ca.mcgill.cs.swevo.jayfx.model.FlyweightElementFactory.java Source code

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Here is the source code for ca.mcgill.cs.swevo.jayfx.model.FlyweightElementFactory.java

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/* JayFX - A Fact Extractor Plug-in for Eclipse
 * Copyright (C) 2006  McGill University (http://www.cs.mcgill.ca/~swevo/jayfx)
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * $Revision: 1.8 $
 */

package ca.mcgill.cs.swevo.jayfx.model;

import java.util.Hashtable;

import edu.ohio_state.cse.khatchad.ajplugintools.ajayfx.model.AJCodeElement;
import edu.ohio_state.cse.khatchad.ajplugintools.ajayfx.model.AdviceElement;
import edu.ohio_state.cse.khatchad.ajplugintools.ajayfx.model.AspectElement;
import org.jdom2.Element;

/**
 * Factory participant in the Flyweight design pattern. Produces unique IElement
 * objects representing the various elements in a Java program.
 */
public class FlyweightElementFactory {

    private FlyweightElementFactory() {

    }

    private static final String KEY_SEPARATOR = ":";

    private static Hashtable<String, IElement> aElements = new Hashtable<String, IElement>();

    /**
     * Returns a flyweight object representing a program element.
     * 
     * @param pCategory
     *            The category of element. Must be a value declared in Category.
     * @param pId
     *            The id for the element. For example, a field Id for
     *            Category.FIELD.
     * @see <a href=
     *      "http://java.sun.com/docs/books/jls/third_edition/html/binaryComp.html#13.1">
     *      Java Specification, Third Section, 13.1 Section for the binary name
     *      convention</a>
     * @return A flyweight IElement.
     * @exception InternalProblemException
     *                if an invalid category is passed as parameter.
     */
    public static IElement getElement(final Category pCategory, final String pId) {
        IElement lReturn = FlyweightElementFactory.aElements
                .get(pCategory + FlyweightElementFactory.KEY_SEPARATOR + pId);
        if (lReturn == null) {
            if (pCategory == Category.CLASS)
                lReturn = new ClassElement(pId);
            else if (pCategory == Category.FIELD)
                lReturn = new FieldElement(pId);
            else if (pCategory == Category.METHOD)
                lReturn = new MethodElement(pId);
            else if (pCategory == Category.PACKAGE)
                lReturn = new PackageElement(pId);
            else if (pCategory == Category.ASPECT)
                lReturn = new AspectElement(pId);
            else if (pCategory == Category.ADVICE)
                lReturn = new AdviceElement(pId);
            else if (pCategory == Category.AJCODE)
                lReturn = new AJCodeElement(pId);
            else
                throw new InternalProblemException("Invalid element category: " + pCategory);
            FlyweightElementFactory.aElements.put(pCategory + FlyweightElementFactory.KEY_SEPARATOR + pId, lReturn);
        }
        return lReturn;
    }

    /**
     * @param elementXML
     * @return
     */
    @SuppressWarnings("unchecked")
    public static <E> E getElement(Element elementXML) {
        // extract the category and the ID and delegate the behavior.
        String identifierString = elementXML.getAttribute(IElement.ID).getValue();
        Category category = Category.valueOf(elementXML.getChild(Category.class.getSimpleName()));
        return (E) getElement(category, identifierString);
    }
}