Tpetra_Details_ScalarViewTraits.hpp

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// @HEADER
// *****************************************************************************
//          Tpetra: Templated Linear Algebra Services Package
//
// Copyright 2008 NTESS and the Tpetra contributors.
// SPDX-License-Identifier: BSD-3-Clause
// *****************************************************************************
// @HEADER

#ifndef TPETRA_DETAILS_SCALARVIEWTRAITS_HPP
#define TPETRA_DETAILS_SCALARVIEWTRAITS_HPP


#include "Tpetra_Details_PackTraits.hpp"

namespace Tpetra {
namespace Details {

template<class T, class D>
struct ScalarViewTraits {
  using value_type = T;
  using device_type = D;

  static Kokkos::View<value_type*, device_type>
  allocateArray (const value_type& x,
                 const size_t numEnt,
                 const std::string& label = "")
  {
    using view_type = Kokkos::View<value_type*, device_type>;

    // When the traits::specialize type is non-void this exploits
    // the fact that Kokkos::View's constructor ignores
    // size arguments beyond what the View's type specifies.  For
    // value_type = Stokhos::UQ::PCE<S>, numValuesPerScalar returns
    // something other than 1, and the constructor will actually use
    // that value.
    // Otherwise, the number of arguments must match the dynamic rank
    // (i.e. number *'s with the value_type of the View)
    const size_t numVals = PackTraits<value_type>::numValuesPerScalar (x);
    if (std::is_same<typename view_type::traits::specialize, void>::value ) {
      return view_type (label, numEnt);
    }
    else {
      return view_type (label, numEnt, numVals);
    }
  }
}; // struct ScalarViewTraits

} // namespace Details
} // namespace Tpetra

#endif // TPETRA_DETAILS_SCALARVIEWTRAITS_HPP