side_effect_strategy.hh

// This file is a part of Aurelia.
// Copyright (C) 2010  Valentin David
// Copyright (C) 2010  University of Bergen
//
// 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/>.
#ifndef __SIDE_EFFECT_STRATEGY_HH
# define __SIDE_EFFECT_STRATEGY_HH

# include "../strategies.hh"
# include <memory>

namespace aurelia {

  template <typename Model>
  struct side_effect_strategy_concept {
    typedef typename Model::strat strat;
    typedef typename Model::input input;
    typedef typename Model::output output;
#ifdef DOC_GEN
    output operator()(strat&, input);
#else
    static_assert(std::is_same<decltype(std::declval<strat&>()
                                        (std::declval<input>())),
                  output>::value,
                  "operator() does not return the right type");

    typedef void check;
#endif
  };
  template <typename S, typename I>
  struct default_side_effect_strategy_model {
    typedef S strat;
    typedef I input;
    typedef decltype(std::declval<strat&>()(std::declval<input>())) output;
  };
  template <typename S, typename I>
  struct side_effect_strategy_model {
    typedef default_side_effect_strategy_model<S, I> model;
  };

  template <typename Kernel>
  struct side_effect_strategy {
  private:
    std::shared_ptr<Kernel> k;

  public:
    side_effect_strategy(const Kernel& k): k(new Kernel(k)) {}
    side_effect_strategy(const side_effect_strategy& other): k(other.k) {}

    void swap(side_effect_strategy& other) {
      std::swap(k, other.k);
    }

    side_effect_strategy& operator=(side_effect_strategy other) {
      this->swap(other);
      return *this;
    }

    template <typename T,
              typename M =
        typename side_effect_strategy_model<Kernel, T>::model>
    typename M::output
    operator()(const T& t) const {
      typedef typename side_effect_strategy_concept<M>::check requires;
      return (*k)(t);
    }

    const Kernel* operator->() const {
      return k.operator->();
    }

    Kernel* operator->() {
      return k.operator->();
    }

    Kernel& operator*() {
      return *k;
    }

    const Kernel& operator*() const {
      return *k;
    }
  };

  template <typename Kernel>
  side_effect_strategy<Kernel> side_effect(const Kernel& k) {
    return side_effect_strategy<Kernel>(k);
  }

}

#endif