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.Pipeline;
  import org.apache.beam.sdk.options.PipelineOptions;
  import org.apache.beam.sdk.runners.TransformHierarchy;
  import org.apache.beam.sdk.transforms.display.DisplayData;
  import org.apache.beam.sdk.transforms.display.HasDisplayData;
  
  /**
   * Validate correct implementation of {@link DisplayData} by evaluating {@link
   * HasDisplayData#populateDisplayData(DisplayData.Builder)} during pipeline construction.
   */
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  class DisplayDataValidator {
    // Do not instantiate
    private DisplayDataValidator() {}
  
    static void validatePipeline(Pipeline pipeline) {
      validateTransforms(pipeline);
    }
  
    static void validateOptions(PipelineOptions options) {
      evaluateDisplayData(options);
    }
  
    private static void validateTransforms(Pipeline pipeline) {
      pipeline.traverseTopologically(Visitor.INSTANCE);
    }
  
    private static void evaluateDisplayData(HasDisplayData component) {
      DisplayData.from(component);
    }
  
    private static class Visitor extends Pipeline.PipelineVisitor.Defaults {
      private static final Visitor INSTANCE = new Visitor();
  
      @Override
      public CompositeBehavior enterCompositeTransform(TransformHierarchy.Node node) {
        if (!node.isRootNode()) {
          evaluateDisplayData(node.getTransform());
        }
  
        return CompositeBehavior.ENTER_TRANSFORM;
      }
  
      @Override
      public void visitPrimitiveTransform(TransformHierarchy.Node node) {
        evaluateDisplayData(node.getTransform());
      }
    }
  }
  