1 // TR1 functional_hash.h header -*- C++ -*-
3 // Copyright (C) 2007, 2008, 2009, 2010 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 /// Dummy generic implementation (for sizeof(size_t) != 4, 8).
90 template<typename _Tp>
92 hash(const _Tp* __ptr, size_t __clength)
95 const char* __cptr = reinterpret_cast<const char*>(__ptr);
96 for (; __clength; --__clength)
97 __result = (__result * 131) + *__cptr++;
103 struct _Fnv_hash_base<4>
105 template<typename _Tp>
107 hash(const _Tp* __ptr, size_t __clength)
109 size_t __result = static_cast<size_t>(2166136261UL);
110 const char* __cptr = reinterpret_cast<const char*>(__ptr);
111 for (; __clength; --__clength)
113 __result ^= static_cast<size_t>(*__cptr++);
114 __result *= static_cast<size_t>(16777619UL);
121 struct _Fnv_hash_base<8>
123 template<typename _Tp>
125 hash(const _Tp* __ptr, size_t __clength)
128 = static_cast<size_t>(14695981039346656037ULL);
129 const char* __cptr = reinterpret_cast<const char*>(__ptr);
130 for (; __clength; --__clength)
132 __result ^= static_cast<size_t>(*__cptr++);
133 __result *= static_cast<size_t>(1099511628211ULL);
140 : public _Fnv_hash_base<sizeof(size_t)>
142 using _Fnv_hash_base<sizeof(size_t)>::hash;
144 template<typename _Tp>
146 hash(const _Tp& __val)
147 { return hash(&__val, sizeof(__val)); }
150 /// Explicit specializations for float.
153 hash<float>::operator()(float __val) const
155 // 0 and -0 both hash to zero.
156 return __val != 0.0f ? std::tr1::_Fnv_hash::hash(__val) : 0;
159 /// Explicit specializations for double.
162 hash<double>::operator()(double __val) const
164 // 0 and -0 both hash to zero.
165 return __val != 0.0 ? std::tr1::_Fnv_hash::hash(__val) : 0;
168 /// Explicit specializations for long double.
171 hash<long double>::operator()(long double __val) const;
173 /// Explicit specialization of member operator for non-builtin types.
176 hash<string>::operator()(string) const;
180 hash<const string&>::operator()(const string&) const;
182 #ifdef _GLIBCXX_USE_WCHAR_T
185 hash<wstring>::operator()(wstring) const;
189 hash<const wstring&>::operator()(const wstring&) const;
192 _GLIBCXX_END_NAMESPACE_VERSION
196 #endif // _GLIBCXX_TR1_FUNCTIONAL_HASH_H