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.access;
  
  import java.io.Serializable;
  import java.util.Collection;
  import java.util.LinkedList;
  import java.util.List;
  
  import org.apache.cayenne.PersistenceState;
  import org.apache.cayenne.Persistent;
  import org.apache.cayenne.util.PersistentObjectList;
  
  /**
   * A list that holds objects for to-many relationships. All operations, except for
   * resolving the list from DB, are not synchronized. The safest way to implement custom
   * synchronization is to synchronize on parent ObjectStore.
   */
  public class ToManyList<E> extends PersistentObjectList<E> implements Serializable {
  
      /**
       * Creates ToManyList.
       * 
       * @since 1.1
       */
      public ToManyList(Persistent source, String relationship) {
          super(source, relationship);
  
          // if source is new, set object list right away
          if (isTransientParent()) {
              objectList = new LinkedList<>();
          }
      }
  
      // ====================================================
      // Standard List Methods.
      // ====================================================
      @Override
      public int hashCode() {
          return 15 + resolvedObjectList().hashCode();
      }
  
      // ====================================================
      // Tracking list modifications, and resolving it
      // on demand
      // ====================================================
  
      @Override
      protected boolean shouldAddToRemovedFromUnresolvedList(Object object) {
          // No point in adding a new or transient object -- these will never be fetched
          // from the database.
          if (object instanceof Persistent) {
              Persistent persistent = (Persistent) object;
              if ((persistent.getPersistenceState() == PersistenceState.TRANSIENT)
                      || (persistent.getPersistenceState() == PersistenceState.NEW)) {
                  return false;
              }
          }
          return true;
      }
  
      @Override
      public String toString() {
          return getClass().getName() + "@" + System.identityHashCode(this);
      }
  
      @Override
      protected void postprocessAdd(Collection<? extends E> collection) {
          // no need for this operation for Persistent objects...
      }
  
      @Override
      protected void postprocessRemove(Collection<? extends E> collection) {
          // no need for this operation for Persistent objects...
      }
  
      @Override
      protected void postprocessAdd(E addedObject) {
          // no need for this operation for Persistent objects...
      }
  
      @Override
      protected void postprocessRemove(E removedObject) {
          // no need for this operation for Persistent objects...
      }
  
      @Override
      protected void updateReverse(List<E> resolved) {
          // no need for this operation for Persistent objects...
      }
  }
  