itkEquivalencyTable.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 itkEquivalencyTable_h
#define itkEquivalencyTable_h
 
 
#include "itkProcessObject.h"
#include <unordered_map>
 
namespace itk
{
class ITKCommon_EXPORT EquivalencyTable : public DataObject
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(EquivalencyTable);

  using Self = EquivalencyTable;
  using Superclass = DataObject;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;
  itkNewMacro(Self);
  itkOverrideGetNameOfClassMacro(EquivalencyTable);

  using HashTableType = std::unordered_map<unsigned long, unsigned long, std::hash<unsigned long>>;
 
  using Iterator = HashTableType::iterator;
  using ConstIterator = HashTableType::const_iterator;
  using ValueType = HashTableType::value_type;

  void
  Flatten();

  bool
  Add(unsigned long a, unsigned long b);

  bool
  AddAndFlatten(unsigned long a, unsigned long b);

  unsigned long
  Lookup(const unsigned long a) const
  {
    auto result = m_HashMap.find(a);
 
    if (result == m_HashMap.end())
    {
      return a;
    }
 
    return result->second;
  }

  unsigned long
  RecursiveLookup(const unsigned long a) const;

  bool
  IsEntry(const unsigned long a) const
  {
    if (m_HashMap.find(a) == m_HashMap.end())
    {
      return false;
    }
 
    return true;
  }

  void
  Erase(const unsigned long a)
  {
    m_HashMap.erase(a);
  }

  void
  Clear()
  {
    m_HashMap.clear();
  }

  bool
  Empty() const
  {
    return m_HashMap.empty();
  }

  HashTableType::size_type
  Size() const
  {
    return m_HashMap.size();
  }

  Iterator
  Begin()
  {
    return m_HashMap.begin();
  }

  Iterator
  End()
  {
    return m_HashMap.end();
  }

  //  void PrintHashTable();
 
protected:
  EquivalencyTable() = default;
  ~EquivalencyTable() override = default;
  void
  PrintSelf(std::ostream & os, Indent indent) const override;
 
  HashTableType m_HashMap{};
};
} // end namespace itk
 
#endif