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EE4J Compatible Implementation for Jakarta Faces API
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/*
 * Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package javax.faces.context;

import java.io.IOException;
import java.util.Map;

import javax.faces.component.NamingContainer;
import javax.faces.component.UIViewRoot;
import javax.faces.render.ResponseStateManager;

/**
 * PartialResponseWriter
 * decorates an existing ResponseWriter to support the
 * generation of a partial response suitable for Ajax operations.
 * In addition to the markup generation methods inherited from
 * javax.faces.context.ResponseWriter, this class provides
 * methods for constructing the standard partial response elements.
 *
 * @since 2.0
 */
public class PartialResponseWriter extends ResponseWriterWrapper {
    // True when we need to close a changes tag
    //
    private boolean inChanges = false;

    // True when we need to close a before insert tag
    //
    private boolean inInsertBefore = false;

    // True when we need to close afer insert tag
    //
    private boolean inInsertAfter = false;
    
    // True when we need to close an update tag
    //
    private boolean inUpdate = false;

    /**
     * Reserved ID value to indicate
     * entire ViewRoot.
     *
     * @since 2.0
     */
    public static final String RENDER_ALL_MARKER = "javax.faces.ViewRoot";

    /**
     * Reserved ID value to indicate
     * serialized ViewState.
     *
     * @since 2.0
     */
    public static final String VIEW_STATE_MARKER = ResponseStateManager.VIEW_STATE_PARAM;

    /**
     * Create a PartialResponseWriter.
     *
     * @param writer The writer to wrap.
     * @since 2.0
     */
    public PartialResponseWriter(ResponseWriter writer) {
        super(writer);
    }

    /**
     * Write the start of a partial response.
     * If {@link UIViewRoot} is an instance of
     * {@link NamingContainer}, then write
     * {@link UIViewRoot#getContainerClientId(FacesContext)} as value of the
     * id attribute of the root element.
     *
     * @throws IOException if an input/output error occurs
     * @since 2.0
     */
    @Override
    public void startDocument() throws IOException {
        ResponseWriter writer = getWrapped();
        String encoding = writer.getCharacterEncoding( );
        if( encoding == null ) {
            encoding = "utf-8";
        }
        writer.writePreamble("\n");
        writer.startElement("partial-response", null);
        FacesContext ctx = FacesContext.getCurrentInstance();
        if (null != ctx && ctx.getViewRoot() instanceof NamingContainer) {
            String id = ctx.getViewRoot().getContainerClientId(ctx);
            writer.writeAttribute("id", id, "id");
        }
    }

    /**
     * Write the end of a partial response.
     *
     * @throws IOException if an input/output error occurs
     * @since 2.0
     */
    @Override
    public void endDocument() throws IOException {
        endChangesIfNecessary();
        ResponseWriter writer = getWrapped();
        /*
         * Because during a