- Main Page
- Related Pages
- Modules
- Namespaces
- Classes
- Files

- File List
- File Members

# eval.hxx

    00001 // eval.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, 2008 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_EVAL_HXX
    00018 # define VCSN_ALGORITHMS_EVAL_HXX
    00019
    00020 # include <vaucanson/algorithms/eval.hh>
    00021 # include <vaucanson/automata/concept/automata_base.hh>
    00022 # include <vaucanson/misc/selectors.hh>
    00023 # include <vaucanson/misc/usual_macros.hh>
    00024 # include <algorithm>
    00025 # include <vector>
    00026
    00027 namespace vcsn {
    00028
    00029   /*-----.
    00030   | Eval |
    00031   `-----*/
    00032
    00033   // precondition : the automaton is realtime
    00034   template <typename auto_t, typename input_t, typename Selt>
    00035   struct eval_functor
    00036   {
    00037       AUTOMATON_TYPES(auto_t);
    00038
    00039       typedef std::vector<semiring_elt_t> weights;
    00040
    00041       const auto_t& a;
    00042       int max_hstate;
    00043
    00044       weights v1, v2;
    00045
    00046       typename weights::const_iterator w;
    00047       typename input_t::const_iterator l;
    00048
    00049       template <typename A>
    00050       eval_functor(const AutomataBase<A>&, const auto_t& aut)
    00051         : a(aut), max_hstate(a.states().back() + 1),
    00052           v1(max_hstate, a.series().semiring().wzero_), v2(max_hstate)
    00053       {}
    00054
    00055       void execute(const input_t& word, Selt& result)
    00056       {
    00057         const monoid_elt_t empty = algebra::identity_as<monoid_elt_value_t>::of(a.series().monoid());
    00058
    00059         // Initialize
    00060         for_all_const_initial_states(i, a)
    00061           v1[*i] = a.get_initial(*i).get(empty);
    00062
    00063         const semiring_elt_t zero = a.series().semiring().wzero_;
    00064
    00065         // Computation
    00066         l = word.begin();
    00067         for (typename input_t::const_iterator w_end = word.end();
    00068              l != w_end; ++l)
    00069         {
    00070           std::fill(v2.begin(), v2.end(), zero);
    00071           int i = 0;
    00072           w = v1.begin();
    00073           for (typename weights::const_iterator v1_end = v1.end();
    00074                w != v1_end; ++w)
    00075           {
    00076             if (*w != zero)
    00077             {
    00078               for (delta_iterator t(a.value(), a.get_state(i)); ! t.done(); t.next())
    00079               {
    00080                 monoid_elt_t l_w(a.series_of(*t).structure().monoid(), *l);
    00081                 if (a.series_of(*t).get(l_w) != a.series().semiring().wzero_)
    00082                 {
    00083                   v2[a.dst_of(*t)] += *w *
    00084                     a.series_of(*t).get(monoid_elt_t(a.structure().series().monoid(), *l));
    00085                 }
    00086               }
    00087             }
    00088             ++i;
    00089           }
    00090           std::swap(v1, v2);
    00091         }
    00092
    00093         // Result
    00094         result = zero;
    00095         int i = 0;
    00096         for_all_const_ (weights, w, v1)
    00097         {
    00098           if (*w != zero)
    00099             result += *w * a.get_final(i).get(empty);
    00100           ++i;
    00101         }
    00102       }
    00103   };
    00104
    00105   /*----------.
    00106   | Wrapper.  |
    00107   `----------*/
    00108
    00109   template<typename A, typename AI, typename W>
    00110   typename Element<A, AI>::semiring_elt_t
    00111   eval(const Element<A, AI>& a, const W& word)
    00112   {
    00113     BENCH_TASK_SCOPED("eval");
    00114     typedef Element<A, AI> automaton_t;
    00115     AUTOMATON_TYPES(automaton_t);
    00116     semiring_elt_t ret(a.structure().series().semiring());
    00117
    00118     // Check if the automaton is empty.
    00119     if (!is_empty(a))
    00120     {
    00121       eval_functor<automaton_t, W, semiring_elt_t> evalf(a.structure(), a);
    00122       evalf.execute(word, ret);
    00123     }
    00124
    00125     return ret;
    00126   }
    00127
    00128 } // ! vcsn
    00129
    00130 #endif // ! VCSN_ALGORITHMS_EVAL_HXX