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Wicket is a Java web application framework that takes simplicity, separation of concerns and ease of development to a whole new level. Wicket pages can be mocked up, previewed and later revised using standard WYSIWYG HTML design tools. Dynamic content processing and form handling is all handled in Java code using a first-class component model backed by POJO data beans that can easily be persisted using your favorite technology.

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/*
 * 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.head.internal;

import java.util.HashSet;
import java.util.Set;

import org.apache.wicket.markup.head.HeaderItem;
import org.apache.wicket.markup.head.IHeaderResponse;
import org.apache.wicket.request.Response;
import org.apache.wicket.response.NullResponse;


/**
 * Default implementation of the {@link org.apache.wicket.markup.head.IHeaderResponse} interface.
 * 
 * @author Matej Knopp
 * @author Igor Vaynberg (ivaynberg)
 */
public abstract class HeaderResponse implements IHeaderResponse
{
	private final Set rendered = new HashSet();

	private boolean closed;

	/**
	 * @see org.apache.wicket.markup.head.IHeaderResponse#markRendered(java.lang.Object)
	 */
	@Override
	public void markRendered(Object object)
	{
		rendered.add(object);
	}

	@Override
	public void render(HeaderItem item)
	{
		if (!closed && !wasItemRendered(item))
		{
			item.render(getResponse());
			markItemRendered(item);
		}
	}

	protected boolean wasItemRendered(HeaderItem item)
	{
		for (Object curToken : item.getRenderTokens())
		{
			if (wasRendered(curToken))
				return true;
		}
		return false;
	}

	protected void markItemRendered(HeaderItem item)
	{
		for (Object curToken : item.getRenderTokens())
		{
			markRendered(curToken);
		}
	}

	/**
	 * @see org.apache.wicket.markup.head.IHeaderResponse#wasRendered(java.lang.Object)
	 */
	@Override
	public boolean wasRendered(Object object)
	{
		return rendered.contains(object);
	}

	/**
	 * @see org.apache.wicket.markup.head.IHeaderResponse#close()
	 */
	@Override
	public void close()
	{
		closed = true;
	}

	/**
	 * @see org.apache.wicket.markup.head.IHeaderResponse#getResponse()
	 */
	@Override
	public final Response getResponse()
	{
		return closed ? NullResponse.getInstance() : getRealResponse();
	}

	/**
	 * @see org.apache.wicket.markup.head.IHeaderResponse#isClosed()
	 */
	@Override
	public boolean isClosed()
	{
		return closed;
	}

	/**
	 * Once the HeaderResponse is closed, no output may be written to it anymore. To enforce that,
	 * the {@link #getResponse()} is defined final in this class and will return a NullResponse
	 * instance once closed or otherwise the Response provided by this method.
	 * 
	 * @return Response
	 */
	protected abstract Response getRealResponse();
}
 















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