/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** 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"
interface nsITransaction;

/*
 * The nsITransactionList interface.
 * <P>
 * The implementation for this interface is provided by the Transaction Manager.
 * This interface provides a mechanism for accessing the transactions on the
 * Undo or Redo stacks as well as any auto-aggregated children that a
 * transaction may have.
 */
[scriptable, uuid(97f863f3-f886-11d4-9d39-0060b0f8baff)]

interface nsITransactionList : nsISupports
{
  /**
   * The number of transactions contained in this list.
   */
  readonly attribute long numItems;

  /**
   * itemIsBatch() returns true if the item at aIndex is a batch. Note that
   * currently there is no requirement for a TransactionManager implementation
   * to associate a toplevel nsITransaction with a batch so it is possible for
   * itemIsBatch() to return true and getItem() to return null. However, you
   * can still access the transactions contained in the batch with a call to
   * getChildListForItem().
   * @param aIndex The index of the item in the list.
   */
  boolean itemIsBatch(in long aIndex);

  /**
   * getItem() returns the transaction at the given index in the list. Note that
   * a null can be returned here if the item is a batch. The transaction
   * returned is AddRef'd so it is up to the caller to Release the transaction
   * when it is done.
   * @param aIndex The index of the item in the list.
   */
  nsITransaction getItem(in long aIndex);

  /**
   * getNumChildrenForItem() returns the number of child (auto-aggreated)
   * transactions the item at aIndex has.
   * @param aIndex The index of the item in the list.
   */
  long getNumChildrenForItem(in long aIndex);

  /**
   * getChildListForItem() returns the list of children associated with the
   * item at aIndex. Implementations may return null if there are no children,
   * or an empty list. The list returned is AddRef'd so it is up to the caller
   * to Release the transaction when it is done.
   * @param aIndex The index of the item in the list.
   */
  nsITransactionList getChildListForItem(in long aIndex);
};