remove twa::compute_support_conditions

Fixes #148.

* spot/twa/twa.hh, spot/twa/twa.cc, spot/kripke/fairkripke.hh,
spot/kripke/fairkripke.cc, spot/ta/tgtaexplicit.hh,
spot/ta/tgtaexplicit.cc, spot/twa/twagraph.hh, spot/twa/twaproduct.hh,
spot/twa/twaproduct.cc, spot/twaalgos/stutter.cc, spot/twa/taatgba.hh,
spot/twa/taatgba.cc: Remove the method.
* spot/taalgos/tgba2ta.cc: Emulate it with a simple loop.
* NEWS: Mention the removal.

spot/twa/taatgba.cc

@@ -66,22 +66,6 @@ namespace spot
     return new taa_succ_iterator(s->get_state(), acc());
   }
 
-  bdd
-  taa_tgba::compute_support_conditions(const spot::state* s) const
-  {
-    const spot::set_state* se = down_cast<const spot::set_state*>(s);
-    assert(se);
-    const state_set* ss = se->get_state();
-
-    bdd res = bddtrue;
-    taa_tgba::state_set::const_iterator i;
-    taa_tgba::state::const_iterator j;
-    for (i = ss->begin(); i != ss->end(); ++i)
-      for (j = (*i)->begin(); j != (*i)->end(); ++j)
-	res |= (*j)->condition;
-    return res;
-  }
-
   /*----------.
   | state_set |
   `----------*/

spot/twa/taatgba.hh

@@ -58,8 +58,6 @@ namespace spot
     virtual std::string format_state(const spot::state* state) const = 0;
 
   protected:
-    virtual bdd compute_support_conditions(const spot::state* state)
-      const final;
 
     typedef std::vector<taa_tgba::state_set*> ss_vec;
 

spot/twa/twa.cc

@@ -30,8 +30,7 @@ namespace spot
 {
   twa::twa(const bdd_dict_ptr& d)
     : iter_cache_(nullptr),
-      dict_(d),
-      last_support_conditions_input_(nullptr)
+      dict_(d)
   {
     props = 0U;
     bddaps_ = bddtrue;
@@ -39,27 +38,11 @@ namespace spot
 
   twa::~twa()
   {
-    if (last_support_conditions_input_)
-      last_support_conditions_input_->destroy();
     delete iter_cache_;
     release_named_properties();
     get_dict()->unregister_all_my_variables(this);
   }
 
-  bdd
-  twa::support_conditions(const state* state) const
-  {
-    if (!last_support_conditions_input_
-	|| last_support_conditions_input_->compare(state) != 0)
-      {
-	last_support_conditions_output_ = compute_support_conditions(state);
-	if (last_support_conditions_input_)
-	  last_support_conditions_input_->destroy();
-	last_support_conditions_input_ = state->clone();
-      }
-    return last_support_conditions_output_;
-  }
-
   state*
   twa::project_state(const state* s,
 		      const const_twa_ptr& t) const

spot/twa/twa.hh

@@ -687,21 +687,6 @@ namespace spot
 	iter_cache_ = i;
     }
 
-    /// \brief Get a formula that must hold whatever successor is taken.
-    ///
-    /// \return A formula which must be verified for all successors
-    ///  of \a state.
-    ///
-    /// This can be as simple as \c bddtrue, or more precisely
-    /// the disjunction of the condition of all successors.  This
-    /// is used as an hint by \c succ_iter() to reduce the number
-    /// of successor to compute in a product.
-    ///
-    /// Sub classes should implement compute_support_conditions(),
-    /// this function is just a wrapper that will cache the
-    /// last return value for efficiency.
-    bdd support_conditions(const state* state) const;
-
     /// \brief Get the dictionary associated to the automaton.
     ///
     /// Automata are labeled by Boolean formulas over atomic
@@ -901,12 +886,7 @@ namespace spot
       return acc_.mark(0);
     }
 
-  protected:
-    /// Do the actual computation of tgba::support_conditions().
-    virtual bdd compute_support_conditions(const state* state) const = 0;
-    mutable const state* last_support_conditions_input_;
   private:
-    mutable bdd last_support_conditions_output_;
     std::vector<formula> aps_;
     bdd bddaps_;
 

spot/twa/twagraph.hh

@@ -202,9 +202,6 @@ namespace spot
 
     virtual ~twa_graph()
     {
-      // Prevent this state from being destroyed by ~twa(),
-      // as the state will be destroyed when g_ is destroyed.
-      last_support_conditions_input_ = nullptr;
     }
 
 #ifndef SWIG
@@ -425,14 +422,6 @@ namespace spot
       SPOT_RETURN(g_.is_dead_edge(t));
 #endif
 
-    virtual bdd compute_support_conditions(const state* s) const
-    {
-      bdd sum = bddfalse;
-      for (auto& t: out(state_number(s)))
-	sum |= t.cond;
-      return sum;
-    }
-
     /// Iterate over all edges, and merge those with compatible
     /// extremities and acceptance.
     void merge_edges();

spot/twa/twaproduct.cc

@@ -318,13 +318,6 @@ namespace spot
 
   twa_product::~twa_product()
   {
-    // Prevent these states from being destroyed by ~tgba(): they
-    // will be destroyed before when the pool is destructed.
-    if (last_support_conditions_input_)
-      {
-	last_support_conditions_input_->destroy();
-	last_support_conditions_input_ = nullptr;
-      }
   }
 
   const state*
@@ -359,16 +352,6 @@ namespace spot
       return new twa_succ_iterator_product(li, ri, this, p);
   }
 
-  bdd
-  twa_product::compute_support_conditions(const state* in) const
-  {
-    const state_product* s = down_cast<const state_product*>(in);
-    assert(s);
-    bdd lsc = left_->support_conditions(s->left());
-    bdd rsc = right_->support_conditions(s->right());
-    return lsc & rsc;
-  }
-
   const acc_cond& twa_product::left_acc() const
   {
     return left_->acc();

spot/twa/twaproduct.hh

@@ -102,9 +102,6 @@ namespace spot
     const acc_cond& left_acc() const;
     const acc_cond& right_acc() const;
 
-  protected:
-    virtual bdd compute_support_conditions(const state* state) const;
-
   protected:
     const_twa_ptr left_;
     const_twa_ptr right_;