/*

     This file is part of Combean.

     Combean is free software; you can redistribute it and/or modify

     it under the terms of the GNU General Public License as published by

     the Free Software Foundation; either version 2 of the License, or

     (at your option) any later version.

     Combean 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

     GNU General Public License for more details.

     You should have received a copy of the GNU General Public License

     along with Combean; if not, write to the Free Software

     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

 */

 /*

  * Created on 20.02.2005

  *

  */

 package net.sourceforge.combean.graph.alg.traversal;

 import net.sourceforge.combean.graph.containers.NodeNumberingAdvisor;

 import net.sourceforge.combean.interfaces.graph.Graph;

 import net.sourceforge.combean.interfaces.graph.Node;

 import net.sourceforge.combean.interfaces.graph.containers.NodeNumbering;

 /**

  * @author schickin

  *

  */

 public class DFSNodeNumberingVisitor extends IdleDFSVisitor {

     /**

      * store dfs number, starting with 1

      * (will be set to the negative value of the actual dfs number

      * while the node is still in the dfs stack.

      */

     private NodeNumbering dfsNum = null;

     private int currentDFSNum = 0;

     /**

      * constructor 

      */

     public DFSNodeNumberingVisitor() {

         super();

     }

     /**

      * @return Returns the dfs numbering.

      */

     public final NodeNumbering getDfsNumbering() {

         return this.dfsNum;

     }

     /**

      * Set the dfs numbering. If left unset, the NodeNumberingAdvisor will

      * be consulted.

      * 

      * @param dfsNum The dfs numbering to set.

      */

     public final void setDfsNumbering(NodeNumbering dfsNum) {

         this.dfsNum = dfsNum;

     }

     /**

      * @param v

      * @return the dfs number of v (positive value,

      * regardless whether v is on the stack of not.

      */

     public final int getDfsNum(Node v) {

         return Math.abs(this.dfsNum.getNumber(v));

     }

     /**

      * @param v

      * @return true if v is on the dfs stack while the dfs is executed.

      */

     protected final boolean isOnStack(Node v) {

         return this.dfsNum.getNumber(v) < 0;

     }

     /* (non-Javadoc)

      * @see net.sourceforge.combean.interfaces.graph.alg.traverse.DFSVisitor#leaveNode(net.sourceforge.combean.interfaces.graph.Node)

      */

     public void leaveNode(Node v) {

         int dfsV = -this.dfsNum.getNumber(v);

         this.dfsNum.setNumber(v, dfsV);

     }

     /* (non-Javadoc)

      * @see net.sourceforge.combean.interfaces.graph.alg.traverse.TraversalVisitor#visitNode(net.sourceforge.combean.interfaces.graph.Node)

      */

     public void visitNode(Node v) {

         this.dfsNum.setNumber(v, -(++this.currentDFSNum));

     }

   /* (non-Javadoc)

      * @see net.sourceforge.combean.interfaces.graph.alg.traverse.TraversalVisitor#init(net.sourceforge.combean.interfaces.graph.Graph)

      */

     public void init(Graph g) {

         if (this.dfsNum == null) {

             this.dfsNum = NodeNumberingAdvisor.getFastestNodeNumbering(g);

         }

         this.dfsNum.init(g);

         this.currentDFSNum = 0;

     }

     /* (non-Javadoc)

      * @see net.sourceforge.combean.interfaces.graph.alg.traverse.TraversalVisitor#initLocal(net.sourceforge.combean.interfaces.graph.Graph, net.sourceforge.combean.interfaces.graph.Node)

      */

     public void initLocal(Graph g, Node startNode) {

         init(g);

     }

 }