AbstractCompositeAspect.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.cocoon.portal.layout.renderer.aspect.impl;

import java.util.Iterator;

import org.apache.cocoon.portal.PortalService;
import org.apache.cocoon.portal.layout.CompositeLayout;
import org.apache.cocoon.portal.layout.Item;
import org.apache.cocoon.portal.layout.Layout;
import org.apache.cocoon.portal.layout.renderer.Renderer;
import org.apache.cocoon.portal.layout.renderer.aspect.RendererAspectContext;
import org.xml.sax.ContentHandler;
import org.xml.sax.SAXException;

/**
 * Insert a composite layout's elements into the resulting XML. Elements (items)
 * are processed in order. Concrete descendents of this class need to implement the
 * actual handling of layout elements.
 *
 * <h2>Applicable to:</h2>
 * <ul>
 *  <li>{@link org.apache.cocoon.portal.layout.CompositeLayout}</li>
 * </ul>
 *
 *
 * @author <a href="mailto:cziegeler@s-und-n.de">Carsten Ziegeler</a>
 * @author <a href="mailto:volker.schmitt@basf-it-services.com">Volker Schmitt</a>
 *
 * @version CVS $Id$
 */
public abstract class AbstractCompositeAspect
    extends AbstractAspect {

	/**
	 * @see org.apache.cocoon.portal.layout.renderer.aspect.impl.AbstractAspect#toSAX(org.apache.cocoon.portal.layout.renderer.aspect.RendererAspectContext, org.apache.cocoon.portal.layout.Layout, org.apache.cocoon.portal.PortalService, org.xml.sax.ContentHandler)
	 */
	public void toSAX(RendererAspectContext context,
              		  Layout                layout,
                	  PortalService         service,
                	  ContentHandler        handler)
	throws SAXException {
        if ( layout instanceof CompositeLayout) {
            CompositeLayout compositeLayout = (CompositeLayout)layout;
            // loop over all rows
            for (Iterator iter = compositeLayout.getItems().iterator(); iter.hasNext();) {
                Item item = (Item) iter.next();
                this.processItem(context, item, handler, service);
            }
        } else {
            throw new SAXException("CompositeLayout expected.");
        }
	}

    /**
     * Process a single layout element.
     *
     * @param item layout item to be processed
     * @param handler SAX handler taking events
     * @param service portal service providing component access
     * @throws SAXException
     */
    protected abstract void processItem(RendererAspectContext context,
                                        Item                  item,
                                        ContentHandler        handler,
                                        PortalService         service)
        throws SAXException;

    /**
     * Default implementation for processing a Layout. Calls the associated
     * renderer for a layout to render it.
     */
    protected void processLayout(Layout layout, PortalService service, ContentHandler handler) throws SAXException {
        if ( layout != null ) {
            final String rendererName = layout.getRendererName();
            final Renderer renderer = service.getComponentManager().getRenderer(rendererName);
            renderer.toSAX(layout, service, handler);
        }
    }
}