itkStructHashFunction.h

Go to the documentation of this file.

/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
#ifndef itkStructHashFunction_h
#define itkStructHashFunction_h
 
#include "itkIntTypes.h"
#include "itkMacro.h"
 
namespace itk
{
template <typename TInput>
class StructHashFunction
{
public:
  using Self = StructHashFunction;
 
  using InputType = TInput;
 
  IdentifierType
  operator()(const InputType & key) const;
};
 
template <typename TInput>
inline IdentifierType
StructHashFunction<TInput>::operator()(const InputType & key) const
{
  auto           len = static_cast<IdentifierType>(sizeof(InputType));
  const auto *   p = reinterpret_cast<const char *>(&key);
  IdentifierType hash = 0UL;
  while (len--)
  {
    hash = hash * 65UL + static_cast<IdentifierType>(*p++);
  }
  hash += (hash >> 5);
  return hash;
}
} // namespace itk
 
#endif // ndef itkStructHashFunction_h