sarray: add an empty query

array/sarray.hpp

@@ -99,6 +99,14 @@ namespace cruft {
             return m_size;
         }
 
+
+        //---------------------------------------------------------------------
+        bool empty (void) const
+        {
+            return m_size == 0;
+        }
+
+
         //---------------------------------------------------------------------
         T& operator[] (std::size_t i)& { return m_data.objects[i]; }
         const T& operator[] (std::size_t i) const& { return m_data.objects[i]; }