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