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The public API classes of the Apache MyFaces CORE JSF-2.2 project
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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 jakarta.faces.render;

import java.io.IOException;

import jakarta.faces.component.UIComponent;
import jakarta.faces.context.FacesContext;
import jakarta.faces.convert.ConverterException;
import org.apache.myfaces.core.api.shared.lang.Assert;

/**
 * see Javadoc of Faces Specification
 */
public abstract class Renderer
{
    /**
     * @since 2.2
     */
    public static final String PASSTHROUGH_RENDERER_LOCALNAME_KEY = "elementName";
    
    public void decode(FacesContext context, T component)
    {
        Assert.notNull(context, "context");
        Assert.notNull(component, "component");
    }

    /**
     * @throws IOException if an input/output error occurs while rendering 
     */
    public void encodeBegin(FacesContext context, T component) throws IOException
    {
        Assert.notNull(context, "context");
        Assert.notNull(component, "component");
    }

    /**
     * Render all children if there are any.
     * 
     * Note: this will only be called if getRendersChildren() returns true. A component which has a renderer with
     * getRendersChildren() set to true will typically contain the rendering logic for its children in this method.
     * 
     * @param context
     * @param component
     * @throws IOException
     */
    public void encodeChildren(FacesContext context, T component) throws IOException
    {
        Assert.notNull(context, "context");
        Assert.notNull(component, "component");

        if (component.getChildCount() > 0)
        {
            for (int i = 0, childCount = component.getChildCount(); i < childCount; i++)
            {
                UIComponent child = component.getChildren().get(i);
                if (!child.isRendered())
                {
                    continue;
                }

                child.encodeAll(context);
            }
        }
    }

    /**
     * @throws IOException if an input/output error occurs while rendering 
     */
    public void encodeEnd(FacesContext context, T component) throws IOException
    {
        Assert.notNull(context, "context");
        Assert.notNull(component, "component");
    }

    public String convertClientId(FacesContext context, String clientId)
    {
        Assert.notNull(context, "context");
        Assert.notNull(clientId, "clientId");
        return clientId;
    }

    /**
     * Switch for deciding who renders the children.
     * 
     * @return true - if the component takes care of rendering its children. In this case, encodeChildren() ought
     *         to be called by the rendering controller (e.g., the rendering controller could be the method encodeAll()
     *         in UIComponent). In the method encodeChildren(), the component should therefore provide all children
     *         encode logic. 
 false - if the component does not take care of rendering its children. 
     *         In this
     *         case, encodeChildren() should not be called by the rendering controller. Instead, the children-list
     *         should be retrieved and the children should directly be rendered by the rendering controller one by one.
     */
    public boolean getRendersChildren()
    {
        return false;
    }

    public Object getConvertedValue(FacesContext context, T component, Object submittedValue)
            throws ConverterException
    {
        Assert.notNull(context, "context");
        Assert.notNull(component, "component");
        return submittedValue;
    }

}