trunk/gora-core/src/main/java/org/apache/gora/persistency/StateManager.java

/**
 * 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
 *
 *     http://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.gora.persistency;

/**
 * StateManager manages objects state for persistency.
 */
public interface StateManager {

  /**
   * If one state manager is allocated per persistent object, 
   * call this method to set the managed persistent. 
   * @param persistent the persistent to manage
   */
  void setManagedPersistent(Persistent persistent);

  /**
   * Returns whether the object is newly constructed.
   * @return true if the object is newly constructed, false if
   * retrieved from a datastore. 
   */
  boolean isNew(Persistent persistent);
  
  /**
   * Sets the state of the object as new for persistency
   */
  void setNew(Persistent persistent);
  
  /**
   * Clears the new state 
   */
  void clearNew(Persistent persistent);

  /**
   * Returns whether any of the fields of the object has been modified 
   * after construction or loading. 
   * @return whether any of the fields of the object has changed
   */
  boolean isDirty(Persistent persistent);
  
  /**
   * Returns whether the field has been modified.
   * @param fieldIndex the offset of the field in the object
   * @return whether the field has been modified.
   */
  boolean isDirty(Persistent persistent, int fieldIndex);
  
  /**
   * Sets all the fields of the object as dirty.
   */
  void setDirty(Persistent persistent);
  
  /**
   * Sets the field as dirty.
   * @param fieldIndex the offset of the field in the object
   */
  void setDirty(Persistent persistent, int fieldIndex);

  /**
   * Clears the field as dirty.
   * @param fieldIndex the offset of the field in the object
   */
  void clearDirty(Persistent persistent, int fieldIndex);
  
  /**
   * Clears the dirty state.
   */
  void clearDirty(Persistent persistent);
  
  /**
   * Returns whether the field has been loaded from the datastore. 
   * @param fieldIndex the offset of the field in the object
   * @return whether the field has been loaded 
   */
  boolean isReadable(Persistent persistent, int fieldIndex);
  
  /**
   * Sets the field as readable.
   * @param fieldIndex the offset of the field in the object
   */
  void setReadable(Persistent persistent, int fieldIndex);

  /**
   * Clears the field as readable.
   * @param fieldIndex the offset of the field in the object
   */
  void clearReadable(Persistent persistent, int fieldIndex);
  
  /**
   * Clears the readable state.
   */
  void clearReadable(Persistent persistent);
  
}