/*
 * Copyright IBM Corp. and others 1991
 *
 * This program and the accompanying materials are made available under
 * the terms of the Eclipse Public License 2.0 which accompanies this
 * distribution and is available at https://www.eclipse.org/legal/epl-2.0/
 * or the Apache License, Version 2.0 which accompanies this distribution and
 * is available at https://www.apache.org/licenses/LICENSE-2.0.
 *
 * This Source Code may also be made available under the following
 * Secondary Licenses when the conditions for such availability set
 * forth in the Eclipse Public License, v. 2.0 are satisfied: GNU
 * General Public License, version 2 with the GNU Classpath
 * Exception [1] and GNU General Public License, version 2 with the
 * OpenJDK Assembly Exception [2].
 *
 * [1] https://www.gnu.org/software/classpath/license.html
 * [2] https://openjdk.org/legal/assembly-exception.html
 *
 * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0 OR GPL-2.0-only WITH OpenJDK-assembly-exception-1.0
 */
package com.ibm.j9ddr.vm29.j9.gc;

import static com.ibm.j9ddr.vm29.events.EventManager.raiseCorruptDataEvent;

import com.ibm.j9ddr.CorruptDataException;
import com.ibm.j9ddr.vm29.pointer.UDATAPointer;
import com.ibm.j9ddr.vm29.pointer.VoidPointer;
import com.ibm.j9ddr.vm29.pointer.generated.J9ObjectPointer;
import com.ibm.j9ddr.vm29.pointer.generated.MM_SublistPuddlePointer;

abstract class GCObjectListSlotIterator extends MMSublistSlotIterator
{
	protected GCObjectListSlotIterator(MM_SublistPuddlePointer sublistPuddle) throws CorruptDataException
	{
		super(sublistPuddle);
	}

	public J9ObjectPointer next()
	{
		/* Note: the superclass implementation returns slots, whereas we want the contents.
		 * This makes the name of this class (and its subclasses) a bit a misnomer. 
		 */
		try {
			UDATAPointer next = UDATAPointer.cast(super.next());
			if(next.notNull()) {
				return J9ObjectPointer.cast(next.at(0));
			} else {
				return J9ObjectPointer.NULL;
			}
		} catch (CorruptDataException cde) {
			raiseCorruptDataEvent("Error getting next item", cde, false);		//can try to recover from this
			return null;
		}
	}
	
	public VoidPointer nextAddress()
	{
		return VoidPointer.cast(super.next());
	}
}
