61 lines
1.7 KiB
C++
61 lines
1.7 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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#pragma once
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#include <sal/config.h>
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#include <compare>
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#include <concepts>
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#include <cstdint>
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#include <cstring>
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#include <limits>
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#include <config_global.h>
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namespace o3tl
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{
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// An approximation of C++20 <compare> std::strong_order that should work at least for IEC559 float
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// and double on platforms that have correspondingly-sized std::int32_t and std::int64_t:
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#if HAVE_CPP_STRONG_ORDER
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inline constexpr auto strong_order = std::strong_order;
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#else
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namespace detail
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{
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template<typename To, typename From> To bit_cast(From val) requires (sizeof (To) == sizeof (From)) {
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char buf alignas(To)[sizeof (From)];
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std::memcpy(buf, &val, sizeof (From));
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return *reinterpret_cast<To const *>(buf);
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}
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struct strong_order
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{
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template <typename T> auto operator ()(T x, T y) const
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requires std::same_as<T, float> && std::numeric_limits<T>::is_iec559
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{
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return bit_cast<std::int32_t>(x) <=> bit_cast<std::int32_t>(y);
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}
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template <typename T> auto operator ()(T x, T y) const
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requires std::same_as<T, double> && std::numeric_limits<T>::is_iec559
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{
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return bit_cast<std::int64_t>(x) <=> bit_cast<std::int64_t>(y);
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}
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};
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}
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inline constexpr auto strong_order = detail::strong_order();
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#endif
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}
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/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
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