1 // TR1 functional_hash.h header -*- C++ -*-
3 // Copyright (C) 2007-2016 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 tr1/functional_hash.h
26 * This is an internal header file, included by other library headers.
27 * Do not attempt to use it directly. @headername{tr1/functional}
30 #ifndef _GLIBCXX_TR1_FUNCTIONAL_HASH_H
31 #define _GLIBCXX_TR1_FUNCTIONAL_HASH_H 1
33 #pragma GCC system_header
35 namespace std
_GLIBCXX_VISIBILITY(default)
39 _GLIBCXX_BEGIN_NAMESPACE_VERSION
41 /// Class template hash.
42 // Declaration of default hash functor std::tr1::hash. The types for
43 // which std::tr1::hash<T> is well-defined is in clause 6.3.3. of the PDTR.
44 template<typename _Tp
>
45 struct hash
: public std::unary_function
<_Tp
, size_t>
48 operator()(_Tp __val
) const;
51 /// Partial specializations for pointer types.
52 template<typename _Tp
>
53 struct hash
<_Tp
*> : public std::unary_function
<_Tp
*, size_t>
56 operator()(_Tp
* __p
) const
57 { return reinterpret_cast<size_t>(__p
); }
60 /// Explicit specializations for integer types.
61 #define _TR1_hashtable_define_trivial_hash(_Tp) \
64 hash<_Tp>::operator()(_Tp __val) const \
65 { return static_cast<size_t>(__val); }
67 _TR1_hashtable_define_trivial_hash(bool);
68 _TR1_hashtable_define_trivial_hash(char);
69 _TR1_hashtable_define_trivial_hash(signed char);
70 _TR1_hashtable_define_trivial_hash(unsigned char);
71 _TR1_hashtable_define_trivial_hash(wchar_t);
72 _TR1_hashtable_define_trivial_hash(short);
73 _TR1_hashtable_define_trivial_hash(int);
74 _TR1_hashtable_define_trivial_hash(long);
75 _TR1_hashtable_define_trivial_hash(long long);
76 _TR1_hashtable_define_trivial_hash(unsigned short);
77 _TR1_hashtable_define_trivial_hash(unsigned int);
78 _TR1_hashtable_define_trivial_hash(unsigned long);
79 _TR1_hashtable_define_trivial_hash(unsigned long long);
81 #undef _TR1_hashtable_define_trivial_hash
83 // Fowler / Noll / Vo (FNV) Hash (type FNV-1a)
84 // (Used by the next specializations of std::tr1::hash.)
86 // N.B. These functions should work on unsigned char, otherwise they do not
87 // correctly implement the FNV-1a algorithm (see PR59406).
88 // The existing behaviour is retained for backwards compatibility.
90 /// Dummy generic implementation (for sizeof(size_t) != 4, 8).
94 template<typename _Tp
>
96 hash(const _Tp
* __ptr
, size_t __clength
)
99 const char* __cptr
= reinterpret_cast<const char*>(__ptr
);
100 for (; __clength
; --__clength
)
101 __result
= (__result
* 131) + *__cptr
++;
107 struct _Fnv_hash_base
<4>
109 template<typename _Tp
>
111 hash(const _Tp
* __ptr
, size_t __clength
)
113 size_t __result
= static_cast<size_t>(2166136261UL);
114 const char* __cptr
= reinterpret_cast<const char*>(__ptr
);
115 for (; __clength
; --__clength
)
117 __result
^= static_cast<size_t>(*__cptr
++);
118 __result
*= static_cast<size_t>(16777619UL);
125 struct _Fnv_hash_base
<8>
127 template<typename _Tp
>
129 hash(const _Tp
* __ptr
, size_t __clength
)
132 = static_cast<size_t>(14695981039346656037ULL);
133 const char* __cptr
= reinterpret_cast<const char*>(__ptr
);
134 for (; __clength
; --__clength
)
136 __result
^= static_cast<size_t>(*__cptr
++);
137 __result
*= static_cast<size_t>(1099511628211ULL);
144 : public _Fnv_hash_base
<sizeof(size_t)>
146 using _Fnv_hash_base
<sizeof(size_t)>::hash
;
148 template<typename _Tp
>
150 hash(const _Tp
& __val
)
151 { return hash(&__val
, sizeof(__val
)); }
154 /// Explicit specializations for float.
157 hash
<float>::operator()(float __val
) const
159 // 0 and -0 both hash to zero.
160 return __val
!= 0.0f
? std::tr1::_Fnv_hash::hash(__val
) : 0;
163 /// Explicit specializations for double.
166 hash
<double>::operator()(double __val
) const
168 // 0 and -0 both hash to zero.
169 return __val
!= 0.0 ? std::tr1::_Fnv_hash::hash(__val
) : 0;
172 /// Explicit specializations for long double.
175 hash
<long double>::operator()(long double __val
) const;
177 /// Explicit specialization of member operator for non-builtin types.
180 hash
<string
>::operator()(string
) const;
184 hash
<const string
&>::operator()(const string
&) const;
186 #ifdef _GLIBCXX_USE_WCHAR_T
189 hash
<wstring
>::operator()(wstring
) const;
193 hash
<const wstring
&>::operator()(const wstring
&) const;
196 _GLIBCXX_END_NAMESPACE_VERSION
200 #endif // _GLIBCXX_TR1_FUNCTIONAL_HASH_H