scope.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 __SCOPE_HH
# define __SCOPE_HH

# include "../strategies.hh"
# include "../../patterns/variable.hh"

namespace aurelia {

  template <typename Strat, typename T>
  struct scope_strategy {
  private:
    Strat s;
    T v;

  public:
    scope_strategy(const Strat& s, const T& v): s(s), v(v) {}
    scope_strategy(const scope_strategy& other): s(other.s), v(other.v) {}

    template <typename U>
    typename strategy_model<Strat, U>::model::output
    operator()(const U& t) const {
      typedef typename strategy_concept
        <typename strategy_model<Strat, U>::model>::check
        require;

      struct onexit {
        const T& v;
        onexit(const T& v): v(v) {
          v.push();
        }
        ~onexit() {
          v.pop();
          }
      };
      onexit oe(v);
      return s(t);
    }
  };

  template <typename Strat, typename T>
  scope_strategy<Strat, variable<T> > scope(const variable<T>& v,
                                            const Strat& s) {
    return scope_strategy<Strat, variable<T> >(s, v);
  }

  template <typename T>
  struct is_variable: public std::false_type {};

  template <typename T>
  struct is_variable<variable<T> >: public std::true_type {};

  template <typename Strat, typename L,
            typename M =
            typename list_model<L>::model,
            typename = typename
            std::enable_if<all_elements<is_variable, L>::value>::type>
  scope_strategy<Strat, L>
  scope(const L& v, const Strat& s) {
    typedef typename list_concept<M>::check require;
    return scope_strategy<Strat, L>(s, v);
  }
}

#endif