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package javax.faces.render;


import java.util.Iterator;
import javax.faces.FacesWrapper;
import javax.faces.context.FacesContext;


/**
 * <p><strong class="changed_modified_2_0">RenderKitFactory</strong> is a 
 * factory object that registers
 * and returns {@link RenderKit} instances.  Implementations of
 * JavaServer Faces must provide at least a default implementation of
 * {@link RenderKit}.  Advanced implementations (or external third party
 * libraries) may provide additional {@link RenderKit} implementations
 * (keyed by render kit identifiers) for performing different types of
 * rendering for the same components.</p>
 *
 * <p>There must be one {@link RenderKitFactory} instance per web
 * application that is utilizing JavaServer Faces.  This instance can be
 * acquired, in a portable manner, by calling:</p>
 * <pre>
 *   RenderKitFactory factory = (RenderKitFactory)
 *    FactoryFinder.getFactory(FactoryFinder.RENDER_KIT_FACTORY);
 * </pre>
 */

public abstract class RenderKitFactory implements FacesWrapper<RenderKitFactory> {

    public RenderKitFactory() {
    }
    
    /**
     * <p class="changed_added_2_0">If this factory has been decorated, the 
     * implementation doing the decorating may override this method to provide
     * access to the implementation being wrapped.  A default implementation
     * is provided that returns <code>null</code>.</p>
     * 
     * @since 2.0
     */

    public RenderKitFactory getWrapped() {
        return null;
    }
    
    /**
     * <p>The render kit identifier of the default {@link RenderKit} instance
     * for this JavaServer Faces implementation.</p>
     */
    public static final String HTML_BASIC_RENDER_KIT = "HTML_BASIC";


    /**
     * <p>Register the specified {@link RenderKit} instance, associated with
     * the specified <code>renderKitId</code>, to be supported by this
     * {@link RenderKitFactory}, replacing any previously registered
     * {@link RenderKit} for this identifier.</p>
     *
     * @param renderKitId Identifier of the {@link RenderKit} to register
     * @param renderKit {@link RenderKit} instance that we are registering
     *
     * @throws NullPointerException if <code>renderKitId</code> or
     *  <code>renderKit</code> is <code>null</code>
     */
    public abstract void addRenderKit(String renderKitId,
                                      RenderKit renderKit);


    /**
     * <p>Return a {@link RenderKit} instance for the specified render
     * kit identifier, possibly customized based on dynamic
     * characteristics of the specified {@link FacesContext}, if
     * non-<code>null</code>.  If there is no registered {@link
     * RenderKit} for the specified identifier, return
     * <code>null</code>.  The set of available render kit identifiers
     * is available via the <code>getRenderKitIds()</code> method.</p>
     *
     * @param context FacesContext for the request currently being
     * processed, or <code>null</code> if none is available.
     * @param renderKitId Render kit identifier of the requested
     *  {@link RenderKit} instance
     *
     * @throws IllegalArgumentException if no {@link RenderKit} instance
     *  can be returned for the specified identifier
     * @throws NullPointerException if <code>renderKitId</code> is
     * <code>null</code>
     */
    public abstract RenderKit getRenderKit(FacesContext context, 
					   String renderKitId);


    /**
     * <p>Return an <code>Iterator</code> over the set of render kit
     * identifiers registered with this factory.  This set must include
     * the value specified by <code>RenderKitFactory.HTML_BASIC_RENDER_KIT</code>.
     * </p>
     */
    public abstract Iterator<String> getRenderKitIds();


}
