itkIndex.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 itkIndex_h
#define itkIndex_h
 
#include "itkMakeFilled.h"
#include "itkOffset.h"
 
#include <cstddef>     // For ptrdiff_t.
#include <type_traits> // For is_integral.
 
namespace itk
{

 
template <unsigned int VDimension = 2>
struct ITK_TEMPLATE_EXPORT Index final
{
public:
  // Using the `rule of zero` to this aggregate type
  // C++20 changes the definition of aggregate such that classes with any user-declared ctors are no longer aggregates.

  using Self = Index;

  using IndexType = Index<VDimension>;
  using IndexValueType = itk::IndexValueType;

  using SizeType = Size<VDimension>;

  using OffsetType = Offset<VDimension>;
  using OffsetValueType = itk::OffsetValueType;

  static constexpr unsigned int Dimension = VDimension;

  static constexpr unsigned int
  GetIndexDimension()
  {
    return VDimension;
  }
 

  const Self
  operator+(const SizeType & sz) const
  {
    Self result;
 
    for (unsigned int i = 0; i < VDimension; ++i)
    {
      result[i] = m_InternalArray[i] + static_cast<IndexValueType>(sz[i]);
    }
    return result;
  }

  const Self &
  operator+=(const SizeType & sz)
  {
    for (unsigned int i = 0; i < VDimension; ++i)
    {
      m_InternalArray[i] += static_cast<IndexValueType>(sz[i]);
    }
    return *this;
  }


  const Self
  operator-(const SizeType & sz) const
  {
    Self result;
 
    for (unsigned int i = 0; i < VDimension; ++i)
    {
      result[i] = m_InternalArray[i] - static_cast<IndexValueType>(sz[i]);
    }
    return result;
  }

  const Self &
  operator-=(const SizeType & sz)
  {
    for (unsigned int i = 0; i < VDimension; ++i)
    {
      m_InternalArray[i] -= static_cast<IndexValueType>(sz[i]);
    }
    return *this;
  }


  const Self
  operator+(const OffsetType & offset) const
  {
    Self result;
 
    for (unsigned int i = 0; i < VDimension; ++i)
    {
      result[i] = m_InternalArray[i] + offset[i];
    }
    return result;
  }

  const Self &
  operator+=(const OffsetType & offset)
  {
    for (unsigned int i = 0; i < VDimension; ++i)
    {
      m_InternalArray[i] += offset[i];
    }
    return *this;
  }


  const Self &
  operator-=(const OffsetType & offset)
  {
    for (unsigned int i = 0; i < VDimension; ++i)
    {
      m_InternalArray[i] -= offset[i];
    }
    return *this;
  }


  const Self
  operator-(const OffsetType & off) const
  {
    Self result;
 
    for (unsigned int i = 0; i < VDimension; ++i)
    {
      result[i] = m_InternalArray[i] - off.m_InternalArray[i];
    }
    return result;
  }

  const OffsetType
  operator-(const Self & vec) const
  {
    OffsetType result;
 
    for (unsigned int i = 0; i < VDimension; ++i)
    {
      result[i] = m_InternalArray[i] - vec.m_InternalArray[i];
    }
    return result;
  }

  const Self
  operator*(const SizeType & vec) const
  {
    Self result;
 
    for (unsigned int i = 0; i < VDimension; ++i)
    {
      result[i] = m_InternalArray[i] * static_cast<IndexValueType>(vec.m_InternalArray[i]);
    }
    return result;
  }

  const IndexValueType *
  GetIndex() const
  {
    return m_InternalArray;
  }

  void
  SetIndex(const IndexValueType val[VDimension])
  {
    std::copy_n(val, VDimension, m_InternalArray);
  }

  void
  SetElement(unsigned int element, IndexValueType val)
  {
    m_InternalArray[element] = val;
  }

  IndexValueType
  GetElement(unsigned int element) const
  {
    return m_InternalArray[element];
  }

  void
  Fill(IndexValueType value)
  {
    std::fill_n(begin(), size(), value);
  } // MATCH std::array assign, ITK Fill

  /*
   *  Ask the compiler to align a type to the maximum useful alignment for the target
   *  machine you are compiling for. Whenever you leave out the alignment factor in an
   *  aligned attribute specification, the compiler automatically sets the alignment
   *  for the type to the largest alignment that is ever used for any data type on
   *  the target machine you are compiling for. Doing this can often make copy
   *  operations more efficient, because the compiler can use whatever instructions
   *  copy the biggest chunks of memory when performing copies to or from the variables
   *  that have types that you have aligned this way.
   */
  static_assert(VDimension > 0, "Error: Only positive value sized VDimension allowed");
  alignas(IndexValueType) IndexValueType m_InternalArray[VDimension];

  template <typename TCoordinate>
  inline void
  CopyWithRound(const FixedArray<TCoordinate, VDimension> & point)
  {
    for (unsigned int i = 0; i < VDimension; ++i)
    {
      m_InternalArray[i] = Math::Round<IndexValueType>(point[i]);
    }
  }


  template <typename TCoordinate>
  inline void
  CopyWithCast(const FixedArray<TCoordinate, VDimension> & point)
  {
    for (unsigned int i = 0; i < VDimension; ++i)
    {
      m_InternalArray[i] = static_cast<IndexValueType>(point[i]);
    }
  }


  static Self
  GetBasisIndex(unsigned int dim);
 
 
  // ======================= Mirror the access pattern behavior of the std::array class
  using value_type = itk::IndexValueType;
  using reference = value_type &;
  using const_reference = const value_type &;
  using iterator = value_type *;
  using const_iterator = const value_type *;
  using size_type = unsigned int;
  using difference_type = ptrdiff_t;
  using reverse_iterator = std::reverse_iterator<iterator>;
  using const_reverse_iterator = std::reverse_iterator<const_iterator>;

  void
  assign(const value_type & newValue)
  {
    std::fill_n(begin(), size(), newValue);
  }
 
  void
  swap(Index & other) noexcept
  {
    std::swap(m_InternalArray, other.m_InternalArray);
  }
 
  constexpr const_iterator
  cbegin() const
  {
    return &m_InternalArray[0];
  }
 
  constexpr iterator
  begin()
  {
    return &m_InternalArray[0];
  }
 
  constexpr const_iterator
  begin() const
  {
    return &m_InternalArray[0];
  }
 
  constexpr const_iterator
  cend() const
  {
    return &m_InternalArray[VDimension];
  }
 
  constexpr iterator
  end()
  {
    return &m_InternalArray[VDimension];
  }
 
  constexpr const_iterator
  end() const
  {
    return &m_InternalArray[VDimension];
  }
 
  reverse_iterator
  rbegin()
  {
    return reverse_iterator(end());
  }
 
  const_reverse_iterator
  rbegin() const
  {
    return const_reverse_iterator(end());
  }
 
  reverse_iterator
  rend()
  {
    return reverse_iterator(begin());
  }
 
  const_reverse_iterator
  rend() const
  {
    return const_reverse_iterator(begin());
  }
 
  constexpr size_type
  size() const
  {
    return VDimension;
  }
 
  constexpr size_type
  max_size() const
  {
    return VDimension;
  }
 
  constexpr bool
  empty() const
  {
    return false;
  }
 
  constexpr reference
  operator[](size_type pos)
  {
    return m_InternalArray[pos];
  }
 
  constexpr const_reference
  operator[](size_type pos) const
  {
    return m_InternalArray[pos];
  }
 
  reference
  at(size_type pos)
  {
    ExceptionThrowingBoundsCheck(pos);
    return m_InternalArray[pos];
  }
 
  const_reference
  at(size_type pos) const
  {
    ExceptionThrowingBoundsCheck(pos);
    return m_InternalArray[pos];
  }
 
  constexpr reference
  front()
  {
    return *begin();
  }
 
  constexpr const_reference
  front() const
  {
    return *begin();
  }
 
  constexpr reference
  back()
  {
    return VDimension ? *(end() - 1) : *end();
  }
 
  constexpr const_reference
  back() const
  {
    return VDimension ? *(end() - 1) : *end();
  }
 
  IndexValueType *
  data()
  {
    return &m_InternalArray[0];
  }
 
  const IndexValueType *
  data() const
  {
    return &m_InternalArray[0];
  }
 

  static constexpr Self
  Filled(const IndexValueType value)
  {
    return MakeFilled<Self>(value);
  }
 
 
private:
  void
  ExceptionThrowingBoundsCheck(size_type pos) const
  {
    if (pos >= VDimension)
    {
      throw std::out_of_range("array::ExceptionThrowingBoundsCheck");
    }
  }
 
}; //------------ End struct Index
 
template <unsigned int VDimension>
Index<VDimension>
Index<VDimension>::GetBasisIndex(unsigned int dim)
{
  Self ind{ { 0 } };
 
  ind.m_InternalArray[dim] = 1;
  return ind;
}
 
template <unsigned int VDimension>
std::ostream &
operator<<(std::ostream & os, const Index<VDimension> & obj)
{
  os << '[';
  for (unsigned int i = 0; i + 1 < VDimension; ++i)
  {
    os << obj[i] << ", ";
  }
  if constexpr (VDimension >= 1)
  {
    os << obj[VDimension - 1];
  }
  os << ']';
  return os;
}
 
// ======================= Mirror the access pattern behavior of the std::array class
// Array comparisons.
template <unsigned int VDimension>
inline bool
operator==(const Index<VDimension> & one, const Index<VDimension> & two)
{
  return std::equal(one.begin(), one.end(), two.begin());
}
 
template <unsigned int VDimension>
inline bool
operator!=(const Index<VDimension> & one, const Index<VDimension> & two)
{
  return !(one == two);
}
 
template <unsigned int VDimension>
inline bool
operator<(const Index<VDimension> & one, const Index<VDimension> & two)
{
  return std::lexicographical_compare(one.begin(), one.end(), two.begin(), two.end());
}
 
template <unsigned int VDimension>
inline bool
operator>(const Index<VDimension> & one, const Index<VDimension> & two)
{
  return two < one;
}
 
template <unsigned int VDimension>
inline bool
operator<=(const Index<VDimension> & one, const Index<VDimension> & two)
{
  return !(one > two);
}
 
template <unsigned int VDimension>
inline bool
operator>=(const Index<VDimension> & one, const Index<VDimension> & two)
{
  return !(one < two);
}
 
// Specialized algorithms [6.2.2.2].
template <unsigned int VDimension>
inline void
swap(Index<VDimension> & one, Index<VDimension> & two) noexcept
{
  std::swap(one.m_InternalArray, two.m_InternalArray);
}
 

template <typename... T>
auto
MakeIndex(const T... values)
{
  const auto toValueType = [](const auto value) {
    static_assert(std::is_integral_v<decltype(value)>, "Each value must have an integral type!");
    return static_cast<IndexValueType>(value);
  };
  return Index<sizeof...(T)>{ { toValueType(values)... } };
}

 
} // end namespace itk
 
#endif