spot/src/tgba/tgbatba.hh

// -*- coding: utf-8 -*-
// Copyright (C) 2010, 2011, 2012, 2013 Laboratoire de Recherche et
// Développement de l'Epita.
// Copyright (C) 2003, 2004, 2006 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 3 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 this program.  If not, see <http://www.gnu.org/licenses/>.

#ifndef SPOT_TGBA_TGBATBA_HH
# define SPOT_TGBA_TGBATBA_HH

#include <list>
#include "tgba.hh"
#include "misc/bddlt.hh"
#include "misc/hash.hh"

namespace spot
{

  /// \ingroup tgba_on_the_fly_algorithms
  /// \brief Degeneralize a spot::tgba on the fly, producing a TBA.
  ///
  /// This class acts as a proxy in front of a spot::tgba, that should
  /// be degeneralized on the fly.  The result is still a spot::tgba,
  /// but it will always have exactly one acceptance condition so
  /// it could be called TBA (without the G).
  ///
  /// The degeneralization is done by synchronizing the input
  /// automaton with a "counter" automaton such as the one shown in
  /// "On-the-fly Verification of Linear Temporal Logic" (Jean-Michel
  /// Couveur, FME99).
  ///
  /// If the input automaton uses N acceptance conditions, the output
  /// automaton can have at most max(N,1) times more states and
  /// transitions.
  ///
  /// \see tgba_sba_proxy
  class SPOT_API tgba_tba_proxy : public tgba
  {
  public:
    tgba_tba_proxy(const tgba* a);

    virtual ~tgba_tba_proxy();

    virtual state* get_init_state() const;

    virtual tgba_succ_iterator*
    succ_iter(const state* local_state,
	      const state* global_state = 0,
	      const tgba* global_automaton = 0) const;

    virtual bdd_dict* get_dict() const;

    virtual std::string format_state(const state* state) const;

    virtual state* project_state(const state* s, const tgba* t) const;

    virtual bdd all_acceptance_conditions() const;
    virtual bdd neg_acceptance_conditions() const;

    typedef std::list<bdd> cycle_list;


    /// \brief Return the acceptance conditions common to all outgoing
    /// transitions of state \a ostate in the original automaton.
    ///
    /// This internal function is only meant to be used to implement
    /// the iterator returned by succ_iter.
    ///
    /// The result of this function is computed the first time, and
    /// then cached.
    bdd common_acceptance_conditions_of_original_state(const state*
						       ostate) const;

    /// \brief Return the union of acceptance conditions of all outgoing
    /// transitions of state \a ostate in the original automaton.
    ///
    /// This internal function is only meant to be used to implement
    /// the iterator returned by succ_iter.
    ///
    /// The result of this function is computed the first time, and
    /// then cached.
    bdd union_acceptance_conditions_of_original_state(const state* s) const;

    /// \brief Create a degeneralized state using the unicity table.
    ///
    /// This is an internal function.  \a s should be a fresh state
    /// from the source automaton.
    state* create_state(state* s, cycle_list::const_iterator acc) const;

  protected:
    virtual bdd compute_support_conditions(const state* state) const;
    virtual bdd compute_support_variables(const state* state) const;

    cycle_list acc_cycle_;
    const tgba* a_;

  private:
    bdd the_acceptance_cond_;
    typedef Sgi::hash_map<const state*, bdd,
			  state_ptr_hash, state_ptr_equal> accmap_t;
    mutable accmap_t accmap_;
    mutable accmap_t accmapu_;

    /// Unicity table for degeneralized states.  See create_state()
    mutable void* uniq_map_;

    // Disallow copy.
    tgba_tba_proxy(const tgba_tba_proxy&);
    tgba_tba_proxy& operator=(const tgba_tba_proxy&);
  };

  /// \ingroup tgba_on_the_fly_algorithms
  /// \brief Degeneralize a spot::tgba on the fly, producing an SBA.
  ///
  /// This class acts as a proxy in front of a spot::tgba, that should
  /// be degeneralized on the fly.
  ///
  /// This is similar to tgba_tba_proxy, except that automata produced
  /// with this algorithms can also been seen as State-based Büchi
  /// Automata (SBA).  See tgba_sba_proxy::state_is_accepting().  (An
  /// SBA is a TBA, and a TBA is a TGBA.)
  ///
  /// This extra property has a small cost in size: if the input
  /// automaton uses N acceptance conditions, the output automaton can
  /// have at most max(N,1)+1 times more states and transitions.
  /// (This is only max(N,1) for tgba_tba_proxy.)
  ///
  /// If you want to degeneralize an automaton once for all, and not
  /// on-the-fly, consider using degeneralize() instead because it is
  /// usually faster.  Also the degeneralize() function implements
  /// several SCC-based optimizations that are not implemented in this
  /// one.
  ///
  /// \see degeneralize
  class SPOT_API tgba_sba_proxy : public tgba_tba_proxy
  {
  public:
    tgba_sba_proxy(const tgba* a);

    /// \brief Whether the state is accepting.
    ///
    /// A particularity of a spot::tgba_sba_proxy automaton is that
    /// when a state has an outgoing accepting arc, all its outgoing
    /// arcs are accepting.  The state itself can therefore be
    /// considered accepting.  This is useful in algorithms working on
    /// degeneralized automata with state acceptance conditions.
    bool state_is_accepting(const state* state) const;

    virtual state* get_init_state() const;
  protected:
    cycle_list::iterator cycle_start_;
  };

}
#endif // SPOT_TGBA_TGBATBA_HH