text: /*=========================================================================
   *
   *  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 itkLabelObjectAccessors_h
  #define itkLabelObjectAccessors_h
  
  #include "itkMacro.h"
  
  /*
   *
   * This code was contributed in the Insight Journal paper:
   * "Label object representation and manipulation with ITK"
   * by Lehmann G.
   * https://hdl.handle.net/1926/584
   * http://www.insight-journal.org/browse/publication/176
   *
   */
  
  namespace itk
  {
  namespace Functor
  {
  template< typename TLabelObject >
  class LabelLabelObjectAccessor
  {
  public:
    typedef TLabelObject                        LabelObjectType;
    typedef typename LabelObjectType::LabelType AttributeValueType;
  
    inline AttributeValueType operator()(const LabelObjectType *labelObject) const
    {
      return labelObject->GetLabel();
    }
  };
  
  template< typename TLabelObject >
  class NumberOfLinesLabelObjectAccessor
  {
  public:
    typedef TLabelObject LabelObjectType;
    typedef int          AttributeValueType;
  
    inline AttributeValueType operator()(const LabelObjectType *labelObject) const
    {
      return labelObject->GetNumberOfLines();
    }
  };
  
  template< typename TLabelObject, typename TAttributeAccessor >
  class LabelObjectComparator
  {
  public:
    typedef TLabelObject       LabelObjectType;
    typedef TAttributeAccessor AttributeAccessorType;
    bool operator()(const LabelObjectType *a, const LabelObjectType *b) const
    {
      return m_Accessor(a) > m_Accessor(b);
    }
  
    LabelObjectComparator() {}
    LabelObjectComparator(LabelObjectComparator const & from)
    {
      m_Accessor = from.m_Accessor;
    }
  
  private:
    AttributeAccessorType m_Accessor;
  };
  
  template< typename TLabelObject, typename TAttributeAccessor >
  class LabelObjectReverseComparator
  {
  public:
    typedef TLabelObject       LabelObjectType;
    typedef TAttributeAccessor AttributeAccessorType;
    bool operator()(const LabelObjectType *a, const LabelObjectType *b) const
    {
      return m_Accessor(a) < m_Accessor(b);
    }
  
    LabelObjectReverseComparator() {}
    LabelObjectReverseComparator(LabelObjectReverseComparator const & from)
    {
      m_Accessor = from.m_Accessor;
    }
  
  private:
    AttributeAccessorType m_Accessor;
  };
  }
  } // end namespace itk
  
  #endif
  