one.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 __ONE_HH
# define __ONE_HH

# include "../../terms/term.hh"
# include "../strategies.hh"

namespace aurelia {

  template <typename Strat>
  struct one_strategy {
  private:
    Strat s;
  public:
    one_strategy(const Strat& s): s(s) {
    }

    template <typename T>
    T operator()(const T& term) const {
      unsigned arity = term.constructor().arity();
      if (arity > 0) {
        for (unsigned i = 0;
             i < arity;
             ++i) {
          try {
            T success = s(term[i]);
            if (diff_no_conv(success, term[i])) {
              return term;
            }
            T *list = (T*)malloc(arity
                                 *sizeof(T));
            for (unsigned j = 0; j < arity; ++j) {
              if (j == i)
                new (list+j) T(success);
              else
                new (list+j) T(term[j]);
            }
            return T(term.constructor(), list);
          } catch (failure) {
          }
        }
        throw failure();
      }
      else
        throw failure();
    }
  };

  template <typename Strat>
  one_strategy<Strat> one(const Strat& s) {
    return one_strategy<Strat>(s);
  }

}

#endif