/*

  * 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.edge.Edge;

 import org.apache.giraph.edge.EdgeFactory;

 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 com.google.common.collect.Lists;

 import java.io.IOException;

 import java.util.List;

 import java.util.regex.Pattern;

 /**

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

  * unweighted graphs with int ids.

  *

  * Each line consists of: vertex neighbor1 neighbor2 ...

  */

 public class IntIntNullTextInputFormat extends

     TextVertexInputFormat<IntWritable, IntWritable, NullWritable> {

   /** Separator of the vertex and neighbors */

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

   @Override

   public TextVertexReader createVertexReader(InputSplit split,

       TaskAttemptContext context)

     throws IOException {

     return new IntIntNullVertexReader();

   }

   /**

    * Vertex reader associated with {@link IntIntNullTextInputFormat}.

    */

   public class IntIntNullVertexReader extends

     TextVertexReaderFromEachLineProcessed<String[]> {

     /**

      * Cached vertex id for the current line

      */

     private IntWritable id;

     @Override

     protected String[] preprocessLine(Text line) throws IOException {

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

       id = new IntWritable(Integer.parseInt(tokens[0]));

       return tokens;

     }

     @Override

     protected IntWritable getId(String[] tokens) throws IOException {

       return id;

     }

     @Override

     protected IntWritable getValue(String[] tokens) throws IOException {

       return id;

     }

     @Override

     protected Iterable<Edge<IntWritable, NullWritable>> getEdges(

         String[] tokens) throws IOException {

       List<Edge<IntWritable, NullWritable>> edges =

           Lists.newArrayListWithCapacity(tokens.length - 1);

       for (int n = 1; n < tokens.length; n++) {

         edges.add(EdgeFactory.create(

             new IntWritable(Integer.parseInt(tokens[n]))));

       }

       return edges;

     }

   }

 }