    001    /*****************************************************************************
    002     * Copyright (C) PicoContainer Organization. All rights reserved.            *
    003     * ------------------------------------------------------------------------- *
    004     * The software in this package is published under the terms of the BSD      *
    005     * style license a copy of which has been included with this distribution in *
    006     * the LICENSE.txt file.                                                     *
    007     *****************************************************************************/
    008    package org.picocontainer.visitors;
    009
    010    import org.picocontainer.ComponentAdapter;
    011    import org.picocontainer.Parameter;
    012    import org.picocontainer.PicoContainer;
    013    import org.picocontainer.ComponentFactory;
    014    import org.picocontainer.visitors.AbstractPicoVisitor;
    015
    016
    017    /**
    018     * Concrete implementation of Visitor which simply checks traversals.
    019     * This can be a useful class for other Visitor implementations to extend,
    020     * as it provides a default implementation in case you one is only interested
    021     * in one PicoVisitor type.  Example:
    022     *
    023     *<pre>
    024     * PicoContainer container = new DefaultPicoContainer();
    025     * PicoContainer child = container.makeChildContainer();
    026     *
    027     * final List allContainers = new ArrayList();
    028     *
    029     * PicoVisitor visitor = new TraversalCheckingVisitor() {
    030     *     public boolean visitContainer(PicoContainer pico) {
    031     *         super.visitContainer(pico);  //Calls checkTraversal for us.
    032     *         allContainers.add(pico);
    033     *         return true;
    034     *     }
    035     * }
    036     * </pre>
    037     *
    038     * @author Michael Rimov
    039     */
    040    public class TraversalCheckingVisitor
    041            extends AbstractPicoVisitor {
    042
    043            /** {@inheritDoc} **/
    044        public boolean visitContainer(PicoContainer pico) {
    045            checkTraversal();
    046            return CONTINUE_TRAVERSAL;
    047        }
    048
    049            /** {@inheritDoc} **/
    050        public void visitComponentAdapter(ComponentAdapter<?> componentAdapter) {
    051            checkTraversal();
    052        }
    053
    054            /** {@inheritDoc} **/
    055        public void visitComponentFactory(ComponentFactory componentFactory) {
    056            checkTraversal();
    057        }
    058
    059            /** {@inheritDoc} **/
    060        public void visitParameter(Parameter parameter) {
    061            checkTraversal();
    062        }
    063
    064    }