unary_wrapper.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
 *
 *  binary_interface.h
 *  Oct 6, 2013
 *
 */

#ifndef TILEDARRAY_TILE_OP_UNARY_WRAPPER_H__INCLUDED
#define TILEDARRAY_TILE_OP_UNARY_WRAPPER_H__INCLUDED

#include <TiledArray/tile_op/tile_interface.h>
#include <TiledArray/permutation.h>
#include <TiledArray/zero_tensor.h>

namespace TiledArray {
  namespace detail {


    template <typename Op>
    class UnaryWrapper {
    public:
      typedef UnaryWrapper<Op> UnaryWrapper_;
      typedef typename Op::argument_type argument_type; 
      typedef typename Op::result_type result_type; 


      static constexpr bool is_consumable = Op::is_consumable;

      template <typename T>
      static constexpr auto is_lazy_tile_v = is_lazy_tile<std::decay_t<T>>::value;

      template <typename T>
      static constexpr auto is_array_tile_v = is_array_tile<std::decay_t<T>>::value;

      template <typename T>
      static constexpr auto is_nonarray_lazy_tile_v = is_lazy_tile_v<T> && !is_array_tile_v<T>;

      template <typename T>
      using eval_t = typename eval_trait<std::decay_t<T> >::type;

    private:

      Op op_; 
      Permutation perm_; 

    public:

      // Compiler generated functions
      UnaryWrapper(const UnaryWrapper_&) = default;
      UnaryWrapper(UnaryWrapper_&&) = default;
      ~UnaryWrapper() = default;
      UnaryWrapper_& operator=(const UnaryWrapper_&) = default;
      UnaryWrapper_& operator=(UnaryWrapper_&&) = default;

      UnaryWrapper(const Op& op, const Permutation& perm) : op_(op), perm_(perm) { }

      UnaryWrapper(const Op& op) : op_(op), perm_() { }



      const Permutation& permutation() const { return perm_; }



      auto operator()(argument_type& arg) const {
        return (perm_ ? op_(arg, perm_) : op_(arg) );
      }


      auto operator()(const argument_type& arg) const {
        return (perm_ ? op_(arg, perm_) : op_(arg) );
      }


      template <typename A,
                std::enable_if_t<is_nonarray_lazy_tile_v<A>>* = nullptr>
      auto operator()(A&& arg) const {
        using TiledArray::meta::invoke;
        return (perm_ ? invoke(op_, invoke_cast(std::forward<A>(arg)), perm_)
                      : invoke(op_, invoke_cast(std::forward<A>(arg))));
      }


      template <typename A, std::enable_if_t<is_array_tile_v<A>>* = nullptr>
      auto operator()(A&& arg) const {
        auto cast_arg = invoke_cast(std::forward<A>(arg));
        // TODO replace with generic lambda, replace cast_arg with std::move(cast_arg)
//        NB using this generic lambda breaks TaskFn ...
//        need to make TaskFn variadic and accepting callables, but this is a lot of MP
//
//        auto op_consume = [this](auto&& arg) {
//          return op_.consume(std::forward<decltype(arg)>(arg));
//        };
        auto op_consume = [this](eval_t<A>& arg) {
          return op_.consume(arg);
        };
        using TiledArray::meta::invoke;
        return (perm_ ? invoke(op_, std::move(cast_arg), perm_)
                      : (arg.is_consumable()
                             ? invoke(op_consume, cast_arg)
                             : invoke(op_, std::move(cast_arg))));
      }

      template <typename A, std::enable_if_t<is_lazy_tile_v<A>>* = nullptr>
      auto consume(A&& arg) const {
        auto cast_arg = invoke_cast(std::forward<A>(arg));
        // TODO replace with generic lambda, replace cast_arg with std::move(cast_arg)
//        NB using this generic lambda breaks TaskFn ...
//        need to make TaskFn variadic and accepting callables, but this is a lot of MP
//
//        auto op_consume = [this](auto&& arg) {
//          return op_.consume(std::forward<decltype(arg)>(arg));
//        };
        auto op_consume = [this](eval_t<A>& arg) {
          return op_.consume(arg);
        };
        using TiledArray::meta::invoke;
        return (perm_ ?
            invoke(op_, std::move(cast_arg), perm_) :
            invoke(op_consume, cast_arg));
      }

      template <typename A, std::enable_if_t<!is_lazy_tile_v<A>>* = nullptr>
      result_type consume(A&& arg) const {
        static_assert(std::is_same<std::decay_t<A>, argument_type>::value,
                      "UnaryWrapper::consume(A&&): invalid argument type A");
        return (perm_ ? op_(std::forward<A>(arg), perm_)
                      : op_.consume(std::forward<A>(arg)));
      }

    }; // class UnaryWrapper

  } // namespace detail
} // namespace TiledArray

#endif // TILEDARRAY_TILE_OP_UNARY_WRAPPER_H__INCLUDED