* tgbaalgos/emptiness_stats.hh (unsigned_statistics): New base

class for ec_statistics and ars_statistics.
(acss_statistics): Inherit from ars_statistics.
* tgbaalgos/emptiness.cc, tgbaalgos/emptiness.hh:
(emptiness_check::statistics, emptiness_check_result::statistics):
New methods.
* tgbatest/randtgba.cc: Adjust to use the above.
* tgbaalgos/gv04.cc, tgbaalgos/ndfs_result.hxx, tgbaalgos/gtec/ce.cc,
tgbaalgos/gtec/ce.hh: Do not inherit from ars_statistics if
acss_statistics is used.

src/tgbaalgos/emptiness.hh

@@ -26,6 +26,7 @@
 #include <iosfwd>
 #include <bdd.h>
 #include "tgba/state.hh"
+#include "emptiness_stats.hh"
 
 namespace spot
 {
@@ -98,6 +99,10 @@ namespace spot
     {
       return a_;
     }
+
+    /// Return statistics, if available.
+    virtual const unsigned_statistics* statistics() const;
+
   protected:
     const tgba* a_;		///< The automaton.
   };
@@ -131,6 +136,9 @@ namespace spot
     /// several time, but generally you should not assume that.
     virtual emptiness_check_result* check() = 0;
 
+    /// Return statistics, if available.
+    virtual const unsigned_statistics* statistics() const;
+
     /// Print statistics, if any.
     virtual std::ostream& print_stats(std::ostream& os) const;