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AspectJ tools most notably contains the AspectJ compiler (AJC). AJC applies aspects to Java classes during compilation, fully replacing Javac for plain Java classes and also compiling native AspectJ or annotation-based @AspectJ syntax. Furthermore, AJC can weave aspects into existing class files in a post-compile binary weaving step. This library is a superset of AspectJ weaver and hence also of AspectJ runtime.

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/* *******************************************************************
 * Copyright (c) 1999-2001 Xerox Corporation,
 *               2002 Palo Alto Research Center, Incorporated (PARC).
 * All rights reserved.
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Public License v 2.0
 * which accompanies this distribution and is available at
 * https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.txt
 *
 * Contributors:
 *     Xerox/PARC     initial implementation
 * ******************************************************************/


package org.aspectj.ajde.ui.internal;

import java.util.Stack;

import org.aspectj.asm.IProgramElement;

/**
 * @author Mik Kersten
 */
public class NavigationHistoryModel {

    private IProgramElement currNode = null;
    private Stack backHistory = new Stack();
    private Stack forwardHistory = new Stack();

    /**
     * @return 	null if the history is empty
     */
	public IProgramElement navigateBack() {
		if (backHistory.isEmpty() || currNode == null) return null;

		forwardHistory.push(currNode);
		currNode = (IProgramElement)backHistory.pop();
		return currNode;
	}

    /**
     * @return 	null if the history is empty
     */
	public IProgramElement navigateForward() {
		if (forwardHistory.isEmpty() || currNode == null) return null;

		backHistory.push(currNode);
		currNode = (IProgramElement)forwardHistory.pop();
		return currNode;
	}


    public void navigateToNode(IProgramElement toNode) {
    	if (currNode != null) backHistory.push(currNode);
    	currNode = toNode;
    }
}