libstdc++
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00001 // functional_hash.h header -*- C++ -*- 00002 00003 // Copyright (C) 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc. 00004 // 00005 // This file is part of the GNU ISO C++ Library. This library is free 00006 // software; you can redistribute it and/or modify it under the 00007 // terms of the GNU General Public License as published by the 00008 // Free Software Foundation; either version 3, or (at your option) 00009 // any later version. 00010 00011 // This library is distributed in the hope that it will be useful, 00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 // GNU General Public License for more details. 00015 00016 // Under Section 7 of GPL version 3, you are granted additional 00017 // permissions described in the GCC Runtime Library Exception, version 00018 // 3.1, as published by the Free Software Foundation. 00019 00020 // You should have received a copy of the GNU General Public License and 00021 // a copy of the GCC Runtime Library Exception along with this program; 00022 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00023 // <http://www.gnu.org/licenses/>. 00024 00025 /** @file bits/functional_hash.h 00026 * This is an internal header file, included by other library headers. 00027 * Do not attempt to use it directly. @headername{functional} 00028 */ 00029 00030 #ifndef _FUNCTIONAL_HASH_H 00031 #define _FUNCTIONAL_HASH_H 1 00032 00033 #pragma GCC system_header 00034 00035 #include <bits/hash_bytes.h> 00036 00037 namespace std _GLIBCXX_VISIBILITY(default) 00038 { 00039 _GLIBCXX_BEGIN_NAMESPACE_VERSION 00040 00041 /** @defgroup hashes Hashes 00042 * @ingroup functors 00043 * 00044 * Hashing functors taking a variable type and returning a @c std::size_t. 00045 * 00046 * @{ 00047 */ 00048 00049 template<typename _Result, typename _Arg> 00050 struct __hash_base 00051 { 00052 typedef _Result result_type; 00053 typedef _Arg argument_type; 00054 }; 00055 00056 /// Primary class template hash. 00057 template<typename _Tp> 00058 struct hash : public __hash_base<size_t, _Tp> 00059 { 00060 static_assert(sizeof(_Tp) < 0, 00061 "std::hash is not specialized for this type"); 00062 size_t operator()(const _Tp&) const noexcept; 00063 }; 00064 00065 /// Partial specializations for pointer types. 00066 template<typename _Tp> 00067 struct hash<_Tp*> : public __hash_base<size_t, _Tp*> 00068 { 00069 size_t 00070 operator()(_Tp* __p) const noexcept 00071 { return reinterpret_cast<size_t>(__p); } 00072 }; 00073 00074 // Explicit specializations for integer types. 00075 #define _Cxx_hashtable_define_trivial_hash(_Tp) \ 00076 template<> \ 00077 struct hash<_Tp> : public __hash_base<size_t, _Tp> \ 00078 { \ 00079 size_t \ 00080 operator()(_Tp __val) const noexcept \ 00081 { return static_cast<size_t>(__val); } \ 00082 }; 00083 00084 /// Explicit specialization for bool. 00085 _Cxx_hashtable_define_trivial_hash(bool) 00086 00087 /// Explicit specialization for char. 00088 _Cxx_hashtable_define_trivial_hash(char) 00089 00090 /// Explicit specialization for signed char. 00091 _Cxx_hashtable_define_trivial_hash(signed char) 00092 00093 /// Explicit specialization for unsigned char. 00094 _Cxx_hashtable_define_trivial_hash(unsigned char) 00095 00096 /// Explicit specialization for wchar_t. 00097 _Cxx_hashtable_define_trivial_hash(wchar_t) 00098 00099 /// Explicit specialization for char16_t. 00100 _Cxx_hashtable_define_trivial_hash(char16_t) 00101 00102 /// Explicit specialization for char32_t. 00103 _Cxx_hashtable_define_trivial_hash(char32_t) 00104 00105 /// Explicit specialization for short. 00106 _Cxx_hashtable_define_trivial_hash(short) 00107 00108 /// Explicit specialization for int. 00109 _Cxx_hashtable_define_trivial_hash(int) 00110 00111 /// Explicit specialization for long. 00112 _Cxx_hashtable_define_trivial_hash(long) 00113 00114 /// Explicit specialization for long long. 00115 _Cxx_hashtable_define_trivial_hash(long long) 00116 00117 /// Explicit specialization for unsigned short. 00118 _Cxx_hashtable_define_trivial_hash(unsigned short) 00119 00120 /// Explicit specialization for unsigned int. 00121 _Cxx_hashtable_define_trivial_hash(unsigned int) 00122 00123 /// Explicit specialization for unsigned long. 00124 _Cxx_hashtable_define_trivial_hash(unsigned long) 00125 00126 /// Explicit specialization for unsigned long long. 00127 _Cxx_hashtable_define_trivial_hash(unsigned long long) 00128 00129 #undef _Cxx_hashtable_define_trivial_hash 00130 00131 struct _Hash_impl 00132 { 00133 static size_t 00134 hash(const void* __ptr, size_t __clength, 00135 size_t __seed = static_cast<size_t>(0xc70f6907UL)) 00136 { return _Hash_bytes(__ptr, __clength, __seed); } 00137 00138 template<typename _Tp> 00139 static size_t 00140 hash(const _Tp& __val) 00141 { return hash(&__val, sizeof(__val)); } 00142 00143 template<typename _Tp> 00144 static size_t 00145 __hash_combine(const _Tp& __val, size_t __hash) 00146 { return hash(&__val, sizeof(__val), __hash); } 00147 }; 00148 00149 struct _Fnv_hash_impl 00150 { 00151 static size_t 00152 hash(const void* __ptr, size_t __clength, 00153 size_t __seed = static_cast<size_t>(2166136261UL)) 00154 { return _Fnv_hash_bytes(__ptr, __clength, __seed); } 00155 00156 template<typename _Tp> 00157 static size_t 00158 hash(const _Tp& __val) 00159 { return hash(&__val, sizeof(__val)); } 00160 00161 template<typename _Tp> 00162 static size_t 00163 __hash_combine(const _Tp& __val, size_t __hash) 00164 { return hash(&__val, sizeof(__val), __hash); } 00165 }; 00166 00167 /// Specialization for float. 00168 template<> 00169 struct hash<float> : public __hash_base<size_t, float> 00170 { 00171 size_t 00172 operator()(float __val) const noexcept 00173 { 00174 // 0 and -0 both hash to zero. 00175 return __val != 0.0f ? std::_Hash_impl::hash(__val) : 0; 00176 } 00177 }; 00178 00179 /// Specialization for double. 00180 template<> 00181 struct hash<double> : public __hash_base<size_t, double> 00182 { 00183 size_t 00184 operator()(double __val) const noexcept 00185 { 00186 // 0 and -0 both hash to zero. 00187 return __val != 0.0 ? std::_Hash_impl::hash(__val) : 0; 00188 } 00189 }; 00190 00191 /// Specialization for long double. 00192 template<> 00193 struct hash<long double> 00194 : public __hash_base<size_t, long double> 00195 { 00196 _GLIBCXX_PURE size_t 00197 operator()(long double __val) const noexcept; 00198 }; 00199 00200 // @} group hashes 00201 00202 _GLIBCXX_END_NAMESPACE_VERSION 00203 } // namespace 00204 00205 #endif // _FUNCTIONAL_HASH_H