/*

  * 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.utils.IntPair;

 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;

 import java.util.regex.Pattern;

 /**

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

  * unweighted graphs with int ids.

  *

  * Each line consists of: source_vertex, target_vertex

  */

 public class IntNullTextEdgeInputFormat extends

     TextEdgeInputFormat<IntWritable, NullWritable> {

   /** Splitter for endpoints */

   private static final Pattern SEPARATOR = Pattern.compile("[\t ]");

   @Override

   public EdgeReader<IntWritable, NullWritable> createEdgeReader(

       InputSplit split, TaskAttemptContext context) throws IOException {

     return new IntNullTextEdgeReader();

   }

   /**

    * {@link org.apache.giraph.io.EdgeReader} associated with

    * {@link IntNullTextEdgeInputFormat}.

    */

   public class IntNullTextEdgeReader extends

       TextEdgeReaderFromEachLineProcessed<IntPair> {

     @Override

     protected IntPair preprocessLine(Text line) throws IOException {

       String[] tokens = SEPARATOR.split(line.toString());

       return new IntPair(Integer.parseInt(tokens[0]),

           Integer.parseInt(tokens[1]));

     }

     @Override

     protected IntWritable getSourceVertexId(IntPair endpoints)

       throws IOException {

       return new IntWritable(endpoints.getFirst());

     }

     @Override

     protected IntWritable getTargetVertexId(IntPair endpoints)

       throws IOException {

       return new IntWritable(endpoints.getSecond());

     }

     @Override

     protected NullWritable getValue(IntPair endpoints) throws IOException {

       return NullWritable.get();

     }

   }

 }