Add a new type of automata: State-labeled Alternating Büchi

Automata (SABA).

* src/saba/saba.hh, src/saba/saba.cc, src/saba/sabastate.hh,
src/saba/sabasucciter.hh: New.  Interface for
SABA (State-labeled Alternating Büchi Automata).
* src/saba/explicitstateconjunction.cc,
src/saba/explicitstateconjunction.hh: New.  Default
implementation for a conjunction of states.
* src/saba/Makefile.am: New.
* src/Makefile.am, configure.ac: Adjust.
* src/sabaalgos/sabareachiter.cc,
src/sabaalgos/sabareachiter.hh: New.  Iterate over all reachable
states of a spot::saba.
* src/sabaalgos/sabadotty.cc, src/sabaalgos/sabadotty.hh: New.
Print reachable states in dot format.
* src/sabaalgos/Makefile.am: New.

src/saba/saba.hh

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+// Copyright (C) 2009 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_SABA_SABA_HH
+# define SPOT_SABA_SABA_HH
+
+#include "sabastate.hh"
+#include "sabasucciter.hh"
+#include <tgba/bdddict.hh>
+
+namespace spot
+{
+  /// \defgroup saba SABA (State-based Alternating Büchi Automata)
+  ///
+  /// Spot was centered around non-deterministic \ref tgba.
+  /// Alternating automata are an extension to non-deterministic
+  /// automata, and are presented with spot::saba.
+  /// This type and its cousins are listed \ref saba_essentials "here".
+  /// This is an abstract interface.
+
+  /// \addtogroup saba_essentials Essential SABA types
+  /// \ingroup saba
+
+  /// \brief A State-based Alternating (Generalized) Büchi Automaton.
+  /// \ingroup saba_essentials
+  ///
+  /// Browsing such automaton can be achieved using two functions:
+  /// \c get_init_state, and \c succ_iter.  The former returns
+  /// the initial state while the latter lists the
+  /// successor states of any state.
+  ///
+  /// Note that although this is a transition-based automata,
+  /// we never represent transitions!  Transition informations are
+  /// obtained by querying the iterator over the successors of
+  /// a state.
+  class saba
+  {
+  protected:
+    saba();
+
+  public:
+    virtual ~saba();
+
+    /// \brief Get the initial state of the automaton.
+    ///
+    /// The state has been allocated with \c new.  It is the
+    /// responsability of the caller to \c delete it when no
+    /// longer needed.
+    virtual saba_state* get_init_state() const = 0;
+
+    /// \brief Get an iterator over the successors of \a local_state.
+    ///
+    /// The iterator has been allocated with \c new.  It is the
+    /// responsability of the caller to \c delete it when no
+    /// longer needed.
+    ///
+    /// \param local_state The state whose successors are to be explored.
+    /// This pointer is not adopted in any way by \c succ_iter, and
+    /// it is still the caller's responsability to delete it when
+    /// appropriate (this can be done during the lifetime of
+    /// the iterator).
+    virtual saba_succ_iterator*
+    succ_iter(const saba_state* local_state) const = 0;
+
+    /// \brief Get the dictionary associated to the automaton.
+    ///
+    /// State are represented as BDDs.  The dictionary allows
+    /// to map BDD variables back to formulae, and vice versa.
+    /// This is useful when dealing with several automata (which
+    /// may use the same BDD variable for different formula),
+    /// or simply when printing.
+    virtual bdd_dict* get_dict() const = 0;
+
+    /// \brief Format the state as a string for printing.
+    ///
+    /// This formating is the responsability of the automata
+    /// that owns the state.
+    virtual std::string format_state(const saba_state* state) const = 0;
+
+    /// \brief Return the set of all acceptance conditions used
+    /// by this automaton.
+    ///
+    /// The goal of the emptiness check is to ensure that
+    /// a strongly connected component walks through each
+    /// of these acceptiong conditions.  I.e., the union
+    /// of the acceptiong conditions of all transition in
+    /// the SCC should be equal to the result of this function.
+    virtual bdd all_acceptance_conditions() const = 0;
+
+    /// The number of acceptance conditions.
+    virtual unsigned int number_of_acceptance_conditions() const;
+  private:
+    mutable int num_acc_;
+  };
+
+} // end namespace spot.
+
+
+#endif // SPOT_SABA_SABA_HH