001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019package org.apache.hadoop.mapreduce;
020
021import java.io.IOException;
022import java.util.Iterator;
023
024import org.apache.hadoop.classification.InterfaceAudience;
025import org.apache.hadoop.classification.InterfaceStability;
026
027/**
028 * <code>MarkableIterator</code> is a wrapper iterator class that 
029 * implements the {@link MarkableIteratorInterface}.
030 * 
031 */
032@InterfaceAudience.Public
033@InterfaceStability.Evolving
034public class MarkableIterator<VALUE> 
035  implements MarkableIteratorInterface<VALUE> {
036
037  MarkableIteratorInterface<VALUE> baseIterator;
038
039  /**
040   * Create a new iterator layered on the input iterator
041   * @param itr underlying iterator that implements MarkableIteratorInterface
042   */
043  public MarkableIterator(Iterator<VALUE> itr)  {
044    if (!(itr instanceof MarkableIteratorInterface)) {
045      throw new IllegalArgumentException("Input Iterator not markable");
046    }
047    baseIterator = (MarkableIteratorInterface<VALUE>) itr;
048  }
049
050  @Override
051  public void mark() throws IOException {
052    baseIterator.mark();
053  }
054
055  @Override
056  public void reset() throws IOException {
057    baseIterator.reset();
058  }
059
060  @Override
061  public void clearMark() throws IOException {
062    baseIterator.clearMark();
063  }
064
065  @Override
066  public boolean hasNext() { 
067    return baseIterator.hasNext();
068  }
069
070  @Override
071  public VALUE next() {
072    return baseIterator.next();
073  }
074
075  @Override
076  public void remove() {
077    throw new UnsupportedOperationException("Remove Not Implemented");
078  }
079}