itkOneWayEquivalencyTable.h

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/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  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
 *
 *         http://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 itkOneWayEquivalencyTable_h
#define itkOneWayEquivalencyTable_h


#include "itkProcessObject.h"
#include "itksys/hash_map.hxx"
#include "ITKWatershedsExport.h"

namespace itk
{
class ITKWatersheds_EXPORT OneWayEquivalencyTable:public DataObject
{
public:
  ITK_DISALLOW_COPY_AND_ASSIGN(OneWayEquivalencyTable);

  using Self = OneWayEquivalencyTable;
  using Superclass = DataObject;
  using Pointer = SmartPointer< Self >;
  using ConstPointer = SmartPointer< const Self >;
  itkNewMacro(Self);
  itkTypeMacro(OneWayEquivalencyTable, DataObject);

  using HashTableType = itksys::hash_map< unsigned long, unsigned long,
                            itksys::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);

  unsigned long Lookup(const unsigned long a) const
  {
    ConstIterator result = m_HashMap.find(a);

    if ( result == m_HashMap.end() ) { return a; }
    else { 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; }
    else { return true; }
  }

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

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

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

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

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

  //  void PrintHashTable();

protected:
  OneWayEquivalencyTable()  = default;
  ~OneWayEquivalencyTable() override = default;
  void PrintSelf(std::ostream & os, Indent indent) const override;

  HashTableType m_HashMap;
};
} // end namespace itk

#endif