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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_subrange_offset_h
#define vtkm_worklet_contourtree_subrange_offset_h

#include <vtkm/worklet/WorkletMapField.h>

namespace vtkm
{
namespace worklet
{
namespace contourtree
{

// Worklet for doing regular to candidate
class SubrangeOffset : public vtkm::worklet::WorkletMapField
{
public:
  typedef void ControlSignature(
    FieldIn<IdType> sortID,           // (input) index into sorted vertices
    WholeArrayIn<IdType> sortVector,  // (input) sorted vector of vertices
    WholeArrayOut<IdType> candidate); // (output) candidate
  typedef void ExecutionSignature(_1, _2, _3);
  using InputDomain = _1;

  // Constructor
  VTKM_EXEC_CONT
  SubrangeOffset() {}

  template <typename InFieldPortalType, typename OutFieldPortalType>
  VTKM_EXEC void operator()(const vtkm::Id& sortID,
                            const InFieldPortalType& sortVector,
                            const OutFieldPortalType& candidate) const
  {
    if (sortVector.Get(sortID) != sortVector.Get(sortID - 1))
      candidate.Set(sortVector.Get(sortID), sortID);
  }
}; // SubrangeOffset
}
}
}

#endif