ITK  5.0.0
Insight Segmentation and Registration Toolkit
itkStructHashFunction.h
Go to the documentation of this file.
1 /*=========================================================================
2  *
3  * Copyright Insight Software Consortium
4  *
5  * Licensed under the Apache License, Version 2.0 (the "License");
6  * you may not use this file except in compliance with the License.
7  * You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0.txt
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  *
17  *=========================================================================*/
18 #ifndef itkStructHashFunction_h
19 #define itkStructHashFunction_h
20 
21 #include "itkIntTypes.h"
22 #include "itkMacro.h"
23 
24 namespace itk
25 {
39 template< typename TInput >
41 {
42 public:
43 
46 
48  using InputType = TInput;
49 
50  IdentifierType operator()(const InputType & key) const;
51 };
52 
53 template< typename TInput >
54 inline IdentifierType
56 ::operator()(const InputType & key) const
57 {
58  auto len = static_cast< IdentifierType >( sizeof( InputType ) );
59  const auto * p = reinterpret_cast< const char * >( &key );
60  IdentifierType hash = 0UL;
61  while ( len-- )
62  {
63  hash = hash * 65UL + static_cast<IdentifierType>(*p++);
64  }
65  hash += ( hash >> 5 );
66  return hash;
67 }
68 }
69 
70 #endif // ndef itkStructHashFunction_h
IdentifierType operator()(const InputType &key) const
SizeValueType IdentifierType
Definition: itkIntTypes.h:87
Generic hash function for an arbitrary struct (or class).