subt.h

Go to the documentation of this file.

/*
 *  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
 *
 *  subt.h
 *  May 8, 2013
 *
 */

#ifndef TILEDARRAY_TILE_OP_SUBT_H__INCLUDED
#define TILEDARRAY_TILE_OP_SUBT_H__INCLUDED

#include <TiledArray/tile_op/tile_interface.h>
#include "../tile_interface/scale.h"
#include "../tile_interface/permute.h"
#include "../tile_interface/clone.h"
#include <TiledArray/zero_tensor.h>

namespace TiledArray {
  namespace detail {


    template <typename Result, typename Left, typename Right,
        bool LeftConsumable, bool RightConsumable>
    class Subt {
    public:

      typedef Subt<Result, Left, Right, LeftConsumable, RightConsumable> Subt_;
      typedef Left left_type; 
      typedef Right right_type; 
      typedef Result result_type; 

      static constexpr bool left_is_consumable =
          LeftConsumable && std::is_same<result_type, left_type>::value;
      static constexpr bool right_is_consumable =
          RightConsumable && std::is_same<result_type, right_type>::value;

    private:

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

      static result_type eval(const left_type& first, const right_type& second,
          const Permutation& perm)
      {
        using TiledArray::subt;
        return subt(first, second, perm);
      }

      static result_type eval(ZeroTensor, const right_type& second,
          const Permutation& perm)
      {
        using TiledArray::neg;
        return neg(second, perm);
      }

      static result_type eval(const left_type& first, ZeroTensor,
          const Permutation& perm)
      {
        using TiledArray::permute;
        return permute(first, perm);
      }

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

      template <bool LC, bool RC,
          typename std::enable_if<!(LC || RC)>::type* = nullptr>
      static result_type eval(const left_type& first, const right_type& second) {
        using TiledArray::subt;
        return subt(first, second);
      }

      template <bool LC, bool RC,
          typename std::enable_if<LC>::type* = nullptr>
      static result_type eval(left_type& first, const right_type& second) {
        using TiledArray::subt_to;
        return subt_to(first, second);
      }

      template <bool LC, bool RC,
          typename std::enable_if<!LC && RC>::type* = nullptr>
      static result_type eval(const left_type& first, right_type& second) {
        using TiledArray::subt_to;
        return subt_to(second, first, -1);
      }

      template <bool LC, bool RC,
          typename std::enable_if<!RC>::type* = nullptr>
      static result_type eval(ZeroTensor, const right_type& second) {
        using TiledArray::neg;
        return neg(second);
      }

      template <bool LC, bool RC,
          typename std::enable_if<RC>::type* = nullptr>
      static result_type eval(ZeroTensor, right_type& second) {
        using TiledArray::neg_to;
        return neg_to(second);
      }

      template <bool LC, bool RC,
          typename std::enable_if<!LC>::type* = nullptr>
      static result_type eval(const left_type& first, ZeroTensor) {
        TiledArray::Clone<result_type, left_type> clone;
        return clone(first);
      }

      template <bool LC, bool RC,
          typename std::enable_if<LC>::type* = nullptr>
      static result_type eval(left_type& first, ZeroTensor) {
        return first;
      }

    public:


      template <typename L, typename R>
      result_type operator()(L&& left, R&& right, const Permutation& perm) const {
        return eval(std::forward<L>(left), std::forward<R>(right), perm);
      }


      template <typename L, typename R>
      result_type operator()(L&& left, R&& right) const {
        return Subt_::template eval<left_is_consumable, right_is_consumable>(
            std::forward<L>(left), std::forward<R>(right));
      }


      template <typename R>
      result_type consume_left(left_type& left, R&& right) const {
        constexpr bool can_consume_left =
            is_consumable_tile<left_type>::value &&
            std::is_same<result_type, left_type>::value;
        constexpr bool can_consume_right = right_is_consumable &&
            ! (std::is_const<R>::value || can_consume_left);
        return Subt_::template eval<can_consume_left, can_consume_right>(left,
            std::forward<R>(right));
      }


      template <typename L>
      result_type consume_right(L&& left, right_type& right) const {
        constexpr bool can_consume_right =
            is_consumable_tile<right_type>::value &&
            std::is_same<result_type, right_type>::value;
        constexpr bool can_consume_left = left_is_consumable &&
            ! (std::is_const<L>::value || can_consume_right);
        return Subt_::template eval<can_consume_left, can_consume_right>(
            std::forward<L>(left), right);
      }

    }; // class Subt


    template <typename Result, typename Left, typename Right, typename Scalar,
        bool LeftConsumable, bool RightConsumable>
    class ScalSubt {
    public:

      typedef ScalSubt<Result, Left, Right, Scalar, LeftConsumable,
          RightConsumable> ScalSubt_; 
      typedef Left left_type; 
      typedef Right right_type; 
      typedef Scalar scalar_type; 
      typedef Result result_type; 

      static constexpr bool left_is_consumable =
          LeftConsumable && std::is_same<result_type, left_type>::value;
      static constexpr bool right_is_consumable =
          RightConsumable && std::is_same<result_type, right_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 left_type& first, const right_type& second,
          const Permutation& perm) const
      {
        using TiledArray::subt;
        return subt(first, second, factor_, perm);
      }

      result_type eval(ZeroTensor, const right_type& second,
          const Permutation& perm) const
      {
        using TiledArray::scale;
        return scale(second, -factor_, perm);
      }

      result_type eval(const left_type& first, ZeroTensor,
          const Permutation& perm) const
      {
        using TiledArray::scale;
        return scale(first, factor_, perm);
      }

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

      template <bool LC, bool RC,
          typename std::enable_if<!(LC || RC)>::type* = nullptr>
      result_type eval(const left_type& first, const right_type& second) const {
        using TiledArray::subt;
        return subt(first, second, factor_);
      }

      template <bool LC, bool RC,
          typename std::enable_if<LC>::type* = nullptr>
      result_type eval(left_type& first, const right_type& second) const {
        using TiledArray::subt_to;
        return subt_to(first, second, factor_);
      }

      template <bool LC, bool RC,
          typename std::enable_if<!LC && RC>::type* = nullptr>
      result_type eval(const left_type& first, right_type& second) const {
        using TiledArray::subt_to;
        return subt_to(second, first, -factor_);
      }

      template <bool LC, bool RC,
          typename std::enable_if<!RC>::type* = nullptr>
      result_type eval(ZeroTensor, const right_type& second) const {
        using TiledArray::scale;
        return scale(second, -factor_);
      }

      template <bool LC, bool RC,
          typename std::enable_if<RC>::type* = nullptr>
      result_type eval(ZeroTensor, right_type& second) const {
        using TiledArray::scale_to;
        return scale_to(second, -factor_);
      }

      template <bool LC, bool RC,
          typename std::enable_if<!LC>::type* = nullptr>
      result_type eval(const left_type& first, ZeroTensor) const {
        using TiledArray::scale;
        return scale(first, factor_);
      }

      template <bool LC, bool RC,
          typename std::enable_if<LC>::type* = nullptr>
      result_type eval(left_type& first, ZeroTensor) const {
        using TiledArray::scale_to;
        return scale_to(first, factor_);
      }

    public:

      // Compiler generated functions
      ScalSubt(const ScalSubt_&) = default;
      ScalSubt(ScalSubt_&&) = default;
      ~ScalSubt() = default;
      ScalSubt_& operator=(const ScalSubt_&) = default;
      ScalSubt_& operator=(ScalSubt_&&) = default;


      explicit ScalSubt(const Scalar factor) : factor_(factor) { }


      template <typename L, typename R>
      result_type
      operator()(L&& left, R&& right, const Permutation& perm) const {
        return eval(std::forward<L>(left), std::forward<R>(right), perm);
      }


      template <typename L, typename R>
      result_type operator()(L&& left, R&& right) const {
        return ScalSubt_::template eval<left_is_consumable, right_is_consumable>(
            std::forward<L>(left), std::forward<R>(right));
      }


      template <typename R>
      result_type consume_left(left_type& left, R&& right) const {
        constexpr bool can_consume_left =
            is_consumable_tile<left_type>::value &&
            std::is_same<result_type, left_type>::value;
        constexpr bool can_consume_right = right_is_consumable &&
            ! (std::is_const<R>::value || can_consume_left);
        return ScalSubt_::template eval<can_consume_left, can_consume_right>(
            left, std::forward<R>(right));
      }


      template <typename L>
      result_type consume_right(L&& left, right_type& right) const {
        constexpr bool can_consume_right =
            is_consumable_tile<right_type>::value &&
            std::is_same<result_type, right_type>::value;
        constexpr bool can_consume_left = left_is_consumable &&
            ! (std::is_const<L>::value || can_consume_right);
        return ScalSubt_::template eval<can_consume_left, can_consume_right>(
            std::forward<L>(left), right);
      }

    }; // class ScalSubt

  } // namespace detail
} // namespace TiledArray

#endif // TILEDARRAY_TILE_OP_SUBT_H__INCLUDED