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// Copyright (C) 2024 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 Q26NUMERIC_H
#define Q26NUMERIC_H
#include <QtCore/qglobal.h>
//
// 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.
//
#include <numeric>
#include <limits>
#include <type_traits>
QT_BEGIN_NAMESPACE
namespace q26 {
// Like std::saturate_cast
#ifdef __cpp_lib_saturation_arithmetic
using std::saturate_cast;
#else
template <typename To, typename From>
constexpr auto saturate_cast(From x)
{
static_assert(std::is_integral_v<To>);
static_assert(std::is_integral_v<From>);
[[maybe_unused]]
constexpr auto Lo = (std::numeric_limits<To>::min)();
constexpr auto Hi = (std::numeric_limits<To>::max)();
if constexpr (std::is_signed_v<From> == std::is_signed_v<To>) {
// same signedness, we can accept regular integer conversion rules
return x < Lo ? Lo :
x > Hi ? Hi :
/*else*/ To(x);
} else {
if constexpr (std::is_signed_v<From>) { // ie. !is_signed_v<To>
if (x < From{0})
return To{0};
}
// from here on, x >= 0
using FromU = std::make_unsigned_t<From>;
using ToU = std::make_unsigned_t<To>;
return FromU(x) > ToU(Hi) ? Hi : To(x); // assumes Hi >= 0
}
}
#endif // __cpp_lib_saturation_arithmetic
} // namespace q26
QT_END_NAMESPACE
#endif /* Q26NUMERIC_H */
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