normalized_composition.hxx

Go to the documentation of this file.

// normalized_composition.hxx: this file is part of the Vaucanson project.
//
// Vaucanson, a generic library for finite state machines.
//
// Copyright (C) 2005, 2006 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_NORMALIZED_COMPOSITION_HXX
# define VCSN_ALGORITHMS_NORMALIZED_COMPOSITION_HXX

# include <set>
# include <queue>
# include <vaucanson/algorithms/normalized_composition.hh>
# include <vaucanson/algorithms/internal/outsplitting.hh>
# include <vaucanson/algebra/concept/freemonoid_product.hh>
# include <vaucanson/algebra/implementation/series/series.hh>
# include <vaucanson/automata/concept/automata.hh>


namespace vcsn {

  template <typename S, typename M1, typename M2, typename lhs_t,
            typename rhs_t, typename res_t>
  struct composer
  {
    typedef std::pair<hstate_t, hstate_t>       pair_hstate_t;
    typedef std::map<pair_hstate_t, hstate_t>   visited_t;
    typedef std::map<hstate_t, pair_hstate_t >  map_of_states_t;
    typedef std::queue<pair_hstate_t>           to_process_t;

    AUTOMATON_TYPES(res_t);
    AUTOMATON_TYPES_(lhs_t, lhs_);
    AUTOMATON_TYPES_(rhs_t, rhs_);

    typedef std::set<htransition_t>                     delta_ret_t;
    typedef typename series_set_elt_t::support_t        support_t;
    typedef typename lhs_series_set_elt_t::support_t    lhs_support_t;
    typedef typename rhs_series_set_elt_t::support_t    rhs_support_t;

    typedef typename lhs_monoid_t::first_monoid_t
    lhs_first_monoid_t;
    typedef typename lhs_monoid_elt_value_t::first_type
    lhs_first_monoid_elt_value_t;
    typedef Element<lhs_first_monoid_t, lhs_first_monoid_elt_value_t>
    lhs_first_monoid_elt_t;

    typedef typename rhs_monoid_t::first_monoid_t
    rhs_first_monoid_t;
    typedef typename rhs_monoid_elt_value_t::first_type
    rhs_first_monoid_elt_value_t;
    typedef Element<rhs_first_monoid_t, rhs_first_monoid_elt_value_t>
    rhs_first_monoid_elt_t;

    typedef typename lhs_monoid_t::second_monoid_t
    lhs_second_monoid_t;
    typedef typename lhs_monoid_elt_value_t::second_type
    lhs_second_monoid_elt_value_t;
    typedef Element<lhs_second_monoid_t, lhs_second_monoid_elt_value_t>
    lhs_second_monoid_elt_t;

    typedef typename rhs_monoid_t::second_monoid_t
    rhs_second_monoid_t;
    typedef typename rhs_monoid_elt_value_t::second_type
    rhs_second_monoid_elt_value_t;
    typedef Element<rhs_second_monoid_t, rhs_second_monoid_elt_value_t>
    rhs_second_monoid_elt_t;

    visited_t visited;
    to_process_t to_process;
    map_of_states_t m;

    const lhs_t&                 lhs;
    const rhs_t&                 rhs;
    res_t&                       output;
    std::set<hstate_t>&          lhs_black_states;
    std::set<hstate_t>&          rhs_black_states;

    const series_set_t& series;
    const monoid_t&     monoid;

    const lhs_series_set_t&     lhs_series;
    const lhs_monoid_t&         lhs_monoid;

    const rhs_series_set_t&     rhs_series;
    const rhs_monoid_t&         rhs_monoid;

    lhs_first_monoid_elt_t lhs_first_identity;
    rhs_first_monoid_elt_t rhs_first_identity;
    lhs_second_monoid_elt_t lhs_second_identity;
    rhs_second_monoid_elt_t rhs_second_identity;

    composer (const AutomataBase<S>&,
              const algebra::FreeMonoidProduct<M1, M2>&,
              const lhs_t&                 aLhs,
              const rhs_t&                 aRhs,
              res_t&                       aOutput,
              std::set<hstate_t>&          aLhs_states,
              std::set<hstate_t>&          aRhs_states)
      : lhs (aLhs),
        rhs (aRhs),
        output (aOutput),
        lhs_black_states (aLhs_states),
        rhs_black_states (aRhs_states),

        series (output.structure().series()),
        monoid (series.monoid()),

        lhs_series (lhs.structure().series()),
        lhs_monoid (lhs_series.monoid()),

        rhs_series (rhs.structure().series()),
        rhs_monoid (rhs_series.monoid()),

        lhs_first_identity (algebra::identity_as<lhs_first_monoid_elt_value_t>::
                            of(lhs_monoid.first_monoid())),
        rhs_first_identity (algebra::identity_as<rhs_first_monoid_elt_value_t>::
                            of(rhs_monoid.first_monoid())),
        lhs_second_identity (algebra::identity_as<lhs_second_monoid_elt_value_t>::
                             of(lhs_monoid.second_monoid())),
        rhs_second_identity (algebra::identity_as<rhs_second_monoid_elt_value_t>::
                             of(rhs_monoid.second_monoid()))
    {
    }

    // - Add a transition between current_state and the state
    //   corresponding to the pair (from,to).
    // - If the state (from,to) does not exist, then it is created.
    // - The transition is labelled by prod_series.
    void
    add_transition(const hstate_t current_state,
                   const hstate_t from,
                   const hstate_t to,
                   typename res_t::series_set_elt_t& prod_series)
    {
      if (lhs_black_states.find(from) == lhs_black_states.end()
          or rhs_black_states.find(to) == rhs_black_states.end())
        {
          const pair_hstate_t new_pair (from, to);

          typename visited_t::const_iterator found =
            visited.find(new_pair);
          hstate_t dst;
          if (found == visited.end())
            {
              dst = output.add_state();
              visited[new_pair] = dst;
              m[dst] = new_pair;
              to_process.push(new_pair);
            }
          else
            dst = found->second;
          output.add_series_transition(current_state, dst, prod_series);
        }
    }

    typename res_t::series_set_elt_t
    series_product (typename monoid_elt_value_t::first_type l1,
                    typename monoid_elt_value_t::second_type l2,
                    semiring_elt_t w)
    {
      typename res_t::series_set_elt_t res (series);
      const monoid_elt_value_t word (l1, l2);
      res.assoc(word, w.value());
      return res;
    }


    // Compute the series for an initial or a final state, on the
    // empty word.
    typename res_t::series_set_elt_t
    state_series (lhs_series_set_elt_t l,
                  rhs_series_set_elt_t r)
    {
      series_set_elt_t res(series);
      res.assoc(monoid_elt_t(monoid,
                             algebra::identity_as<monoid_elt_value_t>::
                             of(monoid).value()),
                l.get(*l.supp().begin()) * r.get(*r.supp().begin()));
      return res;
    }

    void process_one_pair (const hstate_t current_state,
                           const hstate_t lhs_s, const hstate_t rhs_s)
    {

      if (lhs.is_initial(lhs_s) and rhs.is_initial(rhs_s))
        output.set_initial(current_state,
                           state_series (lhs.get_initial(lhs_s),
                                         rhs.get_initial(rhs_s)));

      if (lhs.is_final(lhs_s) and rhs.is_final(rhs_s))
        output.set_final(current_state,
                         state_series (lhs.get_final(lhs_s),
                                       rhs.get_final(rhs_s)));

      delta_ret_t transition_lhs;
      delta_ret_t transition_rhs;
      lhs.deltac(transition_lhs, lhs_s, delta_kind::transitions());
      rhs.deltac(transition_rhs, rhs_s, delta_kind::transitions());

      for_all_const_(delta_ret_t, l, transition_lhs)
        {
          const lhs_series_set_elt_t left_series = lhs.series_of(*l);
          const lhs_monoid_elt_t left_supp_elt (lhs_monoid,
                                                *left_series.supp().begin());

          // (i)
          // If the outgoing transition is of type (*, 1).
          if (left_supp_elt.value().second == lhs_second_identity.value())
            {
              series_set_elt_t s =
                series_product (left_supp_elt.value().first,
                                rhs_second_identity.value(),
                                left_series.get(left_supp_elt));
              add_transition (current_state,
                              lhs.dst_of(*l), rhs_s, s);
            }
          // (iii')
          else
            {
              for_all_const_(delta_ret_t, r, transition_rhs)
                {
                  const rhs_series_set_elt_t right_series =
                    rhs.series_of(*r);
                  const rhs_monoid_elt_t right_supp_elt
                    (rhs_monoid, *right_series.supp().begin());

                  // If the incoming transition is not of type (1, *).
                  if (right_supp_elt.value().first !=
                      rhs_first_identity.value())
                    //  we try to connect a transition of lhs and
                    // a transition of rhs.
                    if (left_supp_elt.value().second ==
                        right_supp_elt.value().first)
                      {
                        series_set_elt_t s =
                          series_product (left_supp_elt.value().first,
                                          right_supp_elt.value().second,
                                          left_series.get(left_supp_elt)
                                          * right_series.get(right_supp_elt));
                        add_transition
                          (current_state,
                           lhs.dst_of(*l), rhs.dst_of(*r),
                           s);
                      }
                }
            }
        }

      for_all_const_(delta_ret_t, r, transition_rhs)
        {
          const rhs_series_set_elt_t right_series = rhs.series_of(*r);
          const rhs_monoid_elt_t right_supp_elt (rhs_monoid,
                                                 *right_series.supp().begin());

          // (ii)
          if (right_supp_elt.value().first == rhs_first_identity.value())
            {
              series_set_elt_t s =
                series_product (lhs_first_identity.value(),
                                right_supp_elt.value().second,
                                right_series.get(right_supp_elt));
              add_transition (current_state,
                              lhs_s, rhs.dst_of(*r), s);
            }
        }

    }


    void operator() ()
    {

      /*----------------------------------.
      | Get initial states of the product |
      `----------------------------------*/
      for_all_initial_states(lhs_s, lhs)
        for_all_initial_states(rhs_s, rhs)
        {
          if (lhs_black_states.find(*lhs_s) == lhs_black_states.end() or
              rhs_black_states.find(*rhs_s) == rhs_black_states.end())
            {
              const hstate_t    new_state = output.add_state();
              const pair_hstate_t       new_pair (*lhs_s, *rhs_s);

              m[new_state] = new_pair;
              visited[new_pair] = new_state;
              to_process.push(new_pair);
            }
        }

      /*-----------.
      | Processing |
      `-----------*/
      while (not to_process.empty())
        {
          const pair_hstate_t p = to_process.front();
          to_process.pop();
          process_one_pair (visited[p], p.first, p.second);
        }
    }
  };



  template <typename S, typename M1, typename M2, typename lhs_t,
            typename rhs_t, typename res_t>
  void
  do_compose(const AutomataBase<S>&,
             const algebra::FreeMonoidProduct<M1, M2>&,
             const lhs_t& lhs,
             const rhs_t& rhs,
             res_t& ret)
  {
    AUTOMATON_TYPES(res_t);

    typedef std::set<hstate_t>                  set_of_states_t;
    set_of_states_t lhs_states;
    set_of_states_t rhs_states;

    composer<S, M1, M2, lhs_t, rhs_t, res_t>
      compose (ret.structure(), ret.structure().series().monoid(),
               lhs, rhs, ret, lhs_states, rhs_states);
    compose ();
  }

  template <typename S, typename M1, typename M2, typename lhs_t,
            typename rhs_t, typename res_t>
  void
  do_u_compose(const AutomataBase<S>&,
               const algebra::FreeMonoidProduct<M1, M2>&,
               const lhs_t& lhs,
               const rhs_t& rhs,
               res_t& ret)
  {
    AUTOMATON_TYPES(res_t);

    typedef std::set<hstate_t>                  set_of_states_t;
    set_of_states_t lhs_states;
    set_of_states_t rhs_states;

    lhs_t lhs_cov = splitting::outsplitting(lhs, lhs_states);
    rhs_t rhs_cov = splitting::insplitting(rhs, rhs_states);

    composer<S, M1, M2, lhs_t, rhs_t, res_t>
      compose (ret.structure(), ret.structure().series().monoid(),
               lhs_cov, rhs_cov, ret, lhs_states, rhs_states);
    compose ();

    eps_removal_here (ret);
    sub_automaton_here (ret, useful_states (ret));
  }



  // Compose dispatchers
  template <typename S, typename M1, typename M2, typename lhs_t,
            typename rhs_t, typename res_t>
  void
  do_compose_dispatcher(const AutomataBase<S>&,
                        const algebra::FreeMonoidProduct<M1, M2>&,
                        SELECTOR(bool),
                        const lhs_t& lhs,
                        const rhs_t& rhs,
                        res_t& ret)
  {
    do_compose (ret.structure(),
                ret.structure().series().monoid(),
                lhs, rhs, ret);
  }


  template <typename S, typename M1, typename M2, typename lhs_t,
            typename rhs_t, typename res_t, typename weight_t>
  void
  do_compose_dispatcher(const AutomataBase<S>&,
                        const algebra::FreeMonoidProduct<M1, M2>&,
                        const weight_t&,
                        const lhs_t& lhs,
                        const rhs_t& rhs,
                        res_t& ret)
  {
    do_u_compose (ret.structure(),
                  ret.structure().series().monoid(),
                  lhs, rhs, ret);
  }

  // Facade for compose

  template <typename S, typename T>
  void
  compose(const Element<S, T>& lhs,
          const Element<S, T>& rhs,
          Element<S, T>& ret)
  {
    typedef Element<S, T> auto_t;
    AUTOMATON_TYPES(auto_t);

    for_all_states (s, ret)
      ret.del_state (*s);

    do_compose_dispatcher (ret.structure(),
                           ret.structure().series().monoid(),
                           SELECT(semiring_elt_value_t),
                           lhs, rhs, ret);
  }



  template <typename S, typename T>
  Element<S, T>
  compose(const Element<S, T>& lhs,
          const Element<S, T>& rhs)
  {
    typedef Element<S, T> auto_t;
    AUTOMATON_TYPES(auto_t);

    typedef algebra::FreeMonoidProduct<
    typename auto_t::series_set_t::monoid_t::first_monoid_t,
      typename auto_t::series_set_t::monoid_t::second_monoid_t> res_monoid_t;

    typedef algebra::Series<typename auto_t::series_set_t::semiring_t,
      res_monoid_t>
      res_series_set_t;

    res_monoid_t monoid(lhs.structure().series().monoid().first_monoid(),
                        rhs.structure().series().monoid().second_monoid());


    res_series_set_t series(lhs.structure().series().semiring(), monoid);

    Automata<series_set_t> aut_set(series);

    Element< Automata<series_set_t>, T> ret(aut_set);
    do_compose_dispatcher(ret.structure(),
                          ret.structure().series().monoid(),
                          SELECT(semiring_elt_value_t),
                          lhs, rhs, ret);
    return ret;
  }


  // Facade for unambiguous composition
  template <typename S, typename T>
  void
  u_compose(const Element<S, T>& lhs,
            const Element<S, T>& rhs,
            Element<S, T>& ret)
  {
    typedef Element<S, T> auto_t;
    AUTOMATON_TYPES(auto_t);

    for_all_states (s, ret)
      ret.del_state (*s);

    do_u_compose (ret.structure(),
                  ret.structure().series().monoid(),
                  lhs, rhs, ret);
  }

  template <typename S, typename T>
  Element<S, T>
  u_compose(const Element<S, T>& lhs,
            const Element<S, T>& rhs)
  {
    typedef Element<S, T> auto_t;
    AUTOMATON_TYPES(auto_t);

    typedef algebra::FreeMonoidProduct<
    typename auto_t::series_set_t::monoid_t::first_monoid_t,
      typename auto_t::series_set_t::monoid_t::second_monoid_t> res_monoid_t;

    typedef algebra::Series<typename auto_t::series_set_t::semiring_t,
      res_monoid_t>
      res_series_set_t;

    res_monoid_t monoid(lhs.structure().series().monoid().first_monoid(),
                        rhs.structure().series().monoid().second_monoid());


    res_series_set_t series(lhs.structure().series().semiring(), monoid);

    Automata<series_set_t> aut_set(series);

    Element< Automata<series_set_t>, T> ret(aut_set);
    do_u_compose(ret.structure(),
                 ret.structure().series().monoid(),
                 lhs, rhs, ret);
    return ret;
  }

} // vcsn

#endif // ! VCSN_ALGORITHMS_NORMALIZED_COMPOSITION_HXX

---