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Clean-room definition of JPA APIs intended for use in developing Hibernate JPA implementation. See README.md for details

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/*
 * Copyright (c) 2008, 2009, 2011 Oracle, Inc. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.  The Eclipse Public License is available
 * at http://www.eclipse.org/legal/epl-v10.html and the Eclipse Distribution License
 * is available at http://www.eclipse.org/org/documents/edl-v10.php.
 */
package javax.persistence.spi;

import java.lang.instrument.IllegalClassFormatException;
import java.security.ProtectionDomain;

/**
 * A persistence provider supplies an instance of this
 * interface to the {@link PersistenceUnitInfo#addTransformer
 * PersistenceUnitInfo.addTransformer}
 * method. The supplied transformer instance will get
 * called to transform entity class files when they are
 * loaded or redefined. The transformation occurs before
 * the class is defined by the JVM.
 *
 * @since Java Persistence 1.0
 */
public interface ClassTransformer {

	/**
	 * Invoked when a class is being loaded or redefined.
	 * The implementation of this method may transform the
	 * supplied class file and return a new replacement class
	 * file.
	 *
	 * @param loader the defining loader of the class to be
	 * transformed, may be null if the bootstrap loader
	 * @param className the name of the class in the internal form
	 * of fully qualified class and interface names
	 * @param classBeingRedefined if this is a redefine, the
	 * class being redefined, otherwise null
	 * @param protectionDomain the protection domain of the
	 * class being defined or redefined
	 * @param classfileBuffer the input byte buffer in class
	 * file format - must not be modified
	 *
	 * @return a well-formed class file buffer (the result of
	 *         the transform), or null if no transform is performed
	 *
	 * @throws IllegalClassFormatException if the input does
	 * not represent a well-formed class file
	 */
	byte[] transform(
			ClassLoader loader,
			String className,
			Class classBeingRedefined,
			ProtectionDomain protectionDomain,
			byte[] classfileBuffer) throws IllegalClassFormatException;
}