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201 lines
3.4 KiB
C++
201 lines
3.4 KiB
C++
//
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// Hash.h
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//
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// Library: Foundation
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// Package: Hashing
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// Module: Hash
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//
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// Definition of the Hash class.
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//
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// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
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// and Contributors.
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//
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// hashRange Copyright 2005-2014 Daniel James.
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// (Extracted from Boost 1.75.0 lib and adapted for poco on 2021-03-31)
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//
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// SPDX-License-Identifier: BSL-1.0
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//
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#ifndef Foundation_Hash_INCLUDED
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#define Foundation_Hash_INCLUDED
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#include "Poco/Foundation.h"
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#include "Poco/Types.h"
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#include <cstddef>
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#if defined(_MSC_VER)
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# define POCO_HASH_ROTL32(x, r) _rotl(x,r)
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#else
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# define POCO_HASH_ROTL32(x, r) (x << r) | (x >> (32 - r))
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#endif
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namespace Poco {
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std::size_t Foundation_API hash(Int8 n);
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std::size_t Foundation_API hash(UInt8 n);
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std::size_t Foundation_API hash(Int16 n);
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std::size_t Foundation_API hash(UInt16 n);
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std::size_t Foundation_API hash(Int32 n);
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std::size_t Foundation_API hash(UInt32 n);
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std::size_t Foundation_API hash(Int64 n);
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std::size_t Foundation_API hash(UInt64 n);
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std::size_t Foundation_API hash(const std::string& str);
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template <class T>
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struct Hash
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/// A generic hash function.
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{
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std::size_t operator () (T value) const
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/// Returns the hash for the given value.
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{
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return Poco::hash(value);
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}
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};
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//
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// inlines
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//
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inline std::size_t hash(Int8 n)
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{
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return static_cast<std::size_t>(n)*2654435761U;
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}
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inline std::size_t hash(UInt8 n)
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{
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return static_cast<std::size_t>(n)*2654435761U;
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}
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inline std::size_t hash(Int16 n)
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{
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return static_cast<std::size_t>(n)*2654435761U;
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}
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inline std::size_t hash(UInt16 n)
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{
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return static_cast<std::size_t>(n)*2654435761U;
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}
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inline std::size_t hash(Int32 n)
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{
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return static_cast<std::size_t>(n)*2654435761U;
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}
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inline std::size_t hash(UInt32 n)
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{
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return static_cast<std::size_t>(n)*2654435761U;
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}
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inline std::size_t hash(Int64 n)
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{
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return static_cast<std::size_t>(n)*2654435761U;
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}
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inline std::size_t hash(UInt64 n)
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{
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return static_cast<std::size_t>(n)*2654435761U;
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}
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namespace Impl {
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template <typename SizeT>
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inline void hashCombine(SizeT& seed, SizeT value)
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{
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seed ^= value + 0x9e3779b9 + (seed<<6) + (seed>>2);
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}
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inline void hashCombine(Poco::UInt32& h1, Poco::UInt32 k1)
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{
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const uint32_t c1 = 0xcc9e2d51;
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const uint32_t c2 = 0x1b873593;
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k1 *= c1;
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k1 = POCO_HASH_ROTL32(k1,15);
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k1 *= c2;
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h1 ^= k1;
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h1 = POCO_HASH_ROTL32(h1,13);
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h1 = h1*5+0xe6546b64;
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}
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#if defined(POCO_PTR_IS_64_BIT) && !(defined(__GNUC__) && ULONG_MAX == 0xffffffff)
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inline void hashCombine(Poco::UInt64& h, Poco::UInt64 k)
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{
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const Poco::UInt64 m = UINT64_C(0xc6a4a7935bd1e995);
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const int r = 47;
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k *= m;
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k ^= k >> r;
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k *= m;
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h ^= k;
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h *= m;
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// Completely arbitrary number, to
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// prevent zeros from hashing to 0.
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h += 0xe6546b64;
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}
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#endif // POCO_PTR_IS_64_BIT
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} // namespace Impl
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template <class T>
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inline void hashCombine(std::size_t& seed, T const& v)
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{
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Hash<T> hasher;
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Impl::hashCombine(seed, hasher(v));
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}
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template <class It>
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inline std::size_t hashRange(It first, It last)
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{
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std::size_t seed = 0;
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for(; first != last; ++first)
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{
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hashCombine<typename std::iterator_traits<It>::value_type>(seed, *first);
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}
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return seed;
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}
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template <class It>
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inline void hashRange(std::size_t& seed, It first, It last)
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{
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for(; first != last; ++first)
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{
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hashCombine<typename std::iterator_traits<It>::value_type>(seed, *first);
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}
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}
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} // namespace Poco
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#endif // Foundation_Hash_INCLUDED
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