itkSparseFieldLayer.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 itkSparseFieldLayer_h
#define itkSparseFieldLayer_h
 
#include "itkObjectFactory.h"
#include "itkObject.h"
#include <vector>
#include <memory> // For unique_ptr.
 
namespace itk
{
template <typename TNodeType>
class ITK_TEMPLATE_EXPORT ConstSparseFieldLayerIterator
{
public:
  const TNodeType &
  operator*() const
  {
    return *m_Pointer;
  }
 
  const TNodeType *
  operator->() const
  {
    return m_Pointer;
  }
 
  [[nodiscard]] const TNodeType *
  GetPointer() const
  {
    return m_Pointer;
  }
 
  bool
  operator==(const ConstSparseFieldLayerIterator o) const
  {
    if (m_Pointer == o.m_Pointer)
    {
      return true;
    }
 
    return false;
  }
 
  ITK_UNEQUAL_OPERATOR_MEMBER_FUNCTION(ConstSparseFieldLayerIterator);
 
  ConstSparseFieldLayerIterator &
  operator++()
  {
    m_Pointer = m_Pointer->Next;
    return *this;
  }
 
  ConstSparseFieldLayerIterator &
  operator--()
  {
    m_Pointer = m_Pointer->Previous;
    return *this;
  }
 
  ConstSparseFieldLayerIterator()
    : m_Pointer(nullptr)
  {}
 
  ConstSparseFieldLayerIterator(TNodeType * p)
    : m_Pointer(p)
  {}
 
protected:
  TNodeType * m_Pointer;
};

template <typename TNodeType>
class ITK_TEMPLATE_EXPORT SparseFieldLayerIterator : public ConstSparseFieldLayerIterator<TNodeType>
{
public:
  using Superclass = ConstSparseFieldLayerIterator<TNodeType>;
 
  SparseFieldLayerIterator()
    : Superclass()
  {}
 
  SparseFieldLayerIterator(TNodeType * p)
    : Superclass(p)
  {}
 
  TNodeType &
  operator*()
  {
    return *this->m_Pointer;
  }
 
  TNodeType *
  operator->()
  {
    return this->m_Pointer;
  }
 
  TNodeType *
  GetPointer()
  {
    return this->m_Pointer;
  }
 
  SparseFieldLayerIterator &
  operator++()
  {
    this->m_Pointer = this->m_Pointer->Next;
    return *this;
  }
 
  SparseFieldLayerIterator &
  operator--()
  {
    this->m_Pointer = this->m_Pointer->Previous;
    return *this;
  }
 
  SparseFieldLayerIterator &
  operator=(Superclass & sc)
  {
    this->m_Pointer = const_cast<TNodeType *>(sc.GetPointer());
    return *this;
  }
};

template <typename TNodeType>
class ITK_TEMPLATE_EXPORT SparseFieldLayer : public Object
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(SparseFieldLayer);

  using Self = SparseFieldLayer;
  using Superclass = Object;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

  itkNewMacro(Self);

  itkOverrideGetNameOfClassMacro(SparseFieldLayer);

  using NodeType = TNodeType;

  using ValueType = NodeType;

  using Iterator = SparseFieldLayerIterator<NodeType>;

  using ConstIterator = ConstSparseFieldLayerIterator<NodeType>;

  struct RegionType
  {
    ConstIterator first;
    ConstIterator last; // this is one past the actual last element
  };
 
  using RegionListType = std::vector<RegionType>;

  NodeType *
  Front()
  {
    return m_HeadNode->Next;
  }

  const NodeType *
  Front() const
  {
    return m_HeadNode->Next;
  }

  void
  PopFront()
  {
    m_HeadNode->Next = m_HeadNode->Next->Next;
    m_HeadNode->Next->Previous = m_HeadNode.get();
    m_Size -= 1;
  }

  void
  PushFront(NodeType * n)
  {
    n->Next = m_HeadNode->Next;
    n->Previous = m_HeadNode.get();
    m_HeadNode->Next->Previous = n;
    m_HeadNode->Next = n;
    m_Size += 1;
  }

  void
  Unlink(NodeType * n)
  {
    n->Previous->Next = n->Next;
    n->Next->Previous = n->Previous;
    m_Size -= 1;
  }

  Iterator
  Begin()
  {
    return Iterator(m_HeadNode->Next);
  }

  ConstIterator
  Begin() const
  {
    return ConstIterator(m_HeadNode->Next);
  }

  Iterator
  End()
  {
    return Iterator(m_HeadNode.get());
  }

  ConstIterator
  End() const
  {
    return ConstIterator(m_HeadNode.get());
  }

  bool
  Empty() const
  {
    if (m_HeadNode->Next == m_HeadNode.get())
    {
      return true;
    }
 
    return false;
  }

  unsigned int
  Size() const;

  RegionListType
  SplitRegions(int num) const;
 
protected:
  SparseFieldLayer();
  ~SparseFieldLayer() override = default;
  void
  PrintSelf(std::ostream & os, Indent indent) const override;
 
private:
  const std::unique_ptr<NodeType> m_HeadNode{ std::make_unique<NodeType>() };
  unsigned int                    m_Size{};
};
} // end namespace itk
 
#ifndef ITK_MANUAL_INSTANTIATION
#  include "itkSparseFieldLayer.hxx"
#endif
 
#endif