11.2.0/tr1/functional_hash.h

// TR1 functional_hash.h header -*- C++ -*-

// Copyright (C) 2007-2021 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)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

namespace tr1
{
  /// 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.)

  // N.B. These functions should work on unsigned char, otherwise they do not
  // correctly implement the FNV-1a algorithm (see PR59406).
  // The existing behaviour is retained for backwards compatibility.

  /// 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
Revision:	1166
Committed:	Tue Oct 26 14:22:36 2021 UTC (4 years ago) by rossy
Content type:	text/x-chdr
File size:	6043 byte(s)
Log Message:	Daodan: Replace MinGW build env with an up-to-date MSYS2 env
#	Content
1	// TR1 functional_hash.h header -- C++ --
2
3	// Copyright (C) 2007-2021 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/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}
28	*/
29
30	#ifndef _GLIBCXX_TR1_FUNCTIONAL_HASH_H
31	#define _GLIBCXX_TR1_FUNCTIONAL_HASH_H 1
32
33	#pragma GCC system_header
34
35	namespace std _GLIBCXX_VISIBILITY(default)
36	{
37	_GLIBCXX_BEGIN_NAMESPACE_VERSION
38
39	namespace tr1
40	{
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>
46	{
47	size_t
48	operator()(_Tp __val) const;
49	};
50
51	/// Partial specializations for pointer types.
52	template<typename _Tp>
53	struct hash<_Tp> : public std::unary_function<_Tp, size_t>
54	{
55	size_t
56	operator()(_Tp* __p) const
57	{ return reinterpret_cast<size_t>(__p); }
58	};
59
60	/// Explicit specializations for integer types.
61	#define _TR1_hashtable_define_trivial_hash(_Tp) \
62	template<> \
63	inline size_t \
64	hash<_Tp>::operator()(_Tp __val) const \
65	{ return static_cast<size_t>(__val); }
66
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);
80
81	#undef _TR1_hashtable_define_trivial_hash
82
83	// Fowler / Noll / Vo (FNV) Hash (type FNV-1a)
84	// (Used by the next specializations of std::tr1::hash.)
85
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.
89
90	/// Dummy generic implementation (for sizeof(size_t) != 4, 8).
91	template<size_t>
92	struct _Fnv_hash_base
93	{
94	template<typename _Tp>
95	static size_t
96	hash(const _Tp* __ptr, size_t __clength)
97	{
98	size_t __result = 0;
99	const char* __cptr = reinterpret_cast<const char*>(__ptr);
100	for (; __clength; --__clength)
101	__result = (__result * 131) + *__cptr++;
102	return __result;
103	}
104	};
105
106	template<>
107	struct _Fnv_hash_base<4>
108	{
109	template<typename _Tp>
110	static size_t
111	hash(const _Tp* __ptr, size_t __clength)
112	{
113	size_t __result = static_cast<size_t>(2166136261UL);
114	const char* __cptr = reinterpret_cast<const char*>(__ptr);
115	for (; __clength; --__clength)
116	{
117	__result ^= static_cast<size_t>(*__cptr++);
118	__result *= static_cast<size_t>(16777619UL);
119	}
120	return __result;
121	}
122	};
123
124	template<>
125	struct _Fnv_hash_base<8>
126	{
127	template<typename _Tp>
128	static size_t
129	hash(const _Tp* __ptr, size_t __clength)
130	{
131	size_t __result
132	= static_cast<size_t>(14695981039346656037ULL);
133	const char* __cptr = reinterpret_cast<const char*>(__ptr);
134	for (; __clength; --__clength)
135	{
136	__result ^= static_cast<size_t>(*__cptr++);
137	__result *= static_cast<size_t>(1099511628211ULL);
138	}
139	return __result;
140	}
141	};
142
143	struct _Fnv_hash
144	: public _Fnv_hash_base<sizeof(size_t)>
145	{
146	using _Fnv_hash_base<sizeof(size_t)>::hash;
147
148	template<typename _Tp>
149	static size_t
150	hash(const _Tp& __val)
151	{ return hash(&__val, sizeof(__val)); }
152	};
153
154	/// Explicit specializations for float.
155	template<>
156	inline size_t
157	hash<float>::operator()(float __val) const
158	{
159	// 0 and -0 both hash to zero.
160	return __val != 0.0f ? std::tr1::_Fnv_hash::hash(__val) : 0;
161	}
162
163	/// Explicit specializations for double.
164	template<>
165	inline size_t
166	hash<double>::operator()(double __val) const
167	{
168	// 0 and -0 both hash to zero.
169	return __val != 0.0 ? std::tr1::_Fnv_hash::hash(__val) : 0;
170	}
171
172	/// Explicit specializations for long double.
173	template<>
174	_GLIBCXX_PURE size_t
175	hash<long double>::operator()(long double __val) const;
176
177	/// Explicit specialization of member operator for non-builtin types.
178	template<>
179	_GLIBCXX_PURE size_t
180	hash<string>::operator()(string) const;
181
182	template<>
183	_GLIBCXX_PURE size_t
184	hash<const string&>::operator()(const string&) const;
185
186	#ifdef _GLIBCXX_USE_WCHAR_T
187	template<>
188	_GLIBCXX_PURE size_t
189	hash<wstring>::operator()(wstring) const;
190
191	template<>
192	_GLIBCXX_PURE size_t
193	hash<const wstring&>::operator()(const wstring&) const;
194	#endif
195	}
196
197	_GLIBCXX_END_NAMESPACE_VERSION
198	}
199
200	#endif // _GLIBCXX_TR1_FUNCTIONAL_HASH_H