/*

  * 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.block_app.test_setup.graphs;

 import org.apache.giraph.block_app.test_setup.NumericTestGraph;

 import org.apache.giraph.block_app.test_setup.TestGraphModifier;

 import org.apache.giraph.function.Supplier;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 /**

  * Create a directed tree that looks like:

  *

  *   0 __

  *  / \  \

  * 1   2  6

  * |   |\

  * 3   4 5

  *

  * Edges are directed from top to bottom.

  * Vertices with no edges are created.

  *

  * @param <I> Vertex id type

  * @param <V> Vertex value type

  * @param <E> Edge value type

  */

 public class SmallDirectedTreeGraphInit<I extends WritableComparable,

     V extends Writable, E extends Writable>

     implements TestGraphModifier<I, V, E> {

   private final Supplier<E> edgeSupplier;

   public SmallDirectedTreeGraphInit() {

     this(null);

   }

   public SmallDirectedTreeGraphInit(Supplier<E> edgeSupplier) {

     this.edgeSupplier = edgeSupplier;

   }

   @Override

   public void modifyGraph(NumericTestGraph<I, V, E> graph) {

     graph.addEdge(0, 1, createEdgeValue());

     graph.addEdge(0, 2, createEdgeValue());

     graph.addEdge(0, 6, createEdgeValue());

     graph.addEdge(1, 3, createEdgeValue());

     graph.addEdge(2, 4, createEdgeValue());

     graph.addEdge(2, 5, createEdgeValue());

     graph.addVertex(3);

     graph.addVertex(4);

     graph.addVertex(5);

     graph.addVertex(6);

   }

   private E createEdgeValue() {

     return edgeSupplier != null ? edgeSupplier.get() : null;

   }

 }