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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.component.visit;

import java.util.AbstractCollection;
import java.util.Collection;
import java.util.Iterator;
import java.util.Set;

import javax.faces.FactoryFinder;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;

/**
 *
 * 

A context object that is used to hold * state relating to performing a component tree visit.

* *
* *

Component tree visits are initiated by calling {@link * UIComponent#visitTree}, at which point both a * {@link VisitContext} and a {@link VisitCallback} must be provided.

*
* * @see UIComponent#visitTree UIComponent.visitTree() * @see VisitCallback * * @since 2.0 */ abstract public class VisitContext { // Design notes: The VisitContext contract could be defined // as an interface. However, there is the potential that we // may need to add new methods in the future, so leaving as // an abstract class in order to have room to grow. // // Since we are an abstract class rather than an interface, // we could provide implementations of of some of the simpler // methods (eg. getFacesContext() and getHints()) to avoid // duplicating this code in VisitContext implementations. // However, doing so would mean that "wrapping" VisitContext // implementations would be forced to pick up such implementations, // so going with a pure contract (no implementation). /** *

This unmodifiable Collection is * returned by getIdsToVisit() and * getSubtreeIdsToVisit() in cases where all ids should * be visited.

*

To simplify logic for * visitTree() implementations, this Collection always * returns false for isEmpty. All other * methods throw UnsupportedOperationException.

* * @since 2.0 */ // Note: We cannot use Collections.emptyList() as that returns // a shared instance - we want to unique instance to allow for // identity tests. static public final Collection ALL_IDS = new AbstractCollection() { @Override public Iterator iterator() { throw new UnsupportedOperationException( "VisitContext.ALL_IDS does not support this operation"); } @Override public int size() { throw new UnsupportedOperationException( "VisitContext.ALL_IDS does not support this operation"); } @Override public boolean isEmpty() { return false; } }; /** *

Returns the FacesContext for the * current request.

* * @return the FacesContext. * * @since 2.0 */ abstract public FacesContext getFacesContext(); /** *

Returns the ids of the components * to visit.

*

In the case of a full tree visit, * this method returns the ALL_IDS collection. Otherwise, if a * partial visit is beign performed, returns a modifiable collection * containing the client ids of the components that should be * visited.

* * @return the ids of the components to visit * */ abstract public Collection getIdsToVisit(); /** *

Given a {@link * javax.faces.component.NamingContainer} component, returns the * client ids of any components underneath the NamingContainer that * should be visited.

*
*

This method is called by NamingContainer visitTree() * implementations to determine whether the NamingContainer contains * components to be visited. In the case where no such components * exist, the NamingContainer can short-circuit the tree visit and * avoid descending into child subtrees.

*

In addition, iterating components such as UIData may be able * to use the returned ids to determine which iterated states * (ie. rows) need to be visited. This allows the visit traversal * to be contstrained such only those rows that contain visit * targets need to be traversed.

*
* @param component a NamingContainer component * @return an unmodifiable Collection containing the client ids of * any components underneath the NamingContainer that are known to be * targets of the tree visit. If no such components exist, returns * an empty Collection. If all components underneath the * NamingContainer should be visited, returns the * {@code VisitContext.ALL_IDS} collection. * @throws IllegalArgumentException if {@code component} is not * an instance of NamingContainer */ abstract public Collection getSubtreeIdsToVisit(UIComponent component); /** *

Called by {@link UIComponent#visitTree UIComponent.visitTree()} * to visit a single component.

* * @param component the component to visit * @param callback the VisitCallback to call * @return a VisitResult value that indicates whether to continue * visiting the component's subtree, skip visiting the component's * subtree or abort the visit altogether. */ abstract public VisitResult invokeVisitCallback(UIComponent component, VisitCallback callback); /** *

Returns hints that influence the behavior of the tree visit.

* *

Interested parties, such as * {@link UIComponent#visitTree UIComponent.visitTree()} implementations, * may check to see whether a particular hint is present by calling * {@code VisitContext.getHints().contains()}, passing in one of the * hints defined by {@link VisitHint}. * * @return a non-empty, unmodifiable collection of VisitHints */ abstract public Set getHints(); /** *

Returns a VisitContext instance that is initialized with the * specified ids and hintsfor use with {@link * UIComponent#visitTree}.

* * @param context the FacesContext for the current request * @param ids the client ids of the components to visit. If null, * all components will be visited. * @param hints the VisitHints to apply to the visit. If * null, no hints are applied. * @return a VisitContext instance that is initialized with the * specified ids and hints. */ public static VisitContext createVisitContext(FacesContext context, Collection ids, Set hints) { VisitContextFactory factory = (VisitContextFactory) FactoryFinder.getFactory(FactoryFinder.VISIT_CONTEXT_FACTORY); return factory.getVisitContext(context, ids, hints); } /** *

Creates a VisitContext instance for use with * {@link UIComponent#visitTree UIComponent.visitTree()}. * This method can be used to obtain a VisitContext instance * when all components should be visited with the default * visit hints.

* @param context the FacesContext for the current request * @return a VisitContext instance */ public static VisitContext createVisitContext(FacesContext context) { return createVisitContext(context, null, null); } }




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