thompson.hxx

// thompson.hxx: this file is part of the Vaucanson project.
//
// Vaucanson, a generic library for finite state machines.
//
// Copyright (C) 2001, 2002, 2003, 2004 The Vaucanson Group.
//
// 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 2
// of the License, or (at your option) any later version.
//
// The complete GNU General Public Licence Notice can be found as the
// `COPYING' file in the root directory.
//
// The Vaucanson Group consists of people listed in the `AUTHORS' file.
//
#ifndef VCSN_ALGORITHMS_THOMPSON_HXX
# define VCSN_ALGORITHMS_THOMPSON_HXX

# include <vaucanson/algorithms/thompson.hh>

# include <vaucanson/automata/concept/automata_base.hh>
# include <vaucanson/algorithms/normalized.hh>

namespace vcsn {

  /*----------------.
  | ThompsonVisitor |
  `----------------*/
  // FIXME : Non optimal version.
  //         There are too much construction of automaton.

  // FIXME : from now, it is only working over LetterAutomaton

  template <class Auto_, class Monoid_, class Semiring_>
  class ThompsonVisitor :
      public rat::ConstNodeVisitor<Monoid_, Semiring_>
  {
    public :
      typedef Auto_                                     automaton_t;
      typedef typename automaton_t::set_t                       automata_set_t;
      typedef typename automaton_t::series_set_t                series_set_t;
      typedef typename automaton_t::series_set_elt_t    series_set_elt_t;
      typedef typename series_set_elt_t::semiring_elt_t semiring_elt_t;
      typedef Monoid_                                   monoid_elt_value_t;
      typedef Semiring_                                 semiring_elt_value_t;
      typedef rat::Node<monoid_elt_value_t, semiring_elt_value_t> node_t;

    public :

      ThompsonVisitor(const series_set_t& s) : series_(s)
      {}

      virtual
      ~ThompsonVisitor()
      {}

      virtual void
      product(const node_t* lhs, const node_t* rhs)
      {
        automaton_t     *tmp_;
        rhs->accept(*this);
        tmp_ = auto_;
        lhs->accept(*this);
        concatenate_of_normalized_here(*auto_, *tmp_);
        delete(tmp_);
      }

      virtual void
      sum(const node_t* lhs, const node_t* rhs)
      {
        automaton_t     *tmp_;
        lhs->accept(*this);
        tmp_ = auto_;
        rhs->accept(*this);
        union_of_normalized_here(*auto_, *tmp_);
      }

      virtual void
      star(const node_t* node)
      {
        node->accept(*this);
        star_of_normalized_here(*auto_);
      }

      virtual void
      left_weight(const semiring_elt_value_t& w, const node_t* node)
      {
        node->accept(*this);

        for (typename automaton_t::initial_iterator i = auto_->initial().begin();
             i != auto_->initial().end();
             ++i)
          auto_->set_initial(*i, semiring_elt_t(w) * auto_->get_initial(*i));
      }

      virtual void
      right_weight(const semiring_elt_value_t& w, const node_t* node)
      {
        node->accept(*this);

        for (typename automaton_t::initial_iterator i = auto_->initial().begin();
             i != auto_->initial().end();
             ++i)
          auto_->set_initial(*i, auto_->get_initial(*i) * semiring_elt_t(w));
      }

      virtual void
      constant(const monoid_elt_value_t& m)
      {
        auto_ = new automaton_t(automata_set_t(series_));
        hstate_t new_i = auto_->add_state();
        hstate_t last = new_i;
        hstate_t new_f;
        for (typename monoid_elt_value_t::const_iterator i = m.begin();
             i != m.end(); ++i)
        {
          new_f = auto_->add_state();
          auto_->add_letter_transition(last, new_f, *i);
          last = new_f;
        }
        auto_->set_initial(new_i);
        auto_->set_final(new_f);
      }

      virtual void
      zero()
      {
        auto_ = new automaton_t(automata_set_t(series_));
      }

      virtual void
      one()
      {
        auto_ = new automaton_t(automata_set_t(series_));
        hstate_t new_i = auto_->add_state();
        hstate_t new_f = auto_->add_state();
        auto_->set_initial(new_i);
        auto_->set_final(new_f);
        auto_->add_spontaneous(new_i, new_f);
      }

      const automaton_t         &get_auto() const
      {
        return *auto_;
      }

    private :
      automaton_t               *auto_;
      const series_set_t        &series_;
  };

  template <typename A, typename auto_t,
            typename Letter, typename Weight>
  void
  do_thompson_of(const AutomataBase<A>&,
                 auto_t& output,
                 const rat::exp<Letter, Weight>& kexp)
  {
    ThompsonVisitor<auto_t, Letter, Weight> visitor(output.structure().series());

    // FIXME :
    // Static assert : Letter = monoid_elt_value_t,
    //                 Weight = semiring_elt_value_t
    kexp.accept(visitor);
    output = visitor.get_auto();
  }

  template<typename A,      typename T,
           typename Letter, typename Weight>
  void
  thompson_of(Element<A, T>& out,
              const rat::exp<Letter, Weight>& kexp)
  {
    do_thompson_of(out.structure(), out, kexp);
  }

  template <class AutoType, class S, class T>
  Element<Automata<S>, AutoType>
  thompson_of(const Element<S, T>& exp)
  {
    Automata<S>                         automata_set(exp.structure());
    Element<Automata<S>, AutoType>      automata(automata_set);

    thompson_of(automata, exp.value());
    return automata;
  }
} // vcsn

#endif // ! VCSN_ALGORITHMS_THOMPSON_HXX

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