1// TR1 functional -*- C++ -*-
2
3// Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc.
4//
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)
9// any later version.
10
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.
15
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.
19
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/>.
24
25/** @file tr1_impl/functional_hash.h
26 *  This is an internal header file, included by other library headers.
27 *  You should not attempt to use it directly.
28 */
29
30namespace std
31{
32_GLIBCXX_BEGIN_NAMESPACE_TR1
33
34  /// Class template hash.
35  // Declaration of default hash functor std::tr1::hash.  The types for
36  // which std::tr1::hash<T> is well-defined is in clause 6.3.3. of the PDTR.
37  template<typename _Tp>
38    struct hash : public std::unary_function<_Tp, size_t>
39    {
40      size_t
41      operator()(_Tp __val) const;
42    };
43
44  /// Partial specializations for pointer types.
45  template<typename _Tp>
46    struct hash<_Tp*> : public std::unary_function<_Tp*, size_t>
47    {
48      size_t
49      operator()(_Tp* __p) const
50      { return reinterpret_cast<size_t>(__p); }
51    };
52
53  /// Explicit specializations for integer types.
54#define _TR1_hashtable_define_trivial_hash(_Tp) 	\
55  template<>						\
56    inline size_t					\
57    hash<_Tp>::operator()(_Tp __val) const		\
58    { return static_cast<size_t>(__val); }
59
60  _TR1_hashtable_define_trivial_hash(bool);
61  _TR1_hashtable_define_trivial_hash(char);
62  _TR1_hashtable_define_trivial_hash(signed char);
63  _TR1_hashtable_define_trivial_hash(unsigned char);
64  _TR1_hashtable_define_trivial_hash(wchar_t);
65#ifdef _GLIBCXX_INCLUDE_AS_CXX0X
66  _TR1_hashtable_define_trivial_hash(char16_t);
67  _TR1_hashtable_define_trivial_hash(char32_t);
68#endif
69  _TR1_hashtable_define_trivial_hash(short);
70  _TR1_hashtable_define_trivial_hash(int);
71  _TR1_hashtable_define_trivial_hash(long);
72  _TR1_hashtable_define_trivial_hash(long long);
73  _TR1_hashtable_define_trivial_hash(unsigned short);
74  _TR1_hashtable_define_trivial_hash(unsigned int);
75  _TR1_hashtable_define_trivial_hash(unsigned long);
76  _TR1_hashtable_define_trivial_hash(unsigned long long);
77
78#undef _TR1_hashtable_define_trivial_hash
79
80  // Fowler / Noll / Vo (FNV) Hash (type FNV-1a)
81  // (Used by the next specializations of std::tr1::hash.)
82
83  /// Dummy generic implementation (for sizeof(size_t) != 4, 8).
84  template<size_t = sizeof(size_t)>
85    struct _Fnv_hash
86    {
87      static size_t
88      hash(const char* __first, size_t __length)
89      {
90	size_t __result = 0;
91	for (; __length > 0; --__length)
92	  __result = (__result * 131) + *__first++;
93	return __result;
94      }
95    };
96
97  template<>
98    struct _Fnv_hash<4>
99    {
100      static size_t
101      hash(const char* __first, size_t __length)
102      {
103	size_t __result = static_cast<size_t>(2166136261UL);
104	for (; __length > 0; --__length)
105	  {
106	    __result ^= static_cast<size_t>(*__first++);
107	    __result *= static_cast<size_t>(16777619UL);
108	  }
109	return __result;
110      }
111    };
112
113  template<>
114    struct _Fnv_hash<8>
115    {
116      static size_t
117      hash(const char* __first, size_t __length)
118      {
119	size_t __result =
120	  static_cast<size_t>(14695981039346656037ULL);
121	for (; __length > 0; --__length)
122	  {
123	    __result ^= static_cast<size_t>(*__first++);
124	    __result *= static_cast<size_t>(1099511628211ULL);
125	  }
126	return __result;
127      }
128    };
129
130  /// Explicit specializations for float.
131  template<>
132    inline size_t
133    hash<float>::operator()(float __val) const
134    {
135      size_t __result = 0;
136
137      // 0 and -0 both hash to zero.
138      if (__val != 0.0f)
139	__result = _Fnv_hash<>::hash(reinterpret_cast<const char*>(&__val),
140				     sizeof(__val));
141      return __result;
142    };
143
144  /// Explicit specializations for double.
145  template<>
146    inline size_t
147    hash<double>::operator()(double __val) const
148    {
149	size_t __result = 0;
150
151	// 0 and -0 both hash to zero.
152	if (__val != 0.0)
153	  __result = _Fnv_hash<>::hash(reinterpret_cast<const char*>(&__val),
154				       sizeof(__val));
155	return __result;
156    };
157
158  /// Explicit specializations for long double.
159  template<>
160    size_t
161    hash<long double>::operator()(long double __val) const;
162
163  /// Explicit specialization of member operator for non-builtin types.
164  template<>
165    size_t
166    hash<string>::operator()(string) const;
167
168  template<>
169    size_t
170    hash<const string&>::operator()(const string&) const;
171
172#ifdef _GLIBCXX_USE_WCHAR_T
173  template<>
174    size_t
175    hash<wstring>::operator()(wstring) const;
176
177  template<>
178    size_t
179    hash<const wstring&>::operator()(const wstring&) const;
180#endif
181
182_GLIBCXX_END_NAMESPACE_TR1
183}
184