/**
* Copyright (c) 2002-2010 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.util;
/**
* This interface is used when dealing with a one-to-one relationship
* between two objects (nodes).
* @param <T> the type of objects on both sides of this link.
*/
public interface Link<T>
{
/**
* @return the object on the other side of this link. If there's no
* object connected null will be returned.
*/
T get();
/**
* Sets {@code entity} to be the object on the other side of this link.
* If there's already a link to another object it will be removed first.
* @param object the object on the other side of this link.
* @return the previously set object or null if there was no previous
* object set.
*/
T set( T object );
/**
* Removes the link if one is set.
* @return the removed object or null if no object was set.
*/
T remove();
/**
* @return {@code true} if there's a link to another object.
*/
boolean has();
}