/*

  * 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.io.formats;

 import com.google.common.collect.ImmutableList;

 import org.apache.giraph.edge.Edge;

 import org.apache.hadoop.io.IntWritable;

 import org.apache.hadoop.io.NullWritable;

 import org.apache.hadoop.io.Text;

 import org.apache.hadoop.mapreduce.InputSplit;

 import org.apache.hadoop.mapreduce.TaskAttemptContext;

 import java.io.IOException;

 /**

  * Simple text-based {@link org.apache.giraph.io.VertexInputFormat} for

  * unweighted graphs without edges or values, just vertices with ids.

  *

  * Each line is just simply the vertex id.

  */

 public class IntNullNullTextInputFormat extends TextVertexInputFormat<

     IntWritable, NullWritable, NullWritable> {

   @Override

   public TextVertexReader createVertexReader(

       InputSplit split, TaskAttemptContext context) throws IOException {

     return new IntNullNullNullVertexReader();

   }

   /**

    * Reader for this InputFormat.

    */

   public class IntNullNullNullVertexReader extends

       TextVertexReaderFromEachLineProcessed<String> {

     /** Cached vertex id */

     private IntWritable id;

     @Override

     protected String preprocessLine(Text line) throws IOException {

       id = new IntWritable(Integer.parseInt(line.toString()));

       return line.toString();

     }

     @Override

     protected IntWritable getId(String line) throws IOException {

       return id;

     }

     @Override

     protected NullWritable getValue(String line) throws IOException {

       return NullWritable.get();

     }

     @Override

     protected Iterable<Edge<IntWritable, NullWritable>> getEdges(String line)

       throws IOException {

       return ImmutableList.of();

     }

   }

 }