/*
    * 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 org.apache.giraph.io.EdgeReader;
  import org.apache.giraph.io.ReverseEdgeDuplicator;
  import org.apache.hadoop.io.IntWritable;
  import org.apache.hadoop.io.NullWritable;
  import org.apache.hadoop.mapreduce.InputSplit;
  import org.apache.hadoop.mapreduce.TaskAttemptContext;
  
  import java.io.IOException;
  
  /**
   * Simple text-based {@link org.apache.giraph.io.EdgeInputFormat} for
   * unweighted graphs with int ids.
   *
   * Each line consists of: source_vertex, target_vertex
   *
   * This version also creates the reverse edges.
   */
  public class IntNullReverseTextEdgeInputFormat
      extends IntNullTextEdgeInputFormat {
    @Override
    public EdgeReader<IntWritable, NullWritable> createEdgeReader(
        InputSplit split, TaskAttemptContext context) throws IOException {
      EdgeReader<IntWritable, NullWritable> edgeReader =
          super.createEdgeReader(split, context);
      edgeReader.setConf(getConf());
      return new ReverseEdgeDuplicator<IntWritable, NullWritable>(edgeReader);
    }
  }