michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "nsISupports.idl"
michael@0: 
michael@0: /*
michael@0:  * The nsITransaction interface.
michael@0:  * <P>
michael@0:  * This interface is implemented by an object that needs to
michael@0:  * execute some behavior that must be tracked by the transaction manager.
michael@0:  */
michael@0: [scriptable, uuid(58e330c1-7b48-11d2-98b9-00805f297d89)]
michael@0: interface nsITransaction : nsISupports
michael@0: {
michael@0:   /**
michael@0:    * Executes the transaction.
michael@0:    */
michael@0:   void doTransaction();
michael@0: 
michael@0:   /**
michael@0:    * Restores the state to what it was before the transaction was executed.
michael@0:    */
michael@0:   void undoTransaction();
michael@0: 
michael@0:   /**
michael@0:    * Executes the transaction again. Can only be called on a transaction that
michael@0:    * was previously undone.
michael@0:    * <P>
michael@0:    * In most cases, the redoTransaction() method will actually call the
michael@0:    * doTransaction() method to execute the transaction again.
michael@0:    */
michael@0:   void redoTransaction();
michael@0: 
michael@0:   /**
michael@0:    * The transaction's transient state. This attribute is checked by
michael@0:    * the transaction manager after the transaction's Execute() method is called.
michael@0:    * If the transient state is false, a reference to the transaction is
michael@0:    * held by the transaction manager so that the transactions' undoTransaction()
michael@0:    * and redoTransaction() methods can be called. If the transient state is
michael@0:    * true, the transaction manager returns immediately after the transaction's
michael@0:    * doTransaction() method is called, no references to the transaction are
michael@0:    * maintained. Transient transactions cannot be undone or redone by the
michael@0:    * transaction manager.
michael@0:    */
michael@0:   readonly attribute boolean isTransient;
michael@0: 
michael@0:   /**
michael@0:    * Attempts to merge a transaction into "this" transaction. Both transactions
michael@0:    * must be in their undo state, doTransaction() methods already called. The
michael@0:    * transaction manager calls this method to coalesce a new transaction with
michael@0:    * the transaction on the top of the undo stack.
michael@0:    * This method returns a boolean value that indicates the merge result.
michael@0:    * A true value indicates that the transactions were merged successfully,
michael@0:    * a false value if the merge was not possible or failed. If true,
michael@0:    * the transaction manager will Release() the new transacton instead of
michael@0:    * pushing it on the undo stack.
michael@0:    * @param aTransaction the previously executed transaction to merge.
michael@0:    */
michael@0:   boolean merge(in nsITransaction aTransaction);
michael@0: };
michael@0: