/**
 * Redistribution and use of this software and associated documentation ("Software"), with or
 * without modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright statements and notices. Redistributions
 * must also contain a copy of this document.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
 * conditions and the following disclaimer in the documentation and/or other materials provided with
 * the distribution.
 *
 * 3. The name "Exolab" must not be used to endorse or promote products derived from this Software
 * without prior written permission of Intalio, Inc. For written permission, please contact
 * info@exolab.org.
 *
 * 4. Products derived from this Software may not be called "Exolab" nor may "Exolab" appear in
 * their names without prior written permission of Intalio, Inc. Exolab is a registered trademark of
 * Intalio, Inc.
 *
 * 5. Due credit should be given to the Exolab Project (http://www.exolab.org/).
 *
 * THIS SOFTWARE IS PROVIDED BY INTALIO, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESSED OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INTALIO, INC. OR ITS
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
 * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Copyright 1999 (C) Intalio, Inc. All Rights Reserved.
 *
 * $Id$
 */

package org.exolab.castor.mapping;

/**
 * A field handler knows how to perform various operations on the field that require access to the
 * field value.
 * 
 * @author <a href="arkin@intalio.com">Assaf Arkin</a>
 * @version $Revision$ $Date: 2003-03-03 00:05:44 -0700 (Mon, 03 Mar 2003) $
 * @see FieldDescriptor
 */
public interface FieldHandler<T> {

  /**
   * Returns the value of the field from the object.
   * 
   * @param object The object
   * @return The value of the field
   * @throws IllegalStateException The Java object has changed and is no longer supported by this
   *         handler, or the handler is not compatible with the Java object
   */
  public T getValue(Object object) throws IllegalStateException;

  /**
   * Sets the value of the field on the object.
   * 
   * @param object The object.
   * @param value The new value.
   * @throws IllegalStateException The Java object has changed and is no longer supported by this
   *         handler, or the handler is not compatible with the Java object.
   * @throws IllegalArgumentException The value passed is not of a supported type.
   */
  public void setValue(Object object, T value)
      throws IllegalStateException, IllegalArgumentException;

  /**
   * Sets the value of the field to a default value.
   * <p>
   * Reference fields are set to null, primitive fields are set to their default value, collection
   * fields are emptied of all elements.
   * 
   * @param object The object.
   * @throws IllegalStateException The Java object has changed and is no longer supported by this
   *         handler, or the handler is not compatible with the Java object.
   */
  public void resetValue(Object object) throws IllegalStateException, IllegalArgumentException;

  /**
   * @deprecated No longer supported
   */
  public void checkValidity(Object object) throws ValidityException, IllegalStateException;

  /**
   * Creates a new instance of the object described by this field.
   * 
   * @param parent The object for which the field is created
   * @return A new instance of the field's value
   * @throws IllegalStateException This field is a simple type and cannot be instantiated
   */
  public T newInstance(Object parent) throws IllegalStateException;

}
