content: /*
   * 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.beam.it.truthmatchers;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.List;
  
  /**
   * Provides a wrapper around a List which can be used to accumulate results, useful for assertions
   * that consume inputs and need to keep state across calls.
   */
  public class ListAccumulator<T> {
  
    private List<T> backingList;
  
    /** Initialize the accumulator. */
    public ListAccumulator() {
      this.backingList = new ArrayList<>();
    }
  
    /**
     * Add the partial results to the backingList, and return the accumulated count.
     *
     * @param partial Partial results to accumulate.
     * @return Accumulated count.
     */
    public int accumulate(Collection<T> partial) {
      this.backingList.addAll(partial);
      return this.backingList.size();
    }
  
    /**
     * Return the count of objects accumulated so far.
     *
     * @return Count, which is the size of the backingList.
     */
    public int count() {
      return this.backingList.size();
    }
  
    /** @return the internal backing list being accumulated. */
    public List<T> getBackingList() {
      return this.backingList;
    }
  }
  