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# shuffle.hxx

    00001 // shuffle.hxx: this file is part of the Vaucanson project.
    00002 //
    00003 // Vaucanson, a generic library for finite state machines.
    00004 //
    00005 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2011 The Vaucanson Group.
    00006 //
    00007 // This program is free software; you can redistribute it and/or
    00008 // modify it under the terms of the GNU General Public License
    00009 // as published by the Free Software Foundation; either version 2
    00010 // of the License, or (at your option) any later version.
    00011 //
    00012 // The complete GNU General Public Licence Notice can be found as the
    00013 // `COPYING' file in the root directory.
    00014 //
    00015 // The Vaucanson Group consists of people listed in the `AUTHORS' file.
    00016 //
    00017 #ifndef VCSN_ALGORITHMS_SHUFFLE_HXX
    00018 # define VCSN_ALGORITHMS_SHUFFLE_HXX
    00019
    00020 # include <set>
    00021 # include <map>
    00022 # include <queue>
    00023 # include <stack>
    00024
    00025 # include <vaucanson/algorithms/shuffle.hh>
    00026
    00027 # ifndef VCSN_NDEBUG
    00028 #  include <vaucanson/algorithms/realtime.hh>
    00029 # endif // ! VCSN_NDEBUG
    00030
    00031 # include <vaucanson/automata/concept/automata_base.hh>
    00032 # include <vaucanson/misc/usual_macros.hh>
    00033 # include <vaucanson/automata/implementation/geometry.hh>
    00034 # include <vaucanson/misc/static.hh>
    00035
    00036 namespace vcsn
    00037 {
    00038
    00039 /*--------------------------------.
    00040 | Functor for shuffle algorithm.  |
    00041 `--------------------------------*/
    00042 template<typename A, typename T, typename U>
    00043 class Shuffle
    00044 {
    00045   public:
    00046     typedef AutomataBase<A> structure_t;
    00047     typedef Element<A, T> lhs_t;
    00048     typedef Element<A, U> rhs_t;
    00049     typedef lhs_t           output_t;
    00050     typedef std::map<typename output_t::hstate_t,
    00051               std::pair<typename lhs_t::hstate_t, typename rhs_t::hstate_t> >
    00052                           pair_map_t;
    00053
    00054     Shuffle (const structure_t& structure,
    00055              const bool use_geometry)
    00056       : use_geometry_(use_geometry),
    00057         series_(structure.series()),
    00058         monoid_(series_.monoid()),
    00059         semiring_zero_(series_.semiring().zero(SELECT(semiring_elt_value_t)))
    00060     {
    00061     }
    00062
    00063     // returns the shuffle of @c lhs and @c rhs (and put it also in @c output)
    00064     output_t&
    00065     operator() (output_t& output,
    00066                 const lhs_t& lhs,
    00067                 const rhs_t& rhs,
    00068                 pair_map_t& m)
    00069     {
    00070       BENCH_TASK_SCOPED("shuffle");
    00071       visited_.clear();
    00072
    00073       precondition(is_realtime(lhs));
    00074       precondition(is_realtime(rhs));
    00075
    00076       this->initialize_queue(output, lhs, rhs, m);
    00077
    00078       while (not to_process_.empty())
    00079       {
    00080         const pair_hstate_t current_pair = to_process_.front();
    00081         to_process_.pop();
    00082
    00083         const hstate_t lhs_s         = current_pair.first;
    00084         const hstate_t rhs_s         = current_pair.second;
    00085         const hstate_t current_state = visited_[current_pair];
    00086
    00087         output.set_initial(current_state,
    00088                            lhs.get_initial(lhs_s) * rhs.get_initial(rhs_s));
    00089         output.set_final(current_state,
    00090                          lhs.get_final(lhs_s) * rhs.get_final(rhs_s));
    00091
    00092         for (typename lhs_t::delta_iterator l(lhs.value(), lhs_s);
    00093              ! l.done();
    00094              l.next())
    00095         {
    00096               const pair_hstate_t new_pair(lhs.dst_of(*l), rhs_s);
    00097               typename visited_t::const_iterator found = visited_.find(new_pair);
    00098
    00099               hstate_t dst;
    00100               if (found == visited_.end())
    00101               {
    00102                 dst = output.add_state();
    00103
    00104                 this->add_state_to_process(output, lhs, rhs, m, dst, new_pair);
    00105               }
    00106               else
    00107                 dst = found->second;
    00108               output.add_series_transition(current_state, dst, lhs.series_of(*l));
    00109         }
    00110         for (typename rhs_t::delta_iterator r(rhs.value(), rhs_s);
    00111              ! r.done();
    00112              r.next())
    00113         {
    00114               const pair_hstate_t new_pair(lhs_s, rhs.dst_of(*r));
    00115               typename visited_t::const_iterator found = visited_.find(new_pair);
    00116
    00117               hstate_t dst;
    00118               if (found == visited_.end())
    00119               {
    00120                 dst = output.add_state();
    00121
    00122                 this->add_state_to_process(output, lhs, rhs, m, dst, new_pair);
    00123               }
    00124               else
    00125                 dst = found->second;
    00126               output.add_series_transition(current_state, dst, rhs.series_of(*r));
    00127         }
    00128
    00129
    00130
    00131       }
    00132       merge_transitions(output);
    00133       return output;
    00134     }
    00135
    00136   private:
    00137       //merge transitions with the same ends
    00138     void merge_transitions(output_t& a)
    00139     {
    00140       typedef std::map<hstate_t, series_set_elt_t> map_t;
    00141       for_all_states(s, a)
    00142         {
    00143           map_t map;
    00144           std::list<htransition_t> transitions;
    00145           for (delta_iterator e(a.value(), *s); ! e.done(); e.next())
    00146             {
    00147               hstate_t target = a.dst_of(*e);
    00148               transitions.push_back(*e);
    00149               typename map_t::iterator it = map.find(target);
    00150               if (it == map.end())
    00151                 map.insert(std::pair<hstate_t, series_set_elt_t>(target,
    00152                                                                  a.series_of(*e)));
    00153               else
    00154                 it->second += a.series_of(*e);
    00155             }
    00156           for_all_(std::list<htransition_t>, e, transitions)
    00157             a.del_transition(*e);
    00158           for_all_(map_t, it, map)
    00159             a.add_series_transition(*s, it->first, it->second);
    00160         }
    00161     }
    00162
    00163     // Some little graphic tools
    00164     class grphx
    00165     {
    00166       public:
    00167         template <typename Output, typename Lhs, typename Rhs>
    00168         static void
    00169         setcoordfrom (Output& a,
    00170                       const Lhs& lhs,
    00171                       const Rhs& rhs,
    00172                       const typename Output::hstate_t state,
    00173                       const typename Lhs::hstate_t x_state,
    00174                       const typename Rhs::hstate_t y_state)
    00175         {
    00176           typename std::map<typename Lhs::hstate_t,
    00177             typename Lhs::geometry_t::coords_t>::const_iterator iter;
    00178           typename std::map<typename Rhs::hstate_t,
    00179             typename Rhs::geometry_t::coords_t>::const_iterator iter2;
    00180           double x = 0, y = 0;
    00181
    00182           iter = lhs.geometry().states().find(x_state);
    00183           if (iter != lhs.geometry().states().end())
    00184             x = iter->second.first;
    00185
    00186           iter2 = rhs.geometry().states().find(y_state);
    00187           if (iter2 != rhs.geometry().states().end())
    00188             y = iter2->second.second;
    00189
    00190           a.geometry().states()[state] = std::make_pair(x, y);
    00191         }
    00192       private:
    00193         // Diagonal alignement with a depth-first traversal
    00194         template<typename I>
    00195         void
    00196         align (const I& a)
    00197         {
    00198           AUTOMATON_TYPES(I);
    00199           std::map<hstate_t,bool> visited;
    00200           std::stack<hstate_t> stack;
    00201
    00202           for_all_const_states(i, a)
    00203             {
    00204               visited[*i] = false;
    00205               // ensure inaccessible states will be visited
    00206               stack.push(*i);
    00207             }
    00208
    00209           for_all_const_initial_states(i, a)
    00210             stack.push(*i);
    00211
    00212           int x = 0;
    00213           while (!stack.empty())
    00214           {
    00215             hstate_t i = stack.top();
    00216             stack.pop();
    00217
    00218             if (!visited[i])
    00219             {
    00220               visited[i] = true;
    00221
    00222               a.geometry()[i] = std::make_pair(x, x);
    00223               x++;
    00224
    00225               for (delta_iterator j(a.value(), i);
    00226                    ! j.done();
    00227                    j.next())
    00228                 stack.push(a.dst_of(*j));
    00229             }
    00230           }
    00231         }
    00232
    00233     };
    00234     class no_grphx
    00235     {
    00236       public:
    00237         template <typename Output, typename Lhs, typename Rhs>
    00238         static void
    00239         setcoordfrom (Output& a,
    00240                       const Lhs& lhs,
    00241                       const Rhs& rhs,
    00242                       const typename Output::hstate_t state,
    00243                       const typename Lhs::hstate_t x_state,
    00244                       const typename Rhs::hstate_t y_state) {};
    00245     };
    00246
    00247     // useful typedefs
    00248     AUTOMATON_TYPES(output_t);
    00249
    00250     typedef std::pair<typename lhs_t::hstate_t, typename rhs_t::hstate_t>
    00251                                                       pair_hstate_t;
    00252     typedef std::list<htransition_t>                    delta_ret_t;
    00253     typedef std::map<pair_hstate_t, hstate_t>           visited_t;
    00254     typedef typename series_set_elt_t::support_t        support_t;
    00255
    00256     // add a @c new_state in the queue
    00257     inline void
    00258     add_state_to_process (output_t& output,
    00259                           const lhs_t& lhs,
    00260                           const rhs_t& rhs,
    00261                           pair_map_t& m,
    00262                           const hstate_t& new_state,
    00263                           const pair_hstate_t& new_pair)
    00264     {
    00265       m[new_state] = new_pair;
    00266       visited_[new_pair] = new_state;
    00267       to_process_.push(new_pair);
    00268
    00269 # define if_(Cond, ThenClause, ElseClause)                      \
    00270 misc::static_if_simple<Cond, ThenClause, ElseClause>::t
    00271 # define eq_(Type1, Type2)                      \
    00272 misc::static_eq<Type1, Type2>::value
    00273 # define DECLARE_GEOMETRY(Type) \
    00274   typedef geometry<typename Type::hstate_t, typename Type::htransition_t, typename Type::geometry_coords_t> geometry_ ## Type ;
    00275
    00276       DECLARE_GEOMETRY(output_t)
    00277       DECLARE_GEOMETRY(lhs_t)
    00278       DECLARE_GEOMETRY(rhs_t)
    00279       if (use_geometry_)
    00280         if_(eq_(typename output_t::geometry_t, geometry_output_t)  and \
    00281             eq_(typename rhs_t::geometry_t, geometry_rhs_t) and \
    00282             eq_(typename lhs_t::geometry_t, geometry_lhs_t),    \
    00283             grphx, no_grphx)
    00284           ::setcoordfrom(output, lhs, rhs,
    00285                          new_state, new_pair.first, new_pair.second);
    00286 # undef if_
    00287 # undef eq_
    00288     }
    00289
    00290     // initialize queue with all pairs of intials states from @c lhs and @c rhs
    00291     inline void
    00292     initialize_queue (output_t& output,
    00293                       const lhs_t& lhs,
    00294                       const rhs_t& rhs,
    00295                       pair_map_t& m)
    00296     {
    00297       for_all_const_initial_states(lhs_s, lhs)
    00298         for_all_const_initial_states(rhs_s, rhs)
    00299         {
    00300           const pair_hstate_t   new_pair(*lhs_s, *rhs_s);
    00301           const hstate_t        new_state = output.add_state();
    00302
    00303           this->add_state_to_process(output, lhs, rhs, m, new_state, new_pair);
    00304         }
    00305     }
    00306
    00307     inline bool
    00308     is_shuffle_not_null (const lhs_t& lhs,
    00309                          const rhs_t& rhs,
    00310                          const typename lhs_t::delta_iterator& l,
    00311                          const typename rhs_t::delta_iterator& r,
    00312                          series_set_elt_t&  prod_series) const
    00313     {
    00314       const series_set_elt_t    left_series  = lhs.series_of(*l);
    00315       const series_set_elt_t    right_series = rhs.series_of(*r);
    00316
    00317       bool                      prod_is_not_null = false;
    00318       for_all_(support_t, supp, left_series.supp())
    00319         {
    00320           const monoid_elt_t     supp_elt (monoid_, *supp);
    00321           const semiring_elt_t l = left_series.get(supp_elt);
    00322           const semiring_elt_t r = right_series.get(supp_elt);
    00323           const semiring_elt_t p = l * r;
    00324           if (p != semiring_zero_)
    00325           {
    00326             prod_series.assoc(*supp, p.value());
    00327             prod_is_not_null = true;
    00328           }
    00329         }
    00330       return (prod_is_not_null);
    00331     }
    00332
    00333     // If set to true, <geometry> tags of the result automaton should be filled
    00334     const bool  use_geometry_;
    00335
    00336     // keep traces of new states created
    00337     visited_t                   visited_;
    00338     // @c to_process_ stores all states of output that needs are not
    00339     std::queue<pair_hstate_t>   to_process_;
    00340
    00341     // frequently used objects in computation
    00342     const series_set_t& series_;
    00343     const monoid_t&             monoid_;
    00344     // This variable's type must not be set to a reference.
    00345     const semiring_elt_t        semiring_zero_;
    00346 };
    00347
    00348 /*-----------.
    00349 | Wrappers.  |
    00350 `-----------*/
    00351
    00352 template<typename A, typename T, typename U>
    00353 Element<A, T>
    00354 shuffle (const Element<A, T>& lhs, const Element<A, U>& rhs,
    00355          std::map<typename T::hstate_t,
    00356          std::pair<typename T::hstate_t, typename U::hstate_t> >& m,
    00357          const bool use_geometry)
    00358 {
    00359   Element<A, T> ret(rhs.structure());
    00360   Shuffle<A, T, U> do_shuffle(ret.structure(), use_geometry);
    00361   return do_shuffle (ret, lhs, rhs, m);
    00362 }
    00363
    00364 template<typename A, typename T, typename U>
    00365 Element<A, T>
    00366 shuffle (const Element<A, T>& lhs, const Element<A, U>& rhs,
    00367          const bool use_geometry)
    00368 {
    00369   std::map<typename T::hstate_t,
    00370     std::pair<typename T::hstate_t, typename U::hstate_t> > m;
    00371   return shuffle (lhs, rhs, m, use_geometry);
    00372 }
    00373
    00374 } // End of namespace vcsn.
    00375
    00376 #endif // ! VCSN_ALGORITHMS_SHUFFLE_HXX