/*

 * Copyright (c) 2005, 2013, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.swing;

import java.util.*;

import java.lang.reflect.Array;

import javax.swing.SwingUtilities;

/**

 * An abstract class to be used in the cases where we need {@code Runnable}

 * to perform  some actions on an appendable set of data.

 * The set of data might be appended after the {@code Runnable} is

 * sent for the execution. Usually such {@code Runnables} are sent to

 * the EDT.

 *

 * <p>

 * Usage example:

 *

 * <p>

 * Say we want to implement JLabel.setText(String text) which sends

 * {@code text} string to the JLabel.setTextImpl(String text) on the EDT.

 * In the event JLabel.setText is called rapidly many times off the EDT

 * we will get many updates on the EDT but only the last one is important.

 * (Every next updates overrides the previous one.)

 * We might want to implement this {@code setText} in a way that only

 * the last update is delivered.

 * <p>

 * Here is how one can do this using {@code AccumulativeRunnable}:

 * <pre>

 * AccumulativeRunnable<String> doSetTextImpl =

 * new  AccumulativeRunnable<String>() {

 *     @Override

 *     protected void run(List<String> args) {

 *         //set to the last string being passed

 *         setTextImpl(args.get(args.size() - 1));

 *     }

 * }

 * void setText(String text) {

 *     //add text and send for the execution if needed.

 *     doSetTextImpl.add(text);

 * }

 * </pre>

 *

 * <p>

 * which sends this region to the

 * handleDirtyRegions(List<Rect> regiouns) on the EDT.

 * addDirtyRegions better be accumulated before handling on the EDT.

 *

 * <p>

 * Here is how it can be implemented using AccumulativeRunnable:

 * <pre>

 * AccumulativeRunnable<Rectangle> doHandleDirtyRegions =

 *     new AccumulativeRunnable<Rectangle>() {

 *         @Override

 *         protected void run(List<Rectangle> args) {

 *             handleDirtyRegions(args);

 *         }

 *     };

 *  void addDirtyRegion(Rectangle rect) {

 *      doHandleDirtyRegions.add(rect);

 *  }

 * </pre>

 *

 * @author Igor Kushnirskiy

 *

 * @param <T> the type this {@code Runnable} accumulates

 *

 * @since 1.6

 */

public abstract class AccumulativeRunnable<T> implements Runnable {

    private List<T> arguments = null;

    /**

     * Equivalent to {@code Runnable.run} method with the

     * accumulated arguments to process.

     *

     * @param args accumulated argumets to process.

     */

    protected abstract void run(List<T> args);

    /**

     * {@inheritDoc}

     *

     * <p>

     * This implementation calls {@code run(List<T> args)} mehtod

     * with the list of accumulated arguments.

     */

    public final void run() {

        run(flush());

    }

    /**

     * appends arguments and sends this {@cod Runnable} for the

     * execution if needed.

     * <p>

     * This implementation uses {@see #submit} to send this

     * {@code Runnable} for execution.

     * @param args the arguments to accumulate

     */

    @SafeVarargs

    @SuppressWarnings("varargs") // Copying args is safe

    public final synchronized void add(T... args) {

        boolean isSubmitted = true;

        if (arguments == null) {

            isSubmitted = false;

            arguments = new ArrayList<T>();

        }

        Collections.addAll(arguments, args);

        if (!isSubmitted) {

            submit();

        }

    }

    /**

     * Sends this {@code Runnable} for the execution

     *

     * <p>

     * This method is to be executed only from {@code add} method.

     *

     * <p>

     * This implementation uses {@code SwingWorker.invokeLater}.

     */

    protected void submit() {

        SwingUtilities.invokeLater(this);

    }

    /**

     * Returns accumulated arguments and flashes the arguments storage.

     *

     * @return accumulated arguments

     */

    private final synchronized List<T> flush() {

        List<T> list = arguments;

        arguments = null;

        return list;

    }

}