/*
 * 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 java.util.NoSuchElementException;

import com.ibm.j9ddr.CorruptDataException;
import com.ibm.j9ddr.vm29.pointer.PointerPointer;
import com.ibm.j9ddr.vm29.pointer.VoidPointer;
import com.ibm.j9ddr.vm29.pointer.generated.J9ClassPointer;
import com.ibm.j9ddr.vm29.pointer.generated.J9MemorySegmentPointer;

public class GCClassHeapIterator extends GCIterator 
{
	private J9ClassPointer classPointer; 
	
	/* Do not instantiate. Use the factory */
	protected GCClassHeapIterator(J9MemorySegmentPointer memorySegment) throws CorruptDataException 
	{
		classPointer = J9ClassPointer.cast(PointerPointer.cast(memorySegment.heapBase()).at(0));
	}
	
	/**
	 * Factory method to construct an appropriate class segment iterator.
	 * @param memorySegment the memorySegment to iterate
	 * 
	 * @return an instance of GCClassHeapIterator 
	 * @throws CorruptDataException 
	 */
	public static GCClassHeapIterator fromJ9MemorySegment(J9MemorySegmentPointer memorySegment) throws CorruptDataException
	{
		return new GCClassHeapIterator(memorySegment);
	}
	
	public boolean hasNext() 
	{
		return classPointer.notNull();
	}

	public J9ClassPointer next() 
	{
		try {
			if(hasNext()) {
				J9ClassPointer clazz = classPointer;
				classPointer = classPointer.nextClassInSegment();
				return clazz;
			} else {
				throw new NoSuchElementException("There are no more items available through this iterator");
			}
		} catch(CorruptDataException cde) {
			raiseCorruptDataEvent("Could not set the current class", cde, false);		//can try to recover from this
			return null;
		}
	}
	
	public VoidPointer nextAddress() 
	{
		// Does not make sense in this case
		throw new UnsupportedOperationException("This iterator cannot return addresses");
	}
}
