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.sdk.values;
  
  import java.io.Serializable;
  import org.apache.beam.sdk.PipelineRunner;
  import org.apache.beam.sdk.annotations.Internal;
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.transforms.ParDo;
  import org.apache.beam.sdk.transforms.View;
  import org.apache.beam.sdk.transforms.ViewFn;
  import org.apache.beam.sdk.transforms.windowing.WindowMappingFn;
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  /**
   * A {@link PCollectionView PCollectionView&lt;T&gt;} is an immutable view of a {@link PCollection}
   * as a value of type {@code T} that can be accessed as a side input to a {@link ParDo} transform.
   *
   * <p>A {@link PCollectionView} should always be the output of a {@link
   * org.apache.beam.sdk.transforms.PTransform}. It is the joint responsibility of this transform and
   * each {@link PipelineRunner} to implement the view in a runner-specific manner.
   *
   * <p>The most common case is using the {@link View} transforms to prepare a {@link PCollection} for
   * use as a side input to {@link ParDo}. See {@link View#asSingleton()}, {@link View#asIterable()},
   * and {@link View#asMap()} for more detail on specific views available in the SDK.
   *
   * <p>NOTE: View methods should not be considered to be user-accessible. They are implementation
   * details of how a Runner obtains information required to construct a view, and are subject to
   * change at any time.
   *
   * @param <T> the type of the value(s) accessible via this {@link PCollectionView}
   */
  public interface PCollectionView<T> extends PValue, Serializable {
    /**
     * <b>For internal use only.</b>
     *
     * <p>Gets the {@link PCollection} this {@link PCollectionView} was created from.
     *
     * <p>The {@link PCollection} may not be available in all contexts.
     */
    @Internal
    @Nullable
    PCollection<?> getPCollection();
    /**
     * <b>For internal use only.</b>
     *
     * @deprecated this method will be removed entirely. The {@link PCollection} underlying a side
     *     input, is part of the side input's specification with a {@link ParDo} transform, which will
     *     obtain that information via a package-private channel.
     */
    @Deprecated
    @Internal
    TupleTag<?> getTagInternal();
  
    /**
     * <b>For internal use only.</b>
     *
     * @deprecated this method will be removed entirely. The {@link ViewFn} for a side input is an
     *     attribute of the side input's specification with a {@link ParDo} transform, which will
     *     obtain this specification via a package-private channel.
     */
    @Deprecated
    @Internal
    ViewFn<?, T> getViewFn();
  
    /**
     * <b>For internal use only.</b>
     *
     * <p>Returns the {@link WindowMappingFn} used to map windows from a main input to the side input
     * of this {@link PCollectionView}.
     */
    @Internal
    WindowMappingFn<?> getWindowMappingFn();
  
    /**
     * <b>For internal use only.</b>
     *
     * @deprecated this method will be removed entirely. The {@link PCollection} underlying a side
     *     input, including its {@link WindowingStrategy}, is part of the side input's specification
     *     with a {@link ParDo} transform, which will obtain that information via a package-private
     *     channel.
     */
    @Deprecated
    @Internal
    WindowingStrategy<?, ?> getWindowingStrategyInternal();
  
    /**
     * <b>For internal use only.</b>
     *
     * @deprecated this method will be removed entirely. The {@link PCollection} underlying a side
     *     input, including its {@link Coder}, is part of the side input's specification with a {@link
     *     ParDo} transform, which will obtain that information via a package-private channel.
     */
    @Deprecated
    @Internal
    Coder<?> getCoderInternal();
  }
  