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.dataflow;
  
  import java.util.List;
  import java.util.Map;
  import org.apache.beam.runners.dataflow.options.DataflowPipelineOptions;
  import org.apache.beam.runners.dataflow.util.OutputReference;
  import org.apache.beam.sdk.Pipeline;
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.extensions.gcp.options.GcpOptions;
  import org.apache.beam.sdk.runners.AppliedPTransform;
  import org.apache.beam.sdk.transforms.PTransform;
  import org.apache.beam.sdk.util.construction.SdkComponents;
  import org.apache.beam.sdk.values.PCollection;
  import org.apache.beam.sdk.values.PCollectionView;
  import org.apache.beam.sdk.values.PInput;
  import org.apache.beam.sdk.values.POutput;
  import org.apache.beam.sdk.values.PValue;
  import org.apache.beam.sdk.values.TupleTag;
  
  /**
   * A {@link TransformTranslator} knows how to translate a particular subclass of {@link PTransform}
   * for the Cloud Dataflow service. It does so by mutating the {@link TranslationContext}.
   */
  @SuppressWarnings({
    "rawtypes" // TODO(https://github.com/apache/beam/issues/20447)
  })
  public interface TransformTranslator<TransformT extends PTransform> {
    void translate(TransformT transform, TranslationContext context);
  
    /**
     * The interface provided to registered callbacks for interacting with the {@link DataflowRunner},
     * including reading and writing the values of {@link PCollection}s and side inputs.
     */
    interface TranslationContext {
      default boolean isStreamingEngine() {
        List<String> experiments = getPipelineOptions().getExperiments();
        return experiments != null
            && experiments.contains(GcpOptions.STREAMING_ENGINE_EXPERIMENT)
            && experiments.contains(GcpOptions.WINDMILL_SERVICE_EXPERIMENT);
      }
  
      /** Returns the configured pipeline options. */
      DataflowPipelineOptions getPipelineOptions();
  
      /** Returns the input of the currently being translated transform. */
      <InputT extends PInput> Map<TupleTag<?>, PCollection<?>> getInputs(
          PTransform<InputT, ?> transform);
  
      <InputT extends PValue> InputT getInput(PTransform<InputT, ?> transform);
  
      /** Returns the output of the currently being translated transform. */
      <OutputT extends POutput> Map<TupleTag<?>, PCollection<?>> getOutputs(
          PTransform<?, OutputT> transform);
  
      <OutputT extends PValue> OutputT getOutput(PTransform<?, OutputT> transform);
  
      /** Returns the full name of the currently being translated transform. */
      String getFullName(PTransform<?, ?> transform);
  
      /**
       * Adds a step to the Dataflow workflow for the given transform, with the given Dataflow step
       * type.
       */
      StepTranslationContext addStep(PTransform<?, ?> transform, String type);
  
      /** Encode a PValue reference as an output reference. */
      OutputReference asOutputReference(PValue value, AppliedPTransform<?, ?, ?> producer);
  
      SdkComponents getSdkComponents();
  
      AppliedPTransform<?, ?, ?> getCurrentTransform();
  
      /** Get the {@link AppliedPTransform} that produced the provided {@link PValue}. */
      AppliedPTransform<?, ?, ?> getProducer(PValue value);
  
      /**
       * Gets the parent composite transform to the current transform, if one exists. Otherwise
       * returns one null.
       */
      AppliedPTransform<?, ?, ?> getCurrentParent();
    }
  
    /** The interface for a {@link TransformTranslator} to build a Dataflow step. */
    interface StepTranslationContext {
      /** Sets the encoding for this Dataflow step. */
      void addEncodingInput(Coder<?> value);
  
      /** Adds an input with the given name and value to this Dataflow step. */
      void addInput(String name, Boolean value);
  
      /** Adds an input with the given name and value to this Dataflow step. */
      void addInput(String name, String value);
  
      /** Adds an input with the given name and value to this Dataflow step. */
      void addInput(String name, Long value);
  
      /**
       * Adds an input with the given name to this Dataflow step, coming from the specified input
       * PValue.
       *
       * <p>The input {@link PValue} must have already been produced by a step earlier in this {@link
       * Pipeline}. If the input value has not yet been produced yet (by a call to either {@link
       * StepTranslationContext#addOutput} or {@link
       * StepTranslationContext#addCollectionToSingletonOutput}) this method will throw an exception.
       */
      void addInput(String name, PInput value);
  
      /** Adds an input that is a dictionary of strings to objects. */
      void addInput(String name, Map<String, Object> elements);
  
      /** Adds an input that is a list of objects. */
      void addInput(String name, List<? extends Map<String, Object>> elements);
  
      /**
       * Adds a primitive output to this Dataflow step with the given name as the local output name,
       * producing the specified output {@code PValue}, including its {@code Coder} if a {@code
       * TypedPValue}. If the {@code PValue} is a {@code PCollection}, wraps its coder inside a {@code
       * WindowedValueCoder}.
       */
      void addOutput(String name, PCollection<?> value);
  
      /**
       * Adds an output to this {@code CollectionToSingleton} Dataflow step, consuming the specified
       * input {@code PValue} and producing the specified output {@code PValue}. This step requires
       * special treatment for its output encoding. Returns a pipeline level unique id.
       */
      void addCollectionToSingletonOutput(
          PCollection<?> inputValue, String outputName, PCollectionView<?> outputValue);
    }
  }
  