/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#include "nsISupports.idl"

/**
 * Used to enumerate over elements defined by its implementor.
 * Although hasMoreElements() can be called independently of getNext(),
 * getNext() must be pre-ceeded by a call to hasMoreElements(). There is
 * no way to "reset" an enumerator, once you obtain one.
 *
 * @version 1.0
 */

[scriptable, uuid(D1899240-F9D2-11D2-BDD6-000064657374)]
interface nsISimpleEnumerator : nsISupports {
  /**
   * Called to determine whether or not the enumerator has
   * any elements that can be returned via getNext(). This method
   * is generally used to determine whether or not to initiate or
   * continue iteration over the enumerator, though it can be
   * called without subsequent getNext() calls. Does not affect
   * internal state of enumerator.
   *
   * @see getNext()
   * @return PR_TRUE if there are remaining elements in the enumerator.
   *         PR_FALSE if there are no more elements in the enumerator.
   */                                            
  boolean hasMoreElements();

  /**
   * Called to retrieve the next element in the enumerator. The "next"
   * element is the first element upon the first call. Must be
   * pre-ceeded by a call to hasMoreElements() which returns PR_TRUE.
   * This method is generally called within a loop to iterate over
   * the elements in the enumerator.
   *
   * @see hasMoreElements()
   * @return NS_OK if the call succeeded in returning a non-null
   *               value through the out parameter.
   *         NS_ERROR_FAILURE if there are no more elements
   *                          to enumerate.
   * @return the next element in the enumeration.
   */
  nsISupports getNext();
};
