Intrepid2_ViewIterator.hpp

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// @HEADER
// *****************************************************************************
//                           Intrepid2 Package
//
// Copyright 2007 NTESS and the Intrepid2 contributors.
// SPDX-License-Identifier: BSD-3-Clause
// *****************************************************************************
// @HEADER

#ifndef Intrepid2_ViewIterator_h
#define Intrepid2_ViewIterator_h

#include "Intrepid2_Utils.hpp"

namespace Intrepid2
{
  template<class ViewType,typename ScalarType>
  class ViewIterator
  {
    ViewType view_;
    Kokkos::Array<int,7> dims_; // 7 is the maximum rank of a Kokkos view
    Kokkos::Array<int,7> index_;
  public:
    KOKKOS_INLINE_FUNCTION
    ViewIterator(ViewType view)
    :
    view_(view)
    {
      for (unsigned d=0; d<getFunctorRank(view); d++)
      {
        dims_[d] = view.extent_int(d);
        index_[d] = 0;
      }
      for (unsigned d=getFunctorRank(view); d<7; d++)
      {
        dims_[d] = 1;
        index_[d] = 0;
      }
    }
    
    KOKKOS_INLINE_FUNCTION
    ScalarType get()
    {
      return view_.access(index_[0],index_[1],index_[2],index_[3],index_[4],index_[5],index_[6]);
    }
    
    KOKKOS_INLINE_FUNCTION
    void set(const ScalarType &value)
    {
      view_.access(index_[0],index_[1],index_[2],index_[3],index_[4],index_[5],index_[6]) = value;
    }
    
    KOKKOS_INLINE_FUNCTION
    int nextIncrementRank()
    {
      const int rank = getFunctorRank(view_);
      for (int r=rank-1; r>=0; r--)
      {
        if (index_[r]+1 < dims_[r]) // can increment without going out of bounds in this dimension
        {
          return r;
        }
      }
      // next increment will take us out of bounds
      return -1;
    }
    
    KOKKOS_INLINE_FUNCTION
    int increment()
    {
      const int rank = getFunctorRank(view_);
      for (int r=rank-1; r>=0; r--)
      {
        if (index_[r]+1 < dims_[r]) // can increment without going out of bounds in this dimension
        {
          index_[r]++;
          // we've completed the increment
          return r;
        }
        else
        {
          // next rank should be incremented -- this one should reset to 0
          index_[r] = 0;
        }
      }
      // if we get here, we have run through all ranks, setting them to 0 -- we've cycled around
      // and in that sense have not completed the increment
      return -1;
    }
    
    KOKKOS_INLINE_FUNCTION
    bool decrement()
    {
      const auto rank = view_.rank();
      for (int r=rank-1; r>=0; r--)
      {
        if (index_[r]-1 >= 0) // can decrement without going out of bounds in this dimension
        {
          index_[r]--;
          return true; // we've completed the decrement
        }
        else
        {
          // next rank should be decremented -- this one should cycle round to dim_[r]-1
          index_[r] = dims_[r]-1;
        }
      }
      // if we get here, we've gone past 0 in every dimension, so we should return false
      // -- we have not completed the decrement in an in-bounds fashion, but have cycled round to the last value
      // to maintain a clean state, let's reset
      reset();
      return false;
    }
    
    KOKKOS_INLINE_FUNCTION
    int getEnumerationIndex()
    {
      int index_1D = 0;
      for (int d=0; d<7; d++)
      {
        if (d>0) index_1D *= dims_[d-1];
        index_1D += index_[d];
      }
      
      return index_1D;
    }
    
    KOKKOS_INLINE_FUNCTION
    void setEnumerationIndex(const int &enumerationIndex)
    {
      Kokkos::Array<int,7> location;
      int remainder = enumerationIndex;
      for (int d=6; d>=0; d--)
      {
        location[d] = remainder % dims_[d];
        remainder  /= dims_[d];
      }
      
      setLocation(location);
    }
    
    KOKKOS_INLINE_FUNCTION
    int getIndex(int dimension)
    {
      return index_[dimension];
    }
    
    KOKKOS_INLINE_FUNCTION
    int getExtent(int dimension)
    {
      return dims_[dimension];
    }
    
    KOKKOS_INLINE_FUNCTION
    void reset(unsigned from_rank_number=0)
    {
      for (unsigned d=from_rank_number; d<view_.rank(); d++)
      {
        index_[d] = 0;
      }
    }
    
    KOKKOS_INLINE_FUNCTION
    void setLocation(const Kokkos::Array<int,7> &location)
    {
      index_ = location;
    }
    
    KOKKOS_INLINE_FUNCTION
    Kokkos::Array<int,7> & getLocation()
    {
      return index_;
    }
  };
} // namespace Intrepid2

#endif /* Intrepid2_ViewIterator_h */