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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 */
* A unique per-element set of attributes that is used as an
* nsIStyleRule; used to implement presentational attributes.
#ifndef nsMappedAttributes_h___
#define nsMappedAttributes_h___
#include "AttrArray.h"
#include "nsMappedAttributeElement.h"
#include "mozilla/Attributes.h"
#include "mozilla/ServoBindingTypes.h"
#include "mozilla/MemoryReporting.h"
class nsAtom;
class nsHTMLStyleSheet;
class nsMappedAttributes final {
using InternalAttr = AttrArray::InternalAttr;
nsMappedAttributes(nsHTMLStyleSheet* aSheet,
nsMapRuleToAttributesFunc aMapRuleFunc);
// Do not return null.
void* operator new(size_t size, uint32_t aAttrCount = 1) noexcept(true);
nsMappedAttributes* Clone(bool aWillAddAttr);
void SetAndSwapAttr(nsAtom* aAttrName, nsAttrValue& aValue,
bool* aValueWasSet);
const nsAttrValue* GetAttr(const nsAtom* aAttrName) const;
const nsAttrValue* GetAttr(const nsAString& aAttrName) const;
uint32_t Count() const { return mAttrCount; }
bool Equals(const nsMappedAttributes* aAttributes) const;
PLDHashNumber HashValue() const;
void DropStyleSheetReference() { mSheet = nullptr; }
void SetStyleSheet(nsHTMLStyleSheet* aSheet);
nsHTMLStyleSheet* GetStyleSheet() { return mSheet; }
void SetRuleMapper(nsMapRuleToAttributesFunc aRuleMapper) {
mRuleMapper = aRuleMapper;
auto Attrs() const {
return mozilla::Span<const InternalAttr>{mBuffer, mAttrCount};
auto Attrs() { return mozilla::Span<InternalAttr>{mBuffer, mAttrCount}; }
const nsAttrName* NameAt(uint32_t aPos) const {
NS_ASSERTION(aPos < mAttrCount, "out-of-bounds");
return &Attrs()[aPos].mName;
const nsAttrValue* AttrAt(uint32_t aPos) const {
NS_ASSERTION(aPos < mAttrCount, "out-of-bounds");
return &Attrs()[aPos].mValue;
// Remove the attr at position aPos. The value of the attr is placed in
// aValue; any value that was already in aValue is destroyed.
void RemoveAttrAt(uint32_t aPos, nsAttrValue& aValue);
const nsAttrName* GetExistingAttrNameFromQName(const nsAString& aName) const;
int32_t IndexOfAttr(const nsAtom* aLocalName) const;
// Apply the contained mapper to the contained set of servo rules,
// unless the servo rules have already been initialized.
void LazilyResolveServoDeclaration(mozilla::dom::Document* aDocument);
// Obtain the contained servo declaration block
// May return null if called before the inner block
// has been (lazily) resolved
const RefPtr<RawServoDeclarationBlock>& GetServoStyle() const {
return mServoStyle;
void ClearServoStyle() {
mServoStyle = nullptr;
size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
static void Shutdown();
void LastRelease();
nsMappedAttributes(const nsMappedAttributes& aCopy);
uint16_t mAttrCount;
#ifdef DEBUG
uint16_t mBufferSize;
nsHTMLStyleSheet* mSheet; // weak
nsMapRuleToAttributesFunc mRuleMapper;
RefPtr<RawServoDeclarationBlock> mServoStyle;
InternalAttr mBuffer[0];
static bool sShuttingDown;
// We're caching some memory to avoid trashing the allocator.
// The memory stored at index N can hold N attribute values.
static nsTArray<void*>* sCachedMappedAttributeAllocations;
#endif /* nsMappedAttributes_h___ */