/***********************************************************************************************************************
 *
 * Copyright (C) 2010 by the Stratosphere project (http://stratosphere.eu)
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 *
 **********************************************************************************************************************/

package eu.stratosphere.pact.runtime.util;

import java.io.IOException;

/**
 * The memory block iterator is an iterator that always buffers a block of elements
 * in memory.
 */
public interface MemoryBlockIterator
{
	/**
	 * Move the iterator to the next memory block. The next memory block starts at the first element that was not
	 * in the block before. A special case is when no record was in the block before, which happens when this
	 * function is invoked two times directly in a sequence, without calling hasNext() or next in between. Then
	 * the block moves one element.
	 * 
	 * @return True if a new memory block was loaded, false if there were no further
	 *         records and hence no further memory block.
	 *         
	 * @throws IOException Thrown, when advancing to the next block failed.
	 */
	public boolean nextBlock() throws IOException;
}
