summaryrefslogtreecommitdiff
path: root/libstdc++-v3/include/tr1/functional_hash.h
blob: 1742e15278863da2995b0909d6b3116d324063a8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
// TR1 functional_hash.h header -*- C++ -*-

// Copyright (C) 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file tr1/functional_hash.h
 *  This is an internal header file, included by other library headers.
 *  Do not attempt to use it directly. @headername{tr1/functional}
 */

#ifndef _GLIBCXX_TR1_FUNCTIONAL_HASH_H
#define _GLIBCXX_TR1_FUNCTIONAL_HASH_H 1

#pragma GCC system_header

namespace std _GLIBCXX_VISIBILITY(default)
{
namespace tr1
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  /// Class template hash.
  // Declaration of default hash functor std::tr1::hash.  The types for
  // which std::tr1::hash<T> is well-defined is in clause 6.3.3. of the PDTR.
  template<typename _Tp>
    struct hash : public std::unary_function<_Tp, size_t>
    {
      size_t
      operator()(_Tp __val) const;
    };

  /// Partial specializations for pointer types.
  template<typename _Tp>
    struct hash<_Tp*> : public std::unary_function<_Tp*, size_t>
    {
      size_t
      operator()(_Tp* __p) const
      { return reinterpret_cast<size_t>(__p); }
    };

  /// Explicit specializations for integer types.
#define _TR1_hashtable_define_trivial_hash(_Tp) 	\
  template<>						\
    inline size_t					\
    hash<_Tp>::operator()(_Tp __val) const		\
    { return static_cast<size_t>(__val); }

  _TR1_hashtable_define_trivial_hash(bool);
  _TR1_hashtable_define_trivial_hash(char);
  _TR1_hashtable_define_trivial_hash(signed char);
  _TR1_hashtable_define_trivial_hash(unsigned char);
  _TR1_hashtable_define_trivial_hash(wchar_t);
  _TR1_hashtable_define_trivial_hash(short);
  _TR1_hashtable_define_trivial_hash(int);
  _TR1_hashtable_define_trivial_hash(long);
  _TR1_hashtable_define_trivial_hash(long long);
  _TR1_hashtable_define_trivial_hash(unsigned short);
  _TR1_hashtable_define_trivial_hash(unsigned int);
  _TR1_hashtable_define_trivial_hash(unsigned long);
  _TR1_hashtable_define_trivial_hash(unsigned long long);

#undef _TR1_hashtable_define_trivial_hash

  // Fowler / Noll / Vo (FNV) Hash (type FNV-1a)
  // (Used by the next specializations of std::tr1::hash.)

  /// Dummy generic implementation (for sizeof(size_t) != 4, 8).
  template<size_t>
    struct _Fnv_hash_base
    {
      template<typename _Tp>
        static size_t
        hash(const _Tp* __ptr, size_t __clength)
        {
	  size_t __result = 0;
	  const char* __cptr = reinterpret_cast<const char*>(__ptr);
	  for (; __clength; --__clength)
	    __result = (__result * 131) + *__cptr++;
	  return __result;
	}
    };

  template<>
    struct _Fnv_hash_base<4>
    {
      template<typename _Tp>
        static size_t
        hash(const _Tp* __ptr, size_t __clength)
        {
	  size_t __result = static_cast<size_t>(2166136261UL);
	  const char* __cptr = reinterpret_cast<const char*>(__ptr);
	  for (; __clength; --__clength)
	    {
	      __result ^= static_cast<size_t>(*__cptr++);
	      __result *= static_cast<size_t>(16777619UL);
	    }
	  return __result;
	}
    };
  
  template<>
    struct _Fnv_hash_base<8>
    {
      template<typename _Tp>
        static size_t
        hash(const _Tp* __ptr, size_t __clength)
        {
	  size_t __result
	    = static_cast<size_t>(14695981039346656037ULL);
	  const char* __cptr = reinterpret_cast<const char*>(__ptr);
	  for (; __clength; --__clength)
	    {
	      __result ^= static_cast<size_t>(*__cptr++);
	      __result *= static_cast<size_t>(1099511628211ULL);
	    }
	  return __result;
	}
    };

  struct _Fnv_hash
  : public _Fnv_hash_base<sizeof(size_t)>
  {
    using _Fnv_hash_base<sizeof(size_t)>::hash;

    template<typename _Tp>
      static size_t
      hash(const _Tp& __val)
      { return hash(&__val, sizeof(__val)); }
  };

  /// Explicit specializations for float.
  template<>
    inline size_t
    hash<float>::operator()(float __val) const
    {
      // 0 and -0 both hash to zero.
      return __val != 0.0f ? std::tr1::_Fnv_hash::hash(__val) : 0;
    }

  /// Explicit specializations for double.
  template<>
    inline size_t
    hash<double>::operator()(double __val) const
    {
      // 0 and -0 both hash to zero.
      return __val != 0.0 ? std::tr1::_Fnv_hash::hash(__val) : 0;
    }

  /// Explicit specializations for long double.
  template<>
    _GLIBCXX_PURE size_t
    hash<long double>::operator()(long double __val) const;

  /// Explicit specialization of member operator for non-builtin types.
  template<>
    _GLIBCXX_PURE size_t
    hash<string>::operator()(string) const;

  template<>
    _GLIBCXX_PURE size_t
    hash<const string&>::operator()(const string&) const;

#ifdef _GLIBCXX_USE_WCHAR_T
  template<>
    _GLIBCXX_PURE size_t
    hash<wstring>::operator()(wstring) const;

  template<>
    _GLIBCXX_PURE size_t
    hash<const wstring&>::operator()(const wstring&) const;
#endif

_GLIBCXX_END_NAMESPACE_VERSION
}
}

#endif // _GLIBCXX_TR1_FUNCTIONAL_HASH_H