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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.myfaces.trinidad.component;
import java.io.IOException;
import javax.faces.context.FacesContext;
/**
* Interface implemented by Components that don't render any content themselves but rather set
* up context before asking their children to render themselves. Implementing this interface
* enables Renderers for components that contain instances of the FlattenedComponents to
* visit each descendant in a flattened view of their children, recursively including any
* FlattenedComponent treating all of these descendants as direct children.
*
* A good indicator that a
* component should implement FlattenedComponent is that the component doesn't delegate to a
* Renderer, but rather renders itself.
*
* @see ComponentProcessor
* @see UIXComponent#processFlattenedChildren(FacesContext, ComponentProcessingContext, ComponentProcessor, UIComponent, Object)
* @see UIXComponent#processFlattenedChildren(FacesContext, ComponentProcessingContext, ComponentProcessor, Iterable, Object)
*/
public interface FlattenedComponent
{
/**
* Set up the component context, process all of the renderable children of this component,
* and the restore the previous context, returning true if any of the children
* were processed.
*
* The context set up and tear down to perform is identical to that which the component
* would perform when handling rendering or implementing invokeOnComponent
*
* To handle actually processing the children, the component will typically delegate to one
* of the two UIXComponent.processFlattenedChildren helpers. If the component only
* processes a single child, as UIXSwitcher does, it will call the version taking a single child
* as the argument. If it processes all of its children as UIXIterator and UIXGroup do, it
* will call getChildren and pass the List<UIComponent> to the version accepting
* an Iterable<UIComponent>.
*
* This method should only be called if FlattenedComponent.isFlatteningChildren
* returns true. If called when FlattenedComponent.isFlatteningChildren
* is false the behavior is undefined and the implementation may throw an
* IllegalStateException.
*
* This method may only be called when the FlattenedComponent is in the correct context
* to process itself.
* @param context Current FacesContext
* @param cpContext ComponentProcesingContext represetning the current child iteration state
* @param childProcessor ComponentProcessor to call for each flattened child
* @param callbackContext childProcessor-specific context to be passed on each call to the
* childProcessor
* @return true if this FlattenedComponent actually processed any children
* @throws IOException if an error occurs while processing children
* @throws IllegalStateException if called when isFlatteningChildren() is
* false.
* @see UIXComponent#processFlattenedChildren(FacesContext, ComponentProcessingContext, ComponentProcessor, UIComponent, Object)
* @see UIXComponent#processFlattenedChildren(FacesContext, ComponentProcessingContext, ComponentProcessor, Iterable, Object)
* @see #isFlatteningChildren
*/
public boolean processFlattenedChildren(
FacesContext context,
ComponentProcessingContext cpContext,
ComponentProcessor childProcessor,
S callbackContext) throws IOException;
/**
* Returns true if this FlattenedComponent is currently flattening its children. This
* allows a FlattenedComponent instance to flatten or not flatten its children as it sees fit.
*
* It is illegal to call processFlattenedChildren on a FlattenedComponent that
* has returned false from isFlatteningChildren.
* @param context FacesContext
* @return true if this FlattenedComponent is currently flattening its children
* @see #processFlattenedChildren
*/
public boolean isFlatteningChildren(FacesContext context);
}