noop.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
 *
 *  noop.h
 *  June 27, 2013
 *
 */
 
#ifndef TILEDARRAY_TILE_OP_NOOP_H__INCLUDED
#define TILEDARRAY_TILE_OP_NOOP_H__INCLUDED
 
#include "../tile_interface/clone.h"
#include "../tile_interface/permute.h"
 
namespace TiledArray {
namespace detail {
 
 
template <typename Result, typename Arg, bool Consumable>
class Noop {
 public:
  typedef Noop<Result, Arg, Consumable> Noop_;  
  typedef Arg argument_type;                    
  typedef Result result_type;                   
 
  static constexpr bool is_consumable = Consumable;
 
 private:
  // Permuting tile evaluation function
  // These operations cannot consume the argument tile since this operation
  // requires temporary storage space.
  template <typename Perm,
            typename = std::enable_if_t<detail::is_permutation_v<Perm>>>
  result_type eval(const Arg& arg, const Perm& perm) const {
    TiledArray::Permute<Result, Arg> permute;
    return permute(arg, 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 Arg& arg) const {
    TiledArray::Clone<Result, Arg> clone;
    return clone(arg);
  }
 
  template <bool C, typename std::enable_if<C>::type* = nullptr>
  result_type eval(Arg& arg) const {
    return arg;
  }
 
 public:
 
  template <typename Perm,
            typename = std::enable_if_t<detail::is_permutation_v<Perm>>>
  result_type operator()(const argument_type& arg, const Perm& perm) const {
    return eval(arg, perm);
  }
 
 
  template <typename A>
  result_type operator()(A&& arg) const {
    return Noop_::template eval<is_consumable>(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 Noop_::template eval<can_consume>(arg);
  }
 
};  // class Noop
 
}  // namespace detail
}  // namespace TiledArray
 
#endif  // TILEDARRAY_TILE_OP_NOOP_H__INCLUDED