// Copyright (C) 2004, 2005  Laboratoire d'Informatique de Paris 6 (LIP6),
// département Systèmes Répartis Coopératifs (SRC), Université Pierre
// et Marie Curie.
//
// This file is part of Spot, a model checking library.
//
// Spot 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.
//
// Spot 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 Spot; see the file COPYING.  If not, write to the Free
// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
// 02111-1307, USA.

#ifndef SPOT_TGBAALGOS_SE05_HH
# define SPOT_TGBAALGOS_SE05_HH

#include <cstddef>
#include "misc/optionmap.hh"

namespace spot
{
  class tgba;
  class emptiness_check;

  /// \addtogroup emptiness_check_algorithms
  /// @{

  /// \brief Returns an emptiness check on the spot::tgba automaton \a a.
  ///
  /// \pre The automaton \a a must have at most one acceptance condition (i.e.
  /// it is a TBA).
  ///
  /// During the visit of \a a, the returned checker stores explicitely all
  /// the traversed states.
  /// The method \a check() of the checker can be called several times
  /// (until it returns a null pointer) to enumerate all the visited accepting
  /// paths. The implemented algorithm is an optimization of
  /// spot::explicit_magic_search and is the following:
  ///
  /// \verbatim
  /// procedure check ()
  /// begin
  ///   call dfs_blue(s0);
  /// end;
  ///
  /// procedure dfs_blue (s)
  /// begin
  ///   s.color = cyan;
  ///   for all t in post(s) do
  ///     if t.color == white then
  ///       call dfs_blue(t);
  ///     else if t.color == cyan and
  ///             (the edge (s,t) is accepting or
  ///              (it exists a predecessor p of s in st_blue and s != t and
  ///              the arc between p and s is accepting)) then
  ///       report cycle;
  ///     end if;
  ///     if the edge (s,t) is accepting then
  ///       call dfs_red(t);
  ///     end if;
  ///   end for;
  ///   s.color = blue;
  /// end;
  ///
  /// procedure dfs_red(s)
  /// begin
  ///   if s.color == cyan then
  ///     report cycle;
  ///   end if;
  ///   s.color = red;
  ///   for all t in post(s) do
  ///     if t.color == blue then
  ///       call dfs_red(t);
  ///     end if;
  ///   end for;
  /// end;
  /// \endverbatim
  ///
  /// It is an adaptation to TBA of the one presented in
  /// \verbatim
  ///  @techreport{SE04,
  ///    author = {Stefan Schwoon and Javier Esparza},
  ///    institution = {Universit{\"a}t Stuttgart, Fakult\"at Informatik,
  ///    Elektrotechnik und Informationstechnik},
  ///    month = {November},
  ///    number = {2004/06},
  ///    title = {A Note on On-The-Fly Verification Algorithms},
  ///    year = {2004},
  ///    url =
  ///{http://www.fmi.uni-stuttgart.de/szs/publications/info/schwoosn.SE04.shtml}
  ///  }
  /// \endverbatim
  ///
  /// \sa spot::explicit_magic_search
  ///
  emptiness_check* explicit_se05_search(const tgba *a,
                                        option_map o = option_map());
  /// \brief Returns an emptiness checker on the spot::tgba automaton \a a.
  ///
  /// \pre The automaton \a a must have at most one acceptance condition (i.e.
  /// it is a TBA).
  ///
  /// During the visit of \a a, the returned checker does not store explicitely
  /// the traversed states but uses the bit-state hashing technic presented in:
  ///
  /// \verbatim
  /// @book{Holzmann91,
  ///    author = {G.J. Holzmann},
  ///    title = {Design and Validation of Computer Protocols},
  ///    publisher = {Prentice-Hall},
  ///    address = {Englewood Cliffs, New Jersey},
  ///    year = {1991}
  /// }
  /// \endverbatim
  ///
  /// Consequently, the detection of an acceptence cycle is not ensured.
  ///
  /// The size of the heap is limited to \n size bytes.
  ///
  /// The implemented algorithm is the same as the one of
  /// spot::explicit_se05_search.
  ///
  /// \sa spot::explicit_se05_search
  ///
  emptiness_check* bit_state_hashing_se05_search(const tgba *a, size_t size,
						 option_map o = option_map());


  /// \brief Wrapper for the two se05 implementations.
  ///
  /// This wrapper calls explicit_se05_search() or
  /// bit_state_hashing_se05_search() according to the \c "bsh" option
  /// in the \c option_map.  If \c "bsh" is set and non null, its value
  /// is used as the size of the hash map.
  emptiness_check* se05(const tgba *a, option_map o);

  /// @}
}

#endif // SPOT_TGBAALGOS_SE05_HH