::refl_meta>;
using indirect_accessor = merged_composite_accessor<
typename facade_traits::conv_indirect_accessor,
typename facade_traits::refl_indirect_accessor>;
using direct_accessor = merged_composite_accessor<
typename facade_traits::conv_direct_accessor,
typename facade_traits::refl_direct_accessor>;
template <class P>
static consteval void diagnose_proxiable() {
bool verdict = true;
verdict &= diagnose_proxiable_size_too_large<
P, F, sizeof(P), F::constraints.max_size>();
verdict &= diagnose_proxiable_align_too_large<
P, F, alignof(P), F::constraints.max_align>();
verdict &= diagnose_proxiable_insufficient_copyability<
P, F, F::constraints.copyability>();
verdict &= diagnose_proxiable_insufficient_relocatability<
P, F, F::constraints.relocatability>();
verdict &= diagnose_proxiable_insufficient_destructibility<
P, F, F::constraints.destructibility>();
verdict &= facade_traits::template diagnose_proxiable_conv<P>();
verdict &= facade_traits::template diagnose_proxiable_refl<P>();
if (!verdict) { std::abort(); } // Propagate the error to the caller side
}
template <class P>
static constexpr bool applicable_ptr = sizeof(P) <= F::constraints.max_size &&
alignof(P) <= F::constraints.max_align &&
has_copyability<P>(F::constraints.copyability) &&
has_relocatability<P>(F::constraints.relocatability) &&
has_destructibility<P>(F::constraints.destructibility) &&
facade_traits::template conv_applicable_ptr<P> &&
facade_traits::template refl_applicable_ptr<P>;
};
using ptr_prototype = void*[2];
template <class M>
struct meta_ptr_indirect_impl {
constexpr meta_ptr_indirect_impl() noexcept : ptr_(nullptr) {};
template <class P>
constexpr explicit meta_ptr_indirect_impl(std::in_place_type_t<P>) noexcept
: ptr_(&storage<P>) {}
bool has_value() const noexcept { return ptr_ != nullptr; }
void reset() noexcept { ptr_ = nullptr; }
const M* operator->() const noexcept { return ptr_; }
private:
const M* ptr_;
template <class P> static constexpr M storage{std::in_place_type<P>};
};
template <class M, class DM>
struct meta_ptr_direct_impl : private M {
using M::M;
bool has_value() const noexcept { return this->DM::dispatcher != nullptr; }
void reset() noexcept { this->DM::dispatcher = nullptr; }
const M* operator->() const noexcept { return this; }
};
template <class M>
struct meta_ptr_traits_impl : std::type_identity<meta_ptr_indirect_impl<M>> {};
template <class F, bool IsDirect, class D, class O, class... Ms>
struct meta_ptr_traits_impl<
composite_meta_impl<invocation_meta<F, IsDirect, D, O>, Ms...>>
: std::type_identity<meta_ptr_direct_impl<composite_meta_impl<
invocation_meta<F, IsDirect, D, O>, Ms...>,
invocation_meta<F, IsDirect, D, O>>> {};
template <class M>
struct meta_ptr_traits : std::type_identity<meta_ptr_indirect_impl<M>> {};
template <class M>
requires(sizeof(M) <= sizeof(ptr_prototype) &&
alignof(M) <= alignof(ptr_prototype) &&
std::is_nothrow_default_constructible_v<M> &&
std::is_trivially_copyable_v<M>)
struct meta_ptr_traits<M> : meta_ptr_traits_impl<M> {};
template <class M>
using meta_ptr = typename meta_ptr_traits<M>::type;
template <class T>
class inplace_ptr {
public:
template <class... Args>
explicit inplace_ptr(std::in_place_t, Args&&... args)
: value_(std::forward<Args>(args)...) {}
inplace_ptr() = default;
inplace_ptr(const inplace_ptr&) = default;
inplace_ptr(inplace_ptr&&) = default;
inplace_ptr& operator=(const inplace_ptr&) = default;
inplace_ptr& operator=(inplace_ptr&&) = default;
T* operator->() noexcept { return std::addressof(value_); }
const T* operator->() const noexcept { return std::addressof(value_); }
T& operator*() & noexcept { return value_; }
const T& operator*() const& noexcept { return value_; }
T&& operator*() && noexcept { return std::move(value_); }
const T&& operator*() const&& noexcept { return std::move(value_); }
private:
[[___PRO_NO_UNIQUE_ADDRESS_ATTRIBUTE]]
T value_;
};
template <class F, bool IsDirect, class D, class O, class P, class... Args>
decltype(auto) invoke_impl(P&& p, Args&&... args) {
auto dispatcher = proxy_helper<F>::get_meta(p)
.template invocation_meta<F, IsDirect, D, O>::dispatcher;
return dispatcher(std::forward<P>(p), std::forward<Args>(args)...);
}
template <class F, class A, qualifier_type Q>
add_qualifier_t<proxy<F>, Q> access_impl(add_qualifier_t<A, Q> a) {
if constexpr (std::is_base_of_v<A, proxy<F>>) {
return static_cast<add_qualifier_t<proxy<F>, Q>>(a);
} else {
using IA = proxy_indirect_accessor<F>;
return static_cast<add_qualifier_t<proxy<F>, Q>>(
*reinterpret_cast<add_qualifier_ptr_t<inplace_ptr<IA>, Q>>(
static_cast<add_qualifier_ptr_t<IA, Q>>(std::addressof(a))));
}
}
} // namespace details
template <class P, class F>
concept proxiable = facade<F> && details::facade_traits<F>::applicable &&
details::facade_traits<F>::template applicable_ptr<P>;
template <facade F>
struct proxy_indirect_accessor : details::facade_traits<F>::indirect_accessor
{ friend class details::inplace_ptr<proxy_indirect_accessor>; };
template <bool IsDirect, class D, class O, facade F, class... Args>
auto proxy_invoke(proxy<F>& p, Args&&... args)
-> typename details::overload_traits<O>::return_type {
return details::invoke_impl<F, IsDirect, D, O>(
p, std::forward<Args>(args)...);
}
template <bool IsDirect, class D, class O, facade F, class... Args>
auto proxy_invoke(const proxy<F>& p, Args&&... args)
-> typename details::overload_traits<O>::return_type {
return details::invoke_impl<F, IsDirect, D, O>(
p, std::forward<Args>(args)...);
}
template <bool IsDirect, class D, class O, facade F, class... Args>
auto proxy_invoke(proxy<F>&& p, Args&&... args)
-> typename details::overload_traits<O>::return_type {
return details::invoke_impl<F, IsDirect, D, O>(
std::move(p), std::forward<Args>(args)...);
}
template <bool IsDirect, class D, class O, facade F, class... Args>
auto proxy_invoke(const proxy<F>&& p, Args&&... args)
-> typename details::overload_traits<O>::return_type {
return details::invoke_impl<F, IsDirect, D, O>(
std::move(p), std::forward<Args>(args)...);
}
template <bool IsDirect, class R, facade F>
const R& proxy_reflect(const proxy<F>& p) noexcept {
return static_cast<const details::refl_meta<IsDirect, R>&>(
details::proxy_helper<F>::get_meta(p)).reflector;
}
template <facade F, class A>
proxy<F>& access_proxy(A& a) noexcept
{ return details::access_impl<F, A, details::qualifier_type::lv>(a); }
template <facade F, class A>
const proxy<F>& access_proxy(const A& a) noexcept
{ return details::access_impl<F, A, details::qualifier_type::const_lv>(a); }
template <facade F, class A>
proxy<F>&& access_proxy(A&& a) noexcept {
return details::access_impl<F, A, details::qualifier_type::rv>(std::move(a));
}
template <facade F, class A>
const proxy<F>&& access_proxy(const A&& a) noexcept {
return details::access_impl<F, A, details::qualifier_type::const_rv>(
std::move(a));
}
template <facade F>
class proxy : public details::facade_traits<F>::direct_accessor,
public details::inplace_ptr<proxy_indirect_accessor<F>> {
friend struct details::proxy_helper<F>;
using _Traits = details::facade_traits<F>;
static_assert(_Traits::applicable);
public:
using facade_type = F;
proxy() noexcept { ___PRO_DEBUG(std::ignore = &_symbol_guard;) }
proxy(std::nullptr_t) noexcept : proxy() {}
proxy(const proxy&) noexcept requires(F::constraints.copyability ==
constraint_level::trivial) = default;
proxy(const proxy& rhs)
noexcept(F::constraints.copyability == constraint_level::nothrow)
requires(F::constraints.copyability == constraint_level::nontrivial ||
F::constraints.copyability == constraint_level::nothrow)
: details::inplace_ptr<proxy_indirect_accessor<F>>() { // Make GCC happy
if (rhs.meta_.has_value()) {
proxy_invoke<true, details::copy_dispatch, void(proxy&) const noexcept(
F::constraints.copyability == constraint_level::nothrow)>(rhs, *this);
}
}
proxy(proxy&& rhs)
noexcept(F::constraints.relocatability == constraint_level::nothrow)
requires(F::constraints.relocatability >= constraint_level::nontrivial &&
F::constraints.copyability != constraint_level::trivial) {
if (rhs.meta_.has_value()) {
if constexpr (F::constraints.relocatability ==
constraint_level::trivial) {
std::ranges::uninitialized_copy(rhs.ptr_, ptr_);
meta_ = rhs.meta_;
rhs.meta_.reset();
} else {
proxy_invoke<true, details::copy_dispatch, void(proxy&) && noexcept(
F::constraints.relocatability == constraint_level::nothrow)>(
std::move(rhs), *this);
}
}
}
template <class P>
constexpr proxy(P&& ptr)
noexcept(std::is_nothrow_constructible_v<std::decay_t<P>, P>)
requires(details::ptr_traits<std::decay_t<P>>::applicable &&
std::is_constructible_v<std::decay_t<P>, P>)
: proxy() { initialize<std::decay_t<P>>(std::forward<P>(ptr)); }
template <class P, class... Args>
constexpr explicit proxy(std::in_place_type_t<P>, Args&&... args)
noexcept(std::is_nothrow_constructible_v<P, Args...>)
requires(details::ptr_traits<P>::applicable &&
std::is_constructible_v<P, Args...>)
: proxy() { initialize<P>(std::forward<Args>(args)...); }
template <class P, class U, class... Args>
constexpr explicit proxy(std::in_place_type_t<P>, std::initializer_list<U> il,
Args&&... args)
noexcept(std::is_nothrow_constructible_v<
P, std::initializer_list<U>&, Args...>)
requires(details::ptr_traits<P>::applicable &&
std::is_constructible_v<P, std::initializer_list<U>&, Args...>)
: proxy() { initialize<P>(il, std::forward<Args>(args)...); }
proxy& operator=(std::nullptr_t)
noexcept(F::constraints.destructibility >= constraint_level::nothrow)
requires(F::constraints.destructibility >= constraint_level::nontrivial)
{ reset(); return *this; }
proxy& operator=(const proxy&) noexcept requires(F::constraints.copyability ==
constraint_level::trivial) = default;
proxy& operator=(const proxy& rhs)
noexcept(F::constraints.copyability >= constraint_level::nothrow &&
F::constraints.destructibility >= constraint_level::nothrow)
requires((F::constraints.copyability == constraint_level::nontrivial ||
F::constraints.copyability == constraint_level::nothrow) &&
F::constraints.destructibility >= constraint_level::nontrivial) {
if (this != &rhs) {
if constexpr (F::constraints.copyability == constraint_level::nothrow) {
std::destroy_at(this);
std::construct_at(this, rhs);
} else {
*this = proxy{rhs};
}
}
return *this;
}
proxy& operator=(proxy&& rhs)
noexcept(F::constraints.relocatability >= constraint_level::nothrow &&
F::constraints.destructibility >= constraint_level::nothrow)
requires(F::constraints.relocatability >= constraint_level::nontrivial &&
F::constraints.destructibility >= constraint_level::nontrivial &&
F::constraints.copyability != constraint_level::trivial) {
if (this != &rhs) {
reset();
std::construct_at(this, std::move(rhs));
}
return *this;
}
template <class P>
constexpr proxy& operator=(P&& ptr)
noexcept(std::is_nothrow_constructible_v<std::decay_t<P>, P> &&
F::constraints.destructibility >= constraint_level::nothrow)
requires(details::ptr_traits<std::decay_t<P>>::applicable &&
std::is_constructible_v<std::decay_t<P>, P> &&
F::constraints.destructibility >= constraint_level::nontrivial) {
if constexpr (std::is_nothrow_constructible_v<std::decay_t<P>, P>) {
std::destroy_at(this);
initialize<std::decay_t<P>>(std::forward<P>(ptr));
} else {
*this = proxy{std::forward<P>(ptr)};
}
return *this;
}
~proxy() requires(F::constraints.destructibility == constraint_level::trivial)
= default;
~proxy() noexcept(F::constraints.destructibility == constraint_level::nothrow)
requires(F::constraints.destructibility == constraint_level::nontrivial ||
F::constraints.destructibility == constraint_level::nothrow) {
if (meta_.has_value()) {
proxy_invoke<true, details::destroy_dispatch, void() noexcept(