placement and pointee equivalence tests

src/proc/mobject/mobject-ref.hpp

@@ -312,5 +312,29 @@ namespace mobject {
   typedef MORef<MObject> MObjectRef;
   
   
+  /* === convenience shortcuts === */
+  
+  /** check if the two references actually share ownership
+   *  on the same underlying \em MObject (as opposed to referring
+   *  to the same \em Placement, which is tested by \c operator== )
+   */
+  template<class MOX, class MOY>
+  inline bool
+  isSharedPointee (MORef<MOX> const& ref1, MORef<MOY> const& ref2)
+  {
+    return ref1.isValid() && ref2.isValid()
+        && isSharedPointee (ref1.getPlacement(), ref2.getPlacement());
+  }
+  
+  /** check if the two references actually denote an equivalent placement */
+  template<class MOX, class MOY>
+  inline bool
+  isEquivalentPlacement (MORef<MOX> const& ref1, MORef<MOY> const& ref2)
+  {
+    return ref1.isValid() && ref2.isValid()
+        && isSameDef (ref1.getPlacement(), ref2.getPlacement());
+  }
+  
+  
 } // namespace mobject
 #endif

src/proc/mobject/placement.hpp

@@ -161,6 +161,14 @@ namespace mobject {
           target = static_pointer_cast<Y>(*this);
         }
       
+      /** free function to detect two placements sharing a pointee */
+      friend bool
+      isSharedPointee (Placement const& p1, Placement const& p2)
+      {
+        return static_cast<const void*> (p1.get())
+            == static_cast<const void*> (p2.get());
+      }
+      
       
       operator string()   const ;
       size_t use_count()  const { return _SmartPtr::use_count(); }