saturate.hh

// Copyright (C) 2007, 2009 EPITA Research and Development Laboratory (LRDE)
//
// This file is part of Olena.
//
// Olena 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, version 2 of the License.
//
// Olena is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Olena.  If not, see <http://www.gnu.org/licenses/>.
//
// As a special exception, you may use this file as part of a free
// software project without restriction.  Specifically, if other files
// instantiate templates or use macros or inline functions from this
// file, or you compile this file and link it with other files to produce
// an executable, this file does not by itself cause the resulting
// executable to be covered by the GNU General Public License.  This
// exception does not however invalidate any other reasons why the
// executable file might be covered by the GNU General Public License.

#ifndef MLN_FUN_V2V_SATURATE_HH
# define MLN_FUN_V2V_SATURATE_HH

# include <mln/core/concept/function.hh>
# include <mln/metal/converts_to.hh>
# include <mln/trait/value_.hh>
# include <mln/value/cast.hh>


namespace mln
{

  namespace fun
  {

    namespace v2v
    {

      // FIXME: Doc!

      template <typename V>
      struct saturate : public Function_v2v< saturate<V> >
      {
        saturate();
        saturate(const V& min, const V& max);

        typedef V result;

        template <typename W>
        V operator()(const W& w) const;

      protected:
        V min_, max_;
        mutable bool needs_update_;
      };


# ifndef MLN_INCLUDE_ONLY

      template <typename V>
      inline
      saturate<V>::saturate()
        : min_(mln_min(V)),
          max_(mln_max(V))
      {
        needs_update_ = true;
      }

      template <typename V>
      inline
      saturate<V>::saturate(const V& min, const V& max)
        : min_(min),
          max_(max)
      {
        mln_precondition(max > min);
        needs_update_ = true;
      }

      template <typename V>
      template <typename W>
      inline
      V
      saturate<V>::operator()(const W& w) const
      {
        // FIXME: Check that W is a larger type than V; otherwise
        // alt code.

        static W min_W, max_W;
        if (needs_update_)
          {
            min_W = mln::value::cast<W>(min_);
            max_W = mln::value::cast<W>(max_);
            needs_update_ = false;
          }

        // FIXME: Below we need something more powerful that mlc_converts_to
        // for instance, with W=int_s<10u> and V=int_u<8u>, it does not
        // works cause the cast is not obvious...
        // mlc_converts_to(W, V)::check();

        if (w < min_W)
          return min_;
        if (w > max_W)
          return max_;
        return mln::value::cast<W>(w);
      }

# endif // ! MLN_INCLUDE_ONLY

    } // end of namespace mln::fun::v2v

  } // end of namespace mln::fun

} // end of namespace mln


#endif // ! MLN_FUN_V2V_SATURATE_HH