You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
291 lines
8.4 KiB
291 lines
8.4 KiB
// functional_hash.h header -*- C++ -*-
|
|
|
|
// Copyright (C) 2007-2021 Free Software Foundation, Inc.
|
|
//
|
|
// This file is part of the GNU ISO C++ Library. This library is free
|
|
// software; you can redistribute it and/or modify it under the
|
|
// terms of the GNU General Public License as published by the
|
|
// Free Software Foundation; either version 3, or (at your option)
|
|
// any later version.
|
|
|
|
// This library is distributed in the hope that it will be useful,
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
// GNU General Public License for more details.
|
|
|
|
// Under Section 7 of GPL version 3, you are granted additional
|
|
// permissions described in the GCC Runtime Library Exception, version
|
|
// 3.1, as published by the Free Software Foundation.
|
|
|
|
// You should have received a copy of the GNU General Public License and
|
|
// a copy of the GCC Runtime Library Exception along with this program;
|
|
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
|
|
// <http://www.gnu.org/licenses/>.
|
|
|
|
/** @file bits/functional_hash.h
|
|
* This is an internal header file, included by other library headers.
|
|
* Do not attempt to use it directly. @headername{functional}
|
|
*/
|
|
|
|
#ifndef _FUNCTIONAL_HASH_H
|
|
#define _FUNCTIONAL_HASH_H 1
|
|
|
|
#pragma GCC system_header
|
|
|
|
#include <type_traits>
|
|
#include <bits/hash_bytes.h>
|
|
|
|
namespace std _GLIBCXX_VISIBILITY(default)
|
|
{
|
|
_GLIBCXX_BEGIN_NAMESPACE_VERSION
|
|
|
|
/** @defgroup hashes Hashes
|
|
* @ingroup functors
|
|
*
|
|
* Hashing functors taking a variable type and returning a @c std::size_t.
|
|
*
|
|
* @{
|
|
*/
|
|
|
|
template<typename _Result, typename _Arg>
|
|
struct __hash_base
|
|
{
|
|
typedef _Result result_type _GLIBCXX17_DEPRECATED;
|
|
typedef _Arg argument_type _GLIBCXX17_DEPRECATED;
|
|
};
|
|
|
|
/// Primary class template hash.
|
|
template<typename _Tp>
|
|
struct hash;
|
|
|
|
template<typename _Tp, typename = void>
|
|
struct __poison_hash
|
|
{
|
|
static constexpr bool __enable_hash_call = false;
|
|
private:
|
|
// Private rather than deleted to be non-trivially-copyable.
|
|
__poison_hash(__poison_hash&&);
|
|
~__poison_hash();
|
|
};
|
|
|
|
template<typename _Tp>
|
|
struct __poison_hash<_Tp, __void_t<decltype(hash<_Tp>()(declval<_Tp>()))>>
|
|
{
|
|
static constexpr bool __enable_hash_call = true;
|
|
};
|
|
|
|
// Helper struct for SFINAE-poisoning non-enum types.
|
|
template<typename _Tp, bool = is_enum<_Tp>::value>
|
|
struct __hash_enum
|
|
{
|
|
private:
|
|
// Private rather than deleted to be non-trivially-copyable.
|
|
__hash_enum(__hash_enum&&);
|
|
~__hash_enum();
|
|
};
|
|
|
|
// Helper struct for hash with enum types.
|
|
template<typename _Tp>
|
|
struct __hash_enum<_Tp, true> : public __hash_base<size_t, _Tp>
|
|
{
|
|
size_t
|
|
operator()(_Tp __val) const noexcept
|
|
{
|
|
using __type = typename underlying_type<_Tp>::type;
|
|
return hash<__type>{}(static_cast<__type>(__val));
|
|
}
|
|
};
|
|
|
|
/// Primary class template hash, usable for enum types only.
|
|
// Use with non-enum types still SFINAES.
|
|
template<typename _Tp>
|
|
struct hash : __hash_enum<_Tp>
|
|
{ };
|
|
|
|
/// Partial specializations for pointer types.
|
|
template<typename _Tp>
|
|
struct hash<_Tp*> : public __hash_base<size_t, _Tp*>
|
|
{
|
|
size_t
|
|
operator()(_Tp* __p) const noexcept
|
|
{ return reinterpret_cast<size_t>(__p); }
|
|
};
|
|
|
|
// Explicit specializations for integer types.
|
|
#define _Cxx_hashtable_define_trivial_hash(_Tp) \
|
|
template<> \
|
|
struct hash<_Tp> : public __hash_base<size_t, _Tp> \
|
|
{ \
|
|
size_t \
|
|
operator()(_Tp __val) const noexcept \
|
|
{ return static_cast<size_t>(__val); } \
|
|
};
|
|
|
|
/// Explicit specialization for bool.
|
|
_Cxx_hashtable_define_trivial_hash(bool)
|
|
|
|
/// Explicit specialization for char.
|
|
_Cxx_hashtable_define_trivial_hash(char)
|
|
|
|
/// Explicit specialization for signed char.
|
|
_Cxx_hashtable_define_trivial_hash(signed char)
|
|
|
|
/// Explicit specialization for unsigned char.
|
|
_Cxx_hashtable_define_trivial_hash(unsigned char)
|
|
|
|
/// Explicit specialization for wchar_t.
|
|
_Cxx_hashtable_define_trivial_hash(wchar_t)
|
|
|
|
#ifdef _GLIBCXX_USE_CHAR8_T
|
|
/// Explicit specialization for char8_t.
|
|
_Cxx_hashtable_define_trivial_hash(char8_t)
|
|
#endif
|
|
|
|
/// Explicit specialization for char16_t.
|
|
_Cxx_hashtable_define_trivial_hash(char16_t)
|
|
|
|
/// Explicit specialization for char32_t.
|
|
_Cxx_hashtable_define_trivial_hash(char32_t)
|
|
|
|
/// Explicit specialization for short.
|
|
_Cxx_hashtable_define_trivial_hash(short)
|
|
|
|
/// Explicit specialization for int.
|
|
_Cxx_hashtable_define_trivial_hash(int)
|
|
|
|
/// Explicit specialization for long.
|
|
_Cxx_hashtable_define_trivial_hash(long)
|
|
|
|
/// Explicit specialization for long long.
|
|
_Cxx_hashtable_define_trivial_hash(long long)
|
|
|
|
/// Explicit specialization for unsigned short.
|
|
_Cxx_hashtable_define_trivial_hash(unsigned short)
|
|
|
|
/// Explicit specialization for unsigned int.
|
|
_Cxx_hashtable_define_trivial_hash(unsigned int)
|
|
|
|
/// Explicit specialization for unsigned long.
|
|
_Cxx_hashtable_define_trivial_hash(unsigned long)
|
|
|
|
/// Explicit specialization for unsigned long long.
|
|
_Cxx_hashtable_define_trivial_hash(unsigned long long)
|
|
|
|
#ifdef __GLIBCXX_TYPE_INT_N_0
|
|
_Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_0)
|
|
_Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_0 unsigned)
|
|
#endif
|
|
#ifdef __GLIBCXX_TYPE_INT_N_1
|
|
_Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_1)
|
|
_Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_1 unsigned)
|
|
#endif
|
|
#ifdef __GLIBCXX_TYPE_INT_N_2
|
|
_Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_2)
|
|
_Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_2 unsigned)
|
|
#endif
|
|
#ifdef __GLIBCXX_TYPE_INT_N_3
|
|
_Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_3)
|
|
_Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_3 unsigned)
|
|
#endif
|
|
|
|
#undef _Cxx_hashtable_define_trivial_hash
|
|
|
|
struct _Hash_impl
|
|
{
|
|
static size_t
|
|
hash(const void* __ptr, size_t __clength,
|
|
size_t __seed = static_cast<size_t>(0xc70f6907UL))
|
|
{ return _Hash_bytes(__ptr, __clength, __seed); }
|
|
|
|
template<typename _Tp>
|
|
static size_t
|
|
hash(const _Tp& __val)
|
|
{ return hash(&__val, sizeof(__val)); }
|
|
|
|
template<typename _Tp>
|
|
static size_t
|
|
__hash_combine(const _Tp& __val, size_t __hash)
|
|
{ return hash(&__val, sizeof(__val), __hash); }
|
|
};
|
|
|
|
// A hash function similar to FNV-1a (see PR59406 for how it differs).
|
|
struct _Fnv_hash_impl
|
|
{
|
|
static size_t
|
|
hash(const void* __ptr, size_t __clength,
|
|
size_t __seed = static_cast<size_t>(2166136261UL))
|
|
{ return _Fnv_hash_bytes(__ptr, __clength, __seed); }
|
|
|
|
template<typename _Tp>
|
|
static size_t
|
|
hash(const _Tp& __val)
|
|
{ return hash(&__val, sizeof(__val)); }
|
|
|
|
template<typename _Tp>
|
|
static size_t
|
|
__hash_combine(const _Tp& __val, size_t __hash)
|
|
{ return hash(&__val, sizeof(__val), __hash); }
|
|
};
|
|
|
|
/// Specialization for float.
|
|
template<>
|
|
struct hash<float> : public __hash_base<size_t, float>
|
|
{
|
|
size_t
|
|
operator()(float __val) const noexcept
|
|
{
|
|
// 0 and -0 both hash to zero.
|
|
return __val != 0.0f ? std::_Hash_impl::hash(__val) : 0;
|
|
}
|
|
};
|
|
|
|
/// Specialization for double.
|
|
template<>
|
|
struct hash<double> : public __hash_base<size_t, double>
|
|
{
|
|
size_t
|
|
operator()(double __val) const noexcept
|
|
{
|
|
// 0 and -0 both hash to zero.
|
|
return __val != 0.0 ? std::_Hash_impl::hash(__val) : 0;
|
|
}
|
|
};
|
|
|
|
/// Specialization for long double.
|
|
template<>
|
|
struct hash<long double>
|
|
: public __hash_base<size_t, long double>
|
|
{
|
|
_GLIBCXX_PURE size_t
|
|
operator()(long double __val) const noexcept;
|
|
};
|
|
|
|
#if __cplusplus >= 201703L
|
|
template<>
|
|
struct hash<nullptr_t> : public __hash_base<size_t, nullptr_t>
|
|
{
|
|
size_t
|
|
operator()(nullptr_t) const noexcept
|
|
{ return 0; }
|
|
};
|
|
#endif
|
|
|
|
/// @} group hashes
|
|
|
|
// Hint about performance of hash functor. If not fast the hash-based
|
|
// containers will cache the hash code.
|
|
// Default behavior is to consider that hashers are fast unless specified
|
|
// otherwise.
|
|
template<typename _Hash>
|
|
struct __is_fast_hash : public std::true_type
|
|
{ };
|
|
|
|
template<>
|
|
struct __is_fast_hash<hash<long double>> : public std::false_type
|
|
{ };
|
|
|
|
_GLIBCXX_END_NAMESPACE_VERSION
|
|
} // namespace
|
|
|
|
#endif // _FUNCTIONAL_HASH_H
|