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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

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