match.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 __MATCH_HH
# define __MATCH_HH

# include "../../terms/term.hh"
# include "../../patterns/pattern.hh"
# include "../../patterns/variable.hh"
# include "../strategies.hh"

namespace aurelia {

  template <typename Pat>
  struct match_strategy {
    typedef typename pattern_concept<typename pattern_model<Pat>::model>
    ::check require;
  private:
    Pat pat;
  public:
    match_strategy(const Pat& pat): pat(pat) {
    }

    template <typename T>
    T operator()(const T& term) const {
      Pat p(pat);
      p = term;
      return term;
    }
  };

  template <typename Pool>
  struct match_strategy<untyped_term<Pool> > {
  private:
    untyped_term<Pool> pat;
  public:
    match_strategy(const untyped_term<Pool>& pat): pat(pat) {
    }

    untyped_term<Pool> operator()(const untyped_term<Pool>& term) const {
      if (term != pat)
        throw failure();
      return term;
    }
  };
  /* @} */

  template <typename Pool, typename List>
  match_strategy<untyped_pattern<Pool, List> >
  operator~(const untyped_pattern<Pool, List>& p) {
    return match_strategy<untyped_pattern<Pool, List> >(p);
  }

  template <typename T>
  match_strategy<variable<T> > operator~(const variable<T>& t) {
    return match_strategy<variable<T> >(t);
  }

  template <typename Pool>
  match_strategy<untyped_term<Pool> > operator~(const untyped_term<Pool>& t) {
    return match_strategy<untyped_term<Pool> >(t);
  }

  template <typename Pool>
  match_strategy<untyped_term<Pool> > operator~(const untyped_constructor<Pool>& t) {
    return match_strategy<untyped_term<Pool> >(t);
  }


  template <typename Pattern,
            typename PattermModel = typename pattern_model<Pattern>::model>
  match_strategy<Pattern> operator~(const Pattern& pattern) {
    return match_strategy<Pattern>(pattern);
  }
}

#endif