content: /*
   * This library is part of OpenCms -
   * the Open Source Content Management System
   *
   * Copyright (c) Alkacon Software GmbH & Co. KG (https://www.alkacon.com)
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * This library 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
   * Lesser General Public License for more details.
   *
   * For further information about Alkacon Software, please see the
   * company website: https://www.alkacon.com
   *
   * For further information about OpenCms, please see the
   * project website: https://www.opencms.org
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  
  package org.opencms.gwt.client.util;
  
  /**
   * Container which contains at most one {@link org.opencms.gwt.client.util.I_CmsUniqueActiveItem}.<p>
   *
   * If a new value is set while this container already contains an item, the previous item is removed and notified of that removal.<p>
   */
  public class CmsUniqueActiveItemContainer {
  
      /** The current item. */
      private I_CmsUniqueActiveItem m_activeItem;
  
      /**
       * Removes the current item.
       */
      public void clear() {
  
          if (m_activeItem != null) {
              m_activeItem.onDeactivate();
              m_activeItem = null;
          }
      }
  
      /**
       * Removes the current item only if it is the same object as the given parameter.<p>
       *
       * @param item the item to match
       */
      public void clearIfMatches(I_CmsUniqueActiveItem item) {
  
          if (item == m_activeItem) {
              clear();
          }
      }
  
      /**
       * Sets the active item.<p>
       *
       * If this container already contains an item, it is replaced with the given item, and its onDeactivate() method is called.<p>
       *
       * @param item the new item
       */
      public void setActiveItem(I_CmsUniqueActiveItem item) {
  
          clear();
          if (item != null) {
              m_activeItem = item;
          }
      }
  
  }
  