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