diff options
Diffstat (limited to 'src/corelib/global/q20memory.h')
| -rw-r--r-- | src/corelib/global/q20memory.h | 59 |
1 files changed, 53 insertions, 6 deletions
diff --git a/src/corelib/global/q20memory.h b/src/corelib/global/q20memory.h index 438613db48..008f4ddeb2 100644 --- a/src/corelib/global/q20memory.h +++ b/src/corelib/global/q20memory.h @@ -1,13 +1,17 @@ // Copyright (C) 2023 The Qt Company Ltd. +// Copyright (C) 2020 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Marc Mutz <marc.mutz@kdab.com> // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only #ifndef Q20MEMORY_H #define Q20MEMORY_H -#include <QtCore/qxptype_traits.h> +#include <QtCore/qtconfigmacros.h> #include <memory> +#include <type_traits> +#include <utility> + // // W A R N I N G // ------------- @@ -26,19 +30,62 @@ QT_BEGIN_NAMESPACE +// like std::construct_at (but not whitelisted for constexpr) namespace q20 { - -#if __cplusplus >= 202002L +#ifdef __cpp_lib_constexpr_dynamic_alloc using std::construct_at; #else template <typename T, typename... Args, typename Enable = std::void_t<decltype(::new (std::declval<void *>()) T(std::declval<Args>()...))> > - static void construct_at(T *ptr, Args && ... args) +T *construct_at(T *ptr, Args && ... args) { - ::new (const_cast<void*>(static_cast<const volatile void*>(ptr))) T(std::forward<Args>(args)...); + return ::new (const_cast<void *>(static_cast<const volatile void *>(ptr))) + T(std::forward<Args>(args)...); +} +#endif // __cpp_lib_constexpr_dynamic_alloc +} // namespace q20 + + +namespace q20 { +// like std::to_address +#ifdef __cpp_lib_to_address +using std::to_address; +#else +// http://eel.is/c++draft/pointer.conversion +template <typename T> +constexpr T *to_address(T *p) noexcept { + // http://eel.is/c++draft/pointer.conversion#1: + // Mandates: T is not a function type. + static_assert(!std::is_function_v<T>, "to_address must not be used on function types"); + return p; } -#endif + +template <typename Ptr, typename std::enable_if_t<!std::is_pointer_v<Ptr>, bool> = true> +constexpr auto to_address(const Ptr &ptr) noexcept; // fwd declared + +namespace detail { + // http://eel.is/c++draft/pointer.conversion#3 + template <typename Ptr, typename = void> + struct to_address_helper { + static auto get(const Ptr &ptr) noexcept + { return q20::to_address(ptr.operator->()); } + }; + template <typename Ptr> + struct to_address_helper<Ptr, std::void_t< + decltype(std::pointer_traits<Ptr>::to_address(std::declval<const Ptr&>())) + >> + { + static auto get(const Ptr &ptr) noexcept + { return std::pointer_traits<Ptr>::to_address(ptr); } + }; +} // namespace detail + +template <typename Ptr, typename std::enable_if_t<!std::is_pointer_v<Ptr>, bool>> +constexpr auto to_address(const Ptr &ptr) noexcept +{ return detail::to_address_helper<Ptr>::get(ptr); } + +#endif // __cpp_lib_to_address } // namespace q20 QT_END_NAMESPACE |