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: /*
michael@0:  * nsStubMutationObserver is an implementation of the nsIMutationObserver
michael@0:  * interface (except for the methods on nsISupports) that is intended to be
michael@0:  * used as a base class within the content/layout library.  All methods do
michael@0:  * nothing.
michael@0:  */
michael@0: 
michael@0: #ifndef nsStubMutationObserver_h_
michael@0: #define nsStubMutationObserver_h_
michael@0: 
michael@0: #include "nsIMutationObserver.h"
michael@0: 
michael@0: /**
michael@0:  * There are two advantages to inheriting from nsStubMutationObserver
michael@0:  * rather than directly from nsIMutationObserver:
michael@0:  *  1. smaller compiled code size (since there's no need for the code
michael@0:  *     for the empty virtual function implementations for every
michael@0:  *     nsIMutationObserver implementation)
michael@0:  *  2. the performance of document's loop over observers benefits from
michael@0:  *     the fact that more of the functions called are the same (which
michael@0:  *     can reduce instruction cache misses and perhaps improve branch
michael@0:  *     prediction)
michael@0:  */
michael@0: class nsStubMutationObserver : public nsIMutationObserver {
michael@0: public:
michael@0:   NS_DECL_NSIMUTATIONOBSERVER
michael@0: };
michael@0: 
michael@0: #endif /* !defined(nsStubMutationObserver_h_) */