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 * Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package javax.swing;

import java.awt.Component;

import java.awt.Container;

import java.awt.Window;

import java.util.*;

import java.awt.FocusTraversalPolicy;

import sun.util.logging.PlatformLogger;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import sun.security.action.GetPropertyAction;

import java.security.AccessController;

import java.security.PrivilegedAction;

/**

 * A FocusTraversalPolicy that determines traversal order by sorting the

 * Components of a focus traversal cycle based on a given Comparator. Portions

 * of the Component hierarchy that are not visible and displayable will not be

 * included.

 * <p>

 * By default, SortingFocusTraversalPolicy implicitly transfers focus down-

 * cycle. That is, during normal focus traversal, the Component

 * traversed after a focus cycle root will be the focus-cycle-root's default

 * Component to focus. This behavior can be disabled using the

 * <code>setImplicitDownCycleTraversal</code> method.

 * <p>

 * By default, methods of this class with return a Component only if it is

 * visible, displayable, enabled, and focusable. Subclasses can modify this

 * behavior by overriding the <code>accept</code> method.

 * <p>

 * This policy takes into account <a

 * href="../../java/awt/doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus traversal

 * policy providers</a>.  When searching for first/last/next/previous Component,

 * if a focus traversal policy provider is encountered, its focus traversal

 * policy is used to perform the search operation.

 *

 * @author David Mendenhall

 *

 * @see java.util.Comparator

 * @since 1.4

 */

public class SortingFocusTraversalPolicy

    extends InternalFrameFocusTraversalPolicy

{

    private Comparator<? super Component> comparator;

    private boolean implicitDownCycleTraversal = true;

    private PlatformLogger log = PlatformLogger.getLogger("javax.swing.SortingFocusTraversalPolicy");

    /**

     * Used by getComponentAfter and getComponentBefore for efficiency. In

     * order to maintain compliance with the specification of

     * FocusTraversalPolicy, if traversal wraps, we should invoke

     * getFirstComponent or getLastComponent. These methods may be overriden in

     * subclasses to behave in a non-generic way. However, in the generic case,

     * these methods will simply return the first or last Components of the

     * sorted list, respectively. Since getComponentAfter and

     * getComponentBefore have already built the sorted list before determining

     * that they need to invoke getFirstComponent or getLastComponent, the

     * sorted list should be reused if possible.

     */

    transient private Container cachedRoot;

    transient private List<Component> cachedCycle;

    // Delegate our fitness test to ContainerOrder so that we only have to

    // code the algorithm once.

    private static final SwingContainerOrderFocusTraversalPolicy

        fitnessTestPolicy = new SwingContainerOrderFocusTraversalPolicy();

    final private int FORWARD_TRAVERSAL = 0;

    final private int BACKWARD_TRAVERSAL = 1;

    /*

     * When true (by default), the legacy merge-sort algo is used to sort an FTP cycle.

     * When false, the default (tim-sort) algo is used, which may lead to an exception.

     * See: JDK-8048887

     */

    private static final boolean legacySortingFTPEnabled;

    private static final Method legacyMergeSortMethod;

    static {

        legacySortingFTPEnabled = "true".equals(AccessController.doPrivileged(

            new GetPropertyAction("swing.legacySortingFTPEnabled", "true")));

        legacyMergeSortMethod = legacySortingFTPEnabled ?

            AccessController.doPrivileged(new PrivilegedAction<Method>() {

                public Method run() {

                    try {

                        Method m = java.util.Arrays.class.getDeclaredMethod("legacyMergeSort",

                                                                            new Class<?>[]{Object[].class,

                                                                                    Comparator.class});

                        m.setAccessible(true);

                        return m;

                    } catch (NoSuchMethodException e) {

                        // using default sorting algo

                        return null;

                    }

                }

            }) :

            null;

    }

    /**

     * Constructs a SortingFocusTraversalPolicy without a Comparator.

     * Subclasses must set the Comparator using <code>setComparator</code>

     * before installing this FocusTraversalPolicy on a focus cycle root or

     * KeyboardFocusManager.

     */

    protected SortingFocusTraversalPolicy() {

    }

    /**

     * Constructs a SortingFocusTraversalPolicy with the specified Comparator.

     *

     * @param comparator the {@code Comparator} to sort by

     */

    public SortingFocusTraversalPolicy(Comparator<? super Component> comparator) {

        this.comparator = comparator;

    }

    private List<Component> getFocusTraversalCycle(Container aContainer) {

        List<Component> cycle = new ArrayList<Component>();

        enumerateAndSortCycle(aContainer, cycle);

        return cycle;

    }

    private int getComponentIndex(List<Component> cycle, Component aComponent) {

        int index;

        try {

            index = Collections.binarySearch(cycle, aComponent, comparator);

        } catch (ClassCastException e) {

            if (log.isLoggable(PlatformLogger.Level.FINE)) {

                log.fine("### During the binary search for " + aComponent + " the exception occurred: ", e);

            }

            return -1;

        }

        if (index < 0) {

            // Fix for 5070991.

            // A workaround for a transitivity problem caused by ROW_TOLERANCE,

            // because of that the component may be missed in the binary search.

            // Try to search it again directly.

            index = cycle.indexOf(aComponent);

        }

        return index;

    }

    private void enumerateAndSortCycle(Container focusCycleRoot, List<Component> cycle) {

        if (focusCycleRoot.isShowing()) {

            enumerateCycle(focusCycleRoot, cycle);

            if (!legacySortingFTPEnabled ||

                !legacySort(cycle, comparator))

            {

                Collections.sort(cycle, comparator);

            }

        }

    }

    private boolean legacySort(List<Component> l, Comparator<? super Component> c) {

        if (legacyMergeSortMethod == null)

            return false;

        Object[] a = l.toArray();

        try {

            legacyMergeSortMethod.invoke(null, a, c);

        } catch (IllegalAccessException | InvocationTargetException e) {

            return false;

        }

        ListIterator<Component> i = l.listIterator();

        for (Object e : a) {

            i.next();

            i.set((Component)e);

        }

        return true;

    }

    @SuppressWarnings("deprecation")

    private void enumerateCycle(Container container, List<Component> cycle) {

        if (!(container.isVisible() && container.isDisplayable())) {

            return;

        }

        cycle.add(container);

        Component[] components = container.getComponents();

        for (Component comp : components) {

            if (comp instanceof Container) {

                Container cont = (Container)comp;

                if (!cont.isFocusCycleRoot() &&

                    !cont.isFocusTraversalPolicyProvider() &&

                    !((cont instanceof JComponent) && ((JComponent)cont).isManagingFocus()))

                {

                    enumerateCycle(cont, cycle);

                    continue;

                }

            }

            cycle.add(comp);

        }

    }

    Container getTopmostProvider(Container focusCycleRoot, Component aComponent) {

        Container aCont = aComponent.getParent();

        Container ftp = null;

        while (aCont  != focusCycleRoot && aCont != null) {

            if (aCont.isFocusTraversalPolicyProvider()) {

                ftp = aCont;

            }

            aCont = aCont.getParent();

        }

        if (aCont == null) {

            return null;

        }

        return ftp;

    }

    /*

     * Checks if a new focus cycle takes place and returns a Component to traverse focus to.

     * @param comp a possible focus cycle root or policy provider

     * @param traversalDirection the direction of the traversal

     * @return a Component to traverse focus to if {@code comp} is a root or provider

     *         and implicit down-cycle is set, otherwise {@code null}

     */

    private Component getComponentDownCycle(Component comp, int traversalDirection) {

        Component retComp = null;

        if (comp instanceof Container) {

            Container cont = (Container)comp;

            if (cont.isFocusCycleRoot()) {

                if (getImplicitDownCycleTraversal()) {

                    retComp = cont.getFocusTraversalPolicy().getDefaultComponent(cont);

                    if (retComp != null && log.isLoggable(PlatformLogger.Level.FINE)) {

                        log.fine("### Transfered focus down-cycle to " + retComp +

                                 " in the focus cycle root " + cont);

                    }

                } else {

                    return null;

                }

            } else if (cont.isFocusTraversalPolicyProvider()) {

                retComp = (traversalDirection == FORWARD_TRAVERSAL ?

                           cont.getFocusTraversalPolicy().getDefaultComponent(cont) :

                           cont.getFocusTraversalPolicy().getLastComponent(cont));

                if (retComp != null && log.isLoggable(PlatformLogger.Level.FINE)) {

                    log.fine("### Transfered focus to " + retComp + " in the FTP provider " + cont);

                }

            }

        }

        return retComp;

    }

    /**

     * Returns the Component that should receive the focus after aComponent.

     * aContainer must be a focus cycle root of aComponent or a focus traversal policy provider.

     * <p>

     * By default, SortingFocusTraversalPolicy implicitly transfers focus down-

     * cycle. That is, during normal focus traversal, the Component

     * traversed after a focus cycle root will be the focus-cycle-root's

     * default Component to focus. This behavior can be disabled using the

     * <code>setImplicitDownCycleTraversal</code> method.

     * <p>

     * If aContainer is <a href="../../java/awt/doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus

     * traversal policy provider</a>, the focus is always transferred down-cycle.

     *

     * @param aContainer a focus cycle root of aComponent or a focus traversal policy provider

     * @param aComponent a (possibly indirect) child of aContainer, or

     *        aContainer itself

     * @return the Component that should receive the focus after aComponent, or

     *         null if no suitable Component can be found

     * @throws IllegalArgumentException if aContainer is not a focus cycle

     *         root of aComponent or a focus traversal policy provider, or if either aContainer or

     *         aComponent is null

     */

    public Component getComponentAfter(Container aContainer, Component aComponent) {

        if (log.isLoggable(PlatformLogger.Level.FINE)) {

            log.fine("### Searching in " + aContainer + " for component after " + aComponent);

        }

        if (aContainer == null || aComponent == null) {

            throw new IllegalArgumentException("aContainer and aComponent cannot be null");

        }

        if (!aContainer.isFocusTraversalPolicyProvider() && !aContainer.isFocusCycleRoot()) {

            throw new IllegalArgumentException("aContainer should be focus cycle root or focus traversal policy provider");

        } else if (aContainer.isFocusCycleRoot() && !aComponent.isFocusCycleRoot(aContainer)) {

            throw new IllegalArgumentException("aContainer is not a focus cycle root of aComponent");

        }

        // Before all the ckecks below we first see if it's an FTP provider or a focus cycle root.

        // If it's the case just go down cycle (if it's set to "implicit").

        Component comp = getComponentDownCycle(aComponent, FORWARD_TRAVERSAL);

        if (comp != null) {

            return comp;

        }

        // See if the component is inside of policy provider.

        Container provider = getTopmostProvider(aContainer, aComponent);

        if (provider != null) {

            if (log.isLoggable(PlatformLogger.Level.FINE)) {

                log.fine("### Asking FTP " + provider + " for component after " + aComponent);

            }

            // FTP knows how to find component after the given. We don't.

            FocusTraversalPolicy policy = provider.getFocusTraversalPolicy();

            Component afterComp = policy.getComponentAfter(provider, aComponent);

            // Null result means that we overstepped the limit of the FTP's cycle.

            // In that case we must quit the cycle, otherwise return the component found.

            if (afterComp != null) {

                if (log.isLoggable(PlatformLogger.Level.FINE)) {

                    log.fine("### FTP returned " + afterComp);

                }

                return afterComp;

            }

            aComponent = provider;

        }

        List<Component> cycle = getFocusTraversalCycle(aContainer);

        if (log.isLoggable(PlatformLogger.Level.FINE)) {

            log.fine("### Cycle is " + cycle + ", component is " + aComponent);

        }

        int index = getComponentIndex(cycle, aComponent);

        if (index < 0) {

            if (log.isLoggable(PlatformLogger.Level.FINE)) {

                log.fine("### Didn't find component " + aComponent + " in a cycle " + aContainer);

            }

            return getFirstComponent(aContainer);

        }

        for (index++; index < cycle.size(); index++) {

            comp = cycle.get(index);

            if (accept(comp)) {

                return comp;

            } else if ((comp = getComponentDownCycle(comp, FORWARD_TRAVERSAL)) != null) {

                return comp;

            }

        }

        if (aContainer.isFocusCycleRoot()) {

            this.cachedRoot = aContainer;

            this.cachedCycle = cycle;

            comp = getFirstComponent(aContainer);

            this.cachedRoot = null;

            this.cachedCycle = null;

            return comp;

        }

        return null;

    }

    /**

     * Returns the Component that should receive the focus before aComponent.

     * aContainer must be a focus cycle root of aComponent or a focus traversal policy provider.

     * <p>

     * By default, SortingFocusTraversalPolicy implicitly transfers focus down-

     * cycle. That is, during normal focus traversal, the Component

     * traversed after a focus cycle root will be the focus-cycle-root's

     * default Component to focus. This behavior can be disabled using the

     * <code>setImplicitDownCycleTraversal</code> method.

     * <p>

     * If aContainer is <a href="../../java/awt/doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus

     * traversal policy provider</a>, the focus is always transferred down-cycle.

     *

     * @param aContainer a focus cycle root of aComponent or a focus traversal policy provider

     * @param aComponent a (possibly indirect) child of aContainer, or

     *        aContainer itself

     * @return the Component that should receive the focus before aComponent,

     *         or null if no suitable Component can be found

     * @throws IllegalArgumentException if aContainer is not a focus cycle

     *         root of aComponent or a focus traversal policy provider, or if either aContainer or

     *         aComponent is null

     */

    public Component getComponentBefore(Container aContainer, Component aComponent) {

        if (aContainer == null || aComponent == null) {

            throw new IllegalArgumentException("aContainer and aComponent cannot be null");

        }

        if (!aContainer.isFocusTraversalPolicyProvider() && !aContainer.isFocusCycleRoot()) {

            throw new IllegalArgumentException("aContainer should be focus cycle root or focus traversal policy provider");

        } else if (aContainer.isFocusCycleRoot() && !aComponent.isFocusCycleRoot(aContainer)) {

            throw new IllegalArgumentException("aContainer is not a focus cycle root of aComponent");

        }

        // See if the component is inside of policy provider.

        Container provider = getTopmostProvider(aContainer, aComponent);

        if (provider != null) {

            if (log.isLoggable(PlatformLogger.Level.FINE)) {

                log.fine("### Asking FTP " + provider + " for component after " + aComponent);

            }

            // FTP knows how to find component after the given. We don't.

            FocusTraversalPolicy policy = provider.getFocusTraversalPolicy();

            Component beforeComp = policy.getComponentBefore(provider, aComponent);

            // Null result means that we overstepped the limit of the FTP's cycle.

            // In that case we must quit the cycle, otherwise return the component found.

            if (beforeComp != null) {

                if (log.isLoggable(PlatformLogger.Level.FINE)) {

                    log.fine("### FTP returned " + beforeComp);

                }

                return beforeComp;

            }

            aComponent = provider;

            // If the provider is traversable it's returned.

            if (accept(aComponent)) {

                return aComponent;

            }

        }

        List<Component> cycle = getFocusTraversalCycle(aContainer);

        if (log.isLoggable(PlatformLogger.Level.FINE)) {

            log.fine("### Cycle is " + cycle + ", component is " + aComponent);

        }

        int index = getComponentIndex(cycle, aComponent);

        if (index < 0) {

            if (log.isLoggable(PlatformLogger.Level.FINE)) {

                log.fine("### Didn't find component " + aComponent + " in a cycle " + aContainer);

            }

            return getLastComponent(aContainer);

        }

        Component comp;

        Component tryComp;

        for (index--; index>=0; index--) {

            comp = cycle.get(index);

            if (comp != aContainer && (tryComp = getComponentDownCycle(comp, BACKWARD_TRAVERSAL)) != null) {

                return tryComp;

            } else if (accept(comp)) {

                return comp;

            }

        }

        if (aContainer.isFocusCycleRoot()) {

            this.cachedRoot = aContainer;

            this.cachedCycle = cycle;

            comp = getLastComponent(aContainer);

            this.cachedRoot = null;

            this.cachedCycle = null;

            return comp;

        }

        return null;

    }

    /**

     * Returns the first Component in the traversal cycle. This method is used

     * to determine the next Component to focus when traversal wraps in the

     * forward direction.

     *

     * @param aContainer a focus cycle root of aComponent or a focus traversal policy provider whose

     *        first Component is to be returned

     * @return the first Component in the traversal cycle of aContainer,

     *         or null if no suitable Component can be found

     * @throws IllegalArgumentException if aContainer is null

     */

    public Component getFirstComponent(Container aContainer) {

        List<Component> cycle;

        if (log.isLoggable(PlatformLogger.Level.FINE)) {

            log.fine("### Getting first component in " + aContainer);

        }

        if (aContainer == null) {

            throw new IllegalArgumentException("aContainer cannot be null");

        }

        if (this.cachedRoot == aContainer) {

            cycle = this.cachedCycle;

        } else {

            cycle = getFocusTraversalCycle(aContainer);

        }

        if (cycle.size() == 0) {

            if (log.isLoggable(PlatformLogger.Level.FINE)) {

                log.fine("### Cycle is empty");

            }

            return null;

        }

        if (log.isLoggable(PlatformLogger.Level.FINE)) {

            log.fine("### Cycle is " + cycle);

        }