/*
Research Project:   Graphical Database for Category Theory
                    J. Bradbury, Dr. R. Rosebrugh, I. Rutherford
                    Mount Allison University 2001
File:               Graph.java
                    (author: Larry Barowski & David E. Daniels,
                             Auburn University, 4/29/96)
Description:	      A class for representing a graph abstractly.
*/

  //Import statements
   import java.io.IOException;
   import java.util.Hashtable;
   import java.util.Enumeration;
   import java.awt.Point;
   import java.lang.Math;
   import java.lang.System;

   public class Graph implements Cloneable
   {
   /**
    *nodeList_ holds the graph
    */
      private NodeList 	nodeList_;
      private Hashtable	idHash_;
      private boolean 	directed_ = false;
      private int	lastTopId_;
      private Hashtable	edges_;  // For edges with intermediate points.
   
   
   
   
   /**
   * construct empty graph
   */
      public Graph()
      {
         nodeList_ = new NodeList();
         idHash_ = new Hashtable();
         edges_ = new Hashtable();
         lastTopId_ = 0;
      }
   
   
   
   
   /**
   * construct empty graph with direction
   */
      public Graph(boolean yesorno)
      {
         nodeList_ = new NodeList();
         idHash_ = new Hashtable();
         edges_ = new Hashtable();
         lastTopId_ = 0;
         directed_ = yesorno;
      }
   
   
   
   
   
      public Graph(GMLobject gml)
      {
         nodeList_ = new NodeList();
         idHash_ = new Hashtable();
         edges_ = new Hashtable();
         lastTopId_ = 0;
      
         directed_ = false;
         Integer tmp;
         if((tmp = (Integer)gml.getValue("directed", GMLobject.GMLinteger)) != null)
            directed_ = (tmp.intValue() != 0);
      
         Node node;
         GMLobject nodegml;
         for(nodegml = gml.getGMLSubObject("node", GMLobject.GMLlist, false);
             nodegml != null; nodegml = gml.getNextGMLSubObject())
         {
            node = new Node(nodegml);
         
            Integer id;
            if((id = node.getIdObject()) != null)
            {
               if(!idHash_.containsKey(id))  // Discard nodes with duplicate id's.
               {
                  idHash_.put(id, node);
                  nodeList_.addNode(node);
               }
            }
            else
               nodeList_.addNode(node);
         }
      
         GMLobject edgegml;
         for(edgegml = gml.getGMLSubObject("edge", GMLobject.GMLlist, false);
             edgegml != null; edgegml = gml.getNextGMLSubObject())
         {
            Integer source, target;
         
            source = (Integer)edgegml.getValue("source", GMLobject.GMLinteger);
            target = (Integer)edgegml.getValue("target", GMLobject.GMLinteger);
         
            if(source != null && target != null)
            {
               Node sourcenode, targetnode;
               sourcenode = (Node)idHash_.get(source);
               targetnode = (Node)idHash_.get(target);
               if(sourcenode != null && targetnode != null)
                  insertEdge(new Edge(sourcenode, targetnode, edgegml));
            }
         }
      
         validateIds();
      
         // Initialize the groups.
         Node tmpnode;
         for(tmpnode = firstNode(); tmpnode != null; tmpnode = nextNode(tmpnode)) {
            if(tmpnode.inGroup()) {
               tmpnode.groupNode_ = (Node)idHash_.get(new Integer(tmpnode.groupNodeId_));
               if(tmpnode.groupNode_ != null) {
                  tmpnode.groupNode_.isGroup_ = true;
                  tmpnode.groupNode_.setChild(tmpnode.getIndex());
               }
            }
         }
      }
   
   
   
   
   
   // Set id's for non-id'd nodes, so all nodes have id's.
      private void validateIds()
      {
      	// Initialize lastTopId_.
         lastTopId_ = 0;
         while(idHash_.containsKey(new Integer(lastTopId_)))
            lastTopId_++;
      
      	// Fill in empty ids.
         Node tmpnode;
         for(tmpnode = firstNode(); tmpnode != null; tmpnode = nextNode(tmpnode))
            if(tmpnode.getIdObject() == null)
            {
               tmpnode.id_ = lastTopId_;
               tmpnode.haveId_ = true;
               idHash_.put(new Integer(lastTopId_), tmpnode);
            
               do 
               { 
                  lastTopId_++; 
               }
               while (idHash_.containsKey(new Integer(lastTopId_)));
            }
      }
   
   
   
   
   
   
   
   /** Set the GML values of a GML object to those of this Graph. */
   
   /* change later so GML is attached to Nodes (and edges) ****/
      public void setGMLvalues(GMLobject gml)
      {
         Node node;
      	// Nodes
         gml.deleteAll("node", GMLobject.GMLlist);
         for(node = nodeList_.firstNode(); node != null; node = nodeList_.nextNode(node))
         {
            GMLobject nodegml = new GMLobject("node", GMLobject.GMLlist);
            gml.addObjectToEnd(nodegml);
            node.setGMLvalues(nodegml);
         }
      
         gml.setValue("directed", GMLobject.GMLinteger, new Integer(directed_? 1: 0));
      
      	// Edges
         gml.deleteAll("edge", GMLobject.GMLlist);
      
         Enumeration edges = edges_.elements();
         while(edges.hasMoreElements())
         {
            Edge edge = (Edge)(edges.nextElement());
            if(directed_ || edge.tail().getIndex() <= edge.head().getIndex())
            {
               GMLobject edgegml = new GMLobject("edge", GMLobject.GMLlist);
               gml.addObjectToEnd(edgegml);
               edge.setGMLvalues(edgegml);
            }
         }
      
      
      }
   
   
   
   
   
   
   // boolean isDirected()======================================================
   /**
    * function to determine the graph type (directed or undirected)
    * @return boolean value
    */
      public boolean isDirected()
      {
         if (directed_)
         {
            return directed_;
         }
         else
            return directed_;
      }
   
   
   
   // clone()===================================================================
   /**
    * makes a copy of the current graph
    * @return copy of current graph
    */
      public Object clone()
      {
         Graph copy;
      
         try
         {
            copy=(Graph)super.clone();
            copy.nodeList_ = (NodeList)nodeList_.clone();
            copy.idHash_ = new Hashtable();
            copy.edges_ = new Hashtable();
            copy.directed_ = directed_;
            copy.lastTopId_ = lastTopId_;
         
            Enumeration edges = edges_.elements();
            while(edges.hasMoreElements())
            {
               Edge edge = (Edge)(edges.nextElement());
               Node head, tail;
               tail = copy.nodeList_.nodeFromIndex(edge.tail_.getIndex());
               head = copy.nodeList_.nodeFromIndex(edge.head_.getIndex());
            
               Edge newedge = new Edge(tail, head, edge);
               copy.edges_.put(new Point(tail.index_, head.index_), newedge);
            }
         
            Node tmpnode;
            for(tmpnode = copy.firstNode(); tmpnode != null; tmpnode = copy.nextNode(tmpnode))
               copy.idHash_.put(new Integer(tmpnode.getId()), tmpnode);
         
            return copy;
         }
            catch(CloneNotSupportedException e)
            {
            }
         return null;
      }
   
   
   
    /**
     * Copy the properties of another graph. This assumes the other graph
     * will be subsequently deleted - otherwise use copy(clone(graph_to_copy)).
     */
      public void copy(Graph newgraph)
      {
         directed_ = newgraph.directed_;
         nodeList_ = newgraph.nodeList_;
         idHash_ = newgraph.idHash_;
         edges_ = newgraph.edges_;
         lastTopId_ = newgraph.lastTopId_;
      }
   
   
   
   // insertNode()==============================================================
   /**
    * insert new node into graph; no initial connections
    * @return index of the new node
    */
      public int insertNode()
      {
         return insertNode(false);
      }
   
   
   
   
   /**
    * Insert new node or dummy node into the graph.
    * @return index of the new node
    */
      public int insertNode(boolean dummy)
      {
         Node node;
      
         node = new Node(dummy);
         nodeList_.addNode(node);
      
         node.haveId_ = true;
         node.id_ = lastTopId_;
         idHash_.put(new Integer(lastTopId_), node);
         do 
            lastTopId_++; 
         while (idHash_.containsKey(new Integer(lastTopId_)));
      
         return node.index_;
      }
   
   //getNodeFromIndex(int index)================================================
   /**
    * @returns the node at  the 'index'
    */
      public Node getNodeFromIndex(int index)
      { 
         return nodeList_.nodeFromIndex(index); 
      }
   
   
   
      public Node getNodeFromId(int id)
      { 
         return (Node)(idHash_.get(new Integer(id))); 
      }
   
   
   
   // insertNodeAt(int index)===================================================
   /**
    * insert new node into graph; into the nodelist at the index
    * @param integer index to place node
    * @return nodeList_ with the new node
    */
      public void insertNodeAt(int index) throws IOException
      {
         Node node;
         IOException e = new IOException("Node " + index +" already exist.");
      
         if(nodeList_.nodeFromIndex(index) == null)
         { 
            node = new Node();
            nodeList_.addNodeAt(node, index);
         
            node.haveId_ = true;
            node.id_ = lastTopId_;
            idHash_.put(new Integer(lastTopId_), node);
            do 
            { 
               lastTopId_++; 
            }
            while (idHash_.containsKey(new Integer(lastTopId_)));
         }
         else
         {
            throw e;  
         }       
      }
   
   /**
    * remove the node from the graph(also removes the edges connected to it)
    */
      public void removeNode(int n)
      {
         Set pSet = new Set();
         Set cSet = new Set();
         Node node;
      
         Node remnode = (Node)nodeList_.nodeFromIndex(n);
      
         if(remnode.isGroup()) {
            int child_index;
            Node child;
         
            for(child_index = remnode.firstChild(); child_index != -1;
                child_index = remnode.nextChild())
               removeNode(child_index);
         }
         else {
         
            for(int child = remnode.firstChild(); child != -1;
                child = remnode.nextChild())
               removeEdge(n, child);
         
            for (node = nodeList_.firstNode(); node != null;
                 node = nodeList_.nextNode(node))
               if (node.hasChild(n))
                  removeEdge(node.getIndex(), n);
         }
      
         nodeList_.removeNodeAt(n);
         Integer id = remnode.getIdObject();
         idHash_.remove(id);
         if(id.intValue() < lastTopId_)
            lastTopId_ = id.intValue();
      
         // If group parent is an empty group, remove it.
         if(remnode.inGroup()) {
            remnode.groupNode_.clearChild(remnode.getIndex());
            if(remnode.groupNode_.firstChild() == -1)
               removeNode(remnode.groupNode_.getIndex());
         }
      }
   
   
   
   /**
    * remove the node from the graph 
    */
      public void removeNode(Node nin)
      {
         removeNode(nin.getIndex());
      }  
   
   
   
   // insertEdge(int n1, int n2)
   /**
    * insert an edge between two nodes
    * @param two integers node indexes
    * 
    */
      public void insertEdge(int n1, int n2)
      {
         insertEdge(n1, n2, new DPoint3[0]);
      }
   
   
   
   
   /**
    * Insert an edge with path points.
    */
      public void insertEdge(int n1, int n2, DPoint3[] points)
      {
         insertEdge(new Edge(nodeList_.nodeFromIndex(n1), nodeList_.nodeFromIndex(n2),
                             points, false));
      }
   
   
   
    /**
    * Insert an edge with path points and a label.
    */
      public void insertEdge(int n1, int n2, DPoint3[] points, String label)
      {
         Edge edge = new Edge(nodeList_.nodeFromIndex(n1),
                nodeList_.nodeFromIndex(n2), points, false);
         insertEdge(edge);
         edge.setLabel(label);
      }
   
   


   
   /**
    * Insert an edge.
    */
      public void insertEdge(Edge edge)
      {
         Node tempnode;
      
         int n1 = edge.tail().getIndex();
         int n2 = edge.head().getIndex();
      
         edges_.remove(new Point(n1, n2));
         if(!directed_)
            edges_.remove(new Point(n2, n1));
      
         edge.tail().setChild(n2);
         if (!directed_)
            edge.head().setChild(n1); 
      
         edges_.put(new Point(n1, n2), edge);
         DPoint3[] points = edge.points();
         if(!directed_ && n1 != n2)
         {
            int length = points.length;
            DPoint3[] reverse_points = new DPoint3[length];
            for(int i = 0; i < length; i++)
               reverse_points[i] = points[length - 1 - i];
         
            edges_.put(new Point(n2, n1), new Edge(edge.head(), edge.tail(),
                                                   reverse_points, false));
         }
      }
   
   
   
   
   
   /**
    * Get the path points for an edge.
    */
      public DPoint3[] getEdgePathPoints(int n1, int n2)
      {
         Edge edge = (Edge)(edges_.get(new Point(n1, n2)));
         if(edge == null)
            return null;
      
         return edge.points();
      }
   
   
   
   
   
   
      public Edge getEdge(int n1, int n2)
      {
         return (Edge)(edges_.get(new Point(n1, n2)));
      }
   
   
   
   
   
   // removeEdge(int n1, int n2)================================================
   /**
    * remove the connection from n1 to n2 but leave the nodes in place
    * @param integer index of each node on the edge
    */
      public void removeEdge(int n1, int n2)
      {
         Node tempnode = nodeList_.nodeFromIndex(n1);
         tempnode.clearChild(n2);
         edges_.remove(new Point(n1, n2));
         if (!directed_ && (n1 != n2))
         {
            tempnode = nodeList_.nodeFromIndex(n2);
            tempnode.clearChild(n1); 
            edges_.remove(new Point(n2, n1));
         } 
      
      }
   
   
   
   
      public void removeEdge(Edge edge)
      {
         removeEdge(edge.tail().getIndex(), edge.head().getIndex());
      }
   
   
   
   
   
   // parents(int n)============================================================
   /**
    * @param node to get parents of
    * @returns a set of all the nodes leading to n
    */
      public Set parents(int n)
      {
         Set parents = new Set();
         Node node;
      
         for (node = nodeList_.firstNode(); node !=null;
              node=nodeList_.nextNode(node))
         {
            if (node.hasChild(n))
               parents.includeElement(node.index_);
         }
         return parents;
      }
   
   
   
   
   
   // children(int n)===========================================================
   /**
    * @returns a set of all the nodes n leads to
    */
      public Set children(int n)
      {
         return nodeList_.nodeFromIndex(n).getChildren();
      }
   
   // numberOfNodes()===========================================================
   /**
    * @returns the number of nodes in the graph
    */
      public int numberOfNodes()
      {
         return nodeList_.count();
      }
   
   // firstNode()===============================================================
   /**
    * @returns the first node of the graph
    */
      public Node firstNode()
      {
         return nodeList_.firstNode();
      }
   
   
   //nextNode(Node node)========================================================
   /**
    * @returns the next node after node
    */
      public Node nextNode(Node node)
      {
         return nodeList_.nextNode(node);
      }
   
   
   //getIndexFromNode (Node node)===============================================
   /**
    * @returns the integer value of the index for the node
    */
      public int getIndexFromNode (Node node)
      {
         return node.index_;
      }
   
   //firstNodeIndex()===========================================================
   /**
    * @returns the  index of the first node in graph.nodeList
    */
      public int firstNodeIndex()
      {
         return nodeList_.firstNodeIndex();
      }
   
   //nextNodeIndex(int index)===================================================
   /**
    * @returns the index of the next node after the current index
    */
      public int nextNodeIndex(int index)	
      {
         return nodeList_.nextNodeIndex(index);
      }
   
   //firstAvailable()===========================================================
      public int firstAvailable()
      {
         return nodeList_.getFirstAvailable();
      }
   
   //highestIndex()=====================================================================
      public int highestIndex()
      {
         return nodeList_.highestIndex();
      }
   
   
   
   
   
   
      public void setDirected(boolean directed)
      {
         if(directed == directed_)
            return;
      
         if(directed)  // From undirected to directed.
         {
            directed_ = true;
            removeFalseEdges_();
         }
         else
         {
            fillBackEdges_();
            directed_ = false;
         }
      }
   
   
   
   
      private void fillBackEdges_()
      {
         Enumeration edges = edges_.elements();
         while(edges.hasMoreElements())
         {
            Edge edge = (Edge)(edges.nextElement());
            if(edges_.get(new Point(edge.head().getIndex(), edge.tail().getIndex()))
               == null)
            {
               int n1 = edge.tail().getIndex();
               int n2 = edge.head().getIndex();
               edge.head().setChild(n1);
               DPoint3[] reverse_points;
               if(n1 > n2)
               {
                  DPoint3[] points = edge.points();
                  int length = points.length;
                  reverse_points = new DPoint3[length];
                  for(int i = 0; i < length; i++)
                     reverse_points[i] = points[length - 1 - i];
               }
               else
                  reverse_points = new DPoint3[0];
               edges_.put(new Point(n2, n1), new Edge(edge.head(), edge.tail(),
                                                      reverse_points, true));
            }
         }
      }
   
   
   
   
   
      private void removeFalseEdges_()
      {
         Enumeration edges = edges_.elements();
         while(edges.hasMoreElements())
         {
            Edge edge = (Edge)(edges.nextElement());
            if(edge.isDummy())
            {
               edge.tail().clearChild(edge.head().getIndex());
               edges_.remove(new Point(edge.tail().getIndex(),
                                       edge.head().getIndex()));
            }
         }
      }
   
   
   
   
      /** Re-index so the indexes go from 0 to number of
       *  nodes - 1.
       */
      public void pack()
      {
         int   map[];
         int n = numberOfNodes();
      
         if(n == nodeList_.highestIndex() + 1)
            return;
      
         int highest_index = nodeList_.highestIndex();
         map = new int[highest_index + 1];
      
         // Re-map the node indexes.
         int node_index, new_node_index;
         Node tmpnode;
         for(node_index = nextNodeIndex(n - 1); node_index != -1;
             node_index = nextNodeIndex(node_index))
         {
            tmpnode = getNodeFromIndex(node_index);
            nodeList_.addNode(tmpnode);  // This will re-map the index.
            map[node_index] = tmpnode.index_;
            nodeList_.removeNodeAt(node_index);
         }
      
      
         // Correct child lists.
         for(tmpnode = firstNode(); tmpnode != null; tmpnode = nextNode(tmpnode))
            for(int child = tmpnode.searchNextChild(n - 1); child != -1;
                child = tmpnode.searchNextChild(child + 1))
            {
               if(child >= n)
               {
                  tmpnode.setChild(map[child]);
                  tmpnode.clearChild(child);
               }
            }
      
         // Correct the edge hash table.
         Enumeration keys = edges_.keys();
         while(keys.hasMoreElements())
         {
            Point key = (Point)(keys.nextElement());
            if(key.x >= n || key.y >= n)
            {
               if(key.x > highest_index || key.y > highest_index)  // Must be a remnant.
                  edges_.remove(key);
               else
               {
                  Edge element = (Edge)edges_.get(key);
                  edges_.remove(key);
                  if(key.x >= n)
                     key.x = map[key.x];
                  if(key.y >= n)
                     key.y = map[key.y];
                  edges_.put(key, element);
               }
            }
         }
      }
   
   
   
   
   
      /** Eliminate edge paths.
       */
      public void removeEdgePaths()
      {
         Enumeration elements = edges_.elements();
         while(elements.hasMoreElements())
         {
            Edge edge = (Edge)(elements.nextElement());
            edge.points_ = new DPoint3[0];
         }
      }
   
   
   
   /** Convert dummy nodes to edge paths.
     */
      public void dummysToEdgePaths()
      {
         Node tmpnode;
         for(tmpnode = firstNode(); tmpnode != null; tmpnode = nextNode(tmpnode))
         {
            if(!tmpnode.isDummy_)
               for(int child = tmpnode.firstChild(); child != -1;
                   child = tmpnode.nextChild())
               {
                  Node childnode = getNodeFromIndex(child);
                  Node tmpchild = childnode;
                  int numdummies = 0;

                  String label = getEdge(tmpnode.index_, child).getLabel();
               
                  // Only the first child is used.
                  while(tmpchild != null && tmpchild.isDummy_)
                  {
                     numdummies++;
                     tmpchild = getNodeFromIndex(tmpchild.firstChild());
                  }
                  if(numdummies > 0 && tmpchild != null)
                  {
                     DPoint3[] edge_points = new DPoint3[numdummies];
                     tmpchild = childnode;
                     int dummy = 0;                   
                     while(tmpchild.isDummy_)
                     {
                        edge_points[dummy++] = new
                              DPoint3(tmpchild.getPosition3());
                        tmpchild = getNodeFromIndex(tmpchild.firstChild());
                     }
                     insertEdge(tmpnode.index_, tmpchild.index_, edge_points,
                             label);
                  }
               }
         }
      
         // Remove all dummy nodes.
         for(tmpnode = firstNode(); tmpnode != null;
                 tmpnode = nextNode(tmpnode))
            if(tmpnode.isDummy_)
               removeNode(tmpnode);
      }
   
   
   
   
   
      public Enumeration getEdges()
      {
         return edges_.elements();
      }
   
   
   
      public Node nodeFromIndex(int index)
      {
         return nodeList_.nodeFromIndex(index);
      }
   
   
   
   
      public void group(Node node, boolean state)
      {
         int child_index;
         Node child;
         if(state == true && node.groupNode_ != null) {
            node.groupNode_.groupActive_ = true;
            Node groupnode = node.groupNode_;
            markGroupChildren_(groupnode, true);
         
            DPoint3 pos = new DPoint3(0.0, 0.0, 0.0);
            DDimension3 size = new DDimension3(0.0, 0.0, 0.0);
            int n;
            n = getGroupCoordinates_(groupnode, pos, size);
         
            pos.x /= n;  pos.y /= n;  pos.z /= n;
            size.width = Math.sqrt(size.width);
            size.height = Math.sqrt(size.height);
            size.depth = Math.sqrt(size.depth);
         
            groupnode.setPosition(pos);
            groupnode.setBoundingBox(size);
            groupnode.grouppos_ = pos;
            groupnode.groupbox_ = size;
         }
         else if(state == false && node.isGroup_) {
         
            node.groupActive_ = false;
            markGroupChildren_(node, false);
         
            node.setSelected(false);
            double dx, dy, dz, rw, rh, rd;
            dx = node.x_ - node.grouppos_.x;
            dy = node.y_ - node.grouppos_.y;
            dz = node.z_ - node.grouppos_.z;
            rw = node.width_ / node.groupbox_.width;
            rh = node.height_ / node.groupbox_.height;
            rd = node.depth_ / node.groupbox_.depth;
         
            adjustGroupChildren_(node, dx, dy, dz, rw, rh, rd);
         }
      }
   
   
   
   
      private int getGroupCoordinates_(Node node, DPoint3 pos, DDimension3 size)
      {
         int child_index;
         Node child;
         int count = 0;
      
         for(child_index = node.firstChild(); child_index != -1;
             child_index = node.nextChild()) {
            child = getNodeFromIndex(child_index);
            if(child.isGroup() && !child.groupActive())
               count += getGroupCoordinates_(child, pos, size);
            else {
               count++;
               size.width += child.width_ * child.width_;
               size.height += child.height_ * child.height_;
               size.depth += child.depth_ * child.depth_;
               pos.x += child.x_;  pos.y += child.y_; pos.z += child.z_;
            }
         }
      
         return count;
      
      }
   
   
   
   
   
   
      private void adjustGroupChildren_(Node node, double dx, double dy, double dz,
                                        double rw, double rh, double rd)
      
      {
         int child_index;
         Node child;
      
         for(child_index = node.firstChild(); child_index != -1;
             child_index = node.nextChild()) {
            child = getNodeFromIndex(child_index);
            if(child.isGroup() && !child.groupActive())
               adjustGroupChildren_(child, dx, dy, dz, rw, rh, rd);
            else {
               child.x_ += dx;
               child.y_ += dy;
               child.z_ += dz;
               child.width_ *= rw;
               child.height_ *= rh;
               child.depth_ *= rd;
            }
         }
      
      }
   
   
   
   
      private void markGroupChildren_(Node node, boolean state)
      {
         int child_index;
         Node child;
      
         for(child_index = node.firstChild(); child_index != -1;
             child_index = node.nextChild()) {
            child = getNodeFromIndex(child_index);
            child.inActiveGroup_ = state;
            if(child.isGroup_ && (state == true || !child.groupActive_))
               markGroupChildren_(child, state);
         }
      
      }
   
   
   
   
   
      public void killGroup(Node node)
      {
         if(node.isGroup()) {
            int child_index;
            Node child;
         
            for(child_index = node.firstChild(); child_index != -1;
                child_index = node.nextChild()) {
               node.clearChild(child_index);
               child = getNodeFromIndex(child_index);
               child.inActiveGroup_ = false;
               child.groupNode_ = null;
            
               if(child.isGroup() && !child.groupActive_)
                  markGroupChildren_(child, false);
            }
         
            removeNode(node.getIndex());
         }
      }
   
   
   
      public void setNodeGroup(Node node, Node groupnode)
      {
      
         // Remove from current group.
         if(node.inGroup()) {
            Node current_group = node.groupNode_;
            current_group.clearChild(node.getIndex());
         
            // If group parent is an empty group, remove it.
            if(current_group.firstChild() == -1)
               removeNode(current_group.getIndex());
         }
      
      
         // Add to new group.
         node.groupNode_ = groupnode;
         groupnode.setChild(node.getIndex());
      }
   
   
   
   
      public void removeGroups()
      {
         int node_index;
      
         for(node_index = nodeList_.firstNodeIndex(); node_index != -1;
             node_index = nodeList_.nextNodeIndex(node_index)) {
            killGroup(getNodeFromIndex(node_index));
         }
      }
   
   }