/*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you 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 org.apache.giraph.utils;

 import java.io.IOException;

 import org.apache.hadoop.io.Writable;

 /**

  * The objects provided by this iterator have lifetimes only until next() is

  * called.  In that sense, the object provided is only a representative object.

  *

  * @param <T> Type that extends Writable that will be iterated

  */

 public abstract class RepresentativeByteStructIterator<T extends

     Writable> extends ByteStructIterator<T> {

   /** Representative writable */

   private final T representativeWritable = createWritable();

   /**

    * Wrap ExtendedDataInput in ByteArrayIterator

    *

    * @param extendedDataInput ExtendedDataInput

    */

   public RepresentativeByteStructIterator(ExtendedDataInput extendedDataInput) {

     super(extendedDataInput);

   }

   @Override

   public T next() {

     try {

       representativeWritable.readFields(extendedDataInput);

     } catch (IOException e) {

       throw new IllegalStateException("next: readFields got IOException", e);

     }

     return representativeWritable;

   }

 }