gecko-dev/dom/base/nsChildContentList.h

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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/. */
#ifndef nsChildContentList_h__
#define nsChildContentList_h__
#include "nsISupportsImpl.h"
#include "nsINodeList.h" // base class
#include "js/TypeDecls.h" // for Handle, Value, JSObject, JSContext
class nsIContent;
class nsINode;
/**
* Class that implements the nsINodeList interface (a list of children of
* the content), by holding a reference to the content and delegating Length
* and Item to its existing child list.
* @see nsINodeList
*/
class nsAttrChildContentList : public nsINodeList {
public:
explicit nsAttrChildContentList(nsINode* aNode) : mNode(aNode) {}
NS_DECL_CYCLE_COLLECTING_ISUPPORTS
NS_DECL_CYCLE_COLLECTION_SKIPPABLE_SCRIPT_HOLDER_CLASS(nsAttrChildContentList)
// nsWrapperCache
virtual JSObject* WrapObject(JSContext* cx,
JS::Handle<JSObject*> aGivenProto) override;
// nsINodeList interface
virtual int32_t IndexOf(nsIContent* aContent) override;
virtual nsIContent* Item(uint32_t aIndex) override;
uint32_t Length() override;
virtual void DropReference() { mNode = nullptr; }
virtual nsINode* GetParentObject() override { return mNode; }
protected:
virtual ~nsAttrChildContentList() {}
private:
// The node whose children make up the list.
// This is a non-owning ref which is safe because it's set to nullptr by
// DropReference() by the node slots get destroyed.
nsINode* MOZ_NON_OWNING_REF mNode;
};
class nsParentNodeChildContentList final : public nsAttrChildContentList {
public:
explicit nsParentNodeChildContentList(nsINode* aNode)
: nsAttrChildContentList(aNode), mIsCacheValid(false) {
ValidateCache();
}
// nsINodeList interface
virtual int32_t IndexOf(nsIContent* aContent) override;
virtual nsIContent* Item(uint32_t aIndex) override;
uint32_t Length() override;
void DropReference() override {
InvalidateCache();
nsAttrChildContentList::DropReference();
}
void InvalidateCache() {
mIsCacheValid = false;
mCachedChildArray.Clear();
}
private:
~nsParentNodeChildContentList() {}
// Return true if validation succeeds, false otherwise
bool ValidateCache();
// Whether cached array of child nodes is valid
bool mIsCacheValid;
// Cached array of child nodes
AutoTArray<nsIContent*, 8> mCachedChildArray;
};
#endif /* nsChildContentList_h__ */