001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.wicket.markup.resolver;
018
019import org.apache.wicket.Component;
020import org.apache.wicket.MarkupContainer;
021import org.apache.wicket.markup.ComponentTag;
022import org.apache.wicket.markup.MarkupStream;
023import org.apache.wicket.markup.WicketTag;
024import org.slf4j.Logger;
025import org.slf4j.LoggerFactory;
026
027
028/**
029 * This is a tag resolver which handles <wicket:container>
030 * 
031 * Sometimes adding components in certain ways may lead to output of invalid markup. For example,
032 * lets pretend we output table rows two at a time using a repeater. The markup would look something
033 * like this:
034 * 
035 * <code>
036 *      &lt;table&gt;
037 *              &lt;span wicket:id="repeater"&gt;
038 *                      &lt;tr&gt;&lt;td&gt;...&lt;/td&gt;&lt;/tr&gt;
039 *                      &lt;tr&gt;&lt;td&gt;...&lt;/td&gt;&lt;/tr&gt;
040 *              &lt;/span&gt;
041 *      &lt;/table&gt;
042 * </code>
043 * 
044 * Notice that we had to attach the repeater to a component tag - in this case a <code>span</code>,
045 * but a span is not a legal tag to nest under <code>table</code>. So we can rewrite the example as
046 * following:
047 * 
048 * <code>
049 *      &lt;table&gt;
050 *              &lt;wicket:container wicket:id="repeater"&gt;
051 *                      &lt;tr&gt;&lt;td&gt;...&lt;/td&gt;&lt;/tr&gt;
052 *                      &lt;tr&gt;&lt;td&gt;...&lt;/td&gt;&lt;/tr&gt;
053 *              &lt;/wicket:container&gt;
054 *      &lt;/table&gt;
055 * </code>
056 * 
057 * The above is valid markup because wicket namespaced tags are allowed anywhere
058 * 
059 * @author Igor Vaynberg (ivaynberg)
060 */
061public class WicketContainerResolver implements IComponentResolver
062{
063        private static final Logger log = LoggerFactory.getLogger(WicketContainerResolver.class);
064
065        private static final long serialVersionUID = 1L;
066
067        /** */
068        public static final String CONTAINER = "container";
069
070        @Override
071        public Component resolve(final MarkupContainer container, final MarkupStream markupStream,
072                final ComponentTag tag)
073        {
074                if (tag instanceof WicketTag && ((WicketTag)tag).isContainerTag())
075                {
076                        return container.get(tag.getId());
077                }
078                return null;
079        }
080}