initial_derivation.hxx

// initial_derivation.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_INITIAL_DERIVATION_HXX
# define VCSN_ALGORITHMS_INITIAL_DERIVATION_HXX

# include <vaucanson/algebra/concept/series_base.hh>
# include <vaucanson/algebra/implementation/series/krat_exp_pattern.hh>

# include <list>

namespace vcsn
{

  template <class Series, class T, class Dispatch>
  struct KRatExpInitialDerivation : algebra::KRatExpMatcher<
    KRatExpInitialDerivation<Series, T, Dispatch>,
    T,
    std::list< Element<Series, T> >,
    Dispatch
    >
  {
    typedef KRatExpInitialDerivation<Series, T, Dispatch>       self_t;
    typedef Element<Series, T>                          exp_t;
    typedef std::list<exp_t>                            list_t;
    typedef std::list<exp_t>                            return_type;
    typedef typename list_t::iterator                   iterator_t;
    IMPORT_TYPEDEF_(exp_t,                              semiring_elt_t);
    IMPORT_TYPEDEF_(exp_t,                              monoid_elt_t);
    typedef typename semiring_elt_t::value_t            semiring_elt_value_t;
    INHERIT_CONSTRUCTORS(self_t, T, semiring_elt_t, Dispatch);

    KRatExpInitialDerivation(const exp_t& exp) :
      exp_(exp)
    {}

    // Useful functions:
  private:
    list_t apply_sum(list_t explist)
    {
      if (explist.size() != 1)
      {
        iterator_t      i = explist.begin();
        exp_t           res = *i;
        for (i++; i != explist.end(); ++i)
        {
          res += *i;
        }
        explist.clear();
        explist.push_back(res);
      }
      return explist;
    }

    list_t& put_in(list_t& s, exp_t e)
    {
      s.clear();
      s.push_back(e);
      return s;
    }

   public:

    // Matches:
    MATCH__(Product, lhs, rhs)
    {
      list_t llist = match(lhs);
      exp_t s (exp_.structure(), rhs);
      list_t res;
      for (typename list_t::const_iterator it = llist.begin();
           it != llist.end(); ++it)
        res.push_back(*it * s);
      return res;
    }
    END

    MATCH__(Sum, lhs, rhs)
    {
      list_t llist = match(lhs);
      list_t rlist = match(rhs);
      list_t res;
      merge(llist.begin(), llist.end(),
                rlist.begin(), rlist.end(),
                inserter(res, res.begin()));
      return res;
    }
    END

    MATCH_(Star, e)
    {
      list_t    res;
      exp_t s (exp_.structure(), e.star());
      res.push_back(s);
      return res;
    }
    END

    MATCH__(LeftWeight, w, e)
    {
      list_t    clist = apply_sum(match(e));
      put_in(clist, semiring_elt_t(w) * *clist.begin());
      return clist;
    }
    END

    MATCH__(RightWeight, e, w)
    {
      list_t    clist = apply_sum(match(e));
      put_in(clist, *clist.begin() * semiring_elt_t(w));
      return clist;
    }
    END

    MATCH_(Constant, m)
    {
      list_t    res;
      exp_t s (exp_.structure(), m);
      res.push_back(s);
      return res;
    }
    END

    MATCH(Zero)
    {
      list_t    res;
      res.push_back(exp_.structure().zero(SELECT(T)));
      return res;
    }
    END

    MATCH(One)
    {
      list_t    res;
      res.push_back(exp_.structure().identity(SELECT(T)));
      return res;
    }
    END

  private:
    exp_t exp_;
  };

}

#endif // ! VCSN_ALGORITHMS_INITIAL_DERIVATION_HXX

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