scale.h

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/*
 *  This file is a part of TiledArray.
 *  Copyright (C) 2016  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
 *  Department of Chemistry, Virginia Tech
 *
 *  scale.h
 *  Jan 11, 2016
 *
 */

#ifndef TILEDARRAY_SRC_TILEDARRAY_TILE_INTERFACE_SCALE_H__INCLUDED
#define TILEDARRAY_SRC_TILEDARRAY_TILE_INTERFACE_SCALE_H__INCLUDED

#include "../type_traits.h"
#include "../permutation.h"
#include "cast.h"

namespace TiledArray {


  template <typename Arg, typename Scalar,
      typename std::enable_if<TiledArray::detail::is_numeric<Scalar>::value>::type* = nullptr>
  inline auto scale(const Arg& arg, const Scalar factor)
  { return arg.scale(factor); }


  template <typename Arg, typename Scalar,
      typename std::enable_if<TiledArray::detail::is_numeric<Scalar>::value>::type* = nullptr>
  inline auto scale(const Arg& arg, const Scalar factor, const Permutation& perm)
  { return arg.scale(factor, perm); }


  template <typename Result, typename Scalar,
      typename std::enable_if<TiledArray::detail::is_numeric<Scalar>::value>::type* = nullptr>
  inline Result& scale_to(Result& result, const Scalar factor)
  { return result.scale_to(factor); }


  namespace tile_interface {

    template <typename... T>
    using result_of_scale_t = decltype(scale(std::declval<T>()...));

    template <typename... T>
    using result_of_scale_to_t = decltype(scale_to(std::declval<T>()...));


    template <typename Arg, typename Scalar, typename Enabler = void>
    struct scale_trait {
      typedef Arg type;
    };

    template <typename Arg, typename Scalar>
    struct scale_trait<Arg, Scalar,
        typename std::enable_if<
            TiledArray::detail::is_type<result_of_scale_t<Arg, Scalar> >::value
        >::type>
    {
      typedef result_of_scale_t<Arg> type;
    };

    template <typename Result, typename Arg, typename Scalar,
        typename Enabler = void>
    class Scale {
    public:
      static_assert(TiledArray::detail::is_numeric<Scalar>::value,
          "Cannot scale tiles by a non-scalar type");

      typedef Result result_type; 
      typedef Arg argument_type; 
      typedef Scalar scalar_type; 

      result_type operator()(const argument_type& arg,
          const scalar_type factor) const
      {
        using TiledArray::scale;
        return scale(arg, factor);
      }

      result_type operator()(const argument_type& arg,
          const scalar_type factor, const Permutation& perm) const
      {
        using TiledArray::scale;
        return scale(arg, factor, perm);
      }
    };

    template <typename Result, typename Arg, typename Scalar>
    class Scale<Result, Arg, Scalar,
        typename std::enable_if<
            ! std::is_same<Result, result_of_scale_t<Arg, Scalar> >::value
        >::type>
    {
    public:
      static_assert(TiledArray::detail::is_numeric<Scalar>::value,
          "Cannot scale tiles by a non-scalar type");

      typedef Result result_type; 
      typedef Arg argument_type; 
      typedef Scalar scalar_type; 

      result_type operator()(const argument_type& arg,
          const scalar_type factor) const
      {
        using TiledArray::scale;
        TiledArray::Cast<Result, result_of_scale_t<Arg, Scalar> > cast;
        return cast(scale(arg, factor));
      }


      result_type operator()(const argument_type& arg,
          const scalar_type factor, const Permutation& perm) const
      {
        using TiledArray::scale;
        TiledArray::Cast<Result, result_of_scale_t<Arg, Scalar, Permutation> > cast;
        return cast(scale(arg, factor, perm));
      }

    };


    template <typename Result, typename Arg, typename Scalar,
        typename Enabler = void>
    class ScaleTo {
    public:
      static_assert(TiledArray::detail::is_numeric<Scalar>::value,
          "Cannot scale tiles by a non-scalar type");

      typedef Result result_type; 
      typedef Arg argument_type; 
      typedef Scalar scalar_type; 

      result_type operator()(argument_type& arg,
          const scalar_type factor) const
      {
        using TiledArray::scale_to;
        return scale_to(arg, factor);
      }

    };

    template <typename Result, typename Arg, typename Scalar>
    class ScaleTo<Result, Arg, Scalar,
        typename std::enable_if<
            ! std::is_same<Result, result_of_scale_t<Arg, Scalar> >::value
        >::type>
    {
    public:
      static_assert(TiledArray::detail::is_numeric<Scalar>::value,
          "Cannot scale tiles by a non-scalar type");

      typedef Result result_type; 
      typedef Arg argument_type; 
      typedef Scalar scalar_type; 

      result_type operator()(const argument_type& arg,
          const scalar_type factor) const
      {
        using TiledArray::scale_to;
        TiledArray::Cast<Result, result_of_scale_to_t<Arg, Scalar> > cast;
        return cast(scale_to(arg, factor));
      }

    };

  } // namespace tile_interface



  template <typename Arg, typename Scalar>
  struct scale_trait :
      public TiledArray::tile_interface::scale_trait<Arg, Scalar>
  { };



  template <typename Result, typename Arg, typename Scalar>
  class Scale :
      public TiledArray::tile_interface::Scale<Result, Arg, Scalar>
  { };


} // namespace TiledArray

#endif // TILEDARRAY_SRC_TILEDARRAY_TILE_INTERFACE_SCALE_H__INCLUDED