/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
 * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
 */
package org.hibernate.bytecode.spi;

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

/**
 * A persistence provider provides an instance of this interface
 * to the PersistenceUnitInfo.addTransformer method.
 * The supplied transformer instance will get called to transform
 * entity class files when they are loaded and redefined.  The transformation
 * occurs before the class is defined by the JVM
 *
 * @author <a href="mailto:bill@jboss.org">Bill Burke</a>
 * @author Emmanuel Bernard
 */
public interface ClassTransformer extends javax.persistence.spi.ClassTransformer {
	/**
	 * Invoked when a class is being loaded or redefined to add hooks for persistence bytecode manipulation.
	 *
	 * @param loader the defining class loaderof the class being transformed.  It may be null if using bootstrap loader
	 * @param className The name of the class being transformed
	 * @param classBeingRedefined If an already loaded class is being redefined, then pass this as a parameter
	 * @param protectionDomain ProtectionDomain of the class being (re)-defined
	 * @param classfileBuffer The input byte buffer in class file format
	 * @return A well-formed class file that can be loaded
	 */
	@Override
	public byte[] transform(
			ClassLoader loader,
			String className,
			Class<?> classBeingRedefined,
			ProtectionDomain protectionDomain,
			byte[] classfileBuffer) throws IllegalClassFormatException;
}
