itkSliceIterator.h

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/*=========================================================================
 *
 *  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 itkSliceIterator_h
#define itkSliceIterator_h
 
#include "itkMacro.h"
#include "itkIntTypes.h"
#include <valarray>
 
namespace itk
{
template <typename TPixel, typename TContainer>
class SliceIterator
{
public:
  SliceIterator(TContainer * n, std::slice s)
    : m_ContainerPointer(n)
    , m_Slice(s)
  {}

  SliceIterator
  Begin()
  {
    SliceIterator ans = *this;
 
    ans.m_Pos = 0;
    return ans;
  }

  SliceIterator
  End()
  {
    SliceIterator ans = *this;
 
    ans.m_Pos = static_cast<OffsetValueType>(m_Slice.size());
    return ans;
  }

  SliceIterator
  operator++()
  {
    ++m_Pos;
    return *this;
  }

  SliceIterator
  operator++(int)
  {
    SliceIterator ans = *this;
 
    ++m_Pos;
    return ans;
  }

  TPixel &
  operator[](OffsetValueType n)
  {
    return this->Loc(m_Pos = n);
  }

  TPixel &
  operator*()
  {
    return Loc(m_Pos);
  }

  bool
  operator==(const SliceIterator & orig) const
  {
    return orig.m_Pos == this->m_Pos && orig.m_Slice.stride() == this->m_Slice.stride() &&
           orig.m_Slice.start() == this->m_Slice.start();
  }
 
  ITK_UNEQUAL_OPERATOR_MEMBER_FUNCTION(SliceIterator);

  bool
  operator<(const SliceIterator & orig) const
  {
    return this->m_Pos < orig.m_Pos && this->m_Slice.stride() == orig.m_Slice.stride() &&
           this->m_Slice.start() == orig.m_Slice.start();
  }
 
private:
  TPixel &
  Loc(OffsetValueType n) const
  {
    const auto start = static_cast<OffsetValueType>(m_Slice.start());
    const auto stride = static_cast<OffsetValueType>(m_Slice.stride());
 
    return (*m_ContainerPointer)[start + n * stride];
  }

  TContainer * m_ContainerPointer;

  OffsetValueType m_Pos{ 0 };

  std::slice m_Slice;
};
} // end namespace itk
 
#endif