carfield.com.hk

Leaf.java

2004-03-24T16:00:00Z

Main.java

2004-03-24T16:00:00Z

package examples.visitor.java;

/* -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * This file is part of the design patterns project at UBC
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * either http:*www.mozilla.org/MPL/ or http:*aspectj.org/MPL/.
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is ca.ubc.cs.spl.pattern.
 *
 * Contributor(s): 
 */

/**
 * Implements the driver for the Visitor design pattern example. 
 *
 * Intent: Represents an operation to be performed on the elements of an 
 * object structure. Visitor lets you define a new operation without changing
 * the classes of the elements on which it operates
 *
 * Participating classes are <code>SumVisitor</code> and 
 * <code>TraversalVisitor</code> as ConcreteVisitors, implementing the 
 * <code>NodeVisitor</code> interface. 
 * <code>RegularNode</code> and <code>Leaf</code> are ConcreteElements, 
 * implementing the <code>Node</code> interface. 
 *
 * In this example, Node, RegularNode and Leaf build up a binary tree that has 
 * int values as leafs. SumVisitor is a NodeVisitor that collects the sum of 
 * elements in the leafs (should be 6). TraversalVisitor is a visitor that 
 * collects a description of the tree like {{1,2},3}
 *
 * This is the Java version.
 *
 * Note that <UL>
 * <LI> Every visitor (even the inteface) has to know of each possible element 
 * type in the object structure. 
 * <LI> Nodes need to know of the visitor interface; they have to implement the 
 * accept(NodeVisitor) method.
 * </UL>
 *
 * @author Jan Hannemann
 * @author Gregor Kiczales
 * @version 1.0, 06/13/02
 * 
 * @see Node
 * @see RegularNode
 * @see Leaf
 * @see NodeVisitor
 * @see SumVisitor
 * @see TraversalVisitor
 */

public class Main { 
	
 /**
 * Implements the driver for the Visitor design pattern example. 
 *
 * In this example, Node, RegularNode and Leaf build up a binary tree that has 
 * int values as leafs. SumVisitor is a NodeVisitor that collects the sum of 
 * elements in the leafs (should be 6). TraversalVisitor is a visitor that 
 * collects a description of the tree like {{1,2},3} 
 *
 * @param args the command-line parameters, unused
 */


	public static void main(String[] args) { 
	 
	 System.out.println("Building the tree (1): leaves");
		
		Leaf one = new Leaf(1);
		Leaf two = new Leaf(2);
		Leaf three = new Leaf(3);
		
	 System.out.println("Building the tree (1): regular nodes");
		
		RegularNode regN = new RegularNode(one, two);
		RegularNode root = new RegularNode(regN, three);
		
 System.out.println("The tree now looks like this: ");
 System.out.println(" regN ");
 System.out.println(" / \\ ");
 System.out.println(" regN 3 ");
 System.out.println(" / \\ ");
 System.out.println(" 1 2 ");
		 
 System.out.println("Visitor 1: SumVisitor, collects the sum of leaf");
 System.out.println("values. Result should be 6.");
				 
		SumVisitor sumVisitor = new SumVisitor(); 
		root.accept(sumVisitor);
		System.out.println(sumVisitor.report()); 
		
 System.out.println("Visitor 2: TraversalVisitor, collects a tree");
 System.out.println("representation. Result should be {{1,2},3}.");
		
		TraversalVisitor traversalVisitor = new TraversalVisitor(); 
		root.accept(traversalVisitor);
		System.out.println(traversalVisitor.report()); 
	}
}

MyVisitor.java

2004-03-24T16:00:00Z

package examples.visitor.aspectj;

/* -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * This file is part of the design patterns project at UBC
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * either http:*www.mozilla.org/MPL/ or http:*aspectj.org/MPL/.
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is ca.ubc.cs.spl.pattern.
 *
 * Contributor(s): 
 */

import ca.ubc.cs.spl.pattern.library.VisitorProtocol;

/**
 * Implements a concrete visitor pattern instance. This aspect assings
 * the roles to the participants.
 *
 * @author Jan Hannemann
 * @author Gregor Kiczales
 * @version 1.0, 06/13/02
 */

public aspect MyVisitor extends VisitorProtocol { 
 
 /** 
 * Assigns the <code>VisitorNode</code> role to <code>Node</code>
 */

 declare parents: Node implements VisitorNode;

 /** 
 * Assigns the <code>VRegularNode</code> role to <code>RegularNode</code>
 */

 declare parents: RegularNode implements VRegularNode;

 /** 
 * Assigns the <code>VLeaf</code> role to <code>Leaf</code>
 */

 declare parents: Leaf implements VLeaf;
}

Node.java

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NodeVisitor.java

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RegularNode.java

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SumVisitor.java

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TraversalVisitor.java

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Visitor.java

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files.lst

2004-03-24T16:00:00Z