/*
    * 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.reducers.collect;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.giraph.reducers.impl.KryoWrappedReduceOperation;
  
  /**
   * Collect values reduce operation
   *
   * @param <S> Type of values to collect
   */
  public class CollectReduceOperation<S>
      extends KryoWrappedReduceOperation<S, List<S>> {
    @Override
    public List<S> createValue() {
      return createList();
    }
  
    @Override
    public void reduce(List<S> reduceInto, S value) {
      reduceInto.add(value);
    }
  
    @Override
    public void reduceMerge(List<S> reduceInto, List<S> toReduce) {
      reduceInto.addAll(toReduce);
    }
  
    public List<S> createList() {
      return new ArrayList<>();
    }
  }