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// Copyright (C) 2023 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#ifndef Q23UTILITY_H
#define Q23UTILITY_H
#include <QtCore/qtconfigmacros.h>
#include <utility>
//
// W A R N I N G
// -------------
//
// This file is not part of the Qt API. Types and functions defined in this
// file can reliably be replaced by their std counterparts, once available.
// You may use these definitions in your own code, but be aware that we
// will remove them once Qt depends on the C++ version that supports
// them in namespace std. There will be NO deprecation warning, the
// definitions will JUST go away.
//
// If you can't agree to these terms, don't use these definitions!
//
// We mean it.
//
QT_BEGIN_NAMESPACE
namespace q23 {
// like std::forward_like
#ifdef __cpp_lib_forward_like
using std::forward_like;
#else
namespace _detail {
// [forward]/6.1 COPY_CONST
template <typename A, typename B>
using copy_const_t = std::conditional_t<
std::is_const_v<A>, const B,
/* else */ B
>;
// [forward]/6.2 OVERRIDE_REF
template <typename A, typename B>
using override_ref_t = std::conditional_t<
std::is_rvalue_reference_v<A>, std::remove_reference_t<B>&&,
/* else */ B&
>;
// [forward]/6.3 "V"
template <typename T, typename U>
using forward_like_ret_t = override_ref_t<
T&&,
copy_const_t<
std::remove_reference_t<T>,
std::remove_reference_t<U>
>
>;
} // namespace detail
// http://eel.is/c++draft/forward#lib:forward_like
template <class T, class U>
[[nodiscard]] constexpr auto forward_like(U &&x) noexcept
-> _detail::forward_like_ret_t<T, U>
{
using V = _detail::forward_like_ret_t<T, U>;
return static_cast<V>(x);
}
#endif // __cpp_lib_forward_like
} // namespace q23
QT_END_NAMESPACE
#endif /* Q23UTILITY_H */
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