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   *  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
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   *    https://www.apache.org/licenses/LICENSE-2.0
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  package org.apache.cayenne.access.translator.ejbql;
  
  import org.apache.cayenne.ejbql.EJBQLBaseVisitor;
  import org.apache.cayenne.ejbql.EJBQLException;
  import org.apache.cayenne.ejbql.EJBQLExpression;
  import org.apache.cayenne.ejbql.EJBQLExpressionVisitor;
  
  /**
   * @since 3.0
   */
  class EJBQLOrderByTranslator extends EJBQLBaseVisitor {
  
      private EJBQLTranslationContext context;
      private int itemCount;
  
      EJBQLOrderByTranslator(EJBQLTranslationContext context) {
          this.context = context;
      }
  
      @Override
      public boolean visitOrderByItem(EJBQLExpression expression) {
          if (itemCount++ > 0) {
              context.append(',');
          }
  
          return true;
      }
  
      @Override
      public boolean visitDescending(EJBQLExpression expression) {
          context.append(" DESC");
          return true;
      }
      
  	@Override
  	public boolean visitAggregate(EJBQLExpression expression) {
  		expression.visit(context.getTranslatorFactory().getAggregateColumnTranslator(context));
  		return false;
  	}
  
      @Override
      public boolean visitPath(EJBQLExpression expression, int finishedChildIndex) {
  
          EJBQLExpressionVisitor childVisitor = new EJBQLPathTranslator(context) {
  
              @Override
              protected void appendMultiColumnPath(EJBQLMultiColumnOperand operand) {
                  throw new EJBQLException("Can't order on multi-column paths or objects");
              }
          };
          expression.visit(childVisitor);
          return false;
      }
  
      @Override
      public boolean visitDbPath(EJBQLExpression expression, int finishedChildIndex) {
          expression.visit(new EJBQLDbPathTranslator(context) {
              @Override
              protected void appendMultiColumnPath(EJBQLMultiColumnOperand operand) {
                  throw new EJBQLException("Can't order on multi-column paths or objects");
              }
          });
          return false;
      }
  }
  