Design Patterns discussion

["Atsushi Tanabe" <ttn13w30a9 AT mx1.ttcn.ne.jp>]

Hi,

Please try , traverse from a leaf to the root  in Visitor.
A sample code is as follows.

Regards

Atsushi Tanabe(Japanese)

--------------------------------------------------
TreeVisitor.java
--------------------------------------------------
public class TreeVisitor {

    public void Visit(TreeNode aNode){

        if(aNode.isLeaf()){
            String path = "";
            TreeNode aCurrentNode = aNode;
            while(aCurrentNode != null){
                path = aCurrentNode.label + path;
                aCurrentNode = aCurrentNode.parent;
            }
            System.out.println(path);
        }

    }
}

--------------------------------------------------
TreeNode.java
--------------------------------------------------
import java.util.ArrayList;

public class TreeNode {
    public String label;
    public TreeNode parent;

    private ArrayList _children = new ArrayList();
    TreeNode(String label){
        this.label = label;
    }

    public TreeNode add(TreeNode aTreeNode){
        aTreeNode.parent = this;
        _children.add(aTreeNode);
        return this;
    }
    public boolean isLeaf(){
        return _children.isEmpty();
    }
    public void Accept(TreeVisitor v){
        v.Visit(this);
        for(int i=0;i<_children.size();i++){
            ((TreeNode)_children.get(i)).Accept(v);
        }
    }

}

--------------------------------------------------
Main.java
--------------------------------------------------
public class Main {

    public static void main(String[] args) {
        TreeNode aTree  = new TreeNode("a");
        aTree.add(new TreeNode("b"));
        aTree.add((new TreeNode("c")).add((new TreeNode("d"))));

        aTree.Accept(new TreeVisitor());
    }

}

----- Original Message ----- 
From: "Lívio Cipriano" 
<lcipriano AT iol.pt>
To: "Roman Neuhauser" 
<neuhauser AT sigpipe.cz>
Cc: 
<gang-of-4-patterns AT cs.uiuc.edu>
Sent: Saturday, August 19, 2006 7:30 PM
Subject: Re: [gang-of-4-patterns] Visitor Pattern


Hi Roman,

The original Visitor pattern only addresses the "application" of the Visitor
to one Node (in a tree structure). Of course that was only an example, cause
the basic utility of this pattern is to add operations to a set of related
Classes.

My problem is that I've a tree structure, I've Visitores and I need to
traversal the tree applying the Visitores, so I'm looking for an example how
to do it. Some idea?

Regards

Lívio Cipriano

----- Original Message -----
# 
lcipriano AT iol.pt
 / 2006-08-19 10:48:13 +0100:
> I would like to find a pattern, maybe using the Visitor one, that can
> be used to traversal a tree.

    What is your question?
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