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  package org.apache.cayenne.access.translator.select;
  
  import org.apache.cayenne.access.sqlbuilder.NodeBuilder;
  import org.apache.cayenne.access.sqlbuilder.sqltree.Node;
  import org.apache.cayenne.exp.Expression;
  import org.apache.cayenne.exp.parser.ASTAggregateFunctionCall;
  import org.apache.cayenne.query.Ordering;
  
  import static org.apache.cayenne.access.sqlbuilder.SQLBuilder.*;
  
  abstract class OrderingAbstractStage implements TranslationStage {
  
      protected void processOrdering(QualifierTranslator qualifierTranslator, TranslatorContext context, Ordering ordering) {
          Expression orderExp = ordering.getSortSpec();
          NodeBuilder nodeBuilder = node(qualifierTranslator.translate(orderExp));
  
          if (ordering.isCaseInsensitive()) {
              nodeBuilder = function("UPPER", nodeBuilder);
          }
  
          // If query is DISTINCT or GROUPING then we need to add the order column as a result column
          Node orderingNode = nodeBuilder.build();
          if (orderColumnAbsent(context, orderingNode)) {
              // deepCopy as some DB expect exactly the same expression in select and in ordering
              ResultNodeDescriptor descriptor = context.addResultNode(orderingNode.deepCopy());
              if (orderExp instanceof ASTAggregateFunctionCall) {
                  descriptor.setAggregate(true);
              }
          }
      }
  
      private boolean orderColumnAbsent(TranslatorContext context, Node orderingNode) {
          for (ResultNodeDescriptor result : context.getResultNodeList()) {
              if (result.getNode().deepEquals(orderingNode)) {
                  return false;
              }
          }
          return true;
      }
  }
  