wicketremovetaghandler.java

Wicket一个开发Java Web应用程序框架。它使得开发web应用程序变得容易而轻松。 Wicket利用一个POJO data beans组件使得它可以与任何持久层技术相结合。

/*
 * 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.wicket.markup.parser.filter;

import java.text.ParseException;

import org.apache.wicket.markup.ComponentTag;
import org.apache.wicket.markup.MarkupElement;
import org.apache.wicket.markup.WicketTag;
import org.apache.wicket.markup.parser.AbstractMarkupFilter;


/**
 * This is a markup inline filter. It identifies preview regions useful for HTML designers to design
 * the page. But they must be removed prior to sending the markup to the client. Preview regions are
 * enclosed by <wicket:remove> tags.
 * 
 * @author Juergen Donnerstag
 */
public final class WicketRemoveTagHandler extends AbstractMarkupFilter
{
	static
	{
		// register "wicket:remove"
		WicketTagIdentifier.registerWellKnownTagName("remove");
	}

	/**
	 * Construct.
	 */
	public WicketRemoveTagHandler()
	{
	}

	/**
	 * Removes preview regions enclosed by <wicket:remove> tags. Note that for obvious
	 * reasons, nested components are not allowed.
	 * 
	 * @see org.apache.wicket.markup.parser.IMarkupFilter#nextTag()
	 * @return The next tag to be processed. Null, if not more tags are available
	 */
	public final MarkupElement nextTag() throws ParseException
	{
		// Get the next tag from the next MarkupFilter in the chain
		// If null, no more tags are available
		final ComponentTag openTag = (ComponentTag)getParent().nextTag();
		if (openTag == null)
		{
			return openTag;
		}

		// If it is not a remove tag, than we are finished
		if (!(openTag instanceof WicketTag) || !((WicketTag)openTag).isRemoveTag())
		{
			return openTag;
		}

		// remove tag must not be open-close tags
		if (openTag.isOpenClose())
		{
			throw new ParseException("Wicket remove tag must not be an open-close tag: " +
					openTag.toUserDebugString(), openTag.getPos());
		}

		// Find the corresponding close tag and remove all tags in between
		ComponentTag closeTag;
		while (null != (closeTag = (ComponentTag)getParent().nextTag()))
		{
			// No Wicket component tags are allowed within the preview region.
			// Wicket components will a component name assigned.
			if (closeTag.getId() == null)
			{
				continue;
			}

			// The first Wicket component following the preview region open
			// tag, must be it's corresponding close tag.
			if (closeTag.closes(openTag))
			{
				// The tag (from open to close) should be ignored by
				// MarkupParser and not be added to the Markup.
				openTag.setIgnore(true);
				return openTag;
			}

			throw new ParseException(
					"Markup remove regions must not contain Wicket component tags. tag: " +
							closeTag.toUserDebugString(), closeTag.getPos());
		}

		throw new ParseException("Did not find close tag for markup remove region. Open tag: " +
				openTag.toUserDebugString(), openTag.getPos());
	}
}