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.spark.translation;
  
  import java.util.Collections;
  import java.util.Iterator;
  import org.apache.beam.sdk.transforms.join.RawUnionValue;
  import org.apache.beam.sdk.values.WindowedValue;
  import org.apache.spark.api.java.function.FlatMapFunction;
  
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  class SparkExecutableStageExtractionFunction<OutputT>
      implements FlatMapFunction<RawUnionValue, WindowedValue<OutputT>> {
    private final int unionTag;
  
    SparkExecutableStageExtractionFunction(int unionTag) {
      this.unionTag = unionTag;
    }
  
    @Override
    public Iterator<WindowedValue<OutputT>> call(RawUnionValue rawUnionValue) {
      if (rawUnionValue.getUnionTag() == unionTag) {
        WindowedValue<OutputT> output = (WindowedValue<OutputT>) rawUnionValue.getValue();
        return Collections.singleton(output).iterator();
      }
      return Collections.emptyIterator();
    }
  }
  