* src/tgbaalgos/ndfs_result.hxx (ndfs_result, acss_interface):

Conditionally inherit from acss_statistics.
* src/tgbaalgos/magic.cc, src/tgbaalgos/se05.cc, src/tgbaalgos/tau03.cc,
src/tgbaalgos/tau03opt.cc: Define Has_Size in all heaps.

ChangeLog

+2005-01-07  Alexandre Duret-Lutz  <adl@src.lip6.fr>
+
+	* src/tgbaalgos/ndfs_result.hxx (ndfs_result, acss_interface):
+	Conditionally inherit from acss_statistics.
+	* src/tgbaalgos/magic.cc, src/tgbaalgos/se05.cc, src/tgbaalgos/tau03.cc,
+	src/tgbaalgos/tau03opt.cc: Define Has_Size in all heaps.
+
 2005-01-06  Denis Poitrenaud  <Denis.Poitrenaud@lip6.fr>
 
 	* src/ltltest/randltl.cc: Include cassert.

src/tgbaalgos/magic.cc

@@ -387,6 +387,7 @@ namespace spot
           return (it != h.end());
         }
 
+      enum { Has_Size = 1 };
       int size() const
         {
           return h.size();
@@ -461,12 +462,7 @@ namespace spot
           return color((h[ha%size_] >> ((ha%4)*2)) & 3U) != WHITE;
         }
 
-      int size() const
-        {
-          // this method must return the number of state stored in the heap. Due
-          // to potential conflicts this size cannot be computed.
-          return 0;
-        }
+      enum { Has_Size = 0 };
 
     private:
       size_t size_;

src/tgbaalgos/ndfs_result.hxx

@@ -61,11 +61,37 @@ namespace spot
 
   typedef std::list<stack_item> stack_type;
 
+  namespace
+  {
+    // The acss_statistics is available only when the heap has a
+    // size() method (which we indicate using n==1).
+
+    template <typename T, int n>
+    struct acss_interface
+    {
+    };
+
+    template <typename T>
+    struct acss_interface<T, 1>
+      : public acss_statistics
+    {
+      int
+      acss_states() const
+      {
+	// all visited states are in the state space search
+	return dynamic_cast<const T*>(this)->h_.size();
+      }
+    };
+
+  }
+
+
   template <typename ndfs_search, typename heap>
   class ndfs_result:
     public emptiness_check_result,
     public ars_statistics,
-    public acss_statistics
+    // Conditionally inherit from acss_statistics.
+    public acss_interface<ndfs_result<ndfs_search, heap>, heap::Has_Size>
   {
   public:
     ndfs_result(const ndfs_search& ms)
@@ -74,12 +100,6 @@ namespace spot
     {
     }
 
-    int acss_states() const
-    {
-      // all visited states are in the state space search
-      return h_.size();
-    }
-
     virtual ~ndfs_result()
     {
     }
@@ -195,6 +215,8 @@ namespace spot
   private:
     const ndfs_search& ms_;
     const heap& h_;
+    template <typename T, int n>
+    friend struct acss_interface;
 
     struct transition {
       const state* source;

src/tgbaalgos/se05.cc

@@ -445,6 +445,7 @@ namespace spot
           return true;
         }
 
+      enum { Has_Size = 1 };
       int size() const
         {
           return h.size() + hc.size();
@@ -548,12 +549,7 @@ namespace spot
           return color((h[ha%size_] >> ((ha%4)*2)) & 3U) != WHITE;
         }
 
-      int size() const
-        {
-          // this method must return the number of state stored in the heap. Due
-          // to potential conflicts this size cannot be computed.
-          return 0;
-        }
+      enum { Has_Size = 0 };
 
     private:
       size_t size_;

src/tgbaalgos/tau03.cc

@@ -361,6 +361,7 @@ namespace spot
           return (it != h.end());
         }
 
+      enum { Has_Size = 1 };
       int size() const
         {
           return h.size();

src/tgbaalgos/tau03opt.cc

@@ -481,6 +481,7 @@ namespace spot
           return true;
         }
 
+      enum { Has_Size = 1 };
       int size() const
         {
           return h.size() + hc.size();