1 // functional_hash.h header -*- C++ -*-
3 // Copyright (C) 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
25 /** @file bits/functional_hash.h
26 * This is an internal header file, included by other library headers.
27 * Do not attempt to use it directly. @headername{functional}
30 #ifndef _FUNCTIONAL_HASH_H
31 #define _FUNCTIONAL_HASH_H 1
33 #pragma GCC system_header
35 #include <bits/hash_bytes.h>
37 namespace std _GLIBCXX_VISIBILITY(default)
39 _GLIBCXX_BEGIN_NAMESPACE_VERSION
41 /** @defgroup hashes Hashes
44 * Hashing functors taking a variable type and returning a @c std::size_t.
49 template<typename _Result, typename _Arg>
52 typedef _Result result_type;
53 typedef _Arg argument_type;
56 /// Primary class template hash.
57 template<typename _Tp>
58 struct hash : public __hash_base<size_t, _Tp>
61 operator()(_Tp __val) const;
64 /// Partial specializations for pointer types.
65 template<typename _Tp>
66 struct hash<_Tp*> : public __hash_base<size_t, _Tp*>
69 operator()(_Tp* __p) const
70 { return reinterpret_cast<size_t>(__p); }
73 // Explicit specializations for integer types.
74 #define _Cxx_hashtable_define_trivial_hash(_Tp) \
77 hash<_Tp>::operator()(_Tp __val) const \
78 { return static_cast<size_t>(__val); }
80 /// Explicit specialization for bool.
81 _Cxx_hashtable_define_trivial_hash(bool);
83 /// Explicit specialization for char.
84 _Cxx_hashtable_define_trivial_hash(char);
86 /// Explicit specialization for signed char.
87 _Cxx_hashtable_define_trivial_hash(signed char);
89 /// Explicit specialization for unsigned char.
90 _Cxx_hashtable_define_trivial_hash(unsigned char);
92 /// Explicit specialization for wchar_t.
93 _Cxx_hashtable_define_trivial_hash(wchar_t);
95 /// Explicit specialization for char16_t.
96 _Cxx_hashtable_define_trivial_hash(char16_t);
98 /// Explicit specialization for char32_t.
99 _Cxx_hashtable_define_trivial_hash(char32_t);
101 /// Explicit specialization for short.
102 _Cxx_hashtable_define_trivial_hash(short);
104 /// Explicit specialization for int.
105 _Cxx_hashtable_define_trivial_hash(int);
107 /// Explicit specialization for long.
108 _Cxx_hashtable_define_trivial_hash(long);
110 /// Explicit specialization for long long.
111 _Cxx_hashtable_define_trivial_hash(long long);
113 /// Explicit specialization for unsigned short.
114 _Cxx_hashtable_define_trivial_hash(unsigned short);
116 /// Explicit specialization for unsigned int.
117 _Cxx_hashtable_define_trivial_hash(unsigned int);
119 /// Explicit specialization for unsigned long.
120 _Cxx_hashtable_define_trivial_hash(unsigned long);
122 /// Explicit specialization for unsigned long long.
123 _Cxx_hashtable_define_trivial_hash(unsigned long long);
125 #undef _Cxx_hashtable_define_trivial_hash
130 hash(const void* __ptr, size_t __clength,
131 size_t __seed = static_cast<size_t>(0xc70f6907UL))
132 { return _Hash_bytes(__ptr, __clength, __seed); }
134 template<typename _Tp>
136 hash(const _Tp& __val)
137 { return hash(&__val, sizeof(__val)); }
139 template<typename _Tp>
141 __hash_combine(const _Tp& __val, size_t __hash)
142 { return hash(&__val, sizeof(__val), __hash); }
145 struct _Fnv_hash_impl
148 hash(const void* __ptr, size_t __clength,
149 size_t __seed = static_cast<size_t>(2166136261UL))
150 { return _Fnv_hash_bytes(__ptr, __clength, __seed); }
152 template<typename _Tp>
154 hash(const _Tp& __val)
155 { return hash(&__val, sizeof(__val)); }
157 template<typename _Tp>
159 __hash_combine(const _Tp& __val, size_t __hash)
160 { return hash(&__val, sizeof(__val), __hash); }
163 /// Specialization for float.
166 hash<float>::operator()(float __val) const
168 // 0 and -0 both hash to zero.
169 return __val != 0.0f ? std::_Hash_impl::hash(__val) : 0;
172 /// Specialization for double.
175 hash<double>::operator()(double __val) const
177 // 0 and -0 both hash to zero.
178 return __val != 0.0 ? std::_Hash_impl::hash(__val) : 0;
181 /// Specialization for long double.
184 hash<long double>::operator()(long double __val) const;
188 _GLIBCXX_END_NAMESPACE_VERSION
191 #endif // _FUNCTIONAL_HASH_H