org.apache.wicket.markup.head.internal.HeaderResponse.java Source code

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Here is the source code for org.apache.wicket.markup.head.internal.HeaderResponse.java

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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<Object> rendered = new HashSet<Object>();

    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();
}