Added osg::RefNodePath class for handling node paths.

include/osg/RefNodePath

@@ -0,0 +1,101 @@
+/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2003 Robert Osfield 
+ *
+ * This library is open source and may be redistributed and/or modified under  
+ * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
+ * (at your option) any later version.  The full license is in LICENSE file
+ * included with this distribution, and on the openscenegraph.org website.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
+ * OpenSceneGraph Public License for more details.
+*/
+
+#ifndef OSG_REFNODEPATH
+#define OSG_REFNODEPATH 1
+
+#include <osg/Group>
+
+namespace osg {
+
+class RefNodePath : public NodeList
+{
+    public :
+    
+        inline RefNodePath() {}
+
+        inline RefNodePath(const RefNodePath& refNodePath):
+            NodeList(refNodePath) {}
+
+        inline explicit RefNodePath(const NodePath& nodePath)
+        {
+            for(osg::NodePath::const_iterator itr=nodePath.begin();
+                itr != nodePath.end();
+                ++itr)
+            {
+                push_back(*itr);
+            }
+        }
+        
+        inline operator NodePath () const
+        {
+            NodePath nodePath;
+            for(NodeList::const_iterator itr=begin();
+                itr != end();
+                ++itr)
+            {
+                nodePath.push_back(const_cast<Node*>(itr->get()));
+            }
+            
+            return nodePath;
+        }
+        
+        /** Check the validity of the RefNodePath to ensure that the parent path
+          * matches those availble in the leaf node of the path.*/
+        bool valid() const
+        {
+            // an empty NodePaath is invalid.
+            if (empty()) return false;
+        
+            // check to make sure that this RefNodeList isn't the only
+            // place that the nodes are referenced, if one node has
+            // a ref count of 1 then nodes must have been removed 
+            // from the scene graph elsewhere invalidating this RefNodePath.
+            for(const_iterator itr=begin();
+                itr != end();
+                ++itr)
+            {
+                if ((*itr)->referenceCount()<=1) return false;
+            }
+            
+            const_reverse_iterator ritr=rbegin();
+            const osg::Node* node = ritr->get();
+            ++ritr;
+            while (ritr!=rend())
+            {
+                const osg::Node* parent = ritr->get();
+                // search of parent in current nodes parent list
+                const osg::Node::ParentList& parents = node->getParents();
+                osg::Node::ParentList::const_iterator pitr=parents.begin();
+                for(; pitr!=parents.end() && parent!=*pitr; ++pitr) {}
+                if (pitr==parents.end()) 
+                {
+                    // original parent not found, so linkage must have changed
+                    // invalidating this RefNodePath.
+                    return false;
+                }
+
+                node = parent;                
+                ++ritr;
+            }
+            
+            // we've passed all the test that could invalidate this RefNodePath
+            return true;
+     }
+    
+};
+
+} // namespace
+
+#endif
+