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.runners.direct;
  
  import org.apache.beam.sdk.runners.AppliedPTransform;
  import org.apache.beam.sdk.transforms.Flatten;
  import org.apache.beam.sdk.transforms.Flatten.PCollections;
  import org.apache.beam.sdk.transforms.PTransform;
  import org.apache.beam.sdk.values.PCollection;
  import org.apache.beam.sdk.values.PCollectionList;
  import org.apache.beam.sdk.values.WindowedValue;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
  
  /**
   * The {@link DirectRunner} {@link TransformEvaluatorFactory} for the {@link Flatten} {@link
   * PTransform}.
   */
  class FlattenEvaluatorFactory implements TransformEvaluatorFactory {
    private final EvaluationContext evaluationContext;
  
    FlattenEvaluatorFactory(EvaluationContext evaluationContext) {
      this.evaluationContext = evaluationContext;
    }
  
    @Override
    public <InputT> TransformEvaluator<InputT> forApplication(
        AppliedPTransform<?, ?, ?> application, CommittedBundle<?> inputBundle) {
      @SuppressWarnings({"cast", "unchecked", "rawtypes"})
      TransformEvaluator<InputT> evaluator =
          (TransformEvaluator<InputT>) createInMemoryEvaluator((AppliedPTransform) application);
      return evaluator;
    }
  
    @Override
    public void cleanup() throws Exception {}
  
    private <InputT> TransformEvaluator<InputT> createInMemoryEvaluator(
        final AppliedPTransform<PCollectionList<InputT>, PCollection<InputT>, PCollections<InputT>>
            application) {
      final UncommittedBundle<InputT> outputBundle =
          evaluationContext.createBundle(
              (PCollection<InputT>) Iterables.getOnlyElement(application.getOutputs().values()));
      final TransformResult<InputT> result =
          StepTransformResult.<InputT>withoutHold(application).addOutput(outputBundle).build();
      return new FlattenEvaluator<>(outputBundle, result);
    }
  
    private static class FlattenEvaluator<InputT> implements TransformEvaluator<InputT> {
      private final UncommittedBundle<InputT> outputBundle;
      private final TransformResult<InputT> result;
  
      public FlattenEvaluator(
          UncommittedBundle<InputT> outputBundle, TransformResult<InputT> result) {
        this.outputBundle = outputBundle;
        this.result = result;
      }
  
      @Override
      public void processElement(WindowedValue<InputT> element) {
        outputBundle.add(element);
      }
  
      @Override
      public TransformResult<InputT> finishBundle() {
        return result;
      }
    }
  }
  