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794e86b99d
This simplifies determining what the byte size of the template type is, so we can write a specific implementation for 32 and 64 bit seeds for hash_combine. Change-Id: Icd68e4618151957ecc00585dd521adf11fe3931a Reviewed-on: https://gerrit.libreoffice.org/c/core/+/182266 Tested-by: Jenkins Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>
55 lines
1.6 KiB
C++
55 lines
1.6 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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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 <cstddef>
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#include <functional>
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#include <type_traits>
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#include <o3tl/concepts.hxx>
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namespace o3tl
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{
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template <typename T, type_32_bit N>
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inline void hash_combine(N& nSeed, T const* pValue, size_t nCount)
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{
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static_assert(sizeof(nSeed) == 4);
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for (size_t i = 0; i < nCount; ++i)
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{
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nSeed ^= std::hash<T>{}(*pValue) + 0x9E3779B9u + (nSeed << 6) + (nSeed >> 2);
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++pValue;
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}
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}
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template <typename T, type_32_bit N> inline void hash_combine(N& nSeed, T const& nValue)
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{
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static_assert(sizeof(nSeed) == 4);
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nSeed ^= std::hash<T>{}(nValue) + 0x9E3779B9u + (nSeed << 6) + (nSeed >> 2);
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}
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template <typename T, type_64_bit N>
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inline void hash_combine(N& nSeed, T const* pValue, size_t nCount)
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{
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static_assert(sizeof(nSeed) == 8);
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for (size_t i = 0; i < nCount; ++i)
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{
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nSeed ^= std::hash<T>{}(*pValue) + 0x9E3779B97F4A7C15llu + (nSeed << 12) + (nSeed >> 4);
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++pValue;
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}
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}
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template <typename T, type_64_bit N> inline void hash_combine(N& nSeed, T const& nValue)
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{
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static_assert(sizeof(nSeed) == 8);
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nSeed ^= std::hash<T>{}(nValue) + 0x9E3779B97F4A7C15llu + (nSeed << 12) + (nSeed >> 4);
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}
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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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