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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/*
* nsStubMutationObserver is an implementation of the nsIMutationObserver
* interface (except for the methods on nsISupports) that is intended to be
* used as a base class within the content/layout library. All methods do
* nothing.
*/
#ifndef nsStubMutationObserver_h_
#define nsStubMutationObserver_h_
#include "nsTHashMap.h"
#include "nsIMutationObserver.h"
/**
* There are two advantages to inheriting from nsStubMutationObserver
* rather than directly from nsIMutationObserver:
* 1. smaller compiled code size (since there's no need for the code
* for the empty virtual function implementations for every
* nsIMutationObserver implementation)
* 2. the performance of document's loop over observers benefits from
* the fact that more of the functions called are the same (which
* can reduce instruction cache misses and perhaps improve branch
* prediction)
*/
class nsStubMutationObserver : public nsIMutationObserver {
public:
NS_DECL_NSIMUTATIONOBSERVER
};
class MutationObserverWrapper;
/**
* @brief Base class for MutationObservers that are used by multiple nodes.
*
* Mutation Observers are stored inside of a nsINode using a DoublyLinkedList,
* restricting the number of nodes a mutation observer can be inserted to one.
*
* To allow a mutation observer to be used by several nodes, this class
* provides a MutationObserverWrapper which implements the nsIMutationObserver
* interface and forwards all method calls to this class. For each node this
* mutation observer will be used for, a wrapper object is created.
*/
class nsMultiMutationObserver : public nsIMutationObserver {
public:
/**
* Adds the mutation observer to aNode by creating a MutationObserverWrapper
* and inserting it into aNode.
* Does nothing if there already is a mutation observer for aNode.
*/
void AddMutationObserverToNode(nsINode* aNode);
/**
* Removes the mutation observer from aNode.
* Does nothing if there is no mutation observer for aNode.
*/
void RemoveMutationObserverFromNode(nsINode* aNode);
/**
* Returns true if there is already a mutation observer for aNode.
*/
bool ContainsNode(const nsINode* aNode) const;
private:
friend class MutationObserverWrapper;
nsTHashMap<nsINode*, MutationObserverWrapper*> mWrapperForNode;
};
/**
* Convenience class that provides support for multiple nodes and has
* default implementations for nsIMutationObserver.
*/
class nsStubMultiMutationObserver : public nsMultiMutationObserver {
public:
NS_DECL_NSIMUTATIONOBSERVER
};
#endif /* !defined(nsStubMutationObserver_h_) */
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