Hash.H
Go to the documentation of this file.
1/*---------------------------------------------------------------------------*\
2 ========= |
3 \\ / F ield | OpenFOAM: The Open Source CFD Toolbox
4 \\ / O peration |
5 \\ / A nd | www.openfoam.com
6 \\/ M anipulation |
7-------------------------------------------------------------------------------
8 Copyright (C) 2011-2012 OpenFOAM Foundation
9 Copyright (C) 2018-2021 OpenCFD Ltd.
10-------------------------------------------------------------------------------
11License
12 This file is part of OpenFOAM.
13
14 OpenFOAM is free software: you can redistribute it and/or modify it
15 under the terms of the GNU General Public License as published by
16 the Free Software Foundation, either version 3 of the License, or
17 (at your option) any later version.
18
19 OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
20 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
21 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
22 for more details.
23
24 You should have received a copy of the GNU General Public License
25 along with OpenFOAM. If not, see <http://www.gnu.org/licenses/>.
26
27Class
28 Foam::Hash
29
30Description
31 Hash function class.
32 The default definition is for primitives.
33 Non-primitives used to hash entries on hash tables will need
34 a specialized version.
35
36\*---------------------------------------------------------------------------*/
37
38#ifndef Hash_H
39#define Hash_H
40
41#include "Hasher.H"
42#include <cstdint>
43
44// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
45
46namespace Foam
47{
48
49/*---------------------------------------------------------------------------*\
50 Class Hash Declaration
51\*---------------------------------------------------------------------------*/
52
53template<class T>
54struct Hash
55{
56 unsigned operator()(const T& obj, unsigned seed=0) const
57 {
58 return Foam::Hasher(&obj, sizeof(T), seed);
59 }
60};
61
62
63// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
64
65//- Hashing of nullptr, always 0
66template<>
67struct Hash<std::nullptr_t>
68{
69 unsigned operator()(std::nullptr_t, unsigned seed=0) const noexcept
70 {
71 return seed;
72 }
73};
74
75//- Hashing of pointers, treat as unsigned integer
76template<>
77struct Hash<void*>
78{
79 unsigned operator()(const void* const ptr, unsigned seed=0) const
80 {
81 const uintptr_t addr = uintptr_t(ptr);
82 return Foam::Hasher(&addr, sizeof(addr), seed);
83 }
84};
85
86
87// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
88
89// Specialization for common integral types
90
91#undef FOAM_HASH_SPECIALIZATION
92#define FOAM_HASH_SPECIALIZATION(Type) \
93 \
94 \
95 \
96 template<> \
97 struct Hash<Type> \
98 { \
99 unsigned operator()(const Type val) const \
100 { \
101 return static_cast<unsigned>(val); \
102 } \
103 unsigned operator()(const Type val, unsigned seed) const \
104 { \
105 return Foam::Hasher(&val, sizeof(Type), seed); \
106 } \
107 }
108
109FOAM_HASH_SPECIALIZATION(bool);
110FOAM_HASH_SPECIALIZATION(char);
111FOAM_HASH_SPECIALIZATION(int32_t);
112FOAM_HASH_SPECIALIZATION(int64_t);
113FOAM_HASH_SPECIALIZATION(uint32_t);
114#undef FOAM_HASH_SPECIALIZATION
115
116
117// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
118
119} // End namespace Foam
120
121// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
122
123#endif
124
125// ************************************************************************* //
FOAM_HASH_SPECIALIZATION
#define FOAM_HASH_SPECIALIZATION(Type)
Definition: Hash.H:91
Hasher.H
Miscellaneous hashing functions, mostly from Bob Jenkins.
T
const volScalarField & T
Definition: createFieldRefs.H:2
Foam
Namespace for OpenFOAM.
Definition: atmBoundaryLayer.C:34
Foam::Hasher
unsigned Hasher(const void *data, size_t len, unsigned seed=0)
Bob Jenkins's 96-bit mixer hashing function (lookup3)
Definition: Hasher.C:581
Foam::noexcept
const direction noexcept
Definition: Scalar.H:223
Foam::Hash< std::nullptr_t >::operator()
unsigned operator()(std::nullptr_t, unsigned seed=0) const noexcept
Definition: Hash.H:68
Foam::Hash< void * >::operator()
unsigned operator()(const void *const ptr, unsigned seed=0) const
Definition: Hash.H:78
Foam::Hash
Hash function class. The default definition is for primitives. Non-primitives used to hash entries on...
Definition: Hash.H:54
Foam::Hash::operator()
unsigned operator()(const T &obj, unsigned seed=0) const
Definition: Hash.H:55