code: package it.unibz.inf.ontop.iq.transform.impl;
  
  import com.google.common.collect.ImmutableList;
  import it.unibz.inf.ontop.iq.IQTree;
  import it.unibz.inf.ontop.iq.LeafIQTree;
  import it.unibz.inf.ontop.iq.node.*;
  import it.unibz.inf.ontop.iq.transform.IQTreeExtendedTransformer;
  
  /**
   * To be extended by overloading the methods of interest.
   */
  public class DefaultIdentityIQTreeExtendedTransformer<T> implements IQTreeExtendedTransformer<T> {
  
      @Override
      public IQTree transformIntensionalData(IntensionalDataNode dataNode, T context) {
          return dataNode;
      }
  
      @Override
      public IQTree transformExtensionalData(ExtensionalDataNode dataNode, T context) {
          return dataNode;
      }
  
      @Override
      public IQTree transformEmpty(EmptyNode node, T context) {
          return node;
      }
  
      @Override
      public IQTree transformTrue(TrueNode node, T context) {
          return node;
      }
  
      @Override
      public IQTree transformValues(ValuesNode node, T context) {
          return node;
      }
  
      @Override
      public IQTree transformNonStandardLeafNode(LeafIQTree leafNode, T context) {
          return leafNode;
      }
  
      @Override
      public IQTree transformConstruction(IQTree tree, ConstructionNode rootNode, IQTree child,
                                          T context) {
          return tree;
      }
  
      @Override
      public IQTree transformAggregation(IQTree tree, AggregationNode aggregationNode, IQTree child,
                                         T context) {
          return tree;
      }
  
      @Override
      public IQTree transformFilter(IQTree tree, FilterNode rootNode, IQTree child, T context) {
          return tree;
      }
  
      @Override
      public IQTree transformFlatten(IQTree tree, FlattenNode rootNode, IQTree child, T context) {
          return tree;
      }
  
      @Override
      public IQTree transformDistinct(IQTree tree, DistinctNode distinctNode, IQTree child, T context) {
          return tree;
      }
  
      @Override
      public IQTree transformSlice(IQTree tree, SliceNode rootNode, IQTree child, T context) {
          return tree;
      }
  
      @Override
      public IQTree transformOrderBy(IQTree tree, OrderByNode rootNode, IQTree child, T context) {
          return tree;
      }
  
      @Override
      public IQTree transformNonStandardUnaryNode(IQTree tree, UnaryOperatorNode rootNode, IQTree child, T context) {
          return tree;
      }
  
      @Override
      public IQTree transformLeftJoin(IQTree tree, LeftJoinNode rootNode, IQTree leftChild, IQTree rightChild, T context) {
          return tree;
      }
  
      @Override
      public IQTree transformNonStandardBinaryNonCommutativeNode(IQTree tree, BinaryNonCommutativeOperatorNode rootNode,
                                                                 IQTree leftChild, IQTree rightChild, T context) {
          return tree;
      }
  
      @Override
      public IQTree transformInnerJoin(IQTree tree, InnerJoinNode rootNode, ImmutableList<IQTree> children, T context) {
          return tree;
      }
  
      @Override
      public IQTree transformUnion(IQTree tree, UnionNode rootNode, ImmutableList<IQTree> children, T context) {
          return tree;
      }
  
      @Override
      public IQTree transformNonStandardNaryNode(IQTree tree, NaryOperatorNode rootNode, ImmutableList<IQTree> children, T context) {
          return tree;
      }
  }
  