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   *  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
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   *
   *    https://www.apache.org/licenses/LICENSE-2.0
   *
   *  Unless required by applicable law or agreed to in writing,
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  package org.apache.cayenne.modeler.util;
  
  import java.awt.datatransfer.DataFlavor;
  import java.awt.datatransfer.Transferable;
  import java.awt.datatransfer.UnsupportedFlavorException;
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.io.Serializable;
  import java.io.StringWriter;
  import java.util.List;
  
  import org.apache.cayenne.configuration.ConfigurationNodeVisitor;
  import org.apache.cayenne.configuration.EmptyConfigurationNodeVisitor;
  import org.apache.cayenne.util.XMLEncoder;
  import org.apache.cayenne.util.XMLSerializable;
  
  /**
   * CayenneTransferable is a data holder of Cayenne object(s), like
   * Entities, Attributes, Relationships etc.
   */
  public class CayenneTransferable implements Transferable {
      /**
       * Flavor used for copy-paste between Cayenne Modeler applications
       */
      public static final DataFlavor CAYENNE_FLAVOR = new DataFlavor(Serializable.class, "Cayenne Object");
      
      /**
       * Supported flavors
       */
      private static final DataFlavor[] FLAVORS = new DataFlavor[] { CAYENNE_FLAVOR, DataFlavor.stringFlavor };
      
      /**
       * Data in the buffer
       */
      private Object data;
      
      public CayenneTransferable(Object data) {
          this.data = data;
      }
  
      public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException,
              IOException {
          
          if (flavor == CAYENNE_FLAVOR) {
              return data;
          } else {
              StringWriter out = new StringWriter();
              XMLEncoder encoder = new XMLEncoder(new PrintWriter(out), "\t");
              ConfigurationNodeVisitor visitor = new EmptyConfigurationNodeVisitor();
  
              encoder.println("<?xml version=\"1.0\" encoding=\"utf-8\"?>");
              
              if (data instanceof XMLSerializable) {
                  ((XMLSerializable) data).encodeAsXML(encoder, visitor);
              } else if (data instanceof List) {
                  for (Object o : (List) data) {
                      ((XMLSerializable) o).encodeAsXML(encoder, visitor);
                  }
              }
              
              return out.toString();
          }
          
      }
  
      public DataFlavor[] getTransferDataFlavors() {
          return FLAVORS;
      }
  
      public boolean isDataFlavorSupported(DataFlavor flavor) {
          return flavor == CAYENNE_FLAVOR || flavor == DataFlavor.stringFlavor;
      }
  
  }
  