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//  This code is based on the algorithm presented in the paper:
//  “Parallel Peak Pruning for Scalable SMP Contour Tree Computation.”
//  Hamish Carr, Gunther Weber, Christopher Sewell, and James Ahrens.
//  Proceedings of the IEEE Symposium on Large Data Analysis and Visualization
//  (LDAV), October 2016, Baltimore, Maryland.

#ifndef vtkm_worklet_contourtree_copy_neighbors_h
#define vtkm_worklet_contourtree_copy_neighbors_h

#include <vtkm/worklet/WorkletMapField.h>
#include <vtkm/worklet/contourtree/Types.h>

namespace vtkm
{
namespace worklet
{
namespace contourtree
{

// Worklet
class CopyNeighbors : public vtkm::worklet::WorkletMapField
{
public:
  using ControlSignature =
    void(FieldIn<IdType> activeSupernode,       // (input) index into supernodes
         WholeArrayIn<IdType> activeSupernodes, // (input) active supernode vertex IDs
         WholeArrayIn<IdType> arcs,             // (input) merge tree arcs
         FieldOut<IdType> sortVector);          // (output) neighbors for active edge
  using ExecutionSignature = _4(_1, _2, _3);
  using InputDomain = _1;

  // Constructor
  VTKM_EXEC_CONT
  CopyNeighbors() {}

  template <typename InFieldPortalType>
  VTKM_EXEC vtkm::Id operator()(const vtkm::Id& activeSupernode,
                                const InFieldPortalType& activeSupernodes,
                                const InFieldPortalType& arcs) const
  {
    vtkm::Id sortVector;
    vtkm::Id superID = activeSupernodes.Get(activeSupernode);
    vtkm::Id neighbour = arcs.Get(superID);
    sortVector = neighbour;
    return sortVector;
  }
}; // CopyNeighbors
}
}
}

#endif
