content: /*****************************************************************
   *   Licensed to the Apache Software Foundation (ASF) under one
   *  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
   *  with the License.  You may obtain a copy of the License at
   *
   *    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
   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   *  KIND, either express or implied.  See the License for the
   *  specific language governing permissions and limitations
   *  under the License.
   ****************************************************************/
  
  package org.apache.cayenne.reflect.valueholder;
  
  import org.apache.cayenne.Persistent;
  import org.apache.cayenne.ValueHolder;
  import org.apache.cayenne.reflect.Accessor;
  import org.apache.cayenne.reflect.BaseToOneProperty;
  import org.apache.cayenne.reflect.ClassDescriptor;
  import org.apache.cayenne.reflect.PropertyException;
  import org.apache.cayenne.util.PersistentObjectHolder;
  
  /**
   * Provides access to a property implemented as a {@link ValueHolder} Field. This
   * implementation hides the fact of the ValueHolder existence. I.e. it never returns it
   * from 'readPropertyDirectly', returning held value instead.
   * 
   * @since 3.0
   */
  class ValueHolderProperty extends BaseToOneProperty {
  
      ValueHolderProperty(ClassDescriptor owner, ClassDescriptor targetDescriptor,
              Accessor accessor, String reverseName) {
          super(owner, targetDescriptor, accessor, reverseName);
      }
  
      /**
       * Returns true if a property ValueHolder is not initialized or is itself a fault.
       */
      @Override
      public boolean isFault(Object object) {
          ValueHolder holder = (ValueHolder) accessor.getValue(object);
          return holder == null || holder.isFault();
      }
  
      public void invalidate(Object object) {
          ValueHolder holder = (ValueHolder) accessor.getValue(object);
          if (holder != null && !holder.isFault()) {
              holder.invalidate();
          }
      }
  
      @Override
      public Object readPropertyDirectly(Object object) throws PropertyException {
          ValueHolder holder = (ValueHolder) accessor.getValue(object);
  
          // TODO: Andrus, 2/9/2006 ValueHolder will resolve an object in a call to
          // 'getValue'; this is inconsistent with 'readPropertyDirectly' contract
          return (holder != null) ? holder.getValueDirectly() : null;
      }
  
      @Override
      public Object readProperty(Object object) throws PropertyException {
          return ensureValueHolderSet(object).getValue();
      }
  
      @Override
      public void writePropertyDirectly(Object object, Object oldValue, Object newValue)
              throws PropertyException {
  
          ValueHolder holder = (ValueHolder) accessor.getValue(object);
          if (holder == null) {
              holder = createValueHolder(object);
              accessor.setValue(object, holder);
          }
  
          holder.setValueDirectly(newValue);
      }
  
      @Override
      public void writeProperty(Object object, Object oldValue, Object newValue)
              throws PropertyException {
          ensureValueHolderSet(object).setValueDirectly(newValue);
      }
  
      /**
       * Injects a ValueHolder in the object if it hasn't been done yet.
       */
      @Override
      public void injectValueHolder(Object object) throws PropertyException {
          ensureValueHolderSet(object);
      }
  
      /**
       * Checks that an object's ValueHolder field described by this property is set,
       * injecting a ValueHolder if needed.
       */
      protected ValueHolder ensureValueHolderSet(Object object) throws PropertyException {
  
          ValueHolder holder = (ValueHolder) accessor.getValue(object);
          if (holder == null) {
              holder = createValueHolder(object);
              accessor.setValue(object, holder);
          }
  
          return holder;
      }
  
      /**
       * Creates a ValueHolder for an object. Default implementation requires that an object
       * implements Persistent interface.
       */
      protected ValueHolder createValueHolder(Object object) throws PropertyException {
          if (!(object instanceof Persistent)) {
  
              throw new PropertyException(
                      "ValueHolders for non-persistent objects are not supported.",
                      this,
                      object);
          }
  
          return new PersistentObjectHolder((Persistent) object, getName());
      }
  }
  