1 // TR1 functional -*- C++ -*-
3 // Copyright (C) 2007, 2008 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 2, 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 // You should have received a copy of the GNU General Public License along
17 // with this library; see the file COPYING. If not, write to the Free
18 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
21 // As a special exception, you may use this file as part of a free software
22 // library without restriction. Specifically, if other files instantiate
23 // templates or use macros or inline functions from this file, or you compile
24 // this file and link it with other files to produce an executable, this
25 // file does not by itself cause the resulting executable to be covered by
26 // the GNU General Public License. This exception does not however
27 // invalidate any other reasons why the executable file might be covered by
28 // the GNU General Public License.
30 /** @file tr1_impl/functional_hash.h
31 * This is an internal header file, included by other library headers.
32 * You should not attempt to use it directly.
37 _GLIBCXX_BEGIN_NAMESPACE_TR1
39 /// Class template hash.
40 // Declaration of default hash functor std::tr1::hash. The types for
41 // which std::tr1::hash<T> is well-defined is in clause 6.3.3. of the PDTR.
42 template<typename _Tp>
43 struct hash : public std::unary_function<_Tp, size_t>
46 operator()(_Tp __val) const;
49 /// Partial specializations for pointer types.
50 template<typename _Tp>
51 struct hash<_Tp*> : public std::unary_function<_Tp*, size_t>
54 operator()(_Tp* __p) const
55 { return reinterpret_cast<size_t>(__p); }
58 /// Explicit specializations for integer types.
59 #define _TR1_hashtable_define_trivial_hash(_Tp) \
62 hash<_Tp>::operator()(_Tp __val) const \
63 { return static_cast<size_t>(__val); }
65 _TR1_hashtable_define_trivial_hash(bool);
66 _TR1_hashtable_define_trivial_hash(char);
67 _TR1_hashtable_define_trivial_hash(signed char);
68 _TR1_hashtable_define_trivial_hash(unsigned char);
69 _TR1_hashtable_define_trivial_hash(wchar_t);
70 _TR1_hashtable_define_trivial_hash(short);
71 _TR1_hashtable_define_trivial_hash(int);
72 _TR1_hashtable_define_trivial_hash(long);
73 _TR1_hashtable_define_trivial_hash(long long);
74 _TR1_hashtable_define_trivial_hash(unsigned short);
75 _TR1_hashtable_define_trivial_hash(unsigned int);
76 _TR1_hashtable_define_trivial_hash(unsigned long);
77 _TR1_hashtable_define_trivial_hash(unsigned long long);
79 #undef _TR1_hashtable_define_trivial_hash
81 // Fowler / Noll / Vo (FNV) Hash (type FNV-1a)
82 // (Used by the next specializations of std::tr1::hash.)
84 /// Dummy generic implementation (for sizeof(size_t) != 4, 8).
85 template<size_t = sizeof(size_t)>
89 hash(const char* __first, size_t __length)
92 for (; __length > 0; --__length)
93 __result = (__result * 131) + *__first++;
102 hash(const char* __first, size_t __length)
104 size_t __result = static_cast<size_t>(2166136261UL);
105 for (; __length > 0; --__length)
107 __result ^= static_cast<size_t>(*__first++);
108 __result *= static_cast<size_t>(16777619UL);
118 hash(const char* __first, size_t __length)
121 static_cast<size_t>(14695981039346656037ULL);
122 for (; __length > 0; --__length)
124 __result ^= static_cast<size_t>(*__first++);
125 __result *= static_cast<size_t>(1099511628211ULL);
131 /// Explicit specializations for float.
134 hash<float>::operator()(float __val) const
138 // 0 and -0 both hash to zero.
140 __result = _Fnv_hash<>::hash(reinterpret_cast<const char*>(&__val),
145 /// Explicit specializations for double.
148 hash<double>::operator()(double __val) const
152 // 0 and -0 both hash to zero.
154 __result = _Fnv_hash<>::hash(reinterpret_cast<const char*>(&__val),
159 /// Explicit specializations for long double.
162 hash<long double>::operator()(long double __val) const;
164 /// Explicit specialization of member operator for non-builtin types.
167 hash<string>::operator()(string) const;
171 hash<const string&>::operator()(const string&) const;
173 #ifdef _GLIBCXX_USE_WCHAR_T
176 hash<wstring>::operator()(wstring) const;
180 hash<const wstring&>::operator()(const wstring&) const;
183 _GLIBCXX_END_NAMESPACE_TR1