/*

 * Copyright (c) 2001, 2008, 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.misc;

import java.util.ArrayList;

/**

 * This is an abstract base class which is called by java.lang.ClassLoader

 * when ClassFormatError is thrown inside defineClass().

 *

 * The purpose of this class is to allow applications (e.g. Java Plug-in)

 * to have a chance to transform the byte code from one form to another

 * if necessary.

 *

 * One application of this class is used by Java Plug-in to transform

 * malformed JDK 1.1 class file into a well-formed Java 2 class file

 * on-the-fly, so JDK 1.1 applets with malformed class file in the

 * Internet may run in Java 2 after transformation.

 *

 * @author      Stanley Man-Kit Ho

 */

public abstract class ClassFileTransformer

{

    // Singleton of ClassFileTransformer

    //

    private static ArrayList<ClassFileTransformer> transformerList

        = new ArrayList<ClassFileTransformer>();

    private static ClassFileTransformer[] transformers

        = new ClassFileTransformer[0];

    /**

     * Add the class file transformer object.

     *

     * @param t Class file transformer instance

     */

    public static void add(ClassFileTransformer t)

    {

        synchronized(transformerList)

        {

            transformerList.add(t);

            transformers = transformerList.toArray(new ClassFileTransformer[0]);

        }

    }

    /**

     * Get the array of ClassFileTransformer object.

     *

     * @return ClassFileTransformer object array

     */

    public static ClassFileTransformer[] getTransformers()

    {

        // transformers is not intended to be changed frequently,

        // so it is okay to not put synchronized block here

        // to speed up performance.

        //

        return transformers;

    }

    /**

     * Transform a byte array from one to the other.

     *

     * @param b Byte array

     * @param off Offset

     * @param len Length of byte array

     * @return Transformed byte array

     */

    public abstract byte[] transform(byte[] b, int off, int len)

                           throws ClassFormatError;

}