add a refcount field (for intrusive refcounting) to ScopePath

src/proc/mobject/session/scope-path.cpp

@@ -83,7 +83,8 @@ namespace session {
    *       may cause an empty default session to be created.
    */
   ScopePath::ScopePath ()
-    : path_()
+    : refcount_(0)
+    , path_()
   {
     clear();
   }
@@ -100,7 +101,8 @@ namespace session {
    *        can't be connected to the (implicit) root
    */
   ScopePath::ScopePath (Scope const& leaf)
-    : path_()
+    : refcount_(0)
+    , path_()
   {
     if (!leaf.isValid()) return; // invalid leaf defines invalid path....
     
@@ -109,6 +111,12 @@ namespace session {
   }
   
   
+  ScopePath::~ScopePath()
+  {
+    WARN_IF (refcount_, "Destroying a scope path frame with ref-count=%u", refcount_);
+  }
+  
+  
   /** constant \em invalid path token. Created by locating an invalid scope */
   const ScopePath ScopePath::INVALID = ScopePath(Scope());
   

src/proc/mobject/session/scope-path.hpp

@@ -110,6 +110,7 @@ namespace session {
   class ScopePath
     : public lib::BoolCheckable<ScopePath>
     {
+      size_t refcount_;
       std::vector<Scope> path_;
       
       typedef vector<Scope>                  _VType;
@@ -117,6 +118,7 @@ namespace session {
       typedef lib::RangeIter<_VIter>      _IterType;
       
     public:
+     ~ScopePath ();
       ScopePath ();
       ScopePath (Scope const& leaf);
       
@@ -127,6 +129,7 @@ namespace session {
       bool empty()      const;
       size_t size()     const;
       size_t length()   const;
+      size_t ref_count()const;
                         ////////////////////////////////////////TICKET #429 : diagnostic output to be added later
       
       /// Iteration is always ascending from leaf to root
@@ -179,6 +182,13 @@ namespace session {
   }
   
   
+  inline size_t
+  ScopePath::ref_count()  const
+  {
+    return refcount_;
+  }
+  
+  
   inline size_t
   ScopePath::length()  const
   {