bdddict.hh

// -*- coding: utf-8 -*-
// Copyright (C) 2011, 2012, 2013 Laboratoire de Recherche et Développement
// de l'Epita (LRDE).
// 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_BDDDICT_HH
# define SPOT_TGBA_BDDDICT_HH

#include <list>
#include <set>
#include <map>
#include <iosfwd>
#include <bdd.h>
#include <vector>
#include "ltlast/formula.hh"
#include "misc/bddalloc.hh"

namespace spot
{

  /// \ingroup tgba_essentials
  /// \brief Map BDD variables to formulae.
  ///
  /// The BDD library uses integers to designate Boolean variables in
  /// its decision diagrams.  This class is used to map such integers
  /// to objects actually used in Spot.  These objects are usually
  /// atomic propositions, but they can also be acceptance conditions,
  /// or "Now/Next" variables (although the latter should be
  /// eventually removed).
  ///
  /// When a BDD variable is registered using a bdd_dict, it is always
  /// associated to a "user" (or "owner") object.  This is done by
  /// supplying the bdd_dict with a pointer to the intended user of
  /// the variable.  When the user object dies, it should release the
  /// BDD variables it was using by calling (for instance)
  /// unregister_all_my_variables(), giving the same pointer.
  /// Variables can also by unregistered one by one using
  /// unregister_variable().
  class bdd_dict: public bdd_allocator
  {
  public:

    bdd_dict();

    /// \brief Destroy the BDD dict.
    ///
    /// This always calls assert_emptiness() to diagnose cases where
    /// variables have not been unregistered.
    ~bdd_dict();

    /// Formula-to-BDD-variable maps.
    typedef std::map<const ltl::formula*, int> fv_map;
    /// BDD-variable-to-formula maps.
    typedef std::map<int, const ltl::formula*> vf_map;

    fv_map now_map;		///< Maps formulae to "Now" BDD variables
    fv_map var_map;		///< Maps atomic propositions to BDD variables
    fv_map acc_map;		///< Maps acceptance conditions to BDD variables

    /// BDD-variable reference counts.
    typedef std::set<const void*> ref_set;

    enum var_type { anon = 0, now, next, var, acc };
    struct bdd_info {
      bdd_info() : type(anon) {}
      var_type type;
      const ltl::formula* f;	// Used unless t==anon.
      ref_set refs;
      int clone_counts;
    };
    typedef std::vector<bdd_info> bdd_info_map;
    // Map BDD variables to their meaning.
    bdd_info_map bdd_map;

    /// \brief Map Next variables to Now variables.
    ///
    /// Use with BuDDy's bdd_replace() function.
    bddPair* next_to_now;
    /// \brief Map Now variables to Next variables.
    ///
    /// Use with BuDDy's bdd_replace() function.
    bddPair* now_to_next;

    /// \brief Register an atomic proposition.
    ///
    /// Return (and maybe allocate) a BDD variable designating formula
    /// \a f.  The \a for_me argument should point to the object using
    /// this BDD variable, this is used for reference counting.  It is
    /// perfectly safe to call this function several time with the same
    /// arguments.
    ///
    /// \return The variable number.  Use bdd_ithvar() or bdd_nithvar()
    ///   to convert this to a BDD.
    int register_proposition(const ltl::formula* f, const void* for_me);

    /// \brief Register BDD variables as atomic propositions.
    ///
    /// Register all variables occurring in \a f as atomic propositions
    /// used by \a for_me.  This assumes that these atomic propositions
    /// are already known from the dictionary (i.e., they have already
    /// been registered by register_proposition() for another
    /// automaton).
    void register_propositions(bdd f, const void* for_me);

    /// \brief Register a couple of Now/Next variables
    ///
    /// Return (and maybe allocate) two BDD variables for a state
    /// associated to formula \a f.  The \a for_me argument should point
    /// to the object using this BDD variable, this is used for
    /// reference counting.  It is perfectly safe to call this
    /// function several time with the same arguments.
    ///
    /// \return The first variable number.  Add one to get the second
    /// variable.  Use bdd_ithvar() or bdd_nithvar() to convert this
    /// to a BDD.
    int register_state(const ltl::formula* f, const void* for_me);

    /// \brief Register an atomic proposition.
    ///
    /// Return (and maybe allocate) a BDD variable designating an
    /// acceptance set associated to formula \a f.  The \a for_me
    /// argument should point to the object using this BDD variable,
    /// this is used for reference counting.  It is perfectly safe to
    /// call this function several time with the same arguments.
    ///
    /// \return The variable number.  Use bdd_ithvar() or bdd_nithvar()
    ///   to convert this to a BDD.
    int register_acceptance_variable(const ltl::formula* f, const void* for_me);

    /// \brief Clone an acceptance variable VAR for FOR_ME.
    ///
    /// This is used in products TGBAs when both operands share the
    /// same acceptance variables but they need to be distinguished in
    /// the result.
    int register_clone_acc(int var, const void* for_me);

    /// \brief Register BDD variables as acceptance variables.
    ///
    /// Register all variables occurring in \a f as acceptance variables
    /// used by \a for_me.  This assumes that these acceptance variables
    /// are already known from the dictionary (i.e., they have already
    /// been registered by register_acceptance_variable() for another
    /// automaton).
    void register_acceptance_variables(bdd f, const void* for_me);

    /// \brief Convert one acceptance condition into the associated
    /// formula.
    ///
    /// This version accepts a conjunction of Acc variables, in which
    /// only one must be positive.  This positive variable will be
    /// converted back into the associated formula.
    ///
    /// The returned formula is not cloned, and is valid until the BDD
    /// variable used in \a oneacc are unregistered.
    const ltl::formula* oneacc_to_formula(bdd oneacc) const;

    /// \brief Convert one acceptance condition into the associated
    /// formula.
    ///
    /// This version takes the number of a BDD variable that must has
    /// been returned by a call to register_acceptance_variable().
    ///
    /// The returned formula is not cloned, and is valid until the BDD
    /// variable \a var is unregistered.
    const ltl::formula* oneacc_to_formula(int var) const;

    /// \brief Register anonymous BDD variables.
    ///
    /// Return (and maybe allocate) \a n consecutive BDD variables which
    /// will be used only by \a for_me.
    ///
    /// \return The variable number.  Use bdd_ithvar() or bdd_nithvar()
    ///   to convert this to a BDD.
    int register_anonymous_variables(int n, const void* for_me);

    /// \brief Duplicate the variable usage of another object.
    ///
    /// This tells this dictionary that the \a for_me object
    /// will be using the same BDD variables as the \a from_other objects.
    /// This ensure that the variables won't be freed when \a from_other
    /// is deleted if \a from_other is still alive.
    void register_all_variables_of(const void* from_other, const void* for_me);

    /// \brief Release all variables used by an object.
    ///
    /// Usually called in the destructor if \a me.
    void unregister_all_my_variables(const void* me);

    /// \brief Release a variable used by \a me.
    void unregister_variable(int var, const void* me);

    /// @{
    /// Check whether formula \a f has already been registered by \a by_me.
    bool is_registered_proposition(const ltl::formula* f, const void* by_me);
    bool is_registered_state(const ltl::formula* f, const void* by_me);
    bool is_registered_acceptance_variable(const ltl::formula* f,
					   const void* by_me);
    /// @}

    /// \brief Dump all variables for debugging.
    /// \param os The output stream.
    std::ostream& dump(std::ostream& os) const;

    /// \brief Make sure the dictionary is empty.
    ///
    /// This will print diagnostics if the dictionary is not empty.
    /// Use for debugging.  This is called automatically by the
    /// destructor.  When Spot is compiled in development mode (i.e.,
    /// with <code>./configure --enable-devel</code>), this function
    /// will abort if the dictionary is not empty.
    ///
    /// The errors detected by this function usually indicate missing
    /// calls to unregister_variable() or
    /// unregister_all_my_variables().
    void assert_emptiness() const;

  protected:
    // SWIG does not grok the following definition, no idea why.
    // It's not important for the Python interface anyway.
#ifndef SWIG
    class anon_free_list : public spot::free_list
    {
    public:
      // WARNING: We need a default constructor so this can be used in
      // a hash; but we should ensure that no object in the hash is
      // constructed with d==0.
      anon_free_list(bdd_dict* d = 0);
      virtual int extend(int n);
    private:
      bdd_dict* dict_;
    };
#endif

    /// List of unused anonymous variable number for each automaton.
    typedef std::map<const void*, anon_free_list> free_anonymous_list_of_type;
    free_anonymous_list_of_type free_anonymous_list_of;

  private:
    // Disallow copy.
    bdd_dict(const bdd_dict& other);
    bdd_dict& operator=(const bdd_dict& other);
  };


}

#endif // SPOT_TGBA_BDDDICT_HH