gecko-dev/editor/txmgr/public/nsITransaction.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* The contents of this file are subject to the Netscape Public License
* Version 1.0 (the "NPL"); you may not use this file except in
* compliance with the NPL. You may obtain a copy of the NPL at
* http://www.mozilla.org/NPL/
*
* Software distributed under the NPL is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
* for the specific language governing rights and limitations under the
* NPL.
*
* The Initial Developer of this code under the NPL is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 1998 Netscape Communications Corporation. All Rights
* Reserved.
*/
#ifndef nsITransaction_h__
#define nsITransaction_h__
#include "nsISupports.h"
#include "nsIOutputStream.h"
#include "nsString.h"
/*
Transaction interface to outside world
*/
#define NS_ITRANSACTION_IID \
{ /* 58E330C1-7B48-11d2-98B9-00805F297D89 */ \
0x58e330c1, 0x7b48, 0x11d2, \
{ 0x98, 0xb9, 0x0, 0x80, 0x5f, 0x29, 0x7d, 0x89 } }
/**
* A transaction specific interface.
* <P>
* It's implemented by an object that executes some behavior that must be
* tracked by the transaction manager.
*/
class nsITransaction : public nsISupports{
public:
static const nsIID& GetIID() { static nsIID iid = NS_ITRANSACTION_IID; return iid; }
/**
* Executes the transaction.
*/
NS_IMETHOD Do(void) = 0;
/**
* Restores the state to what it was before the transaction was executed.
*/
NS_IMETHOD Undo(void) = 0;
/**
* Executes the transaction again. Can only be called on a transaction that
* was previously undone.
* <P>
* In most cases, the Redo() method will actually call the Do() method to
* execute the transaction again.
*/
NS_IMETHOD Redo(void) = 0;
/**
* Retrieves the transaction's transient state. This method is called by
* the transaction manager after the transaction's Do() method is executed.
* If the transient state is false, a reference to the transaction is
* held by the transaction manager so that the transactions' Undo() and
* Redo() methods can be called. If the transient state is true, the
* transaction manager returns immediately after the transaction's Do()
* method is executed, no references to the transaction are maintained.
* Transient transactions cannot be undone or redone by the transaction
* manager.
* @param aIsTransient will contain the transaction's transient state.
*/
NS_IMETHOD GetIsTransient(PRBool *aIsTransient) = 0;
/**
* Attempts to merge a transaction into "this" transaction. Both transactions
* must be in their undo state, Do() methods already executed. The transaction
* manager calls this method to coalesce a new transaction with the
* transaction on the top of the undo stack.
* @param aDidMerge will contain merge result. True if transactions were
* merged successfully. False if merge is not possible or failed. If true,
* the transaction manager will Release() the new transacton instead of
* pushing it on the undo stack.
* @param aTransaction the previously executed transaction to merge.
*/
NS_IMETHOD Merge(PRBool *aDidMerge, nsITransaction *aTransaction) = 0;
/**
* Write a stream representation of the current state of the transaction.
* @param aOutputStream the stream to write to.
*/
NS_IMETHOD Write(nsIOutputStream *aOutputStream) = 0;
/**
* Returns the string to display for the undo menu item.
* @param aString will point to string to display.
*/
NS_IMETHOD GetUndoString(nsString **aString) = 0;
/**
* Returns the string to display for the redo menu item.
* @param aString will point to string to display.
*/
NS_IMETHOD GetRedoString(nsString **aString) = 0;
};
#endif // nsITransaction_h__