scal.h

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/*
 *  This file is a part of TiledArray.
 *  Copyright (C) 2013  Virginia Tech
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *  Justus Calvin
 *  Department of Chemistry, Virginia Tech
 *
 *  scal.h
 *  June 20, 2013
 *
 */

#ifndef TILEDARRAY_TILE_OP_SCAL_H__INCLUDED
#define TILEDARRAY_TILE_OP_SCAL_H__INCLUDED

#include <type_traits>
#include "../tile_interface/scale.h"
#include <TiledArray/tile_op/tile_interface.h>

namespace TiledArray {
  namespace detail {


    template <typename Result, typename Arg, typename Scalar, bool Consumable>
    class Scal {
    public:
      typedef Scal<Result, Arg, Scalar, Consumable> Scal_; 
      typedef Arg argument_type; 
      typedef Scalar scalar_type; 
      typedef Result result_type; 

      static constexpr bool is_consumable =
          Consumable && std::is_same<result_type, argument_type>::value;

    private:

      scalar_type factor_; 

      // Permuting tile evaluation function
      // These operations cannot consume the argument tile since this operation
      // requires temporary storage space.

      result_type eval(const Arg& arg, const Permutation& perm) const {
        using TiledArray::scale;
        return scale(arg, factor_, perm);
      }

      // Non-permuting tile evaluation functions
      // The compiler will select the correct functions based on the
      // consumability of the arguments.

      template <bool C, typename std::enable_if<!C>::type* = nullptr>
      result_type eval(const argument_type& arg) const {
        using TiledArray::scale;
        return scale(arg, factor_);
      }

      template <bool C, typename std::enable_if<C>::type* = nullptr>
      result_type eval(argument_type& arg) const {
        using TiledArray::scale_to;
        return scale_to(arg, factor_);
      }

    public:

      // Compiler generated functions
      Scal(const Scal_&) = default;
      Scal(Scal_&&) = default;
      ~Scal() = default;
      Scal_& operator=(const Scal_&) = default;
      Scal_& operator=(Scal_&&) = default;


      explicit Scal(const scalar_type factor) : factor_(factor) { }


      result_type
      operator()(const argument_type& arg, const Permutation& perm) const {
        return eval(arg, perm);
      }


      template <typename A>
      result_type operator()(A&& arg) const {
        return Scal_::template eval<is_consumable>(std::forward<A>(arg));
      }


      result_type consume(argument_type& arg) const {
        constexpr bool can_consume = is_consumable_tile<argument_type>::value &&
            std::is_same<result_type, argument_type>::value;
        return Scal_::template eval<can_consume>(arg);
      }

    }; // class Scal

  } // namespace detail
} // namespace TiledArray

#endif // TILEDARRAY_TILE_OP_SCAL_H__INCLUDED