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Simplify hash_value for integrals

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This commit is contained in:
Peter Dimov
2021-10-16 17:29:02 +03:00
parent 4e11c855cb
commit 2fc970b6ae
4 changed files with 45 additions and 141 deletions
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177
include/boost/container_hash/hash.hpp
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@@ -20,6 +20,8 @@
#include <boost/container_hash/detail/hash_float.hpp>
#include <boost/type_traits/is_enum.hpp>
#include <boost/type_traits/is_integral.hpp>
#include <boost/type_traits/is_floating_point.hpp>
#include <boost/type_traits/make_unsigned.hpp>
#include <boost/core/enable_if.hpp>
#include <boost/limits.hpp>
#include <boost/cstdint.hpp>
@@ -74,91 +76,20 @@ namespace boost
typedef T argument_type;
typedef std::size_t result_type;
};
struct enable_hash_value { typedef std::size_t type; };
template <typename T> struct basic_numbers {};
template <typename T> struct long_numbers;
template <typename T> struct ulong_numbers;
template <typename T> struct float_numbers {};
template <> struct basic_numbers<bool> :
boost::hash_detail::enable_hash_value {};
template <> struct basic_numbers<char> :
boost::hash_detail::enable_hash_value {};
template <> struct basic_numbers<unsigned char> :
boost::hash_detail::enable_hash_value {};
template <> struct basic_numbers<signed char> :
boost::hash_detail::enable_hash_value {};
template <> struct basic_numbers<short> :
boost::hash_detail::enable_hash_value {};
template <> struct basic_numbers<unsigned short> :
boost::hash_detail::enable_hash_value {};
template <> struct basic_numbers<int> :
boost::hash_detail::enable_hash_value {};
template <> struct basic_numbers<unsigned int> :
boost::hash_detail::enable_hash_value {};
template <> struct basic_numbers<long> :
boost::hash_detail::enable_hash_value {};
template <> struct basic_numbers<unsigned long> :
boost::hash_detail::enable_hash_value {};
#if !defined(BOOST_NO_INTRINSIC_WCHAR_T)
template <> struct basic_numbers<wchar_t> :
boost::hash_detail::enable_hash_value {};
#endif
#if !defined(BOOST_NO_CXX11_CHAR16_T)
template <> struct basic_numbers<char16_t> :
boost::hash_detail::enable_hash_value {};
#endif
#if !defined(BOOST_NO_CXX11_CHAR32_T)
template <> struct basic_numbers<char32_t> :
boost::hash_detail::enable_hash_value {};
#endif
// long_numbers is defined like this to allow for separate
// specialization for long_long and int128_type, in case
// they conflict.
template <typename T> struct long_numbers2 {};
template <typename T> struct ulong_numbers2 {};
template <typename T> struct long_numbers : long_numbers2<T> {};
template <typename T> struct ulong_numbers : ulong_numbers2<T> {};
#if !defined(BOOST_NO_LONG_LONG)
template <> struct long_numbers<boost::long_long_type> :
boost::hash_detail::enable_hash_value {};
template <> struct ulong_numbers<boost::ulong_long_type> :
boost::hash_detail::enable_hash_value {};
#endif
#if defined(BOOST_HAS_INT128)
template <> struct long_numbers2<boost::int128_type> :
boost::hash_detail::enable_hash_value {};
template <> struct ulong_numbers2<boost::uint128_type> :
boost::hash_detail::enable_hash_value {};
#endif
template <> struct float_numbers<float> :
boost::hash_detail::enable_hash_value {};
template <> struct float_numbers<double> :
boost::hash_detail::enable_hash_value {};
template <> struct float_numbers<long double> :
boost::hash_detail::enable_hash_value {};
}
template <typename T>
typename boost::hash_detail::basic_numbers<T>::type hash_value(T);
template <typename T>
typename boost::hash_detail::long_numbers<T>::type hash_value(T);
template <typename T>
typename boost::hash_detail::ulong_numbers<T>::type hash_value(T);
typename boost::enable_if<boost::is_integral<T>, std::size_t>::type
hash_value(T);
template <typename T>
typename boost::enable_if<boost::is_enum<T>, std::size_t>::type
hash_value(T);
template <typename T>
typename boost::enable_if<boost::is_floating_point<T>, std::size_t>::type
hash_value(T);
template <class T> std::size_t hash_value(T* const&);
template< class T, unsigned N >
@@ -177,9 +108,6 @@ namespace boost
std::basic_string_view<Ch, std::char_traits<Ch> > const&);
#endif
template <typename T>
typename boost::hash_detail::float_numbers<T>::type hash_value(T);
#if !defined(BOOST_NO_CXX17_HDR_OPTIONAL)
template <typename T>
std::size_t hash_value(std::optional<T> const&);
@@ -204,46 +132,33 @@ namespace boost
namespace hash_detail
{
template <class T>
inline std::size_t hash_value_signed(T val)
template<class T, bool bigger_than_size_t, bool size_t_64> struct hash_integral_impl;
template<class T, bool size_t_64> struct hash_integral_impl<T, false, size_t_64>
{
const unsigned int size_t_bits = std::numeric_limits<std::size_t>::digits;
// ceiling(std::numeric_limits<T>::digits / size_t_bits) - 1
const int length = (std::numeric_limits<T>::digits - 1)
/ static_cast<int>(size_t_bits);
static std::size_t fn( T v )
{
return static_cast<std::size_t>( v );
}
};
std::size_t seed = 0;
T positive = val < 0 ? -1 - val : val;
// Hopefully, this loop can be unrolled.
for(unsigned int i = length * size_t_bits; i > 0; i -= size_t_bits)
{
seed ^= (std::size_t) (positive >> i) + (seed<<6) + (seed>>2);
}
seed ^= (std::size_t) val + (seed<<6) + (seed>>2);
return seed;
}
template <class T>
inline std::size_t hash_value_unsigned(T val)
template<class T> struct hash_integral_impl<T, true, false>
{
const unsigned int size_t_bits = std::numeric_limits<std::size_t>::digits;
// ceiling(std::numeric_limits<T>::digits / size_t_bits) - 1
const int length = (std::numeric_limits<T>::digits - 1)
/ static_cast<int>(size_t_bits);
static std::size_t fn( T v )
{
// 4294967291 = 2^32-5, biggest prime under 2^32
return static_cast<std::size_t>( static_cast<typename boost::make_unsigned<T>::type>( v ) % 4294967291 );
}
};
std::size_t seed = 0;
// Hopefully, this loop can be unrolled.
for(unsigned int i = length * size_t_bits; i > 0; i -= size_t_bits)
{
seed ^= (std::size_t) (val >> i) + (seed<<6) + (seed>>2);
}
seed ^= (std::size_t) val + (seed<<6) + (seed>>2);
return seed;
}
template<class T> struct hash_integral_impl<T, true, true>
{
static std::size_t fn( T v )
{
// 18446744073709551557ULL = 2^64-59, biggest prime under 2^64
return static_cast<std::size_t>( static_cast<typename boost::make_unsigned<T>::type>( v ) % 18446744073709551557ULL );
}
};
template<int Bits> struct hash_combine_impl
{
@@ -298,21 +213,10 @@ namespace boost
}
template <typename T>
typename boost::hash_detail::basic_numbers<T>::type hash_value(T v)
typename boost::enable_if<boost::is_integral<T>, std::size_t>::type
hash_value(T v)
{
return static_cast<std::size_t>(v);
}
template <typename T>
typename boost::hash_detail::long_numbers<T>::type hash_value(T v)
{
return hash_detail::hash_value_signed(v);
}
template <typename T>
typename boost::hash_detail::ulong_numbers<T>::type hash_value(T v)
{
return hash_detail::hash_value_unsigned(v);
return hash_detail::hash_integral_impl<T, (sizeof(T) > sizeof(std::size_t)), (sizeof(std::size_t) * CHAR_BIT >= 64)>::fn( v );
}
template <typename T>
@@ -322,6 +226,13 @@ namespace boost
return static_cast<std::size_t>(v);
}
template <typename T>
typename boost::enable_if<boost::is_floating_point<T>, std::size_t>::type
hash_value(T v)
{
return boost::hash_detail::float_hash_value(v);
}
// Implementation by Alberto Barbati and Dave Harris.
template <class T> std::size_t hash_value(T* const& v)
{
@@ -427,12 +338,6 @@ namespace boost
}
#endif
template <typename T>
typename boost::hash_detail::float_numbers<T>::type hash_value(T v)
{
return boost::hash_detail::float_hash_value(v);
}
#if !defined(BOOST_NO_CXX17_HDR_OPTIONAL)
template <typename T>
inline std::size_t hash_value(std::optional<T> const& v) {

2
test/hash_complex_test.cpp
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@@ -35,7 +35,7 @@ int main() {}
#endif
#endif
#if defined(__GNUC__) && !defined(BOOST_INTEL_CXX_VERSION)
#if ( defined(__GNUC__) || defined(__clang__) ) && !defined(BOOST_INTEL_CXX_VERSION)
#pragma GCC diagnostic ignored "-Wfloat-equal"
#endif

2
test/hash_float_test.hpp
View File

@@ -30,7 +30,7 @@
#endif
#endif
#if defined(__GNUC__) && !defined(BOOST_INTEL_CXX_VERSION)
#if ( defined(__GNUC__) || defined(__clang__) ) && !defined(BOOST_INTEL_CXX_VERSION)
#pragma GCC diagnostic ignored "-Wfloat-equal"
#endif

5
test/hash_number_test.cpp
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@@ -26,7 +26,7 @@
#pragma warning(disable:4310) // cast truncates constant value
#endif
#if defined(__GNUC__) && !defined(BOOST_INTEL_CXX_VERSION)
#if ( defined(__GNUC__) || defined(__clang__) ) && !defined(BOOST_INTEL_CXX_VERSION)
#pragma GCC diagnostic ignored "-Wfloat-equal"
#endif
@@ -37,8 +37,7 @@ void numeric_extra_tests(typename
{
typedef boost::hash_detail::limits<T> limits;
if(limits::is_signed ||
limits::digits <= boost::hash_detail::limits<std::size_t>::digits)
if(limits::digits <= boost::hash_detail::limits<std::size_t>::digits)
{
BOOST_TEST(BOOST_HASH_TEST_NAMESPACE::hash_value(T(-5)) == (std::size_t)T(-5));
}