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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
   *
   *  Unless required by applicable law or agreed to in writing,
   *  software distributed under the License is distributed on an
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  package org.apache.cayenne.reflect;
  
  /**
   * An accessor for fields storing embedded objects. This accessor will initialize null
   * fields with appropriate embeddable objects when needed during get and set calls.
   * 
   * @since 3.0
   */
  public class EmbeddedFieldAccessor implements Accessor {
  
      protected String propertyPath;
      protected Accessor embeddedAccessor;
      protected Accessor embeddableAccessor;
      protected EmbeddableDescriptor embeddableDescriptor;
  
      public EmbeddedFieldAccessor(EmbeddableDescriptor embeddableDescriptor,
                                   Accessor embeddedAccessor, Accessor embeddableAccessor) {
          this.propertyPath = embeddedAccessor.getName() + "." + embeddableAccessor.getName();
          this.embeddableDescriptor = embeddableDescriptor;
          this.embeddableAccessor = embeddableAccessor;
          this.embeddedAccessor = embeddedAccessor;
      }
  
      public String getName() {
          return propertyPath;
      }
  
      public Object getValue(Object object) throws PropertyException {
          return embeddableAccessor.getValue(getEmbeddable(object));
      }
  
      public void setValue(Object object, Object newValue) throws PropertyException {
          embeddableAccessor.setValue(getEmbeddable(object), newValue);
      }
  
      /**
       * Returns an embeddable object for the owner object, initializing embeddable if it is
       * null. Currently supports only one level of embedding.
       */
      protected Object getEmbeddable(Object owner) {
          Object embeddable = embeddedAccessor.getValue(owner);
          if (embeddable == null) {
              embeddable = embeddableDescriptor.createObject(owner, embeddedAccessor.getName());
              embeddedAccessor.setValue(owner, embeddable);
          }
  
          return embeddable;
      }
  }
  