| /* |
| * 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 java.util.Iterator; |
| import org.apache.hadoop.io.Writable; |
| |
| /** |
| * This iterator is designed to deserialize a byte array on the fly to |
| * provide new copies of writable objects when desired. It does not reuse |
| * objects, and instead creates a new one for every next(). |
| * |
| * @param <T> Type that extends Writable that will be iterated |
| */ |
| public abstract class ByteStructIterator<T extends Writable> implements |
| Iterator<T> { |
| /** Data input */ |
| protected final ExtendedDataInput extendedDataInput; |
| |
| /** |
| * Wrap ExtendedDataInput in ByteArrayIterator |
| * |
| * @param extendedDataInput ExtendedDataInput |
| */ |
| public ByteStructIterator(ExtendedDataInput extendedDataInput) { |
| this.extendedDataInput = extendedDataInput; |
| } |
| |
| @Override |
| public boolean hasNext() { |
| return !extendedDataInput.endOfInput(); |
| } |
| |
| @Override |
| public T next() { |
| T writable = createWritable(); |
| try { |
| writable.readFields(extendedDataInput); |
| } catch (IOException e) { |
| throw new IllegalStateException("next: readFields got IOException", e); |
| } |
| return writable; |
| } |
| |
| @Override |
| public void remove() { |
| throw new UnsupportedOperationException("remove: Not supported"); |
| } |
| |
| /** |
| * Must be able to create the writable object |
| * |
| * @return New writable |
| */ |
| protected abstract T createWritable(); |
| } |