* src/tgba/bddprint.hh (bdd_format_set): New function.

* src/tgba/bddprint.cc (bdd_format_set): Likewise.
* src/tgba/state.hh: Add Doxygen comments.
(state::compare): Take a state*, not a state&.
(state_ptr_less_than): New functor.
* src/tgba/statebdd.hh (state_bdd::compare): Take a state*, not a
state&.
* src/tgba/statebdd.cc (state_bdd::compare): Likewise.
* src/tgba/succiter.hh: Add Doxygen comments.
* src/tgba/tgba.hh: Mention promises.
(tgba::formate_state): New pure virtual method.
* src/tgba/tgbabddconcrete.hh (tgba_bdd_concrete::formate_state):
New method.
* src/tgba/tgbabddconcrete.cc (tgba_bdd_concrete::formate_state):
Likewise.
* src/tgbaalgos/dotty.cc: Adjust to use state_ptr_less_than
and tgba::formate_state.

src/tgba/state.hh

@@ -5,25 +5,48 @@
 
 namespace spot
 {
+
+  /// \brief Abstract class for states.
   class state
   {
   public:
-    // Compares two states (that come from the same automaton).
-    //
-    // This method returns an integer less than, equal to, or greater
-    // than zero if THIS is found, respectively, to be less than, equal
-    // to, or greater than OTHER according to some implicit total order.
-    //
-    // This method should not be called to compare state from
-    // different automata.
-    virtual int compare(const state& other) const = 0;
-
-    virtual bdd as_bdd() const = 0;
+    /// \brief Compares two states (that come from the same automaton).
+    ///
+    /// This method returns an integer less than, equal to, or greater
+    /// than zero if \a this is found, respectively, to be less than, equal
+    /// to, or greater than \a other according to some implicit total order.
+    ///
+    /// This method should not be called to compare states from
+    /// different automata.
+    ///
+    /// \sa spot::state_ptr_less_than
+    virtual int compare(const state* other) const = 0;
 
     virtual ~state()
     {
     }
   };
+
+  /// \brief Strict Weak Ordering for \c state*.
+  ///
+  /// This is meant to be used as a comparison functor for
+  /// STL \c map whose key are of type \c state*.
+  ///
+  /// For instance here is how one could declare
+  /// a map of \c state*.
+  /// \code
+  ///   // Remember how many times each state has been visited.
+  ///   std::map<spot::state*, int, spot::state_ptr_less_than> seen;
+  /// \endcode
+  struct state_ptr_less_than
+  {
+    bool
+    operator()(const state* left, const state *right)
+    {
+      return left->compare(right) < 0;
+    }
+  };
+
 }
 
 #endif // SPOT_TGBA_STATE_HH