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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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   *
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  package org.apache.cayenne.access.util;
  
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.io.StringWriter;
  import java.util.List;
  
  import org.apache.cayenne.CayenneRuntimeException;
  import org.apache.cayenne.ResultIterator;
  import org.apache.cayenne.query.Query;
  
  /**
   * OperationObserver that is used to track the execution of SelectQueries with
   * results returned as ResultIterator.
   * 
   */
  public class IteratedSelectObserver extends DefaultOperationObserver {
      protected ResultIterator resultIterator;
  
      @Override
      public boolean isIteratedResult() {
          return true;
      }
  
      @Override
      public void nextRows(Query query, List<?> dataRows) {
          throw new CayenneRuntimeException("Results unexpectedly returned as list.");
      }
  
      @Override
      public void nextRows(Query q, ResultIterator it) {
          // don't call super - it closes the iterator
          resultIterator = it;
      }
  
      public ResultIterator getResultIterator() {
          if (super.hasExceptions()) {
              StringWriter str = new StringWriter();
              PrintWriter out = new PrintWriter(str);
              super.printExceptions(out);
  
              try {
                  out.close();
                  str.close();
              } catch (IOException ioex) {
                  // this should never happen
              }
  
              throw new CayenneRuntimeException("Error getting ResultIterator: %s", str.getBuffer());
          }
  
          return resultIterator;
      }
  
  }
  