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Fix hash_combine_impl to only test for a specific bit width and not for concrete types

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This commit is contained in:
Peter Dimov
2021-08-10 18:38:41 +03:00
parent b55fbc9252
commit 21f2b5e1db
1 changed files with 40 additions and 35 deletions
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75
include/boost/container_hash/hash.hpp
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@@ -26,6 +26,7 @@
#include <boost/type_traits/is_integral.hpp>
#include <boost/core/enable_if.hpp>
#include <boost/cstdint.hpp>
#include <climits>
#if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
#include <boost/type_traits/is_pointer.hpp>
@@ -307,52 +308,56 @@ namespace boost
return seed;
}
template <typename SizeT>
inline void hash_combine_impl(SizeT& seed, SizeT value)
template<int Bits> struct hash_combine_impl
{
seed ^= value + 0x9e3779b9 + (seed<<6) + (seed>>2);
}
template <typename SizeT>
inline static SizeT fn(SizeT seed, SizeT value)
{
seed ^= value + 0x9e3779b9 + (seed<<6) + (seed>>2);
return seed;
}
};
inline void hash_combine_impl(boost::uint32_t& h1,
boost::uint32_t k1)
template<> struct hash_combine_impl<32>
{
const uint32_t c1 = 0xcc9e2d51;
const uint32_t c2 = 0x1b873593;
inline static boost::uint32_t fn(boost::uint32_t h1, boost::uint32_t k1)
{
const boost::uint32_t c1 = 0xcc9e2d51;
const boost::uint32_t c2 = 0x1b873593;
k1 *= c1;
k1 = BOOST_FUNCTIONAL_HASH_ROTL32(k1,15);
k1 *= c2;
k1 *= c1;
k1 = BOOST_FUNCTIONAL_HASH_ROTL32(k1,15);
k1 *= c2;
h1 ^= k1;
h1 = BOOST_FUNCTIONAL_HASH_ROTL32(h1,13);
h1 = h1*5+0xe6546b64;
}
h1 ^= k1;
h1 = BOOST_FUNCTIONAL_HASH_ROTL32(h1,13);
h1 = h1*5+0xe6546b64;
return h1;
}
};
// Don't define 64-bit hash combine on platforms without 64 bit integers,
// and also not for 32-bit gcc as it warns about the 64-bit constant.
#if !defined(BOOST_NO_INT64_T) && \
!(defined(__GNUC__) && ULONG_MAX == 0xffffffff)
inline void hash_combine_impl(boost::uint64_t& h,
boost::uint64_t k)
template<> struct hash_combine_impl<64>
{
const boost::uint64_t m = UINT64_C(0xc6a4a7935bd1e995);
const int r = 47;
inline static boost::uint64_t fn(boost::uint64_t h, boost::uint64_t k)
{
const boost::uint64_t m = (boost::uint64_t(0xc6a4a793) << 32) + 0x5bd1e995;
const int r = 47;
k *= m;
k ^= k >> r;
k *= m;
k *= m;
k ^= k >> r;
k *= m;
h ^= k;
h *= m;
h ^= k;
h *= m;
// Completely arbitrary number, to prevent 0's
// from hashing to 0.
h += 0xe6546b64;
}
// Completely arbitrary number, to prevent 0's
// from hashing to 0.
h += 0xe6546b64;
#endif // BOOST_NO_INT64_T
return h;
}
};
}
template <typename T>
@@ -413,7 +418,7 @@ namespace boost
inline void hash_combine(std::size_t& seed, T const& v)
{
boost::hash<T> hasher;
return boost::hash_detail::hash_combine_impl(seed, hasher(v));
seed = boost::hash_detail::hash_combine_impl<sizeof(std::size_t) * CHAR_BIT>::fn(seed, hasher(v));
}
#if defined(BOOST_MSVC)